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