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TOMOYO Linux Cross Reference
Linux/net/sctp/outqueue.c

Version: ~ [ linux-5.5-rc1 ] ~ [ linux-5.4.2 ] ~ [ linux-5.3.15 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.88 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.158 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.206 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.206 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.78 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
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  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.
  6  *
  7  * This file is part of the SCTP kernel implementation
  8  *
  9  * These functions implement the sctp_outq class.   The outqueue handles
 10  * bundling and queueing of outgoing SCTP chunks.
 11  *
 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)
 16  * any later version.
 17  *
 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.
 23  *
 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/>.
 27  *
 28  * Please send any bug reports or fixes you make to the
 29  * email address(es):
 30  *    lksctp developers <linux-sctp@vger.kernel.org>
 31  *
 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>
 40  */
 41 
 42 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 43 
 44 #include <linux/types.h>
 45 #include <linux/list.h>   /* For struct list_head */
 46 #include <linux/socket.h>
 47 #include <linux/ip.h>
 48 #include <linux/slab.h>
 49 #include <net/sock.h>     /* For skb_set_owner_w */
 50 
 51 #include <net/sctp/sctp.h>
 52 #include <net/sctp/sm.h>
 53 
 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);
 62 
 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);
 68 
 69 static void sctp_generate_fwdtsn(struct sctp_outq *q, __u32 sack_ctsn);
 70 
 71 static int sctp_outq_flush(struct sctp_outq *q, int rtx_timeout);
 72 
 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)
 76 {
 77         list_add(&ch->list, &q->out_chunk_list);
 78         q->out_qlen += ch->skb->len;
 79 }
 80 
 81 /* Take data from the front of the queue. */
 82 static inline struct sctp_chunk *sctp_outq_dequeue_data(struct sctp_outq *q)
 83 {
 84         struct sctp_chunk *ch = NULL;
 85 
 86         if (!list_empty(&q->out_chunk_list)) {
 87                 struct list_head *entry = q->out_chunk_list.next;
 88 
 89                 ch = list_entry(entry, struct sctp_chunk, list);
 90                 list_del_init(entry);
 91                 q->out_qlen -= ch->skb->len;
 92         }
 93         return ch;
 94 }
 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)
 98 {
 99         list_add_tail(&ch->list, &q->out_chunk_list);
100         q->out_qlen += ch->skb->len;
101 }
102 
103 /*
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.
108  */
109 static inline int sctp_cacc_skip_3_1_d(struct sctp_transport *primary,
110                                        struct sctp_transport *transport,
111                                        int count_of_newacks)
112 {
113         if (count_of_newacks >= 2 && transport != primary)
114                 return 1;
115         return 0;
116 }
117 
118 /*
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.
124  */
125 static inline int sctp_cacc_skip_3_1_f(struct sctp_transport *transport,
126                                        int count_of_newacks)
127 {
128         if (count_of_newacks < 2 &&
129                         (transport && !transport->cacc.cacc_saw_newack))
130                 return 1;
131         return 0;
132 }
133 
134 /*
135  * SFR-CACC algorithm:
136  * 3.1) If CYCLING_CHANGEOVER is 0, the sender SHOULD
137  * execute steps C, D, F.
138  *
139  * C has been implemented in sctp_outq_sack
140  */
141 static inline int sctp_cacc_skip_3_1(struct sctp_transport *primary,
142                                      struct sctp_transport *transport,
143                                      int count_of_newacks)
144 {
145         if (!primary->cacc.cycling_changeover) {
146                 if (sctp_cacc_skip_3_1_d(primary, transport, count_of_newacks))
147                         return 1;
148                 if (sctp_cacc_skip_3_1_f(transport, count_of_newacks))
149                         return 1;
150                 return 0;
151         }
152         return 0;
153 }
154 
155 /*
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
160  * for t.
161  */
162 static inline int sctp_cacc_skip_3_2(struct sctp_transport *primary, __u32 tsn)
163 {
164         if (primary->cacc.cycling_changeover &&
165             TSN_lt(tsn, primary->cacc.next_tsn_at_change))
166                 return 1;
167         return 0;
168 }
169 
170 /*
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.
178  *
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]).
183  */
184 static inline int sctp_cacc_skip(struct sctp_transport *primary,
185                                  struct sctp_transport *transport,
186                                  int count_of_newacks,
187                                  __u32 tsn)
188 {
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)))
192                 return 1;
193         return 0;
194 }
195 
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...
199  */
200 void sctp_outq_init(struct sctp_association *asoc, struct sctp_outq *q)
201 {
202         memset(q, 0, sizeof(struct sctp_outq));
203 
204         q->asoc = asoc;
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);
210 }
211 
212 /* Free the outqueue structure and any related pending chunks.
213  */
214 static void __sctp_outq_teardown(struct sctp_outq *q)
215 {
216         struct sctp_transport *transport;
217         struct list_head *lchunk, *temp;
218         struct sctp_chunk *chunk, *tmp;
219 
220         /* Throw away unacknowledged chunks. */
221         list_for_each_entry(transport, &q->asoc->peer.transport_addr_list,
222                         transports) {
223                 while ((lchunk = sctp_list_dequeue(&transport->transmitted)) != NULL) {
224                         chunk = list_entry(lchunk, struct sctp_chunk,
225                                            transmitted_list);
226                         /* Mark as part of a failed message. */
227                         sctp_chunk_fail(chunk, q->error);
228                         sctp_chunk_free(chunk);
229                 }
230         }
231 
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,
236                                    transmitted_list);
237                 sctp_chunk_fail(chunk, q->error);
238                 sctp_chunk_free(chunk);
239         }
240 
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,
245                                    transmitted_list);
246                 sctp_chunk_fail(chunk, q->error);
247                 sctp_chunk_free(chunk);
248         }
249 
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,
254                                    transmitted_list);
255                 sctp_chunk_fail(chunk, q->error);
256                 sctp_chunk_free(chunk);
257         }
258 
259         /* Throw away any leftover data chunks. */
260         while ((chunk = sctp_outq_dequeue_data(q)) != NULL) {
261 
262                 /* Mark as send failure. */
263                 sctp_chunk_fail(chunk, q->error);
264                 sctp_chunk_free(chunk);
265         }
266 
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);
271         }
272 }
273 
274 void sctp_outq_teardown(struct sctp_outq *q)
275 {
276         __sctp_outq_teardown(q);
277         sctp_outq_init(q->asoc, q);
278 }
279 
280 /* Free the outqueue structure and any related pending chunks.  */
281 void sctp_outq_free(struct sctp_outq *q)
282 {
283         /* Throw away leftover chunks. */
284         __sctp_outq_teardown(q);
285 }
286 
287 /* Put a new chunk in an sctp_outq.  */
288 int sctp_outq_tail(struct sctp_outq *q, struct sctp_chunk *chunk)
289 {
290         struct net *net = sock_net(q->asoc->base.sk);
291         int error = 0;
292 
293         pr_debug("%s: outq:%p, chunk:%p[%s]\n", __func__, q, chunk,
294                  chunk && chunk->chunk_hdr ?
295                  sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)) :
296                  "illegal chunk");
297 
298         /* If it is data, queue it up, otherwise, send it
299          * immediately.
300          */
301         if (sctp_chunk_is_data(chunk)) {
302                 /* Is it OK to queue data chunks?  */
303                 /* From 9. Termination of Association
304                  *
305                  * When either endpoint performs a shutdown, the
306                  * association on each peer will stop accepting new
307                  * data from its user and only deliver data in queue
308                  * at the time of sending or receiving the SHUTDOWN
309                  * chunk.
310                  */
311                 switch (q->asoc->state) {
312                 case SCTP_STATE_CLOSED:
313                 case SCTP_STATE_SHUTDOWN_PENDING:
314                 case SCTP_STATE_SHUTDOWN_SENT:
315                 case SCTP_STATE_SHUTDOWN_RECEIVED:
316                 case SCTP_STATE_SHUTDOWN_ACK_SENT:
317                         /* Cannot send after transport endpoint shutdown */
318                         error = -ESHUTDOWN;
319                         break;
320 
321                 default:
322                         pr_debug("%s: outqueueing: outq:%p, chunk:%p[%s])\n",
323                                  __func__, q, chunk, chunk && chunk->chunk_hdr ?
324                                  sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)) :
325                                  "illegal chunk");
326 
327                         sctp_outq_tail_data(q, chunk);
328                         if (chunk->chunk_hdr->flags & SCTP_DATA_UNORDERED)
329                                 SCTP_INC_STATS(net, SCTP_MIB_OUTUNORDERCHUNKS);
330                         else
331                                 SCTP_INC_STATS(net, SCTP_MIB_OUTORDERCHUNKS);
332                         break;
333                 }
334         } else {
335                 list_add_tail(&chunk->list, &q->control_chunk_list);
336                 SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
337         }
338 
339         if (error < 0)
340                 return error;
341 
342         if (!q->cork)
343                 error = sctp_outq_flush(q, 0);
344 
345         return error;
346 }
347 
348 /* Insert a chunk into the sorted list based on the TSNs.  The retransmit list
349  * and the abandoned list are in ascending order.
350  */
351 static void sctp_insert_list(struct list_head *head, struct list_head *new)
352 {
353         struct list_head *pos;
354         struct sctp_chunk *nchunk, *lchunk;
355         __u32 ntsn, ltsn;
356         int done = 0;
357 
358         nchunk = list_entry(new, struct sctp_chunk, transmitted_list);
359         ntsn = ntohl(nchunk->subh.data_hdr->tsn);
360 
361         list_for_each(pos, head) {
362                 lchunk = list_entry(pos, struct sctp_chunk, transmitted_list);
363                 ltsn = ntohl(lchunk->subh.data_hdr->tsn);
364                 if (TSN_lt(ntsn, ltsn)) {
365                         list_add(new, pos->prev);
366                         done = 1;
367                         break;
368                 }
369         }
370         if (!done)
371                 list_add_tail(new, head);
372 }
373 
374 /* Mark all the eligible packets on a transport for retransmission.  */
375 void sctp_retransmit_mark(struct sctp_outq *q,
376                           struct sctp_transport *transport,
377                           __u8 reason)
378 {
379         struct list_head *lchunk, *ltemp;
380         struct sctp_chunk *chunk;
381 
382         /* Walk through the specified transmitted queue.  */
383         list_for_each_safe(lchunk, ltemp, &transport->transmitted) {
384                 chunk = list_entry(lchunk, struct sctp_chunk,
385                                    transmitted_list);
386 
387                 /* If the chunk is abandoned, move it to abandoned list. */
388                 if (sctp_chunk_abandoned(chunk)) {
389                         list_del_init(lchunk);
390                         sctp_insert_list(&q->abandoned, lchunk);
391 
392                         /* If this chunk has not been previousely acked,
393                          * stop considering it 'outstanding'.  Our peer
394                          * will most likely never see it since it will
395                          * not be retransmitted
396                          */
397                         if (!chunk->tsn_gap_acked) {
398                                 if (chunk->transport)
399                                         chunk->transport->flight_size -=
400                                                         sctp_data_size(chunk);
401                                 q->outstanding_bytes -= sctp_data_size(chunk);
402                                 q->asoc->peer.rwnd += sctp_data_size(chunk);
403                         }
404                         continue;
405                 }
406 
407                 /* If we are doing  retransmission due to a timeout or pmtu
408                  * discovery, only the  chunks that are not yet acked should
409                  * be added to the retransmit queue.
410                  */
411                 if ((reason == SCTP_RTXR_FAST_RTX  &&
412                             (chunk->fast_retransmit == SCTP_NEED_FRTX)) ||
413                     (reason != SCTP_RTXR_FAST_RTX  && !chunk->tsn_gap_acked)) {
414                         /* RFC 2960 6.2.1 Processing a Received SACK
415                          *
416                          * C) Any time a DATA chunk is marked for
417                          * retransmission (via either T3-rtx timer expiration
418                          * (Section 6.3.3) or via fast retransmit
419                          * (Section 7.2.4)), add the data size of those
420                          * chunks to the rwnd.
421                          */
422                         q->asoc->peer.rwnd += sctp_data_size(chunk);
423                         q->outstanding_bytes -= sctp_data_size(chunk);
424                         if (chunk->transport)
425                                 transport->flight_size -= sctp_data_size(chunk);
426 
427                         /* sctpimpguide-05 Section 2.8.2
428                          * M5) If a T3-rtx timer expires, the
429                          * 'TSN.Missing.Report' of all affected TSNs is set
430                          * to 0.
431                          */
432                         chunk->tsn_missing_report = 0;
433 
434                         /* If a chunk that is being used for RTT measurement
435                          * has to be retransmitted, we cannot use this chunk
436                          * anymore for RTT measurements. Reset rto_pending so
437                          * that a new RTT measurement is started when a new
438                          * data chunk is sent.
439                          */
440                         if (chunk->rtt_in_progress) {
441                                 chunk->rtt_in_progress = 0;
442                                 transport->rto_pending = 0;
443                         }
444 
445                         chunk->resent = 1;
446 
447                         /* Move the chunk to the retransmit queue. The chunks
448                          * on the retransmit queue are always kept in order.
449                          */
450                         list_del_init(lchunk);
451                         sctp_insert_list(&q->retransmit, lchunk);
452                 }
453         }
454 
455         pr_debug("%s: transport:%p, reason:%d, cwnd:%d, ssthresh:%d, "
456                  "flight_size:%d, pba:%d\n", __func__, transport, reason,
457                  transport->cwnd, transport->ssthresh, transport->flight_size,
458                  transport->partial_bytes_acked);
459 }
460 
461 /* Mark all the eligible packets on a transport for retransmission and force
462  * one packet out.
463  */
464 void sctp_retransmit(struct sctp_outq *q, struct sctp_transport *transport,
465                      sctp_retransmit_reason_t reason)
466 {
467         struct net *net = sock_net(q->asoc->base.sk);
468         int error = 0;
469 
470         switch (reason) {
471         case SCTP_RTXR_T3_RTX:
472                 SCTP_INC_STATS(net, SCTP_MIB_T3_RETRANSMITS);
473                 sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_T3_RTX);
474                 /* Update the retran path if the T3-rtx timer has expired for
475                  * the current retran path.
476                  */
477                 if (transport == transport->asoc->peer.retran_path)
478                         sctp_assoc_update_retran_path(transport->asoc);
479                 transport->asoc->rtx_data_chunks +=
480                         transport->asoc->unack_data;
481                 break;
482         case SCTP_RTXR_FAST_RTX:
483                 SCTP_INC_STATS(net, SCTP_MIB_FAST_RETRANSMITS);
484                 sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_FAST_RTX);
485                 q->fast_rtx = 1;
486                 break;
487         case SCTP_RTXR_PMTUD:
488                 SCTP_INC_STATS(net, SCTP_MIB_PMTUD_RETRANSMITS);
489                 break;
490         case SCTP_RTXR_T1_RTX:
491                 SCTP_INC_STATS(net, SCTP_MIB_T1_RETRANSMITS);
492                 transport->asoc->init_retries++;
493                 break;
494         default:
495                 BUG();
496         }
497 
498         sctp_retransmit_mark(q, transport, reason);
499 
500         /* PR-SCTP A5) Any time the T3-rtx timer expires, on any destination,
501          * the sender SHOULD try to advance the "Advanced.Peer.Ack.Point" by
502          * following the procedures outlined in C1 - C5.
503          */
504         if (reason == SCTP_RTXR_T3_RTX)
505                 sctp_generate_fwdtsn(q, q->asoc->ctsn_ack_point);
506 
507         /* Flush the queues only on timeout, since fast_rtx is only
508          * triggered during sack processing and the queue
509          * will be flushed at the end.
510          */
511         if (reason != SCTP_RTXR_FAST_RTX)
512                 error = sctp_outq_flush(q, /* rtx_timeout */ 1);
513 
514         if (error)
515                 q->asoc->base.sk->sk_err = -error;
516 }
517 
518 /*
519  * Transmit DATA chunks on the retransmit queue.  Upon return from
520  * sctp_outq_flush_rtx() the packet 'pkt' may contain chunks which
521  * need to be transmitted by the caller.
522  * We assume that pkt->transport has already been set.
523  *
524  * The return value is a normal kernel error return value.
525  */
526 static int sctp_outq_flush_rtx(struct sctp_outq *q, struct sctp_packet *pkt,
527                                int rtx_timeout, int *start_timer)
528 {
529         struct list_head *lqueue;
530         struct sctp_transport *transport = pkt->transport;
531         sctp_xmit_t status;
532         struct sctp_chunk *chunk, *chunk1;
533         int fast_rtx;
534         int error = 0;
535         int timer = 0;
536         int done = 0;
537 
538         lqueue = &q->retransmit;
539         fast_rtx = q->fast_rtx;
540 
541         /* This loop handles time-out retransmissions, fast retransmissions,
542          * and retransmissions due to opening of whindow.
543          *
544          * RFC 2960 6.3.3 Handle T3-rtx Expiration
545          *
546          * E3) Determine how many of the earliest (i.e., lowest TSN)
547          * outstanding DATA chunks for the address for which the
548          * T3-rtx has expired will fit into a single packet, subject
549          * to the MTU constraint for the path corresponding to the
550          * destination transport address to which the retransmission
551          * is being sent (this may be different from the address for
552          * which the timer expires [see Section 6.4]). Call this value
553          * K. Bundle and retransmit those K DATA chunks in a single
554          * packet to the destination endpoint.
555          *
556          * [Just to be painfully clear, if we are retransmitting
557          * because a timeout just happened, we should send only ONE
558          * packet of retransmitted data.]
559          *
560          * For fast retransmissions we also send only ONE packet.  However,
561          * if we are just flushing the queue due to open window, we'll
562          * try to send as much as possible.
563          */
564         list_for_each_entry_safe(chunk, chunk1, lqueue, transmitted_list) {
565                 /* If the chunk is abandoned, move it to abandoned list. */
566                 if (sctp_chunk_abandoned(chunk)) {
567                         list_del_init(&chunk->transmitted_list);
568                         sctp_insert_list(&q->abandoned,
569                                          &chunk->transmitted_list);
570                         continue;
571                 }
572 
573                 /* Make sure that Gap Acked TSNs are not retransmitted.  A
574                  * simple approach is just to move such TSNs out of the
575                  * way and into a 'transmitted' queue and skip to the
576                  * next chunk.
577                  */
578                 if (chunk->tsn_gap_acked) {
579                         list_move_tail(&chunk->transmitted_list,
580                                        &transport->transmitted);
581                         continue;
582                 }
583 
584                 /* If we are doing fast retransmit, ignore non-fast_rtransmit
585                  * chunks
586                  */
587                 if (fast_rtx && !chunk->fast_retransmit)
588                         continue;
589 
590 redo:
591                 /* Attempt to append this chunk to the packet. */
592                 status = sctp_packet_append_chunk(pkt, chunk);
593 
594                 switch (status) {
595                 case SCTP_XMIT_PMTU_FULL:
596                         if (!pkt->has_data && !pkt->has_cookie_echo) {
597                                 /* If this packet did not contain DATA then
598                                  * retransmission did not happen, so do it
599                                  * again.  We'll ignore the error here since
600                                  * control chunks are already freed so there
601                                  * is nothing we can do.
602                                  */
603                                 sctp_packet_transmit(pkt);
604                                 goto redo;
605                         }
606 
607                         /* Send this packet.  */
608                         error = sctp_packet_transmit(pkt);
609 
610                         /* If we are retransmitting, we should only
611                          * send a single packet.
612                          * Otherwise, try appending this chunk again.
613                          */
614                         if (rtx_timeout || fast_rtx)
615                                 done = 1;
616                         else
617                                 goto redo;
618 
619                         /* Bundle next chunk in the next round.  */
620                         break;
621 
622                 case SCTP_XMIT_RWND_FULL:
623                         /* Send this packet. */
624                         error = sctp_packet_transmit(pkt);
625 
626                         /* Stop sending DATA as there is no more room
627                          * at the receiver.
628                          */
629                         done = 1;
630                         break;
631 
632                 case SCTP_XMIT_DELAY:
633                         /* Send this packet. */
634                         error = sctp_packet_transmit(pkt);
635 
636                         /* Stop sending DATA because of nagle delay. */
637                         done = 1;
638                         break;
639 
640                 default:
641                         /* The append was successful, so add this chunk to
642                          * the transmitted list.
643                          */
644                         list_move_tail(&chunk->transmitted_list,
645                                        &transport->transmitted);
646 
647                         /* Mark the chunk as ineligible for fast retransmit
648                          * after it is retransmitted.
649                          */
650                         if (chunk->fast_retransmit == SCTP_NEED_FRTX)
651                                 chunk->fast_retransmit = SCTP_DONT_FRTX;
652 
653                         q->asoc->stats.rtxchunks++;
654                         break;
655                 }
656 
657                 /* Set the timer if there were no errors */
658                 if (!error && !timer)
659                         timer = 1;
660 
661                 if (done)
662                         break;
663         }
664 
665         /* If we are here due to a retransmit timeout or a fast
666          * retransmit and if there are any chunks left in the retransmit
667          * queue that could not fit in the PMTU sized packet, they need
668          * to be marked as ineligible for a subsequent fast retransmit.
669          */
670         if (rtx_timeout || fast_rtx) {
671                 list_for_each_entry(chunk1, lqueue, transmitted_list) {
672                         if (chunk1->fast_retransmit == SCTP_NEED_FRTX)
673                                 chunk1->fast_retransmit = SCTP_DONT_FRTX;
674                 }
675         }
676 
677         *start_timer = timer;
678 
679         /* Clear fast retransmit hint */
680         if (fast_rtx)
681                 q->fast_rtx = 0;
682 
683         return error;
684 }
685 
686 /* Cork the outqueue so queued chunks are really queued. */
687 int sctp_outq_uncork(struct sctp_outq *q)
688 {
689         if (q->cork)
690                 q->cork = 0;
691 
692         return sctp_outq_flush(q, 0);
693 }
694 
695 
696 /*
697  * Try to flush an outqueue.
698  *
699  * Description: Send everything in q which we legally can, subject to
700  * congestion limitations.
701  * * Note: This function can be called from multiple contexts so appropriate
702  * locking concerns must be made.  Today we use the sock lock to protect
703  * this function.
704  */
705 static int sctp_outq_flush(struct sctp_outq *q, int rtx_timeout)
706 {
707         struct sctp_packet *packet;
708         struct sctp_packet singleton;
709         struct sctp_association *asoc = q->asoc;
710         __u16 sport = asoc->base.bind_addr.port;
711         __u16 dport = asoc->peer.port;
712         __u32 vtag = asoc->peer.i.init_tag;
713         struct sctp_transport *transport = NULL;
714         struct sctp_transport *new_transport;
715         struct sctp_chunk *chunk, *tmp;
716         sctp_xmit_t status;
717         int error = 0;
718         int start_timer = 0;
719         int one_packet = 0;
720 
721         /* These transports have chunks to send. */
722         struct list_head transport_list;
723         struct list_head *ltransport;
724 
725         INIT_LIST_HEAD(&transport_list);
726         packet = NULL;
727 
728         /*
729          * 6.10 Bundling
730          *   ...
731          *   When bundling control chunks with DATA chunks, an
732          *   endpoint MUST place control chunks first in the outbound
733          *   SCTP packet.  The transmitter MUST transmit DATA chunks
734          *   within a SCTP packet in increasing order of TSN.
735          *   ...
736          */
737 
738         list_for_each_entry_safe(chunk, tmp, &q->control_chunk_list, list) {
739                 /* RFC 5061, 5.3
740                  * F1) This means that until such time as the ASCONF
741                  * containing the add is acknowledged, the sender MUST
742                  * NOT use the new IP address as a source for ANY SCTP
743                  * packet except on carrying an ASCONF Chunk.
744                  */
745                 if (asoc->src_out_of_asoc_ok &&
746                     chunk->chunk_hdr->type != SCTP_CID_ASCONF)
747                         continue;
748 
749                 list_del_init(&chunk->list);
750 
751                 /* Pick the right transport to use. */
752                 new_transport = chunk->transport;
753 
754                 if (!new_transport) {
755                         /*
756                          * If we have a prior transport pointer, see if
757                          * the destination address of the chunk
758                          * matches the destination address of the
759                          * current transport.  If not a match, then
760                          * try to look up the transport with a given
761                          * destination address.  We do this because
762                          * after processing ASCONFs, we may have new
763                          * transports created.
764                          */
765                         if (transport &&
766                             sctp_cmp_addr_exact(&chunk->dest,
767                                                 &transport->ipaddr))
768                                         new_transport = transport;
769                         else
770                                 new_transport = sctp_assoc_lookup_paddr(asoc,
771                                                                 &chunk->dest);
772 
773                         /* if we still don't have a new transport, then
774                          * use the current active path.
775                          */
776                         if (!new_transport)
777                                 new_transport = asoc->peer.active_path;
778                 } else if ((new_transport->state == SCTP_INACTIVE) ||
779                            (new_transport->state == SCTP_UNCONFIRMED) ||
780                            (new_transport->state == SCTP_PF)) {
781                         /* If the chunk is Heartbeat or Heartbeat Ack,
782                          * send it to chunk->transport, even if it's
783                          * inactive.
784                          *
785                          * 3.3.6 Heartbeat Acknowledgement:
786                          * ...
787                          * A HEARTBEAT ACK is always sent to the source IP
788                          * address of the IP datagram containing the
789                          * HEARTBEAT chunk to which this ack is responding.
790                          * ...
791                          *
792                          * ASCONF_ACKs also must be sent to the source.
793                          */
794                         if (chunk->chunk_hdr->type != SCTP_CID_HEARTBEAT &&
795                             chunk->chunk_hdr->type != SCTP_CID_HEARTBEAT_ACK &&
796                             chunk->chunk_hdr->type != SCTP_CID_ASCONF_ACK)
797                                 new_transport = asoc->peer.active_path;
798                 }
799 
800                 /* Are we switching transports?
801                  * Take care of transport locks.
802                  */
803                 if (new_transport != transport) {
804                         transport = new_transport;
805                         if (list_empty(&transport->send_ready)) {
806                                 list_add_tail(&transport->send_ready,
807                                               &transport_list);
808                         }
809                         packet = &transport->packet;
810                         sctp_packet_config(packet, vtag,
811                                            asoc->peer.ecn_capable);
812                 }
813 
814                 switch (chunk->chunk_hdr->type) {
815                 /*
816                  * 6.10 Bundling
817                  *   ...
818                  *   An endpoint MUST NOT bundle INIT, INIT ACK or SHUTDOWN
819                  *   COMPLETE with any other chunks.  [Send them immediately.]
820                  */
821                 case SCTP_CID_INIT:
822                 case SCTP_CID_INIT_ACK:
823                 case SCTP_CID_SHUTDOWN_COMPLETE:
824                         sctp_packet_init(&singleton, transport, sport, dport);
825                         sctp_packet_config(&singleton, vtag, 0);
826                         sctp_packet_append_chunk(&singleton, chunk);
827                         error = sctp_packet_transmit(&singleton);
828                         if (error < 0)
829                                 return error;
830                         break;
831 
832                 case SCTP_CID_ABORT:
833                         if (sctp_test_T_bit(chunk)) {
834                                 packet->vtag = asoc->c.my_vtag;
835                         }
836                 /* The following chunks are "response" chunks, i.e.
837                  * they are generated in response to something we
838                  * received.  If we are sending these, then we can
839                  * send only 1 packet containing these chunks.
840                  */
841                 case SCTP_CID_HEARTBEAT_ACK:
842                 case SCTP_CID_SHUTDOWN_ACK:
843                 case SCTP_CID_COOKIE_ACK:
844                 case SCTP_CID_COOKIE_ECHO:
845                 case SCTP_CID_ERROR:
846                 case SCTP_CID_ECN_CWR:
847                 case SCTP_CID_ASCONF_ACK:
848                         one_packet = 1;
849                         /* Fall through */
850 
851                 case SCTP_CID_SACK:
852                 case SCTP_CID_HEARTBEAT:
853                 case SCTP_CID_SHUTDOWN:
854                 case SCTP_CID_ECN_ECNE:
855                 case SCTP_CID_ASCONF:
856                 case SCTP_CID_FWD_TSN:
857                         status = sctp_packet_transmit_chunk(packet, chunk,
858                                                             one_packet);
859                         if (status  != SCTP_XMIT_OK) {
860                                 /* put the chunk back */
861                                 list_add(&chunk->list, &q->control_chunk_list);
862                         } else {
863                                 asoc->stats.octrlchunks++;
864                                 /* PR-SCTP C5) If a FORWARD TSN is sent, the
865                                  * sender MUST assure that at least one T3-rtx
866                                  * timer is running.
867                                  */
868                                 if (chunk->chunk_hdr->type == SCTP_CID_FWD_TSN)
869                                         sctp_transport_reset_timers(transport);
870                         }
871                         break;
872 
873                 default:
874                         /* We built a chunk with an illegal type! */
875                         BUG();
876                 }
877         }
878 
879         if (q->asoc->src_out_of_asoc_ok)
880                 goto sctp_flush_out;
881 
882         /* Is it OK to send data chunks?  */
883         switch (asoc->state) {
884         case SCTP_STATE_COOKIE_ECHOED:
885                 /* Only allow bundling when this packet has a COOKIE-ECHO
886                  * chunk.
887                  */
888                 if (!packet || !packet->has_cookie_echo)
889                         break;
890 
891                 /* fallthru */
892         case SCTP_STATE_ESTABLISHED:
893         case SCTP_STATE_SHUTDOWN_PENDING:
894         case SCTP_STATE_SHUTDOWN_RECEIVED:
895                 /*
896                  * RFC 2960 6.1  Transmission of DATA Chunks
897                  *
898                  * C) When the time comes for the sender to transmit,
899                  * before sending new DATA chunks, the sender MUST
900                  * first transmit any outstanding DATA chunks which
901                  * are marked for retransmission (limited by the
902                  * current cwnd).
903                  */
904                 if (!list_empty(&q->retransmit)) {
905                         if (asoc->peer.retran_path->state == SCTP_UNCONFIRMED)
906                                 goto sctp_flush_out;
907                         if (transport == asoc->peer.retran_path)
908                                 goto retran;
909 
910                         /* Switch transports & prepare the packet.  */
911 
912                         transport = asoc->peer.retran_path;
913 
914                         if (list_empty(&transport->send_ready)) {
915                                 list_add_tail(&transport->send_ready,
916                                               &transport_list);
917                         }
918 
919                         packet = &transport->packet;
920                         sctp_packet_config(packet, vtag,
921                                            asoc->peer.ecn_capable);
922                 retran:
923                         error = sctp_outq_flush_rtx(q, packet,
924                                                     rtx_timeout, &start_timer);
925 
926                         if (start_timer)
927                                 sctp_transport_reset_timers(transport);
928 
929                         /* This can happen on COOKIE-ECHO resend.  Only
930                          * one chunk can get bundled with a COOKIE-ECHO.
931                          */
932                         if (packet->has_cookie_echo)
933                                 goto sctp_flush_out;
934 
935                         /* Don't send new data if there is still data
936                          * waiting to retransmit.
937                          */
938                         if (!list_empty(&q->retransmit))
939                                 goto sctp_flush_out;
940                 }
941 
942                 /* Apply Max.Burst limitation to the current transport in
943                  * case it will be used for new data.  We are going to
944                  * rest it before we return, but we want to apply the limit
945                  * to the currently queued data.
946                  */
947                 if (transport)
948                         sctp_transport_burst_limited(transport);
949 
950                 /* Finally, transmit new packets.  */
951                 while ((chunk = sctp_outq_dequeue_data(q)) != NULL) {
952                         /* RFC 2960 6.5 Every DATA chunk MUST carry a valid
953                          * stream identifier.
954                          */
955                         if (chunk->sinfo.sinfo_stream >=
956                             asoc->c.sinit_num_ostreams) {
957 
958                                 /* Mark as failed send. */
959                                 sctp_chunk_fail(chunk, SCTP_ERROR_INV_STRM);
960                                 sctp_chunk_free(chunk);
961                                 continue;
962                         }
963 
964                         /* Has this chunk expired? */
965                         if (sctp_chunk_abandoned(chunk)) {
966                                 sctp_chunk_fail(chunk, 0);
967                                 sctp_chunk_free(chunk);
968                                 continue;
969                         }
970 
971                         /* If there is a specified transport, use it.
972                          * Otherwise, we want to use the active path.
973                          */
974                         new_transport = chunk->transport;
975                         if (!new_transport ||
976                             ((new_transport->state == SCTP_INACTIVE) ||
977                              (new_transport->state == SCTP_UNCONFIRMED) ||
978                              (new_transport->state == SCTP_PF)))
979                                 new_transport = asoc->peer.active_path;
980                         if (new_transport->state == SCTP_UNCONFIRMED)
981                                 continue;
982 
983                         /* Change packets if necessary.  */
984                         if (new_transport != transport) {
985                                 transport = new_transport;
986 
987                                 /* Schedule to have this transport's
988                                  * packet flushed.
989                                  */
990                                 if (list_empty(&transport->send_ready)) {
991                                         list_add_tail(&transport->send_ready,
992                                                       &transport_list);
993                                 }
994 
995                                 packet = &transport->packet;
996                                 sctp_packet_config(packet, vtag,
997                                                    asoc->peer.ecn_capable);
998                                 /* We've switched transports, so apply the
999                                  * Burst limit to the new transport.
1000                                  */
1001                                 sctp_transport_burst_limited(transport);
1002                         }
1003 
1004                         pr_debug("%s: outq:%p, chunk:%p[%s], tx-tsn:0x%x skb->head:%p "
1005                                  "skb->users:%d\n",
1006                                  __func__, q, chunk, chunk && chunk->chunk_hdr ?
1007                                  sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)) :
1008                                  "illegal chunk", ntohl(chunk->subh.data_hdr->tsn),
1009                                  chunk->skb ? chunk->skb->head : NULL, chunk->skb ?
1010                                  atomic_read(&chunk->skb->users) : -1);
1011 
1012                         /* Add the chunk to the packet.  */
1013                         status = sctp_packet_transmit_chunk(packet, chunk, 0);
1014 
1015                         switch (status) {
1016                         case SCTP_XMIT_PMTU_FULL:
1017                         case SCTP_XMIT_RWND_FULL:
1018                         case SCTP_XMIT_DELAY:
1019                                 /* We could not append this chunk, so put
1020                                  * the chunk back on the output queue.
1021                                  */
1022                                 pr_debug("%s: could not transmit tsn:0x%x, status:%d\n",
1023                                          __func__, ntohl(chunk->subh.data_hdr->tsn),
1024                                          status);
1025 
1026                                 sctp_outq_head_data(q, chunk);
1027                                 goto sctp_flush_out;
1028 
1029                         case SCTP_XMIT_OK:
1030                                 /* The sender is in the SHUTDOWN-PENDING state,
1031                                  * The sender MAY set the I-bit in the DATA
1032                                  * chunk header.
1033                                  */
1034                                 if (asoc->state == SCTP_STATE_SHUTDOWN_PENDING)
1035                                         chunk->chunk_hdr->flags |= SCTP_DATA_SACK_IMM;
1036                                 if (chunk->chunk_hdr->flags & SCTP_DATA_UNORDERED)
1037                                         asoc->stats.ouodchunks++;
1038                                 else
1039                                         asoc->stats.oodchunks++;
1040 
1041                                 break;
1042 
1043                         default:
1044                                 BUG();
1045                         }
1046 
1047                         /* BUG: We assume that the sctp_packet_transmit()
1048                          * call below will succeed all the time and add the
1049                          * chunk to the transmitted list and restart the
1050                          * timers.
1051                          * It is possible that the call can fail under OOM
1052                          * conditions.
1053                          *
1054                          * Is this really a problem?  Won't this behave
1055                          * like a lost TSN?
1056                          */
1057                         list_add_tail(&chunk->transmitted_list,
1058                                       &transport->transmitted);
1059 
1060                         sctp_transport_reset_timers(transport);
1061 
1062                         /* Only let one DATA chunk get bundled with a
1063                          * COOKIE-ECHO chunk.
1064                          */
1065                         if (packet->has_cookie_echo)
1066                                 goto sctp_flush_out;
1067                 }
1068                 break;
1069 
1070         default:
1071                 /* Do nothing.  */
1072                 break;
1073         }
1074 
1075 sctp_flush_out:
1076 
1077         /* Before returning, examine all the transports touched in
1078          * this call.  Right now, we bluntly force clear all the
1079          * transports.  Things might change after we implement Nagle.
1080          * But such an examination is still required.
1081          *
1082          * --xguo
1083          */
1084         while ((ltransport = sctp_list_dequeue(&transport_list)) != NULL) {
1085                 struct sctp_transport *t = list_entry(ltransport,
1086                                                       struct sctp_transport,
1087                                                       send_ready);
1088                 packet = &t->packet;
1089                 if (!sctp_packet_empty(packet))
1090                         error = sctp_packet_transmit(packet);
1091 
1092                 /* Clear the burst limited state, if any */
1093                 sctp_transport_burst_reset(t);
1094         }
1095 
1096         return error;
1097 }
1098 
1099 /* Update unack_data based on the incoming SACK chunk */
1100 static void sctp_sack_update_unack_data(struct sctp_association *assoc,
1101                                         struct sctp_sackhdr *sack)
1102 {
1103         sctp_sack_variable_t *frags;
1104         __u16 unack_data;
1105         int i;
1106 
1107         unack_data = assoc->next_tsn - assoc->ctsn_ack_point - 1;
1108 
1109         frags = sack->variable;
1110         for (i = 0; i < ntohs(sack->num_gap_ack_blocks); i++) {
1111                 unack_data -= ((ntohs(frags[i].gab.end) -
1112                                 ntohs(frags[i].gab.start) + 1));
1113         }
1114 
1115         assoc->unack_data = unack_data;
1116 }
1117 
1118 /* This is where we REALLY process a SACK.
1119  *
1120  * Process the SACK against the outqueue.  Mostly, this just frees
1121  * things off the transmitted queue.
1122  */
1123 int sctp_outq_sack(struct sctp_outq *q, struct sctp_chunk *chunk)
1124 {
1125         struct sctp_association *asoc = q->asoc;
1126         struct sctp_sackhdr *sack = chunk->subh.sack_hdr;
1127         struct sctp_transport *transport;
1128         struct sctp_chunk *tchunk = NULL;
1129         struct list_head *lchunk, *transport_list, *temp;
1130         sctp_sack_variable_t *frags = sack->variable;
1131         __u32 sack_ctsn, ctsn, tsn;
1132         __u32 highest_tsn, highest_new_tsn;
1133         __u32 sack_a_rwnd;
1134         unsigned int outstanding;
1135         struct sctp_transport *primary = asoc->peer.primary_path;
1136         int count_of_newacks = 0;
1137         int gap_ack_blocks;
1138         u8 accum_moved = 0;
1139 
1140         /* Grab the association's destination address list. */
1141         transport_list = &asoc->peer.transport_addr_list;
1142 
1143         sack_ctsn = ntohl(sack->cum_tsn_ack);
1144         gap_ack_blocks = ntohs(sack->num_gap_ack_blocks);
1145         asoc->stats.gapcnt += gap_ack_blocks;
1146         /*
1147          * SFR-CACC algorithm:
1148          * On receipt of a SACK the sender SHOULD execute the
1149          * following statements.
1150          *
1151          * 1) If the cumulative ack in the SACK passes next tsn_at_change
1152          * on the current primary, the CHANGEOVER_ACTIVE flag SHOULD be
1153          * cleared. The CYCLING_CHANGEOVER flag SHOULD also be cleared for
1154          * all destinations.
1155          * 2) If the SACK contains gap acks and the flag CHANGEOVER_ACTIVE
1156          * is set the receiver of the SACK MUST take the following actions:
1157          *
1158          * A) Initialize the cacc_saw_newack to 0 for all destination
1159          * addresses.
1160          *
1161          * Only bother if changeover_active is set. Otherwise, this is
1162          * totally suboptimal to do on every SACK.
1163          */
1164         if (primary->cacc.changeover_active) {
1165                 u8 clear_cycling = 0;
1166 
1167                 if (TSN_lte(primary->cacc.next_tsn_at_change, sack_ctsn)) {
1168                         primary->cacc.changeover_active = 0;
1169                         clear_cycling = 1;
1170                 }
1171 
1172                 if (clear_cycling || gap_ack_blocks) {
1173                         list_for_each_entry(transport, transport_list,
1174                                         transports) {
1175                                 if (clear_cycling)
1176                                         transport->cacc.cycling_changeover = 0;
1177                                 if (gap_ack_blocks)
1178                                         transport->cacc.cacc_saw_newack = 0;
1179                         }
1180                 }
1181         }
1182 
1183         /* Get the highest TSN in the sack. */
1184         highest_tsn = sack_ctsn;
1185         if (gap_ack_blocks)
1186                 highest_tsn += ntohs(frags[gap_ack_blocks - 1].gab.end);
1187 
1188         if (TSN_lt(asoc->highest_sacked, highest_tsn))
1189                 asoc->highest_sacked = highest_tsn;
1190 
1191         highest_new_tsn = sack_ctsn;
1192 
1193         /* Run through the retransmit queue.  Credit bytes received
1194          * and free those chunks that we can.
1195          */
1196         sctp_check_transmitted(q, &q->retransmit, NULL, NULL, sack, &highest_new_tsn);
1197 
1198         /* Run through the transmitted queue.
1199          * Credit bytes received and free those chunks which we can.
1200          *
1201          * This is a MASSIVE candidate for optimization.
1202          */
1203         list_for_each_entry(transport, transport_list, transports) {
1204                 sctp_check_transmitted(q, &transport->transmitted,
1205                                        transport, &chunk->source, sack,
1206                                        &highest_new_tsn);
1207                 /*
1208                  * SFR-CACC algorithm:
1209                  * C) Let count_of_newacks be the number of
1210                  * destinations for which cacc_saw_newack is set.
1211                  */
1212                 if (transport->cacc.cacc_saw_newack)
1213                         count_of_newacks++;
1214         }
1215 
1216         /* Move the Cumulative TSN Ack Point if appropriate.  */
1217         if (TSN_lt(asoc->ctsn_ack_point, sack_ctsn)) {
1218                 asoc->ctsn_ack_point = sack_ctsn;
1219                 accum_moved = 1;
1220         }
1221 
1222         if (gap_ack_blocks) {
1223 
1224                 if (asoc->fast_recovery && accum_moved)
1225                         highest_new_tsn = highest_tsn;
1226 
1227                 list_for_each_entry(transport, transport_list, transports)
1228                         sctp_mark_missing(q, &transport->transmitted, transport,
1229                                           highest_new_tsn, count_of_newacks);
1230         }
1231 
1232         /* Update unack_data field in the assoc. */
1233         sctp_sack_update_unack_data(asoc, sack);
1234 
1235         ctsn = asoc->ctsn_ack_point;
1236 
1237         /* Throw away stuff rotting on the sack queue.  */
1238         list_for_each_safe(lchunk, temp, &q->sacked) {
1239                 tchunk = list_entry(lchunk, struct sctp_chunk,
1240                                     transmitted_list);
1241                 tsn = ntohl(tchunk->subh.data_hdr->tsn);
1242                 if (TSN_lte(tsn, ctsn)) {
1243                         list_del_init(&tchunk->transmitted_list);
1244                         sctp_chunk_free(tchunk);
1245                 }
1246         }
1247 
1248         /* ii) Set rwnd equal to the newly received a_rwnd minus the
1249          *     number of bytes still outstanding after processing the
1250          *     Cumulative TSN Ack and the Gap Ack Blocks.
1251          */
1252 
1253         sack_a_rwnd = ntohl(sack->a_rwnd);
1254         outstanding = q->outstanding_bytes;
1255 
1256         if (outstanding < sack_a_rwnd)
1257                 sack_a_rwnd -= outstanding;
1258         else
1259                 sack_a_rwnd = 0;
1260 
1261         asoc->peer.rwnd = sack_a_rwnd;
1262 
1263         sctp_generate_fwdtsn(q, sack_ctsn);
1264 
1265         pr_debug("%s: sack cumulative tsn ack:0x%x\n", __func__, sack_ctsn);
1266         pr_debug("%s: cumulative tsn ack of assoc:%p is 0x%x, "
1267                  "advertised peer ack point:0x%x\n", __func__, asoc, ctsn,
1268                  asoc->adv_peer_ack_point);
1269 
1270         return sctp_outq_is_empty(q);
1271 }
1272 
1273 /* Is the outqueue empty?
1274  * The queue is empty when we have not pending data, no in-flight data
1275  * and nothing pending retransmissions.
1276  */
1277 int sctp_outq_is_empty(const struct sctp_outq *q)
1278 {
1279         return q->out_qlen == 0 && q->outstanding_bytes == 0 &&
1280                list_empty(&q->retransmit);
1281 }
1282 
1283 /********************************************************************
1284  * 2nd Level Abstractions
1285  ********************************************************************/
1286 
1287 /* Go through a transport's transmitted list or the association's retransmit
1288  * list and move chunks that are acked by the Cumulative TSN Ack to q->sacked.
1289  * The retransmit list will not have an associated transport.
1290  *
1291  * I added coherent debug information output.   --xguo
1292  *
1293  * Instead of printing 'sacked' or 'kept' for each TSN on the
1294  * transmitted_queue, we print a range: SACKED: TSN1-TSN2, TSN3, TSN4-TSN5.
1295  * KEPT TSN6-TSN7, etc.
1296  */
1297 static void sctp_check_transmitted(struct sctp_outq *q,
1298                                    struct list_head *transmitted_queue,
1299                                    struct sctp_transport *transport,
1300                                    union sctp_addr *saddr,
1301                                    struct sctp_sackhdr *sack,
1302                                    __u32 *highest_new_tsn_in_sack)
1303 {
1304         struct list_head *lchunk;
1305         struct sctp_chunk *tchunk;
1306         struct list_head tlist;
1307         __u32 tsn;
1308         __u32 sack_ctsn;
1309         __u32 rtt;
1310         __u8 restart_timer = 0;
1311         int bytes_acked = 0;
1312         int migrate_bytes = 0;
1313         bool forward_progress = false;
1314 
1315         sack_ctsn = ntohl(sack->cum_tsn_ack);
1316 
1317         INIT_LIST_HEAD(&tlist);
1318 
1319         /* The while loop will skip empty transmitted queues. */
1320         while (NULL != (lchunk = sctp_list_dequeue(transmitted_queue))) {
1321                 tchunk = list_entry(lchunk, struct sctp_chunk,
1322                                     transmitted_list);
1323 
1324                 if (sctp_chunk_abandoned(tchunk)) {
1325                         /* Move the chunk to abandoned list. */
1326                         sctp_insert_list(&q->abandoned, lchunk);
1327 
1328                         /* If this chunk has not been acked, stop
1329                          * considering it as 'outstanding'.
1330                          */
1331                         if (!tchunk->tsn_gap_acked) {
1332                                 if (tchunk->transport)
1333                                         tchunk->transport->flight_size -=
1334                                                         sctp_data_size(tchunk);
1335                                 q->outstanding_bytes -= sctp_data_size(tchunk);
1336                         }
1337                         continue;
1338                 }
1339 
1340                 tsn = ntohl(tchunk->subh.data_hdr->tsn);
1341                 if (sctp_acked(sack, tsn)) {
1342                         /* If this queue is the retransmit queue, the
1343                          * retransmit timer has already reclaimed
1344                          * the outstanding bytes for this chunk, so only
1345                          * count bytes associated with a transport.
1346                          */
1347                         if (transport) {
1348                                 /* If this chunk is being used for RTT
1349                                  * measurement, calculate the RTT and update
1350                                  * the RTO using this value.
1351                                  *
1352                                  * 6.3.1 C5) Karn's algorithm: RTT measurements
1353                                  * MUST NOT be made using packets that were
1354                                  * retransmitted (and thus for which it is
1355                                  * ambiguous whether the reply was for the
1356                                  * first instance of the packet or a later
1357                                  * instance).
1358                                  */
1359                                 if (!tchunk->tsn_gap_acked &&
1360                                     !tchunk->resent &&
1361                                     tchunk->rtt_in_progress) {
1362                                         tchunk->rtt_in_progress = 0;
1363                                         rtt = jiffies - tchunk->sent_at;
1364                                         sctp_transport_update_rto(transport,
1365                                                                   rtt);
1366                                 }
1367                         }
1368 
1369                         /* If the chunk hasn't been marked as ACKED,
1370                          * mark it and account bytes_acked if the
1371                          * chunk had a valid transport (it will not
1372                          * have a transport if ASCONF had deleted it
1373                          * while DATA was outstanding).
1374                          */
1375                         if (!tchunk->tsn_gap_acked) {
1376                                 tchunk->tsn_gap_acked = 1;
1377                                 if (TSN_lt(*highest_new_tsn_in_sack, tsn))
1378                                         *highest_new_tsn_in_sack = tsn;
1379                                 bytes_acked += sctp_data_size(tchunk);
1380                                 if (!tchunk->transport)
1381                                         migrate_bytes += sctp_data_size(tchunk);
1382                                 forward_progress = true;
1383                         }
1384 
1385                         if (TSN_lte(tsn, sack_ctsn)) {
1386                                 /* RFC 2960  6.3.2 Retransmission Timer Rules
1387                                  *
1388                                  * R3) Whenever a SACK is received
1389                                  * that acknowledges the DATA chunk
1390                                  * with the earliest outstanding TSN
1391                                  * for that address, restart T3-rtx
1392                                  * timer for that address with its
1393                                  * current RTO.
1394                                  */
1395                                 restart_timer = 1;
1396                                 forward_progress = true;
1397 
1398                                 if (!tchunk->tsn_gap_acked) {
1399                                         /*
1400                                          * SFR-CACC algorithm:
1401                                          * 2) If the SACK contains gap acks
1402                                          * and the flag CHANGEOVER_ACTIVE is
1403                                          * set the receiver of the SACK MUST
1404                                          * take the following action:
1405                                          *
1406                                          * B) For each TSN t being acked that
1407                                          * has not been acked in any SACK so
1408                                          * far, set cacc_saw_newack to 1 for
1409                                          * the destination that the TSN was
1410                                          * sent to.
1411                                          */
1412                                         if (transport &&
1413                                             sack->num_gap_ack_blocks &&
1414                                             q->asoc->peer.primary_path->cacc.
1415                                             changeover_active)
1416                                                 transport->cacc.cacc_saw_newack
1417                                                         = 1;
1418                                 }
1419 
1420                                 list_add_tail(&tchunk->transmitted_list,
1421                                               &q->sacked);
1422                         } else {
1423                                 /* RFC2960 7.2.4, sctpimpguide-05 2.8.2
1424                                  * M2) Each time a SACK arrives reporting
1425                                  * 'Stray DATA chunk(s)' record the highest TSN
1426                                  * reported as newly acknowledged, call this
1427                                  * value 'HighestTSNinSack'. A newly
1428                                  * acknowledged DATA chunk is one not
1429                                  * previously acknowledged in a SACK.
1430                                  *
1431                                  * When the SCTP sender of data receives a SACK
1432                                  * chunk that acknowledges, for the first time,
1433                                  * the receipt of a DATA chunk, all the still
1434                                  * unacknowledged DATA chunks whose TSN is
1435                                  * older than that newly acknowledged DATA
1436                                  * chunk, are qualified as 'Stray DATA chunks'.
1437                                  */
1438                                 list_add_tail(lchunk, &tlist);
1439                         }
1440                 } else {
1441                         if (tchunk->tsn_gap_acked) {
1442                                 pr_debug("%s: receiver reneged on data TSN:0x%x\n",
1443                                          __func__, tsn);
1444 
1445                                 tchunk->tsn_gap_acked = 0;
1446 
1447                                 if (tchunk->transport)
1448                                         bytes_acked -= sctp_data_size(tchunk);
1449 
1450                                 /* RFC 2960 6.3.2 Retransmission Timer Rules
1451                                  *
1452                                  * R4) Whenever a SACK is received missing a
1453                                  * TSN that was previously acknowledged via a
1454                                  * Gap Ack Block, start T3-rtx for the
1455                                  * destination address to which the DATA
1456                                  * chunk was originally
1457                                  * transmitted if it is not already running.
1458                                  */
1459                                 restart_timer = 1;
1460                         }
1461 
1462                         list_add_tail(lchunk, &tlist);
1463                 }
1464         }
1465 
1466         if (transport) {
1467                 if (bytes_acked) {
1468                         struct sctp_association *asoc = transport->asoc;
1469 
1470                         /* We may have counted DATA that was migrated
1471                          * to this transport due to DEL-IP operation.
1472                          * Subtract those bytes, since the were never
1473                          * send on this transport and shouldn't be
1474                          * credited to this transport.
1475                          */
1476                         bytes_acked -= migrate_bytes;
1477 
1478                         /* 8.2. When an outstanding TSN is acknowledged,
1479                          * the endpoint shall clear the error counter of
1480                          * the destination transport address to which the
1481                          * DATA chunk was last sent.
1482                          * The association's overall error counter is
1483                          * also cleared.
1484                          */
1485                         transport->error_count = 0;
1486                         transport->asoc->overall_error_count = 0;
1487                         forward_progress = true;
1488 
1489                         /*
1490                          * While in SHUTDOWN PENDING, we may have started
1491                          * the T5 shutdown guard timer after reaching the
1492                          * retransmission limit. Stop that timer as soon
1493                          * as the receiver acknowledged any data.
1494                          */
1495                         if (asoc->state == SCTP_STATE_SHUTDOWN_PENDING &&
1496                             del_timer(&asoc->timers
1497                                 [SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD]))
1498                                         sctp_association_put(asoc);
1499 
1500                         /* Mark the destination transport address as
1501                          * active if it is not so marked.
1502                          */
1503                         if ((transport->state == SCTP_INACTIVE ||
1504                              transport->state == SCTP_UNCONFIRMED) &&
1505                             sctp_cmp_addr_exact(&transport->ipaddr, saddr)) {
1506                                 sctp_assoc_control_transport(
1507                                         transport->asoc,
1508                                         transport,
1509                                         SCTP_TRANSPORT_UP,
1510                                         SCTP_RECEIVED_SACK);
1511                         }
1512 
1513                         sctp_transport_raise_cwnd(transport, sack_ctsn,
1514                                                   bytes_acked);
1515 
1516                         transport->flight_size -= bytes_acked;
1517                         if (transport->flight_size == 0)
1518                                 transport->partial_bytes_acked = 0;
1519                         q->outstanding_bytes -= bytes_acked + migrate_bytes;
1520                 } else {
1521                         /* RFC 2960 6.1, sctpimpguide-06 2.15.2
1522                          * When a sender is doing zero window probing, it
1523                          * should not timeout the association if it continues
1524                          * to receive new packets from the receiver. The
1525                          * reason is that the receiver MAY keep its window
1526                          * closed for an indefinite time.
1527                          * A sender is doing zero window probing when the
1528                          * receiver's advertised window is zero, and there is
1529                          * only one data chunk in flight to the receiver.
1530                          *
1531                          * Allow the association to timeout while in SHUTDOWN
1532                          * PENDING or SHUTDOWN RECEIVED in case the receiver
1533                          * stays in zero window mode forever.
1534                          */
1535                         if (!q->asoc->peer.rwnd &&
1536                             !list_empty(&tlist) &&
1537                             (sack_ctsn+2 == q->asoc->next_tsn) &&
1538                             q->asoc->state < SCTP_STATE_SHUTDOWN_PENDING) {
1539                                 pr_debug("%s: sack received for zero window "
1540                                          "probe:%u\n", __func__, sack_ctsn);
1541 
1542                                 q->asoc->overall_error_count = 0;
1543                                 transport->error_count = 0;
1544                         }
1545                 }
1546 
1547                 /* RFC 2960 6.3.2 Retransmission Timer Rules
1548                  *
1549                  * R2) Whenever all outstanding data sent to an address have
1550                  * been acknowledged, turn off the T3-rtx timer of that
1551                  * address.
1552                  */
1553                 if (!transport->flight_size) {
1554                         if (del_timer(&transport->T3_rtx_timer))
1555                                 sctp_transport_put(transport);
1556                 } else if (restart_timer) {
1557                         if (!mod_timer(&transport->T3_rtx_timer,
1558                                        jiffies + transport->rto))
1559                                 sctp_transport_hold(transport);
1560                 }
1561 
1562                 if (forward_progress) {
1563                         if (transport->dst)
1564                                 dst_confirm(transport->dst);
1565                 }
1566         }
1567 
1568         list_splice(&tlist, transmitted_queue);
1569 }
1570 
1571 /* Mark chunks as missing and consequently may get retransmitted. */
1572 static void sctp_mark_missing(struct sctp_outq *q,
1573                               struct list_head *transmitted_queue,
1574                               struct sctp_transport *transport,
1575                               __u32 highest_new_tsn_in_sack,
1576                               int count_of_newacks)
1577 {
1578         struct sctp_chunk *chunk;
1579         __u32 tsn;
1580         char do_fast_retransmit = 0;
1581         struct sctp_association *asoc = q->asoc;
1582         struct sctp_transport *primary = asoc->peer.primary_path;
1583 
1584         list_for_each_entry(chunk, transmitted_queue, transmitted_list) {
1585 
1586                 tsn = ntohl(chunk->subh.data_hdr->tsn);
1587 
1588                 /* RFC 2960 7.2.4, sctpimpguide-05 2.8.2 M3) Examine all
1589                  * 'Unacknowledged TSN's', if the TSN number of an
1590                  * 'Unacknowledged TSN' is smaller than the 'HighestTSNinSack'
1591                  * value, increment the 'TSN.Missing.Report' count on that
1592                  * chunk if it has NOT been fast retransmitted or marked for
1593                  * fast retransmit already.
1594                  */
1595                 if (chunk->fast_retransmit == SCTP_CAN_FRTX &&
1596                     !chunk->tsn_gap_acked &&
1597                     TSN_lt(tsn, highest_new_tsn_in_sack)) {
1598 
1599                         /* SFR-CACC may require us to skip marking
1600                          * this chunk as missing.
1601                          */
1602                         if (!transport || !sctp_cacc_skip(primary,
1603                                                 chunk->transport,
1604                                                 count_of_newacks, tsn)) {
1605                                 chunk->tsn_missing_report++;
1606 
1607                                 pr_debug("%s: tsn:0x%x missing counter:%d\n",
1608                                          __func__, tsn, chunk->tsn_missing_report);
1609                         }
1610                 }
1611                 /*
1612                  * M4) If any DATA chunk is found to have a
1613                  * 'TSN.Missing.Report'
1614                  * value larger than or equal to 3, mark that chunk for
1615                  * retransmission and start the fast retransmit procedure.
1616                  */
1617 
1618                 if (chunk->tsn_missing_report >= 3) {
1619                         chunk->fast_retransmit = SCTP_NEED_FRTX;
1620                         do_fast_retransmit = 1;
1621                 }
1622         }
1623 
1624         if (transport) {
1625                 if (do_fast_retransmit)
1626                         sctp_retransmit(q, transport, SCTP_RTXR_FAST_RTX);
1627 
1628                 pr_debug("%s: transport:%p, cwnd:%d, ssthresh:%d, "
1629                          "flight_size:%d, pba:%d\n",  __func__, transport,
1630                          transport->cwnd, transport->ssthresh,
1631                          transport->flight_size, transport->partial_bytes_acked);
1632         }
1633 }
1634 
1635 /* Is the given TSN acked by this packet?  */
1636 static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn)
1637 {
1638         int i;
1639         sctp_sack_variable_t *frags;
1640         __u16 gap;
1641         __u32 ctsn = ntohl(sack->cum_tsn_ack);
1642 
1643         if (TSN_lte(tsn, ctsn))
1644                 goto pass;
1645 
1646         /* 3.3.4 Selective Acknowledgement (SACK) (3):
1647          *
1648          * Gap Ack Blocks:
1649          *  These fields contain the Gap Ack Blocks. They are repeated
1650          *  for each Gap Ack Block up to the number of Gap Ack Blocks
1651          *  defined in the Number of Gap Ack Blocks field. All DATA
1652          *  chunks with TSNs greater than or equal to (Cumulative TSN
1653          *  Ack + Gap Ack Block Start) and less than or equal to
1654          *  (Cumulative TSN Ack + Gap Ack Block End) of each Gap Ack
1655          *  Block are assumed to have been received correctly.
1656          */
1657 
1658         frags = sack->variable;
1659         gap = tsn - ctsn;
1660         for (i = 0; i < ntohs(sack->num_gap_ack_blocks); ++i) {
1661                 if (TSN_lte(ntohs(frags[i].gab.start), gap) &&
1662                     TSN_lte(gap, ntohs(frags[i].gab.end)))
1663                         goto pass;
1664         }
1665 
1666         return 0;
1667 pass:
1668         return 1;
1669 }
1670 
1671 static inline int sctp_get_skip_pos(struct sctp_fwdtsn_skip *skiplist,
1672                                     int nskips, __be16 stream)
1673 {
1674         int i;
1675 
1676         for (i = 0; i < nskips; i++) {
1677                 if (skiplist[i].stream == stream)
1678                         return i;
1679         }
1680         return i;
1681 }
1682 
1683 /* Create and add a fwdtsn chunk to the outq's control queue if needed. */
1684 static void sctp_generate_fwdtsn(struct sctp_outq *q, __u32 ctsn)
1685 {
1686         struct sctp_association *asoc = q->asoc;
1687         struct sctp_chunk *ftsn_chunk = NULL;
1688         struct sctp_fwdtsn_skip ftsn_skip_arr[10];
1689         int nskips = 0;
1690         int skip_pos = 0;
1691         __u32 tsn;
1692         struct sctp_chunk *chunk;
1693         struct list_head *lchunk, *temp;
1694 
1695         if (!asoc->peer.prsctp_capable)
1696                 return;
1697 
1698         /* PR-SCTP C1) Let SackCumAck be the Cumulative TSN ACK carried in the
1699          * received SACK.
1700          *
1701          * If (Advanced.Peer.Ack.Point < SackCumAck), then update
1702          * Advanced.Peer.Ack.Point to be equal to SackCumAck.
1703          */
1704         if (TSN_lt(asoc->adv_peer_ack_point, ctsn))
1705                 asoc->adv_peer_ack_point = ctsn;
1706 
1707         /* PR-SCTP C2) Try to further advance the "Advanced.Peer.Ack.Point"
1708          * locally, that is, to move "Advanced.Peer.Ack.Point" up as long as
1709          * the chunk next in the out-queue space is marked as "abandoned" as
1710          * shown in the following example:
1711          *
1712          * Assuming that a SACK arrived with the Cumulative TSN ACK 102
1713          * and the Advanced.Peer.Ack.Point is updated to this value:
1714          *
1715          *   out-queue at the end of  ==>   out-queue after Adv.Ack.Point
1716          *   normal SACK processing           local advancement
1717          *                ...                           ...
1718          *   Adv.Ack.Pt-> 102 acked                     102 acked
1719          *                103 abandoned                 103 abandoned
1720          *                104 abandoned     Adv.Ack.P-> 104 abandoned
1721          *                105                           105
1722          *                106 acked                     106 acked
1723          *                ...                           ...
1724          *
1725          * In this example, the data sender successfully advanced the
1726          * "Advanced.Peer.Ack.Point" from 102 to 104 locally.
1727          */
1728         list_for_each_safe(lchunk, temp, &q->abandoned) {
1729                 chunk = list_entry(lchunk, struct sctp_chunk,
1730                                         transmitted_list);
1731                 tsn = ntohl(chunk->subh.data_hdr->tsn);
1732 
1733                 /* Remove any chunks in the abandoned queue that are acked by
1734                  * the ctsn.
1735                  */
1736                 if (TSN_lte(tsn, ctsn)) {
1737                         list_del_init(lchunk);
1738                         sctp_chunk_free(chunk);
1739                 } else {
1740                         if (TSN_lte(tsn, asoc->adv_peer_ack_point+1)) {
1741                                 asoc->adv_peer_ack_point = tsn;
1742                                 if (chunk->chunk_hdr->flags &
1743                                          SCTP_DATA_UNORDERED)
1744                                         continue;
1745                                 skip_pos = sctp_get_skip_pos(&ftsn_skip_arr[0],
1746                                                 nskips,
1747                                                 chunk->subh.data_hdr->stream);
1748                                 ftsn_skip_arr[skip_pos].stream =
1749                                         chunk->subh.data_hdr->stream;
1750                                 ftsn_skip_arr[skip_pos].ssn =
1751                                          chunk->subh.data_hdr->ssn;
1752                                 if (skip_pos == nskips)
1753                                         nskips++;
1754                                 if (nskips == 10)
1755                                         break;
1756                         } else
1757                                 break;
1758                 }
1759         }
1760 
1761         /* PR-SCTP C3) If, after step C1 and C2, the "Advanced.Peer.Ack.Point"
1762          * is greater than the Cumulative TSN ACK carried in the received
1763          * SACK, the data sender MUST send the data receiver a FORWARD TSN
1764          * chunk containing the latest value of the
1765          * "Advanced.Peer.Ack.Point".
1766          *
1767          * C4) For each "abandoned" TSN the sender of the FORWARD TSN SHOULD
1768          * list each stream and sequence number in the forwarded TSN. This
1769          * information will enable the receiver to easily find any
1770          * stranded TSN's waiting on stream reorder queues. Each stream
1771          * SHOULD only be reported once; this means that if multiple
1772          * abandoned messages occur in the same stream then only the
1773          * highest abandoned stream sequence number is reported. If the
1774          * total size of the FORWARD TSN does NOT fit in a single MTU then
1775          * the sender of the FORWARD TSN SHOULD lower the
1776          * Advanced.Peer.Ack.Point to the last TSN that will fit in a
1777          * single MTU.
1778          */
1779         if (asoc->adv_peer_ack_point > ctsn)
1780                 ftsn_chunk = sctp_make_fwdtsn(asoc, asoc->adv_peer_ack_point,
1781                                               nskips, &ftsn_skip_arr[0]);
1782 
1783         if (ftsn_chunk) {
1784                 list_add_tail(&ftsn_chunk->list, &q->control_chunk_list);
1785                 SCTP_INC_STATS(sock_net(asoc->base.sk), SCTP_MIB_OUTCTRLCHUNKS);
1786         }
1787 }
1788 

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