net/sctp/outqueue.c

   1 /* SCTP kernel implementation
   2  * (C) Copyright IBM Corp. 2001, 2004
   3  * Copyright (c) 1999-2000 Cisco, Inc.
   4  * Copyright (c) 1999-2001 Motorola, Inc.
   5  * Copyright (c) 2001-2003 Intel Corp.
   6  *
   7  * This file is part of the SCTP kernel implementation
   8  *
   9  * These functions implement the sctp_outq class.   The outqueue handles
  10  * bundling and queueing of outgoing SCTP chunks.
  11  *
  12  * This SCTP implementation is free software;
  13  * you can redistribute it and/or modify it under the terms of
  14  * the GNU General Public License as published by
  15  * the Free Software Foundation; either version 2, or (at your option)
  16  * any later version.
  17  *
  18  * This SCTP implementation is distributed in the hope that it
  19  * will be useful, but WITHOUT ANY WARRANTY; without even the implied
  20  *                 ************************
  21  * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  22  * See the GNU General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU General Public License
  25  * along with GNU CC; see the file COPYING.  If not, write to
  26  * the Free Software Foundation, 59 Temple Place - Suite 330,
  27  * Boston, MA 02111-1307, USA.
  28  *
  29  * Please send any bug reports or fixes you make to the
  30  * email address(es):
  31  *    lksctp developers <linux-sctp@vger.kernel.org>
  32  *
  33  * Written or modified by:
  34  *    La Monte H.P. Yarroll <piggy@acm.org>
  35  *    Karl Knutson          <karl@athena.chicago.il.us>
  36  *    Perry Melange         <pmelange@null.cc.uic.edu>
  37  *    Xingang Guo           <xingang.guo@intel.com>
  38  *    Hui Huang             <hui.huang@nokia.com>
  39  *    Sridhar Samudrala     <sri@us.ibm.com>
  40  *    Jon Grimm             <jgrimm@us.ibm.com>
  41  */
  42
  43 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  44
  45 #include <linux/types.h>
  46 #include <linux/list.h>   /* For struct list_head */
  47 #include <linux/socket.h>
  48 #include <linux/ip.h>
  49 #include <linux/slab.h>
  50 #include <net/sock.h>     /* For skb_set_owner_w */
  51
  52 #include <net/sctp/sctp.h>
  53 #include <net/sctp/sm.h>
  54
  55 /* Declare internal functions here.  */
  56 static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn);
  57 static void sctp_check_transmitted(struct sctp_outq *q,
  58                                    struct list_head *transmitted_queue,
  59                                    struct sctp_transport *transport,
  60                                    union sctp_addr *saddr,
  61                                    struct sctp_sackhdr *sack,
  62                                    __u32 *highest_new_tsn);
  63
  64 static void sctp_mark_missing(struct sctp_outq *q,
  65                               struct list_head *transmitted_queue,
  66                               struct sctp_transport *transport,
  67                               __u32 highest_new_tsn,
  68                               int count_of_newacks);
  69
  70 static void sctp_generate_fwdtsn(struct sctp_outq *q, __u32 sack_ctsn);
  71
  72 static int sctp_outq_flush(struct sctp_outq *q, int rtx_timeout);
  73
  74 /* Add data to the front of the queue. */
  75 static inline void sctp_outq_head_data(struct sctp_outq *q,
  76                                         struct sctp_chunk *ch)
  77 {
  78         list_add(&ch->list, &q->out_chunk_list);
  79         q->out_qlen += ch->skb->len;
  80 }
  81
  82 /* Take data from the front of the queue. */
  83 static inline struct sctp_chunk *sctp_outq_dequeue_data(struct sctp_outq *q)
  84 {
  85         struct sctp_chunk *ch = NULL;
  86
  87         if (!list_empty(&q->out_chunk_list)) {
  88                 struct list_head *entry = q->out_chunk_list.next;
  89
  90                 ch = list_entry(entry, struct sctp_chunk, list);
  91                 list_del_init(entry);
  92                 q->out_qlen -= ch->skb->len;
  93         }
  94         return ch;
  95 }
  96 /* Add data chunk to the end of the queue. */
  97 static inline void sctp_outq_tail_data(struct sctp_outq *q,
  98                                        struct sctp_chunk *ch)
  99 {
 100         list_add_tail(&ch->list, &q->out_chunk_list);
 101         q->out_qlen += ch->skb->len;
 102 }
 103
 104 /*
 105  * SFR-CACC algorithm:
 106  * D) If count_of_newacks is greater than or equal to 2
 107  * and t was not sent to the current primary then the
 108  * sender MUST NOT increment missing report count for t.
 109  */
 110 static inline int sctp_cacc_skip_3_1_d(struct sctp_transport *primary,
 111                                        struct sctp_transport *transport,
 112                                        int count_of_newacks)
 113 {
 114         if (count_of_newacks >=2 && transport != primary)
 115                 return 1;
 116         return 0;
 117 }
 118
 119 /*
 120  * SFR-CACC algorithm:
 121  * F) If count_of_newacks is less than 2, let d be the
 122  * destination to which t was sent. If cacc_saw_newack
 123  * is 0 for destination d, then the sender MUST NOT
 124  * increment missing report count for t.
 125  */
 126 static inline int sctp_cacc_skip_3_1_f(struct sctp_transport *transport,
 127                                        int count_of_newacks)
 128 {
 129         if (count_of_newacks < 2 &&
 130                         (transport && !transport->cacc.cacc_saw_newack))
 131                 return 1;
 132         return 0;
 133 }
 134
 135 /*
 136  * SFR-CACC algorithm:
 137  * 3.1) If CYCLING_CHANGEOVER is 0, the sender SHOULD
 138  * execute steps C, D, F.
 139  *
 140  * C has been implemented in sctp_outq_sack
 141  */
 142 static inline int sctp_cacc_skip_3_1(struct sctp_transport *primary,
 143                                      struct sctp_transport *transport,
 144                                      int count_of_newacks)
 145 {
 146         if (!primary->cacc.cycling_changeover) {
 147                 if (sctp_cacc_skip_3_1_d(primary, transport, count_of_newacks))
 148                         return 1;
 149                 if (sctp_cacc_skip_3_1_f(transport, count_of_newacks))
 150                         return 1;
 151                 return 0;
 152         }
 153         return 0;
 154 }
 155
 156 /*
 157  * SFR-CACC algorithm:
 158  * 3.2) Else if CYCLING_CHANGEOVER is 1, and t is less
 159  * than next_tsn_at_change of the current primary, then
 160  * the sender MUST NOT increment missing report count
 161  * for t.
 162  */
 163 static inline int sctp_cacc_skip_3_2(struct sctp_transport *primary, __u32 tsn)
 164 {
 165         if (primary->cacc.cycling_changeover &&
 166             TSN_lt(tsn, primary->cacc.next_tsn_at_change))
 167                 return 1;
 168         return 0;
 169 }
 170
 171 /*
 172  * SFR-CACC algorithm:
 173  * 3) If the missing report count for TSN t is to be
 174  * incremented according to [RFC2960] and
 175  * [SCTP_STEWART-2002], and CHANGEOVER_ACTIVE is set,
 176  * then the sender MUST further execute steps 3.1 and
 177  * 3.2 to determine if the missing report count for
 178  * TSN t SHOULD NOT be incremented.
 179  *
 180  * 3.3) If 3.1 and 3.2 do not dictate that the missing
 181  * report count for t should not be incremented, then
 182  * the sender SHOULD increment missing report count for
 183  * t (according to [RFC2960] and [SCTP_STEWART_2002]).
 184  */
 185 static inline int sctp_cacc_skip(struct sctp_transport *primary,
 186                                  struct sctp_transport *transport,
 187                                  int count_of_newacks,
 188                                  __u32 tsn)
 189 {
 190         if (primary->cacc.changeover_active &&
 191             (sctp_cacc_skip_3_1(primary, transport, count_of_newacks) ||
 192              sctp_cacc_skip_3_2(primary, tsn)))
 193                 return 1;
 194         return 0;
 195 }
 196
 197 /* Initialize an existing sctp_outq.  This does the boring stuff.
 198  * You still need to define handlers if you really want to DO
 199  * something with this structure...
 200  */
 201 void sctp_outq_init(struct sctp_association *asoc, struct sctp_outq *q)
 202 {
 203         memset(q, 0, sizeof(struct sctp_outq));
 204
 205         q->asoc = asoc;
 206         INIT_LIST_HEAD(&q->out_chunk_list);
 207         INIT_LIST_HEAD(&q->control_chunk_list);
 208         INIT_LIST_HEAD(&q->retransmit);
 209         INIT_LIST_HEAD(&q->sacked);
 210         INIT_LIST_HEAD(&q->abandoned);
 211
 212         q->empty = 1;
 213 }
 214
 215 /* Free the outqueue structure and any related pending chunks.
 216  */
 217 static void __sctp_outq_teardown(struct sctp_outq *q)
 218 {
 219         struct sctp_transport *transport;
 220         struct list_head *lchunk, *temp;
 221         struct sctp_chunk *chunk, *tmp;
 222
 223         /* Throw away unacknowledged chunks. */
 224         list_for_each_entry(transport, &q->asoc->peer.transport_addr_list,
 225                         transports) {
 226                 while ((lchunk = sctp_list_dequeue(&transport->transmitted)) != NULL) {
 227                         chunk = list_entry(lchunk, struct sctp_chunk,
 228                                            transmitted_list);
 229                         /* Mark as part of a failed message. */
 230                         sctp_chunk_fail(chunk, q->error);
 231                         sctp_chunk_free(chunk);
 232                 }
 233         }
 234
 235         /* Throw away chunks that have been gap ACKed.  */
 236         list_for_each_safe(lchunk, temp, &q->sacked) {
 237                 list_del_init(lchunk);
 238                 chunk = list_entry(lchunk, struct sctp_chunk,
 239                                    transmitted_list);
 240                 sctp_chunk_fail(chunk, q->error);
 241                 sctp_chunk_free(chunk);
 242         }
 243
 244         /* Throw away any chunks in the retransmit queue. */
 245         list_for_each_safe(lchunk, temp, &q->retransmit) {
 246                 list_del_init(lchunk);
 247                 chunk = list_entry(lchunk, struct sctp_chunk,
 248                                    transmitted_list);
 249                 sctp_chunk_fail(chunk, q->error);
 250                 sctp_chunk_free(chunk);
 251         }
 252
 253         /* Throw away any chunks that are in the abandoned queue. */
 254         list_for_each_safe(lchunk, temp, &q->abandoned) {
 255                 list_del_init(lchunk);
 256                 chunk = list_entry(lchunk, struct sctp_chunk,
 257                                    transmitted_list);
 258                 sctp_chunk_fail(chunk, q->error);
 259                 sctp_chunk_free(chunk);
 260         }
 261
 262         /* Throw away any leftover data chunks. */
 263         while ((chunk = sctp_outq_dequeue_data(q)) != NULL) {
 264
 265                 /* Mark as send failure. */
 266                 sctp_chunk_fail(chunk, q->error);
 267                 sctp_chunk_free(chunk);
 268         }
 269
 270         /* Throw away any leftover control chunks. */
 271         list_for_each_entry_safe(chunk, tmp, &q->control_chunk_list, list) {
 272                 list_del_init(&chunk->list);
 273                 sctp_chunk_free(chunk);
 274         }
 275 }
 276
 277 void sctp_outq_teardown(struct sctp_outq *q)
 278 {
 279         __sctp_outq_teardown(q);
 280         sctp_outq_init(q->asoc, q);
 281 }
 282
 283 /* Free the outqueue structure and any related pending chunks.  */
 284 void sctp_outq_free(struct sctp_outq *q)
 285 {
 286         /* Throw away leftover chunks. */
 287         __sctp_outq_teardown(q);
 288 }
 289
 290 /* Put a new chunk in an sctp_outq.  */
 291 int sctp_outq_tail(struct sctp_outq *q, struct sctp_chunk *chunk)
 292 {
 293         struct net *net = sock_net(q->asoc->base.sk);
 294         int error = 0;
 295
 296         pr_debug("%s: outq:%p, chunk:%p[%s]\n", __func__, q, chunk,
 297                  chunk && chunk->chunk_hdr ?
 298                  sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)) :
 299                  "illegal chunk");
 300
 301         /* If it is data, queue it up, otherwise, send it
 302          * immediately.
 303          */
 304         if (sctp_chunk_is_data(chunk)) {
 305                 /* Is it OK to queue data chunks?  */
 306                 /* From 9. Termination of Association
 307                  *
 308                  * When either endpoint performs a shutdown, the
 309                  * association on each peer will stop accepting new
 310                  * data from its user and only deliver data in queue
 311                  * at the time of sending or receiving the SHUTDOWN
 312                  * chunk.
 313                  */
 314                 switch (q->asoc->state) {
 315                 case SCTP_STATE_CLOSED:
 316                 case SCTP_STATE_SHUTDOWN_PENDING:
 317                 case SCTP_STATE_SHUTDOWN_SENT:
 318                 case SCTP_STATE_SHUTDOWN_RECEIVED:
 319                 case SCTP_STATE_SHUTDOWN_ACK_SENT:
 320                         /* Cannot send after transport endpoint shutdown */
 321                         error = -ESHUTDOWN;
 322                         break;
 323
 324                 default:
 325                         pr_debug("%s: outqueueing: outq:%p, chunk:%p[%s])\n",
 326                                  __func__, q, chunk, chunk && chunk->chunk_hdr ?
 327                                  sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)) :
 328                                  "illegal chunk");
 329
 330                         sctp_outq_tail_data(q, chunk);
 331                         if (chunk->chunk_hdr->flags & SCTP_DATA_UNORDERED)
 332                                 SCTP_INC_STATS(net, SCTP_MIB_OUTUNORDERCHUNKS);
 333                         else
 334                                 SCTP_INC_STATS(net, SCTP_MIB_OUTORDERCHUNKS);
 335                         q->empty = 0;
 336                         break;
 337                 }
 338         } else {
 339                 list_add_tail(&chunk->list, &q->control_chunk_list);
 340                 SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
 341         }
 342
 343         if (error < 0)
 344                 return error;
 345
 346         if (!q->cork)
 347                 error = sctp_outq_flush(q, 0);
 348
 349         return error;
 350 }
 351
 352 /* Insert a chunk into the sorted list based on the TSNs.  The retransmit list
 353  * and the abandoned list are in ascending order.
 354  */
 355 static void sctp_insert_list(struct list_head *head, struct list_head *new)
 356 {
 357         struct list_head *pos;
 358         struct sctp_chunk *nchunk, *lchunk;
 359         __u32 ntsn, ltsn;
 360         int done = 0;
 361
 362         nchunk = list_entry(new, struct sctp_chunk, transmitted_list);
 363         ntsn = ntohl(nchunk->subh.data_hdr->tsn);
 364
 365         list_for_each(pos, head) {
 366                 lchunk = list_entry(pos, struct sctp_chunk, transmitted_list);
 367                 ltsn = ntohl(lchunk->subh.data_hdr->tsn);
 368                 if (TSN_lt(ntsn, ltsn)) {
 369                         list_add(new, pos->prev);
 370                         done = 1;
 371                         break;
 372                 }
 373         }
 374         if (!done)
 375                 list_add_tail(new, head);
 376 }
 377
 378 /* Mark all the eligible packets on a transport for retransmission.  */
 379 void sctp_retransmit_mark(struct sctp_outq *q,
 380                           struct sctp_transport *transport,
 381                           __u8 reason)
 382 {
 383         struct list_head *lchunk, *ltemp;
 384         struct sctp_chunk *chunk;
 385
 386         /* Walk through the specified transmitted queue.  */
 387         list_for_each_safe(lchunk, ltemp, &transport->transmitted) {
 388                 chunk = list_entry(lchunk, struct sctp_chunk,
 389                                    transmitted_list);
 390
 391                 /* If the chunk is abandoned, move it to abandoned list. */
 392                 if (sctp_chunk_abandoned(chunk)) {
 393                         list_del_init(lchunk);
 394                         sctp_insert_list(&q->abandoned, lchunk);
 395
 396                         /* If this chunk has not been previousely acked,
 397                          * stop considering it 'outstanding'.  Our peer
 398                          * will most likely never see it since it will
 399                          * not be retransmitted
 400                          */
 401                         if (!chunk->tsn_gap_acked) {
 402                                 if (chunk->transport)
 403                                         chunk->transport->flight_size -=
 404                                                         sctp_data_size(chunk);
 405                                 q->outstanding_bytes -= sctp_data_size(chunk);
 406                                 q->asoc->peer.rwnd += sctp_data_size(chunk);
 407                         }
 408                         continue;
 409                 }
 410
 411                 /* If we are doing  retransmission due to a timeout or pmtu
 412                  * discovery, only the  chunks that are not yet acked should
 413                  * be added to the retransmit queue.
 414                  */
 415                 if ((reason == SCTP_RTXR_FAST_RTX  &&
 416                             (chunk->fast_retransmit == SCTP_NEED_FRTX)) ||
 417                     (reason != SCTP_RTXR_FAST_RTX  && !chunk->tsn_gap_acked)) {
 418                         /* RFC 2960 6.2.1 Processing a Received SACK
 419                          *
 420                          * C) Any time a DATA chunk is marked for
 421                          * retransmission (via either T3-rtx timer expiration
 422                          * (Section 6.3.3) or via fast retransmit
 423                          * (Section 7.2.4)), add the data size of those
 424                          * chunks to the rwnd.
 425                          */
 426                         q->asoc->peer.rwnd += sctp_data_size(chunk);
 427                         q->outstanding_bytes -= sctp_data_size(chunk);
 428                         if (chunk->transport)
 429                                 transport->flight_size -= sctp_data_size(chunk);
 430
 431                         /* sctpimpguide-05 Section 2.8.2
 432                          * M5) If a T3-rtx timer expires, the
 433                          * 'TSN.Missing.Report' of all affected TSNs is set
 434                          * to 0.
 435                          */
 436                         chunk->tsn_missing_report = 0;
 437
 438                         /* If a chunk that is being used for RTT measurement
 439                          * has to be retransmitted, we cannot use this chunk
 440                          * anymore for RTT measurements. Reset rto_pending so
 441                          * that a new RTT measurement is started when a new
 442                          * data chunk is sent.
 443                          */
 444                         if (chunk->rtt_in_progress) {
 445                                 chunk->rtt_in_progress = 0;
 446                                 transport->rto_pending = 0;
 447                         }
 448
 449                         /* Move the chunk to the retransmit queue. The chunks
 450                          * on the retransmit queue are always kept in order.
 451                          */
 452                         list_del_init(lchunk);
 453                         sctp_insert_list(&q->retransmit, lchunk);
 454                 }
 455         }
 456
 457         pr_debug("%s: transport:%p, reason:%d, cwnd:%d, ssthresh:%d, "
 458                  "flight_size:%d, pba:%d\n", __func__, transport, reason,
 459                  transport->cwnd, transport->ssthresh, transport->flight_size,
 460                  transport->partial_bytes_acked);
 461 }
 462
 463 /* Mark all the eligible packets on a transport for retransmission and force
 464  * one packet out.
 465  */
 466 void sctp_retransmit(struct sctp_outq *q, struct sctp_transport *transport,
 467                      sctp_retransmit_reason_t reason)
 468 {
 469         struct net *net = sock_net(q->asoc->base.sk);
 470         int error = 0;
 471
 472         switch(reason) {
 473         case SCTP_RTXR_T3_RTX:
 474                 SCTP_INC_STATS(net, SCTP_MIB_T3_RETRANSMITS);
 475                 sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_T3_RTX);
 476                 /* Update the retran path if the T3-rtx timer has expired for
 477                  * the current retran path.
 478                  */
 479                 if (transport == transport->asoc->peer.retran_path)
 480                         sctp_assoc_update_retran_path(transport->asoc);
 481                 transport->asoc->rtx_data_chunks +=
 482                         transport->asoc->unack_data;
 483                 break;
 484         case SCTP_RTXR_FAST_RTX:
 485                 SCTP_INC_STATS(net, SCTP_MIB_FAST_RETRANSMITS);
 486                 sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_FAST_RTX);
 487                 q->fast_rtx = 1;
 488                 break;
 489         case SCTP_RTXR_PMTUD:
 490                 SCTP_INC_STATS(net, SCTP_MIB_PMTUD_RETRANSMITS);
 491                 break;
 492         case SCTP_RTXR_T1_RTX:
 493                 SCTP_INC_STATS(net, SCTP_MIB_T1_RETRANSMITS);
 494                 transport->asoc->init_retries++;
 495                 break;
 496         default:
 497                 BUG();
 498         }
 499
 500         sctp_retransmit_mark(q, transport, reason);
 501
 502         /* PR-SCTP A5) Any time the T3-rtx timer expires, on any destination,
 503          * the sender SHOULD try to advance the "Advanced.Peer.Ack.Point" by
 504          * following the procedures outlined in C1 - C5.
 505          */
 506         if (reason == SCTP_RTXR_T3_RTX)
 507                 sctp_generate_fwdtsn(q, q->asoc->ctsn_ack_point);
 508
 509         /* Flush the queues only on timeout, since fast_rtx is only
 510          * triggered during sack processing and the queue
 511          * will be flushed at the end.
 512          */
 513         if (reason != SCTP_RTXR_FAST_RTX)
 514                 error = sctp_outq_flush(q, /* rtx_timeout */ 1);
 515
 516         if (error)
 517                 q->asoc->base.sk->sk_err = -error;
 518 }
 519
 520 /*
 521  * Transmit DATA chunks on the retransmit queue.  Upon return from
 522  * sctp_outq_flush_rtx() the packet 'pkt' may contain chunks which
 523  * need to be transmitted by the caller.
 524  * We assume that pkt->transport has already been set.
 525  *
 526  * The return value is a normal kernel error return value.
 527  */
 528 static int sctp_outq_flush_rtx(struct sctp_outq *q, struct sctp_packet *pkt,
 529                                int rtx_timeout, int *start_timer)
 530 {
 531         struct list_head *lqueue;
 532         struct sctp_transport *transport = pkt->transport;
 533         sctp_xmit_t status;
 534         struct sctp_chunk *chunk, *chunk1;
 535         int fast_rtx;
 536         int error = 0;
 537         int timer = 0;
 538         int done = 0;
 539
 540         lqueue = &q->retransmit;
 541         fast_rtx = q->fast_rtx;
 542
 543         /* This loop handles time-out retransmissions, fast retransmissions,
 544          * and retransmissions due to opening of whindow.
 545          *
 546          * RFC 2960 6.3.3 Handle T3-rtx Expiration
 547          *
 548          * E3) Determine how many of the earliest (i.e., lowest TSN)
 549          * outstanding DATA chunks for the address for which the
 550          * T3-rtx has expired will fit into a single packet, subject
 551          * to the MTU constraint for the path corresponding to the
 552          * destination transport address to which the retransmission
 553          * is being sent (this may be different from the address for
 554          * which the timer expires [see Section 6.4]). Call this value
 555          * K. Bundle and retransmit those K DATA chunks in a single
 556          * packet to the destination endpoint.
 557          *
 558          * [Just to be painfully clear, if we are retransmitting
 559          * because a timeout just happened, we should send only ONE
 560          * packet of retransmitted data.]
 561          *
 562          * For fast retransmissions we also send only ONE packet.  However,
 563          * if we are just flushing the queue due to open window, we'll
 564          * try to send as much as possible.
 565          */
 566         list_for_each_entry_safe(chunk, chunk1, lqueue, transmitted_list) {
 567                 /* If the chunk is abandoned, move it to abandoned list. */
 568                 if (sctp_chunk_abandoned(chunk)) {
 569                         list_del_init(&chunk->transmitted_list);
 570                         sctp_insert_list(&q->abandoned,
 571                                          &chunk->transmitted_list);
 572                         continue;
 573                 }
 574
 575                 /* Make sure that Gap Acked TSNs are not retransmitted.  A
 576                  * simple approach is just to move such TSNs out of the
 577                  * way and into a 'transmitted' queue and skip to the
 578                  * next chunk.
 579                  */
 580                 if (chunk->tsn_gap_acked) {
 581                         list_move_tail(&chunk->transmitted_list,
 582                                        &transport->transmitted);
 583                         continue;
 584                 }
 585
 586                 /* If we are doing fast retransmit, ignore non-fast_rtransmit
 587                  * chunks
 588                  */
 589                 if (fast_rtx && !chunk->fast_retransmit)
 590                         continue;
 591
 592 redo:
 593                 /* Attempt to append this chunk to the packet. */
 594                 status = sctp_packet_append_chunk(pkt, chunk);
 595
 596                 switch (status) {
 597                 case SCTP_XMIT_PMTU_FULL:
 598                         if (!pkt->has_data && !pkt->has_cookie_echo) {
 599                                 /* If this packet did not contain DATA then
 600                                  * retransmission did not happen, so do it
 601                                  * again.  We'll ignore the error here since
 602                                  * control chunks are already freed so there
 603                                  * is nothing we can do.
 604                                  */
 605                                 sctp_packet_transmit(pkt);
 606                                 goto redo;
 607                         }
 608
 609                         /* Send this packet.  */
 610                         error = sctp_packet_transmit(pkt);
 611
 612                         /* If we are retransmitting, we should only
 613                          * send a single packet.
 614                          * Otherwise, try appending this chunk again.
 615                          */
 616                         if (rtx_timeout || fast_rtx)
 617                                 done = 1;
 618                         else
 619                                 goto redo;
 620
 621                         /* Bundle next chunk in the next round.  */
 622                         break;
 623
 624                 case SCTP_XMIT_RWND_FULL:
 625                         /* Send this packet. */
 626                         error = sctp_packet_transmit(pkt);
 627
 628                         /* Stop sending DATA as there is no more room
 629                          * at the receiver.
 630                          */
 631                         done = 1;
 632                         break;
 633
 634                 case SCTP_XMIT_NAGLE_DELAY:
 635                         /* Send this packet. */
 636                         error = sctp_packet_transmit(pkt);
 637
 638                         /* Stop sending DATA because of nagle delay. */
 639                         done = 1;
 640                         break;
 641
 642                 default:
 643                         /* The append was successful, so add this chunk to
 644                          * the transmitted list.
 645                          */
 646                         list_move_tail(&chunk->transmitted_list,
 647                                        &transport->transmitted);
 648
 649                         /* Mark the chunk as ineligible for fast retransmit
 650                          * after it is retransmitted.
 651                          */
 652                         if (chunk->fast_retransmit == SCTP_NEED_FRTX)
 653                                 chunk->fast_retransmit = SCTP_DONT_FRTX;
 654
 655                         q->empty = 0;
 656                         q->asoc->stats.rtxchunks++;
 657                         break;
 658                 }
 659
 660                 /* Set the timer if there were no errors */
 661                 if (!error && !timer)
 662                         timer = 1;
 663
 664                 if (done)
 665                         break;
 666         }
 667
 668         /* If we are here due to a retransmit timeout or a fast
 669          * retransmit and if there are any chunks left in the retransmit
 670          * queue that could not fit in the PMTU sized packet, they need
 671          * to be marked as ineligible for a subsequent fast retransmit.
 672          */
 673         if (rtx_timeout || fast_rtx) {
 674                 list_for_each_entry(chunk1, lqueue, transmitted_list) {
 675                         if (chunk1->fast_retransmit == SCTP_NEED_FRTX)
 676                                 chunk1->fast_retransmit = SCTP_DONT_FRTX;
 677                 }
 678         }
 679
 680         *start_timer = timer;
 681
 682         /* Clear fast retransmit hint */
 683         if (fast_rtx)
 684                 q->fast_rtx = 0;
 685
 686         return error;
 687 }
 688
 689 /* Cork the outqueue so queued chunks are really queued. */
 690 int sctp_outq_uncork(struct sctp_outq *q)
 691 {
 692         if (q->cork)
 693                 q->cork = 0;
 694
 695         return sctp_outq_flush(q, 0);
 696 }
 697
 698
 699 /*
 700  * Try to flush an outqueue.
 701  *
 702  * Description: Send everything in q which we legally can, subject to
 703  * congestion limitations.
 704  * * Note: This function can be called from multiple contexts so appropriate
 705  * locking concerns must be made.  Today we use the sock lock to protect
 706  * this function.
 707  */
 708 static int sctp_outq_flush(struct sctp_outq *q, int rtx_timeout)
 709 {
 710         struct sctp_packet *packet;
 711         struct sctp_packet singleton;
 712         struct sctp_association *asoc = q->asoc;
 713         __u16 sport = asoc->base.bind_addr.port;
 714         __u16 dport = asoc->peer.port;
 715         __u32 vtag = asoc->peer.i.init_tag;
 716         struct sctp_transport *transport = NULL;
 717         struct sctp_transport *new_transport;
 718         struct sctp_chunk *chunk, *tmp;
 719         sctp_xmit_t status;
 720         int error = 0;
 721         int start_timer = 0;
 722         int one_packet = 0;
 723
 724         /* These transports have chunks to send. */
 725         struct list_head transport_list;
 726         struct list_head *ltransport;
 727
 728         INIT_LIST_HEAD(&transport_list);
 729         packet = NULL;
 730
 731         /*
 732          * 6.10 Bundling
 733          *   ...
 734          *   When bundling control chunks with DATA chunks, an
 735          *   endpoint MUST place control chunks first in the outbound
 736          *   SCTP packet.  The transmitter MUST transmit DATA chunks
 737          *   within a SCTP packet in increasing order of TSN.
 738          *   ...
 739          */
 740
 741         list_for_each_entry_safe(chunk, tmp, &q->control_chunk_list, list) {
 742                 /* RFC 5061, 5.3
 743                  * F1) This means that until such time as the ASCONF
 744                  * containing the add is acknowledged, the sender MUST
 745                  * NOT use the new IP address as a source for ANY SCTP
 746                  * packet except on carrying an ASCONF Chunk.
 747                  */
 748                 if (asoc->src_out_of_asoc_ok &&
 749                     chunk->chunk_hdr->type != SCTP_CID_ASCONF)
 750                         continue;
 751
 752                 list_del_init(&chunk->list);
 753
 754                 /* Pick the right transport to use. */
 755                 new_transport = chunk->transport;
 756
 757                 if (!new_transport) {
 758                         /*
 759                          * If we have a prior transport pointer, see if
 760                          * the destination address of the chunk
 761                          * matches the destination address of the
 762                          * current transport.  If not a match, then
 763                          * try to look up the transport with a given
 764                          * destination address.  We do this because
 765                          * after processing ASCONFs, we may have new
 766                          * transports created.
 767                          */
 768                         if (transport &&
 769                             sctp_cmp_addr_exact(&chunk->dest,
 770                                                 &transport->ipaddr))
 771                                         new_transport = transport;
 772                         else
 773                                 new_transport = sctp_assoc_lookup_paddr(asoc,
 774                                                                 &chunk->dest);
 775
 776                         /* if we still don't have a new transport, then
 777                          * use the current active path.
 778                          */
 779                         if (!new_transport)
 780                                 new_transport = asoc->peer.active_path;
 781                 } else if ((new_transport->state == SCTP_INACTIVE) ||
 782                            (new_transport->state == SCTP_UNCONFIRMED) ||
 783                            (new_transport->state == SCTP_PF)) {
 784                         /* If the chunk is Heartbeat or Heartbeat Ack,
 785                          * send it to chunk->transport, even if it's
 786                          * inactive.
 787                          *
 788                          * 3.3.6 Heartbeat Acknowledgement:
 789                          * ...
 790                          * A HEARTBEAT ACK is always sent to the source IP
 791                          * address of the IP datagram containing the
 792                          * HEARTBEAT chunk to which this ack is responding.
 793                          * ...
 794                          *
 795                          * ASCONF_ACKs also must be sent to the source.
 796                          */
 797                         if (chunk->chunk_hdr->type != SCTP_CID_HEARTBEAT &&
 798                             chunk->chunk_hdr->type != SCTP_CID_HEARTBEAT_ACK &&
 799                             chunk->chunk_hdr->type != SCTP_CID_ASCONF_ACK)
 800                                 new_transport = asoc->peer.active_path;
 801                 }
 802
 803                 /* Are we switching transports?
 804                  * Take care of transport locks.
 805                  */
 806                 if (new_transport != transport) {
 807                         transport = new_transport;
 808                         if (list_empty(&transport->send_ready)) {
 809                                 list_add_tail(&transport->send_ready,
 810                                               &transport_list);
 811                         }
 812                         packet = &transport->packet;
 813                         sctp_packet_config(packet, vtag,
 814                                            asoc->peer.ecn_capable);
 815                 }
 816
 817                 switch (chunk->chunk_hdr->type) {
 818                 /*
 819                  * 6.10 Bundling
 820                  *   ...
 821                  *   An endpoint MUST NOT bundle INIT, INIT ACK or SHUTDOWN
 822                  *   COMPLETE with any other chunks.  [Send them immediately.]
 823                  */
 824                 case SCTP_CID_INIT:
 825                 case SCTP_CID_INIT_ACK:
 826                 case SCTP_CID_SHUTDOWN_COMPLETE:
 827                         sctp_packet_init(&singleton, transport, sport, dport);
 828                         sctp_packet_config(&singleton, vtag, 0);
 829                         sctp_packet_append_chunk(&singleton, chunk);
 830                         error = sctp_packet_transmit(&singleton);
 831                         if (error < 0)
 832                                 return error;
 833                         break;
 834
 835                 case SCTP_CID_ABORT:
 836                         if (sctp_test_T_bit(chunk)) {
 837                                 packet->vtag = asoc->c.my_vtag;
 838                         }
 839                 /* The following chunks are "response" chunks, i.e.
 840                  * they are generated in response to something we
 841                  * received.  If we are sending these, then we can
 842                  * send only 1 packet containing these chunks.
 843                  */
 844                 case SCTP_CID_HEARTBEAT_ACK:
 845                 case SCTP_CID_SHUTDOWN_ACK:
 846                 case SCTP_CID_COOKIE_ACK:
 847                 case SCTP_CID_COOKIE_ECHO:
 848                 case SCTP_CID_ERROR:
 849                 case SCTP_CID_ECN_CWR:
 850                 case SCTP_CID_ASCONF_ACK:
 851                         one_packet = 1;
 852                         /* Fall through */
 853
 854                 case SCTP_CID_SACK:
 855                 case SCTP_CID_HEARTBEAT:
 856                 case SCTP_CID_SHUTDOWN:
 857                 case SCTP_CID_ECN_ECNE:
 858                 case SCTP_CID_ASCONF:
 859                 case SCTP_CID_FWD_TSN:
 860                         status = sctp_packet_transmit_chunk(packet, chunk,
 861                                                             one_packet);
 862                         if (status  != SCTP_XMIT_OK) {
 863                                 /* put the chunk back */
 864                                 list_add(&chunk->list, &q->control_chunk_list);
 865                         } else {
 866                                 asoc->stats.octrlchunks++;
 867                                 /* PR-SCTP C5) If a FORWARD TSN is sent, the
 868                                  * sender MUST assure that at least one T3-rtx
 869                                  * timer is running.
 870                                  */
 871                                 if (chunk->chunk_hdr->type == SCTP_CID_FWD_TSN)
 872                                         sctp_transport_reset_timers(transport);
 873                         }
 874                         break;
 875
 876                 default:
 877                         /* We built a chunk with an illegal type! */
 878                         BUG();
 879                 }
 880         }
 881
 882         if (q->asoc->src_out_of_asoc_ok)
 883                 goto sctp_flush_out;
 884
 885         /* Is it OK to send data chunks?  */
 886         switch (asoc->state) {
 887         case SCTP_STATE_COOKIE_ECHOED:
 888                 /* Only allow bundling when this packet has a COOKIE-ECHO
 889                  * chunk.
 890                  */
 891                 if (!packet || !packet->has_cookie_echo)
 892                         break;
 893
 894                 /* fallthru */
 895         case SCTP_STATE_ESTABLISHED:
 896         case SCTP_STATE_SHUTDOWN_PENDING:
 897         case SCTP_STATE_SHUTDOWN_RECEIVED:
 898                 /*
 899                  * RFC 2960 6.1  Transmission of DATA Chunks
 900                  *
 901                  * C) When the time comes for the sender to transmit,
 902                  * before sending new DATA chunks, the sender MUST
 903                  * first transmit any outstanding DATA chunks which
 904                  * are marked for retransmission (limited by the
 905                  * current cwnd).
 906                  */
 907                 if (!list_empty(&q->retransmit)) {
 908                         if (asoc->peer.retran_path->state == SCTP_UNCONFIRMED)
 909                                 goto sctp_flush_out;
 910                         if (transport == asoc->peer.retran_path)
 911                                 goto retran;
 912
 913                         /* Switch transports & prepare the packet.  */
 914
 915                         transport = asoc->peer.retran_path;
 916
 917                         if (list_empty(&transport->send_ready)) {
 918                                 list_add_tail(&transport->send_ready,
 919                                               &transport_list);
 920                         }
 921
 922                         packet = &transport->packet;
 923                         sctp_packet_config(packet, vtag,
 924                                            asoc->peer.ecn_capable);
 925                 retran:
 926                         error = sctp_outq_flush_rtx(q, packet,
 927                                                     rtx_timeout, &start_timer);
 928
 929                         if (start_timer)
 930                                 sctp_transport_reset_timers(transport);
 931
 932                         /* This can happen on COOKIE-ECHO resend.  Only
 933                          * one chunk can get bundled with a COOKIE-ECHO.
 934                          */
 935                         if (packet->has_cookie_echo)
 936                                 goto sctp_flush_out;
 937
 938                         /* Don't send new data if there is still data
 939                          * waiting to retransmit.
 940                          */
 941                         if (!list_empty(&q->retransmit))
 942                                 goto sctp_flush_out;
 943                 }
 944
 945                 /* Apply Max.Burst limitation to the current transport in
 946                  * case it will be used for new data.  We are going to
 947                  * rest it before we return, but we want to apply the limit
 948                  * to the currently queued data.
 949                  */
 950                 if (transport)
 951                         sctp_transport_burst_limited(transport);
 952
 953                 /* Finally, transmit new packets.  */
 954                 while ((chunk = sctp_outq_dequeue_data(q)) != NULL) {
 955                         /* RFC 2960 6.5 Every DATA chunk MUST carry a valid
 956                          * stream identifier.
 957                          */
 958                         if (chunk->sinfo.sinfo_stream >=
 959                             asoc->c.sinit_num_ostreams) {
 960
 961                                 /* Mark as failed send. */
 962                                 sctp_chunk_fail(chunk, SCTP_ERROR_INV_STRM);
 963                                 sctp_chunk_free(chunk);
 964                                 continue;
 965                         }
 966
 967                         /* Has this chunk expired? */
 968                         if (sctp_chunk_abandoned(chunk)) {
 969                                 sctp_chunk_fail(chunk, 0);
 970                                 sctp_chunk_free(chunk);
 971                                 continue;
 972                         }
 973
 974                         /* If there is a specified transport, use it.
 975                          * Otherwise, we want to use the active path.
 976                          */
 977                         new_transport = chunk->transport;
 978                         if (!new_transport ||
 979                             ((new_transport->state == SCTP_INACTIVE) ||
 980                              (new_transport->state == SCTP_UNCONFIRMED) ||
 981                              (new_transport->state == SCTP_PF)))
 982                                 new_transport = asoc->peer.active_path;
 983                         if (new_transport->state == SCTP_UNCONFIRMED)
 984                                 continue;
 985
 986                         /* Change packets if necessary.  */
 987                         if (new_transport != transport) {
 988                                 transport = new_transport;
 989
 990                                 /* Schedule to have this transport's
 991                                  * packet flushed.
 992                                  */
 993                                 if (list_empty(&transport->send_ready)) {
 994                                         list_add_tail(&transport->send_ready,
 995                                                       &transport_list);
 996                                 }
 997
 998                                 packet = &transport->packet;
 999                                 sctp_packet_config(packet, vtag,
1000                                                    asoc->peer.ecn_capable);
1001                                 /* We've switched transports, so apply the
1002                                  * Burst limit to the new transport.
1003                                  */
1004                                 sctp_transport_burst_limited(transport);
1005                         }
1006
1007                         pr_debug("%s: outq:%p, chunk:%p[%s], tx-tsn:0x%x skb->head:%p "
1008                                  "skb->users:%d\n",
1009                                  __func__, q, chunk, chunk && chunk->chunk_hdr ?
1010                                  sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)) :
1011                                  "illegal chunk", ntohl(chunk->subh.data_hdr->tsn),
1012                                  chunk->skb ? chunk->skb->head : NULL, chunk->skb ?
1013                                  atomic_read(&chunk->skb->users) : -1);
1014
1015                         /* Add the chunk to the packet.  */
1016                         status = sctp_packet_transmit_chunk(packet, chunk, 0);
1017
1018                         switch (status) {
1019                         case SCTP_XMIT_PMTU_FULL:
1020                         case SCTP_XMIT_RWND_FULL:
1021                         case SCTP_XMIT_NAGLE_DELAY:
1022                                 /* We could not append this chunk, so put
1023                                  * the chunk back on the output queue.
1024                                  */
1025                                 pr_debug("%s: could not transmit tsn:0x%x, status:%d\n",
1026                                          __func__, ntohl(chunk->subh.data_hdr->tsn),
1027                                          status);
1028
1029                                 sctp_outq_head_data(q, chunk);
1030                                 goto sctp_flush_out;
1031                                 break;
1032
1033                         case SCTP_XMIT_OK:
1034                                 /* The sender is in the SHUTDOWN-PENDING state,
1035                                  * The sender MAY set the I-bit in the DATA
1036                                  * chunk header.
1037                                  */
1038                                 if (asoc->state == SCTP_STATE_SHUTDOWN_PENDING)
1039                                         chunk->chunk_hdr->flags |= SCTP_DATA_SACK_IMM;
1040                                 if (chunk->chunk_hdr->flags & SCTP_DATA_UNORDERED)
1041                                         asoc->stats.ouodchunks++;
1042                                 else
1043                                         asoc->stats.oodchunks++;
1044
1045                                 break;
1046
1047                         default:
1048                                 BUG();
1049                         }
1050
1051                         /* BUG: We assume that the sctp_packet_transmit()
1052                          * call below will succeed all the time and add the
1053                          * chunk to the transmitted list and restart the
1054                          * timers.
1055                          * It is possible that the call can fail under OOM
1056                          * conditions.
1057                          *
1058                          * Is this really a problem?  Won't this behave
1059                          * like a lost TSN?
1060                          */
1061                         list_add_tail(&chunk->transmitted_list,
1062                                       &transport->transmitted);
1063
1064                         sctp_transport_reset_timers(transport);
1065
1066                         q->empty = 0;
1067
1068                         /* Only let one DATA chunk get bundled with a
1069                          * COOKIE-ECHO chunk.
1070                          */
1071                         if (packet->has_cookie_echo)
1072                                 goto sctp_flush_out;
1073                 }
1074                 break;
1075
1076         default:
1077                 /* Do nothing.  */
1078                 break;
1079         }
1080
1081 sctp_flush_out:
1082
1083         /* Before returning, examine all the transports touched in
1084          * this call.  Right now, we bluntly force clear all the
1085          * transports.  Things might change after we implement Nagle.
1086          * But such an examination is still required.
1087          *
1088          * --xguo
1089          */
1090         while ((ltransport = sctp_list_dequeue(&transport_list)) != NULL ) {
1091                 struct sctp_transport *t = list_entry(ltransport,
1092                                                       struct sctp_transport,
1093                                                       send_ready);
1094                 packet = &t->packet;
1095                 if (!sctp_packet_empty(packet))
1096                         error = sctp_packet_transmit(packet);
1097
1098                 /* Clear the burst limited state, if any */
1099                 sctp_transport_burst_reset(t);
1100         }
1101
1102         return error;
1103 }
1104
1105 /* Update unack_data based on the incoming SACK chunk */
1106 static void sctp_sack_update_unack_data(struct sctp_association *assoc,
1107                                         struct sctp_sackhdr *sack)
1108 {
1109         sctp_sack_variable_t *frags;
1110         __u16 unack_data;
1111         int i;
1112
1113         unack_data = assoc->next_tsn - assoc->ctsn_ack_point - 1;
1114
1115         frags = sack->variable;
1116         for (i = 0; i < ntohs(sack->num_gap_ack_blocks); i++) {
1117                 unack_data -= ((ntohs(frags[i].gab.end) -
1118                                 ntohs(frags[i].gab.start) + 1));
1119         }
1120
1121         assoc->unack_data = unack_data;
1122 }
1123
1124 /* This is where we REALLY process a SACK.
1125  *
1126  * Process the SACK against the outqueue.  Mostly, this just frees
1127  * things off the transmitted queue.
1128  */
1129 int sctp_outq_sack(struct sctp_outq *q, struct sctp_chunk *chunk)
1130 {
1131         struct sctp_association *asoc = q->asoc;
1132         struct sctp_sackhdr *sack = chunk->subh.sack_hdr;
1133         struct sctp_transport *transport;
1134         struct sctp_chunk *tchunk = NULL;
1135         struct list_head *lchunk, *transport_list, *temp;
1136         sctp_sack_variable_t *frags = sack->variable;
1137         __u32 sack_ctsn, ctsn, tsn;
1138         __u32 highest_tsn, highest_new_tsn;
1139         __u32 sack_a_rwnd;
1140         unsigned int outstanding;
1141         struct sctp_transport *primary = asoc->peer.primary_path;
1142         int count_of_newacks = 0;
1143         int gap_ack_blocks;
1144         u8 accum_moved = 0;
1145
1146         /* Grab the association's destination address list. */
1147         transport_list = &asoc->peer.transport_addr_list;
1148
1149         sack_ctsn = ntohl(sack->cum_tsn_ack);
1150         gap_ack_blocks = ntohs(sack->num_gap_ack_blocks);
1151         asoc->stats.gapcnt += gap_ack_blocks;
1152         /*
1153          * SFR-CACC algorithm:
1154          * On receipt of a SACK the sender SHOULD execute the
1155          * following statements.
1156          *
1157          * 1) If the cumulative ack in the SACK passes next tsn_at_change
1158          * on the current primary, the CHANGEOVER_ACTIVE flag SHOULD be
1159          * cleared. The CYCLING_CHANGEOVER flag SHOULD also be cleared for
1160          * all destinations.
1161          * 2) If the SACK contains gap acks and the flag CHANGEOVER_ACTIVE
1162          * is set the receiver of the SACK MUST take the following actions:
1163          *
1164          * A) Initialize the cacc_saw_newack to 0 for all destination
1165          * addresses.
1166          *
1167          * Only bother if changeover_active is set. Otherwise, this is
1168          * totally suboptimal to do on every SACK.
1169          */
1170         if (primary->cacc.changeover_active) {
1171                 u8 clear_cycling = 0;
1172
1173                 if (TSN_lte(primary->cacc.next_tsn_at_change, sack_ctsn)) {
1174                         primary->cacc.changeover_active = 0;
1175                         clear_cycling = 1;
1176                 }
1177
1178                 if (clear_cycling || gap_ack_blocks) {
1179                         list_for_each_entry(transport, transport_list,
1180                                         transports) {
1181                                 if (clear_cycling)
1182                                         transport->cacc.cycling_changeover = 0;
1183                                 if (gap_ack_blocks)
1184                                         transport->cacc.cacc_saw_newack = 0;
1185                         }
1186                 }
1187         }
1188
1189         /* Get the highest TSN in the sack. */
1190         highest_tsn = sack_ctsn;
1191         if (gap_ack_blocks)
1192                 highest_tsn += ntohs(frags[gap_ack_blocks - 1].gab.end);
1193
1194         if (TSN_lt(asoc->highest_sacked, highest_tsn))
1195                 asoc->highest_sacked = highest_tsn;
1196
1197         highest_new_tsn = sack_ctsn;
1198
1199         /* Run through the retransmit queue.  Credit bytes received
1200          * and free those chunks that we can.
1201          */
1202         sctp_check_transmitted(q, &q->retransmit, NULL, NULL, sack, &highest_new_tsn);
1203
1204         /* Run through the transmitted queue.
1205          * Credit bytes received and free those chunks which we can.
1206          *
1207          * This is a MASSIVE candidate for optimization.
1208          */
1209         list_for_each_entry(transport, transport_list, transports) {
1210                 sctp_check_transmitted(q, &transport->transmitted,
1211                                        transport, &chunk->source, sack,
1212                                        &highest_new_tsn);
1213                 /*
1214                  * SFR-CACC algorithm:
1215                  * C) Let count_of_newacks be the number of
1216                  * destinations for which cacc_saw_newack is set.
1217                  */
1218                 if (transport->cacc.cacc_saw_newack)
1219                         count_of_newacks ++;
1220         }
1221
1222         /* Move the Cumulative TSN Ack Point if appropriate.  */
1223         if (TSN_lt(asoc->ctsn_ack_point, sack_ctsn)) {
1224                 asoc->ctsn_ack_point = sack_ctsn;
1225                 accum_moved = 1;
1226         }
1227
1228         if (gap_ack_blocks) {
1229
1230                 if (asoc->fast_recovery && accum_moved)
1231                         highest_new_tsn = highest_tsn;
1232
1233                 list_for_each_entry(transport, transport_list, transports)
1234                         sctp_mark_missing(q, &transport->transmitted, transport,
1235                                           highest_new_tsn, count_of_newacks);
1236         }
1237
1238         /* Update unack_data field in the assoc. */
1239         sctp_sack_update_unack_data(asoc, sack);
1240
1241         ctsn = asoc->ctsn_ack_point;
1242
1243         /* Throw away stuff rotting on the sack queue.  */
1244         list_for_each_safe(lchunk, temp, &q->sacked) {
1245                 tchunk = list_entry(lchunk, struct sctp_chunk,
1246                                     transmitted_list);
1247                 tsn = ntohl(tchunk->subh.data_hdr->tsn);
1248                 if (TSN_lte(tsn, ctsn)) {
1249                         list_del_init(&tchunk->transmitted_list);
1250                         sctp_chunk_free(tchunk);
1251                 }
1252         }
1253
1254         /* ii) Set rwnd equal to the newly received a_rwnd minus the
1255          *     number of bytes still outstanding after processing the
1256          *     Cumulative TSN Ack and the Gap Ack Blocks.
1257          */
1258
1259         sack_a_rwnd = ntohl(sack->a_rwnd);
1260         outstanding = q->outstanding_bytes;
1261
1262         if (outstanding < sack_a_rwnd)
1263                 sack_a_rwnd -= outstanding;
1264         else
1265                 sack_a_rwnd = 0;
1266
1267         asoc->peer.rwnd = sack_a_rwnd;
1268
1269         sctp_generate_fwdtsn(q, sack_ctsn);
1270
1271         pr_debug("%s: sack cumulative tsn ack:0x%x\n", __func__, sack_ctsn);
1272         pr_debug("%s: cumulative tsn ack of assoc:%p is 0x%x, "
1273                  "advertised peer ack point:0x%x\n", __func__, asoc, ctsn,
1274                  asoc->adv_peer_ack_point);
1275
1276         /* See if all chunks are acked.
1277          * Make sure the empty queue handler will get run later.
1278          */
1279         q->empty = (list_empty(&q->out_chunk_list) &&
1280                     list_empty(&q->retransmit));
1281         if (!q->empty)
1282                 goto finish;
1283
1284         list_for_each_entry(transport, transport_list, transports) {
1285                 q->empty = q->empty && list_empty(&transport->transmitted);
1286                 if (!q->empty)
1287                         goto finish;
1288         }
1289
1290         pr_debug("%s: sack queue is empty\n", __func__);
1291 finish:
1292         return q->empty;
1293 }
1294
1295 /* Is the outqueue empty?  */
1296 int sctp_outq_is_empty(const struct sctp_outq *q)
1297 {
1298         return q->empty;
1299 }
1300
1301 /********************************************************************
1302  * 2nd Level Abstractions
1303  ********************************************************************/
1304
1305 /* Go through a transport's transmitted list or the association's retransmit
1306  * list and move chunks that are acked by the Cumulative TSN Ack to q->sacked.
1307  * The retransmit list will not have an associated transport.
1308  *
1309  * I added coherent debug information output.   --xguo
1310  *
1311  * Instead of printing 'sacked' or 'kept' for each TSN on the
1312  * transmitted_queue, we print a range: SACKED: TSN1-TSN2, TSN3, TSN4-TSN5.
1313  * KEPT TSN6-TSN7, etc.
1314  */
1315 static void sctp_check_transmitted(struct sctp_outq *q,
1316                                    struct list_head *transmitted_queue,
1317                                    struct sctp_transport *transport,
1318                                    union sctp_addr *saddr,
1319                                    struct sctp_sackhdr *sack,
1320                                    __u32 *highest_new_tsn_in_sack)
1321 {
1322         struct list_head *lchunk;
1323         struct sctp_chunk *tchunk;
1324         struct list_head tlist;
1325         __u32 tsn;
1326         __u32 sack_ctsn;
1327         __u32 rtt;
1328         __u8 restart_timer = 0;
1329         int bytes_acked = 0;
1330         int migrate_bytes = 0;
1331         bool forward_progress = false;
1332
1333         sack_ctsn = ntohl(sack->cum_tsn_ack);
1334
1335         INIT_LIST_HEAD(&tlist);
1336
1337         /* The while loop will skip empty transmitted queues. */
1338         while (NULL != (lchunk = sctp_list_dequeue(transmitted_queue))) {
1339                 tchunk = list_entry(lchunk, struct sctp_chunk,
1340                                     transmitted_list);
1341
1342                 if (sctp_chunk_abandoned(tchunk)) {
1343                         /* Move the chunk to abandoned list. */
1344                         sctp_insert_list(&q->abandoned, lchunk);
1345
1346                         /* If this chunk has not been acked, stop
1347                          * considering it as 'outstanding'.
1348                          */
1349                         if (!tchunk->tsn_gap_acked) {
1350                                 if (tchunk->transport)
1351                                         tchunk->transport->flight_size -=
1352                                                         sctp_data_size(tchunk);
1353                                 q->outstanding_bytes -= sctp_data_size(tchunk);
1354                         }
1355                         continue;
1356                 }
1357
1358                 tsn = ntohl(tchunk->subh.data_hdr->tsn);
1359                 if (sctp_acked(sack, tsn)) {
1360                         /* If this queue is the retransmit queue, the
1361                          * retransmit timer has already reclaimed
1362                          * the outstanding bytes for this chunk, so only
1363                          * count bytes associated with a transport.
1364                          */
1365                         if (transport) {
1366                                 /* If this chunk is being used for RTT
1367                                  * measurement, calculate the RTT and update
1368                                  * the RTO using this value.
1369                                  *
1370                                  * 6.3.1 C5) Karn's algorithm: RTT measurements
1371                                  * MUST NOT be made using packets that were
1372                                  * retransmitted (and thus for which it is
1373                                  * ambiguous whether the reply was for the
1374                                  * first instance of the packet or a later
1375                                  * instance).
1376                                  */
1377                                 if (!tchunk->tsn_gap_acked &&
1378                                     tchunk->rtt_in_progress) {
1379                                         tchunk->rtt_in_progress = 0;
1380                                         rtt = jiffies - tchunk->sent_at;
1381                                         sctp_transport_update_rto(transport,
1382                                                                   rtt);
1383                                 }
1384                         }
1385
1386                         /* If the chunk hasn't been marked as ACKED,
1387                          * mark it and account bytes_acked if the
1388                          * chunk had a valid transport (it will not
1389                          * have a transport if ASCONF had deleted it
1390                          * while DATA was outstanding).
1391                          */
1392                         if (!tchunk->tsn_gap_acked) {
1393                                 tchunk->tsn_gap_acked = 1;
1394                                 *highest_new_tsn_in_sack = tsn;
1395                                 bytes_acked += sctp_data_size(tchunk);
1396                                 if (!tchunk->transport)
1397                                         migrate_bytes += sctp_data_size(tchunk);
1398                                 forward_progress = true;
1399                         }
1400
1401                         if (TSN_lte(tsn, sack_ctsn)) {
1402                                 /* RFC 2960  6.3.2 Retransmission Timer Rules
1403                                  *
1404                                  * R3) Whenever a SACK is received
1405                                  * that acknowledges the DATA chunk
1406                                  * with the earliest outstanding TSN
1407                                  * for that address, restart T3-rtx
1408                                  * timer for that address with its
1409                                  * current RTO.
1410                                  */
1411                                 restart_timer = 1;
1412                                 forward_progress = true;
1413
1414                                 if (!tchunk->tsn_gap_acked) {
1415                                         /*
1416                                          * SFR-CACC algorithm:
1417                                          * 2) If the SACK contains gap acks
1418                                          * and the flag CHANGEOVER_ACTIVE is
1419                                          * set the receiver of the SACK MUST
1420                                          * take the following action:
1421                                          *
1422                                          * B) For each TSN t being acked that
1423                                          * has not been acked in any SACK so
1424                                          * far, set cacc_saw_newack to 1 for
1425                                          * the destination that the TSN was
1426                                          * sent to.
1427                                          */
1428                                         if (transport &&
1429                                             sack->num_gap_ack_blocks &&
1430                                             q->asoc->peer.primary_path->cacc.
1431                                             changeover_active)
1432                                                 transport->cacc.cacc_saw_newack
1433                                                         = 1;
1434                                 }
1435
1436                                 list_add_tail(&tchunk->transmitted_list,
1437                                               &q->sacked);
1438                         } else {
1439                                 /* RFC2960 7.2.4, sctpimpguide-05 2.8.2
1440                                  * M2) Each time a SACK arrives reporting
1441                                  * 'Stray DATA chunk(s)' record the highest TSN
1442                                  * reported as newly acknowledged, call this
1443                                  * value 'HighestTSNinSack'. A newly
1444                                  * acknowledged DATA chunk is one not
1445                                  * previously acknowledged in a SACK.
1446                                  *
1447                                  * When the SCTP sender of data receives a SACK
1448                                  * chunk that acknowledges, for the first time,
1449                                  * the receipt of a DATA chunk, all the still
1450                                  * unacknowledged DATA chunks whose TSN is
1451                                  * older than that newly acknowledged DATA
1452                                  * chunk, are qualified as 'Stray DATA chunks'.
1453                                  */
1454                                 list_add_tail(lchunk, &tlist);
1455                         }
1456                 } else {
1457                         if (tchunk->tsn_gap_acked) {
1458                                 pr_debug("%s: receiver reneged on data TSN:0x%x\n",
1459                                          __func__, tsn);
1460
1461                                 tchunk->tsn_gap_acked = 0;
1462
1463                                 if (tchunk->transport)
1464                                         bytes_acked -= sctp_data_size(tchunk);
1465
1466                                 /* RFC 2960 6.3.2 Retransmission Timer Rules
1467                                  *
1468                                  * R4) Whenever a SACK is received missing a
1469                                  * TSN that was previously acknowledged via a
1470                                  * Gap Ack Block, start T3-rtx for the
1471                                  * destination address to which the DATA
1472                                  * chunk was originally
1473                                  * transmitted if it is not already running.
1474                                  */
1475                                 restart_timer = 1;
1476                         }
1477
1478                         list_add_tail(lchunk, &tlist);
1479                 }
1480         }
1481
1482         if (transport) {
1483                 if (bytes_acked) {
1484                         struct sctp_association *asoc = transport->asoc;
1485
1486                         /* We may have counted DATA that was migrated
1487                          * to this transport due to DEL-IP operation.
1488                          * Subtract those bytes, since the were never
1489                          * send on this transport and shouldn't be
1490                          * credited to this transport.
1491                          */
1492                         bytes_acked -= migrate_bytes;
1493
1494                         /* 8.2. When an outstanding TSN is acknowledged,
1495                          * the endpoint shall clear the error counter of
1496                          * the destination transport address to which the
1497                          * DATA chunk was last sent.
1498                          * The association's overall error counter is
1499                          * also cleared.
1500                          */
1501                         transport->error_count = 0;
1502                         transport->asoc->overall_error_count = 0;
1503                         forward_progress = true;
1504
1505                         /*
1506                          * While in SHUTDOWN PENDING, we may have started
1507                          * the T5 shutdown guard timer after reaching the
1508                          * retransmission limit. Stop that timer as soon
1509                          * as the receiver acknowledged any data.
1510                          */
1511                         if (asoc->state == SCTP_STATE_SHUTDOWN_PENDING &&
1512                             del_timer(&asoc->timers
1513                                 [SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD]))
1514                                         sctp_association_put(asoc);
1515
1516                         /* Mark the destination transport address as
1517                          * active if it is not so marked.
1518                          */
1519                         if ((transport->state == SCTP_INACTIVE ||
1520                              transport->state == SCTP_UNCONFIRMED) &&
1521                             sctp_cmp_addr_exact(&transport->ipaddr, saddr)) {
1522                                 sctp_assoc_control_transport(
1523                                         transport->asoc,
1524                                         transport,
1525                                         SCTP_TRANSPORT_UP,
1526                                         SCTP_RECEIVED_SACK);
1527                         }
1528
1529                         sctp_transport_raise_cwnd(transport, sack_ctsn,
1530                                                   bytes_acked);
1531
1532                         transport->flight_size -= bytes_acked;
1533                         if (transport->flight_size == 0)
1534                                 transport->partial_bytes_acked = 0;
1535                         q->outstanding_bytes -= bytes_acked + migrate_bytes;
1536                 } else {
1537                         /* RFC 2960 6.1, sctpimpguide-06 2.15.2
1538                          * When a sender is doing zero window probing, it
1539                          * should not timeout the association if it continues
1540                          * to receive new packets from the receiver. The
1541                          * reason is that the receiver MAY keep its window
1542                          * closed for an indefinite time.
1543                          * A sender is doing zero window probing when the
1544                          * receiver's advertised window is zero, and there is
1545                          * only one data chunk in flight to the receiver.
1546                          *
1547                          * Allow the association to timeout while in SHUTDOWN
1548                          * PENDING or SHUTDOWN RECEIVED in case the receiver
1549                          * stays in zero window mode forever.
1550                          */
1551                         if (!q->asoc->peer.rwnd &&
1552                             !list_empty(&tlist) &&
1553                             (sack_ctsn+2 == q->asoc->next_tsn) &&
1554                             q->asoc->state < SCTP_STATE_SHUTDOWN_PENDING) {
1555                                 pr_debug("%s: sack received for zero window "
1556                                          "probe:%u\n", __func__, sack_ctsn);
1557
1558                                 q->asoc->overall_error_count = 0;
1559                                 transport->error_count = 0;
1560                         }
1561                 }
1562
1563                 /* RFC 2960 6.3.2 Retransmission Timer Rules
1564                  *
1565                  * R2) Whenever all outstanding data sent to an address have
1566                  * been acknowledged, turn off the T3-rtx timer of that
1567                  * address.
1568                  */
1569                 if (!transport->flight_size) {
1570                         if (del_timer(&transport->T3_rtx_timer))
1571                                 sctp_transport_put(transport);
1572                 } else if (restart_timer) {
1573                         if (!mod_timer(&transport->T3_rtx_timer,
1574                                        jiffies + transport->rto))
1575                                 sctp_transport_hold(transport);
1576                 }
1577
1578                 if (forward_progress) {
1579                         if (transport->dst)
1580                                 dst_confirm(transport->dst);
1581                 }
1582         }
1583
1584         list_splice(&tlist, transmitted_queue);
1585 }
1586
1587 /* Mark chunks as missing and consequently may get retransmitted. */
1588 static void sctp_mark_missing(struct sctp_outq *q,
1589                               struct list_head *transmitted_queue,
1590                               struct sctp_transport *transport,
1591                               __u32 highest_new_tsn_in_sack,
1592                               int count_of_newacks)
1593 {
1594         struct sctp_chunk *chunk;
1595         __u32 tsn;
1596         char do_fast_retransmit = 0;
1597         struct sctp_association *asoc = q->asoc;
1598         struct sctp_transport *primary = asoc->peer.primary_path;
1599
1600         list_for_each_entry(chunk, transmitted_queue, transmitted_list) {
1601
1602                 tsn = ntohl(chunk->subh.data_hdr->tsn);
1603
1604                 /* RFC 2960 7.2.4, sctpimpguide-05 2.8.2 M3) Examine all
1605                  * 'Unacknowledged TSN's', if the TSN number of an
1606                  * 'Unacknowledged TSN' is smaller than the 'HighestTSNinSack'
1607                  * value, increment the 'TSN.Missing.Report' count on that
1608                  * chunk if it has NOT been fast retransmitted or marked for
1609                  * fast retransmit already.
1610                  */
1611                 if (chunk->fast_retransmit == SCTP_CAN_FRTX &&
1612                     !chunk->tsn_gap_acked &&
1613                     TSN_lt(tsn, highest_new_tsn_in_sack)) {
1614
1615                         /* SFR-CACC may require us to skip marking
1616                          * this chunk as missing.
1617                          */
1618                         if (!transport || !sctp_cacc_skip(primary,
1619                                                 chunk->transport,
1620                                                 count_of_newacks, tsn)) {
1621                                 chunk->tsn_missing_report++;
1622
1623                                 pr_debug("%s: tsn:0x%x missing counter:%d\n",
1624                                          __func__, tsn, chunk->tsn_missing_report);
1625                         }
1626                 }
1627                 /*
1628                  * M4) If any DATA chunk is found to have a
1629                  * 'TSN.Missing.Report'
1630                  * value larger than or equal to 3, mark that chunk for
1631                  * retransmission and start the fast retransmit procedure.
1632                  */
1633
1634                 if (chunk->tsn_missing_report >= 3) {
1635                         chunk->fast_retransmit = SCTP_NEED_FRTX;
1636                         do_fast_retransmit = 1;
1637                 }
1638         }
1639
1640         if (transport) {
1641                 if (do_fast_retransmit)
1642                         sctp_retransmit(q, transport, SCTP_RTXR_FAST_RTX);
1643
1644                 pr_debug("%s: transport:%p, cwnd:%d, ssthresh:%d, "
1645                          "flight_size:%d, pba:%d\n",  __func__, transport,
1646                          transport->cwnd, transport->ssthresh,
1647                          transport->flight_size, transport->partial_bytes_acked);
1648         }
1649 }
1650
1651 /* Is the given TSN acked by this packet?  */
1652 static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn)
1653 {
1654         int i;
1655         sctp_sack_variable_t *frags;
1656         __u16 gap;
1657         __u32 ctsn = ntohl(sack->cum_tsn_ack);
1658
1659         if (TSN_lte(tsn, ctsn))
1660                 goto pass;
1661
1662         /* 3.3.4 Selective Acknowledgement (SACK) (3):
1663          *
1664          * Gap Ack Blocks:
1665          *  These fields contain the Gap Ack Blocks. They are repeated
1666          *  for each Gap Ack Block up to the number of Gap Ack Blocks
1667          *  defined in the Number of Gap Ack Blocks field. All DATA
1668          *  chunks with TSNs greater than or equal to (Cumulative TSN
1669          *  Ack + Gap Ack Block Start) and less than or equal to
1670          *  (Cumulative TSN Ack + Gap Ack Block End) of each Gap Ack
1671          *  Block are assumed to have been received correctly.
1672          */
1673
1674         frags = sack->variable;
1675         gap = tsn - ctsn;
1676         for (i = 0; i < ntohs(sack->num_gap_ack_blocks); ++i) {
1677                 if (TSN_lte(ntohs(frags[i].gab.start), gap) &&
1678                     TSN_lte(gap, ntohs(frags[i].gab.end)))
1679                         goto pass;
1680         }
1681
1682         return 0;
1683 pass:
1684         return 1;
1685 }
1686
1687 static inline int sctp_get_skip_pos(struct sctp_fwdtsn_skip *skiplist,
1688                                     int nskips, __be16 stream)
1689 {
1690         int i;
1691
1692         for (i = 0; i < nskips; i++) {
1693                 if (skiplist[i].stream == stream)
1694                         return i;
1695         }
1696         return i;
1697 }
1698
1699 /* Create and add a fwdtsn chunk to the outq's control queue if needed. */
1700 static void sctp_generate_fwdtsn(struct sctp_outq *q, __u32 ctsn)
1701 {
1702         struct sctp_association *asoc = q->asoc;
1703         struct sctp_chunk *ftsn_chunk = NULL;
1704         struct sctp_fwdtsn_skip ftsn_skip_arr[10];
1705         int nskips = 0;
1706         int skip_pos = 0;
1707         __u32 tsn;
1708         struct sctp_chunk *chunk;
1709         struct list_head *lchunk, *temp;
1710
1711         if (!asoc->peer.prsctp_capable)
1712                 return;
1713
1714         /* PR-SCTP C1) Let SackCumAck be the Cumulative TSN ACK carried in the
1715          * received SACK.
1716          *
1717          * If (Advanced.Peer.Ack.Point < SackCumAck), then update
1718          * Advanced.Peer.Ack.Point to be equal to SackCumAck.
1719          */
1720         if (TSN_lt(asoc->adv_peer_ack_point, ctsn))
1721                 asoc->adv_peer_ack_point = ctsn;
1722
1723         /* PR-SCTP C2) Try to further advance the "Advanced.Peer.Ack.Point"
1724          * locally, that is, to move "Advanced.Peer.Ack.Point" up as long as
1725          * the chunk next in the out-queue space is marked as "abandoned" as
1726          * shown in the following example:
1727          *
1728          * Assuming that a SACK arrived with the Cumulative TSN ACK 102
1729          * and the Advanced.Peer.Ack.Point is updated to this value:
1730          *
1731          *   out-queue at the end of  ==>   out-queue after Adv.Ack.Point
1732          *   normal SACK processing           local advancement
1733          *                ...                           ...
1734          *   Adv.Ack.Pt-> 102 acked                     102 acked
1735          *                103 abandoned                 103 abandoned
1736          *                104 abandoned     Adv.Ack.P-> 104 abandoned
1737          *                105                           105
1738          *                106 acked                     106 acked
1739          *                ...                           ...
1740          *
1741          * In this example, the data sender successfully advanced the
1742          * "Advanced.Peer.Ack.Point" from 102 to 104 locally.
1743          */
1744         list_for_each_safe(lchunk, temp, &q->abandoned) {
1745                 chunk = list_entry(lchunk, struct sctp_chunk,
1746                                         transmitted_list);
1747                 tsn = ntohl(chunk->subh.data_hdr->tsn);
1748
1749                 /* Remove any chunks in the abandoned queue that are acked by
1750                  * the ctsn.
1751                  */
1752                 if (TSN_lte(tsn, ctsn)) {
1753                         list_del_init(lchunk);
1754                         sctp_chunk_free(chunk);
1755                 } else {
1756                         if (TSN_lte(tsn, asoc->adv_peer_ack_point+1)) {
1757                                 asoc->adv_peer_ack_point = tsn;
1758                                 if (chunk->chunk_hdr->flags &
1759                                          SCTP_DATA_UNORDERED)
1760                                         continue;
1761                                 skip_pos = sctp_get_skip_pos(&ftsn_skip_arr[0],
1762                                                 nskips,
1763                                                 chunk->subh.data_hdr->stream);
1764                                 ftsn_skip_arr[skip_pos].stream =
1765                                         chunk->subh.data_hdr->stream;
1766                                 ftsn_skip_arr[skip_pos].ssn =
1767                                          chunk->subh.data_hdr->ssn;
1768                                 if (skip_pos == nskips)
1769                                         nskips++;
1770                                 if (nskips == 10)
1771                                         break;
1772                         } else
1773                                 break;
1774                 }
1775         }
1776
1777         /* PR-SCTP C3) If, after step C1 and C2, the "Advanced.Peer.Ack.Point"
1778          * is greater than the Cumulative TSN ACK carried in the received
1779          * SACK, the data sender MUST send the data receiver a FORWARD TSN
1780          * chunk containing the latest value of the
1781          * "Advanced.Peer.Ack.Point".
1782          *
1783          * C4) For each "abandoned" TSN the sender of the FORWARD TSN SHOULD
1784          * list each stream and sequence number in the forwarded TSN. This
1785          * information will enable the receiver to easily find any
1786          * stranded TSN's waiting on stream reorder queues. Each stream
1787          * SHOULD only be reported once; this means that if multiple
1788          * abandoned messages occur in the same stream then only the
1789          * highest abandoned stream sequence number is reported. If the
1790          * total size of the FORWARD TSN does NOT fit in a single MTU then
1791          * the sender of the FORWARD TSN SHOULD lower the
1792          * Advanced.Peer.Ack.Point to the last TSN that will fit in a
1793          * single MTU.
1794          */
1795         if (asoc->adv_peer_ack_point > ctsn)
1796                 ftsn_chunk = sctp_make_fwdtsn(asoc, asoc->adv_peer_ack_point,
1797                                               nskips, &ftsn_skip_arr[0]);
1798
1799         if (ftsn_chunk) {
1800                 list_add_tail(&ftsn_chunk->list, &q->control_chunk_list);
1801                 SCTP_INC_STATS(sock_net(asoc->base.sk), SCTP_MIB_OUTCTRLCHUNKS);
1802         }
1803 }