1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* SCTP kernel implementation
3 * (C) Copyright IBM Corp. 2001, 2004
4 * Copyright (c) 1999-2000 Cisco, Inc.
5 * Copyright (c) 1999-2001 Motorola, Inc.
6 * Copyright (c) 2001-2003 Intel Corp.
7 *
8 * This file is part of the SCTP kernel implementation
9 *
10 * These functions implement the sctp_outq class. The outqueue handles
11 * bundling and queueing of outgoing SCTP chunks.
12 *
13 * Please send any bug reports or fixes you make to the
14 * email address(es):
15 * lksctp developers <linux-sctp@vger.kernel.org>
16 *
17 * Written or modified by:
18 * La Monte H.P. Yarroll <piggy@acm.org>
19 * Karl Knutson <karl@athena.chicago.il.us>
20 * Perry Melange <pmelange@null.cc.uic.edu>
21 * Xingang Guo <xingang.guo@intel.com>
22 * Hui Huang <hui.huang@nokia.com>
23 * Sridhar Samudrala <sri@us.ibm.com>
24 * Jon Grimm <jgrimm@us.ibm.com>
25 */
26
27 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
28
29 #include <linux/types.h>
30 #include <linux/list.h> /* For struct list_head */
31 #include <linux/socket.h>
32 #include <linux/ip.h>
33 #include <linux/slab.h>
34 #include <net/sock.h> /* For skb_set_owner_w */
35
36 #include <net/sctp/sctp.h>
37 #include <net/sctp/sm.h>
38 #include <net/sctp/stream_sched.h>
39 #include <trace/events/sctp.h>
40
41 /* Declare internal functions here. */
42 static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn);
43 static void sctp_check_transmitted(struct sctp_outq *q,
44 struct list_head *transmitted_queue,
45 struct sctp_transport *transport,
46 union sctp_addr *saddr,
47 struct sctp_sackhdr *sack,
48 __u32 *highest_new_tsn);
49
50 static void sctp_mark_missing(struct sctp_outq *q,
51 struct list_head *transmitted_queue,
52 struct sctp_transport *transport,
53 __u32 highest_new_tsn,
54 int count_of_newacks);
55
56 static void sctp_outq_flush(struct sctp_outq *q, int rtx_timeout, gfp_t gfp);
57
58 /* Add data to the front of the queue. */
sctp_outq_head_data(struct sctp_outq * q,struct sctp_chunk * ch)59 static inline void sctp_outq_head_data(struct sctp_outq *q,
60 struct sctp_chunk *ch)
61 {
62 struct sctp_stream_out_ext *oute;
63 __u16 stream;
64
65 list_add(&ch->list, &q->out_chunk_list);
66 q->out_qlen += ch->skb->len;
67
68 stream = sctp_chunk_stream_no(ch);
69 oute = SCTP_SO(&q->asoc->stream, stream)->ext;
70 list_add(&ch->stream_list, &oute->outq);
71 }
72
73 /* Take data from the front of the queue. */
sctp_outq_dequeue_data(struct sctp_outq * q)74 static inline struct sctp_chunk *sctp_outq_dequeue_data(struct sctp_outq *q)
75 {
76 return q->sched->dequeue(q);
77 }
78
79 /* Add data chunk to the end of the queue. */
sctp_outq_tail_data(struct sctp_outq * q,struct sctp_chunk * ch)80 static inline void sctp_outq_tail_data(struct sctp_outq *q,
81 struct sctp_chunk *ch)
82 {
83 struct sctp_stream_out_ext *oute;
84 __u16 stream;
85
86 list_add_tail(&ch->list, &q->out_chunk_list);
87 q->out_qlen += ch->skb->len;
88
89 stream = sctp_chunk_stream_no(ch);
90 oute = SCTP_SO(&q->asoc->stream, stream)->ext;
91 list_add_tail(&ch->stream_list, &oute->outq);
92 }
93
94 /*
95 * SFR-CACC algorithm:
96 * D) If count_of_newacks is greater than or equal to 2
97 * and t was not sent to the current primary then the
98 * sender MUST NOT increment missing report count for t.
99 */
sctp_cacc_skip_3_1_d(struct sctp_transport * primary,struct sctp_transport * transport,int count_of_newacks)100 static inline int sctp_cacc_skip_3_1_d(struct sctp_transport *primary,
101 struct sctp_transport *transport,
102 int count_of_newacks)
103 {
104 if (count_of_newacks >= 2 && transport != primary)
105 return 1;
106 return 0;
107 }
108
109 /*
110 * SFR-CACC algorithm:
111 * F) If count_of_newacks is less than 2, let d be the
112 * destination to which t was sent. If cacc_saw_newack
113 * is 0 for destination d, then the sender MUST NOT
114 * increment missing report count for t.
115 */
sctp_cacc_skip_3_1_f(struct sctp_transport * transport,int count_of_newacks)116 static inline int sctp_cacc_skip_3_1_f(struct sctp_transport *transport,
117 int count_of_newacks)
118 {
119 if (count_of_newacks < 2 &&
120 (transport && !transport->cacc.cacc_saw_newack))
121 return 1;
122 return 0;
123 }
124
125 /*
126 * SFR-CACC algorithm:
127 * 3.1) If CYCLING_CHANGEOVER is 0, the sender SHOULD
128 * execute steps C, D, F.
129 *
130 * C has been implemented in sctp_outq_sack
131 */
sctp_cacc_skip_3_1(struct sctp_transport * primary,struct sctp_transport * transport,int count_of_newacks)132 static inline int sctp_cacc_skip_3_1(struct sctp_transport *primary,
133 struct sctp_transport *transport,
134 int count_of_newacks)
135 {
136 if (!primary->cacc.cycling_changeover) {
137 if (sctp_cacc_skip_3_1_d(primary, transport, count_of_newacks))
138 return 1;
139 if (sctp_cacc_skip_3_1_f(transport, count_of_newacks))
140 return 1;
141 return 0;
142 }
143 return 0;
144 }
145
146 /*
147 * SFR-CACC algorithm:
148 * 3.2) Else if CYCLING_CHANGEOVER is 1, and t is less
149 * than next_tsn_at_change of the current primary, then
150 * the sender MUST NOT increment missing report count
151 * for t.
152 */
sctp_cacc_skip_3_2(struct sctp_transport * primary,__u32 tsn)153 static inline int sctp_cacc_skip_3_2(struct sctp_transport *primary, __u32 tsn)
154 {
155 if (primary->cacc.cycling_changeover &&
156 TSN_lt(tsn, primary->cacc.next_tsn_at_change))
157 return 1;
158 return 0;
159 }
160
161 /*
162 * SFR-CACC algorithm:
163 * 3) If the missing report count for TSN t is to be
164 * incremented according to [RFC2960] and
165 * [SCTP_STEWART-2002], and CHANGEOVER_ACTIVE is set,
166 * then the sender MUST further execute steps 3.1 and
167 * 3.2 to determine if the missing report count for
168 * TSN t SHOULD NOT be incremented.
169 *
170 * 3.3) If 3.1 and 3.2 do not dictate that the missing
171 * report count for t should not be incremented, then
172 * the sender SHOULD increment missing report count for
173 * t (according to [RFC2960] and [SCTP_STEWART_2002]).
174 */
sctp_cacc_skip(struct sctp_transport * primary,struct sctp_transport * transport,int count_of_newacks,__u32 tsn)175 static inline int sctp_cacc_skip(struct sctp_transport *primary,
176 struct sctp_transport *transport,
177 int count_of_newacks,
178 __u32 tsn)
179 {
180 if (primary->cacc.changeover_active &&
181 (sctp_cacc_skip_3_1(primary, transport, count_of_newacks) ||
182 sctp_cacc_skip_3_2(primary, tsn)))
183 return 1;
184 return 0;
185 }
186
187 /* Initialize an existing sctp_outq. This does the boring stuff.
188 * You still need to define handlers if you really want to DO
189 * something with this structure...
190 */
sctp_outq_init(struct sctp_association * asoc,struct sctp_outq * q)191 void sctp_outq_init(struct sctp_association *asoc, struct sctp_outq *q)
192 {
193 memset(q, 0, sizeof(struct sctp_outq));
194
195 q->asoc = asoc;
196 INIT_LIST_HEAD(&q->out_chunk_list);
197 INIT_LIST_HEAD(&q->control_chunk_list);
198 INIT_LIST_HEAD(&q->retransmit);
199 INIT_LIST_HEAD(&q->sacked);
200 INIT_LIST_HEAD(&q->abandoned);
201 sctp_sched_set_sched(asoc, sctp_sk(asoc->base.sk)->default_ss);
202 }
203
204 /* Free the outqueue structure and any related pending chunks.
205 */
__sctp_outq_teardown(struct sctp_outq * q)206 static void __sctp_outq_teardown(struct sctp_outq *q)
207 {
208 struct sctp_transport *transport;
209 struct list_head *lchunk, *temp;
210 struct sctp_chunk *chunk, *tmp;
211
212 /* Throw away unacknowledged chunks. */
213 list_for_each_entry(transport, &q->asoc->peer.transport_addr_list,
214 transports) {
215 while ((lchunk = sctp_list_dequeue(&transport->transmitted)) != NULL) {
216 chunk = list_entry(lchunk, struct sctp_chunk,
217 transmitted_list);
218 /* Mark as part of a failed message. */
219 sctp_chunk_fail(chunk, q->error);
220 sctp_chunk_free(chunk);
221 }
222 }
223
224 /* Throw away chunks that have been gap ACKed. */
225 list_for_each_safe(lchunk, temp, &q->sacked) {
226 list_del_init(lchunk);
227 chunk = list_entry(lchunk, struct sctp_chunk,
228 transmitted_list);
229 sctp_chunk_fail(chunk, q->error);
230 sctp_chunk_free(chunk);
231 }
232
233 /* Throw away any chunks in the retransmit queue. */
234 list_for_each_safe(lchunk, temp, &q->retransmit) {
235 list_del_init(lchunk);
236 chunk = list_entry(lchunk, struct sctp_chunk,
237 transmitted_list);
238 sctp_chunk_fail(chunk, q->error);
239 sctp_chunk_free(chunk);
240 }
241
242 /* Throw away any chunks that are in the abandoned queue. */
243 list_for_each_safe(lchunk, temp, &q->abandoned) {
244 list_del_init(lchunk);
245 chunk = list_entry(lchunk, struct sctp_chunk,
246 transmitted_list);
247 sctp_chunk_fail(chunk, q->error);
248 sctp_chunk_free(chunk);
249 }
250
251 /* Throw away any leftover data chunks. */
252 while ((chunk = sctp_outq_dequeue_data(q)) != NULL) {
253 sctp_sched_dequeue_done(q, chunk);
254
255 /* Mark as send failure. */
256 sctp_chunk_fail(chunk, q->error);
257 sctp_chunk_free(chunk);
258 }
259
260 /* Throw away any leftover control chunks. */
261 list_for_each_entry_safe(chunk, tmp, &q->control_chunk_list, list) {
262 list_del_init(&chunk->list);
263 sctp_chunk_free(chunk);
264 }
265 }
266
sctp_outq_teardown(struct sctp_outq * q)267 void sctp_outq_teardown(struct sctp_outq *q)
268 {
269 __sctp_outq_teardown(q);
270 sctp_outq_init(q->asoc, q);
271 }
272
273 /* Free the outqueue structure and any related pending chunks. */
sctp_outq_free(struct sctp_outq * q)274 void sctp_outq_free(struct sctp_outq *q)
275 {
276 /* Throw away leftover chunks. */
277 __sctp_outq_teardown(q);
278 }
279
280 /* Put a new chunk in an sctp_outq. */
sctp_outq_tail(struct sctp_outq * q,struct sctp_chunk * chunk,gfp_t gfp)281 void sctp_outq_tail(struct sctp_outq *q, struct sctp_chunk *chunk, gfp_t gfp)
282 {
283 struct net *net = q->asoc->base.net;
284
285 pr_debug("%s: outq:%p, chunk:%p[%s]\n", __func__, q, chunk,
286 chunk && chunk->chunk_hdr ?
287 sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)) :
288 "illegal chunk");
289
290 /* If it is data, queue it up, otherwise, send it
291 * immediately.
292 */
293 if (sctp_chunk_is_data(chunk)) {
294 pr_debug("%s: outqueueing: outq:%p, chunk:%p[%s])\n",
295 __func__, q, chunk, chunk && chunk->chunk_hdr ?
296 sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)) :
297 "illegal chunk");
298
299 sctp_outq_tail_data(q, chunk);
300 if (chunk->asoc->peer.prsctp_capable &&
301 SCTP_PR_PRIO_ENABLED(chunk->sinfo.sinfo_flags))
302 chunk->asoc->sent_cnt_removable++;
303 if (chunk->chunk_hdr->flags & SCTP_DATA_UNORDERED)
304 SCTP_INC_STATS(net, SCTP_MIB_OUTUNORDERCHUNKS);
305 else
306 SCTP_INC_STATS(net, SCTP_MIB_OUTORDERCHUNKS);
307 } else {
308 list_add_tail(&chunk->list, &q->control_chunk_list);
309 SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
310 }
311
312 if (!q->cork)
313 sctp_outq_flush(q, 0, gfp);
314 }
315
316 /* Insert a chunk into the sorted list based on the TSNs. The retransmit list
317 * and the abandoned list are in ascending order.
318 */
sctp_insert_list(struct list_head * head,struct list_head * new)319 static void sctp_insert_list(struct list_head *head, struct list_head *new)
320 {
321 struct list_head *pos;
322 struct sctp_chunk *nchunk, *lchunk;
323 __u32 ntsn, ltsn;
324 int done = 0;
325
326 nchunk = list_entry(new, struct sctp_chunk, transmitted_list);
327 ntsn = ntohl(nchunk->subh.data_hdr->tsn);
328
329 list_for_each(pos, head) {
330 lchunk = list_entry(pos, struct sctp_chunk, transmitted_list);
331 ltsn = ntohl(lchunk->subh.data_hdr->tsn);
332 if (TSN_lt(ntsn, ltsn)) {
333 list_add(new, pos->prev);
334 done = 1;
335 break;
336 }
337 }
338 if (!done)
339 list_add_tail(new, head);
340 }
341
sctp_prsctp_prune_sent(struct sctp_association * asoc,struct sctp_sndrcvinfo * sinfo,struct list_head * queue,int msg_len)342 static int sctp_prsctp_prune_sent(struct sctp_association *asoc,
343 struct sctp_sndrcvinfo *sinfo,
344 struct list_head *queue, int msg_len)
345 {
346 struct sctp_chunk *chk, *temp;
347
348 list_for_each_entry_safe(chk, temp, queue, transmitted_list) {
349 struct sctp_stream_out *streamout;
350
351 if (!chk->msg->abandoned &&
352 (!SCTP_PR_PRIO_ENABLED(chk->sinfo.sinfo_flags) ||
353 chk->sinfo.sinfo_timetolive <= sinfo->sinfo_timetolive))
354 continue;
355
356 chk->msg->abandoned = 1;
357 list_del_init(&chk->transmitted_list);
358 sctp_insert_list(&asoc->outqueue.abandoned,
359 &chk->transmitted_list);
360
361 streamout = SCTP_SO(&asoc->stream, chk->sinfo.sinfo_stream);
362 asoc->sent_cnt_removable--;
363 asoc->abandoned_sent[SCTP_PR_INDEX(PRIO)]++;
364 streamout->ext->abandoned_sent[SCTP_PR_INDEX(PRIO)]++;
365
366 if (queue != &asoc->outqueue.retransmit &&
367 !chk->tsn_gap_acked) {
368 if (chk->transport)
369 chk->transport->flight_size -=
370 sctp_data_size(chk);
371 asoc->outqueue.outstanding_bytes -= sctp_data_size(chk);
372 }
373
374 msg_len -= chk->skb->truesize + sizeof(struct sctp_chunk);
375 if (msg_len <= 0)
376 break;
377 }
378
379 return msg_len;
380 }
381
sctp_prsctp_prune_unsent(struct sctp_association * asoc,struct sctp_sndrcvinfo * sinfo,int msg_len)382 static int sctp_prsctp_prune_unsent(struct sctp_association *asoc,
383 struct sctp_sndrcvinfo *sinfo, int msg_len)
384 {
385 struct sctp_outq *q = &asoc->outqueue;
386 struct sctp_chunk *chk, *temp;
387 struct sctp_stream_out *sout;
388
389 q->sched->unsched_all(&asoc->stream);
390
391 list_for_each_entry_safe(chk, temp, &q->out_chunk_list, list) {
392 if (!chk->msg->abandoned &&
393 (!(chk->chunk_hdr->flags & SCTP_DATA_FIRST_FRAG) ||
394 !SCTP_PR_PRIO_ENABLED(chk->sinfo.sinfo_flags) ||
395 chk->sinfo.sinfo_timetolive <= sinfo->sinfo_timetolive))
396 continue;
397
398 chk->msg->abandoned = 1;
399 sctp_sched_dequeue_common(q, chk);
400 asoc->sent_cnt_removable--;
401 asoc->abandoned_unsent[SCTP_PR_INDEX(PRIO)]++;
402
403 sout = SCTP_SO(&asoc->stream, chk->sinfo.sinfo_stream);
404 sout->ext->abandoned_unsent[SCTP_PR_INDEX(PRIO)]++;
405
406 /* clear out_curr if all frag chunks are pruned */
407 if (asoc->stream.out_curr == sout &&
408 list_is_last(&chk->frag_list, &chk->msg->chunks))
409 asoc->stream.out_curr = NULL;
410
411 msg_len -= chk->skb->truesize + sizeof(struct sctp_chunk);
412 sctp_chunk_free(chk);
413 if (msg_len <= 0)
414 break;
415 }
416
417 q->sched->sched_all(&asoc->stream);
418
419 return msg_len;
420 }
421
422 /* Abandon the chunks according their priorities */
sctp_prsctp_prune(struct sctp_association * asoc,struct sctp_sndrcvinfo * sinfo,int msg_len)423 void sctp_prsctp_prune(struct sctp_association *asoc,
424 struct sctp_sndrcvinfo *sinfo, int msg_len)
425 {
426 struct sctp_transport *transport;
427
428 if (!asoc->peer.prsctp_capable || !asoc->sent_cnt_removable)
429 return;
430
431 msg_len = sctp_prsctp_prune_sent(asoc, sinfo,
432 &asoc->outqueue.retransmit,
433 msg_len);
434 if (msg_len <= 0)
435 return;
436
437 list_for_each_entry(transport, &asoc->peer.transport_addr_list,
438 transports) {
439 msg_len = sctp_prsctp_prune_sent(asoc, sinfo,
440 &transport->transmitted,
441 msg_len);
442 if (msg_len <= 0)
443 return;
444 }
445
446 sctp_prsctp_prune_unsent(asoc, sinfo, msg_len);
447 }
448
449 /* Mark all the eligible packets on a transport for retransmission. */
sctp_retransmit_mark(struct sctp_outq * q,struct sctp_transport * transport,__u8 reason)450 void sctp_retransmit_mark(struct sctp_outq *q,
451 struct sctp_transport *transport,
452 __u8 reason)
453 {
454 struct list_head *lchunk, *ltemp;
455 struct sctp_chunk *chunk;
456
457 /* Walk through the specified transmitted queue. */
458 list_for_each_safe(lchunk, ltemp, &transport->transmitted) {
459 chunk = list_entry(lchunk, struct sctp_chunk,
460 transmitted_list);
461
462 /* If the chunk is abandoned, move it to abandoned list. */
463 if (sctp_chunk_abandoned(chunk)) {
464 list_del_init(lchunk);
465 sctp_insert_list(&q->abandoned, lchunk);
466
467 /* If this chunk has not been previousely acked,
468 * stop considering it 'outstanding'. Our peer
469 * will most likely never see it since it will
470 * not be retransmitted
471 */
472 if (!chunk->tsn_gap_acked) {
473 if (chunk->transport)
474 chunk->transport->flight_size -=
475 sctp_data_size(chunk);
476 q->outstanding_bytes -= sctp_data_size(chunk);
477 q->asoc->peer.rwnd += sctp_data_size(chunk);
478 }
479 continue;
480 }
481
482 /* If we are doing retransmission due to a timeout or pmtu
483 * discovery, only the chunks that are not yet acked should
484 * be added to the retransmit queue.
485 */
486 if ((reason == SCTP_RTXR_FAST_RTX &&
487 (chunk->fast_retransmit == SCTP_NEED_FRTX)) ||
488 (reason != SCTP_RTXR_FAST_RTX && !chunk->tsn_gap_acked)) {
489 /* RFC 2960 6.2.1 Processing a Received SACK
490 *
491 * C) Any time a DATA chunk is marked for
492 * retransmission (via either T3-rtx timer expiration
493 * (Section 6.3.3) or via fast retransmit
494 * (Section 7.2.4)), add the data size of those
495 * chunks to the rwnd.
496 */
497 q->asoc->peer.rwnd += sctp_data_size(chunk);
498 q->outstanding_bytes -= sctp_data_size(chunk);
499 if (chunk->transport)
500 transport->flight_size -= sctp_data_size(chunk);
501
502 /* sctpimpguide-05 Section 2.8.2
503 * M5) If a T3-rtx timer expires, the
504 * 'TSN.Missing.Report' of all affected TSNs is set
505 * to 0.
506 */
507 chunk->tsn_missing_report = 0;
508
509 /* If a chunk that is being used for RTT measurement
510 * has to be retransmitted, we cannot use this chunk
511 * anymore for RTT measurements. Reset rto_pending so
512 * that a new RTT measurement is started when a new
513 * data chunk is sent.
514 */
515 if (chunk->rtt_in_progress) {
516 chunk->rtt_in_progress = 0;
517 transport->rto_pending = 0;
518 }
519
520 /* Move the chunk to the retransmit queue. The chunks
521 * on the retransmit queue are always kept in order.
522 */
523 list_del_init(lchunk);
524 sctp_insert_list(&q->retransmit, lchunk);
525 }
526 }
527
528 pr_debug("%s: transport:%p, reason:%d, cwnd:%d, ssthresh:%d, "
529 "flight_size:%d, pba:%d\n", __func__, transport, reason,
530 transport->cwnd, transport->ssthresh, transport->flight_size,
531 transport->partial_bytes_acked);
532 }
533
534 /* Mark all the eligible packets on a transport for retransmission and force
535 * one packet out.
536 */
sctp_retransmit(struct sctp_outq * q,struct sctp_transport * transport,enum sctp_retransmit_reason reason)537 void sctp_retransmit(struct sctp_outq *q, struct sctp_transport *transport,
538 enum sctp_retransmit_reason reason)
539 {
540 struct net *net = q->asoc->base.net;
541
542 switch (reason) {
543 case SCTP_RTXR_T3_RTX:
544 SCTP_INC_STATS(net, SCTP_MIB_T3_RETRANSMITS);
545 sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_T3_RTX);
546 /* Update the retran path if the T3-rtx timer has expired for
547 * the current retran path.
548 */
549 if (transport == transport->asoc->peer.retran_path)
550 sctp_assoc_update_retran_path(transport->asoc);
551 transport->asoc->rtx_data_chunks +=
552 transport->asoc->unack_data;
553 break;
554 case SCTP_RTXR_FAST_RTX:
555 SCTP_INC_STATS(net, SCTP_MIB_FAST_RETRANSMITS);
556 sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_FAST_RTX);
557 q->fast_rtx = 1;
558 break;
559 case SCTP_RTXR_PMTUD:
560 SCTP_INC_STATS(net, SCTP_MIB_PMTUD_RETRANSMITS);
561 break;
562 case SCTP_RTXR_T1_RTX:
563 SCTP_INC_STATS(net, SCTP_MIB_T1_RETRANSMITS);
564 transport->asoc->init_retries++;
565 break;
566 default:
567 BUG();
568 }
569
570 sctp_retransmit_mark(q, transport, reason);
571
572 /* PR-SCTP A5) Any time the T3-rtx timer expires, on any destination,
573 * the sender SHOULD try to advance the "Advanced.Peer.Ack.Point" by
574 * following the procedures outlined in C1 - C5.
575 */
576 if (reason == SCTP_RTXR_T3_RTX)
577 q->asoc->stream.si->generate_ftsn(q, q->asoc->ctsn_ack_point);
578
579 /* Flush the queues only on timeout, since fast_rtx is only
580 * triggered during sack processing and the queue
581 * will be flushed at the end.
582 */
583 if (reason != SCTP_RTXR_FAST_RTX)
584 sctp_outq_flush(q, /* rtx_timeout */ 1, GFP_ATOMIC);
585 }
586
587 /*
588 * Transmit DATA chunks on the retransmit queue. Upon return from
589 * __sctp_outq_flush_rtx() the packet 'pkt' may contain chunks which
590 * need to be transmitted by the caller.
591 * We assume that pkt->transport has already been set.
592 *
593 * The return value is a normal kernel error return value.
594 */
__sctp_outq_flush_rtx(struct sctp_outq * q,struct sctp_packet * pkt,int rtx_timeout,int * start_timer,gfp_t gfp)595 static int __sctp_outq_flush_rtx(struct sctp_outq *q, struct sctp_packet *pkt,
596 int rtx_timeout, int *start_timer, gfp_t gfp)
597 {
598 struct sctp_transport *transport = pkt->transport;
599 struct sctp_chunk *chunk, *chunk1;
600 struct list_head *lqueue;
601 enum sctp_xmit status;
602 int error = 0;
603 int timer = 0;
604 int done = 0;
605 int fast_rtx;
606
607 lqueue = &q->retransmit;
608 fast_rtx = q->fast_rtx;
609
610 /* This loop handles time-out retransmissions, fast retransmissions,
611 * and retransmissions due to opening of whindow.
612 *
613 * RFC 2960 6.3.3 Handle T3-rtx Expiration
614 *
615 * E3) Determine how many of the earliest (i.e., lowest TSN)
616 * outstanding DATA chunks for the address for which the
617 * T3-rtx has expired will fit into a single packet, subject
618 * to the MTU constraint for the path corresponding to the
619 * destination transport address to which the retransmission
620 * is being sent (this may be different from the address for
621 * which the timer expires [see Section 6.4]). Call this value
622 * K. Bundle and retransmit those K DATA chunks in a single
623 * packet to the destination endpoint.
624 *
625 * [Just to be painfully clear, if we are retransmitting
626 * because a timeout just happened, we should send only ONE
627 * packet of retransmitted data.]
628 *
629 * For fast retransmissions we also send only ONE packet. However,
630 * if we are just flushing the queue due to open window, we'll
631 * try to send as much as possible.
632 */
633 list_for_each_entry_safe(chunk, chunk1, lqueue, transmitted_list) {
634 /* If the chunk is abandoned, move it to abandoned list. */
635 if (sctp_chunk_abandoned(chunk)) {
636 list_del_init(&chunk->transmitted_list);
637 sctp_insert_list(&q->abandoned,
638 &chunk->transmitted_list);
639 continue;
640 }
641
642 /* Make sure that Gap Acked TSNs are not retransmitted. A
643 * simple approach is just to move such TSNs out of the
644 * way and into a 'transmitted' queue and skip to the
645 * next chunk.
646 */
647 if (chunk->tsn_gap_acked) {
648 list_move_tail(&chunk->transmitted_list,
649 &transport->transmitted);
650 continue;
651 }
652
653 /* If we are doing fast retransmit, ignore non-fast_rtransmit
654 * chunks
655 */
656 if (fast_rtx && !chunk->fast_retransmit)
657 continue;
658
659 redo:
660 /* Attempt to append this chunk to the packet. */
661 status = sctp_packet_append_chunk(pkt, chunk);
662
663 switch (status) {
664 case SCTP_XMIT_PMTU_FULL:
665 if (!pkt->has_data && !pkt->has_cookie_echo) {
666 /* If this packet did not contain DATA then
667 * retransmission did not happen, so do it
668 * again. We'll ignore the error here since
669 * control chunks are already freed so there
670 * is nothing we can do.
671 */
672 sctp_packet_transmit(pkt, gfp);
673 goto redo;
674 }
675
676 /* Send this packet. */
677 error = sctp_packet_transmit(pkt, gfp);
678
679 /* If we are retransmitting, we should only
680 * send a single packet.
681 * Otherwise, try appending this chunk again.
682 */
683 if (rtx_timeout || fast_rtx)
684 done = 1;
685 else
686 goto redo;
687
688 /* Bundle next chunk in the next round. */
689 break;
690
691 case SCTP_XMIT_RWND_FULL:
692 /* Send this packet. */
693 error = sctp_packet_transmit(pkt, gfp);
694
695 /* Stop sending DATA as there is no more room
696 * at the receiver.
697 */
698 done = 1;
699 break;
700
701 case SCTP_XMIT_DELAY:
702 /* Send this packet. */
703 error = sctp_packet_transmit(pkt, gfp);
704
705 /* Stop sending DATA because of nagle delay. */
706 done = 1;
707 break;
708
709 default:
710 /* The append was successful, so add this chunk to
711 * the transmitted list.
712 */
713 list_move_tail(&chunk->transmitted_list,
714 &transport->transmitted);
715
716 /* Mark the chunk as ineligible for fast retransmit
717 * after it is retransmitted.
718 */
719 if (chunk->fast_retransmit == SCTP_NEED_FRTX)
720 chunk->fast_retransmit = SCTP_DONT_FRTX;
721
722 q->asoc->stats.rtxchunks++;
723 break;
724 }
725
726 /* Set the timer if there were no errors */
727 if (!error && !timer)
728 timer = 1;
729
730 if (done)
731 break;
732 }
733
734 /* If we are here due to a retransmit timeout or a fast
735 * retransmit and if there are any chunks left in the retransmit
736 * queue that could not fit in the PMTU sized packet, they need
737 * to be marked as ineligible for a subsequent fast retransmit.
738 */
739 if (rtx_timeout || fast_rtx) {
740 list_for_each_entry(chunk1, lqueue, transmitted_list) {
741 if (chunk1->fast_retransmit == SCTP_NEED_FRTX)
742 chunk1->fast_retransmit = SCTP_DONT_FRTX;
743 }
744 }
745
746 *start_timer = timer;
747
748 /* Clear fast retransmit hint */
749 if (fast_rtx)
750 q->fast_rtx = 0;
751
752 return error;
753 }
754
755 /* Cork the outqueue so queued chunks are really queued. */
sctp_outq_uncork(struct sctp_outq * q,gfp_t gfp)756 void sctp_outq_uncork(struct sctp_outq *q, gfp_t gfp)
757 {
758 if (q->cork)
759 q->cork = 0;
760
761 sctp_outq_flush(q, 0, gfp);
762 }
763
sctp_packet_singleton(struct sctp_transport * transport,struct sctp_chunk * chunk,gfp_t gfp)764 static int sctp_packet_singleton(struct sctp_transport *transport,
765 struct sctp_chunk *chunk, gfp_t gfp)
766 {
767 const struct sctp_association *asoc = transport->asoc;
768 const __u16 sport = asoc->base.bind_addr.port;
769 const __u16 dport = asoc->peer.port;
770 const __u32 vtag = asoc->peer.i.init_tag;
771 struct sctp_packet singleton;
772
773 sctp_packet_init(&singleton, transport, sport, dport);
774 sctp_packet_config(&singleton, vtag, 0);
775 sctp_packet_append_chunk(&singleton, chunk);
776 return sctp_packet_transmit(&singleton, gfp);
777 }
778
779 /* Struct to hold the context during sctp outq flush */
780 struct sctp_flush_ctx {
781 struct sctp_outq *q;
782 /* Current transport being used. It's NOT the same as curr active one */
783 struct sctp_transport *transport;
784 /* These transports have chunks to send. */
785 struct list_head transport_list;
786 struct sctp_association *asoc;
787 /* Packet on the current transport above */
788 struct sctp_packet *packet;
789 gfp_t gfp;
790 };
791
792 /* transport: current transport */
sctp_outq_select_transport(struct sctp_flush_ctx * ctx,struct sctp_chunk * chunk)793 static void sctp_outq_select_transport(struct sctp_flush_ctx *ctx,
794 struct sctp_chunk *chunk)
795 {
796 struct sctp_transport *new_transport = chunk->transport;
797
798 if (!new_transport) {
799 if (!sctp_chunk_is_data(chunk)) {
800 /* If we have a prior transport pointer, see if
801 * the destination address of the chunk
802 * matches the destination address of the
803 * current transport. If not a match, then
804 * try to look up the transport with a given
805 * destination address. We do this because
806 * after processing ASCONFs, we may have new
807 * transports created.
808 */
809 if (ctx->transport && sctp_cmp_addr_exact(&chunk->dest,
810 &ctx->transport->ipaddr))
811 new_transport = ctx->transport;
812 else
813 new_transport = sctp_assoc_lookup_paddr(ctx->asoc,
814 &chunk->dest);
815 }
816
817 /* if we still don't have a new transport, then
818 * use the current active path.
819 */
820 if (!new_transport)
821 new_transport = ctx->asoc->peer.active_path;
822 } else {
823 __u8 type;
824
825 switch (new_transport->state) {
826 case SCTP_INACTIVE:
827 case SCTP_UNCONFIRMED:
828 case SCTP_PF:
829 /* If the chunk is Heartbeat or Heartbeat Ack,
830 * send it to chunk->transport, even if it's
831 * inactive.
832 *
833 * 3.3.6 Heartbeat Acknowledgement:
834 * ...
835 * A HEARTBEAT ACK is always sent to the source IP
836 * address of the IP datagram containing the
837 * HEARTBEAT chunk to which this ack is responding.
838 * ...
839 *
840 * ASCONF_ACKs also must be sent to the source.
841 */
842 type = chunk->chunk_hdr->type;
843 if (type != SCTP_CID_HEARTBEAT &&
844 type != SCTP_CID_HEARTBEAT_ACK &&
845 type != SCTP_CID_ASCONF_ACK)
846 new_transport = ctx->asoc->peer.active_path;
847 break;
848 default:
849 break;
850 }
851 }
852
853 /* Are we switching transports? Take care of transport locks. */
854 if (new_transport != ctx->transport) {
855 ctx->transport = new_transport;
856 ctx->packet = &ctx->transport->packet;
857
858 if (list_empty(&ctx->transport->send_ready))
859 list_add_tail(&ctx->transport->send_ready,
860 &ctx->transport_list);
861
862 sctp_packet_config(ctx->packet,
863 ctx->asoc->peer.i.init_tag,
864 ctx->asoc->peer.ecn_capable);
865 /* We've switched transports, so apply the
866 * Burst limit to the new transport.
867 */
868 sctp_transport_burst_limited(ctx->transport);
869 }
870 }
871
sctp_outq_flush_ctrl(struct sctp_flush_ctx * ctx)872 static void sctp_outq_flush_ctrl(struct sctp_flush_ctx *ctx)
873 {
874 struct sctp_chunk *chunk, *tmp;
875 enum sctp_xmit status;
876 int one_packet, error;
877
878 list_for_each_entry_safe(chunk, tmp, &ctx->q->control_chunk_list, list) {
879 one_packet = 0;
880
881 /* RFC 5061, 5.3
882 * F1) This means that until such time as the ASCONF
883 * containing the add is acknowledged, the sender MUST
884 * NOT use the new IP address as a source for ANY SCTP
885 * packet except on carrying an ASCONF Chunk.
886 */
887 if (ctx->asoc->src_out_of_asoc_ok &&
888 chunk->chunk_hdr->type != SCTP_CID_ASCONF)
889 continue;
890
891 list_del_init(&chunk->list);
892
893 /* Pick the right transport to use. Should always be true for
894 * the first chunk as we don't have a transport by then.
895 */
896 sctp_outq_select_transport(ctx, chunk);
897
898 switch (chunk->chunk_hdr->type) {
899 /* 6.10 Bundling
900 * ...
901 * An endpoint MUST NOT bundle INIT, INIT ACK or SHUTDOWN
902 * COMPLETE with any other chunks. [Send them immediately.]
903 */
904 case SCTP_CID_INIT:
905 case SCTP_CID_INIT_ACK:
906 case SCTP_CID_SHUTDOWN_COMPLETE:
907 error = sctp_packet_singleton(ctx->transport, chunk,
908 ctx->gfp);
909 if (error < 0) {
910 ctx->asoc->base.sk->sk_err = -error;
911 return;
912 }
913 break;
914
915 case SCTP_CID_ABORT:
916 if (sctp_test_T_bit(chunk))
917 ctx->packet->vtag = ctx->asoc->c.my_vtag;
918 fallthrough;
919
920 /* The following chunks are "response" chunks, i.e.
921 * they are generated in response to something we
922 * received. If we are sending these, then we can
923 * send only 1 packet containing these chunks.
924 */
925 case SCTP_CID_HEARTBEAT_ACK:
926 case SCTP_CID_SHUTDOWN_ACK:
927 case SCTP_CID_COOKIE_ACK:
928 case SCTP_CID_COOKIE_ECHO:
929 case SCTP_CID_ERROR:
930 case SCTP_CID_ECN_CWR:
931 case SCTP_CID_ASCONF_ACK:
932 one_packet = 1;
933 fallthrough;
934
935 case SCTP_CID_SACK:
936 case SCTP_CID_HEARTBEAT:
937 case SCTP_CID_SHUTDOWN:
938 case SCTP_CID_ECN_ECNE:
939 case SCTP_CID_ASCONF:
940 case SCTP_CID_FWD_TSN:
941 case SCTP_CID_I_FWD_TSN:
942 case SCTP_CID_RECONF:
943 status = sctp_packet_transmit_chunk(ctx->packet, chunk,
944 one_packet, ctx->gfp);
945 if (status != SCTP_XMIT_OK) {
946 /* put the chunk back */
947 list_add(&chunk->list, &ctx->q->control_chunk_list);
948 break;
949 }
950
951 ctx->asoc->stats.octrlchunks++;
952 /* PR-SCTP C5) If a FORWARD TSN is sent, the
953 * sender MUST assure that at least one T3-rtx
954 * timer is running.
955 */
956 if (chunk->chunk_hdr->type == SCTP_CID_FWD_TSN ||
957 chunk->chunk_hdr->type == SCTP_CID_I_FWD_TSN) {
958 sctp_transport_reset_t3_rtx(ctx->transport);
959 ctx->transport->last_time_sent = jiffies;
960 }
961
962 if (chunk == ctx->asoc->strreset_chunk)
963 sctp_transport_reset_reconf_timer(ctx->transport);
964
965 break;
966
967 default:
968 /* We built a chunk with an illegal type! */
969 BUG();
970 }
971 }
972 }
973
974 /* Returns false if new data shouldn't be sent */
sctp_outq_flush_rtx(struct sctp_flush_ctx * ctx,int rtx_timeout)975 static bool sctp_outq_flush_rtx(struct sctp_flush_ctx *ctx,
976 int rtx_timeout)
977 {
978 int error, start_timer = 0;
979
980 if (ctx->asoc->peer.retran_path->state == SCTP_UNCONFIRMED)
981 return false;
982
983 if (ctx->transport != ctx->asoc->peer.retran_path) {
984 /* Switch transports & prepare the packet. */
985 ctx->transport = ctx->asoc->peer.retran_path;
986 ctx->packet = &ctx->transport->packet;
987
988 if (list_empty(&ctx->transport->send_ready))
989 list_add_tail(&ctx->transport->send_ready,
990 &ctx->transport_list);
991
992 sctp_packet_config(ctx->packet, ctx->asoc->peer.i.init_tag,
993 ctx->asoc->peer.ecn_capable);
994 }
995
996 error = __sctp_outq_flush_rtx(ctx->q, ctx->packet, rtx_timeout,
997 &start_timer, ctx->gfp);
998 if (error < 0)
999 ctx->asoc->base.sk->sk_err = -error;
1000
1001 if (start_timer) {
1002 sctp_transport_reset_t3_rtx(ctx->transport);
1003 ctx->transport->last_time_sent = jiffies;
1004 }
1005
1006 /* This can happen on COOKIE-ECHO resend. Only
1007 * one chunk can get bundled with a COOKIE-ECHO.
1008 */
1009 if (ctx->packet->has_cookie_echo)
1010 return false;
1011
1012 /* Don't send new data if there is still data
1013 * waiting to retransmit.
1014 */
1015 if (!list_empty(&ctx->q->retransmit))
1016 return false;
1017
1018 return true;
1019 }
1020
sctp_outq_flush_data(struct sctp_flush_ctx * ctx,int rtx_timeout)1021 static void sctp_outq_flush_data(struct sctp_flush_ctx *ctx,
1022 int rtx_timeout)
1023 {
1024 struct sctp_chunk *chunk;
1025 enum sctp_xmit status;
1026
1027 /* Is it OK to send data chunks? */
1028 switch (ctx->asoc->state) {
1029 case SCTP_STATE_COOKIE_ECHOED:
1030 /* Only allow bundling when this packet has a COOKIE-ECHO
1031 * chunk.
1032 */
1033 if (!ctx->packet || !ctx->packet->has_cookie_echo)
1034 return;
1035
1036 fallthrough;
1037 case SCTP_STATE_ESTABLISHED:
1038 case SCTP_STATE_SHUTDOWN_PENDING:
1039 case SCTP_STATE_SHUTDOWN_RECEIVED:
1040 break;
1041
1042 default:
1043 /* Do nothing. */
1044 return;
1045 }
1046
1047 /* RFC 2960 6.1 Transmission of DATA Chunks
1048 *
1049 * C) When the time comes for the sender to transmit,
1050 * before sending new DATA chunks, the sender MUST
1051 * first transmit any outstanding DATA chunks which
1052 * are marked for retransmission (limited by the
1053 * current cwnd).
1054 */
1055 if (!list_empty(&ctx->q->retransmit) &&
1056 !sctp_outq_flush_rtx(ctx, rtx_timeout))
1057 return;
1058
1059 /* Apply Max.Burst limitation to the current transport in
1060 * case it will be used for new data. We are going to
1061 * rest it before we return, but we want to apply the limit
1062 * to the currently queued data.
1063 */
1064 if (ctx->transport)
1065 sctp_transport_burst_limited(ctx->transport);
1066
1067 /* Finally, transmit new packets. */
1068 while ((chunk = sctp_outq_dequeue_data(ctx->q)) != NULL) {
1069 __u32 sid = ntohs(chunk->subh.data_hdr->stream);
1070 __u8 stream_state = SCTP_SO(&ctx->asoc->stream, sid)->state;
1071
1072 /* Has this chunk expired? */
1073 if (sctp_chunk_abandoned(chunk)) {
1074 sctp_sched_dequeue_done(ctx->q, chunk);
1075 sctp_chunk_fail(chunk, 0);
1076 sctp_chunk_free(chunk);
1077 continue;
1078 }
1079
1080 if (stream_state == SCTP_STREAM_CLOSED) {
1081 sctp_outq_head_data(ctx->q, chunk);
1082 break;
1083 }
1084
1085 sctp_outq_select_transport(ctx, chunk);
1086
1087 pr_debug("%s: outq:%p, chunk:%p[%s], tx-tsn:0x%x skb->head:%p skb->users:%d\n",
1088 __func__, ctx->q, chunk, chunk && chunk->chunk_hdr ?
1089 sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)) :
1090 "illegal chunk", ntohl(chunk->subh.data_hdr->tsn),
1091 chunk->skb ? chunk->skb->head : NULL, chunk->skb ?
1092 refcount_read(&chunk->skb->users) : -1);
1093
1094 /* Add the chunk to the packet. */
1095 status = sctp_packet_transmit_chunk(ctx->packet, chunk, 0,
1096 ctx->gfp);
1097 if (status != SCTP_XMIT_OK) {
1098 /* We could not append this chunk, so put
1099 * the chunk back on the output queue.
1100 */
1101 pr_debug("%s: could not transmit tsn:0x%x, status:%d\n",
1102 __func__, ntohl(chunk->subh.data_hdr->tsn),
1103 status);
1104
1105 sctp_outq_head_data(ctx->q, chunk);
1106 break;
1107 }
1108
1109 /* The sender is in the SHUTDOWN-PENDING state,
1110 * The sender MAY set the I-bit in the DATA
1111 * chunk header.
1112 */
1113 if (ctx->asoc->state == SCTP_STATE_SHUTDOWN_PENDING)
1114 chunk->chunk_hdr->flags |= SCTP_DATA_SACK_IMM;
1115 if (chunk->chunk_hdr->flags & SCTP_DATA_UNORDERED)
1116 ctx->asoc->stats.ouodchunks++;
1117 else
1118 ctx->asoc->stats.oodchunks++;
1119
1120 /* Only now it's safe to consider this
1121 * chunk as sent, sched-wise.
1122 */
1123 sctp_sched_dequeue_done(ctx->q, chunk);
1124
1125 list_add_tail(&chunk->transmitted_list,
1126 &ctx->transport->transmitted);
1127
1128 sctp_transport_reset_t3_rtx(ctx->transport);
1129 ctx->transport->last_time_sent = jiffies;
1130
1131 /* Only let one DATA chunk get bundled with a
1132 * COOKIE-ECHO chunk.
1133 */
1134 if (ctx->packet->has_cookie_echo)
1135 break;
1136 }
1137 }
1138
sctp_outq_flush_transports(struct sctp_flush_ctx * ctx)1139 static void sctp_outq_flush_transports(struct sctp_flush_ctx *ctx)
1140 {
1141 struct list_head *ltransport;
1142 struct sctp_packet *packet;
1143 struct sctp_transport *t;
1144 int error = 0;
1145
1146 while ((ltransport = sctp_list_dequeue(&ctx->transport_list)) != NULL) {
1147 t = list_entry(ltransport, struct sctp_transport, send_ready);
1148 packet = &t->packet;
1149 if (!sctp_packet_empty(packet)) {
1150 error = sctp_packet_transmit(packet, ctx->gfp);
1151 if (error < 0)
1152 ctx->q->asoc->base.sk->sk_err = -error;
1153 }
1154
1155 /* Clear the burst limited state, if any */
1156 sctp_transport_burst_reset(t);
1157 }
1158 }
1159
1160 /* Try to flush an outqueue.
1161 *
1162 * Description: Send everything in q which we legally can, subject to
1163 * congestion limitations.
1164 * * Note: This function can be called from multiple contexts so appropriate
1165 * locking concerns must be made. Today we use the sock lock to protect
1166 * this function.
1167 */
1168
sctp_outq_flush(struct sctp_outq * q,int rtx_timeout,gfp_t gfp)1169 static void sctp_outq_flush(struct sctp_outq *q, int rtx_timeout, gfp_t gfp)
1170 {
1171 struct sctp_flush_ctx ctx = {
1172 .q = q,
1173 .transport = NULL,
1174 .transport_list = LIST_HEAD_INIT(ctx.transport_list),
1175 .asoc = q->asoc,
1176 .packet = NULL,
1177 .gfp = gfp,
1178 };
1179
1180 /* 6.10 Bundling
1181 * ...
1182 * When bundling control chunks with DATA chunks, an
1183 * endpoint MUST place control chunks first in the outbound
1184 * SCTP packet. The transmitter MUST transmit DATA chunks
1185 * within a SCTP packet in increasing order of TSN.
1186 * ...
1187 */
1188
1189 sctp_outq_flush_ctrl(&ctx);
1190
1191 if (q->asoc->src_out_of_asoc_ok)
1192 goto sctp_flush_out;
1193
1194 sctp_outq_flush_data(&ctx, rtx_timeout);
1195
1196 sctp_flush_out:
1197
1198 sctp_outq_flush_transports(&ctx);
1199 }
1200
1201 /* Update unack_data based on the incoming SACK chunk */
sctp_sack_update_unack_data(struct sctp_association * assoc,struct sctp_sackhdr * sack)1202 static void sctp_sack_update_unack_data(struct sctp_association *assoc,
1203 struct sctp_sackhdr *sack)
1204 {
1205 union sctp_sack_variable *frags;
1206 __u16 unack_data;
1207 int i;
1208
1209 unack_data = assoc->next_tsn - assoc->ctsn_ack_point - 1;
1210
1211 frags = sack->variable;
1212 for (i = 0; i < ntohs(sack->num_gap_ack_blocks); i++) {
1213 unack_data -= ((ntohs(frags[i].gab.end) -
1214 ntohs(frags[i].gab.start) + 1));
1215 }
1216
1217 assoc->unack_data = unack_data;
1218 }
1219
1220 /* This is where we REALLY process a SACK.
1221 *
1222 * Process the SACK against the outqueue. Mostly, this just frees
1223 * things off the transmitted queue.
1224 */
sctp_outq_sack(struct sctp_outq * q,struct sctp_chunk * chunk)1225 int sctp_outq_sack(struct sctp_outq *q, struct sctp_chunk *chunk)
1226 {
1227 struct sctp_association *asoc = q->asoc;
1228 struct sctp_sackhdr *sack = chunk->subh.sack_hdr;
1229 struct sctp_transport *transport;
1230 struct sctp_chunk *tchunk = NULL;
1231 struct list_head *lchunk, *transport_list, *temp;
1232 union sctp_sack_variable *frags = sack->variable;
1233 __u32 sack_ctsn, ctsn, tsn;
1234 __u32 highest_tsn, highest_new_tsn;
1235 __u32 sack_a_rwnd;
1236 unsigned int outstanding;
1237 struct sctp_transport *primary = asoc->peer.primary_path;
1238 int count_of_newacks = 0;
1239 int gap_ack_blocks;
1240 u8 accum_moved = 0;
1241
1242 /* Grab the association's destination address list. */
1243 transport_list = &asoc->peer.transport_addr_list;
1244
1245 /* SCTP path tracepoint for congestion control debugging. */
1246 if (trace_sctp_probe_path_enabled()) {
1247 list_for_each_entry(transport, transport_list, transports)
1248 trace_sctp_probe_path(transport, asoc);
1249 }
1250
1251 sack_ctsn = ntohl(sack->cum_tsn_ack);
1252 gap_ack_blocks = ntohs(sack->num_gap_ack_blocks);
1253 asoc->stats.gapcnt += gap_ack_blocks;
1254 /*
1255 * SFR-CACC algorithm:
1256 * On receipt of a SACK the sender SHOULD execute the
1257 * following statements.
1258 *
1259 * 1) If the cumulative ack in the SACK passes next tsn_at_change
1260 * on the current primary, the CHANGEOVER_ACTIVE flag SHOULD be
1261 * cleared. The CYCLING_CHANGEOVER flag SHOULD also be cleared for
1262 * all destinations.
1263 * 2) If the SACK contains gap acks and the flag CHANGEOVER_ACTIVE
1264 * is set the receiver of the SACK MUST take the following actions:
1265 *
1266 * A) Initialize the cacc_saw_newack to 0 for all destination
1267 * addresses.
1268 *
1269 * Only bother if changeover_active is set. Otherwise, this is
1270 * totally suboptimal to do on every SACK.
1271 */
1272 if (primary->cacc.changeover_active) {
1273 u8 clear_cycling = 0;
1274
1275 if (TSN_lte(primary->cacc.next_tsn_at_change, sack_ctsn)) {
1276 primary->cacc.changeover_active = 0;
1277 clear_cycling = 1;
1278 }
1279
1280 if (clear_cycling || gap_ack_blocks) {
1281 list_for_each_entry(transport, transport_list,
1282 transports) {
1283 if (clear_cycling)
1284 transport->cacc.cycling_changeover = 0;
1285 if (gap_ack_blocks)
1286 transport->cacc.cacc_saw_newack = 0;
1287 }
1288 }
1289 }
1290
1291 /* Get the highest TSN in the sack. */
1292 highest_tsn = sack_ctsn;
1293 if (gap_ack_blocks)
1294 highest_tsn += ntohs(frags[gap_ack_blocks - 1].gab.end);
1295
1296 if (TSN_lt(asoc->highest_sacked, highest_tsn))
1297 asoc->highest_sacked = highest_tsn;
1298
1299 highest_new_tsn = sack_ctsn;
1300
1301 /* Run through the retransmit queue. Credit bytes received
1302 * and free those chunks that we can.
1303 */
1304 sctp_check_transmitted(q, &q->retransmit, NULL, NULL, sack, &highest_new_tsn);
1305
1306 /* Run through the transmitted queue.
1307 * Credit bytes received and free those chunks which we can.
1308 *
1309 * This is a MASSIVE candidate for optimization.
1310 */
1311 list_for_each_entry(transport, transport_list, transports) {
1312 sctp_check_transmitted(q, &transport->transmitted,
1313 transport, &chunk->source, sack,
1314 &highest_new_tsn);
1315 /*
1316 * SFR-CACC algorithm:
1317 * C) Let count_of_newacks be the number of
1318 * destinations for which cacc_saw_newack is set.
1319 */
1320 if (transport->cacc.cacc_saw_newack)
1321 count_of_newacks++;
1322 }
1323
1324 /* Move the Cumulative TSN Ack Point if appropriate. */
1325 if (TSN_lt(asoc->ctsn_ack_point, sack_ctsn)) {
1326 asoc->ctsn_ack_point = sack_ctsn;
1327 accum_moved = 1;
1328 }
1329
1330 if (gap_ack_blocks) {
1331
1332 if (asoc->fast_recovery && accum_moved)
1333 highest_new_tsn = highest_tsn;
1334
1335 list_for_each_entry(transport, transport_list, transports)
1336 sctp_mark_missing(q, &transport->transmitted, transport,
1337 highest_new_tsn, count_of_newacks);
1338 }
1339
1340 /* Update unack_data field in the assoc. */
1341 sctp_sack_update_unack_data(asoc, sack);
1342
1343 ctsn = asoc->ctsn_ack_point;
1344
1345 /* Throw away stuff rotting on the sack queue. */
1346 list_for_each_safe(lchunk, temp, &q->sacked) {
1347 tchunk = list_entry(lchunk, struct sctp_chunk,
1348 transmitted_list);
1349 tsn = ntohl(tchunk->subh.data_hdr->tsn);
1350 if (TSN_lte(tsn, ctsn)) {
1351 list_del_init(&tchunk->transmitted_list);
1352 if (asoc->peer.prsctp_capable &&
1353 SCTP_PR_PRIO_ENABLED(chunk->sinfo.sinfo_flags))
1354 asoc->sent_cnt_removable--;
1355 sctp_chunk_free(tchunk);
1356 }
1357 }
1358
1359 /* ii) Set rwnd equal to the newly received a_rwnd minus the
1360 * number of bytes still outstanding after processing the
1361 * Cumulative TSN Ack and the Gap Ack Blocks.
1362 */
1363
1364 sack_a_rwnd = ntohl(sack->a_rwnd);
1365 asoc->peer.zero_window_announced = !sack_a_rwnd;
1366 outstanding = q->outstanding_bytes;
1367
1368 if (outstanding < sack_a_rwnd)
1369 sack_a_rwnd -= outstanding;
1370 else
1371 sack_a_rwnd = 0;
1372
1373 asoc->peer.rwnd = sack_a_rwnd;
1374
1375 asoc->stream.si->generate_ftsn(q, sack_ctsn);
1376
1377 pr_debug("%s: sack cumulative tsn ack:0x%x\n", __func__, sack_ctsn);
1378 pr_debug("%s: cumulative tsn ack of assoc:%p is 0x%x, "
1379 "advertised peer ack point:0x%x\n", __func__, asoc, ctsn,
1380 asoc->adv_peer_ack_point);
1381
1382 return sctp_outq_is_empty(q);
1383 }
1384
1385 /* Is the outqueue empty?
1386 * The queue is empty when we have not pending data, no in-flight data
1387 * and nothing pending retransmissions.
1388 */
sctp_outq_is_empty(const struct sctp_outq * q)1389 int sctp_outq_is_empty(const struct sctp_outq *q)
1390 {
1391 return q->out_qlen == 0 && q->outstanding_bytes == 0 &&
1392 list_empty(&q->retransmit);
1393 }
1394
1395 /********************************************************************
1396 * 2nd Level Abstractions
1397 ********************************************************************/
1398
1399 /* Go through a transport's transmitted list or the association's retransmit
1400 * list and move chunks that are acked by the Cumulative TSN Ack to q->sacked.
1401 * The retransmit list will not have an associated transport.
1402 *
1403 * I added coherent debug information output. --xguo
1404 *
1405 * Instead of printing 'sacked' or 'kept' for each TSN on the
1406 * transmitted_queue, we print a range: SACKED: TSN1-TSN2, TSN3, TSN4-TSN5.
1407 * KEPT TSN6-TSN7, etc.
1408 */
sctp_check_transmitted(struct sctp_outq * q,struct list_head * transmitted_queue,struct sctp_transport * transport,union sctp_addr * saddr,struct sctp_sackhdr * sack,__u32 * highest_new_tsn_in_sack)1409 static void sctp_check_transmitted(struct sctp_outq *q,
1410 struct list_head *transmitted_queue,
1411 struct sctp_transport *transport,
1412 union sctp_addr *saddr,
1413 struct sctp_sackhdr *sack,
1414 __u32 *highest_new_tsn_in_sack)
1415 {
1416 struct list_head *lchunk;
1417 struct sctp_chunk *tchunk;
1418 struct list_head tlist;
1419 __u32 tsn;
1420 __u32 sack_ctsn;
1421 __u32 rtt;
1422 __u8 restart_timer = 0;
1423 int bytes_acked = 0;
1424 int migrate_bytes = 0;
1425 bool forward_progress = false;
1426
1427 sack_ctsn = ntohl(sack->cum_tsn_ack);
1428
1429 INIT_LIST_HEAD(&tlist);
1430
1431 /* The while loop will skip empty transmitted queues. */
1432 while (NULL != (lchunk = sctp_list_dequeue(transmitted_queue))) {
1433 tchunk = list_entry(lchunk, struct sctp_chunk,
1434 transmitted_list);
1435
1436 if (sctp_chunk_abandoned(tchunk)) {
1437 /* Move the chunk to abandoned list. */
1438 sctp_insert_list(&q->abandoned, lchunk);
1439
1440 /* If this chunk has not been acked, stop
1441 * considering it as 'outstanding'.
1442 */
1443 if (transmitted_queue != &q->retransmit &&
1444 !tchunk->tsn_gap_acked) {
1445 if (tchunk->transport)
1446 tchunk->transport->flight_size -=
1447 sctp_data_size(tchunk);
1448 q->outstanding_bytes -= sctp_data_size(tchunk);
1449 }
1450 continue;
1451 }
1452
1453 tsn = ntohl(tchunk->subh.data_hdr->tsn);
1454 if (sctp_acked(sack, tsn)) {
1455 /* If this queue is the retransmit queue, the
1456 * retransmit timer has already reclaimed
1457 * the outstanding bytes for this chunk, so only
1458 * count bytes associated with a transport.
1459 */
1460 if (transport && !tchunk->tsn_gap_acked) {
1461 /* If this chunk is being used for RTT
1462 * measurement, calculate the RTT and update
1463 * the RTO using this value.
1464 *
1465 * 6.3.1 C5) Karn's algorithm: RTT measurements
1466 * MUST NOT be made using packets that were
1467 * retransmitted (and thus for which it is
1468 * ambiguous whether the reply was for the
1469 * first instance of the packet or a later
1470 * instance).
1471 */
1472 if (!sctp_chunk_retransmitted(tchunk) &&
1473 tchunk->rtt_in_progress) {
1474 tchunk->rtt_in_progress = 0;
1475 rtt = jiffies - tchunk->sent_at;
1476 sctp_transport_update_rto(transport,
1477 rtt);
1478 }
1479
1480 if (TSN_lte(tsn, sack_ctsn)) {
1481 /*
1482 * SFR-CACC algorithm:
1483 * 2) If the SACK contains gap acks
1484 * and the flag CHANGEOVER_ACTIVE is
1485 * set the receiver of the SACK MUST
1486 * take the following action:
1487 *
1488 * B) For each TSN t being acked that
1489 * has not been acked in any SACK so
1490 * far, set cacc_saw_newack to 1 for
1491 * the destination that the TSN was
1492 * sent to.
1493 */
1494 if (sack->num_gap_ack_blocks &&
1495 q->asoc->peer.primary_path->cacc.
1496 changeover_active)
1497 transport->cacc.cacc_saw_newack
1498 = 1;
1499 }
1500 }
1501
1502 /* If the chunk hasn't been marked as ACKED,
1503 * mark it and account bytes_acked if the
1504 * chunk had a valid transport (it will not
1505 * have a transport if ASCONF had deleted it
1506 * while DATA was outstanding).
1507 */
1508 if (!tchunk->tsn_gap_acked) {
1509 tchunk->tsn_gap_acked = 1;
1510 if (TSN_lt(*highest_new_tsn_in_sack, tsn))
1511 *highest_new_tsn_in_sack = tsn;
1512 bytes_acked += sctp_data_size(tchunk);
1513 if (!tchunk->transport)
1514 migrate_bytes += sctp_data_size(tchunk);
1515 forward_progress = true;
1516 }
1517
1518 if (TSN_lte(tsn, sack_ctsn)) {
1519 /* RFC 2960 6.3.2 Retransmission Timer Rules
1520 *
1521 * R3) Whenever a SACK is received
1522 * that acknowledges the DATA chunk
1523 * with the earliest outstanding TSN
1524 * for that address, restart T3-rtx
1525 * timer for that address with its
1526 * current RTO.
1527 */
1528 restart_timer = 1;
1529 forward_progress = true;
1530
1531 list_add_tail(&tchunk->transmitted_list,
1532 &q->sacked);
1533 } else {
1534 /* RFC2960 7.2.4, sctpimpguide-05 2.8.2
1535 * M2) Each time a SACK arrives reporting
1536 * 'Stray DATA chunk(s)' record the highest TSN
1537 * reported as newly acknowledged, call this
1538 * value 'HighestTSNinSack'. A newly
1539 * acknowledged DATA chunk is one not
1540 * previously acknowledged in a SACK.
1541 *
1542 * When the SCTP sender of data receives a SACK
1543 * chunk that acknowledges, for the first time,
1544 * the receipt of a DATA chunk, all the still
1545 * unacknowledged DATA chunks whose TSN is
1546 * older than that newly acknowledged DATA
1547 * chunk, are qualified as 'Stray DATA chunks'.
1548 */
1549 list_add_tail(lchunk, &tlist);
1550 }
1551 } else {
1552 if (tchunk->tsn_gap_acked) {
1553 pr_debug("%s: receiver reneged on data TSN:0x%x\n",
1554 __func__, tsn);
1555
1556 tchunk->tsn_gap_acked = 0;
1557
1558 if (tchunk->transport)
1559 bytes_acked -= sctp_data_size(tchunk);
1560
1561 /* RFC 2960 6.3.2 Retransmission Timer Rules
1562 *
1563 * R4) Whenever a SACK is received missing a
1564 * TSN that was previously acknowledged via a
1565 * Gap Ack Block, start T3-rtx for the
1566 * destination address to which the DATA
1567 * chunk was originally
1568 * transmitted if it is not already running.
1569 */
1570 restart_timer = 1;
1571 }
1572
1573 list_add_tail(lchunk, &tlist);
1574 }
1575 }
1576
1577 if (transport) {
1578 if (bytes_acked) {
1579 struct sctp_association *asoc = transport->asoc;
1580
1581 /* We may have counted DATA that was migrated
1582 * to this transport due to DEL-IP operation.
1583 * Subtract those bytes, since the were never
1584 * send on this transport and shouldn't be
1585 * credited to this transport.
1586 */
1587 bytes_acked -= migrate_bytes;
1588
1589 /* 8.2. When an outstanding TSN is acknowledged,
1590 * the endpoint shall clear the error counter of
1591 * the destination transport address to which the
1592 * DATA chunk was last sent.
1593 * The association's overall error counter is
1594 * also cleared.
1595 */
1596 transport->error_count = 0;
1597 transport->asoc->overall_error_count = 0;
1598 forward_progress = true;
1599
1600 /*
1601 * While in SHUTDOWN PENDING, we may have started
1602 * the T5 shutdown guard timer after reaching the
1603 * retransmission limit. Stop that timer as soon
1604 * as the receiver acknowledged any data.
1605 */
1606 if (asoc->state == SCTP_STATE_SHUTDOWN_PENDING &&
1607 del_timer(&asoc->timers
1608 [SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD]))
1609 sctp_association_put(asoc);
1610
1611 /* Mark the destination transport address as
1612 * active if it is not so marked.
1613 */
1614 if ((transport->state == SCTP_INACTIVE ||
1615 transport->state == SCTP_UNCONFIRMED) &&
1616 sctp_cmp_addr_exact(&transport->ipaddr, saddr)) {
1617 sctp_assoc_control_transport(
1618 transport->asoc,
1619 transport,
1620 SCTP_TRANSPORT_UP,
1621 SCTP_RECEIVED_SACK);
1622 }
1623
1624 sctp_transport_raise_cwnd(transport, sack_ctsn,
1625 bytes_acked);
1626
1627 transport->flight_size -= bytes_acked;
1628 if (transport->flight_size == 0)
1629 transport->partial_bytes_acked = 0;
1630 q->outstanding_bytes -= bytes_acked + migrate_bytes;
1631 } else {
1632 /* RFC 2960 6.1, sctpimpguide-06 2.15.2
1633 * When a sender is doing zero window probing, it
1634 * should not timeout the association if it continues
1635 * to receive new packets from the receiver. The
1636 * reason is that the receiver MAY keep its window
1637 * closed for an indefinite time.
1638 * A sender is doing zero window probing when the
1639 * receiver's advertised window is zero, and there is
1640 * only one data chunk in flight to the receiver.
1641 *
1642 * Allow the association to timeout while in SHUTDOWN
1643 * PENDING or SHUTDOWN RECEIVED in case the receiver
1644 * stays in zero window mode forever.
1645 */
1646 if (!q->asoc->peer.rwnd &&
1647 !list_empty(&tlist) &&
1648 (sack_ctsn+2 == q->asoc->next_tsn) &&
1649 q->asoc->state < SCTP_STATE_SHUTDOWN_PENDING) {
1650 pr_debug("%s: sack received for zero window "
1651 "probe:%u\n", __func__, sack_ctsn);
1652
1653 q->asoc->overall_error_count = 0;
1654 transport->error_count = 0;
1655 }
1656 }
1657
1658 /* RFC 2960 6.3.2 Retransmission Timer Rules
1659 *
1660 * R2) Whenever all outstanding data sent to an address have
1661 * been acknowledged, turn off the T3-rtx timer of that
1662 * address.
1663 */
1664 if (!transport->flight_size) {
1665 if (del_timer(&transport->T3_rtx_timer))
1666 sctp_transport_put(transport);
1667 } else if (restart_timer) {
1668 if (!mod_timer(&transport->T3_rtx_timer,
1669 jiffies + transport->rto))
1670 sctp_transport_hold(transport);
1671 }
1672
1673 if (forward_progress) {
1674 if (transport->dst)
1675 sctp_transport_dst_confirm(transport);
1676 }
1677 }
1678
1679 list_splice(&tlist, transmitted_queue);
1680 }
1681
1682 /* Mark chunks as missing and consequently may get retransmitted. */
sctp_mark_missing(struct sctp_outq * q,struct list_head * transmitted_queue,struct sctp_transport * transport,__u32 highest_new_tsn_in_sack,int count_of_newacks)1683 static void sctp_mark_missing(struct sctp_outq *q,
1684 struct list_head *transmitted_queue,
1685 struct sctp_transport *transport,
1686 __u32 highest_new_tsn_in_sack,
1687 int count_of_newacks)
1688 {
1689 struct sctp_chunk *chunk;
1690 __u32 tsn;
1691 char do_fast_retransmit = 0;
1692 struct sctp_association *asoc = q->asoc;
1693 struct sctp_transport *primary = asoc->peer.primary_path;
1694
1695 list_for_each_entry(chunk, transmitted_queue, transmitted_list) {
1696
1697 tsn = ntohl(chunk->subh.data_hdr->tsn);
1698
1699 /* RFC 2960 7.2.4, sctpimpguide-05 2.8.2 M3) Examine all
1700 * 'Unacknowledged TSN's', if the TSN number of an
1701 * 'Unacknowledged TSN' is smaller than the 'HighestTSNinSack'
1702 * value, increment the 'TSN.Missing.Report' count on that
1703 * chunk if it has NOT been fast retransmitted or marked for
1704 * fast retransmit already.
1705 */
1706 if (chunk->fast_retransmit == SCTP_CAN_FRTX &&
1707 !chunk->tsn_gap_acked &&
1708 TSN_lt(tsn, highest_new_tsn_in_sack)) {
1709
1710 /* SFR-CACC may require us to skip marking
1711 * this chunk as missing.
1712 */
1713 if (!transport || !sctp_cacc_skip(primary,
1714 chunk->transport,
1715 count_of_newacks, tsn)) {
1716 chunk->tsn_missing_report++;
1717
1718 pr_debug("%s: tsn:0x%x missing counter:%d\n",
1719 __func__, tsn, chunk->tsn_missing_report);
1720 }
1721 }
1722 /*
1723 * M4) If any DATA chunk is found to have a
1724 * 'TSN.Missing.Report'
1725 * value larger than or equal to 3, mark that chunk for
1726 * retransmission and start the fast retransmit procedure.
1727 */
1728
1729 if (chunk->tsn_missing_report >= 3) {
1730 chunk->fast_retransmit = SCTP_NEED_FRTX;
1731 do_fast_retransmit = 1;
1732 }
1733 }
1734
1735 if (transport) {
1736 if (do_fast_retransmit)
1737 sctp_retransmit(q, transport, SCTP_RTXR_FAST_RTX);
1738
1739 pr_debug("%s: transport:%p, cwnd:%d, ssthresh:%d, "
1740 "flight_size:%d, pba:%d\n", __func__, transport,
1741 transport->cwnd, transport->ssthresh,
1742 transport->flight_size, transport->partial_bytes_acked);
1743 }
1744 }
1745
1746 /* Is the given TSN acked by this packet? */
sctp_acked(struct sctp_sackhdr * sack,__u32 tsn)1747 static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn)
1748 {
1749 __u32 ctsn = ntohl(sack->cum_tsn_ack);
1750 union sctp_sack_variable *frags;
1751 __u16 tsn_offset, blocks;
1752 int i;
1753
1754 if (TSN_lte(tsn, ctsn))
1755 goto pass;
1756
1757 /* 3.3.4 Selective Acknowledgment (SACK) (3):
1758 *
1759 * Gap Ack Blocks:
1760 * These fields contain the Gap Ack Blocks. They are repeated
1761 * for each Gap Ack Block up to the number of Gap Ack Blocks
1762 * defined in the Number of Gap Ack Blocks field. All DATA
1763 * chunks with TSNs greater than or equal to (Cumulative TSN
1764 * Ack + Gap Ack Block Start) and less than or equal to
1765 * (Cumulative TSN Ack + Gap Ack Block End) of each Gap Ack
1766 * Block are assumed to have been received correctly.
1767 */
1768
1769 frags = sack->variable;
1770 blocks = ntohs(sack->num_gap_ack_blocks);
1771 tsn_offset = tsn - ctsn;
1772 for (i = 0; i < blocks; ++i) {
1773 if (tsn_offset >= ntohs(frags[i].gab.start) &&
1774 tsn_offset <= ntohs(frags[i].gab.end))
1775 goto pass;
1776 }
1777
1778 return 0;
1779 pass:
1780 return 1;
1781 }
1782
sctp_get_skip_pos(struct sctp_fwdtsn_skip * skiplist,int nskips,__be16 stream)1783 static inline int sctp_get_skip_pos(struct sctp_fwdtsn_skip *skiplist,
1784 int nskips, __be16 stream)
1785 {
1786 int i;
1787
1788 for (i = 0; i < nskips; i++) {
1789 if (skiplist[i].stream == stream)
1790 return i;
1791 }
1792 return i;
1793 }
1794
1795 /* Create and add a fwdtsn chunk to the outq's control queue if needed. */
sctp_generate_fwdtsn(struct sctp_outq * q,__u32 ctsn)1796 void sctp_generate_fwdtsn(struct sctp_outq *q, __u32 ctsn)
1797 {
1798 struct sctp_association *asoc = q->asoc;
1799 struct sctp_chunk *ftsn_chunk = NULL;
1800 struct sctp_fwdtsn_skip ftsn_skip_arr[10];
1801 int nskips = 0;
1802 int skip_pos = 0;
1803 __u32 tsn;
1804 struct sctp_chunk *chunk;
1805 struct list_head *lchunk, *temp;
1806
1807 if (!asoc->peer.prsctp_capable)
1808 return;
1809
1810 /* PR-SCTP C1) Let SackCumAck be the Cumulative TSN ACK carried in the
1811 * received SACK.
1812 *
1813 * If (Advanced.Peer.Ack.Point < SackCumAck), then update
1814 * Advanced.Peer.Ack.Point to be equal to SackCumAck.
1815 */
1816 if (TSN_lt(asoc->adv_peer_ack_point, ctsn))
1817 asoc->adv_peer_ack_point = ctsn;
1818
1819 /* PR-SCTP C2) Try to further advance the "Advanced.Peer.Ack.Point"
1820 * locally, that is, to move "Advanced.Peer.Ack.Point" up as long as
1821 * the chunk next in the out-queue space is marked as "abandoned" as
1822 * shown in the following example:
1823 *
1824 * Assuming that a SACK arrived with the Cumulative TSN ACK 102
1825 * and the Advanced.Peer.Ack.Point is updated to this value:
1826 *
1827 * out-queue at the end of ==> out-queue after Adv.Ack.Point
1828 * normal SACK processing local advancement
1829 * ... ...
1830 * Adv.Ack.Pt-> 102 acked 102 acked
1831 * 103 abandoned 103 abandoned
1832 * 104 abandoned Adv.Ack.P-> 104 abandoned
1833 * 105 105
1834 * 106 acked 106 acked
1835 * ... ...
1836 *
1837 * In this example, the data sender successfully advanced the
1838 * "Advanced.Peer.Ack.Point" from 102 to 104 locally.
1839 */
1840 list_for_each_safe(lchunk, temp, &q->abandoned) {
1841 chunk = list_entry(lchunk, struct sctp_chunk,
1842 transmitted_list);
1843 tsn = ntohl(chunk->subh.data_hdr->tsn);
1844
1845 /* Remove any chunks in the abandoned queue that are acked by
1846 * the ctsn.
1847 */
1848 if (TSN_lte(tsn, ctsn)) {
1849 list_del_init(lchunk);
1850 sctp_chunk_free(chunk);
1851 } else {
1852 if (TSN_lte(tsn, asoc->adv_peer_ack_point+1)) {
1853 asoc->adv_peer_ack_point = tsn;
1854 if (chunk->chunk_hdr->flags &
1855 SCTP_DATA_UNORDERED)
1856 continue;
1857 skip_pos = sctp_get_skip_pos(&ftsn_skip_arr[0],
1858 nskips,
1859 chunk->subh.data_hdr->stream);
1860 ftsn_skip_arr[skip_pos].stream =
1861 chunk->subh.data_hdr->stream;
1862 ftsn_skip_arr[skip_pos].ssn =
1863 chunk->subh.data_hdr->ssn;
1864 if (skip_pos == nskips)
1865 nskips++;
1866 if (nskips == 10)
1867 break;
1868 } else
1869 break;
1870 }
1871 }
1872
1873 /* PR-SCTP C3) If, after step C1 and C2, the "Advanced.Peer.Ack.Point"
1874 * is greater than the Cumulative TSN ACK carried in the received
1875 * SACK, the data sender MUST send the data receiver a FORWARD TSN
1876 * chunk containing the latest value of the
1877 * "Advanced.Peer.Ack.Point".
1878 *
1879 * C4) For each "abandoned" TSN the sender of the FORWARD TSN SHOULD
1880 * list each stream and sequence number in the forwarded TSN. This
1881 * information will enable the receiver to easily find any
1882 * stranded TSN's waiting on stream reorder queues. Each stream
1883 * SHOULD only be reported once; this means that if multiple
1884 * abandoned messages occur in the same stream then only the
1885 * highest abandoned stream sequence number is reported. If the
1886 * total size of the FORWARD TSN does NOT fit in a single MTU then
1887 * the sender of the FORWARD TSN SHOULD lower the
1888 * Advanced.Peer.Ack.Point to the last TSN that will fit in a
1889 * single MTU.
1890 */
1891 if (asoc->adv_peer_ack_point > ctsn)
1892 ftsn_chunk = sctp_make_fwdtsn(asoc, asoc->adv_peer_ack_point,
1893 nskips, &ftsn_skip_arr[0]);
1894
1895 if (ftsn_chunk) {
1896 list_add_tail(&ftsn_chunk->list, &q->control_chunk_list);
1897 SCTP_INC_STATS(asoc->base.net, SCTP_MIB_OUTCTRLCHUNKS);
1898 }
1899 }
1900