net/sctp/ulpqueue.c

   1 /* SCTP kernel reference Implementation
   2  * (C) Copyright IBM Corp. 2001, 2004
   3  * Copyright (c) 1999-2000 Cisco, Inc.
   4  * Copyright (c) 1999-2001 Motorola, Inc.
   5  * Copyright (c) 2001 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  * The SCTP reference 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  * The SCTP reference 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/types.h>
  45 #include <linux/skbuff.h>
  46 #include <net/sock.h>
  47 #include <net/sctp/structs.h>
  48 #include <net/sctp/sctp.h>
  49 #include <net/sctp/sm.h>
  50
  51 /* Forward declarations for internal helpers.  */
  52 static struct sctp_ulpevent * sctp_ulpq_reasm(struct sctp_ulpq *ulpq,
  53                                               struct sctp_ulpevent *);
  54 static struct sctp_ulpevent * sctp_ulpq_order(struct sctp_ulpq *,
  55                                               struct sctp_ulpevent *);
  56
  57 /* 1st Level Abstractions */
  58
  59 /* Initialize a ULP queue from a block of memory.  */
  60 struct sctp_ulpq *sctp_ulpq_init(struct sctp_ulpq *ulpq,
  61                                  struct sctp_association *asoc)
  62 {
  63         memset(ulpq, 0, sizeof(struct sctp_ulpq));
  64
  65         ulpq->asoc = asoc;
  66         skb_queue_head_init(&ulpq->reasm);
  67         skb_queue_head_init(&ulpq->lobby);
  68         ulpq->pd_mode  = 0;
  69         ulpq->malloced = 0;
  70
  71         return ulpq;
  72 }
  73
  74
  75 /* Flush the reassembly and ordering queues.  */
  76 static void sctp_ulpq_flush(struct sctp_ulpq *ulpq)
  77 {
  78         struct sk_buff *skb;
  79         struct sctp_ulpevent *event;
  80
  81         while ((skb = __skb_dequeue(&ulpq->lobby)) != NULL) {
  82                 event = sctp_skb2event(skb);
  83                 sctp_ulpevent_free(event);
  84         }
  85
  86         while ((skb = __skb_dequeue(&ulpq->reasm)) != NULL) {
  87                 event = sctp_skb2event(skb);
  88                 sctp_ulpevent_free(event);
  89         }
  90
  91 }
  92
  93 /* Dispose of a ulpqueue.  */
  94 void sctp_ulpq_free(struct sctp_ulpq *ulpq)
  95 {
  96         sctp_ulpq_flush(ulpq);
  97         if (ulpq->malloced)
  98                 kfree(ulpq);
  99 }
 100
 101 /* Process an incoming DATA chunk.  */
 102 int sctp_ulpq_tail_data(struct sctp_ulpq *ulpq, struct sctp_chunk *chunk,
 103                         gfp_t gfp)
 104 {
 105         struct sk_buff_head temp;
 106         sctp_data_chunk_t *hdr;
 107         struct sctp_ulpevent *event;
 108
 109         hdr = (sctp_data_chunk_t *) chunk->chunk_hdr;
 110
 111         /* Create an event from the incoming chunk. */
 112         event = sctp_ulpevent_make_rcvmsg(chunk->asoc, chunk, gfp);
 113         if (!event)
 114                 return -ENOMEM;
 115
 116         /* Do reassembly if needed.  */
 117         event = sctp_ulpq_reasm(ulpq, event);
 118
 119         /* Do ordering if needed.  */
 120         if ((event) && (event->msg_flags & MSG_EOR)){
 121                 /* Create a temporary list to collect chunks on.  */
 122                 skb_queue_head_init(&temp);
 123                 __skb_queue_tail(&temp, sctp_event2skb(event));
 124
 125                 event = sctp_ulpq_order(ulpq, event);
 126         }
 127
 128         /* Send event to the ULP.  'event' is the sctp_ulpevent for
 129          * very first SKB on the 'temp' list.
 130          */
 131         if (event)
 132                 sctp_ulpq_tail_event(ulpq, event);
 133
 134         return 0;
 135 }
 136
 137 /* Add a new event for propagation to the ULP.  */
 138 /* Clear the partial delivery mode for this socket.   Note: This
 139  * assumes that no association is currently in partial delivery mode.
 140  */
 141 int sctp_clear_pd(struct sock *sk)
 142 {
 143         struct sctp_sock *sp = sctp_sk(sk);
 144
 145         sp->pd_mode = 0;
 146         if (!skb_queue_empty(&sp->pd_lobby)) {
 147                 struct list_head *list;
 148                 sctp_skb_list_tail(&sp->pd_lobby, &sk->sk_receive_queue);
 149                 list = (struct list_head *)&sctp_sk(sk)->pd_lobby;
 150                 INIT_LIST_HEAD(list);
 151                 return 1;
 152         }
 153         return 0;
 154 }
 155
 156 /* Clear the pd_mode and restart any pending messages waiting for delivery. */
 157 static int sctp_ulpq_clear_pd(struct sctp_ulpq *ulpq)
 158 {
 159         ulpq->pd_mode = 0;
 160         return sctp_clear_pd(ulpq->asoc->base.sk);
 161 }
 162
 163 /* If the SKB of 'event' is on a list, it is the first such member
 164  * of that list.
 165  */
 166 int sctp_ulpq_tail_event(struct sctp_ulpq *ulpq, struct sctp_ulpevent *event)
 167 {
 168         struct sock *sk = ulpq->asoc->base.sk;
 169         struct sk_buff_head *queue, *skb_list;
 170         struct sk_buff *skb = sctp_event2skb(event);
 171         int clear_pd = 0;
 172
 173         skb_list = (struct sk_buff_head *) skb->prev;
 174
 175         /* If the socket is just going to throw this away, do not
 176          * even try to deliver it.
 177          */
 178         if (sock_flag(sk, SOCK_DEAD) || (sk->sk_shutdown & RCV_SHUTDOWN))
 179                 goto out_free;
 180
 181         /* Check if the user wishes to receive this event.  */
 182         if (!sctp_ulpevent_is_enabled(event, &sctp_sk(sk)->subscribe))
 183                 goto out_free;
 184
 185         /* If we are in partial delivery mode, post to the lobby until
 186          * partial delivery is cleared, unless, of course _this_ is
 187          * the association the cause of the partial delivery.
 188          */
 189
 190         if (!sctp_sk(sk)->pd_mode) {
 191                 queue = &sk->sk_receive_queue;
 192         } else if (ulpq->pd_mode) {
 193                 if (event->msg_flags & MSG_NOTIFICATION)
 194                         queue = &sctp_sk(sk)->pd_lobby;
 195                 else {
 196                         clear_pd = event->msg_flags & MSG_EOR;
 197                         queue = &sk->sk_receive_queue;
 198                 }
 199         } else
 200                 queue = &sctp_sk(sk)->pd_lobby;
 201
 202
 203         /* If we are harvesting multiple skbs they will be
 204          * collected on a list.
 205          */
 206         if (skb_list)
 207                 sctp_skb_list_tail(skb_list, queue);
 208         else
 209                 __skb_queue_tail(queue, skb);
 210
 211         /* Did we just complete partial delivery and need to get
 212          * rolling again?  Move pending data to the receive
 213          * queue.
 214          */
 215         if (clear_pd)
 216                 sctp_ulpq_clear_pd(ulpq);
 217
 218         if (queue == &sk->sk_receive_queue)
 219                 sk->sk_data_ready(sk, 0);
 220         return 1;
 221
 222 out_free:
 223         if (skb_list)
 224                 sctp_queue_purge_ulpevents(skb_list);
 225         else
 226                 sctp_ulpevent_free(event);
 227
 228         return 0;
 229 }
 230
 231 /* 2nd Level Abstractions */
 232
 233 /* Helper function to store chunks that need to be reassembled.  */
 234 static inline void sctp_ulpq_store_reasm(struct sctp_ulpq *ulpq,
 235                                          struct sctp_ulpevent *event)
 236 {
 237         struct sk_buff *pos;
 238         struct sctp_ulpevent *cevent;
 239         __u32 tsn, ctsn;
 240
 241         tsn = event->tsn;
 242
 243         /* See if it belongs at the end. */
 244         pos = skb_peek_tail(&ulpq->reasm);
 245         if (!pos) {
 246                 __skb_queue_tail(&ulpq->reasm, sctp_event2skb(event));
 247                 return;
 248         }
 249
 250         /* Short circuit just dropping it at the end. */
 251         cevent = sctp_skb2event(pos);
 252         ctsn = cevent->tsn;
 253         if (TSN_lt(ctsn, tsn)) {
 254                 __skb_queue_tail(&ulpq->reasm, sctp_event2skb(event));
 255                 return;
 256         }
 257
 258         /* Find the right place in this list. We store them by TSN.  */
 259         skb_queue_walk(&ulpq->reasm, pos) {
 260                 cevent = sctp_skb2event(pos);
 261                 ctsn = cevent->tsn;
 262
 263                 if (TSN_lt(tsn, ctsn))
 264                         break;
 265         }
 266
 267         /* Insert before pos. */
 268         __skb_insert(sctp_event2skb(event), pos->prev, pos, &ulpq->reasm);
 269
 270 }
 271
 272 /* Helper function to return an event corresponding to the reassembled
 273  * datagram.
 274  * This routine creates a re-assembled skb given the first and last skb's
 275  * as stored in the reassembly queue. The skb's may be non-linear if the sctp
 276  * payload was fragmented on the way and ip had to reassemble them.
 277  * We add the rest of skb's to the first skb's fraglist.
 278  */
 279 static struct sctp_ulpevent *sctp_make_reassembled_event(struct sk_buff_head *queue, struct sk_buff *f_frag, struct sk_buff *l_frag)
 280 {
 281         struct sk_buff *pos;
 282         struct sk_buff *new = NULL;
 283         struct sctp_ulpevent *event;
 284         struct sk_buff *pnext, *last;
 285         struct sk_buff *list = skb_shinfo(f_frag)->frag_list;
 286
 287         /* Store the pointer to the 2nd skb */
 288         if (f_frag == l_frag)
 289                 pos = NULL;
 290         else
 291                 pos = f_frag->next;
 292
 293         /* Get the last skb in the f_frag's frag_list if present. */
 294         for (last = list; list; last = list, list = list->next);
 295
 296         /* Add the list of remaining fragments to the first fragments
 297          * frag_list.
 298          */
 299         if (last)
 300                 last->next = pos;
 301         else {
 302                 if (skb_cloned(f_frag)) {
 303                         /* This is a cloned skb, we can't just modify
 304                          * the frag_list.  We need a new skb to do that.
 305                          * Instead of calling skb_unshare(), we'll do it
 306                          * ourselves since we need to delay the free.
 307                          */
 308                         new = skb_copy(f_frag, GFP_ATOMIC);
 309                         if (!new)
 310                                 return NULL;    /* try again later */
 311
 312                         new->sk = f_frag->sk;
 313
 314                         skb_shinfo(new)->frag_list = pos;
 315                 } else
 316                         skb_shinfo(f_frag)->frag_list = pos;
 317         }
 318
 319         /* Remove the first fragment from the reassembly queue.  */
 320         __skb_unlink(f_frag, queue);
 321
 322         /* if we did unshare, then free the old skb and re-assign */
 323         if (new) {
 324                 kfree_skb(f_frag);
 325                 f_frag = new;
 326         }
 327
 328         while (pos) {
 329
 330                 pnext = pos->next;
 331
 332                 /* Update the len and data_len fields of the first fragment. */
 333                 f_frag->len += pos->len;
 334                 f_frag->data_len += pos->len;
 335
 336                 /* Remove the fragment from the reassembly queue.  */
 337                 __skb_unlink(pos, queue);
 338
 339                 /* Break if we have reached the last fragment.  */
 340                 if (pos == l_frag)
 341                         break;
 342                 pos->next = pnext;
 343                 pos = pnext;
 344         };
 345
 346         event = sctp_skb2event(f_frag);
 347         SCTP_INC_STATS(SCTP_MIB_REASMUSRMSGS);
 348
 349         return event;
 350 }
 351
 352
 353 /* Helper function to check if an incoming chunk has filled up the last
 354  * missing fragment in a SCTP datagram and return the corresponding event.
 355  */
 356 static inline struct sctp_ulpevent *sctp_ulpq_retrieve_reassembled(struct sctp_ulpq *ulpq)
 357 {
 358         struct sk_buff *pos;
 359         struct sctp_ulpevent *cevent;
 360         struct sk_buff *first_frag = NULL;
 361         __u32 ctsn, next_tsn;
 362         struct sctp_ulpevent *retval = NULL;
 363
 364         /* Initialized to 0 just to avoid compiler warning message.  Will
 365          * never be used with this value. It is referenced only after it
 366          * is set when we find the first fragment of a message.
 367          */
 368         next_tsn = 0;
 369
 370         /* The chunks are held in the reasm queue sorted by TSN.
 371          * Walk through the queue sequentially and look for a sequence of
 372          * fragmented chunks that complete a datagram.
 373          * 'first_frag' and next_tsn are reset when we find a chunk which
 374          * is the first fragment of a datagram. Once these 2 fields are set
 375          * we expect to find the remaining middle fragments and the last
 376          * fragment in order. If not, first_frag is reset to NULL and we
 377          * start the next pass when we find another first fragment.
 378          */
 379         skb_queue_walk(&ulpq->reasm, pos) {
 380                 cevent = sctp_skb2event(pos);
 381                 ctsn = cevent->tsn;
 382
 383                 switch (cevent->msg_flags & SCTP_DATA_FRAG_MASK) {
 384                 case SCTP_DATA_FIRST_FRAG:
 385                         first_frag = pos;
 386                         next_tsn = ctsn + 1;
 387                         break;
 388
 389                 case SCTP_DATA_MIDDLE_FRAG:
 390                         if ((first_frag) && (ctsn == next_tsn))
 391                                 next_tsn++;
 392                         else
 393                                 first_frag = NULL;
 394                         break;
 395
 396                 case SCTP_DATA_LAST_FRAG:
 397                         if (first_frag && (ctsn == next_tsn))
 398                                 goto found;
 399                         else
 400                                 first_frag = NULL;
 401                         break;
 402                 };
 403
 404         }
 405 done:
 406         return retval;
 407 found:
 408         retval = sctp_make_reassembled_event(&ulpq->reasm, first_frag, pos);
 409         if (retval)
 410                 retval->msg_flags |= MSG_EOR;
 411         goto done;
 412 }
 413
 414 /* Retrieve the next set of fragments of a partial message. */
 415 static inline struct sctp_ulpevent *sctp_ulpq_retrieve_partial(struct sctp_ulpq *ulpq)
 416 {
 417         struct sk_buff *pos, *last_frag, *first_frag;
 418         struct sctp_ulpevent *cevent;
 419         __u32 ctsn, next_tsn;
 420         int is_last;
 421         struct sctp_ulpevent *retval;
 422
 423         /* The chunks are held in the reasm queue sorted by TSN.
 424          * Walk through the queue sequentially and look for the first
 425          * sequence of fragmented chunks.
 426          */
 427
 428         if (skb_queue_empty(&ulpq->reasm))
 429                 return NULL;
 430
 431         last_frag = first_frag = NULL;
 432         retval = NULL;
 433         next_tsn = 0;
 434         is_last = 0;
 435
 436         skb_queue_walk(&ulpq->reasm, pos) {
 437                 cevent = sctp_skb2event(pos);
 438                 ctsn = cevent->tsn;
 439
 440                 switch (cevent->msg_flags & SCTP_DATA_FRAG_MASK) {
 441                 case SCTP_DATA_MIDDLE_FRAG:
 442                         if (!first_frag) {
 443                                 first_frag = pos;
 444                                 next_tsn = ctsn + 1;
 445                                 last_frag = pos;
 446                         } else if (next_tsn == ctsn)
 447                                 next_tsn++;
 448                         else
 449                                 goto done;
 450                         break;
 451                 case SCTP_DATA_LAST_FRAG:
 452                         if (!first_frag)
 453                                 first_frag = pos;
 454                         else if (ctsn != next_tsn)
 455                                 goto done;
 456                         last_frag = pos;
 457                         is_last = 1;
 458                         goto done;
 459                 default:
 460                         return NULL;
 461                 };
 462         }
 463
 464         /* We have the reassembled event. There is no need to look
 465          * further.
 466          */
 467 done:
 468         retval = sctp_make_reassembled_event(&ulpq->reasm, first_frag, last_frag);
 469         if (retval && is_last)
 470                 retval->msg_flags |= MSG_EOR;
 471
 472         return retval;
 473 }
 474
 475
 476 /* Helper function to reassemble chunks.  Hold chunks on the reasm queue that
 477  * need reassembling.
 478  */
 479 static struct sctp_ulpevent *sctp_ulpq_reasm(struct sctp_ulpq *ulpq,
 480                                                 struct sctp_ulpevent *event)
 481 {
 482         struct sctp_ulpevent *retval = NULL;
 483
 484         /* Check if this is part of a fragmented message.  */
 485         if (SCTP_DATA_NOT_FRAG == (event->msg_flags & SCTP_DATA_FRAG_MASK)) {
 486                 event->msg_flags |= MSG_EOR;
 487                 return event;
 488         }
 489
 490         sctp_ulpq_store_reasm(ulpq, event);
 491         if (!ulpq->pd_mode)
 492                 retval = sctp_ulpq_retrieve_reassembled(ulpq);
 493         else {
 494                 __u32 ctsn, ctsnap;
 495
 496                 /* Do not even bother unless this is the next tsn to
 497                  * be delivered.
 498                  */
 499                 ctsn = event->tsn;
 500                 ctsnap = sctp_tsnmap_get_ctsn(&ulpq->asoc->peer.tsn_map);
 501                 if (TSN_lte(ctsn, ctsnap))
 502                         retval = sctp_ulpq_retrieve_partial(ulpq);
 503         }
 504
 505         return retval;
 506 }
 507
 508 /* Retrieve the first part (sequential fragments) for partial delivery.  */
 509 static inline struct sctp_ulpevent *sctp_ulpq_retrieve_first(struct sctp_ulpq *ulpq)
 510 {
 511         struct sk_buff *pos, *last_frag, *first_frag;
 512         struct sctp_ulpevent *cevent;
 513         __u32 ctsn, next_tsn;
 514         struct sctp_ulpevent *retval;
 515
 516         /* The chunks are held in the reasm queue sorted by TSN.
 517          * Walk through the queue sequentially and look for a sequence of
 518          * fragmented chunks that start a datagram.
 519          */
 520
 521         if (skb_queue_empty(&ulpq->reasm))
 522                 return NULL;
 523
 524         last_frag = first_frag = NULL;
 525         retval = NULL;
 526         next_tsn = 0;
 527
 528         skb_queue_walk(&ulpq->reasm, pos) {
 529                 cevent = sctp_skb2event(pos);
 530                 ctsn = cevent->tsn;
 531
 532                 switch (cevent->msg_flags & SCTP_DATA_FRAG_MASK) {
 533                 case SCTP_DATA_FIRST_FRAG:
 534                         if (!first_frag) {
 535                                 first_frag = pos;
 536                                 next_tsn = ctsn + 1;
 537                                 last_frag = pos;
 538                         } else
 539                                 goto done;
 540                         break;
 541
 542                 case SCTP_DATA_MIDDLE_FRAG:
 543                         if (!first_frag)
 544                                 return NULL;
 545                         if (ctsn == next_tsn) {
 546                                 next_tsn++;
 547                                 last_frag = pos;
 548                         } else
 549                                 goto done;
 550                         break;
 551                 default:
 552                         return NULL;
 553                 };
 554         }
 555
 556         /* We have the reassembled event. There is no need to look
 557          * further.
 558          */
 559 done:
 560         retval = sctp_make_reassembled_event(&ulpq->reasm, first_frag, last_frag);
 561         return retval;
 562 }
 563
 564 /* Helper function to gather skbs that have possibly become
 565  * ordered by an an incoming chunk.
 566  */
 567 static inline void sctp_ulpq_retrieve_ordered(struct sctp_ulpq *ulpq,
 568                                               struct sctp_ulpevent *event)
 569 {
 570         struct sk_buff_head *event_list;
 571         struct sk_buff *pos, *tmp;
 572         struct sctp_ulpevent *cevent;
 573         struct sctp_stream *in;
 574         __u16 sid, csid;
 575         __u16 ssn, cssn;
 576
 577         sid = event->stream;
 578         ssn = event->ssn;
 579         in  = &ulpq->asoc->ssnmap->in;
 580
 581         event_list = (struct sk_buff_head *) sctp_event2skb(event)->prev;
 582
 583         /* We are holding the chunks by stream, by SSN.  */
 584         sctp_skb_for_each(pos, &ulpq->lobby, tmp) {
 585                 cevent = (struct sctp_ulpevent *) pos->cb;
 586                 csid = cevent->stream;
 587                 cssn = cevent->ssn;
 588
 589                 /* Have we gone too far?  */
 590                 if (csid > sid)
 591                         break;
 592
 593                 /* Have we not gone far enough?  */
 594                 if (csid < sid)
 595                         continue;
 596
 597                 if (cssn != sctp_ssn_peek(in, sid))
 598                         break;
 599
 600                 /* Found it, so mark in the ssnmap. */
 601                 sctp_ssn_next(in, sid);
 602
 603                 __skb_unlink(pos, &ulpq->lobby);
 604
 605                 /* Attach all gathered skbs to the event.  */
 606                 __skb_queue_tail(event_list, pos);
 607         }
 608 }
 609
 610 /* Helper function to store chunks needing ordering.  */
 611 static inline void sctp_ulpq_store_ordered(struct sctp_ulpq *ulpq,
 612                                            struct sctp_ulpevent *event)
 613 {
 614         struct sk_buff *pos;
 615         struct sctp_ulpevent *cevent;
 616         __u16 sid, csid;
 617         __u16 ssn, cssn;
 618
 619         pos = skb_peek_tail(&ulpq->lobby);
 620         if (!pos) {
 621                 __skb_queue_tail(&ulpq->lobby, sctp_event2skb(event));
 622                 return;
 623         }
 624
 625         sid = event->stream;
 626         ssn = event->ssn;
 627
 628         cevent = (struct sctp_ulpevent *) pos->cb;
 629         csid = cevent->stream;
 630         cssn = cevent->ssn;
 631         if (sid > csid) {
 632                 __skb_queue_tail(&ulpq->lobby, sctp_event2skb(event));
 633                 return;
 634         }
 635
 636         if ((sid == csid) && SSN_lt(cssn, ssn)) {
 637                 __skb_queue_tail(&ulpq->lobby, sctp_event2skb(event));
 638                 return;
 639         }
 640
 641         /* Find the right place in this list.  We store them by
 642          * stream ID and then by SSN.
 643          */
 644         skb_queue_walk(&ulpq->lobby, pos) {
 645                 cevent = (struct sctp_ulpevent *) pos->cb;
 646                 csid = cevent->stream;
 647                 cssn = cevent->ssn;
 648
 649                 if (csid > sid)
 650                         break;
 651                 if (csid == sid && SSN_lt(ssn, cssn))
 652                         break;
 653         }
 654
 655
 656         /* Insert before pos. */
 657         __skb_insert(sctp_event2skb(event), pos->prev, pos, &ulpq->lobby);
 658
 659 }
 660
 661 static struct sctp_ulpevent *sctp_ulpq_order(struct sctp_ulpq *ulpq,
 662                                              struct sctp_ulpevent *event)
 663 {
 664         __u16 sid, ssn;
 665         struct sctp_stream *in;
 666
 667         /* Check if this message needs ordering.  */
 668         if (SCTP_DATA_UNORDERED & event->msg_flags)
 669                 return event;
 670
 671         /* Note: The stream ID must be verified before this routine.  */
 672         sid = event->stream;
 673         ssn = event->ssn;
 674         in  = &ulpq->asoc->ssnmap->in;
 675
 676         /* Is this the expected SSN for this stream ID?  */
 677         if (ssn != sctp_ssn_peek(in, sid)) {
 678                 /* We've received something out of order, so find where it
 679                  * needs to be placed.  We order by stream and then by SSN.
 680                  */
 681                 sctp_ulpq_store_ordered(ulpq, event);
 682                 return NULL;
 683         }
 684
 685         /* Mark that the next chunk has been found.  */
 686         sctp_ssn_next(in, sid);
 687
 688         /* Go find any other chunks that were waiting for
 689          * ordering.
 690          */
 691         sctp_ulpq_retrieve_ordered(ulpq, event);
 692
 693         return event;
 694 }
 695
 696 /* Helper function to gather skbs that have possibly become
 697  * ordered by forward tsn skipping their dependencies.
 698  */
 699 static inline void sctp_ulpq_reap_ordered(struct sctp_ulpq *ulpq)
 700 {
 701         struct sk_buff *pos, *tmp;
 702         struct sctp_ulpevent *cevent;
 703         struct sctp_ulpevent *event;
 704         struct sctp_stream *in;
 705         struct sk_buff_head temp;
 706         __u16 csid, cssn;
 707
 708         in  = &ulpq->asoc->ssnmap->in;
 709
 710         /* We are holding the chunks by stream, by SSN.  */
 711         skb_queue_head_init(&temp);
 712         event = NULL;
 713         sctp_skb_for_each(pos, &ulpq->lobby, tmp) {
 714                 cevent = (struct sctp_ulpevent *) pos->cb;
 715                 csid = cevent->stream;
 716                 cssn = cevent->ssn;
 717
 718                 if (cssn != sctp_ssn_peek(in, csid))
 719                         break;
 720
 721                 /* Found it, so mark in the ssnmap. */
 722                 sctp_ssn_next(in, csid);
 723
 724                 __skb_unlink(pos, &ulpq->lobby);
 725                 if (!event) {
 726                         /* Create a temporary list to collect chunks on.  */
 727                         event = sctp_skb2event(pos);
 728                         __skb_queue_tail(&temp, sctp_event2skb(event));
 729                 } else {
 730                         /* Attach all gathered skbs to the event.  */
 731                         __skb_queue_tail(&temp, pos);
 732                 }
 733         }
 734
 735         /* Send event to the ULP.  'event' is the sctp_ulpevent for
 736          * very first SKB on the 'temp' list.
 737          */
 738         if (event)
 739                 sctp_ulpq_tail_event(ulpq, event);
 740 }
 741
 742 /* Skip over an SSN. */
 743 void sctp_ulpq_skip(struct sctp_ulpq *ulpq, __u16 sid, __u16 ssn)
 744 {
 745         struct sctp_stream *in;
 746
 747         /* Note: The stream ID must be verified before this routine.  */
 748         in  = &ulpq->asoc->ssnmap->in;
 749
 750         /* Is this an old SSN?  If so ignore. */
 751         if (SSN_lt(ssn, sctp_ssn_peek(in, sid)))
 752                 return;
 753
 754         /* Mark that we are no longer expecting this SSN or lower. */
 755         sctp_ssn_skip(in, sid, ssn);
 756
 757         /* Go find any other chunks that were waiting for
 758          * ordering and deliver them if needed.
 759          */
 760         sctp_ulpq_reap_ordered(ulpq);
 761         return;
 762 }
 763
 764 /* Renege 'needed' bytes from the ordering queue. */
 765 static __u16 sctp_ulpq_renege_order(struct sctp_ulpq *ulpq, __u16 needed)
 766 {
 767         __u16 freed = 0;
 768         __u32 tsn;
 769         struct sk_buff *skb;
 770         struct sctp_ulpevent *event;
 771         struct sctp_tsnmap *tsnmap;
 772
 773         tsnmap = &ulpq->asoc->peer.tsn_map;
 774
 775         while ((skb = __skb_dequeue_tail(&ulpq->lobby)) != NULL) {
 776                 freed += skb_headlen(skb);
 777                 event = sctp_skb2event(skb);
 778                 tsn = event->tsn;
 779
 780                 sctp_ulpevent_free(event);
 781                 sctp_tsnmap_renege(tsnmap, tsn);
 782                 if (freed >= needed)
 783                         return freed;
 784         }
 785
 786         return freed;
 787 }
 788
 789 /* Renege 'needed' bytes from the reassembly queue. */
 790 static __u16 sctp_ulpq_renege_frags(struct sctp_ulpq *ulpq, __u16 needed)
 791 {
 792         __u16 freed = 0;
 793         __u32 tsn;
 794         struct sk_buff *skb;
 795         struct sctp_ulpevent *event;
 796         struct sctp_tsnmap *tsnmap;
 797
 798         tsnmap = &ulpq->asoc->peer.tsn_map;
 799
 800         /* Walk backwards through the list, reneges the newest tsns. */
 801         while ((skb = __skb_dequeue_tail(&ulpq->reasm)) != NULL) {
 802                 freed += skb_headlen(skb);
 803                 event = sctp_skb2event(skb);
 804                 tsn = event->tsn;
 805
 806                 sctp_ulpevent_free(event);
 807                 sctp_tsnmap_renege(tsnmap, tsn);
 808                 if (freed >= needed)
 809                         return freed;
 810         }
 811
 812         return freed;
 813 }
 814
 815 /* Partial deliver the first message as there is pressure on rwnd. */
 816 void sctp_ulpq_partial_delivery(struct sctp_ulpq *ulpq,
 817                                 struct sctp_chunk *chunk,
 818                                 gfp_t gfp)
 819 {
 820         struct sctp_ulpevent *event;
 821         struct sctp_association *asoc;
 822
 823         asoc = ulpq->asoc;
 824
 825         /* Are we already in partial delivery mode?  */
 826         if (!sctp_sk(asoc->base.sk)->pd_mode) {
 827
 828                 /* Is partial delivery possible?  */
 829                 event = sctp_ulpq_retrieve_first(ulpq);
 830                 /* Send event to the ULP.   */
 831                 if (event) {
 832                         sctp_ulpq_tail_event(ulpq, event);
 833                         sctp_sk(asoc->base.sk)->pd_mode = 1;
 834                         ulpq->pd_mode = 1;
 835                         return;
 836                 }
 837         }
 838 }
 839
 840 /* Renege some packets to make room for an incoming chunk.  */
 841 void sctp_ulpq_renege(struct sctp_ulpq *ulpq, struct sctp_chunk *chunk,
 842                       gfp_t gfp)
 843 {
 844         struct sctp_association *asoc;
 845         __u16 needed, freed;
 846
 847         asoc = ulpq->asoc;
 848
 849         if (chunk) {
 850                 needed = ntohs(chunk->chunk_hdr->length);
 851                 needed -= sizeof(sctp_data_chunk_t);
 852         } else
 853                 needed = SCTP_DEFAULT_MAXWINDOW;
 854
 855         freed = 0;
 856
 857         if (skb_queue_empty(&asoc->base.sk->sk_receive_queue)) {
 858                 freed = sctp_ulpq_renege_order(ulpq, needed);
 859                 if (freed < needed) {
 860                         freed += sctp_ulpq_renege_frags(ulpq, needed - freed);
 861                 }
 862         }
 863         /* If able to free enough room, accept this chunk. */
 864         if (chunk && (freed >= needed)) {
 865                 __u32 tsn;
 866                 tsn = ntohl(chunk->subh.data_hdr->tsn);
 867                 sctp_tsnmap_mark(&asoc->peer.tsn_map, tsn);
 868                 sctp_ulpq_tail_data(ulpq, chunk, gfp);
 869
 870                 sctp_ulpq_partial_delivery(ulpq, chunk, gfp);
 871         }
 872
 873         return;
 874 }
 875
 876
 877
 878 /* Notify the application if an association is aborted and in
 879  * partial delivery mode.  Send up any pending received messages.
 880  */
 881 void sctp_ulpq_abort_pd(struct sctp_ulpq *ulpq, gfp_t gfp)
 882 {
 883         struct sctp_ulpevent *ev = NULL;
 884         struct sock *sk;
 885
 886         if (!ulpq->pd_mode)
 887                 return;
 888
 889         sk = ulpq->asoc->base.sk;
 890         if (sctp_ulpevent_type_enabled(SCTP_PARTIAL_DELIVERY_EVENT,
 891                                        &sctp_sk(sk)->subscribe))
 892                 ev = sctp_ulpevent_make_pdapi(ulpq->asoc,
 893                                               SCTP_PARTIAL_DELIVERY_ABORTED,
 894                                               gfp);
 895         if (ev)
 896                 __skb_queue_tail(&sk->sk_receive_queue, sctp_event2skb(ev));
 897
 898         /* If there is data waiting, send it up the socket now. */
 899         if (sctp_ulpq_clear_pd(ulpq) || ev)
 900                 sk->sk_data_ready(sk, 0);
 901 }