blob: 132046cb82fc764ae758a0535aad8816946ae1d2 [file] [log] [blame]
Vlad Yasevich60c778b2008-01-11 09:57:09 -05001/* SCTP kernel implementation
Linus Torvalds1da177e2005-04-16 15:20:36 -07002 * Copyright (c) 1999-2000 Cisco, Inc.
3 * Copyright (c) 1999-2001 Motorola, Inc.
4 * Copyright (c) 2001-2003 International Business Machines Corp.
5 * Copyright (c) 2001 Intel Corp.
6 * Copyright (c) 2001 La Monte H.P. Yarroll
7 *
Vlad Yasevich60c778b2008-01-11 09:57:09 -05008 * This file is part of the SCTP kernel implementation
Linus Torvalds1da177e2005-04-16 15:20:36 -07009 *
10 * This module provides the abstraction for an SCTP tranport representing
11 * a remote transport address. For local transport addresses, we just use
12 * union sctp_addr.
13 *
Vlad Yasevich60c778b2008-01-11 09:57:09 -050014 * This SCTP implementation is free software;
Linus Torvalds1da177e2005-04-16 15:20:36 -070015 * you can redistribute it and/or modify it under the terms of
16 * the GNU General Public License as published by
17 * the Free Software Foundation; either version 2, or (at your option)
18 * any later version.
19 *
Vlad Yasevich60c778b2008-01-11 09:57:09 -050020 * This SCTP implementation is distributed in the hope that it
Linus Torvalds1da177e2005-04-16 15:20:36 -070021 * will be useful, but WITHOUT ANY WARRANTY; without even the implied
22 * ************************
23 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
24 * See the GNU General Public License for more details.
25 *
26 * You should have received a copy of the GNU General Public License
27 * along with GNU CC; see the file COPYING. If not, write to
28 * the Free Software Foundation, 59 Temple Place - Suite 330,
29 * Boston, MA 02111-1307, USA.
30 *
31 * Please send any bug reports or fixes you make to the
32 * email address(es):
33 * lksctp developers <lksctp-developers@lists.sourceforge.net>
34 *
35 * Or submit a bug report through the following website:
36 * http://www.sf.net/projects/lksctp
37 *
38 * Written or modified by:
39 * La Monte H.P. Yarroll <piggy@acm.org>
40 * Karl Knutson <karl@athena.chicago.il.us>
41 * Jon Grimm <jgrimm@us.ibm.com>
42 * Xingang Guo <xingang.guo@intel.com>
43 * Hui Huang <hui.huang@nokia.com>
44 * Sridhar Samudrala <sri@us.ibm.com>
45 * Ardelle Fan <ardelle.fan@intel.com>
46 *
47 * Any bugs reported given to us we will try to fix... any fixes shared will
48 * be incorporated into the next SCTP release.
49 */
50
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090051#include <linux/slab.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070052#include <linux/types.h>
Sridhar Samudralaad8fec12006-07-21 14:48:50 -070053#include <linux/random.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070054#include <net/sctp/sctp.h>
55#include <net/sctp/sm.h>
56
57/* 1st Level Abstractions. */
58
59/* Initialize a new transport from provided memory. */
60static struct sctp_transport *sctp_transport_init(struct sctp_transport *peer,
61 const union sctp_addr *addr,
Al Virodd0fc662005-10-07 07:46:04 +010062 gfp_t gfp)
Linus Torvalds1da177e2005-04-16 15:20:36 -070063{
64 /* Copy in the address. */
65 peer->ipaddr = *addr;
66 peer->af_specific = sctp_get_af_specific(addr->sa.sa_family);
Linus Torvalds1da177e2005-04-16 15:20:36 -070067 memset(&peer->saddr, 0, sizeof(union sctp_addr));
68
69 /* From 6.3.1 RTO Calculation:
70 *
71 * C1) Until an RTT measurement has been made for a packet sent to the
72 * given destination transport address, set RTO to the protocol
73 * parameter 'RTO.Initial'.
74 */
Andrei Pelinescu-Onciul5fdd4ba2009-11-29 00:14:02 -080075 peer->rto = msecs_to_jiffies(sctp_rto_initial);
Linus Torvalds1da177e2005-04-16 15:20:36 -070076
77 peer->last_time_heard = jiffies;
Linus Torvalds1da177e2005-04-16 15:20:36 -070078 peer->last_time_ecne_reduced = jiffies;
79
Frank Filz52ccb8e2005-12-22 11:36:46 -080080 peer->param_flags = SPP_HB_DISABLE |
81 SPP_PMTUD_ENABLE |
82 SPP_SACKDELAY_ENABLE;
Linus Torvalds1da177e2005-04-16 15:20:36 -070083
84 /* Initialize the default path max_retrans. */
Frank Filz52ccb8e2005-12-22 11:36:46 -080085 peer->pathmaxrxt = sctp_max_retrans_path;
Linus Torvalds1da177e2005-04-16 15:20:36 -070086
87 INIT_LIST_HEAD(&peer->transmitted);
88 INIT_LIST_HEAD(&peer->send_ready);
89 INIT_LIST_HEAD(&peer->transports);
90
Pavel Emelyanovb24b8a22008-01-23 21:20:07 -080091 setup_timer(&peer->T3_rtx_timer, sctp_generate_t3_rtx_event,
92 (unsigned long)peer);
93 setup_timer(&peer->hb_timer, sctp_generate_heartbeat_event,
94 (unsigned long)peer);
Vlad Yasevich50b5d6a2010-05-06 00:56:07 -070095 setup_timer(&peer->proto_unreach_timer,
96 sctp_generate_proto_unreach_event, (unsigned long)peer);
Linus Torvalds1da177e2005-04-16 15:20:36 -070097
Sridhar Samudralaad8fec12006-07-21 14:48:50 -070098 /* Initialize the 64-bit random nonce sent with heartbeat. */
99 get_random_bytes(&peer->hb_nonce, sizeof(peer->hb_nonce));
100
Linus Torvalds1da177e2005-04-16 15:20:36 -0700101 atomic_set(&peer->refcnt, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700102
103 return peer;
104}
105
106/* Allocate and initialize a new transport. */
Alexey Dobriyan3182cd82005-07-11 20:57:47 -0700107struct sctp_transport *sctp_transport_new(const union sctp_addr *addr,
Al Virodd0fc662005-10-07 07:46:04 +0100108 gfp_t gfp)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700109{
YOSHIFUJI Hideakid808ad92007-02-09 23:25:18 +0900110 struct sctp_transport *transport;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700111
YOSHIFUJI Hideakid808ad92007-02-09 23:25:18 +0900112 transport = t_new(struct sctp_transport, gfp);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700113 if (!transport)
114 goto fail;
115
116 if (!sctp_transport_init(transport, addr, gfp))
117 goto fail_init;
118
119 transport->malloced = 1;
120 SCTP_DBG_OBJCNT_INC(transport);
121
122 return transport;
123
124fail_init:
125 kfree(transport);
126
127fail:
128 return NULL;
129}
130
131/* This transport is no longer needed. Free up if possible, or
132 * delay until it last reference count.
133 */
134void sctp_transport_free(struct sctp_transport *transport)
135{
136 transport->dead = 1;
137
138 /* Try to delete the heartbeat timer. */
139 if (del_timer(&transport->hb_timer))
140 sctp_transport_put(transport);
141
142 /* Delete the T3_rtx timer if it's active.
143 * There is no point in not doing this now and letting
144 * structure hang around in memory since we know
145 * the tranport is going away.
146 */
147 if (timer_pending(&transport->T3_rtx_timer) &&
148 del_timer(&transport->T3_rtx_timer))
149 sctp_transport_put(transport);
150
Wei Yongjun55fa0cf2010-05-09 16:56:07 +0000151 /* Delete the ICMP proto unreachable timer if it's active. */
152 if (timer_pending(&transport->proto_unreach_timer) &&
153 del_timer(&transport->proto_unreach_timer))
154 sctp_association_put(transport->asoc);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700155
156 sctp_transport_put(transport);
157}
158
159/* Destroy the transport data structure.
160 * Assumes there are no more users of this structure.
161 */
162static void sctp_transport_destroy(struct sctp_transport *transport)
163{
164 SCTP_ASSERT(transport->dead, "Transport is not dead", return);
165
166 if (transport->asoc)
167 sctp_association_put(transport->asoc);
168
YOSHIFUJI Hideakid808ad92007-02-09 23:25:18 +0900169 sctp_packet_free(&transport->packet);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700170
171 dst_release(transport->dst);
172 kfree(transport);
173 SCTP_DBG_OBJCNT_DEC(transport);
174}
175
176/* Start T3_rtx timer if it is not already running and update the heartbeat
177 * timer. This routine is called every time a DATA chunk is sent.
178 */
Vlad Yasevichd9efc222010-04-30 22:41:09 -0400179void sctp_transport_reset_timers(struct sctp_transport *transport)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700180{
181 /* RFC 2960 6.3.2 Retransmission Timer Rules
182 *
183 * R1) Every time a DATA chunk is sent to any address(including a
184 * retransmission), if the T3-rtx timer of that address is not running
185 * start it running so that it will expire after the RTO of that
186 * address.
187 */
188
Vlad Yasevichd9efc222010-04-30 22:41:09 -0400189 if (!timer_pending(&transport->T3_rtx_timer))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700190 if (!mod_timer(&transport->T3_rtx_timer,
191 jiffies + transport->rto))
192 sctp_transport_hold(transport);
193
194 /* When a data chunk is sent, reset the heartbeat interval. */
195 if (!mod_timer(&transport->hb_timer,
196 sctp_transport_timeout(transport)))
197 sctp_transport_hold(transport);
198}
199
200/* This transport has been assigned to an association.
201 * Initialize fields from the association or from the sock itself.
202 * Register the reference count in the association.
203 */
204void sctp_transport_set_owner(struct sctp_transport *transport,
205 struct sctp_association *asoc)
206{
207 transport->asoc = asoc;
208 sctp_association_hold(asoc);
209}
210
211/* Initialize the pmtu of a transport. */
212void sctp_transport_pmtu(struct sctp_transport *transport)
213{
214 struct dst_entry *dst;
215
216 dst = transport->af_specific->get_dst(NULL, &transport->ipaddr, NULL);
217
218 if (dst) {
Frank Filz52ccb8e2005-12-22 11:36:46 -0800219 transport->pathmtu = dst_mtu(dst);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700220 dst_release(dst);
221 } else
Frank Filz52ccb8e2005-12-22 11:36:46 -0800222 transport->pathmtu = SCTP_DEFAULT_MAXSEGMENT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700223}
224
Vlad Yasevichc910b472007-06-07 13:47:03 -0400225/* this is a complete rip-off from __sk_dst_check
226 * the cookie is always 0 since this is how it's used in the
227 * pmtu code
228 */
229static struct dst_entry *sctp_transport_dst_check(struct sctp_transport *t)
230{
231 struct dst_entry *dst = t->dst;
232
233 if (dst && dst->obsolete && dst->ops->check(dst, 0) == NULL) {
234 dst_release(t->dst);
235 t->dst = NULL;
236 return NULL;
237 }
238
239 return dst;
240}
241
242void sctp_transport_update_pmtu(struct sctp_transport *t, u32 pmtu)
243{
244 struct dst_entry *dst;
245
246 if (unlikely(pmtu < SCTP_DEFAULT_MINSEGMENT)) {
247 printk(KERN_WARNING "%s: Reported pmtu %d too low, "
248 "using default minimum of %d\n",
Harvey Harrison0dc47872008-03-05 20:47:47 -0800249 __func__, pmtu,
Vlad Yasevichc910b472007-06-07 13:47:03 -0400250 SCTP_DEFAULT_MINSEGMENT);
251 /* Use default minimum segment size and disable
252 * pmtu discovery on this transport.
253 */
254 t->pathmtu = SCTP_DEFAULT_MINSEGMENT;
Vlad Yasevichc910b472007-06-07 13:47:03 -0400255 } else {
256 t->pathmtu = pmtu;
257 }
258
259 dst = sctp_transport_dst_check(t);
260 if (dst)
261 dst->ops->update_pmtu(dst, pmtu);
262}
263
Linus Torvalds1da177e2005-04-16 15:20:36 -0700264/* Caches the dst entry and source address for a transport's destination
265 * address.
266 */
267void sctp_transport_route(struct sctp_transport *transport,
268 union sctp_addr *saddr, struct sctp_sock *opt)
269{
270 struct sctp_association *asoc = transport->asoc;
271 struct sctp_af *af = transport->af_specific;
272 union sctp_addr *daddr = &transport->ipaddr;
273 struct dst_entry *dst;
274
275 dst = af->get_dst(asoc, daddr, saddr);
276
277 if (saddr)
278 memcpy(&transport->saddr, saddr, sizeof(union sctp_addr));
279 else
YOSHIFUJI Hideakie5117102008-05-29 19:55:05 +0900280 af->get_saddr(opt, asoc, dst, daddr, &transport->saddr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700281
282 transport->dst = dst;
Frank Filz52ccb8e2005-12-22 11:36:46 -0800283 if ((transport->param_flags & SPP_PMTUD_DISABLE) && transport->pathmtu) {
284 return;
285 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700286 if (dst) {
Frank Filz52ccb8e2005-12-22 11:36:46 -0800287 transport->pathmtu = dst_mtu(dst);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700288
289 /* Initialize sk->sk_rcv_saddr, if the transport is the
290 * association's active path for getsockname().
YOSHIFUJI Hideakid808ad92007-02-09 23:25:18 +0900291 */
Vlad Yasevicha78102e2009-11-11 11:54:37 +0000292 if (asoc && (!asoc->peer.primary_path ||
293 (transport == asoc->peer.active_path)))
Neil Hormanbf031ff2005-12-02 20:32:29 -0800294 opt->pf->af->to_sk_saddr(&transport->saddr,
295 asoc->base.sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700296 } else
Frank Filz52ccb8e2005-12-22 11:36:46 -0800297 transport->pathmtu = SCTP_DEFAULT_MAXSEGMENT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700298}
299
300/* Hold a reference to a transport. */
301void sctp_transport_hold(struct sctp_transport *transport)
302{
303 atomic_inc(&transport->refcnt);
304}
305
306/* Release a reference to a transport and clean up
307 * if there are no more references.
308 */
309void sctp_transport_put(struct sctp_transport *transport)
310{
311 if (atomic_dec_and_test(&transport->refcnt))
312 sctp_transport_destroy(transport);
313}
314
315/* Update transport's RTO based on the newly calculated RTT. */
316void sctp_transport_update_rto(struct sctp_transport *tp, __u32 rtt)
317{
318 /* Check for valid transport. */
319 SCTP_ASSERT(tp, "NULL transport", return);
320
321 /* We should not be doing any RTO updates unless rto_pending is set. */
322 SCTP_ASSERT(tp->rto_pending, "rto_pending not set", return);
323
324 if (tp->rttvar || tp->srtt) {
325 /* 6.3.1 C3) When a new RTT measurement R' is made, set
326 * RTTVAR <- (1 - RTO.Beta) * RTTVAR + RTO.Beta * |SRTT - R'|
327 * SRTT <- (1 - RTO.Alpha) * SRTT + RTO.Alpha * R'
328 */
329
330 /* Note: The above algorithm has been rewritten to
331 * express rto_beta and rto_alpha as inverse powers
332 * of two.
333 * For example, assuming the default value of RTO.Alpha of
334 * 1/8, rto_alpha would be expressed as 3.
335 */
336 tp->rttvar = tp->rttvar - (tp->rttvar >> sctp_rto_beta)
337 + ((abs(tp->srtt - rtt)) >> sctp_rto_beta);
338 tp->srtt = tp->srtt - (tp->srtt >> sctp_rto_alpha)
339 + (rtt >> sctp_rto_alpha);
340 } else {
341 /* 6.3.1 C2) When the first RTT measurement R is made, set
342 * SRTT <- R, RTTVAR <- R/2.
343 */
344 tp->srtt = rtt;
345 tp->rttvar = rtt >> 1;
346 }
347
348 /* 6.3.1 G1) Whenever RTTVAR is computed, if RTTVAR = 0, then
349 * adjust RTTVAR <- G, where G is the CLOCK GRANULARITY.
350 */
351 if (tp->rttvar == 0)
352 tp->rttvar = SCTP_CLOCK_GRANULARITY;
353
354 /* 6.3.1 C3) After the computation, update RTO <- SRTT + 4 * RTTVAR. */
355 tp->rto = tp->srtt + (tp->rttvar << 2);
356
357 /* 6.3.1 C6) Whenever RTO is computed, if it is less than RTO.Min
358 * seconds then it is rounded up to RTO.Min seconds.
359 */
360 if (tp->rto < tp->asoc->rto_min)
361 tp->rto = tp->asoc->rto_min;
362
363 /* 6.3.1 C7) A maximum value may be placed on RTO provided it is
364 * at least RTO.max seconds.
365 */
366 if (tp->rto > tp->asoc->rto_max)
367 tp->rto = tp->asoc->rto_max;
368
369 tp->rtt = rtt;
370
371 /* Reset rto_pending so that a new RTT measurement is started when a
372 * new data chunk is sent.
373 */
374 tp->rto_pending = 0;
375
376 SCTP_DEBUG_PRINTK("%s: transport: %p, rtt: %d, srtt: %d "
Harvey Harrison0dc47872008-03-05 20:47:47 -0800377 "rttvar: %d, rto: %ld\n", __func__,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700378 tp, rtt, tp->srtt, tp->rttvar, tp->rto);
379}
380
381/* This routine updates the transport's cwnd and partial_bytes_acked
382 * parameters based on the bytes acked in the received SACK.
383 */
384void sctp_transport_raise_cwnd(struct sctp_transport *transport,
385 __u32 sack_ctsn, __u32 bytes_acked)
386{
Vlad Yasevichcf9b4812010-04-30 22:41:10 -0400387 struct sctp_association *asoc = transport->asoc;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700388 __u32 cwnd, ssthresh, flight_size, pba, pmtu;
389
390 cwnd = transport->cwnd;
391 flight_size = transport->flight_size;
392
Vlad Yasevicha6465232008-06-04 12:38:43 -0700393 /* See if we need to exit Fast Recovery first */
Vlad Yasevichcf9b4812010-04-30 22:41:10 -0400394 if (asoc->fast_recovery &&
395 TSN_lte(asoc->fast_recovery_exit, sack_ctsn))
396 asoc->fast_recovery = 0;
Vlad Yasevicha6465232008-06-04 12:38:43 -0700397
Linus Torvalds1da177e2005-04-16 15:20:36 -0700398 /* The appropriate cwnd increase algorithm is performed if, and only
Vlad Yasevicha6465232008-06-04 12:38:43 -0700399 * if the cumulative TSN whould advanced and the congestion window is
Linus Torvalds1da177e2005-04-16 15:20:36 -0700400 * being fully utilized.
401 */
Vlad Yasevicha6465232008-06-04 12:38:43 -0700402 if (TSN_lte(sack_ctsn, transport->asoc->ctsn_ack_point) ||
Linus Torvalds1da177e2005-04-16 15:20:36 -0700403 (flight_size < cwnd))
404 return;
405
406 ssthresh = transport->ssthresh;
407 pba = transport->partial_bytes_acked;
Frank Filz52ccb8e2005-12-22 11:36:46 -0800408 pmtu = transport->asoc->pathmtu;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700409
410 if (cwnd <= ssthresh) {
Vlad Yasevicha6465232008-06-04 12:38:43 -0700411 /* RFC 4960 7.2.1
412 * o When cwnd is less than or equal to ssthresh, an SCTP
413 * endpoint MUST use the slow-start algorithm to increase
414 * cwnd only if the current congestion window is being fully
415 * utilized, an incoming SACK advances the Cumulative TSN
416 * Ack Point, and the data sender is not in Fast Recovery.
417 * Only when these three conditions are met can the cwnd be
418 * increased; otherwise, the cwnd MUST not be increased.
419 * If these conditions are met, then cwnd MUST be increased
420 * by, at most, the lesser of 1) the total size of the
421 * previously outstanding DATA chunk(s) acknowledged, and
422 * 2) the destination's path MTU. This upper bound protects
423 * against the ACK-Splitting attack outlined in [SAVAGE99].
Linus Torvalds1da177e2005-04-16 15:20:36 -0700424 */
Vlad Yasevichcf9b4812010-04-30 22:41:10 -0400425 if (asoc->fast_recovery)
Vlad Yasevicha6465232008-06-04 12:38:43 -0700426 return;
427
Linus Torvalds1da177e2005-04-16 15:20:36 -0700428 if (bytes_acked > pmtu)
429 cwnd += pmtu;
430 else
431 cwnd += bytes_acked;
432 SCTP_DEBUG_PRINTK("%s: SLOW START: transport: %p, "
433 "bytes_acked: %d, cwnd: %d, ssthresh: %d, "
434 "flight_size: %d, pba: %d\n",
Harvey Harrison0dc47872008-03-05 20:47:47 -0800435 __func__,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700436 transport, bytes_acked, cwnd,
437 ssthresh, flight_size, pba);
438 } else {
439 /* RFC 2960 7.2.2 Whenever cwnd is greater than ssthresh,
440 * upon each SACK arrival that advances the Cumulative TSN Ack
441 * Point, increase partial_bytes_acked by the total number of
442 * bytes of all new chunks acknowledged in that SACK including
443 * chunks acknowledged by the new Cumulative TSN Ack and by
444 * Gap Ack Blocks.
445 *
446 * When partial_bytes_acked is equal to or greater than cwnd
447 * and before the arrival of the SACK the sender had cwnd or
448 * more bytes of data outstanding (i.e., before arrival of the
449 * SACK, flightsize was greater than or equal to cwnd),
450 * increase cwnd by MTU, and reset partial_bytes_acked to
451 * (partial_bytes_acked - cwnd).
452 */
453 pba += bytes_acked;
454 if (pba >= cwnd) {
455 cwnd += pmtu;
456 pba = ((cwnd < pba) ? (pba - cwnd) : 0);
457 }
458 SCTP_DEBUG_PRINTK("%s: CONGESTION AVOIDANCE: "
459 "transport: %p, bytes_acked: %d, cwnd: %d, "
460 "ssthresh: %d, flight_size: %d, pba: %d\n",
Harvey Harrison0dc47872008-03-05 20:47:47 -0800461 __func__,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700462 transport, bytes_acked, cwnd,
463 ssthresh, flight_size, pba);
464 }
465
466 transport->cwnd = cwnd;
467 transport->partial_bytes_acked = pba;
468}
469
470/* This routine is used to lower the transport's cwnd when congestion is
471 * detected.
472 */
473void sctp_transport_lower_cwnd(struct sctp_transport *transport,
474 sctp_lower_cwnd_t reason)
475{
Vlad Yasevichcf9b4812010-04-30 22:41:10 -0400476 struct sctp_association *asoc = transport->asoc;
477
Linus Torvalds1da177e2005-04-16 15:20:36 -0700478 switch (reason) {
479 case SCTP_LOWER_CWND_T3_RTX:
480 /* RFC 2960 Section 7.2.3, sctpimpguide
481 * When the T3-rtx timer expires on an address, SCTP should
482 * perform slow start by:
483 * ssthresh = max(cwnd/2, 4*MTU)
484 * cwnd = 1*MTU
485 * partial_bytes_acked = 0
486 */
487 transport->ssthresh = max(transport->cwnd/2,
Vlad Yasevichcf9b4812010-04-30 22:41:10 -0400488 4*asoc->pathmtu);
489 transport->cwnd = asoc->pathmtu;
Vlad Yasevich33ce8282009-09-04 18:20:58 -0400490
Vlad Yasevichcf9b4812010-04-30 22:41:10 -0400491 /* T3-rtx also clears fast recovery */
492 asoc->fast_recovery = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700493 break;
494
495 case SCTP_LOWER_CWND_FAST_RTX:
496 /* RFC 2960 7.2.4 Adjust the ssthresh and cwnd of the
497 * destination address(es) to which the missing DATA chunks
498 * were last sent, according to the formula described in
499 * Section 7.2.3.
YOSHIFUJI Hideakid808ad92007-02-09 23:25:18 +0900500 *
501 * RFC 2960 7.2.3, sctpimpguide Upon detection of packet
Linus Torvalds1da177e2005-04-16 15:20:36 -0700502 * losses from SACK (see Section 7.2.4), An endpoint
503 * should do the following:
504 * ssthresh = max(cwnd/2, 4*MTU)
505 * cwnd = ssthresh
506 * partial_bytes_acked = 0
507 */
Vlad Yasevichcf9b4812010-04-30 22:41:10 -0400508 if (asoc->fast_recovery)
Vlad Yasevicha6465232008-06-04 12:38:43 -0700509 return;
510
511 /* Mark Fast recovery */
Vlad Yasevichcf9b4812010-04-30 22:41:10 -0400512 asoc->fast_recovery = 1;
513 asoc->fast_recovery_exit = asoc->next_tsn - 1;
Vlad Yasevicha6465232008-06-04 12:38:43 -0700514
Linus Torvalds1da177e2005-04-16 15:20:36 -0700515 transport->ssthresh = max(transport->cwnd/2,
Vlad Yasevichcf9b4812010-04-30 22:41:10 -0400516 4*asoc->pathmtu);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700517 transport->cwnd = transport->ssthresh;
518 break;
519
520 case SCTP_LOWER_CWND_ECNE:
521 /* RFC 2481 Section 6.1.2.
522 * If the sender receives an ECN-Echo ACK packet
523 * then the sender knows that congestion was encountered in the
524 * network on the path from the sender to the receiver. The
525 * indication of congestion should be treated just as a
526 * congestion loss in non-ECN Capable TCP. That is, the TCP
527 * source halves the congestion window "cwnd" and reduces the
528 * slow start threshold "ssthresh".
529 * A critical condition is that TCP does not react to
530 * congestion indications more than once every window of
531 * data (or more loosely more than once every round-trip time).
532 */
Wei Yongjunf61f6f82009-03-02 09:46:13 +0000533 if (time_after(jiffies, transport->last_time_ecne_reduced +
534 transport->rtt)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700535 transport->ssthresh = max(transport->cwnd/2,
Vlad Yasevichcf9b4812010-04-30 22:41:10 -0400536 4*asoc->pathmtu);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700537 transport->cwnd = transport->ssthresh;
538 transport->last_time_ecne_reduced = jiffies;
539 }
540 break;
541
542 case SCTP_LOWER_CWND_INACTIVE:
543 /* RFC 2960 Section 7.2.1, sctpimpguide
544 * When the endpoint does not transmit data on a given
545 * transport address, the cwnd of the transport address
546 * should be adjusted to max(cwnd/2, 4*MTU) per RTO.
547 * NOTE: Although the draft recommends that this check needs
548 * to be done every RTO interval, we do it every hearbeat
549 * interval.
550 */
Vlad Yasevich245cba72009-11-23 15:53:58 -0500551 transport->cwnd = max(transport->cwnd/2,
Vlad Yasevichcf9b4812010-04-30 22:41:10 -0400552 4*asoc->pathmtu);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700553 break;
Stephen Hemminger3ff50b72007-04-20 17:09:22 -0700554 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700555
556 transport->partial_bytes_acked = 0;
557 SCTP_DEBUG_PRINTK("%s: transport: %p reason: %d cwnd: "
Harvey Harrison0dc47872008-03-05 20:47:47 -0800558 "%d ssthresh: %d\n", __func__,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700559 transport, reason,
560 transport->cwnd, transport->ssthresh);
561}
562
Vlad Yasevich46d5a802009-11-23 15:54:00 -0500563/* Apply Max.Burst limit to the congestion window:
564 * sctpimpguide-05 2.14.2
565 * D) When the time comes for the sender to
566 * transmit new DATA chunks, the protocol parameter Max.Burst MUST
567 * first be applied to limit how many new DATA chunks may be sent.
568 * The limit is applied by adjusting cwnd as follows:
569 * if ((flightsize+ Max.Burst * MTU) < cwnd)
570 * cwnd = flightsize + Max.Burst * MTU
571 */
572
573void sctp_transport_burst_limited(struct sctp_transport *t)
574{
575 struct sctp_association *asoc = t->asoc;
576 u32 old_cwnd = t->cwnd;
577 u32 max_burst_bytes;
578
579 if (t->burst_limited)
580 return;
581
582 max_burst_bytes = t->flight_size + (asoc->max_burst * asoc->pathmtu);
583 if (max_burst_bytes < old_cwnd) {
584 t->cwnd = max_burst_bytes;
585 t->burst_limited = old_cwnd;
586 }
587}
588
589/* Restore the old cwnd congestion window, after the burst had it's
590 * desired effect.
591 */
592void sctp_transport_burst_reset(struct sctp_transport *t)
593{
594 if (t->burst_limited) {
595 t->cwnd = t->burst_limited;
596 t->burst_limited = 0;
597 }
598}
599
Linus Torvalds1da177e2005-04-16 15:20:36 -0700600/* What is the next timeout value for this transport? */
601unsigned long sctp_transport_timeout(struct sctp_transport *t)
602{
603 unsigned long timeout;
Sridhar Samudralaad8fec12006-07-21 14:48:50 -0700604 timeout = t->rto + sctp_jitter(t->rto);
605 if (t->state != SCTP_UNCONFIRMED)
606 timeout += t->hbinterval;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700607 timeout += jiffies;
608 return timeout;
609}
Vlad Yasevich749bf922007-03-19 17:02:30 -0700610
611/* Reset transport variables to their initial values */
612void sctp_transport_reset(struct sctp_transport *t)
613{
614 struct sctp_association *asoc = t->asoc;
615
616 /* RFC 2960 (bis), Section 5.2.4
617 * All the congestion control parameters (e.g., cwnd, ssthresh)
618 * related to this peer MUST be reset to their initial values
619 * (see Section 6.2.1)
620 */
621 t->cwnd = min(4*asoc->pathmtu, max_t(__u32, 2*asoc->pathmtu, 4380));
Vlad Yasevich46d5a802009-11-23 15:54:00 -0500622 t->burst_limited = 0;
Vlad Yasevich289f4242007-03-22 12:26:25 -0700623 t->ssthresh = asoc->peer.i.a_rwnd;
Andrei Pelinescu-Onciul5fdd4ba2009-11-29 00:14:02 -0800624 t->rto = asoc->rto_initial;
Vlad Yasevich749bf922007-03-19 17:02:30 -0700625 t->rtt = 0;
626 t->srtt = 0;
627 t->rttvar = 0;
628
629 /* Reset these additional varibles so that we have a clean
630 * slate.
631 */
632 t->partial_bytes_acked = 0;
633 t->flight_size = 0;
634 t->error_count = 0;
635 t->rto_pending = 0;
Vlad Yasevichfaee47c2009-02-13 08:33:43 +0000636 t->hb_sent = 0;
Vlad Yasevich749bf922007-03-19 17:02:30 -0700637
638 /* Initialize the state information for SFR-CACC */
639 t->cacc.changeover_active = 0;
640 t->cacc.cycling_changeover = 0;
641 t->cacc.next_tsn_at_change = 0;
642 t->cacc.cacc_saw_newack = 0;
643}