linux/net/sctp/inqueue.c
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   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.  */
  54void 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        queue->malloced = 0;
  63}
  64
  65/* Release the memory associated with an SCTP inqueue.  */
  66void sctp_inq_free(struct sctp_inq *queue)
  67{
  68        struct sctp_chunk *chunk, *tmp;
  69
  70        /* Empty the queue.  */
  71        list_for_each_entry_safe(chunk, tmp, &queue->in_chunk_list, list) {
  72                list_del_init(&chunk->list);
  73                sctp_chunk_free(chunk);
  74        }
  75
  76        /* If there is a packet which is currently being worked on,
  77         * free it as well.
  78         */
  79        if (queue->in_progress) {
  80                sctp_chunk_free(queue->in_progress);
  81                queue->in_progress = NULL;
  82        }
  83
  84        if (queue->malloced) {
  85                /* Dump the master memory segment.  */
  86                kfree(queue);
  87        }
  88}
  89
  90/* Put a new packet in an SCTP inqueue.
  91 * We assume that packet->sctp_hdr is set and in host byte order.
  92 */
  93void sctp_inq_push(struct sctp_inq *q, struct sctp_chunk *chunk)
  94{
  95        /* Directly call the packet handling routine. */
  96        if (chunk->rcvr->dead) {
  97                sctp_chunk_free(chunk);
  98                return;
  99        }
 100
 101        /* We are now calling this either from the soft interrupt
 102         * or from the backlog processing.
 103         * Eventually, we should clean up inqueue to not rely
 104         * on the BH related data structures.
 105         */
 106        list_add_tail(&chunk->list, &q->in_chunk_list);
 107        q->immediate.func(&q->immediate);
 108}
 109
 110/* Peek at the next chunk on the inqeue. */
 111struct sctp_chunkhdr *sctp_inq_peek(struct sctp_inq *queue)
 112{
 113        struct sctp_chunk *chunk;
 114        sctp_chunkhdr_t *ch = NULL;
 115
 116        chunk = queue->in_progress;
 117        /* If there is no more chunks in this packet, say so */
 118        if (chunk->singleton ||
 119            chunk->end_of_packet ||
 120            chunk->pdiscard)
 121                    return NULL;
 122
 123        ch = (sctp_chunkhdr_t *)chunk->chunk_end;
 124
 125        return ch;
 126}
 127
 128
 129/* Extract a chunk from an SCTP inqueue.
 130 *
 131 * WARNING:  If you need to put the chunk on another queue, you need to
 132 * make a shallow copy (clone) of it.
 133 */
 134struct sctp_chunk *sctp_inq_pop(struct sctp_inq *queue)
 135{
 136        struct sctp_chunk *chunk;
 137        sctp_chunkhdr_t *ch = NULL;
 138
 139        /* The assumption is that we are safe to process the chunks
 140         * at this time.
 141         */
 142
 143        if ((chunk = queue->in_progress)) {
 144                /* There is a packet that we have been working on.
 145                 * Any post processing work to do before we move on?
 146                 */
 147                if (chunk->singleton ||
 148                    chunk->end_of_packet ||
 149                    chunk->pdiscard) {
 150                        sctp_chunk_free(chunk);
 151                        chunk = queue->in_progress = NULL;
 152                } else {
 153                        /* Nothing to do. Next chunk in the packet, please. */
 154                        ch = (sctp_chunkhdr_t *) chunk->chunk_end;
 155
 156                        /* Force chunk->skb->data to chunk->chunk_end.  */
 157                        skb_pull(chunk->skb,
 158                                 chunk->chunk_end - chunk->skb->data);
 159
 160                        /* Verify that we have at least chunk headers
 161                         * worth of buffer left.
 162                         */
 163                        if (skb_headlen(chunk->skb) < sizeof(sctp_chunkhdr_t)) {
 164                                sctp_chunk_free(chunk);
 165                                chunk = queue->in_progress = NULL;
 166                        }
 167                }
 168        }
 169
 170        /* Do we need to take the next packet out of the queue to process? */
 171        if (!chunk) {
 172                struct list_head *entry;
 173
 174                /* Is the queue empty?  */
 175                if (list_empty(&queue->in_chunk_list))
 176                        return NULL;
 177
 178                entry = queue->in_chunk_list.next;
 179                chunk = queue->in_progress =
 180                        list_entry(entry, struct sctp_chunk, list);
 181                list_del_init(entry);
 182
 183                /* This is the first chunk in the packet.  */
 184                chunk->singleton = 1;
 185                ch = (sctp_chunkhdr_t *) chunk->skb->data;
 186                chunk->data_accepted = 0;
 187        }
 188
 189        chunk->chunk_hdr = ch;
 190        chunk->chunk_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
 191        /* In the unlikely case of an IP reassembly, the skb could be
 192         * non-linear. If so, update chunk_end so that it doesn't go past
 193         * the skb->tail.
 194         */
 195        if (unlikely(skb_is_nonlinear(chunk->skb))) {
 196                if (chunk->chunk_end > skb_tail_pointer(chunk->skb))
 197                        chunk->chunk_end = skb_tail_pointer(chunk->skb);
 198        }
 199        skb_pull(chunk->skb, sizeof(sctp_chunkhdr_t));
 200        chunk->subh.v = NULL; /* Subheader is no longer valid.  */
 201
 202        if (chunk->chunk_end < skb_tail_pointer(chunk->skb)) {
 203                /* This is not a singleton */
 204                chunk->singleton = 0;
 205        } else if (chunk->chunk_end > skb_tail_pointer(chunk->skb)) {
 206                /* RFC 2960, Section 6.10  Bundling
 207                 *
 208                 * Partial chunks MUST NOT be placed in an SCTP packet.
 209                 * If the receiver detects a partial chunk, it MUST drop
 210                 * the chunk.
 211                 *
 212                 * Since the end of the chunk is past the end of our buffer
 213                 * (which contains the whole packet, we can freely discard
 214                 * the whole packet.
 215                 */
 216                sctp_chunk_free(chunk);
 217                chunk = queue->in_progress = NULL;
 218
 219                return NULL;
 220        } else {
 221                /* We are at the end of the packet, so mark the chunk
 222                 * in case we need to send a SACK.
 223                 */
 224                chunk->end_of_packet = 1;
 225        }
 226
 227        SCTP_DEBUG_PRINTK("+++sctp_inq_pop+++ chunk %p[%s],"
 228                          " length %d, skb->len %d\n",chunk,
 229                          sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)),
 230                          ntohs(chunk->chunk_hdr->length), chunk->skb->len);
 231        return chunk;
 232}
 233
 234/* Set a top-half handler.
 235 *
 236 * Originally, we the top-half handler was scheduled as a BH.  We now
 237 * call the handler directly in sctp_inq_push() at a time that
 238 * we know we are lock safe.
 239 * The intent is that this routine will pull stuff out of the
 240 * inqueue and process it.
 241 */
 242void sctp_inq_set_th_handler(struct sctp_inq *q, work_func_t callback)
 243{
 244        INIT_WORK(&q->immediate, callback);
 245}
 246
 247
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