net/sctp/outqueue.c

   1 /* SCTP kernel reference Implementation
   2  * (C) Copyright IBM Corp. 2001, 2004
   3  * Copyright (c) 1999-2000 Cisco, Inc.
   4  * Copyright (c) 1999-2001 Motorola, Inc.
   5  * Copyright (c) 2001-2003 Intel Corp.
   6  *
   7  * This file is part of the SCTP kernel reference Implementation
   8  *
   9  * These functions implement the sctp_outq class.   The outqueue handles
  10  * bundling and queueing of outgoing SCTP chunks.
  11  *
  12  * The SCTP reference implementation is free software;
  13  * you can redistribute it and/or modify it under the terms of
  14  * the GNU General Public License as published by
  15  * the Free Software Foundation; either version 2, or (at your option)
  16  * any later version.
  17  *
  18  * The SCTP reference implementation is distributed in the hope that it
  19  * will be useful, but WITHOUT ANY WARRANTY; without even the implied
  20  *                 ************************
  21  * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  22  * See the GNU General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU General Public License
  25  * along with GNU CC; see the file COPYING.  If not, write to
  26  * the Free Software Foundation, 59 Temple Place - Suite 330,
  27  * Boston, MA 02111-1307, USA.
  28  *
  29  * Please send any bug reports or fixes you make to the
  30  * email address(es):
  31  *    lksctp developers <lksctp-developers@lists.sourceforge.net>
  32  *
  33  * Or submit a bug report through the following website:
  34  *    http://www.sf.net/projects/lksctp
  35  *
  36  * Written or modified by:
  37  *    La Monte H.P. Yarroll <piggy@acm.org>
  38  *    Karl Knutson          <karl@athena.chicago.il.us>
  39  *    Perry Melange         <pmelange@null.cc.uic.edu>
  40  *    Xingang Guo           <xingang.guo@intel.com>
  41  *    Hui Huang             <hui.huang@nokia.com>
  42  *    Sridhar Samudrala     <sri@us.ibm.com>
  43  *    Jon Grimm             <jgrimm@us.ibm.com>
  44  *
  45  * Any bugs reported given to us we will try to fix... any fixes shared will
  46  * be incorporated into the next SCTP release.
  47  */
  48
  49 #include <linux/types.h>
  50 #include <linux/list.h>   /* For struct list_head */
  51 #include <linux/socket.h>
  52 #include <linux/ip.h>
  53 #include <net/sock.h>     /* For skb_set_owner_w */
  54
  55 #include <net/sctp/sctp.h>
  56 #include <net/sctp/sm.h>
  57
  58 /* Declare internal functions here.  */
  59 static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn);
  60 static void sctp_check_transmitted(struct sctp_outq *q,
  61                                    struct list_head *transmitted_queue,
  62                                    struct sctp_transport *transport,
  63                                    struct sctp_sackhdr *sack,
  64                                    __u32 highest_new_tsn);
  65
  66 static void sctp_mark_missing(struct sctp_outq *q,
  67                               struct list_head *transmitted_queue,
  68                               struct sctp_transport *transport,
  69                               __u32 highest_new_tsn,
  70                               int count_of_newacks);
  71
  72 static void sctp_generate_fwdtsn(struct sctp_outq *q, __u32 sack_ctsn);
  73
  74 /* Add data to the front of the queue. */
  75 static inline void sctp_outq_head_data(struct sctp_outq *q,
  76                                         struct sctp_chunk *ch)
  77 {
  78         __skb_queue_head(&q->out, (struct sk_buff *)ch);
  79         q->out_qlen += ch->skb->len;
  80         return;
  81 }
  82
  83 /* Take data from the front of the queue. */
  84 static inline struct sctp_chunk *sctp_outq_dequeue_data(struct sctp_outq *q)
  85 {
  86         struct sctp_chunk *ch;
  87         ch = (struct sctp_chunk *)__skb_dequeue(&q->out);
  88         if (ch)
  89                 q->out_qlen -= ch->skb->len;
  90         return ch;
  91 }
  92 /* Add data chunk to the end of the queue. */
  93 static inline void sctp_outq_tail_data(struct sctp_outq *q,
  94                                        struct sctp_chunk *ch)
  95 {
  96         __skb_queue_tail(&q->out, (struct sk_buff *)ch);
  97         q->out_qlen += ch->skb->len;
  98         return;
  99 }
 100
 101 /*
 102  * SFR-CACC algorithm:
 103  * D) If count_of_newacks is greater than or equal to 2
 104  * and t was not sent to the current primary then the
 105  * sender MUST NOT increment missing report count for t.
 106  */
 107 static inline int sctp_cacc_skip_3_1_d(struct sctp_transport *primary,
 108                                        struct sctp_transport *transport,
 109                                        int count_of_newacks)
 110 {
 111         if (count_of_newacks >=2 && transport != primary)
 112                 return 1;
 113         return 0;
 114 }
 115
 116 /*
 117  * SFR-CACC algorithm:
 118  * F) If count_of_newacks is less than 2, let d be the
 119  * destination to which t was sent. If cacc_saw_newack
 120  * is 0 for destination d, then the sender MUST NOT
 121  * increment missing report count for t.
 122  */
 123 static inline int sctp_cacc_skip_3_1_f(struct sctp_transport *transport,
 124                                        int count_of_newacks)
 125 {
 126         if (count_of_newacks < 2 && !transport->cacc.cacc_saw_newack)
 127                 return 1;
 128         return 0;
 129 }
 130
 131 /*
 132  * SFR-CACC algorithm:
 133  * 3.1) If CYCLING_CHANGEOVER is 0, the sender SHOULD
 134  * execute steps C, D, F.
 135  *
 136  * C has been implemented in sctp_outq_sack
 137  */
 138 static inline int sctp_cacc_skip_3_1(struct sctp_transport *primary,
 139                                      struct sctp_transport *transport,
 140                                      int count_of_newacks)
 141 {
 142         if (!primary->cacc.cycling_changeover) {
 143                 if (sctp_cacc_skip_3_1_d(primary, transport, count_of_newacks))
 144                         return 1;
 145                 if (sctp_cacc_skip_3_1_f(transport, count_of_newacks))
 146                         return 1;
 147                 return 0;
 148         }
 149         return 0;
 150 }
 151
 152 /*
 153  * SFR-CACC algorithm:
 154  * 3.2) Else if CYCLING_CHANGEOVER is 1, and t is less
 155  * than next_tsn_at_change of the current primary, then
 156  * the sender MUST NOT increment missing report count
 157  * for t.
 158  */
 159 static inline int sctp_cacc_skip_3_2(struct sctp_transport *primary, __u32 tsn)
 160 {
 161         if (primary->cacc.cycling_changeover &&
 162             TSN_lt(tsn, primary->cacc.next_tsn_at_change))
 163                 return 1;
 164         return 0;
 165 }
 166
 167 /*
 168  * SFR-CACC algorithm:
 169  * 3) If the missing report count for TSN t is to be
 170  * incremented according to [RFC2960] and
 171  * [SCTP_STEWART-2002], and CHANGEOVER_ACTIVE is set,
 172  * then the sender MUST futher execute steps 3.1 and
 173  * 3.2 to determine if the missing report count for
 174  * TSN t SHOULD NOT be incremented.
 175  *
 176  * 3.3) If 3.1 and 3.2 do not dictate that the missing
 177  * report count for t should not be incremented, then
 178  * the sender SOULD increment missing report count for
 179  * t (according to [RFC2960] and [SCTP_STEWART_2002]).
 180  */
 181 static inline int sctp_cacc_skip(struct sctp_transport *primary,
 182                                  struct sctp_transport *transport,
 183                                  int count_of_newacks,
 184                                  __u32 tsn)
 185 {
 186         if (primary->cacc.changeover_active &&
 187             (sctp_cacc_skip_3_1(primary, transport, count_of_newacks)
 188              || sctp_cacc_skip_3_2(primary, tsn)))
 189                 return 1;
 190         return 0;
 191 }
 192
 193 /* Generate a new outqueue.  */
 194 struct sctp_outq *sctp_outq_new(struct sctp_association *asoc)
 195 {
 196         struct sctp_outq *q;
 197
 198         q = t_new(struct sctp_outq, GFP_KERNEL);
 199         if (q) {
 200                 sctp_outq_init(asoc, q);
 201                 q->malloced = 1;
 202         }
 203         return q;
 204 }
 205
 206 /* Initialize an existing sctp_outq.  This does the boring stuff.
 207  * You still need to define handlers if you really want to DO
 208  * something with this structure...
 209  */
 210 void sctp_outq_init(struct sctp_association *asoc, struct sctp_outq *q)
 211 {
 212         q->asoc = asoc;
 213         skb_queue_head_init(&q->out);
 214         skb_queue_head_init(&q->control);
 215         INIT_LIST_HEAD(&q->retransmit);
 216         INIT_LIST_HEAD(&q->sacked);
 217         INIT_LIST_HEAD(&q->abandoned);
 218
 219         q->outstanding_bytes = 0;
 220         q->empty = 1;
 221         q->cork  = 0;
 222
 223         q->malloced = 0;
 224         q->out_qlen = 0;
 225 }
 226
 227 /* Free the outqueue structure and any related pending chunks.
 228  */
 229 void sctp_outq_teardown(struct sctp_outq *q)
 230 {
 231         struct sctp_transport *transport;
 232         struct list_head *lchunk, *pos, *temp;
 233         struct sctp_chunk *chunk;
 234
 235         /* Throw away unacknowledged chunks. */
 236         list_for_each(pos, &q->asoc->peer.transport_addr_list) {
 237                 transport = list_entry(pos, struct sctp_transport, transports);
 238                 while ((lchunk = sctp_list_dequeue(&transport->transmitted)) != NULL) {
 239                         chunk = list_entry(lchunk, struct sctp_chunk,
 240                                            transmitted_list);
 241                         /* Mark as part of a failed message. */
 242                         sctp_chunk_fail(chunk, q->error);
 243                         sctp_chunk_free(chunk);
 244                 }
 245         }
 246
 247         /* Throw away chunks that have been gap ACKed.  */
 248         list_for_each_safe(lchunk, temp, &q->sacked) {
 249                 list_del_init(lchunk);
 250                 chunk = list_entry(lchunk, struct sctp_chunk,
 251                                    transmitted_list);
 252                 sctp_chunk_fail(chunk, q->error);
 253                 sctp_chunk_free(chunk);
 254         }
 255
 256         /* Throw away any chunks in the retransmit queue. */
 257         list_for_each_safe(lchunk, temp, &q->retransmit) {
 258                 list_del_init(lchunk);
 259                 chunk = list_entry(lchunk, struct sctp_chunk,
 260                                    transmitted_list);
 261                 sctp_chunk_fail(chunk, q->error);
 262                 sctp_chunk_free(chunk);
 263         }
 264
 265         /* Throw away any chunks that are in the abandoned queue. */
 266         list_for_each_safe(lchunk, temp, &q->abandoned) {
 267                 list_del_init(lchunk);
 268                 chunk = list_entry(lchunk, struct sctp_chunk,
 269                                    transmitted_list);
 270                 sctp_chunk_fail(chunk, q->error);
 271                 sctp_chunk_free(chunk);
 272         }
 273
 274         /* Throw away any leftover data chunks. */
 275         while ((chunk = sctp_outq_dequeue_data(q)) != NULL) {
 276
 277                 /* Mark as send failure. */
 278                 sctp_chunk_fail(chunk, q->error);
 279                 sctp_chunk_free(chunk);
 280         }
 281
 282         q->error = 0;
 283
 284         /* Throw away any leftover control chunks. */
 285         while ((chunk = (struct sctp_chunk *) skb_dequeue(&q->control)) != NULL)
 286                 sctp_chunk_free(chunk);
 287 }
 288
 289 /* Free the outqueue structure and any related pending chunks.  */
 290 void sctp_outq_free(struct sctp_outq *q)
 291 {
 292         /* Throw away leftover chunks. */
 293         sctp_outq_teardown(q);
 294
 295         /* If we were kmalloc()'d, free the memory.  */
 296         if (q->malloced)
 297                 kfree(q);
 298 }
 299
 300 /* Put a new chunk in an sctp_outq.  */
 301 int sctp_outq_tail(struct sctp_outq *q, struct sctp_chunk *chunk)
 302 {
 303         int error = 0;
 304
 305         SCTP_DEBUG_PRINTK("sctp_outq_tail(%p, %p[%s])\n",
 306                           q, chunk, chunk && chunk->chunk_hdr ?
 307                           sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type))
 308                           : "Illegal Chunk");
 309
 310         /* If it is data, queue it up, otherwise, send it
 311          * immediately.
 312          */
 313         if (SCTP_CID_DATA == chunk->chunk_hdr->type) {
 314                 /* Is it OK to queue data chunks?  */
 315                 /* From 9. Termination of Association
 316                  *
 317                  * When either endpoint performs a shutdown, the
 318                  * association on each peer will stop accepting new
 319                  * data from its user and only deliver data in queue
 320                  * at the time of sending or receiving the SHUTDOWN
 321                  * chunk.
 322                  */
 323                 switch (q->asoc->state) {
 324                 case SCTP_STATE_EMPTY:
 325                 case SCTP_STATE_CLOSED:
 326                 case SCTP_STATE_SHUTDOWN_PENDING:
 327                 case SCTP_STATE_SHUTDOWN_SENT:
 328                 case SCTP_STATE_SHUTDOWN_RECEIVED:
 329                 case SCTP_STATE_SHUTDOWN_ACK_SENT:
 330                         /* Cannot send after transport endpoint shutdown */
 331                         error = -ESHUTDOWN;
 332                         break;
 333
 334                 default:
 335                         SCTP_DEBUG_PRINTK("outqueueing (%p, %p[%s])\n",
 336                           q, chunk, chunk && chunk->chunk_hdr ?
 337                           sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type))
 338                           : "Illegal Chunk");
 339
 340                         sctp_outq_tail_data(q, chunk);
 341                         if (chunk->chunk_hdr->flags & SCTP_DATA_UNORDERED)
 342                                 SCTP_INC_STATS(SCTP_MIB_OUTUNORDERCHUNKS);
 343                         else
 344                                 SCTP_INC_STATS(SCTP_MIB_OUTORDERCHUNKS);
 345                         q->empty = 0;
 346                         break;
 347                 };
 348         } else {
 349                 __skb_queue_tail(&q->control, (struct sk_buff *) chunk);
 350                 SCTP_INC_STATS(SCTP_MIB_OUTCTRLCHUNKS);
 351         }
 352
 353         if (error < 0)
 354                 return error;
 355
 356         if (!q->cork)
 357                 error = sctp_outq_flush(q, 0);
 358
 359         return error;
 360 }
 361
 362 /* Insert a chunk into the sorted list based on the TSNs.  The retransmit list
 363  * and the abandoned list are in ascending order.
 364  */
 365 void sctp_insert_list(struct list_head *head, struct list_head *new)
 366 {
 367         struct list_head *pos;
 368         struct sctp_chunk *nchunk, *lchunk;
 369         __u32 ntsn, ltsn;
 370         int done = 0;
 371
 372         nchunk = list_entry(new, struct sctp_chunk, transmitted_list);
 373         ntsn = ntohl(nchunk->subh.data_hdr->tsn);
 374
 375         list_for_each(pos, head) {
 376                 lchunk = list_entry(pos, struct sctp_chunk, transmitted_list);
 377                 ltsn = ntohl(lchunk->subh.data_hdr->tsn);
 378                 if (TSN_lt(ntsn, ltsn)) {
 379                         list_add(new, pos->prev);
 380                         done = 1;
 381                         break;
 382                 }
 383         }
 384         if (!done)
 385                 list_add_tail(new, head);
 386 }
 387
 388 /* Mark all the eligible packets on a transport for retransmission.  */
 389 void sctp_retransmit_mark(struct sctp_outq *q,
 390                           struct sctp_transport *transport,
 391                           __u8 fast_retransmit)
 392 {
 393         struct list_head *lchunk, *ltemp;
 394         struct sctp_chunk *chunk;
 395
 396         /* Walk through the specified transmitted queue.  */
 397         list_for_each_safe(lchunk, ltemp, &transport->transmitted) {
 398                 chunk = list_entry(lchunk, struct sctp_chunk,
 399                                    transmitted_list);
 400
 401                 /* If the chunk is abandoned, move it to abandoned list. */
 402                 if (sctp_chunk_abandoned(chunk)) {
 403                         list_del_init(lchunk);
 404                         sctp_insert_list(&q->abandoned, lchunk);
 405                         continue;
 406                 }
 407
 408                 /* If we are doing retransmission due to a fast retransmit,
 409                  * only the chunk's that are marked for fast retransmit
 410                  * should be added to the retransmit queue.  If we are doing
 411                  * retransmission due to a timeout or pmtu discovery, only the
 412                  * chunks that are not yet acked should be added to the
 413                  * retransmit queue.
 414                  */
 415                 if ((fast_retransmit && chunk->fast_retransmit) ||
 416                    (!fast_retransmit && !chunk->tsn_gap_acked)) {
 417                         /* RFC 2960 6.2.1 Processing a Received SACK
 418                          *
 419                          * C) Any time a DATA chunk is marked for
 420                          * retransmission (via either T3-rtx timer expiration
 421                          * (Section 6.3.3) or via fast retransmit
 422                          * (Section 7.2.4)), add the data size of those
 423                          * chunks to the rwnd.
 424                          */
 425                         q->asoc->peer.rwnd += sctp_data_size(chunk);
 426                         q->outstanding_bytes -= sctp_data_size(chunk);
 427                         transport->flight_size -= sctp_data_size(chunk);
 428
 429                         /* sctpimpguide-05 Section 2.8.2
 430                          * M5) If a T3-rtx timer expires, the
 431                          * 'TSN.Missing.Report' of all affected TSNs is set
 432                          * to 0.
 433                          */
 434                         chunk->tsn_missing_report = 0;
 435
 436                         /* If a chunk that is being used for RTT measurement
 437                          * has to be retransmitted, we cannot use this chunk
 438                          * anymore for RTT measurements. Reset rto_pending so
 439                          * that a new RTT measurement is started when a new
 440                          * data chunk is sent.
 441                          */
 442                         if (chunk->rtt_in_progress) {
 443                                 chunk->rtt_in_progress = 0;
 444                                 transport->rto_pending = 0;
 445                         }
 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         SCTP_DEBUG_PRINTK("%s: transport: %p, fast_retransmit: %d, "
 456                           "cwnd: %d, ssthresh: %d, flight_size: %d, "
 457                           "pba: %d\n", __FUNCTION__,
 458                           transport, fast_retransmit,
 459                           transport->cwnd, transport->ssthresh,
 460                           transport->flight_size,
 461                           transport->partial_bytes_acked);
 462
 463 }
 464
 465 /* Mark all the eligible packets on a transport for retransmission and force
 466  * one packet out.
 467  */
 468 void sctp_retransmit(struct sctp_outq *q, struct sctp_transport *transport,
 469                      sctp_retransmit_reason_t reason)
 470 {
 471         int error = 0;
 472         __u8 fast_retransmit = 0;
 473
 474         switch(reason) {
 475         case SCTP_RTXR_T3_RTX:
 476                 sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_T3_RTX);
 477                 /* Update the retran path if the T3-rtx timer has expired for
 478                  * the current retran path.
 479                  */
 480                 if (transport == transport->asoc->peer.retran_path)
 481                         sctp_assoc_update_retran_path(transport->asoc);
 482                 break;
 483         case SCTP_RTXR_FAST_RTX:
 484                 sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_FAST_RTX);
 485                 fast_retransmit = 1;
 486                 break;
 487         case SCTP_RTXR_PMTUD:
 488         default:
 489                 break;
 490         }
 491
 492         sctp_retransmit_mark(q, transport, fast_retransmit);
 493
 494         /* PR-SCTP A5) Any time the T3-rtx timer expires, on any destination,
 495          * the sender SHOULD try to advance the "Advanced.Peer.Ack.Point" by
 496          * following the procedures outlined in C1 - C5.
 497          */
 498         sctp_generate_fwdtsn(q, q->asoc->ctsn_ack_point);
 499
 500         error = sctp_outq_flush(q, /* rtx_timeout */ 1);
 501
 502         if (error)
 503                 q->asoc->base.sk->sk_err = -error;
 504 }
 505
 506 /*
 507  * Transmit DATA chunks on the retransmit queue.  Upon return from
 508  * sctp_outq_flush_rtx() the packet 'pkt' may contain chunks which
 509  * need to be transmitted by the caller.
 510  * We assume that pkt->transport has already been set.
 511  *
 512  * The return value is a normal kernel error return value.
 513  */
 514 static int sctp_outq_flush_rtx(struct sctp_outq *q, struct sctp_packet *pkt,
 515                                int rtx_timeout, int *start_timer)
 516 {
 517         struct list_head *lqueue;
 518         struct list_head *lchunk, *lchunk1;
 519         struct sctp_transport *transport = pkt->transport;
 520         sctp_xmit_t status;
 521         struct sctp_chunk *chunk, *chunk1;
 522         struct sctp_association *asoc;
 523         int error = 0;
 524
 525         asoc = q->asoc;
 526         lqueue = &q->retransmit;
 527
 528         /* RFC 2960 6.3.3 Handle T3-rtx Expiration
 529          *
 530          * E3) Determine how many of the earliest (i.e., lowest TSN)
 531          * outstanding DATA chunks for the address for which the
 532          * T3-rtx has expired will fit into a single packet, subject
 533          * to the MTU constraint for the path corresponding to the
 534          * destination transport address to which the retransmission
 535          * is being sent (this may be different from the address for
 536          * which the timer expires [see Section 6.4]). Call this value
 537          * K. Bundle and retransmit those K DATA chunks in a single
 538          * packet to the destination endpoint.
 539          *
 540          * [Just to be painfully clear, if we are retransmitting
 541          * because a timeout just happened, we should send only ONE
 542          * packet of retransmitted data.]
 543          */
 544         lchunk = sctp_list_dequeue(lqueue);
 545
 546         while (lchunk) {
 547                 chunk = list_entry(lchunk, struct sctp_chunk,
 548                                    transmitted_list);
 549
 550                 /* Make sure that Gap Acked TSNs are not retransmitted.  A
 551                  * simple approach is just to move such TSNs out of the
 552                  * way and into a 'transmitted' queue and skip to the
 553                  * next chunk.
 554                  */
 555                 if (chunk->tsn_gap_acked) {
 556                         list_add_tail(lchunk, &transport->transmitted);
 557                         lchunk = sctp_list_dequeue(lqueue);
 558                         continue;
 559                 }
 560
 561                 /* Attempt to append this chunk to the packet. */
 562                 status = sctp_packet_append_chunk(pkt, chunk);
 563
 564                 switch (status) {
 565                 case SCTP_XMIT_PMTU_FULL:
 566                         /* Send this packet.  */
 567                         if ((error = sctp_packet_transmit(pkt)) == 0)
 568                                 *start_timer = 1;
 569
 570                         /* If we are retransmitting, we should only
 571                          * send a single packet.
 572                          */
 573                         if (rtx_timeout) {
 574                                 list_add(lchunk, lqueue);
 575                                 lchunk = NULL;
 576                         }
 577
 578                         /* Bundle lchunk in the next round.  */
 579                         break;
 580
 581                 case SCTP_XMIT_RWND_FULL:
 582                         /* Send this packet. */
 583                         if ((error = sctp_packet_transmit(pkt)) == 0)
 584                                 *start_timer = 1;
 585
 586                         /* Stop sending DATA as there is no more room
 587                          * at the receiver.
 588                          */
 589                         list_add(lchunk, lqueue);
 590                         lchunk = NULL;
 591                         break;
 592
 593                 case SCTP_XMIT_NAGLE_DELAY:
 594                         /* Send this packet. */
 595                         if ((error = sctp_packet_transmit(pkt)) == 0)
 596                                 *start_timer = 1;
 597
 598                         /* Stop sending DATA because of nagle delay. */
 599                         list_add(lchunk, lqueue);
 600                         lchunk = NULL;
 601                         break;
 602
 603                 default:
 604                         /* The append was successful, so add this chunk to
 605                          * the transmitted list.
 606                          */
 607                         list_add_tail(lchunk, &transport->transmitted);
 608
 609                         /* Mark the chunk as ineligible for fast retransmit
 610                          * after it is retransmitted.
 611                          */
 612                         chunk->fast_retransmit = 0;
 613
 614                         *start_timer = 1;
 615                         q->empty = 0;
 616
 617                         /* Retrieve a new chunk to bundle. */
 618                         lchunk = sctp_list_dequeue(lqueue);
 619                         break;
 620                 };
 621
 622                 /* If we are here due to a retransmit timeout or a fast
 623                  * retransmit and if there are any chunks left in the retransmit
 624                  * queue that could not fit in the PMTU sized packet, they need                  * to be marked as ineligible for a subsequent fast retransmit.
 625                  */
 626                 if (rtx_timeout && !lchunk) {
 627                         list_for_each(lchunk1, lqueue) {
 628                                 chunk1 = list_entry(lchunk1, struct sctp_chunk,
 629                                                     transmitted_list);
 630                                 chunk1->fast_retransmit = 0;
 631                         }
 632                 }
 633         }
 634
 635         return error;
 636 }
 637
 638 /* Cork the outqueue so queued chunks are really queued. */
 639 int sctp_outq_uncork(struct sctp_outq *q)
 640 {
 641         int error = 0;
 642         if (q->cork) {
 643                 q->cork = 0;
 644                 error = sctp_outq_flush(q, 0);
 645         }
 646         return error;
 647 }
 648
 649 /*
 650  * Try to flush an outqueue.
 651  *
 652  * Description: Send everything in q which we legally can, subject to
 653  * congestion limitations.
 654  * * Note: This function can be called from multiple contexts so appropriate
 655  * locking concerns must be made.  Today we use the sock lock to protect
 656  * this function.
 657  */
 658 int sctp_outq_flush(struct sctp_outq *q, int rtx_timeout)
 659 {
 660         struct sctp_packet *packet;
 661         struct sctp_packet singleton;
 662         struct sctp_association *asoc = q->asoc;
 663         __u16 sport = asoc->base.bind_addr.port;
 664         __u16 dport = asoc->peer.port;
 665         __u32 vtag = asoc->peer.i.init_tag;
 666         struct sk_buff_head *queue;
 667         struct sctp_transport *transport = NULL;
 668         struct sctp_transport *new_transport;
 669         struct sctp_chunk *chunk;
 670         sctp_xmit_t status;
 671         int error = 0;
 672         int start_timer = 0;
 673
 674         /* These transports have chunks to send. */
 675         struct list_head transport_list;
 676         struct list_head *ltransport;
 677
 678         INIT_LIST_HEAD(&transport_list);
 679         packet = NULL;
 680
 681         /*
 682          * 6.10 Bundling
 683          *   ...
 684          *   When bundling control chunks with DATA chunks, an
 685          *   endpoint MUST place control chunks first in the outbound
 686          *   SCTP packet.  The transmitter MUST transmit DATA chunks
 687          *   within a SCTP packet in increasing order of TSN.
 688          *   ...
 689          */
 690
 691         queue = &q->control;
 692         while ((chunk = (struct sctp_chunk *)skb_dequeue(queue)) != NULL) {
 693                 /* Pick the right transport to use. */
 694                 new_transport = chunk->transport;
 695
 696                 if (!new_transport) {
 697                         new_transport = asoc->peer.active_path;
 698                 } else if (!new_transport->active) {
 699                         /* If the chunk is Heartbeat or Heartbeat Ack,
 700                          * send it to chunk->transport, even if it's
 701                          * inactive.
 702                          *
 703                          * 3.3.6 Heartbeat Acknowledgement:
 704                          * ...
 705                          * A HEARTBEAT ACK is always sent to the source IP
 706                          * address of the IP datagram containing the
 707                          * HEARTBEAT chunk to which this ack is responding.
 708                          * ...
 709                          */
 710                         if (chunk->chunk_hdr->type != SCTP_CID_HEARTBEAT &&
 711                             chunk->chunk_hdr->type != SCTP_CID_HEARTBEAT_ACK)
 712                                 new_transport = asoc->peer.active_path;
 713                 }
 714
 715                 /* Are we switching transports?
 716                  * Take care of transport locks.
 717                  */
 718                 if (new_transport != transport) {
 719                         transport = new_transport;
 720                         if (list_empty(&transport->send_ready)) {
 721                                 list_add_tail(&transport->send_ready,
 722                                               &transport_list);
 723                         }
 724                         packet = &transport->packet;
 725                         sctp_packet_config(packet, vtag,
 726                                            asoc->peer.ecn_capable);
 727                 }
 728
 729                 switch (chunk->chunk_hdr->type) {
 730                 /*
 731                  * 6.10 Bundling
 732                  *   ...
 733                  *   An endpoint MUST NOT bundle INIT, INIT ACK or SHUTDOWN
 734                  *   COMPLETE with any other chunks.  [Send them immediately.]
 735                  */
 736                 case SCTP_CID_INIT:
 737                 case SCTP_CID_INIT_ACK:
 738                 case SCTP_CID_SHUTDOWN_COMPLETE:
 739                         sctp_packet_init(&singleton, transport, sport, dport);
 740                         sctp_packet_config(&singleton, vtag, 0);
 741                         sctp_packet_append_chunk(&singleton, chunk);
 742                         error = sctp_packet_transmit(&singleton);
 743                         if (error < 0)
 744                                 return error;
 745                         break;
 746
 747                 case SCTP_CID_ABORT:
 748                 case SCTP_CID_SACK:
 749                 case SCTP_CID_HEARTBEAT:
 750                 case SCTP_CID_HEARTBEAT_ACK:
 751                 case SCTP_CID_SHUTDOWN:
 752                 case SCTP_CID_SHUTDOWN_ACK:
 753                 case SCTP_CID_ERROR:
 754                 case SCTP_CID_COOKIE_ECHO:
 755                 case SCTP_CID_COOKIE_ACK:
 756                 case SCTP_CID_ECN_ECNE:
 757                 case SCTP_CID_ECN_CWR:
 758                 case SCTP_CID_ASCONF:
 759                 case SCTP_CID_ASCONF_ACK:
 760                 case SCTP_CID_FWD_TSN:
 761                         sctp_packet_transmit_chunk(packet, chunk);
 762                         break;
 763
 764                 default:
 765                         /* We built a chunk with an illegal type! */
 766                         BUG();
 767                 };
 768         }
 769
 770         /* Is it OK to send data chunks?  */
 771         switch (asoc->state) {
 772         case SCTP_STATE_COOKIE_ECHOED:
 773                 /* Only allow bundling when this packet has a COOKIE-ECHO
 774                  * chunk.
 775                  */
 776                 if (!packet || !packet->has_cookie_echo)
 777                         break;
 778
 779                 /* fallthru */
 780         case SCTP_STATE_ESTABLISHED:
 781         case SCTP_STATE_SHUTDOWN_PENDING:
 782         case SCTP_STATE_SHUTDOWN_RECEIVED:
 783                 /*
 784                  * RFC 2960 6.1  Transmission of DATA Chunks
 785                  *
 786                  * C) When the time comes for the sender to transmit,
 787                  * before sending new DATA chunks, the sender MUST
 788                  * first transmit any outstanding DATA chunks which
 789                  * are marked for retransmission (limited by the
 790                  * current cwnd).
 791                  */
 792                 if (!list_empty(&q->retransmit)) {
 793                         if (transport == asoc->peer.retran_path)
 794                                 goto retran;
 795
 796                         /* Switch transports & prepare the packet.  */
 797
 798                         transport = asoc->peer.retran_path;
 799
 800                         if (list_empty(&transport->send_ready)) {
 801                                 list_add_tail(&transport->send_ready,
 802                                               &transport_list);
 803                         }
 804
 805                         packet = &transport->packet;
 806                         sctp_packet_config(packet, vtag,
 807                                            asoc->peer.ecn_capable);
 808                 retran:
 809                         error = sctp_outq_flush_rtx(q, packet,
 810                                                     rtx_timeout, &start_timer);
 811
 812                         if (start_timer)
 813                                 sctp_transport_reset_timers(transport);
 814
 815                         /* This can happen on COOKIE-ECHO resend.  Only
 816                          * one chunk can get bundled with a COOKIE-ECHO.
 817                          */
 818                         if (packet->has_cookie_echo)
 819                                 goto sctp_flush_out;
 820
 821                         /* Don't send new data if there is still data
 822                          * waiting to retransmit.
 823                          */
 824                         if (!list_empty(&q->retransmit))
 825                                 goto sctp_flush_out;
 826                 }
 827
 828                 /* Finally, transmit new packets.  */
 829                 start_timer = 0;
 830                 queue = &q->out;
 831
 832                 while ((chunk = sctp_outq_dequeue_data(q)) != NULL) {
 833                         /* RFC 2960 6.5 Every DATA chunk MUST carry a valid
 834                          * stream identifier.
 835                          */
 836                         if (chunk->sinfo.sinfo_stream >=
 837                             asoc->c.sinit_num_ostreams) {
 838
 839                                 /* Mark as failed send. */
 840                                 sctp_chunk_fail(chunk, SCTP_ERROR_INV_STRM);
 841                                 sctp_chunk_free(chunk);
 842                                 continue;
 843                         }
 844
 845                         /* Has this chunk expired? */
 846                         if (sctp_chunk_abandoned(chunk)) {
 847                                 sctp_chunk_fail(chunk, 0);
 848                                 sctp_chunk_free(chunk);
 849                                 continue;
 850                         }
 851
 852                         /* If there is a specified transport, use it.
 853                          * Otherwise, we want to use the active path.
 854                          */
 855                         new_transport = chunk->transport;
 856                         if (!new_transport || !new_transport->active)
 857                                 new_transport = asoc->peer.active_path;
 858
 859                         /* Change packets if necessary.  */
 860                         if (new_transport != transport) {
 861                                 transport = new_transport;
 862
 863                                 /* Schedule to have this transport's
 864                                  * packet flushed.
 865                                  */
 866                                 if (list_empty(&transport->send_ready)) {
 867                                         list_add_tail(&transport->send_ready,
 868                                                       &transport_list);
 869                                 }
 870
 871                                 packet = &transport->packet;
 872                                 sctp_packet_config(packet, vtag,
 873                                                    asoc->peer.ecn_capable);
 874                         }
 875
 876                         SCTP_DEBUG_PRINTK("sctp_outq_flush(%p, %p[%s]), ",
 877                                           q, chunk,
 878                                           chunk && chunk->chunk_hdr ?
 879                                           sctp_cname(SCTP_ST_CHUNK(
 880                                                   chunk->chunk_hdr->type))
 881                                           : "Illegal Chunk");
 882
 883                         SCTP_DEBUG_PRINTK("TX TSN 0x%x skb->head "
 884                                         "%p skb->users %d.\n",
 885                                         ntohl(chunk->subh.data_hdr->tsn),
 886                                         chunk->skb ?chunk->skb->head : NULL,
 887                                         chunk->skb ?
 888                                         atomic_read(&chunk->skb->users) : -1);
 889
 890                         /* Add the chunk to the packet.  */
 891                         status = sctp_packet_transmit_chunk(packet, chunk);
 892
 893                         switch (status) {
 894                         case SCTP_XMIT_PMTU_FULL:
 895                         case SCTP_XMIT_RWND_FULL:
 896                         case SCTP_XMIT_NAGLE_DELAY:
 897                                 /* We could not append this chunk, so put
 898                                  * the chunk back on the output queue.
 899                                  */
 900                                 SCTP_DEBUG_PRINTK("sctp_outq_flush: could "
 901                                         "not transmit TSN: 0x%x, status: %d\n",
 902                                         ntohl(chunk->subh.data_hdr->tsn),
 903                                         status);
 904                                 sctp_outq_head_data(q, chunk);
 905                                 goto sctp_flush_out;
 906                                 break;
 907
 908                         case SCTP_XMIT_OK:
 909                                 break;
 910
 911                         default:
 912                                 BUG();
 913                         }
 914
 915                         /* BUG: We assume that the sctp_packet_transmit()
 916                          * call below will succeed all the time and add the
 917                          * chunk to the transmitted list and restart the
 918                          * timers.
 919                          * It is possible that the call can fail under OOM
 920                          * conditions.
 921                          *
 922                          * Is this really a problem?  Won't this behave
 923                          * like a lost TSN?
 924                          */
 925                         list_add_tail(&chunk->transmitted_list,
 926                                       &transport->transmitted);
 927
 928                         sctp_transport_reset_timers(transport);
 929
 930                         q->empty = 0;
 931
 932                         /* Only let one DATA chunk get bundled with a
 933                          * COOKIE-ECHO chunk.
 934                          */
 935                         if (packet->has_cookie_echo)
 936                                 goto sctp_flush_out;
 937                 }
 938                 break;
 939
 940         default:
 941                 /* Do nothing.  */
 942                 break;
 943         }
 944
 945 sctp_flush_out:
 946
 947         /* Before returning, examine all the transports touched in
 948          * this call.  Right now, we bluntly force clear all the
 949          * transports.  Things might change after we implement Nagle.
 950          * But such an examination is still required.
 951          *
 952          * --xguo
 953          */
 954         while ((ltransport = sctp_list_dequeue(&transport_list)) != NULL ) {
 955                 struct sctp_transport *t = list_entry(ltransport,
 956                                                       struct sctp_transport,
 957                                                       send_ready);
 958                 packet = &t->packet;
 959                 if (!sctp_packet_empty(packet))
 960                         error = sctp_packet_transmit(packet);
 961         }
 962
 963         return error;
 964 }
 965
 966 /* Update unack_data based on the incoming SACK chunk */
 967 static void sctp_sack_update_unack_data(struct sctp_association *assoc,
 968                                         struct sctp_sackhdr *sack)
 969 {
 970         sctp_sack_variable_t *frags;
 971         __u16 unack_data;
 972         int i;
 973
 974         unack_data = assoc->next_tsn - assoc->ctsn_ack_point - 1;
 975
 976         frags = sack->variable;
 977         for (i = 0; i < ntohs(sack->num_gap_ack_blocks); i++) {
 978                 unack_data -= ((ntohs(frags[i].gab.end) -
 979                                 ntohs(frags[i].gab.start) + 1));
 980         }
 981
 982         assoc->unack_data = unack_data;
 983 }
 984
 985 /* Return the highest new tsn that is acknowledged by the given SACK chunk. */
 986 static __u32 sctp_highest_new_tsn(struct sctp_sackhdr *sack,
 987                                   struct sctp_association *asoc)
 988 {
 989         struct list_head *ltransport, *lchunk;
 990         struct sctp_transport *transport;
 991         struct sctp_chunk *chunk;
 992         __u32 highest_new_tsn, tsn;
 993         struct list_head *transport_list = &asoc->peer.transport_addr_list;
 994
 995         highest_new_tsn = ntohl(sack->cum_tsn_ack);
 996
 997         list_for_each(ltransport, transport_list) {
 998                 transport = list_entry(ltransport, struct sctp_transport,
 999                                        transports);
1000                 list_for_each(lchunk, &transport->transmitted) {
1001                         chunk = list_entry(lchunk, struct sctp_chunk,
1002                                            transmitted_list);
1003                         tsn = ntohl(chunk->subh.data_hdr->tsn);
1004
1005                         if (!chunk->tsn_gap_acked &&
1006                             TSN_lt(highest_new_tsn, tsn) &&
1007                             sctp_acked(sack, tsn))
1008                                 highest_new_tsn = tsn;
1009                 }
1010         }
1011
1012         return highest_new_tsn;
1013 }
1014
1015 /* This is where we REALLY process a SACK.
1016  *
1017  * Process the SACK against the outqueue.  Mostly, this just frees
1018  * things off the transmitted queue.
1019  */
1020 int sctp_outq_sack(struct sctp_outq *q, struct sctp_sackhdr *sack)
1021 {
1022         struct sctp_association *asoc = q->asoc;
1023         struct sctp_transport *transport;
1024         struct sctp_chunk *tchunk = NULL;
1025         struct list_head *lchunk, *transport_list, *pos, *temp;
1026         sctp_sack_variable_t *frags = sack->variable;
1027         __u32 sack_ctsn, ctsn, tsn;
1028         __u32 highest_tsn, highest_new_tsn;
1029         __u32 sack_a_rwnd;
1030         unsigned outstanding;
1031         struct sctp_transport *primary = asoc->peer.primary_path;
1032         int count_of_newacks = 0;
1033
1034         /* Grab the association's destination address list. */
1035         transport_list = &asoc->peer.transport_addr_list;
1036
1037         sack_ctsn = ntohl(sack->cum_tsn_ack);
1038
1039         /*
1040          * SFR-CACC algorithm:
1041          * On receipt of a SACK the sender SHOULD execute the
1042          * following statements.
1043          *
1044          * 1) If the cumulative ack in the SACK passes next tsn_at_change
1045          * on the current primary, the CHANGEOVER_ACTIVE flag SHOULD be
1046          * cleared. The CYCLING_CHANGEOVER flag SHOULD also be cleared for
1047          * all destinations.
1048          */
1049         if (TSN_lte(primary->cacc.next_tsn_at_change, sack_ctsn)) {
1050                 primary->cacc.changeover_active = 0;
1051                 list_for_each(pos, transport_list) {
1052                         transport = list_entry(pos, struct sctp_transport,
1053                                         transports);
1054                         transport->cacc.cycling_changeover = 0;
1055                 }
1056         }
1057
1058         /*
1059          * SFR-CACC algorithm:
1060          * 2) If the SACK contains gap acks and the flag CHANGEOVER_ACTIVE
1061          * is set the receiver of the SACK MUST take the following actions:
1062          *
1063          * A) Initialize the cacc_saw_newack to 0 for all destination
1064          * addresses.
1065          */
1066         if (sack->num_gap_ack_blocks > 0 &&
1067             primary->cacc.changeover_active) {
1068                 list_for_each(pos, transport_list) {
1069                         transport = list_entry(pos, struct sctp_transport,
1070                                         transports);
1071                         transport->cacc.cacc_saw_newack = 0;
1072                 }
1073         }
1074
1075         /* Get the highest TSN in the sack. */
1076         highest_tsn = sack_ctsn;
1077         if (sack->num_gap_ack_blocks)
1078                 highest_tsn +=
1079                     ntohs(frags[ntohs(sack->num_gap_ack_blocks) - 1].gab.end);
1080
1081         if (TSN_lt(asoc->highest_sacked, highest_tsn)) {
1082                 highest_new_tsn = highest_tsn;
1083                 asoc->highest_sacked = highest_tsn;
1084         } else {
1085                 highest_new_tsn = sctp_highest_new_tsn(sack, asoc);
1086         }
1087
1088         /* Run through the retransmit queue.  Credit bytes received
1089          * and free those chunks that we can.
1090          */
1091         sctp_check_transmitted(q, &q->retransmit, NULL, sack, highest_new_tsn);
1092         sctp_mark_missing(q, &q->retransmit, NULL, highest_new_tsn, 0);
1093
1094         /* Run through the transmitted queue.
1095          * Credit bytes received and free those chunks which we can.
1096          *
1097          * This is a MASSIVE candidate for optimization.
1098          */
1099         list_for_each(pos, transport_list) {
1100                 transport  = list_entry(pos, struct sctp_transport,
1101                                         transports);
1102                 sctp_check_transmitted(q, &transport->transmitted,
1103                                        transport, sack, highest_new_tsn);
1104                 /*
1105                  * SFR-CACC algorithm:
1106                  * C) Let count_of_newacks be the number of
1107                  * destinations for which cacc_saw_newack is set.
1108                  */
1109                 if (transport->cacc.cacc_saw_newack)
1110                         count_of_newacks ++;
1111         }
1112
1113         list_for_each(pos, transport_list) {
1114                 transport  = list_entry(pos, struct sctp_transport,
1115                                         transports);
1116                 sctp_mark_missing(q, &transport->transmitted, transport,
1117                                   highest_new_tsn, count_of_newacks);
1118         }
1119
1120         /* Move the Cumulative TSN Ack Point if appropriate.  */
1121         if (TSN_lt(asoc->ctsn_ack_point, sack_ctsn))
1122                 asoc->ctsn_ack_point = sack_ctsn;
1123
1124         /* Update unack_data field in the assoc. */
1125         sctp_sack_update_unack_data(asoc, sack);
1126
1127         ctsn = asoc->ctsn_ack_point;
1128
1129         /* Throw away stuff rotting on the sack queue.  */
1130         list_for_each_safe(lchunk, temp, &q->sacked) {
1131                 tchunk = list_entry(lchunk, struct sctp_chunk,
1132                                     transmitted_list);
1133                 tsn = ntohl(tchunk->subh.data_hdr->tsn);
1134                 if (TSN_lte(tsn, ctsn))
1135                         sctp_chunk_free(tchunk);
1136         }
1137
1138         /* ii) Set rwnd equal to the newly received a_rwnd minus the
1139          *     number of bytes still outstanding after processing the
1140          *     Cumulative TSN Ack and the Gap Ack Blocks.
1141          */
1142
1143         sack_a_rwnd = ntohl(sack->a_rwnd);
1144         outstanding = q->outstanding_bytes;
1145
1146         if (outstanding < sack_a_rwnd)
1147                 sack_a_rwnd -= outstanding;
1148         else
1149                 sack_a_rwnd = 0;
1150
1151         asoc->peer.rwnd = sack_a_rwnd;
1152
1153         sctp_generate_fwdtsn(q, sack_ctsn);
1154
1155         SCTP_DEBUG_PRINTK("%s: sack Cumulative TSN Ack is 0x%x.\n",
1156                           __FUNCTION__, sack_ctsn);
1157         SCTP_DEBUG_PRINTK("%s: Cumulative TSN Ack of association, "
1158                           "%p is 0x%x. Adv peer ack point: 0x%x\n",
1159                           __FUNCTION__, asoc, ctsn, asoc->adv_peer_ack_point);
1160
1161         /* See if all chunks are acked.
1162          * Make sure the empty queue handler will get run later.
1163          */
1164         q->empty = skb_queue_empty(&q->out) && skb_queue_empty(&q->control) &&
1165                         list_empty(&q->retransmit);
1166         if (!q->empty)
1167                 goto finish;
1168
1169         list_for_each(pos, transport_list) {
1170                 transport  = list_entry(pos, struct sctp_transport,
1171                                         transports);
1172                 q->empty = q->empty && list_empty(&transport->transmitted);
1173                 if (!q->empty)
1174                         goto finish;
1175         }
1176
1177         SCTP_DEBUG_PRINTK("sack queue is empty.\n");
1178 finish:
1179         return q->empty;
1180 }
1181
1182 /* Is the outqueue empty?  */
1183 int sctp_outq_is_empty(const struct sctp_outq *q)
1184 {
1185         return q->empty;
1186 }
1187
1188 /********************************************************************
1189  * 2nd Level Abstractions
1190  ********************************************************************/
1191
1192 /* Go through a transport's transmitted list or the association's retransmit
1193  * list and move chunks that are acked by the Cumulative TSN Ack to q->sacked.
1194  * The retransmit list will not have an associated transport.
1195  *
1196  * I added coherent debug information output.   --xguo
1197  *
1198  * Instead of printing 'sacked' or 'kept' for each TSN on the
1199  * transmitted_queue, we print a range: SACKED: TSN1-TSN2, TSN3, TSN4-TSN5.
1200  * KEPT TSN6-TSN7, etc.
1201  */
1202 static void sctp_check_transmitted(struct sctp_outq *q,
1203                                    struct list_head *transmitted_queue,
1204                                    struct sctp_transport *transport,
1205                                    struct sctp_sackhdr *sack,
1206                                    __u32 highest_new_tsn_in_sack)
1207 {
1208         struct list_head *lchunk;
1209         struct sctp_chunk *tchunk;
1210         struct list_head tlist;
1211         __u32 tsn;
1212         __u32 sack_ctsn;
1213         __u32 rtt;
1214         __u8 restart_timer = 0;
1215         int bytes_acked = 0;
1216
1217         /* These state variables are for coherent debug output. --xguo */
1218
1219 #if SCTP_DEBUG
1220         __u32 dbg_ack_tsn = 0;  /* An ACKed TSN range starts here... */
1221         __u32 dbg_last_ack_tsn = 0;  /* ...and finishes here.        */
1222         __u32 dbg_kept_tsn = 0; /* An un-ACKed range starts here...  */
1223         __u32 dbg_last_kept_tsn = 0; /* ...and finishes here.        */
1224
1225         /* 0 : The last TSN was ACKed.
1226          * 1 : The last TSN was NOT ACKed (i.e. KEPT).
1227          * -1: We need to initialize.
1228          */
1229         int dbg_prt_state = -1;
1230 #endif /* SCTP_DEBUG */
1231
1232         sack_ctsn = ntohl(sack->cum_tsn_ack);
1233
1234         INIT_LIST_HEAD(&tlist);
1235
1236         /* The while loop will skip empty transmitted queues. */
1237         while (NULL != (lchunk = sctp_list_dequeue(transmitted_queue))) {
1238                 tchunk = list_entry(lchunk, struct sctp_chunk,
1239                                     transmitted_list);
1240
1241                 if (sctp_chunk_abandoned(tchunk)) {
1242                         /* Move the chunk to abandoned list. */
1243                         sctp_insert_list(&q->abandoned, lchunk);
1244                         continue;
1245                 }
1246
1247                 tsn = ntohl(tchunk->subh.data_hdr->tsn);
1248                 if (sctp_acked(sack, tsn)) {
1249                         /* If this queue is the retransmit queue, the
1250                          * retransmit timer has already reclaimed
1251                          * the outstanding bytes for this chunk, so only
1252                          * count bytes associated with a transport.
1253                          */
1254                         if (transport) {
1255                                 /* If this chunk is being used for RTT
1256                                  * measurement, calculate the RTT and update
1257                                  * the RTO using this value.
1258                                  *
1259                                  * 6.3.1 C5) Karn's algorithm: RTT measurements
1260                                  * MUST NOT be made using packets that were
1261                                  * retransmitted (and thus for which it is
1262                                  * ambiguous whether the reply was for the
1263                                  * first instance of the packet or a later
1264                                  * instance).
1265                                  */
1266                                 if (!tchunk->tsn_gap_acked &&
1267                                     !tchunk->resent &&
1268                                     tchunk->rtt_in_progress) {
1269                                         rtt = jiffies - tchunk->sent_at;
1270                                         sctp_transport_update_rto(transport,
1271                                                                   rtt);
1272                                 }
1273                         }
1274                         if (TSN_lte(tsn, sack_ctsn)) {
1275                                 /* RFC 2960  6.3.2 Retransmission Timer Rules
1276                                  *
1277                                  * R3) Whenever a SACK is received
1278                                  * that acknowledges the DATA chunk
1279                                  * with the earliest outstanding TSN
1280                                  * for that address, restart T3-rtx
1281                                  * timer for that address with its
1282                                  * current RTO.
1283                                  */
1284                                 restart_timer = 1;
1285
1286                                 if (!tchunk->tsn_gap_acked) {
1287                                         tchunk->tsn_gap_acked = 1;
1288                                         bytes_acked += sctp_data_size(tchunk);
1289                                         /*
1290                                          * SFR-CACC algorithm:
1291                                          * 2) If the SACK contains gap acks
1292                                          * and the flag CHANGEOVER_ACTIVE is
1293                                          * set the receiver of the SACK MUST
1294                                          * take the following action:
1295                                          *
1296                                          * B) For each TSN t being acked that
1297                                          * has not been acked in any SACK so
1298                                          * far, set cacc_saw_newack to 1 for
1299                                          * the destination that the TSN was
1300                                          * sent to.
1301                                          */
1302                                         if (transport &&
1303                                             sack->num_gap_ack_blocks &&
1304                                             q->asoc->peer.primary_path->cacc.
1305                                             changeover_active)
1306                                                 transport->cacc.cacc_saw_newack
1307                                                         = 1;
1308                                 }
1309
1310                                 list_add_tail(&tchunk->transmitted_list,
1311                                               &q->sacked);
1312                         } else {
1313                                 /* RFC2960 7.2.4, sctpimpguide-05 2.8.2
1314                                  * M2) Each time a SACK arrives reporting
1315                                  * 'Stray DATA chunk(s)' record the highest TSN
1316                                  * reported as newly acknowledged, call this
1317                                  * value 'HighestTSNinSack'. A newly
1318                                  * acknowledged DATA chunk is one not
1319                                  * previously acknowledged in a SACK.
1320                                  *
1321                                  * When the SCTP sender of data receives a SACK
1322                                  * chunk that acknowledges, for the first time,
1323                                  * the receipt of a DATA chunk, all the still
1324                                  * unacknowledged DATA chunks whose TSN is
1325                                  * older than that newly acknowledged DATA
1326                                  * chunk, are qualified as 'Stray DATA chunks'.
1327                                  */
1328                                 if (!tchunk->tsn_gap_acked) {
1329                                         tchunk->tsn_gap_acked = 1;
1330                                         bytes_acked += sctp_data_size(tchunk);
1331                                 }
1332                                 list_add_tail(lchunk, &tlist);
1333                         }
1334
1335 #if SCTP_DEBUG
1336                         switch (dbg_prt_state) {
1337                         case 0: /* last TSN was ACKed */
1338                                 if (dbg_last_ack_tsn + 1 == tsn) {
1339                                         /* This TSN belongs to the
1340                                          * current ACK range.
1341                                          */
1342                                         break;
1343                                 }
1344
1345                                 if (dbg_last_ack_tsn != dbg_ack_tsn) {
1346                                         /* Display the end of the
1347                                          * current range.
1348                                          */
1349                                         SCTP_DEBUG_PRINTK("-%08x",
1350                                                           dbg_last_ack_tsn);
1351                                 }
1352
1353                                 /* Start a new range.  */
1354                                 SCTP_DEBUG_PRINTK(",%08x", tsn);
1355                                 dbg_ack_tsn = tsn;
1356                                 break;
1357
1358                         case 1: /* The last TSN was NOT ACKed. */
1359                                 if (dbg_last_kept_tsn != dbg_kept_tsn) {
1360                                         /* Display the end of current range. */
1361                                         SCTP_DEBUG_PRINTK("-%08x",
1362                                                           dbg_last_kept_tsn);
1363                                 }
1364
1365                                 SCTP_DEBUG_PRINTK("\n");
1366
1367                                 /* FALL THROUGH... */
1368                         default:
1369                                 /* This is the first-ever TSN we examined.  */
1370                                 /* Start a new range of ACK-ed TSNs.  */
1371                                 SCTP_DEBUG_PRINTK("ACKed: %08x", tsn);
1372                                 dbg_prt_state = 0;
1373                                 dbg_ack_tsn = tsn;
1374                         };
1375
1376                         dbg_last_ack_tsn = tsn;
1377 #endif /* SCTP_DEBUG */
1378
1379                 } else {
1380                         if (tchunk->tsn_gap_acked) {
1381                                 SCTP_DEBUG_PRINTK("%s: Receiver reneged on "
1382                                                   "data TSN: 0x%x\n",
1383                                                   __FUNCTION__,
1384                                                   tsn);
1385                                 tchunk->tsn_gap_acked = 0;
1386
1387                                 bytes_acked -= sctp_data_size(tchunk);
1388
1389                                 /* RFC 2960 6.3.2 Retransmission Timer Rules
1390                                  *
1391                                  * R4) Whenever a SACK is received missing a
1392                                  * TSN that was previously acknowledged via a
1393                                  * Gap Ack Block, start T3-rtx for the
1394                                  * destination address to which the DATA
1395                                  * chunk was originally
1396                                  * transmitted if it is not already running.
1397                                  */
1398                                 restart_timer = 1;
1399                         }
1400
1401                         list_add_tail(lchunk, &tlist);
1402
1403 #if SCTP_DEBUG
1404                         /* See the above comments on ACK-ed TSNs. */
1405                         switch (dbg_prt_state) {
1406                         case 1:
1407                                 if (dbg_last_kept_tsn + 1 == tsn)
1408                                         break;
1409
1410                                 if (dbg_last_kept_tsn != dbg_kept_tsn)
1411                                         SCTP_DEBUG_PRINTK("-%08x",
1412                                                           dbg_last_kept_tsn);
1413
1414                                 SCTP_DEBUG_PRINTK(",%08x", tsn);
1415                                 dbg_kept_tsn = tsn;
1416                                 break;
1417
1418                         case 0:
1419                                 if (dbg_last_ack_tsn != dbg_ack_tsn)
1420                                         SCTP_DEBUG_PRINTK("-%08x",
1421                                                           dbg_last_ack_tsn);
1422                                 SCTP_DEBUG_PRINTK("\n");
1423
1424                                 /* FALL THROUGH... */
1425                         default:
1426                                 SCTP_DEBUG_PRINTK("KEPT: %08x",tsn);
1427                                 dbg_prt_state = 1;
1428                                 dbg_kept_tsn = tsn;
1429                         };
1430
1431                         dbg_last_kept_tsn = tsn;
1432 #endif /* SCTP_DEBUG */
1433                 }
1434         }
1435
1436 #if SCTP_DEBUG
1437         /* Finish off the last range, displaying its ending TSN.  */
1438         switch (dbg_prt_state) {
1439         case 0:
1440                 if (dbg_last_ack_tsn != dbg_ack_tsn) {
1441                         SCTP_DEBUG_PRINTK("-%08x\n", dbg_last_ack_tsn);
1442                 } else {
1443                         SCTP_DEBUG_PRINTK("\n");
1444                 }
1445         break;
1446
1447         case 1:
1448                 if (dbg_last_kept_tsn != dbg_kept_tsn) {
1449                         SCTP_DEBUG_PRINTK("-%08x\n", dbg_last_kept_tsn);
1450                 } else {
1451                         SCTP_DEBUG_PRINTK("\n");
1452                 }
1453         };
1454 #endif /* SCTP_DEBUG */
1455         if (transport) {
1456                 if (bytes_acked) {
1457                         /* 8.2. When an outstanding TSN is acknowledged,
1458                          * the endpoint shall clear the error counter of
1459                          * the destination transport address to which the
1460                          * DATA chunk was last sent.
1461                          * The association's overall error counter is
1462                          * also cleared.
1463                          */
1464                         transport->error_count = 0;
1465                         transport->asoc->overall_error_count = 0;
1466
1467                         /* Mark the destination transport address as
1468                          * active if it is not so marked.
1469                          */
1470                         if (!transport->active) {
1471                                 sctp_assoc_control_transport(
1472                                         transport->asoc,
1473                                         transport,
1474                                         SCTP_TRANSPORT_UP,
1475                                         SCTP_RECEIVED_SACK);
1476                         }
1477
1478                         sctp_transport_raise_cwnd(transport, sack_ctsn,
1479                                                   bytes_acked);
1480
1481                         transport->flight_size -= bytes_acked;
1482                         q->outstanding_bytes -= bytes_acked;
1483                 } else {
1484                         /* RFC 2960 6.1, sctpimpguide-06 2.15.2
1485                          * When a sender is doing zero window probing, it
1486                          * should not timeout the association if it continues
1487                          * to receive new packets from the receiver. The
1488                          * reason is that the receiver MAY keep its window
1489                          * closed for an indefinite time.
1490                          * A sender is doing zero window probing when the
1491                          * receiver's advertised window is zero, and there is
1492                          * only one data chunk in flight to the receiver.
1493                          */
1494                         if (!q->asoc->peer.rwnd &&
1495                             !list_empty(&tlist) &&
1496                             (sack_ctsn+2 == q->asoc->next_tsn)) {
1497                                 SCTP_DEBUG_PRINTK("%s: SACK received for zero "
1498                                                   "window probe: %u\n",
1499                                                   __FUNCTION__, sack_ctsn);
1500                                 q->asoc->overall_error_count = 0;
1501                                 transport->error_count = 0;
1502                         }
1503                 }
1504
1505                 /* RFC 2960 6.3.2 Retransmission Timer Rules
1506                  *
1507                  * R2) Whenever all outstanding data sent to an address have
1508                  * been acknowledged, turn off the T3-rtx timer of that
1509                  * address.
1510                  */
1511                 if (!transport->flight_size) {
1512                         if (timer_pending(&transport->T3_rtx_timer) &&
1513                             del_timer(&transport->T3_rtx_timer)) {
1514                                 sctp_transport_put(transport);
1515                         }
1516                 } else if (restart_timer) {
1517                         if (!mod_timer(&transport->T3_rtx_timer,
1518                                        jiffies + transport->rto))
1519                                 sctp_transport_hold(transport);
1520                 }
1521         }
1522
1523         list_splice(&tlist, transmitted_queue);
1524 }
1525
1526 /* Mark chunks as missing and consequently may get retransmitted. */
1527 static void sctp_mark_missing(struct sctp_outq *q,
1528                               struct list_head *transmitted_queue,
1529                               struct sctp_transport *transport,
1530                               __u32 highest_new_tsn_in_sack,
1531                               int count_of_newacks)
1532 {
1533         struct sctp_chunk *chunk;
1534         struct list_head *pos;
1535         __u32 tsn;
1536         char do_fast_retransmit = 0;
1537         struct sctp_transport *primary = q->asoc->peer.primary_path;
1538
1539         list_for_each(pos, transmitted_queue) {
1540
1541                 chunk = list_entry(pos, struct sctp_chunk, transmitted_list);
1542                 tsn = ntohl(chunk->subh.data_hdr->tsn);
1543
1544                 /* RFC 2960 7.2.4, sctpimpguide-05 2.8.2 M3) Examine all
1545                  * 'Unacknowledged TSN's', if the TSN number of an
1546                  * 'Unacknowledged TSN' is smaller than the 'HighestTSNinSack'
1547                  * value, increment the 'TSN.Missing.Report' count on that
1548                  * chunk if it has NOT been fast retransmitted or marked for
1549                  * fast retransmit already.
1550                  */
1551                 if (!chunk->fast_retransmit &&
1552                     !chunk->tsn_gap_acked &&
1553                     TSN_lt(tsn, highest_new_tsn_in_sack)) {
1554
1555                         /* SFR-CACC may require us to skip marking
1556                          * this chunk as missing.
1557                          */
1558                         if (!transport || !sctp_cacc_skip(primary, transport,
1559                                             count_of_newacks, tsn)) {
1560                                 chunk->tsn_missing_report++;
1561
1562                                 SCTP_DEBUG_PRINTK(
1563                                         "%s: TSN 0x%x missing counter: %d\n",
1564                                         __FUNCTION__, tsn,
1565                                         chunk->tsn_missing_report);
1566                         }
1567                 }
1568                 /*
1569                  * M4) If any DATA chunk is found to have a
1570                  * 'TSN.Missing.Report'
1571                  * value larger than or equal to 4, mark that chunk for
1572                  * retransmission and start the fast retransmit procedure.
1573                  */
1574
1575                 if (chunk->tsn_missing_report >= 4) {
1576                         chunk->fast_retransmit = 1;
1577                         do_fast_retransmit = 1;
1578                 }
1579         }
1580
1581         if (transport) {
1582                 if (do_fast_retransmit)
1583                         sctp_retransmit(q, transport, SCTP_RTXR_FAST_RTX);
1584
1585                 SCTP_DEBUG_PRINTK("%s: transport: %p, cwnd: %d, "
1586                                   "ssthresh: %d, flight_size: %d, pba: %d\n",
1587                                   __FUNCTION__, transport, transport->cwnd,
1588                                   transport->ssthresh, transport->flight_size,
1589                                   transport->partial_bytes_acked);
1590         }
1591 }
1592
1593 /* Is the given TSN acked by this packet?  */
1594 static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn)
1595 {
1596         int i;
1597         sctp_sack_variable_t *frags;
1598         __u16 gap;
1599         __u32 ctsn = ntohl(sack->cum_tsn_ack);
1600
1601         if (TSN_lte(tsn, ctsn))
1602                 goto pass;
1603
1604         /* 3.3.4 Selective Acknowledgement (SACK) (3):
1605          *
1606          * Gap Ack Blocks:
1607          *  These fields contain the Gap Ack Blocks. They are repeated
1608          *  for each Gap Ack Block up to the number of Gap Ack Blocks
1609          *  defined in the Number of Gap Ack Blocks field. All DATA
1610          *  chunks with TSNs greater than or equal to (Cumulative TSN
1611          *  Ack + Gap Ack Block Start) and less than or equal to
1612          *  (Cumulative TSN Ack + Gap Ack Block End) of each Gap Ack
1613          *  Block are assumed to have been received correctly.
1614          */
1615
1616         frags = sack->variable;
1617         gap = tsn - ctsn;
1618         for (i = 0; i < ntohs(sack->num_gap_ack_blocks); ++i) {
1619                 if (TSN_lte(ntohs(frags[i].gab.start), gap) &&
1620                     TSN_lte(gap, ntohs(frags[i].gab.end)))
1621                         goto pass;
1622         }
1623
1624         return 0;
1625 pass:
1626         return 1;
1627 }
1628
1629 static inline int sctp_get_skip_pos(struct sctp_fwdtsn_skip *skiplist,
1630                                     int nskips, __u16 stream)
1631 {
1632         int i;
1633
1634         for (i = 0; i < nskips; i++) {
1635                 if (skiplist[i].stream == stream)
1636                         return i;
1637         }
1638         return i;
1639 }
1640
1641 /* Create and add a fwdtsn chunk to the outq's control queue if needed. */
1642 static void sctp_generate_fwdtsn(struct sctp_outq *q, __u32 ctsn)
1643 {
1644         struct sctp_association *asoc = q->asoc;
1645         struct sctp_chunk *ftsn_chunk = NULL;
1646         struct sctp_fwdtsn_skip ftsn_skip_arr[10];
1647         int nskips = 0;
1648         int skip_pos = 0;
1649         __u32 tsn;
1650         struct sctp_chunk *chunk;
1651         struct list_head *lchunk, *temp;
1652
1653         /* PR-SCTP C1) Let SackCumAck be the Cumulative TSN ACK carried in the
1654          * received SACK.
1655          *
1656          * If (Advanced.Peer.Ack.Point < SackCumAck), then update
1657          * Advanced.Peer.Ack.Point to be equal to SackCumAck.
1658          */
1659         if (TSN_lt(asoc->adv_peer_ack_point, ctsn))
1660                 asoc->adv_peer_ack_point = ctsn;
1661
1662         /* PR-SCTP C2) Try to further advance the "Advanced.Peer.Ack.Point"
1663          * locally, that is, to move "Advanced.Peer.Ack.Point" up as long as
1664          * the chunk next in the out-queue space is marked as "abandoned" as
1665          * shown in the following example:
1666          *
1667          * Assuming that a SACK arrived with the Cumulative TSN ACK 102
1668          * and the Advanced.Peer.Ack.Point is updated to this value:
1669          *
1670          *   out-queue at the end of  ==>   out-queue after Adv.Ack.Point
1671          *   normal SACK processing           local advancement
1672          *                ...                           ...
1673          *   Adv.Ack.Pt-> 102 acked                     102 acked
1674          *                103 abandoned                 103 abandoned
1675          *                104 abandoned     Adv.Ack.P-> 104 abandoned
1676          *                105                           105
1677          *                106 acked                     106 acked
1678          *                ...                           ...
1679          *
1680          * In this example, the data sender successfully advanced the
1681          * "Advanced.Peer.Ack.Point" from 102 to 104 locally.
1682          */
1683         list_for_each_safe(lchunk, temp, &q->abandoned) {
1684                 chunk = list_entry(lchunk, struct sctp_chunk,
1685                                         transmitted_list);
1686                 tsn = ntohl(chunk->subh.data_hdr->tsn);
1687
1688                 /* Remove any chunks in the abandoned queue that are acked by
1689                  * the ctsn.
1690                  */
1691                 if (TSN_lte(tsn, ctsn)) {
1692                         list_del_init(lchunk);
1693                         if (!chunk->tsn_gap_acked) {
1694                         chunk->transport->flight_size -=
1695                                                  sctp_data_size(chunk);
1696                         q->outstanding_bytes -= sctp_data_size(chunk);
1697                         }
1698                         sctp_chunk_free(chunk);
1699                 } else {
1700                         if (TSN_lte(tsn, asoc->adv_peer_ack_point+1)) {
1701                                 asoc->adv_peer_ack_point = tsn;
1702                                 if (chunk->chunk_hdr->flags &
1703                                          SCTP_DATA_UNORDERED)
1704                                         continue;
1705                                 skip_pos = sctp_get_skip_pos(&ftsn_skip_arr[0],
1706                                                 nskips,
1707                                                 chunk->subh.data_hdr->stream);
1708                                 ftsn_skip_arr[skip_pos].stream =
1709                                         chunk->subh.data_hdr->stream;
1710                                 ftsn_skip_arr[skip_pos].ssn =
1711                                          chunk->subh.data_hdr->ssn;
1712                                 if (skip_pos == nskips)
1713                                         nskips++;
1714                                 if (nskips == 10)
1715                                         break;
1716                         } else
1717                                 break;
1718                 }
1719         }
1720
1721         /* PR-SCTP C3) If, after step C1 and C2, the "Advanced.Peer.Ack.Point"
1722          * is greater than the Cumulative TSN ACK carried in the received
1723          * SACK, the data sender MUST send the data receiver a FORWARD TSN
1724          * chunk containing the latest value of the
1725          * "Advanced.Peer.Ack.Point".
1726          *
1727          * C4) For each "abandoned" TSN the sender of the FORWARD TSN SHOULD
1728          * list each stream and sequence number in the forwarded TSN. This
1729          * information will enable the receiver to easily find any
1730          * stranded TSN's waiting on stream reorder queues. Each stream
1731          * SHOULD only be reported once; this means that if multiple
1732          * abandoned messages occur in the same stream then only the
1733          * highest abandoned stream sequence number is reported. If the
1734          * total size of the FORWARD TSN does NOT fit in a single MTU then
1735          * the sender of the FORWARD TSN SHOULD lower the
1736          * Advanced.Peer.Ack.Point to the last TSN that will fit in a
1737          * single MTU.
1738          */
1739         if (asoc->adv_peer_ack_point > ctsn)
1740                 ftsn_chunk = sctp_make_fwdtsn(asoc, asoc->adv_peer_ack_point,
1741                                               nskips, &ftsn_skip_arr[0]);
1742
1743         if (ftsn_chunk) {
1744                 __skb_queue_tail(&q->control, (struct sk_buff *)ftsn_chunk);
1745                 SCTP_INC_STATS(SCTP_MIB_OUTCTRLCHUNKS);
1746         }
1747 }