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60c778b2 | 1 | /* SCTP kernel implementation |
1da177e4 LT |
2 | * (C) Copyright IBM Corp. 2001, 2004 |
3 | * Copyright (c) 1999-2000 Cisco, Inc. | |
4 | * Copyright (c) 1999-2001 Motorola, Inc. | |
5 | * | |
60c778b2 | 6 | * This file is part of the SCTP kernel implementation |
1da177e4 LT |
7 | * |
8 | * These functions handle output processing. | |
9 | * | |
60c778b2 | 10 | * This SCTP implementation is free software; |
1da177e4 LT |
11 | * you can redistribute it and/or modify it under the terms of |
12 | * the GNU General Public License as published by | |
13 | * the Free Software Foundation; either version 2, or (at your option) | |
14 | * any later version. | |
15 | * | |
60c778b2 | 16 | * This SCTP implementation is distributed in the hope that it |
1da177e4 LT |
17 | * will be useful, but WITHOUT ANY WARRANTY; without even the implied |
18 | * ************************ | |
19 | * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. | |
20 | * See the GNU General Public License for more details. | |
21 | * | |
22 | * You should have received a copy of the GNU General Public License | |
23 | * along with GNU CC; see the file COPYING. If not, write to | |
24 | * the Free Software Foundation, 59 Temple Place - Suite 330, | |
25 | * Boston, MA 02111-1307, USA. | |
26 | * | |
27 | * Please send any bug reports or fixes you make to the | |
28 | * email address(es): | |
29 | * lksctp developers <lksctp-developers@lists.sourceforge.net> | |
30 | * | |
31 | * Or submit a bug report through the following website: | |
32 | * http://www.sf.net/projects/lksctp | |
33 | * | |
34 | * Written or modified by: | |
35 | * La Monte H.P. Yarroll <piggy@acm.org> | |
36 | * Karl Knutson <karl@athena.chicago.il.us> | |
37 | * Jon Grimm <jgrimm@austin.ibm.com> | |
38 | * Sridhar Samudrala <sri@us.ibm.com> | |
39 | * | |
40 | * Any bugs reported given to us we will try to fix... any fixes shared will | |
41 | * be incorporated into the next SCTP release. | |
42 | */ | |
43 | ||
44 | #include <linux/types.h> | |
45 | #include <linux/kernel.h> | |
46 | #include <linux/wait.h> | |
47 | #include <linux/time.h> | |
48 | #include <linux/ip.h> | |
49 | #include <linux/ipv6.h> | |
50 | #include <linux/init.h> | |
51 | #include <net/inet_ecn.h> | |
8d2f9e81 | 52 | #include <net/ip.h> |
1da177e4 | 53 | #include <net/icmp.h> |
7c73a6fa | 54 | #include <net/net_namespace.h> |
1da177e4 | 55 | |
1da177e4 LT |
56 | #include <linux/socket.h> /* for sa_family_t */ |
57 | #include <net/sock.h> | |
58 | ||
59 | #include <net/sctp/sctp.h> | |
60 | #include <net/sctp/sm.h> | |
9ad0977f | 61 | #include <net/sctp/checksum.h> |
1da177e4 LT |
62 | |
63 | /* Forward declarations for private helpers. */ | |
e83963b7 | 64 | static sctp_xmit_t sctp_packet_can_append_data(struct sctp_packet *packet, |
1da177e4 | 65 | struct sctp_chunk *chunk); |
e83963b7 VY |
66 | static void sctp_packet_append_data(struct sctp_packet *packet, |
67 | struct sctp_chunk *chunk); | |
68 | static sctp_xmit_t sctp_packet_will_fit(struct sctp_packet *packet, | |
69 | struct sctp_chunk *chunk, | |
70 | u16 chunk_len); | |
1da177e4 LT |
71 | |
72 | /* Config a packet. | |
73 | * This appears to be a followup set of initializations. | |
74 | */ | |
75 | struct sctp_packet *sctp_packet_config(struct sctp_packet *packet, | |
76 | __u32 vtag, int ecn_capable) | |
77 | { | |
78 | struct sctp_chunk *chunk = NULL; | |
79 | ||
0dc47877 | 80 | SCTP_DEBUG_PRINTK("%s: packet:%p vtag:0x%x\n", __func__, |
1da177e4 LT |
81 | packet, vtag); |
82 | ||
83 | packet->vtag = vtag; | |
84 | packet->has_cookie_echo = 0; | |
85 | packet->has_sack = 0; | |
a29a5bd4 | 86 | packet->has_auth = 0; |
4cd57c80 | 87 | packet->has_data = 0; |
1da177e4 | 88 | packet->ipfragok = 0; |
a29a5bd4 | 89 | packet->auth = NULL; |
1da177e4 LT |
90 | |
91 | if (ecn_capable && sctp_packet_empty(packet)) { | |
92 | chunk = sctp_get_ecne_prepend(packet->transport->asoc); | |
93 | ||
94 | /* If there a is a prepend chunk stick it on the list before | |
d808ad9a YH |
95 | * any other chunks get appended. |
96 | */ | |
1da177e4 LT |
97 | if (chunk) |
98 | sctp_packet_append_chunk(packet, chunk); | |
99 | } | |
100 | ||
101 | return packet; | |
102 | } | |
103 | ||
104 | /* Initialize the packet structure. */ | |
105 | struct sctp_packet *sctp_packet_init(struct sctp_packet *packet, | |
106 | struct sctp_transport *transport, | |
107 | __u16 sport, __u16 dport) | |
108 | { | |
109 | struct sctp_association *asoc = transport->asoc; | |
110 | size_t overhead; | |
111 | ||
0dc47877 | 112 | SCTP_DEBUG_PRINTK("%s: packet:%p transport:%p\n", __func__, |
1da177e4 LT |
113 | packet, transport); |
114 | ||
115 | packet->transport = transport; | |
116 | packet->source_port = sport; | |
117 | packet->destination_port = dport; | |
79af02c2 | 118 | INIT_LIST_HEAD(&packet->chunk_list); |
1da177e4 | 119 | if (asoc) { |
d808ad9a YH |
120 | struct sctp_sock *sp = sctp_sk(asoc->base.sk); |
121 | overhead = sp->pf->af->net_header_len; | |
1da177e4 LT |
122 | } else { |
123 | overhead = sizeof(struct ipv6hdr); | |
124 | } | |
125 | overhead += sizeof(struct sctphdr); | |
126 | packet->overhead = overhead; | |
127 | packet->size = overhead; | |
128 | packet->vtag = 0; | |
129 | packet->has_cookie_echo = 0; | |
130 | packet->has_sack = 0; | |
a29a5bd4 | 131 | packet->has_auth = 0; |
4cd57c80 | 132 | packet->has_data = 0; |
1da177e4 LT |
133 | packet->ipfragok = 0; |
134 | packet->malloced = 0; | |
a29a5bd4 | 135 | packet->auth = NULL; |
1da177e4 LT |
136 | return packet; |
137 | } | |
138 | ||
d521c08f WY |
139 | static void sctp_packet_reset(struct sctp_packet *packet) |
140 | { | |
141 | packet->size = packet->overhead; | |
142 | packet->has_cookie_echo = 0; | |
143 | packet->has_sack = 0; | |
144 | packet->has_data = 0; | |
145 | packet->has_auth = 0; | |
146 | packet->ipfragok = 0; | |
147 | packet->auth = NULL; | |
148 | } | |
149 | ||
1da177e4 LT |
150 | /* Free a packet. */ |
151 | void sctp_packet_free(struct sctp_packet *packet) | |
152 | { | |
79af02c2 | 153 | struct sctp_chunk *chunk, *tmp; |
1da177e4 | 154 | |
0dc47877 | 155 | SCTP_DEBUG_PRINTK("%s: packet:%p\n", __func__, packet); |
1da177e4 | 156 | |
79af02c2 DM |
157 | list_for_each_entry_safe(chunk, tmp, &packet->chunk_list, list) { |
158 | list_del_init(&chunk->list); | |
1da177e4 | 159 | sctp_chunk_free(chunk); |
79af02c2 | 160 | } |
1da177e4 LT |
161 | |
162 | if (packet->malloced) | |
163 | kfree(packet); | |
164 | } | |
165 | ||
166 | /* This routine tries to append the chunk to the offered packet. If adding | |
167 | * the chunk causes the packet to exceed the path MTU and COOKIE_ECHO chunk | |
168 | * is not present in the packet, it transmits the input packet. | |
169 | * Data can be bundled with a packet containing a COOKIE_ECHO chunk as long | |
170 | * as it can fit in the packet, but any more data that does not fit in this | |
171 | * packet can be sent only after receiving the COOKIE_ACK. | |
172 | */ | |
173 | sctp_xmit_t sctp_packet_transmit_chunk(struct sctp_packet *packet, | |
2e3216cd VY |
174 | struct sctp_chunk *chunk, |
175 | int one_packet) | |
1da177e4 LT |
176 | { |
177 | sctp_xmit_t retval; | |
178 | int error = 0; | |
179 | ||
0dc47877 | 180 | SCTP_DEBUG_PRINTK("%s: packet:%p chunk:%p\n", __func__, |
1da177e4 LT |
181 | packet, chunk); |
182 | ||
183 | switch ((retval = (sctp_packet_append_chunk(packet, chunk)))) { | |
184 | case SCTP_XMIT_PMTU_FULL: | |
185 | if (!packet->has_cookie_echo) { | |
186 | error = sctp_packet_transmit(packet); | |
187 | if (error < 0) | |
188 | chunk->skb->sk->sk_err = -error; | |
189 | ||
190 | /* If we have an empty packet, then we can NOT ever | |
191 | * return PMTU_FULL. | |
192 | */ | |
2e3216cd VY |
193 | if (!one_packet) |
194 | retval = sctp_packet_append_chunk(packet, | |
195 | chunk); | |
1da177e4 LT |
196 | } |
197 | break; | |
198 | ||
199 | case SCTP_XMIT_RWND_FULL: | |
200 | case SCTP_XMIT_OK: | |
201 | case SCTP_XMIT_NAGLE_DELAY: | |
202 | break; | |
3ff50b79 | 203 | } |
1da177e4 LT |
204 | |
205 | return retval; | |
206 | } | |
207 | ||
4cd57c80 VY |
208 | /* Try to bundle an auth chunk into the packet. */ |
209 | static sctp_xmit_t sctp_packet_bundle_auth(struct sctp_packet *pkt, | |
210 | struct sctp_chunk *chunk) | |
211 | { | |
212 | struct sctp_association *asoc = pkt->transport->asoc; | |
213 | struct sctp_chunk *auth; | |
214 | sctp_xmit_t retval = SCTP_XMIT_OK; | |
215 | ||
216 | /* if we don't have an association, we can't do authentication */ | |
217 | if (!asoc) | |
218 | return retval; | |
219 | ||
220 | /* See if this is an auth chunk we are bundling or if | |
221 | * auth is already bundled. | |
222 | */ | |
223 | if (chunk->chunk_hdr->type == SCTP_CID_AUTH || pkt->auth) | |
224 | return retval; | |
225 | ||
226 | /* if the peer did not request this chunk to be authenticated, | |
227 | * don't do it | |
228 | */ | |
229 | if (!chunk->auth) | |
230 | return retval; | |
231 | ||
232 | auth = sctp_make_auth(asoc); | |
233 | if (!auth) | |
234 | return retval; | |
235 | ||
236 | retval = sctp_packet_append_chunk(pkt, auth); | |
237 | ||
238 | return retval; | |
239 | } | |
240 | ||
1da177e4 LT |
241 | /* Try to bundle a SACK with the packet. */ |
242 | static sctp_xmit_t sctp_packet_bundle_sack(struct sctp_packet *pkt, | |
243 | struct sctp_chunk *chunk) | |
244 | { | |
245 | sctp_xmit_t retval = SCTP_XMIT_OK; | |
246 | ||
247 | /* If sending DATA and haven't aleady bundled a SACK, try to | |
248 | * bundle one in to the packet. | |
249 | */ | |
250 | if (sctp_chunk_is_data(chunk) && !pkt->has_sack && | |
251 | !pkt->has_cookie_echo) { | |
252 | struct sctp_association *asoc; | |
af87b823 | 253 | struct timer_list *timer; |
1da177e4 | 254 | asoc = pkt->transport->asoc; |
af87b823 | 255 | timer = &asoc->timers[SCTP_EVENT_TIMEOUT_SACK]; |
1da177e4 | 256 | |
af87b823 DG |
257 | /* If the SACK timer is running, we have a pending SACK */ |
258 | if (timer_pending(timer)) { | |
1da177e4 LT |
259 | struct sctp_chunk *sack; |
260 | asoc->a_rwnd = asoc->rwnd; | |
261 | sack = sctp_make_sack(asoc); | |
262 | if (sack) { | |
1da177e4 LT |
263 | retval = sctp_packet_append_chunk(pkt, sack); |
264 | asoc->peer.sack_needed = 0; | |
af87b823 | 265 | if (del_timer(timer)) |
1da177e4 LT |
266 | sctp_association_put(asoc); |
267 | } | |
268 | } | |
269 | } | |
270 | return retval; | |
271 | } | |
272 | ||
273 | /* Append a chunk to the offered packet reporting back any inability to do | |
274 | * so. | |
275 | */ | |
276 | sctp_xmit_t sctp_packet_append_chunk(struct sctp_packet *packet, | |
277 | struct sctp_chunk *chunk) | |
278 | { | |
279 | sctp_xmit_t retval = SCTP_XMIT_OK; | |
280 | __u16 chunk_len = WORD_ROUND(ntohs(chunk->chunk_hdr->length)); | |
1da177e4 | 281 | |
0dc47877 | 282 | SCTP_DEBUG_PRINTK("%s: packet:%p chunk:%p\n", __func__, packet, |
1da177e4 LT |
283 | chunk); |
284 | ||
e83963b7 VY |
285 | /* Data chunks are special. Before seeing what else we can |
286 | * bundle into this packet, check to see if we are allowed to | |
287 | * send this DATA. | |
288 | */ | |
289 | if (sctp_chunk_is_data(chunk)) { | |
290 | retval = sctp_packet_can_append_data(packet, chunk); | |
291 | if (retval != SCTP_XMIT_OK) | |
292 | goto finish; | |
293 | } | |
294 | ||
4cd57c80 VY |
295 | /* Try to bundle AUTH chunk */ |
296 | retval = sctp_packet_bundle_auth(packet, chunk); | |
297 | if (retval != SCTP_XMIT_OK) | |
298 | goto finish; | |
1da177e4 | 299 | |
4cd57c80 VY |
300 | /* Try to bundle SACK chunk */ |
301 | retval = sctp_packet_bundle_sack(packet, chunk); | |
1da177e4 LT |
302 | if (retval != SCTP_XMIT_OK) |
303 | goto finish; | |
304 | ||
e83963b7 VY |
305 | /* Check to see if this chunk will fit into the packet */ |
306 | retval = sctp_packet_will_fit(packet, chunk, chunk_len); | |
307 | if (retval != SCTP_XMIT_OK) | |
308 | goto finish; | |
1da177e4 | 309 | |
e83963b7 | 310 | /* We believe that this chunk is OK to add to the packet */ |
4cd57c80 VY |
311 | switch (chunk->chunk_hdr->type) { |
312 | case SCTP_CID_DATA: | |
e83963b7 VY |
313 | /* Account for the data being in the packet */ |
314 | sctp_packet_append_data(packet, chunk); | |
1da177e4 LT |
315 | /* Disallow SACK bundling after DATA. */ |
316 | packet->has_sack = 1; | |
4cd57c80 VY |
317 | /* Disallow AUTH bundling after DATA */ |
318 | packet->has_auth = 1; | |
319 | /* Let it be knows that packet has DATA in it */ | |
320 | packet->has_data = 1; | |
759af00e VY |
321 | /* timestamp the chunk for rtx purposes */ |
322 | chunk->sent_at = jiffies; | |
4cd57c80 VY |
323 | break; |
324 | case SCTP_CID_COOKIE_ECHO: | |
1da177e4 | 325 | packet->has_cookie_echo = 1; |
4cd57c80 VY |
326 | break; |
327 | ||
328 | case SCTP_CID_SACK: | |
1da177e4 | 329 | packet->has_sack = 1; |
4cd57c80 VY |
330 | break; |
331 | ||
332 | case SCTP_CID_AUTH: | |
333 | packet->has_auth = 1; | |
334 | packet->auth = chunk; | |
335 | break; | |
336 | } | |
1da177e4 LT |
337 | |
338 | /* It is OK to send this chunk. */ | |
79af02c2 | 339 | list_add_tail(&chunk->list, &packet->chunk_list); |
1da177e4 LT |
340 | packet->size += chunk_len; |
341 | chunk->transport = packet->transport; | |
342 | finish: | |
343 | return retval; | |
344 | } | |
345 | ||
346 | /* All packets are sent to the network through this function from | |
347 | * sctp_outq_tail(). | |
348 | * | |
349 | * The return value is a normal kernel error return value. | |
350 | */ | |
351 | int sctp_packet_transmit(struct sctp_packet *packet) | |
352 | { | |
353 | struct sctp_transport *tp = packet->transport; | |
354 | struct sctp_association *asoc = tp->asoc; | |
355 | struct sctphdr *sh; | |
1da177e4 | 356 | struct sk_buff *nskb; |
79af02c2 | 357 | struct sctp_chunk *chunk, *tmp; |
1da177e4 LT |
358 | struct sock *sk; |
359 | int err = 0; | |
360 | int padding; /* How much padding do we need? */ | |
361 | __u8 has_data = 0; | |
503b55fd | 362 | struct dst_entry *dst = tp->dst; |
4cd57c80 VY |
363 | unsigned char *auth = NULL; /* pointer to auth in skb data */ |
364 | __u32 cksum_buf_len = sizeof(struct sctphdr); | |
1da177e4 | 365 | |
0dc47877 | 366 | SCTP_DEBUG_PRINTK("%s: packet:%p\n", __func__, packet); |
1da177e4 LT |
367 | |
368 | /* Do NOT generate a chunkless packet. */ | |
79af02c2 | 369 | if (list_empty(&packet->chunk_list)) |
1da177e4 LT |
370 | return err; |
371 | ||
372 | /* Set up convenience variables... */ | |
79af02c2 | 373 | chunk = list_entry(packet->chunk_list.next, struct sctp_chunk, list); |
1da177e4 LT |
374 | sk = chunk->skb->sk; |
375 | ||
376 | /* Allocate the new skb. */ | |
594ccc14 | 377 | nskb = alloc_skb(packet->size + LL_MAX_HEADER, GFP_ATOMIC); |
1da177e4 LT |
378 | if (!nskb) |
379 | goto nomem; | |
380 | ||
381 | /* Make sure the outbound skb has enough header room reserved. */ | |
594ccc14 | 382 | skb_reserve(nskb, packet->overhead + LL_MAX_HEADER); |
1da177e4 LT |
383 | |
384 | /* Set the owning socket so that we know where to get the | |
385 | * destination IP address. | |
386 | */ | |
387 | skb_set_owner_w(nskb, sk); | |
388 | ||
503b55fd SS |
389 | /* The 'obsolete' field of dst is set to 2 when a dst is freed. */ |
390 | if (!dst || (dst->obsolete > 1)) { | |
391 | dst_release(dst); | |
392 | sctp_transport_route(tp, NULL, sctp_sk(sk)); | |
393 | if (asoc && (asoc->param_flags & SPP_PMTUD_ENABLE)) { | |
394 | sctp_assoc_sync_pmtu(asoc); | |
395 | } | |
396 | } | |
adf30907 ED |
397 | dst = dst_clone(tp->dst); |
398 | skb_dst_set(nskb, dst); | |
ff0ac74a | 399 | if (!dst) |
503b55fd | 400 | goto no_route; |
503b55fd | 401 | |
1da177e4 LT |
402 | /* Build the SCTP header. */ |
403 | sh = (struct sctphdr *)skb_push(nskb, sizeof(struct sctphdr)); | |
8dc92f7e | 404 | skb_reset_transport_header(nskb); |
1da177e4 LT |
405 | sh->source = htons(packet->source_port); |
406 | sh->dest = htons(packet->destination_port); | |
407 | ||
408 | /* From 6.8 Adler-32 Checksum Calculation: | |
409 | * After the packet is constructed (containing the SCTP common | |
410 | * header and one or more control or DATA chunks), the | |
411 | * transmitter shall: | |
412 | * | |
413 | * 1) Fill in the proper Verification Tag in the SCTP common | |
414 | * header and initialize the checksum field to 0's. | |
415 | */ | |
416 | sh->vtag = htonl(packet->vtag); | |
417 | sh->checksum = 0; | |
418 | ||
1da177e4 LT |
419 | /** |
420 | * 6.10 Bundling | |
421 | * | |
422 | * An endpoint bundles chunks by simply including multiple | |
423 | * chunks in one outbound SCTP packet. ... | |
424 | */ | |
425 | ||
426 | /** | |
427 | * 3.2 Chunk Field Descriptions | |
428 | * | |
429 | * The total length of a chunk (including Type, Length and | |
430 | * Value fields) MUST be a multiple of 4 bytes. If the length | |
431 | * of the chunk is not a multiple of 4 bytes, the sender MUST | |
432 | * pad the chunk with all zero bytes and this padding is not | |
433 | * included in the chunk length field. The sender should | |
434 | * never pad with more than 3 bytes. | |
435 | * | |
436 | * [This whole comment explains WORD_ROUND() below.] | |
437 | */ | |
438 | SCTP_DEBUG_PRINTK("***sctp_transmit_packet***\n"); | |
79af02c2 DM |
439 | list_for_each_entry_safe(chunk, tmp, &packet->chunk_list, list) { |
440 | list_del_init(&chunk->list); | |
1da177e4 LT |
441 | if (sctp_chunk_is_data(chunk)) { |
442 | ||
443 | if (!chunk->has_tsn) { | |
444 | sctp_chunk_assign_ssn(chunk); | |
445 | sctp_chunk_assign_tsn(chunk); | |
446 | ||
447 | /* 6.3.1 C4) When data is in flight and when allowed | |
448 | * by rule C5, a new RTT measurement MUST be made each | |
449 | * round trip. Furthermore, new RTT measurements | |
450 | * SHOULD be made no more than once per round-trip | |
451 | * for a given destination transport address. | |
452 | */ | |
453 | ||
454 | if (!tp->rto_pending) { | |
455 | chunk->rtt_in_progress = 1; | |
456 | tp->rto_pending = 1; | |
457 | } | |
458 | } else | |
459 | chunk->resent = 1; | |
460 | ||
1da177e4 LT |
461 | has_data = 1; |
462 | } | |
463 | ||
464 | padding = WORD_ROUND(chunk->skb->len) - chunk->skb->len; | |
465 | if (padding) | |
466 | memset(skb_put(chunk->skb, padding), 0, padding); | |
467 | ||
4cd57c80 VY |
468 | /* if this is the auth chunk that we are adding, |
469 | * store pointer where it will be added and put | |
470 | * the auth into the packet. | |
471 | */ | |
472 | if (chunk == packet->auth) | |
473 | auth = skb_tail_pointer(nskb); | |
474 | ||
475 | cksum_buf_len += chunk->skb->len; | |
476 | memcpy(skb_put(nskb, chunk->skb->len), | |
503b55fd | 477 | chunk->skb->data, chunk->skb->len); |
1da177e4 LT |
478 | |
479 | SCTP_DEBUG_PRINTK("%s %p[%s] %s 0x%x, %s %d, %s %d, %s %d\n", | |
480 | "*** Chunk", chunk, | |
481 | sctp_cname(SCTP_ST_CHUNK( | |
482 | chunk->chunk_hdr->type)), | |
483 | chunk->has_tsn ? "TSN" : "No TSN", | |
484 | chunk->has_tsn ? | |
485 | ntohl(chunk->subh.data_hdr->tsn) : 0, | |
486 | "length", ntohs(chunk->chunk_hdr->length), | |
487 | "chunk->skb->len", chunk->skb->len, | |
488 | "rtt_in_progress", chunk->rtt_in_progress); | |
489 | ||
490 | /* | |
491 | * If this is a control chunk, this is our last | |
492 | * reference. Free data chunks after they've been | |
493 | * acknowledged or have failed. | |
494 | */ | |
495 | if (!sctp_chunk_is_data(chunk)) | |
d808ad9a | 496 | sctp_chunk_free(chunk); |
1da177e4 LT |
497 | } |
498 | ||
4cd57c80 VY |
499 | /* SCTP-AUTH, Section 6.2 |
500 | * The sender MUST calculate the MAC as described in RFC2104 [2] | |
501 | * using the hash function H as described by the MAC Identifier and | |
502 | * the shared association key K based on the endpoint pair shared key | |
503 | * described by the shared key identifier. The 'data' used for the | |
504 | * computation of the AUTH-chunk is given by the AUTH chunk with its | |
505 | * HMAC field set to zero (as shown in Figure 6) followed by all | |
506 | * chunks that are placed after the AUTH chunk in the SCTP packet. | |
507 | */ | |
508 | if (auth) | |
509 | sctp_auth_calculate_hmac(asoc, nskb, | |
510 | (struct sctp_auth_chunk *)auth, | |
511 | GFP_ATOMIC); | |
512 | ||
513 | /* 2) Calculate the Adler-32 checksum of the whole packet, | |
514 | * including the SCTP common header and all the | |
515 | * chunks. | |
516 | * | |
517 | * Note: Adler-32 is no longer applicable, as has been replaced | |
518 | * by CRC32-C as described in <draft-ietf-tsvwg-sctpcsum-02.txt>. | |
519 | */ | |
8dc92f7e JB |
520 | if (!sctp_checksum_disable && |
521 | !(dst->dev->features & (NETIF_F_NO_CSUM | NETIF_F_SCTP_CSUM))) { | |
4458f04c VY |
522 | __u32 crc32 = sctp_start_cksum((__u8 *)sh, cksum_buf_len); |
523 | ||
524 | /* 3) Put the resultant value into the checksum field in the | |
525 | * common header, and leave the rest of the bits unchanged. | |
526 | */ | |
527 | sh->checksum = sctp_end_cksum(crc32); | |
8dc92f7e JB |
528 | } else { |
529 | if (dst->dev->features & NETIF_F_SCTP_CSUM) { | |
530 | /* no need to seed psuedo checksum for SCTP */ | |
531 | nskb->ip_summed = CHECKSUM_PARTIAL; | |
532 | nskb->csum_start = (skb_transport_header(nskb) - | |
533 | nskb->head); | |
534 | nskb->csum_offset = offsetof(struct sctphdr, checksum); | |
535 | } else { | |
536 | nskb->ip_summed = CHECKSUM_UNNECESSARY; | |
537 | } | |
538 | } | |
1da177e4 | 539 | |
1da177e4 LT |
540 | /* IP layer ECN support |
541 | * From RFC 2481 | |
542 | * "The ECN-Capable Transport (ECT) bit would be set by the | |
543 | * data sender to indicate that the end-points of the | |
544 | * transport protocol are ECN-capable." | |
545 | * | |
546 | * Now setting the ECT bit all the time, as it should not cause | |
547 | * any problems protocol-wise even if our peer ignores it. | |
548 | * | |
549 | * Note: The works for IPv6 layer checks this bit too later | |
550 | * in transmission. See IP6_ECN_flow_xmit(). | |
551 | */ | |
b9031d9d | 552 | (*tp->af_specific->ecn_capable)(nskb->sk); |
1da177e4 LT |
553 | |
554 | /* Set up the IP options. */ | |
555 | /* BUG: not implemented | |
556 | * For v4 this all lives somewhere in sk->sk_opt... | |
557 | */ | |
558 | ||
559 | /* Dump that on IP! */ | |
560 | if (asoc && asoc->peer.last_sent_to != tp) { | |
561 | /* Considering the multiple CPU scenario, this is a | |
562 | * "correcter" place for last_sent_to. --xguo | |
563 | */ | |
564 | asoc->peer.last_sent_to = tp; | |
565 | } | |
566 | ||
567 | if (has_data) { | |
568 | struct timer_list *timer; | |
569 | unsigned long timeout; | |
570 | ||
571 | tp->last_time_used = jiffies; | |
572 | ||
573 | /* Restart the AUTOCLOSE timer when sending data. */ | |
574 | if (sctp_state(asoc, ESTABLISHED) && asoc->autoclose) { | |
575 | timer = &asoc->timers[SCTP_EVENT_TIMEOUT_AUTOCLOSE]; | |
576 | timeout = asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE]; | |
577 | ||
578 | if (!mod_timer(timer, jiffies + timeout)) | |
579 | sctp_association_hold(asoc); | |
580 | } | |
581 | } | |
582 | ||
1da177e4 LT |
583 | SCTP_DEBUG_PRINTK("***sctp_transmit_packet*** skb len %d\n", |
584 | nskb->len); | |
585 | ||
f880374c HX |
586 | nskb->local_df = packet->ipfragok; |
587 | (*tp->af_specific->sctp_xmit)(nskb, tp); | |
1da177e4 LT |
588 | |
589 | out: | |
d521c08f | 590 | sctp_packet_reset(packet); |
1da177e4 LT |
591 | return err; |
592 | no_route: | |
593 | kfree_skb(nskb); | |
7c73a6fa | 594 | IP_INC_STATS_BH(&init_net, IPSTATS_MIB_OUTNOROUTES); |
1da177e4 LT |
595 | |
596 | /* FIXME: Returning the 'err' will effect all the associations | |
597 | * associated with a socket, although only one of the paths of the | |
598 | * association is unreachable. | |
599 | * The real failure of a transport or association can be passed on | |
600 | * to the user via notifications. So setting this error may not be | |
601 | * required. | |
602 | */ | |
603 | /* err = -EHOSTUNREACH; */ | |
604 | err: | |
605 | /* Control chunks are unreliable so just drop them. DATA chunks | |
606 | * will get resent or dropped later. | |
607 | */ | |
608 | ||
79af02c2 DM |
609 | list_for_each_entry_safe(chunk, tmp, &packet->chunk_list, list) { |
610 | list_del_init(&chunk->list); | |
1da177e4 | 611 | if (!sctp_chunk_is_data(chunk)) |
d808ad9a | 612 | sctp_chunk_free(chunk); |
1da177e4 LT |
613 | } |
614 | goto out; | |
615 | nomem: | |
616 | err = -ENOMEM; | |
617 | goto err; | |
618 | } | |
619 | ||
620 | /******************************************************************** | |
621 | * 2nd Level Abstractions | |
622 | ********************************************************************/ | |
623 | ||
e83963b7 VY |
624 | /* This private function check to see if a chunk can be added */ |
625 | static sctp_xmit_t sctp_packet_can_append_data(struct sctp_packet *packet, | |
1da177e4 LT |
626 | struct sctp_chunk *chunk) |
627 | { | |
628 | sctp_xmit_t retval = SCTP_XMIT_OK; | |
e83963b7 | 629 | size_t datasize, rwnd, inflight, flight_size; |
1da177e4 LT |
630 | struct sctp_transport *transport = packet->transport; |
631 | __u32 max_burst_bytes; | |
632 | struct sctp_association *asoc = transport->asoc; | |
1da177e4 LT |
633 | struct sctp_outq *q = &asoc->outqueue; |
634 | ||
635 | /* RFC 2960 6.1 Transmission of DATA Chunks | |
636 | * | |
637 | * A) At any given time, the data sender MUST NOT transmit new data to | |
638 | * any destination transport address if its peer's rwnd indicates | |
639 | * that the peer has no buffer space (i.e. rwnd is 0, see Section | |
640 | * 6.2.1). However, regardless of the value of rwnd (including if it | |
641 | * is 0), the data sender can always have one DATA chunk in flight to | |
642 | * the receiver if allowed by cwnd (see rule B below). This rule | |
643 | * allows the sender to probe for a change in rwnd that the sender | |
644 | * missed due to the SACK having been lost in transit from the data | |
645 | * receiver to the data sender. | |
646 | */ | |
647 | ||
648 | rwnd = asoc->peer.rwnd; | |
e83963b7 VY |
649 | inflight = q->outstanding_bytes; |
650 | flight_size = transport->flight_size; | |
1da177e4 LT |
651 | |
652 | datasize = sctp_data_size(chunk); | |
653 | ||
654 | if (datasize > rwnd) { | |
655 | if (inflight > 0) { | |
656 | /* We have (at least) one data chunk in flight, | |
657 | * so we can't fall back to rule 6.1 B). | |
658 | */ | |
659 | retval = SCTP_XMIT_RWND_FULL; | |
660 | goto finish; | |
661 | } | |
662 | } | |
663 | ||
664 | /* sctpimpguide-05 2.14.2 | |
665 | * D) When the time comes for the sender to | |
666 | * transmit new DATA chunks, the protocol parameter Max.Burst MUST | |
667 | * first be applied to limit how many new DATA chunks may be sent. | |
668 | * The limit is applied by adjusting cwnd as follows: | |
669 | * if ((flightsize + Max.Burst * MTU) < cwnd) | |
670 | * cwnd = flightsize + Max.Burst * MTU | |
671 | */ | |
52ccb8e9 | 672 | max_burst_bytes = asoc->max_burst * asoc->pathmtu; |
e83963b7 VY |
673 | if ((flight_size + max_burst_bytes) < transport->cwnd) { |
674 | transport->cwnd = flight_size + max_burst_bytes; | |
1da177e4 LT |
675 | SCTP_DEBUG_PRINTK("%s: cwnd limited by max_burst: " |
676 | "transport: %p, cwnd: %d, " | |
677 | "ssthresh: %d, flight_size: %d, " | |
678 | "pba: %d\n", | |
0dc47877 | 679 | __func__, transport, |
1da177e4 LT |
680 | transport->cwnd, |
681 | transport->ssthresh, | |
682 | transport->flight_size, | |
683 | transport->partial_bytes_acked); | |
684 | } | |
685 | ||
686 | /* RFC 2960 6.1 Transmission of DATA Chunks | |
687 | * | |
688 | * B) At any given time, the sender MUST NOT transmit new data | |
689 | * to a given transport address if it has cwnd or more bytes | |
690 | * of data outstanding to that transport address. | |
691 | */ | |
692 | /* RFC 7.2.4 & the Implementers Guide 2.8. | |
693 | * | |
694 | * 3) ... | |
695 | * When a Fast Retransmit is being performed the sender SHOULD | |
696 | * ignore the value of cwnd and SHOULD NOT delay retransmission. | |
697 | */ | |
c226ef9b | 698 | if (chunk->fast_retransmit != SCTP_NEED_FRTX) |
e83963b7 | 699 | if (flight_size >= transport->cwnd) { |
1da177e4 LT |
700 | retval = SCTP_XMIT_RWND_FULL; |
701 | goto finish; | |
702 | } | |
703 | ||
704 | /* Nagle's algorithm to solve small-packet problem: | |
705 | * Inhibit the sending of new chunks when new outgoing data arrives | |
706 | * if any previously transmitted data on the connection remains | |
707 | * unacknowledged. | |
708 | */ | |
e83963b7 VY |
709 | if (!sctp_sk(asoc->base.sk)->nodelay && sctp_packet_empty(packet) && |
710 | inflight && sctp_state(asoc, ESTABLISHED)) { | |
b29e7907 VY |
711 | unsigned max = transport->pathmtu - packet->overhead; |
712 | unsigned len = chunk->skb->len + q->out_qlen; | |
1da177e4 LT |
713 | |
714 | /* Check whether this chunk and all the rest of pending | |
715 | * data will fit or delay in hopes of bundling a full | |
716 | * sized packet. | |
cb95ea32 VY |
717 | * Don't delay large message writes that may have been |
718 | * fragmeneted into small peices. | |
1da177e4 | 719 | */ |
cb95ea32 | 720 | if ((len < max) && (chunk->msg->msg_size < max)) { |
1da177e4 LT |
721 | retval = SCTP_XMIT_NAGLE_DELAY; |
722 | goto finish; | |
723 | } | |
724 | } | |
725 | ||
e83963b7 VY |
726 | finish: |
727 | return retval; | |
728 | } | |
729 | ||
730 | /* This private function does management things when adding DATA chunk */ | |
731 | static void sctp_packet_append_data(struct sctp_packet *packet, | |
732 | struct sctp_chunk *chunk) | |
733 | { | |
734 | struct sctp_transport *transport = packet->transport; | |
735 | size_t datasize = sctp_data_size(chunk); | |
736 | struct sctp_association *asoc = transport->asoc; | |
737 | u32 rwnd = asoc->peer.rwnd; | |
738 | ||
1da177e4 LT |
739 | /* Keep track of how many bytes are in flight over this transport. */ |
740 | transport->flight_size += datasize; | |
741 | ||
742 | /* Keep track of how many bytes are in flight to the receiver. */ | |
743 | asoc->outqueue.outstanding_bytes += datasize; | |
744 | ||
cd497885 SS |
745 | /* Update our view of the receiver's rwnd. Include sk_buff overhead |
746 | * while updating peer.rwnd so that it reduces the chances of a | |
747 | * receiver running out of receive buffer space even when receive | |
748 | * window is still open. This can happen when a sender is sending | |
749 | * sending small messages. | |
750 | */ | |
751 | datasize += sizeof(struct sk_buff); | |
1da177e4 LT |
752 | if (datasize < rwnd) |
753 | rwnd -= datasize; | |
754 | else | |
755 | rwnd = 0; | |
756 | ||
757 | asoc->peer.rwnd = rwnd; | |
758 | /* Has been accepted for transmission. */ | |
759 | if (!asoc->peer.prsctp_capable) | |
760 | chunk->msg->can_abandon = 0; | |
e83963b7 VY |
761 | } |
762 | ||
763 | static sctp_xmit_t sctp_packet_will_fit(struct sctp_packet *packet, | |
764 | struct sctp_chunk *chunk, | |
765 | u16 chunk_len) | |
766 | { | |
767 | size_t psize; | |
768 | size_t pmtu; | |
769 | int too_big; | |
770 | sctp_xmit_t retval = SCTP_XMIT_OK; | |
771 | ||
772 | psize = packet->size; | |
773 | pmtu = ((packet->transport->asoc) ? | |
774 | (packet->transport->asoc->pathmtu) : | |
775 | (packet->transport->pathmtu)); | |
776 | ||
777 | too_big = (psize + chunk_len > pmtu); | |
778 | ||
779 | /* Decide if we need to fragment or resubmit later. */ | |
780 | if (too_big) { | |
781 | /* It's OK to fragmet at IP level if any one of the following | |
782 | * is true: | |
783 | * 1. The packet is empty (meaning this chunk is greater | |
784 | * the MTU) | |
785 | * 2. The chunk we are adding is a control chunk | |
786 | * 3. The packet doesn't have any data in it yet and data | |
787 | * requires authentication. | |
788 | */ | |
789 | if (sctp_packet_empty(packet) || !sctp_chunk_is_data(chunk) || | |
790 | (!packet->has_data && chunk->auth)) { | |
791 | /* We no longer do re-fragmentation. | |
792 | * Just fragment at the IP layer, if we | |
793 | * actually hit this condition | |
794 | */ | |
795 | packet->ipfragok = 1; | |
796 | } else { | |
797 | retval = SCTP_XMIT_PMTU_FULL; | |
798 | } | |
799 | } | |
1da177e4 | 800 | |
1da177e4 LT |
801 | return retval; |
802 | } |