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