patch-2.4.23 linux-2.4.23/net/sctp/sm_sideeffect.c

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diff -urN linux-2.4.22/net/sctp/sm_sideeffect.c linux-2.4.23/net/sctp/sm_sideeffect.c
@@ -0,0 +1,1185 @@
+/* SCTP kernel reference Implementation
+ * Copyright (c) 1999 Cisco, Inc.
+ * Copyright (c) 1999-2001 Motorola, Inc.
+ * Copyright (c) 2001-2002 International Business Machines Corp.
+ *
+ * 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 sctp_chunk_t *sctp_do_ecn_ecne_work(struct sctp_association *asoc,
+					   __u32 lowest_tsn,
+					   sctp_chunk_t *chunk)
+{
+	sctp_chunk_t *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->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->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_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->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_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,
+						0, 0, 0, GFP_ATOMIC);
+
+	if (event)
+		sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP,
+				SCTP_ULPEVENT(event));
+
+	/* 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));
+
+	/* 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 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,
+				  sctp_chunk_t *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,
+				 sctp_sackhdr_t *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,
+			      sctp_chunk_t *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;
+	struct sctp_opt *sp = sctp_sk(sk);
+
+	asoc->state = state;
+	asoc->state_timestamp = jiffies;
+
+	if (SCTP_SOCKET_TCP == sp->type) {
+		/* Change the sk->state of a TCP-style socket that has 
+		 * sucessfully completed a connect() call.
+		 */
+		if ((SCTP_STATE_ESTABLISHED == asoc->state) &&
+		    (SCTP_SS_CLOSED == sk->state))
+			sk->state = SCTP_SS_ESTABLISHED;
+
+		/* Set the RCV_SHUTDOWN flag when a SHUTDOWN is received. */
+		if (SCTP_STATE_SHUTDOWN_RECEIVED == asoc->state)
+			sk->shutdown |= RCV_SHUTDOWN;
+
+	}
+
+	if ((SCTP_STATE_ESTABLISHED == asoc->state) ||
+	    (SCTP_STATE_CLOSED == asoc->state) ||
+	    (SCTP_STATE_SHUTDOWN_RECEIVED == asoc->state)) {
+		/* 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_SOCKET_UDP != sp->type)
+			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, do not free it so that accept() can pick it
+	 * up later.
+	 */
+	if ((SCTP_SOCKET_TCP == sctp_sk(sk)->type) &&
+	    (SCTP_SS_LISTENING == sk->state) && (!asoc->temp))
+		return;
+
+	sctp_unhash_established(asoc);
+	sctp_association_free(asoc);
+}
+
+/* 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;
+	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;
+	sctp_chunk_t *new_obj;
+	sctp_chunk_t *chunk = NULL;
+	struct sctp_packet *packet;
+	struct list_head *pos;
+	struct timer_list *timer;
+	unsigned long timeout;
+	struct sctp_transport *t;
+	sctp_sackhdr_t sackh;
+
+	if(SCTP_EVENT_T_TIMEOUT != event_type)
+		chunk = (sctp_chunk_t *) 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.  */
+			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:
+			/* 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_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_free_chunk(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));
+			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);
+			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:
+			/* 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_flush(&asoc->outqueue, 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;
+
+		default:
+			printk(KERN_WARNING "Impossible command: %u, %p\n",
+			       cmd->verb, cmd->obj.ptr);
+			break;
+		};
+		if (error)
+			return error;
+	}
+
+	return error;
+
+nomem:
+	error = -ENOMEM;
+	return error;
+}
+

FUNET's LINUX-ADM group, linux-adm@nic.funet.fi
TCL-scripts by Sam Shen (who was at: slshen@lbl.gov)