structs.h

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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 Intel Corp.
 *
 * This file is part of the SCTP kernel implementation
 *
 * 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 addresses:
 *    lksctp developers <[email protected]>
 *
 * Or submit a bug report through the following website:
 *    http://www.sf.net/projects/lksctp
 *
 * Written or modified by:
 *    Randall Stewart       <[email protected]>
 *    Ken Morneau       <[email protected]>
 *    Qiaobing Xie      <[email protected]>
 *    La Monte H.P. Yarroll <[email protected]>
 *    Karl Knutson      <[email protected]>
 *    Jon Grimm         <[email protected]>
 *    Xingang Guo       <[email protected]>
 *    Hui Huang         <[email protected]>
 *    Sridhar Samudrala     <[email protected]>
 *    Daisy Chang       <[email protected]>
 *    Dajiang Zhang     <[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.
 */

#ifndef __sctp_structs_h__
#define __sctp_structs_h__

#include <linux/time.h>     /* We get struct timespec.    */
#include <linux/socket.h>   /* linux/in.h needs this!!    */
#include <linux/in.h>       /* We get struct sockaddr_in. */
#include <linux/in6.h>      /* We get struct in6_addr     */
#include <linux/ipv6.h>
#include <asm/param.h>      /* We get MAXHOSTNAMELEN.     */
#include <linux/atomic.h>       /* This gets us atomic counters.  */
#include <linux/skbuff.h>   /* We need sk_buff_head. */
#include <linux/workqueue.h>    /* We need tq_struct.    */
#include <linux/sctp.h>     /* We need sctp* header structs.  */
#include <net/sctp/auth.h>  /* We need auth specific structs */

/* A convenience structure for handling sockaddr structures.
 * We should wean ourselves off this.
 */
union sctp_addr {
    struct sockaddr_in v4;
    struct sockaddr_in6 v6;
    struct sockaddr sa;
};

/* Forward declarations for data structures. */
struct sctp_globals;
struct sctp_endpoint;
struct sctp_association;
struct sctp_transport;
struct sctp_packet;
struct sctp_chunk;
struct sctp_inq;
struct sctp_outq;
struct sctp_bind_addr;
struct sctp_ulpq;
struct sctp_ep_common;
struct sctp_ssnmap;
struct crypto_hash;


#include <net/sctp/tsnmap.h>
#include <net/sctp/ulpevent.h>
#include <net/sctp/ulpqueue.h>

/* Structures useful for managing bind/connect. */

struct sctp_bind_bucket {
    unsigned short  port;
    unsigned short  fastreuse;
    struct hlist_node   node;
    struct hlist_head   owner;
    struct net  *net;
};

struct sctp_bind_hashbucket {
    spinlock_t  lock;
    struct hlist_head   chain;
};

/* Used for hashing all associations.  */
struct sctp_hashbucket {
    rwlock_t    lock;
    struct hlist_head   chain;
} __attribute__((__aligned__(8)));


/* The SCTP globals structure. */
extern struct sctp_globals {
    /* The following variables are implementation specific.  */

    /* Default initialization values to be applied to new associations. */
    __u16 max_instreams;
    __u16 max_outstreams;

    /* This is a list of groups of functions for each address
     * family that we support.
     */
    struct list_head address_families;

    /* This is the hash of all endpoints. */
    int ep_hashsize;
    struct sctp_hashbucket *ep_hashtable;

    /* This is the hash of all associations. */
    int assoc_hashsize;
    struct sctp_hashbucket *assoc_hashtable;

    /* This is the sctp port control hash.  */
    int port_hashsize;
    struct sctp_bind_hashbucket *port_hashtable;

    /* Flag to indicate whether computing and verifying checksum
     * is disabled. */
        bool checksum_disable;
} sctp_globals;

#define sctp_max_instreams      (sctp_globals.max_instreams)
#define sctp_max_outstreams     (sctp_globals.max_outstreams)
#define sctp_address_families       (sctp_globals.address_families)
#define sctp_ep_hashsize        (sctp_globals.ep_hashsize)
#define sctp_ep_hashtable       (sctp_globals.ep_hashtable)
#define sctp_assoc_hashsize     (sctp_globals.assoc_hashsize)
#define sctp_assoc_hashtable        (sctp_globals.assoc_hashtable)
#define sctp_port_hashsize      (sctp_globals.port_hashsize)
#define sctp_port_hashtable     (sctp_globals.port_hashtable)
#define sctp_checksum_disable       (sctp_globals.checksum_disable)

/* SCTP Socket type: UDP or TCP style. */
typedef enum {
    SCTP_SOCKET_UDP = 0,
    SCTP_SOCKET_UDP_HIGH_BANDWIDTH,
    SCTP_SOCKET_TCP
} sctp_socket_type_t;

/* Per socket SCTP information. */
struct sctp_sock {
    /* inet_sock has to be the first member of sctp_sock */
    struct inet_sock inet;
    /* What kind of a socket is this? */
    sctp_socket_type_t type;

    /* PF_ family specific functions.  */
    struct sctp_pf *pf;

    /* Access to HMAC transform. */
    struct crypto_hash *hmac;

    /* What is our base endpointer? */
    struct sctp_endpoint *ep;

    struct sctp_bind_bucket *bind_hash;
    /* Various Socket Options.  */
    __u16 default_stream;
    __u32 default_ppid;
    __u16 default_flags;
    __u32 default_context;
    __u32 default_timetolive;
    __u32 default_rcv_context;
    int max_burst;

    /* Heartbeat interval: The endpoint sends out a Heartbeat chunk to
     * the destination address every heartbeat interval. This value
     * will be inherited by all new associations.
     */
    __u32 hbinterval;

    /* This is the max_retrans value for new associations. */
    __u16 pathmaxrxt;

    /* The initial Path MTU to use for new associations. */
    __u32 pathmtu;

    /* The default SACK delay timeout for new associations. */
    __u32 sackdelay;
    __u32 sackfreq;

    /* Flags controlling Heartbeat, SACK delay, and Path MTU Discovery. */
    __u32 param_flags;

    struct sctp_initmsg initmsg;
    struct sctp_rtoinfo rtoinfo;
    struct sctp_paddrparams paddrparam;
    struct sctp_event_subscribe subscribe;
    struct sctp_assocparams assocparams;
    int user_frag;
    __u32 autoclose;
    __u8 nodelay;
    __u8 disable_fragments;
    __u8 v4mapped;
    __u8 frag_interleave;
    __u32 adaptation_ind;
    __u32 pd_point;

    atomic_t pd_mode;
    /* Receive to here while partial delivery is in effect. */
    struct sk_buff_head pd_lobby;
    struct list_head auto_asconf_list;
    int do_auto_asconf;
};

static inline struct sctp_sock *sctp_sk(const struct sock *sk)
{
       return (struct sctp_sock *)sk;
}

static inline struct sock *sctp_opt2sk(const struct sctp_sock *sp)
{
       return (struct sock *)sp;
}

#if IS_ENABLED(CONFIG_IPV6)
struct sctp6_sock {
       struct sctp_sock  sctp;
       struct ipv6_pinfo inet6;
};
#endif /* CONFIG_IPV6 */


/* This is our APPLICATION-SPECIFIC state cookie.
 * THIS IS NOT DICTATED BY THE SPECIFICATION.
 */
/* These are the parts of an association which we send in the cookie.
 * Most of these are straight out of:
 * RFC2960 12.2 Parameters necessary per association (i.e. the TCB)
 *
 */

struct sctp_cookie {

    /* My          : Tag expected in every inbound packet and sent
     * Verification: in the INIT or INIT ACK chunk.
     * Tag         :
     */
    __u32 my_vtag;

    /* Peer's      : Tag expected in every outbound packet except
     * Verification: in the INIT chunk.
     * Tag         :
     */
    __u32 peer_vtag;

    /* The rest of these are not from the spec, but really need to
     * be in the cookie.
     */

    /* My Tie Tag  : Assist in discovering a restarting association. */
    __u32 my_ttag;

    /* Peer's Tie Tag: Assist in discovering a restarting association. */
    __u32 peer_ttag;

    /* When does this cookie expire? */
    struct timeval expiration;

    /* Number of inbound/outbound streams which are set
     * and negotiated during the INIT process.
     */
    __u16 sinit_num_ostreams;
    __u16 sinit_max_instreams;

    /* This is the first sequence number I used.  */
    __u32 initial_tsn;

    /* This holds the originating address of the INIT packet.  */
    union sctp_addr peer_addr;

    /* IG Section 2.35.3 
     * Include the source port of the INIT-ACK
     */
    __u16       my_port;

    __u8 prsctp_capable;

    /* Padding for future use */
    __u8 padding;       

    __u32 adaptation_ind;

    __u8 auth_random[sizeof(sctp_paramhdr_t) + SCTP_AUTH_RANDOM_LENGTH];
    __u8 auth_hmacs[SCTP_AUTH_NUM_HMACS * sizeof(__u16) + 2];
    __u8 auth_chunks[sizeof(sctp_paramhdr_t) + SCTP_AUTH_MAX_CHUNKS];

    /* This is a shim for my peer's INIT packet, followed by
     * a copy of the raw address list of the association.
     * The length of the raw address list is saved in the
     * raw_addr_list_len field, which will be used at the time when
     * the association TCB is re-constructed from the cookie.
     */
    __u32 raw_addr_list_len;
    struct sctp_init_chunk peer_init[0];
};


/* The format of our cookie that we send to our peer. */
struct sctp_signed_cookie {
    __u8 signature[SCTP_SECRET_SIZE];
    __u32 __pad;        /* force sctp_cookie alignment to 64 bits */
    struct sctp_cookie c;
} __packed;

/* This is another convenience type to allocate memory for address
 * params for the maximum size and pass such structures around
 * internally.
 */
union sctp_addr_param {
    struct sctp_paramhdr p;
    struct sctp_ipv4addr_param v4;
    struct sctp_ipv6addr_param v6;
};

/* A convenience type to allow walking through the various
 * parameters and avoid casting all over the place.
 */
union sctp_params {
    void *v;
    struct sctp_paramhdr *p;
    struct sctp_cookie_preserve_param *life;
    struct sctp_hostname_param *dns;
    struct sctp_cookie_param *cookie;
    struct sctp_supported_addrs_param *sat;
    struct sctp_ipv4addr_param *v4;
    struct sctp_ipv6addr_param *v6;
    union sctp_addr_param *addr;
    struct sctp_adaptation_ind_param *aind;
    struct sctp_supported_ext_param *ext;
    struct sctp_random_param *random;
    struct sctp_chunks_param *chunks;
    struct sctp_hmac_algo_param *hmac_algo;
    struct sctp_addip_param *addip;
};

/* RFC 2960.  Section 3.3.5 Heartbeat.
 *    Heartbeat Information: variable length
 *    The Sender-specific Heartbeat Info field should normally include
 *    information about the sender's current time when this HEARTBEAT
 *    chunk is sent and the destination transport address to which this
 *    HEARTBEAT is sent (see Section 8.3).
 */
typedef struct sctp_sender_hb_info {
    struct sctp_paramhdr param_hdr;
    union sctp_addr daddr;
    unsigned long sent_at;
    __u64 hb_nonce;
} __packed sctp_sender_hb_info_t;

/*
 *  RFC 2960 1.3.2 Sequenced Delivery within Streams
 *
 *  The term "stream" is used in SCTP to refer to a sequence of user
 *  messages that are to be delivered to the upper-layer protocol in
 *  order with respect to other messages within the same stream.  This is
 *  in contrast to its usage in TCP, where it refers to a sequence of
 *  bytes (in this document a byte is assumed to be eight bits).
 *  ...
 *
 *  This is the structure we use to track both our outbound and inbound
 *  SSN, or Stream Sequence Numbers.
 */

struct sctp_stream {
    __u16 *ssn;
    unsigned int len;
};

struct sctp_ssnmap {
    struct sctp_stream in;
    struct sctp_stream out;
    int malloced;
};

struct sctp_ssnmap *sctp_ssnmap_new(__u16 in, __u16 out,
                    gfp_t gfp);
void sctp_ssnmap_free(struct sctp_ssnmap *map);
void sctp_ssnmap_clear(struct sctp_ssnmap *map);

/* What is the current SSN number for this stream? */
static inline __u16 sctp_ssn_peek(struct sctp_stream *stream, __u16 id)
{
    return stream->ssn[id];
}

/* Return the next SSN number for this stream.  */
static inline __u16 sctp_ssn_next(struct sctp_stream *stream, __u16 id)
{
    return stream->ssn[id]++;
}

/* Skip over this ssn and all below. */
static inline void sctp_ssn_skip(struct sctp_stream *stream, __u16 id, 
                 __u16 ssn)
{
    stream->ssn[id] = ssn+1;
}
              
/*
 * Pointers to address related SCTP functions.
 * (i.e. things that depend on the address family.)
 */
struct sctp_af {
    int     (*sctp_xmit)    (struct sk_buff *skb,
                     struct sctp_transport *);
    int     (*setsockopt)   (struct sock *sk,
                     int level,
                     int optname,
                     char __user *optval,
                     unsigned int optlen);
    int     (*getsockopt)   (struct sock *sk,
                     int level,
                     int optname,
                     char __user *optval,
                     int __user *optlen);
    int     (*compat_setsockopt)    (struct sock *sk,
                     int level,
                     int optname,
                     char __user *optval,
                     unsigned int optlen);
    int     (*compat_getsockopt)    (struct sock *sk,
                     int level,
                     int optname,
                     char __user *optval,
                     int __user *optlen);
    void        (*get_dst)  (struct sctp_transport *t,
                     union sctp_addr *saddr,
                     struct flowi *fl,
                     struct sock *sk);
    void        (*get_saddr)    (struct sctp_sock *sk,
                     struct sctp_transport *t,
                     struct flowi *fl);
    void        (*copy_addrlist) (struct list_head *,
                      struct net_device *);
    int     (*cmp_addr) (const union sctp_addr *addr1,
                     const union sctp_addr *addr2);
    void        (*addr_copy)    (union sctp_addr *dst,
                     union sctp_addr *src);
    void        (*from_skb) (union sctp_addr *,
                     struct sk_buff *skb,
                     int saddr);
    void        (*from_sk)  (union sctp_addr *,
                     struct sock *sk);
    void        (*to_sk_saddr)  (union sctp_addr *,
                     struct sock *sk);
    void        (*to_sk_daddr)  (union sctp_addr *,
                     struct sock *sk);
    void        (*from_addr_param) (union sctp_addr *,
                        union sctp_addr_param *,
                        __be16 port, int iif);
    int     (*to_addr_param) (const union sctp_addr *,
                      union sctp_addr_param *); 
    int     (*addr_valid)   (union sctp_addr *,
                     struct sctp_sock *,
                     const struct sk_buff *);
    sctp_scope_t    (*scope) (union sctp_addr *);
    void        (*inaddr_any)   (union sctp_addr *, __be16);
    int     (*is_any)   (const union sctp_addr *);
    int     (*available)    (union sctp_addr *,
                     struct sctp_sock *);
    int     (*skb_iif)  (const struct sk_buff *sk);
    int     (*is_ce)    (const struct sk_buff *sk);
    void        (*seq_dump_addr)(struct seq_file *seq,
                     union sctp_addr *addr);
    void        (*ecn_capable)(struct sock *sk);
    __u16       net_header_len;
    int     sockaddr_len;
    sa_family_t sa_family;
    struct list_head list;
};

struct sctp_af *sctp_get_af_specific(sa_family_t);
int sctp_register_af(struct sctp_af *);

/* Protocol family functions. */
struct sctp_pf {
    void (*event_msgname)(struct sctp_ulpevent *, char *, int *);
    void (*skb_msgname)  (struct sk_buff *, char *, int *);
    int  (*af_supported) (sa_family_t, struct sctp_sock *);
    int  (*cmp_addr) (const union sctp_addr *,
              const union sctp_addr *,
              struct sctp_sock *);
    int  (*bind_verify) (struct sctp_sock *, union sctp_addr *);
    int  (*send_verify) (struct sctp_sock *, union sctp_addr *);
    int  (*supported_addrs)(const struct sctp_sock *, __be16 *);
    struct sock *(*create_accept_sk) (struct sock *sk,
                      struct sctp_association *asoc);
    void (*addr_v4map) (struct sctp_sock *, union sctp_addr *);
    struct sctp_af *af;
};


/* Structure to track chunk fragments that have been acked, but peer
 * fragments of the same message have not.
 */
struct sctp_datamsg {
    /* Chunks waiting to be submitted to lower layer. */
    struct list_head chunks;
    /* Reference counting. */
    atomic_t refcnt;
    /* When is this message no longer interesting to the peer? */
    unsigned long expires_at;
    /* Did the messenge fail to send? */
    int send_error;
    u8 send_failed:1,
       can_abandon:1,   /* can chunks from this message can be abandoned. */
       can_delay;       /* should this message be Nagle delayed */
};

struct sctp_datamsg *sctp_datamsg_from_user(struct sctp_association *,
                        struct sctp_sndrcvinfo *,
                        struct msghdr *, int len);
void sctp_datamsg_free(struct sctp_datamsg *);
void sctp_datamsg_put(struct sctp_datamsg *);
void sctp_chunk_fail(struct sctp_chunk *, int error);
int sctp_chunk_abandoned(struct sctp_chunk *);

/* RFC2960 1.4 Key Terms
 *
 * o Chunk: A unit of information within an SCTP packet, consisting of
 * a chunk header and chunk-specific content.
 *
 * As a matter of convenience, we remember the SCTP common header for
 * each chunk as well as a few other header pointers...
 */
struct sctp_chunk {
    struct list_head list;

    atomic_t refcnt;

    /* This is our link to the per-transport transmitted list.  */
    struct list_head transmitted_list;

    /* This field is used by chunks that hold fragmented data.
     * For the first fragment this is the list that holds the rest of
     * fragments. For the remaining fragments, this is the link to the
     * frag_list maintained in the first fragment.
     */
    struct list_head frag_list;

    /* This points to the sk_buff containing the actual data.  */
    struct sk_buff *skb;

    /* These are the SCTP headers by reverse order in a packet.
     * Note that some of these may happen more than once.  In that
     * case, we point at the "current" one, whatever that means
     * for that level of header.
     */

    /* We point this at the FIRST TLV parameter to chunk_hdr.  */
    union sctp_params param_hdr;
    union {
        __u8 *v;
        struct sctp_datahdr *data_hdr;
        struct sctp_inithdr *init_hdr;
        struct sctp_sackhdr *sack_hdr;
        struct sctp_heartbeathdr *hb_hdr;
        struct sctp_sender_hb_info *hbs_hdr;
        struct sctp_shutdownhdr *shutdown_hdr;
        struct sctp_signed_cookie *cookie_hdr;
        struct sctp_ecnehdr *ecne_hdr;
        struct sctp_cwrhdr *ecn_cwr_hdr;
        struct sctp_errhdr *err_hdr;
        struct sctp_addiphdr *addip_hdr;
        struct sctp_fwdtsn_hdr *fwdtsn_hdr;
        struct sctp_authhdr *auth_hdr;
    } subh;

    __u8 *chunk_end;

    struct sctp_chunkhdr *chunk_hdr;
    struct sctphdr *sctp_hdr;

    /* This needs to be recoverable for SCTP_SEND_FAILED events. */
    struct sctp_sndrcvinfo sinfo;

    /* Which association does this belong to?  */
    struct sctp_association *asoc;

    /* What endpoint received this chunk? */
    struct sctp_ep_common *rcvr;

    /* We fill this in if we are calculating RTT. */
    unsigned long sent_at;

    /* What is the origin IP address for this chunk?  */
    union sctp_addr source;
    /* Destination address for this chunk. */
    union sctp_addr dest;

    /* For outbound message, track all fragments for SEND_FAILED. */
    struct sctp_datamsg *msg;

    /* For an inbound chunk, this tells us where it came from.
     * For an outbound chunk, it tells us where we'd like it to
     * go.  It is NULL if we have no preference.
     */
    struct sctp_transport *transport;

    /* SCTP-AUTH:  For the special case inbound processing of COOKIE-ECHO
     * we need save a pointer to the AUTH chunk, since the SCTP-AUTH
     * spec violates the principle premis that all chunks are processed
     * in order.
     */
    struct sk_buff *auth_chunk;

#define SCTP_CAN_FRTX 0x0
#define SCTP_NEED_FRTX 0x1
#define SCTP_DONT_FRTX 0x2
    __u16   rtt_in_progress:1,  /* This chunk used for RTT calc? */
        has_tsn:1,      /* Does this chunk have a TSN yet? */
        has_ssn:1,      /* Does this chunk have a SSN yet? */
        singleton:1,        /* Only chunk in the packet? */
        end_of_packet:1,    /* Last chunk in the packet? */
        ecn_ce_done:1,      /* Have we processed the ECN CE bit? */
        pdiscard:1,     /* Discard the whole packet now? */
        tsn_gap_acked:1,    /* Is this chunk acked by a GAP ACK? */
        data_accepted:1,    /* At least 1 chunk accepted */
        auth:1,         /* IN: was auth'ed | OUT: needs auth */
        has_asconf:1,       /* IN: have seen an asconf before */
        tsn_missing_report:2,   /* Data chunk missing counter. */
        fast_retransmit:2;  /* Is this chunk fast retransmitted? */
};

void sctp_chunk_hold(struct sctp_chunk *);
void sctp_chunk_put(struct sctp_chunk *);
int sctp_user_addto_chunk(struct sctp_chunk *chunk, int off, int len,
              struct iovec *data);
void sctp_chunk_free(struct sctp_chunk *);
void  *sctp_addto_chunk(struct sctp_chunk *, int len, const void *data);
void  *sctp_addto_chunk_fixed(struct sctp_chunk *, int len, const void *data);
struct sctp_chunk *sctp_chunkify(struct sk_buff *,
                 const struct sctp_association *,
                 struct sock *);
void sctp_init_addrs(struct sctp_chunk *, union sctp_addr *,
             union sctp_addr *);
const union sctp_addr *sctp_source(const struct sctp_chunk *chunk);

enum {
    SCTP_ADDR_NEW,      /* new address added to assoc/ep */
    SCTP_ADDR_SRC,      /* address can be used as source */
    SCTP_ADDR_DEL,      /* address about to be deleted */
};

/* This is a structure for holding either an IPv6 or an IPv4 address.  */
struct sctp_sockaddr_entry {
    struct list_head list;
    struct rcu_head rcu;
    union sctp_addr a;
    __u8 state;
    __u8 valid;
};

#define SCTP_ADDRESS_TICK_DELAY 500

typedef struct sctp_chunk *(sctp_packet_phandler_t)(struct sctp_association *);

/* This structure holds lists of chunks as we are assembling for
 * transmission.
 */
struct sctp_packet {
    /* These are the SCTP header values (host order) for the packet. */
    __u16 source_port;
    __u16 destination_port;
    __u32 vtag;

    /* This contains the payload chunks.  */
    struct list_head chunk_list;

    /* This is the overhead of the sctp and ip headers. */
    size_t overhead;
    /* This is the total size of all chunks INCLUDING padding.  */
    size_t size;

    /* The packet is destined for this transport address.
     * The function we finally use to pass down to the next lower
     * layer lives in the transport structure.
     */
    struct sctp_transport *transport;

    /* pointer to the auth chunk for this packet */
    struct sctp_chunk *auth;

    u8  has_cookie_echo:1,  /* This packet contains a COOKIE-ECHO chunk. */
        has_sack:1,     /* This packet contains a SACK chunk. */
        has_auth:1,     /* This packet contains an AUTH chunk */
        has_data:1,     /* This packet contains at least 1 DATA chunk */
        ipfragok:1,     /* So let ip fragment this packet */
        malloced:1;     /* Is it malloced? */
};

struct sctp_packet *sctp_packet_init(struct sctp_packet *,
                     struct sctp_transport *,
                     __u16 sport, __u16 dport);
struct sctp_packet *sctp_packet_config(struct sctp_packet *, __u32 vtag, int);
sctp_xmit_t sctp_packet_transmit_chunk(struct sctp_packet *,
                                       struct sctp_chunk *, int);
sctp_xmit_t sctp_packet_append_chunk(struct sctp_packet *,
                                     struct sctp_chunk *);
int sctp_packet_transmit(struct sctp_packet *);
void sctp_packet_free(struct sctp_packet *);

static inline int sctp_packet_empty(struct sctp_packet *packet)
{
    return packet->size == packet->overhead;
}

/* This represents a remote transport address.
 * For local transport addresses, we just use union sctp_addr.
 *
 * RFC2960 Section 1.4 Key Terms
 *
 *   o  Transport address:  A Transport Address is traditionally defined
 *  by Network Layer address, Transport Layer protocol and Transport
 *  Layer port number.  In the case of SCTP running over IP, a
 *  transport address is defined by the combination of an IP address
 *  and an SCTP port number (where SCTP is the Transport protocol).
 *
 * RFC2960 Section 7.1 SCTP Differences from TCP Congestion control
 *
 *   o  The sender keeps a separate congestion control parameter set for
 *  each of the destination addresses it can send to (not each
 *  source-destination pair but for each destination).  The parameters
 *  should decay if the address is not used for a long enough time
 *  period.
 *
 */
struct sctp_transport {
    /* A list of transports. */
    struct list_head transports;

    /* Reference counting. */
    atomic_t refcnt;
    __u32    dead:1,
        /* RTO-Pending : A flag used to track if one of the DATA
         *      chunks sent to this address is currently being
         *      used to compute a RTT. If this flag is 0,
         *      the next DATA chunk sent to this destination
         *      should be used to compute a RTT and this flag
         *      should be set. Every time the RTT
         *      calculation completes (i.e. the DATA chunk
         *      is SACK'd) clear this flag.
         */
         rto_pending:1,

        /*
         * hb_sent : a flag that signals that we have a pending
         * heartbeat.
         */
        hb_sent:1,

        /* Is the Path MTU update pending on this tranport */
        pmtu_pending:1,

        /* Is this structure kfree()able? */
        malloced:1;

    /* Has this transport moved the ctsn since we last sacked */
    __u32 sack_generation;

    struct flowi fl;

    /* This is the peer's IP address and port. */
    union sctp_addr ipaddr;

    /* These are the functions we call to handle LLP stuff.  */
    struct sctp_af *af_specific;

    /* Which association do we belong to?  */
    struct sctp_association *asoc;

    /* RFC2960
     *
     * 12.3 Per Transport Address Data
     *
     * For each destination transport address in the peer's
     * address list derived from the INIT or INIT ACK chunk, a
     * number of data elements needs to be maintained including:
     */
    /* RTO         : The current retransmission timeout value.  */
    unsigned long rto;

    __u32 rtt;      /* This is the most recent RTT.  */

    /* RTTVAR      : The current RTT variation.  */
    __u32 rttvar;

    /* SRTT        : The current smoothed round trip time.  */
    __u32 srtt;

    /*
     * These are the congestion stats.
     */
    /* cwnd        : The current congestion window.  */
    __u32 cwnd;       /* This is the actual cwnd.  */

    /* ssthresh    : The current slow start threshold value.  */
    __u32 ssthresh;

    /* partial     : The tracking method for increase of cwnd when in
     * bytes acked : congestion avoidance mode (see Section 6.2.2)
     */
    __u32 partial_bytes_acked;

    /* Data that has been sent, but not acknowledged. */
    __u32 flight_size;

    __u32 burst_limited;    /* Holds old cwnd when max.burst is applied */

    /* Destination */
    struct dst_entry *dst;
    /* Source address. */
    union sctp_addr saddr;

    /* Heartbeat interval: The endpoint sends out a Heartbeat chunk to
     * the destination address every heartbeat interval.
     */
    unsigned long hbinterval;

    /* SACK delay timeout */
    unsigned long sackdelay;
    __u32 sackfreq;

    /* When was the last time (in jiffies) that we heard from this
     * transport?  We use this to pick new active and retran paths.
     */
    unsigned long last_time_heard;

    /* Last time(in jiffies) when cwnd is reduced due to the congestion
     * indication based on ECNE chunk.
     */
    unsigned long last_time_ecne_reduced;

    /* This is the max_retrans value for the transport and will
     * be initialized from the assocs value.  This can be changed
     * using the SCTP_SET_PEER_ADDR_PARAMS socket option.
     */
    __u16 pathmaxrxt;

    /* This is the partially failed retrans value for the transport
     * and will be initialized from the assocs value.  This can be changed
     * using the SCTP_PEER_ADDR_THLDS socket option
     */
    int pf_retrans;
    /* PMTU       : The current known path MTU.  */
    __u32 pathmtu;

    /* Flags controlling Heartbeat, SACK delay, and Path MTU Discovery. */
    __u32 param_flags;

    /* The number of times INIT has been sent on this transport. */
    int init_sent_count;

    /* state       : The current state of this destination,
     *             : i.e. SCTP_ACTIVE, SCTP_INACTIVE, SCTP_UNKNOWN.
     */
    int state;

    /* These are the error stats for this destination.  */

    /* Error count : The current error count for this destination.  */
    unsigned short error_count;

    /* Per         : A timer used by each destination.
     * Destination :
     * Timer       :
     *
     * [Everywhere else in the text this is called T3-rtx. -ed]
     */
    struct timer_list T3_rtx_timer;

    /* Heartbeat timer is per destination. */
    struct timer_list hb_timer;

    /* Timer to handle ICMP proto unreachable envets */
    struct timer_list proto_unreach_timer;

    /* Since we're using per-destination retransmission timers
     * (see above), we're also using per-destination "transmitted"
     * queues.  This probably ought to be a private struct
     * accessible only within the outqueue, but it's not, yet.
     */
    struct list_head transmitted;

    /* We build bundle-able packets for this transport here.  */
    struct sctp_packet packet;

    /* This is the list of transports that have chunks to send.  */
    struct list_head send_ready;

    /* State information saved for SFR_CACC algorithm. The key
     * idea in SFR_CACC is to maintain state at the sender on a
     * per-destination basis when a changeover happens.
     *  char changeover_active;
     *  char cycling_changeover;
     *  __u32 next_tsn_at_change;
     *  char cacc_saw_newack;
     */
    struct {
        /* An unsigned integer, which stores the next TSN to be
         * used by the sender, at the moment of changeover.
         */
        __u32 next_tsn_at_change;

        /* A flag which indicates the occurrence of a changeover */
        char changeover_active;

        /* A flag which indicates whether the change of primary is
         * the first switch to this destination address during an
         * active switch.
         */
        char cycling_changeover;

        /* A temporary flag, which is used during the processing of
         * a SACK to estimate the causative TSN(s)'s group.
         */
        char cacc_saw_newack;
    } cacc;

    /* 64-bit random number sent with heartbeat. */
    __u64 hb_nonce;
};

struct sctp_transport *sctp_transport_new(struct net *, const union sctp_addr *,
                      gfp_t);
void sctp_transport_set_owner(struct sctp_transport *,
                  struct sctp_association *);
void sctp_transport_route(struct sctp_transport *, union sctp_addr *,
              struct sctp_sock *);
void sctp_transport_pmtu(struct sctp_transport *, struct sock *sk);
void sctp_transport_free(struct sctp_transport *);
void sctp_transport_reset_timers(struct sctp_transport *);
void sctp_transport_hold(struct sctp_transport *);
void sctp_transport_put(struct sctp_transport *);
void sctp_transport_update_rto(struct sctp_transport *, __u32);
void sctp_transport_raise_cwnd(struct sctp_transport *, __u32, __u32);
void sctp_transport_lower_cwnd(struct sctp_transport *, sctp_lower_cwnd_t);
void sctp_transport_burst_limited(struct sctp_transport *);
void sctp_transport_burst_reset(struct sctp_transport *);
unsigned long sctp_transport_timeout(struct sctp_transport *);
void sctp_transport_reset(struct sctp_transport *);
void sctp_transport_update_pmtu(struct sock *, struct sctp_transport *, u32);
void sctp_transport_immediate_rtx(struct sctp_transport *);


/* This is the structure we use to queue packets as they come into
 * SCTP.  We write packets to it and read chunks from it.
 */
struct sctp_inq {
    /* This is actually a queue of sctp_chunk each
     * containing a partially decoded packet.
     */
    struct list_head in_chunk_list;
    /* This is the packet which is currently off the in queue and is
     * being worked on through the inbound chunk processing.
     */
    struct sctp_chunk *in_progress;

    /* This is the delayed task to finish delivering inbound
     * messages.
     */
    struct work_struct immediate;

    int malloced;        /* Is this structure kfree()able?  */
};

void sctp_inq_init(struct sctp_inq *);
void sctp_inq_free(struct sctp_inq *);
void sctp_inq_push(struct sctp_inq *, struct sctp_chunk *packet);
struct sctp_chunk *sctp_inq_pop(struct sctp_inq *);
struct sctp_chunkhdr *sctp_inq_peek(struct sctp_inq *);
void sctp_inq_set_th_handler(struct sctp_inq *, work_func_t);

/* This is the structure we use to hold outbound chunks.  You push
 * chunks in and they automatically pop out the other end as bundled
 * packets (it calls (*output_handler)()).
 *
 * This structure covers sections 6.3, 6.4, 6.7, 6.8, 6.10, 7., 8.1,
 * and 8.2 of the v13 draft.
 *
 * It handles retransmissions.  The connection to the timeout portion
 * of the state machine is through sctp_..._timeout() and timeout_handler.
 *
 * If you feed it SACKs, it will eat them.
 *
 * If you give it big chunks, it will fragment them.
 *
 * It assigns TSN's to data chunks.  This happens at the last possible
 * instant before transmission.
 *
 * When free()'d, it empties itself out via output_handler().
 */
struct sctp_outq {
    struct sctp_association *asoc;

    /* Data pending that has never been transmitted.  */
    struct list_head out_chunk_list;

    unsigned int out_qlen;  /* Total length of queued data chunks. */

    /* Error of send failed, may used in SCTP_SEND_FAILED event. */
    unsigned int error;

    /* These are control chunks we want to send.  */
    struct list_head control_chunk_list;

    /* These are chunks that have been sacked but are above the
     * CTSN, or cumulative tsn ack point.
     */
    struct list_head sacked;

    /* Put chunks on this list to schedule them for
     * retransmission.
     */
    struct list_head retransmit;

    /* Put chunks on this list to save them for FWD TSN processing as
     * they were abandoned.
     */
    struct list_head abandoned;

    /* How many unackd bytes do we have in-flight?  */
    __u32 outstanding_bytes;

    /* Are we doing fast-rtx on this queue */
    char fast_rtx;

    /* Corked? */
    char cork;

    /* Is this structure empty?  */
    char empty;

    /* Are we kfree()able? */
    char malloced;
};

void sctp_outq_init(struct sctp_association *, struct sctp_outq *);
void sctp_outq_teardown(struct sctp_outq *);
void sctp_outq_free(struct sctp_outq*);
int sctp_outq_tail(struct sctp_outq *, struct sctp_chunk *chunk);
int sctp_outq_sack(struct sctp_outq *, struct sctp_chunk *);
int sctp_outq_is_empty(const struct sctp_outq *);
void sctp_outq_restart(struct sctp_outq *);

void sctp_retransmit(struct sctp_outq *, struct sctp_transport *,
             sctp_retransmit_reason_t);
void sctp_retransmit_mark(struct sctp_outq *, struct sctp_transport *, __u8);
int sctp_outq_uncork(struct sctp_outq *);
/* Uncork and flush an outqueue.  */
static inline void sctp_outq_cork(struct sctp_outq *q)
{
    q->cork = 1;
}

/* These bind address data fields common between endpoints and associations */
struct sctp_bind_addr {

    /* RFC 2960 12.1 Parameters necessary for the SCTP instance
     *
     * SCTP Port:   The local SCTP port number the endpoint is
     *      bound to.
     */
    __u16 port;

    /* RFC 2960 12.1 Parameters necessary for the SCTP instance
     *
     * Address List: The list of IP addresses that this instance
     *  has bound.  This information is passed to one's
     *  peer(s) in INIT and INIT ACK chunks.
     */
    struct list_head address_list;

    int malloced;        /* Are we kfree()able?  */
};

void sctp_bind_addr_init(struct sctp_bind_addr *, __u16 port);
void sctp_bind_addr_free(struct sctp_bind_addr *);
int sctp_bind_addr_copy(struct net *net, struct sctp_bind_addr *dest,
            const struct sctp_bind_addr *src,
            sctp_scope_t scope, gfp_t gfp,
            int flags);
int sctp_bind_addr_dup(struct sctp_bind_addr *dest,
            const struct sctp_bind_addr *src,
            gfp_t gfp);
int sctp_add_bind_addr(struct sctp_bind_addr *, union sctp_addr *,
               __u8 addr_state, gfp_t gfp);
int sctp_del_bind_addr(struct sctp_bind_addr *, union sctp_addr *);
int sctp_bind_addr_match(struct sctp_bind_addr *, const union sctp_addr *,
             struct sctp_sock *);
int sctp_bind_addr_conflict(struct sctp_bind_addr *, const union sctp_addr *,
             struct sctp_sock *, struct sctp_sock *);
int sctp_bind_addr_state(const struct sctp_bind_addr *bp,
             const union sctp_addr *addr);
union sctp_addr *sctp_find_unmatch_addr(struct sctp_bind_addr   *bp,
                    const union sctp_addr   *addrs,
                    int         addrcnt,
                    struct sctp_sock    *opt);
union sctp_params sctp_bind_addrs_to_raw(const struct sctp_bind_addr *bp,
                     int *addrs_len,
                     gfp_t gfp);
int sctp_raw_to_bind_addrs(struct sctp_bind_addr *bp, __u8 *raw, int len,
               __u16 port, gfp_t gfp);

sctp_scope_t sctp_scope(const union sctp_addr *);
int sctp_in_scope(struct net *net, const union sctp_addr *addr, const sctp_scope_t scope);
int sctp_is_any(struct sock *sk, const union sctp_addr *addr);
int sctp_addr_is_valid(const union sctp_addr *addr);
int sctp_is_ep_boundall(struct sock *sk);


/* What type of endpoint?  */
typedef enum {
    SCTP_EP_TYPE_SOCKET,
    SCTP_EP_TYPE_ASSOCIATION,
} sctp_endpoint_type_t;

/*
 * A common base class to bridge the implmentation view of a
 * socket (usually listening) endpoint versus an association's
 * local endpoint.
 * This common structure is useful for several purposes:
 *   1) Common interface for lookup routines.
 *  a) Subfunctions work for either endpoint or association
 *  b) Single interface to lookup allows hiding the lookup lock rather
 *     than acquiring it externally.
 *   2) Common interface for the inbound chunk handling/state machine.
 *   3) Common object handling routines for reference counting, etc.
 *   4) Disentangle association lookup from endpoint lookup, where we
 *  do not have to find our endpoint to find our association.
 *
 */

struct sctp_ep_common {
    /* Fields to help us manage our entries in the hash tables. */
    struct hlist_node node;
    int hashent;

    /* Runtime type information.  What kind of endpoint is this? */
    sctp_endpoint_type_t type;

    /* Some fields to help us manage this object.
     *   refcnt   - Reference count access to this object.
     *   dead     - Do not attempt to use this object.
     *   malloced - Do we need to kfree this object?
     */
    atomic_t    refcnt;
    char        dead;
    char        malloced;

    /* What socket does this endpoint belong to?  */
    struct sock *sk;

    /* This is where we receive inbound chunks.  */
    struct sctp_inq   inqueue;

    /* This substructure includes the defining parameters of the
     * endpoint:
     * bind_addr.port is our shared port number.
     * bind_addr.address_list is our set of local IP addresses.
     */
    struct sctp_bind_addr bind_addr;
};


/* RFC Section 1.4 Key Terms
 *
 * o SCTP endpoint: The logical sender/receiver of SCTP packets. On a
 *   multi-homed host, an SCTP endpoint is represented to its peers as a
 *   combination of a set of eligible destination transport addresses to
 *   which SCTP packets can be sent and a set of eligible source
 *   transport addresses from which SCTP packets can be received.
 *   All transport addresses used by an SCTP endpoint must use the
 *   same port number, but can use multiple IP addresses. A transport
 *   address used by an SCTP endpoint must not be used by another
 *   SCTP endpoint. In other words, a transport address is unique
 *   to an SCTP endpoint.
 *
 * From an implementation perspective, each socket has one of these.
 * A TCP-style socket will have exactly one association on one of
 * these.  An UDP-style socket will have multiple associations hanging
 * off one of these.
 */

struct sctp_endpoint {
    /* Common substructure for endpoint and association. */
    struct sctp_ep_common base;

    /* Associations: A list of current associations and mappings
     *        to the data consumers for each association. This
     *        may be in the form of a hash table or other
     *        implementation dependent structure. The data
     *        consumers may be process identification
     *        information such as file descriptors, named pipe
     *        pointer, or table pointers dependent on how SCTP
     *        is implemented.
     */
    /* This is really a list of struct sctp_association entries. */
    struct list_head asocs;

    /* Secret Key: A secret key used by this endpoint to compute
     *        the MAC.  This SHOULD be a cryptographic quality
     *        random number with a sufficient length.
     *        Discussion in [RFC1750] can be helpful in
     *        selection of the key.
     */
    __u8 secret_key[SCTP_HOW_MANY_SECRETS][SCTP_SECRET_SIZE];
    int current_key;
    int last_key;
    int key_changed_at;

    /* digest:  This is a digest of the sctp cookie.  This field is
     *      only used on the receive path when we try to validate
     *      that the cookie has not been tampered with.  We put
     *      this here so we pre-allocate this once and can re-use
     *      on every receive.
     */
    __u8 *digest;
 
    /* sendbuf acct. policy.    */
    __u32 sndbuf_policy;

    /* rcvbuf acct. policy. */
    __u32 rcvbuf_policy;

    /* SCTP AUTH: array of the HMACs that will be allocated
     * we need this per association so that we don't serialize
     */
    struct crypto_hash **auth_hmacs;

    /* SCTP-AUTH: hmacs for the endpoint encoded into parameter */
     struct sctp_hmac_algo_param *auth_hmacs_list;

    /* SCTP-AUTH: chunks to authenticate encoded into parameter */
    struct sctp_chunks_param *auth_chunk_list;

    /* SCTP-AUTH: endpoint shared keys */
    struct list_head endpoint_shared_keys;
    __u16 active_key_id;
};

/* Recover the outter endpoint structure. */
static inline struct sctp_endpoint *sctp_ep(struct sctp_ep_common *base)
{
    struct sctp_endpoint *ep;

    ep = container_of(base, struct sctp_endpoint, base);
    return ep;
}

/* These are function signatures for manipulating endpoints.  */
struct sctp_endpoint *sctp_endpoint_new(struct sock *, gfp_t);
void sctp_endpoint_free(struct sctp_endpoint *);
void sctp_endpoint_put(struct sctp_endpoint *);
void sctp_endpoint_hold(struct sctp_endpoint *);
void sctp_endpoint_add_asoc(struct sctp_endpoint *, struct sctp_association *);
struct sctp_association *sctp_endpoint_lookup_assoc(
    const struct sctp_endpoint *ep,
    const union sctp_addr *paddr,
    struct sctp_transport **);
int sctp_endpoint_is_peeled_off(struct sctp_endpoint *,
                const union sctp_addr *);
struct sctp_endpoint *sctp_endpoint_is_match(struct sctp_endpoint *,
                    struct net *, const union sctp_addr *);
int sctp_has_association(struct net *net, const union sctp_addr *laddr,
             const union sctp_addr *paddr);

int sctp_verify_init(struct net *net, const struct sctp_association *asoc,
             sctp_cid_t, sctp_init_chunk_t *peer_init,
             struct sctp_chunk *chunk, struct sctp_chunk **err_chunk);
int sctp_process_init(struct sctp_association *, struct sctp_chunk *chunk,
              const union sctp_addr *peer,
              sctp_init_chunk_t *init, gfp_t gfp);
__u32 sctp_generate_tag(const struct sctp_endpoint *);
__u32 sctp_generate_tsn(const struct sctp_endpoint *);

struct sctp_inithdr_host {
    __u32 init_tag;
    __u32 a_rwnd;
    __u16 num_outbound_streams;
    __u16 num_inbound_streams;
    __u32 initial_tsn;
};

/* RFC2960
 *
 * 12. Recommended Transmission Control Block (TCB) Parameters
 *
 * This section details a recommended set of parameters that should
 * be contained within the TCB for an implementation. This section is
 * for illustrative purposes and should not be deemed as requirements
 * on an implementation or as an exhaustive list of all parameters
 * inside an SCTP TCB. Each implementation may need its own additional
 * parameters for optimization.
 */


/* Here we have information about each individual association. */
struct sctp_association {

    /* A base structure common to endpoint and association.
     * In this context, it represents the associations's view
     * of the local endpoint of the association.
     */
    struct sctp_ep_common base;

    /* Associations on the same socket. */
    struct list_head asocs;

    /* association id. */
    sctp_assoc_t assoc_id;

    /* This is our parent endpoint.  */
    struct sctp_endpoint *ep;

    /* These are those association elements needed in the cookie.  */
    struct sctp_cookie c;

    /* This is all information about our peer.  */
    struct {
        /* rwnd
         *
         * Peer Rwnd   : Current calculated value of the peer's rwnd.
         */
        __u32 rwnd;

        /* transport_addr_list
         *
         * Peer        : A list of SCTP transport addresses that the
         * Transport   : peer is bound to. This information is derived
         * Address     : from the INIT or INIT ACK and is used to
         * List        : associate an inbound packet with a given
         *         : association. Normally this information is
         *         : hashed or keyed for quick lookup and access
         *         : of the TCB.
         *         : The list is also initialized with the list
         *         : of addresses passed with the sctp_connectx()
         *         : call.
         *
         * It is a list of SCTP_transport's.
         */
        struct list_head transport_addr_list;

        /* transport_count
         *
         * Peer        : A count of the number of peer addresses
         * Transport   : in the Peer Transport Address List.
         * Address     :
         * Count       :
         */
        __u16 transport_count;

        /* port
         *   The transport layer port number.
         */
        __u16 port;

        /* primary_path
         *
         * Primary     : This is the current primary destination
         * Path        : transport address of the peer endpoint.  It
         *         : may also specify a source transport address
         *         : on this endpoint.
         *
         * All of these paths live on transport_addr_list.
         *
         * At the bakeoffs, we discovered that the intent of
         * primaryPath is that it only changes when the ULP
         * asks to have it changed.  We add the activePath to
         * designate the connection we are currently using to
         * transmit new data and most control chunks.
         */
        struct sctp_transport *primary_path;

        /* Cache the primary path address here, when we
         * need a an address for msg_name.
         */
        union sctp_addr primary_addr;

        /* active_path
         *   The path that we are currently using to
         *   transmit new data and most control chunks.
         */
        struct sctp_transport *active_path;

        /* retran_path
         *
         * RFC2960 6.4 Multi-homed SCTP Endpoints
         * ...
         * Furthermore, when its peer is multi-homed, an
         * endpoint SHOULD try to retransmit a chunk to an
         * active destination transport address that is
         * different from the last destination address to
         * which the DATA chunk was sent.
         */
        struct sctp_transport *retran_path;

        /* Pointer to last transport I have sent on.  */
        struct sctp_transport *last_sent_to;

        /* This is the last transport I have received DATA on.  */
        struct sctp_transport *last_data_from;

        /*
         * Mapping  An array of bits or bytes indicating which out of
         * Array    order TSN's have been received (relative to the
         *      Last Rcvd TSN). If no gaps exist, i.e. no out of
         *      order packets have been received, this array
         *      will be set to all zero. This structure may be
         *      in the form of a circular buffer or bit array.
         *
         * Last Rcvd   : This is the last TSN received in
         * TSN         : sequence. This value is set initially by
         *         : taking the peer's Initial TSN, received in
         *         : the INIT or INIT ACK chunk, and subtracting
         *         : one from it.
         *
         * Throughout most of the specification this is called the
         * "Cumulative TSN ACK Point".  In this case, we
         * ignore the advice in 12.2 in favour of the term
         * used in the bulk of the text.  This value is hidden
         * in tsn_map--we get it by calling sctp_tsnmap_get_ctsn().
         */
        struct sctp_tsnmap tsn_map;

        /* Ack State   : This flag indicates if the next received
         *             : packet is to be responded to with a
         *             : SACK. This is initializedto 0.  When a packet
         *             : is received it is incremented. If this value
         *             : reaches 2 or more, a SACK is sent and the
         *             : value is reset to 0. Note: This is used only
         *             : when no DATA chunks are received out of
         *             : order.  When DATA chunks are out of order,
         *             : SACK's are not delayed (see Section 6).
         */
        __u8    sack_needed;     /* Do we need to sack the peer? */
        __u32   sack_cnt;
        __u32   sack_generation;

        /* These are capabilities which our peer advertised.  */
        __u8    ecn_capable:1,      /* Can peer do ECN? */
            ipv4_address:1,     /* Peer understands IPv4 addresses? */
            ipv6_address:1,     /* Peer understands IPv6 addresses? */
            hostname_address:1, /* Peer understands DNS addresses? */
            asconf_capable:1,   /* Does peer support ADDIP? */
            prsctp_capable:1,   /* Can peer do PR-SCTP? */
            auth_capable:1;     /* Is peer doing SCTP-AUTH? */

        __u32   adaptation_ind;  /* Adaptation Code point. */

        /* This mask is used to disable sending the ASCONF chunk
         * with specified parameter to peer.
         */
        __be16 addip_disabled_mask;

        struct sctp_inithdr_host i;
        int cookie_len;
        void *cookie;

        /* ADDIP Section 4.2 Upon reception of an ASCONF Chunk.
         * C1) ... "Peer-Serial-Number'. This value MUST be initialized to the
         * Initial TSN Value minus 1
         */
        __u32 addip_serial;

        /* SCTP-AUTH: We need to know pears random number, hmac list
         * and authenticated chunk list.  All that is part of the
         * cookie and these are just pointers to those locations
         */
        sctp_random_param_t *peer_random;
        sctp_chunks_param_t *peer_chunks;
        sctp_hmac_algo_param_t *peer_hmacs;
    } peer;

    /* State       : A state variable indicating what state the
     *         : association is in, i.e. COOKIE-WAIT,
     *         : COOKIE-ECHOED, ESTABLISHED, SHUTDOWN-PENDING,
     *         : SHUTDOWN-SENT, SHUTDOWN-RECEIVED, SHUTDOWN-ACK-SENT.
     *
     *      Note: No "CLOSED" state is illustrated since if a
     *      association is "CLOSED" its TCB SHOULD be removed.
     *
     *      In this implementation we DO have a CLOSED
     *      state which is used during initiation and shutdown.
     *
     *      State takes values from SCTP_STATE_*.
     */
    sctp_state_t state;

    /* The cookie life I award for any cookie.  */
    struct timeval cookie_life;

    /* Overall     : The overall association error count.
     * Error Count : [Clear this any time I get something.]
     */
    int overall_error_count;

    /* These are the association's initial, max, and min RTO values.
     * These values will be initialized by system defaults, but can
     * be modified via the SCTP_RTOINFO socket option.
     */
    unsigned long rto_initial;
    unsigned long rto_max;
    unsigned long rto_min;

    /* Maximum number of new data packets that can be sent in a burst.  */
    int max_burst;

    /* This is the max_retrans value for the association.  This value will
     * be initialized initialized from system defaults, but can be
     * modified by the SCTP_ASSOCINFO socket option.
     */
    int max_retrans;

    /* This is the partially failed retrans value for the transport
     * and will be initialized from the assocs value.  This can be
     * changed using the SCTP_PEER_ADDR_THLDS socket option
     */
    int pf_retrans;

    /* Maximum number of times the endpoint will retransmit INIT  */
    __u16 max_init_attempts;

    /* How many times have we resent an INIT? */
    __u16 init_retries;

    /* The largest timeout or RTO value to use in attempting an INIT */
    unsigned long max_init_timeo;

    /* Heartbeat interval: The endpoint sends out a Heartbeat chunk to
     * the destination address every heartbeat interval. This value
     * will be inherited by all new transports.
     */
    unsigned long hbinterval;

    /* This is the max_retrans value for new transports in the
     * association.
     */
    __u16 pathmaxrxt;

    /* Flag that path mtu update is pending */
    __u8   pmtu_pending;

    /* Association : The smallest PMTU discovered for all of the
     * PMTU        : peer's transport addresses.
     */
    __u32 pathmtu;

    /* Flags controlling Heartbeat, SACK delay, and Path MTU Discovery. */
    __u32 param_flags;

    /* SACK delay timeout */
    unsigned long sackdelay;
    __u32 sackfreq;


    unsigned long timeouts[SCTP_NUM_TIMEOUT_TYPES];
    struct timer_list timers[SCTP_NUM_TIMEOUT_TYPES];

    /* Transport to which SHUTDOWN chunk was last sent.  */
    struct sctp_transport *shutdown_last_sent_to;

    /* How many times have we resent a SHUTDOWN */
    int shutdown_retries;

    /* Transport to which INIT chunk was last sent.  */
    struct sctp_transport *init_last_sent_to;

    /* Next TSN    : The next TSN number to be assigned to a new
     *         : DATA chunk.  This is sent in the INIT or INIT
     *         : ACK chunk to the peer and incremented each
     *         : time a DATA chunk is assigned a TSN
     *         : (normally just prior to transmit or during
     *         : fragmentation).
     */
    __u32 next_tsn;

    /*
     * Last Rcvd   : This is the last TSN received in sequence.  This value
     * TSN         : is set initially by taking the peer's Initial TSN,
     *         : received in the INIT or INIT ACK chunk, and
     *         : subtracting one from it.
     *
     * Most of RFC 2960 refers to this as the Cumulative TSN Ack Point.
     */

    __u32 ctsn_ack_point;

    /* PR-SCTP Advanced.Peer.Ack.Point */
    __u32 adv_peer_ack_point;

    /* Highest TSN that is acknowledged by incoming SACKs. */
    __u32 highest_sacked;

    /* TSN marking the fast recovery exit point */
    __u32 fast_recovery_exit;

    /* Flag to track the current fast recovery state */
    __u8 fast_recovery;

    /* The number of unacknowledged data chunks.  Reported through
     * the SCTP_STATUS sockopt.
     */
    __u16 unack_data;

    /* The total number of data chunks that we've had to retransmit
     * as the result of a T3 timer expiration
     */
    __u32 rtx_data_chunks;

    /* This is the association's receive buffer space.  This value is used
     * to set a_rwnd field in an INIT or a SACK chunk.
     */
    __u32 rwnd;

    /* This is the last advertised value of rwnd over a SACK chunk. */
    __u32 a_rwnd;

    /* Number of bytes by which the rwnd has slopped.  The rwnd is allowed
     * to slop over a maximum of the association's frag_point.
     */
    __u32 rwnd_over;

    /* Keeps treack of rwnd pressure.  This happens when we have
     * a window, but not recevie buffer (i.e small packets).  This one
     * is releases slowly (1 PMTU at a time ).
     */
    __u32 rwnd_press;

    /* This is the sndbuf size in use for the association.
     * This corresponds to the sndbuf size for the association,
     * as specified in the sk->sndbuf.
     */
    int sndbuf_used;

    /* This is the amount of memory that this association has allocated
     * in the receive path at any given time.
     */
    atomic_t rmem_alloc;

    /* This is the wait queue head for send requests waiting on
     * the association sndbuf space.
     */
    wait_queue_head_t   wait;

    /* The message size at which SCTP fragmentation will occur. */
    __u32 frag_point;
    __u32 user_frag;

    /* Counter used to count INIT errors. */
    int init_err_counter;

    /* Count the number of INIT cycles (for doubling timeout). */
    int init_cycle;

    /* Default send parameters. */
    __u16 default_stream;
    __u16 default_flags;
    __u32 default_ppid;
    __u32 default_context;
    __u32 default_timetolive;

    /* Default receive parameters */
    __u32 default_rcv_context;

    /* This tracks outbound ssn for a given stream.  */
    struct sctp_ssnmap *ssnmap;

    /* All outbound chunks go through this structure.  */
    struct sctp_outq outqueue;

    /* A smart pipe that will handle reordering and fragmentation,
     * as well as handle passing events up to the ULP.
     */
    struct sctp_ulpq ulpq;

    /* Last TSN that caused an ECNE Chunk to be sent.  */
    __u32 last_ecne_tsn;

    /* Last TSN that caused a CWR Chunk to be sent.  */
    __u32 last_cwr_tsn;

    /* How many duplicated TSNs have we seen?  */
    int numduptsns;

    /* Number of seconds of idle time before an association is closed.
     * In the association context, this is really used as a boolean
     * since the real timeout is stored in the timeouts array
     */
    __u32 autoclose;

    /* These are to support
     * "SCTP Extensions for Dynamic Reconfiguration of IP Addresses
     *  and Enforcement of Flow and Message Limits"
     * <draft-ietf-tsvwg-addip-sctp-02.txt>
     * or "ADDIP" for short.
     */



    /* 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).
     *
     * [This is our one-and-only-one ASCONF in flight.  If we do
     * not have an ASCONF in flight, this is NULL.]
     */
    struct sctp_chunk *addip_last_asconf;

    /* ADDIP Section 5.2 Upon reception of an ASCONF Chunk.
     *
     * This is needed to implement itmes E1 - E4 of the updated
     * spec.  Here is the justification:
     *
     * Since the peer may bundle multiple ASCONF chunks toward us,
     * we now need the ability to cache multiple ACKs.  The section
     * describes in detail how they are cached and cleaned up.
     */
    struct list_head asconf_ack_list;

    /* These ASCONF chunks are waiting to be sent.
     *
     * These chunaks can't be pushed to outqueue until receiving
     * ASCONF_ACK for the previous ASCONF indicated by
     * addip_last_asconf, so as to guarantee that only one ASCONF
     * is in flight at any time.
     *
     * ADDIP Section 4.1.1 Congestion Control of ASCONF Chunks
     *
     * In defining the ASCONF Chunk transfer procedures, it is
     * essential that these transfers MUST NOT cause congestion
     * within the network.  To achieve this, we place these
     * restrictions on the transfer 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).
     *
     *
     * [I really think this is EXACTLY the sort of intelligence
     *  which already resides in sctp_outq.  Please move this
     *  queue and its supporting logic down there.  --piggy]
     */
    struct list_head addip_chunk_list;

    /* ADDIP Section 4.1 ASCONF Chunk Procedures
     *
     * A2) A serial number should be assigned to the Chunk. The
     * serial number SHOULD be a monotonically increasing
     * number. The serial number SHOULD be initialized at
     * the start of the association to the same value as the
     * Initial TSN and every time a new ASCONF chunk is created
     * it is incremented by one after assigning the serial number
     * to the newly created chunk.
     *
     * ADDIP
     * 3.1.1  Address/Stream Configuration Change Chunk (ASCONF)
     *
     * Serial Number : 32 bits (unsigned integer)
     *
     * This value represents a Serial Number for the ASCONF
     * Chunk. The valid range of Serial Number is from 0 to
     * 4294967295 (2^32 - 1).  Serial Numbers wrap back to 0
     * after reaching 4294967295.
     */
    __u32 addip_serial;
    union sctp_addr *asconf_addr_del_pending;
    int src_out_of_asoc_ok;
    struct sctp_transport *new_transport;

    /* SCTP AUTH: list of the endpoint shared keys.  These
     * keys are provided out of band by the user applicaton
     * and can't change during the lifetime of the association
     */
    struct list_head endpoint_shared_keys;

    /* SCTP AUTH:
     * The current generated assocaition shared key (secret)
     */
    struct sctp_auth_bytes *asoc_shared_key;

    /* SCTP AUTH: hmac id of the first peer requested algorithm
     * that we support.
     */
    __u16 default_hmac_id;

    __u16 active_key_id;

    __u8 need_ecne:1,   /* Need to send an ECNE Chunk? */
         temp:1;        /* Is it a temporary association? */
};


/* An eyecatcher for determining if we are really looking at an
 * association data structure.
 */
enum {
    SCTP_ASSOC_EYECATCHER = 0xa550c123,
};

/* Recover the outter association structure. */
static inline struct sctp_association *sctp_assoc(struct sctp_ep_common *base)
{
    struct sctp_association *asoc;

    asoc = container_of(base, struct sctp_association, base);
    return asoc;
}

/* These are function signatures for manipulating associations.  */


struct sctp_association *
sctp_association_new(const struct sctp_endpoint *, const struct sock *,
             sctp_scope_t scope, gfp_t gfp);
void sctp_association_free(struct sctp_association *);
void sctp_association_put(struct sctp_association *);
void sctp_association_hold(struct sctp_association *);

struct sctp_transport *sctp_assoc_choose_alter_transport(
    struct sctp_association *, struct sctp_transport *);
void sctp_assoc_update_retran_path(struct sctp_association *);
struct sctp_transport *sctp_assoc_lookup_paddr(const struct sctp_association *,
                      const union sctp_addr *);
int sctp_assoc_lookup_laddr(struct sctp_association *asoc,
                const union sctp_addr *laddr);
struct sctp_transport *sctp_assoc_add_peer(struct sctp_association *,
                     const union sctp_addr *address,
                     const gfp_t gfp,
                     const int peer_state);
void sctp_assoc_del_peer(struct sctp_association *asoc,
             const union sctp_addr *addr);
void sctp_assoc_rm_peer(struct sctp_association *asoc,
             struct sctp_transport *peer);
void sctp_assoc_control_transport(struct sctp_association *,
                  struct sctp_transport *,
                  sctp_transport_cmd_t, sctp_sn_error_t);
struct sctp_transport *sctp_assoc_lookup_tsn(struct sctp_association *, __u32);
struct sctp_transport *sctp_assoc_is_match(struct sctp_association *,
                       struct net *,
                       const union sctp_addr *,
                       const union sctp_addr *);
void sctp_assoc_migrate(struct sctp_association *, struct sock *);
void sctp_assoc_update(struct sctp_association *old,
               struct sctp_association *new);

__u32 sctp_association_get_next_tsn(struct sctp_association *);

void sctp_assoc_sync_pmtu(struct sock *, struct sctp_association *);
void sctp_assoc_rwnd_increase(struct sctp_association *, unsigned int);
void sctp_assoc_rwnd_decrease(struct sctp_association *, unsigned int);
void sctp_assoc_set_primary(struct sctp_association *,
                struct sctp_transport *);
void sctp_assoc_del_nonprimary_peers(struct sctp_association *,
                    struct sctp_transport *);
int sctp_assoc_set_bind_addr_from_ep(struct sctp_association *,
                     sctp_scope_t, gfp_t);
int sctp_assoc_set_bind_addr_from_cookie(struct sctp_association *,
                     struct sctp_cookie*,
                     gfp_t gfp);
int sctp_assoc_set_id(struct sctp_association *, gfp_t);
void sctp_assoc_clean_asconf_ack_cache(const struct sctp_association *asoc);
struct sctp_chunk *sctp_assoc_lookup_asconf_ack(
                    const struct sctp_association *asoc,
                    __be32 serial);
void sctp_asconf_queue_teardown(struct sctp_association *asoc);

int sctp_cmp_addr_exact(const union sctp_addr *ss1,
            const union sctp_addr *ss2);
struct sctp_chunk *sctp_get_ecne_prepend(struct sctp_association *asoc);

/* A convenience structure to parse out SCTP specific CMSGs. */
typedef struct sctp_cmsgs {
    struct sctp_initmsg *init;
    struct sctp_sndrcvinfo *info;
} sctp_cmsgs_t;

/* Structure for tracking memory objects */
typedef struct {
    char *label;
    atomic_t *counter;
} sctp_dbg_objcnt_entry_t;

#endif /* __sctp_structs_h__ */