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, 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 *packet)
  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(&packet->list, &q->in_chunk_list);
 100         q->immediate.func(q->immediate.data);
 101 }
 102
 103 /* Extract a chunk from an SCTP inqueue.
 104  *
 105  * WARNING:  If you need to put the chunk on another queue, you need to
 106  * make a shallow copy (clone) of it.
 107  */
 108 struct sctp_chunk *sctp_inq_pop(struct sctp_inq *queue)
 109 {
 110         struct sctp_chunk *chunk;
 111         sctp_chunkhdr_t *ch = NULL;
 112
 113         /* The assumption is that we are safe to process the chunks
 114          * at this time.
 115          */
 116
 117         if ((chunk = queue->in_progress)) {
 118                 /* There is a packet that we have been working on.
 119                  * Any post processing work to do before we move on?
 120                  */
 121                 if (chunk->singleton ||
 122                     chunk->end_of_packet ||
 123                     chunk->pdiscard) {
 124                         sctp_chunk_free(chunk);
 125                         chunk = queue->in_progress = NULL;
 126                 } else {
 127                         /* Nothing to do. Next chunk in the packet, please. */
 128                         ch = (sctp_chunkhdr_t *) chunk->chunk_end;
 129
 130                         /* Force chunk->skb->data to chunk->chunk_end.  */
 131                         skb_pull(chunk->skb,
 132                                  chunk->chunk_end - chunk->skb->data);
 133                 }
 134         }
 135
 136         /* Do we need to take the next packet out of the queue to process? */
 137         if (!chunk) {
 138                 struct list_head *entry;
 139
 140                 /* Is the queue empty?  */
 141                 if (list_empty(&queue->in_chunk_list))
 142                         return NULL;
 143
 144                 entry = queue->in_chunk_list.next;
 145                 chunk = queue->in_progress =
 146                         list_entry(entry, struct sctp_chunk, list);
 147                 list_del_init(entry);
 148
 149                 /* This is the first chunk in the packet.  */
 150                 chunk->singleton = 1;
 151                 ch = (sctp_chunkhdr_t *) chunk->skb->data;
 152                 chunk->data_accepted = 0;
 153         }
 154
 155         chunk->chunk_hdr = ch;
 156         chunk->chunk_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
 157         /* In the unlikely case of an IP reassembly, the skb could be
 158          * non-linear. If so, update chunk_end so that it doesn't go past
 159          * the skb->tail.
 160          */
 161         if (unlikely(skb_is_nonlinear(chunk->skb))) {
 162                 if (chunk->chunk_end > chunk->skb->tail)
 163                         chunk->chunk_end = chunk->skb->tail;
 164         }
 165         skb_pull(chunk->skb, sizeof(sctp_chunkhdr_t));
 166         chunk->subh.v = NULL; /* Subheader is no longer valid.  */
 167
 168         if (chunk->chunk_end < chunk->skb->tail) {
 169                 /* This is not a singleton */
 170                 chunk->singleton = 0;
 171         } else if (chunk->chunk_end > chunk->skb->tail) {
 172                 /* RFC 2960, Section 6.10  Bundling
 173                  *
 174                  * Partial chunks MUST NOT be placed in an SCTP packet.
 175                  * If the receiver detects a partial chunk, it MUST drop
 176                  * the chunk.
 177                  *
 178                  * Since the end of the chunk is past the end of our buffer
 179                  * (which contains the whole packet, we can freely discard
 180                  * the whole packet.
 181                  */
 182                 sctp_chunk_free(chunk);
 183                 chunk = queue->in_progress = NULL;
 184
 185                 return NULL;
 186         } else {
 187                 /* We are at the end of the packet, so mark the chunk
 188                  * in case we need to send a SACK.
 189                  */
 190                 chunk->end_of_packet = 1;
 191         }
 192
 193         SCTP_DEBUG_PRINTK("+++sctp_inq_pop+++ chunk %p[%s],"
 194                           " length %d, skb->len %d\n",chunk,
 195                           sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)),
 196                           ntohs(chunk->chunk_hdr->length), chunk->skb->len);
 197         return chunk;
 198 }
 199
 200 /* Set a top-half handler.
 201  *
 202  * Originally, we the top-half handler was scheduled as a BH.  We now
 203  * call the handler directly in sctp_inq_push() at a time that
 204  * we know we are lock safe.
 205  * The intent is that this routine will pull stuff out of the
 206  * inqueue and process it.
 207  */
 208 void sctp_inq_set_th_handler(struct sctp_inq *q,
 209                                  void (*callback)(void *), void *arg)
 210 {
 211         INIT_WORK(&q->immediate, callback, arg);
 212 }
 213