4eb81a1407b7e027c7da1302a8af43705be3015a
[linux-2.6.git] / net / sctp / outqueue.c
1 /* SCTP kernel reference 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 reference Implementation
8  *
9  * These functions implement the sctp_outq class.   The outqueue handles
10  * bundling and queueing of outgoing SCTP chunks.
11  *
12  * The SCTP reference 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  * The SCTP reference 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, write to
26  * the Free Software Foundation, 59 Temple Place - Suite 330,
27  * Boston, MA 02111-1307, USA.
28  *
29  * Please send any bug reports or fixes you make to the
30  * email address(es):
31  *    lksctp developers <lksctp-developers@lists.sourceforge.net>
32  *
33  * Or submit a bug report through the following website:
34  *    http://www.sf.net/projects/lksctp
35  *
36  * Written or modified by:
37  *    La Monte H.P. Yarroll <piggy@acm.org>
38  *    Karl Knutson          <karl@athena.chicago.il.us>
39  *    Perry Melange         <pmelange@null.cc.uic.edu>
40  *    Xingang Guo           <xingang.guo@intel.com>
41  *    Hui Huang             <hui.huang@nokia.com>
42  *    Sridhar Samudrala     <sri@us.ibm.com>
43  *    Jon Grimm             <jgrimm@us.ibm.com>
44  *
45  * Any bugs reported given to us we will try to fix... any fixes shared will
46  * be incorporated into the next SCTP release.
47  */
48
49 #include <linux/types.h>
50 #include <linux/list.h>   /* For struct list_head */
51 #include <linux/socket.h>
52 #include <linux/ip.h>
53 #include <net/sock.h>     /* For skb_set_owner_w */
54
55 #include <net/sctp/sctp.h>
56 #include <net/sctp/sm.h>
57
58 /* Declare internal functions here.  */
59 static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn);
60 static void sctp_check_transmitted(struct sctp_outq *q,
61                                    struct list_head *transmitted_queue,
62                                    struct sctp_transport *transport,
63                                    struct sctp_sackhdr *sack,
64                                    __u32 highest_new_tsn);
65
66 static void sctp_mark_missing(struct sctp_outq *q,
67                               struct list_head *transmitted_queue,
68                               struct sctp_transport *transport,
69                               __u32 highest_new_tsn,
70                               int count_of_newacks);
71
72 static void sctp_generate_fwdtsn(struct sctp_outq *q, __u32 sack_ctsn);
73
74 /* Add data to the front of the queue. */
75 static inline void sctp_outq_head_data(struct sctp_outq *q,
76                                         struct sctp_chunk *ch)
77 {
78         __skb_queue_head(&q->out, (struct sk_buff *)ch);
79         q->out_qlen += ch->skb->len;
80         return;
81 }
82
83 /* Take data from the front of the queue. */
84 static inline struct sctp_chunk *sctp_outq_dequeue_data(struct sctp_outq *q)
85 {
86         struct sctp_chunk *ch;
87         ch = (struct sctp_chunk *)__skb_dequeue(&q->out);
88         if (ch)
89                 q->out_qlen -= ch->skb->len;
90         return ch;
91 }
92 /* Add data chunk to the end of the queue. */
93 static inline void sctp_outq_tail_data(struct sctp_outq *q,
94                                        struct sctp_chunk *ch)
95 {
96         __skb_queue_tail(&q->out, (struct sk_buff *)ch);
97         q->out_qlen += ch->skb->len;
98         return;
99 }
100
101 /*
102  * SFR-CACC algorithm:
103  * D) If count_of_newacks is greater than or equal to 2
104  * and t was not sent to the current primary then the
105  * sender MUST NOT increment missing report count for t.
106  */
107 static inline int sctp_cacc_skip_3_1_d(struct sctp_transport *primary,
108                                        struct sctp_transport *transport,
109                                        int count_of_newacks)
110 {
111         if (count_of_newacks >=2 && transport != primary)
112                 return 1;
113         return 0;
114 }
115
116 /*
117  * SFR-CACC algorithm:
118  * F) If count_of_newacks is less than 2, let d be the
119  * destination to which t was sent. If cacc_saw_newack
120  * is 0 for destination d, then the sender MUST NOT
121  * increment missing report count for t.
122  */
123 static inline int sctp_cacc_skip_3_1_f(struct sctp_transport *transport,
124                                        int count_of_newacks)
125 {
126         if (count_of_newacks < 2 && !transport->cacc.cacc_saw_newack)
127                 return 1;
128         return 0;
129 }
130
131 /*
132  * SFR-CACC algorithm:
133  * 3.1) If CYCLING_CHANGEOVER is 0, the sender SHOULD
134  * execute steps C, D, F.
135  *
136  * C has been implemented in sctp_outq_sack
137  */
138 static inline int sctp_cacc_skip_3_1(struct sctp_transport *primary,
139                                      struct sctp_transport *transport,
140                                      int count_of_newacks)
141 {
142         if (!primary->cacc.cycling_changeover) {
143                 if (sctp_cacc_skip_3_1_d(primary, transport, count_of_newacks))
144                         return 1;
145                 if (sctp_cacc_skip_3_1_f(transport, count_of_newacks))
146                         return 1;
147                 return 0;
148         }
149         return 0;
150 }
151
152 /*
153  * SFR-CACC algorithm:
154  * 3.2) Else if CYCLING_CHANGEOVER is 1, and t is less
155  * than next_tsn_at_change of the current primary, then
156  * the sender MUST NOT increment missing report count
157  * for t.
158  */
159 static inline int sctp_cacc_skip_3_2(struct sctp_transport *primary, __u32 tsn)
160 {
161         if (primary->cacc.cycling_changeover &&
162             TSN_lt(tsn, primary->cacc.next_tsn_at_change))
163                 return 1;
164         return 0;
165 }
166
167 /*
168  * SFR-CACC algorithm:
169  * 3) If the missing report count for TSN t is to be
170  * incremented according to [RFC2960] and
171  * [SCTP_STEWART-2002], and CHANGEOVER_ACTIVE is set,
172  * then the sender MUST futher execute steps 3.1 and
173  * 3.2 to determine if the missing report count for
174  * TSN t SHOULD NOT be incremented.
175  *
176  * 3.3) If 3.1 and 3.2 do not dictate that the missing
177  * report count for t should not be incremented, then
178  * the sender SOULD increment missing report count for
179  * t (according to [RFC2960] and [SCTP_STEWART_2002]).
180  */
181 static inline int sctp_cacc_skip(struct sctp_transport *primary,
182                                  struct sctp_transport *transport,
183                                  int count_of_newacks,
184                                  __u32 tsn)
185 {
186         if (primary->cacc.changeover_active &&
187             (sctp_cacc_skip_3_1(primary, transport, count_of_newacks)
188              || sctp_cacc_skip_3_2(primary, tsn)))
189                 return 1;
190         return 0;
191 }
192
193 /* Initialize an existing sctp_outq.  This does the boring stuff.
194  * You still need to define handlers if you really want to DO
195  * something with this structure...
196  */
197 void sctp_outq_init(struct sctp_association *asoc, struct sctp_outq *q)
198 {
199         q->asoc = asoc;
200         skb_queue_head_init(&q->out);
201         skb_queue_head_init(&q->control);
202         INIT_LIST_HEAD(&q->retransmit);
203         INIT_LIST_HEAD(&q->sacked);
204         INIT_LIST_HEAD(&q->abandoned);
205
206         q->outstanding_bytes = 0;
207         q->empty = 1;
208         q->cork  = 0;
209
210         q->malloced = 0;
211         q->out_qlen = 0;
212 }
213
214 /* Free the outqueue structure and any related pending chunks.
215  */
216 void sctp_outq_teardown(struct sctp_outq *q)
217 {
218         struct sctp_transport *transport;
219         struct list_head *lchunk, *pos, *temp;
220         struct sctp_chunk *chunk;
221
222         /* Throw away unacknowledged chunks. */
223         list_for_each(pos, &q->asoc->peer.transport_addr_list) {
224                 transport = list_entry(pos, struct sctp_transport, transports);
225                 while ((lchunk = sctp_list_dequeue(&transport->transmitted)) != NULL) {
226                         chunk = list_entry(lchunk, struct sctp_chunk,
227                                            transmitted_list);
228                         /* Mark as part of a failed message. */
229                         sctp_chunk_fail(chunk, q->error);
230                         sctp_chunk_free(chunk);
231                 }
232         }
233
234         /* Throw away chunks that have been gap ACKed.  */
235         list_for_each_safe(lchunk, temp, &q->sacked) {
236                 list_del_init(lchunk);
237                 chunk = list_entry(lchunk, struct sctp_chunk,
238                                    transmitted_list);
239                 sctp_chunk_fail(chunk, q->error);
240                 sctp_chunk_free(chunk);
241         }
242
243         /* Throw away any chunks in the retransmit queue. */
244         list_for_each_safe(lchunk, temp, &q->retransmit) {
245                 list_del_init(lchunk);
246                 chunk = list_entry(lchunk, struct sctp_chunk,
247                                    transmitted_list);
248                 sctp_chunk_fail(chunk, q->error);
249                 sctp_chunk_free(chunk);
250         }
251
252         /* Throw away any chunks that are in the abandoned queue. */
253         list_for_each_safe(lchunk, temp, &q->abandoned) {
254                 list_del_init(lchunk);
255                 chunk = list_entry(lchunk, struct sctp_chunk,
256                                    transmitted_list);
257                 sctp_chunk_fail(chunk, q->error);
258                 sctp_chunk_free(chunk);
259         }
260
261         /* Throw away any leftover data chunks. */
262         while ((chunk = sctp_outq_dequeue_data(q)) != NULL) {
263
264                 /* Mark as send failure. */
265                 sctp_chunk_fail(chunk, q->error);
266                 sctp_chunk_free(chunk);
267         }
268
269         q->error = 0;
270
271         /* Throw away any leftover control chunks. */
272         while ((chunk = (struct sctp_chunk *) skb_dequeue(&q->control)) != NULL)
273                 sctp_chunk_free(chunk);
274 }
275
276 /* Free the outqueue structure and any related pending chunks.  */
277 void sctp_outq_free(struct sctp_outq *q)
278 {
279         /* Throw away leftover chunks. */
280         sctp_outq_teardown(q);
281
282         /* If we were kmalloc()'d, free the memory.  */
283         if (q->malloced)
284                 kfree(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         int error = 0;
291
292         SCTP_DEBUG_PRINTK("sctp_outq_tail(%p, %p[%s])\n",
293                           q, chunk, chunk && chunk->chunk_hdr ?
294                           sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type))
295                           : "Illegal Chunk");
296
297         /* If it is data, queue it up, otherwise, send it
298          * immediately.
299          */
300         if (SCTP_CID_DATA == chunk->chunk_hdr->type) {
301                 /* Is it OK to queue data chunks?  */
302                 /* From 9. Termination of Association
303                  *
304                  * When either endpoint performs a shutdown, the
305                  * association on each peer will stop accepting new
306                  * data from its user and only deliver data in queue
307                  * at the time of sending or receiving the SHUTDOWN
308                  * chunk.
309                  */
310                 switch (q->asoc->state) {
311                 case SCTP_STATE_EMPTY:
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                         SCTP_DEBUG_PRINTK("outqueueing (%p, %p[%s])\n",
323                           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(SCTP_MIB_OUTUNORDERCHUNKS);
330                         else
331                                 SCTP_INC_STATS(SCTP_MIB_OUTORDERCHUNKS);
332                         q->empty = 0;
333                         break;
334                 };
335         } else {
336                 __skb_queue_tail(&q->control, (struct sk_buff *) chunk);
337                 SCTP_INC_STATS(SCTP_MIB_OUTCTRLCHUNKS);
338         }
339
340         if (error < 0)
341                 return error;
342
343         if (!q->cork)
344                 error = sctp_outq_flush(q, 0);
345
346         return error;
347 }
348
349 /* Insert a chunk into the sorted list based on the TSNs.  The retransmit list
350  * and the abandoned list are in ascending order.
351  */
352 static void sctp_insert_list(struct list_head *head, struct list_head *new)
353 {
354         struct list_head *pos;
355         struct sctp_chunk *nchunk, *lchunk;
356         __u32 ntsn, ltsn;
357         int done = 0;
358
359         nchunk = list_entry(new, struct sctp_chunk, transmitted_list);
360         ntsn = ntohl(nchunk->subh.data_hdr->tsn);
361
362         list_for_each(pos, head) {
363                 lchunk = list_entry(pos, struct sctp_chunk, transmitted_list);
364                 ltsn = ntohl(lchunk->subh.data_hdr->tsn);
365                 if (TSN_lt(ntsn, ltsn)) {
366                         list_add(new, pos->prev);
367                         done = 1;
368                         break;
369                 }
370         }
371         if (!done)
372                 list_add_tail(new, head); 
373 }
374
375 /* Mark all the eligible packets on a transport for retransmission.  */
376 void sctp_retransmit_mark(struct sctp_outq *q,
377                           struct sctp_transport *transport,
378                           __u8 fast_retransmit)
379 {
380         struct list_head *lchunk, *ltemp;
381         struct sctp_chunk *chunk;
382
383         /* Walk through the specified transmitted queue.  */
384         list_for_each_safe(lchunk, ltemp, &transport->transmitted) {
385                 chunk = list_entry(lchunk, struct sctp_chunk,
386                                    transmitted_list);
387
388                 /* If the chunk is abandoned, move it to abandoned list. */
389                 if (sctp_chunk_abandoned(chunk)) {
390                         list_del_init(lchunk);
391                         sctp_insert_list(&q->abandoned, lchunk);
392                         continue;
393                 }
394
395                 /* If we are doing retransmission due to a fast retransmit,
396                  * only the chunk's that are marked for fast retransmit
397                  * should be added to the retransmit queue.  If we are doing
398                  * retransmission due to a timeout or pmtu discovery, only the
399                  * chunks that are not yet acked should be added to the
400                  * retransmit queue.
401                  */
402                 if ((fast_retransmit && chunk->fast_retransmit) ||
403                    (!fast_retransmit && !chunk->tsn_gap_acked)) {
404                         /* RFC 2960 6.2.1 Processing a Received SACK
405                          *
406                          * C) Any time a DATA chunk is marked for
407                          * retransmission (via either T3-rtx timer expiration
408                          * (Section 6.3.3) or via fast retransmit
409                          * (Section 7.2.4)), add the data size of those
410                          * chunks to the rwnd.
411                          */
412                         q->asoc->peer.rwnd += sctp_data_size(chunk);
413                         q->outstanding_bytes -= sctp_data_size(chunk);
414                         transport->flight_size -= sctp_data_size(chunk);
415
416                         /* sctpimpguide-05 Section 2.8.2
417                          * M5) If a T3-rtx timer expires, the
418                          * 'TSN.Missing.Report' of all affected TSNs is set
419                          * to 0.
420                          */
421                         chunk->tsn_missing_report = 0;
422
423                         /* If a chunk that is being used for RTT measurement
424                          * has to be retransmitted, we cannot use this chunk
425                          * anymore for RTT measurements. Reset rto_pending so
426                          * that a new RTT measurement is started when a new
427                          * data chunk is sent.
428                          */
429                         if (chunk->rtt_in_progress) {
430                                 chunk->rtt_in_progress = 0;
431                                 transport->rto_pending = 0;
432                         }
433
434                         /* Move the chunk to the retransmit queue. The chunks
435                          * on the retransmit queue are always kept in order.
436                          */
437                         list_del_init(lchunk);
438                         sctp_insert_list(&q->retransmit, lchunk);
439                 }
440         }
441
442         SCTP_DEBUG_PRINTK("%s: transport: %p, fast_retransmit: %d, "
443                           "cwnd: %d, ssthresh: %d, flight_size: %d, "
444                           "pba: %d\n", __FUNCTION__,
445                           transport, fast_retransmit,
446                           transport->cwnd, transport->ssthresh,
447                           transport->flight_size,
448                           transport->partial_bytes_acked);
449
450 }
451
452 /* Mark all the eligible packets on a transport for retransmission and force
453  * one packet out.
454  */
455 void sctp_retransmit(struct sctp_outq *q, struct sctp_transport *transport,
456                      sctp_retransmit_reason_t reason)
457 {
458         int error = 0;
459         __u8 fast_retransmit = 0;
460
461         switch(reason) {
462         case SCTP_RTXR_T3_RTX:
463                 sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_T3_RTX);
464                 /* Update the retran path if the T3-rtx timer has expired for
465                  * the current retran path.
466                  */
467                 if (transport == transport->asoc->peer.retran_path)
468                         sctp_assoc_update_retran_path(transport->asoc);
469                 break;
470         case SCTP_RTXR_FAST_RTX:
471                 sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_FAST_RTX);
472                 fast_retransmit = 1;
473                 break;
474         case SCTP_RTXR_PMTUD:
475         default:
476                 break;
477         }
478
479         sctp_retransmit_mark(q, transport, fast_retransmit);
480
481         /* PR-SCTP A5) Any time the T3-rtx timer expires, on any destination,
482          * the sender SHOULD try to advance the "Advanced.Peer.Ack.Point" by
483          * following the procedures outlined in C1 - C5.
484          */
485         sctp_generate_fwdtsn(q, q->asoc->ctsn_ack_point);
486
487         error = sctp_outq_flush(q, /* rtx_timeout */ 1);
488
489         if (error)
490                 q->asoc->base.sk->sk_err = -error;
491 }
492
493 /*
494  * Transmit DATA chunks on the retransmit queue.  Upon return from
495  * sctp_outq_flush_rtx() the packet 'pkt' may contain chunks which
496  * need to be transmitted by the caller.
497  * We assume that pkt->transport has already been set.
498  *
499  * The return value is a normal kernel error return value.
500  */
501 static int sctp_outq_flush_rtx(struct sctp_outq *q, struct sctp_packet *pkt,
502                                int rtx_timeout, int *start_timer)
503 {
504         struct list_head *lqueue;
505         struct list_head *lchunk, *lchunk1;
506         struct sctp_transport *transport = pkt->transport;
507         sctp_xmit_t status;
508         struct sctp_chunk *chunk, *chunk1;
509         struct sctp_association *asoc;
510         int error = 0;
511
512         asoc = q->asoc;
513         lqueue = &q->retransmit;
514
515         /* RFC 2960 6.3.3 Handle T3-rtx Expiration
516          *
517          * E3) Determine how many of the earliest (i.e., lowest TSN)
518          * outstanding DATA chunks for the address for which the
519          * T3-rtx has expired will fit into a single packet, subject
520          * to the MTU constraint for the path corresponding to the
521          * destination transport address to which the retransmission
522          * is being sent (this may be different from the address for
523          * which the timer expires [see Section 6.4]). Call this value
524          * K. Bundle and retransmit those K DATA chunks in a single
525          * packet to the destination endpoint.
526          *
527          * [Just to be painfully clear, if we are retransmitting
528          * because a timeout just happened, we should send only ONE
529          * packet of retransmitted data.]
530          */
531         lchunk = sctp_list_dequeue(lqueue);
532
533         while (lchunk) {
534                 chunk = list_entry(lchunk, struct sctp_chunk,
535                                    transmitted_list);
536
537                 /* Make sure that Gap Acked TSNs are not retransmitted.  A
538                  * simple approach is just to move such TSNs out of the
539                  * way and into a 'transmitted' queue and skip to the
540                  * next chunk.
541                  */
542                 if (chunk->tsn_gap_acked) {
543                         list_add_tail(lchunk, &transport->transmitted);
544                         lchunk = sctp_list_dequeue(lqueue);
545                         continue;
546                 }
547
548                 /* Attempt to append this chunk to the packet. */
549                 status = sctp_packet_append_chunk(pkt, chunk);
550
551                 switch (status) {
552                 case SCTP_XMIT_PMTU_FULL:
553                         /* Send this packet.  */
554                         if ((error = sctp_packet_transmit(pkt)) == 0)
555                                 *start_timer = 1;
556
557                         /* If we are retransmitting, we should only
558                          * send a single packet.
559                          */
560                         if (rtx_timeout) {
561                                 list_add(lchunk, lqueue);
562                                 lchunk = NULL;
563                         }
564
565                         /* Bundle lchunk in the next round.  */
566                         break;
567
568                 case SCTP_XMIT_RWND_FULL:
569                         /* Send this packet. */
570                         if ((error = sctp_packet_transmit(pkt)) == 0)
571                                 *start_timer = 1;
572
573                         /* Stop sending DATA as there is no more room
574                          * at the receiver.
575                          */
576                         list_add(lchunk, lqueue);
577                         lchunk = NULL;
578                         break;
579
580                 case SCTP_XMIT_NAGLE_DELAY:
581                         /* Send this packet. */
582                         if ((error = sctp_packet_transmit(pkt)) == 0)
583                                 *start_timer = 1;
584
585                         /* Stop sending DATA because of nagle delay. */
586                         list_add(lchunk, lqueue);
587                         lchunk = NULL;
588                         break;
589
590                 default:
591                         /* The append was successful, so add this chunk to
592                          * the transmitted list.
593                          */
594                         list_add_tail(lchunk, &transport->transmitted);
595
596                         /* Mark the chunk as ineligible for fast retransmit 
597                          * after it is retransmitted.
598                          */
599                         chunk->fast_retransmit = 0;
600
601                         *start_timer = 1;
602                         q->empty = 0;
603
604                         /* Retrieve a new chunk to bundle. */
605                         lchunk = sctp_list_dequeue(lqueue);
606                         break;
607                 };
608
609                 /* If we are here due to a retransmit timeout or a fast
610                  * retransmit and if there are any chunks left in the retransmit
611                  * queue that could not fit in the PMTU sized packet, they need                  * to be marked as ineligible for a subsequent fast retransmit.
612                  */
613                 if (rtx_timeout && !lchunk) {
614                         list_for_each(lchunk1, lqueue) {
615                                 chunk1 = list_entry(lchunk1, struct sctp_chunk,
616                                                     transmitted_list);
617                                 chunk1->fast_retransmit = 0;
618                         }
619                 }
620         }
621
622         return error;
623 }
624
625 /* Cork the outqueue so queued chunks are really queued. */
626 int sctp_outq_uncork(struct sctp_outq *q)
627 {
628         int error = 0;
629         if (q->cork) {
630                 q->cork = 0;
631                 error = sctp_outq_flush(q, 0);
632         }
633         return error;
634 }
635
636 /*
637  * Try to flush an outqueue.
638  *
639  * Description: Send everything in q which we legally can, subject to
640  * congestion limitations.
641  * * Note: This function can be called from multiple contexts so appropriate
642  * locking concerns must be made.  Today we use the sock lock to protect
643  * this function.
644  */
645 int sctp_outq_flush(struct sctp_outq *q, int rtx_timeout)
646 {
647         struct sctp_packet *packet;
648         struct sctp_packet singleton;
649         struct sctp_association *asoc = q->asoc;
650         __u16 sport = asoc->base.bind_addr.port;
651         __u16 dport = asoc->peer.port;
652         __u32 vtag = asoc->peer.i.init_tag;
653         struct sk_buff_head *queue;
654         struct sctp_transport *transport = NULL;
655         struct sctp_transport *new_transport;
656         struct sctp_chunk *chunk;
657         sctp_xmit_t status;
658         int error = 0;
659         int start_timer = 0;
660
661         /* These transports have chunks to send. */
662         struct list_head transport_list;
663         struct list_head *ltransport;
664
665         INIT_LIST_HEAD(&transport_list);
666         packet = NULL;
667
668         /*
669          * 6.10 Bundling
670          *   ...
671          *   When bundling control chunks with DATA chunks, an
672          *   endpoint MUST place control chunks first in the outbound
673          *   SCTP packet.  The transmitter MUST transmit DATA chunks
674          *   within a SCTP packet in increasing order of TSN.
675          *   ...
676          */
677
678         queue = &q->control;
679         while ((chunk = (struct sctp_chunk *)skb_dequeue(queue)) != NULL) {
680                 /* Pick the right transport to use. */
681                 new_transport = chunk->transport;
682
683                 if (!new_transport) {
684                         new_transport = asoc->peer.active_path;
685                 } else if (new_transport->state == SCTP_INACTIVE) {
686                         /* If the chunk is Heartbeat or Heartbeat Ack,
687                          * send it to chunk->transport, even if it's
688                          * inactive.
689                          *
690                          * 3.3.6 Heartbeat Acknowledgement:
691                          * ...  
692                          * A HEARTBEAT ACK is always sent to the source IP
693                          * address of the IP datagram containing the
694                          * HEARTBEAT chunk to which this ack is responding.
695                          * ...  
696                          */
697                         if (chunk->chunk_hdr->type != SCTP_CID_HEARTBEAT &&
698                             chunk->chunk_hdr->type != SCTP_CID_HEARTBEAT_ACK)
699                                 new_transport = asoc->peer.active_path;
700                 }
701
702                 /* Are we switching transports?
703                  * Take care of transport locks.
704                  */
705                 if (new_transport != transport) {
706                         transport = new_transport;
707                         if (list_empty(&transport->send_ready)) {
708                                 list_add_tail(&transport->send_ready,
709                                               &transport_list);
710                         }
711                         packet = &transport->packet;
712                         sctp_packet_config(packet, vtag,
713                                            asoc->peer.ecn_capable);
714                 }
715
716                 switch (chunk->chunk_hdr->type) {
717                 /*
718                  * 6.10 Bundling
719                  *   ...
720                  *   An endpoint MUST NOT bundle INIT, INIT ACK or SHUTDOWN
721                  *   COMPLETE with any other chunks.  [Send them immediately.]
722                  */
723                 case SCTP_CID_INIT:
724                 case SCTP_CID_INIT_ACK:
725                 case SCTP_CID_SHUTDOWN_COMPLETE:
726                         sctp_packet_init(&singleton, transport, sport, dport);
727                         sctp_packet_config(&singleton, vtag, 0);
728                         sctp_packet_append_chunk(&singleton, chunk);
729                         error = sctp_packet_transmit(&singleton);
730                         if (error < 0)
731                                 return error;
732                         break;
733
734                 case SCTP_CID_ABORT:
735                 case SCTP_CID_SACK:
736                 case SCTP_CID_HEARTBEAT:
737                 case SCTP_CID_HEARTBEAT_ACK:
738                 case SCTP_CID_SHUTDOWN:
739                 case SCTP_CID_SHUTDOWN_ACK:
740                 case SCTP_CID_ERROR:
741                 case SCTP_CID_COOKIE_ECHO:
742                 case SCTP_CID_COOKIE_ACK:
743                 case SCTP_CID_ECN_ECNE:
744                 case SCTP_CID_ECN_CWR:
745                 case SCTP_CID_ASCONF:
746                 case SCTP_CID_ASCONF_ACK:
747                 case SCTP_CID_FWD_TSN:
748                         sctp_packet_transmit_chunk(packet, chunk);
749                         break;
750
751                 default:
752                         /* We built a chunk with an illegal type! */
753                         BUG();
754                 };
755         }
756
757         /* Is it OK to send data chunks?  */
758         switch (asoc->state) {
759         case SCTP_STATE_COOKIE_ECHOED:
760                 /* Only allow bundling when this packet has a COOKIE-ECHO
761                  * chunk.
762                  */
763                 if (!packet || !packet->has_cookie_echo)
764                         break;
765
766                 /* fallthru */
767         case SCTP_STATE_ESTABLISHED:
768         case SCTP_STATE_SHUTDOWN_PENDING:
769         case SCTP_STATE_SHUTDOWN_RECEIVED:
770                 /*
771                  * RFC 2960 6.1  Transmission of DATA Chunks
772                  *
773                  * C) When the time comes for the sender to transmit,
774                  * before sending new DATA chunks, the sender MUST
775                  * first transmit any outstanding DATA chunks which
776                  * are marked for retransmission (limited by the
777                  * current cwnd).
778                  */
779                 if (!list_empty(&q->retransmit)) {
780                         if (transport == asoc->peer.retran_path)
781                                 goto retran;
782
783                         /* Switch transports & prepare the packet.  */
784
785                         transport = asoc->peer.retran_path;
786
787                         if (list_empty(&transport->send_ready)) {
788                                 list_add_tail(&transport->send_ready,
789                                               &transport_list);
790                         }
791
792                         packet = &transport->packet;
793                         sctp_packet_config(packet, vtag,
794                                            asoc->peer.ecn_capable);
795                 retran:
796                         error = sctp_outq_flush_rtx(q, packet,
797                                                     rtx_timeout, &start_timer);
798
799                         if (start_timer)
800                                 sctp_transport_reset_timers(transport);
801
802                         /* This can happen on COOKIE-ECHO resend.  Only
803                          * one chunk can get bundled with a COOKIE-ECHO.
804                          */
805                         if (packet->has_cookie_echo)
806                                 goto sctp_flush_out;
807
808                         /* Don't send new data if there is still data
809                          * waiting to retransmit.
810                          */
811                         if (!list_empty(&q->retransmit))
812                                 goto sctp_flush_out;
813                 }
814
815                 /* Finally, transmit new packets.  */
816                 start_timer = 0;
817                 queue = &q->out;
818
819                 while ((chunk = sctp_outq_dequeue_data(q)) != NULL) {
820                         /* RFC 2960 6.5 Every DATA chunk MUST carry a valid
821                          * stream identifier.
822                          */
823                         if (chunk->sinfo.sinfo_stream >=
824                             asoc->c.sinit_num_ostreams) {
825
826                                 /* Mark as failed send. */
827                                 sctp_chunk_fail(chunk, SCTP_ERROR_INV_STRM);
828                                 sctp_chunk_free(chunk);
829                                 continue;
830                         }
831
832                         /* Has this chunk expired? */
833                         if (sctp_chunk_abandoned(chunk)) {
834                                 sctp_chunk_fail(chunk, 0);
835                                 sctp_chunk_free(chunk);
836                                 continue;
837                         }
838
839                         /* If there is a specified transport, use it.
840                          * Otherwise, we want to use the active path.
841                          */
842                         new_transport = chunk->transport;
843                         if (!new_transport ||
844                             new_transport->state == SCTP_INACTIVE)
845                                 new_transport = asoc->peer.active_path;
846
847                         /* Change packets if necessary.  */
848                         if (new_transport != transport) {
849                                 transport = new_transport;
850
851                                 /* Schedule to have this transport's
852                                  * packet flushed.
853                                  */
854                                 if (list_empty(&transport->send_ready)) {
855                                         list_add_tail(&transport->send_ready,
856                                                       &transport_list);
857                                 }
858
859                                 packet = &transport->packet;
860                                 sctp_packet_config(packet, vtag,
861                                                    asoc->peer.ecn_capable);
862                         }
863
864                         SCTP_DEBUG_PRINTK("sctp_outq_flush(%p, %p[%s]), ",
865                                           q, chunk,
866                                           chunk && chunk->chunk_hdr ?
867                                           sctp_cname(SCTP_ST_CHUNK(
868                                                   chunk->chunk_hdr->type))
869                                           : "Illegal Chunk");
870
871                         SCTP_DEBUG_PRINTK("TX TSN 0x%x skb->head "
872                                         "%p skb->users %d.\n",
873                                         ntohl(chunk->subh.data_hdr->tsn),
874                                         chunk->skb ?chunk->skb->head : NULL,
875                                         chunk->skb ?
876                                         atomic_read(&chunk->skb->users) : -1);
877
878                         /* Add the chunk to the packet.  */
879                         status = sctp_packet_transmit_chunk(packet, chunk);
880
881                         switch (status) {
882                         case SCTP_XMIT_PMTU_FULL:
883                         case SCTP_XMIT_RWND_FULL:
884                         case SCTP_XMIT_NAGLE_DELAY:
885                                 /* We could not append this chunk, so put
886                                  * the chunk back on the output queue.
887                                  */
888                                 SCTP_DEBUG_PRINTK("sctp_outq_flush: could "
889                                         "not transmit TSN: 0x%x, status: %d\n",
890                                         ntohl(chunk->subh.data_hdr->tsn),
891                                         status);
892                                 sctp_outq_head_data(q, chunk);
893                                 goto sctp_flush_out;
894                                 break;
895
896                         case SCTP_XMIT_OK:
897                                 break;
898
899                         default:
900                                 BUG();
901                         }
902
903                         /* BUG: We assume that the sctp_packet_transmit() 
904                          * call below will succeed all the time and add the
905                          * chunk to the transmitted list and restart the
906                          * timers.
907                          * It is possible that the call can fail under OOM
908                          * conditions.
909                          *
910                          * Is this really a problem?  Won't this behave
911                          * like a lost TSN?
912                          */
913                         list_add_tail(&chunk->transmitted_list,
914                                       &transport->transmitted);
915
916                         sctp_transport_reset_timers(transport);
917
918                         q->empty = 0;
919
920                         /* Only let one DATA chunk get bundled with a
921                          * COOKIE-ECHO chunk.
922                          */
923                         if (packet->has_cookie_echo)
924                                 goto sctp_flush_out;
925                 }
926                 break;
927
928         default:
929                 /* Do nothing.  */
930                 break;
931         }
932
933 sctp_flush_out:
934
935         /* Before returning, examine all the transports touched in
936          * this call.  Right now, we bluntly force clear all the
937          * transports.  Things might change after we implement Nagle.
938          * But such an examination is still required.
939          *
940          * --xguo
941          */
942         while ((ltransport = sctp_list_dequeue(&transport_list)) != NULL ) {
943                 struct sctp_transport *t = list_entry(ltransport,
944                                                       struct sctp_transport,
945                                                       send_ready);
946                 packet = &t->packet;
947                 if (!sctp_packet_empty(packet))
948                         error = sctp_packet_transmit(packet);
949         }
950
951         return error;
952 }
953
954 /* Update unack_data based on the incoming SACK chunk */
955 static void sctp_sack_update_unack_data(struct sctp_association *assoc,
956                                         struct sctp_sackhdr *sack)
957 {
958         sctp_sack_variable_t *frags;
959         __u16 unack_data;
960         int i;
961
962         unack_data = assoc->next_tsn - assoc->ctsn_ack_point - 1;
963
964         frags = sack->variable;
965         for (i = 0; i < ntohs(sack->num_gap_ack_blocks); i++) {
966                 unack_data -= ((ntohs(frags[i].gab.end) -
967                                 ntohs(frags[i].gab.start) + 1));
968         }
969
970         assoc->unack_data = unack_data;
971 }
972
973 /* Return the highest new tsn that is acknowledged by the given SACK chunk. */
974 static __u32 sctp_highest_new_tsn(struct sctp_sackhdr *sack,
975                                   struct sctp_association *asoc)
976 {
977         struct list_head *ltransport, *lchunk;
978         struct sctp_transport *transport;
979         struct sctp_chunk *chunk;
980         __u32 highest_new_tsn, tsn;
981         struct list_head *transport_list = &asoc->peer.transport_addr_list;
982
983         highest_new_tsn = ntohl(sack->cum_tsn_ack);
984
985         list_for_each(ltransport, transport_list) {
986                 transport = list_entry(ltransport, struct sctp_transport,
987                                        transports);
988                 list_for_each(lchunk, &transport->transmitted) {
989                         chunk = list_entry(lchunk, struct sctp_chunk,
990                                            transmitted_list);
991                         tsn = ntohl(chunk->subh.data_hdr->tsn);
992
993                         if (!chunk->tsn_gap_acked &&
994                             TSN_lt(highest_new_tsn, tsn) &&
995                             sctp_acked(sack, tsn))
996                                 highest_new_tsn = tsn;
997                 }
998         }
999
1000         return highest_new_tsn;
1001 }
1002
1003 /* This is where we REALLY process a SACK.
1004  *
1005  * Process the SACK against the outqueue.  Mostly, this just frees
1006  * things off the transmitted queue.
1007  */
1008 int sctp_outq_sack(struct sctp_outq *q, struct sctp_sackhdr *sack)
1009 {
1010         struct sctp_association *asoc = q->asoc;
1011         struct sctp_transport *transport;
1012         struct sctp_chunk *tchunk = NULL;
1013         struct list_head *lchunk, *transport_list, *pos, *temp;
1014         sctp_sack_variable_t *frags = sack->variable;
1015         __u32 sack_ctsn, ctsn, tsn;
1016         __u32 highest_tsn, highest_new_tsn;
1017         __u32 sack_a_rwnd;
1018         unsigned outstanding;
1019         struct sctp_transport *primary = asoc->peer.primary_path;
1020         int count_of_newacks = 0;
1021
1022         /* Grab the association's destination address list. */
1023         transport_list = &asoc->peer.transport_addr_list;
1024
1025         sack_ctsn = ntohl(sack->cum_tsn_ack);
1026
1027         /*
1028          * SFR-CACC algorithm:
1029          * On receipt of a SACK the sender SHOULD execute the
1030          * following statements.
1031          *
1032          * 1) If the cumulative ack in the SACK passes next tsn_at_change
1033          * on the current primary, the CHANGEOVER_ACTIVE flag SHOULD be
1034          * cleared. The CYCLING_CHANGEOVER flag SHOULD also be cleared for
1035          * all destinations.
1036          */
1037         if (TSN_lte(primary->cacc.next_tsn_at_change, sack_ctsn)) {
1038                 primary->cacc.changeover_active = 0;
1039                 list_for_each(pos, transport_list) {
1040                         transport = list_entry(pos, struct sctp_transport,
1041                                         transports);
1042                         transport->cacc.cycling_changeover = 0;
1043                 }
1044         }
1045
1046         /*
1047          * SFR-CACC algorithm:
1048          * 2) If the SACK contains gap acks and the flag CHANGEOVER_ACTIVE
1049          * is set the receiver of the SACK MUST take the following actions:
1050          *
1051          * A) Initialize the cacc_saw_newack to 0 for all destination
1052          * addresses.
1053          */
1054         if (sack->num_gap_ack_blocks > 0 &&
1055             primary->cacc.changeover_active) {
1056                 list_for_each(pos, transport_list) {
1057                         transport = list_entry(pos, struct sctp_transport,
1058                                         transports);
1059                         transport->cacc.cacc_saw_newack = 0;
1060                 }
1061         }
1062
1063         /* Get the highest TSN in the sack. */
1064         highest_tsn = sack_ctsn;
1065         if (sack->num_gap_ack_blocks)
1066                 highest_tsn +=
1067                     ntohs(frags[ntohs(sack->num_gap_ack_blocks) - 1].gab.end);
1068
1069         if (TSN_lt(asoc->highest_sacked, highest_tsn)) {
1070                 highest_new_tsn = highest_tsn;
1071                 asoc->highest_sacked = highest_tsn;
1072         } else {
1073                 highest_new_tsn = sctp_highest_new_tsn(sack, asoc);
1074         }
1075
1076         /* Run through the retransmit queue.  Credit bytes received
1077          * and free those chunks that we can.
1078          */
1079         sctp_check_transmitted(q, &q->retransmit, NULL, sack, highest_new_tsn);
1080         sctp_mark_missing(q, &q->retransmit, NULL, highest_new_tsn, 0);
1081
1082         /* Run through the transmitted queue.
1083          * Credit bytes received and free those chunks which we can.
1084          *
1085          * This is a MASSIVE candidate for optimization.
1086          */
1087         list_for_each(pos, transport_list) {
1088                 transport  = list_entry(pos, struct sctp_transport,
1089                                         transports);
1090                 sctp_check_transmitted(q, &transport->transmitted,
1091                                        transport, sack, highest_new_tsn);
1092                 /*
1093                  * SFR-CACC algorithm:
1094                  * C) Let count_of_newacks be the number of
1095                  * destinations for which cacc_saw_newack is set.
1096                  */
1097                 if (transport->cacc.cacc_saw_newack)
1098                         count_of_newacks ++;
1099         }
1100
1101         list_for_each(pos, transport_list) {
1102                 transport  = list_entry(pos, struct sctp_transport,
1103                                         transports);
1104                 sctp_mark_missing(q, &transport->transmitted, transport,
1105                                   highest_new_tsn, count_of_newacks);
1106         }
1107
1108         /* Move the Cumulative TSN Ack Point if appropriate.  */
1109         if (TSN_lt(asoc->ctsn_ack_point, sack_ctsn))
1110                 asoc->ctsn_ack_point = sack_ctsn;
1111
1112         /* Update unack_data field in the assoc. */
1113         sctp_sack_update_unack_data(asoc, sack);
1114
1115         ctsn = asoc->ctsn_ack_point;
1116
1117         /* Throw away stuff rotting on the sack queue.  */
1118         list_for_each_safe(lchunk, temp, &q->sacked) {
1119                 tchunk = list_entry(lchunk, struct sctp_chunk,
1120                                     transmitted_list);
1121                 tsn = ntohl(tchunk->subh.data_hdr->tsn);
1122                 if (TSN_lte(tsn, ctsn))
1123                         sctp_chunk_free(tchunk);
1124         }
1125
1126         /* ii) Set rwnd equal to the newly received a_rwnd minus the
1127          *     number of bytes still outstanding after processing the
1128          *     Cumulative TSN Ack and the Gap Ack Blocks.
1129          */
1130
1131         sack_a_rwnd = ntohl(sack->a_rwnd);
1132         outstanding = q->outstanding_bytes;
1133
1134         if (outstanding < sack_a_rwnd)
1135                 sack_a_rwnd -= outstanding;
1136         else
1137                 sack_a_rwnd = 0;
1138
1139         asoc->peer.rwnd = sack_a_rwnd;
1140
1141         sctp_generate_fwdtsn(q, sack_ctsn);
1142
1143         SCTP_DEBUG_PRINTK("%s: sack Cumulative TSN Ack is 0x%x.\n",
1144                           __FUNCTION__, sack_ctsn);
1145         SCTP_DEBUG_PRINTK("%s: Cumulative TSN Ack of association, "
1146                           "%p is 0x%x. Adv peer ack point: 0x%x\n",
1147                           __FUNCTION__, asoc, ctsn, asoc->adv_peer_ack_point);
1148
1149         /* See if all chunks are acked.
1150          * Make sure the empty queue handler will get run later.
1151          */
1152         q->empty = skb_queue_empty(&q->out) && skb_queue_empty(&q->control) &&
1153                         list_empty(&q->retransmit);
1154         if (!q->empty)
1155                 goto finish;
1156
1157         list_for_each(pos, transport_list) {
1158                 transport  = list_entry(pos, struct sctp_transport,
1159                                         transports);
1160                 q->empty = q->empty && list_empty(&transport->transmitted);
1161                 if (!q->empty)
1162                         goto finish;
1163         }
1164
1165         SCTP_DEBUG_PRINTK("sack queue is empty.\n");
1166 finish:
1167         return q->empty;
1168 }
1169
1170 /* Is the outqueue empty?  */
1171 int sctp_outq_is_empty(const struct sctp_outq *q)
1172 {
1173         return q->empty;
1174 }
1175
1176 /********************************************************************
1177  * 2nd Level Abstractions
1178  ********************************************************************/
1179
1180 /* Go through a transport's transmitted list or the association's retransmit
1181  * list and move chunks that are acked by the Cumulative TSN Ack to q->sacked.
1182  * The retransmit list will not have an associated transport.
1183  *
1184  * I added coherent debug information output.   --xguo
1185  *
1186  * Instead of printing 'sacked' or 'kept' for each TSN on the
1187  * transmitted_queue, we print a range: SACKED: TSN1-TSN2, TSN3, TSN4-TSN5.
1188  * KEPT TSN6-TSN7, etc.
1189  */
1190 static void sctp_check_transmitted(struct sctp_outq *q,
1191                                    struct list_head *transmitted_queue,
1192                                    struct sctp_transport *transport,
1193                                    struct sctp_sackhdr *sack,
1194                                    __u32 highest_new_tsn_in_sack)
1195 {
1196         struct list_head *lchunk;
1197         struct sctp_chunk *tchunk;
1198         struct list_head tlist;
1199         __u32 tsn;
1200         __u32 sack_ctsn;
1201         __u32 rtt;
1202         __u8 restart_timer = 0;
1203         int bytes_acked = 0;
1204
1205         /* These state variables are for coherent debug output. --xguo */
1206
1207 #if SCTP_DEBUG
1208         __u32 dbg_ack_tsn = 0;  /* An ACKed TSN range starts here... */
1209         __u32 dbg_last_ack_tsn = 0;  /* ...and finishes here.        */
1210         __u32 dbg_kept_tsn = 0; /* An un-ACKed range starts here...  */
1211         __u32 dbg_last_kept_tsn = 0; /* ...and finishes here.        */
1212
1213         /* 0 : The last TSN was ACKed.
1214          * 1 : The last TSN was NOT ACKed (i.e. KEPT).
1215          * -1: We need to initialize.
1216          */
1217         int dbg_prt_state = -1;
1218 #endif /* SCTP_DEBUG */
1219
1220         sack_ctsn = ntohl(sack->cum_tsn_ack);
1221
1222         INIT_LIST_HEAD(&tlist);
1223
1224         /* The while loop will skip empty transmitted queues. */
1225         while (NULL != (lchunk = sctp_list_dequeue(transmitted_queue))) {
1226                 tchunk = list_entry(lchunk, struct sctp_chunk,
1227                                     transmitted_list);
1228
1229                 if (sctp_chunk_abandoned(tchunk)) {
1230                         /* Move the chunk to abandoned list. */
1231                         sctp_insert_list(&q->abandoned, lchunk);
1232                         continue;
1233                 }
1234
1235                 tsn = ntohl(tchunk->subh.data_hdr->tsn);
1236                 if (sctp_acked(sack, tsn)) {
1237                         /* If this queue is the retransmit queue, the
1238                          * retransmit timer has already reclaimed
1239                          * the outstanding bytes for this chunk, so only
1240                          * count bytes associated with a transport.
1241                          */
1242                         if (transport) {
1243                                 /* If this chunk is being used for RTT
1244                                  * measurement, calculate the RTT and update
1245                                  * the RTO using this value.
1246                                  *
1247                                  * 6.3.1 C5) Karn's algorithm: RTT measurements
1248                                  * MUST NOT be made using packets that were
1249                                  * retransmitted (and thus for which it is
1250                                  * ambiguous whether the reply was for the
1251                                  * first instance of the packet or a later
1252                                  * instance).
1253                                  */
1254                                 if (!tchunk->tsn_gap_acked &&
1255                                     !tchunk->resent &&
1256                                     tchunk->rtt_in_progress) {
1257                                         rtt = jiffies - tchunk->sent_at;
1258                                         sctp_transport_update_rto(transport,
1259                                                                   rtt);
1260                                 }
1261                         }
1262                         if (TSN_lte(tsn, sack_ctsn)) {
1263                                 /* RFC 2960  6.3.2 Retransmission Timer Rules
1264                                  *
1265                                  * R3) Whenever a SACK is received
1266                                  * that acknowledges the DATA chunk
1267                                  * with the earliest outstanding TSN
1268                                  * for that address, restart T3-rtx
1269                                  * timer for that address with its
1270                                  * current RTO.
1271                                  */
1272                                 restart_timer = 1;
1273
1274                                 if (!tchunk->tsn_gap_acked) {
1275                                         tchunk->tsn_gap_acked = 1;
1276                                         bytes_acked += sctp_data_size(tchunk);
1277                                         /*
1278                                          * SFR-CACC algorithm:
1279                                          * 2) If the SACK contains gap acks
1280                                          * and the flag CHANGEOVER_ACTIVE is
1281                                          * set the receiver of the SACK MUST
1282                                          * take the following action:
1283                                          *
1284                                          * B) For each TSN t being acked that
1285                                          * has not been acked in any SACK so
1286                                          * far, set cacc_saw_newack to 1 for
1287                                          * the destination that the TSN was
1288                                          * sent to.
1289                                          */
1290                                         if (transport &&
1291                                             sack->num_gap_ack_blocks &&
1292                                             q->asoc->peer.primary_path->cacc.
1293                                             changeover_active)
1294                                                 transport->cacc.cacc_saw_newack
1295                                                         = 1;
1296                                 }
1297
1298                                 list_add_tail(&tchunk->transmitted_list,
1299                                               &q->sacked);
1300                         } else {
1301                                 /* RFC2960 7.2.4, sctpimpguide-05 2.8.2
1302                                  * M2) Each time a SACK arrives reporting
1303                                  * 'Stray DATA chunk(s)' record the highest TSN
1304                                  * reported as newly acknowledged, call this
1305                                  * value 'HighestTSNinSack'. A newly
1306                                  * acknowledged DATA chunk is one not
1307                                  * previously acknowledged in a SACK.
1308                                  *
1309                                  * When the SCTP sender of data receives a SACK
1310                                  * chunk that acknowledges, for the first time,
1311                                  * the receipt of a DATA chunk, all the still
1312                                  * unacknowledged DATA chunks whose TSN is
1313                                  * older than that newly acknowledged DATA
1314                                  * chunk, are qualified as 'Stray DATA chunks'.
1315                                  */
1316                                 if (!tchunk->tsn_gap_acked) {
1317                                         tchunk->tsn_gap_acked = 1;
1318                                         bytes_acked += sctp_data_size(tchunk);
1319                                 }
1320                                 list_add_tail(lchunk, &tlist);
1321                         }
1322
1323 #if SCTP_DEBUG
1324                         switch (dbg_prt_state) {
1325                         case 0: /* last TSN was ACKed */
1326                                 if (dbg_last_ack_tsn + 1 == tsn) {
1327                                         /* This TSN belongs to the
1328                                          * current ACK range.
1329                                          */
1330                                         break;
1331                                 }
1332
1333                                 if (dbg_last_ack_tsn != dbg_ack_tsn) {
1334                                         /* Display the end of the
1335                                          * current range.
1336                                          */
1337                                         SCTP_DEBUG_PRINTK("-%08x",
1338                                                           dbg_last_ack_tsn);
1339                                 }
1340
1341                                 /* Start a new range.  */
1342                                 SCTP_DEBUG_PRINTK(",%08x", tsn);
1343                                 dbg_ack_tsn = tsn;
1344                                 break;
1345
1346                         case 1: /* The last TSN was NOT ACKed. */
1347                                 if (dbg_last_kept_tsn != dbg_kept_tsn) {
1348                                         /* Display the end of current range. */
1349                                         SCTP_DEBUG_PRINTK("-%08x",
1350                                                           dbg_last_kept_tsn);
1351                                 }
1352
1353                                 SCTP_DEBUG_PRINTK("\n");
1354
1355                                 /* FALL THROUGH... */
1356                         default:
1357                                 /* This is the first-ever TSN we examined.  */
1358                                 /* Start a new range of ACK-ed TSNs.  */
1359                                 SCTP_DEBUG_PRINTK("ACKed: %08x", tsn);
1360                                 dbg_prt_state = 0;
1361                                 dbg_ack_tsn = tsn;
1362                         };
1363
1364                         dbg_last_ack_tsn = tsn;
1365 #endif /* SCTP_DEBUG */
1366
1367                 } else {
1368                         if (tchunk->tsn_gap_acked) {
1369                                 SCTP_DEBUG_PRINTK("%s: Receiver reneged on "
1370                                                   "data TSN: 0x%x\n",
1371                                                   __FUNCTION__,
1372                                                   tsn);
1373                                 tchunk->tsn_gap_acked = 0;
1374
1375                                 bytes_acked -= sctp_data_size(tchunk);
1376
1377                                 /* RFC 2960 6.3.2 Retransmission Timer Rules
1378                                  *
1379                                  * R4) Whenever a SACK is received missing a
1380                                  * TSN that was previously acknowledged via a
1381                                  * Gap Ack Block, start T3-rtx for the
1382                                  * destination address to which the DATA
1383                                  * chunk was originally
1384                                  * transmitted if it is not already running.
1385                                  */
1386                                 restart_timer = 1;
1387                         }
1388
1389                         list_add_tail(lchunk, &tlist);
1390
1391 #if SCTP_DEBUG
1392                         /* See the above comments on ACK-ed TSNs. */
1393                         switch (dbg_prt_state) {
1394                         case 1:
1395                                 if (dbg_last_kept_tsn + 1 == tsn)
1396                                         break;
1397
1398                                 if (dbg_last_kept_tsn != dbg_kept_tsn)
1399                                         SCTP_DEBUG_PRINTK("-%08x",
1400                                                           dbg_last_kept_tsn);
1401
1402                                 SCTP_DEBUG_PRINTK(",%08x", tsn);
1403                                 dbg_kept_tsn = tsn;
1404                                 break;
1405
1406                         case 0:
1407                                 if (dbg_last_ack_tsn != dbg_ack_tsn)
1408                                         SCTP_DEBUG_PRINTK("-%08x",
1409                                                           dbg_last_ack_tsn);
1410                                 SCTP_DEBUG_PRINTK("\n");
1411
1412                                 /* FALL THROUGH... */
1413                         default:
1414                                 SCTP_DEBUG_PRINTK("KEPT: %08x",tsn);
1415                                 dbg_prt_state = 1;
1416                                 dbg_kept_tsn = tsn;
1417                         };
1418
1419                         dbg_last_kept_tsn = tsn;
1420 #endif /* SCTP_DEBUG */
1421                 }
1422         }
1423
1424 #if SCTP_DEBUG
1425         /* Finish off the last range, displaying its ending TSN.  */
1426         switch (dbg_prt_state) {
1427         case 0:
1428                 if (dbg_last_ack_tsn != dbg_ack_tsn) {
1429                         SCTP_DEBUG_PRINTK("-%08x\n", dbg_last_ack_tsn);
1430                 } else {
1431                         SCTP_DEBUG_PRINTK("\n");
1432                 }
1433         break;
1434
1435         case 1:
1436                 if (dbg_last_kept_tsn != dbg_kept_tsn) {
1437                         SCTP_DEBUG_PRINTK("-%08x\n", dbg_last_kept_tsn);
1438                 } else {
1439                         SCTP_DEBUG_PRINTK("\n");
1440                 }
1441         };
1442 #endif /* SCTP_DEBUG */
1443         if (transport) {
1444                 if (bytes_acked) {
1445                         /* 8.2. When an outstanding TSN is acknowledged,
1446                          * the endpoint shall clear the error counter of
1447                          * the destination transport address to which the
1448                          * DATA chunk was last sent.
1449                          * The association's overall error counter is
1450                          * also cleared.
1451                          */
1452                         transport->error_count = 0;
1453                         transport->asoc->overall_error_count = 0;
1454
1455                         /* Mark the destination transport address as
1456                          * active if it is not so marked.
1457                          */
1458                         if (transport->state == SCTP_INACTIVE) {
1459                                 sctp_assoc_control_transport(
1460                                         transport->asoc,
1461                                         transport,
1462                                         SCTP_TRANSPORT_UP,
1463                                         SCTP_RECEIVED_SACK);
1464                         }
1465
1466                         sctp_transport_raise_cwnd(transport, sack_ctsn,
1467                                                   bytes_acked);
1468
1469                         transport->flight_size -= bytes_acked;
1470                         q->outstanding_bytes -= bytes_acked;
1471                 } else {
1472                         /* RFC 2960 6.1, sctpimpguide-06 2.15.2
1473                          * When a sender is doing zero window probing, it
1474                          * should not timeout the association if it continues
1475                          * to receive new packets from the receiver. The
1476                          * reason is that the receiver MAY keep its window
1477                          * closed for an indefinite time.
1478                          * A sender is doing zero window probing when the
1479                          * receiver's advertised window is zero, and there is
1480                          * only one data chunk in flight to the receiver.
1481                          */
1482                         if (!q->asoc->peer.rwnd &&
1483                             !list_empty(&tlist) &&
1484                             (sack_ctsn+2 == q->asoc->next_tsn)) {
1485                                 SCTP_DEBUG_PRINTK("%s: SACK received for zero "
1486                                                   "window probe: %u\n",
1487                                                   __FUNCTION__, sack_ctsn);
1488                                 q->asoc->overall_error_count = 0;
1489                                 transport->error_count = 0;
1490                         }
1491                 }
1492
1493                 /* RFC 2960 6.3.2 Retransmission Timer Rules
1494                  *
1495                  * R2) Whenever all outstanding data sent to an address have
1496                  * been acknowledged, turn off the T3-rtx timer of that
1497                  * address.
1498                  */
1499                 if (!transport->flight_size) {
1500                         if (timer_pending(&transport->T3_rtx_timer) &&
1501                             del_timer(&transport->T3_rtx_timer)) {
1502                                 sctp_transport_put(transport);
1503                         }
1504                 } else if (restart_timer) {
1505                         if (!mod_timer(&transport->T3_rtx_timer,
1506                                        jiffies + transport->rto))
1507                                 sctp_transport_hold(transport);
1508                 }
1509         }
1510
1511         list_splice(&tlist, transmitted_queue);
1512 }
1513
1514 /* Mark chunks as missing and consequently may get retransmitted. */
1515 static void sctp_mark_missing(struct sctp_outq *q,
1516                               struct list_head *transmitted_queue,
1517                               struct sctp_transport *transport,
1518                               __u32 highest_new_tsn_in_sack,
1519                               int count_of_newacks)
1520 {
1521         struct sctp_chunk *chunk;
1522         struct list_head *pos;
1523         __u32 tsn;
1524         char do_fast_retransmit = 0;
1525         struct sctp_transport *primary = q->asoc->peer.primary_path;
1526
1527         list_for_each(pos, transmitted_queue) {
1528
1529                 chunk = list_entry(pos, struct sctp_chunk, transmitted_list);
1530                 tsn = ntohl(chunk->subh.data_hdr->tsn);
1531
1532                 /* RFC 2960 7.2.4, sctpimpguide-05 2.8.2 M3) Examine all
1533                  * 'Unacknowledged TSN's', if the TSN number of an
1534                  * 'Unacknowledged TSN' is smaller than the 'HighestTSNinSack'
1535                  * value, increment the 'TSN.Missing.Report' count on that
1536                  * chunk if it has NOT been fast retransmitted or marked for
1537                  * fast retransmit already.
1538                  */
1539                 if (!chunk->fast_retransmit &&
1540                     !chunk->tsn_gap_acked &&
1541                     TSN_lt(tsn, highest_new_tsn_in_sack)) {
1542
1543                         /* SFR-CACC may require us to skip marking
1544                          * this chunk as missing.
1545                          */
1546                         if (!transport || !sctp_cacc_skip(primary, transport,
1547                                             count_of_newacks, tsn)) {
1548                                 chunk->tsn_missing_report++;
1549
1550                                 SCTP_DEBUG_PRINTK(
1551                                         "%s: TSN 0x%x missing counter: %d\n",
1552                                         __FUNCTION__, tsn,
1553                                         chunk->tsn_missing_report);
1554                         }
1555                 }
1556                 /*
1557                  * M4) If any DATA chunk is found to have a
1558                  * 'TSN.Missing.Report'
1559                  * value larger than or equal to 4, mark that chunk for
1560                  * retransmission and start the fast retransmit procedure.
1561                  */
1562
1563                 if (chunk->tsn_missing_report >= 4) {
1564                         chunk->fast_retransmit = 1;
1565                         do_fast_retransmit = 1;
1566                 }
1567         }
1568
1569         if (transport) {
1570                 if (do_fast_retransmit)
1571                         sctp_retransmit(q, transport, SCTP_RTXR_FAST_RTX);
1572
1573                 SCTP_DEBUG_PRINTK("%s: transport: %p, cwnd: %d, "
1574                                   "ssthresh: %d, flight_size: %d, pba: %d\n",
1575                                   __FUNCTION__, transport, transport->cwnd,
1576                                   transport->ssthresh, transport->flight_size,
1577                                   transport->partial_bytes_acked);
1578         }
1579 }
1580
1581 /* Is the given TSN acked by this packet?  */
1582 static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn)
1583 {
1584         int i;
1585         sctp_sack_variable_t *frags;
1586         __u16 gap;
1587         __u32 ctsn = ntohl(sack->cum_tsn_ack);
1588
1589         if (TSN_lte(tsn, ctsn))
1590                 goto pass;
1591
1592         /* 3.3.4 Selective Acknowledgement (SACK) (3):
1593          *
1594          * Gap Ack Blocks:
1595          *  These fields contain the Gap Ack Blocks. They are repeated
1596          *  for each Gap Ack Block up to the number of Gap Ack Blocks
1597          *  defined in the Number of Gap Ack Blocks field. All DATA
1598          *  chunks with TSNs greater than or equal to (Cumulative TSN
1599          *  Ack + Gap Ack Block Start) and less than or equal to
1600          *  (Cumulative TSN Ack + Gap Ack Block End) of each Gap Ack
1601          *  Block are assumed to have been received correctly.
1602          */
1603
1604         frags = sack->variable;
1605         gap = tsn - ctsn;
1606         for (i = 0; i < ntohs(sack->num_gap_ack_blocks); ++i) {
1607                 if (TSN_lte(ntohs(frags[i].gab.start), gap) &&
1608                     TSN_lte(gap, ntohs(frags[i].gab.end)))
1609                         goto pass;
1610         }
1611
1612         return 0;
1613 pass:
1614         return 1;
1615 }
1616
1617 static inline int sctp_get_skip_pos(struct sctp_fwdtsn_skip *skiplist,
1618                                     int nskips, __u16 stream)
1619 {
1620         int i;
1621
1622         for (i = 0; i < nskips; i++) {
1623                 if (skiplist[i].stream == stream)
1624                         return i;
1625         }
1626         return i;
1627 }
1628
1629 /* Create and add a fwdtsn chunk to the outq's control queue if needed. */
1630 static void sctp_generate_fwdtsn(struct sctp_outq *q, __u32 ctsn)
1631 {
1632         struct sctp_association *asoc = q->asoc;
1633         struct sctp_chunk *ftsn_chunk = NULL;
1634         struct sctp_fwdtsn_skip ftsn_skip_arr[10];
1635         int nskips = 0;
1636         int skip_pos = 0;
1637         __u32 tsn;
1638         struct sctp_chunk *chunk;
1639         struct list_head *lchunk, *temp;
1640
1641         /* PR-SCTP C1) Let SackCumAck be the Cumulative TSN ACK carried in the
1642          * received SACK.
1643          * 
1644          * If (Advanced.Peer.Ack.Point < SackCumAck), then update
1645          * Advanced.Peer.Ack.Point to be equal to SackCumAck.
1646          */
1647         if (TSN_lt(asoc->adv_peer_ack_point, ctsn))
1648                 asoc->adv_peer_ack_point = ctsn;
1649
1650         /* PR-SCTP C2) Try to further advance the "Advanced.Peer.Ack.Point"
1651          * locally, that is, to move "Advanced.Peer.Ack.Point" up as long as
1652          * the chunk next in the out-queue space is marked as "abandoned" as
1653          * shown in the following example:
1654          *
1655          * Assuming that a SACK arrived with the Cumulative TSN ACK 102
1656          * and the Advanced.Peer.Ack.Point is updated to this value:
1657          * 
1658          *   out-queue at the end of  ==>   out-queue after Adv.Ack.Point
1659          *   normal SACK processing           local advancement
1660          *                ...                           ...
1661          *   Adv.Ack.Pt-> 102 acked                     102 acked
1662          *                103 abandoned                 103 abandoned
1663          *                104 abandoned     Adv.Ack.P-> 104 abandoned
1664          *                105                           105
1665          *                106 acked                     106 acked
1666          *                ...                           ...
1667          *
1668          * In this example, the data sender successfully advanced the
1669          * "Advanced.Peer.Ack.Point" from 102 to 104 locally.
1670          */
1671         list_for_each_safe(lchunk, temp, &q->abandoned) {
1672                 chunk = list_entry(lchunk, struct sctp_chunk,
1673                                         transmitted_list);
1674                 tsn = ntohl(chunk->subh.data_hdr->tsn);
1675
1676                 /* Remove any chunks in the abandoned queue that are acked by
1677                  * the ctsn.
1678                  */ 
1679                 if (TSN_lte(tsn, ctsn)) {
1680                         list_del_init(lchunk);
1681                         if (!chunk->tsn_gap_acked) {
1682                         chunk->transport->flight_size -=
1683                                                  sctp_data_size(chunk);
1684                         q->outstanding_bytes -= sctp_data_size(chunk);
1685                         }
1686                         sctp_chunk_free(chunk);
1687                 } else {
1688                         if (TSN_lte(tsn, asoc->adv_peer_ack_point+1)) {
1689                                 asoc->adv_peer_ack_point = tsn;
1690                                 if (chunk->chunk_hdr->flags &
1691                                          SCTP_DATA_UNORDERED)
1692                                         continue;
1693                                 skip_pos = sctp_get_skip_pos(&ftsn_skip_arr[0],
1694                                                 nskips,
1695                                                 chunk->subh.data_hdr->stream);
1696                                 ftsn_skip_arr[skip_pos].stream =
1697                                         chunk->subh.data_hdr->stream;
1698                                 ftsn_skip_arr[skip_pos].ssn =
1699                                          chunk->subh.data_hdr->ssn;
1700                                 if (skip_pos == nskips)
1701                                         nskips++;
1702                                 if (nskips == 10)
1703                                         break;
1704                         } else
1705                                 break;
1706                 }
1707         }
1708
1709         /* PR-SCTP C3) If, after step C1 and C2, the "Advanced.Peer.Ack.Point"
1710          * is greater than the Cumulative TSN ACK carried in the received
1711          * SACK, the data sender MUST send the data receiver a FORWARD TSN
1712          * chunk containing the latest value of the
1713          * "Advanced.Peer.Ack.Point".
1714          *
1715          * C4) For each "abandoned" TSN the sender of the FORWARD TSN SHOULD
1716          * list each stream and sequence number in the forwarded TSN. This
1717          * information will enable the receiver to easily find any
1718          * stranded TSN's waiting on stream reorder queues. Each stream
1719          * SHOULD only be reported once; this means that if multiple
1720          * abandoned messages occur in the same stream then only the
1721          * highest abandoned stream sequence number is reported. If the
1722          * total size of the FORWARD TSN does NOT fit in a single MTU then
1723          * the sender of the FORWARD TSN SHOULD lower the
1724          * Advanced.Peer.Ack.Point to the last TSN that will fit in a
1725          * single MTU.
1726          */
1727         if (asoc->adv_peer_ack_point > ctsn)
1728                 ftsn_chunk = sctp_make_fwdtsn(asoc, asoc->adv_peer_ack_point,
1729                                               nskips, &ftsn_skip_arr[0]); 
1730
1731         if (ftsn_chunk) {
1732                 __skb_queue_tail(&q->control, (struct sk_buff *)ftsn_chunk);
1733                 SCTP_INC_STATS(SCTP_MIB_OUTCTRLCHUNKS);
1734         }
1735 }