1 /* SCTP kernel implementation
2 * (C) Copyright IBM Corp. 2001, 2004
3 * Copyright (c) 1999-2000 Cisco, Inc.
4 * Copyright (c) 1999-2001 Motorola, Inc.
5 * Copyright (c) 2001-2003 Intel Corp.
7 * This file is part of the SCTP kernel implementation
9 * These functions implement the sctp_outq class. The outqueue handles
10 * bundling and queueing of outgoing SCTP chunks.
12 * This SCTP implementation is free software;
13 * you can redistribute it and/or modify it under the terms of
14 * the GNU General Public License as published by
15 * the Free Software Foundation; either version 2, or (at your option)
18 * This SCTP implementation is distributed in the hope that it
19 * will be useful, but WITHOUT ANY WARRANTY; without even the implied
20 * ************************
21 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
22 * See the GNU General Public License for more details.
24 * You should have received a copy of the GNU General Public License
25 * along with GNU CC; see the file COPYING. If not, see
26 * <http://www.gnu.org/licenses/>.
28 * Please send any bug reports or fixes you make to the
30 * lksctp developers <linux-sctp@vger.kernel.org>
32 * Written or modified by:
33 * La Monte H.P. Yarroll <piggy@acm.org>
34 * Karl Knutson <karl@athena.chicago.il.us>
35 * Perry Melange <pmelange@null.cc.uic.edu>
36 * Xingang Guo <xingang.guo@intel.com>
37 * Hui Huang <hui.huang@nokia.com>
38 * Sridhar Samudrala <sri@us.ibm.com>
39 * Jon Grimm <jgrimm@us.ibm.com>
42 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
44 #include <linux/types.h>
45 #include <linux/list.h> /* For struct list_head */
46 #include <linux/socket.h>
48 #include <linux/slab.h>
49 #include <net/sock.h> /* For skb_set_owner_w */
51 #include <net/sctp/sctp.h>
52 #include <net/sctp/sm.h>
54 /* Declare internal functions here. */
55 static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn);
56 static void sctp_check_transmitted(struct sctp_outq *q,
57 struct list_head *transmitted_queue,
58 struct sctp_transport *transport,
59 union sctp_addr *saddr,
60 struct sctp_sackhdr *sack,
61 __u32 *highest_new_tsn);
63 static void sctp_mark_missing(struct sctp_outq *q,
64 struct list_head *transmitted_queue,
65 struct sctp_transport *transport,
66 __u32 highest_new_tsn,
67 int count_of_newacks);
69 static void sctp_generate_fwdtsn(struct sctp_outq *q, __u32 sack_ctsn);
71 static void sctp_outq_flush(struct sctp_outq *q, int rtx_timeout, gfp_t gfp);
73 /* Add data to the front of the queue. */
74 static inline void sctp_outq_head_data(struct sctp_outq *q,
75 struct sctp_chunk *ch)
77 list_add(&ch->list, &q->out_chunk_list);
78 q->out_qlen += ch->skb->len;
81 /* Take data from the front of the queue. */
82 static inline struct sctp_chunk *sctp_outq_dequeue_data(struct sctp_outq *q)
84 struct sctp_chunk *ch = NULL;
86 if (!list_empty(&q->out_chunk_list)) {
87 struct list_head *entry = q->out_chunk_list.next;
89 ch = list_entry(entry, struct sctp_chunk, list);
91 q->out_qlen -= ch->skb->len;
95 /* Add data chunk to the end of the queue. */
96 static inline void sctp_outq_tail_data(struct sctp_outq *q,
97 struct sctp_chunk *ch)
99 list_add_tail(&ch->list, &q->out_chunk_list);
100 q->out_qlen += ch->skb->len;
104 * SFR-CACC algorithm:
105 * D) If count_of_newacks is greater than or equal to 2
106 * and t was not sent to the current primary then the
107 * sender MUST NOT increment missing report count for t.
109 static inline int sctp_cacc_skip_3_1_d(struct sctp_transport *primary,
110 struct sctp_transport *transport,
111 int count_of_newacks)
113 if (count_of_newacks >= 2 && transport != primary)
119 * SFR-CACC algorithm:
120 * F) If count_of_newacks is less than 2, let d be the
121 * destination to which t was sent. If cacc_saw_newack
122 * is 0 for destination d, then the sender MUST NOT
123 * increment missing report count for t.
125 static inline int sctp_cacc_skip_3_1_f(struct sctp_transport *transport,
126 int count_of_newacks)
128 if (count_of_newacks < 2 &&
129 (transport && !transport->cacc.cacc_saw_newack))
135 * SFR-CACC algorithm:
136 * 3.1) If CYCLING_CHANGEOVER is 0, the sender SHOULD
137 * execute steps C, D, F.
139 * C has been implemented in sctp_outq_sack
141 static inline int sctp_cacc_skip_3_1(struct sctp_transport *primary,
142 struct sctp_transport *transport,
143 int count_of_newacks)
145 if (!primary->cacc.cycling_changeover) {
146 if (sctp_cacc_skip_3_1_d(primary, transport, count_of_newacks))
148 if (sctp_cacc_skip_3_1_f(transport, count_of_newacks))
156 * SFR-CACC algorithm:
157 * 3.2) Else if CYCLING_CHANGEOVER is 1, and t is less
158 * than next_tsn_at_change of the current primary, then
159 * the sender MUST NOT increment missing report count
162 static inline int sctp_cacc_skip_3_2(struct sctp_transport *primary, __u32 tsn)
164 if (primary->cacc.cycling_changeover &&
165 TSN_lt(tsn, primary->cacc.next_tsn_at_change))
171 * SFR-CACC algorithm:
172 * 3) If the missing report count for TSN t is to be
173 * incremented according to [RFC2960] and
174 * [SCTP_STEWART-2002], and CHANGEOVER_ACTIVE is set,
175 * then the sender MUST further execute steps 3.1 and
176 * 3.2 to determine if the missing report count for
177 * TSN t SHOULD NOT be incremented.
179 * 3.3) If 3.1 and 3.2 do not dictate that the missing
180 * report count for t should not be incremented, then
181 * the sender SHOULD increment missing report count for
182 * t (according to [RFC2960] and [SCTP_STEWART_2002]).
184 static inline int sctp_cacc_skip(struct sctp_transport *primary,
185 struct sctp_transport *transport,
186 int count_of_newacks,
189 if (primary->cacc.changeover_active &&
190 (sctp_cacc_skip_3_1(primary, transport, count_of_newacks) ||
191 sctp_cacc_skip_3_2(primary, tsn)))
196 /* Initialize an existing sctp_outq. This does the boring stuff.
197 * You still need to define handlers if you really want to DO
198 * something with this structure...
200 void sctp_outq_init(struct sctp_association *asoc, struct sctp_outq *q)
202 memset(q, 0, sizeof(struct sctp_outq));
205 INIT_LIST_HEAD(&q->out_chunk_list);
206 INIT_LIST_HEAD(&q->control_chunk_list);
207 INIT_LIST_HEAD(&q->retransmit);
208 INIT_LIST_HEAD(&q->sacked);
209 INIT_LIST_HEAD(&q->abandoned);
212 /* Free the outqueue structure and any related pending chunks.
214 static void __sctp_outq_teardown(struct sctp_outq *q)
216 struct sctp_transport *transport;
217 struct list_head *lchunk, *temp;
218 struct sctp_chunk *chunk, *tmp;
220 /* Throw away unacknowledged chunks. */
221 list_for_each_entry(transport, &q->asoc->peer.transport_addr_list,
223 while ((lchunk = sctp_list_dequeue(&transport->transmitted)) != NULL) {
224 chunk = list_entry(lchunk, struct sctp_chunk,
226 /* Mark as part of a failed message. */
227 sctp_chunk_fail(chunk, q->error);
228 sctp_chunk_free(chunk);
232 /* Throw away chunks that have been gap ACKed. */
233 list_for_each_safe(lchunk, temp, &q->sacked) {
234 list_del_init(lchunk);
235 chunk = list_entry(lchunk, struct sctp_chunk,
237 sctp_chunk_fail(chunk, q->error);
238 sctp_chunk_free(chunk);
241 /* Throw away any chunks in the retransmit queue. */
242 list_for_each_safe(lchunk, temp, &q->retransmit) {
243 list_del_init(lchunk);
244 chunk = list_entry(lchunk, struct sctp_chunk,
246 sctp_chunk_fail(chunk, q->error);
247 sctp_chunk_free(chunk);
250 /* Throw away any chunks that are in the abandoned queue. */
251 list_for_each_safe(lchunk, temp, &q->abandoned) {
252 list_del_init(lchunk);
253 chunk = list_entry(lchunk, struct sctp_chunk,
255 sctp_chunk_fail(chunk, q->error);
256 sctp_chunk_free(chunk);
259 /* Throw away any leftover data chunks. */
260 while ((chunk = sctp_outq_dequeue_data(q)) != NULL) {
262 /* Mark as send failure. */
263 sctp_chunk_fail(chunk, q->error);
264 sctp_chunk_free(chunk);
267 /* Throw away any leftover control chunks. */
268 list_for_each_entry_safe(chunk, tmp, &q->control_chunk_list, list) {
269 list_del_init(&chunk->list);
270 sctp_chunk_free(chunk);
274 void sctp_outq_teardown(struct sctp_outq *q)
276 __sctp_outq_teardown(q);
277 sctp_outq_init(q->asoc, q);
280 /* Free the outqueue structure and any related pending chunks. */
281 void sctp_outq_free(struct sctp_outq *q)
283 /* Throw away leftover chunks. */
284 __sctp_outq_teardown(q);
287 /* Put a new chunk in an sctp_outq. */
288 void sctp_outq_tail(struct sctp_outq *q, struct sctp_chunk *chunk, gfp_t gfp)
290 struct net *net = sock_net(q->asoc->base.sk);
292 pr_debug("%s: outq:%p, chunk:%p[%s]\n", __func__, q, chunk,
293 chunk && chunk->chunk_hdr ?
294 sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)) :
297 /* If it is data, queue it up, otherwise, send it
300 if (sctp_chunk_is_data(chunk)) {
301 pr_debug("%s: outqueueing: outq:%p, chunk:%p[%s])\n",
302 __func__, q, chunk, chunk && chunk->chunk_hdr ?
303 sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)) :
306 sctp_outq_tail_data(q, chunk);
307 if (chunk->asoc->peer.prsctp_capable &&
308 SCTP_PR_PRIO_ENABLED(chunk->sinfo.sinfo_flags))
309 chunk->asoc->sent_cnt_removable++;
310 if (chunk->chunk_hdr->flags & SCTP_DATA_UNORDERED)
311 SCTP_INC_STATS(net, SCTP_MIB_OUTUNORDERCHUNKS);
313 SCTP_INC_STATS(net, SCTP_MIB_OUTORDERCHUNKS);
315 list_add_tail(&chunk->list, &q->control_chunk_list);
316 SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
320 sctp_outq_flush(q, 0, gfp);
323 /* Insert a chunk into the sorted list based on the TSNs. The retransmit list
324 * and the abandoned list are in ascending order.
326 static void sctp_insert_list(struct list_head *head, struct list_head *new)
328 struct list_head *pos;
329 struct sctp_chunk *nchunk, *lchunk;
333 nchunk = list_entry(new, struct sctp_chunk, transmitted_list);
334 ntsn = ntohl(nchunk->subh.data_hdr->tsn);
336 list_for_each(pos, head) {
337 lchunk = list_entry(pos, struct sctp_chunk, transmitted_list);
338 ltsn = ntohl(lchunk->subh.data_hdr->tsn);
339 if (TSN_lt(ntsn, ltsn)) {
340 list_add(new, pos->prev);
346 list_add_tail(new, head);
349 static int sctp_prsctp_prune_sent(struct sctp_association *asoc,
350 struct sctp_sndrcvinfo *sinfo,
351 struct list_head *queue, int msg_len)
353 struct sctp_chunk *chk, *temp;
355 list_for_each_entry_safe(chk, temp, queue, transmitted_list) {
356 if (!SCTP_PR_PRIO_ENABLED(chk->sinfo.sinfo_flags) ||
357 chk->sinfo.sinfo_timetolive <= sinfo->sinfo_timetolive)
360 list_del_init(&chk->transmitted_list);
361 sctp_insert_list(&asoc->outqueue.abandoned,
362 &chk->transmitted_list);
364 asoc->sent_cnt_removable--;
365 asoc->abandoned_sent[SCTP_PR_INDEX(PRIO)]++;
367 if (!chk->tsn_gap_acked) {
369 chk->transport->flight_size -=
371 asoc->outqueue.outstanding_bytes -= sctp_data_size(chk);
374 msg_len -= SCTP_DATA_SNDSIZE(chk) +
375 sizeof(struct sk_buff) +
376 sizeof(struct sctp_chunk);
384 static int sctp_prsctp_prune_unsent(struct sctp_association *asoc,
385 struct sctp_sndrcvinfo *sinfo, int msg_len)
387 struct sctp_outq *q = &asoc->outqueue;
388 struct sctp_chunk *chk, *temp;
390 list_for_each_entry_safe(chk, temp, &q->out_chunk_list, list) {
391 if (!SCTP_PR_PRIO_ENABLED(chk->sinfo.sinfo_flags) ||
392 chk->sinfo.sinfo_timetolive <= sinfo->sinfo_timetolive)
395 list_del_init(&chk->list);
396 q->out_qlen -= chk->skb->len;
397 asoc->sent_cnt_removable--;
398 asoc->abandoned_unsent[SCTP_PR_INDEX(PRIO)]++;
400 msg_len -= SCTP_DATA_SNDSIZE(chk) +
401 sizeof(struct sk_buff) +
402 sizeof(struct sctp_chunk);
403 sctp_chunk_free(chk);
411 /* Abandon the chunks according their priorities */
412 void sctp_prsctp_prune(struct sctp_association *asoc,
413 struct sctp_sndrcvinfo *sinfo, int msg_len)
415 struct sctp_transport *transport;
417 if (!asoc->peer.prsctp_capable || !asoc->sent_cnt_removable)
420 msg_len = sctp_prsctp_prune_sent(asoc, sinfo,
421 &asoc->outqueue.retransmit,
426 list_for_each_entry(transport, &asoc->peer.transport_addr_list,
428 msg_len = sctp_prsctp_prune_sent(asoc, sinfo,
429 &transport->transmitted,
435 sctp_prsctp_prune_unsent(asoc, sinfo, msg_len);
438 /* Mark all the eligible packets on a transport for retransmission. */
439 void sctp_retransmit_mark(struct sctp_outq *q,
440 struct sctp_transport *transport,
443 struct list_head *lchunk, *ltemp;
444 struct sctp_chunk *chunk;
446 /* Walk through the specified transmitted queue. */
447 list_for_each_safe(lchunk, ltemp, &transport->transmitted) {
448 chunk = list_entry(lchunk, struct sctp_chunk,
451 /* If the chunk is abandoned, move it to abandoned list. */
452 if (sctp_chunk_abandoned(chunk)) {
453 list_del_init(lchunk);
454 sctp_insert_list(&q->abandoned, lchunk);
456 /* If this chunk has not been previousely acked,
457 * stop considering it 'outstanding'. Our peer
458 * will most likely never see it since it will
459 * not be retransmitted
461 if (!chunk->tsn_gap_acked) {
462 if (chunk->transport)
463 chunk->transport->flight_size -=
464 sctp_data_size(chunk);
465 q->outstanding_bytes -= sctp_data_size(chunk);
466 q->asoc->peer.rwnd += sctp_data_size(chunk);
471 /* If we are doing retransmission due to a timeout or pmtu
472 * discovery, only the chunks that are not yet acked should
473 * be added to the retransmit queue.
475 if ((reason == SCTP_RTXR_FAST_RTX &&
476 (chunk->fast_retransmit == SCTP_NEED_FRTX)) ||
477 (reason != SCTP_RTXR_FAST_RTX && !chunk->tsn_gap_acked)) {
478 /* RFC 2960 6.2.1 Processing a Received SACK
480 * C) Any time a DATA chunk is marked for
481 * retransmission (via either T3-rtx timer expiration
482 * (Section 6.3.3) or via fast retransmit
483 * (Section 7.2.4)), add the data size of those
484 * chunks to the rwnd.
486 q->asoc->peer.rwnd += sctp_data_size(chunk);
487 q->outstanding_bytes -= sctp_data_size(chunk);
488 if (chunk->transport)
489 transport->flight_size -= sctp_data_size(chunk);
491 /* sctpimpguide-05 Section 2.8.2
492 * M5) If a T3-rtx timer expires, the
493 * 'TSN.Missing.Report' of all affected TSNs is set
496 chunk->tsn_missing_report = 0;
498 /* If a chunk that is being used for RTT measurement
499 * has to be retransmitted, we cannot use this chunk
500 * anymore for RTT measurements. Reset rto_pending so
501 * that a new RTT measurement is started when a new
502 * data chunk is sent.
504 if (chunk->rtt_in_progress) {
505 chunk->rtt_in_progress = 0;
506 transport->rto_pending = 0;
509 /* Move the chunk to the retransmit queue. The chunks
510 * on the retransmit queue are always kept in order.
512 list_del_init(lchunk);
513 sctp_insert_list(&q->retransmit, lchunk);
517 pr_debug("%s: transport:%p, reason:%d, cwnd:%d, ssthresh:%d, "
518 "flight_size:%d, pba:%d\n", __func__, transport, reason,
519 transport->cwnd, transport->ssthresh, transport->flight_size,
520 transport->partial_bytes_acked);
523 /* Mark all the eligible packets on a transport for retransmission and force
526 void sctp_retransmit(struct sctp_outq *q, struct sctp_transport *transport,
527 sctp_retransmit_reason_t reason)
529 struct net *net = sock_net(q->asoc->base.sk);
532 case SCTP_RTXR_T3_RTX:
533 SCTP_INC_STATS(net, SCTP_MIB_T3_RETRANSMITS);
534 sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_T3_RTX);
535 /* Update the retran path if the T3-rtx timer has expired for
536 * the current retran path.
538 if (transport == transport->asoc->peer.retran_path)
539 sctp_assoc_update_retran_path(transport->asoc);
540 transport->asoc->rtx_data_chunks +=
541 transport->asoc->unack_data;
543 case SCTP_RTXR_FAST_RTX:
544 SCTP_INC_STATS(net, SCTP_MIB_FAST_RETRANSMITS);
545 sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_FAST_RTX);
548 case SCTP_RTXR_PMTUD:
549 SCTP_INC_STATS(net, SCTP_MIB_PMTUD_RETRANSMITS);
551 case SCTP_RTXR_T1_RTX:
552 SCTP_INC_STATS(net, SCTP_MIB_T1_RETRANSMITS);
553 transport->asoc->init_retries++;
559 sctp_retransmit_mark(q, transport, reason);
561 /* PR-SCTP A5) Any time the T3-rtx timer expires, on any destination,
562 * the sender SHOULD try to advance the "Advanced.Peer.Ack.Point" by
563 * following the procedures outlined in C1 - C5.
565 if (reason == SCTP_RTXR_T3_RTX)
566 sctp_generate_fwdtsn(q, q->asoc->ctsn_ack_point);
568 /* Flush the queues only on timeout, since fast_rtx is only
569 * triggered during sack processing and the queue
570 * will be flushed at the end.
572 if (reason != SCTP_RTXR_FAST_RTX)
573 sctp_outq_flush(q, /* rtx_timeout */ 1, GFP_ATOMIC);
577 * Transmit DATA chunks on the retransmit queue. Upon return from
578 * sctp_outq_flush_rtx() the packet 'pkt' may contain chunks which
579 * need to be transmitted by the caller.
580 * We assume that pkt->transport has already been set.
582 * The return value is a normal kernel error return value.
584 static int sctp_outq_flush_rtx(struct sctp_outq *q, struct sctp_packet *pkt,
585 int rtx_timeout, int *start_timer)
587 struct list_head *lqueue;
588 struct sctp_transport *transport = pkt->transport;
590 struct sctp_chunk *chunk, *chunk1;
596 lqueue = &q->retransmit;
597 fast_rtx = q->fast_rtx;
599 /* This loop handles time-out retransmissions, fast retransmissions,
600 * and retransmissions due to opening of whindow.
602 * RFC 2960 6.3.3 Handle T3-rtx Expiration
604 * E3) Determine how many of the earliest (i.e., lowest TSN)
605 * outstanding DATA chunks for the address for which the
606 * T3-rtx has expired will fit into a single packet, subject
607 * to the MTU constraint for the path corresponding to the
608 * destination transport address to which the retransmission
609 * is being sent (this may be different from the address for
610 * which the timer expires [see Section 6.4]). Call this value
611 * K. Bundle and retransmit those K DATA chunks in a single
612 * packet to the destination endpoint.
614 * [Just to be painfully clear, if we are retransmitting
615 * because a timeout just happened, we should send only ONE
616 * packet of retransmitted data.]
618 * For fast retransmissions we also send only ONE packet. However,
619 * if we are just flushing the queue due to open window, we'll
620 * try to send as much as possible.
622 list_for_each_entry_safe(chunk, chunk1, lqueue, transmitted_list) {
623 /* If the chunk is abandoned, move it to abandoned list. */
624 if (sctp_chunk_abandoned(chunk)) {
625 list_del_init(&chunk->transmitted_list);
626 sctp_insert_list(&q->abandoned,
627 &chunk->transmitted_list);
631 /* Make sure that Gap Acked TSNs are not retransmitted. A
632 * simple approach is just to move such TSNs out of the
633 * way and into a 'transmitted' queue and skip to the
636 if (chunk->tsn_gap_acked) {
637 list_move_tail(&chunk->transmitted_list,
638 &transport->transmitted);
642 /* If we are doing fast retransmit, ignore non-fast_rtransmit
645 if (fast_rtx && !chunk->fast_retransmit)
649 /* Attempt to append this chunk to the packet. */
650 status = sctp_packet_append_chunk(pkt, chunk);
653 case SCTP_XMIT_PMTU_FULL:
654 if (!pkt->has_data && !pkt->has_cookie_echo) {
655 /* If this packet did not contain DATA then
656 * retransmission did not happen, so do it
657 * again. We'll ignore the error here since
658 * control chunks are already freed so there
659 * is nothing we can do.
661 sctp_packet_transmit(pkt, GFP_ATOMIC);
665 /* Send this packet. */
666 error = sctp_packet_transmit(pkt, GFP_ATOMIC);
668 /* If we are retransmitting, we should only
669 * send a single packet.
670 * Otherwise, try appending this chunk again.
672 if (rtx_timeout || fast_rtx)
677 /* Bundle next chunk in the next round. */
680 case SCTP_XMIT_RWND_FULL:
681 /* Send this packet. */
682 error = sctp_packet_transmit(pkt, GFP_ATOMIC);
684 /* Stop sending DATA as there is no more room
690 case SCTP_XMIT_DELAY:
691 /* Send this packet. */
692 error = sctp_packet_transmit(pkt, GFP_ATOMIC);
694 /* Stop sending DATA because of nagle delay. */
699 /* The append was successful, so add this chunk to
700 * the transmitted list.
702 list_move_tail(&chunk->transmitted_list,
703 &transport->transmitted);
705 /* Mark the chunk as ineligible for fast retransmit
706 * after it is retransmitted.
708 if (chunk->fast_retransmit == SCTP_NEED_FRTX)
709 chunk->fast_retransmit = SCTP_DONT_FRTX;
711 q->asoc->stats.rtxchunks++;
715 /* Set the timer if there were no errors */
716 if (!error && !timer)
723 /* If we are here due to a retransmit timeout or a fast
724 * retransmit and if there are any chunks left in the retransmit
725 * queue that could not fit in the PMTU sized packet, they need
726 * to be marked as ineligible for a subsequent fast retransmit.
728 if (rtx_timeout || fast_rtx) {
729 list_for_each_entry(chunk1, lqueue, transmitted_list) {
730 if (chunk1->fast_retransmit == SCTP_NEED_FRTX)
731 chunk1->fast_retransmit = SCTP_DONT_FRTX;
735 *start_timer = timer;
737 /* Clear fast retransmit hint */
744 /* Cork the outqueue so queued chunks are really queued. */
745 void sctp_outq_uncork(struct sctp_outq *q, gfp_t gfp)
750 sctp_outq_flush(q, 0, gfp);
755 * Try to flush an outqueue.
757 * Description: Send everything in q which we legally can, subject to
758 * congestion limitations.
759 * * Note: This function can be called from multiple contexts so appropriate
760 * locking concerns must be made. Today we use the sock lock to protect
763 static void sctp_outq_flush(struct sctp_outq *q, int rtx_timeout, gfp_t gfp)
765 struct sctp_packet *packet;
766 struct sctp_packet singleton;
767 struct sctp_association *asoc = q->asoc;
768 __u16 sport = asoc->base.bind_addr.port;
769 __u16 dport = asoc->peer.port;
770 __u32 vtag = asoc->peer.i.init_tag;
771 struct sctp_transport *transport = NULL;
772 struct sctp_transport *new_transport;
773 struct sctp_chunk *chunk, *tmp;
779 /* These transports have chunks to send. */
780 struct list_head transport_list;
781 struct list_head *ltransport;
783 INIT_LIST_HEAD(&transport_list);
789 * When bundling control chunks with DATA chunks, an
790 * endpoint MUST place control chunks first in the outbound
791 * SCTP packet. The transmitter MUST transmit DATA chunks
792 * within a SCTP packet in increasing order of TSN.
796 list_for_each_entry_safe(chunk, tmp, &q->control_chunk_list, list) {
798 * F1) This means that until such time as the ASCONF
799 * containing the add is acknowledged, the sender MUST
800 * NOT use the new IP address as a source for ANY SCTP
801 * packet except on carrying an ASCONF Chunk.
803 if (asoc->src_out_of_asoc_ok &&
804 chunk->chunk_hdr->type != SCTP_CID_ASCONF)
807 list_del_init(&chunk->list);
809 /* Pick the right transport to use. */
810 new_transport = chunk->transport;
812 if (!new_transport) {
814 * If we have a prior transport pointer, see if
815 * the destination address of the chunk
816 * matches the destination address of the
817 * current transport. If not a match, then
818 * try to look up the transport with a given
819 * destination address. We do this because
820 * after processing ASCONFs, we may have new
821 * transports created.
824 sctp_cmp_addr_exact(&chunk->dest,
826 new_transport = transport;
828 new_transport = sctp_assoc_lookup_paddr(asoc,
831 /* if we still don't have a new transport, then
832 * use the current active path.
835 new_transport = asoc->peer.active_path;
836 } else if ((new_transport->state == SCTP_INACTIVE) ||
837 (new_transport->state == SCTP_UNCONFIRMED) ||
838 (new_transport->state == SCTP_PF)) {
839 /* If the chunk is Heartbeat or Heartbeat Ack,
840 * send it to chunk->transport, even if it's
843 * 3.3.6 Heartbeat Acknowledgement:
845 * A HEARTBEAT ACK is always sent to the source IP
846 * address of the IP datagram containing the
847 * HEARTBEAT chunk to which this ack is responding.
850 * ASCONF_ACKs also must be sent to the source.
852 if (chunk->chunk_hdr->type != SCTP_CID_HEARTBEAT &&
853 chunk->chunk_hdr->type != SCTP_CID_HEARTBEAT_ACK &&
854 chunk->chunk_hdr->type != SCTP_CID_ASCONF_ACK)
855 new_transport = asoc->peer.active_path;
858 /* Are we switching transports?
859 * Take care of transport locks.
861 if (new_transport != transport) {
862 transport = new_transport;
863 if (list_empty(&transport->send_ready)) {
864 list_add_tail(&transport->send_ready,
867 packet = &transport->packet;
868 sctp_packet_config(packet, vtag,
869 asoc->peer.ecn_capable);
872 switch (chunk->chunk_hdr->type) {
876 * An endpoint MUST NOT bundle INIT, INIT ACK or SHUTDOWN
877 * COMPLETE with any other chunks. [Send them immediately.]
880 case SCTP_CID_INIT_ACK:
881 case SCTP_CID_SHUTDOWN_COMPLETE:
882 sctp_packet_init(&singleton, transport, sport, dport);
883 sctp_packet_config(&singleton, vtag, 0);
884 sctp_packet_append_chunk(&singleton, chunk);
885 error = sctp_packet_transmit(&singleton, gfp);
887 asoc->base.sk->sk_err = -error;
893 if (sctp_test_T_bit(chunk)) {
894 packet->vtag = asoc->c.my_vtag;
896 /* The following chunks are "response" chunks, i.e.
897 * they are generated in response to something we
898 * received. If we are sending these, then we can
899 * send only 1 packet containing these chunks.
901 case SCTP_CID_HEARTBEAT_ACK:
902 case SCTP_CID_SHUTDOWN_ACK:
903 case SCTP_CID_COOKIE_ACK:
904 case SCTP_CID_COOKIE_ECHO:
906 case SCTP_CID_ECN_CWR:
907 case SCTP_CID_ASCONF_ACK:
912 case SCTP_CID_HEARTBEAT:
913 case SCTP_CID_SHUTDOWN:
914 case SCTP_CID_ECN_ECNE:
915 case SCTP_CID_ASCONF:
916 case SCTP_CID_FWD_TSN:
917 case SCTP_CID_RECONF:
918 status = sctp_packet_transmit_chunk(packet, chunk,
920 if (status != SCTP_XMIT_OK) {
921 /* put the chunk back */
922 list_add(&chunk->list, &q->control_chunk_list);
926 asoc->stats.octrlchunks++;
927 /* PR-SCTP C5) If a FORWARD TSN is sent, the
928 * sender MUST assure that at least one T3-rtx
931 if (chunk->chunk_hdr->type == SCTP_CID_FWD_TSN) {
932 sctp_transport_reset_t3_rtx(transport);
933 transport->last_time_sent = jiffies;
936 if (chunk == asoc->strreset_chunk)
937 sctp_transport_reset_reconf_timer(transport);
942 /* We built a chunk with an illegal type! */
947 if (q->asoc->src_out_of_asoc_ok)
950 /* Is it OK to send data chunks? */
951 switch (asoc->state) {
952 case SCTP_STATE_COOKIE_ECHOED:
953 /* Only allow bundling when this packet has a COOKIE-ECHO
956 if (!packet || !packet->has_cookie_echo)
960 case SCTP_STATE_ESTABLISHED:
961 case SCTP_STATE_SHUTDOWN_PENDING:
962 case SCTP_STATE_SHUTDOWN_RECEIVED:
964 * RFC 2960 6.1 Transmission of DATA Chunks
966 * C) When the time comes for the sender to transmit,
967 * before sending new DATA chunks, the sender MUST
968 * first transmit any outstanding DATA chunks which
969 * are marked for retransmission (limited by the
972 if (!list_empty(&q->retransmit)) {
973 if (asoc->peer.retran_path->state == SCTP_UNCONFIRMED)
975 if (transport == asoc->peer.retran_path)
978 /* Switch transports & prepare the packet. */
980 transport = asoc->peer.retran_path;
982 if (list_empty(&transport->send_ready)) {
983 list_add_tail(&transport->send_ready,
987 packet = &transport->packet;
988 sctp_packet_config(packet, vtag,
989 asoc->peer.ecn_capable);
991 error = sctp_outq_flush_rtx(q, packet,
992 rtx_timeout, &start_timer);
994 asoc->base.sk->sk_err = -error;
997 sctp_transport_reset_t3_rtx(transport);
998 transport->last_time_sent = jiffies;
1001 /* This can happen on COOKIE-ECHO resend. Only
1002 * one chunk can get bundled with a COOKIE-ECHO.
1004 if (packet->has_cookie_echo)
1005 goto sctp_flush_out;
1007 /* Don't send new data if there is still data
1008 * waiting to retransmit.
1010 if (!list_empty(&q->retransmit))
1011 goto sctp_flush_out;
1014 /* Apply Max.Burst limitation to the current transport in
1015 * case it will be used for new data. We are going to
1016 * rest it before we return, but we want to apply the limit
1017 * to the currently queued data.
1020 sctp_transport_burst_limited(transport);
1022 /* Finally, transmit new packets. */
1023 while ((chunk = sctp_outq_dequeue_data(q)) != NULL) {
1024 __u32 sid = ntohs(chunk->subh.data_hdr->stream);
1026 /* RFC 2960 6.5 Every DATA chunk MUST carry a valid
1027 * stream identifier.
1029 if (chunk->sinfo.sinfo_stream >=
1030 asoc->c.sinit_num_ostreams) {
1032 /* Mark as failed send. */
1033 sctp_chunk_fail(chunk, SCTP_ERROR_INV_STRM);
1034 if (asoc->peer.prsctp_capable &&
1035 SCTP_PR_PRIO_ENABLED(chunk->sinfo.sinfo_flags))
1036 asoc->sent_cnt_removable--;
1037 sctp_chunk_free(chunk);
1041 /* Has this chunk expired? */
1042 if (sctp_chunk_abandoned(chunk)) {
1043 sctp_chunk_fail(chunk, 0);
1044 sctp_chunk_free(chunk);
1048 if (asoc->stream->out[sid].state == SCTP_STREAM_CLOSED) {
1049 sctp_outq_head_data(q, chunk);
1050 goto sctp_flush_out;
1053 /* If there is a specified transport, use it.
1054 * Otherwise, we want to use the active path.
1056 new_transport = chunk->transport;
1057 if (!new_transport ||
1058 ((new_transport->state == SCTP_INACTIVE) ||
1059 (new_transport->state == SCTP_UNCONFIRMED) ||
1060 (new_transport->state == SCTP_PF)))
1061 new_transport = asoc->peer.active_path;
1062 if (new_transport->state == SCTP_UNCONFIRMED) {
1063 WARN_ONCE(1, "Attempt to send packet on unconfirmed path.");
1064 sctp_chunk_fail(chunk, 0);
1065 sctp_chunk_free(chunk);
1069 /* Change packets if necessary. */
1070 if (new_transport != transport) {
1071 transport = new_transport;
1073 /* Schedule to have this transport's
1076 if (list_empty(&transport->send_ready)) {
1077 list_add_tail(&transport->send_ready,
1081 packet = &transport->packet;
1082 sctp_packet_config(packet, vtag,
1083 asoc->peer.ecn_capable);
1084 /* We've switched transports, so apply the
1085 * Burst limit to the new transport.
1087 sctp_transport_burst_limited(transport);
1090 pr_debug("%s: outq:%p, chunk:%p[%s], tx-tsn:0x%x skb->head:%p "
1092 __func__, q, chunk, chunk && chunk->chunk_hdr ?
1093 sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)) :
1094 "illegal chunk", ntohl(chunk->subh.data_hdr->tsn),
1095 chunk->skb ? chunk->skb->head : NULL, chunk->skb ?
1096 atomic_read(&chunk->skb->users) : -1);
1098 /* Add the chunk to the packet. */
1099 status = sctp_packet_transmit_chunk(packet, chunk, 0, gfp);
1102 case SCTP_XMIT_PMTU_FULL:
1103 case SCTP_XMIT_RWND_FULL:
1104 case SCTP_XMIT_DELAY:
1105 /* We could not append this chunk, so put
1106 * the chunk back on the output queue.
1108 pr_debug("%s: could not transmit tsn:0x%x, status:%d\n",
1109 __func__, ntohl(chunk->subh.data_hdr->tsn),
1112 sctp_outq_head_data(q, chunk);
1113 goto sctp_flush_out;
1116 /* The sender is in the SHUTDOWN-PENDING state,
1117 * The sender MAY set the I-bit in the DATA
1120 if (asoc->state == SCTP_STATE_SHUTDOWN_PENDING)
1121 chunk->chunk_hdr->flags |= SCTP_DATA_SACK_IMM;
1122 if (chunk->chunk_hdr->flags & SCTP_DATA_UNORDERED)
1123 asoc->stats.ouodchunks++;
1125 asoc->stats.oodchunks++;
1133 /* BUG: We assume that the sctp_packet_transmit()
1134 * call below will succeed all the time and add the
1135 * chunk to the transmitted list and restart the
1137 * It is possible that the call can fail under OOM
1140 * Is this really a problem? Won't this behave
1143 list_add_tail(&chunk->transmitted_list,
1144 &transport->transmitted);
1146 sctp_transport_reset_t3_rtx(transport);
1147 transport->last_time_sent = jiffies;
1149 /* Only let one DATA chunk get bundled with a
1150 * COOKIE-ECHO chunk.
1152 if (packet->has_cookie_echo)
1153 goto sctp_flush_out;
1164 /* Before returning, examine all the transports touched in
1165 * this call. Right now, we bluntly force clear all the
1166 * transports. Things might change after we implement Nagle.
1167 * But such an examination is still required.
1171 while ((ltransport = sctp_list_dequeue(&transport_list)) != NULL) {
1172 struct sctp_transport *t = list_entry(ltransport,
1173 struct sctp_transport,
1175 packet = &t->packet;
1176 if (!sctp_packet_empty(packet)) {
1177 error = sctp_packet_transmit(packet, gfp);
1179 asoc->base.sk->sk_err = -error;
1182 /* Clear the burst limited state, if any */
1183 sctp_transport_burst_reset(t);
1187 /* Update unack_data based on the incoming SACK chunk */
1188 static void sctp_sack_update_unack_data(struct sctp_association *assoc,
1189 struct sctp_sackhdr *sack)
1191 sctp_sack_variable_t *frags;
1195 unack_data = assoc->next_tsn - assoc->ctsn_ack_point - 1;
1197 frags = sack->variable;
1198 for (i = 0; i < ntohs(sack->num_gap_ack_blocks); i++) {
1199 unack_data -= ((ntohs(frags[i].gab.end) -
1200 ntohs(frags[i].gab.start) + 1));
1203 assoc->unack_data = unack_data;
1206 /* This is where we REALLY process a SACK.
1208 * Process the SACK against the outqueue. Mostly, this just frees
1209 * things off the transmitted queue.
1211 int sctp_outq_sack(struct sctp_outq *q, struct sctp_chunk *chunk)
1213 struct sctp_association *asoc = q->asoc;
1214 struct sctp_sackhdr *sack = chunk->subh.sack_hdr;
1215 struct sctp_transport *transport;
1216 struct sctp_chunk *tchunk = NULL;
1217 struct list_head *lchunk, *transport_list, *temp;
1218 sctp_sack_variable_t *frags = sack->variable;
1219 __u32 sack_ctsn, ctsn, tsn;
1220 __u32 highest_tsn, highest_new_tsn;
1222 unsigned int outstanding;
1223 struct sctp_transport *primary = asoc->peer.primary_path;
1224 int count_of_newacks = 0;
1228 /* Grab the association's destination address list. */
1229 transport_list = &asoc->peer.transport_addr_list;
1231 sack_ctsn = ntohl(sack->cum_tsn_ack);
1232 gap_ack_blocks = ntohs(sack->num_gap_ack_blocks);
1233 asoc->stats.gapcnt += gap_ack_blocks;
1235 * SFR-CACC algorithm:
1236 * On receipt of a SACK the sender SHOULD execute the
1237 * following statements.
1239 * 1) If the cumulative ack in the SACK passes next tsn_at_change
1240 * on the current primary, the CHANGEOVER_ACTIVE flag SHOULD be
1241 * cleared. The CYCLING_CHANGEOVER flag SHOULD also be cleared for
1243 * 2) If the SACK contains gap acks and the flag CHANGEOVER_ACTIVE
1244 * is set the receiver of the SACK MUST take the following actions:
1246 * A) Initialize the cacc_saw_newack to 0 for all destination
1249 * Only bother if changeover_active is set. Otherwise, this is
1250 * totally suboptimal to do on every SACK.
1252 if (primary->cacc.changeover_active) {
1253 u8 clear_cycling = 0;
1255 if (TSN_lte(primary->cacc.next_tsn_at_change, sack_ctsn)) {
1256 primary->cacc.changeover_active = 0;
1260 if (clear_cycling || gap_ack_blocks) {
1261 list_for_each_entry(transport, transport_list,
1264 transport->cacc.cycling_changeover = 0;
1266 transport->cacc.cacc_saw_newack = 0;
1271 /* Get the highest TSN in the sack. */
1272 highest_tsn = sack_ctsn;
1274 highest_tsn += ntohs(frags[gap_ack_blocks - 1].gab.end);
1276 if (TSN_lt(asoc->highest_sacked, highest_tsn))
1277 asoc->highest_sacked = highest_tsn;
1279 highest_new_tsn = sack_ctsn;
1281 /* Run through the retransmit queue. Credit bytes received
1282 * and free those chunks that we can.
1284 sctp_check_transmitted(q, &q->retransmit, NULL, NULL, sack, &highest_new_tsn);
1286 /* Run through the transmitted queue.
1287 * Credit bytes received and free those chunks which we can.
1289 * This is a MASSIVE candidate for optimization.
1291 list_for_each_entry(transport, transport_list, transports) {
1292 sctp_check_transmitted(q, &transport->transmitted,
1293 transport, &chunk->source, sack,
1296 * SFR-CACC algorithm:
1297 * C) Let count_of_newacks be the number of
1298 * destinations for which cacc_saw_newack is set.
1300 if (transport->cacc.cacc_saw_newack)
1304 /* Move the Cumulative TSN Ack Point if appropriate. */
1305 if (TSN_lt(asoc->ctsn_ack_point, sack_ctsn)) {
1306 asoc->ctsn_ack_point = sack_ctsn;
1310 if (gap_ack_blocks) {
1312 if (asoc->fast_recovery && accum_moved)
1313 highest_new_tsn = highest_tsn;
1315 list_for_each_entry(transport, transport_list, transports)
1316 sctp_mark_missing(q, &transport->transmitted, transport,
1317 highest_new_tsn, count_of_newacks);
1320 /* Update unack_data field in the assoc. */
1321 sctp_sack_update_unack_data(asoc, sack);
1323 ctsn = asoc->ctsn_ack_point;
1325 /* Throw away stuff rotting on the sack queue. */
1326 list_for_each_safe(lchunk, temp, &q->sacked) {
1327 tchunk = list_entry(lchunk, struct sctp_chunk,
1329 tsn = ntohl(tchunk->subh.data_hdr->tsn);
1330 if (TSN_lte(tsn, ctsn)) {
1331 list_del_init(&tchunk->transmitted_list);
1332 if (asoc->peer.prsctp_capable &&
1333 SCTP_PR_PRIO_ENABLED(chunk->sinfo.sinfo_flags))
1334 asoc->sent_cnt_removable--;
1335 sctp_chunk_free(tchunk);
1339 /* ii) Set rwnd equal to the newly received a_rwnd minus the
1340 * number of bytes still outstanding after processing the
1341 * Cumulative TSN Ack and the Gap Ack Blocks.
1344 sack_a_rwnd = ntohl(sack->a_rwnd);
1345 asoc->peer.zero_window_announced = !sack_a_rwnd;
1346 outstanding = q->outstanding_bytes;
1348 if (outstanding < sack_a_rwnd)
1349 sack_a_rwnd -= outstanding;
1353 asoc->peer.rwnd = sack_a_rwnd;
1355 sctp_generate_fwdtsn(q, sack_ctsn);
1357 pr_debug("%s: sack cumulative tsn ack:0x%x\n", __func__, sack_ctsn);
1358 pr_debug("%s: cumulative tsn ack of assoc:%p is 0x%x, "
1359 "advertised peer ack point:0x%x\n", __func__, asoc, ctsn,
1360 asoc->adv_peer_ack_point);
1362 return sctp_outq_is_empty(q);
1365 /* Is the outqueue empty?
1366 * The queue is empty when we have not pending data, no in-flight data
1367 * and nothing pending retransmissions.
1369 int sctp_outq_is_empty(const struct sctp_outq *q)
1371 return q->out_qlen == 0 && q->outstanding_bytes == 0 &&
1372 list_empty(&q->retransmit);
1375 /********************************************************************
1376 * 2nd Level Abstractions
1377 ********************************************************************/
1379 /* Go through a transport's transmitted list or the association's retransmit
1380 * list and move chunks that are acked by the Cumulative TSN Ack to q->sacked.
1381 * The retransmit list will not have an associated transport.
1383 * I added coherent debug information output. --xguo
1385 * Instead of printing 'sacked' or 'kept' for each TSN on the
1386 * transmitted_queue, we print a range: SACKED: TSN1-TSN2, TSN3, TSN4-TSN5.
1387 * KEPT TSN6-TSN7, etc.
1389 static void sctp_check_transmitted(struct sctp_outq *q,
1390 struct list_head *transmitted_queue,
1391 struct sctp_transport *transport,
1392 union sctp_addr *saddr,
1393 struct sctp_sackhdr *sack,
1394 __u32 *highest_new_tsn_in_sack)
1396 struct list_head *lchunk;
1397 struct sctp_chunk *tchunk;
1398 struct list_head tlist;
1402 __u8 restart_timer = 0;
1403 int bytes_acked = 0;
1404 int migrate_bytes = 0;
1405 bool forward_progress = false;
1407 sack_ctsn = ntohl(sack->cum_tsn_ack);
1409 INIT_LIST_HEAD(&tlist);
1411 /* The while loop will skip empty transmitted queues. */
1412 while (NULL != (lchunk = sctp_list_dequeue(transmitted_queue))) {
1413 tchunk = list_entry(lchunk, struct sctp_chunk,
1416 if (sctp_chunk_abandoned(tchunk)) {
1417 /* Move the chunk to abandoned list. */
1418 sctp_insert_list(&q->abandoned, lchunk);
1420 /* If this chunk has not been acked, stop
1421 * considering it as 'outstanding'.
1423 if (!tchunk->tsn_gap_acked) {
1424 if (tchunk->transport)
1425 tchunk->transport->flight_size -=
1426 sctp_data_size(tchunk);
1427 q->outstanding_bytes -= sctp_data_size(tchunk);
1432 tsn = ntohl(tchunk->subh.data_hdr->tsn);
1433 if (sctp_acked(sack, tsn)) {
1434 /* If this queue is the retransmit queue, the
1435 * retransmit timer has already reclaimed
1436 * the outstanding bytes for this chunk, so only
1437 * count bytes associated with a transport.
1440 /* If this chunk is being used for RTT
1441 * measurement, calculate the RTT and update
1442 * the RTO using this value.
1444 * 6.3.1 C5) Karn's algorithm: RTT measurements
1445 * MUST NOT be made using packets that were
1446 * retransmitted (and thus for which it is
1447 * ambiguous whether the reply was for the
1448 * first instance of the packet or a later
1451 if (!tchunk->tsn_gap_acked &&
1452 !sctp_chunk_retransmitted(tchunk) &&
1453 tchunk->rtt_in_progress) {
1454 tchunk->rtt_in_progress = 0;
1455 rtt = jiffies - tchunk->sent_at;
1456 sctp_transport_update_rto(transport,
1461 /* If the chunk hasn't been marked as ACKED,
1462 * mark it and account bytes_acked if the
1463 * chunk had a valid transport (it will not
1464 * have a transport if ASCONF had deleted it
1465 * while DATA was outstanding).
1467 if (!tchunk->tsn_gap_acked) {
1468 tchunk->tsn_gap_acked = 1;
1469 if (TSN_lt(*highest_new_tsn_in_sack, tsn))
1470 *highest_new_tsn_in_sack = tsn;
1471 bytes_acked += sctp_data_size(tchunk);
1472 if (!tchunk->transport)
1473 migrate_bytes += sctp_data_size(tchunk);
1474 forward_progress = true;
1477 if (TSN_lte(tsn, sack_ctsn)) {
1478 /* RFC 2960 6.3.2 Retransmission Timer Rules
1480 * R3) Whenever a SACK is received
1481 * that acknowledges the DATA chunk
1482 * with the earliest outstanding TSN
1483 * for that address, restart T3-rtx
1484 * timer for that address with its
1488 forward_progress = true;
1490 if (!tchunk->tsn_gap_acked) {
1492 * SFR-CACC algorithm:
1493 * 2) If the SACK contains gap acks
1494 * and the flag CHANGEOVER_ACTIVE is
1495 * set the receiver of the SACK MUST
1496 * take the following action:
1498 * B) For each TSN t being acked that
1499 * has not been acked in any SACK so
1500 * far, set cacc_saw_newack to 1 for
1501 * the destination that the TSN was
1505 sack->num_gap_ack_blocks &&
1506 q->asoc->peer.primary_path->cacc.
1508 transport->cacc.cacc_saw_newack
1512 list_add_tail(&tchunk->transmitted_list,
1515 /* RFC2960 7.2.4, sctpimpguide-05 2.8.2
1516 * M2) Each time a SACK arrives reporting
1517 * 'Stray DATA chunk(s)' record the highest TSN
1518 * reported as newly acknowledged, call this
1519 * value 'HighestTSNinSack'. A newly
1520 * acknowledged DATA chunk is one not
1521 * previously acknowledged in a SACK.
1523 * When the SCTP sender of data receives a SACK
1524 * chunk that acknowledges, for the first time,
1525 * the receipt of a DATA chunk, all the still
1526 * unacknowledged DATA chunks whose TSN is
1527 * older than that newly acknowledged DATA
1528 * chunk, are qualified as 'Stray DATA chunks'.
1530 list_add_tail(lchunk, &tlist);
1533 if (tchunk->tsn_gap_acked) {
1534 pr_debug("%s: receiver reneged on data TSN:0x%x\n",
1537 tchunk->tsn_gap_acked = 0;
1539 if (tchunk->transport)
1540 bytes_acked -= sctp_data_size(tchunk);
1542 /* RFC 2960 6.3.2 Retransmission Timer Rules
1544 * R4) Whenever a SACK is received missing a
1545 * TSN that was previously acknowledged via a
1546 * Gap Ack Block, start T3-rtx for the
1547 * destination address to which the DATA
1548 * chunk was originally
1549 * transmitted if it is not already running.
1554 list_add_tail(lchunk, &tlist);
1560 struct sctp_association *asoc = transport->asoc;
1562 /* We may have counted DATA that was migrated
1563 * to this transport due to DEL-IP operation.
1564 * Subtract those bytes, since the were never
1565 * send on this transport and shouldn't be
1566 * credited to this transport.
1568 bytes_acked -= migrate_bytes;
1570 /* 8.2. When an outstanding TSN is acknowledged,
1571 * the endpoint shall clear the error counter of
1572 * the destination transport address to which the
1573 * DATA chunk was last sent.
1574 * The association's overall error counter is
1577 transport->error_count = 0;
1578 transport->asoc->overall_error_count = 0;
1579 forward_progress = true;
1582 * While in SHUTDOWN PENDING, we may have started
1583 * the T5 shutdown guard timer after reaching the
1584 * retransmission limit. Stop that timer as soon
1585 * as the receiver acknowledged any data.
1587 if (asoc->state == SCTP_STATE_SHUTDOWN_PENDING &&
1588 del_timer(&asoc->timers
1589 [SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD]))
1590 sctp_association_put(asoc);
1592 /* Mark the destination transport address as
1593 * active if it is not so marked.
1595 if ((transport->state == SCTP_INACTIVE ||
1596 transport->state == SCTP_UNCONFIRMED) &&
1597 sctp_cmp_addr_exact(&transport->ipaddr, saddr)) {
1598 sctp_assoc_control_transport(
1602 SCTP_RECEIVED_SACK);
1605 sctp_transport_raise_cwnd(transport, sack_ctsn,
1608 transport->flight_size -= bytes_acked;
1609 if (transport->flight_size == 0)
1610 transport->partial_bytes_acked = 0;
1611 q->outstanding_bytes -= bytes_acked + migrate_bytes;
1613 /* RFC 2960 6.1, sctpimpguide-06 2.15.2
1614 * When a sender is doing zero window probing, it
1615 * should not timeout the association if it continues
1616 * to receive new packets from the receiver. The
1617 * reason is that the receiver MAY keep its window
1618 * closed for an indefinite time.
1619 * A sender is doing zero window probing when the
1620 * receiver's advertised window is zero, and there is
1621 * only one data chunk in flight to the receiver.
1623 * Allow the association to timeout while in SHUTDOWN
1624 * PENDING or SHUTDOWN RECEIVED in case the receiver
1625 * stays in zero window mode forever.
1627 if (!q->asoc->peer.rwnd &&
1628 !list_empty(&tlist) &&
1629 (sack_ctsn+2 == q->asoc->next_tsn) &&
1630 q->asoc->state < SCTP_STATE_SHUTDOWN_PENDING) {
1631 pr_debug("%s: sack received for zero window "
1632 "probe:%u\n", __func__, sack_ctsn);
1634 q->asoc->overall_error_count = 0;
1635 transport->error_count = 0;
1639 /* RFC 2960 6.3.2 Retransmission Timer Rules
1641 * R2) Whenever all outstanding data sent to an address have
1642 * been acknowledged, turn off the T3-rtx timer of that
1645 if (!transport->flight_size) {
1646 if (del_timer(&transport->T3_rtx_timer))
1647 sctp_transport_put(transport);
1648 } else if (restart_timer) {
1649 if (!mod_timer(&transport->T3_rtx_timer,
1650 jiffies + transport->rto))
1651 sctp_transport_hold(transport);
1654 if (forward_progress) {
1656 sctp_transport_dst_confirm(transport);
1660 list_splice(&tlist, transmitted_queue);
1663 /* Mark chunks as missing and consequently may get retransmitted. */
1664 static void sctp_mark_missing(struct sctp_outq *q,
1665 struct list_head *transmitted_queue,
1666 struct sctp_transport *transport,
1667 __u32 highest_new_tsn_in_sack,
1668 int count_of_newacks)
1670 struct sctp_chunk *chunk;
1672 char do_fast_retransmit = 0;
1673 struct sctp_association *asoc = q->asoc;
1674 struct sctp_transport *primary = asoc->peer.primary_path;
1676 list_for_each_entry(chunk, transmitted_queue, transmitted_list) {
1678 tsn = ntohl(chunk->subh.data_hdr->tsn);
1680 /* RFC 2960 7.2.4, sctpimpguide-05 2.8.2 M3) Examine all
1681 * 'Unacknowledged TSN's', if the TSN number of an
1682 * 'Unacknowledged TSN' is smaller than the 'HighestTSNinSack'
1683 * value, increment the 'TSN.Missing.Report' count on that
1684 * chunk if it has NOT been fast retransmitted or marked for
1685 * fast retransmit already.
1687 if (chunk->fast_retransmit == SCTP_CAN_FRTX &&
1688 !chunk->tsn_gap_acked &&
1689 TSN_lt(tsn, highest_new_tsn_in_sack)) {
1691 /* SFR-CACC may require us to skip marking
1692 * this chunk as missing.
1694 if (!transport || !sctp_cacc_skip(primary,
1696 count_of_newacks, tsn)) {
1697 chunk->tsn_missing_report++;
1699 pr_debug("%s: tsn:0x%x missing counter:%d\n",
1700 __func__, tsn, chunk->tsn_missing_report);
1704 * M4) If any DATA chunk is found to have a
1705 * 'TSN.Missing.Report'
1706 * value larger than or equal to 3, mark that chunk for
1707 * retransmission and start the fast retransmit procedure.
1710 if (chunk->tsn_missing_report >= 3) {
1711 chunk->fast_retransmit = SCTP_NEED_FRTX;
1712 do_fast_retransmit = 1;
1717 if (do_fast_retransmit)
1718 sctp_retransmit(q, transport, SCTP_RTXR_FAST_RTX);
1720 pr_debug("%s: transport:%p, cwnd:%d, ssthresh:%d, "
1721 "flight_size:%d, pba:%d\n", __func__, transport,
1722 transport->cwnd, transport->ssthresh,
1723 transport->flight_size, transport->partial_bytes_acked);
1727 /* Is the given TSN acked by this packet? */
1728 static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn)
1731 sctp_sack_variable_t *frags;
1732 __u16 tsn_offset, blocks;
1733 __u32 ctsn = ntohl(sack->cum_tsn_ack);
1735 if (TSN_lte(tsn, ctsn))
1738 /* 3.3.4 Selective Acknowledgement (SACK) (3):
1741 * These fields contain the Gap Ack Blocks. They are repeated
1742 * for each Gap Ack Block up to the number of Gap Ack Blocks
1743 * defined in the Number of Gap Ack Blocks field. All DATA
1744 * chunks with TSNs greater than or equal to (Cumulative TSN
1745 * Ack + Gap Ack Block Start) and less than or equal to
1746 * (Cumulative TSN Ack + Gap Ack Block End) of each Gap Ack
1747 * Block are assumed to have been received correctly.
1750 frags = sack->variable;
1751 blocks = ntohs(sack->num_gap_ack_blocks);
1752 tsn_offset = tsn - ctsn;
1753 for (i = 0; i < blocks; ++i) {
1754 if (tsn_offset >= ntohs(frags[i].gab.start) &&
1755 tsn_offset <= ntohs(frags[i].gab.end))
1764 static inline int sctp_get_skip_pos(struct sctp_fwdtsn_skip *skiplist,
1765 int nskips, __be16 stream)
1769 for (i = 0; i < nskips; i++) {
1770 if (skiplist[i].stream == stream)
1776 /* Create and add a fwdtsn chunk to the outq's control queue if needed. */
1777 static void sctp_generate_fwdtsn(struct sctp_outq *q, __u32 ctsn)
1779 struct sctp_association *asoc = q->asoc;
1780 struct sctp_chunk *ftsn_chunk = NULL;
1781 struct sctp_fwdtsn_skip ftsn_skip_arr[10];
1785 struct sctp_chunk *chunk;
1786 struct list_head *lchunk, *temp;
1788 if (!asoc->peer.prsctp_capable)
1791 /* PR-SCTP C1) Let SackCumAck be the Cumulative TSN ACK carried in the
1794 * If (Advanced.Peer.Ack.Point < SackCumAck), then update
1795 * Advanced.Peer.Ack.Point to be equal to SackCumAck.
1797 if (TSN_lt(asoc->adv_peer_ack_point, ctsn))
1798 asoc->adv_peer_ack_point = ctsn;
1800 /* PR-SCTP C2) Try to further advance the "Advanced.Peer.Ack.Point"
1801 * locally, that is, to move "Advanced.Peer.Ack.Point" up as long as
1802 * the chunk next in the out-queue space is marked as "abandoned" as
1803 * shown in the following example:
1805 * Assuming that a SACK arrived with the Cumulative TSN ACK 102
1806 * and the Advanced.Peer.Ack.Point is updated to this value:
1808 * out-queue at the end of ==> out-queue after Adv.Ack.Point
1809 * normal SACK processing local advancement
1811 * Adv.Ack.Pt-> 102 acked 102 acked
1812 * 103 abandoned 103 abandoned
1813 * 104 abandoned Adv.Ack.P-> 104 abandoned
1815 * 106 acked 106 acked
1818 * In this example, the data sender successfully advanced the
1819 * "Advanced.Peer.Ack.Point" from 102 to 104 locally.
1821 list_for_each_safe(lchunk, temp, &q->abandoned) {
1822 chunk = list_entry(lchunk, struct sctp_chunk,
1824 tsn = ntohl(chunk->subh.data_hdr->tsn);
1826 /* Remove any chunks in the abandoned queue that are acked by
1829 if (TSN_lte(tsn, ctsn)) {
1830 list_del_init(lchunk);
1831 sctp_chunk_free(chunk);
1833 if (TSN_lte(tsn, asoc->adv_peer_ack_point+1)) {
1834 asoc->adv_peer_ack_point = tsn;
1835 if (chunk->chunk_hdr->flags &
1836 SCTP_DATA_UNORDERED)
1838 skip_pos = sctp_get_skip_pos(&ftsn_skip_arr[0],
1840 chunk->subh.data_hdr->stream);
1841 ftsn_skip_arr[skip_pos].stream =
1842 chunk->subh.data_hdr->stream;
1843 ftsn_skip_arr[skip_pos].ssn =
1844 chunk->subh.data_hdr->ssn;
1845 if (skip_pos == nskips)
1854 /* PR-SCTP C3) If, after step C1 and C2, the "Advanced.Peer.Ack.Point"
1855 * is greater than the Cumulative TSN ACK carried in the received
1856 * SACK, the data sender MUST send the data receiver a FORWARD TSN
1857 * chunk containing the latest value of the
1858 * "Advanced.Peer.Ack.Point".
1860 * C4) For each "abandoned" TSN the sender of the FORWARD TSN SHOULD
1861 * list each stream and sequence number in the forwarded TSN. This
1862 * information will enable the receiver to easily find any
1863 * stranded TSN's waiting on stream reorder queues. Each stream
1864 * SHOULD only be reported once; this means that if multiple
1865 * abandoned messages occur in the same stream then only the
1866 * highest abandoned stream sequence number is reported. If the
1867 * total size of the FORWARD TSN does NOT fit in a single MTU then
1868 * the sender of the FORWARD TSN SHOULD lower the
1869 * Advanced.Peer.Ack.Point to the last TSN that will fit in a
1872 if (asoc->adv_peer_ack_point > ctsn)
1873 ftsn_chunk = sctp_make_fwdtsn(asoc, asoc->adv_peer_ack_point,
1874 nskips, &ftsn_skip_arr[0]);
1877 list_add_tail(&ftsn_chunk->list, &q->control_chunk_list);
1878 SCTP_INC_STATS(sock_net(asoc->base.sk), SCTP_MIB_OUTCTRLCHUNKS);