net/sctp/outqueue.c

   1 /* SCTP kernel implementation
   2  * (C) Copyright IBM Corp. 2001, 2004
   3  * Copyright (c) 1999-2000 Cisco, Inc.
   4  * Copyright (c) 1999-2001 Motorola, Inc.
   5  * Copyright (c) 2001-2003 Intel Corp.
   6  *
   7  * This file is part of the SCTP kernel implementation
   8  *
   9  * These functions implement the sctp_outq class.   The outqueue handles
  10  * bundling and queueing of outgoing SCTP chunks.
  11  *
  12  * This SCTP implementation is free software;
  13  * you can redistribute it and/or modify it under the terms of
  14  * the GNU General Public License as published by
  15  * the Free Software Foundation; either version 2, or (at your option)
  16  * any later version.
  17  *
  18  * This SCTP implementation is distributed in the hope that it
  19  * will be useful, but WITHOUT ANY WARRANTY; without even the implied
  20  *                 ************************
  21  * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  22  * See the GNU General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU General Public License
  25  * along with GNU CC; see the file COPYING.  If not, 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, *temp;
 225         struct sctp_chunk *chunk, *tmp;
 226
 227         /* Throw away unacknowledged chunks. */
 228         list_for_each_entry(transport, &q->asoc->peer.transport_addr_list,
 229                         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 reason)
 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
 400                         /* If this chunk has not been previousely acked,
 401                          * stop considering it 'outstanding'.  Our peer
 402                          * will most likely never see it since it will
 403                          * not be retransmitted
 404                          */
 405                         if (!chunk->tsn_gap_acked) {
 406                                 chunk->transport->flight_size -=
 407                                                 sctp_data_size(chunk);
 408                                 q->outstanding_bytes -= sctp_data_size(chunk);
 409                                 q->asoc->peer.rwnd += (sctp_data_size(chunk) +
 410                                                         sizeof(struct sk_buff));
 411                         }
 412                         continue;
 413                 }
 414
 415                 /* If we are doing  retransmission due to a timeout or pmtu
 416                  * discovery, only the  chunks that are not yet acked should
 417                  * be added to the retransmit queue.
 418                  */
 419                 if ((reason == SCTP_RTXR_FAST_RTX  &&
 420                             (chunk->fast_retransmit > 0)) ||
 421                     (reason != SCTP_RTXR_FAST_RTX  && !chunk->tsn_gap_acked)) {
 422                         /* If this chunk was sent less then 1 rto ago, do not
 423                          * retransmit this chunk, but give the peer time
 424                          * to acknowlege it.  Do this only when
 425                          * retransmitting due to T3 timeout.
 426                          */
 427                         if (reason == SCTP_RTXR_T3_RTX &&
 428                             (jiffies - chunk->sent_at) < transport->last_rto)
 429                                 continue;
 430
 431                         /* RFC 2960 6.2.1 Processing a Received SACK
 432                          *
 433                          * C) Any time a DATA chunk is marked for
 434                          * retransmission (via either T3-rtx timer expiration
 435                          * (Section 6.3.3) or via fast retransmit
 436                          * (Section 7.2.4)), add the data size of those
 437                          * chunks to the rwnd.
 438                          */
 439                         q->asoc->peer.rwnd += (sctp_data_size(chunk) +
 440                                                 sizeof(struct sk_buff));
 441                         q->outstanding_bytes -= sctp_data_size(chunk);
 442                         transport->flight_size -= sctp_data_size(chunk);
 443
 444                         /* sctpimpguide-05 Section 2.8.2
 445                          * M5) If a T3-rtx timer expires, the
 446                          * 'TSN.Missing.Report' of all affected TSNs is set
 447                          * to 0.
 448                          */
 449                         chunk->tsn_missing_report = 0;
 450
 451                         /* If a chunk that is being used for RTT measurement
 452                          * has to be retransmitted, we cannot use this chunk
 453                          * anymore for RTT measurements. Reset rto_pending so
 454                          * that a new RTT measurement is started when a new
 455                          * data chunk is sent.
 456                          */
 457                         if (chunk->rtt_in_progress) {
 458                                 chunk->rtt_in_progress = 0;
 459                                 transport->rto_pending = 0;
 460                         }
 461
 462                         /* Move the chunk to the retransmit queue. The chunks
 463                          * on the retransmit queue are always kept in order.
 464                          */
 465                         list_del_init(lchunk);
 466                         sctp_insert_list(&q->retransmit, lchunk);
 467                 }
 468         }
 469
 470         SCTP_DEBUG_PRINTK("%s: transport: %p, reason: %d, "
 471                           "cwnd: %d, ssthresh: %d, flight_size: %d, "
 472                           "pba: %d\n", __func__,
 473                           transport, reason,
 474                           transport->cwnd, transport->ssthresh,
 475                           transport->flight_size,
 476                           transport->partial_bytes_acked);
 477
 478 }
 479
 480 /* Mark all the eligible packets on a transport for retransmission and force
 481  * one packet out.
 482  */
 483 void sctp_retransmit(struct sctp_outq *q, struct sctp_transport *transport,
 484                      sctp_retransmit_reason_t reason)
 485 {
 486         int error = 0;
 487
 488         switch(reason) {
 489         case SCTP_RTXR_T3_RTX:
 490                 SCTP_INC_STATS(SCTP_MIB_T3_RETRANSMITS);
 491                 sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_T3_RTX);
 492                 /* Update the retran path if the T3-rtx timer has expired for
 493                  * the current retran path.
 494                  */
 495                 if (transport == transport->asoc->peer.retran_path)
 496                         sctp_assoc_update_retran_path(transport->asoc);
 497                 transport->asoc->rtx_data_chunks +=
 498                         transport->asoc->unack_data;
 499                 break;
 500         case SCTP_RTXR_FAST_RTX:
 501                 SCTP_INC_STATS(SCTP_MIB_FAST_RETRANSMITS);
 502                 sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_FAST_RTX);
 503                 break;
 504         case SCTP_RTXR_PMTUD:
 505                 SCTP_INC_STATS(SCTP_MIB_PMTUD_RETRANSMITS);
 506                 break;
 507         case SCTP_RTXR_T1_RTX:
 508                 SCTP_INC_STATS(SCTP_MIB_T1_RETRANSMITS);
 509                 transport->asoc->init_retries++;
 510                 break;
 511         default:
 512                 BUG();
 513         }
 514
 515         sctp_retransmit_mark(q, transport, reason);
 516
 517         /* PR-SCTP A5) Any time the T3-rtx timer expires, on any destination,
 518          * the sender SHOULD try to advance the "Advanced.Peer.Ack.Point" by
 519          * following the procedures outlined in C1 - C5.
 520          */
 521         sctp_generate_fwdtsn(q, q->asoc->ctsn_ack_point);
 522
 523         error = sctp_outq_flush(q, /* rtx_timeout */ 1);
 524
 525         if (error)
 526                 q->asoc->base.sk->sk_err = -error;
 527 }
 528
 529 /*
 530  * Transmit DATA chunks on the retransmit queue.  Upon return from
 531  * sctp_outq_flush_rtx() the packet 'pkt' may contain chunks which
 532  * need to be transmitted by the caller.
 533  * We assume that pkt->transport has already been set.
 534  *
 535  * The return value is a normal kernel error return value.
 536  */
 537 static int sctp_outq_flush_rtx(struct sctp_outq *q, struct sctp_packet *pkt,
 538                                int rtx_timeout, int *start_timer)
 539 {
 540         struct list_head *lqueue;
 541         struct list_head *lchunk;
 542         struct sctp_transport *transport = pkt->transport;
 543         sctp_xmit_t status;
 544         struct sctp_chunk *chunk, *chunk1;
 545         struct sctp_association *asoc;
 546         int error = 0;
 547
 548         asoc = q->asoc;
 549         lqueue = &q->retransmit;
 550
 551         /* RFC 2960 6.3.3 Handle T3-rtx Expiration
 552          *
 553          * E3) Determine how many of the earliest (i.e., lowest TSN)
 554          * outstanding DATA chunks for the address for which the
 555          * T3-rtx has expired will fit into a single packet, subject
 556          * to the MTU constraint for the path corresponding to the
 557          * destination transport address to which the retransmission
 558          * is being sent (this may be different from the address for
 559          * which the timer expires [see Section 6.4]). Call this value
 560          * K. Bundle and retransmit those K DATA chunks in a single
 561          * packet to the destination endpoint.
 562          *
 563          * [Just to be painfully clear, if we are retransmitting
 564          * because a timeout just happened, we should send only ONE
 565          * packet of retransmitted data.]
 566          */
 567         lchunk = sctp_list_dequeue(lqueue);
 568
 569         while (lchunk) {
 570                 chunk = list_entry(lchunk, struct sctp_chunk,
 571                                    transmitted_list);
 572
 573                 /* Make sure that Gap Acked TSNs are not retransmitted.  A
 574                  * simple approach is just to move such TSNs out of the
 575                  * way and into a 'transmitted' queue and skip to the
 576                  * next chunk.
 577                  */
 578                 if (chunk->tsn_gap_acked) {
 579                         list_add_tail(lchunk, &transport->transmitted);
 580                         lchunk = sctp_list_dequeue(lqueue);
 581                         continue;
 582                 }
 583
 584                 /* Attempt to append this chunk to the packet. */
 585                 status = sctp_packet_append_chunk(pkt, chunk);
 586
 587                 switch (status) {
 588                 case SCTP_XMIT_PMTU_FULL:
 589                         /* Send this packet.  */
 590                         if ((error = sctp_packet_transmit(pkt)) == 0)
 591                                 *start_timer = 1;
 592
 593                         /* If we are retransmitting, we should only
 594                          * send a single packet.
 595                          */
 596                         if (rtx_timeout) {
 597                                 list_add(lchunk, lqueue);
 598                                 lchunk = NULL;
 599                         }
 600
 601                         /* Bundle lchunk in the next round.  */
 602                         break;
 603
 604                 case SCTP_XMIT_RWND_FULL:
 605                         /* Send this packet. */
 606                         if ((error = sctp_packet_transmit(pkt)) == 0)
 607                                 *start_timer = 1;
 608
 609                         /* Stop sending DATA as there is no more room
 610                          * at the receiver.
 611                          */
 612                         list_add(lchunk, lqueue);
 613                         lchunk = NULL;
 614                         break;
 615
 616                 case SCTP_XMIT_NAGLE_DELAY:
 617                         /* Send this packet. */
 618                         if ((error = sctp_packet_transmit(pkt)) == 0)
 619                                 *start_timer = 1;
 620
 621                         /* Stop sending DATA because of nagle delay. */
 622                         list_add(lchunk, lqueue);
 623                         lchunk = NULL;
 624                         break;
 625
 626                 default:
 627                         /* The append was successful, so add this chunk to
 628                          * the transmitted list.
 629                          */
 630                         list_add_tail(lchunk, &transport->transmitted);
 631
 632                         /* Mark the chunk as ineligible for fast retransmit
 633                          * after it is retransmitted.
 634                          */
 635                         if (chunk->fast_retransmit > 0)
 636                                 chunk->fast_retransmit = -1;
 637
 638                         *start_timer = 1;
 639                         q->empty = 0;
 640
 641                         /* Retrieve a new chunk to bundle. */
 642                         lchunk = sctp_list_dequeue(lqueue);
 643                         break;
 644                 }
 645
 646                 /* If we are here due to a retransmit timeout or a fast
 647                  * retransmit and if there are any chunks left in the retransmit
 648                  * queue that could not fit in the PMTU sized packet, they need
 649                  * to be marked as ineligible for a subsequent fast retransmit.
 650                  */
 651                 if (rtx_timeout && !lchunk) {
 652                         list_for_each_entry(chunk1, lqueue, transmitted_list) {
 653                                 if (chunk1->fast_retransmit > 0)
 654                                         chunk1->fast_retransmit = -1;
 655                         }
 656                 }
 657         }
 658
 659         return error;
 660 }
 661
 662 /* Cork the outqueue so queued chunks are really queued. */
 663 int sctp_outq_uncork(struct sctp_outq *q)
 664 {
 665         int error = 0;
 666         if (q->cork)
 667                 q->cork = 0;
 668         error = sctp_outq_flush(q, 0);
 669         return error;
 670 }
 671
 672 /*
 673  * Try to flush an outqueue.
 674  *
 675  * Description: Send everything in q which we legally can, subject to
 676  * congestion limitations.
 677  * * Note: This function can be called from multiple contexts so appropriate
 678  * locking concerns must be made.  Today we use the sock lock to protect
 679  * this function.
 680  */
 681 int sctp_outq_flush(struct sctp_outq *q, int rtx_timeout)
 682 {
 683         struct sctp_packet *packet;
 684         struct sctp_packet singleton;
 685         struct sctp_association *asoc = q->asoc;
 686         __u16 sport = asoc->base.bind_addr.port;
 687         __u16 dport = asoc->peer.port;
 688         __u32 vtag = asoc->peer.i.init_tag;
 689         struct sctp_transport *transport = NULL;
 690         struct sctp_transport *new_transport;
 691         struct sctp_chunk *chunk, *tmp;
 692         sctp_xmit_t status;
 693         int error = 0;
 694         int start_timer = 0;
 695
 696         /* These transports have chunks to send. */
 697         struct list_head transport_list;
 698         struct list_head *ltransport;
 699
 700         INIT_LIST_HEAD(&transport_list);
 701         packet = NULL;
 702
 703         /*
 704          * 6.10 Bundling
 705          *   ...
 706          *   When bundling control chunks with DATA chunks, an
 707          *   endpoint MUST place control chunks first in the outbound
 708          *   SCTP packet.  The transmitter MUST transmit DATA chunks
 709          *   within a SCTP packet in increasing order of TSN.
 710          *   ...
 711          */
 712
 713         list_for_each_entry_safe(chunk, tmp, &q->control_chunk_list, list) {
 714                 list_del_init(&chunk->list);
 715
 716                 /* Pick the right transport to use. */
 717                 new_transport = chunk->transport;
 718
 719                 if (!new_transport) {
 720                         /*
 721                          * If we have a prior transport pointer, see if
 722                          * the destination address of the chunk
 723                          * matches the destination address of the
 724                          * current transport.  If not a match, then
 725                          * try to look up the transport with a given
 726                          * destination address.  We do this because
 727                          * after processing ASCONFs, we may have new
 728                          * transports created.
 729                          */
 730                         if (transport &&
 731                             sctp_cmp_addr_exact(&chunk->dest,
 732                                                 &transport->ipaddr))
 733                                         new_transport = transport;
 734                         else
 735                                 new_transport = sctp_assoc_lookup_paddr(asoc,
 736                                                                 &chunk->dest);
 737
 738                         /* if we still don't have a new transport, then
 739                          * use the current active path.
 740                          */
 741                         if (!new_transport)
 742                                 new_transport = asoc->peer.active_path;
 743                 } else if ((new_transport->state == SCTP_INACTIVE) ||
 744                            (new_transport->state == SCTP_UNCONFIRMED)) {
 745                         /* If the chunk is Heartbeat or Heartbeat Ack,
 746                          * send it to chunk->transport, even if it's
 747                          * inactive.
 748                          *
 749                          * 3.3.6 Heartbeat Acknowledgement:
 750                          * ...
 751                          * A HEARTBEAT ACK is always sent to the source IP
 752                          * address of the IP datagram containing the
 753                          * HEARTBEAT chunk to which this ack is responding.
 754                          * ...
 755                          *
 756                          * ASCONF_ACKs also must be sent to the source.
 757                          */
 758                         if (chunk->chunk_hdr->type != SCTP_CID_HEARTBEAT &&
 759                             chunk->chunk_hdr->type != SCTP_CID_HEARTBEAT_ACK &&
 760                             chunk->chunk_hdr->type != SCTP_CID_ASCONF_ACK)
 761                                 new_transport = asoc->peer.active_path;
 762                 }
 763
 764                 /* Are we switching transports?
 765                  * Take care of transport locks.
 766                  */
 767                 if (new_transport != transport) {
 768                         transport = new_transport;
 769                         if (list_empty(&transport->send_ready)) {
 770                                 list_add_tail(&transport->send_ready,
 771                                               &transport_list);
 772                         }
 773                         packet = &transport->packet;
 774                         sctp_packet_config(packet, vtag,
 775                                            asoc->peer.ecn_capable);
 776                 }
 777
 778                 switch (chunk->chunk_hdr->type) {
 779                 /*
 780                  * 6.10 Bundling
 781                  *   ...
 782                  *   An endpoint MUST NOT bundle INIT, INIT ACK or SHUTDOWN
 783                  *   COMPLETE with any other chunks.  [Send them immediately.]
 784                  */
 785                 case SCTP_CID_INIT:
 786                 case SCTP_CID_INIT_ACK:
 787                 case SCTP_CID_SHUTDOWN_COMPLETE:
 788                         sctp_packet_init(&singleton, transport, sport, dport);
 789                         sctp_packet_config(&singleton, vtag, 0);
 790                         sctp_packet_append_chunk(&singleton, chunk);
 791                         error = sctp_packet_transmit(&singleton);
 792                         if (error < 0)
 793                                 return error;
 794                         break;
 795
 796                 case SCTP_CID_ABORT:
 797                         if (sctp_test_T_bit(chunk)) {
 798                                 packet->vtag = asoc->c.my_vtag;
 799                         }
 800                 case SCTP_CID_SACK:
 801                 case SCTP_CID_HEARTBEAT:
 802                 case SCTP_CID_HEARTBEAT_ACK:
 803                 case SCTP_CID_SHUTDOWN:
 804                 case SCTP_CID_SHUTDOWN_ACK:
 805                 case SCTP_CID_ERROR:
 806                 case SCTP_CID_COOKIE_ECHO:
 807                 case SCTP_CID_COOKIE_ACK:
 808                 case SCTP_CID_ECN_ECNE:
 809                 case SCTP_CID_ECN_CWR:
 810                 case SCTP_CID_ASCONF:
 811                 case SCTP_CID_ASCONF_ACK:
 812                 case SCTP_CID_FWD_TSN:
 813                         sctp_packet_transmit_chunk(packet, chunk);
 814                         break;
 815
 816                 default:
 817                         /* We built a chunk with an illegal type! */
 818                         BUG();
 819                 }
 820         }
 821
 822         /* Is it OK to send data chunks?  */
 823         switch (asoc->state) {
 824         case SCTP_STATE_COOKIE_ECHOED:
 825                 /* Only allow bundling when this packet has a COOKIE-ECHO
 826                  * chunk.
 827                  */
 828                 if (!packet || !packet->has_cookie_echo)
 829                         break;
 830
 831                 /* fallthru */
 832         case SCTP_STATE_ESTABLISHED:
 833         case SCTP_STATE_SHUTDOWN_PENDING:
 834         case SCTP_STATE_SHUTDOWN_RECEIVED:
 835                 /*
 836                  * RFC 2960 6.1  Transmission of DATA Chunks
 837                  *
 838                  * C) When the time comes for the sender to transmit,
 839                  * before sending new DATA chunks, the sender MUST
 840                  * first transmit any outstanding DATA chunks which
 841                  * are marked for retransmission (limited by the
 842                  * current cwnd).
 843                  */
 844                 if (!list_empty(&q->retransmit)) {
 845                         if (transport == asoc->peer.retran_path)
 846                                 goto retran;
 847
 848                         /* Switch transports & prepare the packet.  */
 849
 850                         transport = asoc->peer.retran_path;
 851
 852                         if (list_empty(&transport->send_ready)) {
 853                                 list_add_tail(&transport->send_ready,
 854                                               &transport_list);
 855                         }
 856
 857                         packet = &transport->packet;
 858                         sctp_packet_config(packet, vtag,
 859                                            asoc->peer.ecn_capable);
 860                 retran:
 861                         error = sctp_outq_flush_rtx(q, packet,
 862                                                     rtx_timeout, &start_timer);
 863
 864                         if (start_timer)
 865                                 sctp_transport_reset_timers(transport);
 866
 867                         /* This can happen on COOKIE-ECHO resend.  Only
 868                          * one chunk can get bundled with a COOKIE-ECHO.
 869                          */
 870                         if (packet->has_cookie_echo)
 871                                 goto sctp_flush_out;
 872
 873                         /* Don't send new data if there is still data
 874                          * waiting to retransmit.
 875                          */
 876                         if (!list_empty(&q->retransmit))
 877                                 goto sctp_flush_out;
 878                 }
 879
 880                 /* Finally, transmit new packets.  */
 881                 start_timer = 0;
 882                 while ((chunk = sctp_outq_dequeue_data(q)) != NULL) {
 883                         /* RFC 2960 6.5 Every DATA chunk MUST carry a valid
 884                          * stream identifier.
 885                          */
 886                         if (chunk->sinfo.sinfo_stream >=
 887                             asoc->c.sinit_num_ostreams) {
 888
 889                                 /* Mark as failed send. */
 890                                 sctp_chunk_fail(chunk, SCTP_ERROR_INV_STRM);
 891                                 sctp_chunk_free(chunk);
 892                                 continue;
 893                         }
 894
 895                         /* Has this chunk expired? */
 896                         if (sctp_chunk_abandoned(chunk)) {
 897                                 sctp_chunk_fail(chunk, 0);
 898                                 sctp_chunk_free(chunk);
 899                                 continue;
 900                         }
 901
 902                         /* If there is a specified transport, use it.
 903                          * Otherwise, we want to use the active path.
 904                          */
 905                         new_transport = chunk->transport;
 906                         if (!new_transport ||
 907                             ((new_transport->state == SCTP_INACTIVE) ||
 908                              (new_transport->state == SCTP_UNCONFIRMED)))
 909                                 new_transport = asoc->peer.active_path;
 910
 911                         /* Change packets if necessary.  */
 912                         if (new_transport != transport) {
 913                                 transport = new_transport;
 914
 915                                 /* Schedule to have this transport's
 916                                  * packet flushed.
 917                                  */
 918                                 if (list_empty(&transport->send_ready)) {
 919                                         list_add_tail(&transport->send_ready,
 920                                                       &transport_list);
 921                                 }
 922
 923                                 packet = &transport->packet;
 924                                 sctp_packet_config(packet, vtag,
 925                                                    asoc->peer.ecn_capable);
 926                         }
 927
 928                         SCTP_DEBUG_PRINTK("sctp_outq_flush(%p, %p[%s]), ",
 929                                           q, chunk,
 930                                           chunk && chunk->chunk_hdr ?
 931                                           sctp_cname(SCTP_ST_CHUNK(
 932                                                   chunk->chunk_hdr->type))
 933                                           : "Illegal Chunk");
 934
 935                         SCTP_DEBUG_PRINTK("TX TSN 0x%x skb->head "
 936                                         "%p skb->users %d.\n",
 937                                         ntohl(chunk->subh.data_hdr->tsn),
 938                                         chunk->skb ?chunk->skb->head : NULL,
 939                                         chunk->skb ?
 940                                         atomic_read(&chunk->skb->users) : -1);
 941
 942                         /* Add the chunk to the packet.  */
 943                         status = sctp_packet_transmit_chunk(packet, chunk);
 944
 945                         switch (status) {
 946                         case SCTP_XMIT_PMTU_FULL:
 947                         case SCTP_XMIT_RWND_FULL:
 948                         case SCTP_XMIT_NAGLE_DELAY:
 949                                 /* We could not append this chunk, so put
 950                                  * the chunk back on the output queue.
 951                                  */
 952                                 SCTP_DEBUG_PRINTK("sctp_outq_flush: could "
 953                                         "not transmit TSN: 0x%x, status: %d\n",
 954                                         ntohl(chunk->subh.data_hdr->tsn),
 955                                         status);
 956                                 sctp_outq_head_data(q, chunk);
 957                                 goto sctp_flush_out;
 958                                 break;
 959
 960                         case SCTP_XMIT_OK:
 961                                 break;
 962
 963                         default:
 964                                 BUG();
 965                         }
 966
 967                         /* BUG: We assume that the sctp_packet_transmit()
 968                          * call below will succeed all the time and add the
 969                          * chunk to the transmitted list and restart the
 970                          * timers.
 971                          * It is possible that the call can fail under OOM
 972                          * conditions.
 973                          *
 974                          * Is this really a problem?  Won't this behave
 975                          * like a lost TSN?
 976                          */
 977                         list_add_tail(&chunk->transmitted_list,
 978                                       &transport->transmitted);
 979
 980                         sctp_transport_reset_timers(transport);
 981
 982                         q->empty = 0;
 983
 984                         /* Only let one DATA chunk get bundled with a
 985                          * COOKIE-ECHO chunk.
 986                          */
 987                         if (packet->has_cookie_echo)
 988                                 goto sctp_flush_out;
 989                 }
 990                 break;
 991
 992         default:
 993                 /* Do nothing.  */
 994                 break;
 995         }
 996
 997 sctp_flush_out:
 998
 999         /* Before returning, examine all the transports touched in
1000          * this call.  Right now, we bluntly force clear all the
1001          * transports.  Things might change after we implement Nagle.
1002          * But such an examination is still required.
1003          *
1004          * --xguo
1005          */
1006         while ((ltransport = sctp_list_dequeue(&transport_list)) != NULL ) {
1007                 struct sctp_transport *t = list_entry(ltransport,
1008                                                       struct sctp_transport,
1009                                                       send_ready);
1010                 packet = &t->packet;
1011                 if (!sctp_packet_empty(packet))
1012                         error = sctp_packet_transmit(packet);
1013         }
1014
1015         return error;
1016 }
1017
1018 /* Update unack_data based on the incoming SACK chunk */
1019 static void sctp_sack_update_unack_data(struct sctp_association *assoc,
1020                                         struct sctp_sackhdr *sack)
1021 {
1022         sctp_sack_variable_t *frags;
1023         __u16 unack_data;
1024         int i;
1025
1026         unack_data = assoc->next_tsn - assoc->ctsn_ack_point - 1;
1027
1028         frags = sack->variable;
1029         for (i = 0; i < ntohs(sack->num_gap_ack_blocks); i++) {
1030                 unack_data -= ((ntohs(frags[i].gab.end) -
1031                                 ntohs(frags[i].gab.start) + 1));
1032         }
1033
1034         assoc->unack_data = unack_data;
1035 }
1036
1037 /* Return the highest new tsn that is acknowledged by the given SACK chunk. */
1038 static __u32 sctp_highest_new_tsn(struct sctp_sackhdr *sack,
1039                                   struct sctp_association *asoc)
1040 {
1041         struct sctp_transport *transport;
1042         struct sctp_chunk *chunk;
1043         __u32 highest_new_tsn, tsn;
1044         struct list_head *transport_list = &asoc->peer.transport_addr_list;
1045
1046         highest_new_tsn = ntohl(sack->cum_tsn_ack);
1047
1048         list_for_each_entry(transport, transport_list, transports) {
1049                 list_for_each_entry(chunk, &transport->transmitted,
1050                                 transmitted_list) {
1051                         tsn = ntohl(chunk->subh.data_hdr->tsn);
1052
1053                         if (!chunk->tsn_gap_acked &&
1054                             TSN_lt(highest_new_tsn, tsn) &&
1055                             sctp_acked(sack, tsn))
1056                                 highest_new_tsn = tsn;
1057                 }
1058         }
1059
1060         return highest_new_tsn;
1061 }
1062
1063 /* This is where we REALLY process a SACK.
1064  *
1065  * Process the SACK against the outqueue.  Mostly, this just frees
1066  * things off the transmitted queue.
1067  */
1068 int sctp_outq_sack(struct sctp_outq *q, struct sctp_sackhdr *sack)
1069 {
1070         struct sctp_association *asoc = q->asoc;
1071         struct sctp_transport *transport;
1072         struct sctp_chunk *tchunk = NULL;
1073         struct list_head *lchunk, *transport_list, *temp;
1074         sctp_sack_variable_t *frags = sack->variable;
1075         __u32 sack_ctsn, ctsn, tsn;
1076         __u32 highest_tsn, highest_new_tsn;
1077         __u32 sack_a_rwnd;
1078         unsigned outstanding;
1079         struct sctp_transport *primary = asoc->peer.primary_path;
1080         int count_of_newacks = 0;
1081
1082         /* Grab the association's destination address list. */
1083         transport_list = &asoc->peer.transport_addr_list;
1084
1085         sack_ctsn = ntohl(sack->cum_tsn_ack);
1086
1087         /*
1088          * SFR-CACC algorithm:
1089          * On receipt of a SACK the sender SHOULD execute the
1090          * following statements.
1091          *
1092          * 1) If the cumulative ack in the SACK passes next tsn_at_change
1093          * on the current primary, the CHANGEOVER_ACTIVE flag SHOULD be
1094          * cleared. The CYCLING_CHANGEOVER flag SHOULD also be cleared for
1095          * all destinations.
1096          */
1097         if (TSN_lte(primary->cacc.next_tsn_at_change, sack_ctsn)) {
1098                 primary->cacc.changeover_active = 0;
1099                 list_for_each_entry(transport, transport_list,
1100                                 transports) {
1101                         transport->cacc.cycling_changeover = 0;
1102                 }
1103         }
1104
1105         /*
1106          * SFR-CACC algorithm:
1107          * 2) If the SACK contains gap acks and the flag CHANGEOVER_ACTIVE
1108          * is set the receiver of the SACK MUST take the following actions:
1109          *
1110          * A) Initialize the cacc_saw_newack to 0 for all destination
1111          * addresses.
1112          */
1113         if (sack->num_gap_ack_blocks &&
1114             primary->cacc.changeover_active) {
1115                 list_for_each_entry(transport, transport_list, transports) {
1116                         transport->cacc.cacc_saw_newack = 0;
1117                 }
1118         }
1119
1120         /* Get the highest TSN in the sack. */
1121         highest_tsn = sack_ctsn;
1122         if (sack->num_gap_ack_blocks)
1123                 highest_tsn +=
1124                     ntohs(frags[ntohs(sack->num_gap_ack_blocks) - 1].gab.end);
1125
1126         if (TSN_lt(asoc->highest_sacked, highest_tsn)) {
1127                 highest_new_tsn = highest_tsn;
1128                 asoc->highest_sacked = highest_tsn;
1129         } else {
1130                 highest_new_tsn = sctp_highest_new_tsn(sack, asoc);
1131         }
1132
1133         /* Run through the retransmit queue.  Credit bytes received
1134          * and free those chunks that we can.
1135          */
1136         sctp_check_transmitted(q, &q->retransmit, NULL, sack, highest_new_tsn);
1137         sctp_mark_missing(q, &q->retransmit, NULL, highest_new_tsn, 0);
1138
1139         /* Run through the transmitted queue.
1140          * Credit bytes received and free those chunks which we can.
1141          *
1142          * This is a MASSIVE candidate for optimization.
1143          */
1144         list_for_each_entry(transport, transport_list, transports) {
1145                 sctp_check_transmitted(q, &transport->transmitted,
1146                                        transport, sack, highest_new_tsn);
1147                 /*
1148                  * SFR-CACC algorithm:
1149                  * C) Let count_of_newacks be the number of
1150                  * destinations for which cacc_saw_newack is set.
1151                  */
1152                 if (transport->cacc.cacc_saw_newack)
1153                         count_of_newacks ++;
1154         }
1155
1156         list_for_each_entry(transport, transport_list, transports) {
1157                 sctp_mark_missing(q, &transport->transmitted, transport,
1158                                   highest_new_tsn, count_of_newacks);
1159         }
1160
1161         /* Move the Cumulative TSN Ack Point if appropriate.  */
1162         if (TSN_lt(asoc->ctsn_ack_point, sack_ctsn))
1163                 asoc->ctsn_ack_point = sack_ctsn;
1164
1165         /* Update unack_data field in the assoc. */
1166         sctp_sack_update_unack_data(asoc, sack);
1167
1168         ctsn = asoc->ctsn_ack_point;
1169
1170         /* Throw away stuff rotting on the sack queue.  */
1171         list_for_each_safe(lchunk, temp, &q->sacked) {
1172                 tchunk = list_entry(lchunk, struct sctp_chunk,
1173                                     transmitted_list);
1174                 tsn = ntohl(tchunk->subh.data_hdr->tsn);
1175                 if (TSN_lte(tsn, ctsn)) {
1176                         list_del_init(&tchunk->transmitted_list);
1177                         sctp_chunk_free(tchunk);
1178                 }
1179         }
1180
1181         /* ii) Set rwnd equal to the newly received a_rwnd minus the
1182          *     number of bytes still outstanding after processing the
1183          *     Cumulative TSN Ack and the Gap Ack Blocks.
1184          */
1185
1186         sack_a_rwnd = ntohl(sack->a_rwnd);
1187         outstanding = q->outstanding_bytes;
1188
1189         if (outstanding < sack_a_rwnd)
1190                 sack_a_rwnd -= outstanding;
1191         else
1192                 sack_a_rwnd = 0;
1193
1194         asoc->peer.rwnd = sack_a_rwnd;
1195
1196         sctp_generate_fwdtsn(q, sack_ctsn);
1197
1198         SCTP_DEBUG_PRINTK("%s: sack Cumulative TSN Ack is 0x%x.\n",
1199                           __func__, sack_ctsn);
1200         SCTP_DEBUG_PRINTK("%s: Cumulative TSN Ack of association, "
1201                           "%p is 0x%x. Adv peer ack point: 0x%x\n",
1202                           __func__, asoc, ctsn, asoc->adv_peer_ack_point);
1203
1204         /* See if all chunks are acked.
1205          * Make sure the empty queue handler will get run later.
1206          */
1207         q->empty = (list_empty(&q->out_chunk_list) &&
1208                     list_empty(&q->control_chunk_list) &&
1209                     list_empty(&q->retransmit));
1210         if (!q->empty)
1211                 goto finish;
1212
1213         list_for_each_entry(transport, transport_list, transports) {
1214                 q->empty = q->empty && list_empty(&transport->transmitted);
1215                 if (!q->empty)
1216                         goto finish;
1217         }
1218
1219         SCTP_DEBUG_PRINTK("sack queue is empty.\n");
1220 finish:
1221         return q->empty;
1222 }
1223
1224 /* Is the outqueue empty?  */
1225 int sctp_outq_is_empty(const struct sctp_outq *q)
1226 {
1227         return q->empty;
1228 }
1229
1230 /********************************************************************
1231  * 2nd Level Abstractions
1232  ********************************************************************/
1233
1234 /* Go through a transport's transmitted list or the association's retransmit
1235  * list and move chunks that are acked by the Cumulative TSN Ack to q->sacked.
1236  * The retransmit list will not have an associated transport.
1237  *
1238  * I added coherent debug information output.   --xguo
1239  *
1240  * Instead of printing 'sacked' or 'kept' for each TSN on the
1241  * transmitted_queue, we print a range: SACKED: TSN1-TSN2, TSN3, TSN4-TSN5.
1242  * KEPT TSN6-TSN7, etc.
1243  */
1244 static void sctp_check_transmitted(struct sctp_outq *q,
1245                                    struct list_head *transmitted_queue,
1246                                    struct sctp_transport *transport,
1247                                    struct sctp_sackhdr *sack,
1248                                    __u32 highest_new_tsn_in_sack)
1249 {
1250         struct list_head *lchunk;
1251         struct sctp_chunk *tchunk;
1252         struct list_head tlist;
1253         __u32 tsn;
1254         __u32 sack_ctsn;
1255         __u32 rtt;
1256         __u8 restart_timer = 0;
1257         int bytes_acked = 0;
1258
1259         /* These state variables are for coherent debug output. --xguo */
1260
1261 #if SCTP_DEBUG
1262         __u32 dbg_ack_tsn = 0;  /* An ACKed TSN range starts here... */
1263         __u32 dbg_last_ack_tsn = 0;  /* ...and finishes here.        */
1264         __u32 dbg_kept_tsn = 0; /* An un-ACKed range starts here...  */
1265         __u32 dbg_last_kept_tsn = 0; /* ...and finishes here.        */
1266
1267         /* 0 : The last TSN was ACKed.
1268          * 1 : The last TSN was NOT ACKed (i.e. KEPT).
1269          * -1: We need to initialize.
1270          */
1271         int dbg_prt_state = -1;
1272 #endif /* SCTP_DEBUG */
1273
1274         sack_ctsn = ntohl(sack->cum_tsn_ack);
1275
1276         INIT_LIST_HEAD(&tlist);
1277
1278         /* The while loop will skip empty transmitted queues. */
1279         while (NULL != (lchunk = sctp_list_dequeue(transmitted_queue))) {
1280                 tchunk = list_entry(lchunk, struct sctp_chunk,
1281                                     transmitted_list);
1282
1283                 if (sctp_chunk_abandoned(tchunk)) {
1284                         /* Move the chunk to abandoned list. */
1285                         sctp_insert_list(&q->abandoned, lchunk);
1286
1287                         /* If this chunk has not been acked, stop
1288                          * considering it as 'outstanding'.
1289                          */
1290                         if (!tchunk->tsn_gap_acked) {
1291                                 tchunk->transport->flight_size -=
1292                                                 sctp_data_size(tchunk);
1293                                 q->outstanding_bytes -= sctp_data_size(tchunk);
1294                         }
1295                         continue;
1296                 }
1297
1298                 tsn = ntohl(tchunk->subh.data_hdr->tsn);
1299                 if (sctp_acked(sack, tsn)) {
1300                         /* If this queue is the retransmit queue, the
1301                          * retransmit timer has already reclaimed
1302                          * the outstanding bytes for this chunk, so only
1303                          * count bytes associated with a transport.
1304                          */
1305                         if (transport) {
1306                                 /* If this chunk is being used for RTT
1307                                  * measurement, calculate the RTT and update
1308                                  * the RTO using this value.
1309                                  *
1310                                  * 6.3.1 C5) Karn's algorithm: RTT measurements
1311                                  * MUST NOT be made using packets that were
1312                                  * retransmitted (and thus for which it is
1313                                  * ambiguous whether the reply was for the
1314                                  * first instance of the packet or a later
1315                                  * instance).
1316                                  */
1317                                 if (!tchunk->tsn_gap_acked &&
1318                                     !tchunk->resent &&
1319                                     tchunk->rtt_in_progress) {
1320                                         tchunk->rtt_in_progress = 0;
1321                                         rtt = jiffies - tchunk->sent_at;
1322                                         sctp_transport_update_rto(transport,
1323                                                                   rtt);
1324                                 }
1325                         }
1326                         if (TSN_lte(tsn, sack_ctsn)) {
1327                                 /* RFC 2960  6.3.2 Retransmission Timer Rules
1328                                  *
1329                                  * R3) Whenever a SACK is received
1330                                  * that acknowledges the DATA chunk
1331                                  * with the earliest outstanding TSN
1332                                  * for that address, restart T3-rtx
1333                                  * timer for that address with its
1334                                  * current RTO.
1335                                  */
1336                                 restart_timer = 1;
1337
1338                                 if (!tchunk->tsn_gap_acked) {
1339                                         tchunk->tsn_gap_acked = 1;
1340                                         bytes_acked += sctp_data_size(tchunk);
1341                                         /*
1342                                          * SFR-CACC algorithm:
1343                                          * 2) If the SACK contains gap acks
1344                                          * and the flag CHANGEOVER_ACTIVE is
1345                                          * set the receiver of the SACK MUST
1346                                          * take the following action:
1347                                          *
1348                                          * B) For each TSN t being acked that
1349                                          * has not been acked in any SACK so
1350                                          * far, set cacc_saw_newack to 1 for
1351                                          * the destination that the TSN was
1352                                          * sent to.
1353                                          */
1354                                         if (transport &&
1355                                             sack->num_gap_ack_blocks &&
1356                                             q->asoc->peer.primary_path->cacc.
1357                                             changeover_active)
1358                                                 transport->cacc.cacc_saw_newack
1359                                                         = 1;
1360                                 }
1361
1362                                 list_add_tail(&tchunk->transmitted_list,
1363                                               &q->sacked);
1364                         } else {
1365                                 /* RFC2960 7.2.4, sctpimpguide-05 2.8.2
1366                                  * M2) Each time a SACK arrives reporting
1367                                  * 'Stray DATA chunk(s)' record the highest TSN
1368                                  * reported as newly acknowledged, call this
1369                                  * value 'HighestTSNinSack'. A newly
1370                                  * acknowledged DATA chunk is one not
1371                                  * previously acknowledged in a SACK.
1372                                  *
1373                                  * When the SCTP sender of data receives a SACK
1374                                  * chunk that acknowledges, for the first time,
1375                                  * the receipt of a DATA chunk, all the still
1376                                  * unacknowledged DATA chunks whose TSN is
1377                                  * older than that newly acknowledged DATA
1378                                  * chunk, are qualified as 'Stray DATA chunks'.
1379                                  */
1380                                 if (!tchunk->tsn_gap_acked) {
1381                                         tchunk->tsn_gap_acked = 1;
1382                                         bytes_acked += sctp_data_size(tchunk);
1383                                 }
1384                                 list_add_tail(lchunk, &tlist);
1385                         }
1386
1387 #if SCTP_DEBUG
1388                         switch (dbg_prt_state) {
1389                         case 0: /* last TSN was ACKed */
1390                                 if (dbg_last_ack_tsn + 1 == tsn) {
1391                                         /* This TSN belongs to the
1392                                          * current ACK range.
1393                                          */
1394                                         break;
1395                                 }
1396
1397                                 if (dbg_last_ack_tsn != dbg_ack_tsn) {
1398                                         /* Display the end of the
1399                                          * current range.
1400                                          */
1401                                         SCTP_DEBUG_PRINTK("-%08x",
1402                                                           dbg_last_ack_tsn);
1403                                 }
1404
1405                                 /* Start a new range.  */
1406                                 SCTP_DEBUG_PRINTK(",%08x", tsn);
1407                                 dbg_ack_tsn = tsn;
1408                                 break;
1409
1410                         case 1: /* The last TSN was NOT ACKed. */
1411                                 if (dbg_last_kept_tsn != dbg_kept_tsn) {
1412                                         /* Display the end of current range. */
1413                                         SCTP_DEBUG_PRINTK("-%08x",
1414                                                           dbg_last_kept_tsn);
1415                                 }
1416
1417                                 SCTP_DEBUG_PRINTK("\n");
1418
1419                                 /* FALL THROUGH... */
1420                         default:
1421                                 /* This is the first-ever TSN we examined.  */
1422                                 /* Start a new range of ACK-ed TSNs.  */
1423                                 SCTP_DEBUG_PRINTK("ACKed: %08x", tsn);
1424                                 dbg_prt_state = 0;
1425                                 dbg_ack_tsn = tsn;
1426                         }
1427
1428                         dbg_last_ack_tsn = tsn;
1429 #endif /* SCTP_DEBUG */
1430
1431                 } else {
1432                         if (tchunk->tsn_gap_acked) {
1433                                 SCTP_DEBUG_PRINTK("%s: Receiver reneged on "
1434                                                   "data TSN: 0x%x\n",
1435                                                   __func__,
1436                                                   tsn);
1437                                 tchunk->tsn_gap_acked = 0;
1438
1439                                 bytes_acked -= sctp_data_size(tchunk);
1440
1441                                 /* RFC 2960 6.3.2 Retransmission Timer Rules
1442                                  *
1443                                  * R4) Whenever a SACK is received missing a
1444                                  * TSN that was previously acknowledged via a
1445                                  * Gap Ack Block, start T3-rtx for the
1446                                  * destination address to which the DATA
1447                                  * chunk was originally
1448                                  * transmitted if it is not already running.
1449                                  */
1450                                 restart_timer = 1;
1451                         }
1452
1453                         list_add_tail(lchunk, &tlist);
1454
1455 #if SCTP_DEBUG
1456                         /* See the above comments on ACK-ed TSNs. */
1457                         switch (dbg_prt_state) {
1458                         case 1:
1459                                 if (dbg_last_kept_tsn + 1 == tsn)
1460                                         break;
1461
1462                                 if (dbg_last_kept_tsn != dbg_kept_tsn)
1463                                         SCTP_DEBUG_PRINTK("-%08x",
1464                                                           dbg_last_kept_tsn);
1465
1466                                 SCTP_DEBUG_PRINTK(",%08x", tsn);
1467                                 dbg_kept_tsn = tsn;
1468                                 break;
1469
1470                         case 0:
1471                                 if (dbg_last_ack_tsn != dbg_ack_tsn)
1472                                         SCTP_DEBUG_PRINTK("-%08x",
1473                                                           dbg_last_ack_tsn);
1474                                 SCTP_DEBUG_PRINTK("\n");
1475
1476                                 /* FALL THROUGH... */
1477                         default:
1478                                 SCTP_DEBUG_PRINTK("KEPT: %08x",tsn);
1479                                 dbg_prt_state = 1;
1480                                 dbg_kept_tsn = tsn;
1481                         }
1482
1483                         dbg_last_kept_tsn = tsn;
1484 #endif /* SCTP_DEBUG */
1485                 }
1486         }
1487
1488 #if SCTP_DEBUG
1489         /* Finish off the last range, displaying its ending TSN.  */
1490         switch (dbg_prt_state) {
1491         case 0:
1492                 if (dbg_last_ack_tsn != dbg_ack_tsn) {
1493                         SCTP_DEBUG_PRINTK("-%08x\n", dbg_last_ack_tsn);
1494                 } else {
1495                         SCTP_DEBUG_PRINTK("\n");
1496                 }
1497         break;
1498
1499         case 1:
1500                 if (dbg_last_kept_tsn != dbg_kept_tsn) {
1501                         SCTP_DEBUG_PRINTK("-%08x\n", dbg_last_kept_tsn);
1502                 } else {
1503                         SCTP_DEBUG_PRINTK("\n");
1504                 }
1505         }
1506 #endif /* SCTP_DEBUG */
1507         if (transport) {
1508                 if (bytes_acked) {
1509                         /* 8.2. When an outstanding TSN is acknowledged,
1510                          * the endpoint shall clear the error counter of
1511                          * the destination transport address to which the
1512                          * DATA chunk was last sent.
1513                          * The association's overall error counter is
1514                          * also cleared.
1515                          */
1516                         transport->error_count = 0;
1517                         transport->asoc->overall_error_count = 0;
1518
1519                         /* Mark the destination transport address as
1520                          * active if it is not so marked.
1521                          */
1522                         if ((transport->state == SCTP_INACTIVE) ||
1523                             (transport->state == SCTP_UNCONFIRMED)) {
1524                                 sctp_assoc_control_transport(
1525                                         transport->asoc,
1526                                         transport,
1527                                         SCTP_TRANSPORT_UP,
1528                                         SCTP_RECEIVED_SACK);
1529                         }
1530
1531                         sctp_transport_raise_cwnd(transport, sack_ctsn,
1532                                                   bytes_acked);
1533
1534                         transport->flight_size -= bytes_acked;
1535                         q->outstanding_bytes -= bytes_acked;
1536                 } else {
1537                         /* RFC 2960 6.1, sctpimpguide-06 2.15.2
1538                          * When a sender is doing zero window probing, it
1539                          * should not timeout the association if it continues
1540                          * to receive new packets from the receiver. The
1541                          * reason is that the receiver MAY keep its window
1542                          * closed for an indefinite time.
1543                          * A sender is doing zero window probing when the
1544                          * receiver's advertised window is zero, and there is
1545                          * only one data chunk in flight to the receiver.
1546                          */
1547                         if (!q->asoc->peer.rwnd &&
1548                             !list_empty(&tlist) &&
1549                             (sack_ctsn+2 == q->asoc->next_tsn)) {
1550                                 SCTP_DEBUG_PRINTK("%s: SACK received for zero "
1551                                                   "window probe: %u\n",
1552                                                   __func__, sack_ctsn);
1553                                 q->asoc->overall_error_count = 0;
1554                                 transport->error_count = 0;
1555                         }
1556                 }
1557
1558                 /* RFC 2960 6.3.2 Retransmission Timer Rules
1559                  *
1560                  * R2) Whenever all outstanding data sent to an address have
1561                  * been acknowledged, turn off the T3-rtx timer of that
1562                  * address.
1563                  */
1564                 if (!transport->flight_size) {
1565                         if (timer_pending(&transport->T3_rtx_timer) &&
1566                             del_timer(&transport->T3_rtx_timer)) {
1567                                 sctp_transport_put(transport);
1568                         }
1569                 } else if (restart_timer) {
1570                         if (!mod_timer(&transport->T3_rtx_timer,
1571                                        jiffies + transport->rto))
1572                                 sctp_transport_hold(transport);
1573                 }
1574         }
1575
1576         list_splice(&tlist, transmitted_queue);
1577 }
1578
1579 /* Mark chunks as missing and consequently may get retransmitted. */
1580 static void sctp_mark_missing(struct sctp_outq *q,
1581                               struct list_head *transmitted_queue,
1582                               struct sctp_transport *transport,
1583                               __u32 highest_new_tsn_in_sack,
1584                               int count_of_newacks)
1585 {
1586         struct sctp_chunk *chunk;
1587         __u32 tsn;
1588         char do_fast_retransmit = 0;
1589         struct sctp_transport *primary = q->asoc->peer.primary_path;
1590
1591         list_for_each_entry(chunk, transmitted_queue, transmitted_list) {
1592
1593                 tsn = ntohl(chunk->subh.data_hdr->tsn);
1594
1595                 /* RFC 2960 7.2.4, sctpimpguide-05 2.8.2 M3) Examine all
1596                  * 'Unacknowledged TSN's', if the TSN number of an
1597                  * 'Unacknowledged TSN' is smaller than the 'HighestTSNinSack'
1598                  * value, increment the 'TSN.Missing.Report' count on that
1599                  * chunk if it has NOT been fast retransmitted or marked for
1600                  * fast retransmit already.
1601                  */
1602                 if (!chunk->fast_retransmit &&
1603                     !chunk->tsn_gap_acked &&
1604                     TSN_lt(tsn, highest_new_tsn_in_sack)) {
1605
1606                         /* SFR-CACC may require us to skip marking
1607                          * this chunk as missing.
1608                          */
1609                         if (!transport || !sctp_cacc_skip(primary, transport,
1610                                             count_of_newacks, tsn)) {
1611                                 chunk->tsn_missing_report++;
1612
1613                                 SCTP_DEBUG_PRINTK(
1614                                         "%s: TSN 0x%x missing counter: %d\n",
1615                                         __func__, tsn,
1616                                         chunk->tsn_missing_report);
1617                         }
1618                 }
1619                 /*
1620                  * M4) If any DATA chunk is found to have a
1621                  * 'TSN.Missing.Report'
1622                  * value larger than or equal to 3, mark that chunk for
1623                  * retransmission and start the fast retransmit procedure.
1624                  */
1625
1626                 if (chunk->tsn_missing_report >= 3) {
1627                         chunk->fast_retransmit = 1;
1628                         do_fast_retransmit = 1;
1629                 }
1630         }
1631
1632         if (transport) {
1633                 if (do_fast_retransmit)
1634                         sctp_retransmit(q, transport, SCTP_RTXR_FAST_RTX);
1635
1636                 SCTP_DEBUG_PRINTK("%s: transport: %p, cwnd: %d, "
1637                                   "ssthresh: %d, flight_size: %d, pba: %d\n",
1638                                   __func__, transport, transport->cwnd,
1639                                   transport->ssthresh, transport->flight_size,
1640                                   transport->partial_bytes_acked);
1641         }
1642 }
1643
1644 /* Is the given TSN acked by this packet?  */
1645 static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn)
1646 {
1647         int i;
1648         sctp_sack_variable_t *frags;
1649         __u16 gap;
1650         __u32 ctsn = ntohl(sack->cum_tsn_ack);
1651
1652         if (TSN_lte(tsn, ctsn))
1653                 goto pass;
1654
1655         /* 3.3.4 Selective Acknowledgement (SACK) (3):
1656          *
1657          * Gap Ack Blocks:
1658          *  These fields contain the Gap Ack Blocks. They are repeated
1659          *  for each Gap Ack Block up to the number of Gap Ack Blocks
1660          *  defined in the Number of Gap Ack Blocks field. All DATA
1661          *  chunks with TSNs greater than or equal to (Cumulative TSN
1662          *  Ack + Gap Ack Block Start) and less than or equal to
1663          *  (Cumulative TSN Ack + Gap Ack Block End) of each Gap Ack
1664          *  Block are assumed to have been received correctly.
1665          */
1666
1667         frags = sack->variable;
1668         gap = tsn - ctsn;
1669         for (i = 0; i < ntohs(sack->num_gap_ack_blocks); ++i) {
1670                 if (TSN_lte(ntohs(frags[i].gab.start), gap) &&
1671                     TSN_lte(gap, ntohs(frags[i].gab.end)))
1672                         goto pass;
1673         }
1674
1675         return 0;
1676 pass:
1677         return 1;
1678 }
1679
1680 static inline int sctp_get_skip_pos(struct sctp_fwdtsn_skip *skiplist,
1681                                     int nskips, __be16 stream)
1682 {
1683         int i;
1684
1685         for (i = 0; i < nskips; i++) {
1686                 if (skiplist[i].stream == stream)
1687                         return i;
1688         }
1689         return i;
1690 }
1691
1692 /* Create and add a fwdtsn chunk to the outq's control queue if needed. */
1693 static void sctp_generate_fwdtsn(struct sctp_outq *q, __u32 ctsn)
1694 {
1695         struct sctp_association *asoc = q->asoc;
1696         struct sctp_chunk *ftsn_chunk = NULL;
1697         struct sctp_fwdtsn_skip ftsn_skip_arr[10];
1698         int nskips = 0;
1699         int skip_pos = 0;
1700         __u32 tsn;
1701         struct sctp_chunk *chunk;
1702         struct list_head *lchunk, *temp;
1703
1704         /* PR-SCTP C1) Let SackCumAck be the Cumulative TSN ACK carried in the
1705          * received SACK.
1706          *
1707          * If (Advanced.Peer.Ack.Point < SackCumAck), then update
1708          * Advanced.Peer.Ack.Point to be equal to SackCumAck.
1709          */
1710         if (TSN_lt(asoc->adv_peer_ack_point, ctsn))
1711                 asoc->adv_peer_ack_point = ctsn;
1712
1713         /* PR-SCTP C2) Try to further advance the "Advanced.Peer.Ack.Point"
1714          * locally, that is, to move "Advanced.Peer.Ack.Point" up as long as
1715          * the chunk next in the out-queue space is marked as "abandoned" as
1716          * shown in the following example:
1717          *
1718          * Assuming that a SACK arrived with the Cumulative TSN ACK 102
1719          * and the Advanced.Peer.Ack.Point is updated to this value:
1720          *
1721          *   out-queue at the end of  ==>   out-queue after Adv.Ack.Point
1722          *   normal SACK processing           local advancement
1723          *                ...                           ...
1724          *   Adv.Ack.Pt-> 102 acked                     102 acked
1725          *                103 abandoned                 103 abandoned
1726          *                104 abandoned     Adv.Ack.P-> 104 abandoned
1727          *                105                           105
1728          *                106 acked                     106 acked
1729          *                ...                           ...
1730          *
1731          * In this example, the data sender successfully advanced the
1732          * "Advanced.Peer.Ack.Point" from 102 to 104 locally.
1733          */
1734         list_for_each_safe(lchunk, temp, &q->abandoned) {
1735                 chunk = list_entry(lchunk, struct sctp_chunk,
1736                                         transmitted_list);
1737                 tsn = ntohl(chunk->subh.data_hdr->tsn);
1738
1739                 /* Remove any chunks in the abandoned queue that are acked by
1740                  * the ctsn.
1741                  */
1742                 if (TSN_lte(tsn, ctsn)) {
1743                         list_del_init(lchunk);
1744                         sctp_chunk_free(chunk);
1745                 } else {
1746                         if (TSN_lte(tsn, asoc->adv_peer_ack_point+1)) {
1747                                 asoc->adv_peer_ack_point = tsn;
1748                                 if (chunk->chunk_hdr->flags &
1749                                          SCTP_DATA_UNORDERED)
1750                                         continue;
1751                                 skip_pos = sctp_get_skip_pos(&ftsn_skip_arr[0],
1752                                                 nskips,
1753                                                 chunk->subh.data_hdr->stream);
1754                                 ftsn_skip_arr[skip_pos].stream =
1755                                         chunk->subh.data_hdr->stream;
1756                                 ftsn_skip_arr[skip_pos].ssn =
1757                                          chunk->subh.data_hdr->ssn;
1758                                 if (skip_pos == nskips)
1759                                         nskips++;
1760                                 if (nskips == 10)
1761                                         break;
1762                         } else
1763                                 break;
1764                 }
1765         }
1766
1767         /* PR-SCTP C3) If, after step C1 and C2, the "Advanced.Peer.Ack.Point"
1768          * is greater than the Cumulative TSN ACK carried in the received
1769          * SACK, the data sender MUST send the data receiver a FORWARD TSN
1770          * chunk containing the latest value of the
1771          * "Advanced.Peer.Ack.Point".
1772          *
1773          * C4) For each "abandoned" TSN the sender of the FORWARD TSN SHOULD
1774          * list each stream and sequence number in the forwarded TSN. This
1775          * information will enable the receiver to easily find any
1776          * stranded TSN's waiting on stream reorder queues. Each stream
1777          * SHOULD only be reported once; this means that if multiple
1778          * abandoned messages occur in the same stream then only the
1779          * highest abandoned stream sequence number is reported. If the
1780          * total size of the FORWARD TSN does NOT fit in a single MTU then
1781          * the sender of the FORWARD TSN SHOULD lower the
1782          * Advanced.Peer.Ack.Point to the last TSN that will fit in a
1783          * single MTU.
1784          */
1785         if (asoc->adv_peer_ack_point > ctsn)
1786                 ftsn_chunk = sctp_make_fwdtsn(asoc, asoc->adv_peer_ack_point,
1787                                               nskips, &ftsn_skip_arr[0]);
1788
1789         if (ftsn_chunk) {
1790                 list_add_tail(&ftsn_chunk->list, &q->control_chunk_list);
1791                 SCTP_INC_STATS(SCTP_MIB_OUTCTRLCHUNKS);
1792         }
1793 }