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Diffstat (limited to 'net/sctp/transport.c')
| -rw-r--r-- | net/sctp/transport.c | 514 |
1 files changed, 514 insertions, 0 deletions
diff --git a/net/sctp/transport.c b/net/sctp/transport.c new file mode 100644 index 0000000..f30882e --- /dev/null +++ b/net/sctp/transport.c @@ -0,0 +1,514 @@ +/* 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> +#include <net/sctp/sm.h> + +/* 1st Level Abstractions. */ + +/* Initialize a new transport from provided memory. */ +static struct sctp_transport *sctp_transport_init(struct sctp_transport *peer, + const union sctp_addr *addr, + int gfp) +{ + /* 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 = sctp_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 = SCTP_ACTIVE; + peer->hb_allowed = 0; + + /* Initialize the default path max_retrans. */ + peer->max_retrans = sctp_max_retrans_path; + peer->error_count = 0; + + 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; + + /* Initialize the state information for SFR-CACC */ + peer->cacc.changeover_active = 0; + peer->cacc.cycling_changeover = 0; + peer->cacc.next_tsn_at_change = 0; + peer->cacc.cacc_saw_newack = 0; + + return peer; +} + +/* 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; +} + +/* 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); + + /* Delete the T3_rtx timer if it's active. + * There is no point in not doing this now and letting + * structure hang around in memory since we know + * the tranport is going away. + */ + if (timer_pending(&transport->T3_rtx_timer) && + del_timer(&transport->T3_rtx_timer)) + sctp_transport_put(transport); + + + sctp_transport_put(transport); +} + +/* Destroy the transport data structure. + * Assumes there are no more users of this structure. + */ +static 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); + + sctp_packet_free(&transport->packet); + + 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_mtu(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_sock *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_mtu(dst); + + /* Initialize sk->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) +{ + /* 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 >> sctp_rto_beta) + + ((abs(tp->srtt - rtt)) >> sctp_rto_beta); + tp->srtt = tp->srtt - (tp->srtt >> sctp_rto_alpha) + + (rtt >> sctp_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 + * When the T3-rtx timer expires on an address, SCTP should + * perform slow start by: + * ssthresh = max(cwnd/2, 4*MTU) + * cwnd = 1*MTU + * partial_bytes_acked = 0 + */ + transport->ssthresh = max(transport->cwnd/2, + 4*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 Upon detection of packet + * losses from SACK (see Section 7.2.4), An endpoint + * should do the following: + * ssthresh = max(cwnd/2, 4*MTU) + * cwnd = ssthresh + * partial_bytes_acked = 0 + */ + transport->ssthresh = max(transport->cwnd/2, + 4*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, + 4*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 + * When the endpoint does not transmit data on a given + * transport address, the cwnd of the transport address + * should be adjusted to max(cwnd/2, 4*MTU) per RTO. + * 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 = max(transport->cwnd/2, + 4*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; +} |