initial commit with v2.6.9

[linux-2.6.9-moxart.git] / net / sctp / sm_sideeffect.c

/* SCTP kernel reference 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 reference 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.
 *
 * The SCTP reference 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.
 *
 * The SCTP reference 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@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>
 *
 * Any bugs reported given to us we will try to fix... any fixes shared will
 * be incorporated into the next SCTP release.
 */

#include <linux/skbuff.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/ip.h>
#include <net/sock.h>
#include <net/sctp/sctp.h>
#include <net/sctp/sm.h>

/********************************************************************
 * 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.  */
int sctp_gen_sack(struct sctp_association *asoc, int force,
                  sctp_cmd_seq_t *commands)
{
        __u32 ctsn, max_tsn_seen;
        struct sctp_chunk *sack;
        int error = 0;

        if (force)
                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) {
                /* We will need a SACK for the next packet.  */
                asoc->peer.sack_needed = 1;
                goto out;
        } else {
                if (asoc->a_rwnd > asoc->rwnd)
                        asoc->a_rwnd = asoc->rwnd;
                sack = sctp_make_sack(asoc);
                if (!sack)
                        goto nomem;

                asoc->peer.sack_needed = 0;

                error = sctp_outq_tail(&asoc->outqueue, sack);

                /* Stop the SACK timer.  */
                sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
                                SCTP_TO(SCTP_EVENT_TIMEOUT_SACK));
        }
out:
        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;

        /* Check whether a task is in the sock.  */

        sctp_bh_lock_sock(asoc->base.sk);
        if (sock_owned_by_user(asoc->base.sk)) {
                SCTP_DEBUG_PRINTK("%s:Sock is busy.\n", __FUNCTION__);

                /* 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(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:
        sctp_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)
{
        int error = 0;

        sctp_bh_lock_sock(asoc->base.sk);
        if (sock_owned_by_user(asoc->base.sk)) {
                SCTP_DEBUG_PRINTK("%s:Sock is busy: timer %d\n",
                                  __FUNCTION__,
                                  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(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:
        sctp_bh_unlock_sock(asoc->base.sk);
        sctp_association_put(asoc);
}

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);
}

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);
}

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);
}

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);
}

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() */

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;

        sctp_bh_lock_sock(asoc->base.sk);
        if (sock_owned_by_user(asoc->base.sk)) {
                SCTP_DEBUG_PRINTK("%s:Sock is busy.\n", __FUNCTION__);

                /* 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(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:
        sctp_bh_unlock_sock(asoc->base.sk);
        sctp_transport_put(transport);
}

/* Inject a SACK Timeout event into the state machine.  */
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,
        sctp_generate_heartbeat_event,
        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(struct sctp_association *asoc,
                                         struct sctp_transport *transport)
{
        /* The check for association's overall error counter exceeding the
         * threshold is done in the state function.
         */
        asoc->overall_error_count++;

        if (transport->active &&
            (transport->error_count++ >= transport->error_threshold)) {
                SCTP_DEBUG_PRINTK("transport_strike: transport "
                                  "IP:%d.%d.%d.%d failed.\n",
                                  NIPQUAD(transport->ipaddr.v4.sin_addr));
                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.
         */
        transport->rto = min((transport->rto * 2), transport->asoc->rto_max);
}

/* Worker routine to handle INIT command failure.  */
static void sctp_cmd_init_failed(sctp_cmd_seq_t *commands,
                                 struct sctp_association *asoc,
                                 unsigned error)
{
        struct sctp_ulpevent *event;

        event = sctp_ulpevent_make_assoc_change(asoc,0, SCTP_CANT_STR_ASSOC,
                                                (__u16)error, 0, 0,
                                                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 error)
{
        struct sctp_ulpevent *event;

        /* Cancel any partial delivery in progress. */
        sctp_ulpq_abort_pd(&asoc->ulpq, GFP_ATOMIC);

        event = sctp_ulpevent_make_assoc_change(asoc, 0, SCTP_COMM_LOST,
                                                (__u16)error, 0, 0,
                                                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));

        /* Set sk_err to ECONNRESET on a 1-1 style socket. */
        if (!sctp_style(asoc->base.sk, UDP))
                asoc->base.sk->sk_err = ECONNRESET; 

        /* 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, int 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->chunk_hdr->type,
                               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;
        struct list_head *pos;

        /* 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(pos, &asoc->peer.transport_addr_list) {
                t = list_entry(pos, struct sctp_transport, 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;
        struct list_head *pos;

        /* Stop all heartbeat timers. */

        list_for_each(pos, &asoc->peer.transport_addr_list) {
                t = list_entry(pos, struct sctp_transport, 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;
        struct list_head *pos;

        list_for_each(pos, &asoc->peer.transport_addr_list) {
                t = list_entry(pos, struct sctp_transport, transports);
                if (timer_pending(&t->T3_rtx_timer) &&
                    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_association *asoc,
                                     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;

        /* 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.
         * The association's overall error count is also cleared.
         */
        t->error_count = 0;
        t->asoc->overall_error_count = 0;

        /* Mark the destination transport address as active if it is not so
         * marked.
         */
        if (!t->active)
                sctp_assoc_control_transport(asoc, t, SCTP_TRANSPORT_UP,
                                             SCTP_HEARTBEAT_SUCCESS);

        /* 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.
         */
        hbinfo = (sctp_sender_hb_info_t *) chunk->skb->data;
        sctp_transport_update_rto(t, (jiffies - hbinfo->sent_at));
}

/* Helper function to do a transport reset at the expiry of the hearbeat
 * timer.
 */
static void sctp_cmd_transport_reset(sctp_cmd_seq_t *cmds,
                                     struct sctp_association *asoc,
                                     struct sctp_transport *t)
{
        sctp_transport_lower_cwnd(t, SCTP_LOWER_CWND_INACTIVE);

        /* Mark one strike against a transport.  */
        sctp_do_8_2_transport_strike(asoc, 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_sackhdr *sackh)
{
        int err;

        if (sctp_outq_sack(&asoc->outqueue, sackh)) {
                /* There are no more TSNs awaiting SACK.  */
                err = sctp_do_sm(SCTP_EVENT_T_OTHER,
                                 SCTP_ST_OTHER(SCTP_EVENT_NO_PENDING_TSN),
                                 asoc->state, asoc->ep, asoc, NULL,
                                 GFP_ATOMIC);
        } else {
                /* Windows may have opened, so we need
                 * to check if we have DATA to transmit
                 */
                err = sctp_outq_flush(&asoc->outqueue, 0);
        }

        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;

        t = sctp_assoc_choose_shutdown_transport(asoc);
        asoc->shutdown_last_sent_to = t;
        asoc->timeouts[SCTP_EVENT_TIMEOUT_T2_SHUTDOWN] = t->rto;
        chunk->transport = t;
}

/* 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;

        if (sctp_style(sk, TCP)) {
                /* Change the sk->sk_state of a TCP-style socket that has 
                 * sucessfully 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, 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 = asoc->peer.active_path;
        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_operr_chunk *operr_chunk;
        struct sctp_errhdr *err_hdr;

        operr_chunk = (struct sctp_operr_chunk *)chunk->chunk_hdr;
        err_hdr = &operr_chunk->err_hdr;

        switch (err_hdr->cause) {
        case SCTP_ERROR_UNKNOWN_CHUNK:
        {
                struct sctp_chunkhdr *unk_chunk_hdr;

                unk_chunk_hdr = (struct sctp_chunkhdr *)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:
                        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));
        }

        return;
}

/* 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);
                }
        }

        return;
}

/* 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 \
        SCTP_DEBUG_PRINTK("sctp_do_sm prefn: " \
                          "ep %p, %s, %s, asoc %p[%s], %s\n", \
                          ep, sctp_evttype_tbl[event_type], \
                          (*debug_fn)(subtype), asoc, \
                          sctp_state_tbl[state], state_fn->name)

#define DEBUG_POST \
        SCTP_DEBUG_PRINTK("sctp_do_sm postfn: " \
                          "asoc %p, status: %s\n", \
                          asoc, sctp_status_tbl[status])

#define DEBUG_POST_SFX \
        SCTP_DEBUG_PRINTK("sctp_do_sm post sfx: error %d, asoc %p[%s]\n", \
                          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(sctp_event_t event_type, sctp_subtype_t subtype,
               sctp_state_t state,
               struct sctp_endpoint *ep,
               struct sctp_association *asoc,
               void *event_arg,
               int 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(event_type, state, subtype);

        sctp_init_cmd_seq(&commands);

        DEBUG_PRE;
        status = (*state_fn->fn)(ep, asoc, subtype, event_arg, &commands);
        DEBUG_POST;

        error = sctp_side_effects(event_type, subtype, state,
                                  ep, asoc, event_arg, status, 
                                  &commands, gfp);
        DEBUG_POST_SFX;

        return error;
}

#undef DEBUG_PRE
#undef DEBUG_POST

/*****************************************************************
 * This the master state function side effect processing function.
 *****************************************************************/
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,
                      int 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:
                SCTP_DEBUG_PRINTK("Ignored sctp protocol event - state %d, "
                                  "event_type %d, event_id %d\n",
                                  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:
                printk(KERN_ERR "sctp protocol violation state %d "
                       "chunkid %d\n", state, subtype.chunk);
                break;

        case SCTP_DISPOSITION_NOT_IMPL:
                printk(KERN_WARNING "sctp unimplemented feature in state %d, "
                       "event_type %d, event_id %d\n",
                       state, event_type, subtype.chunk);
                break;

        case SCTP_DISPOSITION_BUG:
                printk(KERN_ERR "sctp bug in state %d, "
                       "event_type %d, event_id %d\n",
                       state, event_type, subtype.chunk);
                BUG();
                break;

        default:
                printk(KERN_ERR "sctp impossible disposition %d "
                       "in state %d, event_type %d, event_id %d\n",
                       status, state, event_type, subtype.chunk);
                BUG();
                break;
        };

bail:
        return error;
}

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

/* This is the side-effect interpreter.  */
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,
                         int 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 list_head *pos;
        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 = (struct sctp_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;
                        }
                        asoc = cmd->obj.ptr;
                        /* Register with the endpoint.  */
                        sctp_endpoint_add_asoc(ep, asoc);
                        sctp_hash_established(asoc);
                        break;

                case SCTP_CMD_UPDATE_ASSOC:
                       sctp_assoc_update(asoc, cmd->obj.ptr);
                       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.  */
                        sctp_tsnmap_mark(&asoc->peer.tsn_map, cmd->obj.u32);
                        break;

                case SCTP_CMD_REPORT_FWDTSN:
                        /* Move the Cumulattive TSN Ack ahead. */
                        sctp_tsnmap_skip(&asoc->peer.tsn_map, 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.ptr);
                        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.ptr);
                        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.ptr, 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.ptr)
                                        sctp_chunk_free(cmd->obj.ptr);
                                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.ptr)
                                sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
                                                SCTP_CHUNK(cmd->obj.ptr));

                        /* 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->counters[SCTP_COUNTER_INIT_ERROR] > 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.  */
                        SCTP_DEBUG_PRINTK("sm_sideff: %s %p, %s %p.\n",
                                          "chunk_up:", cmd->obj.ptr,
                                          "ulpq:", &asoc->ulpq);
                        sctp_ulpq_tail_data(&asoc->ulpq, cmd->obj.ptr,
                                            GFP_ATOMIC);
                        break;

                case SCTP_CMD_EVENT_ULP:
                        /* Send a notification to the sockets layer.  */
                        SCTP_DEBUG_PRINTK("sm_sideff: %s %p, %s %p.\n",
                                          "event_up:",cmd->obj.ptr,
                                          "ulpq:",&asoc->ulpq);
                        sctp_ulpq_tail_event(&asoc->ulpq, cmd->obj.ptr);
                        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.ptr);
                        break;

                case SCTP_CMD_SEND_PKT:
                        /* Send a full packet to our peer.  */
                        packet = cmd->obj.ptr;
                        sctp_packet_transmit(packet);
                        sctp_ootb_pkt_free(packet);
                        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_TRANSMIT:
                        /* Kick start transmission. */
                        error = sctp_outq_uncork(&asoc->outqueue);
                        local_cork = 0;
                        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.ptr);
                        break;

                case SCTP_CMD_TIMER_START:
                        timer = &asoc->timers[cmd->obj.to];
                        timeout = asoc->timeouts[cmd->obj.to];
                        if (!timeout)
                                BUG();

                        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 (timer_pending(timer) && del_timer(timer))
                                sctp_association_put(asoc);
                        break;

                case SCTP_CMD_INIT_RESTART:
                        /* Do the needed accounting and updates
                         * associated with restarting an initialization
                         * timer.
                         */
                        asoc->counters[SCTP_COUNTER_INIT_ERROR]++;
                        asoc->timeouts[cmd->obj.to] *= 2;
                        if (asoc->timeouts[cmd->obj.to] >
                            asoc->max_init_timeo) {
                                asoc->timeouts[cmd->obj.to] =
                                        asoc->max_init_timeo;
                        }

                        /* If we've sent any data bundled with
                         * COOKIE-ECHO we need to resend.
                         */
                        list_for_each(pos, &asoc->peer.transport_addr_list) {
                                t = list_entry(pos, struct sctp_transport,
                                               transports);
                                sctp_retransmit_mark(&asoc->outqueue, t, 0);
                        }

                        sctp_add_cmd_sf(commands,
                                        SCTP_CMD_TIMER_RESTART,
                                        SCTP_TO(cmd->obj.to));
                        break;

                case SCTP_CMD_INIT_FAILED:
                        sctp_cmd_init_failed(commands, asoc, cmd->obj.u32);
                        break;

                case SCTP_CMD_ASSOC_FAILED:
                        sctp_cmd_assoc_failed(commands, asoc, event_type,
                                              subtype, chunk, cmd->obj.u32);
                        break;

                case SCTP_CMD_COUNTER_INC:
                        asoc->counters[cmd->obj.counter]++;
                        break;

                case SCTP_CMD_COUNTER_RESET:
                        asoc->counters[cmd->obj.counter] = 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:
                        SCTP_DEBUG_PRINTK("vtag mismatch!\n");
                        break;

                case SCTP_CMD_STRIKE:
                        /* Mark one strike against a transport.  */
                        sctp_do_8_2_transport_strike(asoc, cmd->obj.transport);
                        break;

                case SCTP_CMD_TRANSPORT_RESET:
                        t = cmd->obj.transport;
                        sctp_cmd_transport_reset(commands, asoc, t);
                        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, asoc, 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.u32;
                        sackh.a_rwnd = 0;
                        sackh.num_gap_ack_blocks = 0;
                        sackh.num_dup_tsns = 0;
                        sctp_add_cmd_sf(commands, SCTP_CMD_PROCESS_SACK,
                                        SCTP_SACKH(&sackh));
                        break;

                case SCTP_CMD_DISCARD_PACKET:
                        /* We need to discard the whole packet.  */
                        chunk->pdiscard = 1;
                        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, cmd->obj.ptr,
                                                   GFP_ATOMIC);
                        break;

                case SCTP_CMD_RENEGE:
                        sctp_ulpq_renege(&asoc->ulpq, cmd->obj.ptr,
                                         GFP_ATOMIC);
                        break;

                case SCTP_CMD_SETUP_T4:
                        sctp_cmd_setup_t4(commands, asoc, cmd->obj.ptr);
                        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;
                default:
                        printk(KERN_WARNING "Impossible command: %u, %p\n",
                               cmd->verb, cmd->obj.ptr);
                        break;
                };
                if (error)
                        break;
        }

out:
        if (local_cork)
                sctp_outq_uncork(&asoc->outqueue);
        return error;
nomem:
        error = -ENOMEM;
        goto out;
}