net/sctp/inqueue.c

   1 /* SCTP kernel implementation
   2  * Copyright (c) 1999-2000 Cisco, Inc.
   3  * Copyright (c) 1999-2001 Motorola, Inc.
   4  * Copyright (c) 2002 International Business Machines, Corp.
   5  *
   6  * This file is part of the SCTP kernel implementation
   7  *
   8  * These functions are the methods for accessing the SCTP inqueue.
   9  *
  10  * An SCTP inqueue is a queue into which you push SCTP packets
  11  * (which might be bundles or fragments of chunks) and out of which you
  12  * pop SCTP whole chunks.
  13  *
  14  * This SCTP implementation is free software;
  15  * you can redistribute it and/or modify it under the terms of
  16  * the GNU General Public License as published by
  17  * the Free Software Foundation; either version 2, or (at your option)
  18  * any later version.
  19  *
  20  * This SCTP implementation is distributed in the hope that it
  21  * will be useful, but WITHOUT ANY WARRANTY; without even the implied
  22  *                 ************************
  23  * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  24  * See the GNU General Public License for more details.
  25  *
  26  * You should have received a copy of the GNU General Public License
  27  * along with GNU CC; see the file COPYING.  If not, write to
  28  * the Free Software Foundation, 59 Temple Place - Suite 330,
  29  * Boston, MA 02111-1307, USA.
  30  *
  31  * Please send any bug reports or fixes you make to the
  32  * email address(es):
  33  *    lksctp developers <lksctp-developers@lists.sourceforge.net>
  34  *
  35  * Or submit a bug report through the following website:
  36  *    http://www.sf.net/projects/lksctp
  37  *
  38  * Written or modified by:
  39  *    La Monte H.P. Yarroll <piggy@acm.org>
  40  *    Karl Knutson <karl@athena.chicago.il.us>
  41  *
  42  * Any bugs reported given to us we will try to fix... any fixes shared will
  43  * be incorporated into the next SCTP release.
  44  */
  45
  46 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  47
  48 #include <net/sctp/sctp.h>
  49 #include <net/sctp/sm.h>
  50 #include <linux/interrupt.h>
  51 #include <linux/slab.h>
  52
  53 /* Initialize an SCTP inqueue.  */
  54 void sctp_inq_init(struct sctp_inq *queue)
  55 {
  56         INIT_LIST_HEAD(&queue->in_chunk_list);
  57         queue->in_progress = NULL;
  58
  59         /* Create a task for delivering data.  */
  60         INIT_WORK(&queue->immediate, NULL);
  61 }
  62
  63 /* Release the memory associated with an SCTP inqueue.  */
  64 void sctp_inq_free(struct sctp_inq *queue)
  65 {
  66         struct sctp_chunk *chunk, *tmp;
  67
  68         /* Empty the queue.  */
  69         list_for_each_entry_safe(chunk, tmp, &queue->in_chunk_list, list) {
  70                 list_del_init(&chunk->list);
  71                 sctp_chunk_free(chunk);
  72         }
  73
  74         /* If there is a packet which is currently being worked on,
  75          * free it as well.
  76          */
  77         if (queue->in_progress) {
  78                 sctp_chunk_free(queue->in_progress);
  79                 queue->in_progress = NULL;
  80         }
  81 }
  82
  83 /* Put a new packet in an SCTP inqueue.
  84  * We assume that packet->sctp_hdr is set and in host byte order.
  85  */
  86 void sctp_inq_push(struct sctp_inq *q, struct sctp_chunk *chunk)
  87 {
  88         /* Directly call the packet handling routine. */
  89         if (chunk->rcvr->dead) {
  90                 sctp_chunk_free(chunk);
  91                 return;
  92         }
  93
  94         /* We are now calling this either from the soft interrupt
  95          * or from the backlog processing.
  96          * Eventually, we should clean up inqueue to not rely
  97          * on the BH related data structures.
  98          */
  99         list_add_tail(&chunk->list, &q->in_chunk_list);
 100         if (chunk->asoc)
 101                 chunk->asoc->stats.ipackets++;
 102         q->immediate.func(&q->immediate);
 103 }
 104
 105 /* Peek at the next chunk on the inqeue. */
 106 struct sctp_chunkhdr *sctp_inq_peek(struct sctp_inq *queue)
 107 {
 108         struct sctp_chunk *chunk;
 109         sctp_chunkhdr_t *ch = NULL;
 110
 111         chunk = queue->in_progress;
 112         /* If there is no more chunks in this packet, say so */
 113         if (chunk->singleton ||
 114             chunk->end_of_packet ||
 115             chunk->pdiscard)
 116                     return NULL;
 117
 118         ch = (sctp_chunkhdr_t *)chunk->chunk_end;
 119
 120         return ch;
 121 }
 122
 123
 124 /* Extract a chunk from an SCTP inqueue.
 125  *
 126  * WARNING:  If you need to put the chunk on another queue, you need to
 127  * make a shallow copy (clone) of it.
 128  */
 129 struct sctp_chunk *sctp_inq_pop(struct sctp_inq *queue)
 130 {
 131         struct sctp_chunk *chunk;
 132         sctp_chunkhdr_t *ch = NULL;
 133
 134         /* The assumption is that we are safe to process the chunks
 135          * at this time.
 136          */
 137
 138         if ((chunk = queue->in_progress)) {
 139                 /* There is a packet that we have been working on.
 140                  * Any post processing work to do before we move on?
 141                  */
 142                 if (chunk->singleton ||
 143                     chunk->end_of_packet ||
 144                     chunk->pdiscard) {
 145                         sctp_chunk_free(chunk);
 146                         chunk = queue->in_progress = NULL;
 147                 } else {
 148                         /* Nothing to do. Next chunk in the packet, please. */
 149                         ch = (sctp_chunkhdr_t *) chunk->chunk_end;
 150
 151                         /* Force chunk->skb->data to chunk->chunk_end.  */
 152                         skb_pull(chunk->skb,
 153                                  chunk->chunk_end - chunk->skb->data);
 154
 155                         /* Verify that we have at least chunk headers
 156                          * worth of buffer left.
 157                          */
 158                         if (skb_headlen(chunk->skb) < sizeof(sctp_chunkhdr_t)) {
 159                                 sctp_chunk_free(chunk);
 160                                 chunk = queue->in_progress = NULL;
 161                         }
 162                 }
 163         }
 164
 165         /* Do we need to take the next packet out of the queue to process? */
 166         if (!chunk) {
 167                 struct list_head *entry;
 168
 169                 /* Is the queue empty?  */
 170                 if (list_empty(&queue->in_chunk_list))
 171                         return NULL;
 172
 173                 entry = queue->in_chunk_list.next;
 174                 chunk = queue->in_progress =
 175                         list_entry(entry, struct sctp_chunk, list);
 176                 list_del_init(entry);
 177
 178                 /* This is the first chunk in the packet.  */
 179                 chunk->singleton = 1;
 180                 ch = (sctp_chunkhdr_t *) chunk->skb->data;
 181                 chunk->data_accepted = 0;
 182         }
 183
 184         chunk->chunk_hdr = ch;
 185         chunk->chunk_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
 186         /* In the unlikely case of an IP reassembly, the skb could be
 187          * non-linear. If so, update chunk_end so that it doesn't go past
 188          * the skb->tail.
 189          */
 190         if (unlikely(skb_is_nonlinear(chunk->skb))) {
 191                 if (chunk->chunk_end > skb_tail_pointer(chunk->skb))
 192                         chunk->chunk_end = skb_tail_pointer(chunk->skb);
 193         }
 194         skb_pull(chunk->skb, sizeof(sctp_chunkhdr_t));
 195         chunk->subh.v = NULL; /* Subheader is no longer valid.  */
 196
 197         if (chunk->chunk_end < skb_tail_pointer(chunk->skb)) {
 198                 /* This is not a singleton */
 199                 chunk->singleton = 0;
 200         } else if (chunk->chunk_end > skb_tail_pointer(chunk->skb)) {
 201                 /* RFC 2960, Section 6.10  Bundling
 202                  *
 203                  * Partial chunks MUST NOT be placed in an SCTP packet.
 204                  * If the receiver detects a partial chunk, it MUST drop
 205                  * the chunk.
 206                  *
 207                  * Since the end of the chunk is past the end of our buffer
 208                  * (which contains the whole packet, we can freely discard
 209                  * the whole packet.
 210                  */
 211                 sctp_chunk_free(chunk);
 212                 chunk = queue->in_progress = NULL;
 213
 214                 return NULL;
 215         } else {
 216                 /* We are at the end of the packet, so mark the chunk
 217                  * in case we need to send a SACK.
 218                  */
 219                 chunk->end_of_packet = 1;
 220         }
 221
 222         SCTP_DEBUG_PRINTK("+++sctp_inq_pop+++ chunk %p[%s],"
 223                           " length %d, skb->len %d\n",chunk,
 224                           sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)),
 225                           ntohs(chunk->chunk_hdr->length), chunk->skb->len);
 226         return chunk;
 227 }
 228
 229 /* Set a top-half handler.
 230  *
 231  * Originally, we the top-half handler was scheduled as a BH.  We now
 232  * call the handler directly in sctp_inq_push() at a time that
 233  * we know we are lock safe.
 234  * The intent is that this routine will pull stuff out of the
 235  * inqueue and process it.
 236  */
 237 void sctp_inq_set_th_handler(struct sctp_inq *q, work_func_t callback)
 238 {
 239         INIT_WORK(&q->immediate, callback);
 240 }
 241