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         list_add(&ch->list, &q->out_chunk_list);
  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 = NULL;
  87
  88         if (!list_empty(&q->out_chunk_list)) {
  89                 struct list_head *entry = q->out_chunk_list.next;
  90
  91                 ch = list_entry(entry, struct sctp_chunk, list);
  92                 list_del_init(entry);
  93                 q->out_qlen -= ch->skb->len;
  94         }
  95         return ch;
  96 }
  97 /* Add data chunk to the end of the queue. */
  98 static inline void sctp_outq_tail_data(struct sctp_outq *q,
  99                                        struct sctp_chunk *ch)
 100 {
 101         list_add_tail(&ch->list, &q->out_chunk_list);
 102         q->out_qlen += ch->skb->len;
 103         return;
 104 }
 105
 106 /*
 107  * SFR-CACC algorithm:
 108  * D) If count_of_newacks is greater than or equal to 2
 109  * and t was not sent to the current primary then the
 110  * sender MUST NOT increment missing report count for t.
 111  */
 112 static inline int sctp_cacc_skip_3_1_d(struct sctp_transport *primary,
 113                                        struct sctp_transport *transport,
 114                                        int count_of_newacks)
 115 {
 116         if (count_of_newacks >=2 && transport != primary)
 117                 return 1;
 118         return 0;
 119 }
 120
 121 /*
 122  * SFR-CACC algorithm:
 123  * F) If count_of_newacks is less than 2, let d be the
 124  * destination to which t was sent. If cacc_saw_newack
 125  * is 0 for destination d, then the sender MUST NOT
 126  * increment missing report count for t.
 127  */
 128 static inline int sctp_cacc_skip_3_1_f(struct sctp_transport *transport,
 129                                        int count_of_newacks)
 130 {
 131         if (count_of_newacks < 2 && !transport->cacc.cacc_saw_newack)
 132                 return 1;
 133         return 0;
 134 }
 135
 136 /*
 137  * SFR-CACC algorithm:
 138  * 3.1) If CYCLING_CHANGEOVER is 0, the sender SHOULD
 139  * execute steps C, D, F.
 140  *
 141  * C has been implemented in sctp_outq_sack
 142  */
 143 static inline int sctp_cacc_skip_3_1(struct sctp_transport *primary,
 144                                      struct sctp_transport *transport,
 145                                      int count_of_newacks)
 146 {
 147         if (!primary->cacc.cycling_changeover) {
 148                 if (sctp_cacc_skip_3_1_d(primary, transport, count_of_newacks))
 149                         return 1;
 150                 if (sctp_cacc_skip_3_1_f(transport, count_of_newacks))
 151                         return 1;
 152                 return 0;
 153         }
 154         return 0;
 155 }
 156
 157 /*
 158  * SFR-CACC algorithm:
 159  * 3.2) Else if CYCLING_CHANGEOVER is 1, and t is less
 160  * than next_tsn_at_change of the current primary, then
 161  * the sender MUST NOT increment missing report count
 162  * for t.
 163  */
 164 static inline int sctp_cacc_skip_3_2(struct sctp_transport *primary, __u32 tsn)
 165 {
 166         if (primary->cacc.cycling_changeover &&
 167             TSN_lt(tsn, primary->cacc.next_tsn_at_change))
 168                 return 1;
 169         return 0;
 170 }
 171
 172 /*
 173  * SFR-CACC algorithm:
 174  * 3) If the missing report count for TSN t is to be
 175  * incremented according to [RFC2960] and
 176  * [SCTP_STEWART-2002], and CHANGEOVER_ACTIVE is set,
 177  * then the sender MUST futher execute steps 3.1 and
 178  * 3.2 to determine if the missing report count for
 179  * TSN t SHOULD NOT be incremented.
 180  *
 181  * 3.3) If 3.1 and 3.2 do not dictate that the missing
 182  * report count for t should not be incremented, then
 183  * the sender SOULD increment missing report count for
 184  * t (according to [RFC2960] and [SCTP_STEWART_2002]).
 185  */
 186 static inline int sctp_cacc_skip(struct sctp_transport *primary,
 187                                  struct sctp_transport *transport,
 188                                  int count_of_newacks,
 189                                  __u32 tsn)
 190 {
 191         if (primary->cacc.changeover_active &&
 192             (sctp_cacc_skip_3_1(primary, transport, count_of_newacks)
 193              || sctp_cacc_skip_3_2(primary, tsn)))
 194                 return 1;
 195         return 0;
 196 }
 197
 198 /* Initialize an existing sctp_outq.  This does the boring stuff.
 199  * You still need to define handlers if you really want to DO
 200  * something with this structure...
 201  */
 202 void sctp_outq_init(struct sctp_association *asoc, struct sctp_outq *q)
 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         q->outstanding_bytes = 0;
 212         q->empty = 1;
 213         q->cork  = 0;
 214
 215         q->malloced = 0;
 216         q->out_qlen = 0;
 217 }
 218
 219 /* Free the outqueue structure and any related pending chunks.
 220  */
 221 void sctp_outq_teardown(struct sctp_outq *q)
 222 {
 223         struct sctp_transport *transport;
 224         struct list_head *lchunk, *pos, *temp;
 225         struct sctp_chunk *chunk, *tmp;
 226
 227         /* Throw away unacknowledged chunks. */
 228         list_for_each(pos, &q->asoc->peer.transport_addr_list) {
 229                 transport = list_entry(pos, struct sctp_transport, transports);
 230                 while ((lchunk = sctp_list_dequeue(&transport->transmitted)) != NULL) {
 231                         chunk = list_entry(lchunk, struct sctp_chunk,
 232                                            transmitted_list);
 233                         /* Mark as part of a failed message. */
 234                         sctp_chunk_fail(chunk, q->error);
 235                         sctp_chunk_free(chunk);
 236                 }
 237         }
 238
 239         /* Throw away chunks that have been gap ACKed.  */
 240         list_for_each_safe(lchunk, temp, &q->sacked) {
 241                 list_del_init(lchunk);
 242                 chunk = list_entry(lchunk, struct sctp_chunk,
 243                                    transmitted_list);
 244                 sctp_chunk_fail(chunk, q->error);
 245                 sctp_chunk_free(chunk);
 246         }
 247
 248         /* Throw away any chunks in the retransmit queue. */
 249         list_for_each_safe(lchunk, temp, &q->retransmit) {
 250                 list_del_init(lchunk);
 251                 chunk = list_entry(lchunk, struct sctp_chunk,
 252                                    transmitted_list);
 253                 sctp_chunk_fail(chunk, q->error);
 254                 sctp_chunk_free(chunk);
 255         }
 256
 257         /* Throw away any chunks that are in the abandoned queue. */
 258         list_for_each_safe(lchunk, temp, &q->abandoned) {
 259                 list_del_init(lchunk);
 260                 chunk = list_entry(lchunk, struct sctp_chunk,
 261                                    transmitted_list);
 262                 sctp_chunk_fail(chunk, q->error);
 263                 sctp_chunk_free(chunk);
 264         }
 265
 266         /* Throw away any leftover data chunks. */
 267         while ((chunk = sctp_outq_dequeue_data(q)) != NULL) {
 268
 269                 /* Mark as send failure. */
 270                 sctp_chunk_fail(chunk, q->error);
 271                 sctp_chunk_free(chunk);
 272         }
 273
 274         q->error = 0;
 275
 276         /* Throw away any leftover control chunks. */
 277         list_for_each_entry_safe(chunk, tmp, &q->control_chunk_list, list) {
 278                 list_del_init(&chunk->list);
 279                 sctp_chunk_free(chunk);
 280         }
 281 }
 282
 283 /* Free the outqueue structure and any related pending chunks.  */
 284 void sctp_outq_free(struct sctp_outq *q)
 285 {
 286         /* Throw away leftover chunks. */
 287         sctp_outq_teardown(q);
 288
 289         /* If we were kmalloc()'d, free the memory.  */
 290         if (q->malloced)
 291                 kfree(q);
 292 }
 293
 294 /* Put a new chunk in an sctp_outq.  */
 295 int sctp_outq_tail(struct sctp_outq *q, struct sctp_chunk *chunk)
 296 {
 297         int error = 0;
 298
 299         SCTP_DEBUG_PRINTK("sctp_outq_tail(%p, %p[%s])\n",
 300                           q, chunk, chunk && chunk->chunk_hdr ?
 301                           sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type))
 302                           : "Illegal Chunk");
 303
 304         /* If it is data, queue it up, otherwise, send it
 305          * immediately.
 306          */
 307         if (SCTP_CID_DATA == chunk->chunk_hdr->type) {
 308                 /* Is it OK to queue data chunks?  */
 309                 /* From 9. Termination of Association
 310                  *
 311                  * When either endpoint performs a shutdown, the
 312                  * association on each peer will stop accepting new
 313                  * data from its user and only deliver data in queue
 314                  * at the time of sending or receiving the SHUTDOWN
 315                  * chunk.
 316                  */
 317                 switch (q->asoc->state) {
 318                 case SCTP_STATE_EMPTY:
 319                 case SCTP_STATE_CLOSED:
 320                 case SCTP_STATE_SHUTDOWN_PENDING:
 321                 case SCTP_STATE_SHUTDOWN_SENT:
 322                 case SCTP_STATE_SHUTDOWN_RECEIVED:
 323                 case SCTP_STATE_SHUTDOWN_ACK_SENT:
 324                         /* Cannot send after transport endpoint shutdown */
 325                         error = -ESHUTDOWN;
 326                         break;
 327
 328                 default:
 329                         SCTP_DEBUG_PRINTK("outqueueing (%p, %p[%s])\n",
 330                           q, chunk, chunk && chunk->chunk_hdr ?
 331                           sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type))
 332                           : "Illegal Chunk");
 333
 334                         sctp_outq_tail_data(q, chunk);
 335                         if (chunk->chunk_hdr->flags & SCTP_DATA_UNORDERED)
 336                                 SCTP_INC_STATS(SCTP_MIB_OUTUNORDERCHUNKS);
 337                         else
 338                                 SCTP_INC_STATS(SCTP_MIB_OUTORDERCHUNKS);
 339                         q->empty = 0;
 340                         break;
 341                 };
 342         } else {
 343                 list_add_tail(&chunk->list, &q->control_chunk_list);
 344                 SCTP_INC_STATS(SCTP_MIB_OUTCTRLCHUNKS);
 345         }
 346
 347         if (error < 0)
 348                 return error;
 349
 350         if (!q->cork)
 351                 error = sctp_outq_flush(q, 0);
 352
 353         return error;
 354 }
 355
 356 /* Insert a chunk into the sorted list based on the TSNs.  The retransmit list
 357  * and the abandoned list are in ascending order.
 358  */
 359 static void sctp_insert_list(struct list_head *head, struct list_head *new)
 360 {
 361         struct list_head *pos;
 362         struct sctp_chunk *nchunk, *lchunk;
 363         __u32 ntsn, ltsn;
 364         int done = 0;
 365
 366         nchunk = list_entry(new, struct sctp_chunk, transmitted_list);
 367         ntsn = ntohl(nchunk->subh.data_hdr->tsn);
 368
 369         list_for_each(pos, head) {
 370                 lchunk = list_entry(pos, struct sctp_chunk, transmitted_list);
 371                 ltsn = ntohl(lchunk->subh.data_hdr->tsn);
 372                 if (TSN_lt(ntsn, ltsn)) {
 373                         list_add(new, pos->prev);
 374                         done = 1;
 375                         break;
 376                 }
 377         }
 378         if (!done)
 379                 list_add_tail(new, head);
 380 }
 381
 382 /* Mark all the eligible packets on a transport for retransmission.  */
 383 void sctp_retransmit_mark(struct sctp_outq *q,
 384                           struct sctp_transport *transport,
 385                           __u8 fast_retransmit)
 386 {
 387         struct list_head *lchunk, *ltemp;
 388         struct sctp_chunk *chunk;
 389
 390         /* Walk through the specified transmitted queue.  */
 391         list_for_each_safe(lchunk, ltemp, &transport->transmitted) {
 392                 chunk = list_entry(lchunk, struct sctp_chunk,
 393                                    transmitted_list);
 394
 395                 /* If the chunk is abandoned, move it to abandoned list. */
 396                 if (sctp_chunk_abandoned(chunk)) {
 397                         list_del_init(lchunk);
 398                         sctp_insert_list(&q->abandoned, lchunk);
 399                         continue;
 400                 }
 401
 402                 /* If we are doing retransmission due to a fast retransmit,
 403                  * only the chunk's that are marked for fast retransmit
 404                  * should be added to the retransmit queue.  If we are doing
 405                  * retransmission due to a timeout or pmtu discovery, only the
 406                  * chunks that are not yet acked should be added to the
 407                  * retransmit queue.
 408                  */
 409                 if ((fast_retransmit && (chunk->fast_retransmit > 0)) ||
 410                    (!fast_retransmit && !chunk->tsn_gap_acked)) {
 411                         /* RFC 2960 6.2.1 Processing a Received SACK
 412                          *
 413                          * C) Any time a DATA chunk is marked for
 414                          * retransmission (via either T3-rtx timer expiration
 415                          * (Section 6.3.3) or via fast retransmit
 416                          * (Section 7.2.4)), add the data size of those
 417                          * chunks to the rwnd.
 418                          */
 419                         q->asoc->peer.rwnd += (sctp_data_size(chunk) +
 420                                                 sizeof(struct sk_buff));
 421                         q->outstanding_bytes -= sctp_data_size(chunk);
 422                         transport->flight_size -= sctp_data_size(chunk);
 423
 424                         /* sctpimpguide-05 Section 2.8.2
 425                          * M5) If a T3-rtx timer expires, the
 426                          * 'TSN.Missing.Report' of all affected TSNs is set
 427                          * to 0.
 428                          */
 429                         chunk->tsn_missing_report = 0;
 430
 431                         /* If a chunk that is being used for RTT measurement
 432                          * has to be retransmitted, we cannot use this chunk
 433                          * anymore for RTT measurements. Reset rto_pending so
 434                          * that a new RTT measurement is started when a new
 435                          * data chunk is sent.
 436                          */
 437                         if (chunk->rtt_in_progress) {
 438                                 chunk->rtt_in_progress = 0;
 439                                 transport->rto_pending = 0;
 440                         }
 441
 442                         /* Move the chunk to the retransmit queue. The chunks
 443                          * on the retransmit queue are always kept in order.
 444                          */
 445                         list_del_init(lchunk);
 446                         sctp_insert_list(&q->retransmit, lchunk);
 447                 }
 448         }
 449
 450         SCTP_DEBUG_PRINTK("%s: transport: %p, fast_retransmit: %d, "
 451                           "cwnd: %d, ssthresh: %d, flight_size: %d, "
 452                           "pba: %d\n", __FUNCTION__,
 453                           transport, fast_retransmit,
 454                           transport->cwnd, transport->ssthresh,
 455                           transport->flight_size,
 456                           transport->partial_bytes_acked);
 457
 458 }
 459
 460 /* Mark all the eligible packets on a transport for retransmission and force
 461  * one packet out.
 462  */
 463 void sctp_retransmit(struct sctp_outq *q, struct sctp_transport *transport,
 464                      sctp_retransmit_reason_t reason)
 465 {
 466         int error = 0;
 467         __u8 fast_retransmit = 0;
 468
 469         switch(reason) {
 470         case SCTP_RTXR_T3_RTX:
 471                 SCTP_INC_STATS(SCTP_MIB_T3_RETRANSMITS);
 472                 sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_T3_RTX);
 473                 /* Update the retran path if the T3-rtx timer has expired for
 474                  * the current retran path.
 475                  */
 476                 if (transport == transport->asoc->peer.retran_path)
 477                         sctp_assoc_update_retran_path(transport->asoc);
 478                 break;
 479         case SCTP_RTXR_FAST_RTX:
 480                 SCTP_INC_STATS(SCTP_MIB_FAST_RETRANSMITS);
 481                 sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_FAST_RTX);
 482                 fast_retransmit = 1;
 483                 break;
 484         case SCTP_RTXR_PMTUD:
 485                 SCTP_INC_STATS(SCTP_MIB_PMTUD_RETRANSMITS);
 486                 break;
 487         default:
 488                 BUG();
 489         }
 490
 491         sctp_retransmit_mark(q, transport, fast_retransmit);
 492
 493         /* PR-SCTP A5) Any time the T3-rtx timer expires, on any destination,
 494          * the sender SHOULD try to advance the "Advanced.Peer.Ack.Point" by
 495          * following the procedures outlined in C1 - C5.
 496          */
 497         sctp_generate_fwdtsn(q, q->asoc->ctsn_ack_point);
 498
 499         error = sctp_outq_flush(q, /* rtx_timeout */ 1);
 500
 501         if (error)
 502                 q->asoc->base.sk->sk_err = -error;
 503 }
 504
 505 /*
 506  * Transmit DATA chunks on the retransmit queue.  Upon return from
 507  * sctp_outq_flush_rtx() the packet 'pkt' may contain chunks which
 508  * need to be transmitted by the caller.
 509  * We assume that pkt->transport has already been set.
 510  *
 511  * The return value is a normal kernel error return value.
 512  */
 513 static int sctp_outq_flush_rtx(struct sctp_outq *q, struct sctp_packet *pkt,
 514                                int rtx_timeout, int *start_timer)
 515 {
 516         struct list_head *lqueue;
 517         struct list_head *lchunk, *lchunk1;
 518         struct sctp_transport *transport = pkt->transport;
 519         sctp_xmit_t status;
 520         struct sctp_chunk *chunk, *chunk1;
 521         struct sctp_association *asoc;
 522         int error = 0;
 523
 524         asoc = q->asoc;
 525         lqueue = &q->retransmit;
 526
 527         /* RFC 2960 6.3.3 Handle T3-rtx Expiration
 528          *
 529          * E3) Determine how many of the earliest (i.e., lowest TSN)
 530          * outstanding DATA chunks for the address for which the
 531          * T3-rtx has expired will fit into a single packet, subject
 532          * to the MTU constraint for the path corresponding to the
 533          * destination transport address to which the retransmission
 534          * is being sent (this may be different from the address for
 535          * which the timer expires [see Section 6.4]). Call this value
 536          * K. Bundle and retransmit those K DATA chunks in a single
 537          * packet to the destination endpoint.
 538          *
 539          * [Just to be painfully clear, if we are retransmitting
 540          * because a timeout just happened, we should send only ONE
 541          * packet of retransmitted data.]
 542          */
 543         lchunk = sctp_list_dequeue(lqueue);
 544
 545         while (lchunk) {
 546                 chunk = list_entry(lchunk, struct sctp_chunk,
 547                                    transmitted_list);
 548
 549                 /* Make sure that Gap Acked TSNs are not retransmitted.  A
 550                  * simple approach is just to move such TSNs out of the
 551                  * way and into a 'transmitted' queue and skip to the
 552                  * next chunk.
 553                  */
 554                 if (chunk->tsn_gap_acked) {
 555                         list_add_tail(lchunk, &transport->transmitted);
 556                         lchunk = sctp_list_dequeue(lqueue);
 557                         continue;
 558                 }
 559
 560                 /* Attempt to append this chunk to the packet. */
 561                 status = sctp_packet_append_chunk(pkt, chunk);
 562
 563                 switch (status) {
 564                 case SCTP_XMIT_PMTU_FULL:
 565                         /* Send this packet.  */
 566                         if ((error = sctp_packet_transmit(pkt)) == 0)
 567                                 *start_timer = 1;
 568
 569                         /* If we are retransmitting, we should only
 570                          * send a single packet.
 571                          */
 572                         if (rtx_timeout) {
 573                                 list_add(lchunk, lqueue);
 574                                 lchunk = NULL;
 575                         }
 576
 577                         /* Bundle lchunk in the next round.  */
 578                         break;
 579
 580                 case SCTP_XMIT_RWND_FULL:
 581                         /* Send this packet. */
 582                         if ((error = sctp_packet_transmit(pkt)) == 0)
 583                                 *start_timer = 1;
 584
 585                         /* Stop sending DATA as there is no more room
 586                          * at the receiver.
 587                          */
 588                         list_add(lchunk, lqueue);
 589                         lchunk = NULL;
 590                         break;
 591
 592                 case SCTP_XMIT_NAGLE_DELAY:
 593                         /* Send this packet. */
 594                         if ((error = sctp_packet_transmit(pkt)) == 0)
 595                                 *start_timer = 1;
 596
 597                         /* Stop sending DATA because of nagle delay. */
 598                         list_add(lchunk, lqueue);
 599                         lchunk = NULL;
 600                         break;
 601
 602                 default:
 603                         /* The append was successful, so add this chunk to
 604                          * the transmitted list.
 605                          */
 606                         list_add_tail(lchunk, &transport->transmitted);
 607
 608                         /* Mark the chunk as ineligible for fast retransmit
 609                          * after it is retransmitted.
 610                          */
 611                         if (chunk->fast_retransmit > 0)
 612                                 chunk->fast_retransmit = -1;
 613
 614                         *start_timer = 1;
 615                         q->empty = 0;
 616
 617                         /* Retrieve a new chunk to bundle. */
 618                         lchunk = sctp_list_dequeue(lqueue);
 619                         break;
 620                 };
 621
 622                 /* If we are here due to a retransmit timeout or a fast
 623                  * retransmit and if there are any chunks left in the retransmit
 624                  * queue that could not fit in the PMTU sized packet, they need                  * to be marked as ineligible for a subsequent fast retransmit.
 625                  */
 626                 if (rtx_timeout && !lchunk) {
 627                         list_for_each(lchunk1, lqueue) {
 628                                 chunk1 = list_entry(lchunk1, struct sctp_chunk,
 629                                                     transmitted_list);
 630                                 if (chunk1->fast_retransmit > 0)
 631                                         chunk1->fast_retransmit = -1;
 632                         }
 633                 }
 634         }
 635
 636         return error;
 637 }
 638
 639 /* Cork the outqueue so queued chunks are really queued. */
 640 int sctp_outq_uncork(struct sctp_outq *q)
 641 {
 642         int error = 0;
 643         if (q->cork) {
 644                 q->cork = 0;
 645                 error = sctp_outq_flush(q, 0);
 646         }
 647         return error;
 648 }
 649
 650 /*
 651  * Try to flush an outqueue.
 652  *
 653  * Description: Send everything in q which we legally can, subject to
 654  * congestion limitations.
 655  * * Note: This function can be called from multiple contexts so appropriate
 656  * locking concerns must be made.  Today we use the sock lock to protect
 657  * this function.
 658  */
 659 int sctp_outq_flush(struct sctp_outq *q, int rtx_timeout)
 660 {
 661         struct sctp_packet *packet;
 662         struct sctp_packet singleton;
 663         struct sctp_association *asoc = q->asoc;
 664         __u16 sport = asoc->base.bind_addr.port;
 665         __u16 dport = asoc->peer.port;
 666         __u32 vtag = asoc->peer.i.init_tag;
 667         struct sctp_transport *transport = NULL;
 668         struct sctp_transport *new_transport;
 669         struct sctp_chunk *chunk, *tmp;
 670         sctp_xmit_t status;
 671         int error = 0;
 672         int start_timer = 0;
 673
 674         /* These transports have chunks to send. */
 675         struct list_head transport_list;
 676         struct list_head *ltransport;
 677
 678         INIT_LIST_HEAD(&transport_list);
 679         packet = NULL;
 680
 681         /*
 682          * 6.10 Bundling
 683          *   ...
 684          *   When bundling control chunks with DATA chunks, an
 685          *   endpoint MUST place control chunks first in the outbound
 686          *   SCTP packet.  The transmitter MUST transmit DATA chunks
 687          *   within a SCTP packet in increasing order of TSN.
 688          *   ...
 689          */
 690
 691         list_for_each_entry_safe(chunk, tmp, &q->control_chunk_list, list) {
 692                 list_del_init(&chunk->list);
 693
 694                 /* Pick the right transport to use. */
 695                 new_transport = chunk->transport;
 696
 697                 if (!new_transport) {
 698                         new_transport = asoc->peer.active_path;
 699                 } else if ((new_transport->state == SCTP_INACTIVE) ||
 700                            (new_transport->state == SCTP_UNCONFIRMED)) {
 701                         /* If the chunk is Heartbeat or Heartbeat Ack,
 702                          * send it to chunk->transport, even if it's
 703                          * inactive.
 704                          *
 705                          * 3.3.6 Heartbeat Acknowledgement:
 706                          * ...
 707                          * A HEARTBEAT ACK is always sent to the source IP
 708                          * address of the IP datagram containing the
 709                          * HEARTBEAT chunk to which this ack is responding.
 710                          * ...
 711                          */
 712                         if (chunk->chunk_hdr->type != SCTP_CID_HEARTBEAT &&
 713                             chunk->chunk_hdr->type != SCTP_CID_HEARTBEAT_ACK)
 714                                 new_transport = asoc->peer.active_path;
 715                 }
 716
 717                 /* Are we switching transports?
 718                  * Take care of transport locks.
 719                  */
 720                 if (new_transport != transport) {
 721                         transport = new_transport;
 722                         if (list_empty(&transport->send_ready)) {
 723                                 list_add_tail(&transport->send_ready,
 724                                               &transport_list);
 725                         }
 726                         packet = &transport->packet;
 727                         sctp_packet_config(packet, vtag,
 728                                            asoc->peer.ecn_capable);
 729                 }
 730
 731                 switch (chunk->chunk_hdr->type) {
 732                 /*
 733                  * 6.10 Bundling
 734                  *   ...
 735                  *   An endpoint MUST NOT bundle INIT, INIT ACK or SHUTDOWN
 736                  *   COMPLETE with any other chunks.  [Send them immediately.]
 737                  */
 738                 case SCTP_CID_INIT:
 739                 case SCTP_CID_INIT_ACK:
 740                 case SCTP_CID_SHUTDOWN_COMPLETE:
 741                         sctp_packet_init(&singleton, transport, sport, dport);
 742                         sctp_packet_config(&singleton, vtag, 0);
 743                         sctp_packet_append_chunk(&singleton, chunk);
 744                         error = sctp_packet_transmit(&singleton);
 745                         if (error < 0)
 746                                 return error;
 747                         break;
 748
 749                 case SCTP_CID_ABORT:
 750                 case SCTP_CID_SACK:
 751                 case SCTP_CID_HEARTBEAT:
 752                 case SCTP_CID_HEARTBEAT_ACK:
 753                 case SCTP_CID_SHUTDOWN:
 754                 case SCTP_CID_SHUTDOWN_ACK:
 755                 case SCTP_CID_ERROR:
 756                 case SCTP_CID_COOKIE_ECHO:
 757                 case SCTP_CID_COOKIE_ACK:
 758                 case SCTP_CID_ECN_ECNE:
 759                 case SCTP_CID_ECN_CWR:
 760                 case SCTP_CID_ASCONF:
 761                 case SCTP_CID_ASCONF_ACK:
 762                 case SCTP_CID_FWD_TSN:
 763                         sctp_packet_transmit_chunk(packet, chunk);
 764                         break;
 765
 766                 default:
 767                         /* We built a chunk with an illegal type! */
 768                         BUG();
 769                 };
 770         }
 771
 772         /* Is it OK to send data chunks?  */
 773         switch (asoc->state) {
 774         case SCTP_STATE_COOKIE_ECHOED:
 775                 /* Only allow bundling when this packet has a COOKIE-ECHO
 776                  * chunk.
 777                  */
 778                 if (!packet || !packet->has_cookie_echo)
 779                         break;
 780
 781                 /* fallthru */
 782         case SCTP_STATE_ESTABLISHED:
 783         case SCTP_STATE_SHUTDOWN_PENDING:
 784         case SCTP_STATE_SHUTDOWN_RECEIVED:
 785                 /*
 786                  * RFC 2960 6.1  Transmission of DATA Chunks
 787                  *
 788                  * C) When the time comes for the sender to transmit,
 789                  * before sending new DATA chunks, the sender MUST
 790                  * first transmit any outstanding DATA chunks which
 791                  * are marked for retransmission (limited by the
 792                  * current cwnd).
 793                  */
 794                 if (!list_empty(&q->retransmit)) {
 795                         if (transport == asoc->peer.retran_path)
 796                                 goto retran;
 797
 798                         /* Switch transports & prepare the packet.  */
 799
 800                         transport = asoc->peer.retran_path;
 801
 802                         if (list_empty(&transport->send_ready)) {
 803                                 list_add_tail(&transport->send_ready,
 804                                               &transport_list);
 805                         }
 806
 807                         packet = &transport->packet;
 808                         sctp_packet_config(packet, vtag,
 809                                            asoc->peer.ecn_capable);
 810                 retran:
 811                         error = sctp_outq_flush_rtx(q, packet,
 812                                                     rtx_timeout, &start_timer);
 813
 814                         if (start_timer)
 815                                 sctp_transport_reset_timers(transport);
 816
 817                         /* This can happen on COOKIE-ECHO resend.  Only
 818                          * one chunk can get bundled with a COOKIE-ECHO.
 819                          */
 820                         if (packet->has_cookie_echo)
 821                                 goto sctp_flush_out;
 822
 823                         /* Don't send new data if there is still data
 824                          * waiting to retransmit.
 825                          */
 826                         if (!list_empty(&q->retransmit))
 827                                 goto sctp_flush_out;
 828                 }
 829
 830                 /* Finally, transmit new packets.  */
 831                 start_timer = 0;
 832                 while ((chunk = sctp_outq_dequeue_data(q)) != NULL) {
 833                         /* RFC 2960 6.5 Every DATA chunk MUST carry a valid
 834                          * stream identifier.
 835                          */
 836                         if (chunk->sinfo.sinfo_stream >=
 837                             asoc->c.sinit_num_ostreams) {
 838
 839                                 /* Mark as failed send. */
 840                                 sctp_chunk_fail(chunk, SCTP_ERROR_INV_STRM);
 841                                 sctp_chunk_free(chunk);
 842                                 continue;
 843                         }
 844
 845                         /* Has this chunk expired? */
 846                         if (sctp_chunk_abandoned(chunk)) {
 847                                 sctp_chunk_fail(chunk, 0);
 848                                 sctp_chunk_free(chunk);
 849                                 continue;
 850                         }
 851
 852                         /* If there is a specified transport, use it.
 853                          * Otherwise, we want to use the active path.
 854                          */
 855                         new_transport = chunk->transport;
 856                         if (!new_transport ||
 857                             ((new_transport->state == SCTP_INACTIVE) ||
 858                              (new_transport->state == SCTP_UNCONFIRMED)))
 859                                 new_transport = asoc->peer.active_path;
 860
 861                         /* Change packets if necessary.  */
 862                         if (new_transport != transport) {
 863                                 transport = new_transport;
 864
 865                                 /* Schedule to have this transport's
 866                                  * packet flushed.
 867                                  */
 868                                 if (list_empty(&transport->send_ready)) {
 869                                         list_add_tail(&transport->send_ready,
 870                                                       &transport_list);
 871                                 }
 872
 873                                 packet = &transport->packet;
 874                                 sctp_packet_config(packet, vtag,
 875                                                    asoc->peer.ecn_capable);
 876                         }
 877
 878                         SCTP_DEBUG_PRINTK("sctp_outq_flush(%p, %p[%s]), ",
 879                                           q, chunk,
 880                                           chunk && chunk->chunk_hdr ?
 881                                           sctp_cname(SCTP_ST_CHUNK(
 882                                                   chunk->chunk_hdr->type))
 883                                           : "Illegal Chunk");
 884
 885                         SCTP_DEBUG_PRINTK("TX TSN 0x%x skb->head "
 886                                         "%p skb->users %d.\n",
 887                                         ntohl(chunk->subh.data_hdr->tsn),
 888                                         chunk->skb ?chunk->skb->head : NULL,
 889                                         chunk->skb ?
 890                                         atomic_read(&chunk->skb->users) : -1);
 891
 892                         /* Add the chunk to the packet.  */
 893                         status = sctp_packet_transmit_chunk(packet, chunk);
 894
 895                         switch (status) {
 896                         case SCTP_XMIT_PMTU_FULL:
 897                         case SCTP_XMIT_RWND_FULL:
 898                         case SCTP_XMIT_NAGLE_DELAY:
 899                                 /* We could not append this chunk, so put
 900                                  * the chunk back on the output queue.
 901                                  */
 902                                 SCTP_DEBUG_PRINTK("sctp_outq_flush: could "
 903                                         "not transmit TSN: 0x%x, status: %d\n",
 904                                         ntohl(chunk->subh.data_hdr->tsn),
 905                                         status);
 906                                 sctp_outq_head_data(q, chunk);
 907                                 goto sctp_flush_out;
 908                                 break;
 909
 910                         case SCTP_XMIT_OK:
 911                                 break;
 912
 913                         default:
 914                                 BUG();
 915                         }
 916
 917                         /* BUG: We assume that the sctp_packet_transmit()
 918                          * call below will succeed all the time and add the
 919                          * chunk to the transmitted list and restart the
 920                          * timers.
 921                          * It is possible that the call can fail under OOM
 922                          * conditions.
 923                          *
 924                          * Is this really a problem?  Won't this behave
 925                          * like a lost TSN?
 926                          */
 927                         list_add_tail(&chunk->transmitted_list,
 928                                       &transport->transmitted);
 929
 930                         sctp_transport_reset_timers(transport);
 931
 932                         q->empty = 0;
 933
 934                         /* Only let one DATA chunk get bundled with a
 935                          * COOKIE-ECHO chunk.
 936                          */
 937                         if (packet->has_cookie_echo)
 938                                 goto sctp_flush_out;
 939                 }
 940                 break;
 941
 942         default:
 943                 /* Do nothing.  */
 944                 break;
 945         }
 946
 947 sctp_flush_out:
 948
 949         /* Before returning, examine all the transports touched in
 950          * this call.  Right now, we bluntly force clear all the
 951          * transports.  Things might change after we implement Nagle.
 952          * But such an examination is still required.
 953          *
 954          * --xguo
 955          */
 956         while ((ltransport = sctp_list_dequeue(&transport_list)) != NULL ) {
 957                 struct sctp_transport *t = list_entry(ltransport,
 958                                                       struct sctp_transport,
 959                                                       send_ready);
 960                 packet = &t->packet;
 961                 if (!sctp_packet_empty(packet))
 962                         error = sctp_packet_transmit(packet);
 963         }
 964
 965         return error;
 966 }
 967
 968 /* Update unack_data based on the incoming SACK chunk */
 969 static void sctp_sack_update_unack_data(struct sctp_association *assoc,
 970                                         struct sctp_sackhdr *sack)
 971 {
 972         sctp_sack_variable_t *frags;
 973         __u16 unack_data;
 974         int i;
 975
 976         unack_data = assoc->next_tsn - assoc->ctsn_ack_point - 1;
 977
 978         frags = sack->variable;
 979         for (i = 0; i < ntohs(sack->num_gap_ack_blocks); i++) {
 980                 unack_data -= ((ntohs(frags[i].gab.end) -
 981                                 ntohs(frags[i].gab.start) + 1));
 982         }
 983
 984         assoc->unack_data = unack_data;
 985 }
 986
 987 /* Return the highest new tsn that is acknowledged by the given SACK chunk. */
 988 static __u32 sctp_highest_new_tsn(struct sctp_sackhdr *sack,
 989                                   struct sctp_association *asoc)
 990 {
 991         struct list_head *ltransport, *lchunk;
 992         struct sctp_transport *transport;
 993         struct sctp_chunk *chunk;
 994         __u32 highest_new_tsn, tsn;
 995         struct list_head *transport_list = &asoc->peer.transport_addr_list;
 996
 997         highest_new_tsn = ntohl(sack->cum_tsn_ack);
 998
 999         list_for_each(ltransport, transport_list) {
1000                 transport = list_entry(ltransport, struct sctp_transport,
1001                                        transports);
1002                 list_for_each(lchunk, &transport->transmitted) {
1003                         chunk = list_entry(lchunk, struct sctp_chunk,
1004                                            transmitted_list);
1005                         tsn = ntohl(chunk->subh.data_hdr->tsn);
1006
1007                         if (!chunk->tsn_gap_acked &&
1008                             TSN_lt(highest_new_tsn, tsn) &&
1009                             sctp_acked(sack, tsn))
1010                                 highest_new_tsn = tsn;
1011                 }
1012         }
1013
1014         return highest_new_tsn;
1015 }
1016
1017 /* This is where we REALLY process a SACK.
1018  *
1019  * Process the SACK against the outqueue.  Mostly, this just frees
1020  * things off the transmitted queue.
1021  */
1022 int sctp_outq_sack(struct sctp_outq *q, struct sctp_sackhdr *sack)
1023 {
1024         struct sctp_association *asoc = q->asoc;
1025         struct sctp_transport *transport;
1026         struct sctp_chunk *tchunk = NULL;
1027         struct list_head *lchunk, *transport_list, *pos, *temp;
1028         sctp_sack_variable_t *frags = sack->variable;
1029         __u32 sack_ctsn, ctsn, tsn;
1030         __u32 highest_tsn, highest_new_tsn;
1031         __u32 sack_a_rwnd;
1032         unsigned outstanding;
1033         struct sctp_transport *primary = asoc->peer.primary_path;
1034         int count_of_newacks = 0;
1035
1036         /* Grab the association's destination address list. */
1037         transport_list = &asoc->peer.transport_addr_list;
1038
1039         sack_ctsn = ntohl(sack->cum_tsn_ack);
1040
1041         /*
1042          * SFR-CACC algorithm:
1043          * On receipt of a SACK the sender SHOULD execute the
1044          * following statements.
1045          *
1046          * 1) If the cumulative ack in the SACK passes next tsn_at_change
1047          * on the current primary, the CHANGEOVER_ACTIVE flag SHOULD be
1048          * cleared. The CYCLING_CHANGEOVER flag SHOULD also be cleared for
1049          * all destinations.
1050          */
1051         if (TSN_lte(primary->cacc.next_tsn_at_change, sack_ctsn)) {
1052                 primary->cacc.changeover_active = 0;
1053                 list_for_each(pos, transport_list) {
1054                         transport = list_entry(pos, struct sctp_transport,
1055                                         transports);
1056                         transport->cacc.cycling_changeover = 0;
1057                 }
1058         }
1059
1060         /*
1061          * SFR-CACC algorithm:
1062          * 2) If the SACK contains gap acks and the flag CHANGEOVER_ACTIVE
1063          * is set the receiver of the SACK MUST take the following actions:
1064          *
1065          * A) Initialize the cacc_saw_newack to 0 for all destination
1066          * addresses.
1067          */
1068         if (sack->num_gap_ack_blocks &&
1069             primary->cacc.changeover_active) {
1070                 list_for_each(pos, transport_list) {
1071                         transport = list_entry(pos, struct sctp_transport,
1072                                         transports);
1073                         transport->cacc.cacc_saw_newack = 0;
1074                 }
1075         }
1076
1077         /* Get the highest TSN in the sack. */
1078         highest_tsn = sack_ctsn;
1079         if (sack->num_gap_ack_blocks)
1080                 highest_tsn +=
1081                     ntohs(frags[ntohs(sack->num_gap_ack_blocks) - 1].gab.end);
1082
1083         if (TSN_lt(asoc->highest_sacked, highest_tsn)) {
1084                 highest_new_tsn = highest_tsn;
1085                 asoc->highest_sacked = highest_tsn;
1086         } else {
1087                 highest_new_tsn = sctp_highest_new_tsn(sack, asoc);
1088         }
1089
1090         /* Run through the retransmit queue.  Credit bytes received
1091          * and free those chunks that we can.
1092          */
1093         sctp_check_transmitted(q, &q->retransmit, NULL, sack, highest_new_tsn);
1094         sctp_mark_missing(q, &q->retransmit, NULL, highest_new_tsn, 0);
1095
1096         /* Run through the transmitted queue.
1097          * Credit bytes received and free those chunks which we can.
1098          *
1099          * This is a MASSIVE candidate for optimization.
1100          */
1101         list_for_each(pos, transport_list) {
1102                 transport  = list_entry(pos, struct sctp_transport,
1103                                         transports);
1104                 sctp_check_transmitted(q, &transport->transmitted,
1105                                        transport, sack, highest_new_tsn);
1106                 /*
1107                  * SFR-CACC algorithm:
1108                  * C) Let count_of_newacks be the number of
1109                  * destinations for which cacc_saw_newack is set.
1110                  */
1111                 if (transport->cacc.cacc_saw_newack)
1112                         count_of_newacks ++;
1113         }
1114
1115         list_for_each(pos, transport_list) {
1116                 transport  = list_entry(pos, struct sctp_transport,
1117                                         transports);
1118                 sctp_mark_missing(q, &transport->transmitted, transport,
1119                                   highest_new_tsn, count_of_newacks);
1120         }
1121
1122         /* Move the Cumulative TSN Ack Point if appropriate.  */
1123         if (TSN_lt(asoc->ctsn_ack_point, sack_ctsn))
1124                 asoc->ctsn_ack_point = sack_ctsn;
1125
1126         /* Update unack_data field in the assoc. */
1127         sctp_sack_update_unack_data(asoc, sack);
1128
1129         ctsn = asoc->ctsn_ack_point;
1130
1131         /* Throw away stuff rotting on the sack queue.  */
1132         list_for_each_safe(lchunk, temp, &q->sacked) {
1133                 tchunk = list_entry(lchunk, struct sctp_chunk,
1134                                     transmitted_list);
1135                 tsn = ntohl(tchunk->subh.data_hdr->tsn);
1136                 if (TSN_lte(tsn, ctsn))
1137                         sctp_chunk_free(tchunk);
1138         }
1139
1140         /* ii) Set rwnd equal to the newly received a_rwnd minus the
1141          *     number of bytes still outstanding after processing the
1142          *     Cumulative TSN Ack and the Gap Ack Blocks.
1143          */
1144
1145         sack_a_rwnd = ntohl(sack->a_rwnd);
1146         outstanding = q->outstanding_bytes;
1147
1148         if (outstanding < sack_a_rwnd)
1149                 sack_a_rwnd -= outstanding;
1150         else
1151                 sack_a_rwnd = 0;
1152
1153         asoc->peer.rwnd = sack_a_rwnd;
1154
1155         sctp_generate_fwdtsn(q, sack_ctsn);
1156
1157         SCTP_DEBUG_PRINTK("%s: sack Cumulative TSN Ack is 0x%x.\n",
1158                           __FUNCTION__, sack_ctsn);
1159         SCTP_DEBUG_PRINTK("%s: Cumulative TSN Ack of association, "
1160                           "%p is 0x%x. Adv peer ack point: 0x%x\n",
1161                           __FUNCTION__, asoc, ctsn, asoc->adv_peer_ack_point);
1162
1163         /* See if all chunks are acked.
1164          * Make sure the empty queue handler will get run later.
1165          */
1166         q->empty = (list_empty(&q->out_chunk_list) &&
1167                     list_empty(&q->control_chunk_list) &&
1168                     list_empty(&q->retransmit));
1169         if (!q->empty)
1170                 goto finish;
1171
1172         list_for_each(pos, transport_list) {
1173                 transport  = list_entry(pos, struct sctp_transport,
1174                                         transports);
1175                 q->empty = q->empty && list_empty(&transport->transmitted);
1176                 if (!q->empty)
1177                         goto finish;
1178         }
1179
1180         SCTP_DEBUG_PRINTK("sack queue is empty.\n");
1181 finish:
1182         return q->empty;
1183 }
1184
1185 /* Is the outqueue empty?  */
1186 int sctp_outq_is_empty(const struct sctp_outq *q)
1187 {
1188         return q->empty;
1189 }
1190
1191 /********************************************************************
1192  * 2nd Level Abstractions
1193  ********************************************************************/
1194
1195 /* Go through a transport's transmitted list or the association's retransmit
1196  * list and move chunks that are acked by the Cumulative TSN Ack to q->sacked.
1197  * The retransmit list will not have an associated transport.
1198  *
1199  * I added coherent debug information output.   --xguo
1200  *
1201  * Instead of printing 'sacked' or 'kept' for each TSN on the
1202  * transmitted_queue, we print a range: SACKED: TSN1-TSN2, TSN3, TSN4-TSN5.
1203  * KEPT TSN6-TSN7, etc.
1204  */
1205 static void sctp_check_transmitted(struct sctp_outq *q,
1206                                    struct list_head *transmitted_queue,
1207                                    struct sctp_transport *transport,
1208                                    struct sctp_sackhdr *sack,
1209                                    __u32 highest_new_tsn_in_sack)
1210 {
1211         struct list_head *lchunk;
1212         struct sctp_chunk *tchunk;
1213         struct list_head tlist;
1214         __u32 tsn;
1215         __u32 sack_ctsn;
1216         __u32 rtt;
1217         __u8 restart_timer = 0;
1218         int bytes_acked = 0;
1219
1220         /* These state variables are for coherent debug output. --xguo */
1221
1222 #if SCTP_DEBUG
1223         __u32 dbg_ack_tsn = 0;  /* An ACKed TSN range starts here... */
1224         __u32 dbg_last_ack_tsn = 0;  /* ...and finishes here.        */
1225         __u32 dbg_kept_tsn = 0; /* An un-ACKed range starts here...  */
1226         __u32 dbg_last_kept_tsn = 0; /* ...and finishes here.        */
1227
1228         /* 0 : The last TSN was ACKed.
1229          * 1 : The last TSN was NOT ACKed (i.e. KEPT).
1230          * -1: We need to initialize.
1231          */
1232         int dbg_prt_state = -1;
1233 #endif /* SCTP_DEBUG */
1234
1235         sack_ctsn = ntohl(sack->cum_tsn_ack);
1236
1237         INIT_LIST_HEAD(&tlist);
1238
1239         /* The while loop will skip empty transmitted queues. */
1240         while (NULL != (lchunk = sctp_list_dequeue(transmitted_queue))) {
1241                 tchunk = list_entry(lchunk, struct sctp_chunk,
1242                                     transmitted_list);
1243
1244                 if (sctp_chunk_abandoned(tchunk)) {
1245                         /* Move the chunk to abandoned list. */
1246                         sctp_insert_list(&q->abandoned, lchunk);
1247                         continue;
1248                 }
1249
1250                 tsn = ntohl(tchunk->subh.data_hdr->tsn);
1251                 if (sctp_acked(sack, tsn)) {
1252                         /* If this queue is the retransmit queue, the
1253                          * retransmit timer has already reclaimed
1254                          * the outstanding bytes for this chunk, so only
1255                          * count bytes associated with a transport.
1256                          */
1257                         if (transport) {
1258                                 /* If this chunk is being used for RTT
1259                                  * measurement, calculate the RTT and update
1260                                  * the RTO using this value.
1261                                  *
1262                                  * 6.3.1 C5) Karn's algorithm: RTT measurements
1263                                  * MUST NOT be made using packets that were
1264                                  * retransmitted (and thus for which it is
1265                                  * ambiguous whether the reply was for the
1266                                  * first instance of the packet or a later
1267                                  * instance).
1268                                  */
1269                                 if (!tchunk->tsn_gap_acked &&
1270                                     !tchunk->resent &&
1271                                     tchunk->rtt_in_progress) {
1272                                         tchunk->rtt_in_progress = 0;
1273                                         rtt = jiffies - tchunk->sent_at;
1274                                         sctp_transport_update_rto(transport,
1275                                                                   rtt);
1276                                 }
1277                         }
1278                         if (TSN_lte(tsn, sack_ctsn)) {
1279                                 /* RFC 2960  6.3.2 Retransmission Timer Rules
1280                                  *
1281                                  * R3) Whenever a SACK is received
1282                                  * that acknowledges the DATA chunk
1283                                  * with the earliest outstanding TSN
1284                                  * for that address, restart T3-rtx
1285                                  * timer for that address with its
1286                                  * current RTO.
1287                                  */
1288                                 restart_timer = 1;
1289
1290                                 if (!tchunk->tsn_gap_acked) {
1291                                         tchunk->tsn_gap_acked = 1;
1292                                         bytes_acked += sctp_data_size(tchunk);
1293                                         /*
1294                                          * SFR-CACC algorithm:
1295                                          * 2) If the SACK contains gap acks
1296                                          * and the flag CHANGEOVER_ACTIVE is
1297                                          * set the receiver of the SACK MUST
1298                                          * take the following action:
1299                                          *
1300                                          * B) For each TSN t being acked that
1301                                          * has not been acked in any SACK so
1302                                          * far, set cacc_saw_newack to 1 for
1303                                          * the destination that the TSN was
1304                                          * sent to.
1305                                          */
1306                                         if (transport &&
1307                                             sack->num_gap_ack_blocks &&
1308                                             q->asoc->peer.primary_path->cacc.
1309                                             changeover_active)
1310                                                 transport->cacc.cacc_saw_newack
1311                                                         = 1;
1312                                 }
1313
1314                                 list_add_tail(&tchunk->transmitted_list,
1315                                               &q->sacked);
1316                         } else {
1317                                 /* RFC2960 7.2.4, sctpimpguide-05 2.8.2
1318                                  * M2) Each time a SACK arrives reporting
1319                                  * 'Stray DATA chunk(s)' record the highest TSN
1320                                  * reported as newly acknowledged, call this
1321                                  * value 'HighestTSNinSack'. A newly
1322                                  * acknowledged DATA chunk is one not
1323                                  * previously acknowledged in a SACK.
1324                                  *
1325                                  * When the SCTP sender of data receives a SACK
1326                                  * chunk that acknowledges, for the first time,
1327                                  * the receipt of a DATA chunk, all the still
1328                                  * unacknowledged DATA chunks whose TSN is
1329                                  * older than that newly acknowledged DATA
1330                                  * chunk, are qualified as 'Stray DATA chunks'.
1331                                  */
1332                                 if (!tchunk->tsn_gap_acked) {
1333                                         tchunk->tsn_gap_acked = 1;
1334                                         bytes_acked += sctp_data_size(tchunk);
1335                                 }
1336                                 list_add_tail(lchunk, &tlist);
1337                         }
1338
1339 #if SCTP_DEBUG
1340                         switch (dbg_prt_state) {
1341                         case 0: /* last TSN was ACKed */
1342                                 if (dbg_last_ack_tsn + 1 == tsn) {
1343                                         /* This TSN belongs to the
1344                                          * current ACK range.
1345                                          */
1346                                         break;
1347                                 }
1348
1349                                 if (dbg_last_ack_tsn != dbg_ack_tsn) {
1350                                         /* Display the end of the
1351                                          * current range.
1352                                          */
1353                                         SCTP_DEBUG_PRINTK("-%08x",
1354                                                           dbg_last_ack_tsn);
1355                                 }
1356
1357                                 /* Start a new range.  */
1358                                 SCTP_DEBUG_PRINTK(",%08x", tsn);
1359                                 dbg_ack_tsn = tsn;
1360                                 break;
1361
1362                         case 1: /* The last TSN was NOT ACKed. */
1363                                 if (dbg_last_kept_tsn != dbg_kept_tsn) {
1364                                         /* Display the end of current range. */
1365                                         SCTP_DEBUG_PRINTK("-%08x",
1366                                                           dbg_last_kept_tsn);
1367                                 }
1368
1369                                 SCTP_DEBUG_PRINTK("\n");
1370
1371                                 /* FALL THROUGH... */
1372                         default:
1373                                 /* This is the first-ever TSN we examined.  */
1374                                 /* Start a new range of ACK-ed TSNs.  */
1375                                 SCTP_DEBUG_PRINTK("ACKed: %08x", tsn);
1376                                 dbg_prt_state = 0;
1377                                 dbg_ack_tsn = tsn;
1378                         };
1379
1380                         dbg_last_ack_tsn = tsn;
1381 #endif /* SCTP_DEBUG */
1382
1383                 } else {
1384                         if (tchunk->tsn_gap_acked) {
1385                                 SCTP_DEBUG_PRINTK("%s: Receiver reneged on "
1386                                                   "data TSN: 0x%x\n",
1387                                                   __FUNCTION__,
1388                                                   tsn);
1389                                 tchunk->tsn_gap_acked = 0;
1390
1391                                 bytes_acked -= sctp_data_size(tchunk);
1392
1393                                 /* RFC 2960 6.3.2 Retransmission Timer Rules
1394                                  *
1395                                  * R4) Whenever a SACK is received missing a
1396                                  * TSN that was previously acknowledged via a
1397                                  * Gap Ack Block, start T3-rtx for the
1398                                  * destination address to which the DATA
1399                                  * chunk was originally
1400                                  * transmitted if it is not already running.
1401                                  */
1402                                 restart_timer = 1;
1403                         }
1404
1405                         list_add_tail(lchunk, &tlist);
1406
1407 #if SCTP_DEBUG
1408                         /* See the above comments on ACK-ed TSNs. */
1409                         switch (dbg_prt_state) {
1410                         case 1:
1411                                 if (dbg_last_kept_tsn + 1 == tsn)
1412                                         break;
1413
1414                                 if (dbg_last_kept_tsn != dbg_kept_tsn)
1415                                         SCTP_DEBUG_PRINTK("-%08x",
1416                                                           dbg_last_kept_tsn);
1417
1418                                 SCTP_DEBUG_PRINTK(",%08x", tsn);
1419                                 dbg_kept_tsn = tsn;
1420                                 break;
1421
1422                         case 0:
1423                                 if (dbg_last_ack_tsn != dbg_ack_tsn)
1424                                         SCTP_DEBUG_PRINTK("-%08x",
1425                                                           dbg_last_ack_tsn);
1426                                 SCTP_DEBUG_PRINTK("\n");
1427
1428                                 /* FALL THROUGH... */
1429                         default:
1430                                 SCTP_DEBUG_PRINTK("KEPT: %08x",tsn);
1431                                 dbg_prt_state = 1;
1432                                 dbg_kept_tsn = tsn;
1433                         };
1434
1435                         dbg_last_kept_tsn = tsn;
1436 #endif /* SCTP_DEBUG */
1437                 }
1438         }
1439
1440 #if SCTP_DEBUG
1441         /* Finish off the last range, displaying its ending TSN.  */
1442         switch (dbg_prt_state) {
1443         case 0:
1444                 if (dbg_last_ack_tsn != dbg_ack_tsn) {
1445                         SCTP_DEBUG_PRINTK("-%08x\n", dbg_last_ack_tsn);
1446                 } else {
1447                         SCTP_DEBUG_PRINTK("\n");
1448                 }
1449         break;
1450
1451         case 1:
1452                 if (dbg_last_kept_tsn != dbg_kept_tsn) {
1453                         SCTP_DEBUG_PRINTK("-%08x\n", dbg_last_kept_tsn);
1454                 } else {
1455                         SCTP_DEBUG_PRINTK("\n");
1456                 }
1457         };
1458 #endif /* SCTP_DEBUG */
1459         if (transport) {
1460                 if (bytes_acked) {
1461                         /* 8.2. When an outstanding TSN is acknowledged,
1462                          * the endpoint shall clear the error counter of
1463                          * the destination transport address to which the
1464                          * DATA chunk was last sent.
1465                          * The association's overall error counter is
1466                          * also cleared.
1467                          */
1468                         transport->error_count = 0;
1469                         transport->asoc->overall_error_count = 0;
1470
1471                         /* Mark the destination transport address as
1472                          * active if it is not so marked.
1473                          */
1474                         if ((transport->state == SCTP_INACTIVE) ||
1475                             (transport->state == SCTP_UNCONFIRMED)) {
1476                                 sctp_assoc_control_transport(
1477                                         transport->asoc,
1478                                         transport,
1479                                         SCTP_TRANSPORT_UP,
1480                                         SCTP_RECEIVED_SACK);
1481                         }
1482
1483                         sctp_transport_raise_cwnd(transport, sack_ctsn,
1484                                                   bytes_acked);
1485
1486                         transport->flight_size -= bytes_acked;
1487                         q->outstanding_bytes -= bytes_acked;
1488                 } else {
1489                         /* RFC 2960 6.1, sctpimpguide-06 2.15.2
1490                          * When a sender is doing zero window probing, it
1491                          * should not timeout the association if it continues
1492                          * to receive new packets from the receiver. The
1493                          * reason is that the receiver MAY keep its window
1494                          * closed for an indefinite time.
1495                          * A sender is doing zero window probing when the
1496                          * receiver's advertised window is zero, and there is
1497                          * only one data chunk in flight to the receiver.
1498                          */
1499                         if (!q->asoc->peer.rwnd &&
1500                             !list_empty(&tlist) &&
1501                             (sack_ctsn+2 == q->asoc->next_tsn)) {
1502                                 SCTP_DEBUG_PRINTK("%s: SACK received for zero "
1503                                                   "window probe: %u\n",
1504                                                   __FUNCTION__, sack_ctsn);
1505                                 q->asoc->overall_error_count = 0;
1506                                 transport->error_count = 0;
1507                         }
1508                 }
1509
1510                 /* RFC 2960 6.3.2 Retransmission Timer Rules
1511                  *
1512                  * R2) Whenever all outstanding data sent to an address have
1513                  * been acknowledged, turn off the T3-rtx timer of that
1514                  * address.
1515                  */
1516                 if (!transport->flight_size) {
1517                         if (timer_pending(&transport->T3_rtx_timer) &&
1518                             del_timer(&transport->T3_rtx_timer)) {
1519                                 sctp_transport_put(transport);
1520                         }
1521                 } else if (restart_timer) {
1522                         if (!mod_timer(&transport->T3_rtx_timer,
1523                                        jiffies + transport->rto))
1524                                 sctp_transport_hold(transport);
1525                 }
1526         }
1527
1528         list_splice(&tlist, transmitted_queue);
1529 }
1530
1531 /* Mark chunks as missing and consequently may get retransmitted. */
1532 static void sctp_mark_missing(struct sctp_outq *q,
1533                               struct list_head *transmitted_queue,
1534                               struct sctp_transport *transport,
1535                               __u32 highest_new_tsn_in_sack,
1536                               int count_of_newacks)
1537 {
1538         struct sctp_chunk *chunk;
1539         struct list_head *pos;
1540         __u32 tsn;
1541         char do_fast_retransmit = 0;
1542         struct sctp_transport *primary = q->asoc->peer.primary_path;
1543
1544         list_for_each(pos, transmitted_queue) {
1545
1546                 chunk = list_entry(pos, struct sctp_chunk, transmitted_list);
1547                 tsn = ntohl(chunk->subh.data_hdr->tsn);
1548
1549                 /* RFC 2960 7.2.4, sctpimpguide-05 2.8.2 M3) Examine all
1550                  * 'Unacknowledged TSN's', if the TSN number of an
1551                  * 'Unacknowledged TSN' is smaller than the 'HighestTSNinSack'
1552                  * value, increment the 'TSN.Missing.Report' count on that
1553                  * chunk if it has NOT been fast retransmitted or marked for
1554                  * fast retransmit already.
1555                  */
1556                 if (!chunk->fast_retransmit &&
1557                     !chunk->tsn_gap_acked &&
1558                     TSN_lt(tsn, highest_new_tsn_in_sack)) {
1559
1560                         /* SFR-CACC may require us to skip marking
1561                          * this chunk as missing.
1562                          */
1563                         if (!transport || !sctp_cacc_skip(primary, transport,
1564                                             count_of_newacks, tsn)) {
1565                                 chunk->tsn_missing_report++;
1566
1567                                 SCTP_DEBUG_PRINTK(
1568                                         "%s: TSN 0x%x missing counter: %d\n",
1569                                         __FUNCTION__, tsn,
1570                                         chunk->tsn_missing_report);
1571                         }
1572                 }
1573                 /*
1574                  * M4) If any DATA chunk is found to have a
1575                  * 'TSN.Missing.Report'
1576                  * value larger than or equal to 3, mark that chunk for
1577                  * retransmission and start the fast retransmit procedure.
1578                  */
1579
1580                 if (chunk->tsn_missing_report >= 3) {
1581                         chunk->fast_retransmit = 1;
1582                         do_fast_retransmit = 1;
1583                 }
1584         }
1585
1586         if (transport) {
1587                 if (do_fast_retransmit)
1588                         sctp_retransmit(q, transport, SCTP_RTXR_FAST_RTX);
1589
1590                 SCTP_DEBUG_PRINTK("%s: transport: %p, cwnd: %d, "
1591                                   "ssthresh: %d, flight_size: %d, pba: %d\n",
1592                                   __FUNCTION__, transport, transport->cwnd,
1593                                   transport->ssthresh, transport->flight_size,
1594                                   transport->partial_bytes_acked);
1595         }
1596 }
1597
1598 /* Is the given TSN acked by this packet?  */
1599 static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn)
1600 {
1601         int i;
1602         sctp_sack_variable_t *frags;
1603         __u16 gap;
1604         __u32 ctsn = ntohl(sack->cum_tsn_ack);
1605
1606         if (TSN_lte(tsn, ctsn))
1607                 goto pass;
1608
1609         /* 3.3.4 Selective Acknowledgement (SACK) (3):
1610          *
1611          * Gap Ack Blocks:
1612          *  These fields contain the Gap Ack Blocks. They are repeated
1613          *  for each Gap Ack Block up to the number of Gap Ack Blocks
1614          *  defined in the Number of Gap Ack Blocks field. All DATA
1615          *  chunks with TSNs greater than or equal to (Cumulative TSN
1616          *  Ack + Gap Ack Block Start) and less than or equal to
1617          *  (Cumulative TSN Ack + Gap Ack Block End) of each Gap Ack
1618          *  Block are assumed to have been received correctly.
1619          */
1620
1621         frags = sack->variable;
1622         gap = tsn - ctsn;
1623         for (i = 0; i < ntohs(sack->num_gap_ack_blocks); ++i) {
1624                 if (TSN_lte(ntohs(frags[i].gab.start), gap) &&
1625                     TSN_lte(gap, ntohs(frags[i].gab.end)))
1626                         goto pass;
1627         }
1628
1629         return 0;
1630 pass:
1631         return 1;
1632 }
1633
1634 static inline int sctp_get_skip_pos(struct sctp_fwdtsn_skip *skiplist,
1635                                     int nskips, __be16 stream)
1636 {
1637         int i;
1638
1639         for (i = 0; i < nskips; i++) {
1640                 if (skiplist[i].stream == stream)
1641                         return i;
1642         }
1643         return i;
1644 }
1645
1646 /* Create and add a fwdtsn chunk to the outq's control queue if needed. */
1647 static void sctp_generate_fwdtsn(struct sctp_outq *q, __u32 ctsn)
1648 {
1649         struct sctp_association *asoc = q->asoc;
1650         struct sctp_chunk *ftsn_chunk = NULL;
1651         struct sctp_fwdtsn_skip ftsn_skip_arr[10];
1652         int nskips = 0;
1653         int skip_pos = 0;
1654         __u32 tsn;
1655         struct sctp_chunk *chunk;
1656         struct list_head *lchunk, *temp;
1657
1658         /* PR-SCTP C1) Let SackCumAck be the Cumulative TSN ACK carried in the
1659          * received SACK.
1660          *
1661          * If (Advanced.Peer.Ack.Point < SackCumAck), then update
1662          * Advanced.Peer.Ack.Point to be equal to SackCumAck.
1663          */
1664         if (TSN_lt(asoc->adv_peer_ack_point, ctsn))
1665                 asoc->adv_peer_ack_point = ctsn;
1666
1667         /* PR-SCTP C2) Try to further advance the "Advanced.Peer.Ack.Point"
1668          * locally, that is, to move "Advanced.Peer.Ack.Point" up as long as
1669          * the chunk next in the out-queue space is marked as "abandoned" as
1670          * shown in the following example:
1671          *
1672          * Assuming that a SACK arrived with the Cumulative TSN ACK 102
1673          * and the Advanced.Peer.Ack.Point is updated to this value:
1674          *
1675          *   out-queue at the end of  ==>   out-queue after Adv.Ack.Point
1676          *   normal SACK processing           local advancement
1677          *                ...                           ...
1678          *   Adv.Ack.Pt-> 102 acked                     102 acked
1679          *                103 abandoned                 103 abandoned
1680          *                104 abandoned     Adv.Ack.P-> 104 abandoned
1681          *                105                           105
1682          *                106 acked                     106 acked
1683          *                ...                           ...
1684          *
1685          * In this example, the data sender successfully advanced the
1686          * "Advanced.Peer.Ack.Point" from 102 to 104 locally.
1687          */
1688         list_for_each_safe(lchunk, temp, &q->abandoned) {
1689                 chunk = list_entry(lchunk, struct sctp_chunk,
1690                                         transmitted_list);
1691                 tsn = ntohl(chunk->subh.data_hdr->tsn);
1692
1693                 /* Remove any chunks in the abandoned queue that are acked by
1694                  * the ctsn.
1695                  */
1696                 if (TSN_lte(tsn, ctsn)) {
1697                         list_del_init(lchunk);
1698                         if (!chunk->tsn_gap_acked) {
1699                                 chunk->transport->flight_size -=
1700                                         sctp_data_size(chunk);
1701                                 q->outstanding_bytes -= sctp_data_size(chunk);
1702                         }
1703                         sctp_chunk_free(chunk);
1704                 } else {
1705                         if (TSN_lte(tsn, asoc->adv_peer_ack_point+1)) {
1706                                 asoc->adv_peer_ack_point = tsn;
1707                                 if (chunk->chunk_hdr->flags &
1708                                          SCTP_DATA_UNORDERED)
1709                                         continue;
1710                                 skip_pos = sctp_get_skip_pos(&ftsn_skip_arr[0],
1711                                                 nskips,
1712                                                 chunk->subh.data_hdr->stream);
1713                                 ftsn_skip_arr[skip_pos].stream =
1714                                         chunk->subh.data_hdr->stream;
1715                                 ftsn_skip_arr[skip_pos].ssn =
1716                                          chunk->subh.data_hdr->ssn;
1717                                 if (skip_pos == nskips)
1718                                         nskips++;
1719                                 if (nskips == 10)
1720                                         break;
1721                         } else
1722                                 break;
1723                 }
1724         }
1725
1726         /* PR-SCTP C3) If, after step C1 and C2, the "Advanced.Peer.Ack.Point"
1727          * is greater than the Cumulative TSN ACK carried in the received
1728          * SACK, the data sender MUST send the data receiver a FORWARD TSN
1729          * chunk containing the latest value of the
1730          * "Advanced.Peer.Ack.Point".
1731          *
1732          * C4) For each "abandoned" TSN the sender of the FORWARD TSN SHOULD
1733          * list each stream and sequence number in the forwarded TSN. This
1734          * information will enable the receiver to easily find any
1735          * stranded TSN's waiting on stream reorder queues. Each stream
1736          * SHOULD only be reported once; this means that if multiple
1737          * abandoned messages occur in the same stream then only the
1738          * highest abandoned stream sequence number is reported. If the
1739          * total size of the FORWARD TSN does NOT fit in a single MTU then
1740          * the sender of the FORWARD TSN SHOULD lower the
1741          * Advanced.Peer.Ack.Point to the last TSN that will fit in a
1742          * single MTU.
1743          */
1744         if (asoc->adv_peer_ack_point > ctsn)
1745                 ftsn_chunk = sctp_make_fwdtsn(asoc, asoc->adv_peer_ack_point,
1746                                               nskips, &ftsn_skip_arr[0]);
1747
1748         if (ftsn_chunk) {
1749                 list_add_tail(&ftsn_chunk->list, &q->control_chunk_list);
1750                 SCTP_INC_STATS(SCTP_MIB_OUTCTRLCHUNKS);
1751         }
1752 }