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 /* Initialize an existing sctp_outq.  This does the boring stuff.
 194  * You still need to define handlers if you really want to DO
 195  * something with this structure...
 196  */
 197 void sctp_outq_init(struct sctp_association *asoc, struct sctp_outq *q)
 198 {
 199         q->asoc = asoc;
 200         skb_queue_head_init(&q->out);
 201         skb_queue_head_init(&q->control);
 202         INIT_LIST_HEAD(&q->retransmit);
 203         INIT_LIST_HEAD(&q->sacked);
 204         INIT_LIST_HEAD(&q->abandoned);
 205
 206         q->outstanding_bytes = 0;
 207         q->empty = 1;
 208         q->cork  = 0;
 209
 210         q->malloced = 0;
 211         q->out_qlen = 0;
 212 }
 213
 214 /* Free the outqueue structure and any related pending chunks.
 215  */
 216 void sctp_outq_teardown(struct sctp_outq *q)
 217 {
 218         struct sctp_transport *transport;
 219         struct list_head *lchunk, *pos, *temp;
 220         struct sctp_chunk *chunk;
 221
 222         /* Throw away unacknowledged chunks. */
 223         list_for_each(pos, &q->asoc->peer.transport_addr_list) {
 224                 transport = list_entry(pos, struct sctp_transport, transports);
 225                 while ((lchunk = sctp_list_dequeue(&transport->transmitted)) != NULL) {
 226                         chunk = list_entry(lchunk, struct sctp_chunk,
 227                                            transmitted_list);
 228                         /* Mark as part of a failed message. */
 229                         sctp_chunk_fail(chunk, q->error);
 230                         sctp_chunk_free(chunk);
 231                 }
 232         }
 233
 234         /* Throw away chunks that have been gap ACKed.  */
 235         list_for_each_safe(lchunk, temp, &q->sacked) {
 236                 list_del_init(lchunk);
 237                 chunk = list_entry(lchunk, struct sctp_chunk,
 238                                    transmitted_list);
 239                 sctp_chunk_fail(chunk, q->error);
 240                 sctp_chunk_free(chunk);
 241         }
 242
 243         /* Throw away any chunks in the retransmit queue. */
 244         list_for_each_safe(lchunk, temp, &q->retransmit) {
 245                 list_del_init(lchunk);
 246                 chunk = list_entry(lchunk, struct sctp_chunk,
 247                                    transmitted_list);
 248                 sctp_chunk_fail(chunk, q->error);
 249                 sctp_chunk_free(chunk);
 250         }
 251
 252         /* Throw away any chunks that are in the abandoned queue. */
 253         list_for_each_safe(lchunk, temp, &q->abandoned) {
 254                 list_del_init(lchunk);
 255                 chunk = list_entry(lchunk, struct sctp_chunk,
 256                                    transmitted_list);
 257                 sctp_chunk_fail(chunk, q->error);
 258                 sctp_chunk_free(chunk);
 259         }
 260
 261         /* Throw away any leftover data chunks. */
 262         while ((chunk = sctp_outq_dequeue_data(q)) != NULL) {
 263
 264                 /* Mark as send failure. */
 265                 sctp_chunk_fail(chunk, q->error);
 266                 sctp_chunk_free(chunk);
 267         }
 268
 269         q->error = 0;
 270
 271         /* Throw away any leftover control chunks. */
 272         while ((chunk = (struct sctp_chunk *) skb_dequeue(&q->control)) != NULL)
 273                 sctp_chunk_free(chunk);
 274 }
 275
 276 /* Free the outqueue structure and any related pending chunks.  */
 277 void sctp_outq_free(struct sctp_outq *q)
 278 {
 279         /* Throw away leftover chunks. */
 280         sctp_outq_teardown(q);
 281
 282         /* If we were kmalloc()'d, free the memory.  */
 283         if (q->malloced)
 284                 kfree(q);
 285 }
 286
 287 /* Put a new chunk in an sctp_outq.  */
 288 int sctp_outq_tail(struct sctp_outq *q, struct sctp_chunk *chunk)
 289 {
 290         int error = 0;
 291
 292         SCTP_DEBUG_PRINTK("sctp_outq_tail(%p, %p[%s])\n",
 293                           q, chunk, chunk && chunk->chunk_hdr ?
 294                           sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type))
 295                           : "Illegal Chunk");
 296
 297         /* If it is data, queue it up, otherwise, send it
 298          * immediately.
 299          */
 300         if (SCTP_CID_DATA == chunk->chunk_hdr->type) {
 301                 /* Is it OK to queue data chunks?  */
 302                 /* From 9. Termination of Association
 303                  *
 304                  * When either endpoint performs a shutdown, the
 305                  * association on each peer will stop accepting new
 306                  * data from its user and only deliver data in queue
 307                  * at the time of sending or receiving the SHUTDOWN
 308                  * chunk.
 309                  */
 310                 switch (q->asoc->state) {
 311                 case SCTP_STATE_EMPTY:
 312                 case SCTP_STATE_CLOSED:
 313                 case SCTP_STATE_SHUTDOWN_PENDING:
 314                 case SCTP_STATE_SHUTDOWN_SENT:
 315                 case SCTP_STATE_SHUTDOWN_RECEIVED:
 316                 case SCTP_STATE_SHUTDOWN_ACK_SENT:
 317                         /* Cannot send after transport endpoint shutdown */
 318                         error = -ESHUTDOWN;
 319                         break;
 320
 321                 default:
 322                         SCTP_DEBUG_PRINTK("outqueueing (%p, %p[%s])\n",
 323                           q, chunk, chunk && chunk->chunk_hdr ?
 324                           sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type))
 325                           : "Illegal Chunk");
 326
 327                         sctp_outq_tail_data(q, chunk);
 328                         if (chunk->chunk_hdr->flags & SCTP_DATA_UNORDERED)
 329                                 SCTP_INC_STATS(SCTP_MIB_OUTUNORDERCHUNKS);
 330                         else
 331                                 SCTP_INC_STATS(SCTP_MIB_OUTORDERCHUNKS);
 332                         q->empty = 0;
 333                         break;
 334                 };
 335         } else {
 336                 __skb_queue_tail(&q->control, (struct sk_buff *) chunk);
 337                 SCTP_INC_STATS(SCTP_MIB_OUTCTRLCHUNKS);
 338         }
 339
 340         if (error < 0)
 341                 return error;
 342
 343         if (!q->cork)
 344                 error = sctp_outq_flush(q, 0);
 345
 346         return error;
 347 }
 348
 349 /* Insert a chunk into the sorted list based on the TSNs.  The retransmit list
 350  * and the abandoned list are in ascending order.
 351  */
 352 static void sctp_insert_list(struct list_head *head, struct list_head *new)
 353 {
 354         struct list_head *pos;
 355         struct sctp_chunk *nchunk, *lchunk;
 356         __u32 ntsn, ltsn;
 357         int done = 0;
 358
 359         nchunk = list_entry(new, struct sctp_chunk, transmitted_list);
 360         ntsn = ntohl(nchunk->subh.data_hdr->tsn);
 361
 362         list_for_each(pos, head) {
 363                 lchunk = list_entry(pos, struct sctp_chunk, transmitted_list);
 364                 ltsn = ntohl(lchunk->subh.data_hdr->tsn);
 365                 if (TSN_lt(ntsn, ltsn)) {
 366                         list_add(new, pos->prev);
 367                         done = 1;
 368                         break;
 369                 }
 370         }
 371         if (!done)
 372                 list_add_tail(new, head);
 373 }
 374
 375 /* Mark all the eligible packets on a transport for retransmission.  */
 376 void sctp_retransmit_mark(struct sctp_outq *q,
 377                           struct sctp_transport *transport,
 378                           __u8 fast_retransmit)
 379 {
 380         struct list_head *lchunk, *ltemp;
 381         struct sctp_chunk *chunk;
 382
 383         /* Walk through the specified transmitted queue.  */
 384         list_for_each_safe(lchunk, ltemp, &transport->transmitted) {
 385                 chunk = list_entry(lchunk, struct sctp_chunk,
 386                                    transmitted_list);
 387
 388                 /* If the chunk is abandoned, move it to abandoned list. */
 389                 if (sctp_chunk_abandoned(chunk)) {
 390                         list_del_init(lchunk);
 391                         sctp_insert_list(&q->abandoned, lchunk);
 392                         continue;
 393                 }
 394
 395                 /* If we are doing retransmission due to a fast retransmit,
 396                  * only the chunk's that are marked for fast retransmit
 397                  * should be added to the retransmit queue.  If we are doing
 398                  * retransmission due to a timeout or pmtu discovery, only the
 399                  * chunks that are not yet acked should be added to the
 400                  * retransmit queue.
 401                  */
 402                 if ((fast_retransmit && chunk->fast_retransmit) ||
 403                    (!fast_retransmit && !chunk->tsn_gap_acked)) {
 404                         /* RFC 2960 6.2.1 Processing a Received SACK
 405                          *
 406                          * C) Any time a DATA chunk is marked for
 407                          * retransmission (via either T3-rtx timer expiration
 408                          * (Section 6.3.3) or via fast retransmit
 409                          * (Section 7.2.4)), add the data size of those
 410                          * chunks to the rwnd.
 411                          */
 412                         q->asoc->peer.rwnd += sctp_data_size(chunk);
 413                         q->outstanding_bytes -= sctp_data_size(chunk);
 414                         transport->flight_size -= sctp_data_size(chunk);
 415
 416                         /* sctpimpguide-05 Section 2.8.2
 417                          * M5) If a T3-rtx timer expires, the
 418                          * 'TSN.Missing.Report' of all affected TSNs is set
 419                          * to 0.
 420                          */
 421                         chunk->tsn_missing_report = 0;
 422
 423                         /* If a chunk that is being used for RTT measurement
 424                          * has to be retransmitted, we cannot use this chunk
 425                          * anymore for RTT measurements. Reset rto_pending so
 426                          * that a new RTT measurement is started when a new
 427                          * data chunk is sent.
 428                          */
 429                         if (chunk->rtt_in_progress) {
 430                                 chunk->rtt_in_progress = 0;
 431                                 transport->rto_pending = 0;
 432                         }
 433
 434                         /* Move the chunk to the retransmit queue. The chunks
 435                          * on the retransmit queue are always kept in order.
 436                          */
 437                         list_del_init(lchunk);
 438                         sctp_insert_list(&q->retransmit, lchunk);
 439                 }
 440         }
 441
 442         SCTP_DEBUG_PRINTK("%s: transport: %p, fast_retransmit: %d, "
 443                           "cwnd: %d, ssthresh: %d, flight_size: %d, "
 444                           "pba: %d\n", __FUNCTION__,
 445                           transport, fast_retransmit,
 446                           transport->cwnd, transport->ssthresh,
 447                           transport->flight_size,
 448                           transport->partial_bytes_acked);
 449
 450 }
 451
 452 /* Mark all the eligible packets on a transport for retransmission and force
 453  * one packet out.
 454  */
 455 void sctp_retransmit(struct sctp_outq *q, struct sctp_transport *transport,
 456                      sctp_retransmit_reason_t reason)
 457 {
 458         int error = 0;
 459         __u8 fast_retransmit = 0;
 460
 461         switch(reason) {
 462         case SCTP_RTXR_T3_RTX:
 463                 sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_T3_RTX);
 464                 /* Update the retran path if the T3-rtx timer has expired for
 465                  * the current retran path.
 466                  */
 467                 if (transport == transport->asoc->peer.retran_path)
 468                         sctp_assoc_update_retran_path(transport->asoc);
 469                 break;
 470         case SCTP_RTXR_FAST_RTX:
 471                 sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_FAST_RTX);
 472                 fast_retransmit = 1;
 473                 break;
 474         case SCTP_RTXR_PMTUD:
 475         default:
 476                 break;
 477         }
 478
 479         sctp_retransmit_mark(q, transport, fast_retransmit);
 480
 481         /* PR-SCTP A5) Any time the T3-rtx timer expires, on any destination,
 482          * the sender SHOULD try to advance the "Advanced.Peer.Ack.Point" by
 483          * following the procedures outlined in C1 - C5.
 484          */
 485         sctp_generate_fwdtsn(q, q->asoc->ctsn_ack_point);
 486
 487         error = sctp_outq_flush(q, /* rtx_timeout */ 1);
 488
 489         if (error)
 490                 q->asoc->base.sk->sk_err = -error;
 491 }
 492
 493 /*
 494  * Transmit DATA chunks on the retransmit queue.  Upon return from
 495  * sctp_outq_flush_rtx() the packet 'pkt' may contain chunks which
 496  * need to be transmitted by the caller.
 497  * We assume that pkt->transport has already been set.
 498  *
 499  * The return value is a normal kernel error return value.
 500  */
 501 static int sctp_outq_flush_rtx(struct sctp_outq *q, struct sctp_packet *pkt,
 502                                int rtx_timeout, int *start_timer)
 503 {
 504         struct list_head *lqueue;
 505         struct list_head *lchunk, *lchunk1;
 506         struct sctp_transport *transport = pkt->transport;
 507         sctp_xmit_t status;
 508         struct sctp_chunk *chunk, *chunk1;
 509         struct sctp_association *asoc;
 510         int error = 0;
 511
 512         asoc = q->asoc;
 513         lqueue = &q->retransmit;
 514
 515         /* RFC 2960 6.3.3 Handle T3-rtx Expiration
 516          *
 517          * E3) Determine how many of the earliest (i.e., lowest TSN)
 518          * outstanding DATA chunks for the address for which the
 519          * T3-rtx has expired will fit into a single packet, subject
 520          * to the MTU constraint for the path corresponding to the
 521          * destination transport address to which the retransmission
 522          * is being sent (this may be different from the address for
 523          * which the timer expires [see Section 6.4]). Call this value
 524          * K. Bundle and retransmit those K DATA chunks in a single
 525          * packet to the destination endpoint.
 526          *
 527          * [Just to be painfully clear, if we are retransmitting
 528          * because a timeout just happened, we should send only ONE
 529          * packet of retransmitted data.]
 530          */
 531         lchunk = sctp_list_dequeue(lqueue);
 532
 533         while (lchunk) {
 534                 chunk = list_entry(lchunk, struct sctp_chunk,
 535                                    transmitted_list);
 536
 537                 /* Make sure that Gap Acked TSNs are not retransmitted.  A
 538                  * simple approach is just to move such TSNs out of the
 539                  * way and into a 'transmitted' queue and skip to the
 540                  * next chunk.
 541                  */
 542                 if (chunk->tsn_gap_acked) {
 543                         list_add_tail(lchunk, &transport->transmitted);
 544                         lchunk = sctp_list_dequeue(lqueue);
 545                         continue;
 546                 }
 547
 548                 /* Attempt to append this chunk to the packet. */
 549                 status = sctp_packet_append_chunk(pkt, chunk);
 550
 551                 switch (status) {
 552                 case SCTP_XMIT_PMTU_FULL:
 553                         /* Send this packet.  */
 554                         if ((error = sctp_packet_transmit(pkt)) == 0)
 555                                 *start_timer = 1;
 556
 557                         /* If we are retransmitting, we should only
 558                          * send a single packet.
 559                          */
 560                         if (rtx_timeout) {
 561                                 list_add(lchunk, lqueue);
 562                                 lchunk = NULL;
 563                         }
 564
 565                         /* Bundle lchunk in the next round.  */
 566                         break;
 567
 568                 case SCTP_XMIT_RWND_FULL:
 569                         /* Send this packet. */
 570                         if ((error = sctp_packet_transmit(pkt)) == 0)
 571                                 *start_timer = 1;
 572
 573                         /* Stop sending DATA as there is no more room
 574                          * at the receiver.
 575                          */
 576                         list_add(lchunk, lqueue);
 577                         lchunk = NULL;
 578                         break;
 579
 580                 case SCTP_XMIT_NAGLE_DELAY:
 581                         /* Send this packet. */
 582                         if ((error = sctp_packet_transmit(pkt)) == 0)
 583                                 *start_timer = 1;
 584
 585                         /* Stop sending DATA because of nagle delay. */
 586                         list_add(lchunk, lqueue);
 587                         lchunk = NULL;
 588                         break;
 589
 590                 default:
 591                         /* The append was successful, so add this chunk to
 592                          * the transmitted list.
 593                          */
 594                         list_add_tail(lchunk, &transport->transmitted);
 595
 596                         /* Mark the chunk as ineligible for fast retransmit
 597                          * after it is retransmitted.
 598                          */
 599                         chunk->fast_retransmit = 0;
 600
 601                         *start_timer = 1;
 602                         q->empty = 0;
 603
 604                         /* Retrieve a new chunk to bundle. */
 605                         lchunk = sctp_list_dequeue(lqueue);
 606                         break;
 607                 };
 608
 609                 /* If we are here due to a retransmit timeout or a fast
 610                  * retransmit and if there are any chunks left in the retransmit
 611                  * queue that could not fit in the PMTU sized packet, they need                  * to be marked as ineligible for a subsequent fast retransmit.
 612                  */
 613                 if (rtx_timeout && !lchunk) {
 614                         list_for_each(lchunk1, lqueue) {
 615                                 chunk1 = list_entry(lchunk1, struct sctp_chunk,
 616                                                     transmitted_list);
 617                                 chunk1->fast_retransmit = 0;
 618                         }
 619                 }
 620         }
 621
 622         return error;
 623 }
 624
 625 /* Cork the outqueue so queued chunks are really queued. */
 626 int sctp_outq_uncork(struct sctp_outq *q)
 627 {
 628         int error = 0;
 629         if (q->cork) {
 630                 q->cork = 0;
 631                 error = sctp_outq_flush(q, 0);
 632         }
 633         return error;
 634 }
 635
 636 /*
 637  * Try to flush an outqueue.
 638  *
 639  * Description: Send everything in q which we legally can, subject to
 640  * congestion limitations.
 641  * * Note: This function can be called from multiple contexts so appropriate
 642  * locking concerns must be made.  Today we use the sock lock to protect
 643  * this function.
 644  */
 645 int sctp_outq_flush(struct sctp_outq *q, int rtx_timeout)
 646 {
 647         struct sctp_packet *packet;
 648         struct sctp_packet singleton;
 649         struct sctp_association *asoc = q->asoc;
 650         __u16 sport = asoc->base.bind_addr.port;
 651         __u16 dport = asoc->peer.port;
 652         __u32 vtag = asoc->peer.i.init_tag;
 653         struct sk_buff_head *queue;
 654         struct sctp_transport *transport = NULL;
 655         struct sctp_transport *new_transport;
 656         struct sctp_chunk *chunk;
 657         sctp_xmit_t status;
 658         int error = 0;
 659         int start_timer = 0;
 660
 661         /* These transports have chunks to send. */
 662         struct list_head transport_list;
 663         struct list_head *ltransport;
 664
 665         INIT_LIST_HEAD(&transport_list);
 666         packet = NULL;
 667
 668         /*
 669          * 6.10 Bundling
 670          *   ...
 671          *   When bundling control chunks with DATA chunks, an
 672          *   endpoint MUST place control chunks first in the outbound
 673          *   SCTP packet.  The transmitter MUST transmit DATA chunks
 674          *   within a SCTP packet in increasing order of TSN.
 675          *   ...
 676          */
 677
 678         queue = &q->control;
 679         while ((chunk = (struct sctp_chunk *)skb_dequeue(queue)) != NULL) {
 680                 /* Pick the right transport to use. */
 681                 new_transport = chunk->transport;
 682
 683                 if (!new_transport) {
 684                         new_transport = asoc->peer.active_path;
 685                 } else if (!new_transport->active) {
 686                         /* If the chunk is Heartbeat or Heartbeat Ack,
 687                          * send it to chunk->transport, even if it's
 688                          * inactive.
 689                          *
 690                          * 3.3.6 Heartbeat Acknowledgement:
 691                          * ...
 692                          * A HEARTBEAT ACK is always sent to the source IP
 693                          * address of the IP datagram containing the
 694                          * HEARTBEAT chunk to which this ack is responding.
 695                          * ...
 696                          */
 697                         if (chunk->chunk_hdr->type != SCTP_CID_HEARTBEAT &&
 698                             chunk->chunk_hdr->type != SCTP_CID_HEARTBEAT_ACK)
 699                                 new_transport = asoc->peer.active_path;
 700                 }
 701
 702                 /* Are we switching transports?
 703                  * Take care of transport locks.
 704                  */
 705                 if (new_transport != transport) {
 706                         transport = new_transport;
 707                         if (list_empty(&transport->send_ready)) {
 708                                 list_add_tail(&transport->send_ready,
 709                                               &transport_list);
 710                         }
 711                         packet = &transport->packet;
 712                         sctp_packet_config(packet, vtag,
 713                                            asoc->peer.ecn_capable);
 714                 }
 715
 716                 switch (chunk->chunk_hdr->type) {
 717                 /*
 718                  * 6.10 Bundling
 719                  *   ...
 720                  *   An endpoint MUST NOT bundle INIT, INIT ACK or SHUTDOWN
 721                  *   COMPLETE with any other chunks.  [Send them immediately.]
 722                  */
 723                 case SCTP_CID_INIT:
 724                 case SCTP_CID_INIT_ACK:
 725                 case SCTP_CID_SHUTDOWN_COMPLETE:
 726                         sctp_packet_init(&singleton, transport, sport, dport);
 727                         sctp_packet_config(&singleton, vtag, 0);
 728                         sctp_packet_append_chunk(&singleton, chunk);
 729                         error = sctp_packet_transmit(&singleton);
 730                         if (error < 0)
 731                                 return error;
 732                         break;
 733
 734                 case SCTP_CID_ABORT:
 735                 case SCTP_CID_SACK:
 736                 case SCTP_CID_HEARTBEAT:
 737                 case SCTP_CID_HEARTBEAT_ACK:
 738                 case SCTP_CID_SHUTDOWN:
 739                 case SCTP_CID_SHUTDOWN_ACK:
 740                 case SCTP_CID_ERROR:
 741                 case SCTP_CID_COOKIE_ECHO:
 742                 case SCTP_CID_COOKIE_ACK:
 743                 case SCTP_CID_ECN_ECNE:
 744                 case SCTP_CID_ECN_CWR:
 745                 case SCTP_CID_ASCONF:
 746                 case SCTP_CID_ASCONF_ACK:
 747                 case SCTP_CID_FWD_TSN:
 748                         sctp_packet_transmit_chunk(packet, chunk);
 749                         break;
 750
 751                 default:
 752                         /* We built a chunk with an illegal type! */
 753                         BUG();
 754                 };
 755         }
 756
 757         /* Is it OK to send data chunks?  */
 758         switch (asoc->state) {
 759         case SCTP_STATE_COOKIE_ECHOED:
 760                 /* Only allow bundling when this packet has a COOKIE-ECHO
 761                  * chunk.
 762                  */
 763                 if (!packet || !packet->has_cookie_echo)
 764                         break;
 765
 766                 /* fallthru */
 767         case SCTP_STATE_ESTABLISHED:
 768         case SCTP_STATE_SHUTDOWN_PENDING:
 769         case SCTP_STATE_SHUTDOWN_RECEIVED:
 770                 /*
 771                  * RFC 2960 6.1  Transmission of DATA Chunks
 772                  *
 773                  * C) When the time comes for the sender to transmit,
 774                  * before sending new DATA chunks, the sender MUST
 775                  * first transmit any outstanding DATA chunks which
 776                  * are marked for retransmission (limited by the
 777                  * current cwnd).
 778                  */
 779                 if (!list_empty(&q->retransmit)) {
 780                         if (transport == asoc->peer.retran_path)
 781                                 goto retran;
 782
 783                         /* Switch transports & prepare the packet.  */
 784
 785                         transport = asoc->peer.retran_path;
 786
 787                         if (list_empty(&transport->send_ready)) {
 788                                 list_add_tail(&transport->send_ready,
 789                                               &transport_list);
 790                         }
 791
 792                         packet = &transport->packet;
 793                         sctp_packet_config(packet, vtag,
 794                                            asoc->peer.ecn_capable);
 795                 retran:
 796                         error = sctp_outq_flush_rtx(q, packet,
 797                                                     rtx_timeout, &start_timer);
 798
 799                         if (start_timer)
 800                                 sctp_transport_reset_timers(transport);
 801
 802                         /* This can happen on COOKIE-ECHO resend.  Only
 803                          * one chunk can get bundled with a COOKIE-ECHO.
 804                          */
 805                         if (packet->has_cookie_echo)
 806                                 goto sctp_flush_out;
 807
 808                         /* Don't send new data if there is still data
 809                          * waiting to retransmit.
 810                          */
 811                         if (!list_empty(&q->retransmit))
 812                                 goto sctp_flush_out;
 813                 }
 814
 815                 /* Finally, transmit new packets.  */
 816                 start_timer = 0;
 817                 queue = &q->out;
 818
 819                 while ((chunk = sctp_outq_dequeue_data(q)) != NULL) {
 820                         /* RFC 2960 6.5 Every DATA chunk MUST carry a valid
 821                          * stream identifier.
 822                          */
 823                         if (chunk->sinfo.sinfo_stream >=
 824                             asoc->c.sinit_num_ostreams) {
 825
 826                                 /* Mark as failed send. */
 827                                 sctp_chunk_fail(chunk, SCTP_ERROR_INV_STRM);
 828                                 sctp_chunk_free(chunk);
 829                                 continue;
 830                         }
 831
 832                         /* Has this chunk expired? */
 833                         if (sctp_chunk_abandoned(chunk)) {
 834                                 sctp_chunk_fail(chunk, 0);
 835                                 sctp_chunk_free(chunk);
 836                                 continue;
 837                         }
 838
 839                         /* If there is a specified transport, use it.
 840                          * Otherwise, we want to use the active path.
 841                          */
 842                         new_transport = chunk->transport;
 843                         if (!new_transport || !new_transport->active)
 844                                 new_transport = asoc->peer.active_path;
 845
 846                         /* Change packets if necessary.  */
 847                         if (new_transport != transport) {
 848                                 transport = new_transport;
 849
 850                                 /* Schedule to have this transport's
 851                                  * packet flushed.
 852                                  */
 853                                 if (list_empty(&transport->send_ready)) {
 854                                         list_add_tail(&transport->send_ready,
 855                                                       &transport_list);
 856                                 }
 857
 858                                 packet = &transport->packet;
 859                                 sctp_packet_config(packet, vtag,
 860                                                    asoc->peer.ecn_capable);
 861                         }
 862
 863                         SCTP_DEBUG_PRINTK("sctp_outq_flush(%p, %p[%s]), ",
 864                                           q, chunk,
 865                                           chunk && chunk->chunk_hdr ?
 866                                           sctp_cname(SCTP_ST_CHUNK(
 867                                                   chunk->chunk_hdr->type))
 868                                           : "Illegal Chunk");
 869
 870                         SCTP_DEBUG_PRINTK("TX TSN 0x%x skb->head "
 871                                         "%p skb->users %d.\n",
 872                                         ntohl(chunk->subh.data_hdr->tsn),
 873                                         chunk->skb ?chunk->skb->head : NULL,
 874                                         chunk->skb ?
 875                                         atomic_read(&chunk->skb->users) : -1);
 876
 877                         /* Add the chunk to the packet.  */
 878                         status = sctp_packet_transmit_chunk(packet, chunk);
 879
 880                         switch (status) {
 881                         case SCTP_XMIT_PMTU_FULL:
 882                         case SCTP_XMIT_RWND_FULL:
 883                         case SCTP_XMIT_NAGLE_DELAY:
 884                                 /* We could not append this chunk, so put
 885                                  * the chunk back on the output queue.
 886                                  */
 887                                 SCTP_DEBUG_PRINTK("sctp_outq_flush: could "
 888                                         "not transmit TSN: 0x%x, status: %d\n",
 889                                         ntohl(chunk->subh.data_hdr->tsn),
 890                                         status);
 891                                 sctp_outq_head_data(q, chunk);
 892                                 goto sctp_flush_out;
 893                                 break;
 894
 895                         case SCTP_XMIT_OK:
 896                                 break;
 897
 898                         default:
 899                                 BUG();
 900                         }
 901
 902                         /* BUG: We assume that the sctp_packet_transmit()
 903                          * call below will succeed all the time and add the
 904                          * chunk to the transmitted list and restart the
 905                          * timers.
 906                          * It is possible that the call can fail under OOM
 907                          * conditions.
 908                          *
 909                          * Is this really a problem?  Won't this behave
 910                          * like a lost TSN?
 911                          */
 912                         list_add_tail(&chunk->transmitted_list,
 913                                       &transport->transmitted);
 914
 915                         sctp_transport_reset_timers(transport);
 916
 917                         q->empty = 0;
 918
 919                         /* Only let one DATA chunk get bundled with a
 920                          * COOKIE-ECHO chunk.
 921                          */
 922                         if (packet->has_cookie_echo)
 923                                 goto sctp_flush_out;
 924                 }
 925                 break;
 926
 927         default:
 928                 /* Do nothing.  */
 929                 break;
 930         }
 931
 932 sctp_flush_out:
 933
 934         /* Before returning, examine all the transports touched in
 935          * this call.  Right now, we bluntly force clear all the
 936          * transports.  Things might change after we implement Nagle.
 937          * But such an examination is still required.
 938          *
 939          * --xguo
 940          */
 941         while ((ltransport = sctp_list_dequeue(&transport_list)) != NULL ) {
 942                 struct sctp_transport *t = list_entry(ltransport,
 943                                                       struct sctp_transport,
 944                                                       send_ready);
 945                 packet = &t->packet;
 946                 if (!sctp_packet_empty(packet))
 947                         error = sctp_packet_transmit(packet);
 948         }
 949
 950         return error;
 951 }
 952
 953 /* Update unack_data based on the incoming SACK chunk */
 954 static void sctp_sack_update_unack_data(struct sctp_association *assoc,
 955                                         struct sctp_sackhdr *sack)
 956 {
 957         sctp_sack_variable_t *frags;
 958         __u16 unack_data;
 959         int i;
 960
 961         unack_data = assoc->next_tsn - assoc->ctsn_ack_point - 1;
 962
 963         frags = sack->variable;
 964         for (i = 0; i < ntohs(sack->num_gap_ack_blocks); i++) {
 965                 unack_data -= ((ntohs(frags[i].gab.end) -
 966                                 ntohs(frags[i].gab.start) + 1));
 967         }
 968
 969         assoc->unack_data = unack_data;
 970 }
 971
 972 /* Return the highest new tsn that is acknowledged by the given SACK chunk. */
 973 static __u32 sctp_highest_new_tsn(struct sctp_sackhdr *sack,
 974                                   struct sctp_association *asoc)
 975 {
 976         struct list_head *ltransport, *lchunk;
 977         struct sctp_transport *transport;
 978         struct sctp_chunk *chunk;
 979         __u32 highest_new_tsn, tsn;
 980         struct list_head *transport_list = &asoc->peer.transport_addr_list;
 981
 982         highest_new_tsn = ntohl(sack->cum_tsn_ack);
 983
 984         list_for_each(ltransport, transport_list) {
 985                 transport = list_entry(ltransport, struct sctp_transport,
 986                                        transports);
 987                 list_for_each(lchunk, &transport->transmitted) {
 988                         chunk = list_entry(lchunk, struct sctp_chunk,
 989                                            transmitted_list);
 990                         tsn = ntohl(chunk->subh.data_hdr->tsn);
 991
 992                         if (!chunk->tsn_gap_acked &&
 993                             TSN_lt(highest_new_tsn, tsn) &&
 994                             sctp_acked(sack, tsn))
 995                                 highest_new_tsn = tsn;
 996                 }
 997         }
 998
 999         return highest_new_tsn;
1000 }
1001
1002 /* This is where we REALLY process a SACK.
1003  *
1004  * Process the SACK against the outqueue.  Mostly, this just frees
1005  * things off the transmitted queue.
1006  */
1007 int sctp_outq_sack(struct sctp_outq *q, struct sctp_sackhdr *sack)
1008 {
1009         struct sctp_association *asoc = q->asoc;
1010         struct sctp_transport *transport;
1011         struct sctp_chunk *tchunk = NULL;
1012         struct list_head *lchunk, *transport_list, *pos, *temp;
1013         sctp_sack_variable_t *frags = sack->variable;
1014         __u32 sack_ctsn, ctsn, tsn;
1015         __u32 highest_tsn, highest_new_tsn;
1016         __u32 sack_a_rwnd;
1017         unsigned outstanding;
1018         struct sctp_transport *primary = asoc->peer.primary_path;
1019         int count_of_newacks = 0;
1020
1021         /* Grab the association's destination address list. */
1022         transport_list = &asoc->peer.transport_addr_list;
1023
1024         sack_ctsn = ntohl(sack->cum_tsn_ack);
1025
1026         /*
1027          * SFR-CACC algorithm:
1028          * On receipt of a SACK the sender SHOULD execute the
1029          * following statements.
1030          *
1031          * 1) If the cumulative ack in the SACK passes next tsn_at_change
1032          * on the current primary, the CHANGEOVER_ACTIVE flag SHOULD be
1033          * cleared. The CYCLING_CHANGEOVER flag SHOULD also be cleared for
1034          * all destinations.
1035          */
1036         if (TSN_lte(primary->cacc.next_tsn_at_change, sack_ctsn)) {
1037                 primary->cacc.changeover_active = 0;
1038                 list_for_each(pos, transport_list) {
1039                         transport = list_entry(pos, struct sctp_transport,
1040                                         transports);
1041                         transport->cacc.cycling_changeover = 0;
1042                 }
1043         }
1044
1045         /*
1046          * SFR-CACC algorithm:
1047          * 2) If the SACK contains gap acks and the flag CHANGEOVER_ACTIVE
1048          * is set the receiver of the SACK MUST take the following actions:
1049          *
1050          * A) Initialize the cacc_saw_newack to 0 for all destination
1051          * addresses.
1052          */
1053         if (sack->num_gap_ack_blocks > 0 &&
1054             primary->cacc.changeover_active) {
1055                 list_for_each(pos, transport_list) {
1056                         transport = list_entry(pos, struct sctp_transport,
1057                                         transports);
1058                         transport->cacc.cacc_saw_newack = 0;
1059                 }
1060         }
1061
1062         /* Get the highest TSN in the sack. */
1063         highest_tsn = sack_ctsn;
1064         if (sack->num_gap_ack_blocks)
1065                 highest_tsn +=
1066                     ntohs(frags[ntohs(sack->num_gap_ack_blocks) - 1].gab.end);
1067
1068         if (TSN_lt(asoc->highest_sacked, highest_tsn)) {
1069                 highest_new_tsn = highest_tsn;
1070                 asoc->highest_sacked = highest_tsn;
1071         } else {
1072                 highest_new_tsn = sctp_highest_new_tsn(sack, asoc);
1073         }
1074
1075         /* Run through the retransmit queue.  Credit bytes received
1076          * and free those chunks that we can.
1077          */
1078         sctp_check_transmitted(q, &q->retransmit, NULL, sack, highest_new_tsn);
1079         sctp_mark_missing(q, &q->retransmit, NULL, highest_new_tsn, 0);
1080
1081         /* Run through the transmitted queue.
1082          * Credit bytes received and free those chunks which we can.
1083          *
1084          * This is a MASSIVE candidate for optimization.
1085          */
1086         list_for_each(pos, transport_list) {
1087                 transport  = list_entry(pos, struct sctp_transport,
1088                                         transports);
1089                 sctp_check_transmitted(q, &transport->transmitted,
1090                                        transport, sack, highest_new_tsn);
1091                 /*
1092                  * SFR-CACC algorithm:
1093                  * C) Let count_of_newacks be the number of
1094                  * destinations for which cacc_saw_newack is set.
1095                  */
1096                 if (transport->cacc.cacc_saw_newack)
1097                         count_of_newacks ++;
1098         }
1099
1100         list_for_each(pos, transport_list) {
1101                 transport  = list_entry(pos, struct sctp_transport,
1102                                         transports);
1103                 sctp_mark_missing(q, &transport->transmitted, transport,
1104                                   highest_new_tsn, count_of_newacks);
1105         }
1106
1107         /* Move the Cumulative TSN Ack Point if appropriate.  */
1108         if (TSN_lt(asoc->ctsn_ack_point, sack_ctsn))
1109                 asoc->ctsn_ack_point = sack_ctsn;
1110
1111         /* Update unack_data field in the assoc. */
1112         sctp_sack_update_unack_data(asoc, sack);
1113
1114         ctsn = asoc->ctsn_ack_point;
1115
1116         /* Throw away stuff rotting on the sack queue.  */
1117         list_for_each_safe(lchunk, temp, &q->sacked) {
1118                 tchunk = list_entry(lchunk, struct sctp_chunk,
1119                                     transmitted_list);
1120                 tsn = ntohl(tchunk->subh.data_hdr->tsn);
1121                 if (TSN_lte(tsn, ctsn))
1122                         sctp_chunk_free(tchunk);
1123         }
1124
1125         /* ii) Set rwnd equal to the newly received a_rwnd minus the
1126          *     number of bytes still outstanding after processing the
1127          *     Cumulative TSN Ack and the Gap Ack Blocks.
1128          */
1129
1130         sack_a_rwnd = ntohl(sack->a_rwnd);
1131         outstanding = q->outstanding_bytes;
1132
1133         if (outstanding < sack_a_rwnd)
1134                 sack_a_rwnd -= outstanding;
1135         else
1136                 sack_a_rwnd = 0;
1137
1138         asoc->peer.rwnd = sack_a_rwnd;
1139
1140         sctp_generate_fwdtsn(q, sack_ctsn);
1141
1142         SCTP_DEBUG_PRINTK("%s: sack Cumulative TSN Ack is 0x%x.\n",
1143                           __FUNCTION__, sack_ctsn);
1144         SCTP_DEBUG_PRINTK("%s: Cumulative TSN Ack of association, "
1145                           "%p is 0x%x. Adv peer ack point: 0x%x\n",
1146                           __FUNCTION__, asoc, ctsn, asoc->adv_peer_ack_point);
1147
1148         /* See if all chunks are acked.
1149          * Make sure the empty queue handler will get run later.
1150          */
1151         q->empty = skb_queue_empty(&q->out) && skb_queue_empty(&q->control) &&
1152                         list_empty(&q->retransmit);
1153         if (!q->empty)
1154                 goto finish;
1155
1156         list_for_each(pos, transport_list) {
1157                 transport  = list_entry(pos, struct sctp_transport,
1158                                         transports);
1159                 q->empty = q->empty && list_empty(&transport->transmitted);
1160                 if (!q->empty)
1161                         goto finish;
1162         }
1163
1164         SCTP_DEBUG_PRINTK("sack queue is empty.\n");
1165 finish:
1166         return q->empty;
1167 }
1168
1169 /* Is the outqueue empty?  */
1170 int sctp_outq_is_empty(const struct sctp_outq *q)
1171 {
1172         return q->empty;
1173 }
1174
1175 /********************************************************************
1176  * 2nd Level Abstractions
1177  ********************************************************************/
1178
1179 /* Go through a transport's transmitted list or the association's retransmit
1180  * list and move chunks that are acked by the Cumulative TSN Ack to q->sacked.
1181  * The retransmit list will not have an associated transport.
1182  *
1183  * I added coherent debug information output.   --xguo
1184  *
1185  * Instead of printing 'sacked' or 'kept' for each TSN on the
1186  * transmitted_queue, we print a range: SACKED: TSN1-TSN2, TSN3, TSN4-TSN5.
1187  * KEPT TSN6-TSN7, etc.
1188  */
1189 static void sctp_check_transmitted(struct sctp_outq *q,
1190                                    struct list_head *transmitted_queue,
1191                                    struct sctp_transport *transport,
1192                                    struct sctp_sackhdr *sack,
1193                                    __u32 highest_new_tsn_in_sack)
1194 {
1195         struct list_head *lchunk;
1196         struct sctp_chunk *tchunk;
1197         struct list_head tlist;
1198         __u32 tsn;
1199         __u32 sack_ctsn;
1200         __u32 rtt;
1201         __u8 restart_timer = 0;
1202         int bytes_acked = 0;
1203
1204         /* These state variables are for coherent debug output. --xguo */
1205
1206 #if SCTP_DEBUG
1207         __u32 dbg_ack_tsn = 0;  /* An ACKed TSN range starts here... */
1208         __u32 dbg_last_ack_tsn = 0;  /* ...and finishes here.        */
1209         __u32 dbg_kept_tsn = 0; /* An un-ACKed range starts here...  */
1210         __u32 dbg_last_kept_tsn = 0; /* ...and finishes here.        */
1211
1212         /* 0 : The last TSN was ACKed.
1213          * 1 : The last TSN was NOT ACKed (i.e. KEPT).
1214          * -1: We need to initialize.
1215          */
1216         int dbg_prt_state = -1;
1217 #endif /* SCTP_DEBUG */
1218
1219         sack_ctsn = ntohl(sack->cum_tsn_ack);
1220
1221         INIT_LIST_HEAD(&tlist);
1222
1223         /* The while loop will skip empty transmitted queues. */
1224         while (NULL != (lchunk = sctp_list_dequeue(transmitted_queue))) {
1225                 tchunk = list_entry(lchunk, struct sctp_chunk,
1226                                     transmitted_list);
1227
1228                 if (sctp_chunk_abandoned(tchunk)) {
1229                         /* Move the chunk to abandoned list. */
1230                         sctp_insert_list(&q->abandoned, lchunk);
1231                         continue;
1232                 }
1233
1234                 tsn = ntohl(tchunk->subh.data_hdr->tsn);
1235                 if (sctp_acked(sack, tsn)) {
1236                         /* If this queue is the retransmit queue, the
1237                          * retransmit timer has already reclaimed
1238                          * the outstanding bytes for this chunk, so only
1239                          * count bytes associated with a transport.
1240                          */
1241                         if (transport) {
1242                                 /* If this chunk is being used for RTT
1243                                  * measurement, calculate the RTT and update
1244                                  * the RTO using this value.
1245                                  *
1246                                  * 6.3.1 C5) Karn's algorithm: RTT measurements
1247                                  * MUST NOT be made using packets that were
1248                                  * retransmitted (and thus for which it is
1249                                  * ambiguous whether the reply was for the
1250                                  * first instance of the packet or a later
1251                                  * instance).
1252                                  */
1253                                 if (!tchunk->tsn_gap_acked &&
1254                                     !tchunk->resent &&
1255                                     tchunk->rtt_in_progress) {
1256                                         rtt = jiffies - tchunk->sent_at;
1257                                         sctp_transport_update_rto(transport,
1258                                                                   rtt);
1259                                 }
1260                         }
1261                         if (TSN_lte(tsn, sack_ctsn)) {
1262                                 /* RFC 2960  6.3.2 Retransmission Timer Rules
1263                                  *
1264                                  * R3) Whenever a SACK is received
1265                                  * that acknowledges the DATA chunk
1266                                  * with the earliest outstanding TSN
1267                                  * for that address, restart T3-rtx
1268                                  * timer for that address with its
1269                                  * current RTO.
1270                                  */
1271                                 restart_timer = 1;
1272
1273                                 if (!tchunk->tsn_gap_acked) {
1274                                         tchunk->tsn_gap_acked = 1;
1275                                         bytes_acked += sctp_data_size(tchunk);
1276                                         /*
1277                                          * SFR-CACC algorithm:
1278                                          * 2) If the SACK contains gap acks
1279                                          * and the flag CHANGEOVER_ACTIVE is
1280                                          * set the receiver of the SACK MUST
1281                                          * take the following action:
1282                                          *
1283                                          * B) For each TSN t being acked that
1284                                          * has not been acked in any SACK so
1285                                          * far, set cacc_saw_newack to 1 for
1286                                          * the destination that the TSN was
1287                                          * sent to.
1288                                          */
1289                                         if (transport &&
1290                                             sack->num_gap_ack_blocks &&
1291                                             q->asoc->peer.primary_path->cacc.
1292                                             changeover_active)
1293                                                 transport->cacc.cacc_saw_newack
1294                                                         = 1;
1295                                 }
1296
1297                                 list_add_tail(&tchunk->transmitted_list,
1298                                               &q->sacked);
1299                         } else {
1300                                 /* RFC2960 7.2.4, sctpimpguide-05 2.8.2
1301                                  * M2) Each time a SACK arrives reporting
1302                                  * 'Stray DATA chunk(s)' record the highest TSN
1303                                  * reported as newly acknowledged, call this
1304                                  * value 'HighestTSNinSack'. A newly
1305                                  * acknowledged DATA chunk is one not
1306                                  * previously acknowledged in a SACK.
1307                                  *
1308                                  * When the SCTP sender of data receives a SACK
1309                                  * chunk that acknowledges, for the first time,
1310                                  * the receipt of a DATA chunk, all the still
1311                                  * unacknowledged DATA chunks whose TSN is
1312                                  * older than that newly acknowledged DATA
1313                                  * chunk, are qualified as 'Stray DATA chunks'.
1314                                  */
1315                                 if (!tchunk->tsn_gap_acked) {
1316                                         tchunk->tsn_gap_acked = 1;
1317                                         bytes_acked += sctp_data_size(tchunk);
1318                                 }
1319                                 list_add_tail(lchunk, &tlist);
1320                         }
1321
1322 #if SCTP_DEBUG
1323                         switch (dbg_prt_state) {
1324                         case 0: /* last TSN was ACKed */
1325                                 if (dbg_last_ack_tsn + 1 == tsn) {
1326                                         /* This TSN belongs to the
1327                                          * current ACK range.
1328                                          */
1329                                         break;
1330                                 }
1331
1332                                 if (dbg_last_ack_tsn != dbg_ack_tsn) {
1333                                         /* Display the end of the
1334                                          * current range.
1335                                          */
1336                                         SCTP_DEBUG_PRINTK("-%08x",
1337                                                           dbg_last_ack_tsn);
1338                                 }
1339
1340                                 /* Start a new range.  */
1341                                 SCTP_DEBUG_PRINTK(",%08x", tsn);
1342                                 dbg_ack_tsn = tsn;
1343                                 break;
1344
1345                         case 1: /* The last TSN was NOT ACKed. */
1346                                 if (dbg_last_kept_tsn != dbg_kept_tsn) {
1347                                         /* Display the end of current range. */
1348                                         SCTP_DEBUG_PRINTK("-%08x",
1349                                                           dbg_last_kept_tsn);
1350                                 }
1351
1352                                 SCTP_DEBUG_PRINTK("\n");
1353
1354                                 /* FALL THROUGH... */
1355                         default:
1356                                 /* This is the first-ever TSN we examined.  */
1357                                 /* Start a new range of ACK-ed TSNs.  */
1358                                 SCTP_DEBUG_PRINTK("ACKed: %08x", tsn);
1359                                 dbg_prt_state = 0;
1360                                 dbg_ack_tsn = tsn;
1361                         };
1362
1363                         dbg_last_ack_tsn = tsn;
1364 #endif /* SCTP_DEBUG */
1365
1366                 } else {
1367                         if (tchunk->tsn_gap_acked) {
1368                                 SCTP_DEBUG_PRINTK("%s: Receiver reneged on "
1369                                                   "data TSN: 0x%x\n",
1370                                                   __FUNCTION__,
1371                                                   tsn);
1372                                 tchunk->tsn_gap_acked = 0;
1373
1374                                 bytes_acked -= sctp_data_size(tchunk);
1375
1376                                 /* RFC 2960 6.3.2 Retransmission Timer Rules
1377                                  *
1378                                  * R4) Whenever a SACK is received missing a
1379                                  * TSN that was previously acknowledged via a
1380                                  * Gap Ack Block, start T3-rtx for the
1381                                  * destination address to which the DATA
1382                                  * chunk was originally
1383                                  * transmitted if it is not already running.
1384                                  */
1385                                 restart_timer = 1;
1386                         }
1387
1388                         list_add_tail(lchunk, &tlist);
1389
1390 #if SCTP_DEBUG
1391                         /* See the above comments on ACK-ed TSNs. */
1392                         switch (dbg_prt_state) {
1393                         case 1:
1394                                 if (dbg_last_kept_tsn + 1 == tsn)
1395                                         break;
1396
1397                                 if (dbg_last_kept_tsn != dbg_kept_tsn)
1398                                         SCTP_DEBUG_PRINTK("-%08x",
1399                                                           dbg_last_kept_tsn);
1400
1401                                 SCTP_DEBUG_PRINTK(",%08x", tsn);
1402                                 dbg_kept_tsn = tsn;
1403                                 break;
1404
1405                         case 0:
1406                                 if (dbg_last_ack_tsn != dbg_ack_tsn)
1407                                         SCTP_DEBUG_PRINTK("-%08x",
1408                                                           dbg_last_ack_tsn);
1409                                 SCTP_DEBUG_PRINTK("\n");
1410
1411                                 /* FALL THROUGH... */
1412                         default:
1413                                 SCTP_DEBUG_PRINTK("KEPT: %08x",tsn);
1414                                 dbg_prt_state = 1;
1415                                 dbg_kept_tsn = tsn;
1416                         };
1417
1418                         dbg_last_kept_tsn = tsn;
1419 #endif /* SCTP_DEBUG */
1420                 }
1421         }
1422
1423 #if SCTP_DEBUG
1424         /* Finish off the last range, displaying its ending TSN.  */
1425         switch (dbg_prt_state) {
1426         case 0:
1427                 if (dbg_last_ack_tsn != dbg_ack_tsn) {
1428                         SCTP_DEBUG_PRINTK("-%08x\n", dbg_last_ack_tsn);
1429                 } else {
1430                         SCTP_DEBUG_PRINTK("\n");
1431                 }
1432         break;
1433
1434         case 1:
1435                 if (dbg_last_kept_tsn != dbg_kept_tsn) {
1436                         SCTP_DEBUG_PRINTK("-%08x\n", dbg_last_kept_tsn);
1437                 } else {
1438                         SCTP_DEBUG_PRINTK("\n");
1439                 }
1440         };
1441 #endif /* SCTP_DEBUG */
1442         if (transport) {
1443                 if (bytes_acked) {
1444                         /* 8.2. When an outstanding TSN is acknowledged,
1445                          * the endpoint shall clear the error counter of
1446                          * the destination transport address to which the
1447                          * DATA chunk was last sent.
1448                          * The association's overall error counter is
1449                          * also cleared.
1450                          */
1451                         transport->error_count = 0;
1452                         transport->asoc->overall_error_count = 0;
1453
1454                         /* Mark the destination transport address as
1455                          * active if it is not so marked.
1456                          */
1457                         if (!transport->active) {
1458                                 sctp_assoc_control_transport(
1459                                         transport->asoc,
1460                                         transport,
1461                                         SCTP_TRANSPORT_UP,
1462                                         SCTP_RECEIVED_SACK);
1463                         }
1464
1465                         sctp_transport_raise_cwnd(transport, sack_ctsn,
1466                                                   bytes_acked);
1467
1468                         transport->flight_size -= bytes_acked;
1469                         q->outstanding_bytes -= bytes_acked;
1470                 } else {
1471                         /* RFC 2960 6.1, sctpimpguide-06 2.15.2
1472                          * When a sender is doing zero window probing, it
1473                          * should not timeout the association if it continues
1474                          * to receive new packets from the receiver. The
1475                          * reason is that the receiver MAY keep its window
1476                          * closed for an indefinite time.
1477                          * A sender is doing zero window probing when the
1478                          * receiver's advertised window is zero, and there is
1479                          * only one data chunk in flight to the receiver.
1480                          */
1481                         if (!q->asoc->peer.rwnd &&
1482                             !list_empty(&tlist) &&
1483                             (sack_ctsn+2 == q->asoc->next_tsn)) {
1484                                 SCTP_DEBUG_PRINTK("%s: SACK received for zero "
1485                                                   "window probe: %u\n",
1486                                                   __FUNCTION__, sack_ctsn);
1487                                 q->asoc->overall_error_count = 0;
1488                                 transport->error_count = 0;
1489                         }
1490                 }
1491
1492                 /* RFC 2960 6.3.2 Retransmission Timer Rules
1493                  *
1494                  * R2) Whenever all outstanding data sent to an address have
1495                  * been acknowledged, turn off the T3-rtx timer of that
1496                  * address.
1497                  */
1498                 if (!transport->flight_size) {
1499                         if (timer_pending(&transport->T3_rtx_timer) &&
1500                             del_timer(&transport->T3_rtx_timer)) {
1501                                 sctp_transport_put(transport);
1502                         }
1503                 } else if (restart_timer) {
1504                         if (!mod_timer(&transport->T3_rtx_timer,
1505                                        jiffies + transport->rto))
1506                                 sctp_transport_hold(transport);
1507                 }
1508         }
1509
1510         list_splice(&tlist, transmitted_queue);
1511 }
1512
1513 /* Mark chunks as missing and consequently may get retransmitted. */
1514 static void sctp_mark_missing(struct sctp_outq *q,
1515                               struct list_head *transmitted_queue,
1516                               struct sctp_transport *transport,
1517                               __u32 highest_new_tsn_in_sack,
1518                               int count_of_newacks)
1519 {
1520         struct sctp_chunk *chunk;
1521         struct list_head *pos;
1522         __u32 tsn;
1523         char do_fast_retransmit = 0;
1524         struct sctp_transport *primary = q->asoc->peer.primary_path;
1525
1526         list_for_each(pos, transmitted_queue) {
1527
1528                 chunk = list_entry(pos, struct sctp_chunk, transmitted_list);
1529                 tsn = ntohl(chunk->subh.data_hdr->tsn);
1530
1531                 /* RFC 2960 7.2.4, sctpimpguide-05 2.8.2 M3) Examine all
1532                  * 'Unacknowledged TSN's', if the TSN number of an
1533                  * 'Unacknowledged TSN' is smaller than the 'HighestTSNinSack'
1534                  * value, increment the 'TSN.Missing.Report' count on that
1535                  * chunk if it has NOT been fast retransmitted or marked for
1536                  * fast retransmit already.
1537                  */
1538                 if (!chunk->fast_retransmit &&
1539                     !chunk->tsn_gap_acked &&
1540                     TSN_lt(tsn, highest_new_tsn_in_sack)) {
1541
1542                         /* SFR-CACC may require us to skip marking
1543                          * this chunk as missing.
1544                          */
1545                         if (!transport || !sctp_cacc_skip(primary, transport,
1546                                             count_of_newacks, tsn)) {
1547                                 chunk->tsn_missing_report++;
1548
1549                                 SCTP_DEBUG_PRINTK(
1550                                         "%s: TSN 0x%x missing counter: %d\n",
1551                                         __FUNCTION__, tsn,
1552                                         chunk->tsn_missing_report);
1553                         }
1554                 }
1555                 /*
1556                  * M4) If any DATA chunk is found to have a
1557                  * 'TSN.Missing.Report'
1558                  * value larger than or equal to 4, mark that chunk for
1559                  * retransmission and start the fast retransmit procedure.
1560                  */
1561
1562                 if (chunk->tsn_missing_report >= 4) {
1563                         chunk->fast_retransmit = 1;
1564                         do_fast_retransmit = 1;
1565                 }
1566         }
1567
1568         if (transport) {
1569                 if (do_fast_retransmit)
1570                         sctp_retransmit(q, transport, SCTP_RTXR_FAST_RTX);
1571
1572                 SCTP_DEBUG_PRINTK("%s: transport: %p, cwnd: %d, "
1573                                   "ssthresh: %d, flight_size: %d, pba: %d\n",
1574                                   __FUNCTION__, transport, transport->cwnd,
1575                                   transport->ssthresh, transport->flight_size,
1576                                   transport->partial_bytes_acked);
1577         }
1578 }
1579
1580 /* Is the given TSN acked by this packet?  */
1581 static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn)
1582 {
1583         int i;
1584         sctp_sack_variable_t *frags;
1585         __u16 gap;
1586         __u32 ctsn = ntohl(sack->cum_tsn_ack);
1587
1588         if (TSN_lte(tsn, ctsn))
1589                 goto pass;
1590
1591         /* 3.3.4 Selective Acknowledgement (SACK) (3):
1592          *
1593          * Gap Ack Blocks:
1594          *  These fields contain the Gap Ack Blocks. They are repeated
1595          *  for each Gap Ack Block up to the number of Gap Ack Blocks
1596          *  defined in the Number of Gap Ack Blocks field. All DATA
1597          *  chunks with TSNs greater than or equal to (Cumulative TSN
1598          *  Ack + Gap Ack Block Start) and less than or equal to
1599          *  (Cumulative TSN Ack + Gap Ack Block End) of each Gap Ack
1600          *  Block are assumed to have been received correctly.
1601          */
1602
1603         frags = sack->variable;
1604         gap = tsn - ctsn;
1605         for (i = 0; i < ntohs(sack->num_gap_ack_blocks); ++i) {
1606                 if (TSN_lte(ntohs(frags[i].gab.start), gap) &&
1607                     TSN_lte(gap, ntohs(frags[i].gab.end)))
1608                         goto pass;
1609         }
1610
1611         return 0;
1612 pass:
1613         return 1;
1614 }
1615
1616 static inline int sctp_get_skip_pos(struct sctp_fwdtsn_skip *skiplist,
1617                                     int nskips, __u16 stream)
1618 {
1619         int i;
1620
1621         for (i = 0; i < nskips; i++) {
1622                 if (skiplist[i].stream == stream)
1623                         return i;
1624         }
1625         return i;
1626 }
1627
1628 /* Create and add a fwdtsn chunk to the outq's control queue if needed. */
1629 static void sctp_generate_fwdtsn(struct sctp_outq *q, __u32 ctsn)
1630 {
1631         struct sctp_association *asoc = q->asoc;
1632         struct sctp_chunk *ftsn_chunk = NULL;
1633         struct sctp_fwdtsn_skip ftsn_skip_arr[10];
1634         int nskips = 0;
1635         int skip_pos = 0;
1636         __u32 tsn;
1637         struct sctp_chunk *chunk;
1638         struct list_head *lchunk, *temp;
1639
1640         /* PR-SCTP C1) Let SackCumAck be the Cumulative TSN ACK carried in the
1641          * received SACK.
1642          *
1643          * If (Advanced.Peer.Ack.Point < SackCumAck), then update
1644          * Advanced.Peer.Ack.Point to be equal to SackCumAck.
1645          */
1646         if (TSN_lt(asoc->adv_peer_ack_point, ctsn))
1647                 asoc->adv_peer_ack_point = ctsn;
1648
1649         /* PR-SCTP C2) Try to further advance the "Advanced.Peer.Ack.Point"
1650          * locally, that is, to move "Advanced.Peer.Ack.Point" up as long as
1651          * the chunk next in the out-queue space is marked as "abandoned" as
1652          * shown in the following example:
1653          *
1654          * Assuming that a SACK arrived with the Cumulative TSN ACK 102
1655          * and the Advanced.Peer.Ack.Point is updated to this value:
1656          *
1657          *   out-queue at the end of  ==>   out-queue after Adv.Ack.Point
1658          *   normal SACK processing           local advancement
1659          *                ...                           ...
1660          *   Adv.Ack.Pt-> 102 acked                     102 acked
1661          *                103 abandoned                 103 abandoned
1662          *                104 abandoned     Adv.Ack.P-> 104 abandoned
1663          *                105                           105
1664          *                106 acked                     106 acked
1665          *                ...                           ...
1666          *
1667          * In this example, the data sender successfully advanced the
1668          * "Advanced.Peer.Ack.Point" from 102 to 104 locally.
1669          */
1670         list_for_each_safe(lchunk, temp, &q->abandoned) {
1671                 chunk = list_entry(lchunk, struct sctp_chunk,
1672                                         transmitted_list);
1673                 tsn = ntohl(chunk->subh.data_hdr->tsn);
1674
1675                 /* Remove any chunks in the abandoned queue that are acked by
1676                  * the ctsn.
1677                  */
1678                 if (TSN_lte(tsn, ctsn)) {
1679                         list_del_init(lchunk);
1680                         if (!chunk->tsn_gap_acked) {
1681                         chunk->transport->flight_size -=
1682                                                  sctp_data_size(chunk);
1683                         q->outstanding_bytes -= sctp_data_size(chunk);
1684                         }
1685                         sctp_chunk_free(chunk);
1686                 } else {
1687                         if (TSN_lte(tsn, asoc->adv_peer_ack_point+1)) {
1688                                 asoc->adv_peer_ack_point = tsn;
1689                                 if (chunk->chunk_hdr->flags &
1690                                          SCTP_DATA_UNORDERED)
1691                                         continue;
1692                                 skip_pos = sctp_get_skip_pos(&ftsn_skip_arr[0],
1693                                                 nskips,
1694                                                 chunk->subh.data_hdr->stream);
1695                                 ftsn_skip_arr[skip_pos].stream =
1696                                         chunk->subh.data_hdr->stream;
1697                                 ftsn_skip_arr[skip_pos].ssn =
1698                                          chunk->subh.data_hdr->ssn;
1699                                 if (skip_pos == nskips)
1700                                         nskips++;
1701                                 if (nskips == 10)
1702                                         break;
1703                         } else
1704                                 break;
1705                 }
1706         }
1707
1708         /* PR-SCTP C3) If, after step C1 and C2, the "Advanced.Peer.Ack.Point"
1709          * is greater than the Cumulative TSN ACK carried in the received
1710          * SACK, the data sender MUST send the data receiver a FORWARD TSN
1711          * chunk containing the latest value of the
1712          * "Advanced.Peer.Ack.Point".
1713          *
1714          * C4) For each "abandoned" TSN the sender of the FORWARD TSN SHOULD
1715          * list each stream and sequence number in the forwarded TSN. This
1716          * information will enable the receiver to easily find any
1717          * stranded TSN's waiting on stream reorder queues. Each stream
1718          * SHOULD only be reported once; this means that if multiple
1719          * abandoned messages occur in the same stream then only the
1720          * highest abandoned stream sequence number is reported. If the
1721          * total size of the FORWARD TSN does NOT fit in a single MTU then
1722          * the sender of the FORWARD TSN SHOULD lower the
1723          * Advanced.Peer.Ack.Point to the last TSN that will fit in a
1724          * single MTU.
1725          */
1726         if (asoc->adv_peer_ack_point > ctsn)
1727                 ftsn_chunk = sctp_make_fwdtsn(asoc, asoc->adv_peer_ack_point,
1728                                               nskips, &ftsn_skip_arr[0]);
1729
1730         if (ftsn_chunk) {
1731                 __skb_queue_tail(&q->control, (struct sk_buff *)ftsn_chunk);
1732                 SCTP_INC_STATS(SCTP_MIB_OUTCTRLCHUNKS);
1733         }
1734 }