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60c778b2 | 1 | /* SCTP kernel implementation |
1da177e4 LT |
2 | * 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 | * | |
60c778b2 | 8 | * This file is part of the SCTP kernel implementation |
1da177e4 LT |
9 | * |
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 | * | |
60c778b2 | 14 | * This SCTP implementation is free software; |
1da177e4 LT |
15 | * 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 | * | |
60c778b2 | 20 | * This SCTP implementation is distributed in the hope that it |
1da177e4 LT |
21 | * 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 | ||
145ce502 JP |
51 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
52 | ||
5a0e3ad6 | 53 | #include <linux/slab.h> |
1da177e4 | 54 | #include <linux/types.h> |
ad8fec17 | 55 | #include <linux/random.h> |
1da177e4 LT |
56 | #include <net/sctp/sctp.h> |
57 | #include <net/sctp/sm.h> | |
58 | ||
59 | /* 1st Level Abstractions. */ | |
60 | ||
61 | /* Initialize a new transport from provided memory. */ | |
89bf3450 EB |
62 | static struct sctp_transport *sctp_transport_init(struct net *net, |
63 | struct sctp_transport *peer, | |
1da177e4 | 64 | const union sctp_addr *addr, |
dd0fc66f | 65 | gfp_t gfp) |
1da177e4 LT |
66 | { |
67 | /* Copy in the address. */ | |
68 | peer->ipaddr = *addr; | |
69 | peer->af_specific = sctp_get_af_specific(addr->sa.sa_family); | |
1da177e4 LT |
70 | memset(&peer->saddr, 0, sizeof(union sctp_addr)); |
71 | ||
4244854d NH |
72 | peer->sack_generation = 0; |
73 | ||
1da177e4 LT |
74 | /* From 6.3.1 RTO Calculation: |
75 | * | |
76 | * C1) Until an RTT measurement has been made for a packet sent to the | |
77 | * given destination transport address, set RTO to the protocol | |
78 | * parameter 'RTO.Initial'. | |
79 | */ | |
e1fc3b14 | 80 | peer->rto = msecs_to_jiffies(net->sctp.rto_initial); |
1da177e4 LT |
81 | |
82 | peer->last_time_heard = jiffies; | |
1da177e4 LT |
83 | peer->last_time_ecne_reduced = jiffies; |
84 | ||
52ccb8e9 FF |
85 | peer->param_flags = SPP_HB_DISABLE | |
86 | SPP_PMTUD_ENABLE | | |
87 | SPP_SACKDELAY_ENABLE; | |
1da177e4 LT |
88 | |
89 | /* Initialize the default path max_retrans. */ | |
e1fc3b14 EB |
90 | peer->pathmaxrxt = net->sctp.max_retrans_path; |
91 | peer->pf_retrans = net->sctp.pf_retrans; | |
1da177e4 LT |
92 | |
93 | INIT_LIST_HEAD(&peer->transmitted); | |
94 | INIT_LIST_HEAD(&peer->send_ready); | |
95 | INIT_LIST_HEAD(&peer->transports); | |
96 | ||
b24b8a24 PE |
97 | setup_timer(&peer->T3_rtx_timer, sctp_generate_t3_rtx_event, |
98 | (unsigned long)peer); | |
99 | setup_timer(&peer->hb_timer, sctp_generate_heartbeat_event, | |
100 | (unsigned long)peer); | |
50b5d6ad VY |
101 | setup_timer(&peer->proto_unreach_timer, |
102 | sctp_generate_proto_unreach_event, (unsigned long)peer); | |
1da177e4 | 103 | |
ad8fec17 SS |
104 | /* Initialize the 64-bit random nonce sent with heartbeat. */ |
105 | get_random_bytes(&peer->hb_nonce, sizeof(peer->hb_nonce)); | |
106 | ||
1da177e4 | 107 | atomic_set(&peer->refcnt, 1); |
1da177e4 LT |
108 | |
109 | return peer; | |
110 | } | |
111 | ||
112 | /* Allocate and initialize a new transport. */ | |
89bf3450 EB |
113 | struct sctp_transport *sctp_transport_new(struct net *net, |
114 | const union sctp_addr *addr, | |
dd0fc66f | 115 | gfp_t gfp) |
1da177e4 | 116 | { |
d808ad9a | 117 | struct sctp_transport *transport; |
1da177e4 | 118 | |
939cfa75 | 119 | transport = kzalloc(sizeof(*transport), gfp); |
1da177e4 LT |
120 | if (!transport) |
121 | goto fail; | |
122 | ||
89bf3450 | 123 | if (!sctp_transport_init(net, transport, addr, gfp)) |
1da177e4 LT |
124 | goto fail_init; |
125 | ||
1da177e4 LT |
126 | SCTP_DBG_OBJCNT_INC(transport); |
127 | ||
128 | return transport; | |
129 | ||
130 | fail_init: | |
131 | kfree(transport); | |
132 | ||
133 | fail: | |
134 | return NULL; | |
135 | } | |
136 | ||
137 | /* This transport is no longer needed. Free up if possible, or | |
138 | * delay until it last reference count. | |
139 | */ | |
140 | void sctp_transport_free(struct sctp_transport *transport) | |
141 | { | |
142 | transport->dead = 1; | |
143 | ||
144 | /* Try to delete the heartbeat timer. */ | |
145 | if (del_timer(&transport->hb_timer)) | |
146 | sctp_transport_put(transport); | |
147 | ||
148 | /* Delete the T3_rtx timer if it's active. | |
149 | * There is no point in not doing this now and letting | |
150 | * structure hang around in memory since we know | |
151 | * the tranport is going away. | |
152 | */ | |
25cc4ae9 | 153 | if (del_timer(&transport->T3_rtx_timer)) |
1da177e4 LT |
154 | sctp_transport_put(transport); |
155 | ||
55fa0cfd | 156 | /* Delete the ICMP proto unreachable timer if it's active. */ |
25cc4ae9 | 157 | if (del_timer(&transport->proto_unreach_timer)) |
55fa0cfd | 158 | sctp_association_put(transport->asoc); |
1da177e4 LT |
159 | |
160 | sctp_transport_put(transport); | |
161 | } | |
162 | ||
45122ca2 | 163 | static void sctp_transport_destroy_rcu(struct rcu_head *head) |
1da177e4 | 164 | { |
45122ca2 | 165 | struct sctp_transport *transport; |
1da177e4 | 166 | |
45122ca2 | 167 | transport = container_of(head, struct sctp_transport, rcu); |
1da177e4 LT |
168 | |
169 | dst_release(transport->dst); | |
170 | kfree(transport); | |
171 | SCTP_DBG_OBJCNT_DEC(transport); | |
172 | } | |
173 | ||
45122ca2 TG |
174 | /* Destroy the transport data structure. |
175 | * Assumes there are no more users of this structure. | |
176 | */ | |
177 | static void sctp_transport_destroy(struct sctp_transport *transport) | |
178 | { | |
179 | SCTP_ASSERT(transport->dead, "Transport is not dead", return); | |
180 | ||
181 | call_rcu(&transport->rcu, sctp_transport_destroy_rcu); | |
8c98653f DB |
182 | |
183 | sctp_packet_free(&transport->packet); | |
184 | ||
185 | if (transport->asoc) | |
186 | sctp_association_put(transport->asoc); | |
45122ca2 TG |
187 | } |
188 | ||
1da177e4 LT |
189 | /* Start T3_rtx timer if it is not already running and update the heartbeat |
190 | * timer. This routine is called every time a DATA chunk is sent. | |
191 | */ | |
d9efc223 | 192 | void sctp_transport_reset_timers(struct sctp_transport *transport) |
1da177e4 LT |
193 | { |
194 | /* RFC 2960 6.3.2 Retransmission Timer Rules | |
195 | * | |
196 | * R1) Every time a DATA chunk is sent to any address(including a | |
197 | * retransmission), if the T3-rtx timer of that address is not running | |
198 | * start it running so that it will expire after the RTO of that | |
199 | * address. | |
200 | */ | |
201 | ||
d9efc223 | 202 | if (!timer_pending(&transport->T3_rtx_timer)) |
1da177e4 LT |
203 | if (!mod_timer(&transport->T3_rtx_timer, |
204 | jiffies + transport->rto)) | |
205 | sctp_transport_hold(transport); | |
206 | ||
207 | /* When a data chunk is sent, reset the heartbeat interval. */ | |
208 | if (!mod_timer(&transport->hb_timer, | |
209 | sctp_transport_timeout(transport))) | |
210 | sctp_transport_hold(transport); | |
211 | } | |
212 | ||
213 | /* This transport has been assigned to an association. | |
214 | * Initialize fields from the association or from the sock itself. | |
215 | * Register the reference count in the association. | |
216 | */ | |
217 | void sctp_transport_set_owner(struct sctp_transport *transport, | |
218 | struct sctp_association *asoc) | |
219 | { | |
220 | transport->asoc = asoc; | |
221 | sctp_association_hold(asoc); | |
222 | } | |
223 | ||
224 | /* Initialize the pmtu of a transport. */ | |
9914ae3c | 225 | void sctp_transport_pmtu(struct sctp_transport *transport, struct sock *sk) |
1da177e4 | 226 | { |
da0420be | 227 | /* If we don't have a fresh route, look one up */ |
f5b0a874 | 228 | if (!transport->dst || transport->dst->obsolete) { |
da0420be VY |
229 | dst_release(transport->dst); |
230 | transport->af_specific->get_dst(transport, &transport->saddr, | |
8663c938 | 231 | &transport->fl, sk); |
da0420be | 232 | } |
1da177e4 | 233 | |
da0420be VY |
234 | if (transport->dst) { |
235 | transport->pathmtu = dst_mtu(transport->dst); | |
1da177e4 | 236 | } else |
52ccb8e9 | 237 | transport->pathmtu = SCTP_DEFAULT_MAXSEGMENT; |
1da177e4 LT |
238 | } |
239 | ||
02f3d4ce | 240 | void sctp_transport_update_pmtu(struct sock *sk, struct sctp_transport *t, u32 pmtu) |
c910b47e VY |
241 | { |
242 | struct dst_entry *dst; | |
243 | ||
244 | if (unlikely(pmtu < SCTP_DEFAULT_MINSEGMENT)) { | |
145ce502 JP |
245 | pr_warn("%s: Reported pmtu %d too low, using default minimum of %d\n", |
246 | __func__, pmtu, | |
247 | SCTP_DEFAULT_MINSEGMENT); | |
c910b47e VY |
248 | /* Use default minimum segment size and disable |
249 | * pmtu discovery on this transport. | |
250 | */ | |
251 | t->pathmtu = SCTP_DEFAULT_MINSEGMENT; | |
c910b47e VY |
252 | } else { |
253 | t->pathmtu = pmtu; | |
254 | } | |
255 | ||
256 | dst = sctp_transport_dst_check(t); | |
02f3d4ce DM |
257 | if (!dst) |
258 | t->af_specific->get_dst(t, &t->saddr, &t->fl, sk); | |
259 | ||
260 | if (dst) { | |
6700c270 | 261 | dst->ops->update_pmtu(dst, sk, NULL, pmtu); |
02f3d4ce DM |
262 | |
263 | dst = sctp_transport_dst_check(t); | |
264 | if (!dst) | |
265 | t->af_specific->get_dst(t, &t->saddr, &t->fl, sk); | |
266 | } | |
c910b47e VY |
267 | } |
268 | ||
1da177e4 LT |
269 | /* Caches the dst entry and source address for a transport's destination |
270 | * address. | |
271 | */ | |
272 | void sctp_transport_route(struct sctp_transport *transport, | |
273 | union sctp_addr *saddr, struct sctp_sock *opt) | |
274 | { | |
275 | struct sctp_association *asoc = transport->asoc; | |
276 | struct sctp_af *af = transport->af_specific; | |
1da177e4 | 277 | |
8663c938 | 278 | af->get_dst(transport, saddr, &transport->fl, sctp_opt2sk(opt)); |
1da177e4 LT |
279 | |
280 | if (saddr) | |
281 | memcpy(&transport->saddr, saddr, sizeof(union sctp_addr)); | |
282 | else | |
8663c938 | 283 | af->get_saddr(opt, transport, &transport->fl); |
1da177e4 | 284 | |
52ccb8e9 FF |
285 | if ((transport->param_flags & SPP_PMTUD_DISABLE) && transport->pathmtu) { |
286 | return; | |
287 | } | |
da0420be VY |
288 | if (transport->dst) { |
289 | transport->pathmtu = dst_mtu(transport->dst); | |
1da177e4 LT |
290 | |
291 | /* Initialize sk->sk_rcv_saddr, if the transport is the | |
292 | * association's active path for getsockname(). | |
d808ad9a | 293 | */ |
a78102e7 VY |
294 | if (asoc && (!asoc->peer.primary_path || |
295 | (transport == asoc->peer.active_path))) | |
bf031fff NH |
296 | opt->pf->af->to_sk_saddr(&transport->saddr, |
297 | asoc->base.sk); | |
1da177e4 | 298 | } else |
52ccb8e9 | 299 | transport->pathmtu = SCTP_DEFAULT_MAXSEGMENT; |
1da177e4 LT |
300 | } |
301 | ||
302 | /* Hold a reference to a transport. */ | |
303 | void sctp_transport_hold(struct sctp_transport *transport) | |
304 | { | |
305 | atomic_inc(&transport->refcnt); | |
306 | } | |
307 | ||
308 | /* Release a reference to a transport and clean up | |
309 | * if there are no more references. | |
310 | */ | |
311 | void sctp_transport_put(struct sctp_transport *transport) | |
312 | { | |
313 | if (atomic_dec_and_test(&transport->refcnt)) | |
314 | sctp_transport_destroy(transport); | |
315 | } | |
316 | ||
317 | /* Update transport's RTO based on the newly calculated RTT. */ | |
318 | void sctp_transport_update_rto(struct sctp_transport *tp, __u32 rtt) | |
319 | { | |
320 | /* Check for valid transport. */ | |
321 | SCTP_ASSERT(tp, "NULL transport", return); | |
322 | ||
323 | /* We should not be doing any RTO updates unless rto_pending is set. */ | |
324 | SCTP_ASSERT(tp->rto_pending, "rto_pending not set", return); | |
325 | ||
326 | if (tp->rttvar || tp->srtt) { | |
e1fc3b14 | 327 | struct net *net = sock_net(tp->asoc->base.sk); |
1da177e4 LT |
328 | /* 6.3.1 C3) When a new RTT measurement R' is made, set |
329 | * RTTVAR <- (1 - RTO.Beta) * RTTVAR + RTO.Beta * |SRTT - R'| | |
330 | * SRTT <- (1 - RTO.Alpha) * SRTT + RTO.Alpha * R' | |
331 | */ | |
332 | ||
333 | /* Note: The above algorithm has been rewritten to | |
334 | * express rto_beta and rto_alpha as inverse powers | |
335 | * of two. | |
336 | * For example, assuming the default value of RTO.Alpha of | |
337 | * 1/8, rto_alpha would be expressed as 3. | |
338 | */ | |
e1fc3b14 | 339 | tp->rttvar = tp->rttvar - (tp->rttvar >> net->sctp.rto_beta) |
92d64c26 | 340 | + (((__u32)abs64((__s64)tp->srtt - (__s64)rtt)) >> net->sctp.rto_beta); |
e1fc3b14 EB |
341 | tp->srtt = tp->srtt - (tp->srtt >> net->sctp.rto_alpha) |
342 | + (rtt >> net->sctp.rto_alpha); | |
1da177e4 LT |
343 | } else { |
344 | /* 6.3.1 C2) When the first RTT measurement R is made, set | |
345 | * SRTT <- R, RTTVAR <- R/2. | |
346 | */ | |
347 | tp->srtt = rtt; | |
348 | tp->rttvar = rtt >> 1; | |
349 | } | |
350 | ||
351 | /* 6.3.1 G1) Whenever RTTVAR is computed, if RTTVAR = 0, then | |
352 | * adjust RTTVAR <- G, where G is the CLOCK GRANULARITY. | |
353 | */ | |
354 | if (tp->rttvar == 0) | |
355 | tp->rttvar = SCTP_CLOCK_GRANULARITY; | |
356 | ||
357 | /* 6.3.1 C3) After the computation, update RTO <- SRTT + 4 * RTTVAR. */ | |
358 | tp->rto = tp->srtt + (tp->rttvar << 2); | |
359 | ||
360 | /* 6.3.1 C6) Whenever RTO is computed, if it is less than RTO.Min | |
361 | * seconds then it is rounded up to RTO.Min seconds. | |
362 | */ | |
363 | if (tp->rto < tp->asoc->rto_min) | |
364 | tp->rto = tp->asoc->rto_min; | |
365 | ||
366 | /* 6.3.1 C7) A maximum value may be placed on RTO provided it is | |
367 | * at least RTO.max seconds. | |
368 | */ | |
369 | if (tp->rto > tp->asoc->rto_max) | |
370 | tp->rto = tp->asoc->rto_max; | |
371 | ||
196d6759 | 372 | sctp_max_rto(tp->asoc, tp); |
1da177e4 LT |
373 | tp->rtt = rtt; |
374 | ||
375 | /* Reset rto_pending so that a new RTT measurement is started when a | |
376 | * new data chunk is sent. | |
377 | */ | |
378 | tp->rto_pending = 0; | |
379 | ||
380 | SCTP_DEBUG_PRINTK("%s: transport: %p, rtt: %d, srtt: %d " | |
0dc47877 | 381 | "rttvar: %d, rto: %ld\n", __func__, |
1da177e4 LT |
382 | tp, rtt, tp->srtt, tp->rttvar, tp->rto); |
383 | } | |
384 | ||
385 | /* This routine updates the transport's cwnd and partial_bytes_acked | |
386 | * parameters based on the bytes acked in the received SACK. | |
387 | */ | |
388 | void sctp_transport_raise_cwnd(struct sctp_transport *transport, | |
389 | __u32 sack_ctsn, __u32 bytes_acked) | |
390 | { | |
cf9b4812 | 391 | struct sctp_association *asoc = transport->asoc; |
1da177e4 LT |
392 | __u32 cwnd, ssthresh, flight_size, pba, pmtu; |
393 | ||
394 | cwnd = transport->cwnd; | |
395 | flight_size = transport->flight_size; | |
396 | ||
a6465234 | 397 | /* See if we need to exit Fast Recovery first */ |
cf9b4812 VY |
398 | if (asoc->fast_recovery && |
399 | TSN_lte(asoc->fast_recovery_exit, sack_ctsn)) | |
400 | asoc->fast_recovery = 0; | |
a6465234 | 401 | |
1da177e4 | 402 | /* The appropriate cwnd increase algorithm is performed if, and only |
a6465234 | 403 | * if the cumulative TSN whould advanced and the congestion window is |
1da177e4 LT |
404 | * being fully utilized. |
405 | */ | |
a6465234 | 406 | if (TSN_lte(sack_ctsn, transport->asoc->ctsn_ack_point) || |
1da177e4 LT |
407 | (flight_size < cwnd)) |
408 | return; | |
409 | ||
410 | ssthresh = transport->ssthresh; | |
411 | pba = transport->partial_bytes_acked; | |
52ccb8e9 | 412 | pmtu = transport->asoc->pathmtu; |
1da177e4 LT |
413 | |
414 | if (cwnd <= ssthresh) { | |
a6465234 VY |
415 | /* RFC 4960 7.2.1 |
416 | * o When cwnd is less than or equal to ssthresh, an SCTP | |
417 | * endpoint MUST use the slow-start algorithm to increase | |
418 | * cwnd only if the current congestion window is being fully | |
419 | * utilized, an incoming SACK advances the Cumulative TSN | |
420 | * Ack Point, and the data sender is not in Fast Recovery. | |
421 | * Only when these three conditions are met can the cwnd be | |
422 | * increased; otherwise, the cwnd MUST not be increased. | |
423 | * If these conditions are met, then cwnd MUST be increased | |
424 | * by, at most, the lesser of 1) the total size of the | |
425 | * previously outstanding DATA chunk(s) acknowledged, and | |
426 | * 2) the destination's path MTU. This upper bound protects | |
427 | * against the ACK-Splitting attack outlined in [SAVAGE99]. | |
1da177e4 | 428 | */ |
cf9b4812 | 429 | if (asoc->fast_recovery) |
a6465234 VY |
430 | return; |
431 | ||
1da177e4 LT |
432 | if (bytes_acked > pmtu) |
433 | cwnd += pmtu; | |
434 | else | |
435 | cwnd += bytes_acked; | |
436 | SCTP_DEBUG_PRINTK("%s: SLOW START: transport: %p, " | |
437 | "bytes_acked: %d, cwnd: %d, ssthresh: %d, " | |
438 | "flight_size: %d, pba: %d\n", | |
0dc47877 | 439 | __func__, |
1da177e4 LT |
440 | transport, bytes_acked, cwnd, |
441 | ssthresh, flight_size, pba); | |
442 | } else { | |
443 | /* RFC 2960 7.2.2 Whenever cwnd is greater than ssthresh, | |
444 | * upon each SACK arrival that advances the Cumulative TSN Ack | |
445 | * Point, increase partial_bytes_acked by the total number of | |
446 | * bytes of all new chunks acknowledged in that SACK including | |
447 | * chunks acknowledged by the new Cumulative TSN Ack and by | |
448 | * Gap Ack Blocks. | |
449 | * | |
450 | * When partial_bytes_acked is equal to or greater than cwnd | |
451 | * and before the arrival of the SACK the sender had cwnd or | |
452 | * more bytes of data outstanding (i.e., before arrival of the | |
453 | * SACK, flightsize was greater than or equal to cwnd), | |
454 | * increase cwnd by MTU, and reset partial_bytes_acked to | |
455 | * (partial_bytes_acked - cwnd). | |
456 | */ | |
457 | pba += bytes_acked; | |
458 | if (pba >= cwnd) { | |
459 | cwnd += pmtu; | |
460 | pba = ((cwnd < pba) ? (pba - cwnd) : 0); | |
461 | } | |
462 | SCTP_DEBUG_PRINTK("%s: CONGESTION AVOIDANCE: " | |
463 | "transport: %p, bytes_acked: %d, cwnd: %d, " | |
464 | "ssthresh: %d, flight_size: %d, pba: %d\n", | |
0dc47877 | 465 | __func__, |
1da177e4 LT |
466 | transport, bytes_acked, cwnd, |
467 | ssthresh, flight_size, pba); | |
468 | } | |
469 | ||
470 | transport->cwnd = cwnd; | |
471 | transport->partial_bytes_acked = pba; | |
472 | } | |
473 | ||
474 | /* This routine is used to lower the transport's cwnd when congestion is | |
475 | * detected. | |
476 | */ | |
477 | void sctp_transport_lower_cwnd(struct sctp_transport *transport, | |
478 | sctp_lower_cwnd_t reason) | |
479 | { | |
cf9b4812 VY |
480 | struct sctp_association *asoc = transport->asoc; |
481 | ||
1da177e4 LT |
482 | switch (reason) { |
483 | case SCTP_LOWER_CWND_T3_RTX: | |
484 | /* RFC 2960 Section 7.2.3, sctpimpguide | |
485 | * When the T3-rtx timer expires on an address, SCTP should | |
486 | * perform slow start by: | |
487 | * ssthresh = max(cwnd/2, 4*MTU) | |
488 | * cwnd = 1*MTU | |
489 | * partial_bytes_acked = 0 | |
490 | */ | |
491 | transport->ssthresh = max(transport->cwnd/2, | |
cf9b4812 VY |
492 | 4*asoc->pathmtu); |
493 | transport->cwnd = asoc->pathmtu; | |
33ce8281 | 494 | |
cf9b4812 VY |
495 | /* T3-rtx also clears fast recovery */ |
496 | asoc->fast_recovery = 0; | |
1da177e4 LT |
497 | break; |
498 | ||
499 | case SCTP_LOWER_CWND_FAST_RTX: | |
500 | /* RFC 2960 7.2.4 Adjust the ssthresh and cwnd of the | |
501 | * destination address(es) to which the missing DATA chunks | |
502 | * were last sent, according to the formula described in | |
503 | * Section 7.2.3. | |
d808ad9a YH |
504 | * |
505 | * RFC 2960 7.2.3, sctpimpguide Upon detection of packet | |
1da177e4 LT |
506 | * losses from SACK (see Section 7.2.4), An endpoint |
507 | * should do the following: | |
508 | * ssthresh = max(cwnd/2, 4*MTU) | |
509 | * cwnd = ssthresh | |
510 | * partial_bytes_acked = 0 | |
511 | */ | |
cf9b4812 | 512 | if (asoc->fast_recovery) |
a6465234 VY |
513 | return; |
514 | ||
515 | /* Mark Fast recovery */ | |
cf9b4812 VY |
516 | asoc->fast_recovery = 1; |
517 | asoc->fast_recovery_exit = asoc->next_tsn - 1; | |
a6465234 | 518 | |
1da177e4 | 519 | transport->ssthresh = max(transport->cwnd/2, |
cf9b4812 | 520 | 4*asoc->pathmtu); |
1da177e4 LT |
521 | transport->cwnd = transport->ssthresh; |
522 | break; | |
523 | ||
524 | case SCTP_LOWER_CWND_ECNE: | |
525 | /* RFC 2481 Section 6.1.2. | |
526 | * If the sender receives an ECN-Echo ACK packet | |
527 | * then the sender knows that congestion was encountered in the | |
528 | * network on the path from the sender to the receiver. The | |
529 | * indication of congestion should be treated just as a | |
530 | * congestion loss in non-ECN Capable TCP. That is, the TCP | |
531 | * source halves the congestion window "cwnd" and reduces the | |
532 | * slow start threshold "ssthresh". | |
533 | * A critical condition is that TCP does not react to | |
534 | * congestion indications more than once every window of | |
535 | * data (or more loosely more than once every round-trip time). | |
536 | */ | |
f61f6f82 WY |
537 | if (time_after(jiffies, transport->last_time_ecne_reduced + |
538 | transport->rtt)) { | |
1da177e4 | 539 | transport->ssthresh = max(transport->cwnd/2, |
cf9b4812 | 540 | 4*asoc->pathmtu); |
1da177e4 LT |
541 | transport->cwnd = transport->ssthresh; |
542 | transport->last_time_ecne_reduced = jiffies; | |
543 | } | |
544 | break; | |
545 | ||
546 | case SCTP_LOWER_CWND_INACTIVE: | |
547 | /* RFC 2960 Section 7.2.1, sctpimpguide | |
548 | * When the endpoint does not transmit data on a given | |
549 | * transport address, the cwnd of the transport address | |
550 | * should be adjusted to max(cwnd/2, 4*MTU) per RTO. | |
551 | * NOTE: Although the draft recommends that this check needs | |
552 | * to be done every RTO interval, we do it every hearbeat | |
553 | * interval. | |
554 | */ | |
245cba7e | 555 | transport->cwnd = max(transport->cwnd/2, |
cf9b4812 | 556 | 4*asoc->pathmtu); |
1da177e4 | 557 | break; |
3ff50b79 | 558 | } |
1da177e4 LT |
559 | |
560 | transport->partial_bytes_acked = 0; | |
561 | SCTP_DEBUG_PRINTK("%s: transport: %p reason: %d cwnd: " | |
0dc47877 | 562 | "%d ssthresh: %d\n", __func__, |
1da177e4 LT |
563 | transport, reason, |
564 | transport->cwnd, transport->ssthresh); | |
565 | } | |
566 | ||
46d5a808 VY |
567 | /* Apply Max.Burst limit to the congestion window: |
568 | * sctpimpguide-05 2.14.2 | |
569 | * D) When the time comes for the sender to | |
570 | * transmit new DATA chunks, the protocol parameter Max.Burst MUST | |
571 | * first be applied to limit how many new DATA chunks may be sent. | |
572 | * The limit is applied by adjusting cwnd as follows: | |
573 | * if ((flightsize+ Max.Burst * MTU) < cwnd) | |
574 | * cwnd = flightsize + Max.Burst * MTU | |
575 | */ | |
576 | ||
577 | void sctp_transport_burst_limited(struct sctp_transport *t) | |
578 | { | |
579 | struct sctp_association *asoc = t->asoc; | |
580 | u32 old_cwnd = t->cwnd; | |
581 | u32 max_burst_bytes; | |
582 | ||
583 | if (t->burst_limited) | |
584 | return; | |
585 | ||
586 | max_burst_bytes = t->flight_size + (asoc->max_burst * asoc->pathmtu); | |
587 | if (max_burst_bytes < old_cwnd) { | |
588 | t->cwnd = max_burst_bytes; | |
589 | t->burst_limited = old_cwnd; | |
590 | } | |
591 | } | |
592 | ||
593 | /* Restore the old cwnd congestion window, after the burst had it's | |
594 | * desired effect. | |
595 | */ | |
596 | void sctp_transport_burst_reset(struct sctp_transport *t) | |
597 | { | |
598 | if (t->burst_limited) { | |
599 | t->cwnd = t->burst_limited; | |
600 | t->burst_limited = 0; | |
601 | } | |
602 | } | |
603 | ||
1da177e4 LT |
604 | /* What is the next timeout value for this transport? */ |
605 | unsigned long sctp_transport_timeout(struct sctp_transport *t) | |
606 | { | |
607 | unsigned long timeout; | |
ad8fec17 | 608 | timeout = t->rto + sctp_jitter(t->rto); |
5aa93bcf NH |
609 | if ((t->state != SCTP_UNCONFIRMED) && |
610 | (t->state != SCTP_PF)) | |
ad8fec17 | 611 | timeout += t->hbinterval; |
1da177e4 LT |
612 | timeout += jiffies; |
613 | return timeout; | |
614 | } | |
749bf921 VY |
615 | |
616 | /* Reset transport variables to their initial values */ | |
617 | void sctp_transport_reset(struct sctp_transport *t) | |
618 | { | |
619 | struct sctp_association *asoc = t->asoc; | |
620 | ||
621 | /* RFC 2960 (bis), Section 5.2.4 | |
622 | * All the congestion control parameters (e.g., cwnd, ssthresh) | |
623 | * related to this peer MUST be reset to their initial values | |
624 | * (see Section 6.2.1) | |
625 | */ | |
626 | t->cwnd = min(4*asoc->pathmtu, max_t(__u32, 2*asoc->pathmtu, 4380)); | |
46d5a808 | 627 | t->burst_limited = 0; |
289f4249 | 628 | t->ssthresh = asoc->peer.i.a_rwnd; |
5fdd4bae | 629 | t->rto = asoc->rto_initial; |
196d6759 | 630 | sctp_max_rto(asoc, t); |
749bf921 VY |
631 | t->rtt = 0; |
632 | t->srtt = 0; | |
633 | t->rttvar = 0; | |
634 | ||
635 | /* Reset these additional varibles so that we have a clean | |
636 | * slate. | |
637 | */ | |
638 | t->partial_bytes_acked = 0; | |
639 | t->flight_size = 0; | |
640 | t->error_count = 0; | |
641 | t->rto_pending = 0; | |
faee47cd | 642 | t->hb_sent = 0; |
749bf921 VY |
643 | |
644 | /* Initialize the state information for SFR-CACC */ | |
645 | t->cacc.changeover_active = 0; | |
646 | t->cacc.cycling_changeover = 0; | |
647 | t->cacc.next_tsn_at_change = 0; | |
648 | t->cacc.cacc_saw_newack = 0; | |
649 | } | |
ddc4bbee MH |
650 | |
651 | /* Schedule retransmission on the given transport */ | |
652 | void sctp_transport_immediate_rtx(struct sctp_transport *t) | |
653 | { | |
654 | /* Stop pending T3_rtx_timer */ | |
25cc4ae9 | 655 | if (del_timer(&t->T3_rtx_timer)) |
ddc4bbee | 656 | sctp_transport_put(t); |
25cc4ae9 | 657 | |
ddc4bbee MH |
658 | sctp_retransmit(&t->asoc->outqueue, t, SCTP_RTXR_T3_RTX); |
659 | if (!timer_pending(&t->T3_rtx_timer)) { | |
660 | if (!mod_timer(&t->T3_rtx_timer, jiffies + t->rto)) | |
661 | sctp_transport_hold(t); | |
662 | } | |
663 | return; | |
664 | } |