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#include <net/sctp/sctp.h>
  47#include <net/sctp/sm.h>
  48#include <linux/interrupt.h>
  49#include <linux/slab.h>
  50
  51/* Initialize an SCTP inqueue.  */
  52void sctp_inq_init(struct sctp_inq *queue)
  53{
  54        INIT_LIST_HEAD(&queue->in_chunk_list);
  55        queue->in_progress = NULL;
  56
  57        /* Create a task for delivering data.  */
  58        INIT_WORK(&queue->immediate, NULL);
  59
  60        queue->malloced = 0;
  61}
  62
  63/* Release the memory associated with an SCTP inqueue.  */
  64void 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        if (queue->malloced) {
  83                /* Dump the master memory segment.  */
  84                kfree(queue);
  85        }
  86}
  87
  88/* Put a new packet in an SCTP inqueue.
  89 * We assume that packet->sctp_hdr is set and in host byte order.
  90 */
  91void sctp_inq_push(struct sctp_inq *q, struct sctp_chunk *chunk)
  92{
  93        /* Directly call the packet handling routine. */
  94        if (chunk->rcvr->dead) {
  95                sctp_chunk_free(chunk);
  96                return;
  97        }
  98
  99        /* We are now calling this either from the soft interrupt
 100         * or from the backlog processing.
 101         * Eventually, we should clean up inqueue to not rely
 102         * on the BH related data structures.
 103         */
 104        list_add_tail(&chunk->list, &q->in_chunk_list);
 105        q->immediate.func(&q->immediate);
 106}
 107
 108/* Peek at the next chunk on the inqeue. */
 109struct sctp_chunkhdr *sctp_inq_peek(struct sctp_inq *queue)
 110{
 111        struct sctp_chunk *chunk;
 112        sctp_chunkhdr_t *ch = NULL;
 113
 114        chunk = queue->in_progress;
 115        /* If there is no more chunks in this packet, say so */
 116        if (chunk->singleton ||
 117            chunk->end_of_packet ||
 118            chunk->pdiscard)
 119                    return NULL;
 120
 121        ch = (sctp_chunkhdr_t *)chunk->chunk_end;
 122
 123        return ch;
 124}
 125
 126
 127/* Extract a chunk from an SCTP inqueue.
 128 *
 129 * WARNING:  If you need to put the chunk on another queue, you need to
 130 * make a shallow copy (clone) of it.
 131 */
 132struct sctp_chunk *sctp_inq_pop(struct sctp_inq *queue)
 133{
 134        struct sctp_chunk *chunk;
 135        sctp_chunkhdr_t *ch = NULL;
 136
 137        /* The assumption is that we are safe to process the chunks
 138         * at this time.
 139         */
 140
 141        if ((chunk = queue->in_progress)) {
 142                /* There is a packet that we have been working on.
 143                 * Any post processing work to do before we move on?
 144                 */
 145                if (chunk->singleton ||
 146                    chunk->end_of_packet ||
 147                    chunk->pdiscard) {
 148                        sctp_chunk_free(chunk);
 149                        chunk = queue->in_progress = NULL;
 150                } else {
 151                        /* Nothing to do. Next chunk in the packet, please. */
 152                        ch = (sctp_chunkhdr_t *) chunk->chunk_end;
 153
 154                        /* Force chunk->skb->data to chunk->chunk_end.  */
 155                        skb_pull(chunk->skb,
 156                                 chunk->chunk_end - chunk->skb->data);
 157
 158                        /* Verify that we have at least chunk headers
 159                         * worth of buffer left.
 160                         */
 161                        if (skb_headlen(chunk->skb) < sizeof(sctp_chunkhdr_t)) {
 162                                sctp_chunk_free(chunk);
 163                                chunk = queue->in_progress = NULL;
 164                        }
 165                }
 166        }
 167
 168        /* Do we need to take the next packet out of the queue to process? */
 169        if (!chunk) {
 170                struct list_head *entry;
 171
 172                /* Is the queue empty?  */
 173                if (list_empty(&queue->in_chunk_list))
 174                        return NULL;
 175
 176                entry = queue->in_chunk_list.next;
 177                chunk = queue->in_progress =
 178                        list_entry(entry, struct sctp_chunk, list);
 179                list_del_init(entry);
 180
 181                /* This is the first chunk in the packet.  */
 182                chunk->singleton = 1;
 183                ch = (sctp_chunkhdr_t *) chunk->skb->data;
 184                chunk->data_accepted = 0;
 185        }
 186
 187        chunk->chunk_hdr = ch;
 188        chunk->chunk_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
 189        /* In the unlikely case of an IP reassembly, the skb could be
 190         * non-linear. If so, update chunk_end so that it doesn't go past
 191         * the skb->tail.
 192         */
 193        if (unlikely(skb_is_nonlinear(chunk->skb))) {
 194                if (chunk->chunk_end > skb_tail_pointer(chunk->skb))
 195                        chunk->chunk_end = skb_tail_pointer(chunk->skb);
 196        }
 197        skb_pull(chunk->skb, sizeof(sctp_chunkhdr_t));
 198        chunk->subh.v = NULL; /* Subheader is no longer valid.  */
 199
 200        if (chunk->chunk_end < skb_tail_pointer(chunk->skb)) {
 201                /* This is not a singleton */
 202                chunk->singleton = 0;
 203        } else if (chunk->chunk_end > skb_tail_pointer(chunk->skb)) {
 204                /* RFC 2960, Section 6.10  Bundling
 205                 *
 206                 * Partial chunks MUST NOT be placed in an SCTP packet.
 207                 * If the receiver detects a partial chunk, it MUST drop
 208                 * the chunk.
 209                 *
 210                 * Since the end of the chunk is past the end of our buffer
 211                 * (which contains the whole packet, we can freely discard
 212                 * the whole packet.
 213                 */
 214                sctp_chunk_free(chunk);
 215                chunk = queue->in_progress = NULL;
 216
 217                return NULL;
 218        } else {
 219                /* We are at the end of the packet, so mark the chunk
 220                 * in case we need to send a SACK.
 221                 */
 222                chunk->end_of_packet = 1;
 223        }
 224
 225        SCTP_DEBUG_PRINTK("+++sctp_inq_pop+++ chunk %p[%s],"
 226                          " length %d, skb->len %d\n",chunk,
 227                          sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)),
 228                          ntohs(chunk->chunk_hdr->length), chunk->skb->len);
 229        return chunk;
 230}
 231
 232/* Set a top-half handler.
 233 *
 234 * Originally, we the top-half handler was scheduled as a BH.  We now
 235 * call the handler directly in sctp_inq_push() at a time that
 236 * we know we are lock safe.
 237 * The intent is that this routine will pull stuff out of the
 238 * inqueue and process it.
 239 */
 240void sctp_inq_set_th_handler(struct sctp_inq *q, work_func_t callback)
 241{
 242        INIT_WORK(&q->immediate, callback);
 243}
 244
 245