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