/* SCTP kernel implementation
   * (C) Copyright IBM Corp. 2001, 2004
   * Copyright (c) 1999 Cisco, Inc.
   * Copyright (c) 1999-2001 Motorola, Inc.
   *
   * This file is part of the SCTP kernel implementation
   *
   * These functions work with the state functions in sctp_sm_statefuns.c
   * to implement that state operations.  These functions implement the
   * steps which require modifying existing data structures.
   *
   * 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, see
   * <http://www.gnu.org/licenses/>.
   *
   * Please send any bug reports or fixes you make to the
   * email address(es):
   *    lksctp developers <linux-sctp@vger.kernel.org>
   *
   * Written or modified by:
   *    La Monte H.P. Yarroll <piggy@acm.org>
   *    Karl Knutson          <karl@athena.chicago.il.us>
   *    Jon Grimm             <jgrimm@austin.ibm.com>
   *    Hui Huang		    <hui.huang@nokia.com>
   *    Dajiang Zhang	    <dajiang.zhang@nokia.com>
   *    Daisy Chang	    <daisyc@us.ibm.com>
   *    Sridhar Samudrala	    <sri@us.ibm.com>
   *    Ardelle Fan	    <ardelle.fan@intel.com>
   */
  
  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  
  #include <linux/skbuff.h>
  #include <linux/types.h>
  #include <linux/socket.h>
  #include <linux/ip.h>
  #include <linux/gfp.h>
  #include <net/sock.h>
  #include <net/sctp/sctp.h>
  #include <net/sctp/sm.h>
  
  static int sctp_cmd_interpreter(sctp_event_t event_type,
  				sctp_subtype_t subtype,
  				sctp_state_t state,
  				struct sctp_endpoint *ep,
  				struct sctp_association *asoc,
  				void *event_arg,
  				sctp_disposition_t status,
  				sctp_cmd_seq_t *commands,
  				gfp_t gfp);
  static int sctp_side_effects(sctp_event_t event_type, sctp_subtype_t subtype,
  			     sctp_state_t state,
  			     struct sctp_endpoint *ep,
  			     struct sctp_association *asoc,
  			     void *event_arg,
  			     sctp_disposition_t status,
  			     sctp_cmd_seq_t *commands,
  			     gfp_t gfp);
  
  static void sctp_cmd_hb_timer_update(sctp_cmd_seq_t *cmds,
  				     struct sctp_transport *t);
  /********************************************************************
   * Helper functions
   ********************************************************************/
  
  /* A helper function for delayed processing of INET ECN CE bit. */
  static void sctp_do_ecn_ce_work(struct sctp_association *asoc,
  				__u32 lowest_tsn)
  {
  	/* Save the TSN away for comparison when we receive CWR */
  
  	asoc->last_ecne_tsn = lowest_tsn;
  	asoc->need_ecne = 1;
  }
  
  /* Helper function for delayed processing of SCTP ECNE chunk.  */
  /* RFC 2960 Appendix A
   *
   * RFC 2481 details a specific bit for a sender to send in
   * the header of its next outbound TCP segment to indicate to
   * its peer that it has reduced its congestion window.  This
   * is termed the CWR bit.  For SCTP the same indication is made
   * by including the CWR chunk.  This chunk contains one data
   * element, i.e. the TSN number that was sent in the ECNE chunk.
   * This element represents the lowest TSN number in the datagram
   * that was originally marked with the CE bit.
   */
  static struct sctp_chunk *sctp_do_ecn_ecne_work(struct sctp_association *asoc,
  					   __u32 lowest_tsn,
  					   struct sctp_chunk *chunk)
  {
  	struct sctp_chunk *repl;
  
  	/* Our previously transmitted packet ran into some congestion
  	 * so we should take action by reducing cwnd and ssthresh
  	 * and then ACK our peer that we we've done so by
  	 * sending a CWR.
  	 */
  
  	/* First, try to determine if we want to actually lower
  	 * our cwnd variables.  Only lower them if the ECNE looks more
  	 * recent than the last response.
  	 */
  	if (TSN_lt(asoc->last_cwr_tsn, lowest_tsn)) {
  		struct sctp_transport *transport;
  
  		/* Find which transport's congestion variables
  		 * need to be adjusted.
  		 */
  		transport = sctp_assoc_lookup_tsn(asoc, lowest_tsn);
  
  		/* Update the congestion variables. */
  		if (transport)
  			sctp_transport_lower_cwnd(transport,
  						  SCTP_LOWER_CWND_ECNE);
  		asoc->last_cwr_tsn = lowest_tsn;
  	}
  
  	/* Always try to quiet the other end.  In case of lost CWR,
  	 * resend last_cwr_tsn.
  	 */
  	repl = sctp_make_cwr(asoc, asoc->last_cwr_tsn, chunk);
  
  	/* If we run out of memory, it will look like a lost CWR.  We'll
  	 * get back in sync eventually.
  	 */
  	return repl;
  }
  
  /* Helper function to do delayed processing of ECN CWR chunk.  */
  static void sctp_do_ecn_cwr_work(struct sctp_association *asoc,
  				 __u32 lowest_tsn)
  {
  	/* Turn off ECNE getting auto-prepended to every outgoing
  	 * packet
  	 */
  	asoc->need_ecne = 0;
  }
  
  /* Generate SACK if necessary.  We call this at the end of a packet.  */
  static int sctp_gen_sack(struct sctp_association *asoc, int force,
  			 sctp_cmd_seq_t *commands)
  {
  	__u32 ctsn, max_tsn_seen;
  	struct sctp_chunk *sack;
  	struct sctp_transport *trans = asoc->peer.last_data_from;
  	int error = 0;
  
  	if (force ||
  	    (!trans && (asoc->param_flags & SPP_SACKDELAY_DISABLE)) ||
  	    (trans && (trans->param_flags & SPP_SACKDELAY_DISABLE)))
  		asoc->peer.sack_needed = 1;
  
  	ctsn = sctp_tsnmap_get_ctsn(&asoc->peer.tsn_map);
  	max_tsn_seen = sctp_tsnmap_get_max_tsn_seen(&asoc->peer.tsn_map);
  
  	/* From 12.2 Parameters necessary per association (i.e. the TCB):
  	 *
  	 * Ack State : This flag indicates if the next received packet
  	 * 	     : is to be responded to with a SACK. ...
  	 *	     : When DATA chunks are out of order, SACK's
  	 *           : are not delayed (see Section 6).
  	 *
  	 * [This is actually not mentioned in Section 6, but we
  	 * implement it here anyway. --piggy]
  	 */
  	if (max_tsn_seen != ctsn)
  		asoc->peer.sack_needed = 1;
  
  	/* From 6.2  Acknowledgement on Reception of DATA Chunks:
  	 *
  	 * Section 4.2 of [RFC2581] SHOULD be followed. Specifically,
  	 * an acknowledgement SHOULD be generated for at least every
  	 * second packet (not every second DATA chunk) received, and
  	 * SHOULD be generated within 200 ms of the arrival of any
  	 * unacknowledged DATA chunk. ...
  	 */
  	if (!asoc->peer.sack_needed) {
  		asoc->peer.sack_cnt++;
  
  		/* Set the SACK delay timeout based on the
  		 * SACK delay for the last transport
  		 * data was received from, or the default
  		 * for the association.
  		 */
  		if (trans) {
  			/* We will need a SACK for the next packet.  */
  			if (asoc->peer.sack_cnt >= trans->sackfreq - 1)
  				asoc->peer.sack_needed = 1;
  
  			asoc->timeouts[SCTP_EVENT_TIMEOUT_SACK] =
  				trans->sackdelay;
  		} else {
  			/* We will need a SACK for the next packet.  */
  			if (asoc->peer.sack_cnt >= asoc->sackfreq - 1)
  				asoc->peer.sack_needed = 1;
  
  			asoc->timeouts[SCTP_EVENT_TIMEOUT_SACK] =
  				asoc->sackdelay;
  		}
  
  		/* Restart the SACK timer. */
  		sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_RESTART,
  				SCTP_TO(SCTP_EVENT_TIMEOUT_SACK));
  	} else {
  		asoc->a_rwnd = asoc->rwnd;
  		sack = sctp_make_sack(asoc);
  		if (!sack)
  			goto nomem;
  
  		asoc->peer.sack_needed = 0;
  		asoc->peer.sack_cnt = 0;
  
  		sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(sack));
  
  		/* Stop the SACK timer.  */
  		sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
  				SCTP_TO(SCTP_EVENT_TIMEOUT_SACK));
  	}
  
  	return error;
  nomem:
  	error = -ENOMEM;
  	return error;
  }
  
  /* When the T3-RTX timer expires, it calls this function to create the
   * relevant state machine event.
   */
  void sctp_generate_t3_rtx_event(unsigned long peer)
  {
  	int error;
  	struct sctp_transport *transport = (struct sctp_transport *) peer;
  	struct sctp_association *asoc = transport->asoc;
  	struct net *net = sock_net(asoc->base.sk);
  
  	/* Check whether a task is in the sock.  */
  
  	bh_lock_sock(asoc->base.sk);
  	if (sock_owned_by_user(asoc->base.sk)) {
  		pr_debug("%s: sock is busy
  ", __func__);
  
  		/* Try again later.  */
  		if (!mod_timer(&transport->T3_rtx_timer, jiffies + (HZ/20)))
  			sctp_transport_hold(transport);
  		goto out_unlock;
  	}
  
  	/* Is this transport really dead and just waiting around for
  	 * the timer to let go of the reference?
  	 */
  	if (transport->dead)
  		goto out_unlock;
  
  	/* Run through the state machine.  */
  	error = sctp_do_sm(net, SCTP_EVENT_T_TIMEOUT,
  			   SCTP_ST_TIMEOUT(SCTP_EVENT_TIMEOUT_T3_RTX),
  			   asoc->state,
  			   asoc->ep, asoc,
  			   transport, GFP_ATOMIC);
  
  	if (error)
  		asoc->base.sk->sk_err = -error;
  
  out_unlock:
  	bh_unlock_sock(asoc->base.sk);
  	sctp_transport_put(transport);
  }
  
  /* This is a sa interface for producing timeout events.  It works
   * for timeouts which use the association as their parameter.
   */
  static void sctp_generate_timeout_event(struct sctp_association *asoc,
  					sctp_event_timeout_t timeout_type)
  {
  	struct net *net = sock_net(asoc->base.sk);
  	int error = 0;
  
  	bh_lock_sock(asoc->base.sk);
  	if (sock_owned_by_user(asoc->base.sk)) {
  		pr_debug("%s: sock is busy: timer %d
  ", __func__,
  			 timeout_type);
  
  		/* Try again later.  */
  		if (!mod_timer(&asoc->timers[timeout_type], jiffies + (HZ/20)))
  			sctp_association_hold(asoc);
  		goto out_unlock;
  	}
  
  	/* Is this association really dead and just waiting around for
  	 * the timer to let go of the reference?
  	 */
  	if (asoc->base.dead)
  		goto out_unlock;
  
  	/* Run through the state machine.  */
  	error = sctp_do_sm(net, SCTP_EVENT_T_TIMEOUT,
  			   SCTP_ST_TIMEOUT(timeout_type),
  			   asoc->state, asoc->ep, asoc,
  			   (void *)timeout_type, GFP_ATOMIC);
  
  	if (error)
  		asoc->base.sk->sk_err = -error;
  
  out_unlock:
  	bh_unlock_sock(asoc->base.sk);
  	sctp_association_put(asoc);
  }
  
  static void sctp_generate_t1_cookie_event(unsigned long data)
  {
  	struct sctp_association *asoc = (struct sctp_association *) data;
  	sctp_generate_timeout_event(asoc, SCTP_EVENT_TIMEOUT_T1_COOKIE);
  }
  
  static void sctp_generate_t1_init_event(unsigned long data)
  {
  	struct sctp_association *asoc = (struct sctp_association *) data;
  	sctp_generate_timeout_event(asoc, SCTP_EVENT_TIMEOUT_T1_INIT);
  }
  
  static void sctp_generate_t2_shutdown_event(unsigned long data)
  {
  	struct sctp_association *asoc = (struct sctp_association *) data;
  	sctp_generate_timeout_event(asoc, SCTP_EVENT_TIMEOUT_T2_SHUTDOWN);
  }
  
  static void sctp_generate_t4_rto_event(unsigned long data)
  {
  	struct sctp_association *asoc = (struct sctp_association *) data;
  	sctp_generate_timeout_event(asoc, SCTP_EVENT_TIMEOUT_T4_RTO);
  }
  
  static void sctp_generate_t5_shutdown_guard_event(unsigned long data)
  {
  	struct sctp_association *asoc = (struct sctp_association *)data;
  	sctp_generate_timeout_event(asoc,
  				    SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD);
  
  } /* sctp_generate_t5_shutdown_guard_event() */
  
  static void sctp_generate_autoclose_event(unsigned long data)
  {
  	struct sctp_association *asoc = (struct sctp_association *) data;
  	sctp_generate_timeout_event(asoc, SCTP_EVENT_TIMEOUT_AUTOCLOSE);
  }
  
  /* Generate a heart beat event.  If the sock is busy, reschedule.   Make
   * sure that the transport is still valid.
   */
  void sctp_generate_heartbeat_event(unsigned long data)
  {
  	int error = 0;
  	struct sctp_transport *transport = (struct sctp_transport *) data;
  	struct sctp_association *asoc = transport->asoc;
  	struct net *net = sock_net(asoc->base.sk);
  
  	bh_lock_sock(asoc->base.sk);
  	if (sock_owned_by_user(asoc->base.sk)) {
  		pr_debug("%s: sock is busy
  ", __func__);
  
  		/* Try again later.  */
  		if (!mod_timer(&transport->hb_timer, jiffies + (HZ/20)))
  			sctp_transport_hold(transport);
  		goto out_unlock;
  	}
  
  	/* Is this structure just waiting around for us to actually
  	 * get destroyed?
  	 */
  	if (transport->dead)
  		goto out_unlock;
  
  	error = sctp_do_sm(net, SCTP_EVENT_T_TIMEOUT,
  			   SCTP_ST_TIMEOUT(SCTP_EVENT_TIMEOUT_HEARTBEAT),
  			   asoc->state, asoc->ep, asoc,
  			   transport, GFP_ATOMIC);
  
  	 if (error)
  		 asoc->base.sk->sk_err = -error;
  
  out_unlock:
  	bh_unlock_sock(asoc->base.sk);
  	sctp_transport_put(transport);
  }
  
  /* Handle the timeout of the ICMP protocol unreachable timer.  Trigger
   * the correct state machine transition that will close the association.
   */
  void sctp_generate_proto_unreach_event(unsigned long data)
  {
  	struct sctp_transport *transport = (struct sctp_transport *) data;
  	struct sctp_association *asoc = transport->asoc;
  	struct net *net = sock_net(asoc->base.sk);
  
  	bh_lock_sock(asoc->base.sk);
  	if (sock_owned_by_user(asoc->base.sk)) {
  		pr_debug("%s: sock is busy
  ", __func__);
  
  		/* Try again later.  */
  		if (!mod_timer(&transport->proto_unreach_timer,
  				jiffies + (HZ/20)))
  			sctp_association_hold(asoc);
  		goto out_unlock;
  	}
  
  	/* Is this structure just waiting around for us to actually
  	 * get destroyed?
  	 */
  	if (asoc->base.dead)
  		goto out_unlock;
  
  	sctp_do_sm(net, SCTP_EVENT_T_OTHER,
  		   SCTP_ST_OTHER(SCTP_EVENT_ICMP_PROTO_UNREACH),
  		   asoc->state, asoc->ep, asoc, transport, GFP_ATOMIC);
  
  out_unlock:
  	bh_unlock_sock(asoc->base.sk);
  	sctp_association_put(asoc);
  }
  
  
  /* Inject a SACK Timeout event into the state machine.  */
  static void sctp_generate_sack_event(unsigned long data)
  {
  	struct sctp_association *asoc = (struct sctp_association *) data;
  	sctp_generate_timeout_event(asoc, SCTP_EVENT_TIMEOUT_SACK);
  }
  
  sctp_timer_event_t *sctp_timer_events[SCTP_NUM_TIMEOUT_TYPES] = {
  	NULL,
  	sctp_generate_t1_cookie_event,
  	sctp_generate_t1_init_event,
  	sctp_generate_t2_shutdown_event,
  	NULL,
  	sctp_generate_t4_rto_event,
  	sctp_generate_t5_shutdown_guard_event,
  	NULL,
  	sctp_generate_sack_event,
  	sctp_generate_autoclose_event,
  };
  
  
  /* RFC 2960 8.2 Path Failure Detection
   *
   * When its peer endpoint is multi-homed, an endpoint should keep a
   * error counter for each of the destination transport addresses of the
   * peer endpoint.
   *
   * Each time the T3-rtx timer expires on any address, or when a
   * HEARTBEAT sent to an idle address is not acknowledged within a RTO,
   * the error counter of that destination address will be incremented.
   * When the value in the error counter exceeds the protocol parameter
   * 'Path.Max.Retrans' of that destination address, the endpoint should
   * mark the destination transport address as inactive, and a
   * notification SHOULD be sent to the upper layer.
   *
   */
  static void sctp_do_8_2_transport_strike(sctp_cmd_seq_t *commands,
  					 struct sctp_association *asoc,
  					 struct sctp_transport *transport,
  					 int is_hb)
  {
  	/* The check for association's overall error counter exceeding the
  	 * threshold is done in the state function.
  	 */
  	/* We are here due to a timer expiration.  If the timer was
  	 * not a HEARTBEAT, then normal error tracking is done.
  	 * If the timer was a heartbeat, we only increment error counts
  	 * when we already have an outstanding HEARTBEAT that has not
  	 * been acknowledged.
  	 * Additionally, some tranport states inhibit error increments.
  	 */
  	if (!is_hb) {
  		asoc->overall_error_count++;
  		if (transport->state != SCTP_INACTIVE)
  			transport->error_count++;
  	 } else if (transport->hb_sent) {
  		if (transport->state != SCTP_UNCONFIRMED)
  			asoc->overall_error_count++;
  		if (transport->state != SCTP_INACTIVE)
  			transport->error_count++;
  	}
  
  	/* If the transport error count is greater than the pf_retrans
  	 * threshold, and less than pathmaxrtx, and if the current state
  	 * is SCTP_ACTIVE, then mark this transport as Partially Failed,
  	 * see SCTP Quick Failover Draft, section 5.1
  	 */
  	if ((transport->state == SCTP_ACTIVE) &&
  	   (asoc->pf_retrans < transport->pathmaxrxt) &&
  	   (transport->error_count > asoc->pf_retrans)) {
  
  		sctp_assoc_control_transport(asoc, transport,
  					     SCTP_TRANSPORT_PF,
  					     0);
  
  		/* Update the hb timer to resend a heartbeat every rto */
  		sctp_cmd_hb_timer_update(commands, transport);
  	}
  
  	if (transport->state != SCTP_INACTIVE &&
  	    (transport->error_count > transport->pathmaxrxt)) {
  		pr_debug("%s: association:%p transport addr:%pISpc failed
  ",
  			 __func__, asoc, &transport->ipaddr.sa);
  
  		sctp_assoc_control_transport(asoc, transport,
  					     SCTP_TRANSPORT_DOWN,
  					     SCTP_FAILED_THRESHOLD);
  	}
  
  	/* E2) For the destination address for which the timer
  	 * expires, set RTO <- RTO * 2 ("back off the timer").  The
  	 * maximum value discussed in rule C7 above (RTO.max) may be
  	 * used to provide an upper bound to this doubling operation.
  	 *
  	 * Special Case:  the first HB doesn't trigger exponential backoff.
  	 * The first unacknowledged HB triggers it.  We do this with a flag
  	 * that indicates that we have an outstanding HB.
  	 */
  	if (!is_hb || transport->hb_sent) {
  		transport->rto = min((transport->rto * 2), transport->asoc->rto_max);
  		sctp_max_rto(asoc, transport);
  	}
  }
  
  /* Worker routine to handle INIT command failure.  */
  static void sctp_cmd_init_failed(sctp_cmd_seq_t *commands,
  				 struct sctp_association *asoc,
  				 unsigned int error)
  {
  	struct sctp_ulpevent *event;
  
  	event = sctp_ulpevent_make_assoc_change(asoc, 0, SCTP_CANT_STR_ASSOC,
  						(__u16)error, 0, 0, NULL,
  						GFP_ATOMIC);
  
  	if (event)
  		sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP,
  				SCTP_ULPEVENT(event));
  
  	sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
  			SCTP_STATE(SCTP_STATE_CLOSED));
  
  	/* SEND_FAILED sent later when cleaning up the association. */
  	asoc->outqueue.error = error;
  	sctp_add_cmd_sf(commands, SCTP_CMD_DELETE_TCB, SCTP_NULL());
  }
  
  /* Worker routine to handle SCTP_CMD_ASSOC_FAILED.  */
  static void sctp_cmd_assoc_failed(sctp_cmd_seq_t *commands,
  				  struct sctp_association *asoc,
  				  sctp_event_t event_type,
  				  sctp_subtype_t subtype,
  				  struct sctp_chunk *chunk,
  				  unsigned int error)
  {
  	struct sctp_ulpevent *event;
  	struct sctp_chunk *abort;
  	/* Cancel any partial delivery in progress. */
  	sctp_ulpq_abort_pd(&asoc->ulpq, GFP_ATOMIC);
  
  	if (event_type == SCTP_EVENT_T_CHUNK && subtype.chunk == SCTP_CID_ABORT)
  		event = sctp_ulpevent_make_assoc_change(asoc, 0, SCTP_COMM_LOST,
  						(__u16)error, 0, 0, chunk,
  						GFP_ATOMIC);
  	else
  		event = sctp_ulpevent_make_assoc_change(asoc, 0, SCTP_COMM_LOST,
  						(__u16)error, 0, 0, NULL,
  						GFP_ATOMIC);
  	if (event)
  		sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP,
  				SCTP_ULPEVENT(event));
  
  	if (asoc->overall_error_count >= asoc->max_retrans) {
  		abort = sctp_make_violation_max_retrans(asoc, chunk);
  		if (abort)
  			sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
  					SCTP_CHUNK(abort));
  	}
  
  	sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
  			SCTP_STATE(SCTP_STATE_CLOSED));
  
  	/* SEND_FAILED sent later when cleaning up the association. */
  	asoc->outqueue.error = error;
  	sctp_add_cmd_sf(commands, SCTP_CMD_DELETE_TCB, SCTP_NULL());
  }
  
  /* Process an init chunk (may be real INIT/INIT-ACK or an embedded INIT
   * inside the cookie.  In reality, this is only used for INIT-ACK processing
   * since all other cases use "temporary" associations and can do all
   * their work in statefuns directly.
   */
  static int sctp_cmd_process_init(sctp_cmd_seq_t *commands,
  				 struct sctp_association *asoc,
  				 struct sctp_chunk *chunk,
  				 sctp_init_chunk_t *peer_init,
  				 gfp_t gfp)
  {
  	int error;
  
  	/* We only process the init as a sideeffect in a single
  	 * case.   This is when we process the INIT-ACK.   If we
  	 * fail during INIT processing (due to malloc problems),
  	 * just return the error and stop processing the stack.
  	 */
  	if (!sctp_process_init(asoc, chunk, sctp_source(chunk), peer_init, gfp))
  		error = -ENOMEM;
  	else
  		error = 0;
  
  	return error;
  }
  
  /* Helper function to break out starting up of heartbeat timers.  */
  static void sctp_cmd_hb_timers_start(sctp_cmd_seq_t *cmds,
  				     struct sctp_association *asoc)
  {
  	struct sctp_transport *t;
  
  	/* Start a heartbeat timer for each transport on the association.
  	 * hold a reference on the transport to make sure none of
  	 * the needed data structures go away.
  	 */
  	list_for_each_entry(t, &asoc->peer.transport_addr_list, transports) {
  
  		if (!mod_timer(&t->hb_timer, sctp_transport_timeout(t)))
  			sctp_transport_hold(t);
  	}
  }
  
  static void sctp_cmd_hb_timers_stop(sctp_cmd_seq_t *cmds,
  				    struct sctp_association *asoc)
  {
  	struct sctp_transport *t;
  
  	/* Stop all heartbeat timers. */
  
  	list_for_each_entry(t, &asoc->peer.transport_addr_list,
  			transports) {
  		if (del_timer(&t->hb_timer))
  			sctp_transport_put(t);
  	}
  }
  
  /* Helper function to stop any pending T3-RTX timers */
  static void sctp_cmd_t3_rtx_timers_stop(sctp_cmd_seq_t *cmds,
  					struct sctp_association *asoc)
  {
  	struct sctp_transport *t;
  
  	list_for_each_entry(t, &asoc->peer.transport_addr_list,
  			transports) {
  		if (del_timer(&t->T3_rtx_timer))
  			sctp_transport_put(t);
  	}
  }
  
  
  /* Helper function to update the heartbeat timer. */
  static void sctp_cmd_hb_timer_update(sctp_cmd_seq_t *cmds,
  				     struct sctp_transport *t)
  {
  	/* Update the heartbeat timer.  */
  	if (!mod_timer(&t->hb_timer, sctp_transport_timeout(t)))
  		sctp_transport_hold(t);
  }
  
  /* Helper function to handle the reception of an HEARTBEAT ACK.  */
  static void sctp_cmd_transport_on(sctp_cmd_seq_t *cmds,
  				  struct sctp_association *asoc,
  				  struct sctp_transport *t,
  				  struct sctp_chunk *chunk)
  {
  	sctp_sender_hb_info_t *hbinfo;
  	int was_unconfirmed = 0;
  
  	/* 8.3 Upon the receipt of the HEARTBEAT ACK, the sender of the
  	 * HEARTBEAT should clear the error counter of the destination
  	 * transport address to which the HEARTBEAT was sent.
  	 */
  	t->error_count = 0;
  
  	/*
  	 * Although RFC4960 specifies that the overall error count must
  	 * be cleared when a HEARTBEAT ACK is received, we make an
  	 * exception while in SHUTDOWN PENDING. If the peer keeps its
  	 * window shut forever, we may never be able to transmit our
  	 * outstanding data and rely on the retransmission limit be reached
  	 * to shutdown the association.
  	 */
  	if (t->asoc->state != SCTP_STATE_SHUTDOWN_PENDING)
  		t->asoc->overall_error_count = 0;
  
  	/* Clear the hb_sent flag to signal that we had a good
  	 * acknowledgement.
  	 */
  	t->hb_sent = 0;
  
  	/* Mark the destination transport address as active if it is not so
  	 * marked.
  	 */
  	if ((t->state == SCTP_INACTIVE) || (t->state == SCTP_UNCONFIRMED)) {
  		was_unconfirmed = 1;
  		sctp_assoc_control_transport(asoc, t, SCTP_TRANSPORT_UP,
  					     SCTP_HEARTBEAT_SUCCESS);
  	}
  
  	if (t->state == SCTP_PF)
  		sctp_assoc_control_transport(asoc, t, SCTP_TRANSPORT_UP,
  					     SCTP_HEARTBEAT_SUCCESS);
  
  	/* HB-ACK was received for a the proper HB.  Consider this
  	 * forward progress.
  	 */
  	if (t->dst)
  		dst_confirm(t->dst);
  
  	/* The receiver of the HEARTBEAT ACK should also perform an
  	 * RTT measurement for that destination transport address
  	 * using the time value carried in the HEARTBEAT ACK chunk.
  	 * If the transport's rto_pending variable has been cleared,
  	 * it was most likely due to a retransmit.  However, we want
  	 * to re-enable it to properly update the rto.
  	 */
  	if (t->rto_pending == 0)
  		t->rto_pending = 1;
  
  	hbinfo = (sctp_sender_hb_info_t *) chunk->skb->data;
  	sctp_transport_update_rto(t, (jiffies - hbinfo->sent_at));
  
  	/* Update the heartbeat timer.  */
  	if (!mod_timer(&t->hb_timer, sctp_transport_timeout(t)))
  		sctp_transport_hold(t);
  
  	if (was_unconfirmed && asoc->peer.transport_count == 1)
  		sctp_transport_immediate_rtx(t);
  }
  
  
  /* Helper function to process the process SACK command.  */
  static int sctp_cmd_process_sack(sctp_cmd_seq_t *cmds,
  				 struct sctp_association *asoc,
  				 struct sctp_chunk *chunk)
  {
  	int err = 0;
  
  	if (sctp_outq_sack(&asoc->outqueue, chunk)) {
  		struct net *net = sock_net(asoc->base.sk);
  
  		/* There are no more TSNs awaiting SACK.  */
  		err = sctp_do_sm(net, SCTP_EVENT_T_OTHER,
  				 SCTP_ST_OTHER(SCTP_EVENT_NO_PENDING_TSN),
  				 asoc->state, asoc->ep, asoc, NULL,
  				 GFP_ATOMIC);
  	}
  
  	return err;
  }
  
  /* Helper function to set the timeout value for T2-SHUTDOWN timer and to set
   * the transport for a shutdown chunk.
   */
  static void sctp_cmd_setup_t2(sctp_cmd_seq_t *cmds,
  			      struct sctp_association *asoc,
  			      struct sctp_chunk *chunk)
  {
  	struct sctp_transport *t;
  
  	if (chunk->transport)
  		t = chunk->transport;
  	else {
  		t = sctp_assoc_choose_alter_transport(asoc,
  					      asoc->shutdown_last_sent_to);
  		chunk->transport = t;
  	}
  	asoc->shutdown_last_sent_to = t;
  	asoc->timeouts[SCTP_EVENT_TIMEOUT_T2_SHUTDOWN] = t->rto;
  }
  
  /* Helper function to change the state of an association. */
  static void sctp_cmd_new_state(sctp_cmd_seq_t *cmds,
  			       struct sctp_association *asoc,
  			       sctp_state_t state)
  {
  	struct sock *sk = asoc->base.sk;
  
  	asoc->state = state;
  
  	pr_debug("%s: asoc:%p[%s]
  ", __func__, asoc, sctp_state_tbl[state]);
  
  	if (sctp_style(sk, TCP)) {
  		/* Change the sk->sk_state of a TCP-style socket that has
  		 * successfully completed a connect() call.
  		 */
  		if (sctp_state(asoc, ESTABLISHED) && sctp_sstate(sk, CLOSED))
  			sk->sk_state = SCTP_SS_ESTABLISHED;
  
  		/* Set the RCV_SHUTDOWN flag when a SHUTDOWN is received. */
  		if (sctp_state(asoc, SHUTDOWN_RECEIVED) &&
  		    sctp_sstate(sk, ESTABLISHED))
  			sk->sk_shutdown |= RCV_SHUTDOWN;
  	}
  
  	if (sctp_state(asoc, COOKIE_WAIT)) {
  		/* Reset init timeouts since they may have been
  		 * increased due to timer expirations.
  		 */
  		asoc->timeouts[SCTP_EVENT_TIMEOUT_T1_INIT] =
  						asoc->rto_initial;
  		asoc->timeouts[SCTP_EVENT_TIMEOUT_T1_COOKIE] =
  						asoc->rto_initial;
  	}
  
  	if (sctp_state(asoc, ESTABLISHED) ||
  	    sctp_state(asoc, CLOSED) ||
  	    sctp_state(asoc, SHUTDOWN_RECEIVED)) {
  		/* Wake up any processes waiting in the asoc's wait queue in
  		 * sctp_wait_for_connect() or sctp_wait_for_sndbuf().
  		 */
  		if (waitqueue_active(&asoc->wait))
  			wake_up_interruptible(&asoc->wait);
  
  		/* Wake up any processes waiting in the sk's sleep queue of
  		 * a TCP-style or UDP-style peeled-off socket in
  		 * sctp_wait_for_accept() or sctp_wait_for_packet().
  		 * For a UDP-style socket, the waiters are woken up by the
  		 * notifications.
  		 */
  		if (!sctp_style(sk, UDP))
  			sk->sk_state_change(sk);
  	}
  }
  
  /* Helper function to delete an association. */
  static void sctp_cmd_delete_tcb(sctp_cmd_seq_t *cmds,
  				struct sctp_association *asoc)
  {
  	struct sock *sk = asoc->base.sk;
  
  	/* If it is a non-temporary association belonging to a TCP-style
  	 * listening socket that is not closed, do not free it so that accept()
  	 * can pick it up later.
  	 */
  	if (sctp_style(sk, TCP) && sctp_sstate(sk, LISTENING) &&
  	    (!asoc->temp) && (sk->sk_shutdown != SHUTDOWN_MASK))
  		return;
  
  	sctp_unhash_established(asoc);
  	sctp_association_free(asoc);
  }
  
  /*
   * ADDIP Section 4.1 ASCONF Chunk Procedures
   * A4) Start a T-4 RTO timer, using the RTO value of the selected
   * destination address (we use active path instead of primary path just
   * because primary path may be inactive.
   */
  static void sctp_cmd_setup_t4(sctp_cmd_seq_t *cmds,
  				struct sctp_association *asoc,
  				struct sctp_chunk *chunk)
  {
  	struct sctp_transport *t;
  
  	t = sctp_assoc_choose_alter_transport(asoc, chunk->transport);
  	asoc->timeouts[SCTP_EVENT_TIMEOUT_T4_RTO] = t->rto;
  	chunk->transport = t;
  }
  
  /* Process an incoming Operation Error Chunk. */
  static void sctp_cmd_process_operr(sctp_cmd_seq_t *cmds,
  				   struct sctp_association *asoc,
  				   struct sctp_chunk *chunk)
  {
  	struct sctp_errhdr *err_hdr;
  	struct sctp_ulpevent *ev;
  
  	while (chunk->chunk_end > chunk->skb->data) {
  		err_hdr = (struct sctp_errhdr *)(chunk->skb->data);
  
  		ev = sctp_ulpevent_make_remote_error(asoc, chunk, 0,
  						     GFP_ATOMIC);
  		if (!ev)
  			return;
  
  		sctp_ulpq_tail_event(&asoc->ulpq, ev);
  
  		switch (err_hdr->cause) {
  		case SCTP_ERROR_UNKNOWN_CHUNK:
  		{
  			sctp_chunkhdr_t *unk_chunk_hdr;
  
  			unk_chunk_hdr = (sctp_chunkhdr_t *)err_hdr->variable;
  			switch (unk_chunk_hdr->type) {
  			/* ADDIP 4.1 A9) If the peer responds to an ASCONF with
  			 * an ERROR chunk reporting that it did not recognized
  			 * the ASCONF chunk type, the sender of the ASCONF MUST
  			 * NOT send any further ASCONF chunks and MUST stop its
  			 * T-4 timer.
  			 */
  			case SCTP_CID_ASCONF:
  				if (asoc->peer.asconf_capable == 0)
  					break;
  
  				asoc->peer.asconf_capable = 0;
  				sctp_add_cmd_sf(cmds, SCTP_CMD_TIMER_STOP,
  					SCTP_TO(SCTP_EVENT_TIMEOUT_T4_RTO));
  				break;
  			default:
  				break;
  			}
  			break;
  		}
  		default:
  			break;
  		}
  	}
  }
  
  /* Process variable FWDTSN chunk information. */
  static void sctp_cmd_process_fwdtsn(struct sctp_ulpq *ulpq,
  				    struct sctp_chunk *chunk)
  {
  	struct sctp_fwdtsn_skip *skip;
  	/* Walk through all the skipped SSNs */
  	sctp_walk_fwdtsn(skip, chunk) {
  		sctp_ulpq_skip(ulpq, ntohs(skip->stream), ntohs(skip->ssn));
  	}
  }
  
  /* Helper function to remove the association non-primary peer
   * transports.
   */
  static void sctp_cmd_del_non_primary(struct sctp_association *asoc)
  {
  	struct sctp_transport *t;
  	struct list_head *pos;
  	struct list_head *temp;
  
  	list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
  		t = list_entry(pos, struct sctp_transport, transports);
  		if (!sctp_cmp_addr_exact(&t->ipaddr,
  					 &asoc->peer.primary_addr)) {
  			sctp_assoc_del_peer(asoc, &t->ipaddr);
  		}
  	}
  }
  
  /* Helper function to set sk_err on a 1-1 style socket. */
  static void sctp_cmd_set_sk_err(struct sctp_association *asoc, int error)
  {
  	struct sock *sk = asoc->base.sk;
  
  	if (!sctp_style(sk, UDP))
  		sk->sk_err = error;
  }
  
  /* Helper function to generate an association change event */
  static void sctp_cmd_assoc_change(sctp_cmd_seq_t *commands,
  				 struct sctp_association *asoc,
  				 u8 state)
  {
  	struct sctp_ulpevent *ev;
  
  	ev = sctp_ulpevent_make_assoc_change(asoc, 0, state, 0,
  					    asoc->c.sinit_num_ostreams,
  					    asoc->c.sinit_max_instreams,
  					    NULL, GFP_ATOMIC);
  	if (ev)
  		sctp_ulpq_tail_event(&asoc->ulpq, ev);
  }
  
  /* Helper function to generate an adaptation indication event */
  static void sctp_cmd_adaptation_ind(sctp_cmd_seq_t *commands,
  				    struct sctp_association *asoc)
  {
  	struct sctp_ulpevent *ev;
  
  	ev = sctp_ulpevent_make_adaptation_indication(asoc, GFP_ATOMIC);
  
  	if (ev)
  		sctp_ulpq_tail_event(&asoc->ulpq, ev);
  }
  
  
  static void sctp_cmd_t1_timer_update(struct sctp_association *asoc,
  				    sctp_event_timeout_t timer,
  				    char *name)
  {
  	struct sctp_transport *t;
  
  	t = asoc->init_last_sent_to;
  	asoc->init_err_counter++;
  
  	if (t->init_sent_count > (asoc->init_cycle + 1)) {
  		asoc->timeouts[timer] *= 2;
  		if (asoc->timeouts[timer] > asoc->max_init_timeo) {
  			asoc->timeouts[timer] = asoc->max_init_timeo;
  		}
  		asoc->init_cycle++;
  
  		pr_debug("%s: T1[%s] timeout adjustment init_err_counter:%d"
  			 " cycle:%d timeout:%ld
  ", __func__, name,
  			 asoc->init_err_counter, asoc->init_cycle,
  			 asoc->timeouts[timer]);
  	}
  
  }
  
  /* Send the whole message, chunk by chunk, to the outqueue.
   * This way the whole message is queued up and bundling if
   * encouraged for small fragments.
   */
  static int sctp_cmd_send_msg(struct sctp_association *asoc,
  				struct sctp_datamsg *msg)
  {
  	struct sctp_chunk *chunk;
  	int error = 0;
  
  	list_for_each_entry(chunk, &msg->chunks, frag_list) {
  		error = sctp_outq_tail(&asoc->outqueue, chunk);
  		if (error)
  			break;
  	}
  
  	return error;
  }
  
  
  /* Sent the next ASCONF packet currently stored in the association.
   * This happens after the ASCONF_ACK was succeffully processed.
   */
  static void sctp_cmd_send_asconf(struct sctp_association *asoc)
  {
  	struct net *net = sock_net(asoc->base.sk);
  
  	/* Send the next asconf chunk from the addip chunk
  	 * queue.
  	 */
  	if (!list_empty(&asoc->addip_chunk_list)) {
  		struct list_head *entry = asoc->addip_chunk_list.next;
  		struct sctp_chunk *asconf = list_entry(entry,
  						struct sctp_chunk, list);
  		list_del_init(entry);
  
  		/* Hold the chunk until an ASCONF_ACK is received. */
  		sctp_chunk_hold(asconf);
  		if (sctp_primitive_ASCONF(net, asoc, asconf))
  			sctp_chunk_free(asconf);
  		else
  			asoc->addip_last_asconf = asconf;
  	}
  }
  
  
  /* These three macros allow us to pull the debugging code out of the
   * main flow of sctp_do_sm() to keep attention focused on the real
   * functionality there.
   */
  #define debug_pre_sfn() \
  	pr_debug("%s[pre-fn]: ep:%p, %s, %s, asoc:%p[%s], %s
  ", __func__, \
  		 ep, sctp_evttype_tbl[event_type], (*debug_fn)(subtype),   \
  		 asoc, sctp_state_tbl[state], state_fn->name)
  
  #define debug_post_sfn() \
  	pr_debug("%s[post-fn]: asoc:%p, status:%s
  ", __func__, asoc, \
  		 sctp_status_tbl[status])
  
  #define debug_post_sfx() \
  	pr_debug("%s[post-sfx]: error:%d, asoc:%p[%s]
  ", __func__, error, \
  		 asoc, sctp_state_tbl[(asoc && sctp_id2assoc(ep->base.sk, \
  		 sctp_assoc2id(asoc))) ? asoc->state : SCTP_STATE_CLOSED])
  
  /*
   * This is the master state machine processing function.
   *
   * If you want to understand all of lksctp, this is a
   * good place to start.
   */
  int sctp_do_sm(struct net *net, sctp_event_t event_type, sctp_subtype_t subtype,
  	       sctp_state_t state,
  	       struct sctp_endpoint *ep,
  	       struct sctp_association *asoc,
  	       void *event_arg,
  	       gfp_t gfp)
  {
  	sctp_cmd_seq_t commands;
  	const sctp_sm_table_entry_t *state_fn;
  	sctp_disposition_t status;
  	int error = 0;
  	typedef const char *(printfn_t)(sctp_subtype_t);
  	static printfn_t *table[] = {
  		NULL, sctp_cname, sctp_tname, sctp_oname, sctp_pname,
  	};
  	printfn_t *debug_fn  __attribute__ ((unused)) = table[event_type];
  
  	/* Look up the state function, run it, and then process the
  	 * side effects.  These three steps are the heart of lksctp.
  	 */
  	state_fn = sctp_sm_lookup_event(net, event_type, state, subtype);
  
  	sctp_init_cmd_seq(&commands);
  
  	debug_pre_sfn();
  	status = state_fn->fn(net, ep, asoc, subtype, event_arg, &commands);
  	debug_post_sfn();
  
  	error = sctp_side_effects(event_type, subtype, state,
  				  ep, asoc, event_arg, status,
  				  &commands, gfp);
  	debug_post_sfx();
  
  	return error;
  }
  
  /*****************************************************************
   * This the master state function side effect processing function.
   *****************************************************************/
  static int sctp_side_effects(sctp_event_t event_type, sctp_subtype_t subtype,
  			     sctp_state_t state,
  			     struct sctp_endpoint *ep,
  			     struct sctp_association *asoc,
  			     void *event_arg,
  			     sctp_disposition_t status,
  			     sctp_cmd_seq_t *commands,
  			     gfp_t gfp)
  {
  	int error;
  
  	/* FIXME - Most of the dispositions left today would be categorized
  	 * as "exceptional" dispositions.  For those dispositions, it
  	 * may not be proper to run through any of the commands at all.
  	 * For example, the command interpreter might be run only with
  	 * disposition SCTP_DISPOSITION_CONSUME.
  	 */
  	if (0 != (error = sctp_cmd_interpreter(event_type, subtype, state,
  					       ep, asoc,
  					       event_arg, status,
  					       commands, gfp)))
  		goto bail;
  
  	switch (status) {
  	case SCTP_DISPOSITION_DISCARD:
  		pr_debug("%s: ignored sctp protocol event - state:%d, "
  			 "event_type:%d, event_id:%d
  ", __func__, state,
  			 event_type, subtype.chunk);
  		break;
  
  	case SCTP_DISPOSITION_NOMEM:
  		/* We ran out of memory, so we need to discard this
  		 * packet.
  		 */
  		/* BUG--we should now recover some memory, probably by
  		 * reneging...
  		 */
  		error = -ENOMEM;
  		break;
  
  	case SCTP_DISPOSITION_DELETE_TCB:
  		/* This should now be a command. */
  		break;
  
  	case SCTP_DISPOSITION_CONSUME:
  	case SCTP_DISPOSITION_ABORT:
  		/*
  		 * We should no longer have much work to do here as the
  		 * real work has been done as explicit commands above.
  		 */
  		break;
  
  	case SCTP_DISPOSITION_VIOLATION:
  		net_err_ratelimited("protocol violation state %d chunkid %d
  ",
  				    state, subtype.chunk);
  		break;
  
  	case SCTP_DISPOSITION_NOT_IMPL:
  		pr_warn("unimplemented feature in state %d, event_type %d, event_id %d
  ",
  			state, event_type, subtype.chunk);
  		break;
  
  	case SCTP_DISPOSITION_BUG:
  		pr_err("bug in state %d, event_type %d, event_id %d
  ",
  		       state, event_type, subtype.chunk);
  		BUG();
  		break;
  
  	default:
  		pr_err("impossible disposition %d in state %d, event_type %d, event_id %d
  ",
  		       status, state, event_type, subtype.chunk);
  		BUG();
  		break;
  	}
  
  bail:
  	return error;
  }
  
  /********************************************************************
   * 2nd Level Abstractions
   ********************************************************************/
  
  /* This is the side-effect interpreter.  */
  static int sctp_cmd_interpreter(sctp_event_t event_type,
  				sctp_subtype_t subtype,
  				sctp_state_t state,
  				struct sctp_endpoint *ep,
  				struct sctp_association *asoc,
  				void *event_arg,
  				sctp_disposition_t status,
  				sctp_cmd_seq_t *commands,
  				gfp_t gfp)
  {
  	int error = 0;
  	int force;
  	sctp_cmd_t *cmd;
  	struct sctp_chunk *new_obj;
  	struct sctp_chunk *chunk = NULL;
  	struct sctp_packet *packet;
  	struct timer_list *timer;
  	unsigned long timeout;
  	struct sctp_transport *t;
  	struct sctp_sackhdr sackh;
  	int local_cork = 0;
  
  	if (SCTP_EVENT_T_TIMEOUT != event_type)
  		chunk = event_arg;
  
  	/* Note:  This whole file is a huge candidate for rework.
  	 * For example, each command could either have its own handler, so
  	 * the loop would look like:
  	 *     while (cmds)
  	 *         cmd->handle(x, y, z)
  	 * --jgrimm
  	 */
  	while (NULL != (cmd = sctp_next_cmd(commands))) {
  		switch (cmd->verb) {
  		case SCTP_CMD_NOP:
  			/* Do nothing. */
  			break;
  
  		case SCTP_CMD_NEW_ASOC:
  			/* Register a new association.  */
  			if (local_cork) {
  				sctp_outq_uncork(&asoc->outqueue);
  				local_cork = 0;
  			}
  
  			/* Register with the endpoint.  */
  			asoc = cmd->obj.asoc;
  			BUG_ON(asoc->peer.primary_path == NULL);
  			sctp_endpoint_add_asoc(ep, asoc);
  			sctp_hash_established(asoc);
  			break;
  
  		case SCTP_CMD_UPDATE_ASSOC:
  		       sctp_assoc_update(asoc, cmd->obj.asoc);
  		       break;
  
  		case SCTP_CMD_PURGE_OUTQUEUE:
  		       sctp_outq_teardown(&asoc->outqueue);
  		       break;
  
  		case SCTP_CMD_DELETE_TCB:
  			if (local_cork) {
  				sctp_outq_uncork(&asoc->outqueue);
  				local_cork = 0;
  			}
  			/* Delete the current association.  */
  			sctp_cmd_delete_tcb(commands, asoc);
  			asoc = NULL;
  			break;
  
  		case SCTP_CMD_NEW_STATE:
  			/* Enter a new state.  */
  			sctp_cmd_new_state(commands, asoc, cmd->obj.state);
  			break;
  
  		case SCTP_CMD_REPORT_TSN:
  			/* Record the arrival of a TSN.  */
  			error = sctp_tsnmap_mark(&asoc->peer.tsn_map,
  						 cmd->obj.u32, NULL);
  			break;
  
  		case SCTP_CMD_REPORT_FWDTSN:
  			/* Move the Cumulattive TSN Ack ahead. */
  			sctp_tsnmap_skip(&asoc->peer.tsn_map, cmd->obj.u32);
  
  			/* purge the fragmentation queue */
  			sctp_ulpq_reasm_flushtsn(&asoc->ulpq, cmd->obj.u32);
  
  			/* Abort any in progress partial delivery. */
  			sctp_ulpq_abort_pd(&asoc->ulpq, GFP_ATOMIC);
  			break;
  
  		case SCTP_CMD_PROCESS_FWDTSN:
  			sctp_cmd_process_fwdtsn(&asoc->ulpq, cmd->obj.chunk);
  			break;
  
  		case SCTP_CMD_GEN_SACK:
  			/* Generate a Selective ACK.
  			 * The argument tells us whether to just count
  			 * the packet and MAYBE generate a SACK, or
  			 * force a SACK out.
  			 */
  			force = cmd->obj.i32;
  			error = sctp_gen_sack(asoc, force, commands);
  			break;
  
  		case SCTP_CMD_PROCESS_SACK:
  			/* Process an inbound SACK.  */
  			error = sctp_cmd_process_sack(commands, asoc,
  						      cmd->obj.chunk);
  			break;
  
  		case SCTP_CMD_GEN_INIT_ACK:
  			/* Generate an INIT ACK chunk.  */
  			new_obj = sctp_make_init_ack(asoc, chunk, GFP_ATOMIC,
  						     0);
  			if (!new_obj)
  				goto nomem;
  
  			sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
  					SCTP_CHUNK(new_obj));
  			break;
  
  		case SCTP_CMD_PEER_INIT:
  			/* Process a unified INIT from the peer.
  			 * Note: Only used during INIT-ACK processing.  If
  			 * there is an error just return to the outter
  			 * layer which will bail.
  			 */
  			error = sctp_cmd_process_init(commands, asoc, chunk,
  						      cmd->obj.init, gfp);
  			break;
  
  		case SCTP_CMD_GEN_COOKIE_ECHO:
  			/* Generate a COOKIE ECHO chunk.  */
  			new_obj = sctp_make_cookie_echo(asoc, chunk);
  			if (!new_obj) {
  				if (cmd->obj.chunk)
  					sctp_chunk_free(cmd->obj.chunk);
  				goto nomem;
  			}
  			sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
  					SCTP_CHUNK(new_obj));
  
  			/* If there is an ERROR chunk to be sent along with
  			 * the COOKIE_ECHO, send it, too.
  			 */
  			if (cmd->obj.chunk)
  				sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
  						SCTP_CHUNK(cmd->obj.chunk));
  
  			if (new_obj->transport) {
  				new_obj->transport->init_sent_count++;
  				asoc->init_last_sent_to = new_obj->transport;
  			}
  
  			/* FIXME - Eventually come up with a cleaner way to
  			 * enabling COOKIE-ECHO + DATA bundling during
  			 * multihoming stale cookie scenarios, the following
  			 * command plays with asoc->peer.retran_path to
  			 * avoid the problem of sending the COOKIE-ECHO and
  			 * DATA in different paths, which could result
  			 * in the association being ABORTed if the DATA chunk
  			 * is processed first by the server.  Checking the
  			 * init error counter simply causes this command
  			 * to be executed only during failed attempts of
  			 * association establishment.
  			 */
  			if ((asoc->peer.retran_path !=
  			     asoc->peer.primary_path) &&
  			    (asoc->init_err_counter > 0)) {
  				sctp_add_cmd_sf(commands,
  						SCTP_CMD_FORCE_PRIM_RETRAN,
  						SCTP_NULL());
  			}
  
  			break;
  
  		case SCTP_CMD_GEN_SHUTDOWN:
  			/* Generate SHUTDOWN when in SHUTDOWN_SENT state.
  			 * Reset error counts.
  			 */
  			asoc->overall_error_count = 0;
  
  			/* Generate a SHUTDOWN chunk.  */
  			new_obj = sctp_make_shutdown(asoc, chunk);
  			if (!new_obj)
  				goto nomem;
  			sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
  					SCTP_CHUNK(new_obj));
  			break;
  
  		case SCTP_CMD_CHUNK_ULP:
  			/* Send a chunk to the sockets layer.  */
  			pr_debug("%s: sm_sideff: chunk_up:%p, ulpq:%p
  ",
  				 __func__, cmd->obj.chunk, &asoc->ulpq);
  
  			sctp_ulpq_tail_data(&asoc->ulpq, cmd->obj.chunk,
  					    GFP_ATOMIC);
  			break;
  
  		case SCTP_CMD_EVENT_ULP:
  			/* Send a notification to the sockets layer.  */
  			pr_debug("%s: sm_sideff: event_up:%p, ulpq:%p
  ",
  				 __func__, cmd->obj.ulpevent, &asoc->ulpq);
  
  			sctp_ulpq_tail_event(&asoc->ulpq, cmd->obj.ulpevent);
  			break;
  
  		case SCTP_CMD_REPLY:
  			/* If an caller has not already corked, do cork. */
  			if (!asoc->outqueue.cork) {
  				sctp_outq_cork(&asoc->outqueue);
  				local_cork = 1;
  			}
  			/* Send a chunk to our peer.  */
  			error = sctp_outq_tail(&asoc->outqueue, cmd->obj.chunk);
  			break;
  
  		case SCTP_CMD_SEND_PKT:
  			/* Send a full packet to our peer.  */
  			packet = cmd->obj.packet;
  			sctp_packet_transmit(packet);
  			sctp_ootb_pkt_free(packet);
  			break;
  
  		case SCTP_CMD_T1_RETRAN:
  			/* Mark a transport for retransmission.  */
  			sctp_retransmit(&asoc->outqueue, cmd->obj.transport,
  					SCTP_RTXR_T1_RTX);
  			break;
  
  		case SCTP_CMD_RETRAN:
  			/* Mark a transport for retransmission.  */
  			sctp_retransmit(&asoc->outqueue, cmd->obj.transport,
  					SCTP_RTXR_T3_RTX);
  			break;
  
  		case SCTP_CMD_ECN_CE:
  			/* Do delayed CE processing.   */
  			sctp_do_ecn_ce_work(asoc, cmd->obj.u32);
  			break;
  
  		case SCTP_CMD_ECN_ECNE:
  			/* Do delayed ECNE processing. */
  			new_obj = sctp_do_ecn_ecne_work(asoc, cmd->obj.u32,
  							chunk);
  			if (new_obj)
  				sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
  						SCTP_CHUNK(new_obj));
  			break;
  
  		case SCTP_CMD_ECN_CWR:
  			/* Do delayed CWR processing.  */
  			sctp_do_ecn_cwr_work(asoc, cmd->obj.u32);
  			break;
  
  		case SCTP_CMD_SETUP_T2:
  			sctp_cmd_setup_t2(commands, asoc, cmd->obj.chunk);
  			break;
  
  		case SCTP_CMD_TIMER_START_ONCE:
  			timer = &asoc->timers[cmd->obj.to];
  
  			if (timer_pending(timer))
  				break;
  			/* fall through */
  
  		case SCTP_CMD_TIMER_START:
  			timer = &asoc->timers[cmd->obj.to];
  			timeout = asoc->timeouts[cmd->obj.to];
  			BUG_ON(!timeout);
  
  			timer->expires = jiffies + timeout;
  			sctp_association_hold(asoc);
  			add_timer(timer);
  			break;
  
  		case SCTP_CMD_TIMER_RESTART:
  			timer = &asoc->timers[cmd->obj.to];
  			timeout = asoc->timeouts[cmd->obj.to];
  			if (!mod_timer(timer, jiffies + timeout))
  				sctp_association_hold(asoc);
  			break;
  
  		case SCTP_CMD_TIMER_STOP:
  			timer = &asoc->timers[cmd->obj.to];
  			if (del_timer(timer))
  				sctp_association_put(asoc);
  			break;
  
  		case SCTP_CMD_INIT_CHOOSE_TRANSPORT:
  			chunk = cmd->obj.chunk;
  			t = sctp_assoc_choose_alter_transport(asoc,
  						asoc->init_last_sent_to);
  			asoc->init_last_sent_to = t;
  			chunk->transport = t;
  			t->init_sent_count++;
  			/* Set the new transport as primary */
  			sctp_assoc_set_primary(asoc, t);
  			break;
  
  		case SCTP_CMD_INIT_RESTART:
  			/* Do the needed accounting and updates
  			 * associated with restarting an initialization
  			 * timer. Only multiply the timeout by two if
  			 * all transports have been tried at the current
  			 * timeout.
  			 */
  			sctp_cmd_t1_timer_update(asoc,
  						SCTP_EVENT_TIMEOUT_T1_INIT,
  						"INIT");
  
  			sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_RESTART,
  					SCTP_TO(SCTP_EVENT_TIMEOUT_T1_INIT));
  			break;
  
  		case SCTP_CMD_COOKIEECHO_RESTART:
  			/* Do the needed accounting and updates
  			 * associated with restarting an initialization
  			 * timer. Only multiply the timeout by two if
  			 * all transports have been tried at the current
  			 * timeout.
  			 */
  			sctp_cmd_t1_timer_update(asoc,
  						SCTP_EVENT_TIMEOUT_T1_COOKIE,
  						"COOKIE");
  
  			/* If we've sent any data bundled with
  			 * COOKIE-ECHO we need to resend.
  			 */
  			list_for_each_entry(t, &asoc->peer.transport_addr_list,
  					transports) {
  				sctp_retransmit_mark(&asoc->outqueue, t,
  					    SCTP_RTXR_T1_RTX);
  			}
  
  			sctp_add_cmd_sf(commands,
  					SCTP_CMD_TIMER_RESTART,
  					SCTP_TO(SCTP_EVENT_TIMEOUT_T1_COOKIE));
  			break;
  
  		case SCTP_CMD_INIT_FAILED:
  			sctp_cmd_init_failed(commands, asoc, cmd->obj.err);
  			break;
  
  		case SCTP_CMD_ASSOC_FAILED:
  			sctp_cmd_assoc_failed(commands, asoc, event_type,
  					      subtype, chunk, cmd->obj.err);
  			break;
  
  		case SCTP_CMD_INIT_COUNTER_INC:
  			asoc->init_err_counter++;
  			break;
  
  		case SCTP_CMD_INIT_COUNTER_RESET:
  			asoc->init_err_counter = 0;
  			asoc->init_cycle = 0;
  			list_for_each_entry(t, &asoc->peer.transport_addr_list,
  					    transports) {
  				t->init_sent_count = 0;
  			}
  			break;
  
  		case SCTP_CMD_REPORT_DUP:
  			sctp_tsnmap_mark_dup(&asoc->peer.tsn_map,
  					     cmd->obj.u32);
  			break;
  
  		case SCTP_CMD_REPORT_BAD_TAG:
  			pr_debug("%s: vtag mismatch!
  ", __func__);
  			break;
  
  		case SCTP_CMD_STRIKE:
  			/* Mark one strike against a transport.  */
  			sctp_do_8_2_transport_strike(commands, asoc,
  						    cmd->obj.transport, 0);
  			break;
  
  		case SCTP_CMD_TRANSPORT_IDLE:
  			t = cmd->obj.transport;
  			sctp_transport_lower_cwnd(t, SCTP_LOWER_CWND_INACTIVE);
  			break;
  
  		case SCTP_CMD_TRANSPORT_HB_SENT:
  			t = cmd->obj.transport;
  			sctp_do_8_2_transport_strike(commands, asoc,
  						     t, 1);
  			t->hb_sent = 1;
  			break;
  
  		case SCTP_CMD_TRANSPORT_ON:
  			t = cmd->obj.transport;
  			sctp_cmd_transport_on(commands, asoc, t, chunk);
  			break;
  
  		case SCTP_CMD_HB_TIMERS_START:
  			sctp_cmd_hb_timers_start(commands, asoc);
  			break;
  
  		case SCTP_CMD_HB_TIMER_UPDATE:
  			t = cmd->obj.transport;
  			sctp_cmd_hb_timer_update(commands, t);
  			break;
  
  		case SCTP_CMD_HB_TIMERS_STOP:
  			sctp_cmd_hb_timers_stop(commands, asoc);
  			break;
  
  		case SCTP_CMD_REPORT_ERROR:
  			error = cmd->obj.error;
  			break;
  
  		case SCTP_CMD_PROCESS_CTSN:
  			/* Dummy up a SACK for processing. */
  			sackh.cum_tsn_ack = cmd->obj.be32;
  			sackh.a_rwnd = asoc->peer.rwnd +
  					asoc->outqueue.outstanding_bytes;
  			sackh.num_gap_ack_blocks = 0;
  			sackh.num_dup_tsns = 0;
  			chunk->subh.sack_hdr = &sackh;
  			sctp_add_cmd_sf(commands, SCTP_CMD_PROCESS_SACK,
  					SCTP_CHUNK(chunk));
  			break;
  
  		case SCTP_CMD_DISCARD_PACKET:
  			/* We need to discard the whole packet.
  			 * Uncork the queue since there might be
  			 * responses pending
  			 */
  			chunk->pdiscard = 1;
  			if (asoc) {
  				sctp_outq_uncork(&asoc->outqueue);
  				local_cork = 0;
  			}
  			break;
  
  		case SCTP_CMD_RTO_PENDING:
  			t = cmd->obj.transport;
  			t->rto_pending = 1;
  			break;
  
  		case SCTP_CMD_PART_DELIVER:
  			sctp_ulpq_partial_delivery(&asoc->ulpq, GFP_ATOMIC);
  			break;
  
  		case SCTP_CMD_RENEGE:
  			sctp_ulpq_renege(&asoc->ulpq, cmd->obj.chunk,
  					 GFP_ATOMIC);
  			break;
  
  		case SCTP_CMD_SETUP_T4:
  			sctp_cmd_setup_t4(commands, asoc, cmd->obj.chunk);
  			break;
  
  		case SCTP_CMD_PROCESS_OPERR:
  			sctp_cmd_process_operr(commands, asoc, chunk);
  			break;
  		case SCTP_CMD_CLEAR_INIT_TAG:
  			asoc->peer.i.init_tag = 0;
  			break;
  		case SCTP_CMD_DEL_NON_PRIMARY:
  			sctp_cmd_del_non_primary(asoc);
  			break;
  		case SCTP_CMD_T3_RTX_TIMERS_STOP:
  			sctp_cmd_t3_rtx_timers_stop(commands, asoc);
  			break;
  		case SCTP_CMD_FORCE_PRIM_RETRAN:
  			t = asoc->peer.retran_path;
  			asoc->peer.retran_path = asoc->peer.primary_path;
  			error = sctp_outq_uncork(&asoc->outqueue);
  			local_cork = 0;
  			asoc->peer.retran_path = t;
  			break;
  		case SCTP_CMD_SET_SK_ERR:
  			sctp_cmd_set_sk_err(asoc, cmd->obj.error);
  			break;
  		case SCTP_CMD_ASSOC_CHANGE:
  			sctp_cmd_assoc_change(commands, asoc,
  					      cmd->obj.u8);
  			break;
  		case SCTP_CMD_ADAPTATION_IND:
  			sctp_cmd_adaptation_ind(commands, asoc);
  			break;
  
  		case SCTP_CMD_ASSOC_SHKEY:
  			error = sctp_auth_asoc_init_active_key(asoc,
  						GFP_ATOMIC);
  			break;
  		case SCTP_CMD_UPDATE_INITTAG:
  			asoc->peer.i.init_tag = cmd->obj.u32;
  			break;
  		case SCTP_CMD_SEND_MSG:
  			if (!asoc->outqueue.cork) {
  				sctp_outq_cork(&asoc->outqueue);
  				local_cork = 1;
  			}
  			error = sctp_cmd_send_msg(asoc, cmd->obj.msg);
  			break;
  		case SCTP_CMD_SEND_NEXT_ASCONF:
  			sctp_cmd_send_asconf(asoc);
  			break;
  		case SCTP_CMD_PURGE_ASCONF_QUEUE:
  			sctp_asconf_queue_teardown(asoc);
  			break;
  
  		case SCTP_CMD_SET_ASOC:
  			asoc = cmd->obj.asoc;
  			break;
  
  		default:
  			pr_warn("Impossible command: %u
  ",
  				cmd->verb);
  			break;
  		}
  
  		if (error)
  			break;
  	}
  
  out:
  	/* If this is in response to a received chunk, wait until
  	 * we are done with the packet to open the queue so that we don't
  	 * send multiple packets in response to a single request.
  	 */
  	if (asoc && SCTP_EVENT_T_CHUNK == event_type && chunk) {
  		if (chunk->end_of_packet || chunk->singleton)
  			error = sctp_outq_uncork(&asoc->outqueue);
  	} else if (local_cork)
  		error = sctp_outq_uncork(&asoc->outqueue);
  	return error;
  nomem:
  	error = -ENOMEM;
  	goto out;
  }