Linux-2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 1205 insertions, 0 deletions

diff --git a/net/sctp/associola.c b/net/sctp/associola.c
new file mode 100644
index 000000000000..663843d97a92
--- /dev/null
+++ b/net/sctp/associola.c
@@ -0,0 +1,1205 @@
+/* SCTP kernel reference Implementation
+ * (C) Copyright IBM Corp. 2001, 2004
+ * Copyright (c) 1999-2000 Cisco, Inc.
+ * Copyright (c) 1999-2001 Motorola, Inc.
+ * Copyright (c) 2001 Intel Corp.
+ * Copyright (c) 2001 La Monte H.P. Yarroll
+ *
+ * This file is part of the SCTP kernel reference Implementation
+ *
+ * This module provides the abstraction for an SCTP association.
+ *
+ * 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@us.ibm.com>
+ *    Xingang Guo           <xingang.guo@intel.com>
+ *    Hui Huang             <hui.huang@nokia.com>
+ *    Sridhar Samudrala	    <sri@us.ibm.com>
+ *    Daisy Chang	    <daisyc@us.ibm.com>
+ *    Ryan Layer	    <rmlayer@us.ibm.com>
+ *    Kevin Gao             <kevin.gao@intel.com>
+ *
+ * Any bugs reported given to us we will try to fix... any fixes shared will
+ * be incorporated into the next SCTP release.
+ */
+
+#include <linux/types.h>
+#include <linux/fcntl.h>
+#include <linux/poll.h>
+#include <linux/init.h>
+#include <linux/sched.h>
+
+#include <linux/slab.h>
+#include <linux/in.h>
+#include <net/ipv6.h>
+#include <net/sctp/sctp.h>
+#include <net/sctp/sm.h>
+
+/* Forward declarations for internal functions. */
+static void sctp_assoc_bh_rcv(struct sctp_association *asoc);
+
+
+/* 1st Level Abstractions. */
+
+/* Initialize a new association from provided memory. */
+static struct sctp_association *sctp_association_init(struct sctp_association *asoc,
+					  const struct sctp_endpoint *ep,
+					  const struct sock *sk,
+					  sctp_scope_t scope,
+					  int gfp)
+{
+	struct sctp_sock *sp;
+	int i;
+
+	/* Retrieve the SCTP per socket area.  */
+	sp = sctp_sk((struct sock *)sk);
+
+	/* Init all variables to a known value.  */
+	memset(asoc, 0, sizeof(struct sctp_association));
+
+	/* Discarding const is appropriate here.  */
+	asoc->ep = (struct sctp_endpoint *)ep;
+	sctp_endpoint_hold(asoc->ep);
+
+	/* Hold the sock.  */
+	asoc->base.sk = (struct sock *)sk;
+	sock_hold(asoc->base.sk);
+
+	/* Initialize the common base substructure.  */
+	asoc->base.type = SCTP_EP_TYPE_ASSOCIATION;
+
+	/* Initialize the object handling fields.  */
+	atomic_set(&asoc->base.refcnt, 1);
+	asoc->base.dead = 0;
+	asoc->base.malloced = 0;
+
+	/* Initialize the bind addr area.  */
+	sctp_bind_addr_init(&asoc->base.bind_addr, ep->base.bind_addr.port);
+	rwlock_init(&asoc->base.addr_lock);
+
+	asoc->state = SCTP_STATE_CLOSED;
+
+	/* Set these values from the socket values, a conversion between
+	 * millsecons to seconds/microseconds must also be done.
+	 */
+	asoc->cookie_life.tv_sec = sp->assocparams.sasoc_cookie_life / 1000;
+	asoc->cookie_life.tv_usec = (sp->assocparams.sasoc_cookie_life % 1000)
+					* 1000;
+	asoc->pmtu = 0;
+	asoc->frag_point = 0;
+
+	/* Set the association max_retrans and RTO values from the
+	 * socket values.
+	 */
+	asoc->max_retrans = sp->assocparams.sasoc_asocmaxrxt;
+	asoc->rto_initial = msecs_to_jiffies(sp->rtoinfo.srto_initial);
+	asoc->rto_max = msecs_to_jiffies(sp->rtoinfo.srto_max);
+	asoc->rto_min = msecs_to_jiffies(sp->rtoinfo.srto_min);
+
+	asoc->overall_error_count = 0;
+
+	/* Initialize the maximum mumber of new data packets that can be sent
+	 * in a burst.
+	 */
+	asoc->max_burst = sctp_max_burst;
+
+	/* Copy things from the endpoint.  */
+	for (i = SCTP_EVENT_TIMEOUT_NONE; i < SCTP_NUM_TIMEOUT_TYPES; ++i) {
+		asoc->timeouts[i] = ep->timeouts[i];
+		init_timer(&asoc->timers[i]);
+		asoc->timers[i].function = sctp_timer_events[i];
+		asoc->timers[i].data = (unsigned long) asoc;
+	}
+
+	/* Pull default initialization values from the sock options.
+	 * Note: This assumes that the values have already been
+	 * validated in the sock.
+	 */
+	asoc->c.sinit_max_instreams = sp->initmsg.sinit_max_instreams;
+	asoc->c.sinit_num_ostreams  = sp->initmsg.sinit_num_ostreams;
+	asoc->max_init_attempts	= sp->initmsg.sinit_max_attempts;
+
+	asoc->max_init_timeo =
+		 msecs_to_jiffies(sp->initmsg.sinit_max_init_timeo);
+
+	/* Allocate storage for the ssnmap after the inbound and outbound
+	 * streams have been negotiated during Init.
+	 */
+	asoc->ssnmap = NULL;
+
+	/* Set the local window size for receive.
+	 * This is also the rcvbuf space per association.
+	 * RFC 6 - A SCTP receiver MUST be able to receive a minimum of
+	 * 1500 bytes in one SCTP packet.
+	 */
+	if (sk->sk_rcvbuf < SCTP_DEFAULT_MINWINDOW)
+		asoc->rwnd = SCTP_DEFAULT_MINWINDOW;
+	else
+		asoc->rwnd = sk->sk_rcvbuf;
+
+	asoc->a_rwnd = asoc->rwnd;
+
+	asoc->rwnd_over = 0;
+
+	/* Use my own max window until I learn something better.  */
+	asoc->peer.rwnd = SCTP_DEFAULT_MAXWINDOW;
+
+	/* Set the sndbuf size for transmit.  */
+	asoc->sndbuf_used = 0;
+
+	init_waitqueue_head(&asoc->wait);
+
+	asoc->c.my_vtag = sctp_generate_tag(ep);
+	asoc->peer.i.init_tag = 0;     /* INIT needs a vtag of 0. */
+	asoc->c.peer_vtag = 0;
+	asoc->c.my_ttag   = 0;
+	asoc->c.peer_ttag = 0;
+	asoc->c.my_port = ep->base.bind_addr.port;
+
+	asoc->c.initial_tsn = sctp_generate_tsn(ep);
+
+	asoc->next_tsn = asoc->c.initial_tsn;
+
+	asoc->ctsn_ack_point = asoc->next_tsn - 1;
+	asoc->adv_peer_ack_point = asoc->ctsn_ack_point;
+	asoc->highest_sacked = asoc->ctsn_ack_point;
+	asoc->last_cwr_tsn = asoc->ctsn_ack_point;
+	asoc->unack_data = 0;
+
+	SCTP_DEBUG_PRINTK("myctsnap for %s INIT as 0x%x.\n",
+			  asoc->ep->debug_name,
+			  asoc->ctsn_ack_point);
+
+	/* ADDIP Section 4.1 Asconf Chunk Procedures
+	 *
+	 * When an endpoint has an ASCONF signaled change to be sent to the
+	 * remote endpoint it should do the following:
+	 * ...
+	 * A2) a serial number should be assigned to the chunk. The serial
+	 * number SHOULD be a monotonically increasing number. The serial
+	 * numbers SHOULD be initialized at the start of the
+	 * association to the same value as the initial TSN.
+	 */
+	asoc->addip_serial = asoc->c.initial_tsn;
+
+	skb_queue_head_init(&asoc->addip_chunks);
+
+	/* Make an empty list of remote transport addresses.  */
+	INIT_LIST_HEAD(&asoc->peer.transport_addr_list);
+
+	/* RFC 2960 5.1 Normal Establishment of an Association
+	 *
+	 * After the reception of the first data chunk in an
+	 * association the endpoint must immediately respond with a
+	 * sack to acknowledge the data chunk.  Subsequent
+	 * acknowledgements should be done as described in Section
+	 * 6.2.
+	 *
+	 * [We implement this by telling a new association that it
+	 * already received one packet.]
+	 */
+	asoc->peer.sack_needed = 1;
+
+	/* Assume that the peer recongizes ASCONF until reported otherwise
+	 * via an ERROR chunk.
+	 */
+	asoc->peer.asconf_capable = 1;
+
+	/* Create an input queue.  */
+	sctp_inq_init(&asoc->base.inqueue);
+	sctp_inq_set_th_handler(&asoc->base.inqueue,
+				    (void (*)(void *))sctp_assoc_bh_rcv,
+				    asoc);
+
+	/* Create an output queue.  */
+	sctp_outq_init(asoc, &asoc->outqueue);
+
+	if (!sctp_ulpq_init(&asoc->ulpq, asoc))
+		goto fail_init;
+
+	/* Set up the tsn tracking. */
+	sctp_tsnmap_init(&asoc->peer.tsn_map, SCTP_TSN_MAP_SIZE, 0);
+
+	asoc->need_ecne = 0;
+
+	asoc->assoc_id = 0;
+
+	/* Assume that peer would support both address types unless we are
+	 * told otherwise.
+	 */
+	asoc->peer.ipv4_address = 1;
+	asoc->peer.ipv6_address = 1;
+	INIT_LIST_HEAD(&asoc->asocs);
+
+	asoc->autoclose = sp->autoclose;
+
+	asoc->default_stream = sp->default_stream;
+	asoc->default_ppid = sp->default_ppid;
+	asoc->default_flags = sp->default_flags;
+	asoc->default_context = sp->default_context;
+	asoc->default_timetolive = sp->default_timetolive;
+
+	return asoc;
+
+fail_init:
+	sctp_endpoint_put(asoc->ep);
+	sock_put(asoc->base.sk);
+	return NULL;
+}
+
+/* Allocate and initialize a new association */
+struct sctp_association *sctp_association_new(const struct sctp_endpoint *ep,
+					 const struct sock *sk,
+					 sctp_scope_t scope, int gfp)
+{
+	struct sctp_association *asoc;
+
+	asoc = t_new(struct sctp_association, gfp);
+	if (!asoc)
+		goto fail;
+
+	if (!sctp_association_init(asoc, ep, sk, scope, gfp))
+		goto fail_init;
+
+	asoc->base.malloced = 1;
+	SCTP_DBG_OBJCNT_INC(assoc);
+
+	return asoc;
+
+fail_init:
+	kfree(asoc);
+fail:
+	return NULL;
+}
+
+/* Free this association if possible.  There may still be users, so
+ * the actual deallocation may be delayed.
+ */
+void sctp_association_free(struct sctp_association *asoc)
+{
+	struct sock *sk = asoc->base.sk;
+	struct sctp_transport *transport;
+	struct list_head *pos, *temp;
+	int i;
+
+	list_del(&asoc->asocs);
+
+	/* Decrement the backlog value for a TCP-style listening socket. */
+	if (sctp_style(sk, TCP) && sctp_sstate(sk, LISTENING))
+		sk->sk_ack_backlog--;
+
+	/* Mark as dead, so other users can know this structure is
+	 * going away.
+	 */
+	asoc->base.dead = 1;
+
+	/* Dispose of any data lying around in the outqueue. */
+	sctp_outq_free(&asoc->outqueue);
+
+	/* Dispose of any pending messages for the upper layer. */
+	sctp_ulpq_free(&asoc->ulpq);
+
+	/* Dispose of any pending chunks on the inqueue. */
+	sctp_inq_free(&asoc->base.inqueue);
+
+	/* Free ssnmap storage. */
+	sctp_ssnmap_free(asoc->ssnmap);
+
+	/* Clean up the bound address list. */
+	sctp_bind_addr_free(&asoc->base.bind_addr);
+
+	/* Do we need to go through all of our timers and
+	 * delete them?   To be safe we will try to delete all, but we
+	 * should be able to go through and make a guess based
+	 * on our state.
+	 */
+	for (i = SCTP_EVENT_TIMEOUT_NONE; i < SCTP_NUM_TIMEOUT_TYPES; ++i) {
+		if (timer_pending(&asoc->timers[i]) &&
+		    del_timer(&asoc->timers[i]))
+			sctp_association_put(asoc);
+	}
+
+	/* Free peer's cached cookie. */
+	if (asoc->peer.cookie) {
+		kfree(asoc->peer.cookie);
+	}
+
+	/* Release the transport structures. */
+	list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
+		transport = list_entry(pos, struct sctp_transport, transports);
+		list_del(pos);
+		sctp_transport_free(transport);
+	}
+
+	/* Free any cached ASCONF_ACK chunk. */
+	if (asoc->addip_last_asconf_ack)
+		sctp_chunk_free(asoc->addip_last_asconf_ack);
+
+	/* Free any cached ASCONF chunk. */
+	if (asoc->addip_last_asconf)
+		sctp_chunk_free(asoc->addip_last_asconf);
+
+	sctp_association_put(asoc);
+}
+
+/* Cleanup and free up an association. */
+static void sctp_association_destroy(struct sctp_association *asoc)
+{
+	SCTP_ASSERT(asoc->base.dead, "Assoc is not dead", return);
+
+	sctp_endpoint_put(asoc->ep);
+	sock_put(asoc->base.sk);
+
+	if (asoc->assoc_id != 0) {
+		spin_lock_bh(&sctp_assocs_id_lock);
+		idr_remove(&sctp_assocs_id, asoc->assoc_id);
+		spin_unlock_bh(&sctp_assocs_id_lock);
+	}
+
+	if (asoc->base.malloced) {
+		kfree(asoc);
+		SCTP_DBG_OBJCNT_DEC(assoc);
+	}
+}
+
+/* Change the primary destination address for the peer. */
+void sctp_assoc_set_primary(struct sctp_association *asoc,
+			    struct sctp_transport *transport)
+{
+	asoc->peer.primary_path = transport;
+
+	/* Set a default msg_name for events. */
+	memcpy(&asoc->peer.primary_addr, &transport->ipaddr,
+	       sizeof(union sctp_addr));
+
+	/* If the primary path is changing, assume that the
+	 * user wants to use this new path.
+	 */
+	if (transport->active)
+		asoc->peer.active_path = transport;
+
+	/*
+	 * SFR-CACC algorithm:
+	 * Upon the receipt of a request to change the primary
+	 * destination address, on the data structure for the new
+	 * primary destination, the sender MUST do the following:
+	 *
+	 * 1) If CHANGEOVER_ACTIVE is set, then there was a switch
+	 * to this destination address earlier. The sender MUST set
+	 * CYCLING_CHANGEOVER to indicate that this switch is a
+	 * double switch to the same destination address.
+	 */
+	if (transport->cacc.changeover_active)
+		transport->cacc.cycling_changeover = 1;
+
+	/* 2) The sender MUST set CHANGEOVER_ACTIVE to indicate that
+	 * a changeover has occurred.
+	 */
+	transport->cacc.changeover_active = 1;
+
+	/* 3) The sender MUST store the next TSN to be sent in
+	 * next_tsn_at_change.
+	 */
+	transport->cacc.next_tsn_at_change = asoc->next_tsn;
+}
+
+/* Add a transport address to an association.  */
+struct sctp_transport *sctp_assoc_add_peer(struct sctp_association *asoc,
+					   const union sctp_addr *addr,
+					   int gfp)
+{
+	struct sctp_transport *peer;
+	struct sctp_sock *sp;
+	unsigned short port;
+
+	sp = sctp_sk(asoc->base.sk);
+
+	/* AF_INET and AF_INET6 share common port field. */
+	port = addr->v4.sin_port;
+
+	/* Set the port if it has not been set yet.  */
+	if (0 == asoc->peer.port)
+		asoc->peer.port = port;
+
+	/* Check to see if this is a duplicate. */
+	peer = sctp_assoc_lookup_paddr(asoc, addr);
+	if (peer)
+		return peer;
+
+	peer = sctp_transport_new(addr, gfp);
+	if (!peer)
+		return NULL;
+
+	sctp_transport_set_owner(peer, asoc);
+
+	/* Initialize the pmtu of the transport. */
+	sctp_transport_pmtu(peer);
+
+	/* If this is the first transport addr on this association,
+	 * initialize the association PMTU to the peer's PMTU.
+	 * If not and the current association PMTU is higher than the new
+	 * peer's PMTU, reset the association PMTU to the new peer's PMTU.
+	 */
+	if (asoc->pmtu)
+		asoc->pmtu = min_t(int, peer->pmtu, asoc->pmtu);
+	else
+		asoc->pmtu = peer->pmtu;
+
+	SCTP_DEBUG_PRINTK("sctp_assoc_add_peer:association %p PMTU set to "
+			  "%d\n", asoc, asoc->pmtu);
+
+	asoc->frag_point = sctp_frag_point(sp, asoc->pmtu);
+
+	/* The asoc->peer.port might not be meaningful yet, but
+	 * initialize the packet structure anyway.
+	 */
+	sctp_packet_init(&peer->packet, peer, asoc->base.bind_addr.port,
+			 asoc->peer.port);
+
+	/* 7.2.1 Slow-Start
+	 *
+	 * o The initial cwnd before DATA transmission or after a sufficiently
+	 *   long idle period MUST be set to
+	 *      min(4*MTU, max(2*MTU, 4380 bytes))
+	 *
+	 * o The initial value of ssthresh MAY be arbitrarily high
+	 *   (for example, implementations MAY use the size of the
+	 *   receiver advertised window).
+	 */
+	peer->cwnd = min(4*asoc->pmtu, max_t(__u32, 2*asoc->pmtu, 4380));
+
+	/* At this point, we may not have the receiver's advertised window,
+	 * so initialize ssthresh to the default value and it will be set
+	 * later when we process the INIT.
+	 */
+	peer->ssthresh = SCTP_DEFAULT_MAXWINDOW;
+
+	peer->partial_bytes_acked = 0;
+	peer->flight_size = 0;
+
+	/* By default, enable heartbeat for peer address. */
+	peer->hb_allowed = 1;
+
+	/* Initialize the peer's heartbeat interval based on the
+	 * sock configured value.
+	 */
+	peer->hb_interval = msecs_to_jiffies(sp->paddrparam.spp_hbinterval);
+
+	/* Set the path max_retrans.  */
+	peer->max_retrans = sp->paddrparam.spp_pathmaxrxt;
+
+	/* Set the transport's RTO.initial value */
+	peer->rto = asoc->rto_initial;
+
+	/* Attach the remote transport to our asoc.  */
+	list_add_tail(&peer->transports, &asoc->peer.transport_addr_list);
+
+	/* If we do not yet have a primary path, set one.  */
+	if (!asoc->peer.primary_path) {
+		sctp_assoc_set_primary(asoc, peer);
+		asoc->peer.retran_path = peer;
+	}
+
+	if (asoc->peer.active_path == asoc->peer.retran_path)
+		asoc->peer.retran_path = peer;
+
+	return peer;
+}
+
+/* Delete a transport address from an association.  */
+void sctp_assoc_del_peer(struct sctp_association *asoc,
+			 const union sctp_addr *addr)
+{
+	struct list_head	*pos;
+	struct list_head	*temp;
+	struct sctp_transport	*peer = NULL;
+	struct sctp_transport	*transport;
+
+	list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
+		transport = list_entry(pos, struct sctp_transport, transports);
+		if (sctp_cmp_addr_exact(addr, &transport->ipaddr)) {
+			peer = transport;
+			list_del(pos);
+			break;
+		}
+	}
+
+	/* The address we want delete is not in the association. */
+	if (!peer)
+		return;
+
+	/* Get the first transport of asoc. */ 
+	pos = asoc->peer.transport_addr_list.next;
+	transport = list_entry(pos, struct sctp_transport, transports);
+
+	/* Update any entries that match the peer to be deleted. */  
+	if (asoc->peer.primary_path == peer)
+		sctp_assoc_set_primary(asoc, transport);
+	if (asoc->peer.active_path == peer)
+		asoc->peer.active_path = transport;
+	if (asoc->peer.retran_path == peer)
+		asoc->peer.retran_path = transport;
+	if (asoc->peer.last_data_from == peer)
+		asoc->peer.last_data_from = transport;
+
+	sctp_transport_free(peer);
+}
+
+/* Lookup a transport by address. */
+struct sctp_transport *sctp_assoc_lookup_paddr(
+					const struct sctp_association *asoc,
+					const union sctp_addr *address)
+{
+	struct sctp_transport *t;
+	struct list_head *pos;
+
+	/* Cycle through all transports searching for a peer address. */
+
+	list_for_each(pos, &asoc->peer.transport_addr_list) {
+		t = list_entry(pos, struct sctp_transport, transports);
+		if (sctp_cmp_addr_exact(address, &t->ipaddr))
+			return t;
+	}
+
+	return NULL;
+}
+
+/* Engage in transport control operations.
+ * Mark the transport up or down and send a notification to the user.
+ * Select and update the new active and retran paths.
+ */
+void sctp_assoc_control_transport(struct sctp_association *asoc,
+				  struct sctp_transport *transport,
+				  sctp_transport_cmd_t command,
+				  sctp_sn_error_t error)
+{
+	struct sctp_transport *t = NULL;
+	struct sctp_transport *first;
+	struct sctp_transport *second;
+	struct sctp_ulpevent *event;
+	struct list_head *pos;
+	int spc_state = 0;
+
+	/* Record the transition on the transport.  */
+	switch (command) {
+	case SCTP_TRANSPORT_UP:
+		transport->active = SCTP_ACTIVE;
+		spc_state = SCTP_ADDR_AVAILABLE;
+		break;
+
+	case SCTP_TRANSPORT_DOWN:
+		transport->active = SCTP_INACTIVE;
+		spc_state = SCTP_ADDR_UNREACHABLE;
+		break;
+
+	default:
+		return;
+	};
+
+	/* Generate and send a SCTP_PEER_ADDR_CHANGE notification to the
+	 * user.
+	 */
+	event = sctp_ulpevent_make_peer_addr_change(asoc,
+				(struct sockaddr_storage *) &transport->ipaddr,
+				0, spc_state, error, GFP_ATOMIC);
+	if (event)
+		sctp_ulpq_tail_event(&asoc->ulpq, event);
+
+	/* Select new active and retran paths. */
+
+	/* Look for the two most recently used active transports.
+	 *
+	 * This code produces the wrong ordering whenever jiffies
+	 * rolls over, but we still get usable transports, so we don't
+	 * worry about it.
+	 */
+	first = NULL; second = NULL;
+
+	list_for_each(pos, &asoc->peer.transport_addr_list) {
+		t = list_entry(pos, struct sctp_transport, transports);
+
+		if (!t->active)
+			continue;
+		if (!first || t->last_time_heard > first->last_time_heard) {
+			second = first;
+			first = t;
+		}
+		if (!second || t->last_time_heard > second->last_time_heard)
+			second = t;
+	}
+
+	/* RFC 2960 6.4 Multi-Homed SCTP Endpoints
+	 *
+	 * By default, an endpoint should always transmit to the
+	 * primary path, unless the SCTP user explicitly specifies the
+	 * destination transport address (and possibly source
+	 * transport address) to use.
+	 *
+	 * [If the primary is active but not most recent, bump the most
+	 * recently used transport.]
+	 */
+	if (asoc->peer.primary_path->active &&
+	    first != asoc->peer.primary_path) {
+		second = first;
+		first = asoc->peer.primary_path;
+	}
+
+	/* If we failed to find a usable transport, just camp on the
+	 * primary, even if it is inactive.
+	 */
+	if (!first) {
+		first = asoc->peer.primary_path;
+		second = asoc->peer.primary_path;
+	}
+
+	/* Set the active and retran transports.  */
+	asoc->peer.active_path = first;
+	asoc->peer.retran_path = second;
+}
+
+/* Hold a reference to an association. */
+void sctp_association_hold(struct sctp_association *asoc)
+{
+	atomic_inc(&asoc->base.refcnt);
+}
+
+/* Release a reference to an association and cleanup
+ * if there are no more references.
+ */
+void sctp_association_put(struct sctp_association *asoc)
+{
+	if (atomic_dec_and_test(&asoc->base.refcnt))
+		sctp_association_destroy(asoc);
+}
+
+/* Allocate the next TSN, Transmission Sequence Number, for the given
+ * association.
+ */
+__u32 sctp_association_get_next_tsn(struct sctp_association *asoc)
+{
+	/* From Section 1.6 Serial Number Arithmetic:
+	 * Transmission Sequence Numbers wrap around when they reach
+	 * 2**32 - 1.  That is, the next TSN a DATA chunk MUST use
+	 * after transmitting TSN = 2*32 - 1 is TSN = 0.
+	 */
+	__u32 retval = asoc->next_tsn;
+	asoc->next_tsn++;
+	asoc->unack_data++;
+
+	return retval;
+}
+
+/* Compare two addresses to see if they match.  Wildcard addresses
+ * only match themselves.
+ */
+int sctp_cmp_addr_exact(const union sctp_addr *ss1,
+			const union sctp_addr *ss2)
+{
+	struct sctp_af *af;
+
+	af = sctp_get_af_specific(ss1->sa.sa_family);
+	if (unlikely(!af))
+		return 0;
+
+	return af->cmp_addr(ss1, ss2);
+}
+
+/* Return an ecne chunk to get prepended to a packet.
+ * Note:  We are sly and return a shared, prealloced chunk.  FIXME:
+ * No we don't, but we could/should.
+ */
+struct sctp_chunk *sctp_get_ecne_prepend(struct sctp_association *asoc)
+{
+	struct sctp_chunk *chunk;
+
+	/* Send ECNE if needed.
+	 * Not being able to allocate a chunk here is not deadly.
+	 */
+	if (asoc->need_ecne)
+		chunk = sctp_make_ecne(asoc, asoc->last_ecne_tsn);
+	else
+		chunk = NULL;
+
+	return chunk;
+}
+
+/*
+ * Find which transport this TSN was sent on.
+ */
+struct sctp_transport *sctp_assoc_lookup_tsn(struct sctp_association *asoc,
+					     __u32 tsn)
+{
+	struct sctp_transport *active;
+	struct sctp_transport *match;
+	struct list_head *entry, *pos;
+	struct sctp_transport *transport;
+	struct sctp_chunk *chunk;
+	__u32 key = htonl(tsn);
+
+	match = NULL;
+
+	/*
+	 * FIXME: In general, find a more efficient data structure for
+	 * searching.
+	 */
+
+	/*
+	 * The general strategy is to search each transport's transmitted
+	 * list.   Return which transport this TSN lives on.
+	 *
+	 * Let's be hopeful and check the active_path first.
+	 * Another optimization would be to know if there is only one
+	 * outbound path and not have to look for the TSN at all.
+	 *
+	 */
+
+	active = asoc->peer.active_path;
+
+	list_for_each(entry, &active->transmitted) {
+		chunk = list_entry(entry, struct sctp_chunk, transmitted_list);
+
+		if (key == chunk->subh.data_hdr->tsn) {
+			match = active;
+			goto out;
+		}
+	}
+
+	/* If not found, go search all the other transports. */
+	list_for_each(pos, &asoc->peer.transport_addr_list) {
+		transport = list_entry(pos, struct sctp_transport, transports);
+
+		if (transport == active)
+			break;
+		list_for_each(entry, &transport->transmitted) {
+			chunk = list_entry(entry, struct sctp_chunk,
+					   transmitted_list);
+			if (key == chunk->subh.data_hdr->tsn) {
+				match = transport;
+				goto out;
+			}
+		}
+	}
+out:
+	return match;
+}
+
+/* Is this the association we are looking for? */
+struct sctp_transport *sctp_assoc_is_match(struct sctp_association *asoc,
+					   const union sctp_addr *laddr,
+					   const union sctp_addr *paddr)
+{
+	struct sctp_transport *transport;
+
+	sctp_read_lock(&asoc->base.addr_lock);
+
+	if ((asoc->base.bind_addr.port == laddr->v4.sin_port) &&
+	    (asoc->peer.port == paddr->v4.sin_port)) {
+		transport = sctp_assoc_lookup_paddr(asoc, paddr);
+		if (!transport)
+			goto out;
+
+		if (sctp_bind_addr_match(&asoc->base.bind_addr, laddr,
+					 sctp_sk(asoc->base.sk)))
+			goto out;
+	}
+	transport = NULL;
+
+out:
+	sctp_read_unlock(&asoc->base.addr_lock);
+	return transport;
+}
+
+/* Do delayed input processing.  This is scheduled by sctp_rcv(). */
+static void sctp_assoc_bh_rcv(struct sctp_association *asoc)
+{
+	struct sctp_endpoint *ep;
+	struct sctp_chunk *chunk;
+	struct sock *sk;
+	struct sctp_inq *inqueue;
+	int state;
+	sctp_subtype_t subtype;
+	int error = 0;
+
+	/* The association should be held so we should be safe. */
+	ep = asoc->ep;
+	sk = asoc->base.sk;
+
+	inqueue = &asoc->base.inqueue;
+	sctp_association_hold(asoc);
+	while (NULL != (chunk = sctp_inq_pop(inqueue))) {
+		state = asoc->state;
+		subtype = SCTP_ST_CHUNK(chunk->chunk_hdr->type);
+
+		/* Remember where the last DATA chunk came from so we
+		 * know where to send the SACK.
+		 */
+		if (sctp_chunk_is_data(chunk))
+			asoc->peer.last_data_from = chunk->transport;
+		else
+			SCTP_INC_STATS(SCTP_MIB_INCTRLCHUNKS);
+
+		if (chunk->transport)
+			chunk->transport->last_time_heard = jiffies;
+
+		/* Run through the state machine. */
+		error = sctp_do_sm(SCTP_EVENT_T_CHUNK, subtype,
+				   state, ep, asoc, chunk, GFP_ATOMIC);
+
+		/* Check to see if the association is freed in response to
+		 * the incoming chunk.  If so, get out of the while loop.
+		 */
+		if (asoc->base.dead)
+			break;
+
+		/* If there is an error on chunk, discard this packet. */
+		if (error && chunk)
+			chunk->pdiscard = 1;
+	}
+	sctp_association_put(asoc);
+}
+
+/* This routine moves an association from its old sk to a new sk.  */
+void sctp_assoc_migrate(struct sctp_association *assoc, struct sock *newsk)
+{
+	struct sctp_sock *newsp = sctp_sk(newsk);
+	struct sock *oldsk = assoc->base.sk;
+
+	/* Delete the association from the old endpoint's list of
+	 * associations.
+	 */
+	list_del_init(&assoc->asocs);
+
+	/* Decrement the backlog value for a TCP-style socket. */
+	if (sctp_style(oldsk, TCP))
+		oldsk->sk_ack_backlog--;
+
+	/* Release references to the old endpoint and the sock.  */
+	sctp_endpoint_put(assoc->ep);
+	sock_put(assoc->base.sk);
+
+	/* Get a reference to the new endpoint.  */
+	assoc->ep = newsp->ep;
+	sctp_endpoint_hold(assoc->ep);
+
+	/* Get a reference to the new sock.  */
+	assoc->base.sk = newsk;
+	sock_hold(assoc->base.sk);
+
+	/* Add the association to the new endpoint's list of associations.  */
+	sctp_endpoint_add_asoc(newsp->ep, assoc);
+}
+
+/* Update an association (possibly from unexpected COOKIE-ECHO processing).  */
+void sctp_assoc_update(struct sctp_association *asoc,
+		       struct sctp_association *new)
+{
+	struct sctp_transport *trans;
+	struct list_head *pos, *temp;
+
+	/* Copy in new parameters of peer. */
+	asoc->c = new->c;
+	asoc->peer.rwnd = new->peer.rwnd;
+	asoc->peer.sack_needed = new->peer.sack_needed;
+	asoc->peer.i = new->peer.i;
+	sctp_tsnmap_init(&asoc->peer.tsn_map, SCTP_TSN_MAP_SIZE,
+			 asoc->peer.i.initial_tsn);
+
+	/* Remove any peer addresses not present in the new association. */
+	list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
+		trans = list_entry(pos, struct sctp_transport, transports);
+		if (!sctp_assoc_lookup_paddr(new, &trans->ipaddr))
+			sctp_assoc_del_peer(asoc, &trans->ipaddr);
+	}
+
+	/* If the case is A (association restart), use
+	 * initial_tsn as next_tsn. If the case is B, use
+	 * current next_tsn in case data sent to peer
+	 * has been discarded and needs retransmission.
+	 */
+	if (asoc->state >= SCTP_STATE_ESTABLISHED) {
+		asoc->next_tsn = new->next_tsn;
+		asoc->ctsn_ack_point = new->ctsn_ack_point;
+		asoc->adv_peer_ack_point = new->adv_peer_ack_point;
+
+		/* Reinitialize SSN for both local streams
+		 * and peer's streams.
+		 */
+		sctp_ssnmap_clear(asoc->ssnmap);
+
+	} else {
+		/* Add any peer addresses from the new association. */
+		list_for_each(pos, &new->peer.transport_addr_list) {
+			trans = list_entry(pos, struct sctp_transport,
+					   transports);
+			if (!sctp_assoc_lookup_paddr(asoc, &trans->ipaddr))
+				sctp_assoc_add_peer(asoc, &trans->ipaddr,
+						    GFP_ATOMIC);
+		}
+
+		asoc->ctsn_ack_point = asoc->next_tsn - 1;
+		asoc->adv_peer_ack_point = asoc->ctsn_ack_point;
+		if (!asoc->ssnmap) {
+			/* Move the ssnmap. */
+			asoc->ssnmap = new->ssnmap;
+			new->ssnmap = NULL;
+		}
+	}
+}
+
+/* Update the retran path for sending a retransmitted packet.
+ * Round-robin through the active transports, else round-robin
+ * through the inactive transports as this is the next best thing
+ * we can try.
+ */
+void sctp_assoc_update_retran_path(struct sctp_association *asoc)
+{
+	struct sctp_transport *t, *next;
+	struct list_head *head = &asoc->peer.transport_addr_list;
+	struct list_head *pos;
+
+	/* Find the next transport in a round-robin fashion. */
+	t = asoc->peer.retran_path;
+	pos = &t->transports;
+	next = NULL;
+
+	while (1) {
+		/* Skip the head. */
+		if (pos->next == head)
+			pos = head->next;
+		else
+			pos = pos->next;
+
+		t = list_entry(pos, struct sctp_transport, transports);
+
+		/* Try to find an active transport. */
+
+		if (t->active) {
+			break;
+		} else {
+			/* Keep track of the next transport in case
+			 * we don't find any active transport.
+			 */
+			if (!next)
+				next = t;
+		}
+
+		/* We have exhausted the list, but didn't find any
+		 * other active transports.  If so, use the next
+		 * transport.
+		 */
+		if (t == asoc->peer.retran_path) {
+			t = next;
+			break;
+		}
+	}
+
+	asoc->peer.retran_path = t;
+}
+
+/* Choose the transport for sending a SHUTDOWN packet.  */
+struct sctp_transport *sctp_assoc_choose_shutdown_transport(
+	struct sctp_association *asoc)
+{
+	/* If this is the first time SHUTDOWN is sent, use the active path,
+	 * else use the retran path. If the last SHUTDOWN was sent over the
+	 * retran path, update the retran path and use it.
+	 */
+	if (!asoc->shutdown_last_sent_to)
+		return asoc->peer.active_path;
+	else {
+		if (asoc->shutdown_last_sent_to == asoc->peer.retran_path)
+			sctp_assoc_update_retran_path(asoc);
+		return asoc->peer.retran_path;
+	}
+
+}
+
+/* Update the association's pmtu and frag_point by going through all the
+ * transports. This routine is called when a transport's PMTU has changed.
+ */
+void sctp_assoc_sync_pmtu(struct sctp_association *asoc)
+{
+	struct sctp_transport *t;
+	struct list_head *pos;
+	__u32 pmtu = 0;
+
+	if (!asoc)
+		return;
+
+	/* Get the lowest pmtu of all the transports. */
+	list_for_each(pos, &asoc->peer.transport_addr_list) {
+		t = list_entry(pos, struct sctp_transport, transports);
+		if (!pmtu || (t->pmtu < pmtu))
+			pmtu = t->pmtu;
+	}
+
+	if (pmtu) {
+		struct sctp_sock *sp = sctp_sk(asoc->base.sk);
+		asoc->pmtu = pmtu;
+		asoc->frag_point = sctp_frag_point(sp, pmtu);
+	}
+
+	SCTP_DEBUG_PRINTK("%s: asoc:%p, pmtu:%d, frag_point:%d\n",
+			  __FUNCTION__, asoc, asoc->pmtu, asoc->frag_point);
+}
+
+/* Should we send a SACK to update our peer? */
+static inline int sctp_peer_needs_update(struct sctp_association *asoc)
+{
+	switch (asoc->state) {
+	case SCTP_STATE_ESTABLISHED:
+	case SCTP_STATE_SHUTDOWN_PENDING:
+	case SCTP_STATE_SHUTDOWN_RECEIVED:
+	case SCTP_STATE_SHUTDOWN_SENT:
+		if ((asoc->rwnd > asoc->a_rwnd) &&
+		    ((asoc->rwnd - asoc->a_rwnd) >=
+		     min_t(__u32, (asoc->base.sk->sk_rcvbuf >> 1), asoc->pmtu)))
+			return 1;
+		break;
+	default:
+		break;
+	}
+	return 0;
+}
+
+/* Increase asoc's rwnd by len and send any window update SACK if needed. */
+void sctp_assoc_rwnd_increase(struct sctp_association *asoc, unsigned len)
+{
+	struct sctp_chunk *sack;
+	struct timer_list *timer;
+
+	if (asoc->rwnd_over) {
+		if (asoc->rwnd_over >= len) {
+			asoc->rwnd_over -= len;
+		} else {
+			asoc->rwnd += (len - asoc->rwnd_over);
+			asoc->rwnd_over = 0;
+		}
+	} else {
+		asoc->rwnd += len;
+	}
+
+	SCTP_DEBUG_PRINTK("%s: asoc %p rwnd increased by %d to (%u, %u) "
+			  "- %u\n", __FUNCTION__, asoc, len, asoc->rwnd,
+			  asoc->rwnd_over, asoc->a_rwnd);
+
+	/* Send a window update SACK if the rwnd has increased by at least the
+	 * minimum of the association's PMTU and half of the receive buffer.
+	 * The algorithm used is similar to the one described in
+	 * Section 4.2.3.3 of RFC 1122.
+	 */
+	if (sctp_peer_needs_update(asoc)) {
+		asoc->a_rwnd = asoc->rwnd;
+		SCTP_DEBUG_PRINTK("%s: Sending window update SACK- asoc: %p "
+				  "rwnd: %u a_rwnd: %u\n", __FUNCTION__,
+				  asoc, asoc->rwnd, asoc->a_rwnd);
+		sack = sctp_make_sack(asoc);
+		if (!sack)
+			return;
+
+		asoc->peer.sack_needed = 0;
+
+		sctp_outq_tail(&asoc->outqueue, sack);
+
+		/* Stop the SACK timer.  */
+		timer = &asoc->timers[SCTP_EVENT_TIMEOUT_SACK];
+		if (timer_pending(timer) && del_timer(timer))
+			sctp_association_put(asoc);
+	}
+}
+
+/* Decrease asoc's rwnd by len. */
+void sctp_assoc_rwnd_decrease(struct sctp_association *asoc, unsigned len)
+{
+	SCTP_ASSERT(asoc->rwnd, "rwnd zero", return);
+	SCTP_ASSERT(!asoc->rwnd_over, "rwnd_over not zero", return);
+	if (asoc->rwnd >= len) {
+		asoc->rwnd -= len;
+	} else {
+		asoc->rwnd_over = len - asoc->rwnd;
+		asoc->rwnd = 0;
+	}
+	SCTP_DEBUG_PRINTK("%s: asoc %p rwnd decreased by %d to (%u, %u)\n",
+			  __FUNCTION__, asoc, len, asoc->rwnd,
+			  asoc->rwnd_over);
+}
+
+/* Build the bind address list for the association based on info from the
+ * local endpoint and the remote peer.
+ */
+int sctp_assoc_set_bind_addr_from_ep(struct sctp_association *asoc, int gfp)
+{
+	sctp_scope_t scope;
+	int flags;
+
+	/* Use scoping rules to determine the subset of addresses from
+	 * the endpoint.
+	 */
+	scope = sctp_scope(&asoc->peer.active_path->ipaddr);
+	flags = (PF_INET6 == asoc->base.sk->sk_family) ? SCTP_ADDR6_ALLOWED : 0;
+	if (asoc->peer.ipv4_address)
+		flags |= SCTP_ADDR4_PEERSUPP;
+	if (asoc->peer.ipv6_address)
+		flags |= SCTP_ADDR6_PEERSUPP;
+
+	return sctp_bind_addr_copy(&asoc->base.bind_addr,
+				   &asoc->ep->base.bind_addr,
+				   scope, gfp, flags);
+}
+
+/* Build the association's bind address list from the cookie.  */
+int sctp_assoc_set_bind_addr_from_cookie(struct sctp_association *asoc,
+					 struct sctp_cookie *cookie, int gfp)
+{
+	int var_size2 = ntohs(cookie->peer_init->chunk_hdr.length);
+	int var_size3 = cookie->raw_addr_list_len;
+	__u8 *raw = (__u8 *)cookie->peer_init + var_size2;
+
+	return sctp_raw_to_bind_addrs(&asoc->base.bind_addr, raw, var_size3,
+				      asoc->ep->base.bind_addr.port, gfp);
+}
+
+/* Lookup laddr in the bind address list of an association. */ 
+int sctp_assoc_lookup_laddr(struct sctp_association *asoc, 
+			    const union sctp_addr *laddr)
+{
+	int found;
+
+	sctp_read_lock(&asoc->base.addr_lock);
+	if ((asoc->base.bind_addr.port == ntohs(laddr->v4.sin_port)) &&
+	    sctp_bind_addr_match(&asoc->base.bind_addr, laddr,
+			         sctp_sk(asoc->base.sk))) {
+		found = 1;
+		goto out;
+	}
+
+	found = 0;
+out:
+	sctp_read_unlock(&asoc->base.addr_lock);
+	return found;
+}