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

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diff -urN linux-2.4.22/net/sctp/transport.c linux-2.4.23/net/sctp/transport.c
@@ -0,0 +1,500 @@
+/* SCTP kernel reference Implementation
+ * Copyright (c) 1999-2000 Cisco, Inc.
+ * Copyright (c) 1999-2001 Motorola, Inc.
+ * Copyright (c) 2001-2003 International Business Machines Corp.
+ * 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 tranport representing
+ * a remote transport address.  For local transport addresses, we just use
+ * union sctp_addr.
+ *
+ * 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>
+ *    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/types.h>
+#include <net/sctp/sctp.h>
+
+/* 1st Level Abstractions.  */
+
+/* Allocate and initialize a new transport.  */
+struct sctp_transport *sctp_transport_new(const union sctp_addr *addr, int gfp)
+{
+        struct sctp_transport *transport;
+
+        transport = t_new(struct sctp_transport, gfp);
+	if (!transport)
+		goto fail;
+
+	if (!sctp_transport_init(transport, addr, gfp))
+		goto fail_init;
+
+	transport->malloced = 1;
+	SCTP_DBG_OBJCNT_INC(transport);
+
+	return transport;
+
+fail_init:
+	kfree(transport);
+
+fail:
+	return NULL;
+}
+
+/* Initialize a new transport from provided memory.  */
+struct sctp_transport *sctp_transport_init(struct sctp_transport *peer,
+					   const union sctp_addr *addr,
+					   int gfp)
+{
+	struct sctp_protocol *proto = sctp_get_protocol();
+
+	/* Copy in the address.  */
+	peer->ipaddr = *addr;
+	peer->af_specific = sctp_get_af_specific(addr->sa.sa_family);
+	peer->asoc = NULL;
+
+	peer->dst = NULL;
+	memset(&peer->saddr, 0, sizeof(union sctp_addr));
+
+	/* From 6.3.1 RTO Calculation:
+	 *
+	 * C1) Until an RTT measurement has been made for a packet sent to the
+	 * given destination transport address, set RTO to the protocol
+	 * parameter 'RTO.Initial'.
+	 */
+	peer->rtt = 0;
+	peer->rto = proto->rto_initial;
+	peer->rttvar = 0;
+	peer->srtt = 0;
+	peer->rto_pending = 0;
+
+	peer->last_time_heard = jiffies;
+	peer->last_time_used = jiffies;
+	peer->last_time_ecne_reduced = jiffies;
+
+	peer->active = 1;
+	peer->hb_allowed = 0;
+
+	/* Initialize the default path max_retrans.  */
+	peer->max_retrans = proto->max_retrans_path;
+	peer->error_threshold = 0;
+	peer->error_count = 0;
+
+	peer->debug_name = "unnamedtransport";
+
+	INIT_LIST_HEAD(&peer->transmitted);
+	INIT_LIST_HEAD(&peer->send_ready);
+	INIT_LIST_HEAD(&peer->transports);
+
+	/* Set up the retransmission timer.  */
+	init_timer(&peer->T3_rtx_timer);
+	peer->T3_rtx_timer.function = sctp_generate_t3_rtx_event;
+	peer->T3_rtx_timer.data = (unsigned long)peer;
+
+	/* Set up the heartbeat timer. */
+	init_timer(&peer->hb_timer);
+	peer->hb_interval = SCTP_DEFAULT_TIMEOUT_HEARTBEAT;
+	peer->hb_timer.function = sctp_generate_heartbeat_event;
+	peer->hb_timer.data = (unsigned long)peer;
+
+	atomic_set(&peer->refcnt, 1);
+	peer->dead = 0;
+
+	peer->malloced = 0;
+	return peer;
+}
+
+/* This transport is no longer needed.  Free up if possible, or
+ * delay until it last reference count.
+ */
+void sctp_transport_free(struct sctp_transport *transport)
+{
+	transport->dead = 1;
+
+	/* Try to delete the heartbeat timer.  */
+	if (del_timer(&transport->hb_timer))
+		sctp_transport_put(transport);
+
+	sctp_transport_put(transport);
+}
+
+/* Destroy the transport data structure.
+ * Assumes there are no more users of this structure.
+ */
+void sctp_transport_destroy(struct sctp_transport *transport)
+{
+	SCTP_ASSERT(transport->dead, "Transport is not dead", return);
+
+	if (transport->asoc)
+		sctp_association_put(transport->asoc);
+
+	dst_release(transport->dst);
+	kfree(transport);
+	SCTP_DBG_OBJCNT_DEC(transport);
+}
+
+/* Start T3_rtx timer if it is not already running and update the heartbeat
+ * timer.  This routine is called every time a DATA chunk is sent.
+ */
+void sctp_transport_reset_timers(struct sctp_transport *transport)
+{
+	/* RFC 2960 6.3.2 Retransmission Timer Rules
+	 *
+	 * R1) Every time a DATA chunk is sent to any address(including a
+	 * retransmission), if the T3-rtx timer of that address is not running
+	 * start it running so that it will expire after the RTO of that
+	 * address.
+	 */
+
+	if (!timer_pending(&transport->T3_rtx_timer))
+		if (!mod_timer(&transport->T3_rtx_timer,
+			       jiffies + transport->rto))
+			sctp_transport_hold(transport);
+
+	/* When a data chunk is sent, reset the heartbeat interval.  */
+	if (!mod_timer(&transport->hb_timer,
+		       sctp_transport_timeout(transport)))
+	    sctp_transport_hold(transport);
+}
+
+/* This transport has been assigned to an association.
+ * Initialize fields from the association or from the sock itself.
+ * Register the reference count in the association.
+ */
+void sctp_transport_set_owner(struct sctp_transport *transport,
+			      struct sctp_association *asoc)
+{
+	transport->asoc = asoc;
+	sctp_association_hold(asoc);
+}
+
+/* Initialize the pmtu of a transport. */
+void sctp_transport_pmtu(struct sctp_transport *transport)
+{
+	struct dst_entry *dst;
+
+	dst = transport->af_specific->get_dst(NULL, &transport->ipaddr, NULL);
+
+	if (dst) {
+		transport->pmtu = dst_pmtu(dst);
+		dst_release(dst);
+	} else
+		transport->pmtu = SCTP_DEFAULT_MAXSEGMENT;
+}
+
+/* Caches the dst entry and source address for a transport's destination
+ * address.
+ */
+void sctp_transport_route(struct sctp_transport *transport,
+			  union sctp_addr *saddr, struct sctp_opt *opt)
+{
+	struct sctp_association *asoc = transport->asoc;
+	struct sctp_af *af = transport->af_specific;
+	union sctp_addr *daddr = &transport->ipaddr;
+	struct dst_entry *dst;
+
+	dst = af->get_dst(asoc, daddr, saddr);
+
+	if (saddr)
+		memcpy(&transport->saddr, saddr, sizeof(union sctp_addr));
+	else
+		af->get_saddr(asoc, dst, daddr, &transport->saddr);
+
+	transport->dst = dst;
+	if (dst) {
+		transport->pmtu = dst_pmtu(dst);
+
+		/* Initialize sk->rcv_saddr, if the transport is the
+		 * association's active path for getsockname().
+		 */ 
+		if (asoc && (transport == asoc->peer.active_path))
+			af->to_sk_saddr(&transport->saddr, asoc->base.sk);
+	} else
+		transport->pmtu = SCTP_DEFAULT_MAXSEGMENT;
+}
+
+/* Hold a reference to a transport.  */
+void sctp_transport_hold(struct sctp_transport *transport)
+{
+	atomic_inc(&transport->refcnt);
+}
+
+/* Release a reference to a transport and clean up
+ * if there are no more references.
+ */
+void sctp_transport_put(struct sctp_transport *transport)
+{
+	if (atomic_dec_and_test(&transport->refcnt))
+		sctp_transport_destroy(transport);
+}
+
+/* Update transport's RTO based on the newly calculated RTT. */
+void sctp_transport_update_rto(struct sctp_transport *tp, __u32 rtt)
+{
+	struct sctp_protocol *proto = sctp_get_protocol();
+
+	/* Check for valid transport.  */
+	SCTP_ASSERT(tp, "NULL transport", return);
+
+	/* We should not be doing any RTO updates unless rto_pending is set.  */
+	SCTP_ASSERT(tp->rto_pending, "rto_pending not set", return);
+
+	if (tp->rttvar || tp->srtt) {
+		/* 6.3.1 C3) When a new RTT measurement R' is made, set
+		 * RTTVAR <- (1 - RTO.Beta) * RTTVAR + RTO.Beta * |SRTT - R'|
+		 * SRTT <- (1 - RTO.Alpha) * SRTT + RTO.Alpha * R'
+		 */
+
+		/* Note:  The above algorithm has been rewritten to
+		 * express rto_beta and rto_alpha as inverse powers
+		 * of two.
+		 * For example, assuming the default value of RTO.Alpha of
+		 * 1/8, rto_alpha would be expressed as 3.
+		 */
+		tp->rttvar = tp->rttvar - (tp->rttvar >> proto->rto_beta)
+			+ ((abs(tp->srtt - rtt)) >> proto->rto_beta);
+		tp->srtt = tp->srtt - (tp->srtt >> proto->rto_alpha)
+			+ (rtt >> proto->rto_alpha);
+	} else {
+		/* 6.3.1 C2) When the first RTT measurement R is made, set
+		 * SRTT <- R, RTTVAR <- R/2.
+		 */
+		tp->srtt = rtt;
+		tp->rttvar = rtt >> 1;
+	}
+
+	/* 6.3.1 G1) Whenever RTTVAR is computed, if RTTVAR = 0, then
+	 * adjust RTTVAR <- G, where G is the CLOCK GRANULARITY.
+	 */
+	if (tp->rttvar == 0)
+		tp->rttvar = SCTP_CLOCK_GRANULARITY;
+
+	/* 6.3.1 C3) After the computation, update RTO <- SRTT + 4 * RTTVAR. */
+	tp->rto = tp->srtt + (tp->rttvar << 2);
+
+	/* 6.3.1 C6) Whenever RTO is computed, if it is less than RTO.Min
+	 * seconds then it is rounded up to RTO.Min seconds.
+	 */
+	if (tp->rto < tp->asoc->rto_min)
+		tp->rto = tp->asoc->rto_min;
+
+	/* 6.3.1 C7) A maximum value may be placed on RTO provided it is
+	 * at least RTO.max seconds.
+	 */
+	if (tp->rto > tp->asoc->rto_max)
+		tp->rto = tp->asoc->rto_max;
+
+	tp->rtt = rtt;
+
+	/* Reset rto_pending so that a new RTT measurement is started when a
+	 * new data chunk is sent.
+	 */
+	tp->rto_pending = 0;
+
+	SCTP_DEBUG_PRINTK("%s: transport: %p, rtt: %d, srtt: %d "
+			  "rttvar: %d, rto: %d\n", __FUNCTION__,
+			  tp, rtt, tp->srtt, tp->rttvar, tp->rto);
+}
+
+/* This routine updates the transport's cwnd and partial_bytes_acked
+ * parameters based on the bytes acked in the received SACK.
+ */
+void sctp_transport_raise_cwnd(struct sctp_transport *transport,
+			       __u32 sack_ctsn, __u32 bytes_acked)
+{
+	__u32 cwnd, ssthresh, flight_size, pba, pmtu;
+
+	cwnd = transport->cwnd;
+	flight_size = transport->flight_size;
+
+	/* The appropriate cwnd increase algorithm is performed if, and only
+	 * if the cumulative TSN has advanced and the congestion window is
+	 * being fully utilized.
+	 */
+	if ((transport->asoc->ctsn_ack_point >= sack_ctsn) ||
+	    (flight_size < cwnd))
+		return;
+
+	ssthresh = transport->ssthresh;
+	pba = transport->partial_bytes_acked;
+	pmtu = transport->asoc->pmtu;
+
+	if (cwnd <= ssthresh) {
+		/* RFC 2960 7.2.1, sctpimpguide-05 2.14.2 When cwnd is less
+		 * than or equal to ssthresh an SCTP endpoint MUST use the
+		 * slow start algorithm to increase cwnd only if the current
+		 * congestion window is being fully utilized and an incoming
+		 * SACK advances the Cumulative TSN Ack Point. Only when these
+		 * two conditions are met can the cwnd be increased otherwise
+		 * the cwnd MUST not be increased. If these conditions are met
+		 * then cwnd MUST be increased by at most the lesser of
+		 * 1) the total size of the previously outstanding DATA
+		 * chunk(s) acknowledged, and 2) the destination's path MTU.
+		 */
+		if (bytes_acked > pmtu)
+			cwnd += pmtu;
+		else
+			cwnd += bytes_acked;
+		SCTP_DEBUG_PRINTK("%s: SLOW START: transport: %p, "
+				  "bytes_acked: %d, cwnd: %d, ssthresh: %d, "
+				  "flight_size: %d, pba: %d\n",
+				  __FUNCTION__,
+				  transport, bytes_acked, cwnd,
+				  ssthresh, flight_size, pba);
+	} else {
+		/* RFC 2960 7.2.2 Whenever cwnd is greater than ssthresh,
+		 * upon each SACK arrival that advances the Cumulative TSN Ack
+		 * Point, increase partial_bytes_acked by the total number of
+		 * bytes of all new chunks acknowledged in that SACK including
+		 * chunks acknowledged by the new Cumulative TSN Ack and by
+		 * Gap Ack Blocks.
+		 *
+		 * When partial_bytes_acked is equal to or greater than cwnd
+		 * and before the arrival of the SACK the sender had cwnd or
+		 * more bytes of data outstanding (i.e., before arrival of the
+		 * SACK, flightsize was greater than or equal to cwnd),
+		 * increase cwnd by MTU, and reset partial_bytes_acked to
+		 * (partial_bytes_acked - cwnd).
+		 */
+		pba += bytes_acked;
+		if (pba >= cwnd) {
+			cwnd += pmtu;
+			pba = ((cwnd < pba) ? (pba - cwnd) : 0);
+		}
+		SCTP_DEBUG_PRINTK("%s: CONGESTION AVOIDANCE: "
+				  "transport: %p, bytes_acked: %d, cwnd: %d, "
+				  "ssthresh: %d, flight_size: %d, pba: %d\n",
+				  __FUNCTION__,
+				  transport, bytes_acked, cwnd,
+				  ssthresh, flight_size, pba);
+	}
+
+	transport->cwnd = cwnd;
+	transport->partial_bytes_acked = pba;
+}
+
+/* This routine is used to lower the transport's cwnd when congestion is
+ * detected.
+ */
+void sctp_transport_lower_cwnd(struct sctp_transport *transport,
+			       sctp_lower_cwnd_t reason)
+{
+	switch (reason) {
+	case SCTP_LOWER_CWND_T3_RTX:
+		/* RFC 2960 Section 7.2.3, sctpimpguide-05 Section 2.9.2
+		 * When the T3-rtx timer expires on an address, SCTP should
+		 * perform slow start by:
+		 *      ssthresh = max(cwnd/2, 2*MTU)
+		 *      cwnd = 1*MTU
+		 *      partial_bytes_acked = 0
+		 */
+		transport->ssthresh = max(transport->cwnd/2,
+					  2*transport->asoc->pmtu);
+		transport->cwnd = transport->asoc->pmtu;
+		break;
+
+	case SCTP_LOWER_CWND_FAST_RTX:
+		/* RFC 2960 7.2.4 Adjust the ssthresh and cwnd of the
+		 * destination address(es) to which the missing DATA chunks
+		 * were last sent, according to the formula described in
+		 * Section 7.2.3.
+	 	 *
+	 	 * RFC 2960 7.2.3, sctpimpguide-05 2.9.2 Upon detection of
+		 * packet losses from SACK (see Section 7.2.4), An endpoint
+		 * should do the following:
+		 *      ssthresh = max(cwnd/2, 2*MTU)
+		 *      cwnd = ssthresh
+		 *      partial_bytes_acked = 0
+		 */
+		transport->ssthresh = max(transport->cwnd/2,
+					  2*transport->asoc->pmtu);
+		transport->cwnd = transport->ssthresh;
+		break;
+
+	case SCTP_LOWER_CWND_ECNE:
+		/* RFC 2481 Section 6.1.2.
+		 * If the sender receives an ECN-Echo ACK packet
+		 * then the sender knows that congestion was encountered in the
+		 * network on the path from the sender to the receiver. The
+		 * indication of congestion should be treated just as a
+		 * congestion loss in non-ECN Capable TCP. That is, the TCP
+		 * source halves the congestion window "cwnd" and reduces the
+		 * slow start threshold "ssthresh".
+		 * A critical condition is that TCP does not react to
+		 * congestion indications more than once every window of
+		 * data (or more loosely more than once every round-trip time).
+		 */
+		if ((jiffies - transport->last_time_ecne_reduced) >
+		    transport->rtt) {
+			transport->ssthresh = max(transport->cwnd/2,
+					  	  2*transport->asoc->pmtu);
+			transport->cwnd = transport->ssthresh;
+			transport->last_time_ecne_reduced = jiffies;
+		}
+		break;
+
+	case SCTP_LOWER_CWND_INACTIVE:
+		/* RFC 2960 Section 7.2.1, sctpimpguide-05 Section 2.14.2
+		 * When the association does not transmit data on a given
+		 * transport address within an RTO, the cwnd of the transport
+		 * address should be adjusted to 2*MTU.
+		 * NOTE: Although the draft recommends that this check needs
+		 * to be done every RTO interval, we do it every hearbeat
+		 * interval.
+		 */
+		if ((jiffies - transport->last_time_used) > transport->rto)
+			transport->cwnd = 2*transport->asoc->pmtu;
+		break;
+	};
+
+	transport->partial_bytes_acked = 0;
+	SCTP_DEBUG_PRINTK("%s: transport: %p reason: %d cwnd: "
+			  "%d ssthresh: %d\n", __FUNCTION__,
+			  transport, reason,
+			  transport->cwnd, transport->ssthresh);
+}
+
+/* What is the next timeout value for this transport? */
+unsigned long sctp_transport_timeout(struct sctp_transport *t)
+{
+	unsigned long timeout;
+	timeout = t->hb_interval + t->rto + sctp_jitter(t->rto);
+	timeout += jiffies;
+	return timeout;
+}
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