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         local_bh_disable();
  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         local_bh_enable();
  98 }
  99
 100 /* Peek at the next chunk on the inqeue. */
 101 struct sctp_chunkhdr *sctp_inq_peek(struct sctp_inq *queue)
 102 {
 103         struct sctp_chunk *chunk;
 104         sctp_chunkhdr_t *ch = NULL;
 105
 106         chunk = queue->in_progress;
 107         /* If there is no more chunks in this packet, say so */
 108         if (chunk->singleton ||
 109             chunk->end_of_packet ||
 110             chunk->pdiscard)
 111                     return NULL;
 112
 113         ch = (sctp_chunkhdr_t *)chunk->chunk_end;
 114
 115         return ch;
 116 }
 117
 118
 119 /* Extract a chunk from an SCTP inqueue.
 120  *
 121  * WARNING:  If you need to put the chunk on another queue, you need to
 122  * make a shallow copy (clone) of it.
 123  */
 124 struct sctp_chunk *sctp_inq_pop(struct sctp_inq *queue)
 125 {
 126         struct sctp_chunk *chunk;
 127         sctp_chunkhdr_t *ch = NULL;
 128
 129         /* The assumption is that we are safe to process the chunks
 130          * at this time.
 131          */
 132
 133         if ((chunk = queue->in_progress)) {
 134                 /* There is a packet that we have been working on.
 135                  * Any post processing work to do before we move on?
 136                  */
 137                 if (chunk->singleton ||
 138                     chunk->end_of_packet ||
 139                     chunk->pdiscard) {
 140                         sctp_chunk_free(chunk);
 141                         chunk = queue->in_progress = NULL;
 142                 } else {
 143                         /* Nothing to do. Next chunk in the packet, please. */
 144                         ch = (sctp_chunkhdr_t *) chunk->chunk_end;
 145                         /* Force chunk->skb->data to chunk->chunk_end.  */
 146                         skb_pull(chunk->skb, chunk->chunk_end - chunk->skb->data);
 147                         /* We are guaranteed to pull a SCTP header. */
 148                 }
 149         }
 150
 151         /* Do we need to take the next packet out of the queue to process? */
 152         if (!chunk) {
 153                 struct list_head *entry;
 154
 155                 /* Is the queue empty?  */
 156                 if (list_empty(&queue->in_chunk_list))
 157                         return NULL;
 158
 159                 entry = queue->in_chunk_list.next;
 160                 chunk = queue->in_progress =
 161                         list_entry(entry, struct sctp_chunk, list);
 162                 list_del_init(entry);
 163
 164                 /* This is the first chunk in the packet.  */
 165                 chunk->singleton = 1;
 166                 ch = (sctp_chunkhdr_t *) chunk->skb->data;
 167                 chunk->data_accepted = 0;
 168
 169                 if (chunk->asoc)
 170                         sock_rps_save_rxhash(chunk->asoc->base.sk, chunk->skb);
 171         }
 172
 173         chunk->chunk_hdr = ch;
 174         chunk->chunk_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
 175         /* In the unlikely case of an IP reassembly, the skb could be
 176          * non-linear. If so, update chunk_end so that it doesn't go past
 177          * the skb->tail.
 178          */
 179         if (unlikely(skb_is_nonlinear(chunk->skb))) {
 180                 if (chunk->chunk_end > skb_tail_pointer(chunk->skb))
 181                         chunk->chunk_end = skb_tail_pointer(chunk->skb);
 182         }
 183         skb_pull(chunk->skb, sizeof(sctp_chunkhdr_t));
 184         chunk->subh.v = NULL; /* Subheader is no longer valid.  */
 185
 186         if (chunk->chunk_end + sizeof(sctp_chunkhdr_t) <
 187             skb_tail_pointer(chunk->skb)) {
 188                 /* This is not a singleton */
 189                 chunk->singleton = 0;
 190         } else if (chunk->chunk_end > skb_tail_pointer(chunk->skb)) {
 191                 /* Discard inside state machine. */
 192                 chunk->pdiscard = 1;
 193                 chunk->chunk_end = skb_tail_pointer(chunk->skb);
 194         } else {
 195                 /* We are at the end of the packet, so mark the chunk
 196                  * in case we need to send a SACK.
 197                  */
 198                 chunk->end_of_packet = 1;
 199         }
 200
 201         pr_debug("+++sctp_inq_pop+++ chunk:%p[%s], length:%d, skb->len:%d\n",
 202                  chunk, sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)),
 203                  ntohs(chunk->chunk_hdr->length), chunk->skb->len);
 204
 205         return chunk;
 206 }
 207
 208 /* Set a top-half handler.
 209  *
 210  * Originally, we the top-half handler was scheduled as a BH.  We now
 211  * call the handler directly in sctp_inq_push() at a time that
 212  * we know we are lock safe.
 213  * The intent is that this routine will pull stuff out of the
 214  * inqueue and process it.
 215  */
 216 void sctp_inq_set_th_handler(struct sctp_inq *q, work_func_t callback)
 217 {
 218         INIT_WORK(&q->immediate, callback);
 219 }