net/sctp/inqueue.c

   1 /* SCTP kernel reference 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 reference 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  * The SCTP reference 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  * The SCTP reference 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
  50 /* Initialize an SCTP inqueue.  */
  51 void sctp_inq_init(struct sctp_inq *queue)
  52 {
  53         INIT_LIST_HEAD(&queue->in_chunk_list);
  54         queue->in_progress = NULL;
  55
  56         /* Create a task for delivering data.  */
  57         INIT_WORK(&queue->immediate, NULL);
  58
  59         queue->malloced = 0;
  60 }
  61
  62 /* Release the memory associated with an SCTP inqueue.  */
  63 void sctp_inq_free(struct sctp_inq *queue)
  64 {
  65         struct sctp_chunk *chunk, *tmp;
  66
  67         /* Empty the queue.  */
  68         list_for_each_entry_safe(chunk, tmp, &queue->in_chunk_list, list) {
  69                 list_del_init(&chunk->list);
  70                 sctp_chunk_free(chunk);
  71         }
  72
  73         /* If there is a packet which is currently being worked on,
  74          * free it as well.
  75          */
  76         if (queue->in_progress) {
  77                 sctp_chunk_free(queue->in_progress);
  78                 queue->in_progress = NULL;
  79         }
  80
  81         if (queue->malloced) {
  82                 /* Dump the master memory segment.  */
  83                 kfree(queue);
  84         }
  85 }
  86
  87 /* Put a new packet in an SCTP inqueue.
  88  * We assume that packet->sctp_hdr is set and in host byte order.
  89  */
  90 void sctp_inq_push(struct sctp_inq *q, struct sctp_chunk *chunk)
  91 {
  92         /* Directly call the packet handling routine. */
  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         q->immediate.func(&q->immediate);
 101 }
 102
 103 /* Peek at the next chunk on the inqeue. */
 104 struct sctp_chunkhdr *sctp_inq_peek(struct sctp_inq *queue)
 105 {
 106         struct sctp_chunk *chunk;
 107         sctp_chunkhdr_t *ch = NULL;
 108
 109         chunk = queue->in_progress;
 110         /* If there is no more chunks in this packet, say so */
 111         if (chunk->singleton ||
 112             chunk->end_of_packet ||
 113             chunk->pdiscard)
 114                     return NULL;
 115
 116         ch = (sctp_chunkhdr_t *)chunk->chunk_end;
 117
 118         return ch;
 119 }
 120
 121
 122 /* Extract a chunk from an SCTP inqueue.
 123  *
 124  * WARNING:  If you need to put the chunk on another queue, you need to
 125  * make a shallow copy (clone) of it.
 126  */
 127 struct sctp_chunk *sctp_inq_pop(struct sctp_inq *queue)
 128 {
 129         struct sctp_chunk *chunk;
 130         sctp_chunkhdr_t *ch = NULL;
 131
 132         /* The assumption is that we are safe to process the chunks
 133          * at this time.
 134          */
 135
 136         if ((chunk = queue->in_progress)) {
 137                 /* There is a packet that we have been working on.
 138                  * Any post processing work to do before we move on?
 139                  */
 140                 if (chunk->singleton ||
 141                     chunk->end_of_packet ||
 142                     chunk->pdiscard) {
 143                         sctp_chunk_free(chunk);
 144                         chunk = queue->in_progress = NULL;
 145                 } else {
 146                         /* Nothing to do. Next chunk in the packet, please. */
 147                         ch = (sctp_chunkhdr_t *) chunk->chunk_end;
 148
 149                         /* Force chunk->skb->data to chunk->chunk_end.  */
 150                         skb_pull(chunk->skb,
 151                                  chunk->chunk_end - chunk->skb->data);
 152
 153                         /* Verify that we have at least chunk headers
 154                          * worth of buffer left.
 155                          */
 156                         if (skb_headlen(chunk->skb) < sizeof(sctp_chunkhdr_t)) {
 157                                 sctp_chunk_free(chunk);
 158                                 chunk = queue->in_progress = NULL;
 159                         }
 160                 }
 161         }
 162
 163         /* Do we need to take the next packet out of the queue to process? */
 164         if (!chunk) {
 165                 struct list_head *entry;
 166
 167                 /* Is the queue empty?  */
 168                 if (list_empty(&queue->in_chunk_list))
 169                         return NULL;
 170
 171                 entry = queue->in_chunk_list.next;
 172                 chunk = queue->in_progress =
 173                         list_entry(entry, struct sctp_chunk, list);
 174                 list_del_init(entry);
 175
 176                 /* This is the first chunk in the packet.  */
 177                 chunk->singleton = 1;
 178                 ch = (sctp_chunkhdr_t *) chunk->skb->data;
 179                 chunk->data_accepted = 0;
 180         }
 181
 182         chunk->chunk_hdr = ch;
 183         chunk->chunk_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
 184         /* In the unlikely case of an IP reassembly, the skb could be
 185          * non-linear. If so, update chunk_end so that it doesn't go past
 186          * the skb->tail.
 187          */
 188         if (unlikely(skb_is_nonlinear(chunk->skb))) {
 189                 if (chunk->chunk_end > skb_tail_pointer(chunk->skb))
 190                         chunk->chunk_end = skb_tail_pointer(chunk->skb);
 191         }
 192         skb_pull(chunk->skb, sizeof(sctp_chunkhdr_t));
 193         chunk->subh.v = NULL; /* Subheader is no longer valid.  */
 194
 195         if (chunk->chunk_end < skb_tail_pointer(chunk->skb)) {
 196                 /* This is not a singleton */
 197                 chunk->singleton = 0;
 198         } else if (chunk->chunk_end > skb_tail_pointer(chunk->skb)) {
 199                 /* RFC 2960, Section 6.10  Bundling
 200                  *
 201                  * Partial chunks MUST NOT be placed in an SCTP packet.
 202                  * If the receiver detects a partial chunk, it MUST drop
 203                  * the chunk.
 204                  *
 205                  * Since the end of the chunk is past the end of our buffer
 206                  * (which contains the whole packet, we can freely discard
 207                  * the whole packet.
 208                  */
 209                 sctp_chunk_free(chunk);
 210                 chunk = queue->in_progress = NULL;
 211
 212                 return NULL;
 213         } else {
 214                 /* We are at the end of the packet, so mark the chunk
 215                  * in case we need to send a SACK.
 216                  */
 217                 chunk->end_of_packet = 1;
 218         }
 219
 220         SCTP_DEBUG_PRINTK("+++sctp_inq_pop+++ chunk %p[%s],"
 221                           " length %d, skb->len %d\n",chunk,
 222                           sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)),
 223                           ntohs(chunk->chunk_hdr->length), chunk->skb->len);
 224         return chunk;
 225 }
 226
 227 /* Set a top-half handler.
 228  *
 229  * Originally, we the top-half handler was scheduled as a BH.  We now
 230  * call the handler directly in sctp_inq_push() at a time that
 231  * we know we are lock safe.
 232  * The intent is that this routine will pull stuff out of the
 233  * inqueue and process it.
 234  */
 235 void sctp_inq_set_th_handler(struct sctp_inq *q, work_func_t callback)
 236 {
 237         INIT_WORK(&q->immediate, callback);
 238 }
 239