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, see
  28  * <http://www.gnu.org/licenses/>.
  29  *
  30  * Please send any bug reports or fixes you make to the
  31  * email address(es):
  32  *    lksctp developers <linux-sctp@vger.kernel.org>
  33  *
  34  * Written or modified by:
  35  *    La Monte H.P. Yarroll <piggy@acm.org>
  36  *    Karl Knutson <karl@athena.chicago.il.us>
  37  */
  38
  39 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  40
  41 #include <net/sctp/sctp.h>
  42 #include <net/sctp/sm.h>
  43 #include <linux/interrupt.h>
  44 #include <linux/slab.h>
  45
  46 /* Initialize an SCTP inqueue.  */
  47 void sctp_inq_init(struct sctp_inq *queue)
  48 {
  49         INIT_LIST_HEAD(&queue->in_chunk_list);
  50         queue->in_progress = NULL;
  51
  52         /* Create a task for delivering data.  */
  53         INIT_WORK(&queue->immediate, NULL);
  54 }
  55
  56 /* Release the memory associated with an SCTP inqueue.  */
  57 void sctp_inq_free(struct sctp_inq *queue)
  58 {
  59         struct sctp_chunk *chunk, *tmp;
  60
  61         /* Empty the queue.  */
  62         list_for_each_entry_safe(chunk, tmp, &queue->in_chunk_list, list) {
  63                 list_del_init(&chunk->list);
  64                 sctp_chunk_free(chunk);
  65         }
  66
  67         /* If there is a packet which is currently being worked on,
  68          * free it as well.
  69          */
  70         if (queue->in_progress) {
  71                 sctp_chunk_free(queue->in_progress);
  72                 queue->in_progress = NULL;
  73         }
  74 }
  75
  76 /* Put a new packet in an SCTP inqueue.
  77  * We assume that packet->sctp_hdr is set and in host byte order.
  78  */
  79 void sctp_inq_push(struct sctp_inq *q, struct sctp_chunk *chunk)
  80 {
  81         /* Directly call the packet handling routine. */
  82         if (chunk->rcvr->dead) {
  83                 sctp_chunk_free(chunk);
  84                 return;
  85         }
  86
  87         /* We are now calling this either from the soft interrupt
  88          * or from the backlog processing.
  89          * Eventually, we should clean up inqueue to not rely
  90          * on the BH related data structures.
  91          */
  92         list_add_tail(&chunk->list, &q->in_chunk_list);
  93         if (chunk->asoc)
  94                 chunk->asoc->stats.ipackets++;
  95         q->immediate.func(&q->immediate);
  96 }
  97
  98 /* Peek at the next chunk on the inqeue. */
  99 struct sctp_chunkhdr *sctp_inq_peek(struct sctp_inq *queue)
 100 {
 101         struct sctp_chunk *chunk;
 102         sctp_chunkhdr_t *ch = NULL;
 103
 104         chunk = queue->in_progress;
 105         /* If there is no more chunks in this packet, say so */
 106         if (chunk->singleton ||
 107             chunk->end_of_packet ||
 108             chunk->pdiscard)
 109                     return NULL;
 110
 111         ch = (sctp_chunkhdr_t *)chunk->chunk_end;
 112
 113         return ch;
 114 }
 115
 116
 117 /* Extract a chunk from an SCTP inqueue.
 118  *
 119  * WARNING:  If you need to put the chunk on another queue, you need to
 120  * make a shallow copy (clone) of it.
 121  */
 122 struct sctp_chunk *sctp_inq_pop(struct sctp_inq *queue)
 123 {
 124         struct sctp_chunk *chunk;
 125         sctp_chunkhdr_t *ch = NULL;
 126
 127         /* The assumption is that we are safe to process the chunks
 128          * at this time.
 129          */
 130
 131         if ((chunk = queue->in_progress)) {
 132                 /* There is a packet that we have been working on.
 133                  * Any post processing work to do before we move on?
 134                  */
 135                 if (chunk->singleton ||
 136                     chunk->end_of_packet ||
 137                     chunk->pdiscard) {
 138                         sctp_chunk_free(chunk);
 139                         chunk = queue->in_progress = NULL;
 140                 } else {
 141                         /* Nothing to do. Next chunk in the packet, please. */
 142                         ch = (sctp_chunkhdr_t *) chunk->chunk_end;
 143                         /* Force chunk->skb->data to chunk->chunk_end.  */
 144                         skb_pull(chunk->skb, chunk->chunk_end - chunk->skb->data);
 145                         /* We are guaranteed to pull a SCTP header. */
 146                 }
 147         }
 148
 149         /* Do we need to take the next packet out of the queue to process? */
 150         if (!chunk) {
 151                 struct list_head *entry;
 152
 153                 /* Is the queue empty?  */
 154                 if (list_empty(&queue->in_chunk_list))
 155                         return NULL;
 156
 157                 entry = queue->in_chunk_list.next;
 158                 chunk = queue->in_progress =
 159                         list_entry(entry, struct sctp_chunk, list);
 160                 list_del_init(entry);
 161
 162                 /* This is the first chunk in the packet.  */
 163                 chunk->singleton = 1;
 164                 ch = (sctp_chunkhdr_t *) chunk->skb->data;
 165                 chunk->data_accepted = 0;
 166         }
 167
 168         chunk->chunk_hdr = ch;
 169         chunk->chunk_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
 170         /* In the unlikely case of an IP reassembly, the skb could be
 171          * non-linear. If so, update chunk_end so that it doesn't go past
 172          * the skb->tail.
 173          */
 174         if (unlikely(skb_is_nonlinear(chunk->skb))) {
 175                 if (chunk->chunk_end > skb_tail_pointer(chunk->skb))
 176                         chunk->chunk_end = skb_tail_pointer(chunk->skb);
 177         }
 178         skb_pull(chunk->skb, sizeof(sctp_chunkhdr_t));
 179         chunk->subh.v = NULL; /* Subheader is no longer valid.  */
 180
 181         if (chunk->chunk_end + sizeof(sctp_chunkhdr_t) <
 182             skb_tail_pointer(chunk->skb)) {
 183                 /* This is not a singleton */
 184                 chunk->singleton = 0;
 185         } else if (chunk->chunk_end > skb_tail_pointer(chunk->skb)) {
 186                 /* Discard inside state machine. */
 187                 chunk->pdiscard = 1;
 188                 chunk->chunk_end = skb_tail_pointer(chunk->skb);
 189         } else {
 190                 /* We are at the end of the packet, so mark the chunk
 191                  * in case we need to send a SACK.
 192                  */
 193                 chunk->end_of_packet = 1;
 194         }
 195
 196         pr_debug("+++sctp_inq_pop+++ chunk:%p[%s], length:%d, skb->len:%d\n",
 197                  chunk, sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)),
 198                  ntohs(chunk->chunk_hdr->length), chunk->skb->len);
 199
 200         return chunk;
 201 }
 202
 203 /* Set a top-half handler.
 204  *
 205  * Originally, we the top-half handler was scheduled as a BH.  We now
 206  * call the handler directly in sctp_inq_push() at a time that
 207  * we know we are lock safe.
 208  * The intent is that this routine will pull stuff out of the
 209  * inqueue and process it.
 210  */
 211 void sctp_inq_set_th_handler(struct sctp_inq *q, work_func_t callback)
 212 {
 213         INIT_WORK(&q->immediate, callback);
 214 }