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 <linux-sctp@vger.kernel.org>
  34  *
  35  * Written or modified by:
  36  *    La Monte H.P. Yarroll <piggy@acm.org>
  37  *    Karl Knutson <karl@athena.chicago.il.us>
  38  */
  39
  40 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  41
  42 #include <net/sctp/sctp.h>
  43 #include <net/sctp/sm.h>
  44 #include <linux/interrupt.h>
  45 #include <linux/slab.h>
  46
  47 /* Initialize an SCTP inqueue.  */
  48 void sctp_inq_init(struct sctp_inq *queue)
  49 {
  50         INIT_LIST_HEAD(&queue->in_chunk_list);
  51         queue->in_progress = NULL;
  52
  53         /* Create a task for delivering data.  */
  54         INIT_WORK(&queue->immediate, NULL);
  55 }
  56
  57 /* Release the memory associated with an SCTP inqueue.  */
  58 void sctp_inq_free(struct sctp_inq *queue)
  59 {
  60         struct sctp_chunk *chunk, *tmp;
  61
  62         /* Empty the queue.  */
  63         list_for_each_entry_safe(chunk, tmp, &queue->in_chunk_list, list) {
  64                 list_del_init(&chunk->list);
  65                 sctp_chunk_free(chunk);
  66         }
  67
  68         /* If there is a packet which is currently being worked on,
  69          * free it as well.
  70          */
  71         if (queue->in_progress) {
  72                 sctp_chunk_free(queue->in_progress);
  73                 queue->in_progress = NULL;
  74         }
  75 }
  76
  77 /* Put a new packet in an SCTP inqueue.
  78  * We assume that packet->sctp_hdr is set and in host byte order.
  79  */
  80 void sctp_inq_push(struct sctp_inq *q, struct sctp_chunk *chunk)
  81 {
  82         /* Directly call the packet handling routine. */
  83         if (chunk->rcvr->dead) {
  84                 sctp_chunk_free(chunk);
  85                 return;
  86         }
  87
  88         /* We are now calling this either from the soft interrupt
  89          * or from the backlog processing.
  90          * Eventually, we should clean up inqueue to not rely
  91          * on the BH related data structures.
  92          */
  93         list_add_tail(&chunk->list, &q->in_chunk_list);
  94         if (chunk->asoc)
  95                 chunk->asoc->stats.ipackets++;
  96         q->immediate.func(&q->immediate);
  97 }
  98
  99 /* Peek at the next chunk on the inqeue. */
 100 struct sctp_chunkhdr *sctp_inq_peek(struct sctp_inq *queue)
 101 {
 102         struct sctp_chunk *chunk;
 103         sctp_chunkhdr_t *ch = NULL;
 104
 105         chunk = queue->in_progress;
 106         /* If there is no more chunks in this packet, say so */
 107         if (chunk->singleton ||
 108             chunk->end_of_packet ||
 109             chunk->pdiscard)
 110                     return NULL;
 111
 112         ch = (sctp_chunkhdr_t *)chunk->chunk_end;
 113
 114         return ch;
 115 }
 116
 117
 118 /* Extract a chunk from an SCTP inqueue.
 119  *
 120  * WARNING:  If you need to put the chunk on another queue, you need to
 121  * make a shallow copy (clone) of it.
 122  */
 123 struct sctp_chunk *sctp_inq_pop(struct sctp_inq *queue)
 124 {
 125         struct sctp_chunk *chunk;
 126         sctp_chunkhdr_t *ch = NULL;
 127
 128         /* The assumption is that we are safe to process the chunks
 129          * at this time.
 130          */
 131
 132         if ((chunk = queue->in_progress)) {
 133                 /* There is a packet that we have been working on.
 134                  * Any post processing work to do before we move on?
 135                  */
 136                 if (chunk->singleton ||
 137                     chunk->end_of_packet ||
 138                     chunk->pdiscard) {
 139                         sctp_chunk_free(chunk);
 140                         chunk = queue->in_progress = NULL;
 141                 } else {
 142                         /* Nothing to do. Next chunk in the packet, please. */
 143                         ch = (sctp_chunkhdr_t *) chunk->chunk_end;
 144
 145                         /* Force chunk->skb->data to chunk->chunk_end.  */
 146                         skb_pull(chunk->skb,
 147                                  chunk->chunk_end - chunk->skb->data);
 148
 149                         /* Verify that we have at least chunk headers
 150                          * worth of buffer left.
 151                          */
 152                         if (skb_headlen(chunk->skb) < sizeof(sctp_chunkhdr_t)) {
 153                                 sctp_chunk_free(chunk);
 154                                 chunk = queue->in_progress = NULL;
 155                         }
 156                 }
 157         }
 158
 159         /* Do we need to take the next packet out of the queue to process? */
 160         if (!chunk) {
 161                 struct list_head *entry;
 162
 163                 /* Is the queue empty?  */
 164                 if (list_empty(&queue->in_chunk_list))
 165                         return NULL;
 166
 167                 entry = queue->in_chunk_list.next;
 168                 chunk = queue->in_progress =
 169                         list_entry(entry, struct sctp_chunk, list);
 170                 list_del_init(entry);
 171
 172                 /* This is the first chunk in the packet.  */
 173                 chunk->singleton = 1;
 174                 ch = (sctp_chunkhdr_t *) chunk->skb->data;
 175                 chunk->data_accepted = 0;
 176         }
 177
 178         chunk->chunk_hdr = ch;
 179         chunk->chunk_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
 180         /* In the unlikely case of an IP reassembly, the skb could be
 181          * non-linear. If so, update chunk_end so that it doesn't go past
 182          * the skb->tail.
 183          */
 184         if (unlikely(skb_is_nonlinear(chunk->skb))) {
 185                 if (chunk->chunk_end > skb_tail_pointer(chunk->skb))
 186                         chunk->chunk_end = skb_tail_pointer(chunk->skb);
 187         }
 188         skb_pull(chunk->skb, sizeof(sctp_chunkhdr_t));
 189         chunk->subh.v = NULL; /* Subheader is no longer valid.  */
 190
 191         if (chunk->chunk_end < skb_tail_pointer(chunk->skb)) {
 192                 /* This is not a singleton */
 193                 chunk->singleton = 0;
 194         } else if (chunk->chunk_end > skb_tail_pointer(chunk->skb)) {
 195                 /* RFC 2960, Section 6.10  Bundling
 196                  *
 197                  * Partial chunks MUST NOT be placed in an SCTP packet.
 198                  * If the receiver detects a partial chunk, it MUST drop
 199                  * the chunk.
 200                  *
 201                  * Since the end of the chunk is past the end of our buffer
 202                  * (which contains the whole packet, we can freely discard
 203                  * the whole packet.
 204                  */
 205                 sctp_chunk_free(chunk);
 206                 chunk = queue->in_progress = NULL;
 207
 208                 return NULL;
 209         } else {
 210                 /* We are at the end of the packet, so mark the chunk
 211                  * in case we need to send a SACK.
 212                  */
 213                 chunk->end_of_packet = 1;
 214         }
 215
 216         pr_debug("+++sctp_inq_pop+++ chunk:%p[%s], length:%d, skb->len:%d\n",
 217                  chunk, sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)),
 218                  ntohs(chunk->chunk_hdr->length), chunk->skb->len);
 219
 220         return chunk;
 221 }
 222
 223 /* Set a top-half handler.
 224  *
 225  * Originally, we the top-half handler was scheduled as a BH.  We now
 226  * call the handler directly in sctp_inq_push() at a time that
 227  * we know we are lock safe.
 228  * The intent is that this routine will pull stuff out of the
 229  * inqueue and process it.
 230  */
 231 void sctp_inq_set_th_handler(struct sctp_inq *q, work_func_t callback)
 232 {
 233         INIT_WORK(&q->immediate, callback);
 234 }