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