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