/* 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.
   * Copyright (c) 2001 La Monte H.P. Yarroll
   *

   * This file is part of the SCTP kernel implementation

   *
   * This module provides the abstraction for an SCTP association.
   *

   * This SCTP implementation is free software;

   * you can redistribute it and/or modify it under the terms of
   * the GNU General Public License as published by
   * the Free Software Foundation; either version 2, or (at your option)
   * any later version.
   *

   * This SCTP implementation is distributed in the hope that it

   * will be useful, but WITHOUT ANY WARRANTY; without even the implied
   *                 ************************
   * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   * See the GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with GNU CC; see the file COPYING.  If not, write to
   * the Free Software Foundation, 59 Temple Place - Suite 330,
   * Boston, MA 02111-1307, USA.
   *
   * Please send any bug reports or fixes you make to the
   * email address(es):
   *    lksctp developers <lksctp-developers@lists.sourceforge.net>
   *
   * Or submit a bug report through the following website:
   *    http://www.sf.net/projects/lksctp
   *
   * Written or modified by:
   *    La Monte H.P. Yarroll <piggy@acm.org>
   *    Karl Knutson          <karl@athena.chicago.il.us>
   *    Jon Grimm             <jgrimm@us.ibm.com>
   *    Xingang Guo           <xingang.guo@intel.com>
   *    Hui Huang             <hui.huang@nokia.com>
   *    Sridhar Samudrala	    <sri@us.ibm.com>
   *    Daisy Chang	    <daisyc@us.ibm.com>
   *    Ryan Layer	    <rmlayer@us.ibm.com>
   *    Kevin Gao             <kevin.gao@intel.com>
   *
   * Any bugs reported given to us we will try to fix... any fixes shared will
   * be incorporated into the next SCTP release.
   */

  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

  #include <linux/types.h>
  #include <linux/fcntl.h>
  #include <linux/poll.h>
  #include <linux/init.h>

  
  #include <linux/slab.h>
  #include <linux/in.h>
  #include <net/ipv6.h>
  #include <net/sctp/sctp.h>
  #include <net/sctp/sm.h>
  
  /* Forward declarations for internal functions. */

  static void sctp_assoc_bh_rcv(struct work_struct *work);

  static void sctp_assoc_free_asconf_acks(struct sctp_association *asoc);

  static void sctp_assoc_free_asconf_queue(struct sctp_association *asoc);

  /* Keep track of the new idr low so that we don't re-use association id
   * numbers too fast.  It is protected by they idr spin lock is in the
   * range of 1 - INT_MAX.
   */
  static u32 idr_low = 1;

  
  /* 1st Level Abstractions. */
  
  /* Initialize a new association from provided memory. */
  static struct sctp_association *sctp_association_init(struct sctp_association *asoc,
  					  const struct sctp_endpoint *ep,
  					  const struct sock *sk,
  					  sctp_scope_t scope,

  					  gfp_t gfp)

  {
  	struct sctp_sock *sp;
  	int i;

  	sctp_paramhdr_t *p;
  	int err;

  
  	/* Retrieve the SCTP per socket area.  */
  	sp = sctp_sk((struct sock *)sk);

  	/* Discarding const is appropriate here.  */
  	asoc->ep = (struct sctp_endpoint *)ep;
  	sctp_endpoint_hold(asoc->ep);
  
  	/* Hold the sock.  */
  	asoc->base.sk = (struct sock *)sk;
  	sock_hold(asoc->base.sk);
  
  	/* Initialize the common base substructure.  */
  	asoc->base.type = SCTP_EP_TYPE_ASSOCIATION;
  
  	/* Initialize the object handling fields.  */
  	atomic_set(&asoc->base.refcnt, 1);
  	asoc->base.dead = 0;
  	asoc->base.malloced = 0;
  
  	/* Initialize the bind addr area.  */
  	sctp_bind_addr_init(&asoc->base.bind_addr, ep->base.bind_addr.port);

  
  	asoc->state = SCTP_STATE_CLOSED;
  
  	/* Set these values from the socket values, a conversion between
  	 * millsecons to seconds/microseconds must also be done.
  	 */
  	asoc->cookie_life.tv_sec = sp->assocparams.sasoc_cookie_life / 1000;
  	asoc->cookie_life.tv_usec = (sp->assocparams.sasoc_cookie_life % 1000)
  					* 1000;

  	asoc->frag_point = 0;

  	asoc->user_frag = sp->user_frag;

  
  	/* Set the association max_retrans and RTO values from the
  	 * socket values.
  	 */
  	asoc->max_retrans = sp->assocparams.sasoc_asocmaxrxt;
  	asoc->rto_initial = msecs_to_jiffies(sp->rtoinfo.srto_initial);
  	asoc->rto_max = msecs_to_jiffies(sp->rtoinfo.srto_max);
  	asoc->rto_min = msecs_to_jiffies(sp->rtoinfo.srto_min);
  
  	asoc->overall_error_count = 0;

  	/* Initialize the association's heartbeat interval based on the
  	 * sock configured value.
  	 */
  	asoc->hbinterval = msecs_to_jiffies(sp->hbinterval);
  
  	/* Initialize path max retrans value. */
  	asoc->pathmaxrxt = sp->pathmaxrxt;
  
  	/* Initialize default path MTU. */
  	asoc->pathmtu = sp->pathmtu;
  
  	/* Set association default SACK delay */
  	asoc->sackdelay = msecs_to_jiffies(sp->sackdelay);

  	asoc->sackfreq = sp->sackfreq;

  
  	/* Set the association default flags controlling
  	 * Heartbeat, SACK delay, and Path MTU Discovery.
  	 */
  	asoc->param_flags = sp->param_flags;

  	/* Initialize the maximum mumber of new data packets that can be sent
  	 * in a burst.
  	 */

  	asoc->max_burst = sp->max_burst;

  	/* initialize association timers */
  	asoc->timeouts[SCTP_EVENT_TIMEOUT_NONE] = 0;
  	asoc->timeouts[SCTP_EVENT_TIMEOUT_T1_COOKIE] = asoc->rto_initial;
  	asoc->timeouts[SCTP_EVENT_TIMEOUT_T1_INIT] = asoc->rto_initial;
  	asoc->timeouts[SCTP_EVENT_TIMEOUT_T2_SHUTDOWN] = asoc->rto_initial;
  	asoc->timeouts[SCTP_EVENT_TIMEOUT_T3_RTX] = 0;
  	asoc->timeouts[SCTP_EVENT_TIMEOUT_T4_RTO] = 0;
  
  	/* sctpimpguide Section 2.12.2
  	 * If the 'T5-shutdown-guard' timer is used, it SHOULD be set to the
  	 * recommended value of 5 times 'RTO.Max'.
  	 */

  	asoc->timeouts[SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD]

  		= 5 * asoc->rto_max;
  
  	asoc->timeouts[SCTP_EVENT_TIMEOUT_HEARTBEAT] = 0;

  	asoc->timeouts[SCTP_EVENT_TIMEOUT_SACK] = asoc->sackdelay;

  	asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE] =

  		min_t(unsigned long, sp->autoclose, sctp_max_autoclose) * HZ;

  	/* Initializes the timers */

  	for (i = SCTP_EVENT_TIMEOUT_NONE; i < SCTP_NUM_TIMEOUT_TYPES; ++i)
  		setup_timer(&asoc->timers[i], sctp_timer_events[i],
  				(unsigned long)asoc);

  
  	/* Pull default initialization values from the sock options.
  	 * Note: This assumes that the values have already been
  	 * validated in the sock.
  	 */
  	asoc->c.sinit_max_instreams = sp->initmsg.sinit_max_instreams;
  	asoc->c.sinit_num_ostreams  = sp->initmsg.sinit_num_ostreams;
  	asoc->max_init_attempts	= sp->initmsg.sinit_max_attempts;
  
  	asoc->max_init_timeo =
  		 msecs_to_jiffies(sp->initmsg.sinit_max_init_timeo);
  
  	/* Allocate storage for the ssnmap after the inbound and outbound
  	 * streams have been negotiated during Init.
  	 */
  	asoc->ssnmap = NULL;
  
  	/* Set the local window size for receive.
  	 * This is also the rcvbuf space per association.
  	 * RFC 6 - A SCTP receiver MUST be able to receive a minimum of
  	 * 1500 bytes in one SCTP packet.
  	 */

  	if ((sk->sk_rcvbuf/2) < SCTP_DEFAULT_MINWINDOW)

  		asoc->rwnd = SCTP_DEFAULT_MINWINDOW;
  	else

  		asoc->rwnd = sk->sk_rcvbuf/2;

  
  	asoc->a_rwnd = asoc->rwnd;
  
  	asoc->rwnd_over = 0;

  	asoc->rwnd_press = 0;

  
  	/* Use my own max window until I learn something better.  */
  	asoc->peer.rwnd = SCTP_DEFAULT_MAXWINDOW;
  
  	/* Set the sndbuf size for transmit.  */
  	asoc->sndbuf_used = 0;

  	/* Initialize the receive memory counter */
  	atomic_set(&asoc->rmem_alloc, 0);

  	init_waitqueue_head(&asoc->wait);
  
  	asoc->c.my_vtag = sctp_generate_tag(ep);
  	asoc->peer.i.init_tag = 0;     /* INIT needs a vtag of 0. */
  	asoc->c.peer_vtag = 0;
  	asoc->c.my_ttag   = 0;
  	asoc->c.peer_ttag = 0;
  	asoc->c.my_port = ep->base.bind_addr.port;
  
  	asoc->c.initial_tsn = sctp_generate_tsn(ep);
  
  	asoc->next_tsn = asoc->c.initial_tsn;
  
  	asoc->ctsn_ack_point = asoc->next_tsn - 1;
  	asoc->adv_peer_ack_point = asoc->ctsn_ack_point;
  	asoc->highest_sacked = asoc->ctsn_ack_point;
  	asoc->last_cwr_tsn = asoc->ctsn_ack_point;
  	asoc->unack_data = 0;

  	/* ADDIP Section 4.1 Asconf Chunk Procedures
  	 *
  	 * When an endpoint has an ASCONF signaled change to be sent to the
  	 * remote endpoint it should do the following:
  	 * ...
  	 * A2) a serial number should be assigned to the chunk. The serial
  	 * number SHOULD be a monotonically increasing number. The serial
  	 * numbers SHOULD be initialized at the start of the
  	 * association to the same value as the initial TSN.
  	 */
  	asoc->addip_serial = asoc->c.initial_tsn;

  	INIT_LIST_HEAD(&asoc->addip_chunk_list);

  	INIT_LIST_HEAD(&asoc->asconf_ack_list);

  
  	/* Make an empty list of remote transport addresses.  */
  	INIT_LIST_HEAD(&asoc->peer.transport_addr_list);

  	asoc->peer.transport_count = 0;

  
  	/* RFC 2960 5.1 Normal Establishment of an Association
  	 *
  	 * After the reception of the first data chunk in an
  	 * association the endpoint must immediately respond with a
  	 * sack to acknowledge the data chunk.  Subsequent
  	 * acknowledgements should be done as described in Section
  	 * 6.2.
  	 *
  	 * [We implement this by telling a new association that it
  	 * already received one packet.]
  	 */
  	asoc->peer.sack_needed = 1;

  	asoc->peer.sack_cnt = 0;

  	/* Assume that the peer will tell us if he recognizes ASCONF
  	 * as part of INIT exchange.
  	 * The sctp_addip_noauth option is there for backward compatibilty
  	 * and will revert old behavior.

  	 */

  	asoc->peer.asconf_capable = 0;

  	if (sctp_addip_noauth)
  		asoc->peer.asconf_capable = 1;

  	asoc->asconf_addr_del_pending = NULL;
  	asoc->src_out_of_asoc_ok = 0;

  	asoc->new_transport = NULL;

  
  	/* Create an input queue.  */
  	sctp_inq_init(&asoc->base.inqueue);

  	sctp_inq_set_th_handler(&asoc->base.inqueue, sctp_assoc_bh_rcv);

  
  	/* Create an output queue.  */
  	sctp_outq_init(asoc, &asoc->outqueue);
  
  	if (!sctp_ulpq_init(&asoc->ulpq, asoc))
  		goto fail_init;

  	memset(&asoc->peer.tsn_map, 0, sizeof(struct sctp_tsnmap));

  
  	asoc->need_ecne = 0;
  
  	asoc->assoc_id = 0;
  
  	/* Assume that peer would support both address types unless we are
  	 * told otherwise.
  	 */
  	asoc->peer.ipv4_address = 1;

  	if (asoc->base.sk->sk_family == PF_INET6)
  		asoc->peer.ipv6_address = 1;

  	INIT_LIST_HEAD(&asoc->asocs);
  
  	asoc->autoclose = sp->autoclose;
  
  	asoc->default_stream = sp->default_stream;
  	asoc->default_ppid = sp->default_ppid;
  	asoc->default_flags = sp->default_flags;
  	asoc->default_context = sp->default_context;
  	asoc->default_timetolive = sp->default_timetolive;

  	asoc->default_rcv_context = sp->default_rcv_context;

  	/* AUTH related initializations */
  	INIT_LIST_HEAD(&asoc->endpoint_shared_keys);
  	err = sctp_auth_asoc_copy_shkeys(ep, asoc, gfp);
  	if (err)
  		goto fail_init;
  
  	asoc->active_key_id = ep->active_key_id;
  	asoc->asoc_shared_key = NULL;
  
  	asoc->default_hmac_id = 0;
  	/* Save the hmacs and chunks list into this association */
  	if (ep->auth_hmacs_list)
  		memcpy(asoc->c.auth_hmacs, ep->auth_hmacs_list,
  			ntohs(ep->auth_hmacs_list->param_hdr.length));
  	if (ep->auth_chunk_list)
  		memcpy(asoc->c.auth_chunks, ep->auth_chunk_list,
  			ntohs(ep->auth_chunk_list->param_hdr.length));
  
  	/* Get the AUTH random number for this association */
  	p = (sctp_paramhdr_t *)asoc->c.auth_random;
  	p->type = SCTP_PARAM_RANDOM;
  	p->length = htons(sizeof(sctp_paramhdr_t) + SCTP_AUTH_RANDOM_LENGTH);
  	get_random_bytes(p+1, SCTP_AUTH_RANDOM_LENGTH);

  	return asoc;
  
  fail_init:
  	sctp_endpoint_put(asoc->ep);
  	sock_put(asoc->base.sk);
  	return NULL;
  }
  
  /* Allocate and initialize a new association */
  struct sctp_association *sctp_association_new(const struct sctp_endpoint *ep,
  					 const struct sock *sk,

  					 sctp_scope_t scope,

  					 gfp_t gfp)

  {
  	struct sctp_association *asoc;
  
  	asoc = t_new(struct sctp_association, gfp);
  	if (!asoc)
  		goto fail;
  
  	if (!sctp_association_init(asoc, ep, sk, scope, gfp))
  		goto fail_init;
  
  	asoc->base.malloced = 1;
  	SCTP_DBG_OBJCNT_INC(assoc);

  	SCTP_DEBUG_PRINTK("Created asoc %p
  ", asoc);

  
  	return asoc;
  
  fail_init:
  	kfree(asoc);
  fail:
  	return NULL;
  }
  
  /* Free this association if possible.  There may still be users, so
   * the actual deallocation may be delayed.
   */
  void sctp_association_free(struct sctp_association *asoc)
  {
  	struct sock *sk = asoc->base.sk;
  	struct sctp_transport *transport;
  	struct list_head *pos, *temp;
  	int i;

  	/* Only real associations count against the endpoint, so
  	 * don't bother for if this is a temporary association.
  	 */
  	if (!asoc->temp) {
  		list_del(&asoc->asocs);
  
  		/* Decrement the backlog value for a TCP-style listening
  		 * socket.
  		 */
  		if (sctp_style(sk, TCP) && sctp_sstate(sk, LISTENING))
  			sk->sk_ack_backlog--;
  	}

  
  	/* Mark as dead, so other users can know this structure is
  	 * going away.
  	 */
  	asoc->base.dead = 1;
  
  	/* Dispose of any data lying around in the outqueue. */
  	sctp_outq_free(&asoc->outqueue);
  
  	/* Dispose of any pending messages for the upper layer. */
  	sctp_ulpq_free(&asoc->ulpq);
  
  	/* Dispose of any pending chunks on the inqueue. */
  	sctp_inq_free(&asoc->base.inqueue);

  	sctp_tsnmap_free(&asoc->peer.tsn_map);

  	/* Free ssnmap storage. */
  	sctp_ssnmap_free(asoc->ssnmap);
  
  	/* Clean up the bound address list. */
  	sctp_bind_addr_free(&asoc->base.bind_addr);
  
  	/* Do we need to go through all of our timers and
  	 * delete them?   To be safe we will try to delete all, but we
  	 * should be able to go through and make a guess based
  	 * on our state.
  	 */
  	for (i = SCTP_EVENT_TIMEOUT_NONE; i < SCTP_NUM_TIMEOUT_TYPES; ++i) {
  		if (timer_pending(&asoc->timers[i]) &&
  		    del_timer(&asoc->timers[i]))
  			sctp_association_put(asoc);
  	}
  
  	/* Free peer's cached cookie. */

  	kfree(asoc->peer.cookie);

  	kfree(asoc->peer.peer_random);
  	kfree(asoc->peer.peer_chunks);
  	kfree(asoc->peer.peer_hmacs);

  
  	/* Release the transport structures. */
  	list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
  		transport = list_entry(pos, struct sctp_transport, transports);
  		list_del(pos);
  		sctp_transport_free(transport);
  	}

  	asoc->peer.transport_count = 0;

  	sctp_asconf_queue_teardown(asoc);

  	/* Free pending address space being deleted */
  	if (asoc->asconf_addr_del_pending != NULL)
  		kfree(asoc->asconf_addr_del_pending);

  	/* AUTH - Free the endpoint shared keys */
  	sctp_auth_destroy_keys(&asoc->endpoint_shared_keys);
  
  	/* AUTH - Free the association shared key */
  	sctp_auth_key_put(asoc->asoc_shared_key);

  	sctp_association_put(asoc);
  }
  
  /* Cleanup and free up an association. */
  static void sctp_association_destroy(struct sctp_association *asoc)
  {
  	SCTP_ASSERT(asoc->base.dead, "Assoc is not dead", return);
  
  	sctp_endpoint_put(asoc->ep);
  	sock_put(asoc->base.sk);
  
  	if (asoc->assoc_id != 0) {
  		spin_lock_bh(&sctp_assocs_id_lock);
  		idr_remove(&sctp_assocs_id, asoc->assoc_id);
  		spin_unlock_bh(&sctp_assocs_id_lock);
  	}

  	WARN_ON(atomic_read(&asoc->rmem_alloc));

  	if (asoc->base.malloced) {
  		kfree(asoc);
  		SCTP_DBG_OBJCNT_DEC(assoc);
  	}
  }
  
  /* Change the primary destination address for the peer. */
  void sctp_assoc_set_primary(struct sctp_association *asoc,
  			    struct sctp_transport *transport)
  {

  	int changeover = 0;
  
  	/* it's a changeover only if we already have a primary path
  	 * that we are changing
  	 */
  	if (asoc->peer.primary_path != NULL &&
  	    asoc->peer.primary_path != transport)
  		changeover = 1 ;

  	asoc->peer.primary_path = transport;
  
  	/* Set a default msg_name for events. */
  	memcpy(&asoc->peer.primary_addr, &transport->ipaddr,
  	       sizeof(union sctp_addr));
  
  	/* If the primary path is changing, assume that the
  	 * user wants to use this new path.
  	 */

  	if ((transport->state == SCTP_ACTIVE) ||
  	    (transport->state == SCTP_UNKNOWN))

  		asoc->peer.active_path = transport;
  
  	/*
  	 * SFR-CACC algorithm:
  	 * Upon the receipt of a request to change the primary
  	 * destination address, on the data structure for the new
  	 * primary destination, the sender MUST do the following:
  	 *
  	 * 1) If CHANGEOVER_ACTIVE is set, then there was a switch
  	 * to this destination address earlier. The sender MUST set
  	 * CYCLING_CHANGEOVER to indicate that this switch is a
  	 * double switch to the same destination address.

  	 *
  	 * Really, only bother is we have data queued or outstanding on
  	 * the association.

  	 */

  	if (!asoc->outqueue.outstanding_bytes && !asoc->outqueue.out_qlen)
  		return;

  	if (transport->cacc.changeover_active)

  		transport->cacc.cycling_changeover = changeover;

  
  	/* 2) The sender MUST set CHANGEOVER_ACTIVE to indicate that
  	 * a changeover has occurred.
  	 */

  	transport->cacc.changeover_active = changeover;

  
  	/* 3) The sender MUST store the next TSN to be sent in
  	 * next_tsn_at_change.
  	 */
  	transport->cacc.next_tsn_at_change = asoc->next_tsn;
  }

  /* Remove a transport from an association.  */
  void sctp_assoc_rm_peer(struct sctp_association *asoc,
  			struct sctp_transport *peer)
  {
  	struct list_head	*pos;
  	struct sctp_transport	*transport;
  
  	SCTP_DEBUG_PRINTK_IPADDR("sctp_assoc_rm_peer:association %p addr: ",
  				 " port: %d
  ",
  				 asoc,
  				 (&peer->ipaddr),

  				 ntohs(peer->ipaddr.v4.sin_port));

  
  	/* If we are to remove the current retran_path, update it
  	 * to the next peer before removing this peer from the list.
  	 */
  	if (asoc->peer.retran_path == peer)
  		sctp_assoc_update_retran_path(asoc);
  
  	/* Remove this peer from the list. */
  	list_del(&peer->transports);
  
  	/* Get the first transport of asoc. */
  	pos = asoc->peer.transport_addr_list.next;
  	transport = list_entry(pos, struct sctp_transport, transports);
  
  	/* Update any entries that match the peer to be deleted. */
  	if (asoc->peer.primary_path == peer)
  		sctp_assoc_set_primary(asoc, transport);
  	if (asoc->peer.active_path == peer)
  		asoc->peer.active_path = transport;

  	if (asoc->peer.retran_path == peer)
  		asoc->peer.retran_path = transport;

  	if (asoc->peer.last_data_from == peer)
  		asoc->peer.last_data_from = transport;
  
  	/* If we remove the transport an INIT was last sent to, set it to
  	 * NULL. Combined with the update of the retran path above, this
  	 * will cause the next INIT to be sent to the next available
  	 * transport, maintaining the cycle.
  	 */
  	if (asoc->init_last_sent_to == peer)
  		asoc->init_last_sent_to = NULL;

  	/* If we remove the transport an SHUTDOWN was last sent to, set it
  	 * to NULL. Combined with the update of the retran path above, this
  	 * will cause the next SHUTDOWN to be sent to the next available
  	 * transport, maintaining the cycle.
  	 */
  	if (asoc->shutdown_last_sent_to == peer)
  		asoc->shutdown_last_sent_to = NULL;

  	/* If we remove the transport an ASCONF was last sent to, set it to
  	 * NULL.
  	 */
  	if (asoc->addip_last_asconf &&
  	    asoc->addip_last_asconf->transport == peer)
  		asoc->addip_last_asconf->transport = NULL;

  	/* If we have something on the transmitted list, we have to
  	 * save it off.  The best place is the active path.
  	 */
  	if (!list_empty(&peer->transmitted)) {
  		struct sctp_transport *active = asoc->peer.active_path;
  		struct sctp_chunk *ch;
  
  		/* Reset the transport of each chunk on this list */
  		list_for_each_entry(ch, &peer->transmitted,
  					transmitted_list) {
  			ch->transport = NULL;
  			ch->rtt_in_progress = 0;
  		}
  
  		list_splice_tail_init(&peer->transmitted,
  					&active->transmitted);
  
  		/* Start a T3 timer here in case it wasn't running so
  		 * that these migrated packets have a chance to get
  		 * retrnasmitted.
  		 */
  		if (!timer_pending(&active->T3_rtx_timer))
  			if (!mod_timer(&active->T3_rtx_timer,
  					jiffies + active->rto))
  				sctp_transport_hold(active);
  	}

  	asoc->peer.transport_count--;
  
  	sctp_transport_free(peer);
  }

  /* Add a transport address to an association.  */
  struct sctp_transport *sctp_assoc_add_peer(struct sctp_association *asoc,
  					   const union sctp_addr *addr,

  					   const gfp_t gfp,

  					   const int peer_state)

  {
  	struct sctp_transport *peer;
  	struct sctp_sock *sp;
  	unsigned short port;
  
  	sp = sctp_sk(asoc->base.sk);
  
  	/* AF_INET and AF_INET6 share common port field. */

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

  	SCTP_DEBUG_PRINTK_IPADDR("sctp_assoc_add_peer:association %p addr: ",

  				 " port: %d state:%d
  ",

  				 asoc,
  				 addr,

  				 port,

  				 peer_state);

  	/* Set the port if it has not been set yet.  */
  	if (0 == asoc->peer.port)
  		asoc->peer.port = port;
  
  	/* Check to see if this is a duplicate. */
  	peer = sctp_assoc_lookup_paddr(asoc, addr);

  	if (peer) {

  		/* An UNKNOWN state is only set on transports added by
  		 * user in sctp_connectx() call.  Such transports should be
  		 * considered CONFIRMED per RFC 4960, Section 5.4.
  		 */

  		if (peer->state == SCTP_UNKNOWN) {

  			peer->state = SCTP_ACTIVE;

  		}

  		return peer;

  	}

  
  	peer = sctp_transport_new(addr, gfp);
  	if (!peer)
  		return NULL;
  
  	sctp_transport_set_owner(peer, asoc);

  	/* Initialize the peer's heartbeat interval based on the
  	 * association configured value.
  	 */
  	peer->hbinterval = asoc->hbinterval;
  
  	/* Set the path max_retrans.  */
  	peer->pathmaxrxt = asoc->pathmaxrxt;
  
  	/* Initialize the peer's SACK delay timeout based on the
  	 * association configured value.
  	 */
  	peer->sackdelay = asoc->sackdelay;

  	peer->sackfreq = asoc->sackfreq;

  
  	/* Enable/disable heartbeat, SACK delay, and path MTU discovery
  	 * based on association setting.
  	 */
  	peer->param_flags = asoc->param_flags;

  	sctp_transport_route(peer, NULL, sp);

  	/* Initialize the pmtu of the transport. */

  	if (peer->param_flags & SPP_PMTUD_DISABLE) {
  		if (asoc->pathmtu)
  			peer->pathmtu = asoc->pathmtu;
  		else
  			peer->pathmtu = SCTP_DEFAULT_MAXSEGMENT;
  	}

  
  	/* If this is the first transport addr on this association,
  	 * initialize the association PMTU to the peer's PMTU.
  	 * If not and the current association PMTU is higher than the new
  	 * peer's PMTU, reset the association PMTU to the new peer's PMTU.
  	 */

  	if (asoc->pathmtu)
  		asoc->pathmtu = min_t(int, peer->pathmtu, asoc->pathmtu);

  	else

  		asoc->pathmtu = peer->pathmtu;

  
  	SCTP_DEBUG_PRINTK("sctp_assoc_add_peer:association %p PMTU set to "

  			  "%d
  ", asoc, asoc->pathmtu);

  	peer->pmtu_pending = 0;

  	asoc->frag_point = sctp_frag_point(asoc, asoc->pathmtu);

  
  	/* The asoc->peer.port might not be meaningful yet, but
  	 * initialize the packet structure anyway.
  	 */
  	sctp_packet_init(&peer->packet, peer, asoc->base.bind_addr.port,
  			 asoc->peer.port);
  
  	/* 7.2.1 Slow-Start
  	 *
  	 * o The initial cwnd before DATA transmission or after a sufficiently
  	 *   long idle period MUST be set to
  	 *      min(4*MTU, max(2*MTU, 4380 bytes))
  	 *
  	 * o The initial value of ssthresh MAY be arbitrarily high
  	 *   (for example, implementations MAY use the size of the
  	 *   receiver advertised window).
  	 */

  	peer->cwnd = min(4*asoc->pathmtu, max_t(__u32, 2*asoc->pathmtu, 4380));

  
  	/* At this point, we may not have the receiver's advertised window,
  	 * so initialize ssthresh to the default value and it will be set
  	 * later when we process the INIT.
  	 */
  	peer->ssthresh = SCTP_DEFAULT_MAXWINDOW;
  
  	peer->partial_bytes_acked = 0;
  	peer->flight_size = 0;

  	peer->burst_limited = 0;

  	/* Set the transport's RTO.initial value */
  	peer->rto = asoc->rto_initial;

  	/* Set the peer's active state. */
  	peer->state = peer_state;

  	/* Attach the remote transport to our asoc.  */
  	list_add_tail(&peer->transports, &asoc->peer.transport_addr_list);

  	asoc->peer.transport_count++;

  
  	/* If we do not yet have a primary path, set one.  */
  	if (!asoc->peer.primary_path) {
  		sctp_assoc_set_primary(asoc, peer);
  		asoc->peer.retran_path = peer;
  	}

  	if (asoc->peer.active_path == asoc->peer.retran_path &&
  	    peer->state != SCTP_UNCONFIRMED) {

  		asoc->peer.retran_path = peer;

  	}

  
  	return peer;
  }
  
  /* Delete a transport address from an association.  */
  void sctp_assoc_del_peer(struct sctp_association *asoc,
  			 const union sctp_addr *addr)
  {
  	struct list_head	*pos;
  	struct list_head	*temp;

  	struct sctp_transport	*transport;
  
  	list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
  		transport = list_entry(pos, struct sctp_transport, transports);
  		if (sctp_cmp_addr_exact(addr, &transport->ipaddr)) {

  			/* Do book keeping for removing the peer and free it. */
  			sctp_assoc_rm_peer(asoc, transport);

  			break;
  		}
  	}

  }
  
  /* Lookup a transport by address. */
  struct sctp_transport *sctp_assoc_lookup_paddr(
  					const struct sctp_association *asoc,
  					const union sctp_addr *address)
  {
  	struct sctp_transport *t;

  
  	/* Cycle through all transports searching for a peer address. */

  	list_for_each_entry(t, &asoc->peer.transport_addr_list,
  			transports) {

  		if (sctp_cmp_addr_exact(address, &t->ipaddr))
  			return t;
  	}
  
  	return NULL;
  }

  /* Remove all transports except a give one */
  void sctp_assoc_del_nonprimary_peers(struct sctp_association *asoc,
  				     struct sctp_transport *primary)
  {
  	struct sctp_transport	*temp;
  	struct sctp_transport	*t;
  
  	list_for_each_entry_safe(t, temp, &asoc->peer.transport_addr_list,
  				 transports) {
  		/* if the current transport is not the primary one, delete it */
  		if (t != primary)
  			sctp_assoc_rm_peer(asoc, t);
  	}

  }

  /* Engage in transport control operations.
   * Mark the transport up or down and send a notification to the user.
   * Select and update the new active and retran paths.
   */
  void sctp_assoc_control_transport(struct sctp_association *asoc,
  				  struct sctp_transport *transport,
  				  sctp_transport_cmd_t command,
  				  sctp_sn_error_t error)
  {
  	struct sctp_transport *t = NULL;
  	struct sctp_transport *first;
  	struct sctp_transport *second;
  	struct sctp_ulpevent *event;

  	struct sockaddr_storage addr;

  	int spc_state = 0;
  
  	/* Record the transition on the transport.  */
  	switch (command) {
  	case SCTP_TRANSPORT_UP:

  		/* If we are moving from UNCONFIRMED state due
  		 * to heartbeat success, report the SCTP_ADDR_CONFIRMED
  		 * state to the user, otherwise report SCTP_ADDR_AVAILABLE.
  		 */
  		if (SCTP_UNCONFIRMED == transport->state &&
  		    SCTP_HEARTBEAT_SUCCESS == error)
  			spc_state = SCTP_ADDR_CONFIRMED;
  		else
  			spc_state = SCTP_ADDR_AVAILABLE;

  		transport->state = SCTP_ACTIVE;

  		break;
  
  	case SCTP_TRANSPORT_DOWN:

  		/* If the transport was never confirmed, do not transition it
  		 * to inactive state.  Also, release the cached route since
  		 * there may be a better route next time.

  		 */
  		if (transport->state != SCTP_UNCONFIRMED)
  			transport->state = SCTP_INACTIVE;

  		else {
  			dst_release(transport->dst);
  			transport->dst = NULL;
  		}

  		spc_state = SCTP_ADDR_UNREACHABLE;
  		break;
  
  	default:
  		return;

  	}

  
  	/* Generate and send a SCTP_PEER_ADDR_CHANGE notification to the
  	 * user.
  	 */

  	memset(&addr, 0, sizeof(struct sockaddr_storage));

  	memcpy(&addr, &transport->ipaddr, transport->af_specific->sockaddr_len);

  	event = sctp_ulpevent_make_peer_addr_change(asoc, &addr,

  				0, spc_state, error, GFP_ATOMIC);
  	if (event)
  		sctp_ulpq_tail_event(&asoc->ulpq, event);
  
  	/* Select new active and retran paths. */
  
  	/* Look for the two most recently used active transports.
  	 *
  	 * This code produces the wrong ordering whenever jiffies
  	 * rolls over, but we still get usable transports, so we don't
  	 * worry about it.
  	 */
  	first = NULL; second = NULL;

  	list_for_each_entry(t, &asoc->peer.transport_addr_list,
  			transports) {

  		if ((t->state == SCTP_INACTIVE) ||
  		    (t->state == SCTP_UNCONFIRMED))

  			continue;
  		if (!first || t->last_time_heard > first->last_time_heard) {
  			second = first;
  			first = t;
  		}
  		if (!second || t->last_time_heard > second->last_time_heard)
  			second = t;
  	}
  
  	/* RFC 2960 6.4 Multi-Homed SCTP Endpoints
  	 *
  	 * By default, an endpoint should always transmit to the
  	 * primary path, unless the SCTP user explicitly specifies the
  	 * destination transport address (and possibly source
  	 * transport address) to use.
  	 *
  	 * [If the primary is active but not most recent, bump the most
  	 * recently used transport.]
  	 */

  	if (((asoc->peer.primary_path->state == SCTP_ACTIVE) ||
  	     (asoc->peer.primary_path->state == SCTP_UNKNOWN)) &&

  	    first != asoc->peer.primary_path) {
  		second = first;
  		first = asoc->peer.primary_path;
  	}
  
  	/* If we failed to find a usable transport, just camp on the
  	 * primary, even if it is inactive.
  	 */
  	if (!first) {
  		first = asoc->peer.primary_path;
  		second = asoc->peer.primary_path;
  	}
  
  	/* Set the active and retran transports.  */
  	asoc->peer.active_path = first;
  	asoc->peer.retran_path = second;
  }
  
  /* Hold a reference to an association. */
  void sctp_association_hold(struct sctp_association *asoc)
  {
  	atomic_inc(&asoc->base.refcnt);
  }
  
  /* Release a reference to an association and cleanup
   * if there are no more references.
   */
  void sctp_association_put(struct sctp_association *asoc)
  {
  	if (atomic_dec_and_test(&asoc->base.refcnt))
  		sctp_association_destroy(asoc);
  }
  
  /* Allocate the next TSN, Transmission Sequence Number, for the given
   * association.
   */
  __u32 sctp_association_get_next_tsn(struct sctp_association *asoc)
  {
  	/* From Section 1.6 Serial Number Arithmetic:
  	 * Transmission Sequence Numbers wrap around when they reach
  	 * 2**32 - 1.  That is, the next TSN a DATA chunk MUST use
  	 * after transmitting TSN = 2*32 - 1 is TSN = 0.
  	 */
  	__u32 retval = asoc->next_tsn;
  	asoc->next_tsn++;
  	asoc->unack_data++;
  
  	return retval;
  }
  
  /* Compare two addresses to see if they match.  Wildcard addresses
   * only match themselves.
   */
  int sctp_cmp_addr_exact(const union sctp_addr *ss1,
  			const union sctp_addr *ss2)
  {
  	struct sctp_af *af;
  
  	af = sctp_get_af_specific(ss1->sa.sa_family);
  	if (unlikely(!af))
  		return 0;
  
  	return af->cmp_addr(ss1, ss2);
  }
  
  /* Return an ecne chunk to get prepended to a packet.
   * Note:  We are sly and return a shared, prealloced chunk.  FIXME:
   * No we don't, but we could/should.
   */
  struct sctp_chunk *sctp_get_ecne_prepend(struct sctp_association *asoc)
  {
  	struct sctp_chunk *chunk;
  
  	/* Send ECNE if needed.
  	 * Not being able to allocate a chunk here is not deadly.
  	 */
  	if (asoc->need_ecne)
  		chunk = sctp_make_ecne(asoc, asoc->last_ecne_tsn);
  	else
  		chunk = NULL;
  
  	return chunk;
  }
  
  /*
   * Find which transport this TSN was sent on.
   */
  struct sctp_transport *sctp_assoc_lookup_tsn(struct sctp_association *asoc,
  					     __u32 tsn)
  {
  	struct sctp_transport *active;
  	struct sctp_transport *match;

  	struct sctp_transport *transport;
  	struct sctp_chunk *chunk;

  	__be32 key = htonl(tsn);

  
  	match = NULL;
  
  	/*
  	 * FIXME: In general, find a more efficient data structure for
  	 * searching.
  	 */
  
  	/*
  	 * The general strategy is to search each transport's transmitted
  	 * list.   Return which transport this TSN lives on.
  	 *
  	 * Let's be hopeful and check the active_path first.
  	 * Another optimization would be to know if there is only one
  	 * outbound path and not have to look for the TSN at all.
  	 *
  	 */
  
  	active = asoc->peer.active_path;

  	list_for_each_entry(chunk, &active->transmitted,
  			transmitted_list) {

  
  		if (key == chunk->subh.data_hdr->tsn) {
  			match = active;
  			goto out;
  		}
  	}
  
  	/* If not found, go search all the other transports. */

  	list_for_each_entry(transport, &asoc->peer.transport_addr_list,
  			transports) {

  
  		if (transport == active)
  			break;

  		list_for_each_entry(chunk, &transport->transmitted,
  				transmitted_list) {

  			if (key == chunk->subh.data_hdr->tsn) {
  				match = transport;
  				goto out;
  			}
  		}
  	}
  out:
  	return match;
  }
  
  /* Is this the association we are looking for? */
  struct sctp_transport *sctp_assoc_is_match(struct sctp_association *asoc,
  					   const union sctp_addr *laddr,
  					   const union sctp_addr *paddr)
  {
  	struct sctp_transport *transport;

  	if ((htons(asoc->base.bind_addr.port) == laddr->v4.sin_port) &&
  	    (htons(asoc->peer.port) == paddr->v4.sin_port)) {

  		transport = sctp_assoc_lookup_paddr(asoc, paddr);
  		if (!transport)
  			goto out;
  
  		if (sctp_bind_addr_match(&asoc->base.bind_addr, laddr,
  					 sctp_sk(asoc->base.sk)))
  			goto out;
  	}
  	transport = NULL;
  
  out:

  	return transport;
  }
  
  /* Do delayed input processing.  This is scheduled by sctp_rcv(). */

  static void sctp_assoc_bh_rcv(struct work_struct *work)

  {

  	struct sctp_association *asoc =
  		container_of(work, struct sctp_association,
  			     base.inqueue.immediate);

  	struct sctp_endpoint *ep;
  	struct sctp_chunk *chunk;

  	struct sctp_inq *inqueue;
  	int state;
  	sctp_subtype_t subtype;
  	int error = 0;
  
  	/* The association should be held so we should be safe. */
  	ep = asoc->ep;

  
  	inqueue = &asoc->base.inqueue;
  	sctp_association_hold(asoc);
  	while (NULL != (chunk = sctp_inq_pop(inqueue))) {
  		state = asoc->state;
  		subtype = SCTP_ST_CHUNK(chunk->chunk_hdr->type);

  		/* SCTP-AUTH, Section 6.3:
  		 *    The receiver has a list of chunk types which it expects
  		 *    to be received only after an AUTH-chunk.  This list has
  		 *    been sent to the peer during the association setup.  It
  		 *    MUST silently discard these chunks if they are not placed
  		 *    after an AUTH chunk in the packet.
  		 */
  		if (sctp_auth_recv_cid(subtype.chunk, asoc) && !chunk->auth)
  			continue;

  		/* Remember where the last DATA chunk came from so we
  		 * know where to send the SACK.
  		 */
  		if (sctp_chunk_is_data(chunk))
  			asoc->peer.last_data_from = chunk->transport;
  		else
  			SCTP_INC_STATS(SCTP_MIB_INCTRLCHUNKS);
  
  		if (chunk->transport)
  			chunk->transport->last_time_heard = jiffies;
  
  		/* Run through the state machine. */
  		error = sctp_do_sm(SCTP_EVENT_T_CHUNK, subtype,
  				   state, ep, asoc, chunk, GFP_ATOMIC);
  
  		/* Check to see if the association is freed in response to
  		 * the incoming chunk.  If so, get out of the while loop.
  		 */
  		if (asoc->base.dead)
  			break;
  
  		/* If there is an error on chunk, discard this packet. */
  		if (error && chunk)
  			chunk->pdiscard = 1;
  	}
  	sctp_association_put(asoc);
  }
  
  /* This routine moves an association from its old sk to a new sk.  */
  void sctp_assoc_migrate(struct sctp_association *assoc, struct sock *newsk)
  {
  	struct sctp_sock *newsp = sctp_sk(newsk);
  	struct sock *oldsk = assoc->base.sk;
  
  	/* Delete the association from the old endpoint's list of
  	 * associations.
  	 */
  	list_del_init(&assoc->asocs);
  
  	/* Decrement the backlog value for a TCP-style socket. */
  	if (sctp_style(oldsk, TCP))
  		oldsk->sk_ack_backlog--;
  
  	/* Release references to the old endpoint and the sock.  */
  	sctp_endpoint_put(assoc->ep);
  	sock_put(assoc->base.sk);
  
  	/* Get a reference to the new endpoint.  */
  	assoc->ep = newsp->ep;
  	sctp_endpoint_hold(assoc->ep);
  
  	/* Get a reference to the new sock.  */
  	assoc->base.sk = newsk;
  	sock_hold(assoc->base.sk);
  
  	/* Add the association to the new endpoint's list of associations.  */
  	sctp_endpoint_add_asoc(newsp->ep, assoc);
  }
  
  /* Update an association (possibly from unexpected COOKIE-ECHO processing).  */
  void sctp_assoc_update(struct sctp_association *asoc,
  		       struct sctp_association *new)
  {
  	struct sctp_transport *trans;
  	struct list_head *pos, *temp;
  
  	/* Copy in new parameters of peer. */
  	asoc->c = new->c;
  	asoc->peer.rwnd = new->peer.rwnd;
  	asoc->peer.sack_needed = new->peer.sack_needed;
  	asoc->peer.i = new->peer.i;

  	sctp_tsnmap_init(&asoc->peer.tsn_map, SCTP_TSN_MAP_INITIAL,
  			 asoc->peer.i.initial_tsn, GFP_ATOMIC);

  
  	/* Remove any peer addresses not present in the new association. */
  	list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
  		trans = list_entry(pos, struct sctp_transport, transports);

  		if (!sctp_assoc_lookup_paddr(new, &trans->ipaddr)) {
  			sctp_assoc_rm_peer(asoc, trans);
  			continue;
  		}

  
  		if (asoc->state >= SCTP_STATE_ESTABLISHED)
  			sctp_transport_reset(trans);

  	}
  
  	/* If the case is A (association restart), use
  	 * initial_tsn as next_tsn. If the case is B, use
  	 * current next_tsn in case data sent to peer
  	 * has been discarded and needs retransmission.
  	 */
  	if (asoc->state >= SCTP_STATE_ESTABLISHED) {
  		asoc->next_tsn = new->next_tsn;
  		asoc->ctsn_ack_point = new->ctsn_ack_point;
  		asoc->adv_peer_ack_point = new->adv_peer_ack_point;
  
  		/* Reinitialize SSN for both local streams
  		 * and peer's streams.
  		 */
  		sctp_ssnmap_clear(asoc->ssnmap);

  		/* Flush the ULP reassembly and ordered queue.
  		 * Any data there will now be stale and will
  		 * cause problems.
  		 */
  		sctp_ulpq_flush(&asoc->ulpq);

  		/* reset the overall association error count so
  		 * that the restarted association doesn't get torn
  		 * down on the next retransmission timer.
  		 */
  		asoc->overall_error_count = 0;

  	} else {
  		/* Add any peer addresses from the new association. */

  		list_for_each_entry(trans, &new->peer.transport_addr_list,
  				transports) {

  			if (!sctp_assoc_lookup_paddr(asoc, &trans->ipaddr))
  				sctp_assoc_add_peer(asoc, &trans->ipaddr,

  						    GFP_ATOMIC, trans->state);

  		}
  
  		asoc->ctsn_ack_point = asoc->next_tsn - 1;
  		asoc->adv_peer_ack_point = asoc->ctsn_ack_point;
  		if (!asoc->ssnmap) {
  			/* Move the ssnmap. */
  			asoc->ssnmap = new->ssnmap;
  			new->ssnmap = NULL;
  		}

  
  		if (!asoc->assoc_id) {
  			/* get a new association id since we don't have one
  			 * yet.
  			 */
  			sctp_assoc_set_id(asoc, GFP_ATOMIC);
  		}

  	}

  	/* SCTP-AUTH: Save the peer parameters from the new assocaitions
  	 * and also move the association shared keys over
  	 */
  	kfree(asoc->peer.peer_random);
  	asoc->peer.peer_random = new->peer.peer_random;
  	new->peer.peer_random = NULL;
  
  	kfree(asoc->peer.peer_chunks);
  	asoc->peer.peer_chunks = new->peer.peer_chunks;
  	new->peer.peer_chunks = NULL;
  
  	kfree(asoc->peer.peer_hmacs);
  	asoc->peer.peer_hmacs = new->peer.peer_hmacs;
  	new->peer.peer_hmacs = NULL;
  
  	sctp_auth_key_put(asoc->asoc_shared_key);
  	sctp_auth_asoc_init_active_key(asoc, GFP_ATOMIC);

  }
  
  /* Update the retran path for sending a retransmitted packet.
   * Round-robin through the active transports, else round-robin
   * through the inactive transports as this is the next best thing
   * we can try.
   */
  void sctp_assoc_update_retran_path(struct sctp_association *asoc)
  {
  	struct sctp_transport *t, *next;
  	struct list_head *head = &asoc->peer.transport_addr_list;
  	struct list_head *pos;

  	if (asoc->peer.transport_count == 1)
  		return;

  	/* Find the next transport in a round-robin fashion. */
  	t = asoc->peer.retran_path;
  	pos = &t->transports;
  	next = NULL;
  
  	while (1) {
  		/* Skip the head. */
  		if (pos->next == head)
  			pos = head->next;
  		else
  			pos = pos->next;
  
  		t = list_entry(pos, struct sctp_transport, transports);

  		/* We have exhausted the list, but didn't find any
  		 * other active transports.  If so, use the next
  		 * transport.
  		 */
  		if (t == asoc->peer.retran_path) {
  			t = next;
  			break;
  		}

  		/* Try to find an active transport. */

  		if ((t->state == SCTP_ACTIVE) ||
  		    (t->state == SCTP_UNKNOWN)) {

  			break;
  		} else {
  			/* Keep track of the next transport in case
  			 * we don't find any active transport.
  			 */

  			if (t->state != SCTP_UNCONFIRMED && !next)

  				next = t;
  		}

  	}

  	if (t)
  		asoc->peer.retran_path = t;

  	else
  		t = asoc->peer.retran_path;

  
  	SCTP_DEBUG_PRINTK_IPADDR("sctp_assoc_update_retran_path:association"
  				 " %p addr: ",
  				 " port: %d
  ",
  				 asoc,
  				 (&t->ipaddr),

  				 ntohs(t->ipaddr.v4.sin_port));

  }

  /* Choose the transport for sending retransmit packet.  */
  struct sctp_transport *sctp_assoc_choose_alter_transport(
  	struct sctp_association *asoc, struct sctp_transport *last_sent_to)

  {

  	/* If this is the first time packet is sent, use the active path,
  	 * else use the retran path. If the last packet was sent over the

  	 * retran path, update the retran path and use it.
  	 */

  	if (!last_sent_to)

  		return asoc->peer.active_path;
  	else {

  		if (last_sent_to == asoc->peer.retran_path)

  			sctp_assoc_update_retran_path(asoc);
  		return asoc->peer.retran_path;
  	}

  }
  
  /* Update the association's pmtu and frag_point by going through all the
   * transports. This routine is called when a transport's PMTU has changed.
   */
  void sctp_assoc_sync_pmtu(struct sctp_association *asoc)
  {
  	struct sctp_transport *t;

  	__u32 pmtu = 0;
  
  	if (!asoc)
  		return;
  
  	/* Get the lowest pmtu of all the transports. */

  	list_for_each_entry(t, &asoc->peer.transport_addr_list,
  				transports) {

  		if (t->pmtu_pending && t->dst) {
  			sctp_transport_update_pmtu(t, dst_mtu(t->dst));
  			t->pmtu_pending = 0;
  		}

  		if (!pmtu || (t->pathmtu < pmtu))
  			pmtu = t->pathmtu;

  	}
  
  	if (pmtu) {

  		asoc->pathmtu = pmtu;

  		asoc->frag_point = sctp_frag_point(asoc, pmtu);

  	}
  
  	SCTP_DEBUG_PRINTK("%s: asoc:%p, pmtu:%d, frag_point:%d
  ",

  			  __func__, asoc, asoc->pathmtu, asoc->frag_point);

  }
  
  /* Should we send a SACK to update our peer? */
  static inline int sctp_peer_needs_update(struct sctp_association *asoc)
  {
  	switch (asoc->state) {
  	case SCTP_STATE_ESTABLISHED:
  	case SCTP_STATE_SHUTDOWN_PENDING:
  	case SCTP_STATE_SHUTDOWN_RECEIVED:
  	case SCTP_STATE_SHUTDOWN_SENT:
  		if ((asoc->rwnd > asoc->a_rwnd) &&

  		    ((asoc->rwnd - asoc->a_rwnd) >= max_t(__u32,
  			   (asoc->base.sk->sk_rcvbuf >> sctp_rwnd_upd_shift),
  			   asoc->pathmtu)))

  			return 1;
  		break;
  	default:
  		break;
  	}
  	return 0;
  }
  
  /* Increase asoc's rwnd by len and send any window update SACK if needed. */
  void sctp_assoc_rwnd_increase(struct sctp_association *asoc, unsigned len)
  {
  	struct sctp_chunk *sack;
  	struct timer_list *timer;
  
  	if (asoc->rwnd_over) {
  		if (asoc->rwnd_over >= len) {
  			asoc->rwnd_over -= len;
  		} else {
  			asoc->rwnd += (len - asoc->rwnd_over);
  			asoc->rwnd_over = 0;
  		}
  	} else {
  		asoc->rwnd += len;
  	}

  	/* If we had window pressure, start recovering it
  	 * once our rwnd had reached the accumulated pressure
  	 * threshold.  The idea is to recover slowly, but up
  	 * to the initial advertised window.
  	 */
  	if (asoc->rwnd_press && asoc->rwnd >= asoc->rwnd_press) {
  		int change = min(asoc->pathmtu, asoc->rwnd_press);
  		asoc->rwnd += change;
  		asoc->rwnd_press -= change;
  	}

  	SCTP_DEBUG_PRINTK("%s: asoc %p rwnd increased by %d to (%u, %u) "

  			  "- %u
  ", __func__, asoc, len, asoc->rwnd,

  			  asoc->rwnd_over, asoc->a_rwnd);
  
  	/* Send a window update SACK if the rwnd has increased by at least the
  	 * minimum of the association's PMTU and half of the receive buffer.
  	 * The algorithm used is similar to the one described in
  	 * Section 4.2.3.3 of RFC 1122.
  	 */
  	if (sctp_peer_needs_update(asoc)) {
  		asoc->a_rwnd = asoc->rwnd;
  		SCTP_DEBUG_PRINTK("%s: Sending window update SACK- asoc: %p "

  				  "rwnd: %u a_rwnd: %u
  ", __func__,

  				  asoc, asoc->rwnd, asoc->a_rwnd);
  		sack = sctp_make_sack(asoc);
  		if (!sack)
  			return;
  
  		asoc->peer.sack_needed = 0;
  
  		sctp_outq_tail(&asoc->outqueue, sack);
  
  		/* Stop the SACK timer.  */
  		timer = &asoc->timers[SCTP_EVENT_TIMEOUT_SACK];
  		if (timer_pending(timer) && del_timer(timer))
  			sctp_association_put(asoc);
  	}
  }
  
  /* Decrease asoc's rwnd by len. */
  void sctp_assoc_rwnd_decrease(struct sctp_association *asoc, unsigned len)
  {

  	int rx_count;
  	int over = 0;

  	SCTP_ASSERT(asoc->rwnd, "rwnd zero", return);
  	SCTP_ASSERT(!asoc->rwnd_over, "rwnd_over not zero", return);

  
  	if (asoc->ep->rcvbuf_policy)
  		rx_count = atomic_read(&asoc->rmem_alloc);
  	else
  		rx_count = atomic_read(&asoc->base.sk->sk_rmem_alloc);
  
  	/* If we've reached or overflowed our receive buffer, announce
  	 * a 0 rwnd if rwnd would still be positive.  Store the
  	 * the pottential pressure overflow so that the window can be restored
  	 * back to original value.
  	 */
  	if (rx_count >= asoc->base.sk->sk_rcvbuf)
  		over = 1;

  	if (asoc->rwnd >= len) {
  		asoc->rwnd -= len;

  		if (over) {

  			asoc->rwnd_press += asoc->rwnd;

  			asoc->rwnd = 0;
  		}

  	} else {
  		asoc->rwnd_over = len - asoc->rwnd;
  		asoc->rwnd = 0;
  	}

  	SCTP_DEBUG_PRINTK("%s: asoc %p rwnd decreased by %d to (%u, %u, %u)
  ",

  			  __func__, asoc, len, asoc->rwnd,

  			  asoc->rwnd_over, asoc->rwnd_press);

  }
  
  /* Build the bind address list for the association based on info from the
   * local endpoint and the remote peer.
   */

  int sctp_assoc_set_bind_addr_from_ep(struct sctp_association *asoc,

  				     sctp_scope_t scope, gfp_t gfp)

  {

  	int flags;
  
  	/* Use scoping rules to determine the subset of addresses from
  	 * the endpoint.
  	 */

  	flags = (PF_INET6 == asoc->base.sk->sk_family) ? SCTP_ADDR6_ALLOWED : 0;
  	if (asoc->peer.ipv4_address)
  		flags |= SCTP_ADDR4_PEERSUPP;
  	if (asoc->peer.ipv6_address)
  		flags |= SCTP_ADDR6_PEERSUPP;
  
  	return sctp_bind_addr_copy(&asoc->base.bind_addr,
  				   &asoc->ep->base.bind_addr,
  				   scope, gfp, flags);
  }
  
  /* Build the association's bind address list from the cookie.  */
  int sctp_assoc_set_bind_addr_from_cookie(struct sctp_association *asoc,

  					 struct sctp_cookie *cookie,

  					 gfp_t gfp)

  {
  	int var_size2 = ntohs(cookie->peer_init->chunk_hdr.length);
  	int var_size3 = cookie->raw_addr_list_len;
  	__u8 *raw = (__u8 *)cookie->peer_init + var_size2;
  
  	return sctp_raw_to_bind_addrs(&asoc->base.bind_addr, raw, var_size3,
  				      asoc->ep->base.bind_addr.port, gfp);
  }

  /* Lookup laddr in the bind address list of an association. */
  int sctp_assoc_lookup_laddr(struct sctp_association *asoc,

  			    const union sctp_addr *laddr)
  {

  	int found = 0;

  	if ((asoc->base.bind_addr.port == ntohs(laddr->v4.sin_port)) &&
  	    sctp_bind_addr_match(&asoc->base.bind_addr, laddr,

  				 sctp_sk(asoc->base.sk)))

  		found = 1;

  	return found;
  }

  
  /* Set an association id for a given association */
  int sctp_assoc_set_id(struct sctp_association *asoc, gfp_t gfp)
  {
  	int assoc_id;
  	int error = 0;

  
  	/* If the id is already assigned, keep it. */
  	if (asoc->assoc_id)
  		return error;

  retry:
  	if (unlikely(!idr_pre_get(&sctp_assocs_id, gfp)))
  		return -ENOMEM;
  
  	spin_lock_bh(&sctp_assocs_id_lock);
  	error = idr_get_new_above(&sctp_assocs_id, (void *)asoc,

  				    idr_low, &assoc_id);
  	if (!error) {
  		idr_low = assoc_id + 1;
  		if (idr_low == INT_MAX)
  			idr_low = 1;
  	}

  	spin_unlock_bh(&sctp_assocs_id_lock);
  	if (error == -EAGAIN)
  		goto retry;
  	else if (error)
  		return error;
  
  	asoc->assoc_id = (sctp_assoc_t) assoc_id;
  	return error;
  }

  /* Free the ASCONF queue */
  static void sctp_assoc_free_asconf_queue(struct sctp_association *asoc)
  {
  	struct sctp_chunk *asconf;
  	struct sctp_chunk *tmp;
  
  	list_for_each_entry_safe(asconf, tmp, &asoc->addip_chunk_list, list) {
  		list_del_init(&asconf->list);
  		sctp_chunk_free(asconf);
  	}
  }

  /* Free asconf_ack cache */
  static void sctp_assoc_free_asconf_acks(struct sctp_association *asoc)
  {
  	struct sctp_chunk *ack;
  	struct sctp_chunk *tmp;
  
  	list_for_each_entry_safe(ack, tmp, &asoc->asconf_ack_list,
  				transmitted_list) {
  		list_del_init(&ack->transmitted_list);
  		sctp_chunk_free(ack);
  	}
  }
  
  /* Clean up the ASCONF_ACK queue */
  void sctp_assoc_clean_asconf_ack_cache(const struct sctp_association *asoc)
  {
  	struct sctp_chunk *ack;
  	struct sctp_chunk *tmp;

  	/* We can remove all the entries from the queue up to

  	 * the "Peer-Sequence-Number".
  	 */
  	list_for_each_entry_safe(ack, tmp, &asoc->asconf_ack_list,
  				transmitted_list) {
  		if (ack->subh.addip_hdr->serial ==
  				htonl(asoc->peer.addip_serial))
  			break;
  
  		list_del_init(&ack->transmitted_list);
  		sctp_chunk_free(ack);
  	}
  }
  
  /* Find the ASCONF_ACK whose serial number matches ASCONF */
  struct sctp_chunk *sctp_assoc_lookup_asconf_ack(
  					const struct sctp_association *asoc,
  					__be32 serial)
  {

  	struct sctp_chunk *ack;

  
  	/* Walk through the list of cached ASCONF-ACKs and find the
  	 * ack chunk whose serial number matches that of the request.
  	 */
  	list_for_each_entry(ack, &asoc->asconf_ack_list, transmitted_list) {
  		if (ack->subh.addip_hdr->serial == serial) {
  			sctp_chunk_hold(ack);

  			return ack;

  		}
  	}

  	return NULL;

  }

  
  void sctp_asconf_queue_teardown(struct sctp_association *asoc)
  {
  	/* Free any cached ASCONF_ACK chunk. */
  	sctp_assoc_free_asconf_acks(asoc);
  
  	/* Free the ASCONF queue. */
  	sctp_assoc_free_asconf_queue(asoc);
  
  	/* Free any cached ASCONF chunk. */
  	if (asoc->addip_last_asconf)
  		sctp_chunk_free(asoc->addip_last_asconf);
  }