net/sctp/outqueue.c

   1 /* SCTP kernel implementation
   2  * (C) Copyright IBM Corp. 2001, 2004
   3  * Copyright (c) 1999-2000 Cisco, Inc.
   4  * Copyright (c) 1999-2001 Motorola, Inc.
   5  * Copyright (c) 2001-2003 Intel Corp.
   6  *
   7  * This file is part of the SCTP kernel implementation
   8  *
   9  * These functions implement the sctp_outq class.   The outqueue handles
  10  * bundling and queueing of outgoing SCTP chunks.
  11  *
  12  * This SCTP implementation is free software;
  13  * you can redistribute it and/or modify it under the terms of
  14  * the GNU General Public License as published by
  15  * the Free Software Foundation; either version 2, or (at your option)
  16  * any later version.
  17  *
  18  * This SCTP implementation is distributed in the hope that it
  19  * will be useful, but WITHOUT ANY WARRANTY; without even the implied
  20  *                 ************************
  21  * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  22  * See the GNU General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU General Public License
  25  * along with GNU CC; see the file COPYING.  If not, see
  26  * <http://www.gnu.org/licenses/>.
  27  *
  28  * Please send any bug reports or fixes you make to the
  29  * email address(es):
  30  *    lksctp developers <linux-sctp@vger.kernel.org>
  31  *
  32  * Written or modified by:
  33  *    La Monte H.P. Yarroll <piggy@acm.org>
  34  *    Karl Knutson          <karl@athena.chicago.il.us>
  35  *    Perry Melange         <pmelange@null.cc.uic.edu>
  36  *    Xingang Guo           <xingang.guo@intel.com>
  37  *    Hui Huang             <hui.huang@nokia.com>
  38  *    Sridhar Samudrala     <sri@us.ibm.com>
  39  *    Jon Grimm             <jgrimm@us.ibm.com>
  40  */
  41
  42 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  43
  44 #include <linux/types.h>
  45 #include <linux/list.h>   /* For struct list_head */
  46 #include <linux/socket.h>
  47 #include <linux/ip.h>
  48 #include <linux/slab.h>
  49 #include <net/sock.h>     /* For skb_set_owner_w */
  50
  51 #include <net/sctp/sctp.h>
  52 #include <net/sctp/sm.h>
  53
  54 /* Declare internal functions here.  */
  55 static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn);
  56 static void sctp_check_transmitted(struct sctp_outq *q,
  57                                    struct list_head *transmitted_queue,
  58                                    struct sctp_transport *transport,
  59                                    union sctp_addr *saddr,
  60                                    struct sctp_sackhdr *sack,
  61                                    __u32 *highest_new_tsn);
  62
  63 static void sctp_mark_missing(struct sctp_outq *q,
  64                               struct list_head *transmitted_queue,
  65                               struct sctp_transport *transport,
  66                               __u32 highest_new_tsn,
  67                               int count_of_newacks);
  68
  69 static void sctp_generate_fwdtsn(struct sctp_outq *q, __u32 sack_ctsn);
  70
  71 static int sctp_outq_flush(struct sctp_outq *q, int rtx_timeout);
  72
  73 /* Add data to the front of the queue. */
  74 static inline void sctp_outq_head_data(struct sctp_outq *q,
  75                                         struct sctp_chunk *ch)
  76 {
  77         list_add(&ch->list, &q->out_chunk_list);
  78         q->out_qlen += ch->skb->len;
  79 }
  80
  81 /* Take data from the front of the queue. */
  82 static inline struct sctp_chunk *sctp_outq_dequeue_data(struct sctp_outq *q)
  83 {
  84         struct sctp_chunk *ch = NULL;
  85
  86         if (!list_empty(&q->out_chunk_list)) {
  87                 struct list_head *entry = q->out_chunk_list.next;
  88
  89                 ch = list_entry(entry, struct sctp_chunk, list);
  90                 list_del_init(entry);
  91                 q->out_qlen -= ch->skb->len;
  92         }
  93         return ch;
  94 }
  95 /* Add data chunk to the end of the queue. */
  96 static inline void sctp_outq_tail_data(struct sctp_outq *q,
  97                                        struct sctp_chunk *ch)
  98 {
  99         list_add_tail(&ch->list, &q->out_chunk_list);
 100         q->out_qlen += ch->skb->len;
 101 }
 102
 103 /*
 104  * SFR-CACC algorithm:
 105  * D) If count_of_newacks is greater than or equal to 2
 106  * and t was not sent to the current primary then the
 107  * sender MUST NOT increment missing report count for t.
 108  */
 109 static inline int sctp_cacc_skip_3_1_d(struct sctp_transport *primary,
 110                                        struct sctp_transport *transport,
 111                                        int count_of_newacks)
 112 {
 113         if (count_of_newacks >= 2 && transport != primary)
 114                 return 1;
 115         return 0;
 116 }
 117
 118 /*
 119  * SFR-CACC algorithm:
 120  * F) If count_of_newacks is less than 2, let d be the
 121  * destination to which t was sent. If cacc_saw_newack
 122  * is 0 for destination d, then the sender MUST NOT
 123  * increment missing report count for t.
 124  */
 125 static inline int sctp_cacc_skip_3_1_f(struct sctp_transport *transport,
 126                                        int count_of_newacks)
 127 {
 128         if (count_of_newacks < 2 &&
 129                         (transport && !transport->cacc.cacc_saw_newack))
 130                 return 1;
 131         return 0;
 132 }
 133
 134 /*
 135  * SFR-CACC algorithm:
 136  * 3.1) If CYCLING_CHANGEOVER is 0, the sender SHOULD
 137  * execute steps C, D, F.
 138  *
 139  * C has been implemented in sctp_outq_sack
 140  */
 141 static inline int sctp_cacc_skip_3_1(struct sctp_transport *primary,
 142                                      struct sctp_transport *transport,
 143                                      int count_of_newacks)
 144 {
 145         if (!primary->cacc.cycling_changeover) {
 146                 if (sctp_cacc_skip_3_1_d(primary, transport, count_of_newacks))
 147                         return 1;
 148                 if (sctp_cacc_skip_3_1_f(transport, count_of_newacks))
 149                         return 1;
 150                 return 0;
 151         }
 152         return 0;
 153 }
 154
 155 /*
 156  * SFR-CACC algorithm:
 157  * 3.2) Else if CYCLING_CHANGEOVER is 1, and t is less
 158  * than next_tsn_at_change of the current primary, then
 159  * the sender MUST NOT increment missing report count
 160  * for t.
 161  */
 162 static inline int sctp_cacc_skip_3_2(struct sctp_transport *primary, __u32 tsn)
 163 {
 164         if (primary->cacc.cycling_changeover &&
 165             TSN_lt(tsn, primary->cacc.next_tsn_at_change))
 166                 return 1;
 167         return 0;
 168 }
 169
 170 /*
 171  * SFR-CACC algorithm:
 172  * 3) If the missing report count for TSN t is to be
 173  * incremented according to [RFC2960] and
 174  * [SCTP_STEWART-2002], and CHANGEOVER_ACTIVE is set,
 175  * then the sender MUST further execute steps 3.1 and
 176  * 3.2 to determine if the missing report count for
 177  * TSN t SHOULD NOT be incremented.
 178  *
 179  * 3.3) If 3.1 and 3.2 do not dictate that the missing
 180  * report count for t should not be incremented, then
 181  * the sender SHOULD increment missing report count for
 182  * t (according to [RFC2960] and [SCTP_STEWART_2002]).
 183  */
 184 static inline int sctp_cacc_skip(struct sctp_transport *primary,
 185                                  struct sctp_transport *transport,
 186                                  int count_of_newacks,
 187                                  __u32 tsn)
 188 {
 189         if (primary->cacc.changeover_active &&
 190             (sctp_cacc_skip_3_1(primary, transport, count_of_newacks) ||
 191              sctp_cacc_skip_3_2(primary, tsn)))
 192                 return 1;
 193         return 0;
 194 }
 195
 196 /* Initialize an existing sctp_outq.  This does the boring stuff.
 197  * You still need to define handlers if you really want to DO
 198  * something with this structure...
 199  */
 200 void sctp_outq_init(struct sctp_association *asoc, struct sctp_outq *q)
 201 {
 202         memset(q, 0, sizeof(struct sctp_outq));
 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->empty = 1;
 212 }
 213
 214 /* Free the outqueue structure and any related pending chunks.
 215  */
 216 static void __sctp_outq_teardown(struct sctp_outq *q)
 217 {
 218         struct sctp_transport *transport;
 219         struct list_head *lchunk, *temp;
 220         struct sctp_chunk *chunk, *tmp;
 221
 222         /* Throw away unacknowledged chunks. */
 223         list_for_each_entry(transport, &q->asoc->peer.transport_addr_list,
 224                         transports) {
 225                 while ((lchunk = sctp_list_dequeue(&transport->transmitted)) != NULL) {
 226                         chunk = list_entry(lchunk, struct sctp_chunk,
 227                                            transmitted_list);
 228                         /* Mark as part of a failed message. */
 229                         sctp_chunk_fail(chunk, q->error);
 230                         sctp_chunk_free(chunk);
 231                 }
 232         }
 233
 234         /* Throw away chunks that have been gap ACKed.  */
 235         list_for_each_safe(lchunk, temp, &q->sacked) {
 236                 list_del_init(lchunk);
 237                 chunk = list_entry(lchunk, struct sctp_chunk,
 238                                    transmitted_list);
 239                 sctp_chunk_fail(chunk, q->error);
 240                 sctp_chunk_free(chunk);
 241         }
 242
 243         /* Throw away any chunks in the retransmit queue. */
 244         list_for_each_safe(lchunk, temp, &q->retransmit) {
 245                 list_del_init(lchunk);
 246                 chunk = list_entry(lchunk, struct sctp_chunk,
 247                                    transmitted_list);
 248                 sctp_chunk_fail(chunk, q->error);
 249                 sctp_chunk_free(chunk);
 250         }
 251
 252         /* Throw away any chunks that are in the abandoned queue. */
 253         list_for_each_safe(lchunk, temp, &q->abandoned) {
 254                 list_del_init(lchunk);
 255                 chunk = list_entry(lchunk, struct sctp_chunk,
 256                                    transmitted_list);
 257                 sctp_chunk_fail(chunk, q->error);
 258                 sctp_chunk_free(chunk);
 259         }
 260
 261         /* Throw away any leftover data chunks. */
 262         while ((chunk = sctp_outq_dequeue_data(q)) != NULL) {
 263
 264                 /* Mark as send failure. */
 265                 sctp_chunk_fail(chunk, q->error);
 266                 sctp_chunk_free(chunk);
 267         }
 268
 269         /* Throw away any leftover control chunks. */
 270         list_for_each_entry_safe(chunk, tmp, &q->control_chunk_list, list) {
 271                 list_del_init(&chunk->list);
 272                 sctp_chunk_free(chunk);
 273         }
 274 }
 275
 276 void sctp_outq_teardown(struct sctp_outq *q)
 277 {
 278         __sctp_outq_teardown(q);
 279         sctp_outq_init(q->asoc, q);
 280 }
 281
 282 /* Free the outqueue structure and any related pending chunks.  */
 283 void sctp_outq_free(struct sctp_outq *q)
 284 {
 285         /* Throw away leftover chunks. */
 286         __sctp_outq_teardown(q);
 287 }
 288
 289 /* Put a new chunk in an sctp_outq.  */
 290 int sctp_outq_tail(struct sctp_outq *q, struct sctp_chunk *chunk)
 291 {
 292         struct net *net = sock_net(q->asoc->base.sk);
 293         int error = 0;
 294
 295         pr_debug("%s: outq:%p, chunk:%p[%s]\n", __func__, q, chunk,
 296                  chunk && chunk->chunk_hdr ?
 297                  sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)) :
 298                  "illegal chunk");
 299
 300         /* If it is data, queue it up, otherwise, send it
 301          * immediately.
 302          */
 303         if (sctp_chunk_is_data(chunk)) {
 304                 /* Is it OK to queue data chunks?  */
 305                 /* From 9. Termination of Association
 306                  *
 307                  * When either endpoint performs a shutdown, the
 308                  * association on each peer will stop accepting new
 309                  * data from its user and only deliver data in queue
 310                  * at the time of sending or receiving the SHUTDOWN
 311                  * chunk.
 312                  */
 313                 switch (q->asoc->state) {
 314                 case SCTP_STATE_CLOSED:
 315                 case SCTP_STATE_SHUTDOWN_PENDING:
 316                 case SCTP_STATE_SHUTDOWN_SENT:
 317                 case SCTP_STATE_SHUTDOWN_RECEIVED:
 318                 case SCTP_STATE_SHUTDOWN_ACK_SENT:
 319                         /* Cannot send after transport endpoint shutdown */
 320                         error = -ESHUTDOWN;
 321                         break;
 322
 323                 default:
 324                         pr_debug("%s: outqueueing: outq:%p, chunk:%p[%s])\n",
 325                                  __func__, q, chunk, chunk && chunk->chunk_hdr ?
 326                                  sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)) :
 327                                  "illegal chunk");
 328
 329                         sctp_outq_tail_data(q, chunk);
 330                         if (chunk->chunk_hdr->flags & SCTP_DATA_UNORDERED)
 331                                 SCTP_INC_STATS(net, SCTP_MIB_OUTUNORDERCHUNKS);
 332                         else
 333                                 SCTP_INC_STATS(net, SCTP_MIB_OUTORDERCHUNKS);
 334                         q->empty = 0;
 335                         break;
 336                 }
 337         } else {
 338                 list_add_tail(&chunk->list, &q->control_chunk_list);
 339                 SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
 340         }
 341
 342         if (error < 0)
 343                 return error;
 344
 345         if (!q->cork)
 346                 error = sctp_outq_flush(q, 0);
 347
 348         return error;
 349 }
 350
 351 /* Insert a chunk into the sorted list based on the TSNs.  The retransmit list
 352  * and the abandoned list are in ascending order.
 353  */
 354 static void sctp_insert_list(struct list_head *head, struct list_head *new)
 355 {
 356         struct list_head *pos;
 357         struct sctp_chunk *nchunk, *lchunk;
 358         __u32 ntsn, ltsn;
 359         int done = 0;
 360
 361         nchunk = list_entry(new, struct sctp_chunk, transmitted_list);
 362         ntsn = ntohl(nchunk->subh.data_hdr->tsn);
 363
 364         list_for_each(pos, head) {
 365                 lchunk = list_entry(pos, struct sctp_chunk, transmitted_list);
 366                 ltsn = ntohl(lchunk->subh.data_hdr->tsn);
 367                 if (TSN_lt(ntsn, ltsn)) {
 368                         list_add(new, pos->prev);
 369                         done = 1;
 370                         break;
 371                 }
 372         }
 373         if (!done)
 374                 list_add_tail(new, head);
 375 }
 376
 377 /* Mark all the eligible packets on a transport for retransmission.  */
 378 void sctp_retransmit_mark(struct sctp_outq *q,
 379                           struct sctp_transport *transport,
 380                           __u8 reason)
 381 {
 382         struct list_head *lchunk, *ltemp;
 383         struct sctp_chunk *chunk;
 384
 385         /* Walk through the specified transmitted queue.  */
 386         list_for_each_safe(lchunk, ltemp, &transport->transmitted) {
 387                 chunk = list_entry(lchunk, struct sctp_chunk,
 388                                    transmitted_list);
 389
 390                 /* If the chunk is abandoned, move it to abandoned list. */
 391                 if (sctp_chunk_abandoned(chunk)) {
 392                         list_del_init(lchunk);
 393                         sctp_insert_list(&q->abandoned, lchunk);
 394
 395                         /* If this chunk has not been previousely acked,
 396                          * stop considering it 'outstanding'.  Our peer
 397                          * will most likely never see it since it will
 398                          * not be retransmitted
 399                          */
 400                         if (!chunk->tsn_gap_acked) {
 401                                 if (chunk->transport)
 402                                         chunk->transport->flight_size -=
 403                                                         sctp_data_size(chunk);
 404                                 q->outstanding_bytes -= sctp_data_size(chunk);
 405                                 q->asoc->peer.rwnd += sctp_data_size(chunk);
 406                         }
 407                         continue;
 408                 }
 409
 410                 /* If we are doing  retransmission due to a timeout or pmtu
 411                  * discovery, only the  chunks that are not yet acked should
 412                  * be added to the retransmit queue.
 413                  */
 414                 if ((reason == SCTP_RTXR_FAST_RTX  &&
 415                             (chunk->fast_retransmit == SCTP_NEED_FRTX)) ||
 416                     (reason != SCTP_RTXR_FAST_RTX  && !chunk->tsn_gap_acked)) {
 417                         /* RFC 2960 6.2.1 Processing a Received SACK
 418                          *
 419                          * C) Any time a DATA chunk is marked for
 420                          * retransmission (via either T3-rtx timer expiration
 421                          * (Section 6.3.3) or via fast retransmit
 422                          * (Section 7.2.4)), add the data size of those
 423                          * chunks to the rwnd.
 424                          */
 425                         q->asoc->peer.rwnd += sctp_data_size(chunk);
 426                         q->outstanding_bytes -= sctp_data_size(chunk);
 427                         if (chunk->transport)
 428                                 transport->flight_size -= sctp_data_size(chunk);
 429
 430                         /* sctpimpguide-05 Section 2.8.2
 431                          * M5) If a T3-rtx timer expires, the
 432                          * 'TSN.Missing.Report' of all affected TSNs is set
 433                          * to 0.
 434                          */
 435                         chunk->tsn_missing_report = 0;
 436
 437                         /* If a chunk that is being used for RTT measurement
 438                          * has to be retransmitted, we cannot use this chunk
 439                          * anymore for RTT measurements. Reset rto_pending so
 440                          * that a new RTT measurement is started when a new
 441                          * data chunk is sent.
 442                          */
 443                         if (chunk->rtt_in_progress) {
 444                                 chunk->rtt_in_progress = 0;
 445                                 transport->rto_pending = 0;
 446                         }
 447
 448                         chunk->resent = 1;
 449
 450                         /* Move the chunk to the retransmit queue. The chunks
 451                          * on the retransmit queue are always kept in order.
 452                          */
 453                         list_del_init(lchunk);
 454                         sctp_insert_list(&q->retransmit, lchunk);
 455                 }
 456         }
 457
 458         pr_debug("%s: transport:%p, reason:%d, cwnd:%d, ssthresh:%d, "
 459                  "flight_size:%d, pba:%d\n", __func__, transport, reason,
 460                  transport->cwnd, transport->ssthresh, transport->flight_size,
 461                  transport->partial_bytes_acked);
 462 }
 463
 464 /* Mark all the eligible packets on a transport for retransmission and force
 465  * one packet out.
 466  */
 467 void sctp_retransmit(struct sctp_outq *q, struct sctp_transport *transport,
 468                      sctp_retransmit_reason_t reason)
 469 {
 470         struct net *net = sock_net(q->asoc->base.sk);
 471         int error = 0;
 472
 473         switch (reason) {
 474         case SCTP_RTXR_T3_RTX:
 475                 SCTP_INC_STATS(net, SCTP_MIB_T3_RETRANSMITS);
 476                 sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_T3_RTX);
 477                 /* Update the retran path if the T3-rtx timer has expired for
 478                  * the current retran path.
 479                  */
 480                 if (transport == transport->asoc->peer.retran_path)
 481                         sctp_assoc_update_retran_path(transport->asoc);
 482                 transport->asoc->rtx_data_chunks +=
 483                         transport->asoc->unack_data;
 484                 break;
 485         case SCTP_RTXR_FAST_RTX:
 486                 SCTP_INC_STATS(net, SCTP_MIB_FAST_RETRANSMITS);
 487                 sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_FAST_RTX);
 488                 q->fast_rtx = 1;
 489                 break;
 490         case SCTP_RTXR_PMTUD:
 491                 SCTP_INC_STATS(net, SCTP_MIB_PMTUD_RETRANSMITS);
 492                 break;
 493         case SCTP_RTXR_T1_RTX:
 494                 SCTP_INC_STATS(net, SCTP_MIB_T1_RETRANSMITS);
 495                 transport->asoc->init_retries++;
 496                 break;
 497         default:
 498                 BUG();
 499         }
 500
 501         sctp_retransmit_mark(q, transport, reason);
 502
 503         /* PR-SCTP A5) Any time the T3-rtx timer expires, on any destination,
 504          * the sender SHOULD try to advance the "Advanced.Peer.Ack.Point" by
 505          * following the procedures outlined in C1 - C5.
 506          */
 507         if (reason == SCTP_RTXR_T3_RTX)
 508                 sctp_generate_fwdtsn(q, q->asoc->ctsn_ack_point);
 509
 510         /* Flush the queues only on timeout, since fast_rtx is only
 511          * triggered during sack processing and the queue
 512          * will be flushed at the end.
 513          */
 514         if (reason != SCTP_RTXR_FAST_RTX)
 515                 error = sctp_outq_flush(q, /* rtx_timeout */ 1);
 516
 517         if (error)
 518                 q->asoc->base.sk->sk_err = -error;
 519 }
 520
 521 /*
 522  * Transmit DATA chunks on the retransmit queue.  Upon return from
 523  * sctp_outq_flush_rtx() the packet 'pkt' may contain chunks which
 524  * need to be transmitted by the caller.
 525  * We assume that pkt->transport has already been set.
 526  *
 527  * The return value is a normal kernel error return value.
 528  */
 529 static int sctp_outq_flush_rtx(struct sctp_outq *q, struct sctp_packet *pkt,
 530                                int rtx_timeout, int *start_timer)
 531 {
 532         struct list_head *lqueue;
 533         struct sctp_transport *transport = pkt->transport;
 534         sctp_xmit_t status;
 535         struct sctp_chunk *chunk, *chunk1;
 536         int fast_rtx;
 537         int error = 0;
 538         int timer = 0;
 539         int done = 0;
 540
 541         lqueue = &q->retransmit;
 542         fast_rtx = q->fast_rtx;
 543
 544         /* This loop handles time-out retransmissions, fast retransmissions,
 545          * and retransmissions due to opening of whindow.
 546          *
 547          * RFC 2960 6.3.3 Handle T3-rtx Expiration
 548          *
 549          * E3) Determine how many of the earliest (i.e., lowest TSN)
 550          * outstanding DATA chunks for the address for which the
 551          * T3-rtx has expired will fit into a single packet, subject
 552          * to the MTU constraint for the path corresponding to the
 553          * destination transport address to which the retransmission
 554          * is being sent (this may be different from the address for
 555          * which the timer expires [see Section 6.4]). Call this value
 556          * K. Bundle and retransmit those K DATA chunks in a single
 557          * packet to the destination endpoint.
 558          *
 559          * [Just to be painfully clear, if we are retransmitting
 560          * because a timeout just happened, we should send only ONE
 561          * packet of retransmitted data.]
 562          *
 563          * For fast retransmissions we also send only ONE packet.  However,
 564          * if we are just flushing the queue due to open window, we'll
 565          * try to send as much as possible.
 566          */
 567         list_for_each_entry_safe(chunk, chunk1, lqueue, transmitted_list) {
 568                 /* If the chunk is abandoned, move it to abandoned list. */
 569                 if (sctp_chunk_abandoned(chunk)) {
 570                         list_del_init(&chunk->transmitted_list);
 571                         sctp_insert_list(&q->abandoned,
 572                                          &chunk->transmitted_list);
 573                         continue;
 574                 }
 575
 576                 /* Make sure that Gap Acked TSNs are not retransmitted.  A
 577                  * simple approach is just to move such TSNs out of the
 578                  * way and into a 'transmitted' queue and skip to the
 579                  * next chunk.
 580                  */
 581                 if (chunk->tsn_gap_acked) {
 582                         list_move_tail(&chunk->transmitted_list,
 583                                        &transport->transmitted);
 584                         continue;
 585                 }
 586
 587                 /* If we are doing fast retransmit, ignore non-fast_rtransmit
 588                  * chunks
 589                  */
 590                 if (fast_rtx && !chunk->fast_retransmit)
 591                         continue;
 592
 593 redo:
 594                 /* Attempt to append this chunk to the packet. */
 595                 status = sctp_packet_append_chunk(pkt, chunk);
 596
 597                 switch (status) {
 598                 case SCTP_XMIT_PMTU_FULL:
 599                         if (!pkt->has_data && !pkt->has_cookie_echo) {
 600                                 /* If this packet did not contain DATA then
 601                                  * retransmission did not happen, so do it
 602                                  * again.  We'll ignore the error here since
 603                                  * control chunks are already freed so there
 604                                  * is nothing we can do.
 605                                  */
 606                                 sctp_packet_transmit(pkt);
 607                                 goto redo;
 608                         }
 609
 610                         /* Send this packet.  */
 611                         error = sctp_packet_transmit(pkt);
 612
 613                         /* If we are retransmitting, we should only
 614                          * send a single packet.
 615                          * Otherwise, try appending this chunk again.
 616                          */
 617                         if (rtx_timeout || fast_rtx)
 618                                 done = 1;
 619                         else
 620                                 goto redo;
 621
 622                         /* Bundle next chunk in the next round.  */
 623                         break;
 624
 625                 case SCTP_XMIT_RWND_FULL:
 626                         /* Send this packet. */
 627                         error = sctp_packet_transmit(pkt);
 628
 629                         /* Stop sending DATA as there is no more room
 630                          * at the receiver.
 631                          */
 632                         done = 1;
 633                         break;
 634
 635                 case SCTP_XMIT_NAGLE_DELAY:
 636                         /* Send this packet. */
 637                         error = sctp_packet_transmit(pkt);
 638
 639                         /* Stop sending DATA because of nagle delay. */
 640                         done = 1;
 641                         break;
 642
 643                 default:
 644                         /* The append was successful, so add this chunk to
 645                          * the transmitted list.
 646                          */
 647                         list_move_tail(&chunk->transmitted_list,
 648                                        &transport->transmitted);
 649
 650                         /* Mark the chunk as ineligible for fast retransmit
 651                          * after it is retransmitted.
 652                          */
 653                         if (chunk->fast_retransmit == SCTP_NEED_FRTX)
 654                                 chunk->fast_retransmit = SCTP_DONT_FRTX;
 655
 656                         q->empty = 0;
 657                         q->asoc->stats.rtxchunks++;
 658                         break;
 659                 }
 660
 661                 /* Set the timer if there were no errors */
 662                 if (!error && !timer)
 663                         timer = 1;
 664
 665                 if (done)
 666                         break;
 667         }
 668
 669         /* If we are here due to a retransmit timeout or a fast
 670          * retransmit and if there are any chunks left in the retransmit
 671          * queue that could not fit in the PMTU sized packet, they need
 672          * to be marked as ineligible for a subsequent fast retransmit.
 673          */
 674         if (rtx_timeout || fast_rtx) {
 675                 list_for_each_entry(chunk1, lqueue, transmitted_list) {
 676                         if (chunk1->fast_retransmit == SCTP_NEED_FRTX)
 677                                 chunk1->fast_retransmit = SCTP_DONT_FRTX;
 678                 }
 679         }
 680
 681         *start_timer = timer;
 682
 683         /* Clear fast retransmit hint */
 684         if (fast_rtx)
 685                 q->fast_rtx = 0;
 686
 687         return error;
 688 }
 689
 690 /* Cork the outqueue so queued chunks are really queued. */
 691 int sctp_outq_uncork(struct sctp_outq *q)
 692 {
 693         if (q->cork)
 694                 q->cork = 0;
 695
 696         return sctp_outq_flush(q, 0);
 697 }
 698
 699
 700 /*
 701  * Try to flush an outqueue.
 702  *
 703  * Description: Send everything in q which we legally can, subject to
 704  * congestion limitations.
 705  * * Note: This function can be called from multiple contexts so appropriate
 706  * locking concerns must be made.  Today we use the sock lock to protect
 707  * this function.
 708  */
 709 static int sctp_outq_flush(struct sctp_outq *q, int rtx_timeout)
 710 {
 711         struct sctp_packet *packet;
 712         struct sctp_packet singleton;
 713         struct sctp_association *asoc = q->asoc;
 714         __u16 sport = asoc->base.bind_addr.port;
 715         __u16 dport = asoc->peer.port;
 716         __u32 vtag = asoc->peer.i.init_tag;
 717         struct sctp_transport *transport = NULL;
 718         struct sctp_transport *new_transport;
 719         struct sctp_chunk *chunk, *tmp;
 720         sctp_xmit_t status;
 721         int error = 0;
 722         int start_timer = 0;
 723         int one_packet = 0;
 724
 725         /* These transports have chunks to send. */
 726         struct list_head transport_list;
 727         struct list_head *ltransport;
 728
 729         INIT_LIST_HEAD(&transport_list);
 730         packet = NULL;
 731
 732         /*
 733          * 6.10 Bundling
 734          *   ...
 735          *   When bundling control chunks with DATA chunks, an
 736          *   endpoint MUST place control chunks first in the outbound
 737          *   SCTP packet.  The transmitter MUST transmit DATA chunks
 738          *   within a SCTP packet in increasing order of TSN.
 739          *   ...
 740          */
 741
 742         list_for_each_entry_safe(chunk, tmp, &q->control_chunk_list, list) {
 743                 /* RFC 5061, 5.3
 744                  * F1) This means that until such time as the ASCONF
 745                  * containing the add is acknowledged, the sender MUST
 746                  * NOT use the new IP address as a source for ANY SCTP
 747                  * packet except on carrying an ASCONF Chunk.
 748                  */
 749                 if (asoc->src_out_of_asoc_ok &&
 750                     chunk->chunk_hdr->type != SCTP_CID_ASCONF)
 751                         continue;
 752
 753                 list_del_init(&chunk->list);
 754
 755                 /* Pick the right transport to use. */
 756                 new_transport = chunk->transport;
 757
 758                 if (!new_transport) {
 759                         /*
 760                          * If we have a prior transport pointer, see if
 761                          * the destination address of the chunk
 762                          * matches the destination address of the
 763                          * current transport.  If not a match, then
 764                          * try to look up the transport with a given
 765                          * destination address.  We do this because
 766                          * after processing ASCONFs, we may have new
 767                          * transports created.
 768                          */
 769                         if (transport &&
 770                             sctp_cmp_addr_exact(&chunk->dest,
 771                                                 &transport->ipaddr))
 772                                         new_transport = transport;
 773                         else
 774                                 new_transport = sctp_assoc_lookup_paddr(asoc,
 775                                                                 &chunk->dest);
 776
 777                         /* if we still don't have a new transport, then
 778                          * use the current active path.
 779                          */
 780                         if (!new_transport)
 781                                 new_transport = asoc->peer.active_path;
 782                 } else if ((new_transport->state == SCTP_INACTIVE) ||
 783                            (new_transport->state == SCTP_UNCONFIRMED) ||
 784                            (new_transport->state == SCTP_PF)) {
 785                         /* If the chunk is Heartbeat or Heartbeat Ack,
 786                          * send it to chunk->transport, even if it's
 787                          * inactive.
 788                          *
 789                          * 3.3.6 Heartbeat Acknowledgement:
 790                          * ...
 791                          * A HEARTBEAT ACK is always sent to the source IP
 792                          * address of the IP datagram containing the
 793                          * HEARTBEAT chunk to which this ack is responding.
 794                          * ...
 795                          *
 796                          * ASCONF_ACKs also must be sent to the source.
 797                          */
 798                         if (chunk->chunk_hdr->type != SCTP_CID_HEARTBEAT &&
 799                             chunk->chunk_hdr->type != SCTP_CID_HEARTBEAT_ACK &&
 800                             chunk->chunk_hdr->type != SCTP_CID_ASCONF_ACK)
 801                                 new_transport = asoc->peer.active_path;
 802                 }
 803
 804                 /* Are we switching transports?
 805                  * Take care of transport locks.
 806                  */
 807                 if (new_transport != transport) {
 808                         transport = new_transport;
 809                         if (list_empty(&transport->send_ready)) {
 810                                 list_add_tail(&transport->send_ready,
 811                                               &transport_list);
 812                         }
 813                         packet = &transport->packet;
 814                         sctp_packet_config(packet, vtag,
 815                                            asoc->peer.ecn_capable);
 816                 }
 817
 818                 switch (chunk->chunk_hdr->type) {
 819                 /*
 820                  * 6.10 Bundling
 821                  *   ...
 822                  *   An endpoint MUST NOT bundle INIT, INIT ACK or SHUTDOWN
 823                  *   COMPLETE with any other chunks.  [Send them immediately.]
 824                  */
 825                 case SCTP_CID_INIT:
 826                 case SCTP_CID_INIT_ACK:
 827                 case SCTP_CID_SHUTDOWN_COMPLETE:
 828                         sctp_packet_init(&singleton, transport, sport, dport);
 829                         sctp_packet_config(&singleton, vtag, 0);
 830                         sctp_packet_append_chunk(&singleton, chunk);
 831                         error = sctp_packet_transmit(&singleton);
 832                         if (error < 0)
 833                                 return error;
 834                         break;
 835
 836                 case SCTP_CID_ABORT:
 837                         if (sctp_test_T_bit(chunk)) {
 838                                 packet->vtag = asoc->c.my_vtag;
 839                         }
 840                 /* The following chunks are "response" chunks, i.e.
 841                  * they are generated in response to something we
 842                  * received.  If we are sending these, then we can
 843                  * send only 1 packet containing these chunks.
 844                  */
 845                 case SCTP_CID_HEARTBEAT_ACK:
 846                 case SCTP_CID_SHUTDOWN_ACK:
 847                 case SCTP_CID_COOKIE_ACK:
 848                 case SCTP_CID_COOKIE_ECHO:
 849                 case SCTP_CID_ERROR:
 850                 case SCTP_CID_ECN_CWR:
 851                 case SCTP_CID_ASCONF_ACK:
 852                         one_packet = 1;
 853                         /* Fall through */
 854
 855                 case SCTP_CID_SACK:
 856                 case SCTP_CID_HEARTBEAT:
 857                 case SCTP_CID_SHUTDOWN:
 858                 case SCTP_CID_ECN_ECNE:
 859                 case SCTP_CID_ASCONF:
 860                 case SCTP_CID_FWD_TSN:
 861                         status = sctp_packet_transmit_chunk(packet, chunk,
 862                                                             one_packet);
 863                         if (status  != SCTP_XMIT_OK) {
 864                                 /* put the chunk back */
 865                                 list_add(&chunk->list, &q->control_chunk_list);
 866                         } else {
 867                                 asoc->stats.octrlchunks++;
 868                                 /* PR-SCTP C5) If a FORWARD TSN is sent, the
 869                                  * sender MUST assure that at least one T3-rtx
 870                                  * timer is running.
 871                                  */
 872                                 if (chunk->chunk_hdr->type == SCTP_CID_FWD_TSN)
 873                                         sctp_transport_reset_timers(transport);
 874                         }
 875                         break;
 876
 877                 default:
 878                         /* We built a chunk with an illegal type! */
 879                         BUG();
 880                 }
 881         }
 882
 883         if (q->asoc->src_out_of_asoc_ok)
 884                 goto sctp_flush_out;
 885
 886         /* Is it OK to send data chunks?  */
 887         switch (asoc->state) {
 888         case SCTP_STATE_COOKIE_ECHOED:
 889                 /* Only allow bundling when this packet has a COOKIE-ECHO
 890                  * chunk.
 891                  */
 892                 if (!packet || !packet->has_cookie_echo)
 893                         break;
 894
 895                 /* fallthru */
 896         case SCTP_STATE_ESTABLISHED:
 897         case SCTP_STATE_SHUTDOWN_PENDING:
 898         case SCTP_STATE_SHUTDOWN_RECEIVED:
 899                 /*
 900                  * RFC 2960 6.1  Transmission of DATA Chunks
 901                  *
 902                  * C) When the time comes for the sender to transmit,
 903                  * before sending new DATA chunks, the sender MUST
 904                  * first transmit any outstanding DATA chunks which
 905                  * are marked for retransmission (limited by the
 906                  * current cwnd).
 907                  */
 908                 if (!list_empty(&q->retransmit)) {
 909                         if (asoc->peer.retran_path->state == SCTP_UNCONFIRMED)
 910                                 goto sctp_flush_out;
 911                         if (transport == asoc->peer.retran_path)
 912                                 goto retran;
 913
 914                         /* Switch transports & prepare the packet.  */
 915
 916                         transport = asoc->peer.retran_path;
 917
 918                         if (list_empty(&transport->send_ready)) {
 919                                 list_add_tail(&transport->send_ready,
 920                                               &transport_list);
 921                         }
 922
 923                         packet = &transport->packet;
 924                         sctp_packet_config(packet, vtag,
 925                                            asoc->peer.ecn_capable);
 926                 retran:
 927                         error = sctp_outq_flush_rtx(q, packet,
 928                                                     rtx_timeout, &start_timer);
 929
 930                         if (start_timer)
 931                                 sctp_transport_reset_timers(transport);
 932
 933                         /* This can happen on COOKIE-ECHO resend.  Only
 934                          * one chunk can get bundled with a COOKIE-ECHO.
 935                          */
 936                         if (packet->has_cookie_echo)
 937                                 goto sctp_flush_out;
 938
 939                         /* Don't send new data if there is still data
 940                          * waiting to retransmit.
 941                          */
 942                         if (!list_empty(&q->retransmit))
 943                                 goto sctp_flush_out;
 944                 }
 945
 946                 /* Apply Max.Burst limitation to the current transport in
 947                  * case it will be used for new data.  We are going to
 948                  * rest it before we return, but we want to apply the limit
 949                  * to the currently queued data.
 950                  */
 951                 if (transport)
 952                         sctp_transport_burst_limited(transport);
 953
 954                 /* Finally, transmit new packets.  */
 955                 while ((chunk = sctp_outq_dequeue_data(q)) != NULL) {
 956                         /* RFC 2960 6.5 Every DATA chunk MUST carry a valid
 957                          * stream identifier.
 958                          */
 959                         if (chunk->sinfo.sinfo_stream >=
 960                             asoc->c.sinit_num_ostreams) {
 961
 962                                 /* Mark as failed send. */
 963                                 sctp_chunk_fail(chunk, SCTP_ERROR_INV_STRM);
 964                                 sctp_chunk_free(chunk);
 965                                 continue;
 966                         }
 967
 968                         /* Has this chunk expired? */
 969                         if (sctp_chunk_abandoned(chunk)) {
 970                                 sctp_chunk_fail(chunk, 0);
 971                                 sctp_chunk_free(chunk);
 972                                 continue;
 973                         }
 974
 975                         /* If there is a specified transport, use it.
 976                          * Otherwise, we want to use the active path.
 977                          */
 978                         new_transport = chunk->transport;
 979                         if (!new_transport ||
 980                             ((new_transport->state == SCTP_INACTIVE) ||
 981                              (new_transport->state == SCTP_UNCONFIRMED) ||
 982                              (new_transport->state == SCTP_PF)))
 983                                 new_transport = asoc->peer.active_path;
 984                         if (new_transport->state == SCTP_UNCONFIRMED)
 985                                 continue;
 986
 987                         /* Change packets if necessary.  */
 988                         if (new_transport != transport) {
 989                                 transport = new_transport;
 990
 991                                 /* Schedule to have this transport's
 992                                  * packet flushed.
 993                                  */
 994                                 if (list_empty(&transport->send_ready)) {
 995                                         list_add_tail(&transport->send_ready,
 996                                                       &transport_list);
 997                                 }
 998
 999                                 packet = &transport->packet;
1000                                 sctp_packet_config(packet, vtag,
1001                                                    asoc->peer.ecn_capable);
1002                                 /* We've switched transports, so apply the
1003                                  * Burst limit to the new transport.
1004                                  */
1005                                 sctp_transport_burst_limited(transport);
1006                         }
1007
1008                         pr_debug("%s: outq:%p, chunk:%p[%s], tx-tsn:0x%x skb->head:%p "
1009                                  "skb->users:%d\n",
1010                                  __func__, q, chunk, chunk && chunk->chunk_hdr ?
1011                                  sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)) :
1012                                  "illegal chunk", ntohl(chunk->subh.data_hdr->tsn),
1013                                  chunk->skb ? chunk->skb->head : NULL, chunk->skb ?
1014                                  atomic_read(&chunk->skb->users) : -1);
1015
1016                         /* Add the chunk to the packet.  */
1017                         status = sctp_packet_transmit_chunk(packet, chunk, 0);
1018
1019                         switch (status) {
1020                         case SCTP_XMIT_PMTU_FULL:
1021                         case SCTP_XMIT_RWND_FULL:
1022                         case SCTP_XMIT_NAGLE_DELAY:
1023                                 /* We could not append this chunk, so put
1024                                  * the chunk back on the output queue.
1025                                  */
1026                                 pr_debug("%s: could not transmit tsn:0x%x, status:%d\n",
1027                                          __func__, ntohl(chunk->subh.data_hdr->tsn),
1028                                          status);
1029
1030                                 sctp_outq_head_data(q, chunk);
1031                                 goto sctp_flush_out;
1032                                 break;
1033
1034                         case SCTP_XMIT_OK:
1035                                 /* The sender is in the SHUTDOWN-PENDING state,
1036                                  * The sender MAY set the I-bit in the DATA
1037                                  * chunk header.
1038                                  */
1039                                 if (asoc->state == SCTP_STATE_SHUTDOWN_PENDING)
1040                                         chunk->chunk_hdr->flags |= SCTP_DATA_SACK_IMM;
1041                                 if (chunk->chunk_hdr->flags & SCTP_DATA_UNORDERED)
1042                                         asoc->stats.ouodchunks++;
1043                                 else
1044                                         asoc->stats.oodchunks++;
1045
1046                                 break;
1047
1048                         default:
1049                                 BUG();
1050                         }
1051
1052                         /* BUG: We assume that the sctp_packet_transmit()
1053                          * call below will succeed all the time and add the
1054                          * chunk to the transmitted list and restart the
1055                          * timers.
1056                          * It is possible that the call can fail under OOM
1057                          * conditions.
1058                          *
1059                          * Is this really a problem?  Won't this behave
1060                          * like a lost TSN?
1061                          */
1062                         list_add_tail(&chunk->transmitted_list,
1063                                       &transport->transmitted);
1064
1065                         sctp_transport_reset_timers(transport);
1066
1067                         q->empty = 0;
1068
1069                         /* Only let one DATA chunk get bundled with a
1070                          * COOKIE-ECHO chunk.
1071                          */
1072                         if (packet->has_cookie_echo)
1073                                 goto sctp_flush_out;
1074                 }
1075                 break;
1076
1077         default:
1078                 /* Do nothing.  */
1079                 break;
1080         }
1081
1082 sctp_flush_out:
1083
1084         /* Before returning, examine all the transports touched in
1085          * this call.  Right now, we bluntly force clear all the
1086          * transports.  Things might change after we implement Nagle.
1087          * But such an examination is still required.
1088          *
1089          * --xguo
1090          */
1091         while ((ltransport = sctp_list_dequeue(&transport_list)) != NULL) {
1092                 struct sctp_transport *t = list_entry(ltransport,
1093                                                       struct sctp_transport,
1094                                                       send_ready);
1095                 packet = &t->packet;
1096                 if (!sctp_packet_empty(packet))
1097                         error = sctp_packet_transmit(packet);
1098
1099                 /* Clear the burst limited state, if any */
1100                 sctp_transport_burst_reset(t);
1101         }
1102
1103         return error;
1104 }
1105
1106 /* Update unack_data based on the incoming SACK chunk */
1107 static void sctp_sack_update_unack_data(struct sctp_association *assoc,
1108                                         struct sctp_sackhdr *sack)
1109 {
1110         sctp_sack_variable_t *frags;
1111         __u16 unack_data;
1112         int i;
1113
1114         unack_data = assoc->next_tsn - assoc->ctsn_ack_point - 1;
1115
1116         frags = sack->variable;
1117         for (i = 0; i < ntohs(sack->num_gap_ack_blocks); i++) {
1118                 unack_data -= ((ntohs(frags[i].gab.end) -
1119                                 ntohs(frags[i].gab.start) + 1));
1120         }
1121
1122         assoc->unack_data = unack_data;
1123 }
1124
1125 /* This is where we REALLY process a SACK.
1126  *
1127  * Process the SACK against the outqueue.  Mostly, this just frees
1128  * things off the transmitted queue.
1129  */
1130 int sctp_outq_sack(struct sctp_outq *q, struct sctp_chunk *chunk)
1131 {
1132         struct sctp_association *asoc = q->asoc;
1133         struct sctp_sackhdr *sack = chunk->subh.sack_hdr;
1134         struct sctp_transport *transport;
1135         struct sctp_chunk *tchunk = NULL;
1136         struct list_head *lchunk, *transport_list, *temp;
1137         sctp_sack_variable_t *frags = sack->variable;
1138         __u32 sack_ctsn, ctsn, tsn;
1139         __u32 highest_tsn, highest_new_tsn;
1140         __u32 sack_a_rwnd;
1141         unsigned int outstanding;
1142         struct sctp_transport *primary = asoc->peer.primary_path;
1143         int count_of_newacks = 0;
1144         int gap_ack_blocks;
1145         u8 accum_moved = 0;
1146
1147         /* Grab the association's destination address list. */
1148         transport_list = &asoc->peer.transport_addr_list;
1149
1150         sack_ctsn = ntohl(sack->cum_tsn_ack);
1151         gap_ack_blocks = ntohs(sack->num_gap_ack_blocks);
1152         asoc->stats.gapcnt += gap_ack_blocks;
1153         /*
1154          * SFR-CACC algorithm:
1155          * On receipt of a SACK the sender SHOULD execute the
1156          * following statements.
1157          *
1158          * 1) If the cumulative ack in the SACK passes next tsn_at_change
1159          * on the current primary, the CHANGEOVER_ACTIVE flag SHOULD be
1160          * cleared. The CYCLING_CHANGEOVER flag SHOULD also be cleared for
1161          * all destinations.
1162          * 2) If the SACK contains gap acks and the flag CHANGEOVER_ACTIVE
1163          * is set the receiver of the SACK MUST take the following actions:
1164          *
1165          * A) Initialize the cacc_saw_newack to 0 for all destination
1166          * addresses.
1167          *
1168          * Only bother if changeover_active is set. Otherwise, this is
1169          * totally suboptimal to do on every SACK.
1170          */
1171         if (primary->cacc.changeover_active) {
1172                 u8 clear_cycling = 0;
1173
1174                 if (TSN_lte(primary->cacc.next_tsn_at_change, sack_ctsn)) {
1175                         primary->cacc.changeover_active = 0;
1176                         clear_cycling = 1;
1177                 }
1178
1179                 if (clear_cycling || gap_ack_blocks) {
1180                         list_for_each_entry(transport, transport_list,
1181                                         transports) {
1182                                 if (clear_cycling)
1183                                         transport->cacc.cycling_changeover = 0;
1184                                 if (gap_ack_blocks)
1185                                         transport->cacc.cacc_saw_newack = 0;
1186                         }
1187                 }
1188         }
1189
1190         /* Get the highest TSN in the sack. */
1191         highest_tsn = sack_ctsn;
1192         if (gap_ack_blocks)
1193                 highest_tsn += ntohs(frags[gap_ack_blocks - 1].gab.end);
1194
1195         if (TSN_lt(asoc->highest_sacked, highest_tsn))
1196                 asoc->highest_sacked = highest_tsn;
1197
1198         highest_new_tsn = sack_ctsn;
1199
1200         /* Run through the retransmit queue.  Credit bytes received
1201          * and free those chunks that we can.
1202          */
1203         sctp_check_transmitted(q, &q->retransmit, NULL, NULL, sack, &highest_new_tsn);
1204
1205         /* Run through the transmitted queue.
1206          * Credit bytes received and free those chunks which we can.
1207          *
1208          * This is a MASSIVE candidate for optimization.
1209          */
1210         list_for_each_entry(transport, transport_list, transports) {
1211                 sctp_check_transmitted(q, &transport->transmitted,
1212                                        transport, &chunk->source, sack,
1213                                        &highest_new_tsn);
1214                 /*
1215                  * SFR-CACC algorithm:
1216                  * C) Let count_of_newacks be the number of
1217                  * destinations for which cacc_saw_newack is set.
1218                  */
1219                 if (transport->cacc.cacc_saw_newack)
1220                         count_of_newacks++;
1221         }
1222
1223         /* Move the Cumulative TSN Ack Point if appropriate.  */
1224         if (TSN_lt(asoc->ctsn_ack_point, sack_ctsn)) {
1225                 asoc->ctsn_ack_point = sack_ctsn;
1226                 accum_moved = 1;
1227         }
1228
1229         if (gap_ack_blocks) {
1230
1231                 if (asoc->fast_recovery && accum_moved)
1232                         highest_new_tsn = highest_tsn;
1233
1234                 list_for_each_entry(transport, transport_list, transports)
1235                         sctp_mark_missing(q, &transport->transmitted, transport,
1236                                           highest_new_tsn, count_of_newacks);
1237         }
1238
1239         /* Update unack_data field in the assoc. */
1240         sctp_sack_update_unack_data(asoc, sack);
1241
1242         ctsn = asoc->ctsn_ack_point;
1243
1244         /* Throw away stuff rotting on the sack queue.  */
1245         list_for_each_safe(lchunk, temp, &q->sacked) {
1246                 tchunk = list_entry(lchunk, struct sctp_chunk,
1247                                     transmitted_list);
1248                 tsn = ntohl(tchunk->subh.data_hdr->tsn);
1249                 if (TSN_lte(tsn, ctsn)) {
1250                         list_del_init(&tchunk->transmitted_list);
1251                         sctp_chunk_free(tchunk);
1252                 }
1253         }
1254
1255         /* ii) Set rwnd equal to the newly received a_rwnd minus the
1256          *     number of bytes still outstanding after processing the
1257          *     Cumulative TSN Ack and the Gap Ack Blocks.
1258          */
1259
1260         sack_a_rwnd = ntohl(sack->a_rwnd);
1261         outstanding = q->outstanding_bytes;
1262
1263         if (outstanding < sack_a_rwnd)
1264                 sack_a_rwnd -= outstanding;
1265         else
1266                 sack_a_rwnd = 0;
1267
1268         asoc->peer.rwnd = sack_a_rwnd;
1269
1270         sctp_generate_fwdtsn(q, sack_ctsn);
1271
1272         pr_debug("%s: sack cumulative tsn ack:0x%x\n", __func__, sack_ctsn);
1273         pr_debug("%s: cumulative tsn ack of assoc:%p is 0x%x, "
1274                  "advertised peer ack point:0x%x\n", __func__, asoc, ctsn,
1275                  asoc->adv_peer_ack_point);
1276
1277         /* See if all chunks are acked.
1278          * Make sure the empty queue handler will get run later.
1279          */
1280         q->empty = (list_empty(&q->out_chunk_list) &&
1281                     list_empty(&q->retransmit));
1282         if (!q->empty)
1283                 goto finish;
1284
1285         list_for_each_entry(transport, transport_list, transports) {
1286                 q->empty = q->empty && list_empty(&transport->transmitted);
1287                 if (!q->empty)
1288                         goto finish;
1289         }
1290
1291         pr_debug("%s: sack queue is empty\n", __func__);
1292 finish:
1293         return q->empty;
1294 }
1295
1296 /* Is the outqueue empty?  */
1297 int sctp_outq_is_empty(const struct sctp_outq *q)
1298 {
1299         return q->empty;
1300 }
1301
1302 /********************************************************************
1303  * 2nd Level Abstractions
1304  ********************************************************************/
1305
1306 /* Go through a transport's transmitted list or the association's retransmit
1307  * list and move chunks that are acked by the Cumulative TSN Ack to q->sacked.
1308  * The retransmit list will not have an associated transport.
1309  *
1310  * I added coherent debug information output.   --xguo
1311  *
1312  * Instead of printing 'sacked' or 'kept' for each TSN on the
1313  * transmitted_queue, we print a range: SACKED: TSN1-TSN2, TSN3, TSN4-TSN5.
1314  * KEPT TSN6-TSN7, etc.
1315  */
1316 static void sctp_check_transmitted(struct sctp_outq *q,
1317                                    struct list_head *transmitted_queue,
1318                                    struct sctp_transport *transport,
1319                                    union sctp_addr *saddr,
1320                                    struct sctp_sackhdr *sack,
1321                                    __u32 *highest_new_tsn_in_sack)
1322 {
1323         struct list_head *lchunk;
1324         struct sctp_chunk *tchunk;
1325         struct list_head tlist;
1326         __u32 tsn;
1327         __u32 sack_ctsn;
1328         __u32 rtt;
1329         __u8 restart_timer = 0;
1330         int bytes_acked = 0;
1331         int migrate_bytes = 0;
1332         bool forward_progress = false;
1333
1334         sack_ctsn = ntohl(sack->cum_tsn_ack);
1335
1336         INIT_LIST_HEAD(&tlist);
1337
1338         /* The while loop will skip empty transmitted queues. */
1339         while (NULL != (lchunk = sctp_list_dequeue(transmitted_queue))) {
1340                 tchunk = list_entry(lchunk, struct sctp_chunk,
1341                                     transmitted_list);
1342
1343                 if (sctp_chunk_abandoned(tchunk)) {
1344                         /* Move the chunk to abandoned list. */
1345                         sctp_insert_list(&q->abandoned, lchunk);
1346
1347                         /* If this chunk has not been acked, stop
1348                          * considering it as 'outstanding'.
1349                          */
1350                         if (!tchunk->tsn_gap_acked) {
1351                                 if (tchunk->transport)
1352                                         tchunk->transport->flight_size -=
1353                                                         sctp_data_size(tchunk);
1354                                 q->outstanding_bytes -= sctp_data_size(tchunk);
1355                         }
1356                         continue;
1357                 }
1358
1359                 tsn = ntohl(tchunk->subh.data_hdr->tsn);
1360                 if (sctp_acked(sack, tsn)) {
1361                         /* If this queue is the retransmit queue, the
1362                          * retransmit timer has already reclaimed
1363                          * the outstanding bytes for this chunk, so only
1364                          * count bytes associated with a transport.
1365                          */
1366                         if (transport) {
1367                                 /* If this chunk is being used for RTT
1368                                  * measurement, calculate the RTT and update
1369                                  * the RTO using this value.
1370                                  *
1371                                  * 6.3.1 C5) Karn's algorithm: RTT measurements
1372                                  * MUST NOT be made using packets that were
1373                                  * retransmitted (and thus for which it is
1374                                  * ambiguous whether the reply was for the
1375                                  * first instance of the packet or a later
1376                                  * instance).
1377                                  */
1378                                 if (!tchunk->tsn_gap_acked &&
1379                                     !tchunk->resent &&
1380                                     tchunk->rtt_in_progress) {
1381                                         tchunk->rtt_in_progress = 0;
1382                                         rtt = jiffies - tchunk->sent_at;
1383                                         sctp_transport_update_rto(transport,
1384                                                                   rtt);
1385                                 }
1386                         }
1387
1388                         /* If the chunk hasn't been marked as ACKED,
1389                          * mark it and account bytes_acked if the
1390                          * chunk had a valid transport (it will not
1391                          * have a transport if ASCONF had deleted it
1392                          * while DATA was outstanding).
1393                          */
1394                         if (!tchunk->tsn_gap_acked) {
1395                                 tchunk->tsn_gap_acked = 1;
1396                                 if (TSN_lt(*highest_new_tsn_in_sack, tsn))
1397                                         *highest_new_tsn_in_sack = tsn;
1398                                 bytes_acked += sctp_data_size(tchunk);
1399                                 if (!tchunk->transport)
1400                                         migrate_bytes += sctp_data_size(tchunk);
1401                                 forward_progress = true;
1402                         }
1403
1404                         if (TSN_lte(tsn, sack_ctsn)) {
1405                                 /* RFC 2960  6.3.2 Retransmission Timer Rules
1406                                  *
1407                                  * R3) Whenever a SACK is received
1408                                  * that acknowledges the DATA chunk
1409                                  * with the earliest outstanding TSN
1410                                  * for that address, restart T3-rtx
1411                                  * timer for that address with its
1412                                  * current RTO.
1413                                  */
1414                                 restart_timer = 1;
1415                                 forward_progress = true;
1416
1417                                 if (!tchunk->tsn_gap_acked) {
1418                                         /*
1419                                          * SFR-CACC algorithm:
1420                                          * 2) If the SACK contains gap acks
1421                                          * and the flag CHANGEOVER_ACTIVE is
1422                                          * set the receiver of the SACK MUST
1423                                          * take the following action:
1424                                          *
1425                                          * B) For each TSN t being acked that
1426                                          * has not been acked in any SACK so
1427                                          * far, set cacc_saw_newack to 1 for
1428                                          * the destination that the TSN was
1429                                          * sent to.
1430                                          */
1431                                         if (transport &&
1432                                             sack->num_gap_ack_blocks &&
1433                                             q->asoc->peer.primary_path->cacc.
1434                                             changeover_active)
1435                                                 transport->cacc.cacc_saw_newack
1436                                                         = 1;
1437                                 }
1438
1439                                 list_add_tail(&tchunk->transmitted_list,
1440                                               &q->sacked);
1441                         } else {
1442                                 /* RFC2960 7.2.4, sctpimpguide-05 2.8.2
1443                                  * M2) Each time a SACK arrives reporting
1444                                  * 'Stray DATA chunk(s)' record the highest TSN
1445                                  * reported as newly acknowledged, call this
1446                                  * value 'HighestTSNinSack'. A newly
1447                                  * acknowledged DATA chunk is one not
1448                                  * previously acknowledged in a SACK.
1449                                  *
1450                                  * When the SCTP sender of data receives a SACK
1451                                  * chunk that acknowledges, for the first time,
1452                                  * the receipt of a DATA chunk, all the still
1453                                  * unacknowledged DATA chunks whose TSN is
1454                                  * older than that newly acknowledged DATA
1455                                  * chunk, are qualified as 'Stray DATA chunks'.
1456                                  */
1457                                 list_add_tail(lchunk, &tlist);
1458                         }
1459                 } else {
1460                         if (tchunk->tsn_gap_acked) {
1461                                 pr_debug("%s: receiver reneged on data TSN:0x%x\n",
1462                                          __func__, tsn);
1463
1464                                 tchunk->tsn_gap_acked = 0;
1465
1466                                 if (tchunk->transport)
1467                                         bytes_acked -= sctp_data_size(tchunk);
1468
1469                                 /* RFC 2960 6.3.2 Retransmission Timer Rules
1470                                  *
1471                                  * R4) Whenever a SACK is received missing a
1472                                  * TSN that was previously acknowledged via a
1473                                  * Gap Ack Block, start T3-rtx for the
1474                                  * destination address to which the DATA
1475                                  * chunk was originally
1476                                  * transmitted if it is not already running.
1477                                  */
1478                                 restart_timer = 1;
1479                         }
1480
1481                         list_add_tail(lchunk, &tlist);
1482                 }
1483         }
1484
1485         if (transport) {
1486                 if (bytes_acked) {
1487                         struct sctp_association *asoc = transport->asoc;
1488
1489                         /* We may have counted DATA that was migrated
1490                          * to this transport due to DEL-IP operation.
1491                          * Subtract those bytes, since the were never
1492                          * send on this transport and shouldn't be
1493                          * credited to this transport.
1494                          */
1495                         bytes_acked -= migrate_bytes;
1496
1497                         /* 8.2. When an outstanding TSN is acknowledged,
1498                          * the endpoint shall clear the error counter of
1499                          * the destination transport address to which the
1500                          * DATA chunk was last sent.
1501                          * The association's overall error counter is
1502                          * also cleared.
1503                          */
1504                         transport->error_count = 0;
1505                         transport->asoc->overall_error_count = 0;
1506                         forward_progress = true;
1507
1508                         /*
1509                          * While in SHUTDOWN PENDING, we may have started
1510                          * the T5 shutdown guard timer after reaching the
1511                          * retransmission limit. Stop that timer as soon
1512                          * as the receiver acknowledged any data.
1513                          */
1514                         if (asoc->state == SCTP_STATE_SHUTDOWN_PENDING &&
1515                             del_timer(&asoc->timers
1516                                 [SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD]))
1517                                         sctp_association_put(asoc);
1518
1519                         /* Mark the destination transport address as
1520                          * active if it is not so marked.
1521                          */
1522                         if ((transport->state == SCTP_INACTIVE ||
1523                              transport->state == SCTP_UNCONFIRMED) &&
1524                             sctp_cmp_addr_exact(&transport->ipaddr, saddr)) {
1525                                 sctp_assoc_control_transport(
1526                                         transport->asoc,
1527                                         transport,
1528                                         SCTP_TRANSPORT_UP,
1529                                         SCTP_RECEIVED_SACK);
1530                         }
1531
1532                         sctp_transport_raise_cwnd(transport, sack_ctsn,
1533                                                   bytes_acked);
1534
1535                         transport->flight_size -= bytes_acked;
1536                         if (transport->flight_size == 0)
1537                                 transport->partial_bytes_acked = 0;
1538                         q->outstanding_bytes -= bytes_acked + migrate_bytes;
1539                 } else {
1540                         /* RFC 2960 6.1, sctpimpguide-06 2.15.2
1541                          * When a sender is doing zero window probing, it
1542                          * should not timeout the association if it continues
1543                          * to receive new packets from the receiver. The
1544                          * reason is that the receiver MAY keep its window
1545                          * closed for an indefinite time.
1546                          * A sender is doing zero window probing when the
1547                          * receiver's advertised window is zero, and there is
1548                          * only one data chunk in flight to the receiver.
1549                          *
1550                          * Allow the association to timeout while in SHUTDOWN
1551                          * PENDING or SHUTDOWN RECEIVED in case the receiver
1552                          * stays in zero window mode forever.
1553                          */
1554                         if (!q->asoc->peer.rwnd &&
1555                             !list_empty(&tlist) &&
1556                             (sack_ctsn+2 == q->asoc->next_tsn) &&
1557                             q->asoc->state < SCTP_STATE_SHUTDOWN_PENDING) {
1558                                 pr_debug("%s: sack received for zero window "
1559                                          "probe:%u\n", __func__, sack_ctsn);
1560
1561                                 q->asoc->overall_error_count = 0;
1562                                 transport->error_count = 0;
1563                         }
1564                 }
1565
1566                 /* RFC 2960 6.3.2 Retransmission Timer Rules
1567                  *
1568                  * R2) Whenever all outstanding data sent to an address have
1569                  * been acknowledged, turn off the T3-rtx timer of that
1570                  * address.
1571                  */
1572                 if (!transport->flight_size) {
1573                         if (del_timer(&transport->T3_rtx_timer))
1574                                 sctp_transport_put(transport);
1575                 } else if (restart_timer) {
1576                         if (!mod_timer(&transport->T3_rtx_timer,
1577                                        jiffies + transport->rto))
1578                                 sctp_transport_hold(transport);
1579                 }
1580
1581                 if (forward_progress) {
1582                         if (transport->dst)
1583                                 dst_confirm(transport->dst);
1584                 }
1585         }
1586
1587         list_splice(&tlist, transmitted_queue);
1588 }
1589
1590 /* Mark chunks as missing and consequently may get retransmitted. */
1591 static void sctp_mark_missing(struct sctp_outq *q,
1592                               struct list_head *transmitted_queue,
1593                               struct sctp_transport *transport,
1594                               __u32 highest_new_tsn_in_sack,
1595                               int count_of_newacks)
1596 {
1597         struct sctp_chunk *chunk;
1598         __u32 tsn;
1599         char do_fast_retransmit = 0;
1600         struct sctp_association *asoc = q->asoc;
1601         struct sctp_transport *primary = asoc->peer.primary_path;
1602
1603         list_for_each_entry(chunk, transmitted_queue, transmitted_list) {
1604
1605                 tsn = ntohl(chunk->subh.data_hdr->tsn);
1606
1607                 /* RFC 2960 7.2.4, sctpimpguide-05 2.8.2 M3) Examine all
1608                  * 'Unacknowledged TSN's', if the TSN number of an
1609                  * 'Unacknowledged TSN' is smaller than the 'HighestTSNinSack'
1610                  * value, increment the 'TSN.Missing.Report' count on that
1611                  * chunk if it has NOT been fast retransmitted or marked for
1612                  * fast retransmit already.
1613                  */
1614                 if (chunk->fast_retransmit == SCTP_CAN_FRTX &&
1615                     !chunk->tsn_gap_acked &&
1616                     TSN_lt(tsn, highest_new_tsn_in_sack)) {
1617
1618                         /* SFR-CACC may require us to skip marking
1619                          * this chunk as missing.
1620                          */
1621                         if (!transport || !sctp_cacc_skip(primary,
1622                                                 chunk->transport,
1623                                                 count_of_newacks, tsn)) {
1624                                 chunk->tsn_missing_report++;
1625
1626                                 pr_debug("%s: tsn:0x%x missing counter:%d\n",
1627                                          __func__, tsn, chunk->tsn_missing_report);
1628                         }
1629                 }
1630                 /*
1631                  * M4) If any DATA chunk is found to have a
1632                  * 'TSN.Missing.Report'
1633                  * value larger than or equal to 3, mark that chunk for
1634                  * retransmission and start the fast retransmit procedure.
1635                  */
1636
1637                 if (chunk->tsn_missing_report >= 3) {
1638                         chunk->fast_retransmit = SCTP_NEED_FRTX;
1639                         do_fast_retransmit = 1;
1640                 }
1641         }
1642
1643         if (transport) {
1644                 if (do_fast_retransmit)
1645                         sctp_retransmit(q, transport, SCTP_RTXR_FAST_RTX);
1646
1647                 pr_debug("%s: transport:%p, cwnd:%d, ssthresh:%d, "
1648                          "flight_size:%d, pba:%d\n",  __func__, transport,
1649                          transport->cwnd, transport->ssthresh,
1650                          transport->flight_size, transport->partial_bytes_acked);
1651         }
1652 }
1653
1654 /* Is the given TSN acked by this packet?  */
1655 static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn)
1656 {
1657         int i;
1658         sctp_sack_variable_t *frags;
1659         __u16 gap;
1660         __u32 ctsn = ntohl(sack->cum_tsn_ack);
1661
1662         if (TSN_lte(tsn, ctsn))
1663                 goto pass;
1664
1665         /* 3.3.4 Selective Acknowledgement (SACK) (3):
1666          *
1667          * Gap Ack Blocks:
1668          *  These fields contain the Gap Ack Blocks. They are repeated
1669          *  for each Gap Ack Block up to the number of Gap Ack Blocks
1670          *  defined in the Number of Gap Ack Blocks field. All DATA
1671          *  chunks with TSNs greater than or equal to (Cumulative TSN
1672          *  Ack + Gap Ack Block Start) and less than or equal to
1673          *  (Cumulative TSN Ack + Gap Ack Block End) of each Gap Ack
1674          *  Block are assumed to have been received correctly.
1675          */
1676
1677         frags = sack->variable;
1678         gap = tsn - ctsn;
1679         for (i = 0; i < ntohs(sack->num_gap_ack_blocks); ++i) {
1680                 if (TSN_lte(ntohs(frags[i].gab.start), gap) &&
1681                     TSN_lte(gap, ntohs(frags[i].gab.end)))
1682                         goto pass;
1683         }
1684
1685         return 0;
1686 pass:
1687         return 1;
1688 }
1689
1690 static inline int sctp_get_skip_pos(struct sctp_fwdtsn_skip *skiplist,
1691                                     int nskips, __be16 stream)
1692 {
1693         int i;
1694
1695         for (i = 0; i < nskips; i++) {
1696                 if (skiplist[i].stream == stream)
1697                         return i;
1698         }
1699         return i;
1700 }
1701
1702 /* Create and add a fwdtsn chunk to the outq's control queue if needed. */
1703 static void sctp_generate_fwdtsn(struct sctp_outq *q, __u32 ctsn)
1704 {
1705         struct sctp_association *asoc = q->asoc;
1706         struct sctp_chunk *ftsn_chunk = NULL;
1707         struct sctp_fwdtsn_skip ftsn_skip_arr[10];
1708         int nskips = 0;
1709         int skip_pos = 0;
1710         __u32 tsn;
1711         struct sctp_chunk *chunk;
1712         struct list_head *lchunk, *temp;
1713
1714         if (!asoc->peer.prsctp_capable)
1715                 return;
1716
1717         /* PR-SCTP C1) Let SackCumAck be the Cumulative TSN ACK carried in the
1718          * received SACK.
1719          *
1720          * If (Advanced.Peer.Ack.Point < SackCumAck), then update
1721          * Advanced.Peer.Ack.Point to be equal to SackCumAck.
1722          */
1723         if (TSN_lt(asoc->adv_peer_ack_point, ctsn))
1724                 asoc->adv_peer_ack_point = ctsn;
1725
1726         /* PR-SCTP C2) Try to further advance the "Advanced.Peer.Ack.Point"
1727          * locally, that is, to move "Advanced.Peer.Ack.Point" up as long as
1728          * the chunk next in the out-queue space is marked as "abandoned" as
1729          * shown in the following example:
1730          *
1731          * Assuming that a SACK arrived with the Cumulative TSN ACK 102
1732          * and the Advanced.Peer.Ack.Point is updated to this value:
1733          *
1734          *   out-queue at the end of  ==>   out-queue after Adv.Ack.Point
1735          *   normal SACK processing           local advancement
1736          *                ...                           ...
1737          *   Adv.Ack.Pt-> 102 acked                     102 acked
1738          *                103 abandoned                 103 abandoned
1739          *                104 abandoned     Adv.Ack.P-> 104 abandoned
1740          *                105                           105
1741          *                106 acked                     106 acked
1742          *                ...                           ...
1743          *
1744          * In this example, the data sender successfully advanced the
1745          * "Advanced.Peer.Ack.Point" from 102 to 104 locally.
1746          */
1747         list_for_each_safe(lchunk, temp, &q->abandoned) {
1748                 chunk = list_entry(lchunk, struct sctp_chunk,
1749                                         transmitted_list);
1750                 tsn = ntohl(chunk->subh.data_hdr->tsn);
1751
1752                 /* Remove any chunks in the abandoned queue that are acked by
1753                  * the ctsn.
1754                  */
1755                 if (TSN_lte(tsn, ctsn)) {
1756                         list_del_init(lchunk);
1757                         sctp_chunk_free(chunk);
1758                 } else {
1759                         if (TSN_lte(tsn, asoc->adv_peer_ack_point+1)) {
1760                                 asoc->adv_peer_ack_point = tsn;
1761                                 if (chunk->chunk_hdr->flags &
1762                                          SCTP_DATA_UNORDERED)
1763                                         continue;
1764                                 skip_pos = sctp_get_skip_pos(&ftsn_skip_arr[0],
1765                                                 nskips,
1766                                                 chunk->subh.data_hdr->stream);
1767                                 ftsn_skip_arr[skip_pos].stream =
1768                                         chunk->subh.data_hdr->stream;
1769                                 ftsn_skip_arr[skip_pos].ssn =
1770                                          chunk->subh.data_hdr->ssn;
1771                                 if (skip_pos == nskips)
1772                                         nskips++;
1773                                 if (nskips == 10)
1774                                         break;
1775                         } else
1776                                 break;
1777                 }
1778         }
1779
1780         /* PR-SCTP C3) If, after step C1 and C2, the "Advanced.Peer.Ack.Point"
1781          * is greater than the Cumulative TSN ACK carried in the received
1782          * SACK, the data sender MUST send the data receiver a FORWARD TSN
1783          * chunk containing the latest value of the
1784          * "Advanced.Peer.Ack.Point".
1785          *
1786          * C4) For each "abandoned" TSN the sender of the FORWARD TSN SHOULD
1787          * list each stream and sequence number in the forwarded TSN. This
1788          * information will enable the receiver to easily find any
1789          * stranded TSN's waiting on stream reorder queues. Each stream
1790          * SHOULD only be reported once; this means that if multiple
1791          * abandoned messages occur in the same stream then only the
1792          * highest abandoned stream sequence number is reported. If the
1793          * total size of the FORWARD TSN does NOT fit in a single MTU then
1794          * the sender of the FORWARD TSN SHOULD lower the
1795          * Advanced.Peer.Ack.Point to the last TSN that will fit in a
1796          * single MTU.
1797          */
1798         if (asoc->adv_peer_ack_point > ctsn)
1799                 ftsn_chunk = sctp_make_fwdtsn(asoc, asoc->adv_peer_ack_point,
1800                                               nskips, &ftsn_skip_arr[0]);
1801
1802         if (ftsn_chunk) {
1803                 list_add_tail(&ftsn_chunk->list, &q->control_chunk_list);
1804                 SCTP_INC_STATS(sock_net(asoc->base.sk), SCTP_MIB_OUTCTRLCHUNKS);
1805         }
1806 }