socket.c

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/* SCTP kernel implementation
 * (C) Copyright IBM Corp. 2001, 2004
 * Copyright (c) 1999-2000 Cisco, Inc.
 * Copyright (c) 1999-2001 Motorola, Inc.
 * Copyright (c) 2001-2003 Intel Corp.
 * Copyright (c) 2001-2002 Nokia, Inc.
 * Copyright (c) 2001 La Monte H.P. Yarroll
 *
 * This file is part of the SCTP kernel implementation
 *
 * These functions interface with the sockets layer to implement the
 * SCTP Extensions for the Sockets API.
 *
 * Note that the descriptions from the specification are USER level
 * functions--this file is the functions which populate the struct proto
 * for SCTP which is the BOTTOM of the sockets interface.
 *
 * This SCTP implementation is free software;
 * you can redistribute it and/or modify it under the terms of
 * the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * This SCTP implementation is distributed in the hope that it
 * will be useful, but WITHOUT ANY WARRANTY; without even the implied
 *                 ************************
 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with GNU CC; see the file COPYING.  If not, write to
 * the Free Software Foundation, 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 *
 * Please send any bug reports or fixes you make to the
 * email address(es):
 *    lksctp developers <[email protected]>
 *
 * Or submit a bug report through the following website:
 *    http://www.sf.net/projects/lksctp
 *
 * Written or modified by:
 *    La Monte H.P. Yarroll <[email protected]>
 *    Narasimha Budihal     <[email protected]>
 *    Karl Knutson          <[email protected]>
 *    Jon Grimm             <[email protected]>
 *    Xingang Guo           <[email protected]>
 *    Daisy Chang           <[email protected]>
 *    Sridhar Samudrala     <[email protected]>
 *    Inaky Perez-Gonzalez  <[email protected]>
 *    Ardelle Fan       <[email protected]>
 *    Ryan Layer        <[email protected]>
 *    Anup Pemmaiah         <[email protected]>
 *    Kevin Gao             <[email protected]>
 *
 * Any bugs reported given to us we will try to fix... any fixes shared will
 * be incorporated into the next SCTP release.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/wait.h>
#include <linux/time.h>
#include <linux/ip.h>
#include <linux/capability.h>
#include <linux/fcntl.h>
#include <linux/poll.h>
#include <linux/init.h>
#include <linux/crypto.h>
#include <linux/slab.h>
#include <linux/file.h>

#include <net/ip.h>
#include <net/icmp.h>
#include <net/route.h>
#include <net/ipv6.h>
#include <net/inet_common.h>

#include <linux/socket.h> /* for sa_family_t */
#include <linux/export.h>
#include <net/sock.h>
#include <net/sctp/sctp.h>
#include <net/sctp/sm.h>

/* WARNING:  Please do not remove the SCTP_STATIC attribute to
 * any of the functions below as they are used to export functions
 * used by a project regression testsuite.
 */

/* Forward declarations for internal helper functions. */
static int sctp_writeable(struct sock *sk);
static void sctp_wfree(struct sk_buff *skb);
static int sctp_wait_for_sndbuf(struct sctp_association *, long *timeo_p,
                size_t msg_len);
static int sctp_wait_for_packet(struct sock * sk, int *err, long *timeo_p);
static int sctp_wait_for_connect(struct sctp_association *, long *timeo_p);
static int sctp_wait_for_accept(struct sock *sk, long timeo);
static void sctp_wait_for_close(struct sock *sk, long timeo);
static struct sctp_af *sctp_sockaddr_af(struct sctp_sock *opt,
                    union sctp_addr *addr, int len);
static int sctp_bindx_add(struct sock *, struct sockaddr *, int);
static int sctp_bindx_rem(struct sock *, struct sockaddr *, int);
static int sctp_send_asconf_add_ip(struct sock *, struct sockaddr *, int);
static int sctp_send_asconf_del_ip(struct sock *, struct sockaddr *, int);
static int sctp_send_asconf(struct sctp_association *asoc,
                struct sctp_chunk *chunk);
static int sctp_do_bind(struct sock *, union sctp_addr *, int);
static int sctp_autobind(struct sock *sk);
static void sctp_sock_migrate(struct sock *, struct sock *,
                  struct sctp_association *, sctp_socket_type_t);
static char *sctp_hmac_alg = SCTP_COOKIE_HMAC_ALG;

extern struct kmem_cache *sctp_bucket_cachep;
extern long sysctl_sctp_mem[3];
extern int sysctl_sctp_rmem[3];
extern int sysctl_sctp_wmem[3];

static int sctp_memory_pressure;
static atomic_long_t sctp_memory_allocated;
struct percpu_counter sctp_sockets_allocated;

static void sctp_enter_memory_pressure(struct sock *sk)
{
    sctp_memory_pressure = 1;
}


/* Get the sndbuf space available at the time on the association.  */
static inline int sctp_wspace(struct sctp_association *asoc)
{
    int amt;

    if (asoc->ep->sndbuf_policy)
        amt = asoc->sndbuf_used;
    else
        amt = sk_wmem_alloc_get(asoc->base.sk);

    if (amt >= asoc->base.sk->sk_sndbuf) {
        if (asoc->base.sk->sk_userlocks & SOCK_SNDBUF_LOCK)
            amt = 0;
        else {
            amt = sk_stream_wspace(asoc->base.sk);
            if (amt < 0)
                amt = 0;
        }
    } else {
        amt = asoc->base.sk->sk_sndbuf - amt;
    }
    return amt;
}

/* Increment the used sndbuf space count of the corresponding association by
 * the size of the outgoing data chunk.
 * Also, set the skb destructor for sndbuf accounting later.
 *
 * Since it is always 1-1 between chunk and skb, and also a new skb is always
 * allocated for chunk bundling in sctp_packet_transmit(), we can use the
 * destructor in the data chunk skb for the purpose of the sndbuf space
 * tracking.
 */
static inline void sctp_set_owner_w(struct sctp_chunk *chunk)
{
    struct sctp_association *asoc = chunk->asoc;
    struct sock *sk = asoc->base.sk;

    /* The sndbuf space is tracked per association.  */
    sctp_association_hold(asoc);

    skb_set_owner_w(chunk->skb, sk);

    chunk->skb->destructor = sctp_wfree;
    /* Save the chunk pointer in skb for sctp_wfree to use later.  */
    *((struct sctp_chunk **)(chunk->skb->cb)) = chunk;

    asoc->sndbuf_used += SCTP_DATA_SNDSIZE(chunk) +
                sizeof(struct sk_buff) +
                sizeof(struct sctp_chunk);

    atomic_add(sizeof(struct sctp_chunk), &sk->sk_wmem_alloc);
    sk->sk_wmem_queued += chunk->skb->truesize;
    sk_mem_charge(sk, chunk->skb->truesize);
}

/* Verify that this is a valid address. */
static inline int sctp_verify_addr(struct sock *sk, union sctp_addr *addr,
                   int len)
{
    struct sctp_af *af;

    /* Verify basic sockaddr. */
    af = sctp_sockaddr_af(sctp_sk(sk), addr, len);
    if (!af)
        return -EINVAL;

    /* Is this a valid SCTP address?  */
    if (!af->addr_valid(addr, sctp_sk(sk), NULL))
        return -EINVAL;

    if (!sctp_sk(sk)->pf->send_verify(sctp_sk(sk), (addr)))
        return -EINVAL;

    return 0;
}

/* Look up the association by its id.  If this is not a UDP-style
 * socket, the ID field is always ignored.
 */
struct sctp_association *sctp_id2assoc(struct sock *sk, sctp_assoc_t id)
{
    struct sctp_association *asoc = NULL;

    /* If this is not a UDP-style socket, assoc id should be ignored. */
    if (!sctp_style(sk, UDP)) {
        /* Return NULL if the socket state is not ESTABLISHED. It
         * could be a TCP-style listening socket or a socket which
         * hasn't yet called connect() to establish an association.
         */
        if (!sctp_sstate(sk, ESTABLISHED))
            return NULL;

        /* Get the first and the only association from the list. */
        if (!list_empty(&sctp_sk(sk)->ep->asocs))
            asoc = list_entry(sctp_sk(sk)->ep->asocs.next,
                      struct sctp_association, asocs);
        return asoc;
    }

    /* Otherwise this is a UDP-style socket. */
    if (!id || (id == (sctp_assoc_t)-1))
        return NULL;

    spin_lock_bh(&sctp_assocs_id_lock);
    asoc = (struct sctp_association *)idr_find(&sctp_assocs_id, (int)id);
    spin_unlock_bh(&sctp_assocs_id_lock);

    if (!asoc || (asoc->base.sk != sk) || asoc->base.dead)
        return NULL;

    return asoc;
}

/* Look up the transport from an address and an assoc id. If both address and
 * id are specified, the associations matching the address and the id should be
 * the same.
 */
static struct sctp_transport *sctp_addr_id2transport(struct sock *sk,
                          struct sockaddr_storage *addr,
                          sctp_assoc_t id)
{
    struct sctp_association *addr_asoc = NULL, *id_asoc = NULL;
    struct sctp_transport *transport;
    union sctp_addr *laddr = (union sctp_addr *)addr;

    addr_asoc = sctp_endpoint_lookup_assoc(sctp_sk(sk)->ep,
                           laddr,
                           &transport);

    if (!addr_asoc)
        return NULL;

    id_asoc = sctp_id2assoc(sk, id);
    if (id_asoc && (id_asoc != addr_asoc))
        return NULL;

    sctp_get_pf_specific(sk->sk_family)->addr_v4map(sctp_sk(sk),
                        (union sctp_addr *)addr);

    return transport;
}

/* API 3.1.2 bind() - UDP Style Syntax
 * The syntax of bind() is,
 *
 *   ret = bind(int sd, struct sockaddr *addr, int addrlen);
 *
 *   sd      - the socket descriptor returned by socket().
 *   addr    - the address structure (struct sockaddr_in or struct
 *             sockaddr_in6 [RFC 2553]),
 *   addr_len - the size of the address structure.
 */
SCTP_STATIC int sctp_bind(struct sock *sk, struct sockaddr *addr, int addr_len)
{
    int retval = 0;

    sctp_lock_sock(sk);

    SCTP_DEBUG_PRINTK("sctp_bind(sk: %p, addr: %p, addr_len: %d)\n",
              sk, addr, addr_len);

    /* Disallow binding twice. */
    if (!sctp_sk(sk)->ep->base.bind_addr.port)
        retval = sctp_do_bind(sk, (union sctp_addr *)addr,
                      addr_len);
    else
        retval = -EINVAL;

    sctp_release_sock(sk);

    return retval;
}

static long sctp_get_port_local(struct sock *, union sctp_addr *);

/* Verify this is a valid sockaddr. */
static struct sctp_af *sctp_sockaddr_af(struct sctp_sock *opt,
                    union sctp_addr *addr, int len)
{
    struct sctp_af *af;

    /* Check minimum size.  */
    if (len < sizeof (struct sockaddr))
        return NULL;

    /* V4 mapped address are really of AF_INET family */
    if (addr->sa.sa_family == AF_INET6 &&
        ipv6_addr_v4mapped(&addr->v6.sin6_addr)) {
        if (!opt->pf->af_supported(AF_INET, opt))
            return NULL;
    } else {
        /* Does this PF support this AF? */
        if (!opt->pf->af_supported(addr->sa.sa_family, opt))
            return NULL;
    }

    /* If we get this far, af is valid. */
    af = sctp_get_af_specific(addr->sa.sa_family);

    if (len < af->sockaddr_len)
        return NULL;

    return af;
}

/* Bind a local address either to an endpoint or to an association.  */
SCTP_STATIC int sctp_do_bind(struct sock *sk, union sctp_addr *addr, int len)
{
    struct sctp_sock *sp = sctp_sk(sk);
    struct sctp_endpoint *ep = sp->ep;
    struct sctp_bind_addr *bp = &ep->base.bind_addr;
    struct sctp_af *af;
    unsigned short snum;
    int ret = 0;

    /* Common sockaddr verification. */
    af = sctp_sockaddr_af(sp, addr, len);
    if (!af) {
        SCTP_DEBUG_PRINTK("sctp_do_bind(sk: %p, newaddr: %p, len: %d) EINVAL\n",
                  sk, addr, len);
        return -EINVAL;
    }

    snum = ntohs(addr->v4.sin_port);

    SCTP_DEBUG_PRINTK_IPADDR("sctp_do_bind(sk: %p, new addr: ",
                 ", port: %d, new port: %d, len: %d)\n",
                 sk,
                 addr,
                 bp->port, snum,
                 len);

    /* PF specific bind() address verification. */
    if (!sp->pf->bind_verify(sp, addr))
        return -EADDRNOTAVAIL;

    /* We must either be unbound, or bind to the same port.
     * It's OK to allow 0 ports if we are already bound.
     * We'll just inhert an already bound port in this case
     */
    if (bp->port) {
        if (!snum)
            snum = bp->port;
        else if (snum != bp->port) {
            SCTP_DEBUG_PRINTK("sctp_do_bind:"
                  " New port %d does not match existing port "
                  "%d.\n", snum, bp->port);
            return -EINVAL;
        }
    }

    if (snum && snum < PROT_SOCK && !capable(CAP_NET_BIND_SERVICE))
        return -EACCES;

    /* See if the address matches any of the addresses we may have
     * already bound before checking against other endpoints.
     */
    if (sctp_bind_addr_match(bp, addr, sp))
        return -EINVAL;

    /* Make sure we are allowed to bind here.
     * The function sctp_get_port_local() does duplicate address
     * detection.
     */
    addr->v4.sin_port = htons(snum);
    if ((ret = sctp_get_port_local(sk, addr))) {
        return -EADDRINUSE;
    }

    /* Refresh ephemeral port.  */
    if (!bp->port)
        bp->port = inet_sk(sk)->inet_num;

    /* Add the address to the bind address list.
     * Use GFP_ATOMIC since BHs will be disabled.
     */
    ret = sctp_add_bind_addr(bp, addr, SCTP_ADDR_SRC, GFP_ATOMIC);

    /* Copy back into socket for getsockname() use. */
    if (!ret) {
        inet_sk(sk)->inet_sport = htons(inet_sk(sk)->inet_num);
        af->to_sk_saddr(addr, sk);
    }

    return ret;
}

 /* ADDIP Section 4.1.1 Congestion Control of ASCONF Chunks
 *
 * R1) One and only one ASCONF Chunk MAY be in transit and unacknowledged
 * at any one time.  If a sender, after sending an ASCONF chunk, decides
 * it needs to transfer another ASCONF Chunk, it MUST wait until the
 * ASCONF-ACK Chunk returns from the previous ASCONF Chunk before sending a
 * subsequent ASCONF. Note this restriction binds each side, so at any
 * time two ASCONF may be in-transit on any given association (one sent
 * from each endpoint).
 */
static int sctp_send_asconf(struct sctp_association *asoc,
                struct sctp_chunk *chunk)
{
    struct net  *net = sock_net(asoc->base.sk);
    int     retval = 0;

    /* If there is an outstanding ASCONF chunk, queue it for later
     * transmission.
     */
    if (asoc->addip_last_asconf) {
        list_add_tail(&chunk->list, &asoc->addip_chunk_list);
        goto out;
    }

    /* Hold the chunk until an ASCONF_ACK is received. */
    sctp_chunk_hold(chunk);
    retval = sctp_primitive_ASCONF(net, asoc, chunk);
    if (retval)
        sctp_chunk_free(chunk);
    else
        asoc->addip_last_asconf = chunk;

out:
    return retval;
}

/* Add a list of addresses as bind addresses to local endpoint or
 * association.
 *
 * Basically run through each address specified in the addrs/addrcnt
 * array/length pair, determine if it is IPv6 or IPv4 and call
 * sctp_do_bind() on it.
 *
 * If any of them fails, then the operation will be reversed and the
 * ones that were added will be removed.
 *
 * Only sctp_setsockopt_bindx() is supposed to call this function.
 */
static int sctp_bindx_add(struct sock *sk, struct sockaddr *addrs, int addrcnt)
{
    int cnt;
    int retval = 0;
    void *addr_buf;
    struct sockaddr *sa_addr;
    struct sctp_af *af;

    SCTP_DEBUG_PRINTK("sctp_bindx_add (sk: %p, addrs: %p, addrcnt: %d)\n",
              sk, addrs, addrcnt);

    addr_buf = addrs;
    for (cnt = 0; cnt < addrcnt; cnt++) {
        /* The list may contain either IPv4 or IPv6 address;
         * determine the address length for walking thru the list.
         */
        sa_addr = addr_buf;
        af = sctp_get_af_specific(sa_addr->sa_family);
        if (!af) {
            retval = -EINVAL;
            goto err_bindx_add;
        }

        retval = sctp_do_bind(sk, (union sctp_addr *)sa_addr,
                      af->sockaddr_len);

        addr_buf += af->sockaddr_len;

err_bindx_add:
        if (retval < 0) {
            /* Failed. Cleanup the ones that have been added */
            if (cnt > 0)
                sctp_bindx_rem(sk, addrs, cnt);
            return retval;
        }
    }

    return retval;
}

/* Send an ASCONF chunk with Add IP address parameters to all the peers of the
 * associations that are part of the endpoint indicating that a list of local
 * addresses are added to the endpoint.
 *
 * If any of the addresses is already in the bind address list of the
 * association, we do not send the chunk for that association.  But it will not
 * affect other associations.
 *
 * Only sctp_setsockopt_bindx() is supposed to call this function.
 */
static int sctp_send_asconf_add_ip(struct sock      *sk,
                   struct sockaddr  *addrs,
                   int          addrcnt)
{
    struct net *net = sock_net(sk);
    struct sctp_sock        *sp;
    struct sctp_endpoint        *ep;
    struct sctp_association     *asoc;
    struct sctp_bind_addr       *bp;
    struct sctp_chunk       *chunk;
    struct sctp_sockaddr_entry  *laddr;
    union sctp_addr         *addr;
    union sctp_addr         saveaddr;
    void                *addr_buf;
    struct sctp_af          *af;
    struct list_head        *p;
    int                 i;
    int                 retval = 0;

    if (!net->sctp.addip_enable)
        return retval;

    sp = sctp_sk(sk);
    ep = sp->ep;

    SCTP_DEBUG_PRINTK("%s: (sk: %p, addrs: %p, addrcnt: %d)\n",
              __func__, sk, addrs, addrcnt);

    list_for_each_entry(asoc, &ep->asocs, asocs) {

        if (!asoc->peer.asconf_capable)
            continue;

        if (asoc->peer.addip_disabled_mask & SCTP_PARAM_ADD_IP)
            continue;

        if (!sctp_state(asoc, ESTABLISHED))
            continue;

        /* Check if any address in the packed array of addresses is
         * in the bind address list of the association. If so,
         * do not send the asconf chunk to its peer, but continue with
         * other associations.
         */
        addr_buf = addrs;
        for (i = 0; i < addrcnt; i++) {
            addr = addr_buf;
            af = sctp_get_af_specific(addr->v4.sin_family);
            if (!af) {
                retval = -EINVAL;
                goto out;
            }

            if (sctp_assoc_lookup_laddr(asoc, addr))
                break;

            addr_buf += af->sockaddr_len;
        }
        if (i < addrcnt)
            continue;

        /* Use the first valid address in bind addr list of
         * association as Address Parameter of ASCONF CHUNK.
         */
        bp = &asoc->base.bind_addr;
        p = bp->address_list.next;
        laddr = list_entry(p, struct sctp_sockaddr_entry, list);
        chunk = sctp_make_asconf_update_ip(asoc, &laddr->a, addrs,
                           addrcnt, SCTP_PARAM_ADD_IP);
        if (!chunk) {
            retval = -ENOMEM;
            goto out;
        }

        /* Add the new addresses to the bind address list with
         * use_as_src set to 0.
         */
        addr_buf = addrs;
        for (i = 0; i < addrcnt; i++) {
            addr = addr_buf;
            af = sctp_get_af_specific(addr->v4.sin_family);
            memcpy(&saveaddr, addr, af->sockaddr_len);
            retval = sctp_add_bind_addr(bp, &saveaddr,
                            SCTP_ADDR_NEW, GFP_ATOMIC);
            addr_buf += af->sockaddr_len;
        }
        if (asoc->src_out_of_asoc_ok) {
            struct sctp_transport *trans;

            list_for_each_entry(trans,
                &asoc->peer.transport_addr_list, transports) {
                /* Clear the source and route cache */
                dst_release(trans->dst);
                trans->cwnd = min(4*asoc->pathmtu, max_t(__u32,
                    2*asoc->pathmtu, 4380));
                trans->ssthresh = asoc->peer.i.a_rwnd;
                trans->rto = asoc->rto_initial;
                trans->rtt = trans->srtt = trans->rttvar = 0;
                sctp_transport_route(trans, NULL,
                    sctp_sk(asoc->base.sk));
            }
        }
        retval = sctp_send_asconf(asoc, chunk);
    }

out:
    return retval;
}

/* Remove a list of addresses from bind addresses list.  Do not remove the
 * last address.
 *
 * Basically run through each address specified in the addrs/addrcnt
 * array/length pair, determine if it is IPv6 or IPv4 and call
 * sctp_del_bind() on it.
 *
 * If any of them fails, then the operation will be reversed and the
 * ones that were removed will be added back.
 *
 * At least one address has to be left; if only one address is
 * available, the operation will return -EBUSY.
 *
 * Only sctp_setsockopt_bindx() is supposed to call this function.
 */
static int sctp_bindx_rem(struct sock *sk, struct sockaddr *addrs, int addrcnt)
{
    struct sctp_sock *sp = sctp_sk(sk);
    struct sctp_endpoint *ep = sp->ep;
    int cnt;
    struct sctp_bind_addr *bp = &ep->base.bind_addr;
    int retval = 0;
    void *addr_buf;
    union sctp_addr *sa_addr;
    struct sctp_af *af;

    SCTP_DEBUG_PRINTK("sctp_bindx_rem (sk: %p, addrs: %p, addrcnt: %d)\n",
              sk, addrs, addrcnt);

    addr_buf = addrs;
    for (cnt = 0; cnt < addrcnt; cnt++) {
        /* If the bind address list is empty or if there is only one
         * bind address, there is nothing more to be removed (we need
         * at least one address here).
         */
        if (list_empty(&bp->address_list) ||
            (sctp_list_single_entry(&bp->address_list))) {
            retval = -EBUSY;
            goto err_bindx_rem;
        }

        sa_addr = addr_buf;
        af = sctp_get_af_specific(sa_addr->sa.sa_family);
        if (!af) {
            retval = -EINVAL;
            goto err_bindx_rem;
        }

        if (!af->addr_valid(sa_addr, sp, NULL)) {
            retval = -EADDRNOTAVAIL;
            goto err_bindx_rem;
        }

        if (sa_addr->v4.sin_port &&
            sa_addr->v4.sin_port != htons(bp->port)) {
            retval = -EINVAL;
            goto err_bindx_rem;
        }

        if (!sa_addr->v4.sin_port)
            sa_addr->v4.sin_port = htons(bp->port);

        /* FIXME - There is probably a need to check if sk->sk_saddr and
         * sk->sk_rcv_addr are currently set to one of the addresses to
         * be removed. This is something which needs to be looked into
         * when we are fixing the outstanding issues with multi-homing
         * socket routing and failover schemes. Refer to comments in
         * sctp_do_bind(). -daisy
         */
        retval = sctp_del_bind_addr(bp, sa_addr);

        addr_buf += af->sockaddr_len;
err_bindx_rem:
        if (retval < 0) {
            /* Failed. Add the ones that has been removed back */
            if (cnt > 0)
                sctp_bindx_add(sk, addrs, cnt);
            return retval;
        }
    }

    return retval;
}

/* Send an ASCONF chunk with Delete IP address parameters to all the peers of
 * the associations that are part of the endpoint indicating that a list of
 * local addresses are removed from the endpoint.
 *
 * If any of the addresses is already in the bind address list of the
 * association, we do not send the chunk for that association.  But it will not
 * affect other associations.
 *
 * Only sctp_setsockopt_bindx() is supposed to call this function.
 */
static int sctp_send_asconf_del_ip(struct sock      *sk,
                   struct sockaddr  *addrs,
                   int          addrcnt)
{
    struct net *net = sock_net(sk);
    struct sctp_sock    *sp;
    struct sctp_endpoint    *ep;
    struct sctp_association *asoc;
    struct sctp_transport   *transport;
    struct sctp_bind_addr   *bp;
    struct sctp_chunk   *chunk;
    union sctp_addr     *laddr;
    void            *addr_buf;
    struct sctp_af      *af;
    struct sctp_sockaddr_entry *saddr;
    int             i;
    int             retval = 0;
    int         stored = 0;

    chunk = NULL;
    if (!net->sctp.addip_enable)
        return retval;

    sp = sctp_sk(sk);
    ep = sp->ep;

    SCTP_DEBUG_PRINTK("%s: (sk: %p, addrs: %p, addrcnt: %d)\n",
              __func__, sk, addrs, addrcnt);

    list_for_each_entry(asoc, &ep->asocs, asocs) {

        if (!asoc->peer.asconf_capable)
            continue;

        if (asoc->peer.addip_disabled_mask & SCTP_PARAM_DEL_IP)
            continue;

        if (!sctp_state(asoc, ESTABLISHED))
            continue;

        /* Check if any address in the packed array of addresses is
         * not present in the bind address list of the association.
         * If so, do not send the asconf chunk to its peer, but
         * continue with other associations.
         */
        addr_buf = addrs;
        for (i = 0; i < addrcnt; i++) {
            laddr = addr_buf;
            af = sctp_get_af_specific(laddr->v4.sin_family);
            if (!af) {
                retval = -EINVAL;
                goto out;
            }

            if (!sctp_assoc_lookup_laddr(asoc, laddr))
                break;

            addr_buf += af->sockaddr_len;
        }
        if (i < addrcnt)
            continue;

        /* Find one address in the association's bind address list
         * that is not in the packed array of addresses. This is to
         * make sure that we do not delete all the addresses in the
         * association.
         */
        bp = &asoc->base.bind_addr;
        laddr = sctp_find_unmatch_addr(bp, (union sctp_addr *)addrs,
                           addrcnt, sp);
        if ((laddr == NULL) && (addrcnt == 1)) {
            if (asoc->asconf_addr_del_pending)
                continue;
            asoc->asconf_addr_del_pending =
                kzalloc(sizeof(union sctp_addr), GFP_ATOMIC);
            if (asoc->asconf_addr_del_pending == NULL) {
                retval = -ENOMEM;
                goto out;
            }
            asoc->asconf_addr_del_pending->sa.sa_family =
                    addrs->sa_family;
            asoc->asconf_addr_del_pending->v4.sin_port =
                    htons(bp->port);
            if (addrs->sa_family == AF_INET) {
                struct sockaddr_in *sin;

                sin = (struct sockaddr_in *)addrs;
                asoc->asconf_addr_del_pending->v4.sin_addr.s_addr = sin->sin_addr.s_addr;
            } else if (addrs->sa_family == AF_INET6) {
                struct sockaddr_in6 *sin6;

                sin6 = (struct sockaddr_in6 *)addrs;
                asoc->asconf_addr_del_pending->v6.sin6_addr = sin6->sin6_addr;
            }
            SCTP_DEBUG_PRINTK_IPADDR("send_asconf_del_ip: keep the last address asoc: %p ",
                " at %p\n", asoc, asoc->asconf_addr_del_pending,
                asoc->asconf_addr_del_pending);
            asoc->src_out_of_asoc_ok = 1;
            stored = 1;
            goto skip_mkasconf;
        }

        /* We do not need RCU protection throughout this loop
         * because this is done under a socket lock from the
         * setsockopt call.
         */
        chunk = sctp_make_asconf_update_ip(asoc, laddr, addrs, addrcnt,
                           SCTP_PARAM_DEL_IP);
        if (!chunk) {
            retval = -ENOMEM;
            goto out;
        }

skip_mkasconf:
        /* Reset use_as_src flag for the addresses in the bind address
         * list that are to be deleted.
         */
        addr_buf = addrs;
        for (i = 0; i < addrcnt; i++) {
            laddr = addr_buf;
            af = sctp_get_af_specific(laddr->v4.sin_family);
            list_for_each_entry(saddr, &bp->address_list, list) {
                if (sctp_cmp_addr_exact(&saddr->a, laddr))
                    saddr->state = SCTP_ADDR_DEL;
            }
            addr_buf += af->sockaddr_len;
        }

        /* Update the route and saddr entries for all the transports
         * as some of the addresses in the bind address list are
         * about to be deleted and cannot be used as source addresses.
         */
        list_for_each_entry(transport, &asoc->peer.transport_addr_list,
                    transports) {
            dst_release(transport->dst);
            sctp_transport_route(transport, NULL,
                         sctp_sk(asoc->base.sk));
        }

        if (stored)
            /* We don't need to transmit ASCONF */
            continue;
        retval = sctp_send_asconf(asoc, chunk);
    }
out:
    return retval;
}

/* set addr events to assocs in the endpoint.  ep and addr_wq must be locked */
int sctp_asconf_mgmt(struct sctp_sock *sp, struct sctp_sockaddr_entry *addrw)
{
    struct sock *sk = sctp_opt2sk(sp);
    union sctp_addr *addr;
    struct sctp_af *af;

    /* It is safe to write port space in caller. */
    addr = &addrw->a;
    addr->v4.sin_port = htons(sp->ep->base.bind_addr.port);
    af = sctp_get_af_specific(addr->sa.sa_family);
    if (!af)
        return -EINVAL;
    if (sctp_verify_addr(sk, addr, af->sockaddr_len))
        return -EINVAL;

    if (addrw->state == SCTP_ADDR_NEW)
        return sctp_send_asconf_add_ip(sk, (struct sockaddr *)addr, 1);
    else
        return sctp_send_asconf_del_ip(sk, (struct sockaddr *)addr, 1);
}

/* Helper for tunneling sctp_bindx() requests through sctp_setsockopt()
 *
 * API 8.1
 * int sctp_bindx(int sd, struct sockaddr *addrs, int addrcnt,
 *                int flags);
 *
 * If sd is an IPv4 socket, the addresses passed must be IPv4 addresses.
 * If the sd is an IPv6 socket, the addresses passed can either be IPv4
 * or IPv6 addresses.
 *
 * A single address may be specified as INADDR_ANY or IN6ADDR_ANY, see
 * Section 3.1.2 for this usage.
 *
 * addrs is a pointer to an array of one or more socket addresses. Each
 * address is contained in its appropriate structure (i.e. struct
 * sockaddr_in or struct sockaddr_in6) the family of the address type
 * must be used to distinguish the address length (note that this
 * representation is termed a "packed array" of addresses). The caller
 * specifies the number of addresses in the array with addrcnt.
 *
 * On success, sctp_bindx() returns 0. On failure, sctp_bindx() returns
 * -1, and sets errno to the appropriate error code.
 *
 * For SCTP, the port given in each socket address must be the same, or
 * sctp_bindx() will fail, setting errno to EINVAL.
 *
 * The flags parameter is formed from the bitwise OR of zero or more of
 * the following currently defined flags:
 *
 * SCTP_BINDX_ADD_ADDR
 *
 * SCTP_BINDX_REM_ADDR
 *
 * SCTP_BINDX_ADD_ADDR directs SCTP to add the given addresses to the
 * association, and SCTP_BINDX_REM_ADDR directs SCTP to remove the given
 * addresses from the association. The two flags are mutually exclusive;
 * if both are given, sctp_bindx() will fail with EINVAL. A caller may
 * not remove all addresses from an association; sctp_bindx() will
 * reject such an attempt with EINVAL.
 *
 * An application can use sctp_bindx(SCTP_BINDX_ADD_ADDR) to associate
 * additional addresses with an endpoint after calling bind().  Or use
 * sctp_bindx(SCTP_BINDX_REM_ADDR) to remove some addresses a listening
 * socket is associated with so that no new association accepted will be
 * associated with those addresses. If the endpoint supports dynamic
 * address a SCTP_BINDX_REM_ADDR or SCTP_BINDX_ADD_ADDR may cause a
 * endpoint to send the appropriate message to the peer to change the
 * peers address lists.
 *
 * Adding and removing addresses from a connected association is
 * optional functionality. Implementations that do not support this
 * functionality should return EOPNOTSUPP.
 *
 * Basically do nothing but copying the addresses from user to kernel
 * land and invoking either sctp_bindx_add() or sctp_bindx_rem() on the sk.
 * This is used for tunneling the sctp_bindx() request through sctp_setsockopt()
 * from userspace.
 *
 * We don't use copy_from_user() for optimization: we first do the
 * sanity checks (buffer size -fast- and access check-healthy
 * pointer); if all of those succeed, then we can alloc the memory
 * (expensive operation) needed to copy the data to kernel. Then we do
 * the copying without checking the user space area
 * (__copy_from_user()).
 *
 * On exit there is no need to do sockfd_put(), sys_setsockopt() does
 * it.
 *
 * sk        The sk of the socket
 * addrs     The pointer to the addresses in user land
 * addrssize Size of the addrs buffer
 * op        Operation to perform (add or remove, see the flags of
 *           sctp_bindx)
 *
 * Returns 0 if ok, <0 errno code on error.
 */
SCTP_STATIC int sctp_setsockopt_bindx(struct sock* sk,
                      struct sockaddr __user *addrs,
                      int addrs_size, int op)
{
    struct sockaddr *kaddrs;
    int err;
    int addrcnt = 0;
    int walk_size = 0;
    struct sockaddr *sa_addr;
    void *addr_buf;
    struct sctp_af *af;

    SCTP_DEBUG_PRINTK("sctp_setsockopt_bindx: sk %p addrs %p"
              " addrs_size %d opt %d\n", sk, addrs, addrs_size, op);

    if (unlikely(addrs_size <= 0))
        return -EINVAL;

    /* Check the user passed a healthy pointer.  */
    if (unlikely(!access_ok(VERIFY_READ, addrs, addrs_size)))
        return -EFAULT;

    /* Alloc space for the address array in kernel memory.  */
    kaddrs = kmalloc(addrs_size, GFP_KERNEL);
    if (unlikely(!kaddrs))
        return -ENOMEM;

    if (__copy_from_user(kaddrs, addrs, addrs_size)) {
        kfree(kaddrs);
        return -EFAULT;
    }

    /* Walk through the addrs buffer and count the number of addresses. */
    addr_buf = kaddrs;
    while (walk_size < addrs_size) {
        if (walk_size + sizeof(sa_family_t) > addrs_size) {
            kfree(kaddrs);
            return -EINVAL;
        }

        sa_addr = addr_buf;
        af = sctp_get_af_specific(sa_addr->sa_family);

        /* If the address family is not supported or if this address
         * causes the address buffer to overflow return EINVAL.
         */
        if (!af || (walk_size + af->sockaddr_len) > addrs_size) {
            kfree(kaddrs);
            return -EINVAL;
        }
        addrcnt++;
        addr_buf += af->sockaddr_len;
        walk_size += af->sockaddr_len;
    }

    /* Do the work. */
    switch (op) {
    case SCTP_BINDX_ADD_ADDR:
        err = sctp_bindx_add(sk, kaddrs, addrcnt);
        if (err)
            goto out;
        err = sctp_send_asconf_add_ip(sk, kaddrs, addrcnt);
        break;

    case SCTP_BINDX_REM_ADDR:
        err = sctp_bindx_rem(sk, kaddrs, addrcnt);
        if (err)
            goto out;
        err = sctp_send_asconf_del_ip(sk, kaddrs, addrcnt);
        break;

    default:
        err = -EINVAL;
        break;
    }

out:
    kfree(kaddrs);

    return err;
}

/* __sctp_connect(struct sock* sk, struct sockaddr *kaddrs, int addrs_size)
 *
 * Common routine for handling connect() and sctp_connectx().
 * Connect will come in with just a single address.
 */
static int __sctp_connect(struct sock* sk,
              struct sockaddr *kaddrs,
              int addrs_size,
              sctp_assoc_t *assoc_id)
{
    struct net *net = sock_net(sk);
    struct sctp_sock *sp;
    struct sctp_endpoint *ep;
    struct sctp_association *asoc = NULL;
    struct sctp_association *asoc2;
    struct sctp_transport *transport;
    union sctp_addr to;
    struct sctp_af *af;
    sctp_scope_t scope;
    long timeo;
    int err = 0;
    int addrcnt = 0;
    int walk_size = 0;
    union sctp_addr *sa_addr = NULL;
    void *addr_buf;
    unsigned short port;
    unsigned int f_flags = 0;

    sp = sctp_sk(sk);
    ep = sp->ep;

    /* connect() cannot be done on a socket that is already in ESTABLISHED
     * state - UDP-style peeled off socket or a TCP-style socket that
     * is already connected.
     * It cannot be done even on a TCP-style listening socket.
     */
    if (sctp_sstate(sk, ESTABLISHED) ||
        (sctp_style(sk, TCP) && sctp_sstate(sk, LISTENING))) {
        err = -EISCONN;
        goto out_free;
    }

    /* Walk through the addrs buffer and count the number of addresses. */
    addr_buf = kaddrs;
    while (walk_size < addrs_size) {
        if (walk_size + sizeof(sa_family_t) > addrs_size) {
            err = -EINVAL;
            goto out_free;
        }

        sa_addr = addr_buf;
        af = sctp_get_af_specific(sa_addr->sa.sa_family);

        /* If the address family is not supported or if this address
         * causes the address buffer to overflow return EINVAL.
         */
        if (!af || (walk_size + af->sockaddr_len) > addrs_size) {
            err = -EINVAL;
            goto out_free;
        }

        port = ntohs(sa_addr->v4.sin_port);

        /* Save current address so we can work with it */
        memcpy(&to, sa_addr, af->sockaddr_len);

        err = sctp_verify_addr(sk, &to, af->sockaddr_len);
        if (err)
            goto out_free;

        /* Make sure the destination port is correctly set
         * in all addresses.
         */
        if (asoc && asoc->peer.port && asoc->peer.port != port)
            goto out_free;


        /* Check if there already is a matching association on the
         * endpoint (other than the one created here).
         */
        asoc2 = sctp_endpoint_lookup_assoc(ep, &to, &transport);
        if (asoc2 && asoc2 != asoc) {
            if (asoc2->state >= SCTP_STATE_ESTABLISHED)
                err = -EISCONN;
            else
                err = -EALREADY;
            goto out_free;
        }

        /* If we could not find a matching association on the endpoint,
         * make sure that there is no peeled-off association matching
         * the peer address even on another socket.
         */
        if (sctp_endpoint_is_peeled_off(ep, &to)) {
            err = -EADDRNOTAVAIL;
            goto out_free;
        }

        if (!asoc) {
            /* If a bind() or sctp_bindx() is not called prior to
             * an sctp_connectx() call, the system picks an
             * ephemeral port and will choose an address set
             * equivalent to binding with a wildcard address.
             */
            if (!ep->base.bind_addr.port) {
                if (sctp_autobind(sk)) {
                    err = -EAGAIN;
                    goto out_free;
                }
            } else {
                /*
                 * If an unprivileged user inherits a 1-many
                 * style socket with open associations on a
                 * privileged port, it MAY be permitted to
                 * accept new associations, but it SHOULD NOT
                 * be permitted to open new associations.
                 */
                if (ep->base.bind_addr.port < PROT_SOCK &&
                    !capable(CAP_NET_BIND_SERVICE)) {
                    err = -EACCES;
                    goto out_free;
                }
            }

            scope = sctp_scope(&to);
            asoc = sctp_association_new(ep, sk, scope, GFP_KERNEL);
            if (!asoc) {
                err = -ENOMEM;
                goto out_free;
            }

            err = sctp_assoc_set_bind_addr_from_ep(asoc, scope,
                                  GFP_KERNEL);
            if (err < 0) {
                goto out_free;
            }

        }

        /* Prime the peer's transport structures.  */
        transport = sctp_assoc_add_peer(asoc, &to, GFP_KERNEL,
                        SCTP_UNKNOWN);
        if (!transport) {
            err = -ENOMEM;
            goto out_free;
        }

        addrcnt++;
        addr_buf += af->sockaddr_len;
        walk_size += af->sockaddr_len;
    }

    /* In case the user of sctp_connectx() wants an association
     * id back, assign one now.
     */
    if (assoc_id) {
        err = sctp_assoc_set_id(asoc, GFP_KERNEL);
        if (err < 0)
            goto out_free;
    }

    err = sctp_primitive_ASSOCIATE(net, asoc, NULL);
    if (err < 0) {
        goto out_free;
    }

    /* Initialize sk's dport and daddr for getpeername() */
    inet_sk(sk)->inet_dport = htons(asoc->peer.port);
    af = sctp_get_af_specific(sa_addr->sa.sa_family);
    af->to_sk_daddr(sa_addr, sk);
    sk->sk_err = 0;

    /* in-kernel sockets don't generally have a file allocated to them
     * if all they do is call sock_create_kern().
     */
    if (sk->sk_socket->file)
        f_flags = sk->sk_socket->file->f_flags;

    timeo = sock_sndtimeo(sk, f_flags & O_NONBLOCK);

    err = sctp_wait_for_connect(asoc, &timeo);
    if ((err == 0 || err == -EINPROGRESS) && assoc_id)
        *assoc_id = asoc->assoc_id;

    /* Don't free association on exit. */
    asoc = NULL;

out_free:

    SCTP_DEBUG_PRINTK("About to exit __sctp_connect() free asoc: %p"
              " kaddrs: %p err: %d\n",
              asoc, kaddrs, err);
    if (asoc) {
        /* sctp_primitive_ASSOCIATE may have added this association
         * To the hash table, try to unhash it, just in case, its a noop
         * if it wasn't hashed so we're safe
         */
        sctp_unhash_established(asoc);
        sctp_association_free(asoc);
    }
    return err;
}

/* Helper for tunneling sctp_connectx() requests through sctp_setsockopt()
 *
 * API 8.9
 * int sctp_connectx(int sd, struct sockaddr *addrs, int addrcnt,
 *          sctp_assoc_t *asoc);
 *
 * If sd is an IPv4 socket, the addresses passed must be IPv4 addresses.
 * If the sd is an IPv6 socket, the addresses passed can either be IPv4
 * or IPv6 addresses.
 *
 * A single address may be specified as INADDR_ANY or IN6ADDR_ANY, see
 * Section 3.1.2 for this usage.
 *
 * addrs is a pointer to an array of one or more socket addresses. Each
 * address is contained in its appropriate structure (i.e. struct
 * sockaddr_in or struct sockaddr_in6) the family of the address type
 * must be used to distengish the address length (note that this
 * representation is termed a "packed array" of addresses). The caller
 * specifies the number of addresses in the array with addrcnt.
 *
 * On success, sctp_connectx() returns 0. It also sets the assoc_id to
 * the association id of the new association.  On failure, sctp_connectx()
 * returns -1, and sets errno to the appropriate error code.  The assoc_id
 * is not touched by the kernel.
 *
 * For SCTP, the port given in each socket address must be the same, or
 * sctp_connectx() will fail, setting errno to EINVAL.
 *
 * An application can use sctp_connectx to initiate an association with
 * an endpoint that is multi-homed.  Much like sctp_bindx() this call
 * allows a caller to specify multiple addresses at which a peer can be
 * reached.  The way the SCTP stack uses the list of addresses to set up
 * the association is implementation dependent.  This function only
 * specifies that the stack will try to make use of all the addresses in
 * the list when needed.
 *
 * Note that the list of addresses passed in is only used for setting up
 * the association.  It does not necessarily equal the set of addresses
 * the peer uses for the resulting association.  If the caller wants to
 * find out the set of peer addresses, it must use sctp_getpaddrs() to
 * retrieve them after the association has been set up.
 *
 * Basically do nothing but copying the addresses from user to kernel
 * land and invoking either sctp_connectx(). This is used for tunneling
 * the sctp_connectx() request through sctp_setsockopt() from userspace.
 *
 * We don't use copy_from_user() for optimization: we first do the
 * sanity checks (buffer size -fast- and access check-healthy
 * pointer); if all of those succeed, then we can alloc the memory
 * (expensive operation) needed to copy the data to kernel. Then we do
 * the copying without checking the user space area
 * (__copy_from_user()).
 *
 * On exit there is no need to do sockfd_put(), sys_setsockopt() does
 * it.
 *
 * sk        The sk of the socket
 * addrs     The pointer to the addresses in user land
 * addrssize Size of the addrs buffer
 *
 * Returns >=0 if ok, <0 errno code on error.
 */
SCTP_STATIC int __sctp_setsockopt_connectx(struct sock* sk,
                      struct sockaddr __user *addrs,
                      int addrs_size,
                      sctp_assoc_t *assoc_id)
{
    int err = 0;
    struct sockaddr *kaddrs;

    SCTP_DEBUG_PRINTK("%s - sk %p addrs %p addrs_size %d\n",
              __func__, sk, addrs, addrs_size);

    if (unlikely(addrs_size <= 0))
        return -EINVAL;

    /* Check the user passed a healthy pointer.  */
    if (unlikely(!access_ok(VERIFY_READ, addrs, addrs_size)))
        return -EFAULT;

    /* Alloc space for the address array in kernel memory.  */
    kaddrs = kmalloc(addrs_size, GFP_KERNEL);
    if (unlikely(!kaddrs))
        return -ENOMEM;

    if (__copy_from_user(kaddrs, addrs, addrs_size)) {
        err = -EFAULT;
    } else {
        err = __sctp_connect(sk, kaddrs, addrs_size, assoc_id);
    }

    kfree(kaddrs);

    return err;
}

/*
 * This is an older interface.  It's kept for backward compatibility
 * to the option that doesn't provide association id.
 */
SCTP_STATIC int sctp_setsockopt_connectx_old(struct sock* sk,
                      struct sockaddr __user *addrs,
                      int addrs_size)
{
    return __sctp_setsockopt_connectx(sk, addrs, addrs_size, NULL);
}

/*
 * New interface for the API.  The since the API is done with a socket
 * option, to make it simple we feed back the association id is as a return
 * indication to the call.  Error is always negative and association id is
 * always positive.
 */
SCTP_STATIC int sctp_setsockopt_connectx(struct sock* sk,
                      struct sockaddr __user *addrs,
                      int addrs_size)
{
    sctp_assoc_t assoc_id = 0;
    int err = 0;

    err = __sctp_setsockopt_connectx(sk, addrs, addrs_size, &assoc_id);

    if (err)
        return err;
    else
        return assoc_id;
}

/*
 * New (hopefully final) interface for the API.
 * We use the sctp_getaddrs_old structure so that use-space library
 * can avoid any unnecessary allocations.   The only defferent part
 * is that we store the actual length of the address buffer into the
 * addrs_num structure member.  That way we can re-use the existing
 * code.
 */
SCTP_STATIC int sctp_getsockopt_connectx3(struct sock* sk, int len,
                    char __user *optval,
                    int __user *optlen)
{
    struct sctp_getaddrs_old param;
    sctp_assoc_t assoc_id = 0;
    int err = 0;

    if (len < sizeof(param))
        return -EINVAL;

    if (copy_from_user(&param, optval, sizeof(param)))
        return -EFAULT;

    err = __sctp_setsockopt_connectx(sk,
            (struct sockaddr __user *)param.addrs,
            param.addr_num, &assoc_id);

    if (err == 0 || err == -EINPROGRESS) {
        if (copy_to_user(optval, &assoc_id, sizeof(assoc_id)))
            return -EFAULT;
        if (put_user(sizeof(assoc_id), optlen))
            return -EFAULT;
    }

    return err;
}

/* API 3.1.4 close() - UDP Style Syntax
 * Applications use close() to perform graceful shutdown (as described in
 * Section 10.1 of [SCTP]) on ALL the associations currently represented
 * by a UDP-style socket.
 *
 * The syntax is
 *
 *   ret = close(int sd);
 *
 *   sd      - the socket descriptor of the associations to be closed.
 *
 * To gracefully shutdown a specific association represented by the
 * UDP-style socket, an application should use the sendmsg() call,
 * passing no user data, but including the appropriate flag in the
 * ancillary data (see Section xxxx).
 *
 * If sd in the close() call is a branched-off socket representing only
 * one association, the shutdown is performed on that association only.
 *
 * 4.1.6 close() - TCP Style Syntax
 *
 * Applications use close() to gracefully close down an association.
 *
 * The syntax is:
 *
 *    int close(int sd);
 *
 *      sd      - the socket descriptor of the association to be closed.
 *
 * After an application calls close() on a socket descriptor, no further
 * socket operations will succeed on that descriptor.
 *
 * API 7.1.4 SO_LINGER
 *
 * An application using the TCP-style socket can use this option to
 * perform the SCTP ABORT primitive.  The linger option structure is:
 *
 *  struct  linger {
 *     int     l_onoff;                // option on/off
 *     int     l_linger;               // linger time
 * };
 *
 * To enable the option, set l_onoff to 1.  If the l_linger value is set
 * to 0, calling close() is the same as the ABORT primitive.  If the
 * value is set to a negative value, the setsockopt() call will return
 * an error.  If the value is set to a positive value linger_time, the
 * close() can be blocked for at most linger_time ms.  If the graceful
 * shutdown phase does not finish during this period, close() will
 * return but the graceful shutdown phase continues in the system.
 */
SCTP_STATIC void sctp_close(struct sock *sk, long timeout)
{
    struct net *net = sock_net(sk);
    struct sctp_endpoint *ep;
    struct sctp_association *asoc;
    struct list_head *pos, *temp;
    unsigned int data_was_unread;

    SCTP_DEBUG_PRINTK("sctp_close(sk: 0x%p, timeout:%ld)\n", sk, timeout);

    sctp_lock_sock(sk);
    sk->sk_shutdown = SHUTDOWN_MASK;
    sk->sk_state = SCTP_SS_CLOSING;

    ep = sctp_sk(sk)->ep;

    /* Clean up any skbs sitting on the receive queue.  */
    data_was_unread = sctp_queue_purge_ulpevents(&sk->sk_receive_queue);
    data_was_unread += sctp_queue_purge_ulpevents(&sctp_sk(sk)->pd_lobby);

    /* Walk all associations on an endpoint.  */
    list_for_each_safe(pos, temp, &ep->asocs) {
        asoc = list_entry(pos, struct sctp_association, asocs);

        if (sctp_style(sk, TCP)) {
            /* A closed association can still be in the list if
             * it belongs to a TCP-style listening socket that is
             * not yet accepted. If so, free it. If not, send an
             * ABORT or SHUTDOWN based on the linger options.
             */
            if (sctp_state(asoc, CLOSED)) {
                sctp_unhash_established(asoc);
                sctp_association_free(asoc);
                continue;
            }
        }

        if (data_was_unread || !skb_queue_empty(&asoc->ulpq.lobby) ||
            !skb_queue_empty(&asoc->ulpq.reasm) ||
            (sock_flag(sk, SOCK_LINGER) && !sk->sk_lingertime)) {
            struct sctp_chunk *chunk;

            chunk = sctp_make_abort_user(asoc, NULL, 0);
            if (chunk)
                sctp_primitive_ABORT(net, asoc, chunk);
        } else
            sctp_primitive_SHUTDOWN(net, asoc, NULL);
    }

    /* On a TCP-style socket, block for at most linger_time if set. */
    if (sctp_style(sk, TCP) && timeout)
        sctp_wait_for_close(sk, timeout);

    /* This will run the backlog queue.  */
    sctp_release_sock(sk);

    /* Supposedly, no process has access to the socket, but
     * the net layers still may.
     */
    sctp_local_bh_disable();
    sctp_bh_lock_sock(sk);

    /* Hold the sock, since sk_common_release() will put sock_put()
     * and we have just a little more cleanup.
     */
    sock_hold(sk);
    sk_common_release(sk);

    sctp_bh_unlock_sock(sk);
    sctp_local_bh_enable();

    sock_put(sk);

    SCTP_DBG_OBJCNT_DEC(sock);
}

/* Handle EPIPE error. */
static int sctp_error(struct sock *sk, int flags, int err)
{
    if (err == -EPIPE)
        err = sock_error(sk) ? : -EPIPE;
    if (err == -EPIPE && !(flags & MSG_NOSIGNAL))
        send_sig(SIGPIPE, current, 0);
    return err;
}

/* API 3.1.3 sendmsg() - UDP Style Syntax
 *
 * An application uses sendmsg() and recvmsg() calls to transmit data to
 * and receive data from its peer.
 *
 *  ssize_t sendmsg(int socket, const struct msghdr *message,
 *                  int flags);
 *
 *  socket  - the socket descriptor of the endpoint.
 *  message - pointer to the msghdr structure which contains a single
 *            user message and possibly some ancillary data.
 *
 *            See Section 5 for complete description of the data
 *            structures.
 *
 *  flags   - flags sent or received with the user message, see Section
 *            5 for complete description of the flags.
 *
 * Note:  This function could use a rewrite especially when explicit
 * connect support comes in.
 */
/* BUG:  We do not implement the equivalent of sk_stream_wait_memory(). */

SCTP_STATIC int sctp_msghdr_parse(const struct msghdr *, sctp_cmsgs_t *);

SCTP_STATIC int sctp_sendmsg(struct kiocb *iocb, struct sock *sk,
                 struct msghdr *msg, size_t msg_len)
{
    struct net *net = sock_net(sk);
    struct sctp_sock *sp;
    struct sctp_endpoint *ep;
    struct sctp_association *new_asoc=NULL, *asoc=NULL;
    struct sctp_transport *transport, *chunk_tp;
    struct sctp_chunk *chunk;
    union sctp_addr to;
    struct sockaddr *msg_name = NULL;
    struct sctp_sndrcvinfo default_sinfo;
    struct sctp_sndrcvinfo *sinfo;
    struct sctp_initmsg *sinit;
    sctp_assoc_t associd = 0;
    sctp_cmsgs_t cmsgs = { NULL };
    int err;
    sctp_scope_t scope;
    long timeo;
    __u16 sinfo_flags = 0;
    struct sctp_datamsg *datamsg;
    int msg_flags = msg->msg_flags;

    SCTP_DEBUG_PRINTK("sctp_sendmsg(sk: %p, msg: %p, msg_len: %zu)\n",
              sk, msg, msg_len);

    err = 0;
    sp = sctp_sk(sk);
    ep = sp->ep;

    SCTP_DEBUG_PRINTK("Using endpoint: %p.\n", ep);

    /* We cannot send a message over a TCP-style listening socket. */
    if (sctp_style(sk, TCP) && sctp_sstate(sk, LISTENING)) {
        err = -EPIPE;
        goto out_nounlock;
    }

    /* Parse out the SCTP CMSGs.  */
    err = sctp_msghdr_parse(msg, &cmsgs);

    if (err) {
        SCTP_DEBUG_PRINTK("msghdr parse err = %x\n", err);
        goto out_nounlock;
    }

    /* Fetch the destination address for this packet.  This
     * address only selects the association--it is not necessarily
     * the address we will send to.
     * For a peeled-off socket, msg_name is ignored.
     */
    if (!sctp_style(sk, UDP_HIGH_BANDWIDTH) && msg->msg_name) {
        int msg_namelen = msg->msg_namelen;

        err = sctp_verify_addr(sk, (union sctp_addr *)msg->msg_name,
                       msg_namelen);
        if (err)
            return err;

        if (msg_namelen > sizeof(to))
            msg_namelen = sizeof(to);
        memcpy(&to, msg->msg_name, msg_namelen);
        msg_name = msg->msg_name;
    }

    sinfo = cmsgs.info;
    sinit = cmsgs.init;

    /* Did the user specify SNDRCVINFO?  */
    if (sinfo) {
        sinfo_flags = sinfo->sinfo_flags;
        associd = sinfo->sinfo_assoc_id;
    }

    SCTP_DEBUG_PRINTK("msg_len: %zu, sinfo_flags: 0x%x\n",
              msg_len, sinfo_flags);

    /* SCTP_EOF or SCTP_ABORT cannot be set on a TCP-style socket. */
    if (sctp_style(sk, TCP) && (sinfo_flags & (SCTP_EOF | SCTP_ABORT))) {
        err = -EINVAL;
        goto out_nounlock;
    }

    /* If SCTP_EOF is set, no data can be sent. Disallow sending zero
     * length messages when SCTP_EOF|SCTP_ABORT is not set.
     * If SCTP_ABORT is set, the message length could be non zero with
     * the msg_iov set to the user abort reason.
     */
    if (((sinfo_flags & SCTP_EOF) && (msg_len > 0)) ||
        (!(sinfo_flags & (SCTP_EOF|SCTP_ABORT)) && (msg_len == 0))) {
        err = -EINVAL;
        goto out_nounlock;
    }

    /* If SCTP_ADDR_OVER is set, there must be an address
     * specified in msg_name.
     */
    if ((sinfo_flags & SCTP_ADDR_OVER) && (!msg->msg_name)) {
        err = -EINVAL;
        goto out_nounlock;
    }

    transport = NULL;

    SCTP_DEBUG_PRINTK("About to look up association.\n");

    sctp_lock_sock(sk);

    /* If a msg_name has been specified, assume this is to be used.  */
    if (msg_name) {
        /* Look for a matching association on the endpoint. */
        asoc = sctp_endpoint_lookup_assoc(ep, &to, &transport);
        if (!asoc) {
            /* If we could not find a matching association on the
             * endpoint, make sure that it is not a TCP-style
             * socket that already has an association or there is
             * no peeled-off association on another socket.
             */
            if ((sctp_style(sk, TCP) &&
                 sctp_sstate(sk, ESTABLISHED)) ||
                sctp_endpoint_is_peeled_off(ep, &to)) {
                err = -EADDRNOTAVAIL;
                goto out_unlock;
            }
        }
    } else {
        asoc = sctp_id2assoc(sk, associd);
        if (!asoc) {
            err = -EPIPE;
            goto out_unlock;
        }
    }

    if (asoc) {
        SCTP_DEBUG_PRINTK("Just looked up association: %p.\n", asoc);

        /* We cannot send a message on a TCP-style SCTP_SS_ESTABLISHED
         * socket that has an association in CLOSED state. This can
         * happen when an accepted socket has an association that is
         * already CLOSED.
         */
        if (sctp_state(asoc, CLOSED) && sctp_style(sk, TCP)) {
            err = -EPIPE;
            goto out_unlock;
        }

        if (sinfo_flags & SCTP_EOF) {
            SCTP_DEBUG_PRINTK("Shutting down association: %p\n",
                      asoc);
            sctp_primitive_SHUTDOWN(net, asoc, NULL);
            err = 0;
            goto out_unlock;
        }
        if (sinfo_flags & SCTP_ABORT) {

            chunk = sctp_make_abort_user(asoc, msg, msg_len);
            if (!chunk) {
                err = -ENOMEM;
                goto out_unlock;
            }

            SCTP_DEBUG_PRINTK("Aborting association: %p\n", asoc);
            sctp_primitive_ABORT(net, asoc, chunk);
            err = 0;
            goto out_unlock;
        }
    }

    /* Do we need to create the association?  */
    if (!asoc) {
        SCTP_DEBUG_PRINTK("There is no association yet.\n");

        if (sinfo_flags & (SCTP_EOF | SCTP_ABORT)) {
            err = -EINVAL;
            goto out_unlock;
        }

        /* Check for invalid stream against the stream counts,
         * either the default or the user specified stream counts.
         */
        if (sinfo) {
            if (!sinit || (sinit && !sinit->sinit_num_ostreams)) {
                /* Check against the defaults. */
                if (sinfo->sinfo_stream >=
                    sp->initmsg.sinit_num_ostreams) {
                    err = -EINVAL;
                    goto out_unlock;
                }
            } else {
                /* Check against the requested.  */
                if (sinfo->sinfo_stream >=
                    sinit->sinit_num_ostreams) {
                    err = -EINVAL;
                    goto out_unlock;
                }
            }
        }

        /*
         * API 3.1.2 bind() - UDP Style Syntax
         * If a bind() or sctp_bindx() is not called prior to a
         * sendmsg() call that initiates a new association, the
         * system picks an ephemeral port and will choose an address
         * set equivalent to binding with a wildcard address.
         */
        if (!ep->base.bind_addr.port) {
            if (sctp_autobind(sk)) {
                err = -EAGAIN;
                goto out_unlock;
            }
        } else {
            /*
             * If an unprivileged user inherits a one-to-many
             * style socket with open associations on a privileged
             * port, it MAY be permitted to accept new associations,
             * but it SHOULD NOT be permitted to open new
             * associations.
             */
            if (ep->base.bind_addr.port < PROT_SOCK &&
                !capable(CAP_NET_BIND_SERVICE)) {
                err = -EACCES;
                goto out_unlock;
            }
        }

        scope = sctp_scope(&to);
        new_asoc = sctp_association_new(ep, sk, scope, GFP_KERNEL);
        if (!new_asoc) {
            err = -ENOMEM;
            goto out_unlock;
        }
        asoc = new_asoc;
        err = sctp_assoc_set_bind_addr_from_ep(asoc, scope, GFP_KERNEL);
        if (err < 0) {
            err = -ENOMEM;
            goto out_free;
        }

        /* If the SCTP_INIT ancillary data is specified, set all
         * the association init values accordingly.
         */
        if (sinit) {
            if (sinit->sinit_num_ostreams) {
                asoc->c.sinit_num_ostreams =
                    sinit->sinit_num_ostreams;
            }
            if (sinit->sinit_max_instreams) {
                asoc->c.sinit_max_instreams =
                    sinit->sinit_max_instreams;
            }
            if (sinit->sinit_max_attempts) {
                asoc->max_init_attempts
                    = sinit->sinit_max_attempts;
            }
            if (sinit->sinit_max_init_timeo) {
                asoc->max_init_timeo =
                 msecs_to_jiffies(sinit->sinit_max_init_timeo);
            }
        }

        /* Prime the peer's transport structures.  */
        transport = sctp_assoc_add_peer(asoc, &to, GFP_KERNEL, SCTP_UNKNOWN);
        if (!transport) {
            err = -ENOMEM;
            goto out_free;
        }
    }

    /* ASSERT: we have a valid association at this point.  */
    SCTP_DEBUG_PRINTK("We have a valid association.\n");

    if (!sinfo) {
        /* If the user didn't specify SNDRCVINFO, make up one with
         * some defaults.
         */
        memset(&default_sinfo, 0, sizeof(default_sinfo));
        default_sinfo.sinfo_stream = asoc->default_stream;
        default_sinfo.sinfo_flags = asoc->default_flags;
        default_sinfo.sinfo_ppid = asoc->default_ppid;
        default_sinfo.sinfo_context = asoc->default_context;
        default_sinfo.sinfo_timetolive = asoc->default_timetolive;
        default_sinfo.sinfo_assoc_id = sctp_assoc2id(asoc);
        sinfo = &default_sinfo;
    }

    /* API 7.1.7, the sndbuf size per association bounds the
     * maximum size of data that can be sent in a single send call.
     */
    if (msg_len > sk->sk_sndbuf) {
        err = -EMSGSIZE;
        goto out_free;
    }

    if (asoc->pmtu_pending)
        sctp_assoc_pending_pmtu(sk, asoc);

    /* If fragmentation is disabled and the message length exceeds the
     * association fragmentation point, return EMSGSIZE.  The I-D
     * does not specify what this error is, but this looks like
     * a great fit.
     */
    if (sctp_sk(sk)->disable_fragments && (msg_len > asoc->frag_point)) {
        err = -EMSGSIZE;
        goto out_free;
    }

    /* Check for invalid stream. */
    if (sinfo->sinfo_stream >= asoc->c.sinit_num_ostreams) {
        err = -EINVAL;
        goto out_free;
    }

    timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
    if (!sctp_wspace(asoc)) {
        err = sctp_wait_for_sndbuf(asoc, &timeo, msg_len);
        if (err)
            goto out_free;
    }

    /* If an address is passed with the sendto/sendmsg call, it is used
     * to override the primary destination address in the TCP model, or
     * when SCTP_ADDR_OVER flag is set in the UDP model.
     */
    if ((sctp_style(sk, TCP) && msg_name) ||
        (sinfo_flags & SCTP_ADDR_OVER)) {
        chunk_tp = sctp_assoc_lookup_paddr(asoc, &to);
        if (!chunk_tp) {
            err = -EINVAL;
            goto out_free;
        }
    } else
        chunk_tp = NULL;

    /* Auto-connect, if we aren't connected already. */
    if (sctp_state(asoc, CLOSED)) {
        err = sctp_primitive_ASSOCIATE(net, asoc, NULL);
        if (err < 0)
            goto out_free;
        SCTP_DEBUG_PRINTK("We associated primitively.\n");
    }

    /* Break the message into multiple chunks of maximum size. */
    datamsg = sctp_datamsg_from_user(asoc, sinfo, msg, msg_len);
    if (IS_ERR(datamsg)) {
        err = PTR_ERR(datamsg);
        goto out_free;
    }

    /* Now send the (possibly) fragmented message. */
    list_for_each_entry(chunk, &datamsg->chunks, frag_list) {
        sctp_chunk_hold(chunk);

        /* Do accounting for the write space.  */
        sctp_set_owner_w(chunk);

        chunk->transport = chunk_tp;
    }

    /* Send it to the lower layers.  Note:  all chunks
     * must either fail or succeed.   The lower layer
     * works that way today.  Keep it that way or this
     * breaks.
     */
    err = sctp_primitive_SEND(net, asoc, datamsg);
    /* Did the lower layer accept the chunk? */
    if (err)
        sctp_datamsg_free(datamsg);
    else
        sctp_datamsg_put(datamsg);

    SCTP_DEBUG_PRINTK("We sent primitively.\n");

    if (err)
        goto out_free;
    else
        err = msg_len;

    /* If we are already past ASSOCIATE, the lower
     * layers are responsible for association cleanup.
     */
    goto out_unlock;

out_free:
    if (new_asoc) {
        sctp_unhash_established(asoc);
        sctp_association_free(asoc);
    }
out_unlock:
    sctp_release_sock(sk);

out_nounlock:
    return sctp_error(sk, msg_flags, err);

#if 0
do_sock_err:
    if (msg_len)
        err = msg_len;
    else
        err = sock_error(sk);
    goto out;

do_interrupted:
    if (msg_len)
        err = msg_len;
    goto out;
#endif /* 0 */
}

/* This is an extended version of skb_pull() that removes the data from the
 * start of a skb even when data is spread across the list of skb's in the
 * frag_list. len specifies the total amount of data that needs to be removed.
 * when 'len' bytes could be removed from the skb, it returns 0.
 * If 'len' exceeds the total skb length,  it returns the no. of bytes that
 * could not be removed.
 */
static int sctp_skb_pull(struct sk_buff *skb, int len)
{
    struct sk_buff *list;
    int skb_len = skb_headlen(skb);
    int rlen;

    if (len <= skb_len) {
        __skb_pull(skb, len);
        return 0;
    }
    len -= skb_len;
    __skb_pull(skb, skb_len);

    skb_walk_frags(skb, list) {
        rlen = sctp_skb_pull(list, len);
        skb->len -= (len-rlen);
        skb->data_len -= (len-rlen);

        if (!rlen)
            return 0;

        len = rlen;
    }

    return len;
}

/* API 3.1.3  recvmsg() - UDP Style Syntax
 *
 *  ssize_t recvmsg(int socket, struct msghdr *message,
 *                    int flags);
 *
 *  socket  - the socket descriptor of the endpoint.
 *  message - pointer to the msghdr structure which contains a single
 *            user message and possibly some ancillary data.
 *
 *            See Section 5 for complete description of the data
 *            structures.
 *
 *  flags   - flags sent or received with the user message, see Section
 *            5 for complete description of the flags.
 */
static struct sk_buff *sctp_skb_recv_datagram(struct sock *, int, int, int *);

SCTP_STATIC int sctp_recvmsg(struct kiocb *iocb, struct sock *sk,
                 struct msghdr *msg, size_t len, int noblock,
                 int flags, int *addr_len)
{
    struct sctp_ulpevent *event = NULL;
    struct sctp_sock *sp = sctp_sk(sk);
    struct sk_buff *skb;
    int copied;
    int err = 0;
    int skb_len;

    SCTP_DEBUG_PRINTK("sctp_recvmsg(%s: %p, %s: %p, %s: %zd, %s: %d, %s: "
              "0x%x, %s: %p)\n", "sk", sk, "msghdr", msg,
              "len", len, "knoblauch", noblock,
              "flags", flags, "addr_len", addr_len);

    sctp_lock_sock(sk);

    if (sctp_style(sk, TCP) && !sctp_sstate(sk, ESTABLISHED)) {
        err = -ENOTCONN;
        goto out;
    }

    skb = sctp_skb_recv_datagram(sk, flags, noblock, &err);
    if (!skb)
        goto out;

    /* Get the total length of the skb including any skb's in the
     * frag_list.
     */
    skb_len = skb->len;

    copied = skb_len;
    if (copied > len)
        copied = len;

    err = skb_copy_datagram_iovec(skb, 0, msg->msg_iov, copied);

    event = sctp_skb2event(skb);

    if (err)
        goto out_free;

    sock_recv_ts_and_drops(msg, sk, skb);
    if (sctp_ulpevent_is_notification(event)) {
        msg->msg_flags |= MSG_NOTIFICATION;
        sp->pf->event_msgname(event, msg->msg_name, addr_len);
    } else {
        sp->pf->skb_msgname(skb, msg->msg_name, addr_len);
    }

    /* Check if we allow SCTP_SNDRCVINFO. */
    if (sp->subscribe.sctp_data_io_event)
        sctp_ulpevent_read_sndrcvinfo(event, msg);
#if 0
    /* FIXME: we should be calling IP/IPv6 layers.  */
    if (sk->sk_protinfo.af_inet.cmsg_flags)
        ip_cmsg_recv(msg, skb);
#endif

    err = copied;

    /* If skb's length exceeds the user's buffer, update the skb and
     * push it back to the receive_queue so that the next call to
     * recvmsg() will return the remaining data. Don't set MSG_EOR.
     */
    if (skb_len > copied) {
        msg->msg_flags &= ~MSG_EOR;
        if (flags & MSG_PEEK)
            goto out_free;
        sctp_skb_pull(skb, copied);
        skb_queue_head(&sk->sk_receive_queue, skb);

        /* When only partial message is copied to the user, increase
         * rwnd by that amount. If all the data in the skb is read,
         * rwnd is updated when the event is freed.
         */
        if (!sctp_ulpevent_is_notification(event))
            sctp_assoc_rwnd_increase(event->asoc, copied);
        goto out;
    } else if ((event->msg_flags & MSG_NOTIFICATION) ||
           (event->msg_flags & MSG_EOR))
        msg->msg_flags |= MSG_EOR;
    else
        msg->msg_flags &= ~MSG_EOR;

out_free:
    if (flags & MSG_PEEK) {
        /* Release the skb reference acquired after peeking the skb in
         * sctp_skb_recv_datagram().
         */
        kfree_skb(skb);
    } else {
        /* Free the event which includes releasing the reference to
         * the owner of the skb, freeing the skb and updating the
         * rwnd.
         */
        sctp_ulpevent_free(event);
    }
out:
    sctp_release_sock(sk);
    return err;
}

/* 7.1.12 Enable/Disable message fragmentation (SCTP_DISABLE_FRAGMENTS)
 *
 * This option is a on/off flag.  If enabled no SCTP message
 * fragmentation will be performed.  Instead if a message being sent
 * exceeds the current PMTU size, the message will NOT be sent and
 * instead a error will be indicated to the user.
 */
static int sctp_setsockopt_disable_fragments(struct sock *sk,
                         char __user *optval,
                         unsigned int optlen)
{
    int val;

    if (optlen < sizeof(int))
        return -EINVAL;

    if (get_user(val, (int __user *)optval))
        return -EFAULT;

    sctp_sk(sk)->disable_fragments = (val == 0) ? 0 : 1;

    return 0;
}

static int sctp_setsockopt_events(struct sock *sk, char __user *optval,
                  unsigned int optlen)
{
    struct sctp_association *asoc;
    struct sctp_ulpevent *event;

    if (optlen > sizeof(struct sctp_event_subscribe))
        return -EINVAL;
    if (copy_from_user(&sctp_sk(sk)->subscribe, optval, optlen))
        return -EFAULT;

    /*
     * At the time when a user app subscribes to SCTP_SENDER_DRY_EVENT,
     * if there is no data to be sent or retransmit, the stack will
     * immediately send up this notification.
     */
    if (sctp_ulpevent_type_enabled(SCTP_SENDER_DRY_EVENT,
                       &sctp_sk(sk)->subscribe)) {
        asoc = sctp_id2assoc(sk, 0);

        if (asoc && sctp_outq_is_empty(&asoc->outqueue)) {
            event = sctp_ulpevent_make_sender_dry_event(asoc,
                    GFP_ATOMIC);
            if (!event)
                return -ENOMEM;

            sctp_ulpq_tail_event(&asoc->ulpq, event);
        }
    }

    return 0;
}

/* 7.1.8 Automatic Close of associations (SCTP_AUTOCLOSE)
 *
 * This socket option is applicable to the UDP-style socket only.  When
 * set it will cause associations that are idle for more than the
 * specified number of seconds to automatically close.  An association
 * being idle is defined an association that has NOT sent or received
 * user data.  The special value of '0' indicates that no automatic
 * close of any associations should be performed.  The option expects an
 * integer defining the number of seconds of idle time before an
 * association is closed.
 */
static int sctp_setsockopt_autoclose(struct sock *sk, char __user *optval,
                     unsigned int optlen)
{
    struct sctp_sock *sp = sctp_sk(sk);

    /* Applicable to UDP-style socket only */
    if (sctp_style(sk, TCP))
        return -EOPNOTSUPP;
    if (optlen != sizeof(int))
        return -EINVAL;
    if (copy_from_user(&sp->autoclose, optval, optlen))
        return -EFAULT;

    return 0;
}

/* 7.1.13 Peer Address Parameters (SCTP_PEER_ADDR_PARAMS)
 *
 * Applications can enable or disable heartbeats for any peer address of
 * an association, modify an address's heartbeat interval, force a
 * heartbeat to be sent immediately, and adjust the address's maximum
 * number of retransmissions sent before an address is considered
 * unreachable.  The following structure is used to access and modify an
 * address's parameters:
 *
 *  struct sctp_paddrparams {
 *     sctp_assoc_t            spp_assoc_id;
 *     struct sockaddr_storage spp_address;
 *     uint32_t                spp_hbinterval;
 *     uint16_t                spp_pathmaxrxt;
 *     uint32_t                spp_pathmtu;
 *     uint32_t                spp_sackdelay;
 *     uint32_t                spp_flags;
 * };
 *
 *   spp_assoc_id    - (one-to-many style socket) This is filled in the
 *                     application, and identifies the association for
 *                     this query.
 *   spp_address     - This specifies which address is of interest.
 *   spp_hbinterval  - This contains the value of the heartbeat interval,
 *                     in milliseconds.  If a  value of zero
 *                     is present in this field then no changes are to
 *                     be made to this parameter.
 *   spp_pathmaxrxt  - This contains the maximum number of
 *                     retransmissions before this address shall be
 *                     considered unreachable. If a  value of zero
 *                     is present in this field then no changes are to
 *                     be made to this parameter.
 *   spp_pathmtu     - When Path MTU discovery is disabled the value
 *                     specified here will be the "fixed" path mtu.
 *                     Note that if the spp_address field is empty
 *                     then all associations on this address will
 *                     have this fixed path mtu set upon them.
 *
 *   spp_sackdelay   - When delayed sack is enabled, this value specifies
 *                     the number of milliseconds that sacks will be delayed
 *                     for. This value will apply to all addresses of an
 *                     association if the spp_address field is empty. Note
 *                     also, that if delayed sack is enabled and this
 *                     value is set to 0, no change is made to the last
 *                     recorded delayed sack timer value.
 *
 *   spp_flags       - These flags are used to control various features
 *                     on an association. The flag field may contain
 *                     zero or more of the following options.
 *
 *                     SPP_HB_ENABLE  - Enable heartbeats on the
 *                     specified address. Note that if the address
 *                     field is empty all addresses for the association
 *                     have heartbeats enabled upon them.
 *
 *                     SPP_HB_DISABLE - Disable heartbeats on the
 *                     speicifed address. Note that if the address
 *                     field is empty all addresses for the association
 *                     will have their heartbeats disabled. Note also
 *                     that SPP_HB_ENABLE and SPP_HB_DISABLE are
 *                     mutually exclusive, only one of these two should
 *                     be specified. Enabling both fields will have
 *                     undetermined results.
 *
 *                     SPP_HB_DEMAND - Request a user initiated heartbeat
 *                     to be made immediately.
 *
 *                     SPP_HB_TIME_IS_ZERO - Specify's that the time for
 *                     heartbeat delayis to be set to the value of 0
 *                     milliseconds.
 *
 *                     SPP_PMTUD_ENABLE - This field will enable PMTU
 *                     discovery upon the specified address. Note that
 *                     if the address feild is empty then all addresses
 *                     on the association are effected.
 *
 *                     SPP_PMTUD_DISABLE - This field will disable PMTU
 *                     discovery upon the specified address. Note that
 *                     if the address feild is empty then all addresses
 *                     on the association are effected. Not also that
 *                     SPP_PMTUD_ENABLE and SPP_PMTUD_DISABLE are mutually
 *                     exclusive. Enabling both will have undetermined
 *                     results.
 *
 *                     SPP_SACKDELAY_ENABLE - Setting this flag turns
 *                     on delayed sack. The time specified in spp_sackdelay
 *                     is used to specify the sack delay for this address. Note
 *                     that if spp_address is empty then all addresses will
 *                     enable delayed sack and take on the sack delay
 *                     value specified in spp_sackdelay.
 *                     SPP_SACKDELAY_DISABLE - Setting this flag turns
 *                     off delayed sack. If the spp_address field is blank then
 *                     delayed sack is disabled for the entire association. Note
 *                     also that this field is mutually exclusive to
 *                     SPP_SACKDELAY_ENABLE, setting both will have undefined
 *                     results.
 */
static int sctp_apply_peer_addr_params(struct sctp_paddrparams *params,
                       struct sctp_transport   *trans,
                       struct sctp_association *asoc,
                       struct sctp_sock        *sp,
                       int                      hb_change,
                       int                      pmtud_change,
                       int                      sackdelay_change)
{
    int error;

    if (params->spp_flags & SPP_HB_DEMAND && trans) {
        struct net *net = sock_net(trans->asoc->base.sk);

        error = sctp_primitive_REQUESTHEARTBEAT(net, trans->asoc, trans);
        if (error)
            return error;
    }

    /* Note that unless the spp_flag is set to SPP_HB_ENABLE the value of
     * this field is ignored.  Note also that a value of zero indicates
     * the current setting should be left unchanged.
     */
    if (params->spp_flags & SPP_HB_ENABLE) {

        /* Re-zero the interval if the SPP_HB_TIME_IS_ZERO is
         * set.  This lets us use 0 value when this flag
         * is set.
         */
        if (params->spp_flags & SPP_HB_TIME_IS_ZERO)
            params->spp_hbinterval = 0;

        if (params->spp_hbinterval ||
            (params->spp_flags & SPP_HB_TIME_IS_ZERO)) {
            if (trans) {
                trans->hbinterval =
                    msecs_to_jiffies(params->spp_hbinterval);
            } else if (asoc) {
                asoc->hbinterval =
                    msecs_to_jiffies(params->spp_hbinterval);
            } else {
                sp->hbinterval = params->spp_hbinterval;
            }
        }
    }

    if (hb_change) {
        if (trans) {
            trans->param_flags =
                (trans->param_flags & ~SPP_HB) | hb_change;
        } else if (asoc) {
            asoc->param_flags =
                (asoc->param_flags & ~SPP_HB) | hb_change;
        } else {
            sp->param_flags =
                (sp->param_flags & ~SPP_HB) | hb_change;
        }
    }

    /* When Path MTU discovery is disabled the value specified here will
     * be the "fixed" path mtu (i.e. the value of the spp_flags field must
     * include the flag SPP_PMTUD_DISABLE for this field to have any
     * effect).
     */
    if ((params->spp_flags & SPP_PMTUD_DISABLE) && params->spp_pathmtu) {
        if (trans) {
            trans->pathmtu = params->spp_pathmtu;
            sctp_assoc_sync_pmtu(sctp_opt2sk(sp), asoc);
        } else if (asoc) {
            asoc->pathmtu = params->spp_pathmtu;
            sctp_frag_point(asoc, params->spp_pathmtu);
        } else {
            sp->pathmtu = params->spp_pathmtu;
        }
    }

    if (pmtud_change) {
        if (trans) {
            int update = (trans->param_flags & SPP_PMTUD_DISABLE) &&
                (params->spp_flags & SPP_PMTUD_ENABLE);
            trans->param_flags =
                (trans->param_flags & ~SPP_PMTUD) | pmtud_change;
            if (update) {
                sctp_transport_pmtu(trans, sctp_opt2sk(sp));
                sctp_assoc_sync_pmtu(sctp_opt2sk(sp), asoc);
            }
        } else if (asoc) {
            asoc->param_flags =
                (asoc->param_flags & ~SPP_PMTUD) | pmtud_change;
        } else {
            sp->param_flags =
                (sp->param_flags & ~SPP_PMTUD) | pmtud_change;
        }
    }

    /* Note that unless the spp_flag is set to SPP_SACKDELAY_ENABLE the
     * value of this field is ignored.  Note also that a value of zero
     * indicates the current setting should be left unchanged.
     */
    if ((params->spp_flags & SPP_SACKDELAY_ENABLE) && params->spp_sackdelay) {
        if (trans) {
            trans->sackdelay =
                msecs_to_jiffies(params->spp_sackdelay);
        } else if (asoc) {
            asoc->sackdelay =
                msecs_to_jiffies(params->spp_sackdelay);
        } else {
            sp->sackdelay = params->spp_sackdelay;
        }
    }

    if (sackdelay_change) {
        if (trans) {
            trans->param_flags =
                (trans->param_flags & ~SPP_SACKDELAY) |
                sackdelay_change;
        } else if (asoc) {
            asoc->param_flags =
                (asoc->param_flags & ~SPP_SACKDELAY) |
                sackdelay_change;
        } else {
            sp->param_flags =
                (sp->param_flags & ~SPP_SACKDELAY) |
                sackdelay_change;
        }
    }

    /* Note that a value of zero indicates the current setting should be
       left unchanged.
     */
    if (params->spp_pathmaxrxt) {
        if (trans) {
            trans->pathmaxrxt = params->spp_pathmaxrxt;
        } else if (asoc) {
            asoc->pathmaxrxt = params->spp_pathmaxrxt;
        } else {
            sp->pathmaxrxt = params->spp_pathmaxrxt;
        }
    }

    return 0;
}

static int sctp_setsockopt_peer_addr_params(struct sock *sk,
                        char __user *optval,
                        unsigned int optlen)
{
    struct sctp_paddrparams  params;
    struct sctp_transport   *trans = NULL;
    struct sctp_association *asoc = NULL;
    struct sctp_sock        *sp = sctp_sk(sk);
    int error;
    int hb_change, pmtud_change, sackdelay_change;

    if (optlen != sizeof(struct sctp_paddrparams))
        return - EINVAL;

    if (copy_from_user(&params, optval, optlen))
        return -EFAULT;

    /* Validate flags and value parameters. */
    hb_change        = params.spp_flags & SPP_HB;
    pmtud_change     = params.spp_flags & SPP_PMTUD;
    sackdelay_change = params.spp_flags & SPP_SACKDELAY;

    if (hb_change        == SPP_HB ||
        pmtud_change     == SPP_PMTUD ||
        sackdelay_change == SPP_SACKDELAY ||
        params.spp_sackdelay > 500 ||
        (params.spp_pathmtu &&
         params.spp_pathmtu < SCTP_DEFAULT_MINSEGMENT))
        return -EINVAL;

    /* If an address other than INADDR_ANY is specified, and
     * no transport is found, then the request is invalid.
     */
    if (!sctp_is_any(sk, ( union sctp_addr *)&params.spp_address)) {
        trans = sctp_addr_id2transport(sk, &params.spp_address,
                           params.spp_assoc_id);
        if (!trans)
            return -EINVAL;
    }

    /* Get association, if assoc_id != 0 and the socket is a one
     * to many style socket, and an association was not found, then
     * the id was invalid.
     */
    asoc = sctp_id2assoc(sk, params.spp_assoc_id);
    if (!asoc && params.spp_assoc_id && sctp_style(sk, UDP))
        return -EINVAL;

    /* Heartbeat demand can only be sent on a transport or
     * association, but not a socket.
     */
    if (params.spp_flags & SPP_HB_DEMAND && !trans && !asoc)
        return -EINVAL;

    /* Process parameters. */
    error = sctp_apply_peer_addr_params(&params, trans, asoc, sp,
                        hb_change, pmtud_change,
                        sackdelay_change);

    if (error)
        return error;

    /* If changes are for association, also apply parameters to each
     * transport.
     */
    if (!trans && asoc) {
        list_for_each_entry(trans, &asoc->peer.transport_addr_list,
                transports) {
            sctp_apply_peer_addr_params(&params, trans, asoc, sp,
                            hb_change, pmtud_change,
                            sackdelay_change);
        }
    }

    return 0;
}

/*
 * 7.1.23.  Get or set delayed ack timer (SCTP_DELAYED_SACK)
 *
 * This option will effect the way delayed acks are performed.  This
 * option allows you to get or set the delayed ack time, in
 * milliseconds.  It also allows changing the delayed ack frequency.
 * Changing the frequency to 1 disables the delayed sack algorithm.  If
 * the assoc_id is 0, then this sets or gets the endpoints default
 * values.  If the assoc_id field is non-zero, then the set or get
 * effects the specified association for the one to many model (the
 * assoc_id field is ignored by the one to one model).  Note that if
 * sack_delay or sack_freq are 0 when setting this option, then the
 * current values will remain unchanged.
 *
 * struct sctp_sack_info {
 *     sctp_assoc_t            sack_assoc_id;
 *     uint32_t                sack_delay;
 *     uint32_t                sack_freq;
 * };
 *
 * sack_assoc_id -  This parameter, indicates which association the user
 *    is performing an action upon.  Note that if this field's value is
 *    zero then the endpoints default value is changed (effecting future
 *    associations only).
 *
 * sack_delay -  This parameter contains the number of milliseconds that
 *    the user is requesting the delayed ACK timer be set to.  Note that
 *    this value is defined in the standard to be between 200 and 500
 *    milliseconds.
 *
 * sack_freq -  This parameter contains the number of packets that must
 *    be received before a sack is sent without waiting for the delay
 *    timer to expire.  The default value for this is 2, setting this
 *    value to 1 will disable the delayed sack algorithm.
 */

static int sctp_setsockopt_delayed_ack(struct sock *sk,
                       char __user *optval, unsigned int optlen)
{
    struct sctp_sack_info    params;
    struct sctp_transport   *trans = NULL;
    struct sctp_association *asoc = NULL;
    struct sctp_sock        *sp = sctp_sk(sk);

    if (optlen == sizeof(struct sctp_sack_info)) {
        if (copy_from_user(&params, optval, optlen))
            return -EFAULT;

        if (params.sack_delay == 0 && params.sack_freq == 0)
            return 0;
    } else if (optlen == sizeof(struct sctp_assoc_value)) {
        pr_warn("Use of struct sctp_assoc_value in delayed_ack socket option deprecated\n");
        pr_warn("Use struct sctp_sack_info instead\n");
        if (copy_from_user(&params, optval, optlen))
            return -EFAULT;

        if (params.sack_delay == 0)
            params.sack_freq = 1;
        else
            params.sack_freq = 0;
    } else
        return - EINVAL;

    /* Validate value parameter. */
    if (params.sack_delay > 500)
        return -EINVAL;

    /* Get association, if sack_assoc_id != 0 and the socket is a one
     * to many style socket, and an association was not found, then
     * the id was invalid.
     */
    asoc = sctp_id2assoc(sk, params.sack_assoc_id);
    if (!asoc && params.sack_assoc_id && sctp_style(sk, UDP))
        return -EINVAL;

    if (params.sack_delay) {
        if (asoc) {
            asoc->sackdelay =
                msecs_to_jiffies(params.sack_delay);
            asoc->param_flags =
                (asoc->param_flags & ~SPP_SACKDELAY) |
                SPP_SACKDELAY_ENABLE;
        } else {
            sp->sackdelay = params.sack_delay;
            sp->param_flags =
                (sp->param_flags & ~SPP_SACKDELAY) |
                SPP_SACKDELAY_ENABLE;
        }
    }

    if (params.sack_freq == 1) {
        if (asoc) {
            asoc->param_flags =
                (asoc->param_flags & ~SPP_SACKDELAY) |
                SPP_SACKDELAY_DISABLE;
        } else {
            sp->param_flags =
                (sp->param_flags & ~SPP_SACKDELAY) |
                SPP_SACKDELAY_DISABLE;
        }
    } else if (params.sack_freq > 1) {
        if (asoc) {
            asoc->sackfreq = params.sack_freq;
            asoc->param_flags =
                (asoc->param_flags & ~SPP_SACKDELAY) |
                SPP_SACKDELAY_ENABLE;
        } else {
            sp->sackfreq = params.sack_freq;
            sp->param_flags =
                (sp->param_flags & ~SPP_SACKDELAY) |
                SPP_SACKDELAY_ENABLE;
        }
    }

    /* If change is for association, also apply to each transport. */
    if (asoc) {
        list_for_each_entry(trans, &asoc->peer.transport_addr_list,
                transports) {
            if (params.sack_delay) {
                trans->sackdelay =
                    msecs_to_jiffies(params.sack_delay);
                trans->param_flags =
                    (trans->param_flags & ~SPP_SACKDELAY) |
                    SPP_SACKDELAY_ENABLE;
            }
            if (params.sack_freq == 1) {
                trans->param_flags =
                    (trans->param_flags & ~SPP_SACKDELAY) |
                    SPP_SACKDELAY_DISABLE;
            } else if (params.sack_freq > 1) {
                trans->sackfreq = params.sack_freq;
                trans->param_flags =
                    (trans->param_flags & ~SPP_SACKDELAY) |
                    SPP_SACKDELAY_ENABLE;
            }
        }
    }

    return 0;
}

/* 7.1.3 Initialization Parameters (SCTP_INITMSG)
 *
 * Applications can specify protocol parameters for the default association
 * initialization.  The option name argument to setsockopt() and getsockopt()
 * is SCTP_INITMSG.
 *
 * Setting initialization parameters is effective only on an unconnected
 * socket (for UDP-style sockets only future associations are effected
 * by the change).  With TCP-style sockets, this option is inherited by
 * sockets derived from a listener socket.
 */
static int sctp_setsockopt_initmsg(struct sock *sk, char __user *optval, unsigned int optlen)
{
    struct sctp_initmsg sinit;
    struct sctp_sock *sp = sctp_sk(sk);

    if (optlen != sizeof(struct sctp_initmsg))
        return -EINVAL;
    if (copy_from_user(&sinit, optval, optlen))
        return -EFAULT;

    if (sinit.sinit_num_ostreams)
        sp->initmsg.sinit_num_ostreams = sinit.sinit_num_ostreams;
    if (sinit.sinit_max_instreams)
        sp->initmsg.sinit_max_instreams = sinit.sinit_max_instreams;
    if (sinit.sinit_max_attempts)
        sp->initmsg.sinit_max_attempts = sinit.sinit_max_attempts;
    if (sinit.sinit_max_init_timeo)
        sp->initmsg.sinit_max_init_timeo = sinit.sinit_max_init_timeo;

    return 0;
}

/*
 * 7.1.14 Set default send parameters (SCTP_DEFAULT_SEND_PARAM)
 *
 *   Applications that wish to use the sendto() system call may wish to
 *   specify a default set of parameters that would normally be supplied
 *   through the inclusion of ancillary data.  This socket option allows
 *   such an application to set the default sctp_sndrcvinfo structure.
 *   The application that wishes to use this socket option simply passes
 *   in to this call the sctp_sndrcvinfo structure defined in Section
 *   5.2.2) The input parameters accepted by this call include
 *   sinfo_stream, sinfo_flags, sinfo_ppid, sinfo_context,
 *   sinfo_timetolive.  The user must provide the sinfo_assoc_id field in
 *   to this call if the caller is using the UDP model.
 */
static int sctp_setsockopt_default_send_param(struct sock *sk,
                          char __user *optval,
                          unsigned int optlen)
{
    struct sctp_sndrcvinfo info;
    struct sctp_association *asoc;
    struct sctp_sock *sp = sctp_sk(sk);

    if (optlen != sizeof(struct sctp_sndrcvinfo))
        return -EINVAL;
    if (copy_from_user(&info, optval, optlen))
        return -EFAULT;

    asoc = sctp_id2assoc(sk, info.sinfo_assoc_id);
    if (!asoc && info.sinfo_assoc_id && sctp_style(sk, UDP))
        return -EINVAL;

    if (asoc) {
        asoc->default_stream = info.sinfo_stream;
        asoc->default_flags = info.sinfo_flags;
        asoc->default_ppid = info.sinfo_ppid;
        asoc->default_context = info.sinfo_context;
        asoc->default_timetolive = info.sinfo_timetolive;
    } else {
        sp->default_stream = info.sinfo_stream;
        sp->default_flags = info.sinfo_flags;
        sp->default_ppid = info.sinfo_ppid;
        sp->default_context = info.sinfo_context;
        sp->default_timetolive = info.sinfo_timetolive;
    }

    return 0;
}

/* 7.1.10 Set Primary Address (SCTP_PRIMARY_ADDR)
 *
 * Requests that the local SCTP stack use the enclosed peer address as
 * the association primary.  The enclosed address must be one of the
 * association peer's addresses.
 */
static int sctp_setsockopt_primary_addr(struct sock *sk, char __user *optval,
                    unsigned int optlen)
{
    struct sctp_prim prim;
    struct sctp_transport *trans;

    if (optlen != sizeof(struct sctp_prim))
        return -EINVAL;

    if (copy_from_user(&prim, optval, sizeof(struct sctp_prim)))
        return -EFAULT;

    trans = sctp_addr_id2transport(sk, &prim.ssp_addr, prim.ssp_assoc_id);
    if (!trans)
        return -EINVAL;

    sctp_assoc_set_primary(trans->asoc, trans);

    return 0;
}

/*
 * 7.1.5 SCTP_NODELAY
 *
 * Turn on/off any Nagle-like algorithm.  This means that packets are
 * generally sent as soon as possible and no unnecessary delays are
 * introduced, at the cost of more packets in the network.  Expects an
 *  integer boolean flag.
 */
static int sctp_setsockopt_nodelay(struct sock *sk, char __user *optval,
                   unsigned int optlen)
{
    int val;

    if (optlen < sizeof(int))
        return -EINVAL;
    if (get_user(val, (int __user *)optval))
        return -EFAULT;

    sctp_sk(sk)->nodelay = (val == 0) ? 0 : 1;
    return 0;
}

/*
 *
 * 7.1.1 SCTP_RTOINFO
 *
 * The protocol parameters used to initialize and bound retransmission
 * timeout (RTO) are tunable. sctp_rtoinfo structure is used to access
 * and modify these parameters.
 * All parameters are time values, in milliseconds.  A value of 0, when
 * modifying the parameters, indicates that the current value should not
 * be changed.
 *
 */
static int sctp_setsockopt_rtoinfo(struct sock *sk, char __user *optval, unsigned int optlen)
{
    struct sctp_rtoinfo rtoinfo;
    struct sctp_association *asoc;

    if (optlen != sizeof (struct sctp_rtoinfo))
        return -EINVAL;

    if (copy_from_user(&rtoinfo, optval, optlen))
        return -EFAULT;

    asoc = sctp_id2assoc(sk, rtoinfo.srto_assoc_id);

    /* Set the values to the specific association */
    if (!asoc && rtoinfo.srto_assoc_id && sctp_style(sk, UDP))
        return -EINVAL;

    if (asoc) {
        if (rtoinfo.srto_initial != 0)
            asoc->rto_initial =
                msecs_to_jiffies(rtoinfo.srto_initial);
        if (rtoinfo.srto_max != 0)
            asoc->rto_max = msecs_to_jiffies(rtoinfo.srto_max);
        if (rtoinfo.srto_min != 0)
            asoc->rto_min = msecs_to_jiffies(rtoinfo.srto_min);
    } else {
        /* If there is no association or the association-id = 0
         * set the values to the endpoint.
         */
        struct sctp_sock *sp = sctp_sk(sk);

        if (rtoinfo.srto_initial != 0)
            sp->rtoinfo.srto_initial = rtoinfo.srto_initial;
        if (rtoinfo.srto_max != 0)
            sp->rtoinfo.srto_max = rtoinfo.srto_max;
        if (rtoinfo.srto_min != 0)
            sp->rtoinfo.srto_min = rtoinfo.srto_min;
    }

    return 0;
}

/*
 *
 * 7.1.2 SCTP_ASSOCINFO
 *
 * This option is used to tune the maximum retransmission attempts
 * of the association.
 * Returns an error if the new association retransmission value is
 * greater than the sum of the retransmission value  of the peer.
 * See [SCTP] for more information.
 *
 */
static int sctp_setsockopt_associnfo(struct sock *sk, char __user *optval, unsigned int optlen)
{

    struct sctp_assocparams assocparams;
    struct sctp_association *asoc;

    if (optlen != sizeof(struct sctp_assocparams))
        return -EINVAL;
    if (copy_from_user(&assocparams, optval, optlen))
        return -EFAULT;

    asoc = sctp_id2assoc(sk, assocparams.sasoc_assoc_id);

    if (!asoc && assocparams.sasoc_assoc_id && sctp_style(sk, UDP))
        return -EINVAL;

    /* Set the values to the specific association */
    if (asoc) {
        if (assocparams.sasoc_asocmaxrxt != 0) {
            __u32 path_sum = 0;
            int   paths = 0;
            struct sctp_transport *peer_addr;

            list_for_each_entry(peer_addr, &asoc->peer.transport_addr_list,
                    transports) {
                path_sum += peer_addr->pathmaxrxt;
                paths++;
            }

            /* Only validate asocmaxrxt if we have more than
             * one path/transport.  We do this because path
             * retransmissions are only counted when we have more
             * then one path.
             */
            if (paths > 1 &&
                assocparams.sasoc_asocmaxrxt > path_sum)
                return -EINVAL;

            asoc->max_retrans = assocparams.sasoc_asocmaxrxt;
        }

        if (assocparams.sasoc_cookie_life != 0) {
            asoc->cookie_life.tv_sec =
                    assocparams.sasoc_cookie_life / 1000;
            asoc->cookie_life.tv_usec =
                    (assocparams.sasoc_cookie_life % 1000)
                    * 1000;
        }
    } else {
        /* Set the values to the endpoint */
        struct sctp_sock *sp = sctp_sk(sk);

        if (assocparams.sasoc_asocmaxrxt != 0)
            sp->assocparams.sasoc_asocmaxrxt =
                        assocparams.sasoc_asocmaxrxt;
        if (assocparams.sasoc_cookie_life != 0)
            sp->assocparams.sasoc_cookie_life =
                        assocparams.sasoc_cookie_life;
    }
    return 0;
}

/*
 * 7.1.16 Set/clear IPv4 mapped addresses (SCTP_I_WANT_MAPPED_V4_ADDR)
 *
 * This socket option is a boolean flag which turns on or off mapped V4
 * addresses.  If this option is turned on and the socket is type
 * PF_INET6, then IPv4 addresses will be mapped to V6 representation.
 * If this option is turned off, then no mapping will be done of V4
 * addresses and a user will receive both PF_INET6 and PF_INET type
 * addresses on the socket.
 */
static int sctp_setsockopt_mappedv4(struct sock *sk, char __user *optval, unsigned int optlen)
{
    int val;
    struct sctp_sock *sp = sctp_sk(sk);

    if (optlen < sizeof(int))
        return -EINVAL;
    if (get_user(val, (int __user *)optval))
        return -EFAULT;
    if (val)
        sp->v4mapped = 1;
    else
        sp->v4mapped = 0;

    return 0;
}

/*
 * 8.1.16.  Get or Set the Maximum Fragmentation Size (SCTP_MAXSEG)
 * This option will get or set the maximum size to put in any outgoing
 * SCTP DATA chunk.  If a message is larger than this size it will be
 * fragmented by SCTP into the specified size.  Note that the underlying
 * SCTP implementation may fragment into smaller sized chunks when the
 * PMTU of the underlying association is smaller than the value set by
 * the user.  The default value for this option is '0' which indicates
 * the user is NOT limiting fragmentation and only the PMTU will effect
 * SCTP's choice of DATA chunk size.  Note also that values set larger
 * than the maximum size of an IP datagram will effectively let SCTP
 * control fragmentation (i.e. the same as setting this option to 0).
 *
 * The following structure is used to access and modify this parameter:
 *
 * struct sctp_assoc_value {
 *   sctp_assoc_t assoc_id;
 *   uint32_t assoc_value;
 * };
 *
 * assoc_id:  This parameter is ignored for one-to-one style sockets.
 *    For one-to-many style sockets this parameter indicates which
 *    association the user is performing an action upon.  Note that if
 *    this field's value is zero then the endpoints default value is
 *    changed (effecting future associations only).
 * assoc_value:  This parameter specifies the maximum size in bytes.
 */
static int sctp_setsockopt_maxseg(struct sock *sk, char __user *optval, unsigned int optlen)
{
    struct sctp_assoc_value params;
    struct sctp_association *asoc;
    struct sctp_sock *sp = sctp_sk(sk);
    int val;

    if (optlen == sizeof(int)) {
        pr_warn("Use of int in maxseg socket option deprecated\n");
        pr_warn("Use struct sctp_assoc_value instead\n");
        if (copy_from_user(&val, optval, optlen))
            return -EFAULT;
        params.assoc_id = 0;
    } else if (optlen == sizeof(struct sctp_assoc_value)) {
        if (copy_from_user(&params, optval, optlen))
            return -EFAULT;
        val = params.assoc_value;
    } else
        return -EINVAL;

    if ((val != 0) && ((val < 8) || (val > SCTP_MAX_CHUNK_LEN)))
        return -EINVAL;

    asoc = sctp_id2assoc(sk, params.assoc_id);
    if (!asoc && params.assoc_id && sctp_style(sk, UDP))
        return -EINVAL;

    if (asoc) {
        if (val == 0) {
            val = asoc->pathmtu;
            val -= sp->pf->af->net_header_len;
            val -= sizeof(struct sctphdr) +
                    sizeof(struct sctp_data_chunk);
        }
        asoc->user_frag = val;
        asoc->frag_point = sctp_frag_point(asoc, asoc->pathmtu);
    } else {
        sp->user_frag = val;
    }

    return 0;
}


/*
 *  7.1.9 Set Peer Primary Address (SCTP_SET_PEER_PRIMARY_ADDR)
 *
 *   Requests that the peer mark the enclosed address as the association
 *   primary. The enclosed address must be one of the association's
 *   locally bound addresses. The following structure is used to make a
 *   set primary request:
 */
static int sctp_setsockopt_peer_primary_addr(struct sock *sk, char __user *optval,
                         unsigned int optlen)
{
    struct net *net = sock_net(sk);
    struct sctp_sock    *sp;
    struct sctp_association *asoc = NULL;
    struct sctp_setpeerprim prim;
    struct sctp_chunk   *chunk;
    struct sctp_af      *af;
    int             err;

    sp = sctp_sk(sk);

    if (!net->sctp.addip_enable)
        return -EPERM;

    if (optlen != sizeof(struct sctp_setpeerprim))
        return -EINVAL;

    if (copy_from_user(&prim, optval, optlen))
        return -EFAULT;

    asoc = sctp_id2assoc(sk, prim.sspp_assoc_id);
    if (!asoc)
        return -EINVAL;

    if (!asoc->peer.asconf_capable)
        return -EPERM;

    if (asoc->peer.addip_disabled_mask & SCTP_PARAM_SET_PRIMARY)
        return -EPERM;

    if (!sctp_state(asoc, ESTABLISHED))
        return -ENOTCONN;

    af = sctp_get_af_specific(prim.sspp_addr.ss_family);
    if (!af)
        return -EINVAL;

    if (!af->addr_valid((union sctp_addr *)&prim.sspp_addr, sp, NULL))
        return -EADDRNOTAVAIL;

    if (!sctp_assoc_lookup_laddr(asoc, (union sctp_addr *)&prim.sspp_addr))
        return -EADDRNOTAVAIL;

    /* Create an ASCONF chunk with SET_PRIMARY parameter    */
    chunk = sctp_make_asconf_set_prim(asoc,
                      (union sctp_addr *)&prim.sspp_addr);
    if (!chunk)
        return -ENOMEM;

    err = sctp_send_asconf(asoc, chunk);

    SCTP_DEBUG_PRINTK("We set peer primary addr primitively.\n");

    return err;
}

static int sctp_setsockopt_adaptation_layer(struct sock *sk, char __user *optval,
                        unsigned int optlen)
{
    struct sctp_setadaptation adaptation;

    if (optlen != sizeof(struct sctp_setadaptation))
        return -EINVAL;
    if (copy_from_user(&adaptation, optval, optlen))
        return -EFAULT;

    sctp_sk(sk)->adaptation_ind = adaptation.ssb_adaptation_ind;

    return 0;
}

/*
 * 7.1.29.  Set or Get the default context (SCTP_CONTEXT)
 *
 * The context field in the sctp_sndrcvinfo structure is normally only
 * used when a failed message is retrieved holding the value that was
 * sent down on the actual send call.  This option allows the setting of
 * a default context on an association basis that will be received on
 * reading messages from the peer.  This is especially helpful in the
 * one-2-many model for an application to keep some reference to an
 * internal state machine that is processing messages on the
 * association.  Note that the setting of this value only effects
 * received messages from the peer and does not effect the value that is
 * saved with outbound messages.
 */
static int sctp_setsockopt_context(struct sock *sk, char __user *optval,
                   unsigned int optlen)
{
    struct sctp_assoc_value params;
    struct sctp_sock *sp;
    struct sctp_association *asoc;

    if (optlen != sizeof(struct sctp_assoc_value))
        return -EINVAL;
    if (copy_from_user(&params, optval, optlen))
        return -EFAULT;

    sp = sctp_sk(sk);

    if (params.assoc_id != 0) {
        asoc = sctp_id2assoc(sk, params.assoc_id);
        if (!asoc)
            return -EINVAL;
        asoc->default_rcv_context = params.assoc_value;
    } else {
        sp->default_rcv_context = params.assoc_value;
    }

    return 0;
}

/*
 * 7.1.24.  Get or set fragmented interleave (SCTP_FRAGMENT_INTERLEAVE)
 *
 * This options will at a minimum specify if the implementation is doing
 * fragmented interleave.  Fragmented interleave, for a one to many
 * socket, is when subsequent calls to receive a message may return
 * parts of messages from different associations.  Some implementations
 * may allow you to turn this value on or off.  If so, when turned off,
 * no fragment interleave will occur (which will cause a head of line
 * blocking amongst multiple associations sharing the same one to many
 * socket).  When this option is turned on, then each receive call may
 * come from a different association (thus the user must receive data
 * with the extended calls (e.g. sctp_recvmsg) to keep track of which
 * association each receive belongs to.
 *
 * This option takes a boolean value.  A non-zero value indicates that
 * fragmented interleave is on.  A value of zero indicates that
 * fragmented interleave is off.
 *
 * Note that it is important that an implementation that allows this
 * option to be turned on, have it off by default.  Otherwise an unaware
 * application using the one to many model may become confused and act
 * incorrectly.
 */
static int sctp_setsockopt_fragment_interleave(struct sock *sk,
                           char __user *optval,
                           unsigned int optlen)
{
    int val;

    if (optlen != sizeof(int))
        return -EINVAL;
    if (get_user(val, (int __user *)optval))
        return -EFAULT;

    sctp_sk(sk)->frag_interleave = (val == 0) ? 0 : 1;

    return 0;
}

/*
 * 8.1.21.  Set or Get the SCTP Partial Delivery Point
 *       (SCTP_PARTIAL_DELIVERY_POINT)
 *
 * This option will set or get the SCTP partial delivery point.  This
 * point is the size of a message where the partial delivery API will be
 * invoked to help free up rwnd space for the peer.  Setting this to a
 * lower value will cause partial deliveries to happen more often.  The
 * calls argument is an integer that sets or gets the partial delivery
 * point.  Note also that the call will fail if the user attempts to set
 * this value larger than the socket receive buffer size.
 *
 * Note that any single message having a length smaller than or equal to
 * the SCTP partial delivery point will be delivered in one single read
 * call as long as the user provided buffer is large enough to hold the
 * message.
 */
static int sctp_setsockopt_partial_delivery_point(struct sock *sk,
                          char __user *optval,
                          unsigned int optlen)
{
    u32 val;

    if (optlen != sizeof(u32))
        return -EINVAL;
    if (get_user(val, (int __user *)optval))
        return -EFAULT;

    /* Note: We double the receive buffer from what the user sets
     * it to be, also initial rwnd is based on rcvbuf/2.
     */
    if (val > (sk->sk_rcvbuf >> 1))
        return -EINVAL;

    sctp_sk(sk)->pd_point = val;

    return 0; /* is this the right error code? */
}

/*
 * 7.1.28.  Set or Get the maximum burst (SCTP_MAX_BURST)
 *
 * This option will allow a user to change the maximum burst of packets
 * that can be emitted by this association.  Note that the default value
 * is 4, and some implementations may restrict this setting so that it
 * can only be lowered.
 *
 * NOTE: This text doesn't seem right.  Do this on a socket basis with
 * future associations inheriting the socket value.
 */
static int sctp_setsockopt_maxburst(struct sock *sk,
                    char __user *optval,
                    unsigned int optlen)
{
    struct sctp_assoc_value params;
    struct sctp_sock *sp;
    struct sctp_association *asoc;
    int val;
    int assoc_id = 0;

    if (optlen == sizeof(int)) {
        pr_warn("Use of int in max_burst socket option deprecated\n");
        pr_warn("Use struct sctp_assoc_value instead\n");
        if (copy_from_user(&val, optval, optlen))
            return -EFAULT;
    } else if (optlen == sizeof(struct sctp_assoc_value)) {
        if (copy_from_user(&params, optval, optlen))
            return -EFAULT;
        val = params.assoc_value;
        assoc_id = params.assoc_id;
    } else
        return -EINVAL;

    sp = sctp_sk(sk);

    if (assoc_id != 0) {
        asoc = sctp_id2assoc(sk, assoc_id);
        if (!asoc)
            return -EINVAL;
        asoc->max_burst = val;
    } else
        sp->max_burst = val;

    return 0;
}

/*
 * 7.1.18.  Add a chunk that must be authenticated (SCTP_AUTH_CHUNK)
 *
 * This set option adds a chunk type that the user is requesting to be
 * received only in an authenticated way.  Changes to the list of chunks
 * will only effect future associations on the socket.
 */
static int sctp_setsockopt_auth_chunk(struct sock *sk,
                      char __user *optval,
                      unsigned int optlen)
{
    struct net *net = sock_net(sk);
    struct sctp_authchunk val;

    if (!net->sctp.auth_enable)
        return -EACCES;

    if (optlen != sizeof(struct sctp_authchunk))
        return -EINVAL;
    if (copy_from_user(&val, optval, optlen))
        return -EFAULT;

    switch (val.sauth_chunk) {
    case SCTP_CID_INIT:
    case SCTP_CID_INIT_ACK:
    case SCTP_CID_SHUTDOWN_COMPLETE:
    case SCTP_CID_AUTH:
        return -EINVAL;
    }

    /* add this chunk id to the endpoint */
    return sctp_auth_ep_add_chunkid(sctp_sk(sk)->ep, val.sauth_chunk);
}

/*
 * 7.1.19.  Get or set the list of supported HMAC Identifiers (SCTP_HMAC_IDENT)
 *
 * This option gets or sets the list of HMAC algorithms that the local
 * endpoint requires the peer to use.
 */
static int sctp_setsockopt_hmac_ident(struct sock *sk,
                      char __user *optval,
                      unsigned int optlen)
{
    struct net *net = sock_net(sk);
    struct sctp_hmacalgo *hmacs;
    u32 idents;
    int err;

    if (!net->sctp.auth_enable)
        return -EACCES;

    if (optlen < sizeof(struct sctp_hmacalgo))
        return -EINVAL;

    hmacs= memdup_user(optval, optlen);
    if (IS_ERR(hmacs))
        return PTR_ERR(hmacs);

    idents = hmacs->shmac_num_idents;
    if (idents == 0 || idents > SCTP_AUTH_NUM_HMACS ||
        (idents * sizeof(u16)) > (optlen - sizeof(struct sctp_hmacalgo))) {
        err = -EINVAL;
        goto out;
    }

    err = sctp_auth_ep_set_hmacs(sctp_sk(sk)->ep, hmacs);
out:
    kfree(hmacs);
    return err;
}

/*
 * 7.1.20.  Set a shared key (SCTP_AUTH_KEY)
 *
 * This option will set a shared secret key which is used to build an
 * association shared key.
 */
static int sctp_setsockopt_auth_key(struct sock *sk,
                    char __user *optval,
                    unsigned int optlen)
{
    struct net *net = sock_net(sk);
    struct sctp_authkey *authkey;
    struct sctp_association *asoc;
    int ret;

    if (!net->sctp.auth_enable)
        return -EACCES;

    if (optlen <= sizeof(struct sctp_authkey))
        return -EINVAL;

    authkey= memdup_user(optval, optlen);
    if (IS_ERR(authkey))
        return PTR_ERR(authkey);

    if (authkey->sca_keylength > optlen - sizeof(struct sctp_authkey)) {
        ret = -EINVAL;
        goto out;
    }

    asoc = sctp_id2assoc(sk, authkey->sca_assoc_id);
    if (!asoc && authkey->sca_assoc_id && sctp_style(sk, UDP)) {
        ret = -EINVAL;
        goto out;
    }

    ret = sctp_auth_set_key(sctp_sk(sk)->ep, asoc, authkey);
out:
    kfree(authkey);
    return ret;
}

/*
 * 7.1.21.  Get or set the active shared key (SCTP_AUTH_ACTIVE_KEY)
 *
 * This option will get or set the active shared key to be used to build
 * the association shared key.
 */
static int sctp_setsockopt_active_key(struct sock *sk,
                      char __user *optval,
                      unsigned int optlen)
{
    struct net *net = sock_net(sk);
    struct sctp_authkeyid val;
    struct sctp_association *asoc;

    if (!net->sctp.auth_enable)
        return -EACCES;

    if (optlen != sizeof(struct sctp_authkeyid))
        return -EINVAL;
    if (copy_from_user(&val, optval, optlen))
        return -EFAULT;

    asoc = sctp_id2assoc(sk, val.scact_assoc_id);
    if (!asoc && val.scact_assoc_id && sctp_style(sk, UDP))
        return -EINVAL;

    return sctp_auth_set_active_key(sctp_sk(sk)->ep, asoc,
                    val.scact_keynumber);
}

/*
 * 7.1.22.  Delete a shared key (SCTP_AUTH_DELETE_KEY)
 *
 * This set option will delete a shared secret key from use.
 */
static int sctp_setsockopt_del_key(struct sock *sk,
                   char __user *optval,
                   unsigned int optlen)
{
    struct net *net = sock_net(sk);
    struct sctp_authkeyid val;
    struct sctp_association *asoc;

    if (!net->sctp.auth_enable)
        return -EACCES;

    if (optlen != sizeof(struct sctp_authkeyid))
        return -EINVAL;
    if (copy_from_user(&val, optval, optlen))
        return -EFAULT;

    asoc = sctp_id2assoc(sk, val.scact_assoc_id);
    if (!asoc && val.scact_assoc_id && sctp_style(sk, UDP))
        return -EINVAL;

    return sctp_auth_del_key_id(sctp_sk(sk)->ep, asoc,
                    val.scact_keynumber);

}

/*
 * 8.1.23 SCTP_AUTO_ASCONF
 *
 * This option will enable or disable the use of the automatic generation of
 * ASCONF chunks to add and delete addresses to an existing association.  Note
 * that this option has two caveats namely: a) it only affects sockets that
 * are bound to all addresses available to the SCTP stack, and b) the system
 * administrator may have an overriding control that turns the ASCONF feature
 * off no matter what setting the socket option may have.
 * This option expects an integer boolean flag, where a non-zero value turns on
 * the option, and a zero value turns off the option.
 * Note. In this implementation, socket operation overrides default parameter
 * being set by sysctl as well as FreeBSD implementation
 */
static int sctp_setsockopt_auto_asconf(struct sock *sk, char __user *optval,
                    unsigned int optlen)
{
    int val;
    struct sctp_sock *sp = sctp_sk(sk);

    if (optlen < sizeof(int))
        return -EINVAL;
    if (get_user(val, (int __user *)optval))
        return -EFAULT;
    if (!sctp_is_ep_boundall(sk) && val)
        return -EINVAL;
    if ((val && sp->do_auto_asconf) || (!val && !sp->do_auto_asconf))
        return 0;

    if (val == 0 && sp->do_auto_asconf) {
        list_del(&sp->auto_asconf_list);
        sp->do_auto_asconf = 0;
    } else if (val && !sp->do_auto_asconf) {
        list_add_tail(&sp->auto_asconf_list,
            &sock_net(sk)->sctp.auto_asconf_splist);
        sp->do_auto_asconf = 1;
    }
    return 0;
}


/*
 * SCTP_PEER_ADDR_THLDS
 *
 * This option allows us to alter the partially failed threshold for one or all
 * transports in an association.  See Section 6.1 of:
 * http://www.ietf.org/id/draft-nishida-tsvwg-sctp-failover-05.txt
 */
static int sctp_setsockopt_paddr_thresholds(struct sock *sk,
                        char __user *optval,
                        unsigned int optlen)
{
    struct sctp_paddrthlds val;
    struct sctp_transport *trans;
    struct sctp_association *asoc;

    if (optlen < sizeof(struct sctp_paddrthlds))
        return -EINVAL;
    if (copy_from_user(&val, (struct sctp_paddrthlds __user *)optval,
               sizeof(struct sctp_paddrthlds)))
        return -EFAULT;


    if (sctp_is_any(sk, (const union sctp_addr *)&val.spt_address)) {
        asoc = sctp_id2assoc(sk, val.spt_assoc_id);
        if (!asoc)
            return -ENOENT;
        list_for_each_entry(trans, &asoc->peer.transport_addr_list,
                    transports) {
            if (val.spt_pathmaxrxt)
                trans->pathmaxrxt = val.spt_pathmaxrxt;
            trans->pf_retrans = val.spt_pathpfthld;
        }

        if (val.spt_pathmaxrxt)
            asoc->pathmaxrxt = val.spt_pathmaxrxt;
        asoc->pf_retrans = val.spt_pathpfthld;
    } else {
        trans = sctp_addr_id2transport(sk, &val.spt_address,
                           val.spt_assoc_id);
        if (!trans)
            return -ENOENT;

        if (val.spt_pathmaxrxt)
            trans->pathmaxrxt = val.spt_pathmaxrxt;
        trans->pf_retrans = val.spt_pathpfthld;
    }

    return 0;
}

/* API 6.2 setsockopt(), getsockopt()
 *
 * Applications use setsockopt() and getsockopt() to set or retrieve
 * socket options.  Socket options are used to change the default
 * behavior of sockets calls.  They are described in Section 7.
 *
 * The syntax is:
 *
 *   ret = getsockopt(int sd, int level, int optname, void __user *optval,
 *                    int __user *optlen);
 *   ret = setsockopt(int sd, int level, int optname, const void __user *optval,
 *                    int optlen);
 *
 *   sd      - the socket descript.
 *   level   - set to IPPROTO_SCTP for all SCTP options.
 *   optname - the option name.
 *   optval  - the buffer to store the value of the option.
 *   optlen  - the size of the buffer.
 */
SCTP_STATIC int sctp_setsockopt(struct sock *sk, int level, int optname,
                char __user *optval, unsigned int optlen)
{
    int retval = 0;

    SCTP_DEBUG_PRINTK("sctp_setsockopt(sk: %p... optname: %d)\n",
              sk, optname);

    /* I can hardly begin to describe how wrong this is.  This is
     * so broken as to be worse than useless.  The API draft
     * REALLY is NOT helpful here...  I am not convinced that the
     * semantics of setsockopt() with a level OTHER THAN SOL_SCTP
     * are at all well-founded.
     */
    if (level != SOL_SCTP) {
        struct sctp_af *af = sctp_sk(sk)->pf->af;
        retval = af->setsockopt(sk, level, optname, optval, optlen);
        goto out_nounlock;
    }

    sctp_lock_sock(sk);

    switch (optname) {
    case SCTP_SOCKOPT_BINDX_ADD:
        /* 'optlen' is the size of the addresses buffer. */
        retval = sctp_setsockopt_bindx(sk, (struct sockaddr __user *)optval,
                           optlen, SCTP_BINDX_ADD_ADDR);
        break;

    case SCTP_SOCKOPT_BINDX_REM:
        /* 'optlen' is the size of the addresses buffer. */
        retval = sctp_setsockopt_bindx(sk, (struct sockaddr __user *)optval,
                           optlen, SCTP_BINDX_REM_ADDR);
        break;

    case SCTP_SOCKOPT_CONNECTX_OLD:
        /* 'optlen' is the size of the addresses buffer. */
        retval = sctp_setsockopt_connectx_old(sk,
                        (struct sockaddr __user *)optval,
                        optlen);
        break;

    case SCTP_SOCKOPT_CONNECTX:
        /* 'optlen' is the size of the addresses buffer. */
        retval = sctp_setsockopt_connectx(sk,
                        (struct sockaddr __user *)optval,
                        optlen);
        break;

    case SCTP_DISABLE_FRAGMENTS:
        retval = sctp_setsockopt_disable_fragments(sk, optval, optlen);
        break;

    case SCTP_EVENTS:
        retval = sctp_setsockopt_events(sk, optval, optlen);
        break;

    case SCTP_AUTOCLOSE:
        retval = sctp_setsockopt_autoclose(sk, optval, optlen);
        break;

    case SCTP_PEER_ADDR_PARAMS:
        retval = sctp_setsockopt_peer_addr_params(sk, optval, optlen);
        break;

    case SCTP_DELAYED_SACK:
        retval = sctp_setsockopt_delayed_ack(sk, optval, optlen);
        break;
    case SCTP_PARTIAL_DELIVERY_POINT:
        retval = sctp_setsockopt_partial_delivery_point(sk, optval, optlen);
        break;

    case SCTP_INITMSG:
        retval = sctp_setsockopt_initmsg(sk, optval, optlen);
        break;
    case SCTP_DEFAULT_SEND_PARAM:
        retval = sctp_setsockopt_default_send_param(sk, optval,
                                optlen);
        break;
    case SCTP_PRIMARY_ADDR:
        retval = sctp_setsockopt_primary_addr(sk, optval, optlen);
        break;
    case SCTP_SET_PEER_PRIMARY_ADDR:
        retval = sctp_setsockopt_peer_primary_addr(sk, optval, optlen);
        break;
    case SCTP_NODELAY:
        retval = sctp_setsockopt_nodelay(sk, optval, optlen);
        break;
    case SCTP_RTOINFO:
        retval = sctp_setsockopt_rtoinfo(sk, optval, optlen);
        break;
    case SCTP_ASSOCINFO:
        retval = sctp_setsockopt_associnfo(sk, optval, optlen);
        break;
    case SCTP_I_WANT_MAPPED_V4_ADDR:
        retval = sctp_setsockopt_mappedv4(sk, optval, optlen);
        break;
    case SCTP_MAXSEG:
        retval = sctp_setsockopt_maxseg(sk, optval, optlen);
        break;
    case SCTP_ADAPTATION_LAYER:
        retval = sctp_setsockopt_adaptation_layer(sk, optval, optlen);
        break;
    case SCTP_CONTEXT:
        retval = sctp_setsockopt_context(sk, optval, optlen);
        break;
    case SCTP_FRAGMENT_INTERLEAVE:
        retval = sctp_setsockopt_fragment_interleave(sk, optval, optlen);
        break;
    case SCTP_MAX_BURST:
        retval = sctp_setsockopt_maxburst(sk, optval, optlen);
        break;
    case SCTP_AUTH_CHUNK:
        retval = sctp_setsockopt_auth_chunk(sk, optval, optlen);
        break;
    case SCTP_HMAC_IDENT:
        retval = sctp_setsockopt_hmac_ident(sk, optval, optlen);
        break;
    case SCTP_AUTH_KEY:
        retval = sctp_setsockopt_auth_key(sk, optval, optlen);
        break;
    case SCTP_AUTH_ACTIVE_KEY:
        retval = sctp_setsockopt_active_key(sk, optval, optlen);
        break;
    case SCTP_AUTH_DELETE_KEY:
        retval = sctp_setsockopt_del_key(sk, optval, optlen);
        break;
    case SCTP_AUTO_ASCONF:
        retval = sctp_setsockopt_auto_asconf(sk, optval, optlen);
        break;
    case SCTP_PEER_ADDR_THLDS:
        retval = sctp_setsockopt_paddr_thresholds(sk, optval, optlen);
        break;
    default:
        retval = -ENOPROTOOPT;
        break;
    }

    sctp_release_sock(sk);

out_nounlock:
    return retval;
}

/* API 3.1.6 connect() - UDP Style Syntax
 *
 * An application may use the connect() call in the UDP model to initiate an
 * association without sending data.
 *
 * The syntax is:
 *
 * ret = connect(int sd, const struct sockaddr *nam, socklen_t len);
 *
 * sd: the socket descriptor to have a new association added to.
 *
 * nam: the address structure (either struct sockaddr_in or struct
 *    sockaddr_in6 defined in RFC2553 [7]).
 *
 * len: the size of the address.
 */
SCTP_STATIC int sctp_connect(struct sock *sk, struct sockaddr *addr,
                 int addr_len)
{
    int err = 0;
    struct sctp_af *af;

    sctp_lock_sock(sk);

    SCTP_DEBUG_PRINTK("%s - sk: %p, sockaddr: %p, addr_len: %d\n",
              __func__, sk, addr, addr_len);

    /* Validate addr_len before calling common connect/connectx routine. */
    af = sctp_get_af_specific(addr->sa_family);
    if (!af || addr_len < af->sockaddr_len) {
        err = -EINVAL;
    } else {
        /* Pass correct addr len to common routine (so it knows there
         * is only one address being passed.
         */
        err = __sctp_connect(sk, addr, af->sockaddr_len, NULL);
    }

    sctp_release_sock(sk);
    return err;
}

/* FIXME: Write comments. */
SCTP_STATIC int sctp_disconnect(struct sock *sk, int flags)
{
    return -EOPNOTSUPP; /* STUB */
}

/* 4.1.4 accept() - TCP Style Syntax
 *
 * Applications use accept() call to remove an established SCTP
 * association from the accept queue of the endpoint.  A new socket
 * descriptor will be returned from accept() to represent the newly
 * formed association.
 */
SCTP_STATIC struct sock *sctp_accept(struct sock *sk, int flags, int *err)
{
    struct sctp_sock *sp;
    struct sctp_endpoint *ep;
    struct sock *newsk = NULL;
    struct sctp_association *asoc;
    long timeo;
    int error = 0;

    sctp_lock_sock(sk);

    sp = sctp_sk(sk);
    ep = sp->ep;

    if (!sctp_style(sk, TCP)) {
        error = -EOPNOTSUPP;
        goto out;
    }

    if (!sctp_sstate(sk, LISTENING)) {
        error = -EINVAL;
        goto out;
    }

    timeo = sock_rcvtimeo(sk, flags & O_NONBLOCK);

    error = sctp_wait_for_accept(sk, timeo);
    if (error)
        goto out;

    /* We treat the list of associations on the endpoint as the accept
     * queue and pick the first association on the list.
     */
    asoc = list_entry(ep->asocs.next, struct sctp_association, asocs);

    newsk = sp->pf->create_accept_sk(sk, asoc);
    if (!newsk) {
        error = -ENOMEM;
        goto out;
    }

    /* Populate the fields of the newsk from the oldsk and migrate the
     * asoc to the newsk.
     */
    sctp_sock_migrate(sk, newsk, asoc, SCTP_SOCKET_TCP);

out:
    sctp_release_sock(sk);
    *err = error;
    return newsk;
}

/* The SCTP ioctl handler. */
SCTP_STATIC int sctp_ioctl(struct sock *sk, int cmd, unsigned long arg)
{
    int rc = -ENOTCONN;

    sctp_lock_sock(sk);

    /*
     * SEQPACKET-style sockets in LISTENING state are valid, for
     * SCTP, so only discard TCP-style sockets in LISTENING state.
     */
    if (sctp_style(sk, TCP) && sctp_sstate(sk, LISTENING))
        goto out;

    switch (cmd) {
    case SIOCINQ: {
        struct sk_buff *skb;
        unsigned int amount = 0;

        skb = skb_peek(&sk->sk_receive_queue);
        if (skb != NULL) {
            /*
             * We will only return the amount of this packet since
             * that is all that will be read.
             */
            amount = skb->len;
        }
        rc = put_user(amount, (int __user *)arg);
        break;
    }
    default:
        rc = -ENOIOCTLCMD;
        break;
    }
out:
    sctp_release_sock(sk);
    return rc;
}

/* This is the function which gets called during socket creation to
 * initialized the SCTP-specific portion of the sock.
 * The sock structure should already be zero-filled memory.
 */
SCTP_STATIC int sctp_init_sock(struct sock *sk)
{
    struct net *net = sock_net(sk);
    struct sctp_endpoint *ep;
    struct sctp_sock *sp;

    SCTP_DEBUG_PRINTK("sctp_init_sock(sk: %p)\n", sk);

    sp = sctp_sk(sk);

    /* Initialize the SCTP per socket area.  */
    switch (sk->sk_type) {
    case SOCK_SEQPACKET:
        sp->type = SCTP_SOCKET_UDP;
        break;
    case SOCK_STREAM:
        sp->type = SCTP_SOCKET_TCP;
        break;
    default:
        return -ESOCKTNOSUPPORT;
    }

    /* Initialize default send parameters. These parameters can be
     * modified with the SCTP_DEFAULT_SEND_PARAM socket option.
     */
    sp->default_stream = 0;
    sp->default_ppid = 0;
    sp->default_flags = 0;
    sp->default_context = 0;
    sp->default_timetolive = 0;

    sp->default_rcv_context = 0;
    sp->max_burst = net->sctp.max_burst;

    /* Initialize default setup parameters. These parameters
     * can be modified with the SCTP_INITMSG socket option or
     * overridden by the SCTP_INIT CMSG.
     */
    sp->initmsg.sinit_num_ostreams   = sctp_max_outstreams;
    sp->initmsg.sinit_max_instreams  = sctp_max_instreams;
    sp->initmsg.sinit_max_attempts   = net->sctp.max_retrans_init;
    sp->initmsg.sinit_max_init_timeo = net->sctp.rto_max;

    /* Initialize default RTO related parameters.  These parameters can
     * be modified for with the SCTP_RTOINFO socket option.
     */
    sp->rtoinfo.srto_initial = net->sctp.rto_initial;
    sp->rtoinfo.srto_max     = net->sctp.rto_max;
    sp->rtoinfo.srto_min     = net->sctp.rto_min;

    /* Initialize default association related parameters. These parameters
     * can be modified with the SCTP_ASSOCINFO socket option.
     */
    sp->assocparams.sasoc_asocmaxrxt = net->sctp.max_retrans_association;
    sp->assocparams.sasoc_number_peer_destinations = 0;
    sp->assocparams.sasoc_peer_rwnd = 0;
    sp->assocparams.sasoc_local_rwnd = 0;
    sp->assocparams.sasoc_cookie_life = net->sctp.valid_cookie_life;

    /* Initialize default event subscriptions. By default, all the
     * options are off.
     */
    memset(&sp->subscribe, 0, sizeof(struct sctp_event_subscribe));

    /* Default Peer Address Parameters.  These defaults can
     * be modified via SCTP_PEER_ADDR_PARAMS
     */
    sp->hbinterval  = net->sctp.hb_interval;
    sp->pathmaxrxt  = net->sctp.max_retrans_path;
    sp->pathmtu     = 0; // allow default discovery
    sp->sackdelay   = net->sctp.sack_timeout;
    sp->sackfreq    = 2;
    sp->param_flags = SPP_HB_ENABLE |
              SPP_PMTUD_ENABLE |
              SPP_SACKDELAY_ENABLE;

    /* If enabled no SCTP message fragmentation will be performed.
     * Configure through SCTP_DISABLE_FRAGMENTS socket option.
     */
    sp->disable_fragments = 0;

    /* Enable Nagle algorithm by default.  */
    sp->nodelay           = 0;

    /* Enable by default. */
    sp->v4mapped          = 1;

    /* Auto-close idle associations after the configured
     * number of seconds.  A value of 0 disables this
     * feature.  Configure through the SCTP_AUTOCLOSE socket option,
     * for UDP-style sockets only.
     */
    sp->autoclose         = 0;

    /* User specified fragmentation limit. */
    sp->user_frag         = 0;

    sp->adaptation_ind = 0;

    sp->pf = sctp_get_pf_specific(sk->sk_family);

    /* Control variables for partial data delivery. */
    atomic_set(&sp->pd_mode, 0);
    skb_queue_head_init(&sp->pd_lobby);
    sp->frag_interleave = 0;

    /* Create a per socket endpoint structure.  Even if we
     * change the data structure relationships, this may still
     * be useful for storing pre-connect address information.
     */
    ep = sctp_endpoint_new(sk, GFP_KERNEL);
    if (!ep)
        return -ENOMEM;

    sp->ep = ep;
    sp->hmac = NULL;

    SCTP_DBG_OBJCNT_INC(sock);

    local_bh_disable();
    percpu_counter_inc(&sctp_sockets_allocated);
    sock_prot_inuse_add(net, sk->sk_prot, 1);
    if (net->sctp.default_auto_asconf) {
        list_add_tail(&sp->auto_asconf_list,
            &net->sctp.auto_asconf_splist);
        sp->do_auto_asconf = 1;
    } else
        sp->do_auto_asconf = 0;
    local_bh_enable();

    return 0;
}

/* Cleanup any SCTP per socket resources.  */
SCTP_STATIC void sctp_destroy_sock(struct sock *sk)
{
    struct sctp_sock *sp;

    SCTP_DEBUG_PRINTK("sctp_destroy_sock(sk: %p)\n", sk);

    /* Release our hold on the endpoint. */
    sp = sctp_sk(sk);
    if (sp->do_auto_asconf) {
        sp->do_auto_asconf = 0;
        list_del(&sp->auto_asconf_list);
    }
    sctp_endpoint_free(sp->ep);
    local_bh_disable();
    percpu_counter_dec(&sctp_sockets_allocated);
    sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
    local_bh_enable();
}

/* API 4.1.7 shutdown() - TCP Style Syntax
 *     int shutdown(int socket, int how);
 *
 *     sd      - the socket descriptor of the association to be closed.
 *     how     - Specifies the type of shutdown.  The  values  are
 *               as follows:
 *               SHUT_RD
 *                     Disables further receive operations. No SCTP
 *                     protocol action is taken.
 *               SHUT_WR
 *                     Disables further send operations, and initiates
 *                     the SCTP shutdown sequence.
 *               SHUT_RDWR
 *                     Disables further send  and  receive  operations
 *                     and initiates the SCTP shutdown sequence.
 */
SCTP_STATIC void sctp_shutdown(struct sock *sk, int how)
{
    struct net *net = sock_net(sk);
    struct sctp_endpoint *ep;
    struct sctp_association *asoc;

    if (!sctp_style(sk, TCP))
        return;

    if (how & SEND_SHUTDOWN) {
        ep = sctp_sk(sk)->ep;
        if (!list_empty(&ep->asocs)) {
            asoc = list_entry(ep->asocs.next,
                      struct sctp_association, asocs);
            sctp_primitive_SHUTDOWN(net, asoc, NULL);
        }
    }
}

/* 7.2.1 Association Status (SCTP_STATUS)

 * Applications can retrieve current status information about an
 * association, including association state, peer receiver window size,
 * number of unacked data chunks, and number of data chunks pending
 * receipt.  This information is read-only.
 */
static int sctp_getsockopt_sctp_status(struct sock *sk, int len,
                       char __user *optval,
                       int __user *optlen)
{
    struct sctp_status status;
    struct sctp_association *asoc = NULL;
    struct sctp_transport *transport;
    sctp_assoc_t associd;
    int retval = 0;

    if (len < sizeof(status)) {
        retval = -EINVAL;
        goto out;
    }

    len = sizeof(status);
    if (copy_from_user(&status, optval, len)) {
        retval = -EFAULT;
        goto out;
    }

    associd = status.sstat_assoc_id;
    asoc = sctp_id2assoc(sk, associd);
    if (!asoc) {
        retval = -EINVAL;
        goto out;
    }

    transport = asoc->peer.primary_path;

    status.sstat_assoc_id = sctp_assoc2id(asoc);
    status.sstat_state = asoc->state;
    status.sstat_rwnd =  asoc->peer.rwnd;
    status.sstat_unackdata = asoc->unack_data;

    status.sstat_penddata = sctp_tsnmap_pending(&asoc->peer.tsn_map);
    status.sstat_instrms = asoc->c.sinit_max_instreams;
    status.sstat_outstrms = asoc->c.sinit_num_ostreams;
    status.sstat_fragmentation_point = asoc->frag_point;
    status.sstat_primary.spinfo_assoc_id = sctp_assoc2id(transport->asoc);
    memcpy(&status.sstat_primary.spinfo_address, &transport->ipaddr,
            transport->af_specific->sockaddr_len);
    /* Map ipv4 address into v4-mapped-on-v6 address.  */
    sctp_get_pf_specific(sk->sk_family)->addr_v4map(sctp_sk(sk),
        (union sctp_addr *)&status.sstat_primary.spinfo_address);
    status.sstat_primary.spinfo_state = transport->state;
    status.sstat_primary.spinfo_cwnd = transport->cwnd;
    status.sstat_primary.spinfo_srtt = transport->srtt;
    status.sstat_primary.spinfo_rto = jiffies_to_msecs(transport->rto);
    status.sstat_primary.spinfo_mtu = transport->pathmtu;

    if (status.sstat_primary.spinfo_state == SCTP_UNKNOWN)
        status.sstat_primary.spinfo_state = SCTP_ACTIVE;

    if (put_user(len, optlen)) {
        retval = -EFAULT;
        goto out;
    }

    SCTP_DEBUG_PRINTK("sctp_getsockopt_sctp_status(%d): %d %d %d\n",
              len, status.sstat_state, status.sstat_rwnd,
              status.sstat_assoc_id);

    if (copy_to_user(optval, &status, len)) {
        retval = -EFAULT;
        goto out;
    }

out:
    return retval;
}


/* 7.2.2 Peer Address Information (SCTP_GET_PEER_ADDR_INFO)
 *
 * Applications can retrieve information about a specific peer address
 * of an association, including its reachability state, congestion
 * window, and retransmission timer values.  This information is
 * read-only.
 */
static int sctp_getsockopt_peer_addr_info(struct sock *sk, int len,
                      char __user *optval,
                      int __user *optlen)
{
    struct sctp_paddrinfo pinfo;
    struct sctp_transport *transport;
    int retval = 0;

    if (len < sizeof(pinfo)) {
        retval = -EINVAL;
        goto out;
    }

    len = sizeof(pinfo);
    if (copy_from_user(&pinfo, optval, len)) {
        retval = -EFAULT;
        goto out;
    }

    transport = sctp_addr_id2transport(sk, &pinfo.spinfo_address,
                       pinfo.spinfo_assoc_id);
    if (!transport)
        return -EINVAL;

    pinfo.spinfo_assoc_id = sctp_assoc2id(transport->asoc);
    pinfo.spinfo_state = transport->state;
    pinfo.spinfo_cwnd = transport->cwnd;
    pinfo.spinfo_srtt = transport->srtt;
    pinfo.spinfo_rto = jiffies_to_msecs(transport->rto);
    pinfo.spinfo_mtu = transport->pathmtu;

    if (pinfo.spinfo_state == SCTP_UNKNOWN)
        pinfo.spinfo_state = SCTP_ACTIVE;

    if (put_user(len, optlen)) {
        retval = -EFAULT;
        goto out;
    }

    if (copy_to_user(optval, &pinfo, len)) {
        retval = -EFAULT;
        goto out;
    }

out:
    return retval;
}

/* 7.1.12 Enable/Disable message fragmentation (SCTP_DISABLE_FRAGMENTS)
 *
 * This option is a on/off flag.  If enabled no SCTP message
 * fragmentation will be performed.  Instead if a message being sent
 * exceeds the current PMTU size, the message will NOT be sent and
 * instead a error will be indicated to the user.
 */
static int sctp_getsockopt_disable_fragments(struct sock *sk, int len,
                    char __user *optval, int __user *optlen)
{
    int val;

    if (len < sizeof(int))
        return -EINVAL;

    len = sizeof(int);
    val = (sctp_sk(sk)->disable_fragments == 1);
    if (put_user(len, optlen))
        return -EFAULT;
    if (copy_to_user(optval, &val, len))
        return -EFAULT;
    return 0;
}

/* 7.1.15 Set notification and ancillary events (SCTP_EVENTS)
 *
 * This socket option is used to specify various notifications and
 * ancillary data the user wishes to receive.
 */
static int sctp_getsockopt_events(struct sock *sk, int len, char __user *optval,
                  int __user *optlen)
{
    if (len <= 0)
        return -EINVAL;
    if (len > sizeof(struct sctp_event_subscribe))
        len = sizeof(struct sctp_event_subscribe);
    if (put_user(len, optlen))
        return -EFAULT;
    if (copy_to_user(optval, &sctp_sk(sk)->subscribe, len))
        return -EFAULT;
    return 0;
}

/* 7.1.8 Automatic Close of associations (SCTP_AUTOCLOSE)
 *
 * This socket option is applicable to the UDP-style socket only.  When
 * set it will cause associations that are idle for more than the
 * specified number of seconds to automatically close.  An association
 * being idle is defined an association that has NOT sent or received
 * user data.  The special value of '0' indicates that no automatic
 * close of any associations should be performed.  The option expects an
 * integer defining the number of seconds of idle time before an
 * association is closed.
 */
static int sctp_getsockopt_autoclose(struct sock *sk, int len, char __user *optval, int __user *optlen)
{
    /* Applicable to UDP-style socket only */
    if (sctp_style(sk, TCP))
        return -EOPNOTSUPP;
    if (len < sizeof(int))
        return -EINVAL;
    len = sizeof(int);
    if (put_user(len, optlen))
        return -EFAULT;
    if (copy_to_user(optval, &sctp_sk(sk)->autoclose, sizeof(int)))
        return -EFAULT;
    return 0;
}

/* Helper routine to branch off an association to a new socket.  */
int sctp_do_peeloff(struct sock *sk, sctp_assoc_t id, struct socket **sockp)
{
    struct sctp_association *asoc = sctp_id2assoc(sk, id);
    struct socket *sock;
    struct sctp_af *af;
    int err = 0;

    if (!asoc)
        return -EINVAL;

    /* An association cannot be branched off from an already peeled-off
     * socket, nor is this supported for tcp style sockets.
     */
    if (!sctp_style(sk, UDP))
        return -EINVAL;

    /* Create a new socket.  */
    err = sock_create(sk->sk_family, SOCK_SEQPACKET, IPPROTO_SCTP, &sock);
    if (err < 0)
        return err;

    sctp_copy_sock(sock->sk, sk, asoc);

    /* Make peeled-off sockets more like 1-1 accepted sockets.
     * Set the daddr and initialize id to something more random
     */
    af = sctp_get_af_specific(asoc->peer.primary_addr.sa.sa_family);
    af->to_sk_daddr(&asoc->peer.primary_addr, sk);

    /* Populate the fields of the newsk from the oldsk and migrate the
     * asoc to the newsk.
     */
    sctp_sock_migrate(sk, sock->sk, asoc, SCTP_SOCKET_UDP_HIGH_BANDWIDTH);

    *sockp = sock;

    return err;
}
EXPORT_SYMBOL(sctp_do_peeloff);

static int sctp_getsockopt_peeloff(struct sock *sk, int len, char __user *optval, int __user *optlen)
{
    sctp_peeloff_arg_t peeloff;
    struct socket *newsock;
    struct file *newfile;
    int retval = 0;

    if (len < sizeof(sctp_peeloff_arg_t))
        return -EINVAL;
    len = sizeof(sctp_peeloff_arg_t);
    if (copy_from_user(&peeloff, optval, len))
        return -EFAULT;

    retval = sctp_do_peeloff(sk, peeloff.associd, &newsock);
    if (retval < 0)
        goto out;

    /* Map the socket to an unused fd that can be returned to the user.  */
    retval = get_unused_fd();
    if (retval < 0) {
        sock_release(newsock);
        goto out;
    }

    newfile = sock_alloc_file(newsock, 0, NULL);
    if (unlikely(IS_ERR(newfile))) {
        put_unused_fd(retval);
        sock_release(newsock);
        return PTR_ERR(newfile);
    }

    SCTP_DEBUG_PRINTK("%s: sk: %p newsk: %p sd: %d\n",
              __func__, sk, newsock->sk, retval);

    /* Return the fd mapped to the new socket.  */
    if (put_user(len, optlen)) {
        fput(newfile);
        put_unused_fd(retval);
        return -EFAULT;
    }
    peeloff.sd = retval;
    if (copy_to_user(optval, &peeloff, len)) {
        fput(newfile);
        put_unused_fd(retval);
        return -EFAULT;
    }
    fd_install(retval, newfile);
out:
    return retval;
}

/* 7.1.13 Peer Address Parameters (SCTP_PEER_ADDR_PARAMS)
 *
 * Applications can enable or disable heartbeats for any peer address of
 * an association, modify an address's heartbeat interval, force a
 * heartbeat to be sent immediately, and adjust the address's maximum
 * number of retransmissions sent before an address is considered
 * unreachable.  The following structure is used to access and modify an
 * address's parameters:
 *
 *  struct sctp_paddrparams {
 *     sctp_assoc_t            spp_assoc_id;
 *     struct sockaddr_storage spp_address;
 *     uint32_t                spp_hbinterval;
 *     uint16_t                spp_pathmaxrxt;
 *     uint32_t                spp_pathmtu;
 *     uint32_t                spp_sackdelay;
 *     uint32_t                spp_flags;
 * };
 *
 *   spp_assoc_id    - (one-to-many style socket) This is filled in the
 *                     application, and identifies the association for
 *                     this query.
 *   spp_address     - This specifies which address is of interest.
 *   spp_hbinterval  - This contains the value of the heartbeat interval,
 *                     in milliseconds.  If a  value of zero
 *                     is present in this field then no changes are to
 *                     be made to this parameter.
 *   spp_pathmaxrxt  - This contains the maximum number of
 *                     retransmissions before this address shall be
 *                     considered unreachable. If a  value of zero
 *                     is present in this field then no changes are to
 *                     be made to this parameter.
 *   spp_pathmtu     - When Path MTU discovery is disabled the value
 *                     specified here will be the "fixed" path mtu.
 *                     Note that if the spp_address field is empty
 *                     then all associations on this address will
 *                     have this fixed path mtu set upon them.
 *
 *   spp_sackdelay   - When delayed sack is enabled, this value specifies
 *                     the number of milliseconds that sacks will be delayed
 *                     for. This value will apply to all addresses of an
 *                     association if the spp_address field is empty. Note
 *                     also, that if delayed sack is enabled and this
 *                     value is set to 0, no change is made to the last
 *                     recorded delayed sack timer value.
 *
 *   spp_flags       - These flags are used to control various features
 *                     on an association. The flag field may contain
 *                     zero or more of the following options.
 *
 *                     SPP_HB_ENABLE  - Enable heartbeats on the
 *                     specified address. Note that if the address
 *                     field is empty all addresses for the association
 *                     have heartbeats enabled upon them.
 *
 *                     SPP_HB_DISABLE - Disable heartbeats on the
 *                     speicifed address. Note that if the address
 *                     field is empty all addresses for the association
 *                     will have their heartbeats disabled. Note also
 *                     that SPP_HB_ENABLE and SPP_HB_DISABLE are
 *                     mutually exclusive, only one of these two should
 *                     be specified. Enabling both fields will have
 *                     undetermined results.
 *
 *                     SPP_HB_DEMAND - Request a user initiated heartbeat
 *                     to be made immediately.
 *
 *                     SPP_PMTUD_ENABLE - This field will enable PMTU
 *                     discovery upon the specified address. Note that
 *                     if the address feild is empty then all addresses
 *                     on the association are effected.
 *
 *                     SPP_PMTUD_DISABLE - This field will disable PMTU
 *                     discovery upon the specified address. Note that
 *                     if the address feild is empty then all addresses
 *                     on the association are effected. Not also that
 *                     SPP_PMTUD_ENABLE and SPP_PMTUD_DISABLE are mutually
 *                     exclusive. Enabling both will have undetermined
 *                     results.
 *
 *                     SPP_SACKDELAY_ENABLE - Setting this flag turns
 *                     on delayed sack. The time specified in spp_sackdelay
 *                     is used to specify the sack delay for this address. Note
 *                     that if spp_address is empty then all addresses will
 *                     enable delayed sack and take on the sack delay
 *                     value specified in spp_sackdelay.
 *                     SPP_SACKDELAY_DISABLE - Setting this flag turns
 *                     off delayed sack. If the spp_address field is blank then
 *                     delayed sack is disabled for the entire association. Note
 *                     also that this field is mutually exclusive to
 *                     SPP_SACKDELAY_ENABLE, setting both will have undefined
 *                     results.
 */
static int sctp_getsockopt_peer_addr_params(struct sock *sk, int len,
                        char __user *optval, int __user *optlen)
{
    struct sctp_paddrparams  params;
    struct sctp_transport   *trans = NULL;
    struct sctp_association *asoc = NULL;
    struct sctp_sock        *sp = sctp_sk(sk);

    if (len < sizeof(struct sctp_paddrparams))
        return -EINVAL;
    len = sizeof(struct sctp_paddrparams);
    if (copy_from_user(&params, optval, len))
        return -EFAULT;

    /* If an address other than INADDR_ANY is specified, and
     * no transport is found, then the request is invalid.
     */
    if (!sctp_is_any(sk, ( union sctp_addr *)&params.spp_address)) {
        trans = sctp_addr_id2transport(sk, &params.spp_address,
                           params.spp_assoc_id);
        if (!trans) {
            SCTP_DEBUG_PRINTK("Failed no transport\n");
            return -EINVAL;
        }
    }

    /* Get association, if assoc_id != 0 and the socket is a one
     * to many style socket, and an association was not found, then
     * the id was invalid.
     */
    asoc = sctp_id2assoc(sk, params.spp_assoc_id);
    if (!asoc && params.spp_assoc_id && sctp_style(sk, UDP)) {
        SCTP_DEBUG_PRINTK("Failed no association\n");
        return -EINVAL;
    }

    if (trans) {
        /* Fetch transport values. */
        params.spp_hbinterval = jiffies_to_msecs(trans->hbinterval);
        params.spp_pathmtu    = trans->pathmtu;
        params.spp_pathmaxrxt = trans->pathmaxrxt;
        params.spp_sackdelay  = jiffies_to_msecs(trans->sackdelay);

        /*draft-11 doesn't say what to return in spp_flags*/
        params.spp_flags      = trans->param_flags;
    } else if (asoc) {
        /* Fetch association values. */
        params.spp_hbinterval = jiffies_to_msecs(asoc->hbinterval);
        params.spp_pathmtu    = asoc->pathmtu;
        params.spp_pathmaxrxt = asoc->pathmaxrxt;
        params.spp_sackdelay  = jiffies_to_msecs(asoc->sackdelay);

        /*draft-11 doesn't say what to return in spp_flags*/
        params.spp_flags      = asoc->param_flags;
    } else {
        /* Fetch socket values. */
        params.spp_hbinterval = sp->hbinterval;
        params.spp_pathmtu    = sp->pathmtu;
        params.spp_sackdelay  = sp->sackdelay;
        params.spp_pathmaxrxt = sp->pathmaxrxt;

        /*draft-11 doesn't say what to return in spp_flags*/
        params.spp_flags      = sp->param_flags;
    }

    if (copy_to_user(optval, &params, len))
        return -EFAULT;

    if (put_user(len, optlen))
        return -EFAULT;

    return 0;
}

/*
 * 7.1.23.  Get or set delayed ack timer (SCTP_DELAYED_SACK)
 *
 * This option will effect the way delayed acks are performed.  This
 * option allows you to get or set the delayed ack time, in
 * milliseconds.  It also allows changing the delayed ack frequency.
 * Changing the frequency to 1 disables the delayed sack algorithm.  If
 * the assoc_id is 0, then this sets or gets the endpoints default
 * values.  If the assoc_id field is non-zero, then the set or get
 * effects the specified association for the one to many model (the
 * assoc_id field is ignored by the one to one model).  Note that if
 * sack_delay or sack_freq are 0 when setting this option, then the
 * current values will remain unchanged.
 *
 * struct sctp_sack_info {
 *     sctp_assoc_t            sack_assoc_id;
 *     uint32_t                sack_delay;
 *     uint32_t                sack_freq;
 * };
 *
 * sack_assoc_id -  This parameter, indicates which association the user
 *    is performing an action upon.  Note that if this field's value is
 *    zero then the endpoints default value is changed (effecting future
 *    associations only).
 *
 * sack_delay -  This parameter contains the number of milliseconds that
 *    the user is requesting the delayed ACK timer be set to.  Note that
 *    this value is defined in the standard to be between 200 and 500
 *    milliseconds.
 *
 * sack_freq -  This parameter contains the number of packets that must
 *    be received before a sack is sent without waiting for the delay
 *    timer to expire.  The default value for this is 2, setting this
 *    value to 1 will disable the delayed sack algorithm.
 */
static int sctp_getsockopt_delayed_ack(struct sock *sk, int len,
                        char __user *optval,
                        int __user *optlen)
{
    struct sctp_sack_info    params;
    struct sctp_association *asoc = NULL;
    struct sctp_sock        *sp = sctp_sk(sk);

    if (len >= sizeof(struct sctp_sack_info)) {
        len = sizeof(struct sctp_sack_info);

        if (copy_from_user(&params, optval, len))
            return -EFAULT;
    } else if (len == sizeof(struct sctp_assoc_value)) {
        pr_warn("Use of struct sctp_assoc_value in delayed_ack socket option deprecated\n");
        pr_warn("Use struct sctp_sack_info instead\n");
        if (copy_from_user(&params, optval, len))
            return -EFAULT;
    } else
        return - EINVAL;

    /* Get association, if sack_assoc_id != 0 and the socket is a one
     * to many style socket, and an association was not found, then
     * the id was invalid.
     */
    asoc = sctp_id2assoc(sk, params.sack_assoc_id);
    if (!asoc && params.sack_assoc_id && sctp_style(sk, UDP))
        return -EINVAL;

    if (asoc) {
        /* Fetch association values. */
        if (asoc->param_flags & SPP_SACKDELAY_ENABLE) {
            params.sack_delay = jiffies_to_msecs(
                asoc->sackdelay);
            params.sack_freq = asoc->sackfreq;

        } else {
            params.sack_delay = 0;
            params.sack_freq = 1;
        }
    } else {
        /* Fetch socket values. */
        if (sp->param_flags & SPP_SACKDELAY_ENABLE) {
            params.sack_delay  = sp->sackdelay;
            params.sack_freq = sp->sackfreq;
        } else {
            params.sack_delay  = 0;
            params.sack_freq = 1;
        }
    }

    if (copy_to_user(optval, &params, len))
        return -EFAULT;

    if (put_user(len, optlen))
        return -EFAULT;

    return 0;
}

/* 7.1.3 Initialization Parameters (SCTP_INITMSG)
 *
 * Applications can specify protocol parameters for the default association
 * initialization.  The option name argument to setsockopt() and getsockopt()
 * is SCTP_INITMSG.
 *
 * Setting initialization parameters is effective only on an unconnected
 * socket (for UDP-style sockets only future associations are effected
 * by the change).  With TCP-style sockets, this option is inherited by
 * sockets derived from a listener socket.
 */
static int sctp_getsockopt_initmsg(struct sock *sk, int len, char __user *optval, int __user *optlen)
{
    if (len < sizeof(struct sctp_initmsg))
        return -EINVAL;
    len = sizeof(struct sctp_initmsg);
    if (put_user(len, optlen))
        return -EFAULT;
    if (copy_to_user(optval, &sctp_sk(sk)->initmsg, len))
        return -EFAULT;
    return 0;
}


static int sctp_getsockopt_peer_addrs(struct sock *sk, int len,
                      char __user *optval, int __user *optlen)
{
    struct sctp_association *asoc;
    int cnt = 0;
    struct sctp_getaddrs getaddrs;
    struct sctp_transport *from;
    void __user *to;
    union sctp_addr temp;
    struct sctp_sock *sp = sctp_sk(sk);
    int addrlen;
    size_t space_left;
    int bytes_copied;

    if (len < sizeof(struct sctp_getaddrs))
        return -EINVAL;

    if (copy_from_user(&getaddrs, optval, sizeof(struct sctp_getaddrs)))
        return -EFAULT;

    /* For UDP-style sockets, id specifies the association to query.  */
    asoc = sctp_id2assoc(sk, getaddrs.assoc_id);
    if (!asoc)
        return -EINVAL;

    to = optval + offsetof(struct sctp_getaddrs,addrs);
    space_left = len - offsetof(struct sctp_getaddrs,addrs);

    list_for_each_entry(from, &asoc->peer.transport_addr_list,
                transports) {
        memcpy(&temp, &from->ipaddr, sizeof(temp));
        sctp_get_pf_specific(sk->sk_family)->addr_v4map(sp, &temp);
        addrlen = sctp_get_af_specific(temp.sa.sa_family)->sockaddr_len;
        if (space_left < addrlen)
            return -ENOMEM;
        if (copy_to_user(to, &temp, addrlen))
            return -EFAULT;
        to += addrlen;
        cnt++;
        space_left -= addrlen;
    }

    if (put_user(cnt, &((struct sctp_getaddrs __user *)optval)->addr_num))
        return -EFAULT;
    bytes_copied = ((char __user *)to) - optval;
    if (put_user(bytes_copied, optlen))
        return -EFAULT;

    return 0;
}

static int sctp_copy_laddrs(struct sock *sk, __u16 port, void *to,
                size_t space_left, int *bytes_copied)
{
    struct sctp_sockaddr_entry *addr;
    union sctp_addr temp;
    int cnt = 0;
    int addrlen;
    struct net *net = sock_net(sk);

    rcu_read_lock();
    list_for_each_entry_rcu(addr, &net->sctp.local_addr_list, list) {
        if (!addr->valid)
            continue;

        if ((PF_INET == sk->sk_family) &&
            (AF_INET6 == addr->a.sa.sa_family))
            continue;
        if ((PF_INET6 == sk->sk_family) &&
            inet_v6_ipv6only(sk) &&
            (AF_INET == addr->a.sa.sa_family))
            continue;
        memcpy(&temp, &addr->a, sizeof(temp));
        if (!temp.v4.sin_port)
            temp.v4.sin_port = htons(port);

        sctp_get_pf_specific(sk->sk_family)->addr_v4map(sctp_sk(sk),
                                &temp);
        addrlen = sctp_get_af_specific(temp.sa.sa_family)->sockaddr_len;
        if (space_left < addrlen) {
            cnt =  -ENOMEM;
            break;
        }
        memcpy(to, &temp, addrlen);

        to += addrlen;
        cnt ++;
        space_left -= addrlen;
        *bytes_copied += addrlen;
    }
    rcu_read_unlock();

    return cnt;
}


static int sctp_getsockopt_local_addrs(struct sock *sk, int len,
                       char __user *optval, int __user *optlen)
{
    struct sctp_bind_addr *bp;
    struct sctp_association *asoc;
    int cnt = 0;
    struct sctp_getaddrs getaddrs;
    struct sctp_sockaddr_entry *addr;
    void __user *to;
    union sctp_addr temp;
    struct sctp_sock *sp = sctp_sk(sk);
    int addrlen;
    int err = 0;
    size_t space_left;
    int bytes_copied = 0;
    void *addrs;
    void *buf;

    if (len < sizeof(struct sctp_getaddrs))
        return -EINVAL;

    if (copy_from_user(&getaddrs, optval, sizeof(struct sctp_getaddrs)))
        return -EFAULT;

    /*
     *  For UDP-style sockets, id specifies the association to query.
     *  If the id field is set to the value '0' then the locally bound
     *  addresses are returned without regard to any particular
     *  association.
     */
    if (0 == getaddrs.assoc_id) {
        bp = &sctp_sk(sk)->ep->base.bind_addr;
    } else {
        asoc = sctp_id2assoc(sk, getaddrs.assoc_id);
        if (!asoc)
            return -EINVAL;
        bp = &asoc->base.bind_addr;
    }

    to = optval + offsetof(struct sctp_getaddrs,addrs);
    space_left = len - offsetof(struct sctp_getaddrs,addrs);

    addrs = kmalloc(space_left, GFP_KERNEL);
    if (!addrs)
        return -ENOMEM;

    /* If the endpoint is bound to 0.0.0.0 or ::0, get the valid
     * addresses from the global local address list.
     */
    if (sctp_list_single_entry(&bp->address_list)) {
        addr = list_entry(bp->address_list.next,
                  struct sctp_sockaddr_entry, list);
        if (sctp_is_any(sk, &addr->a)) {
            cnt = sctp_copy_laddrs(sk, bp->port, addrs,
                        space_left, &bytes_copied);
            if (cnt < 0) {
                err = cnt;
                goto out;
            }
            goto copy_getaddrs;
        }
    }

    buf = addrs;
    /* Protection on the bound address list is not needed since
     * in the socket option context we hold a socket lock and
     * thus the bound address list can't change.
     */
    list_for_each_entry(addr, &bp->address_list, list) {
        memcpy(&temp, &addr->a, sizeof(temp));
        sctp_get_pf_specific(sk->sk_family)->addr_v4map(sp, &temp);
        addrlen = sctp_get_af_specific(temp.sa.sa_family)->sockaddr_len;
        if (space_left < addrlen) {
            err =  -ENOMEM; /*fixme: right error?*/
            goto out;
        }
        memcpy(buf, &temp, addrlen);
        buf += addrlen;
        bytes_copied += addrlen;
        cnt ++;
        space_left -= addrlen;
    }

copy_getaddrs:
    if (copy_to_user(to, addrs, bytes_copied)) {
        err = -EFAULT;
        goto out;
    }
    if (put_user(cnt, &((struct sctp_getaddrs __user *)optval)->addr_num)) {
        err = -EFAULT;
        goto out;
    }
    if (put_user(bytes_copied, optlen))
        err = -EFAULT;
out:
    kfree(addrs);
    return err;
}

/* 7.1.10 Set Primary Address (SCTP_PRIMARY_ADDR)
 *
 * Requests that the local SCTP stack use the enclosed peer address as
 * the association primary.  The enclosed address must be one of the
 * association peer's addresses.
 */
static int sctp_getsockopt_primary_addr(struct sock *sk, int len,
                    char __user *optval, int __user *optlen)
{
    struct sctp_prim prim;
    struct sctp_association *asoc;
    struct sctp_sock *sp = sctp_sk(sk);

    if (len < sizeof(struct sctp_prim))
        return -EINVAL;

    len = sizeof(struct sctp_prim);

    if (copy_from_user(&prim, optval, len))
        return -EFAULT;

    asoc = sctp_id2assoc(sk, prim.ssp_assoc_id);
    if (!asoc)
        return -EINVAL;

    if (!asoc->peer.primary_path)
        return -ENOTCONN;

    memcpy(&prim.ssp_addr, &asoc->peer.primary_path->ipaddr,
        asoc->peer.primary_path->af_specific->sockaddr_len);

    sctp_get_pf_specific(sk->sk_family)->addr_v4map(sp,
            (union sctp_addr *)&prim.ssp_addr);

    if (put_user(len, optlen))
        return -EFAULT;
    if (copy_to_user(optval, &prim, len))
        return -EFAULT;

    return 0;
}

/*
 * 7.1.11  Set Adaptation Layer Indicator (SCTP_ADAPTATION_LAYER)
 *
 * Requests that the local endpoint set the specified Adaptation Layer
 * Indication parameter for all future INIT and INIT-ACK exchanges.
 */
static int sctp_getsockopt_adaptation_layer(struct sock *sk, int len,
                  char __user *optval, int __user *optlen)
{
    struct sctp_setadaptation adaptation;

    if (len < sizeof(struct sctp_setadaptation))
        return -EINVAL;

    len = sizeof(struct sctp_setadaptation);

    adaptation.ssb_adaptation_ind = sctp_sk(sk)->adaptation_ind;

    if (put_user(len, optlen))
        return -EFAULT;
    if (copy_to_user(optval, &adaptation, len))
        return -EFAULT;

    return 0;
}

/*
 *
 * 7.1.14 Set default send parameters (SCTP_DEFAULT_SEND_PARAM)
 *
 *   Applications that wish to use the sendto() system call may wish to
 *   specify a default set of parameters that would normally be supplied
 *   through the inclusion of ancillary data.  This socket option allows
 *   such an application to set the default sctp_sndrcvinfo structure.


 *   The application that wishes to use this socket option simply passes
 *   in to this call the sctp_sndrcvinfo structure defined in Section
 *   5.2.2) The input parameters accepted by this call include
 *   sinfo_stream, sinfo_flags, sinfo_ppid, sinfo_context,
 *   sinfo_timetolive.  The user must provide the sinfo_assoc_id field in
 *   to this call if the caller is using the UDP model.
 *
 *   For getsockopt, it get the default sctp_sndrcvinfo structure.
 */
static int sctp_getsockopt_default_send_param(struct sock *sk,
                    int len, char __user *optval,
                    int __user *optlen)
{
    struct sctp_sndrcvinfo info;
    struct sctp_association *asoc;
    struct sctp_sock *sp = sctp_sk(sk);

    if (len < sizeof(struct sctp_sndrcvinfo))
        return -EINVAL;

    len = sizeof(struct sctp_sndrcvinfo);

    if (copy_from_user(&info, optval, len))
        return -EFAULT;

    asoc = sctp_id2assoc(sk, info.sinfo_assoc_id);
    if (!asoc && info.sinfo_assoc_id && sctp_style(sk, UDP))
        return -EINVAL;

    if (asoc) {
        info.sinfo_stream = asoc->default_stream;
        info.sinfo_flags = asoc->default_flags;
        info.sinfo_ppid = asoc->default_ppid;
        info.sinfo_context = asoc->default_context;
        info.sinfo_timetolive = asoc->default_timetolive;
    } else {
        info.sinfo_stream = sp->default_stream;
        info.sinfo_flags = sp->default_flags;
        info.sinfo_ppid = sp->default_ppid;
        info.sinfo_context = sp->default_context;
        info.sinfo_timetolive = sp->default_timetolive;
    }

    if (put_user(len, optlen))
        return -EFAULT;
    if (copy_to_user(optval, &info, len))
        return -EFAULT;

    return 0;
}

/*
 *
 * 7.1.5 SCTP_NODELAY
 *
 * Turn on/off any Nagle-like algorithm.  This means that packets are
 * generally sent as soon as possible and no unnecessary delays are
 * introduced, at the cost of more packets in the network.  Expects an
 * integer boolean flag.
 */

static int sctp_getsockopt_nodelay(struct sock *sk, int len,
                   char __user *optval, int __user *optlen)
{
    int val;

    if (len < sizeof(int))
        return -EINVAL;

    len = sizeof(int);
    val = (sctp_sk(sk)->nodelay == 1);
    if (put_user(len, optlen))
        return -EFAULT;
    if (copy_to_user(optval, &val, len))
        return -EFAULT;
    return 0;
}

/*
 *
 * 7.1.1 SCTP_RTOINFO
 *
 * The protocol parameters used to initialize and bound retransmission
 * timeout (RTO) are tunable. sctp_rtoinfo structure is used to access
 * and modify these parameters.
 * All parameters are time values, in milliseconds.  A value of 0, when
 * modifying the parameters, indicates that the current value should not
 * be changed.
 *
 */
static int sctp_getsockopt_rtoinfo(struct sock *sk, int len,
                char __user *optval,
                int __user *optlen) {
    struct sctp_rtoinfo rtoinfo;
    struct sctp_association *asoc;

    if (len < sizeof (struct sctp_rtoinfo))
        return -EINVAL;

    len = sizeof(struct sctp_rtoinfo);

    if (copy_from_user(&rtoinfo, optval, len))
        return -EFAULT;

    asoc = sctp_id2assoc(sk, rtoinfo.srto_assoc_id);

    if (!asoc && rtoinfo.srto_assoc_id && sctp_style(sk, UDP))
        return -EINVAL;

    /* Values corresponding to the specific association. */
    if (asoc) {
        rtoinfo.srto_initial = jiffies_to_msecs(asoc->rto_initial);
        rtoinfo.srto_max = jiffies_to_msecs(asoc->rto_max);
        rtoinfo.srto_min = jiffies_to_msecs(asoc->rto_min);
    } else {
        /* Values corresponding to the endpoint. */
        struct sctp_sock *sp = sctp_sk(sk);

        rtoinfo.srto_initial = sp->rtoinfo.srto_initial;
        rtoinfo.srto_max = sp->rtoinfo.srto_max;
        rtoinfo.srto_min = sp->rtoinfo.srto_min;
    }

    if (put_user(len, optlen))
        return -EFAULT;

    if (copy_to_user(optval, &rtoinfo, len))
        return -EFAULT;

    return 0;
}

/*
 *
 * 7.1.2 SCTP_ASSOCINFO
 *
 * This option is used to tune the maximum retransmission attempts
 * of the association.
 * Returns an error if the new association retransmission value is
 * greater than the sum of the retransmission value  of the peer.
 * See [SCTP] for more information.
 *
 */
static int sctp_getsockopt_associnfo(struct sock *sk, int len,
                     char __user *optval,
                     int __user *optlen)
{

    struct sctp_assocparams assocparams;
    struct sctp_association *asoc;
    struct list_head *pos;
    int cnt = 0;

    if (len < sizeof (struct sctp_assocparams))
        return -EINVAL;

    len = sizeof(struct sctp_assocparams);

    if (copy_from_user(&assocparams, optval, len))
        return -EFAULT;

    asoc = sctp_id2assoc(sk, assocparams.sasoc_assoc_id);

    if (!asoc && assocparams.sasoc_assoc_id && sctp_style(sk, UDP))
        return -EINVAL;

    /* Values correspoinding to the specific association */
    if (asoc) {
        assocparams.sasoc_asocmaxrxt = asoc->max_retrans;
        assocparams.sasoc_peer_rwnd = asoc->peer.rwnd;
        assocparams.sasoc_local_rwnd = asoc->a_rwnd;
        assocparams.sasoc_cookie_life = (asoc->cookie_life.tv_sec
                        * 1000) +
                        (asoc->cookie_life.tv_usec
                        / 1000);

        list_for_each(pos, &asoc->peer.transport_addr_list) {
            cnt ++;
        }

        assocparams.sasoc_number_peer_destinations = cnt;
    } else {
        /* Values corresponding to the endpoint */
        struct sctp_sock *sp = sctp_sk(sk);

        assocparams.sasoc_asocmaxrxt = sp->assocparams.sasoc_asocmaxrxt;
        assocparams.sasoc_peer_rwnd = sp->assocparams.sasoc_peer_rwnd;
        assocparams.sasoc_local_rwnd = sp->assocparams.sasoc_local_rwnd;
        assocparams.sasoc_cookie_life =
                    sp->assocparams.sasoc_cookie_life;
        assocparams.sasoc_number_peer_destinations =
                    sp->assocparams.
                    sasoc_number_peer_destinations;
    }

    if (put_user(len, optlen))
        return -EFAULT;

    if (copy_to_user(optval, &assocparams, len))
        return -EFAULT;

    return 0;
}

/*
 * 7.1.16 Set/clear IPv4 mapped addresses (SCTP_I_WANT_MAPPED_V4_ADDR)
 *
 * This socket option is a boolean flag which turns on or off mapped V4
 * addresses.  If this option is turned on and the socket is type
 * PF_INET6, then IPv4 addresses will be mapped to V6 representation.
 * If this option is turned off, then no mapping will be done of V4
 * addresses and a user will receive both PF_INET6 and PF_INET type
 * addresses on the socket.
 */
static int sctp_getsockopt_mappedv4(struct sock *sk, int len,
                    char __user *optval, int __user *optlen)
{
    int val;
    struct sctp_sock *sp = sctp_sk(sk);

    if (len < sizeof(int))
        return -EINVAL;

    len = sizeof(int);
    val = sp->v4mapped;
    if (put_user(len, optlen))
        return -EFAULT;
    if (copy_to_user(optval, &val, len))
        return -EFAULT;

    return 0;
}

/*
 * 7.1.29.  Set or Get the default context (SCTP_CONTEXT)
 * (chapter and verse is quoted at sctp_setsockopt_context())
 */
static int sctp_getsockopt_context(struct sock *sk, int len,
                   char __user *optval, int __user *optlen)
{
    struct sctp_assoc_value params;
    struct sctp_sock *sp;
    struct sctp_association *asoc;

    if (len < sizeof(struct sctp_assoc_value))
        return -EINVAL;

    len = sizeof(struct sctp_assoc_value);

    if (copy_from_user(&params, optval, len))
        return -EFAULT;

    sp = sctp_sk(sk);

    if (params.assoc_id != 0) {
        asoc = sctp_id2assoc(sk, params.assoc_id);
        if (!asoc)
            return -EINVAL;
        params.assoc_value = asoc->default_rcv_context;
    } else {
        params.assoc_value = sp->default_rcv_context;
    }

    if (put_user(len, optlen))
        return -EFAULT;
    if (copy_to_user(optval, &params, len))
        return -EFAULT;

    return 0;
}

/*
 * 8.1.16.  Get or Set the Maximum Fragmentation Size (SCTP_MAXSEG)
 * This option will get or set the maximum size to put in any outgoing
 * SCTP DATA chunk.  If a message is larger than this size it will be
 * fragmented by SCTP into the specified size.  Note that the underlying
 * SCTP implementation may fragment into smaller sized chunks when the
 * PMTU of the underlying association is smaller than the value set by
 * the user.  The default value for this option is '0' which indicates
 * the user is NOT limiting fragmentation and only the PMTU will effect
 * SCTP's choice of DATA chunk size.  Note also that values set larger
 * than the maximum size of an IP datagram will effectively let SCTP
 * control fragmentation (i.e. the same as setting this option to 0).
 *
 * The following structure is used to access and modify this parameter:
 *
 * struct sctp_assoc_value {
 *   sctp_assoc_t assoc_id;
 *   uint32_t assoc_value;
 * };
 *
 * assoc_id:  This parameter is ignored for one-to-one style sockets.
 *    For one-to-many style sockets this parameter indicates which
 *    association the user is performing an action upon.  Note that if
 *    this field's value is zero then the endpoints default value is
 *    changed (effecting future associations only).
 * assoc_value:  This parameter specifies the maximum size in bytes.
 */
static int sctp_getsockopt_maxseg(struct sock *sk, int len,
                  char __user *optval, int __user *optlen)
{
    struct sctp_assoc_value params;
    struct sctp_association *asoc;

    if (len == sizeof(int)) {
        pr_warn("Use of int in maxseg socket option deprecated\n");
        pr_warn("Use struct sctp_assoc_value instead\n");
        params.assoc_id = 0;
    } else if (len >= sizeof(struct sctp_assoc_value)) {
        len = sizeof(struct sctp_assoc_value);
        if (copy_from_user(&params, optval, sizeof(params)))
            return -EFAULT;
    } else
        return -EINVAL;

    asoc = sctp_id2assoc(sk, params.assoc_id);
    if (!asoc && params.assoc_id && sctp_style(sk, UDP))
        return -EINVAL;

    if (asoc)
        params.assoc_value = asoc->frag_point;
    else
        params.assoc_value = sctp_sk(sk)->user_frag;

    if (put_user(len, optlen))
        return -EFAULT;
    if (len == sizeof(int)) {
        if (copy_to_user(optval, &params.assoc_value, len))
            return -EFAULT;
    } else {
        if (copy_to_user(optval, &params, len))
            return -EFAULT;
    }

    return 0;
}

/*
 * 7.1.24.  Get or set fragmented interleave (SCTP_FRAGMENT_INTERLEAVE)
 * (chapter and verse is quoted at sctp_setsockopt_fragment_interleave())
 */
static int sctp_getsockopt_fragment_interleave(struct sock *sk, int len,
                           char __user *optval, int __user *optlen)
{
    int val;

    if (len < sizeof(int))
        return -EINVAL;

    len = sizeof(int);

    val = sctp_sk(sk)->frag_interleave;
    if (put_user(len, optlen))
        return -EFAULT;
    if (copy_to_user(optval, &val, len))
        return -EFAULT;

    return 0;
}

/*
 * 7.1.25.  Set or Get the sctp partial delivery point
 * (chapter and verse is quoted at sctp_setsockopt_partial_delivery_point())
 */
static int sctp_getsockopt_partial_delivery_point(struct sock *sk, int len,
                          char __user *optval,
                          int __user *optlen)
{
    u32 val;

    if (len < sizeof(u32))
        return -EINVAL;

    len = sizeof(u32);

    val = sctp_sk(sk)->pd_point;
    if (put_user(len, optlen))
        return -EFAULT;
    if (copy_to_user(optval, &val, len))
        return -EFAULT;

    return 0;
}

/*
 * 7.1.28.  Set or Get the maximum burst (SCTP_MAX_BURST)
 * (chapter and verse is quoted at sctp_setsockopt_maxburst())
 */
static int sctp_getsockopt_maxburst(struct sock *sk, int len,
                    char __user *optval,
                    int __user *optlen)
{
    struct sctp_assoc_value params;
    struct sctp_sock *sp;
    struct sctp_association *asoc;

    if (len == sizeof(int)) {
        pr_warn("Use of int in max_burst socket option deprecated\n");
        pr_warn("Use struct sctp_assoc_value instead\n");
        params.assoc_id = 0;
    } else if (len >= sizeof(struct sctp_assoc_value)) {
        len = sizeof(struct sctp_assoc_value);
        if (copy_from_user(&params, optval, len))
            return -EFAULT;
    } else
        return -EINVAL;

    sp = sctp_sk(sk);

    if (params.assoc_id != 0) {
        asoc = sctp_id2assoc(sk, params.assoc_id);
        if (!asoc)
            return -EINVAL;
        params.assoc_value = asoc->max_burst;
    } else
        params.assoc_value = sp->max_burst;

    if (len == sizeof(int)) {
        if (copy_to_user(optval, &params.assoc_value, len))
            return -EFAULT;
    } else {
        if (copy_to_user(optval, &params, len))
            return -EFAULT;
    }

    return 0;

}

static int sctp_getsockopt_hmac_ident(struct sock *sk, int len,
                    char __user *optval, int __user *optlen)
{
    struct net *net = sock_net(sk);
    struct sctp_hmacalgo  __user *p = (void __user *)optval;
    struct sctp_hmac_algo_param *hmacs;
    __u16 data_len = 0;
    u32 num_idents;

    if (!net->sctp.auth_enable)
        return -EACCES;

    hmacs = sctp_sk(sk)->ep->auth_hmacs_list;
    data_len = ntohs(hmacs->param_hdr.length) - sizeof(sctp_paramhdr_t);

    if (len < sizeof(struct sctp_hmacalgo) + data_len)
        return -EINVAL;

    len = sizeof(struct sctp_hmacalgo) + data_len;
    num_idents = data_len / sizeof(u16);

    if (put_user(len, optlen))
        return -EFAULT;
    if (put_user(num_idents, &p->shmac_num_idents))
        return -EFAULT;
    if (copy_to_user(p->shmac_idents, hmacs->hmac_ids, data_len))
        return -EFAULT;
    return 0;
}

static int sctp_getsockopt_active_key(struct sock *sk, int len,
                    char __user *optval, int __user *optlen)
{
    struct net *net = sock_net(sk);
    struct sctp_authkeyid val;
    struct sctp_association *asoc;

    if (!net->sctp.auth_enable)
        return -EACCES;

    if (len < sizeof(struct sctp_authkeyid))
        return -EINVAL;
    if (copy_from_user(&val, optval, sizeof(struct sctp_authkeyid)))
        return -EFAULT;

    asoc = sctp_id2assoc(sk, val.scact_assoc_id);
    if (!asoc && val.scact_assoc_id && sctp_style(sk, UDP))
        return -EINVAL;

    if (asoc)
        val.scact_keynumber = asoc->active_key_id;
    else
        val.scact_keynumber = sctp_sk(sk)->ep->active_key_id;

    len = sizeof(struct sctp_authkeyid);
    if (put_user(len, optlen))
        return -EFAULT;
    if (copy_to_user(optval, &val, len))
        return -EFAULT;

    return 0;
}

static int sctp_getsockopt_peer_auth_chunks(struct sock *sk, int len,
                    char __user *optval, int __user *optlen)
{
    struct net *net = sock_net(sk);
    struct sctp_authchunks __user *p = (void __user *)optval;
    struct sctp_authchunks val;
    struct sctp_association *asoc;
    struct sctp_chunks_param *ch;
    u32    num_chunks = 0;
    char __user *to;

    if (!net->sctp.auth_enable)
        return -EACCES;

    if (len < sizeof(struct sctp_authchunks))
        return -EINVAL;

    if (copy_from_user(&val, optval, sizeof(struct sctp_authchunks)))
        return -EFAULT;

    to = p->gauth_chunks;
    asoc = sctp_id2assoc(sk, val.gauth_assoc_id);
    if (!asoc)
        return -EINVAL;

    ch = asoc->peer.peer_chunks;
    if (!ch)
        goto num;

    /* See if the user provided enough room for all the data */
    num_chunks = ntohs(ch->param_hdr.length) - sizeof(sctp_paramhdr_t);
    if (len < num_chunks)
        return -EINVAL;

    if (copy_to_user(to, ch->chunks, num_chunks))
        return -EFAULT;
num:
    len = sizeof(struct sctp_authchunks) + num_chunks;
    if (put_user(len, optlen)) return -EFAULT;
    if (put_user(num_chunks, &p->gauth_number_of_chunks))
        return -EFAULT;
    return 0;
}

static int sctp_getsockopt_local_auth_chunks(struct sock *sk, int len,
                    char __user *optval, int __user *optlen)
{
    struct net *net = sock_net(sk);
    struct sctp_authchunks __user *p = (void __user *)optval;
    struct sctp_authchunks val;
    struct sctp_association *asoc;
    struct sctp_chunks_param *ch;
    u32    num_chunks = 0;
    char __user *to;

    if (!net->sctp.auth_enable)
        return -EACCES;

    if (len < sizeof(struct sctp_authchunks))
        return -EINVAL;

    if (copy_from_user(&val, optval, sizeof(struct sctp_authchunks)))
        return -EFAULT;

    to = p->gauth_chunks;
    asoc = sctp_id2assoc(sk, val.gauth_assoc_id);
    if (!asoc && val.gauth_assoc_id && sctp_style(sk, UDP))
        return -EINVAL;

    if (asoc)
        ch = (struct sctp_chunks_param*)asoc->c.auth_chunks;
    else
        ch = sctp_sk(sk)->ep->auth_chunk_list;

    if (!ch)
        goto num;

    num_chunks = ntohs(ch->param_hdr.length) - sizeof(sctp_paramhdr_t);
    if (len < sizeof(struct sctp_authchunks) + num_chunks)
        return -EINVAL;

    if (copy_to_user(to, ch->chunks, num_chunks))
        return -EFAULT;
num:
    len = sizeof(struct sctp_authchunks) + num_chunks;
    if (put_user(len, optlen))
        return -EFAULT;
    if (put_user(num_chunks, &p->gauth_number_of_chunks))
        return -EFAULT;

    return 0;
}

/*
 * 8.2.5.  Get the Current Number of Associations (SCTP_GET_ASSOC_NUMBER)
 * This option gets the current number of associations that are attached
 * to a one-to-many style socket.  The option value is an uint32_t.
 */
static int sctp_getsockopt_assoc_number(struct sock *sk, int len,
                    char __user *optval, int __user *optlen)
{
    struct sctp_sock *sp = sctp_sk(sk);
    struct sctp_association *asoc;
    u32 val = 0;

    if (sctp_style(sk, TCP))
        return -EOPNOTSUPP;

    if (len < sizeof(u32))
        return -EINVAL;

    len = sizeof(u32);

    list_for_each_entry(asoc, &(sp->ep->asocs), asocs) {
        val++;
    }

    if (put_user(len, optlen))
        return -EFAULT;
    if (copy_to_user(optval, &val, len))
        return -EFAULT;

    return 0;
}

/*
 * 8.1.23 SCTP_AUTO_ASCONF
 * See the corresponding setsockopt entry as description
 */
static int sctp_getsockopt_auto_asconf(struct sock *sk, int len,
                   char __user *optval, int __user *optlen)
{
    int val = 0;

    if (len < sizeof(int))
        return -EINVAL;

    len = sizeof(int);
    if (sctp_sk(sk)->do_auto_asconf && sctp_is_ep_boundall(sk))
        val = 1;
    if (put_user(len, optlen))
        return -EFAULT;
    if (copy_to_user(optval, &val, len))
        return -EFAULT;
    return 0;
}

/*
 * 8.2.6. Get the Current Identifiers of Associations
 *        (SCTP_GET_ASSOC_ID_LIST)
 *
 * This option gets the current list of SCTP association identifiers of
 * the SCTP associations handled by a one-to-many style socket.
 */
static int sctp_getsockopt_assoc_ids(struct sock *sk, int len,
                    char __user *optval, int __user *optlen)
{
    struct sctp_sock *sp = sctp_sk(sk);
    struct sctp_association *asoc;
    struct sctp_assoc_ids *ids;
    u32 num = 0;

    if (sctp_style(sk, TCP))
        return -EOPNOTSUPP;

    if (len < sizeof(struct sctp_assoc_ids))
        return -EINVAL;

    list_for_each_entry(asoc, &(sp->ep->asocs), asocs) {
        num++;
    }

    if (len < sizeof(struct sctp_assoc_ids) + sizeof(sctp_assoc_t) * num)
        return -EINVAL;

    len = sizeof(struct sctp_assoc_ids) + sizeof(sctp_assoc_t) * num;

    ids = kmalloc(len, GFP_KERNEL);
    if (unlikely(!ids))
        return -ENOMEM;

    ids->gaids_number_of_ids = num;
    num = 0;
    list_for_each_entry(asoc, &(sp->ep->asocs), asocs) {
        ids->gaids_assoc_id[num++] = asoc->assoc_id;
    }

    if (put_user(len, optlen) || copy_to_user(optval, ids, len)) {
        kfree(ids);
        return -EFAULT;
    }

    kfree(ids);
    return 0;
}

/*
 * SCTP_PEER_ADDR_THLDS
 *
 * This option allows us to fetch the partially failed threshold for one or all
 * transports in an association.  See Section 6.1 of:
 * http://www.ietf.org/id/draft-nishida-tsvwg-sctp-failover-05.txt
 */
static int sctp_getsockopt_paddr_thresholds(struct sock *sk,
                        char __user *optval,
                        int len,
                        int __user *optlen)
{
    struct sctp_paddrthlds val;
    struct sctp_transport *trans;
    struct sctp_association *asoc;

    if (len < sizeof(struct sctp_paddrthlds))
        return -EINVAL;
    len = sizeof(struct sctp_paddrthlds);
    if (copy_from_user(&val, (struct sctp_paddrthlds __user *)optval, len))
        return -EFAULT;

    if (sctp_is_any(sk, (const union sctp_addr *)&val.spt_address)) {
        asoc = sctp_id2assoc(sk, val.spt_assoc_id);
        if (!asoc)
            return -ENOENT;

        val.spt_pathpfthld = asoc->pf_retrans;
        val.spt_pathmaxrxt = asoc->pathmaxrxt;
    } else {
        trans = sctp_addr_id2transport(sk, &val.spt_address,
                           val.spt_assoc_id);
        if (!trans)
            return -ENOENT;

        val.spt_pathmaxrxt = trans->pathmaxrxt;
        val.spt_pathpfthld = trans->pf_retrans;
    }

    if (put_user(len, optlen) || copy_to_user(optval, &val, len))
        return -EFAULT;

    return 0;
}

SCTP_STATIC int sctp_getsockopt(struct sock *sk, int level, int optname,
                char __user *optval, int __user *optlen)
{
    int retval = 0;
    int len;

    SCTP_DEBUG_PRINTK("sctp_getsockopt(sk: %p... optname: %d)\n",
              sk, optname);

    /* I can hardly begin to describe how wrong this is.  This is
     * so broken as to be worse than useless.  The API draft
     * REALLY is NOT helpful here...  I am not convinced that the
     * semantics of getsockopt() with a level OTHER THAN SOL_SCTP
     * are at all well-founded.
     */
    if (level != SOL_SCTP) {
        struct sctp_af *af = sctp_sk(sk)->pf->af;

        retval = af->getsockopt(sk, level, optname, optval, optlen);
        return retval;
    }

    if (get_user(len, optlen))
        return -EFAULT;

    sctp_lock_sock(sk);

    switch (optname) {
    case SCTP_STATUS:
        retval = sctp_getsockopt_sctp_status(sk, len, optval, optlen);
        break;
    case SCTP_DISABLE_FRAGMENTS:
        retval = sctp_getsockopt_disable_fragments(sk, len, optval,
                               optlen);
        break;
    case SCTP_EVENTS:
        retval = sctp_getsockopt_events(sk, len, optval, optlen);
        break;
    case SCTP_AUTOCLOSE:
        retval = sctp_getsockopt_autoclose(sk, len, optval, optlen);
        break;
    case SCTP_SOCKOPT_PEELOFF:
        retval = sctp_getsockopt_peeloff(sk, len, optval, optlen);
        break;
    case SCTP_PEER_ADDR_PARAMS:
        retval = sctp_getsockopt_peer_addr_params(sk, len, optval,
                              optlen);
        break;
    case SCTP_DELAYED_SACK:
        retval = sctp_getsockopt_delayed_ack(sk, len, optval,
                              optlen);
        break;
    case SCTP_INITMSG:
        retval = sctp_getsockopt_initmsg(sk, len, optval, optlen);
        break;
    case SCTP_GET_PEER_ADDRS:
        retval = sctp_getsockopt_peer_addrs(sk, len, optval,
                            optlen);
        break;
    case SCTP_GET_LOCAL_ADDRS:
        retval = sctp_getsockopt_local_addrs(sk, len, optval,
                             optlen);
        break;
    case SCTP_SOCKOPT_CONNECTX3:
        retval = sctp_getsockopt_connectx3(sk, len, optval, optlen);
        break;
    case SCTP_DEFAULT_SEND_PARAM:
        retval = sctp_getsockopt_default_send_param(sk, len,
                                optval, optlen);
        break;
    case SCTP_PRIMARY_ADDR:
        retval = sctp_getsockopt_primary_addr(sk, len, optval, optlen);
        break;
    case SCTP_NODELAY:
        retval = sctp_getsockopt_nodelay(sk, len, optval, optlen);
        break;
    case SCTP_RTOINFO:
        retval = sctp_getsockopt_rtoinfo(sk, len, optval, optlen);
        break;
    case SCTP_ASSOCINFO:
        retval = sctp_getsockopt_associnfo(sk, len, optval, optlen);
        break;
    case SCTP_I_WANT_MAPPED_V4_ADDR:
        retval = sctp_getsockopt_mappedv4(sk, len, optval, optlen);
        break;
    case SCTP_MAXSEG:
        retval = sctp_getsockopt_maxseg(sk, len, optval, optlen);
        break;
    case SCTP_GET_PEER_ADDR_INFO:
        retval = sctp_getsockopt_peer_addr_info(sk, len, optval,
                            optlen);
        break;
    case SCTP_ADAPTATION_LAYER:
        retval = sctp_getsockopt_adaptation_layer(sk, len, optval,
                            optlen);
        break;
    case SCTP_CONTEXT:
        retval = sctp_getsockopt_context(sk, len, optval, optlen);
        break;
    case SCTP_FRAGMENT_INTERLEAVE:
        retval = sctp_getsockopt_fragment_interleave(sk, len, optval,
                                 optlen);
        break;
    case SCTP_PARTIAL_DELIVERY_POINT:
        retval = sctp_getsockopt_partial_delivery_point(sk, len, optval,
                                optlen);
        break;
    case SCTP_MAX_BURST:
        retval = sctp_getsockopt_maxburst(sk, len, optval, optlen);
        break;
    case SCTP_AUTH_KEY:
    case SCTP_AUTH_CHUNK:
    case SCTP_AUTH_DELETE_KEY:
        retval = -EOPNOTSUPP;
        break;
    case SCTP_HMAC_IDENT:
        retval = sctp_getsockopt_hmac_ident(sk, len, optval, optlen);
        break;
    case SCTP_AUTH_ACTIVE_KEY:
        retval = sctp_getsockopt_active_key(sk, len, optval, optlen);
        break;
    case SCTP_PEER_AUTH_CHUNKS:
        retval = sctp_getsockopt_peer_auth_chunks(sk, len, optval,
                            optlen);
        break;
    case SCTP_LOCAL_AUTH_CHUNKS:
        retval = sctp_getsockopt_local_auth_chunks(sk, len, optval,
                            optlen);
        break;
    case SCTP_GET_ASSOC_NUMBER:
        retval = sctp_getsockopt_assoc_number(sk, len, optval, optlen);
        break;
    case SCTP_GET_ASSOC_ID_LIST:
        retval = sctp_getsockopt_assoc_ids(sk, len, optval, optlen);
        break;
    case SCTP_AUTO_ASCONF:
        retval = sctp_getsockopt_auto_asconf(sk, len, optval, optlen);
        break;
    case SCTP_PEER_ADDR_THLDS:
        retval = sctp_getsockopt_paddr_thresholds(sk, optval, len, optlen);
        break;
    default:
        retval = -ENOPROTOOPT;
        break;
    }

    sctp_release_sock(sk);
    return retval;
}

static void sctp_hash(struct sock *sk)
{
    /* STUB */
}

static void sctp_unhash(struct sock *sk)
{
    /* STUB */
}

/* Check if port is acceptable.  Possibly find first available port.
 *
 * The port hash table (contained in the 'global' SCTP protocol storage
 * returned by struct sctp_protocol *sctp_get_protocol()). The hash
 * table is an array of 4096 lists (sctp_bind_hashbucket). Each
 * list (the list number is the port number hashed out, so as you
 * would expect from a hash function, all the ports in a given list have
 * such a number that hashes out to the same list number; you were
 * expecting that, right?); so each list has a set of ports, with a
 * link to the socket (struct sock) that uses it, the port number and
 * a fastreuse flag (FIXME: NPI ipg).
 */
static struct sctp_bind_bucket *sctp_bucket_create(
    struct sctp_bind_hashbucket *head, struct net *, unsigned short snum);

static long sctp_get_port_local(struct sock *sk, union sctp_addr *addr)
{
    struct sctp_bind_hashbucket *head; /* hash list */
    struct sctp_bind_bucket *pp; /* hash list port iterator */
    struct hlist_node *node;
    unsigned short snum;
    int ret;

    snum = ntohs(addr->v4.sin_port);

    SCTP_DEBUG_PRINTK("sctp_get_port() begins, snum=%d\n", snum);
    sctp_local_bh_disable();

    if (snum == 0) {
        /* Search for an available port. */
        int low, high, remaining, index;
        unsigned int rover;

        inet_get_local_port_range(&low, &high);
        remaining = (high - low) + 1;
        rover = net_random() % remaining + low;

        do {
            rover++;
            if ((rover < low) || (rover > high))
                rover = low;
            if (inet_is_reserved_local_port(rover))
                continue;
            index = sctp_phashfn(sock_net(sk), rover);
            head = &sctp_port_hashtable[index];
            sctp_spin_lock(&head->lock);
            sctp_for_each_hentry(pp, node, &head->chain)
                if ((pp->port == rover) &&
                    net_eq(sock_net(sk), pp->net))
                    goto next;
            break;
        next:
            sctp_spin_unlock(&head->lock);
        } while (--remaining > 0);

        /* Exhausted local port range during search? */
        ret = 1;
        if (remaining <= 0)
            goto fail;

        /* OK, here is the one we will use.  HEAD (the port
         * hash table list entry) is non-NULL and we hold it's
         * mutex.
         */
        snum = rover;
    } else {
        /* We are given an specific port number; we verify
         * that it is not being used. If it is used, we will
         * exahust the search in the hash list corresponding
         * to the port number (snum) - we detect that with the
         * port iterator, pp being NULL.
         */
        head = &sctp_port_hashtable[sctp_phashfn(sock_net(sk), snum)];
        sctp_spin_lock(&head->lock);
        sctp_for_each_hentry(pp, node, &head->chain) {
            if ((pp->port == snum) && net_eq(pp->net, sock_net(sk)))
                goto pp_found;
        }
    }
    pp = NULL;
    goto pp_not_found;
pp_found:
    if (!hlist_empty(&pp->owner)) {
        /* We had a port hash table hit - there is an
         * available port (pp != NULL) and it is being
         * used by other socket (pp->owner not empty); that other
         * socket is going to be sk2.
         */
        int reuse = sk->sk_reuse;
        struct sock *sk2;

        SCTP_DEBUG_PRINTK("sctp_get_port() found a possible match\n");
        if (pp->fastreuse && sk->sk_reuse &&
            sk->sk_state != SCTP_SS_LISTENING)
            goto success;

        /* Run through the list of sockets bound to the port
         * (pp->port) [via the pointers bind_next and
         * bind_pprev in the struct sock *sk2 (pp->sk)]. On each one,
         * we get the endpoint they describe and run through
         * the endpoint's list of IP (v4 or v6) addresses,
         * comparing each of the addresses with the address of
         * the socket sk. If we find a match, then that means
         * that this port/socket (sk) combination are already
         * in an endpoint.
         */
        sk_for_each_bound(sk2, node, &pp->owner) {
            struct sctp_endpoint *ep2;
            ep2 = sctp_sk(sk2)->ep;

            if (sk == sk2 ||
                (reuse && sk2->sk_reuse &&
                 sk2->sk_state != SCTP_SS_LISTENING))
                continue;

            if (sctp_bind_addr_conflict(&ep2->base.bind_addr, addr,
                         sctp_sk(sk2), sctp_sk(sk))) {
                ret = (long)sk2;
                goto fail_unlock;
            }
        }
        SCTP_DEBUG_PRINTK("sctp_get_port(): Found a match\n");
    }
pp_not_found:
    /* If there was a hash table miss, create a new port.  */
    ret = 1;
    if (!pp && !(pp = sctp_bucket_create(head, sock_net(sk), snum)))
        goto fail_unlock;

    /* In either case (hit or miss), make sure fastreuse is 1 only
     * if sk->sk_reuse is too (that is, if the caller requested
     * SO_REUSEADDR on this socket -sk-).
     */
    if (hlist_empty(&pp->owner)) {
        if (sk->sk_reuse && sk->sk_state != SCTP_SS_LISTENING)
            pp->fastreuse = 1;
        else
            pp->fastreuse = 0;
    } else if (pp->fastreuse &&
        (!sk->sk_reuse || sk->sk_state == SCTP_SS_LISTENING))
        pp->fastreuse = 0;

    /* We are set, so fill up all the data in the hash table
     * entry, tie the socket list information with the rest of the
     * sockets FIXME: Blurry, NPI (ipg).
     */
success:
    if (!sctp_sk(sk)->bind_hash) {
        inet_sk(sk)->inet_num = snum;
        sk_add_bind_node(sk, &pp->owner);
        sctp_sk(sk)->bind_hash = pp;
    }
    ret = 0;

fail_unlock:
    sctp_spin_unlock(&head->lock);

fail:
    sctp_local_bh_enable();
    return ret;
}

/* Assign a 'snum' port to the socket.  If snum == 0, an ephemeral
 * port is requested.
 */
static int sctp_get_port(struct sock *sk, unsigned short snum)
{
    long ret;
    union sctp_addr addr;
    struct sctp_af *af = sctp_sk(sk)->pf->af;

    /* Set up a dummy address struct from the sk. */
    af->from_sk(&addr, sk);
    addr.v4.sin_port = htons(snum);

    /* Note: sk->sk_num gets filled in if ephemeral port request. */
    ret = sctp_get_port_local(sk, &addr);

    return ret ? 1 : 0;
}

/*
 *  Move a socket to LISTENING state.
 */
SCTP_STATIC int sctp_listen_start(struct sock *sk, int backlog)
{
    struct sctp_sock *sp = sctp_sk(sk);
    struct sctp_endpoint *ep = sp->ep;
    struct crypto_hash *tfm = NULL;

    /* Allocate HMAC for generating cookie. */
    if (!sctp_sk(sk)->hmac && sctp_hmac_alg) {
        tfm = crypto_alloc_hash(sctp_hmac_alg, 0, CRYPTO_ALG_ASYNC);
        if (IS_ERR(tfm)) {
            net_info_ratelimited("failed to load transform for %s: %ld\n",
                         sctp_hmac_alg, PTR_ERR(tfm));
            return -ENOSYS;
        }
        sctp_sk(sk)->hmac = tfm;
    }

    /*
     * If a bind() or sctp_bindx() is not called prior to a listen()
     * call that allows new associations to be accepted, the system
     * picks an ephemeral port and will choose an address set equivalent
     * to binding with a wildcard address.
     *
     * This is not currently spelled out in the SCTP sockets
     * extensions draft, but follows the practice as seen in TCP
     * sockets.
     *
     */
    sk->sk_state = SCTP_SS_LISTENING;
    if (!ep->base.bind_addr.port) {
        if (sctp_autobind(sk))
            return -EAGAIN;
    } else {
        if (sctp_get_port(sk, inet_sk(sk)->inet_num)) {
            sk->sk_state = SCTP_SS_CLOSED;
            return -EADDRINUSE;
        }
    }

    sk->sk_max_ack_backlog = backlog;
    sctp_hash_endpoint(ep);
    return 0;
}

/*
 * 4.1.3 / 5.1.3 listen()
 *
 *   By default, new associations are not accepted for UDP style sockets.
 *   An application uses listen() to mark a socket as being able to
 *   accept new associations.
 *
 *   On TCP style sockets, applications use listen() to ready the SCTP
 *   endpoint for accepting inbound associations.
 *
 *   On both types of endpoints a backlog of '0' disables listening.
 *
 *  Move a socket to LISTENING state.
 */
int sctp_inet_listen(struct socket *sock, int backlog)
{
    struct sock *sk = sock->sk;
    struct sctp_endpoint *ep = sctp_sk(sk)->ep;
    int err = -EINVAL;

    if (unlikely(backlog < 0))
        return err;

    sctp_lock_sock(sk);

    /* Peeled-off sockets are not allowed to listen().  */
    if (sctp_style(sk, UDP_HIGH_BANDWIDTH))
        goto out;

    if (sock->state != SS_UNCONNECTED)
        goto out;

    /* If backlog is zero, disable listening. */
    if (!backlog) {
        if (sctp_sstate(sk, CLOSED))
            goto out;

        err = 0;
        sctp_unhash_endpoint(ep);
        sk->sk_state = SCTP_SS_CLOSED;
        if (sk->sk_reuse)
            sctp_sk(sk)->bind_hash->fastreuse = 1;
        goto out;
    }

    /* If we are already listening, just update the backlog */
    if (sctp_sstate(sk, LISTENING))
        sk->sk_max_ack_backlog = backlog;
    else {
        err = sctp_listen_start(sk, backlog);
        if (err)
            goto out;
    }

    err = 0;
out:
    sctp_release_sock(sk);
    return err;
}

/*
 * This function is done by modeling the current datagram_poll() and the
 * tcp_poll().  Note that, based on these implementations, we don't
 * lock the socket in this function, even though it seems that,
 * ideally, locking or some other mechanisms can be used to ensure
 * the integrity of the counters (sndbuf and wmem_alloc) used
 * in this place.  We assume that we don't need locks either until proven
 * otherwise.
 *
 * Another thing to note is that we include the Async I/O support
 * here, again, by modeling the current TCP/UDP code.  We don't have
 * a good way to test with it yet.
 */
unsigned int sctp_poll(struct file *file, struct socket *sock, poll_table *wait)
{
    struct sock *sk = sock->sk;
    struct sctp_sock *sp = sctp_sk(sk);
    unsigned int mask;

    poll_wait(file, sk_sleep(sk), wait);

    /* A TCP-style listening socket becomes readable when the accept queue
     * is not empty.
     */
    if (sctp_style(sk, TCP) && sctp_sstate(sk, LISTENING))
        return (!list_empty(&sp->ep->asocs)) ?
            (POLLIN | POLLRDNORM) : 0;

    mask = 0;

    /* Is there any exceptional events?  */
    if (sk->sk_err || !skb_queue_empty(&sk->sk_error_queue))
        mask |= POLLERR;
    if (sk->sk_shutdown & RCV_SHUTDOWN)
        mask |= POLLRDHUP | POLLIN | POLLRDNORM;
    if (sk->sk_shutdown == SHUTDOWN_MASK)
        mask |= POLLHUP;

    /* Is it readable?  Reconsider this code with TCP-style support.  */
    if (!skb_queue_empty(&sk->sk_receive_queue))
        mask |= POLLIN | POLLRDNORM;

    /* The association is either gone or not ready.  */
    if (!sctp_style(sk, UDP) && sctp_sstate(sk, CLOSED))
        return mask;

    /* Is it writable?  */
    if (sctp_writeable(sk)) {
        mask |= POLLOUT | POLLWRNORM;
    } else {
        set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
        /*
         * Since the socket is not locked, the buffer
         * might be made available after the writeable check and
         * before the bit is set.  This could cause a lost I/O
         * signal.  tcp_poll() has a race breaker for this race
         * condition.  Based on their implementation, we put
         * in the following code to cover it as well.
         */
        if (sctp_writeable(sk))
            mask |= POLLOUT | POLLWRNORM;
    }
    return mask;
}

/********************************************************************
 * 2nd Level Abstractions
 ********************************************************************/

static struct sctp_bind_bucket *sctp_bucket_create(
    struct sctp_bind_hashbucket *head, struct net *net, unsigned short snum)
{
    struct sctp_bind_bucket *pp;

    pp = kmem_cache_alloc(sctp_bucket_cachep, GFP_ATOMIC);
    if (pp) {
        SCTP_DBG_OBJCNT_INC(bind_bucket);
        pp->port = snum;
        pp->fastreuse = 0;
        INIT_HLIST_HEAD(&pp->owner);
        pp->net = net;
        hlist_add_head(&pp->node, &head->chain);
    }
    return pp;
}

/* Caller must hold hashbucket lock for this tb with local BH disabled */
static void sctp_bucket_destroy(struct sctp_bind_bucket *pp)
{
    if (pp && hlist_empty(&pp->owner)) {
        __hlist_del(&pp->node);
        kmem_cache_free(sctp_bucket_cachep, pp);
        SCTP_DBG_OBJCNT_DEC(bind_bucket);
    }
}

/* Release this socket's reference to a local port.  */
static inline void __sctp_put_port(struct sock *sk)
{
    struct sctp_bind_hashbucket *head =
        &sctp_port_hashtable[sctp_phashfn(sock_net(sk),
                          inet_sk(sk)->inet_num)];
    struct sctp_bind_bucket *pp;

    sctp_spin_lock(&head->lock);
    pp = sctp_sk(sk)->bind_hash;
    __sk_del_bind_node(sk);
    sctp_sk(sk)->bind_hash = NULL;
    inet_sk(sk)->inet_num = 0;
    sctp_bucket_destroy(pp);
    sctp_spin_unlock(&head->lock);
}

void sctp_put_port(struct sock *sk)
{
    sctp_local_bh_disable();
    __sctp_put_port(sk);
    sctp_local_bh_enable();
}

/*
 * The system picks an ephemeral port and choose an address set equivalent
 * to binding with a wildcard address.
 * One of those addresses will be the primary address for the association.
 * This automatically enables the multihoming capability of SCTP.
 */
static int sctp_autobind(struct sock *sk)
{
    union sctp_addr autoaddr;
    struct sctp_af *af;
    __be16 port;

    /* Initialize a local sockaddr structure to INADDR_ANY. */
    af = sctp_sk(sk)->pf->af;

    port = htons(inet_sk(sk)->inet_num);
    af->inaddr_any(&autoaddr, port);

    return sctp_do_bind(sk, &autoaddr, af->sockaddr_len);
}

/* Parse out IPPROTO_SCTP CMSG headers.  Perform only minimal validation.
 *
 * From RFC 2292
 * 4.2 The cmsghdr Structure *
 *
 * When ancillary data is sent or received, any number of ancillary data
 * objects can be specified by the msg_control and msg_controllen members of
 * the msghdr structure, because each object is preceded by
 * a cmsghdr structure defining the object's length (the cmsg_len member).
 * Historically Berkeley-derived implementations have passed only one object
 * at a time, but this API allows multiple objects to be
 * passed in a single call to sendmsg() or recvmsg(). The following example
 * shows two ancillary data objects in a control buffer.
 *
 *   |<--------------------------- msg_controllen -------------------------->|
 *   |                                                                       |
 *
 *   |<----- ancillary data object ----->|<----- ancillary data object ----->|
 *
 *   |<---------- CMSG_SPACE() --------->|<---------- CMSG_SPACE() --------->|
 *   |                                   |                                   |
 *
 *   |<---------- cmsg_len ---------->|  |<--------- cmsg_len ----------->|  |
 *
 *   |<--------- CMSG_LEN() --------->|  |<-------- CMSG_LEN() ---------->|  |
 *   |                                |  |                                |  |
 *
 *   +-----+-----+-----+--+-----------+--+-----+-----+-----+--+-----------+--+
 *   |cmsg_|cmsg_|cmsg_|XX|           |XX|cmsg_|cmsg_|cmsg_|XX|           |XX|
 *
 *   |len  |level|type |XX|cmsg_data[]|XX|len  |level|type |XX|cmsg_data[]|XX|
 *
 *   +-----+-----+-----+--+-----------+--+-----+-----+-----+--+-----------+--+
 *    ^
 *    |
 *
 * msg_control
 * points here
 */
SCTP_STATIC int sctp_msghdr_parse(const struct msghdr *msg,
                  sctp_cmsgs_t *cmsgs)
{
    struct cmsghdr *cmsg;
    struct msghdr *my_msg = (struct msghdr *)msg;

    for (cmsg = CMSG_FIRSTHDR(msg);
         cmsg != NULL;
         cmsg = CMSG_NXTHDR(my_msg, cmsg)) {
        if (!CMSG_OK(my_msg, cmsg))
            return -EINVAL;

        /* Should we parse this header or ignore?  */
        if (cmsg->cmsg_level != IPPROTO_SCTP)
            continue;

        /* Strictly check lengths following example in SCM code.  */
        switch (cmsg->cmsg_type) {
        case SCTP_INIT:
            /* SCTP Socket API Extension
             * 5.2.1 SCTP Initiation Structure (SCTP_INIT)
             *
             * This cmsghdr structure provides information for
             * initializing new SCTP associations with sendmsg().
             * The SCTP_INITMSG socket option uses this same data
             * structure.  This structure is not used for
             * recvmsg().
             *
             * cmsg_level    cmsg_type      cmsg_data[]
             * ------------  ------------   ----------------------
             * IPPROTO_SCTP  SCTP_INIT      struct sctp_initmsg
             */
            if (cmsg->cmsg_len !=
                CMSG_LEN(sizeof(struct sctp_initmsg)))
                return -EINVAL;
            cmsgs->init = (struct sctp_initmsg *)CMSG_DATA(cmsg);
            break;

        case SCTP_SNDRCV:
            /* SCTP Socket API Extension
             * 5.2.2 SCTP Header Information Structure(SCTP_SNDRCV)
             *
             * This cmsghdr structure specifies SCTP options for
             * sendmsg() and describes SCTP header information
             * about a received message through recvmsg().
             *
             * cmsg_level    cmsg_type      cmsg_data[]
             * ------------  ------------   ----------------------
             * IPPROTO_SCTP  SCTP_SNDRCV    struct sctp_sndrcvinfo
             */
            if (cmsg->cmsg_len !=
                CMSG_LEN(sizeof(struct sctp_sndrcvinfo)))
                return -EINVAL;

            cmsgs->info =
                (struct sctp_sndrcvinfo *)CMSG_DATA(cmsg);

            /* Minimally, validate the sinfo_flags. */
            if (cmsgs->info->sinfo_flags &
                ~(SCTP_UNORDERED | SCTP_ADDR_OVER |
                  SCTP_ABORT | SCTP_EOF))
                return -EINVAL;
            break;

        default:
            return -EINVAL;
        }
    }
    return 0;
}

/*
 * Wait for a packet..
 * Note: This function is the same function as in core/datagram.c
 * with a few modifications to make lksctp work.
 */
static int sctp_wait_for_packet(struct sock * sk, int *err, long *timeo_p)
{
    int error;
    DEFINE_WAIT(wait);

    prepare_to_wait_exclusive(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);

    /* Socket errors? */
    error = sock_error(sk);
    if (error)
        goto out;

    if (!skb_queue_empty(&sk->sk_receive_queue))
        goto ready;

    /* Socket shut down?  */
    if (sk->sk_shutdown & RCV_SHUTDOWN)
        goto out;

    /* Sequenced packets can come disconnected.  If so we report the
     * problem.
     */
    error = -ENOTCONN;

    /* Is there a good reason to think that we may receive some data?  */
    if (list_empty(&sctp_sk(sk)->ep->asocs) && !sctp_sstate(sk, LISTENING))
        goto out;

    /* Handle signals.  */
    if (signal_pending(current))
        goto interrupted;

    /* Let another process have a go.  Since we are going to sleep
     * anyway.  Note: This may cause odd behaviors if the message
     * does not fit in the user's buffer, but this seems to be the
     * only way to honor MSG_DONTWAIT realistically.
     */
    sctp_release_sock(sk);
    *timeo_p = schedule_timeout(*timeo_p);
    sctp_lock_sock(sk);

ready:
    finish_wait(sk_sleep(sk), &wait);
    return 0;

interrupted:
    error = sock_intr_errno(*timeo_p);

out:
    finish_wait(sk_sleep(sk), &wait);
    *err = error;
    return error;
}

/* Receive a datagram.
 * Note: This is pretty much the same routine as in core/datagram.c
 * with a few changes to make lksctp work.
 */
static struct sk_buff *sctp_skb_recv_datagram(struct sock *sk, int flags,
                          int noblock, int *err)
{
    int error;
    struct sk_buff *skb;
    long timeo;

    timeo = sock_rcvtimeo(sk, noblock);

    SCTP_DEBUG_PRINTK("Timeout: timeo: %ld, MAX: %ld.\n",
              timeo, MAX_SCHEDULE_TIMEOUT);

    do {
        /* Again only user level code calls this function,
         * so nothing interrupt level
         * will suddenly eat the receive_queue.
         *
         *  Look at current nfs client by the way...
         *  However, this function was correct in any case. 8)
         */
        if (flags & MSG_PEEK) {
            spin_lock_bh(&sk->sk_receive_queue.lock);
            skb = skb_peek(&sk->sk_receive_queue);
            if (skb)
                atomic_inc(&skb->users);
            spin_unlock_bh(&sk->sk_receive_queue.lock);
        } else {
            skb = skb_dequeue(&sk->sk_receive_queue);
        }

        if (skb)
            return skb;

        /* Caller is allowed not to check sk->sk_err before calling. */
        error = sock_error(sk);
        if (error)
            goto no_packet;

        if (sk->sk_shutdown & RCV_SHUTDOWN)
            break;

        /* User doesn't want to wait.  */
        error = -EAGAIN;
        if (!timeo)
            goto no_packet;
    } while (sctp_wait_for_packet(sk, err, &timeo) == 0);

    return NULL;

no_packet:
    *err = error;
    return NULL;
}

/* If sndbuf has changed, wake up per association sndbuf waiters.  */
static void __sctp_write_space(struct sctp_association *asoc)
{
    struct sock *sk = asoc->base.sk;
    struct socket *sock = sk->sk_socket;

    if ((sctp_wspace(asoc) > 0) && sock) {
        if (waitqueue_active(&asoc->wait))
            wake_up_interruptible(&asoc->wait);

        if (sctp_writeable(sk)) {
            wait_queue_head_t *wq = sk_sleep(sk);

            if (wq && waitqueue_active(wq))
                wake_up_interruptible(wq);

            /* Note that we try to include the Async I/O support
             * here by modeling from the current TCP/UDP code.
             * We have not tested with it yet.
             */
            if (!(sk->sk_shutdown & SEND_SHUTDOWN))
                sock_wake_async(sock,
                        SOCK_WAKE_SPACE, POLL_OUT);
        }
    }
}

/* Do accounting for the sndbuf space.
 * Decrement the used sndbuf space of the corresponding association by the
 * data size which was just transmitted(freed).
 */
static void sctp_wfree(struct sk_buff *skb)
{
    struct sctp_association *asoc;
    struct sctp_chunk *chunk;
    struct sock *sk;

    /* Get the saved chunk pointer.  */
    chunk = *((struct sctp_chunk **)(skb->cb));
    asoc = chunk->asoc;
    sk = asoc->base.sk;
    asoc->sndbuf_used -= SCTP_DATA_SNDSIZE(chunk) +
                sizeof(struct sk_buff) +
                sizeof(struct sctp_chunk);

    atomic_sub(sizeof(struct sctp_chunk), &sk->sk_wmem_alloc);

    /*
     * This undoes what is done via sctp_set_owner_w and sk_mem_charge
     */
    sk->sk_wmem_queued   -= skb->truesize;
    sk_mem_uncharge(sk, skb->truesize);

    sock_wfree(skb);
    __sctp_write_space(asoc);

    sctp_association_put(asoc);
}

/* Do accounting for the receive space on the socket.
 * Accounting for the association is done in ulpevent.c
 * We set this as a destructor for the cloned data skbs so that
 * accounting is done at the correct time.
 */
void sctp_sock_rfree(struct sk_buff *skb)
{
    struct sock *sk = skb->sk;
    struct sctp_ulpevent *event = sctp_skb2event(skb);

    atomic_sub(event->rmem_len, &sk->sk_rmem_alloc);

    /*
     * Mimic the behavior of sock_rfree
     */
    sk_mem_uncharge(sk, event->rmem_len);
}


/* Helper function to wait for space in the sndbuf.  */
static int sctp_wait_for_sndbuf(struct sctp_association *asoc, long *timeo_p,
                size_t msg_len)
{
    struct sock *sk = asoc->base.sk;
    int err = 0;
    long current_timeo = *timeo_p;
    DEFINE_WAIT(wait);

    SCTP_DEBUG_PRINTK("wait_for_sndbuf: asoc=%p, timeo=%ld, msg_len=%zu\n",
              asoc, (long)(*timeo_p), msg_len);

    /* Increment the association's refcnt.  */
    sctp_association_hold(asoc);

    /* Wait on the association specific sndbuf space. */
    for (;;) {
        prepare_to_wait_exclusive(&asoc->wait, &wait,
                      TASK_INTERRUPTIBLE);
        if (!*timeo_p)
            goto do_nonblock;
        if (sk->sk_err || asoc->state >= SCTP_STATE_SHUTDOWN_PENDING ||
            asoc->base.dead)
            goto do_error;
        if (signal_pending(current))
            goto do_interrupted;
        if (msg_len <= sctp_wspace(asoc))
            break;

        /* Let another process have a go.  Since we are going
         * to sleep anyway.
         */
        sctp_release_sock(sk);
        current_timeo = schedule_timeout(current_timeo);
        BUG_ON(sk != asoc->base.sk);
        sctp_lock_sock(sk);

        *timeo_p = current_timeo;
    }

out:
    finish_wait(&asoc->wait, &wait);

    /* Release the association's refcnt.  */
    sctp_association_put(asoc);

    return err;

do_error:
    err = -EPIPE;
    goto out;

do_interrupted:
    err = sock_intr_errno(*timeo_p);
    goto out;

do_nonblock:
    err = -EAGAIN;
    goto out;
}

void sctp_data_ready(struct sock *sk, int len)
{
    struct socket_wq *wq;

    rcu_read_lock();
    wq = rcu_dereference(sk->sk_wq);
    if (wq_has_sleeper(wq))
        wake_up_interruptible_sync_poll(&wq->wait, POLLIN |
                        POLLRDNORM | POLLRDBAND);
    sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_IN);
    rcu_read_unlock();
}

/* If socket sndbuf has changed, wake up all per association waiters.  */
void sctp_write_space(struct sock *sk)
{
    struct sctp_association *asoc;

    /* Wake up the tasks in each wait queue.  */
    list_for_each_entry(asoc, &((sctp_sk(sk))->ep->asocs), asocs) {
        __sctp_write_space(asoc);
    }
}

/* Is there any sndbuf space available on the socket?
 *
 * Note that sk_wmem_alloc is the sum of the send buffers on all of the
 * associations on the same socket.  For a UDP-style socket with
 * multiple associations, it is possible for it to be "unwriteable"
 * prematurely.  I assume that this is acceptable because
 * a premature "unwriteable" is better than an accidental "writeable" which
 * would cause an unwanted block under certain circumstances.  For the 1-1
 * UDP-style sockets or TCP-style sockets, this code should work.
 *  - Daisy
 */
static int sctp_writeable(struct sock *sk)
{
    int amt = 0;

    amt = sk->sk_sndbuf - sk_wmem_alloc_get(sk);
    if (amt < 0)
        amt = 0;
    return amt;
}

/* Wait for an association to go into ESTABLISHED state. If timeout is 0,
 * returns immediately with EINPROGRESS.
 */
static int sctp_wait_for_connect(struct sctp_association *asoc, long *timeo_p)
{
    struct sock *sk = asoc->base.sk;
    int err = 0;
    long current_timeo = *timeo_p;
    DEFINE_WAIT(wait);

    SCTP_DEBUG_PRINTK("%s: asoc=%p, timeo=%ld\n", __func__, asoc,
              (long)(*timeo_p));

    /* Increment the association's refcnt.  */
    sctp_association_hold(asoc);

    for (;;) {
        prepare_to_wait_exclusive(&asoc->wait, &wait,
                      TASK_INTERRUPTIBLE);
        if (!*timeo_p)
            goto do_nonblock;
        if (sk->sk_shutdown & RCV_SHUTDOWN)
            break;
        if (sk->sk_err || asoc->state >= SCTP_STATE_SHUTDOWN_PENDING ||
            asoc->base.dead)
            goto do_error;
        if (signal_pending(current))
            goto do_interrupted;

        if (sctp_state(asoc, ESTABLISHED))
            break;

        /* Let another process have a go.  Since we are going
         * to sleep anyway.
         */
        sctp_release_sock(sk);
        current_timeo = schedule_timeout(current_timeo);
        sctp_lock_sock(sk);

        *timeo_p = current_timeo;
    }

out:
    finish_wait(&asoc->wait, &wait);

    /* Release the association's refcnt.  */
    sctp_association_put(asoc);

    return err;

do_error:
    if (asoc->init_err_counter + 1 > asoc->max_init_attempts)
        err = -ETIMEDOUT;
    else
        err = -ECONNREFUSED;
    goto out;

do_interrupted:
    err = sock_intr_errno(*timeo_p);
    goto out;

do_nonblock:
    err = -EINPROGRESS;
    goto out;
}

static int sctp_wait_for_accept(struct sock *sk, long timeo)
{
    struct sctp_endpoint *ep;
    int err = 0;
    DEFINE_WAIT(wait);

    ep = sctp_sk(sk)->ep;


    for (;;) {
        prepare_to_wait_exclusive(sk_sleep(sk), &wait,
                      TASK_INTERRUPTIBLE);

        if (list_empty(&ep->asocs)) {
            sctp_release_sock(sk);
            timeo = schedule_timeout(timeo);
            sctp_lock_sock(sk);
        }

        err = -EINVAL;
        if (!sctp_sstate(sk, LISTENING))
            break;

        err = 0;
        if (!list_empty(&ep->asocs))
            break;

        err = sock_intr_errno(timeo);
        if (signal_pending(current))
            break;

        err = -EAGAIN;
        if (!timeo)
            break;
    }

    finish_wait(sk_sleep(sk), &wait);

    return err;
}

static void sctp_wait_for_close(struct sock *sk, long timeout)
{
    DEFINE_WAIT(wait);

    do {
        prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
        if (list_empty(&sctp_sk(sk)->ep->asocs))
            break;
        sctp_release_sock(sk);
        timeout = schedule_timeout(timeout);
        sctp_lock_sock(sk);
    } while (!signal_pending(current) && timeout);

    finish_wait(sk_sleep(sk), &wait);
}

static void sctp_skb_set_owner_r_frag(struct sk_buff *skb, struct sock *sk)
{
    struct sk_buff *frag;

    if (!skb->data_len)
        goto done;

    /* Don't forget the fragments. */
    skb_walk_frags(skb, frag)
        sctp_skb_set_owner_r_frag(frag, sk);

done:
    sctp_skb_set_owner_r(skb, sk);
}

void sctp_copy_sock(struct sock *newsk, struct sock *sk,
            struct sctp_association *asoc)
{
    struct inet_sock *inet = inet_sk(sk);
    struct inet_sock *newinet;

    newsk->sk_type = sk->sk_type;
    newsk->sk_bound_dev_if = sk->sk_bound_dev_if;
    newsk->sk_flags = sk->sk_flags;
    newsk->sk_no_check = sk->sk_no_check;
    newsk->sk_reuse = sk->sk_reuse;

    newsk->sk_shutdown = sk->sk_shutdown;
    newsk->sk_destruct = inet_sock_destruct;
    newsk->sk_family = sk->sk_family;
    newsk->sk_protocol = IPPROTO_SCTP;
    newsk->sk_backlog_rcv = sk->sk_prot->backlog_rcv;
    newsk->sk_sndbuf = sk->sk_sndbuf;
    newsk->sk_rcvbuf = sk->sk_rcvbuf;
    newsk->sk_lingertime = sk->sk_lingertime;
    newsk->sk_rcvtimeo = sk->sk_rcvtimeo;
    newsk->sk_sndtimeo = sk->sk_sndtimeo;

    newinet = inet_sk(newsk);

    /* Initialize sk's sport, dport, rcv_saddr and daddr for
     * getsockname() and getpeername()
     */
    newinet->inet_sport = inet->inet_sport;
    newinet->inet_saddr = inet->inet_saddr;
    newinet->inet_rcv_saddr = inet->inet_rcv_saddr;
    newinet->inet_dport = htons(asoc->peer.port);
    newinet->pmtudisc = inet->pmtudisc;
    newinet->inet_id = asoc->next_tsn ^ jiffies;

    newinet->uc_ttl = inet->uc_ttl;
    newinet->mc_loop = 1;
    newinet->mc_ttl = 1;
    newinet->mc_index = 0;
    newinet->mc_list = NULL;
}

/* Populate the fields of the newsk from the oldsk and migrate the assoc
 * and its messages to the newsk.
 */
static void sctp_sock_migrate(struct sock *oldsk, struct sock *newsk,
                  struct sctp_association *assoc,
                  sctp_socket_type_t type)
{
    struct sctp_sock *oldsp = sctp_sk(oldsk);
    struct sctp_sock *newsp = sctp_sk(newsk);
    struct sctp_bind_bucket *pp; /* hash list port iterator */
    struct sctp_endpoint *newep = newsp->ep;
    struct sk_buff *skb, *tmp;
    struct sctp_ulpevent *event;
    struct sctp_bind_hashbucket *head;
    struct list_head tmplist;

    /* Migrate socket buffer sizes and all the socket level options to the
     * new socket.
     */
    newsk->sk_sndbuf = oldsk->sk_sndbuf;
    newsk->sk_rcvbuf = oldsk->sk_rcvbuf;
    /* Brute force copy old sctp opt. */
    if (oldsp->do_auto_asconf) {
        memcpy(&tmplist, &newsp->auto_asconf_list, sizeof(tmplist));
        inet_sk_copy_descendant(newsk, oldsk);
        memcpy(&newsp->auto_asconf_list, &tmplist, sizeof(tmplist));
    } else
        inet_sk_copy_descendant(newsk, oldsk);

    /* Restore the ep value that was overwritten with the above structure
     * copy.
     */
    newsp->ep = newep;
    newsp->hmac = NULL;

    /* Hook this new socket in to the bind_hash list. */
    head = &sctp_port_hashtable[sctp_phashfn(sock_net(oldsk),
                         inet_sk(oldsk)->inet_num)];
    sctp_local_bh_disable();
    sctp_spin_lock(&head->lock);
    pp = sctp_sk(oldsk)->bind_hash;
    sk_add_bind_node(newsk, &pp->owner);
    sctp_sk(newsk)->bind_hash = pp;
    inet_sk(newsk)->inet_num = inet_sk(oldsk)->inet_num;
    sctp_spin_unlock(&head->lock);
    sctp_local_bh_enable();

    /* Copy the bind_addr list from the original endpoint to the new
     * endpoint so that we can handle restarts properly
     */
    sctp_bind_addr_dup(&newsp->ep->base.bind_addr,
                &oldsp->ep->base.bind_addr, GFP_KERNEL);

    /* Move any messages in the old socket's receive queue that are for the
     * peeled off association to the new socket's receive queue.
     */
    sctp_skb_for_each(skb, &oldsk->sk_receive_queue, tmp) {
        event = sctp_skb2event(skb);
        if (event->asoc == assoc) {
            __skb_unlink(skb, &oldsk->sk_receive_queue);
            __skb_queue_tail(&newsk->sk_receive_queue, skb);
            sctp_skb_set_owner_r_frag(skb, newsk);
        }
    }

    /* Clean up any messages pending delivery due to partial
     * delivery.   Three cases:
     * 1) No partial deliver;  no work.
     * 2) Peeling off partial delivery; keep pd_lobby in new pd_lobby.
     * 3) Peeling off non-partial delivery; move pd_lobby to receive_queue.
     */
    skb_queue_head_init(&newsp->pd_lobby);
    atomic_set(&sctp_sk(newsk)->pd_mode, assoc->ulpq.pd_mode);

    if (atomic_read(&sctp_sk(oldsk)->pd_mode)) {
        struct sk_buff_head *queue;

        /* Decide which queue to move pd_lobby skbs to. */
        if (assoc->ulpq.pd_mode) {
            queue = &newsp->pd_lobby;
        } else
            queue = &newsk->sk_receive_queue;

        /* Walk through the pd_lobby, looking for skbs that
         * need moved to the new socket.
         */
        sctp_skb_for_each(skb, &oldsp->pd_lobby, tmp) {
            event = sctp_skb2event(skb);
            if (event->asoc == assoc) {
                __skb_unlink(skb, &oldsp->pd_lobby);
                __skb_queue_tail(queue, skb);
                sctp_skb_set_owner_r_frag(skb, newsk);
            }
        }

        /* Clear up any skbs waiting for the partial
         * delivery to finish.
         */
        if (assoc->ulpq.pd_mode)
            sctp_clear_pd(oldsk, NULL);

    }

    sctp_skb_for_each(skb, &assoc->ulpq.reasm, tmp)
        sctp_skb_set_owner_r_frag(skb, newsk);

    sctp_skb_for_each(skb, &assoc->ulpq.lobby, tmp)
        sctp_skb_set_owner_r_frag(skb, newsk);

    /* Set the type of socket to indicate that it is peeled off from the
     * original UDP-style socket or created with the accept() call on a
     * TCP-style socket..
     */
    newsp->type = type;

    /* Mark the new socket "in-use" by the user so that any packets
     * that may arrive on the association after we've moved it are
     * queued to the backlog.  This prevents a potential race between
     * backlog processing on the old socket and new-packet processing
     * on the new socket.
     *
     * The caller has just allocated newsk so we can guarantee that other
     * paths won't try to lock it and then oldsk.
     */
    lock_sock_nested(newsk, SINGLE_DEPTH_NESTING);
    sctp_assoc_migrate(assoc, newsk);

    /* If the association on the newsk is already closed before accept()
     * is called, set RCV_SHUTDOWN flag.
     */
    if (sctp_state(assoc, CLOSED) && sctp_style(newsk, TCP))
        newsk->sk_shutdown |= RCV_SHUTDOWN;

    newsk->sk_state = SCTP_SS_ESTABLISHED;
    sctp_release_sock(newsk);
}


/* This proto struct describes the ULP interface for SCTP.  */
struct proto sctp_prot = {
    .name        =  "SCTP",
    .owner       =  THIS_MODULE,
    .close       =  sctp_close,
    .connect     =  sctp_connect,
    .disconnect  =  sctp_disconnect,
    .accept      =  sctp_accept,
    .ioctl       =  sctp_ioctl,
    .init        =  sctp_init_sock,
    .destroy     =  sctp_destroy_sock,
    .shutdown    =  sctp_shutdown,
    .setsockopt  =  sctp_setsockopt,
    .getsockopt  =  sctp_getsockopt,
    .sendmsg     =  sctp_sendmsg,
    .recvmsg     =  sctp_recvmsg,
    .bind        =  sctp_bind,
    .backlog_rcv =  sctp_backlog_rcv,
    .hash        =  sctp_hash,
    .unhash      =  sctp_unhash,
    .get_port    =  sctp_get_port,
    .obj_size    =  sizeof(struct sctp_sock),
    .sysctl_mem  =  sysctl_sctp_mem,
    .sysctl_rmem =  sysctl_sctp_rmem,
    .sysctl_wmem =  sysctl_sctp_wmem,
    .memory_pressure = &sctp_memory_pressure,
    .enter_memory_pressure = sctp_enter_memory_pressure,
    .memory_allocated = &sctp_memory_allocated,
    .sockets_allocated = &sctp_sockets_allocated,
};

#if IS_ENABLED(CONFIG_IPV6)

struct proto sctpv6_prot = {
    .name       = "SCTPv6",
    .owner      = THIS_MODULE,
    .close      = sctp_close,
    .connect    = sctp_connect,
    .disconnect = sctp_disconnect,
    .accept     = sctp_accept,
    .ioctl      = sctp_ioctl,
    .init       = sctp_init_sock,
    .destroy    = sctp_destroy_sock,
    .shutdown   = sctp_shutdown,
    .setsockopt = sctp_setsockopt,
    .getsockopt = sctp_getsockopt,
    .sendmsg    = sctp_sendmsg,
    .recvmsg    = sctp_recvmsg,
    .bind       = sctp_bind,
    .backlog_rcv    = sctp_backlog_rcv,
    .hash       = sctp_hash,
    .unhash     = sctp_unhash,
    .get_port   = sctp_get_port,
    .obj_size   = sizeof(struct sctp6_sock),
    .sysctl_mem = sysctl_sctp_mem,
    .sysctl_rmem    = sysctl_sctp_rmem,
    .sysctl_wmem    = sysctl_sctp_wmem,
    .memory_pressure = &sctp_memory_pressure,
    .enter_memory_pressure = sctp_enter_memory_pressure,
    .memory_allocated = &sctp_memory_allocated,
    .sockets_allocated = &sctp_sockets_allocated,
};
#endif /* IS_ENABLED(CONFIG_IPV6) */