af_decnet.c

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/*
 * DECnet       An implementation of the DECnet protocol suite for the LINUX
 *              operating system.  DECnet is implemented using the  BSD Socket
 *              interface as the means of communication with the user level.
 *
 *              DECnet Socket Layer Interface
 *
 * Authors:     Eduardo Marcelo Serrat <[email protected]>
 *              Patrick Caulfield <[email protected]>
 *
 * Changes:
 *        Steve Whitehouse: Copied from Eduardo Serrat and Patrick Caulfield's
 *                          version of the code. Original copyright preserved
 *                          below.
 *        Steve Whitehouse: Some bug fixes, cleaning up some code to make it
 *                          compatible with my routing layer.
 *        Steve Whitehouse: Merging changes from Eduardo Serrat and Patrick
 *                          Caulfield.
 *        Steve Whitehouse: Further bug fixes, checking module code still works
 *                          with new routing layer.
 *        Steve Whitehouse: Additional set/get_sockopt() calls.
 *        Steve Whitehouse: Fixed TIOCINQ ioctl to be same as Eduardo's new
 *                          code.
 *        Steve Whitehouse: recvmsg() changed to try and behave in a POSIX like
 *                          way. Didn't manage it entirely, but its better.
 *        Steve Whitehouse: ditto for sendmsg().
 *        Steve Whitehouse: A selection of bug fixes to various things.
 *        Steve Whitehouse: Added TIOCOUTQ ioctl.
 *        Steve Whitehouse: Fixes to username2sockaddr & sockaddr2username.
 *        Steve Whitehouse: Fixes to connect() error returns.
 *       Patrick Caulfield: Fixes to delayed acceptance logic.
 *         David S. Miller: New socket locking
 *        Steve Whitehouse: Socket list hashing/locking
 *         Arnaldo C. Melo: use capable, not suser
 *        Steve Whitehouse: Removed unused code. Fix to use sk->allocation
 *                          when required.
 *       Patrick Caulfield: /proc/net/decnet now has object name/number
 *        Steve Whitehouse: Fixed local port allocation, hashed sk list
 *          Matthew Wilcox: Fixes for dn_ioctl()
 *        Steve Whitehouse: New connect/accept logic to allow timeouts and
 *                          prepare for sendpage etc.
 */


/******************************************************************************
    (c) 1995-1998 E.M. Serrat       [email protected]

    This program 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 of the License, or
    any later version.

    This program 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.

HISTORY:

Version           Kernel     Date       Author/Comments
-------           ------     ----       ---------------
Version 0.0.1     2.0.30    01-dic-97   Eduardo Marcelo Serrat
                    ([email protected])

                    First Development of DECnet Socket La-
                    yer for Linux. Only supports outgoing
                    connections.

Version 0.0.2     2.1.105   20-jun-98   Patrick J. Caulfield
                    ([email protected])

                    Port to new kernel development version.

Version 0.0.3     2.1.106   25-jun-98   Eduardo Marcelo Serrat
                    ([email protected])
                    _
                    Added support for incoming connections
                    so we can start developing server apps
                    on Linux.
                    -
                    Module Support
Version 0.0.4     2.1.109   21-jul-98   Eduardo Marcelo Serrat
                       ([email protected])
                       _
                    Added support for X11R6.4. Now we can
                    use DECnet transport for X on Linux!!!
                       -
Version 0.0.5    2.1.110   01-aug-98   Eduardo Marcelo Serrat
                       ([email protected])
                       Removed bugs on flow control
                       Removed bugs on incoming accessdata
                       order
                       -
Version 0.0.6    2.1.110   07-aug-98   Eduardo Marcelo Serrat
                       dn_recvmsg fixes

                    Patrick J. Caulfield
                       dn_bind fixes
*******************************************************************************/

#include <linux/module.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/timer.h>
#include <linux/string.h>
#include <linux/sockios.h>
#include <linux/net.h>
#include <linux/netdevice.h>
#include <linux/inet.h>
#include <linux/route.h>
#include <linux/netfilter.h>
#include <linux/seq_file.h>
#include <net/sock.h>
#include <net/tcp_states.h>
#include <net/flow.h>
#include <asm/ioctls.h>
#include <linux/capability.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/proc_fs.h>
#include <linux/stat.h>
#include <linux/init.h>
#include <linux/poll.h>
#include <net/net_namespace.h>
#include <net/neighbour.h>
#include <net/dst.h>
#include <net/fib_rules.h>
#include <net/dn.h>
#include <net/dn_nsp.h>
#include <net/dn_dev.h>
#include <net/dn_route.h>
#include <net/dn_fib.h>
#include <net/dn_neigh.h>

struct dn_sock {
    struct sock sk;
    struct dn_scp scp;
};

static void dn_keepalive(struct sock *sk);

#define DN_SK_HASH_SHIFT 8
#define DN_SK_HASH_SIZE (1 << DN_SK_HASH_SHIFT)
#define DN_SK_HASH_MASK (DN_SK_HASH_SIZE - 1)


static const struct proto_ops dn_proto_ops;
static DEFINE_RWLOCK(dn_hash_lock);
static struct hlist_head dn_sk_hash[DN_SK_HASH_SIZE];
static struct hlist_head dn_wild_sk;
static atomic_long_t decnet_memory_allocated;

static int __dn_setsockopt(struct socket *sock, int level, int optname, char __user *optval, unsigned int optlen, int flags);
static int __dn_getsockopt(struct socket *sock, int level, int optname, char __user *optval, int __user *optlen, int flags);

static struct hlist_head *dn_find_list(struct sock *sk)
{
    struct dn_scp *scp = DN_SK(sk);

    if (scp->addr.sdn_flags & SDF_WILD)
        return hlist_empty(&dn_wild_sk) ? &dn_wild_sk : NULL;

    return &dn_sk_hash[le16_to_cpu(scp->addrloc) & DN_SK_HASH_MASK];
}

/*
 * Valid ports are those greater than zero and not already in use.
 */
static int check_port(__le16 port)
{
    struct sock *sk;
    struct hlist_node *node;

    if (port == 0)
        return -1;

    sk_for_each(sk, node, &dn_sk_hash[le16_to_cpu(port) & DN_SK_HASH_MASK]) {
        struct dn_scp *scp = DN_SK(sk);
        if (scp->addrloc == port)
            return -1;
    }
    return 0;
}

static unsigned short port_alloc(struct sock *sk)
{
    struct dn_scp *scp = DN_SK(sk);
static unsigned short port = 0x2000;
    unsigned short i_port = port;

    while(check_port(cpu_to_le16(++port)) != 0) {
        if (port == i_port)
            return 0;
    }

    scp->addrloc = cpu_to_le16(port);

    return 1;
}

/*
 * Since this is only ever called from user
 * level, we don't need a write_lock() version
 * of this.
 */
static int dn_hash_sock(struct sock *sk)
{
    struct dn_scp *scp = DN_SK(sk);
    struct hlist_head *list;
    int rv = -EUSERS;

    BUG_ON(sk_hashed(sk));

    write_lock_bh(&dn_hash_lock);

    if (!scp->addrloc && !port_alloc(sk))
        goto out;

    rv = -EADDRINUSE;
    if ((list = dn_find_list(sk)) == NULL)
        goto out;

    sk_add_node(sk, list);
    rv = 0;
out:
    write_unlock_bh(&dn_hash_lock);
    return rv;
}

static void dn_unhash_sock(struct sock *sk)
{
    write_lock(&dn_hash_lock);
    sk_del_node_init(sk);
    write_unlock(&dn_hash_lock);
}

static void dn_unhash_sock_bh(struct sock *sk)
{
    write_lock_bh(&dn_hash_lock);
    sk_del_node_init(sk);
    write_unlock_bh(&dn_hash_lock);
}

static struct hlist_head *listen_hash(struct sockaddr_dn *addr)
{
    int i;
    unsigned int hash = addr->sdn_objnum;

    if (hash == 0) {
        hash = addr->sdn_objnamel;
        for(i = 0; i < le16_to_cpu(addr->sdn_objnamel); i++) {
            hash ^= addr->sdn_objname[i];
            hash ^= (hash << 3);
        }
    }

    return &dn_sk_hash[hash & DN_SK_HASH_MASK];
}

/*
 * Called to transform a socket from bound (i.e. with a local address)
 * into a listening socket (doesn't need a local port number) and rehashes
 * based upon the object name/number.
 */
static void dn_rehash_sock(struct sock *sk)
{
    struct hlist_head *list;
    struct dn_scp *scp = DN_SK(sk);

    if (scp->addr.sdn_flags & SDF_WILD)
        return;

    write_lock_bh(&dn_hash_lock);
    sk_del_node_init(sk);
    DN_SK(sk)->addrloc = 0;
    list = listen_hash(&DN_SK(sk)->addr);
    sk_add_node(sk, list);
    write_unlock_bh(&dn_hash_lock);
}

int dn_sockaddr2username(struct sockaddr_dn *sdn, unsigned char *buf, unsigned char type)
{
    int len = 2;

    *buf++ = type;

    switch (type) {
    case 0:
        *buf++ = sdn->sdn_objnum;
        break;
    case 1:
        *buf++ = 0;
        *buf++ = le16_to_cpu(sdn->sdn_objnamel);
        memcpy(buf, sdn->sdn_objname, le16_to_cpu(sdn->sdn_objnamel));
        len = 3 + le16_to_cpu(sdn->sdn_objnamel);
        break;
    case 2:
        memset(buf, 0, 5);
        buf += 5;
        *buf++ = le16_to_cpu(sdn->sdn_objnamel);
        memcpy(buf, sdn->sdn_objname, le16_to_cpu(sdn->sdn_objnamel));
        len = 7 + le16_to_cpu(sdn->sdn_objnamel);
        break;
    }

    return len;
}

/*
 * On reception of usernames, we handle types 1 and 0 for destination
 * addresses only. Types 2 and 4 are used for source addresses, but the
 * UIC, GIC are ignored and they are both treated the same way. Type 3
 * is never used as I've no idea what its purpose might be or what its
 * format is.
 */
int dn_username2sockaddr(unsigned char *data, int len, struct sockaddr_dn *sdn, unsigned char *fmt)
{
    unsigned char type;
    int size = len;
    int namel = 12;

    sdn->sdn_objnum = 0;
    sdn->sdn_objnamel = cpu_to_le16(0);
    memset(sdn->sdn_objname, 0, DN_MAXOBJL);

    if (len < 2)
        return -1;

    len -= 2;
    *fmt = *data++;
    type = *data++;

    switch (*fmt) {
    case 0:
        sdn->sdn_objnum = type;
        return 2;
    case 1:
        namel = 16;
        break;
    case 2:
        len  -= 4;
        data += 4;
        break;
    case 4:
        len  -= 8;
        data += 8;
        break;
    default:
        return -1;
    }

    len -= 1;

    if (len < 0)
        return -1;

    sdn->sdn_objnamel = cpu_to_le16(*data++);
    len -= le16_to_cpu(sdn->sdn_objnamel);

    if ((len < 0) || (le16_to_cpu(sdn->sdn_objnamel) > namel))
        return -1;

    memcpy(sdn->sdn_objname, data, le16_to_cpu(sdn->sdn_objnamel));

    return size - len;
}

struct sock *dn_sklist_find_listener(struct sockaddr_dn *addr)
{
    struct hlist_head *list = listen_hash(addr);
    struct hlist_node *node;
    struct sock *sk;

    read_lock(&dn_hash_lock);
    sk_for_each(sk, node, list) {
        struct dn_scp *scp = DN_SK(sk);
        if (sk->sk_state != TCP_LISTEN)
            continue;
        if (scp->addr.sdn_objnum) {
            if (scp->addr.sdn_objnum != addr->sdn_objnum)
                continue;
        } else {
            if (addr->sdn_objnum)
                continue;
            if (scp->addr.sdn_objnamel != addr->sdn_objnamel)
                continue;
            if (memcmp(scp->addr.sdn_objname, addr->sdn_objname, le16_to_cpu(addr->sdn_objnamel)) != 0)
                continue;
        }
        sock_hold(sk);
        read_unlock(&dn_hash_lock);
        return sk;
    }

    sk = sk_head(&dn_wild_sk);
    if (sk) {
        if (sk->sk_state == TCP_LISTEN)
            sock_hold(sk);
        else
            sk = NULL;
    }

    read_unlock(&dn_hash_lock);
    return sk;
}

struct sock *dn_find_by_skb(struct sk_buff *skb)
{
    struct dn_skb_cb *cb = DN_SKB_CB(skb);
    struct sock *sk;
    struct hlist_node *node;
    struct dn_scp *scp;

    read_lock(&dn_hash_lock);
    sk_for_each(sk, node, &dn_sk_hash[le16_to_cpu(cb->dst_port) & DN_SK_HASH_MASK]) {
        scp = DN_SK(sk);
        if (cb->src != dn_saddr2dn(&scp->peer))
            continue;
        if (cb->dst_port != scp->addrloc)
            continue;
        if (scp->addrrem && (cb->src_port != scp->addrrem))
            continue;
        sock_hold(sk);
        goto found;
    }
    sk = NULL;
found:
    read_unlock(&dn_hash_lock);
    return sk;
}



static void dn_destruct(struct sock *sk)
{
    struct dn_scp *scp = DN_SK(sk);

    skb_queue_purge(&scp->data_xmit_queue);
    skb_queue_purge(&scp->other_xmit_queue);
    skb_queue_purge(&scp->other_receive_queue);

    dst_release(rcu_dereference_check(sk->sk_dst_cache, 1));
}

static int dn_memory_pressure;

static void dn_enter_memory_pressure(struct sock *sk)
{
    if (!dn_memory_pressure) {
        dn_memory_pressure = 1;
    }
}

static struct proto dn_proto = {
    .name           = "NSP",
    .owner          = THIS_MODULE,
    .enter_memory_pressure  = dn_enter_memory_pressure,
    .memory_pressure    = &dn_memory_pressure,
    .memory_allocated   = &decnet_memory_allocated,
    .sysctl_mem     = sysctl_decnet_mem,
    .sysctl_wmem        = sysctl_decnet_wmem,
    .sysctl_rmem        = sysctl_decnet_rmem,
    .max_header     = DN_MAX_NSP_DATA_HEADER + 64,
    .obj_size       = sizeof(struct dn_sock),
};

static struct sock *dn_alloc_sock(struct net *net, struct socket *sock, gfp_t gfp)
{
    struct dn_scp *scp;
    struct sock *sk = sk_alloc(net, PF_DECnet, gfp, &dn_proto);

    if  (!sk)
        goto out;

    if (sock)
        sock->ops = &dn_proto_ops;
    sock_init_data(sock, sk);

    sk->sk_backlog_rcv = dn_nsp_backlog_rcv;
    sk->sk_destruct    = dn_destruct;
    sk->sk_no_check    = 1;
    sk->sk_family      = PF_DECnet;
    sk->sk_protocol    = 0;
    sk->sk_allocation  = gfp;
    sk->sk_sndbuf      = sysctl_decnet_wmem[1];
    sk->sk_rcvbuf      = sysctl_decnet_rmem[1];

    /* Initialization of DECnet Session Control Port        */
    scp = DN_SK(sk);
    scp->state  = DN_O;     /* Open         */
    scp->numdat = 1;        /* Next data seg to tx  */
    scp->numoth = 1;        /* Next oth data to tx  */
    scp->ackxmt_dat = 0;        /* Last data seg ack'ed */
    scp->ackxmt_oth = 0;        /* Last oth data ack'ed */
    scp->ackrcv_dat = 0;        /* Highest data ack recv*/
    scp->ackrcv_oth = 0;        /* Last oth data ack rec*/
    scp->flowrem_sw = DN_SEND;
    scp->flowloc_sw = DN_SEND;
    scp->flowrem_dat = 0;
    scp->flowrem_oth = 1;
    scp->flowloc_dat = 0;
    scp->flowloc_oth = 1;
    scp->services_rem = 0;
    scp->services_loc = 1 | NSP_FC_NONE;
    scp->info_rem = 0;
    scp->info_loc = 0x03; /* NSP version 4.1 */
    scp->segsize_rem = 230 - DN_MAX_NSP_DATA_HEADER; /* Default: Updated by remote segsize */
    scp->nonagle = 0;
    scp->multi_ireq = 1;
    scp->accept_mode = ACC_IMMED;
    scp->addr.sdn_family    = AF_DECnet;
    scp->peer.sdn_family    = AF_DECnet;
    scp->accessdata.acc_accl = 5;
    memcpy(scp->accessdata.acc_acc, "LINUX", 5);

    scp->max_window   = NSP_MAX_WINDOW;
    scp->snd_window   = NSP_MIN_WINDOW;
    scp->nsp_srtt     = NSP_INITIAL_SRTT;
    scp->nsp_rttvar   = NSP_INITIAL_RTTVAR;
    scp->nsp_rxtshift = 0;

    skb_queue_head_init(&scp->data_xmit_queue);
    skb_queue_head_init(&scp->other_xmit_queue);
    skb_queue_head_init(&scp->other_receive_queue);

    scp->persist = 0;
    scp->persist_fxn = NULL;
    scp->keepalive = 10 * HZ;
    scp->keepalive_fxn = dn_keepalive;

    init_timer(&scp->delack_timer);
    scp->delack_pending = 0;
    scp->delack_fxn = dn_nsp_delayed_ack;

    dn_start_slow_timer(sk);
out:
    return sk;
}

/*
 * Keepalive timer.
 * FIXME: Should respond to SO_KEEPALIVE etc.
 */
static void dn_keepalive(struct sock *sk)
{
    struct dn_scp *scp = DN_SK(sk);

    /*
     * By checking the other_data transmit queue is empty
     * we are double checking that we are not sending too
     * many of these keepalive frames.
     */
    if (skb_queue_empty(&scp->other_xmit_queue))
        dn_nsp_send_link(sk, DN_NOCHANGE, 0);
}


/*
 * Timer for shutdown/destroyed sockets.
 * When socket is dead & no packets have been sent for a
 * certain amount of time, they are removed by this
 * routine. Also takes care of sending out DI & DC
 * frames at correct times.
 */
int dn_destroy_timer(struct sock *sk)
{
    struct dn_scp *scp = DN_SK(sk);

    scp->persist = dn_nsp_persist(sk);

    switch (scp->state) {
    case DN_DI:
        dn_nsp_send_disc(sk, NSP_DISCINIT, 0, GFP_ATOMIC);
        if (scp->nsp_rxtshift >= decnet_di_count)
            scp->state = DN_CN;
        return 0;

    case DN_DR:
        dn_nsp_send_disc(sk, NSP_DISCINIT, 0, GFP_ATOMIC);
        if (scp->nsp_rxtshift >= decnet_dr_count)
            scp->state = DN_DRC;
        return 0;

    case DN_DN:
        if (scp->nsp_rxtshift < decnet_dn_count) {
            /* printk(KERN_DEBUG "dn_destroy_timer: DN\n"); */
            dn_nsp_send_disc(sk, NSP_DISCCONF, NSP_REASON_DC,
                     GFP_ATOMIC);
            return 0;
        }
    }

    scp->persist = (HZ * decnet_time_wait);

    if (sk->sk_socket)
        return 0;

    if ((jiffies - scp->stamp) >= (HZ * decnet_time_wait)) {
        dn_unhash_sock(sk);
        sock_put(sk);
        return 1;
    }

    return 0;
}

static void dn_destroy_sock(struct sock *sk)
{
    struct dn_scp *scp = DN_SK(sk);

    scp->nsp_rxtshift = 0; /* reset back off */

    if (sk->sk_socket) {
        if (sk->sk_socket->state != SS_UNCONNECTED)
            sk->sk_socket->state = SS_DISCONNECTING;
    }

    sk->sk_state = TCP_CLOSE;

    switch (scp->state) {
    case DN_DN:
        dn_nsp_send_disc(sk, NSP_DISCCONF, NSP_REASON_DC,
                 sk->sk_allocation);
        scp->persist_fxn = dn_destroy_timer;
        scp->persist = dn_nsp_persist(sk);
        break;
    case DN_CR:
        scp->state = DN_DR;
        goto disc_reject;
    case DN_RUN:
        scp->state = DN_DI;
    case DN_DI:
    case DN_DR:
disc_reject:
        dn_nsp_send_disc(sk, NSP_DISCINIT, 0, sk->sk_allocation);
    case DN_NC:
    case DN_NR:
    case DN_RJ:
    case DN_DIC:
    case DN_CN:
    case DN_DRC:
    case DN_CI:
    case DN_CD:
        scp->persist_fxn = dn_destroy_timer;
        scp->persist = dn_nsp_persist(sk);
        break;
    default:
        printk(KERN_DEBUG "DECnet: dn_destroy_sock passed socket in invalid state\n");
    case DN_O:
        dn_stop_slow_timer(sk);

        dn_unhash_sock_bh(sk);
        sock_put(sk);

        break;
    }
}

char *dn_addr2asc(__u16 addr, char *buf)
{
    unsigned short node, area;

    node = addr & 0x03ff;
    area = addr >> 10;
    sprintf(buf, "%hd.%hd", area, node);

    return buf;
}



static int dn_create(struct net *net, struct socket *sock, int protocol,
             int kern)
{
    struct sock *sk;

    if (!net_eq(net, &init_net))
        return -EAFNOSUPPORT;

    switch (sock->type) {
    case SOCK_SEQPACKET:
        if (protocol != DNPROTO_NSP)
            return -EPROTONOSUPPORT;
        break;
    case SOCK_STREAM:
        break;
    default:
        return -ESOCKTNOSUPPORT;
    }


    if ((sk = dn_alloc_sock(net, sock, GFP_KERNEL)) == NULL)
        return -ENOBUFS;

    sk->sk_protocol = protocol;

    return 0;
}


static int
dn_release(struct socket *sock)
{
    struct sock *sk = sock->sk;

    if (sk) {
        sock_orphan(sk);
        sock_hold(sk);
        lock_sock(sk);
        dn_destroy_sock(sk);
        release_sock(sk);
        sock_put(sk);
    }

    return 0;
}

static int dn_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
{
    struct sock *sk = sock->sk;
    struct dn_scp *scp = DN_SK(sk);
    struct sockaddr_dn *saddr = (struct sockaddr_dn *)uaddr;
    struct net_device *dev, *ldev;
    int rv;

    if (addr_len != sizeof(struct sockaddr_dn))
        return -EINVAL;

    if (saddr->sdn_family != AF_DECnet)
        return -EINVAL;

    if (le16_to_cpu(saddr->sdn_nodeaddrl) && (le16_to_cpu(saddr->sdn_nodeaddrl) != 2))
        return -EINVAL;

    if (le16_to_cpu(saddr->sdn_objnamel) > DN_MAXOBJL)
        return -EINVAL;

    if (saddr->sdn_flags & ~SDF_WILD)
        return -EINVAL;

    if (!capable(CAP_NET_BIND_SERVICE) && (saddr->sdn_objnum ||
        (saddr->sdn_flags & SDF_WILD)))
        return -EACCES;

    if (!(saddr->sdn_flags & SDF_WILD)) {
        if (le16_to_cpu(saddr->sdn_nodeaddrl)) {
            rcu_read_lock();
            ldev = NULL;
            for_each_netdev_rcu(&init_net, dev) {
                if (!dev->dn_ptr)
                    continue;
                if (dn_dev_islocal(dev, dn_saddr2dn(saddr))) {
                    ldev = dev;
                    break;
                }
            }
            rcu_read_unlock();
            if (ldev == NULL)
                return -EADDRNOTAVAIL;
        }
    }

    rv = -EINVAL;
    lock_sock(sk);
    if (sock_flag(sk, SOCK_ZAPPED)) {
        memcpy(&scp->addr, saddr, addr_len);
        sock_reset_flag(sk, SOCK_ZAPPED);

        rv = dn_hash_sock(sk);
        if (rv)
            sock_set_flag(sk, SOCK_ZAPPED);
    }
    release_sock(sk);

    return rv;
}


static int dn_auto_bind(struct socket *sock)
{
    struct sock *sk = sock->sk;
    struct dn_scp *scp = DN_SK(sk);
    int rv;

    sock_reset_flag(sk, SOCK_ZAPPED);

    scp->addr.sdn_flags  = 0;
    scp->addr.sdn_objnum = 0;

    /*
     * This stuff is to keep compatibility with Eduardo's
     * patch. I hope I can dispense with it shortly...
     */
    if ((scp->accessdata.acc_accl != 0) &&
        (scp->accessdata.acc_accl <= 12)) {

        scp->addr.sdn_objnamel = cpu_to_le16(scp->accessdata.acc_accl);
        memcpy(scp->addr.sdn_objname, scp->accessdata.acc_acc, le16_to_cpu(scp->addr.sdn_objnamel));

        scp->accessdata.acc_accl = 0;
        memset(scp->accessdata.acc_acc, 0, 40);
    }
    /* End of compatibility stuff */

    scp->addr.sdn_add.a_len = cpu_to_le16(2);
    rv = dn_dev_bind_default((__le16 *)scp->addr.sdn_add.a_addr);
    if (rv == 0) {
        rv = dn_hash_sock(sk);
        if (rv)
            sock_set_flag(sk, SOCK_ZAPPED);
    }

    return rv;
}

static int dn_confirm_accept(struct sock *sk, long *timeo, gfp_t allocation)
{
    struct dn_scp *scp = DN_SK(sk);
    DEFINE_WAIT(wait);
    int err;

    if (scp->state != DN_CR)
        return -EINVAL;

    scp->state = DN_CC;
    scp->segsize_loc = dst_metric_advmss(__sk_dst_get(sk));
    dn_send_conn_conf(sk, allocation);

    prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
    for(;;) {
        release_sock(sk);
        if (scp->state == DN_CC)
            *timeo = schedule_timeout(*timeo);
        lock_sock(sk);
        err = 0;
        if (scp->state == DN_RUN)
            break;
        err = sock_error(sk);
        if (err)
            break;
        err = sock_intr_errno(*timeo);
        if (signal_pending(current))
            break;
        err = -EAGAIN;
        if (!*timeo)
            break;
        prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
    }
    finish_wait(sk_sleep(sk), &wait);
    if (err == 0) {
        sk->sk_socket->state = SS_CONNECTED;
    } else if (scp->state != DN_CC) {
        sk->sk_socket->state = SS_UNCONNECTED;
    }
    return err;
}

static int dn_wait_run(struct sock *sk, long *timeo)
{
    struct dn_scp *scp = DN_SK(sk);
    DEFINE_WAIT(wait);
    int err = 0;

    if (scp->state == DN_RUN)
        goto out;

    if (!*timeo)
        return -EALREADY;

    prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
    for(;;) {
        release_sock(sk);
        if (scp->state == DN_CI || scp->state == DN_CC)
            *timeo = schedule_timeout(*timeo);
        lock_sock(sk);
        err = 0;
        if (scp->state == DN_RUN)
            break;
        err = sock_error(sk);
        if (err)
            break;
        err = sock_intr_errno(*timeo);
        if (signal_pending(current))
            break;
        err = -ETIMEDOUT;
        if (!*timeo)
            break;
        prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
    }
    finish_wait(sk_sleep(sk), &wait);
out:
    if (err == 0) {
        sk->sk_socket->state = SS_CONNECTED;
    } else if (scp->state != DN_CI && scp->state != DN_CC) {
        sk->sk_socket->state = SS_UNCONNECTED;
    }
    return err;
}

static int __dn_connect(struct sock *sk, struct sockaddr_dn *addr, int addrlen, long *timeo, int flags)
{
    struct socket *sock = sk->sk_socket;
    struct dn_scp *scp = DN_SK(sk);
    int err = -EISCONN;
    struct flowidn fld;

    if (sock->state == SS_CONNECTED)
        goto out;

    if (sock->state == SS_CONNECTING) {
        err = 0;
        if (scp->state == DN_RUN) {
            sock->state = SS_CONNECTED;
            goto out;
        }
        err = -ECONNREFUSED;
        if (scp->state != DN_CI && scp->state != DN_CC) {
            sock->state = SS_UNCONNECTED;
            goto out;
        }
        return dn_wait_run(sk, timeo);
    }

    err = -EINVAL;
    if (scp->state != DN_O)
        goto out;

    if (addr == NULL || addrlen != sizeof(struct sockaddr_dn))
        goto out;
    if (addr->sdn_family != AF_DECnet)
        goto out;
    if (addr->sdn_flags & SDF_WILD)
        goto out;

    if (sock_flag(sk, SOCK_ZAPPED)) {
        err = dn_auto_bind(sk->sk_socket);
        if (err)
            goto out;
    }

    memcpy(&scp->peer, addr, sizeof(struct sockaddr_dn));

    err = -EHOSTUNREACH;
    memset(&fld, 0, sizeof(fld));
    fld.flowidn_oif = sk->sk_bound_dev_if;
    fld.daddr = dn_saddr2dn(&scp->peer);
    fld.saddr = dn_saddr2dn(&scp->addr);
    dn_sk_ports_copy(&fld, scp);
    fld.flowidn_proto = DNPROTO_NSP;
    if (dn_route_output_sock(&sk->sk_dst_cache, &fld, sk, flags) < 0)
        goto out;
    sk->sk_route_caps = sk->sk_dst_cache->dev->features;
    sock->state = SS_CONNECTING;
    scp->state = DN_CI;
    scp->segsize_loc = dst_metric_advmss(sk->sk_dst_cache);

    dn_nsp_send_conninit(sk, NSP_CI);
    err = -EINPROGRESS;
    if (*timeo) {
        err = dn_wait_run(sk, timeo);
    }
out:
    return err;
}

static int dn_connect(struct socket *sock, struct sockaddr *uaddr, int addrlen, int flags)
{
    struct sockaddr_dn *addr = (struct sockaddr_dn *)uaddr;
    struct sock *sk = sock->sk;
    int err;
    long timeo = sock_sndtimeo(sk, flags & O_NONBLOCK);

    lock_sock(sk);
    err = __dn_connect(sk, addr, addrlen, &timeo, 0);
    release_sock(sk);

    return err;
}

static inline int dn_check_state(struct sock *sk, struct sockaddr_dn *addr, int addrlen, long *timeo, int flags)
{
    struct dn_scp *scp = DN_SK(sk);

    switch (scp->state) {
    case DN_RUN:
        return 0;
    case DN_CR:
        return dn_confirm_accept(sk, timeo, sk->sk_allocation);
    case DN_CI:
    case DN_CC:
        return dn_wait_run(sk, timeo);
    case DN_O:
        return __dn_connect(sk, addr, addrlen, timeo, flags);
    }

    return -EINVAL;
}


static void dn_access_copy(struct sk_buff *skb, struct accessdata_dn *acc)
{
    unsigned char *ptr = skb->data;

    acc->acc_userl = *ptr++;
    memcpy(&acc->acc_user, ptr, acc->acc_userl);
    ptr += acc->acc_userl;

    acc->acc_passl = *ptr++;
    memcpy(&acc->acc_pass, ptr, acc->acc_passl);
    ptr += acc->acc_passl;

    acc->acc_accl = *ptr++;
    memcpy(&acc->acc_acc, ptr, acc->acc_accl);

    skb_pull(skb, acc->acc_accl + acc->acc_passl + acc->acc_userl + 3);

}

static void dn_user_copy(struct sk_buff *skb, struct optdata_dn *opt)
{
    unsigned char *ptr = skb->data;
    u16 len = *ptr++; /* yes, it's 8bit on the wire */

    BUG_ON(len > 16); /* we've checked the contents earlier */
    opt->opt_optl   = cpu_to_le16(len);
    opt->opt_status = 0;
    memcpy(opt->opt_data, ptr, len);
    skb_pull(skb, len + 1);
}

static struct sk_buff *dn_wait_for_connect(struct sock *sk, long *timeo)
{
    DEFINE_WAIT(wait);
    struct sk_buff *skb = NULL;
    int err = 0;

    prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
    for(;;) {
        release_sock(sk);
        skb = skb_dequeue(&sk->sk_receive_queue);
        if (skb == NULL) {
            *timeo = schedule_timeout(*timeo);
            skb = skb_dequeue(&sk->sk_receive_queue);
        }
        lock_sock(sk);
        if (skb != NULL)
            break;
        err = -EINVAL;
        if (sk->sk_state != TCP_LISTEN)
            break;
        err = sock_intr_errno(*timeo);
        if (signal_pending(current))
            break;
        err = -EAGAIN;
        if (!*timeo)
            break;
        prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
    }
    finish_wait(sk_sleep(sk), &wait);

    return skb == NULL ? ERR_PTR(err) : skb;
}

static int dn_accept(struct socket *sock, struct socket *newsock, int flags)
{
    struct sock *sk = sock->sk, *newsk;
    struct sk_buff *skb = NULL;
    struct dn_skb_cb *cb;
    unsigned char menuver;
    int err = 0;
    unsigned char type;
    long timeo = sock_rcvtimeo(sk, flags & O_NONBLOCK);
    struct dst_entry *dst;

    lock_sock(sk);

    if (sk->sk_state != TCP_LISTEN || DN_SK(sk)->state != DN_O) {
        release_sock(sk);
        return -EINVAL;
    }

    skb = skb_dequeue(&sk->sk_receive_queue);
    if (skb == NULL) {
        skb = dn_wait_for_connect(sk, &timeo);
        if (IS_ERR(skb)) {
            release_sock(sk);
            return PTR_ERR(skb);
        }
    }

    cb = DN_SKB_CB(skb);
    sk->sk_ack_backlog--;
    newsk = dn_alloc_sock(sock_net(sk), newsock, sk->sk_allocation);
    if (newsk == NULL) {
        release_sock(sk);
        kfree_skb(skb);
        return -ENOBUFS;
    }
    release_sock(sk);

    dst = skb_dst(skb);
    sk_dst_set(newsk, dst);
    skb_dst_set(skb, NULL);

    DN_SK(newsk)->state        = DN_CR;
    DN_SK(newsk)->addrrem      = cb->src_port;
    DN_SK(newsk)->services_rem = cb->services;
    DN_SK(newsk)->info_rem     = cb->info;
    DN_SK(newsk)->segsize_rem  = cb->segsize;
    DN_SK(newsk)->accept_mode  = DN_SK(sk)->accept_mode;

    if (DN_SK(newsk)->segsize_rem < 230)
        DN_SK(newsk)->segsize_rem = 230;

    if ((DN_SK(newsk)->services_rem & NSP_FC_MASK) == NSP_FC_NONE)
        DN_SK(newsk)->max_window = decnet_no_fc_max_cwnd;

    newsk->sk_state  = TCP_LISTEN;
    memcpy(&(DN_SK(newsk)->addr), &(DN_SK(sk)->addr), sizeof(struct sockaddr_dn));

    /*
     * If we are listening on a wild socket, we don't want
     * the newly created socket on the wrong hash queue.
     */
    DN_SK(newsk)->addr.sdn_flags &= ~SDF_WILD;

    skb_pull(skb, dn_username2sockaddr(skb->data, skb->len, &(DN_SK(newsk)->addr), &type));
    skb_pull(skb, dn_username2sockaddr(skb->data, skb->len, &(DN_SK(newsk)->peer), &type));
    *(__le16 *)(DN_SK(newsk)->peer.sdn_add.a_addr) = cb->src;
    *(__le16 *)(DN_SK(newsk)->addr.sdn_add.a_addr) = cb->dst;

    menuver = *skb->data;
    skb_pull(skb, 1);

    if (menuver & DN_MENUVER_ACC)
        dn_access_copy(skb, &(DN_SK(newsk)->accessdata));

    if (menuver & DN_MENUVER_USR)
        dn_user_copy(skb, &(DN_SK(newsk)->conndata_in));

    if (menuver & DN_MENUVER_PRX)
        DN_SK(newsk)->peer.sdn_flags |= SDF_PROXY;

    if (menuver & DN_MENUVER_UIC)
        DN_SK(newsk)->peer.sdn_flags |= SDF_UICPROXY;

    kfree_skb(skb);

    memcpy(&(DN_SK(newsk)->conndata_out), &(DN_SK(sk)->conndata_out),
        sizeof(struct optdata_dn));
    memcpy(&(DN_SK(newsk)->discdata_out), &(DN_SK(sk)->discdata_out),
        sizeof(struct optdata_dn));

    lock_sock(newsk);
    err = dn_hash_sock(newsk);
    if (err == 0) {
        sock_reset_flag(newsk, SOCK_ZAPPED);
        dn_send_conn_ack(newsk);

        /*
         * Here we use sk->sk_allocation since although the conn conf is
         * for the newsk, the context is the old socket.
         */
        if (DN_SK(newsk)->accept_mode == ACC_IMMED)
            err = dn_confirm_accept(newsk, &timeo,
                        sk->sk_allocation);
    }
    release_sock(newsk);
    return err;
}


static int dn_getname(struct socket *sock, struct sockaddr *uaddr,int *uaddr_len,int peer)
{
    struct sockaddr_dn *sa = (struct sockaddr_dn *)uaddr;
    struct sock *sk = sock->sk;
    struct dn_scp *scp = DN_SK(sk);

    *uaddr_len = sizeof(struct sockaddr_dn);

    lock_sock(sk);

    if (peer) {
        if ((sock->state != SS_CONNECTED &&
             sock->state != SS_CONNECTING) &&
            scp->accept_mode == ACC_IMMED) {
            release_sock(sk);
            return -ENOTCONN;
        }

        memcpy(sa, &scp->peer, sizeof(struct sockaddr_dn));
    } else {
        memcpy(sa, &scp->addr, sizeof(struct sockaddr_dn));
    }

    release_sock(sk);

    return 0;
}


static unsigned int dn_poll(struct file *file, struct socket *sock, poll_table  *wait)
{
    struct sock *sk = sock->sk;
    struct dn_scp *scp = DN_SK(sk);
    int mask = datagram_poll(file, sock, wait);

    if (!skb_queue_empty(&scp->other_receive_queue))
        mask |= POLLRDBAND;

    return mask;
}

static int dn_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
{
    struct sock *sk = sock->sk;
    struct dn_scp *scp = DN_SK(sk);
    int err = -EOPNOTSUPP;
    long amount = 0;
    struct sk_buff *skb;
    int val;

    switch(cmd)
    {
    case SIOCGIFADDR:
    case SIOCSIFADDR:
        return dn_dev_ioctl(cmd, (void __user *)arg);

    case SIOCATMARK:
        lock_sock(sk);
        val = !skb_queue_empty(&scp->other_receive_queue);
        if (scp->state != DN_RUN)
            val = -ENOTCONN;
        release_sock(sk);
        return val;

    case TIOCOUTQ:
        amount = sk->sk_sndbuf - sk_wmem_alloc_get(sk);
        if (amount < 0)
            amount = 0;
        err = put_user(amount, (int __user *)arg);
        break;

    case TIOCINQ:
        lock_sock(sk);
        skb = skb_peek(&scp->other_receive_queue);
        if (skb) {
            amount = skb->len;
        } else {
            skb_queue_walk(&sk->sk_receive_queue, skb)
                amount += skb->len;
        }
        release_sock(sk);
        err = put_user(amount, (int __user *)arg);
        break;

    default:
        err = -ENOIOCTLCMD;
        break;
    }

    return err;
}

static int dn_listen(struct socket *sock, int backlog)
{
    struct sock *sk = sock->sk;
    int err = -EINVAL;

    lock_sock(sk);

    if (sock_flag(sk, SOCK_ZAPPED))
        goto out;

    if ((DN_SK(sk)->state != DN_O) || (sk->sk_state == TCP_LISTEN))
        goto out;

    sk->sk_max_ack_backlog = backlog;
    sk->sk_ack_backlog     = 0;
    sk->sk_state           = TCP_LISTEN;
    err                 = 0;
    dn_rehash_sock(sk);

out:
    release_sock(sk);

    return err;
}


static int dn_shutdown(struct socket *sock, int how)
{
    struct sock *sk = sock->sk;
    struct dn_scp *scp = DN_SK(sk);
    int err = -ENOTCONN;

    lock_sock(sk);

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

    err = 0;
    if (sock->state == SS_DISCONNECTING)
        goto out;

    err = -EINVAL;
    if (scp->state == DN_O)
        goto out;

    if (how != SHUT_RDWR)
        goto out;

    sk->sk_shutdown = SHUTDOWN_MASK;
    dn_destroy_sock(sk);
    err = 0;

out:
    release_sock(sk);

    return err;
}

static int dn_setsockopt(struct socket *sock, int level, int optname, char __user *optval, unsigned int optlen)
{
    struct sock *sk = sock->sk;
    int err;

    lock_sock(sk);
    err = __dn_setsockopt(sock, level, optname, optval, optlen, 0);
    release_sock(sk);

    return err;
}

static int __dn_setsockopt(struct socket *sock, int level,int optname, char __user *optval, unsigned int optlen, int flags)
{
    struct  sock *sk = sock->sk;
    struct dn_scp *scp = DN_SK(sk);
    long timeo;
    union {
        struct optdata_dn opt;
        struct accessdata_dn acc;
        int mode;
        unsigned long win;
        int val;
        unsigned char services;
        unsigned char info;
    } u;
    int err;

    if (optlen && !optval)
        return -EINVAL;

    if (optlen > sizeof(u))
        return -EINVAL;

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

    switch (optname) {
    case DSO_CONDATA:
        if (sock->state == SS_CONNECTED)
            return -EISCONN;
        if ((scp->state != DN_O) && (scp->state != DN_CR))
            return -EINVAL;

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

        if (le16_to_cpu(u.opt.opt_optl) > 16)
            return -EINVAL;

        memcpy(&scp->conndata_out, &u.opt, optlen);
        break;

    case DSO_DISDATA:
        if (sock->state != SS_CONNECTED &&
            scp->accept_mode == ACC_IMMED)
            return -ENOTCONN;

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

        if (le16_to_cpu(u.opt.opt_optl) > 16)
            return -EINVAL;

        memcpy(&scp->discdata_out, &u.opt, optlen);
        break;

    case DSO_CONACCESS:
        if (sock->state == SS_CONNECTED)
            return -EISCONN;
        if (scp->state != DN_O)
            return -EINVAL;

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

        if ((u.acc.acc_accl > DN_MAXACCL) ||
            (u.acc.acc_passl > DN_MAXACCL) ||
            (u.acc.acc_userl > DN_MAXACCL))
            return -EINVAL;

        memcpy(&scp->accessdata, &u.acc, optlen);
        break;

    case DSO_ACCEPTMODE:
        if (sock->state == SS_CONNECTED)
            return -EISCONN;
        if (scp->state != DN_O)
            return -EINVAL;

        if (optlen != sizeof(int))
            return -EINVAL;

        if ((u.mode != ACC_IMMED) && (u.mode != ACC_DEFER))
            return -EINVAL;

        scp->accept_mode = (unsigned char)u.mode;
        break;

    case DSO_CONACCEPT:
        if (scp->state != DN_CR)
            return -EINVAL;
        timeo = sock_rcvtimeo(sk, 0);
        err = dn_confirm_accept(sk, &timeo, sk->sk_allocation);
        return err;

    case DSO_CONREJECT:
        if (scp->state != DN_CR)
            return -EINVAL;

        scp->state = DN_DR;
        sk->sk_shutdown = SHUTDOWN_MASK;
        dn_nsp_send_disc(sk, 0x38, 0, sk->sk_allocation);
        break;

    default:
#ifdef CONFIG_NETFILTER
        return nf_setsockopt(sk, PF_DECnet, optname, optval, optlen);
#endif
    case DSO_LINKINFO:
    case DSO_STREAM:
    case DSO_SEQPACKET:
        return -ENOPROTOOPT;

    case DSO_MAXWINDOW:
        if (optlen != sizeof(unsigned long))
            return -EINVAL;
        if (u.win > NSP_MAX_WINDOW)
            u.win = NSP_MAX_WINDOW;
        if (u.win == 0)
            return -EINVAL;
        scp->max_window = u.win;
        if (scp->snd_window > u.win)
            scp->snd_window = u.win;
        break;

    case DSO_NODELAY:
        if (optlen != sizeof(int))
            return -EINVAL;
        if (scp->nonagle == 2)
            return -EINVAL;
        scp->nonagle = (u.val == 0) ? 0 : 1;
        /* if (scp->nonagle == 1) { Push pending frames } */
        break;

    case DSO_CORK:
        if (optlen != sizeof(int))
            return -EINVAL;
        if (scp->nonagle == 1)
            return -EINVAL;
        scp->nonagle = (u.val == 0) ? 0 : 2;
        /* if (scp->nonagle == 0) { Push pending frames } */
        break;

    case DSO_SERVICES:
        if (optlen != sizeof(unsigned char))
            return -EINVAL;
        if ((u.services & ~NSP_FC_MASK) != 0x01)
            return -EINVAL;
        if ((u.services & NSP_FC_MASK) == NSP_FC_MASK)
            return -EINVAL;
        scp->services_loc = u.services;
        break;

    case DSO_INFO:
        if (optlen != sizeof(unsigned char))
            return -EINVAL;
        if (u.info & 0xfc)
            return -EINVAL;
        scp->info_loc = u.info;
        break;
    }

    return 0;
}

static int dn_getsockopt(struct socket *sock, int level, int optname, char __user *optval, int __user *optlen)
{
    struct sock *sk = sock->sk;
    int err;

    lock_sock(sk);
    err = __dn_getsockopt(sock, level, optname, optval, optlen, 0);
    release_sock(sk);

    return err;
}

static int __dn_getsockopt(struct socket *sock, int level,int optname, char __user *optval,int __user *optlen, int flags)
{
    struct  sock *sk = sock->sk;
    struct dn_scp *scp = DN_SK(sk);
    struct linkinfo_dn link;
    unsigned int r_len;
    void *r_data = NULL;
    unsigned int val;

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

    switch (optname) {
    case DSO_CONDATA:
        if (r_len > sizeof(struct optdata_dn))
            r_len = sizeof(struct optdata_dn);
        r_data = &scp->conndata_in;
        break;

    case DSO_DISDATA:
        if (r_len > sizeof(struct optdata_dn))
            r_len = sizeof(struct optdata_dn);
        r_data = &scp->discdata_in;
        break;

    case DSO_CONACCESS:
        if (r_len > sizeof(struct accessdata_dn))
            r_len = sizeof(struct accessdata_dn);
        r_data = &scp->accessdata;
        break;

    case DSO_ACCEPTMODE:
        if (r_len > sizeof(unsigned char))
            r_len = sizeof(unsigned char);
        r_data = &scp->accept_mode;
        break;

    case DSO_LINKINFO:
        if (r_len > sizeof(struct linkinfo_dn))
            r_len = sizeof(struct linkinfo_dn);

        memset(&link, 0, sizeof(link));

        switch (sock->state) {
        case SS_CONNECTING:
            link.idn_linkstate = LL_CONNECTING;
            break;
        case SS_DISCONNECTING:
            link.idn_linkstate = LL_DISCONNECTING;
            break;
        case SS_CONNECTED:
            link.idn_linkstate = LL_RUNNING;
            break;
        default:
            link.idn_linkstate = LL_INACTIVE;
        }

        link.idn_segsize = scp->segsize_rem;
        r_data = &link;
        break;

    default:
#ifdef CONFIG_NETFILTER
    {
        int ret, len;

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

        ret = nf_getsockopt(sk, PF_DECnet, optname, optval, &len);
        if (ret >= 0)
            ret = put_user(len, optlen);
        return ret;
    }
#endif
    case DSO_STREAM:
    case DSO_SEQPACKET:
    case DSO_CONACCEPT:
    case DSO_CONREJECT:
        return -ENOPROTOOPT;

    case DSO_MAXWINDOW:
        if (r_len > sizeof(unsigned long))
            r_len = sizeof(unsigned long);
        r_data = &scp->max_window;
        break;

    case DSO_NODELAY:
        if (r_len > sizeof(int))
            r_len = sizeof(int);
        val = (scp->nonagle == 1);
        r_data = &val;
        break;

    case DSO_CORK:
        if (r_len > sizeof(int))
            r_len = sizeof(int);
        val = (scp->nonagle == 2);
        r_data = &val;
        break;

    case DSO_SERVICES:
        if (r_len > sizeof(unsigned char))
            r_len = sizeof(unsigned char);
        r_data = &scp->services_rem;
        break;

    case DSO_INFO:
        if (r_len > sizeof(unsigned char))
            r_len = sizeof(unsigned char);
        r_data = &scp->info_rem;
        break;
    }

    if (r_data) {
        if (copy_to_user(optval, r_data, r_len))
            return -EFAULT;
        if (put_user(r_len, optlen))
            return -EFAULT;
    }

    return 0;
}


static int dn_data_ready(struct sock *sk, struct sk_buff_head *q, int flags, int target)
{
    struct sk_buff *skb;
    int len = 0;

    if (flags & MSG_OOB)
        return !skb_queue_empty(q) ? 1 : 0;

    skb_queue_walk(q, skb) {
        struct dn_skb_cb *cb = DN_SKB_CB(skb);
        len += skb->len;

        if (cb->nsp_flags & 0x40) {
            /* SOCK_SEQPACKET reads to EOM */
            if (sk->sk_type == SOCK_SEQPACKET)
                return 1;
            /* so does SOCK_STREAM unless WAITALL is specified */
            if (!(flags & MSG_WAITALL))
                return 1;
        }

        /* minimum data length for read exceeded */
        if (len >= target)
            return 1;
    }

    return 0;
}


static int dn_recvmsg(struct kiocb *iocb, struct socket *sock,
    struct msghdr *msg, size_t size, int flags)
{
    struct sock *sk = sock->sk;
    struct dn_scp *scp = DN_SK(sk);
    struct sk_buff_head *queue = &sk->sk_receive_queue;
    size_t target = size > 1 ? 1 : 0;
    size_t copied = 0;
    int rv = 0;
    struct sk_buff *skb, *n;
    struct dn_skb_cb *cb = NULL;
    unsigned char eor = 0;
    long timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);

    lock_sock(sk);

    if (sock_flag(sk, SOCK_ZAPPED)) {
        rv = -EADDRNOTAVAIL;
        goto out;
    }

    if (sk->sk_shutdown & RCV_SHUTDOWN) {
        rv = 0;
        goto out;
    }

    rv = dn_check_state(sk, NULL, 0, &timeo, flags);
    if (rv)
        goto out;

    if (flags & ~(MSG_CMSG_COMPAT|MSG_PEEK|MSG_OOB|MSG_WAITALL|MSG_DONTWAIT|MSG_NOSIGNAL)) {
        rv = -EOPNOTSUPP;
        goto out;
    }

    if (flags & MSG_OOB)
        queue = &scp->other_receive_queue;

    if (flags & MSG_WAITALL)
        target = size;


    /*
     * See if there is data ready to read, sleep if there isn't
     */
    for(;;) {
        DEFINE_WAIT(wait);

        if (sk->sk_err)
            goto out;

        if (!skb_queue_empty(&scp->other_receive_queue)) {
            if (!(flags & MSG_OOB)) {
                msg->msg_flags |= MSG_OOB;
                if (!scp->other_report) {
                    scp->other_report = 1;
                    goto out;
                }
            }
        }

        if (scp->state != DN_RUN)
            goto out;

        if (signal_pending(current)) {
            rv = sock_intr_errno(timeo);
            goto out;
        }

        if (dn_data_ready(sk, queue, flags, target))
            break;

        if (flags & MSG_DONTWAIT) {
            rv = -EWOULDBLOCK;
            goto out;
        }

        prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
        set_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags);
        sk_wait_event(sk, &timeo, dn_data_ready(sk, queue, flags, target));
        clear_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags);
        finish_wait(sk_sleep(sk), &wait);
    }

    skb_queue_walk_safe(queue, skb, n) {
        unsigned int chunk = skb->len;
        cb = DN_SKB_CB(skb);

        if ((chunk + copied) > size)
            chunk = size - copied;

        if (memcpy_toiovec(msg->msg_iov, skb->data, chunk)) {
            rv = -EFAULT;
            break;
        }
        copied += chunk;

        if (!(flags & MSG_PEEK))
            skb_pull(skb, chunk);

        eor = cb->nsp_flags & 0x40;

        if (skb->len == 0) {
            skb_unlink(skb, queue);
            kfree_skb(skb);
            /*
             * N.B. Don't refer to skb or cb after this point
             * in loop.
             */
            if ((scp->flowloc_sw == DN_DONTSEND) && !dn_congested(sk)) {
                scp->flowloc_sw = DN_SEND;
                dn_nsp_send_link(sk, DN_SEND, 0);
            }
        }

        if (eor) {
            if (sk->sk_type == SOCK_SEQPACKET)
                break;
            if (!(flags & MSG_WAITALL))
                break;
        }

        if (flags & MSG_OOB)
            break;

        if (copied >= target)
            break;
    }

    rv = copied;


    if (eor && (sk->sk_type == SOCK_SEQPACKET))
        msg->msg_flags |= MSG_EOR;

out:
    if (rv == 0)
        rv = (flags & MSG_PEEK) ? -sk->sk_err : sock_error(sk);

    if ((rv >= 0) && msg->msg_name) {
        memcpy(msg->msg_name, &scp->peer, sizeof(struct sockaddr_dn));
        msg->msg_namelen = sizeof(struct sockaddr_dn);
    }

    release_sock(sk);

    return rv;
}


static inline int dn_queue_too_long(struct dn_scp *scp, struct sk_buff_head *queue, int flags)
{
    unsigned char fctype = scp->services_rem & NSP_FC_MASK;
    if (skb_queue_len(queue) >= scp->snd_window)
        return 1;
    if (fctype != NSP_FC_NONE) {
        if (flags & MSG_OOB) {
            if (scp->flowrem_oth == 0)
                return 1;
        } else {
            if (scp->flowrem_dat == 0)
                return 1;
        }
    }
    return 0;
}

/*
 * The DECnet spec requires that the "routing layer" accepts packets which
 * are at least 230 bytes in size. This excludes any headers which the NSP
 * layer might add, so we always assume that we'll be using the maximal
 * length header on data packets. The variation in length is due to the
 * inclusion (or not) of the two 16 bit acknowledgement fields so it doesn't
 * make much practical difference.
 */
unsigned int dn_mss_from_pmtu(struct net_device *dev, int mtu)
{
    unsigned int mss = 230 - DN_MAX_NSP_DATA_HEADER;
    if (dev) {
        struct dn_dev *dn_db = rcu_dereference_raw(dev->dn_ptr);
        mtu -= LL_RESERVED_SPACE(dev);
        if (dn_db->use_long)
            mtu -= 21;
        else
            mtu -= 6;
        mtu -= DN_MAX_NSP_DATA_HEADER;
    } else {
        /*
         * 21 = long header, 16 = guess at MAC header length
         */
        mtu -= (21 + DN_MAX_NSP_DATA_HEADER + 16);
    }
    if (mtu > mss)
        mss = mtu;
    return mss;
}

static inline unsigned int dn_current_mss(struct sock *sk, int flags)
{
    struct dst_entry *dst = __sk_dst_get(sk);
    struct dn_scp *scp = DN_SK(sk);
    int mss_now = min_t(int, scp->segsize_loc, scp->segsize_rem);

    /* Other data messages are limited to 16 bytes per packet */
    if (flags & MSG_OOB)
        return 16;

    /* This works out the maximum size of segment we can send out */
    if (dst) {
        u32 mtu = dst_mtu(dst);
        mss_now = min_t(int, dn_mss_from_pmtu(dst->dev, mtu), mss_now);
    }

    return mss_now;
}

/*
 * N.B. We get the timeout wrong here, but then we always did get it
 * wrong before and this is another step along the road to correcting
 * it. It ought to get updated each time we pass through the routine,
 * but in practise it probably doesn't matter too much for now.
 */
static inline struct sk_buff *dn_alloc_send_pskb(struct sock *sk,
                  unsigned long datalen, int noblock,
                  int *errcode)
{
    struct sk_buff *skb = sock_alloc_send_skb(sk, datalen,
                           noblock, errcode);
    if (skb) {
        skb->protocol = htons(ETH_P_DNA_RT);
        skb->pkt_type = PACKET_OUTGOING;
    }
    return skb;
}

static int dn_sendmsg(struct kiocb *iocb, struct socket *sock,
              struct msghdr *msg, size_t size)
{
    struct sock *sk = sock->sk;
    struct dn_scp *scp = DN_SK(sk);
    size_t mss;
    struct sk_buff_head *queue = &scp->data_xmit_queue;
    int flags = msg->msg_flags;
    int err = 0;
    size_t sent = 0;
    int addr_len = msg->msg_namelen;
    struct sockaddr_dn *addr = (struct sockaddr_dn *)msg->msg_name;
    struct sk_buff *skb = NULL;
    struct dn_skb_cb *cb;
    size_t len;
    unsigned char fctype;
    long timeo;

    if (flags & ~(MSG_TRYHARD|MSG_OOB|MSG_DONTWAIT|MSG_EOR|MSG_NOSIGNAL|MSG_MORE|MSG_CMSG_COMPAT))
        return -EOPNOTSUPP;

    if (addr_len && (addr_len != sizeof(struct sockaddr_dn)))
        return -EINVAL;

    lock_sock(sk);
    timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
    /*
     * The only difference between stream sockets and sequenced packet
     * sockets is that the stream sockets always behave as if MSG_EOR
     * has been set.
     */
    if (sock->type == SOCK_STREAM) {
        if (flags & MSG_EOR) {
            err = -EINVAL;
            goto out;
        }
        flags |= MSG_EOR;
    }


    err = dn_check_state(sk, addr, addr_len, &timeo, flags);
    if (err)
        goto out_err;

    if (sk->sk_shutdown & SEND_SHUTDOWN) {
        err = -EPIPE;
        if (!(flags & MSG_NOSIGNAL))
            send_sig(SIGPIPE, current, 0);
        goto out_err;
    }

    if ((flags & MSG_TRYHARD) && sk->sk_dst_cache)
        dst_negative_advice(sk);

    mss = scp->segsize_rem;
    fctype = scp->services_rem & NSP_FC_MASK;

    mss = dn_current_mss(sk, flags);

    if (flags & MSG_OOB) {
        queue = &scp->other_xmit_queue;
        if (size > mss) {
            err = -EMSGSIZE;
            goto out;
        }
    }

    scp->persist_fxn = dn_nsp_xmit_timeout;

    while(sent < size) {
        err = sock_error(sk);
        if (err)
            goto out;

        if (signal_pending(current)) {
            err = sock_intr_errno(timeo);
            goto out;
        }

        /*
         * Calculate size that we wish to send.
         */
        len = size - sent;

        if (len > mss)
            len = mss;

        /*
         * Wait for queue size to go down below the window
         * size.
         */
        if (dn_queue_too_long(scp, queue, flags)) {
            DEFINE_WAIT(wait);

            if (flags & MSG_DONTWAIT) {
                err = -EWOULDBLOCK;
                goto out;
            }

            prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
            set_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags);
            sk_wait_event(sk, &timeo,
                      !dn_queue_too_long(scp, queue, flags));
            clear_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags);
            finish_wait(sk_sleep(sk), &wait);
            continue;
        }

        /*
         * Get a suitably sized skb.
         * 64 is a bit of a hack really, but its larger than any
         * link-layer headers and has served us well as a good
         * guess as to their real length.
         */
        skb = dn_alloc_send_pskb(sk, len + 64 + DN_MAX_NSP_DATA_HEADER,
                     flags & MSG_DONTWAIT, &err);

        if (err)
            break;

        if (!skb)
            continue;

        cb = DN_SKB_CB(skb);

        skb_reserve(skb, 64 + DN_MAX_NSP_DATA_HEADER);

        if (memcpy_fromiovec(skb_put(skb, len), msg->msg_iov, len)) {
            err = -EFAULT;
            goto out;
        }

        if (flags & MSG_OOB) {
            cb->nsp_flags = 0x30;
            if (fctype != NSP_FC_NONE)
                scp->flowrem_oth--;
        } else {
            cb->nsp_flags = 0x00;
            if (scp->seg_total == 0)
                cb->nsp_flags |= 0x20;

            scp->seg_total += len;

            if (((sent + len) == size) && (flags & MSG_EOR)) {
                cb->nsp_flags |= 0x40;
                scp->seg_total = 0;
                if (fctype == NSP_FC_SCMC)
                    scp->flowrem_dat--;
            }
            if (fctype == NSP_FC_SRC)
                scp->flowrem_dat--;
        }

        sent += len;
        dn_nsp_queue_xmit(sk, skb, sk->sk_allocation, flags & MSG_OOB);
        skb = NULL;

        scp->persist = dn_nsp_persist(sk);

    }
out:

    kfree_skb(skb);

    release_sock(sk);

    return sent ? sent : err;

out_err:
    err = sk_stream_error(sk, flags, err);
    release_sock(sk);
    return err;
}

static int dn_device_event(struct notifier_block *this, unsigned long event,
            void *ptr)
{
    struct net_device *dev = (struct net_device *)ptr;

    if (!net_eq(dev_net(dev), &init_net))
        return NOTIFY_DONE;

    switch (event) {
    case NETDEV_UP:
        dn_dev_up(dev);
        break;
    case NETDEV_DOWN:
        dn_dev_down(dev);
        break;
    default:
        break;
    }

    return NOTIFY_DONE;
}

static struct notifier_block dn_dev_notifier = {
    .notifier_call = dn_device_event,
};

extern int dn_route_rcv(struct sk_buff *, struct net_device *, struct packet_type *, struct net_device *);

static struct packet_type dn_dix_packet_type __read_mostly = {
    .type =     cpu_to_be16(ETH_P_DNA_RT),
    .func =     dn_route_rcv,
};

#ifdef CONFIG_PROC_FS
struct dn_iter_state {
    int bucket;
};

static struct sock *dn_socket_get_first(struct seq_file *seq)
{
    struct dn_iter_state *state = seq->private;
    struct sock *n = NULL;

    for(state->bucket = 0;
        state->bucket < DN_SK_HASH_SIZE;
        ++state->bucket) {
        n = sk_head(&dn_sk_hash[state->bucket]);
        if (n)
            break;
    }

    return n;
}

static struct sock *dn_socket_get_next(struct seq_file *seq,
                       struct sock *n)
{
    struct dn_iter_state *state = seq->private;

    n = sk_next(n);
try_again:
    if (n)
        goto out;
    if (++state->bucket >= DN_SK_HASH_SIZE)
        goto out;
    n = sk_head(&dn_sk_hash[state->bucket]);
    goto try_again;
out:
    return n;
}

static struct sock *socket_get_idx(struct seq_file *seq, loff_t *pos)
{
    struct sock *sk = dn_socket_get_first(seq);

    if (sk) {
        while(*pos && (sk = dn_socket_get_next(seq, sk)))
            --*pos;
    }
    return *pos ? NULL : sk;
}

static void *dn_socket_get_idx(struct seq_file *seq, loff_t pos)
{
    void *rc;
    read_lock_bh(&dn_hash_lock);
    rc = socket_get_idx(seq, &pos);
    if (!rc) {
        read_unlock_bh(&dn_hash_lock);
    }
    return rc;
}

static void *dn_socket_seq_start(struct seq_file *seq, loff_t *pos)
{
    return *pos ? dn_socket_get_idx(seq, *pos - 1) : SEQ_START_TOKEN;
}

static void *dn_socket_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
    void *rc;

    if (v == SEQ_START_TOKEN) {
        rc = dn_socket_get_idx(seq, 0);
        goto out;
    }

    rc = dn_socket_get_next(seq, v);
    if (rc)
        goto out;
    read_unlock_bh(&dn_hash_lock);
out:
    ++*pos;
    return rc;
}

static void dn_socket_seq_stop(struct seq_file *seq, void *v)
{
    if (v && v != SEQ_START_TOKEN)
        read_unlock_bh(&dn_hash_lock);
}

#define IS_NOT_PRINTABLE(x) ((x) < 32 || (x) > 126)

static void dn_printable_object(struct sockaddr_dn *dn, unsigned char *buf)
{
    int i;

    switch (le16_to_cpu(dn->sdn_objnamel)) {
    case 0:
        sprintf(buf, "%d", dn->sdn_objnum);
        break;
    default:
        for (i = 0; i < le16_to_cpu(dn->sdn_objnamel); i++) {
            buf[i] = dn->sdn_objname[i];
            if (IS_NOT_PRINTABLE(buf[i]))
                buf[i] = '.';
        }
        buf[i] = 0;
    }
}

static char *dn_state2asc(unsigned char state)
{
    switch (state) {
    case DN_O:
        return "OPEN";
    case DN_CR:
        return "  CR";
    case DN_DR:
        return "  DR";
    case DN_DRC:
        return " DRC";
    case DN_CC:
        return "  CC";
    case DN_CI:
        return "  CI";
    case DN_NR:
        return "  NR";
    case DN_NC:
        return "  NC";
    case DN_CD:
        return "  CD";
    case DN_RJ:
        return "  RJ";
    case DN_RUN:
        return " RUN";
    case DN_DI:
        return "  DI";
    case DN_DIC:
        return " DIC";
    case DN_DN:
        return "  DN";
    case DN_CL:
        return "  CL";
    case DN_CN:
        return "  CN";
    }

    return "????";
}

static inline void dn_socket_format_entry(struct seq_file *seq, struct sock *sk)
{
    struct dn_scp *scp = DN_SK(sk);
    char buf1[DN_ASCBUF_LEN];
    char buf2[DN_ASCBUF_LEN];
    char local_object[DN_MAXOBJL+3];
    char remote_object[DN_MAXOBJL+3];

    dn_printable_object(&scp->addr, local_object);
    dn_printable_object(&scp->peer, remote_object);

    seq_printf(seq,
           "%6s/%04X %04d:%04d %04d:%04d %01d %-16s "
           "%6s/%04X %04d:%04d %04d:%04d %01d %-16s %4s %s\n",
           dn_addr2asc(le16_to_cpu(dn_saddr2dn(&scp->addr)), buf1),
           scp->addrloc,
           scp->numdat,
           scp->numoth,
           scp->ackxmt_dat,
           scp->ackxmt_oth,
           scp->flowloc_sw,
           local_object,
           dn_addr2asc(le16_to_cpu(dn_saddr2dn(&scp->peer)), buf2),
           scp->addrrem,
           scp->numdat_rcv,
           scp->numoth_rcv,
           scp->ackrcv_dat,
           scp->ackrcv_oth,
           scp->flowrem_sw,
           remote_object,
           dn_state2asc(scp->state),
           ((scp->accept_mode == ACC_IMMED) ? "IMMED" : "DEFER"));
}

static int dn_socket_seq_show(struct seq_file *seq, void *v)
{
    if (v == SEQ_START_TOKEN) {
        seq_puts(seq, "Local                                              Remote\n");
    } else {
        dn_socket_format_entry(seq, v);
    }
    return 0;
}

static const struct seq_operations dn_socket_seq_ops = {
    .start  = dn_socket_seq_start,
    .next   = dn_socket_seq_next,
    .stop   = dn_socket_seq_stop,
    .show   = dn_socket_seq_show,
};

static int dn_socket_seq_open(struct inode *inode, struct file *file)
{
    return seq_open_private(file, &dn_socket_seq_ops,
            sizeof(struct dn_iter_state));
}

static const struct file_operations dn_socket_seq_fops = {
    .owner      = THIS_MODULE,
    .open       = dn_socket_seq_open,
    .read       = seq_read,
    .llseek     = seq_lseek,
    .release    = seq_release_private,
};
#endif

static const struct net_proto_family    dn_family_ops = {
    .family =   AF_DECnet,
    .create =   dn_create,
    .owner  =   THIS_MODULE,
};

static const struct proto_ops dn_proto_ops = {
    .family =   AF_DECnet,
    .owner =    THIS_MODULE,
    .release =  dn_release,
    .bind =     dn_bind,
    .connect =  dn_connect,
    .socketpair =   sock_no_socketpair,
    .accept =   dn_accept,
    .getname =  dn_getname,
    .poll =     dn_poll,
    .ioctl =    dn_ioctl,
    .listen =   dn_listen,
    .shutdown = dn_shutdown,
    .setsockopt =   dn_setsockopt,
    .getsockopt =   dn_getsockopt,
    .sendmsg =  dn_sendmsg,
    .recvmsg =  dn_recvmsg,
    .mmap =     sock_no_mmap,
    .sendpage = sock_no_sendpage,
};

void dn_register_sysctl(void);
void dn_unregister_sysctl(void);

MODULE_DESCRIPTION("The Linux DECnet Network Protocol");
MODULE_AUTHOR("Linux DECnet Project Team");
MODULE_LICENSE("GPL");
MODULE_ALIAS_NETPROTO(PF_DECnet);

static char banner[] __initdata = KERN_INFO "NET4: DECnet for Linux: V.2.5.68s (C) 1995-2003 Linux DECnet Project Team\n";

static int __init decnet_init(void)
{
    int rc;

    printk(banner);

    rc = proto_register(&dn_proto, 1);
    if (rc != 0)
        goto out;

    dn_neigh_init();
    dn_dev_init();
    dn_route_init();
    dn_fib_init();

    sock_register(&dn_family_ops);
    dev_add_pack(&dn_dix_packet_type);
    register_netdevice_notifier(&dn_dev_notifier);

    proc_net_fops_create(&init_net, "decnet", S_IRUGO, &dn_socket_seq_fops);
    dn_register_sysctl();
out:
    return rc;

}
module_init(decnet_init);

/*
 * Prevent DECnet module unloading until its fixed properly.
 * Requires an audit of the code to check for memory leaks and
 * initialisation problems etc.
 */
#if 0
static void __exit decnet_exit(void)
{
    sock_unregister(AF_DECnet);
    rtnl_unregister_all(PF_DECnet);
    dev_remove_pack(&dn_dix_packet_type);

    dn_unregister_sysctl();

    unregister_netdevice_notifier(&dn_dev_notifier);

    dn_route_cleanup();
    dn_dev_cleanup();
    dn_neigh_cleanup();
    dn_fib_cleanup();

    proc_net_remove(&init_net, "decnet");

    proto_unregister(&dn_proto);

    rcu_barrier_bh(); /* Wait for completion of call_rcu_bh()'s */
}
module_exit(decnet_exit);
#endif