linux/net/sctp/outqueue.c
<<
>>
Prefs
   1/* SCTP kernel implementation
   2 * (C) Copyright IBM Corp. 2001, 2004
   3 * Copyright (c) 1999-2000 Cisco, Inc.
   4 * Copyright (c) 1999-2001 Motorola, Inc.
   5 * Copyright (c) 2001-2003 Intel Corp.
   6 *
   7 * This file is part of the SCTP kernel implementation
   8 *
   9 * These functions implement the sctp_outq class.   The outqueue handles
  10 * bundling and queueing of outgoing SCTP chunks.
  11 *
  12 * This SCTP implementation is free software;
  13 * you can redistribute it and/or modify it under the terms of
  14 * the GNU General Public License as published by
  15 * the Free Software Foundation; either version 2, or (at your option)
  16 * any later version.
  17 *
  18 * This SCTP implementation is distributed in the hope that it
  19 * will be useful, but WITHOUT ANY WARRANTY; without even the implied
  20 *                 ************************
  21 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  22 * See the GNU General Public License for more details.
  23 *
  24 * You should have received a copy of the GNU General Public License
  25 * along with GNU CC; see the file COPYING.  If not, write to
  26 * the Free Software Foundation, 59 Temple Place - Suite 330,
  27 * Boston, MA 02111-1307, USA.
  28 *
  29 * Please send any bug reports or fixes you make to the
  30 * email address(es):
  31 *    lksctp developers <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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  50
  51#include <linux/types.h>
  52#include <linux/list.h>   /* For struct list_head */
  53#include <linux/socket.h>
  54#include <linux/ip.h>
  55#include <linux/slab.h>
  56#include <net/sock.h>     /* For skb_set_owner_w */
  57
  58#include <net/sctp/sctp.h>
  59#include <net/sctp/sm.h>
  60
  61/* Declare internal functions here.  */
  62static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn);
  63static void sctp_check_transmitted(struct sctp_outq *q,
  64                                   struct list_head *transmitted_queue,
  65                                   struct sctp_transport *transport,
  66                                   union sctp_addr *saddr,
  67                                   struct sctp_sackhdr *sack,
  68                                   __u32 *highest_new_tsn);
  69
  70static void sctp_mark_missing(struct sctp_outq *q,
  71                              struct list_head *transmitted_queue,
  72                              struct sctp_transport *transport,
  73                              __u32 highest_new_tsn,
  74                              int count_of_newacks);
  75
  76static void sctp_generate_fwdtsn(struct sctp_outq *q, __u32 sack_ctsn);
  77
  78static int sctp_outq_flush(struct sctp_outq *q, int rtx_timeout);
  79
  80/* Add data to the front of the queue. */
  81static inline void sctp_outq_head_data(struct sctp_outq *q,
  82                                        struct sctp_chunk *ch)
  83{
  84        list_add(&ch->list, &q->out_chunk_list);
  85        q->out_qlen += ch->skb->len;
  86}
  87
  88/* Take data from the front of the queue. */
  89static inline struct sctp_chunk *sctp_outq_dequeue_data(struct sctp_outq *q)
  90{
  91        struct sctp_chunk *ch = NULL;
  92
  93        if (!list_empty(&q->out_chunk_list)) {
  94                struct list_head *entry = q->out_chunk_list.next;
  95
  96                ch = list_entry(entry, struct sctp_chunk, list);
  97                list_del_init(entry);
  98                q->out_qlen -= ch->skb->len;
  99        }
 100        return ch;
 101}
 102/* Add data chunk to the end of the queue. */
 103static inline void sctp_outq_tail_data(struct sctp_outq *q,
 104                                       struct sctp_chunk *ch)
 105{
 106        list_add_tail(&ch->list, &q->out_chunk_list);
 107        q->out_qlen += ch->skb->len;
 108}
 109
 110/*
 111 * SFR-CACC algorithm:
 112 * D) If count_of_newacks is greater than or equal to 2
 113 * and t was not sent to the current primary then the
 114 * sender MUST NOT increment missing report count for t.
 115 */
 116static inline int sctp_cacc_skip_3_1_d(struct sctp_transport *primary,
 117                                       struct sctp_transport *transport,
 118                                       int count_of_newacks)
 119{
 120        if (count_of_newacks >=2 && transport != primary)
 121                return 1;
 122        return 0;
 123}
 124
 125/*
 126 * SFR-CACC algorithm:
 127 * F) If count_of_newacks is less than 2, let d be the
 128 * destination to which t was sent. If cacc_saw_newack
 129 * is 0 for destination d, then the sender MUST NOT
 130 * increment missing report count for t.
 131 */
 132static inline int sctp_cacc_skip_3_1_f(struct sctp_transport *transport,
 133                                       int count_of_newacks)
 134{
 135        if (count_of_newacks < 2 &&
 136                        (transport && !transport->cacc.cacc_saw_newack))
 137                return 1;
 138        return 0;
 139}
 140
 141/*
 142 * SFR-CACC algorithm:
 143 * 3.1) If CYCLING_CHANGEOVER is 0, the sender SHOULD
 144 * execute steps C, D, F.
 145 *
 146 * C has been implemented in sctp_outq_sack
 147 */
 148static inline int sctp_cacc_skip_3_1(struct sctp_transport *primary,
 149                                     struct sctp_transport *transport,
 150                                     int count_of_newacks)
 151{
 152        if (!primary->cacc.cycling_changeover) {
 153                if (sctp_cacc_skip_3_1_d(primary, transport, count_of_newacks))
 154                        return 1;
 155                if (sctp_cacc_skip_3_1_f(transport, count_of_newacks))
 156                        return 1;
 157                return 0;
 158        }
 159        return 0;
 160}
 161
 162/*
 163 * SFR-CACC algorithm:
 164 * 3.2) Else if CYCLING_CHANGEOVER is 1, and t is less
 165 * than next_tsn_at_change of the current primary, then
 166 * the sender MUST NOT increment missing report count
 167 * for t.
 168 */
 169static inline int sctp_cacc_skip_3_2(struct sctp_transport *primary, __u32 tsn)
 170{
 171        if (primary->cacc.cycling_changeover &&
 172            TSN_lt(tsn, primary->cacc.next_tsn_at_change))
 173                return 1;
 174        return 0;
 175}
 176
 177/*
 178 * SFR-CACC algorithm:
 179 * 3) If the missing report count for TSN t is to be
 180 * incremented according to [RFC2960] and
 181 * [SCTP_STEWART-2002], and CHANGEOVER_ACTIVE is set,
 182 * then the sender MUST further execute steps 3.1 and
 183 * 3.2 to determine if the missing report count for
 184 * TSN t SHOULD NOT be incremented.
 185 *
 186 * 3.3) If 3.1 and 3.2 do not dictate that the missing
 187 * report count for t should not be incremented, then
 188 * the sender SHOULD increment missing report count for
 189 * t (according to [RFC2960] and [SCTP_STEWART_2002]).
 190 */
 191static inline int sctp_cacc_skip(struct sctp_transport *primary,
 192                                 struct sctp_transport *transport,
 193                                 int count_of_newacks,
 194                                 __u32 tsn)
 195{
 196        if (primary->cacc.changeover_active &&
 197            (sctp_cacc_skip_3_1(primary, transport, count_of_newacks) ||
 198             sctp_cacc_skip_3_2(primary, tsn)))
 199                return 1;
 200        return 0;
 201}
 202
 203/* Initialize an existing sctp_outq.  This does the boring stuff.
 204 * You still need to define handlers if you really want to DO
 205 * something with this structure...
 206 */
 207void sctp_outq_init(struct sctp_association *asoc, struct sctp_outq *q)
 208{
 209        q->asoc = asoc;
 210        INIT_LIST_HEAD(&q->out_chunk_list);
 211        INIT_LIST_HEAD(&q->control_chunk_list);
 212        INIT_LIST_HEAD(&q->retransmit);
 213        INIT_LIST_HEAD(&q->sacked);
 214        INIT_LIST_HEAD(&q->abandoned);
 215
 216        q->fast_rtx = 0;
 217        q->outstanding_bytes = 0;
 218        q->empty = 1;
 219        q->cork  = 0;
 220
 221        q->malloced = 0;
 222        q->out_qlen = 0;
 223}
 224
 225/* Free the outqueue structure and any related pending chunks.
 226 */
 227void sctp_outq_teardown(struct sctp_outq *q)
 228{
 229        struct sctp_transport *transport;
 230        struct list_head *lchunk, *temp;
 231        struct sctp_chunk *chunk, *tmp;
 232
 233        /* Throw away unacknowledged chunks. */
 234        list_for_each_entry(transport, &q->asoc->peer.transport_addr_list,
 235                        transports) {
 236                while ((lchunk = sctp_list_dequeue(&transport->transmitted)) != NULL) {
 237                        chunk = list_entry(lchunk, struct sctp_chunk,
 238                                           transmitted_list);
 239                        /* Mark as part of a failed message. */
 240                        sctp_chunk_fail(chunk, q->error);
 241                        sctp_chunk_free(chunk);
 242                }
 243        }
 244
 245        /* Throw away chunks that have been gap ACKed.  */
 246        list_for_each_safe(lchunk, temp, &q->sacked) {
 247                list_del_init(lchunk);
 248                chunk = list_entry(lchunk, struct sctp_chunk,
 249                                   transmitted_list);
 250                sctp_chunk_fail(chunk, q->error);
 251                sctp_chunk_free(chunk);
 252        }
 253
 254        /* Throw away any chunks in the retransmit queue. */
 255        list_for_each_safe(lchunk, temp, &q->retransmit) {
 256                list_del_init(lchunk);
 257                chunk = list_entry(lchunk, struct sctp_chunk,
 258                                   transmitted_list);
 259                sctp_chunk_fail(chunk, q->error);
 260                sctp_chunk_free(chunk);
 261        }
 262
 263        /* Throw away any chunks that are in the abandoned queue. */
 264        list_for_each_safe(lchunk, temp, &q->abandoned) {
 265                list_del_init(lchunk);
 266                chunk = list_entry(lchunk, struct sctp_chunk,
 267                                   transmitted_list);
 268                sctp_chunk_fail(chunk, q->error);
 269                sctp_chunk_free(chunk);
 270        }
 271
 272        /* Throw away any leftover data chunks. */
 273        while ((chunk = sctp_outq_dequeue_data(q)) != NULL) {
 274
 275                /* Mark as send failure. */
 276                sctp_chunk_fail(chunk, q->error);
 277                sctp_chunk_free(chunk);
 278        }
 279
 280        q->error = 0;
 281
 282        /* Throw away any leftover control chunks. */
 283        list_for_each_entry_safe(chunk, tmp, &q->control_chunk_list, list) {
 284                list_del_init(&chunk->list);
 285                sctp_chunk_free(chunk);
 286        }
 287}
 288
 289/* Free the outqueue structure and any related pending chunks.  */
 290void 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.  */
 301int sctp_outq_tail(struct sctp_outq *q, struct sctp_chunk *chunk)
 302{
 303        struct net *net = sock_net(q->asoc->base.sk);
 304        int error = 0;
 305
 306        SCTP_DEBUG_PRINTK("sctp_outq_tail(%p, %p[%s])\n",
 307                          q, chunk, chunk && chunk->chunk_hdr ?
 308                          sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type))
 309                          : "Illegal Chunk");
 310
 311        /* If it is data, queue it up, otherwise, send it
 312         * immediately.
 313         */
 314        if (sctp_chunk_is_data(chunk)) {
 315                /* Is it OK to queue data chunks?  */
 316                /* From 9. Termination of Association
 317                 *
 318                 * When either endpoint performs a shutdown, the
 319                 * association on each peer will stop accepting new
 320                 * data from its user and only deliver data in queue
 321                 * at the time of sending or receiving the SHUTDOWN
 322                 * chunk.
 323                 */
 324                switch (q->asoc->state) {
 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(net, SCTP_MIB_OUTUNORDERCHUNKS);
 343                        else
 344                                SCTP_INC_STATS(net, SCTP_MIB_OUTORDERCHUNKS);
 345                        q->empty = 0;
 346                        break;
 347                }
 348        } else {
 349                list_add_tail(&chunk->list, &q->control_chunk_list);
 350                SCTP_INC_STATS(net, 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 */
 365static 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.  */
 389void sctp_retransmit_mark(struct sctp_outq *q,
 390                          struct sctp_transport *transport,
 391                          __u8 reason)
 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
 406                        /* If this chunk has not been previousely acked,
 407                         * stop considering it 'outstanding'.  Our peer
 408                         * will most likely never see it since it will
 409                         * not be retransmitted
 410                         */
 411                        if (!chunk->tsn_gap_acked) {
 412                                if (chunk->transport)
 413                                        chunk->transport->flight_size -=
 414                                                        sctp_data_size(chunk);
 415                                q->outstanding_bytes -= sctp_data_size(chunk);
 416                                q->asoc->peer.rwnd += sctp_data_size(chunk);
 417                        }
 418                        continue;
 419                }
 420
 421                /* If we are doing  retransmission due to a timeout or pmtu
 422                 * discovery, only the  chunks that are not yet acked should
 423                 * be added to the retransmit queue.
 424                 */
 425                if ((reason == SCTP_RTXR_FAST_RTX  &&
 426                            (chunk->fast_retransmit == SCTP_NEED_FRTX)) ||
 427                    (reason != SCTP_RTXR_FAST_RTX  && !chunk->tsn_gap_acked)) {
 428                        /* RFC 2960 6.2.1 Processing a Received SACK
 429                         *
 430                         * C) Any time a DATA chunk is marked for
 431                         * retransmission (via either T3-rtx timer expiration
 432                         * (Section 6.3.3) or via fast retransmit
 433                         * (Section 7.2.4)), add the data size of those
 434                         * chunks to the rwnd.
 435                         */
 436                        q->asoc->peer.rwnd += sctp_data_size(chunk);
 437                        q->outstanding_bytes -= sctp_data_size(chunk);
 438                        if (chunk->transport)
 439                                transport->flight_size -= sctp_data_size(chunk);
 440
 441                        /* sctpimpguide-05 Section 2.8.2
 442                         * M5) If a T3-rtx timer expires, the
 443                         * 'TSN.Missing.Report' of all affected TSNs is set
 444                         * to 0.
 445                         */
 446                        chunk->tsn_missing_report = 0;
 447
 448                        /* If a chunk that is being used for RTT measurement
 449                         * has to be retransmitted, we cannot use this chunk
 450                         * anymore for RTT measurements. Reset rto_pending so
 451                         * that a new RTT measurement is started when a new
 452                         * data chunk is sent.
 453                         */
 454                        if (chunk->rtt_in_progress) {
 455                                chunk->rtt_in_progress = 0;
 456                                transport->rto_pending = 0;
 457                        }
 458
 459                        /* Move the chunk to the retransmit queue. The chunks
 460                         * on the retransmit queue are always kept in order.
 461                         */
 462                        list_del_init(lchunk);
 463                        sctp_insert_list(&q->retransmit, lchunk);
 464                }
 465        }
 466
 467        SCTP_DEBUG_PRINTK("%s: transport: %p, reason: %d, "
 468                          "cwnd: %d, ssthresh: %d, flight_size: %d, "
 469                          "pba: %d\n", __func__,
 470                          transport, reason,
 471                          transport->cwnd, transport->ssthresh,
 472                          transport->flight_size,
 473                          transport->partial_bytes_acked);
 474
 475}
 476
 477/* Mark all the eligible packets on a transport for retransmission and force
 478 * one packet out.
 479 */
 480void sctp_retransmit(struct sctp_outq *q, struct sctp_transport *transport,
 481                     sctp_retransmit_reason_t reason)
 482{
 483        struct net *net = sock_net(q->asoc->base.sk);
 484        int error = 0;
 485
 486        switch(reason) {
 487        case SCTP_RTXR_T3_RTX:
 488                SCTP_INC_STATS(net, SCTP_MIB_T3_RETRANSMITS);
 489                sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_T3_RTX);
 490                /* Update the retran path if the T3-rtx timer has expired for
 491                 * the current retran path.
 492                 */
 493                if (transport == transport->asoc->peer.retran_path)
 494                        sctp_assoc_update_retran_path(transport->asoc);
 495                transport->asoc->rtx_data_chunks +=
 496                        transport->asoc->unack_data;
 497                break;
 498        case SCTP_RTXR_FAST_RTX:
 499                SCTP_INC_STATS(net, SCTP_MIB_FAST_RETRANSMITS);
 500                sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_FAST_RTX);
 501                q->fast_rtx = 1;
 502                break;
 503        case SCTP_RTXR_PMTUD:
 504                SCTP_INC_STATS(net, SCTP_MIB_PMTUD_RETRANSMITS);
 505                break;
 506        case SCTP_RTXR_T1_RTX:
 507                SCTP_INC_STATS(net, SCTP_MIB_T1_RETRANSMITS);
 508                transport->asoc->init_retries++;
 509                break;
 510        default:
 511                BUG();
 512        }
 513
 514        sctp_retransmit_mark(q, transport, reason);
 515
 516        /* PR-SCTP A5) Any time the T3-rtx timer expires, on any destination,
 517         * the sender SHOULD try to advance the "Advanced.Peer.Ack.Point" by
 518         * following the procedures outlined in C1 - C5.
 519         */
 520        if (reason == SCTP_RTXR_T3_RTX)
 521                sctp_generate_fwdtsn(q, q->asoc->ctsn_ack_point);
 522
 523        /* Flush the queues only on timeout, since fast_rtx is only
 524         * triggered during sack processing and the queue
 525         * will be flushed at the end.
 526         */
 527        if (reason != SCTP_RTXR_FAST_RTX)
 528                error = sctp_outq_flush(q, /* rtx_timeout */ 1);
 529
 530        if (error)
 531                q->asoc->base.sk->sk_err = -error;
 532}
 533
 534/*
 535 * Transmit DATA chunks on the retransmit queue.  Upon return from
 536 * sctp_outq_flush_rtx() the packet 'pkt' may contain chunks which
 537 * need to be transmitted by the caller.
 538 * We assume that pkt->transport has already been set.
 539 *
 540 * The return value is a normal kernel error return value.
 541 */
 542static int sctp_outq_flush_rtx(struct sctp_outq *q, struct sctp_packet *pkt,
 543                               int rtx_timeout, int *start_timer)
 544{
 545        struct list_head *lqueue;
 546        struct sctp_transport *transport = pkt->transport;
 547        sctp_xmit_t status;
 548        struct sctp_chunk *chunk, *chunk1;
 549        int fast_rtx;
 550        int error = 0;
 551        int timer = 0;
 552        int done = 0;
 553
 554        lqueue = &q->retransmit;
 555        fast_rtx = q->fast_rtx;
 556
 557        /* This loop handles time-out retransmissions, fast retransmissions,
 558         * and retransmissions due to opening of whindow.
 559         *
 560         * RFC 2960 6.3.3 Handle T3-rtx Expiration
 561         *
 562         * E3) Determine how many of the earliest (i.e., lowest TSN)
 563         * outstanding DATA chunks for the address for which the
 564         * T3-rtx has expired will fit into a single packet, subject
 565         * to the MTU constraint for the path corresponding to the
 566         * destination transport address to which the retransmission
 567         * is being sent (this may be different from the address for
 568         * which the timer expires [see Section 6.4]). Call this value
 569         * K. Bundle and retransmit those K DATA chunks in a single
 570         * packet to the destination endpoint.
 571         *
 572         * [Just to be painfully clear, if we are retransmitting
 573         * because a timeout just happened, we should send only ONE
 574         * packet of retransmitted data.]
 575         *
 576         * For fast retransmissions we also send only ONE packet.  However,
 577         * if we are just flushing the queue due to open window, we'll
 578         * try to send as much as possible.
 579         */
 580        list_for_each_entry_safe(chunk, chunk1, lqueue, transmitted_list) {
 581                /* If the chunk is abandoned, move it to abandoned list. */
 582                if (sctp_chunk_abandoned(chunk)) {
 583                        list_del_init(&chunk->transmitted_list);
 584                        sctp_insert_list(&q->abandoned,
 585                                         &chunk->transmitted_list);
 586                        continue;
 587                }
 588
 589                /* Make sure that Gap Acked TSNs are not retransmitted.  A
 590                 * simple approach is just to move such TSNs out of the
 591                 * way and into a 'transmitted' queue and skip to the
 592                 * next chunk.
 593                 */
 594                if (chunk->tsn_gap_acked) {
 595                        list_move_tail(&chunk->transmitted_list,
 596                                       &transport->transmitted);
 597                        continue;
 598                }
 599
 600                /* If we are doing fast retransmit, ignore non-fast_rtransmit
 601                 * chunks
 602                 */
 603                if (fast_rtx && !chunk->fast_retransmit)
 604                        continue;
 605
 606redo:
 607                /* Attempt to append this chunk to the packet. */
 608                status = sctp_packet_append_chunk(pkt, chunk);
 609
 610                switch (status) {
 611                case SCTP_XMIT_PMTU_FULL:
 612                        if (!pkt->has_data && !pkt->has_cookie_echo) {
 613                                /* If this packet did not contain DATA then
 614                                 * retransmission did not happen, so do it
 615                                 * again.  We'll ignore the error here since
 616                                 * control chunks are already freed so there
 617                                 * is nothing we can do.
 618                                 */
 619                                sctp_packet_transmit(pkt);
 620                                goto redo;
 621                        }
 622
 623                        /* Send this packet.  */
 624                        error = sctp_packet_transmit(pkt);
 625
 626                        /* If we are retransmitting, we should only
 627                         * send a single packet.
 628                         * Otherwise, try appending this chunk again.
 629                         */
 630                        if (rtx_timeout || fast_rtx)
 631                                done = 1;
 632                        else
 633                                goto redo;
 634
 635                        /* Bundle next chunk in the next round.  */
 636                        break;
 637
 638                case SCTP_XMIT_RWND_FULL:
 639                        /* Send this packet. */
 640                        error = sctp_packet_transmit(pkt);
 641
 642                        /* Stop sending DATA as there is no more room
 643                         * at the receiver.
 644                         */
 645                        done = 1;
 646                        break;
 647
 648                case SCTP_XMIT_NAGLE_DELAY:
 649                        /* Send this packet. */
 650                        error = sctp_packet_transmit(pkt);
 651
 652                        /* Stop sending DATA because of nagle delay. */
 653                        done = 1;
 654                        break;
 655
 656                default:
 657                        /* The append was successful, so add this chunk to
 658                         * the transmitted list.
 659                         */
 660                        list_move_tail(&chunk->transmitted_list,
 661                                       &transport->transmitted);
 662
 663                        /* Mark the chunk as ineligible for fast retransmit
 664                         * after it is retransmitted.
 665                         */
 666                        if (chunk->fast_retransmit == SCTP_NEED_FRTX)
 667                                chunk->fast_retransmit = SCTP_DONT_FRTX;
 668
 669                        q->empty = 0;
 670                        break;
 671                }
 672
 673                /* Set the timer if there were no errors */
 674                if (!error && !timer)
 675                        timer = 1;
 676
 677                if (done)
 678                        break;
 679        }
 680
 681        /* If we are here due to a retransmit timeout or a fast
 682         * retransmit and if there are any chunks left in the retransmit
 683         * queue that could not fit in the PMTU sized packet, they need
 684         * to be marked as ineligible for a subsequent fast retransmit.
 685         */
 686        if (rtx_timeout || fast_rtx) {
 687                list_for_each_entry(chunk1, lqueue, transmitted_list) {
 688                        if (chunk1->fast_retransmit == SCTP_NEED_FRTX)
 689                                chunk1->fast_retransmit = SCTP_DONT_FRTX;
 690                }
 691        }
 692
 693        *start_timer = timer;
 694
 695        /* Clear fast retransmit hint */
 696        if (fast_rtx)
 697                q->fast_rtx = 0;
 698
 699        return error;
 700}
 701
 702/* Cork the outqueue so queued chunks are really queued. */
 703int sctp_outq_uncork(struct sctp_outq *q)
 704{
 705        int error = 0;
 706        if (q->cork)
 707                q->cork = 0;
 708        error = sctp_outq_flush(q, 0);
 709        return error;
 710}
 711
 712
 713/*
 714 * Try to flush an outqueue.
 715 *
 716 * Description: Send everything in q which we legally can, subject to
 717 * congestion limitations.
 718 * * Note: This function can be called from multiple contexts so appropriate
 719 * locking concerns must be made.  Today we use the sock lock to protect
 720 * this function.
 721 */
 722static int sctp_outq_flush(struct sctp_outq *q, int rtx_timeout)
 723{
 724        struct sctp_packet *packet;
 725        struct sctp_packet singleton;
 726        struct sctp_association *asoc = q->asoc;
 727        __u16 sport = asoc->base.bind_addr.port;
 728        __u16 dport = asoc->peer.port;
 729        __u32 vtag = asoc->peer.i.init_tag;
 730        struct sctp_transport *transport = NULL;
 731        struct sctp_transport *new_transport;
 732        struct sctp_chunk *chunk, *tmp;
 733        sctp_xmit_t status;
 734        int error = 0;
 735        int start_timer = 0;
 736        int one_packet = 0;
 737
 738        /* These transports have chunks to send. */
 739        struct list_head transport_list;
 740        struct list_head *ltransport;
 741
 742        INIT_LIST_HEAD(&transport_list);
 743        packet = NULL;
 744
 745        /*
 746         * 6.10 Bundling
 747         *   ...
 748         *   When bundling control chunks with DATA chunks, an
 749         *   endpoint MUST place control chunks first in the outbound
 750         *   SCTP packet.  The transmitter MUST transmit DATA chunks
 751         *   within a SCTP packet in increasing order of TSN.
 752         *   ...
 753         */
 754
 755        list_for_each_entry_safe(chunk, tmp, &q->control_chunk_list, list) {
 756                /* RFC 5061, 5.3
 757                 * F1) This means that until such time as the ASCONF
 758                 * containing the add is acknowledged, the sender MUST
 759                 * NOT use the new IP address as a source for ANY SCTP
 760                 * packet except on carrying an ASCONF Chunk.
 761                 */
 762                if (asoc->src_out_of_asoc_ok &&
 763                    chunk->chunk_hdr->type != SCTP_CID_ASCONF)
 764                        continue;
 765
 766                list_del_init(&chunk->list);
 767
 768                /* Pick the right transport to use. */
 769                new_transport = chunk->transport;
 770
 771                if (!new_transport) {
 772                        /*
 773                         * If we have a prior transport pointer, see if
 774                         * the destination address of the chunk
 775                         * matches the destination address of the
 776                         * current transport.  If not a match, then
 777                         * try to look up the transport with a given
 778                         * destination address.  We do this because
 779                         * after processing ASCONFs, we may have new
 780                         * transports created.
 781                         */
 782                        if (transport &&
 783                            sctp_cmp_addr_exact(&chunk->dest,
 784                                                &transport->ipaddr))
 785                                        new_transport = transport;
 786                        else
 787                                new_transport = sctp_assoc_lookup_paddr(asoc,
 788                                                                &chunk->dest);
 789
 790                        /* if we still don't have a new transport, then
 791                         * use the current active path.
 792                         */
 793                        if (!new_transport)
 794                                new_transport = asoc->peer.active_path;
 795                } else if ((new_transport->state == SCTP_INACTIVE) ||
 796                           (new_transport->state == SCTP_UNCONFIRMED) ||
 797                           (new_transport->state == SCTP_PF)) {
 798                        /* If the chunk is Heartbeat or Heartbeat Ack,
 799                         * send it to chunk->transport, even if it's
 800                         * inactive.
 801                         *
 802                         * 3.3.6 Heartbeat Acknowledgement:
 803                         * ...
 804                         * A HEARTBEAT ACK is always sent to the source IP
 805                         * address of the IP datagram containing the
 806                         * HEARTBEAT chunk to which this ack is responding.
 807                         * ...
 808                         *
 809                         * ASCONF_ACKs also must be sent to the source.
 810                         */
 811                        if (chunk->chunk_hdr->type != SCTP_CID_HEARTBEAT &&
 812                            chunk->chunk_hdr->type != SCTP_CID_HEARTBEAT_ACK &&
 813                            chunk->chunk_hdr->type != SCTP_CID_ASCONF_ACK)
 814                                new_transport = asoc->peer.active_path;
 815                }
 816
 817                /* Are we switching transports?
 818                 * Take care of transport locks.
 819                 */
 820                if (new_transport != transport) {
 821                        transport = new_transport;
 822                        if (list_empty(&transport->send_ready)) {
 823                                list_add_tail(&transport->send_ready,
 824                                              &transport_list);
 825                        }
 826                        packet = &transport->packet;
 827                        sctp_packet_config(packet, vtag,
 828                                           asoc->peer.ecn_capable);
 829                }
 830
 831                switch (chunk->chunk_hdr->type) {
 832                /*
 833                 * 6.10 Bundling
 834                 *   ...
 835                 *   An endpoint MUST NOT bundle INIT, INIT ACK or SHUTDOWN
 836                 *   COMPLETE with any other chunks.  [Send them immediately.]
 837                 */
 838                case SCTP_CID_INIT:
 839                case SCTP_CID_INIT_ACK:
 840                case SCTP_CID_SHUTDOWN_COMPLETE:
 841                        sctp_packet_init(&singleton, transport, sport, dport);
 842                        sctp_packet_config(&singleton, vtag, 0);
 843                        sctp_packet_append_chunk(&singleton, chunk);
 844                        error = sctp_packet_transmit(&singleton);
 845                        if (error < 0)
 846                                return error;
 847                        break;
 848
 849                case SCTP_CID_ABORT:
 850                        if (sctp_test_T_bit(chunk)) {
 851                                packet->vtag = asoc->c.my_vtag;
 852                        }
 853                /* The following chunks are "response" chunks, i.e.
 854                 * they are generated in response to something we
 855                 * received.  If we are sending these, then we can
 856                 * send only 1 packet containing these chunks.
 857                 */
 858                case SCTP_CID_HEARTBEAT_ACK:
 859                case SCTP_CID_SHUTDOWN_ACK:
 860                case SCTP_CID_COOKIE_ACK:
 861                case SCTP_CID_COOKIE_ECHO:
 862                case SCTP_CID_ERROR:
 863                case SCTP_CID_ECN_CWR:
 864                case SCTP_CID_ASCONF_ACK:
 865                        one_packet = 1;
 866                        /* Fall through */
 867
 868                case SCTP_CID_SACK:
 869                case SCTP_CID_HEARTBEAT:
 870                case SCTP_CID_SHUTDOWN:
 871                case SCTP_CID_ECN_ECNE:
 872                case SCTP_CID_ASCONF:
 873                case SCTP_CID_FWD_TSN:
 874                        status = sctp_packet_transmit_chunk(packet, chunk,
 875                                                            one_packet);
 876                        if (status  != SCTP_XMIT_OK) {
 877                                /* put the chunk back */
 878                                list_add(&chunk->list, &q->control_chunk_list);
 879                        } else if (chunk->chunk_hdr->type == SCTP_CID_FWD_TSN) {
 880                                /* PR-SCTP C5) If a FORWARD TSN is sent, the
 881                                 * sender MUST assure that at least one T3-rtx
 882                                 * timer is running.
 883                                 */
 884                                sctp_transport_reset_timers(transport);
 885                        }
 886                        break;
 887
 888                default:
 889                        /* We built a chunk with an illegal type! */
 890                        BUG();
 891                }
 892        }
 893
 894        if (q->asoc->src_out_of_asoc_ok)
 895                goto sctp_flush_out;
 896
 897        /* Is it OK to send data chunks?  */
 898        switch (asoc->state) {
 899        case SCTP_STATE_COOKIE_ECHOED:
 900                /* Only allow bundling when this packet has a COOKIE-ECHO
 901                 * chunk.
 902                 */
 903                if (!packet || !packet->has_cookie_echo)
 904                        break;
 905
 906                /* fallthru */
 907        case SCTP_STATE_ESTABLISHED:
 908        case SCTP_STATE_SHUTDOWN_PENDING:
 909        case SCTP_STATE_SHUTDOWN_RECEIVED:
 910                /*
 911                 * RFC 2960 6.1  Transmission of DATA Chunks
 912                 *
 913                 * C) When the time comes for the sender to transmit,
 914                 * before sending new DATA chunks, the sender MUST
 915                 * first transmit any outstanding DATA chunks which
 916                 * are marked for retransmission (limited by the
 917                 * current cwnd).
 918                 */
 919                if (!list_empty(&q->retransmit)) {
 920                        if (asoc->peer.retran_path->state == SCTP_UNCONFIRMED)
 921                                goto sctp_flush_out;
 922                        if (transport == asoc->peer.retran_path)
 923                                goto retran;
 924
 925                        /* Switch transports & prepare the packet.  */
 926
 927                        transport = asoc->peer.retran_path;
 928
 929                        if (list_empty(&transport->send_ready)) {
 930                                list_add_tail(&transport->send_ready,
 931                                              &transport_list);
 932                        }
 933
 934                        packet = &transport->packet;
 935                        sctp_packet_config(packet, vtag,
 936                                           asoc->peer.ecn_capable);
 937                retran:
 938                        error = sctp_outq_flush_rtx(q, packet,
 939                                                    rtx_timeout, &start_timer);
 940
 941                        if (start_timer)
 942                                sctp_transport_reset_timers(transport);
 943
 944                        /* This can happen on COOKIE-ECHO resend.  Only
 945                         * one chunk can get bundled with a COOKIE-ECHO.
 946                         */
 947                        if (packet->has_cookie_echo)
 948                                goto sctp_flush_out;
 949
 950                        /* Don't send new data if there is still data
 951                         * waiting to retransmit.
 952                         */
 953                        if (!list_empty(&q->retransmit))
 954                                goto sctp_flush_out;
 955                }
 956
 957                /* Apply Max.Burst limitation to the current transport in
 958                 * case it will be used for new data.  We are going to
 959                 * rest it before we return, but we want to apply the limit
 960                 * to the currently queued data.
 961                 */
 962                if (transport)
 963                        sctp_transport_burst_limited(transport);
 964
 965                /* Finally, transmit new packets.  */
 966                while ((chunk = sctp_outq_dequeue_data(q)) != NULL) {
 967                        /* RFC 2960 6.5 Every DATA chunk MUST carry a valid
 968                         * stream identifier.
 969                         */
 970                        if (chunk->sinfo.sinfo_stream >=
 971                            asoc->c.sinit_num_ostreams) {
 972
 973                                /* Mark as failed send. */
 974                                sctp_chunk_fail(chunk, SCTP_ERROR_INV_STRM);
 975                                sctp_chunk_free(chunk);
 976                                continue;
 977                        }
 978
 979                        /* Has this chunk expired? */
 980                        if (sctp_chunk_abandoned(chunk)) {
 981                                sctp_chunk_fail(chunk, 0);
 982                                sctp_chunk_free(chunk);
 983                                continue;
 984                        }
 985
 986                        /* If there is a specified transport, use it.
 987                         * Otherwise, we want to use the active path.
 988                         */
 989                        new_transport = chunk->transport;
 990                        if (!new_transport ||
 991                            ((new_transport->state == SCTP_INACTIVE) ||
 992                             (new_transport->state == SCTP_UNCONFIRMED) ||
 993                             (new_transport->state == SCTP_PF)))
 994                                new_transport = asoc->peer.active_path;
 995                        if (new_transport->state == SCTP_UNCONFIRMED)
 996                                continue;
 997
 998                        /* Change packets if necessary.  */
 999                        if (new_transport != transport) {
1000                                transport = new_transport;
1001
1002                                /* Schedule to have this transport's
1003                                 * packet flushed.
1004                                 */
1005                                if (list_empty(&transport->send_ready)) {
1006                                        list_add_tail(&transport->send_ready,
1007                                                      &transport_list);
1008                                }
1009
1010                                packet = &transport->packet;
1011                                sctp_packet_config(packet, vtag,
1012                                                   asoc->peer.ecn_capable);
1013                                /* We've switched transports, so apply the
1014                                 * Burst limit to the new transport.
1015                                 */
1016                                sctp_transport_burst_limited(transport);
1017                        }
1018
1019                        SCTP_DEBUG_PRINTK("sctp_outq_flush(%p, %p[%s]), ",
1020                                          q, chunk,
1021                                          chunk && chunk->chunk_hdr ?
1022                                          sctp_cname(SCTP_ST_CHUNK(
1023                                                  chunk->chunk_hdr->type))
1024                                          : "Illegal Chunk");
1025
1026                        SCTP_DEBUG_PRINTK("TX TSN 0x%x skb->head "
1027                                        "%p skb->users %d.\n",
1028                                        ntohl(chunk->subh.data_hdr->tsn),
1029                                        chunk->skb ?chunk->skb->head : NULL,
1030                                        chunk->skb ?
1031                                        atomic_read(&chunk->skb->users) : -1);
1032
1033                        /* Add the chunk to the packet.  */
1034                        status = sctp_packet_transmit_chunk(packet, chunk, 0);
1035
1036                        switch (status) {
1037                        case SCTP_XMIT_PMTU_FULL:
1038                        case SCTP_XMIT_RWND_FULL:
1039                        case SCTP_XMIT_NAGLE_DELAY:
1040                                /* We could not append this chunk, so put
1041                                 * the chunk back on the output queue.
1042                                 */
1043                                SCTP_DEBUG_PRINTK("sctp_outq_flush: could "
1044                                        "not transmit TSN: 0x%x, status: %d\n",
1045                                        ntohl(chunk->subh.data_hdr->tsn),
1046                                        status);
1047                                sctp_outq_head_data(q, chunk);
1048                                goto sctp_flush_out;
1049                                break;
1050
1051                        case SCTP_XMIT_OK:
1052                                /* The sender is in the SHUTDOWN-PENDING state,
1053                                 * The sender MAY set the I-bit in the DATA
1054                                 * chunk header.
1055                                 */
1056                                if (asoc->state == SCTP_STATE_SHUTDOWN_PENDING)
1057                                        chunk->chunk_hdr->flags |= SCTP_DATA_SACK_IMM;
1058
1059                                break;
1060
1061                        default:
1062                                BUG();
1063                        }
1064
1065                        /* BUG: We assume that the sctp_packet_transmit()
1066                         * call below will succeed all the time and add the
1067                         * chunk to the transmitted list and restart the
1068                         * timers.
1069                         * It is possible that the call can fail under OOM
1070                         * conditions.
1071                         *
1072                         * Is this really a problem?  Won't this behave
1073                         * like a lost TSN?
1074                         */
1075                        list_add_tail(&chunk->transmitted_list,
1076                                      &transport->transmitted);
1077
1078                        sctp_transport_reset_timers(transport);
1079
1080                        q->empty = 0;
1081
1082                        /* Only let one DATA chunk get bundled with a
1083                         * COOKIE-ECHO chunk.
1084                         */
1085                        if (packet->has_cookie_echo)
1086                                goto sctp_flush_out;
1087                }
1088                break;
1089
1090        default:
1091                /* Do nothing.  */
1092                break;
1093        }
1094
1095sctp_flush_out:
1096
1097        /* Before returning, examine all the transports touched in
1098         * this call.  Right now, we bluntly force clear all the
1099         * transports.  Things might change after we implement Nagle.
1100         * But such an examination is still required.
1101         *
1102         * --xguo
1103         */
1104        while ((ltransport = sctp_list_dequeue(&transport_list)) != NULL ) {
1105                struct sctp_transport *t = list_entry(ltransport,
1106                                                      struct sctp_transport,
1107                                                      send_ready);
1108                packet = &t->packet;
1109                if (!sctp_packet_empty(packet))
1110                        error = sctp_packet_transmit(packet);
1111
1112                /* Clear the burst limited state, if any */
1113                sctp_transport_burst_reset(t);
1114        }
1115
1116        return error;
1117}
1118
1119/* Update unack_data based on the incoming SACK chunk */
1120static void sctp_sack_update_unack_data(struct sctp_association *assoc,
1121                                        struct sctp_sackhdr *sack)
1122{
1123        sctp_sack_variable_t *frags;
1124        __u16 unack_data;
1125        int i;
1126
1127        unack_data = assoc->next_tsn - assoc->ctsn_ack_point - 1;
1128
1129        frags = sack->variable;
1130        for (i = 0; i < ntohs(sack->num_gap_ack_blocks); i++) {
1131                unack_data -= ((ntohs(frags[i].gab.end) -
1132                                ntohs(frags[i].gab.start) + 1));
1133        }
1134
1135        assoc->unack_data = unack_data;
1136}
1137
1138/* This is where we REALLY process a SACK.
1139 *
1140 * Process the SACK against the outqueue.  Mostly, this just frees
1141 * things off the transmitted queue.
1142 */
1143int sctp_outq_sack(struct sctp_outq *q, struct sctp_chunk *chunk)
1144{
1145        struct sctp_association *asoc = q->asoc;
1146        struct sctp_sackhdr *sack = chunk->subh.sack_hdr;
1147        struct sctp_transport *transport;
1148        struct sctp_chunk *tchunk = NULL;
1149        struct list_head *lchunk, *transport_list, *temp;
1150        sctp_sack_variable_t *frags = sack->variable;
1151        __u32 sack_ctsn, ctsn, tsn;
1152        __u32 highest_tsn, highest_new_tsn;
1153        __u32 sack_a_rwnd;
1154        unsigned int outstanding;
1155        struct sctp_transport *primary = asoc->peer.primary_path;
1156        int count_of_newacks = 0;
1157        int gap_ack_blocks;
1158        u8 accum_moved = 0;
1159
1160        /* Grab the association's destination address list. */
1161        transport_list = &asoc->peer.transport_addr_list;
1162
1163        sack_ctsn = ntohl(sack->cum_tsn_ack);
1164        gap_ack_blocks = ntohs(sack->num_gap_ack_blocks);
1165        /*
1166         * SFR-CACC algorithm:
1167         * On receipt of a SACK the sender SHOULD execute the
1168         * following statements.
1169         *
1170         * 1) If the cumulative ack in the SACK passes next tsn_at_change
1171         * on the current primary, the CHANGEOVER_ACTIVE flag SHOULD be
1172         * cleared. The CYCLING_CHANGEOVER flag SHOULD also be cleared for
1173         * all destinations.
1174         * 2) If the SACK contains gap acks and the flag CHANGEOVER_ACTIVE
1175         * is set the receiver of the SACK MUST take the following actions:
1176         *
1177         * A) Initialize the cacc_saw_newack to 0 for all destination
1178         * addresses.
1179         *
1180         * Only bother if changeover_active is set. Otherwise, this is
1181         * totally suboptimal to do on every SACK.
1182         */
1183        if (primary->cacc.changeover_active) {
1184                u8 clear_cycling = 0;
1185
1186                if (TSN_lte(primary->cacc.next_tsn_at_change, sack_ctsn)) {
1187                        primary->cacc.changeover_active = 0;
1188                        clear_cycling = 1;
1189                }
1190
1191                if (clear_cycling || gap_ack_blocks) {
1192                        list_for_each_entry(transport, transport_list,
1193                                        transports) {
1194                                if (clear_cycling)
1195                                        transport->cacc.cycling_changeover = 0;
1196                                if (gap_ack_blocks)
1197                                        transport->cacc.cacc_saw_newack = 0;
1198                        }
1199                }
1200        }
1201
1202        /* Get the highest TSN in the sack. */
1203        highest_tsn = sack_ctsn;
1204        if (gap_ack_blocks)
1205                highest_tsn += ntohs(frags[gap_ack_blocks - 1].gab.end);
1206
1207        if (TSN_lt(asoc->highest_sacked, highest_tsn))
1208                asoc->highest_sacked = highest_tsn;
1209
1210        highest_new_tsn = sack_ctsn;
1211
1212        /* Run through the retransmit queue.  Credit bytes received
1213         * and free those chunks that we can.
1214         */
1215        sctp_check_transmitted(q, &q->retransmit, NULL, NULL, sack, &highest_new_tsn);
1216
1217        /* Run through the transmitted queue.
1218         * Credit bytes received and free those chunks which we can.
1219         *
1220         * This is a MASSIVE candidate for optimization.
1221         */
1222        list_for_each_entry(transport, transport_list, transports) {
1223                sctp_check_transmitted(q, &transport->transmitted,
1224                                       transport, &chunk->source, sack,
1225                                       &highest_new_tsn);
1226                /*
1227                 * SFR-CACC algorithm:
1228                 * C) Let count_of_newacks be the number of
1229                 * destinations for which cacc_saw_newack is set.
1230                 */
1231                if (transport->cacc.cacc_saw_newack)
1232                        count_of_newacks ++;
1233        }
1234
1235        /* Move the Cumulative TSN Ack Point if appropriate.  */
1236        if (TSN_lt(asoc->ctsn_ack_point, sack_ctsn)) {
1237                asoc->ctsn_ack_point = sack_ctsn;
1238                accum_moved = 1;
1239        }
1240
1241        if (gap_ack_blocks) {
1242
1243                if (asoc->fast_recovery && accum_moved)
1244                        highest_new_tsn = highest_tsn;
1245
1246                list_for_each_entry(transport, transport_list, transports)
1247                        sctp_mark_missing(q, &transport->transmitted, transport,
1248                                          highest_new_tsn, count_of_newacks);
1249        }
1250
1251        /* Update unack_data field in the assoc. */
1252        sctp_sack_update_unack_data(asoc, sack);
1253
1254        ctsn = asoc->ctsn_ack_point;
1255
1256        /* Throw away stuff rotting on the sack queue.  */
1257        list_for_each_safe(lchunk, temp, &q->sacked) {
1258                tchunk = list_entry(lchunk, struct sctp_chunk,
1259                                    transmitted_list);
1260                tsn = ntohl(tchunk->subh.data_hdr->tsn);
1261                if (TSN_lte(tsn, ctsn)) {
1262                        list_del_init(&tchunk->transmitted_list);
1263                        sctp_chunk_free(tchunk);
1264                }
1265        }
1266
1267        /* ii) Set rwnd equal to the newly received a_rwnd minus the
1268         *     number of bytes still outstanding after processing the
1269         *     Cumulative TSN Ack and the Gap Ack Blocks.
1270         */
1271
1272        sack_a_rwnd = ntohl(sack->a_rwnd);
1273        outstanding = q->outstanding_bytes;
1274
1275        if (outstanding < sack_a_rwnd)
1276                sack_a_rwnd -= outstanding;
1277        else
1278                sack_a_rwnd = 0;
1279
1280        asoc->peer.rwnd = sack_a_rwnd;
1281
1282        sctp_generate_fwdtsn(q, sack_ctsn);
1283
1284        SCTP_DEBUG_PRINTK("%s: sack Cumulative TSN Ack is 0x%x.\n",
1285                          __func__, sack_ctsn);
1286        SCTP_DEBUG_PRINTK("%s: Cumulative TSN Ack of association, "
1287                          "%p is 0x%x. Adv peer ack point: 0x%x\n",
1288                          __func__, asoc, ctsn, asoc->adv_peer_ack_point);
1289
1290        /* See if all chunks are acked.
1291         * Make sure the empty queue handler will get run later.
1292         */
1293        q->empty = (list_empty(&q->out_chunk_list) &&
1294                    list_empty(&q->retransmit));
1295        if (!q->empty)
1296                goto finish;
1297
1298        list_for_each_entry(transport, transport_list, transports) {
1299                q->empty = q->empty && list_empty(&transport->transmitted);
1300                if (!q->empty)
1301                        goto finish;
1302        }
1303
1304        SCTP_DEBUG_PRINTK("sack queue is empty.\n");
1305finish:
1306        return q->empty;
1307}
1308
1309/* Is the outqueue empty?  */
1310int sctp_outq_is_empty(const struct sctp_outq *q)
1311{
1312        return q->empty;
1313}
1314
1315/********************************************************************
1316 * 2nd Level Abstractions
1317 ********************************************************************/
1318
1319/* Go through a transport's transmitted list or the association's retransmit
1320 * list and move chunks that are acked by the Cumulative TSN Ack to q->sacked.
1321 * The retransmit list will not have an associated transport.
1322 *
1323 * I added coherent debug information output.   --xguo
1324 *
1325 * Instead of printing 'sacked' or 'kept' for each TSN on the
1326 * transmitted_queue, we print a range: SACKED: TSN1-TSN2, TSN3, TSN4-TSN5.
1327 * KEPT TSN6-TSN7, etc.
1328 */
1329static void sctp_check_transmitted(struct sctp_outq *q,
1330                                   struct list_head *transmitted_queue,
1331                                   struct sctp_transport *transport,
1332                                   union sctp_addr *saddr,
1333                                   struct sctp_sackhdr *sack,
1334                                   __u32 *highest_new_tsn_in_sack)
1335{
1336        struct list_head *lchunk;
1337        struct sctp_chunk *tchunk;
1338        struct list_head tlist;
1339        __u32 tsn;
1340        __u32 sack_ctsn;
1341        __u32 rtt;
1342        __u8 restart_timer = 0;
1343        int bytes_acked = 0;
1344        int migrate_bytes = 0;
1345
1346        /* These state variables are for coherent debug output. --xguo */
1347
1348#if SCTP_DEBUG
1349        __u32 dbg_ack_tsn = 0;  /* An ACKed TSN range starts here... */
1350        __u32 dbg_last_ack_tsn = 0;  /* ...and finishes here.        */
1351        __u32 dbg_kept_tsn = 0; /* An un-ACKed range starts here...  */
1352        __u32 dbg_last_kept_tsn = 0; /* ...and finishes here.        */
1353
1354        /* 0 : The last TSN was ACKed.
1355         * 1 : The last TSN was NOT ACKed (i.e. KEPT).
1356         * -1: We need to initialize.
1357         */
1358        int dbg_prt_state = -1;
1359#endif /* SCTP_DEBUG */
1360
1361        sack_ctsn = ntohl(sack->cum_tsn_ack);
1362
1363        INIT_LIST_HEAD(&tlist);
1364
1365        /* The while loop will skip empty transmitted queues. */
1366        while (NULL != (lchunk = sctp_list_dequeue(transmitted_queue))) {
1367                tchunk = list_entry(lchunk, struct sctp_chunk,
1368                                    transmitted_list);
1369
1370                if (sctp_chunk_abandoned(tchunk)) {
1371                        /* Move the chunk to abandoned list. */
1372                        sctp_insert_list(&q->abandoned, lchunk);
1373
1374                        /* If this chunk has not been acked, stop
1375                         * considering it as 'outstanding'.
1376                         */
1377                        if (!tchunk->tsn_gap_acked) {
1378                                if (tchunk->transport)
1379                                        tchunk->transport->flight_size -=
1380                                                        sctp_data_size(tchunk);
1381                                q->outstanding_bytes -= sctp_data_size(tchunk);
1382                        }
1383                        continue;
1384                }
1385
1386                tsn = ntohl(tchunk->subh.data_hdr->tsn);
1387                if (sctp_acked(sack, tsn)) {
1388                        /* If this queue is the retransmit queue, the
1389                         * retransmit timer has already reclaimed
1390                         * the outstanding bytes for this chunk, so only
1391                         * count bytes associated with a transport.
1392                         */
1393                        if (transport) {
1394                                /* If this chunk is being used for RTT
1395                                 * measurement, calculate the RTT and update
1396                                 * the RTO using this value.
1397                                 *
1398                                 * 6.3.1 C5) Karn's algorithm: RTT measurements
1399                                 * MUST NOT be made using packets that were
1400                                 * retransmitted (and thus for which it is
1401                                 * ambiguous whether the reply was for the
1402                                 * first instance of the packet or a later
1403                                 * instance).
1404                                 */
1405                                if (!tchunk->tsn_gap_acked &&
1406                                    tchunk->rtt_in_progress) {
1407                                        tchunk->rtt_in_progress = 0;
1408                                        rtt = jiffies - tchunk->sent_at;
1409                                        sctp_transport_update_rto(transport,
1410                                                                  rtt);
1411                                }
1412                        }
1413
1414                        /* If the chunk hasn't been marked as ACKED,
1415                         * mark it and account bytes_acked if the
1416                         * chunk had a valid transport (it will not
1417                         * have a transport if ASCONF had deleted it
1418                         * while DATA was outstanding).
1419                         */
1420                        if (!tchunk->tsn_gap_acked) {
1421                                tchunk->tsn_gap_acked = 1;
1422                                *highest_new_tsn_in_sack = tsn;
1423                                bytes_acked += sctp_data_size(tchunk);
1424                                if (!tchunk->transport)
1425                                        migrate_bytes += sctp_data_size(tchunk);
1426                        }
1427
1428                        if (TSN_lte(tsn, sack_ctsn)) {
1429                                /* RFC 2960  6.3.2 Retransmission Timer Rules
1430                                 *
1431                                 * R3) Whenever a SACK is received
1432                                 * that acknowledges the DATA chunk
1433                                 * with the earliest outstanding TSN
1434                                 * for that address, restart T3-rtx
1435                                 * timer for that address with its
1436                                 * current RTO.
1437                                 */
1438                                restart_timer = 1;
1439
1440                                if (!tchunk->tsn_gap_acked) {
1441                                        /*
1442                                         * SFR-CACC algorithm:
1443                                         * 2) If the SACK contains gap acks
1444                                         * and the flag CHANGEOVER_ACTIVE is
1445                                         * set the receiver of the SACK MUST
1446                                         * take the following action:
1447                                         *
1448                                         * B) For each TSN t being acked that
1449                                         * has not been acked in any SACK so
1450                                         * far, set cacc_saw_newack to 1 for
1451                                         * the destination that the TSN was
1452                                         * sent to.
1453                                         */
1454                                        if (transport &&
1455                                            sack->num_gap_ack_blocks &&
1456                                            q->asoc->peer.primary_path->cacc.
1457                                            changeover_active)
1458                                                transport->cacc.cacc_saw_newack
1459                                                        = 1;
1460                                }
1461
1462                                list_add_tail(&tchunk->transmitted_list,
1463                                              &q->sacked);
1464                        } else {
1465                                /* RFC2960 7.2.4, sctpimpguide-05 2.8.2
1466                                 * M2) Each time a SACK arrives reporting
1467                                 * 'Stray DATA chunk(s)' record the highest TSN
1468                                 * reported as newly acknowledged, call this
1469                                 * value 'HighestTSNinSack'. A newly
1470                                 * acknowledged DATA chunk is one not
1471                                 * previously acknowledged in a SACK.
1472                                 *
1473                                 * When the SCTP sender of data receives a SACK
1474                                 * chunk that acknowledges, for the first time,
1475                                 * the receipt of a DATA chunk, all the still
1476                                 * unacknowledged DATA chunks whose TSN is
1477                                 * older than that newly acknowledged DATA
1478                                 * chunk, are qualified as 'Stray DATA chunks'.
1479                                 */
1480                                list_add_tail(lchunk, &tlist);
1481                        }
1482
1483#if SCTP_DEBUG
1484                        switch (dbg_prt_state) {
1485                        case 0: /* last TSN was ACKed */
1486                                if (dbg_last_ack_tsn + 1 == tsn) {
1487                                        /* This TSN belongs to the
1488                                         * current ACK range.
1489                                         */
1490                                        break;
1491                                }
1492
1493                                if (dbg_last_ack_tsn != dbg_ack_tsn) {
1494                                        /* Display the end of the
1495                                         * current range.
1496                                         */
1497                                        SCTP_DEBUG_PRINTK_CONT("-%08x",
1498                                                               dbg_last_ack_tsn);
1499                                }
1500
1501                                /* Start a new range.  */
1502                                SCTP_DEBUG_PRINTK_CONT(",%08x", tsn);
1503                                dbg_ack_tsn = tsn;
1504                                break;
1505
1506                        case 1: /* The last TSN was NOT ACKed. */
1507                                if (dbg_last_kept_tsn != dbg_kept_tsn) {
1508                                        /* Display the end of current range. */
1509                                        SCTP_DEBUG_PRINTK_CONT("-%08x",
1510                                                               dbg_last_kept_tsn);
1511                                }
1512
1513                                SCTP_DEBUG_PRINTK_CONT("\n");
1514
1515                                /* FALL THROUGH... */
1516                        default:
1517                                /* This is the first-ever TSN we examined.  */
1518                                /* Start a new range of ACK-ed TSNs.  */
1519                                SCTP_DEBUG_PRINTK("ACKed: %08x", tsn);
1520                                dbg_prt_state = 0;
1521                                dbg_ack_tsn = tsn;
1522                        }
1523
1524                        dbg_last_ack_tsn = tsn;
1525#endif /* SCTP_DEBUG */
1526
1527                } else {
1528                        if (tchunk->tsn_gap_acked) {
1529                                SCTP_DEBUG_PRINTK("%s: Receiver reneged on "
1530                                                  "data TSN: 0x%x\n",
1531                                                  __func__,
1532                                                  tsn);
1533                                tchunk->tsn_gap_acked = 0;
1534
1535                                if (tchunk->transport)
1536                                        bytes_acked -= sctp_data_size(tchunk);
1537
1538                                /* RFC 2960 6.3.2 Retransmission Timer Rules
1539                                 *
1540                                 * R4) Whenever a SACK is received missing a
1541                                 * TSN that was previously acknowledged via a
1542                                 * Gap Ack Block, start T3-rtx for the
1543                                 * destination address to which the DATA
1544                                 * chunk was originally
1545                                 * transmitted if it is not already running.
1546                                 */
1547                                restart_timer = 1;
1548                        }
1549
1550                        list_add_tail(lchunk, &tlist);
1551
1552#if SCTP_DEBUG
1553                        /* See the above comments on ACK-ed TSNs. */
1554                        switch (dbg_prt_state) {
1555                        case 1:
1556                                if (dbg_last_kept_tsn + 1 == tsn)
1557                                        break;
1558
1559                                if (dbg_last_kept_tsn != dbg_kept_tsn)
1560                                        SCTP_DEBUG_PRINTK_CONT("-%08x",
1561                                                               dbg_last_kept_tsn);
1562
1563                                SCTP_DEBUG_PRINTK_CONT(",%08x", tsn);
1564                                dbg_kept_tsn = tsn;
1565                                break;
1566
1567                        case 0:
1568                                if (dbg_last_ack_tsn != dbg_ack_tsn)
1569                                        SCTP_DEBUG_PRINTK_CONT("-%08x",
1570                                                               dbg_last_ack_tsn);
1571                                SCTP_DEBUG_PRINTK_CONT("\n");
1572
1573                                /* FALL THROUGH... */
1574                        default:
1575                                SCTP_DEBUG_PRINTK("KEPT: %08x",tsn);
1576                                dbg_prt_state = 1;
1577                                dbg_kept_tsn = tsn;
1578                        }
1579
1580                        dbg_last_kept_tsn = tsn;
1581#endif /* SCTP_DEBUG */
1582                }
1583        }
1584
1585#if SCTP_DEBUG
1586        /* Finish off the last range, displaying its ending TSN.  */
1587        switch (dbg_prt_state) {
1588        case 0:
1589                if (dbg_last_ack_tsn != dbg_ack_tsn) {
1590                        SCTP_DEBUG_PRINTK_CONT("-%08x\n", dbg_last_ack_tsn);
1591                } else {
1592                        SCTP_DEBUG_PRINTK_CONT("\n");
1593                }
1594        break;
1595
1596        case 1:
1597                if (dbg_last_kept_tsn != dbg_kept_tsn) {
1598                        SCTP_DEBUG_PRINTK_CONT("-%08x\n", dbg_last_kept_tsn);
1599                } else {
1600                        SCTP_DEBUG_PRINTK_CONT("\n");
1601                }
1602        }
1603#endif /* SCTP_DEBUG */
1604        if (transport) {
1605                if (bytes_acked) {
1606                        struct sctp_association *asoc = transport->asoc;
1607
1608                        /* We may have counted DATA that was migrated
1609                         * to this transport due to DEL-IP operation.
1610                         * Subtract those bytes, since the were never
1611                         * send on this transport and shouldn't be
1612                         * credited to this transport.
1613                         */
1614                        bytes_acked -= migrate_bytes;
1615
1616                        /* 8.2. When an outstanding TSN is acknowledged,
1617                         * the endpoint shall clear the error counter of
1618                         * the destination transport address to which the
1619                         * DATA chunk was last sent.
1620                         * The association's overall error counter is
1621                         * also cleared.
1622                         */
1623                        transport->error_count = 0;
1624                        transport->asoc->overall_error_count = 0;
1625
1626                        /*
1627                         * While in SHUTDOWN PENDING, we may have started
1628                         * the T5 shutdown guard timer after reaching the
1629                         * retransmission limit. Stop that timer as soon
1630                         * as the receiver acknowledged any data.
1631                         */
1632                        if (asoc->state == SCTP_STATE_SHUTDOWN_PENDING &&
1633                            del_timer(&asoc->timers
1634                                [SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD]))
1635                                        sctp_association_put(asoc);
1636
1637                        /* Mark the destination transport address as
1638                         * active if it is not so marked.
1639                         */
1640                        if ((transport->state == SCTP_INACTIVE ||
1641                             transport->state == SCTP_UNCONFIRMED) &&
1642                            sctp_cmp_addr_exact(&transport->ipaddr, saddr)) {
1643                                sctp_assoc_control_transport(
1644                                        transport->asoc,
1645                                        transport,
1646                                        SCTP_TRANSPORT_UP,
1647                                        SCTP_RECEIVED_SACK);
1648                        }
1649
1650                        sctp_transport_raise_cwnd(transport, sack_ctsn,
1651                                                  bytes_acked);
1652
1653                        transport->flight_size -= bytes_acked;
1654                        if (transport->flight_size == 0)
1655                                transport->partial_bytes_acked = 0;
1656                        q->outstanding_bytes -= bytes_acked + migrate_bytes;
1657                } else {
1658                        /* RFC 2960 6.1, sctpimpguide-06 2.15.2
1659                         * When a sender is doing zero window probing, it
1660                         * should not timeout the association if it continues
1661                         * to receive new packets from the receiver. The
1662                         * reason is that the receiver MAY keep its window
1663                         * closed for an indefinite time.
1664                         * A sender is doing zero window probing when the
1665                         * receiver's advertised window is zero, and there is
1666                         * only one data chunk in flight to the receiver.
1667                         *
1668                         * Allow the association to timeout while in SHUTDOWN
1669                         * PENDING or SHUTDOWN RECEIVED in case the receiver
1670                         * stays in zero window mode forever.
1671                         */
1672                        if (!q->asoc->peer.rwnd &&
1673                            !list_empty(&tlist) &&
1674                            (sack_ctsn+2 == q->asoc->next_tsn) &&
1675                            q->asoc->state < SCTP_STATE_SHUTDOWN_PENDING) {
1676                                SCTP_DEBUG_PRINTK("%s: SACK received for zero "
1677                                                  "window probe: %u\n",
1678                                                  __func__, sack_ctsn);
1679                                q->asoc->overall_error_count = 0;
1680                                transport->error_count = 0;
1681                        }
1682                }
1683
1684                /* RFC 2960 6.3.2 Retransmission Timer Rules
1685                 *
1686                 * R2) Whenever all outstanding data sent to an address have
1687                 * been acknowledged, turn off the T3-rtx timer of that
1688                 * address.
1689                 */
1690                if (!transport->flight_size) {
1691                        if (timer_pending(&transport->T3_rtx_timer) &&
1692                            del_timer(&transport->T3_rtx_timer)) {
1693                                sctp_transport_put(transport);
1694                        }
1695                } else if (restart_timer) {
1696                        if (!mod_timer(&transport->T3_rtx_timer,
1697                                       jiffies + transport->rto))
1698                                sctp_transport_hold(transport);
1699                }
1700        }
1701
1702        list_splice(&tlist, transmitted_queue);
1703}
1704
1705/* Mark chunks as missing and consequently may get retransmitted. */
1706static void sctp_mark_missing(struct sctp_outq *q,
1707                              struct list_head *transmitted_queue,
1708                              struct sctp_transport *transport,
1709                              __u32 highest_new_tsn_in_sack,
1710                              int count_of_newacks)
1711{
1712        struct sctp_chunk *chunk;
1713        __u32 tsn;
1714        char do_fast_retransmit = 0;
1715        struct sctp_association *asoc = q->asoc;
1716        struct sctp_transport *primary = asoc->peer.primary_path;
1717
1718        list_for_each_entry(chunk, transmitted_queue, transmitted_list) {
1719
1720                tsn = ntohl(chunk->subh.data_hdr->tsn);
1721
1722                /* RFC 2960 7.2.4, sctpimpguide-05 2.8.2 M3) Examine all
1723                 * 'Unacknowledged TSN's', if the TSN number of an
1724                 * 'Unacknowledged TSN' is smaller than the 'HighestTSNinSack'
1725                 * value, increment the 'TSN.Missing.Report' count on that
1726                 * chunk if it has NOT been fast retransmitted or marked for
1727                 * fast retransmit already.
1728                 */
1729                if (chunk->fast_retransmit == SCTP_CAN_FRTX &&
1730                    !chunk->tsn_gap_acked &&
1731                    TSN_lt(tsn, highest_new_tsn_in_sack)) {
1732
1733                        /* SFR-CACC may require us to skip marking
1734                         * this chunk as missing.
1735                         */
1736                        if (!transport || !sctp_cacc_skip(primary,
1737                                                chunk->transport,
1738                                                count_of_newacks, tsn)) {
1739                                chunk->tsn_missing_report++;
1740
1741                                SCTP_DEBUG_PRINTK(
1742                                        "%s: TSN 0x%x missing counter: %d\n",
1743                                        __func__, tsn,
1744                                        chunk->tsn_missing_report);
1745                        }
1746                }
1747                /*
1748                 * M4) If any DATA chunk is found to have a
1749                 * 'TSN.Missing.Report'
1750                 * value larger than or equal to 3, mark that chunk for
1751                 * retransmission and start the fast retransmit procedure.
1752                 */
1753
1754                if (chunk->tsn_missing_report >= 3) {
1755                        chunk->fast_retransmit = SCTP_NEED_FRTX;
1756                        do_fast_retransmit = 1;
1757                }
1758        }
1759
1760        if (transport) {
1761                if (do_fast_retransmit)
1762                        sctp_retransmit(q, transport, SCTP_RTXR_FAST_RTX);
1763
1764                SCTP_DEBUG_PRINTK("%s: transport: %p, cwnd: %d, "
1765                                  "ssthresh: %d, flight_size: %d, pba: %d\n",
1766                                  __func__, transport, transport->cwnd,
1767                                  transport->ssthresh, transport->flight_size,
1768                                  transport->partial_bytes_acked);
1769        }
1770}
1771
1772/* Is the given TSN acked by this packet?  */
1773static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn)
1774{
1775        int i;
1776        sctp_sack_variable_t *frags;
1777        __u16 gap;
1778        __u32 ctsn = ntohl(sack->cum_tsn_ack);
1779
1780        if (TSN_lte(tsn, ctsn))
1781                goto pass;
1782
1783        /* 3.3.4 Selective Acknowledgement (SACK) (3):
1784         *
1785         * Gap Ack Blocks:
1786         *  These fields contain the Gap Ack Blocks. They are repeated
1787         *  for each Gap Ack Block up to the number of Gap Ack Blocks
1788         *  defined in the Number of Gap Ack Blocks field. All DATA
1789         *  chunks with TSNs greater than or equal to (Cumulative TSN
1790         *  Ack + Gap Ack Block Start) and less than or equal to
1791         *  (Cumulative TSN Ack + Gap Ack Block End) of each Gap Ack
1792         *  Block are assumed to have been received correctly.
1793         */
1794
1795        frags = sack->variable;
1796        gap = tsn - ctsn;
1797        for (i = 0; i < ntohs(sack->num_gap_ack_blocks); ++i) {
1798                if (TSN_lte(ntohs(frags[i].gab.start), gap) &&
1799                    TSN_lte(gap, ntohs(frags[i].gab.end)))
1800                        goto pass;
1801        }
1802
1803        return 0;
1804pass:
1805        return 1;
1806}
1807
1808static inline int sctp_get_skip_pos(struct sctp_fwdtsn_skip *skiplist,
1809                                    int nskips, __be16 stream)
1810{
1811        int i;
1812
1813        for (i = 0; i < nskips; i++) {
1814                if (skiplist[i].stream == stream)
1815                        return i;
1816        }
1817        return i;
1818}
1819
1820/* Create and add a fwdtsn chunk to the outq's control queue if needed. */
1821static void sctp_generate_fwdtsn(struct sctp_outq *q, __u32 ctsn)
1822{
1823        struct sctp_association *asoc = q->asoc;
1824        struct sctp_chunk *ftsn_chunk = NULL;
1825        struct sctp_fwdtsn_skip ftsn_skip_arr[10];
1826        int nskips = 0;
1827        int skip_pos = 0;
1828        __u32 tsn;
1829        struct sctp_chunk *chunk;
1830        struct list_head *lchunk, *temp;
1831
1832        if (!asoc->peer.prsctp_capable)
1833                return;
1834
1835        /* PR-SCTP C1) Let SackCumAck be the Cumulative TSN ACK carried in the
1836         * received SACK.
1837         *
1838         * If (Advanced.Peer.Ack.Point < SackCumAck), then update
1839         * Advanced.Peer.Ack.Point to be equal to SackCumAck.
1840         */
1841        if (TSN_lt(asoc->adv_peer_ack_point, ctsn))
1842                asoc->adv_peer_ack_point = ctsn;
1843
1844        /* PR-SCTP C2) Try to further advance the "Advanced.Peer.Ack.Point"
1845         * locally, that is, to move "Advanced.Peer.Ack.Point" up as long as
1846         * the chunk next in the out-queue space is marked as "abandoned" as
1847         * shown in the following example:
1848         *
1849         * Assuming that a SACK arrived with the Cumulative TSN ACK 102
1850         * and the Advanced.Peer.Ack.Point is updated to this value:
1851         *
1852         *   out-queue at the end of  ==>   out-queue after Adv.Ack.Point
1853         *   normal SACK processing           local advancement
1854         *                ...                           ...
1855         *   Adv.Ack.Pt-> 102 acked                     102 acked
1856         *                103 abandoned                 103 abandoned
1857         *                104 abandoned     Adv.Ack.P-> 104 abandoned
1858         *                105                           105
1859         *                106 acked                     106 acked
1860         *                ...                           ...
1861         *
1862         * In this example, the data sender successfully advanced the
1863         * "Advanced.Peer.Ack.Point" from 102 to 104 locally.
1864         */
1865        list_for_each_safe(lchunk, temp, &q->abandoned) {
1866                chunk = list_entry(lchunk, struct sctp_chunk,
1867                                        transmitted_list);
1868                tsn = ntohl(chunk->subh.data_hdr->tsn);
1869
1870                /* Remove any chunks in the abandoned queue that are acked by
1871                 * the ctsn.
1872                 */
1873                if (TSN_lte(tsn, ctsn)) {
1874                        list_del_init(lchunk);
1875                        sctp_chunk_free(chunk);
1876                } else {
1877                        if (TSN_lte(tsn, asoc->adv_peer_ack_point+1)) {
1878                                asoc->adv_peer_ack_point = tsn;
1879                                if (chunk->chunk_hdr->flags &
1880                                         SCTP_DATA_UNORDERED)
1881                                        continue;
1882                                skip_pos = sctp_get_skip_pos(&ftsn_skip_arr[0],
1883                                                nskips,
1884                                                chunk->subh.data_hdr->stream);
1885                                ftsn_skip_arr[skip_pos].stream =
1886                                        chunk->subh.data_hdr->stream;
1887                                ftsn_skip_arr[skip_pos].ssn =
1888                                         chunk->subh.data_hdr->ssn;
1889                                if (skip_pos == nskips)
1890                                        nskips++;
1891                                if (nskips == 10)
1892                                        break;
1893                        } else
1894                                break;
1895                }
1896        }
1897
1898        /* PR-SCTP C3) If, after step C1 and C2, the "Advanced.Peer.Ack.Point"
1899         * is greater than the Cumulative TSN ACK carried in the received
1900         * SACK, the data sender MUST send the data receiver a FORWARD TSN
1901         * chunk containing the latest value of the
1902         * "Advanced.Peer.Ack.Point".
1903         *
1904         * C4) For each "abandoned" TSN the sender of the FORWARD TSN SHOULD
1905         * list each stream and sequence number in the forwarded TSN. This
1906         * information will enable the receiver to easily find any
1907         * stranded TSN's waiting on stream reorder queues. Each stream
1908         * SHOULD only be reported once; this means that if multiple
1909         * abandoned messages occur in the same stream then only the
1910         * highest abandoned stream sequence number is reported. If the
1911         * total size of the FORWARD TSN does NOT fit in a single MTU then
1912         * the sender of the FORWARD TSN SHOULD lower the
1913         * Advanced.Peer.Ack.Point to the last TSN that will fit in a
1914         * single MTU.
1915         */
1916        if (asoc->adv_peer_ack_point > ctsn)
1917                ftsn_chunk = sctp_make_fwdtsn(asoc, asoc->adv_peer_ack_point,
1918                                              nskips, &ftsn_skip_arr[0]);
1919
1920        if (ftsn_chunk) {
1921                list_add_tail(&ftsn_chunk->list, &q->control_chunk_list);
1922                SCTP_INC_STATS(sock_net(asoc->base.sk), SCTP_MIB_OUTCTRLCHUNKS);
1923        }
1924}
1925
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.