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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/* 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. */
51void sctp_inq_init(struct sctp_inq *queue)
52{
53 skb_queue_head_init(&queue->in);
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. */
63void sctp_inq_free(struct sctp_inq *queue)
64{
65 struct sctp_chunk *chunk;
66
67 /* Empty the queue. */
68 while ((chunk = (struct sctp_chunk *) skb_dequeue(&queue->in)) != NULL)
69 sctp_chunk_free(chunk);
70
71 /* If there is a packet which is currently being worked on,
72 * free it as well.
73 */
74 if (queue->in_progress)
75 sctp_chunk_free(queue->in_progress);
76
77 if (queue->malloced) {
78 /* Dump the master memory segment. */
79 kfree(queue);
80 }
81}
82
83/* Put a new packet in an SCTP inqueue.
84 * We assume that packet->sctp_hdr is set and in host byte order.
85 */
86void sctp_inq_push(struct sctp_inq *q, struct sctp_chunk *packet)
87{
88 /* Directly call the packet handling routine. */
89
90 /* We are now calling this either from the soft interrupt
91 * or from the backlog processing.
92 * Eventually, we should clean up inqueue to not rely
93 * on the BH related data structures.
94 */
95 skb_queue_tail(&(q->in), (struct sk_buff *) packet);
96 q->immediate.func(q->immediate.data);
97}
98
99/* Extract a chunk from an SCTP inqueue.
100 *
101 * WARNING: If you need to put the chunk on another queue, you need to
102 * make a shallow copy (clone) of it.
103 */
104struct sctp_chunk *sctp_inq_pop(struct sctp_inq *queue)
105{
106 struct sctp_chunk *chunk;
107 sctp_chunkhdr_t *ch = NULL;
108
109 /* The assumption is that we are safe to process the chunks
110 * at this time.
111 */
112
113 if ((chunk = queue->in_progress)) {
114 /* There is a packet that we have been working on.
115 * Any post processing work to do before we move on?
116 */
117 if (chunk->singleton ||
118 chunk->end_of_packet ||
119 chunk->pdiscard) {
120 sctp_chunk_free(chunk);
121 chunk = queue->in_progress = NULL;
122 } else {
123 /* Nothing to do. Next chunk in the packet, please. */
124 ch = (sctp_chunkhdr_t *) chunk->chunk_end;
125
126 /* Force chunk->skb->data to chunk->chunk_end. */
127 skb_pull(chunk->skb,
128 chunk->chunk_end - chunk->skb->data);
129 }
130 }
131
132 /* Do we need to take the next packet out of the queue to process? */
133 if (!chunk) {
134 /* Is the queue empty? */
135 if (skb_queue_empty(&queue->in))
136 return NULL;
137
138 chunk = queue->in_progress =
139 (struct sctp_chunk *) skb_dequeue(&queue->in);
140
141 /* This is the first chunk in the packet. */
142 chunk->singleton = 1;
143 ch = (sctp_chunkhdr_t *) chunk->skb->data;
144 }
145
146 chunk->chunk_hdr = ch;
147 chunk->chunk_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
148 /* In the unlikely case of an IP reassembly, the skb could be
149 * non-linear. If so, update chunk_end so that it doesn't go past
150 * the skb->tail.
151 */
152 if (unlikely(skb_is_nonlinear(chunk->skb))) {
153 if (chunk->chunk_end > chunk->skb->tail)
154 chunk->chunk_end = chunk->skb->tail;
155 }
156 skb_pull(chunk->skb, sizeof(sctp_chunkhdr_t));
157 chunk->subh.v = NULL; /* Subheader is no longer valid. */
158
159 if (chunk->chunk_end < chunk->skb->tail) {
160 /* This is not a singleton */
161 chunk->singleton = 0;
162 } else if (chunk->chunk_end > chunk->skb->tail) {
163 /* RFC 2960, Section 6.10 Bundling
164 *
165 * Partial chunks MUST NOT be placed in an SCTP packet.
166 * If the receiver detects a partial chunk, it MUST drop
167 * the chunk.
168 *
169 * Since the end of the chunk is past the end of our buffer
170 * (which contains the whole packet, we can freely discard
171 * the whole packet.
172 */
173 sctp_chunk_free(chunk);
174 chunk = queue->in_progress = NULL;
175
176 return NULL;
177 } else {
178 /* We are at the end of the packet, so mark the chunk
179 * in case we need to send a SACK.
180 */
181 chunk->end_of_packet = 1;
182 }
183
184 SCTP_DEBUG_PRINTK("+++sctp_inq_pop+++ chunk %p[%s],"
185 " length %d, skb->len %d\n",chunk,
186 sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)),
187 ntohs(chunk->chunk_hdr->length), chunk->skb->len);
188 return chunk;
189}
190
191/* Set a top-half handler.
192 *
193 * Originally, we the top-half handler was scheduled as a BH. We now
194 * call the handler directly in sctp_inq_push() at a time that
195 * we know we are lock safe.
196 * The intent is that this routine will pull stuff out of the
197 * inqueue and process it.
198 */
199void sctp_inq_set_th_handler(struct sctp_inq *q,
200 void (*callback)(void *), void *arg)
201{
202 INIT_WORK(&q->immediate, callback, arg);
203}
204