linux/net/sctp/ulpqueue.c
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   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 Intel Corp.
   6 * Copyright (c) 2001 Nokia, Inc.
   7 * Copyright (c) 2001 La Monte H.P. Yarroll
   8 *
   9 * This abstraction carries sctp events to the ULP (sockets).
  10 *
  11 * This SCTP implementation is free software;
  12 * you can redistribute it and/or modify it under the terms of
  13 * the GNU General Public License as published by
  14 * the Free Software Foundation; either version 2, or (at your option)
  15 * any later version.
  16 *
  17 * This SCTP implementation is distributed in the hope that it
  18 * will be useful, but WITHOUT ANY WARRANTY; without even the implied
  19 *                 ************************
  20 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  21 * See the GNU General Public License for more details.
  22 *
  23 * You should have received a copy of the GNU General Public License
  24 * along with GNU CC; see the file COPYING.  If not, write to
  25 * the Free Software Foundation, 59 Temple Place - Suite 330,
  26 * Boston, MA 02111-1307, USA.
  27 *
  28 * Please send any bug reports or fixes you make to the
  29 * email address(es):
  30 *    lksctp developers <lksctp-developers@lists.sourceforge.net>
  31 *
  32 * Or submit a bug report through the following website:
  33 *    http://www.sf.net/projects/lksctp
  34 *
  35 * Written or modified by:
  36 *    Jon Grimm             <jgrimm@us.ibm.com>
  37 *    La Monte H.P. Yarroll <piggy@acm.org>
  38 *    Sridhar Samudrala     <sri@us.ibm.com>
  39 *
  40 * Any bugs reported given to us we will try to fix... any fixes shared will
  41 * be incorporated into the next SCTP release.
  42 */
  43
  44#include <linux/slab.h>
  45#include <linux/types.h>
  46#include <linux/skbuff.h>
  47#include <net/sock.h>
  48#include <net/sctp/structs.h>
  49#include <net/sctp/sctp.h>
  50#include <net/sctp/sm.h>
  51
  52/* Forward declarations for internal helpers.  */
  53static struct sctp_ulpevent * sctp_ulpq_reasm(struct sctp_ulpq *ulpq,
  54                                              struct sctp_ulpevent *);
  55static struct sctp_ulpevent * sctp_ulpq_order(struct sctp_ulpq *,
  56                                              struct sctp_ulpevent *);
  57static void sctp_ulpq_reasm_drain(struct sctp_ulpq *ulpq);
  58
  59/* 1st Level Abstractions */
  60
  61/* Initialize a ULP queue from a block of memory.  */
  62struct sctp_ulpq *sctp_ulpq_init(struct sctp_ulpq *ulpq,
  63                                 struct sctp_association *asoc)
  64{
  65        memset(ulpq, 0, sizeof(struct sctp_ulpq));
  66
  67        ulpq->asoc = asoc;
  68        skb_queue_head_init(&ulpq->reasm);
  69        skb_queue_head_init(&ulpq->lobby);
  70        ulpq->pd_mode  = 0;
  71        ulpq->malloced = 0;
  72
  73        return ulpq;
  74}
  75
  76
  77/* Flush the reassembly and ordering queues.  */
  78void sctp_ulpq_flush(struct sctp_ulpq *ulpq)
  79{
  80        struct sk_buff *skb;
  81        struct sctp_ulpevent *event;
  82
  83        while ((skb = __skb_dequeue(&ulpq->lobby)) != NULL) {
  84                event = sctp_skb2event(skb);
  85                sctp_ulpevent_free(event);
  86        }
  87
  88        while ((skb = __skb_dequeue(&ulpq->reasm)) != NULL) {
  89                event = sctp_skb2event(skb);
  90                sctp_ulpevent_free(event);
  91        }
  92
  93}
  94
  95/* Dispose of a ulpqueue.  */
  96void sctp_ulpq_free(struct sctp_ulpq *ulpq)
  97{
  98        sctp_ulpq_flush(ulpq);
  99        if (ulpq->malloced)
 100                kfree(ulpq);
 101}
 102
 103/* Process an incoming DATA chunk.  */
 104int sctp_ulpq_tail_data(struct sctp_ulpq *ulpq, struct sctp_chunk *chunk,
 105                        gfp_t gfp)
 106{
 107        struct sk_buff_head temp;
 108        struct sctp_ulpevent *event;
 109
 110        /* Create an event from the incoming chunk. */
 111        event = sctp_ulpevent_make_rcvmsg(chunk->asoc, chunk, gfp);
 112        if (!event)
 113                return -ENOMEM;
 114
 115        /* Do reassembly if needed.  */
 116        event = sctp_ulpq_reasm(ulpq, event);
 117
 118        /* Do ordering if needed.  */
 119        if ((event) && (event->msg_flags & MSG_EOR)){
 120                /* Create a temporary list to collect chunks on.  */
 121                skb_queue_head_init(&temp);
 122                __skb_queue_tail(&temp, sctp_event2skb(event));
 123
 124                event = sctp_ulpq_order(ulpq, event);
 125        }
 126
 127        /* Send event to the ULP.  'event' is the sctp_ulpevent for
 128         * very first SKB on the 'temp' list.
 129         */
 130        if (event)
 131                sctp_ulpq_tail_event(ulpq, event);
 132
 133        return 0;
 134}
 135
 136/* Add a new event for propagation to the ULP.  */
 137/* Clear the partial delivery mode for this socket.   Note: This
 138 * assumes that no association is currently in partial delivery mode.
 139 */
 140int sctp_clear_pd(struct sock *sk, struct sctp_association *asoc)
 141{
 142        struct sctp_sock *sp = sctp_sk(sk);
 143
 144        if (atomic_dec_and_test(&sp->pd_mode)) {
 145                /* This means there are no other associations in PD, so
 146                 * we can go ahead and clear out the lobby in one shot
 147                 */
 148                if (!skb_queue_empty(&sp->pd_lobby)) {
 149                        struct list_head *list;
 150                        sctp_skb_list_tail(&sp->pd_lobby, &sk->sk_receive_queue);
 151                        list = (struct list_head *)&sctp_sk(sk)->pd_lobby;
 152                        INIT_LIST_HEAD(list);
 153                        return 1;
 154                }
 155        } else {
 156                /* There are other associations in PD, so we only need to
 157                 * pull stuff out of the lobby that belongs to the
 158                 * associations that is exiting PD (all of its notifications
 159                 * are posted here).
 160                 */
 161                if (!skb_queue_empty(&sp->pd_lobby) && asoc) {
 162                        struct sk_buff *skb, *tmp;
 163                        struct sctp_ulpevent *event;
 164
 165                        sctp_skb_for_each(skb, &sp->pd_lobby, tmp) {
 166                                event = sctp_skb2event(skb);
 167                                if (event->asoc == asoc) {
 168                                        __skb_unlink(skb, &sp->pd_lobby);
 169                                        __skb_queue_tail(&sk->sk_receive_queue,
 170                                                         skb);
 171                                }
 172                        }
 173                }
 174        }
 175
 176        return 0;
 177}
 178
 179/* Set the pd_mode on the socket and ulpq */
 180static void sctp_ulpq_set_pd(struct sctp_ulpq *ulpq)
 181{
 182        struct sctp_sock *sp = sctp_sk(ulpq->asoc->base.sk);
 183
 184        atomic_inc(&sp->pd_mode);
 185        ulpq->pd_mode = 1;
 186}
 187
 188/* Clear the pd_mode and restart any pending messages waiting for delivery. */
 189static int sctp_ulpq_clear_pd(struct sctp_ulpq *ulpq)
 190{
 191        ulpq->pd_mode = 0;
 192        sctp_ulpq_reasm_drain(ulpq);
 193        return sctp_clear_pd(ulpq->asoc->base.sk, ulpq->asoc);
 194}
 195
 196/* If the SKB of 'event' is on a list, it is the first such member
 197 * of that list.
 198 */
 199int sctp_ulpq_tail_event(struct sctp_ulpq *ulpq, struct sctp_ulpevent *event)
 200{
 201        struct sock *sk = ulpq->asoc->base.sk;
 202        struct sk_buff_head *queue, *skb_list;
 203        struct sk_buff *skb = sctp_event2skb(event);
 204        int clear_pd = 0;
 205
 206        skb_list = (struct sk_buff_head *) skb->prev;
 207
 208        /* If the socket is just going to throw this away, do not
 209         * even try to deliver it.
 210         */
 211        if (sock_flag(sk, SOCK_DEAD) || (sk->sk_shutdown & RCV_SHUTDOWN))
 212                goto out_free;
 213
 214        /* Check if the user wishes to receive this event.  */
 215        if (!sctp_ulpevent_is_enabled(event, &sctp_sk(sk)->subscribe))
 216                goto out_free;
 217
 218        /* If we are in partial delivery mode, post to the lobby until
 219         * partial delivery is cleared, unless, of course _this_ is
 220         * the association the cause of the partial delivery.
 221         */
 222
 223        if (atomic_read(&sctp_sk(sk)->pd_mode) == 0) {
 224                queue = &sk->sk_receive_queue;
 225        } else {
 226                if (ulpq->pd_mode) {
 227                        /* If the association is in partial delivery, we
 228                         * need to finish delivering the partially processed
 229                         * packet before passing any other data.  This is
 230                         * because we don't truly support stream interleaving.
 231                         */
 232                        if ((event->msg_flags & MSG_NOTIFICATION) ||
 233                            (SCTP_DATA_NOT_FRAG ==
 234                                    (event->msg_flags & SCTP_DATA_FRAG_MASK)))
 235                                queue = &sctp_sk(sk)->pd_lobby;
 236                        else {
 237                                clear_pd = event->msg_flags & MSG_EOR;
 238                                queue = &sk->sk_receive_queue;
 239                        }
 240                } else {
 241                        /*
 242                         * If fragment interleave is enabled, we
 243                         * can queue this to the receive queue instead
 244                         * of the lobby.
 245                         */
 246                        if (sctp_sk(sk)->frag_interleave)
 247                                queue = &sk->sk_receive_queue;
 248                        else
 249                                queue = &sctp_sk(sk)->pd_lobby;
 250                }
 251        }
 252
 253        /* If we are harvesting multiple skbs they will be
 254         * collected on a list.
 255         */
 256        if (skb_list)
 257                sctp_skb_list_tail(skb_list, queue);
 258        else
 259                __skb_queue_tail(queue, skb);
 260
 261        /* Did we just complete partial delivery and need to get
 262         * rolling again?  Move pending data to the receive
 263         * queue.
 264         */
 265        if (clear_pd)
 266                sctp_ulpq_clear_pd(ulpq);
 267
 268        if (queue == &sk->sk_receive_queue)
 269                sk->sk_data_ready(sk, 0);
 270        return 1;
 271
 272out_free:
 273        if (skb_list)
 274                sctp_queue_purge_ulpevents(skb_list);
 275        else
 276                sctp_ulpevent_free(event);
 277
 278        return 0;
 279}
 280
 281/* 2nd Level Abstractions */
 282
 283/* Helper function to store chunks that need to be reassembled.  */
 284static void sctp_ulpq_store_reasm(struct sctp_ulpq *ulpq,
 285                                         struct sctp_ulpevent *event)
 286{
 287        struct sk_buff *pos;
 288        struct sctp_ulpevent *cevent;
 289        __u32 tsn, ctsn;
 290
 291        tsn = event->tsn;
 292
 293        /* See if it belongs at the end. */
 294        pos = skb_peek_tail(&ulpq->reasm);
 295        if (!pos) {
 296                __skb_queue_tail(&ulpq->reasm, sctp_event2skb(event));
 297                return;
 298        }
 299
 300        /* Short circuit just dropping it at the end. */
 301        cevent = sctp_skb2event(pos);
 302        ctsn = cevent->tsn;
 303        if (TSN_lt(ctsn, tsn)) {
 304                __skb_queue_tail(&ulpq->reasm, sctp_event2skb(event));
 305                return;
 306        }
 307
 308        /* Find the right place in this list. We store them by TSN.  */
 309        skb_queue_walk(&ulpq->reasm, pos) {
 310                cevent = sctp_skb2event(pos);
 311                ctsn = cevent->tsn;
 312
 313                if (TSN_lt(tsn, ctsn))
 314                        break;
 315        }
 316
 317        /* Insert before pos. */
 318        __skb_queue_before(&ulpq->reasm, pos, sctp_event2skb(event));
 319
 320}
 321
 322/* Helper function to return an event corresponding to the reassembled
 323 * datagram.
 324 * This routine creates a re-assembled skb given the first and last skb's
 325 * as stored in the reassembly queue. The skb's may be non-linear if the sctp
 326 * payload was fragmented on the way and ip had to reassemble them.
 327 * We add the rest of skb's to the first skb's fraglist.
 328 */
 329static struct sctp_ulpevent *sctp_make_reassembled_event(struct net *net,
 330        struct sk_buff_head *queue, struct sk_buff *f_frag,
 331        struct sk_buff *l_frag)
 332{
 333        struct sk_buff *pos;
 334        struct sk_buff *new = NULL;
 335        struct sctp_ulpevent *event;
 336        struct sk_buff *pnext, *last;
 337        struct sk_buff *list = skb_shinfo(f_frag)->frag_list;
 338
 339        /* Store the pointer to the 2nd skb */
 340        if (f_frag == l_frag)
 341                pos = NULL;
 342        else
 343                pos = f_frag->next;
 344
 345        /* Get the last skb in the f_frag's frag_list if present. */
 346        for (last = list; list; last = list, list = list->next);
 347
 348        /* Add the list of remaining fragments to the first fragments
 349         * frag_list.
 350         */
 351        if (last)
 352                last->next = pos;
 353        else {
 354                if (skb_cloned(f_frag)) {
 355                        /* This is a cloned skb, we can't just modify
 356                         * the frag_list.  We need a new skb to do that.
 357                         * Instead of calling skb_unshare(), we'll do it
 358                         * ourselves since we need to delay the free.
 359                         */
 360                        new = skb_copy(f_frag, GFP_ATOMIC);
 361                        if (!new)
 362                                return NULL;    /* try again later */
 363
 364                        sctp_skb_set_owner_r(new, f_frag->sk);
 365
 366                        skb_shinfo(new)->frag_list = pos;
 367                } else
 368                        skb_shinfo(f_frag)->frag_list = pos;
 369        }
 370
 371        /* Remove the first fragment from the reassembly queue.  */
 372        __skb_unlink(f_frag, queue);
 373
 374        /* if we did unshare, then free the old skb and re-assign */
 375        if (new) {
 376                kfree_skb(f_frag);
 377                f_frag = new;
 378        }
 379
 380        while (pos) {
 381
 382                pnext = pos->next;
 383
 384                /* Update the len and data_len fields of the first fragment. */
 385                f_frag->len += pos->len;
 386                f_frag->data_len += pos->len;
 387
 388                /* Remove the fragment from the reassembly queue.  */
 389                __skb_unlink(pos, queue);
 390
 391                /* Break if we have reached the last fragment.  */
 392                if (pos == l_frag)
 393                        break;
 394                pos->next = pnext;
 395                pos = pnext;
 396        }
 397
 398        event = sctp_skb2event(f_frag);
 399        SCTP_INC_STATS(net, SCTP_MIB_REASMUSRMSGS);
 400
 401        return event;
 402}
 403
 404
 405/* Helper function to check if an incoming chunk has filled up the last
 406 * missing fragment in a SCTP datagram and return the corresponding event.
 407 */
 408static struct sctp_ulpevent *sctp_ulpq_retrieve_reassembled(struct sctp_ulpq *ulpq)
 409{
 410        struct sk_buff *pos;
 411        struct sctp_ulpevent *cevent;
 412        struct sk_buff *first_frag = NULL;
 413        __u32 ctsn, next_tsn;
 414        struct sctp_ulpevent *retval = NULL;
 415        struct sk_buff *pd_first = NULL;
 416        struct sk_buff *pd_last = NULL;
 417        size_t pd_len = 0;
 418        struct sctp_association *asoc;
 419        u32 pd_point;
 420
 421        /* Initialized to 0 just to avoid compiler warning message.  Will
 422         * never be used with this value. It is referenced only after it
 423         * is set when we find the first fragment of a message.
 424         */
 425        next_tsn = 0;
 426
 427        /* The chunks are held in the reasm queue sorted by TSN.
 428         * Walk through the queue sequentially and look for a sequence of
 429         * fragmented chunks that complete a datagram.
 430         * 'first_frag' and next_tsn are reset when we find a chunk which
 431         * is the first fragment of a datagram. Once these 2 fields are set
 432         * we expect to find the remaining middle fragments and the last
 433         * fragment in order. If not, first_frag is reset to NULL and we
 434         * start the next pass when we find another first fragment.
 435         *
 436         * There is a potential to do partial delivery if user sets
 437         * SCTP_PARTIAL_DELIVERY_POINT option. Lets count some things here
 438         * to see if can do PD.
 439         */
 440        skb_queue_walk(&ulpq->reasm, pos) {
 441                cevent = sctp_skb2event(pos);
 442                ctsn = cevent->tsn;
 443
 444                switch (cevent->msg_flags & SCTP_DATA_FRAG_MASK) {
 445                case SCTP_DATA_FIRST_FRAG:
 446                        /* If this "FIRST_FRAG" is the first
 447                         * element in the queue, then count it towards
 448                         * possible PD.
 449                         */
 450                        if (pos == ulpq->reasm.next) {
 451                            pd_first = pos;
 452                            pd_last = pos;
 453                            pd_len = pos->len;
 454                        } else {
 455                            pd_first = NULL;
 456                            pd_last = NULL;
 457                            pd_len = 0;
 458                        }
 459
 460                        first_frag = pos;
 461                        next_tsn = ctsn + 1;
 462                        break;
 463
 464                case SCTP_DATA_MIDDLE_FRAG:
 465                        if ((first_frag) && (ctsn == next_tsn)) {
 466                                next_tsn++;
 467                                if (pd_first) {
 468                                    pd_last = pos;
 469                                    pd_len += pos->len;
 470                                }
 471                        } else
 472                                first_frag = NULL;
 473                        break;
 474
 475                case SCTP_DATA_LAST_FRAG:
 476                        if (first_frag && (ctsn == next_tsn))
 477                                goto found;
 478                        else
 479                                first_frag = NULL;
 480                        break;
 481                }
 482        }
 483
 484        asoc = ulpq->asoc;
 485        if (pd_first) {
 486                /* Make sure we can enter partial deliver.
 487                 * We can trigger partial delivery only if framgent
 488                 * interleave is set, or the socket is not already
 489                 * in  partial delivery.
 490                 */
 491                if (!sctp_sk(asoc->base.sk)->frag_interleave &&
 492                    atomic_read(&sctp_sk(asoc->base.sk)->pd_mode))
 493                        goto done;
 494
 495                cevent = sctp_skb2event(pd_first);
 496                pd_point = sctp_sk(asoc->base.sk)->pd_point;
 497                if (pd_point && pd_point <= pd_len) {
 498                        retval = sctp_make_reassembled_event(sock_net(asoc->base.sk),
 499                                                             &ulpq->reasm,
 500                                                             pd_first,
 501                                                             pd_last);
 502                        if (retval)
 503                                sctp_ulpq_set_pd(ulpq);
 504                }
 505        }
 506done:
 507        return retval;
 508found:
 509        retval = sctp_make_reassembled_event(sock_net(ulpq->asoc->base.sk),
 510                                             &ulpq->reasm, first_frag, pos);
 511        if (retval)
 512                retval->msg_flags |= MSG_EOR;
 513        goto done;
 514}
 515
 516/* Retrieve the next set of fragments of a partial message. */
 517static struct sctp_ulpevent *sctp_ulpq_retrieve_partial(struct sctp_ulpq *ulpq)
 518{
 519        struct sk_buff *pos, *last_frag, *first_frag;
 520        struct sctp_ulpevent *cevent;
 521        __u32 ctsn, next_tsn;
 522        int is_last;
 523        struct sctp_ulpevent *retval;
 524
 525        /* The chunks are held in the reasm queue sorted by TSN.
 526         * Walk through the queue sequentially and look for the first
 527         * sequence of fragmented chunks.
 528         */
 529
 530        if (skb_queue_empty(&ulpq->reasm))
 531                return NULL;
 532
 533        last_frag = first_frag = NULL;
 534        retval = NULL;
 535        next_tsn = 0;
 536        is_last = 0;
 537
 538        skb_queue_walk(&ulpq->reasm, pos) {
 539                cevent = sctp_skb2event(pos);
 540                ctsn = cevent->tsn;
 541
 542                switch (cevent->msg_flags & SCTP_DATA_FRAG_MASK) {
 543                case SCTP_DATA_MIDDLE_FRAG:
 544                        if (!first_frag) {
 545                                first_frag = pos;
 546                                next_tsn = ctsn + 1;
 547                                last_frag = pos;
 548                        } else if (next_tsn == ctsn)
 549                                next_tsn++;
 550                        else
 551                                goto done;
 552                        break;
 553                case SCTP_DATA_LAST_FRAG:
 554                        if (!first_frag)
 555                                first_frag = pos;
 556                        else if (ctsn != next_tsn)
 557                                goto done;
 558                        last_frag = pos;
 559                        is_last = 1;
 560                        goto done;
 561                default:
 562                        return NULL;
 563                }
 564        }
 565
 566        /* We have the reassembled event. There is no need to look
 567         * further.
 568         */
 569done:
 570        retval = sctp_make_reassembled_event(sock_net(ulpq->asoc->base.sk),
 571                                        &ulpq->reasm, first_frag, last_frag);
 572        if (retval && is_last)
 573                retval->msg_flags |= MSG_EOR;
 574
 575        return retval;
 576}
 577
 578
 579/* Helper function to reassemble chunks.  Hold chunks on the reasm queue that
 580 * need reassembling.
 581 */
 582static struct sctp_ulpevent *sctp_ulpq_reasm(struct sctp_ulpq *ulpq,
 583                                                struct sctp_ulpevent *event)
 584{
 585        struct sctp_ulpevent *retval = NULL;
 586
 587        /* Check if this is part of a fragmented message.  */
 588        if (SCTP_DATA_NOT_FRAG == (event->msg_flags & SCTP_DATA_FRAG_MASK)) {
 589                event->msg_flags |= MSG_EOR;
 590                return event;
 591        }
 592
 593        sctp_ulpq_store_reasm(ulpq, event);
 594        if (!ulpq->pd_mode)
 595                retval = sctp_ulpq_retrieve_reassembled(ulpq);
 596        else {
 597                __u32 ctsn, ctsnap;
 598
 599                /* Do not even bother unless this is the next tsn to
 600                 * be delivered.
 601                 */
 602                ctsn = event->tsn;
 603                ctsnap = sctp_tsnmap_get_ctsn(&ulpq->asoc->peer.tsn_map);
 604                if (TSN_lte(ctsn, ctsnap))
 605                        retval = sctp_ulpq_retrieve_partial(ulpq);
 606        }
 607
 608        return retval;
 609}
 610
 611/* Retrieve the first part (sequential fragments) for partial delivery.  */
 612static struct sctp_ulpevent *sctp_ulpq_retrieve_first(struct sctp_ulpq *ulpq)
 613{
 614        struct sk_buff *pos, *last_frag, *first_frag;
 615        struct sctp_ulpevent *cevent;
 616        __u32 ctsn, next_tsn;
 617        struct sctp_ulpevent *retval;
 618
 619        /* The chunks are held in the reasm queue sorted by TSN.
 620         * Walk through the queue sequentially and look for a sequence of
 621         * fragmented chunks that start a datagram.
 622         */
 623
 624        if (skb_queue_empty(&ulpq->reasm))
 625                return NULL;
 626
 627        last_frag = first_frag = NULL;
 628        retval = NULL;
 629        next_tsn = 0;
 630
 631        skb_queue_walk(&ulpq->reasm, pos) {
 632                cevent = sctp_skb2event(pos);
 633                ctsn = cevent->tsn;
 634
 635                switch (cevent->msg_flags & SCTP_DATA_FRAG_MASK) {
 636                case SCTP_DATA_FIRST_FRAG:
 637                        if (!first_frag) {
 638                                first_frag = pos;
 639                                next_tsn = ctsn + 1;
 640                                last_frag = pos;
 641                        } else
 642                                goto done;
 643                        break;
 644
 645                case SCTP_DATA_MIDDLE_FRAG:
 646                        if (!first_frag)
 647                                return NULL;
 648                        if (ctsn == next_tsn) {
 649                                next_tsn++;
 650                                last_frag = pos;
 651                        } else
 652                                goto done;
 653                        break;
 654                default:
 655                        return NULL;
 656                }
 657        }
 658
 659        /* We have the reassembled event. There is no need to look
 660         * further.
 661         */
 662done:
 663        retval = sctp_make_reassembled_event(sock_net(ulpq->asoc->base.sk),
 664                                        &ulpq->reasm, first_frag, last_frag);
 665        return retval;
 666}
 667
 668/*
 669 * Flush out stale fragments from the reassembly queue when processing
 670 * a Forward TSN.
 671 *
 672 * RFC 3758, Section 3.6
 673 *
 674 * After receiving and processing a FORWARD TSN, the data receiver MUST
 675 * take cautions in updating its re-assembly queue.  The receiver MUST
 676 * remove any partially reassembled message, which is still missing one
 677 * or more TSNs earlier than or equal to the new cumulative TSN point.
 678 * In the event that the receiver has invoked the partial delivery API,
 679 * a notification SHOULD also be generated to inform the upper layer API
 680 * that the message being partially delivered will NOT be completed.
 681 */
 682void sctp_ulpq_reasm_flushtsn(struct sctp_ulpq *ulpq, __u32 fwd_tsn)
 683{
 684        struct sk_buff *pos, *tmp;
 685        struct sctp_ulpevent *event;
 686        __u32 tsn;
 687
 688        if (skb_queue_empty(&ulpq->reasm))
 689                return;
 690
 691        skb_queue_walk_safe(&ulpq->reasm, pos, tmp) {
 692                event = sctp_skb2event(pos);
 693                tsn = event->tsn;
 694
 695                /* Since the entire message must be abandoned by the
 696                 * sender (item A3 in Section 3.5, RFC 3758), we can
 697                 * free all fragments on the list that are less then
 698                 * or equal to ctsn_point
 699                 */
 700                if (TSN_lte(tsn, fwd_tsn)) {
 701                        __skb_unlink(pos, &ulpq->reasm);
 702                        sctp_ulpevent_free(event);
 703                } else
 704                        break;
 705        }
 706}
 707
 708/*
 709 * Drain the reassembly queue.  If we just cleared parted delivery, it
 710 * is possible that the reassembly queue will contain already reassembled
 711 * messages.  Retrieve any such messages and give them to the user.
 712 */
 713static void sctp_ulpq_reasm_drain(struct sctp_ulpq *ulpq)
 714{
 715        struct sctp_ulpevent *event = NULL;
 716        struct sk_buff_head temp;
 717
 718        if (skb_queue_empty(&ulpq->reasm))
 719                return;
 720
 721        while ((event = sctp_ulpq_retrieve_reassembled(ulpq)) != NULL) {
 722                /* Do ordering if needed.  */
 723                if ((event) && (event->msg_flags & MSG_EOR)){
 724                        skb_queue_head_init(&temp);
 725                        __skb_queue_tail(&temp, sctp_event2skb(event));
 726
 727                        event = sctp_ulpq_order(ulpq, event);
 728                }
 729
 730                /* Send event to the ULP.  'event' is the
 731                 * sctp_ulpevent for  very first SKB on the  temp' list.
 732                 */
 733                if (event)
 734                        sctp_ulpq_tail_event(ulpq, event);
 735        }
 736}
 737
 738
 739/* Helper function to gather skbs that have possibly become
 740 * ordered by an an incoming chunk.
 741 */
 742static void sctp_ulpq_retrieve_ordered(struct sctp_ulpq *ulpq,
 743                                              struct sctp_ulpevent *event)
 744{
 745        struct sk_buff_head *event_list;
 746        struct sk_buff *pos, *tmp;
 747        struct sctp_ulpevent *cevent;
 748        struct sctp_stream *in;
 749        __u16 sid, csid, cssn;
 750
 751        sid = event->stream;
 752        in  = &ulpq->asoc->ssnmap->in;
 753
 754        event_list = (struct sk_buff_head *) sctp_event2skb(event)->prev;
 755
 756        /* We are holding the chunks by stream, by SSN.  */
 757        sctp_skb_for_each(pos, &ulpq->lobby, tmp) {
 758                cevent = (struct sctp_ulpevent *) pos->cb;
 759                csid = cevent->stream;
 760                cssn = cevent->ssn;
 761
 762                /* Have we gone too far?  */
 763                if (csid > sid)
 764                        break;
 765
 766                /* Have we not gone far enough?  */
 767                if (csid < sid)
 768                        continue;
 769
 770                if (cssn != sctp_ssn_peek(in, sid))
 771                        break;
 772
 773                /* Found it, so mark in the ssnmap. */
 774                sctp_ssn_next(in, sid);
 775
 776                __skb_unlink(pos, &ulpq->lobby);
 777
 778                /* Attach all gathered skbs to the event.  */
 779                __skb_queue_tail(event_list, pos);
 780        }
 781}
 782
 783/* Helper function to store chunks needing ordering.  */
 784static void sctp_ulpq_store_ordered(struct sctp_ulpq *ulpq,
 785                                           struct sctp_ulpevent *event)
 786{
 787        struct sk_buff *pos;
 788        struct sctp_ulpevent *cevent;
 789        __u16 sid, csid;
 790        __u16 ssn, cssn;
 791
 792        pos = skb_peek_tail(&ulpq->lobby);
 793        if (!pos) {
 794                __skb_queue_tail(&ulpq->lobby, sctp_event2skb(event));
 795                return;
 796        }
 797
 798        sid = event->stream;
 799        ssn = event->ssn;
 800
 801        cevent = (struct sctp_ulpevent *) pos->cb;
 802        csid = cevent->stream;
 803        cssn = cevent->ssn;
 804        if (sid > csid) {
 805                __skb_queue_tail(&ulpq->lobby, sctp_event2skb(event));
 806                return;
 807        }
 808
 809        if ((sid == csid) && SSN_lt(cssn, ssn)) {
 810                __skb_queue_tail(&ulpq->lobby, sctp_event2skb(event));
 811                return;
 812        }
 813
 814        /* Find the right place in this list.  We store them by
 815         * stream ID and then by SSN.
 816         */
 817        skb_queue_walk(&ulpq->lobby, pos) {
 818                cevent = (struct sctp_ulpevent *) pos->cb;
 819                csid = cevent->stream;
 820                cssn = cevent->ssn;
 821
 822                if (csid > sid)
 823                        break;
 824                if (csid == sid && SSN_lt(ssn, cssn))
 825                        break;
 826        }
 827
 828
 829        /* Insert before pos. */
 830        __skb_queue_before(&ulpq->lobby, pos, sctp_event2skb(event));
 831}
 832
 833static struct sctp_ulpevent *sctp_ulpq_order(struct sctp_ulpq *ulpq,
 834                                             struct sctp_ulpevent *event)
 835{
 836        __u16 sid, ssn;
 837        struct sctp_stream *in;
 838
 839        /* Check if this message needs ordering.  */
 840        if (SCTP_DATA_UNORDERED & event->msg_flags)
 841                return event;
 842
 843        /* Note: The stream ID must be verified before this routine.  */
 844        sid = event->stream;
 845        ssn = event->ssn;
 846        in  = &ulpq->asoc->ssnmap->in;
 847
 848        /* Is this the expected SSN for this stream ID?  */
 849        if (ssn != sctp_ssn_peek(in, sid)) {
 850                /* We've received something out of order, so find where it
 851                 * needs to be placed.  We order by stream and then by SSN.
 852                 */
 853                sctp_ulpq_store_ordered(ulpq, event);
 854                return NULL;
 855        }
 856
 857        /* Mark that the next chunk has been found.  */
 858        sctp_ssn_next(in, sid);
 859
 860        /* Go find any other chunks that were waiting for
 861         * ordering.
 862         */
 863        sctp_ulpq_retrieve_ordered(ulpq, event);
 864
 865        return event;
 866}
 867
 868/* Helper function to gather skbs that have possibly become
 869 * ordered by forward tsn skipping their dependencies.
 870 */
 871static void sctp_ulpq_reap_ordered(struct sctp_ulpq *ulpq, __u16 sid)
 872{
 873        struct sk_buff *pos, *tmp;
 874        struct sctp_ulpevent *cevent;
 875        struct sctp_ulpevent *event;
 876        struct sctp_stream *in;
 877        struct sk_buff_head temp;
 878        struct sk_buff_head *lobby = &ulpq->lobby;
 879        __u16 csid, cssn;
 880
 881        in  = &ulpq->asoc->ssnmap->in;
 882
 883        /* We are holding the chunks by stream, by SSN.  */
 884        skb_queue_head_init(&temp);
 885        event = NULL;
 886        sctp_skb_for_each(pos, lobby, tmp) {
 887                cevent = (struct sctp_ulpevent *) pos->cb;
 888                csid = cevent->stream;
 889                cssn = cevent->ssn;
 890
 891                /* Have we gone too far?  */
 892                if (csid > sid)
 893                        break;
 894
 895                /* Have we not gone far enough?  */
 896                if (csid < sid)
 897                        continue;
 898
 899                /* see if this ssn has been marked by skipping */
 900                if (!SSN_lt(cssn, sctp_ssn_peek(in, csid)))
 901                        break;
 902
 903                __skb_unlink(pos, lobby);
 904                if (!event)
 905                        /* Create a temporary list to collect chunks on.  */
 906                        event = sctp_skb2event(pos);
 907
 908                /* Attach all gathered skbs to the event.  */
 909                __skb_queue_tail(&temp, pos);
 910        }
 911
 912        /* If we didn't reap any data, see if the next expected SSN
 913         * is next on the queue and if so, use that.
 914         */
 915        if (event == NULL && pos != (struct sk_buff *)lobby) {
 916                cevent = (struct sctp_ulpevent *) pos->cb;
 917                csid = cevent->stream;
 918                cssn = cevent->ssn;
 919
 920                if (csid == sid && cssn == sctp_ssn_peek(in, csid)) {
 921                        sctp_ssn_next(in, csid);
 922                        __skb_unlink(pos, lobby);
 923                        __skb_queue_tail(&temp, pos);
 924                        event = sctp_skb2event(pos);
 925                }
 926        }
 927
 928        /* Send event to the ULP.  'event' is the sctp_ulpevent for
 929         * very first SKB on the 'temp' list.
 930         */
 931        if (event) {
 932                /* see if we have more ordered that we can deliver */
 933                sctp_ulpq_retrieve_ordered(ulpq, event);
 934                sctp_ulpq_tail_event(ulpq, event);
 935        }
 936}
 937
 938/* Skip over an SSN. This is used during the processing of
 939 * Forwared TSN chunk to skip over the abandoned ordered data
 940 */
 941void sctp_ulpq_skip(struct sctp_ulpq *ulpq, __u16 sid, __u16 ssn)
 942{
 943        struct sctp_stream *in;
 944
 945        /* Note: The stream ID must be verified before this routine.  */
 946        in  = &ulpq->asoc->ssnmap->in;
 947
 948        /* Is this an old SSN?  If so ignore. */
 949        if (SSN_lt(ssn, sctp_ssn_peek(in, sid)))
 950                return;
 951
 952        /* Mark that we are no longer expecting this SSN or lower. */
 953        sctp_ssn_skip(in, sid, ssn);
 954
 955        /* Go find any other chunks that were waiting for
 956         * ordering and deliver them if needed.
 957         */
 958        sctp_ulpq_reap_ordered(ulpq, sid);
 959}
 960
 961static __u16 sctp_ulpq_renege_list(struct sctp_ulpq *ulpq,
 962                struct sk_buff_head *list, __u16 needed)
 963{
 964        __u16 freed = 0;
 965        __u32 tsn;
 966        struct sk_buff *skb;
 967        struct sctp_ulpevent *event;
 968        struct sctp_tsnmap *tsnmap;
 969
 970        tsnmap = &ulpq->asoc->peer.tsn_map;
 971
 972        while ((skb = __skb_dequeue_tail(list)) != NULL) {
 973                freed += skb_headlen(skb);
 974                event = sctp_skb2event(skb);
 975                tsn = event->tsn;
 976
 977                sctp_ulpevent_free(event);
 978                sctp_tsnmap_renege(tsnmap, tsn);
 979                if (freed >= needed)
 980                        return freed;
 981        }
 982
 983        return freed;
 984}
 985
 986/* Renege 'needed' bytes from the ordering queue. */
 987static __u16 sctp_ulpq_renege_order(struct sctp_ulpq *ulpq, __u16 needed)
 988{
 989        return sctp_ulpq_renege_list(ulpq, &ulpq->lobby, needed);
 990}
 991
 992/* Renege 'needed' bytes from the reassembly queue. */
 993static __u16 sctp_ulpq_renege_frags(struct sctp_ulpq *ulpq, __u16 needed)
 994{
 995        return sctp_ulpq_renege_list(ulpq, &ulpq->reasm, needed);
 996}
 997
 998/* Partial deliver the first message as there is pressure on rwnd. */
 999void sctp_ulpq_partial_delivery(struct sctp_ulpq *ulpq,
1000                                struct sctp_chunk *chunk,
1001                                gfp_t gfp)
1002{
1003        struct sctp_ulpevent *event;
1004        struct sctp_association *asoc;
1005        struct sctp_sock *sp;
1006
1007        asoc = ulpq->asoc;
1008        sp = sctp_sk(asoc->base.sk);
1009
1010        /* If the association is already in Partial Delivery mode
1011         * we have noting to do.
1012         */
1013        if (ulpq->pd_mode)
1014                return;
1015
1016        /* If the user enabled fragment interleave socket option,
1017         * multiple associations can enter partial delivery.
1018         * Otherwise, we can only enter partial delivery if the
1019         * socket is not in partial deliver mode.
1020         */
1021        if (sp->frag_interleave || atomic_read(&sp->pd_mode) == 0) {
1022                /* Is partial delivery possible?  */
1023                event = sctp_ulpq_retrieve_first(ulpq);
1024                /* Send event to the ULP.   */
1025                if (event) {
1026                        sctp_ulpq_tail_event(ulpq, event);
1027                        sctp_ulpq_set_pd(ulpq);
1028                        return;
1029                }
1030        }
1031}
1032
1033/* Renege some packets to make room for an incoming chunk.  */
1034void sctp_ulpq_renege(struct sctp_ulpq *ulpq, struct sctp_chunk *chunk,
1035                      gfp_t gfp)
1036{
1037        struct sctp_association *asoc;
1038        __u16 needed, freed;
1039
1040        asoc = ulpq->asoc;
1041
1042        if (chunk) {
1043                needed = ntohs(chunk->chunk_hdr->length);
1044                needed -= sizeof(sctp_data_chunk_t);
1045        } else
1046                needed = SCTP_DEFAULT_MAXWINDOW;
1047
1048        freed = 0;
1049
1050        if (skb_queue_empty(&asoc->base.sk->sk_receive_queue)) {
1051                freed = sctp_ulpq_renege_order(ulpq, needed);
1052                if (freed < needed) {
1053                        freed += sctp_ulpq_renege_frags(ulpq, needed - freed);
1054                }
1055        }
1056        /* If able to free enough room, accept this chunk. */
1057        if (chunk && (freed >= needed)) {
1058                __u32 tsn;
1059                tsn = ntohl(chunk->subh.data_hdr->tsn);
1060                sctp_tsnmap_mark(&asoc->peer.tsn_map, tsn, chunk->transport);
1061                sctp_ulpq_tail_data(ulpq, chunk, gfp);
1062
1063                sctp_ulpq_partial_delivery(ulpq, chunk, gfp);
1064        }
1065
1066        sk_mem_reclaim(asoc->base.sk);
1067}
1068
1069
1070
1071/* Notify the application if an association is aborted and in
1072 * partial delivery mode.  Send up any pending received messages.
1073 */
1074void sctp_ulpq_abort_pd(struct sctp_ulpq *ulpq, gfp_t gfp)
1075{
1076        struct sctp_ulpevent *ev = NULL;
1077        struct sock *sk;
1078
1079        if (!ulpq->pd_mode)
1080                return;
1081
1082        sk = ulpq->asoc->base.sk;
1083        if (sctp_ulpevent_type_enabled(SCTP_PARTIAL_DELIVERY_EVENT,
1084                                       &sctp_sk(sk)->subscribe))
1085                ev = sctp_ulpevent_make_pdapi(ulpq->asoc,
1086                                              SCTP_PARTIAL_DELIVERY_ABORTED,
1087                                              gfp);
1088        if (ev)
1089                __skb_queue_tail(&sk->sk_receive_queue, sctp_event2skb(ev));
1090
1091        /* If there is data waiting, send it up the socket now. */
1092        if (sctp_ulpq_clear_pd(ulpq) || ev)
1093                sk->sk_data_ready(sk, 0);
1094}
1095
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