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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> | |
52 | #include <net/icmp.h> | |
53 | ||
54 | #ifndef TEST_FRAME | |
55 | #include <net/tcp.h> | |
56 | #endif /* TEST_FRAME (not defined) */ | |
57 | ||
58 | #include <linux/socket.h> /* for sa_family_t */ | |
59 | #include <net/sock.h> | |
60 | ||
61 | #include <net/sctp/sctp.h> | |
62 | #include <net/sctp/sm.h> | |
9ad0977f | 63 | #include <net/sctp/checksum.h> |
1da177e4 LT |
64 | |
65 | /* Forward declarations for private helpers. */ | |
66 | static sctp_xmit_t sctp_packet_append_data(struct sctp_packet *packet, | |
67 | struct sctp_chunk *chunk); | |
68 | ||
69 | /* Config a packet. | |
70 | * This appears to be a followup set of initializations. | |
71 | */ | |
72 | struct sctp_packet *sctp_packet_config(struct sctp_packet *packet, | |
73 | __u32 vtag, int ecn_capable) | |
74 | { | |
75 | struct sctp_chunk *chunk = NULL; | |
76 | ||
0dc47877 | 77 | SCTP_DEBUG_PRINTK("%s: packet:%p vtag:0x%x\n", __func__, |
1da177e4 LT |
78 | packet, vtag); |
79 | ||
80 | packet->vtag = vtag; | |
81 | packet->has_cookie_echo = 0; | |
82 | packet->has_sack = 0; | |
a29a5bd4 | 83 | packet->has_auth = 0; |
4cd57c80 | 84 | packet->has_data = 0; |
1da177e4 | 85 | packet->ipfragok = 0; |
a29a5bd4 | 86 | packet->auth = NULL; |
1da177e4 LT |
87 | |
88 | if (ecn_capable && sctp_packet_empty(packet)) { | |
89 | chunk = sctp_get_ecne_prepend(packet->transport->asoc); | |
90 | ||
91 | /* If there a is a prepend chunk stick it on the list before | |
d808ad9a YH |
92 | * any other chunks get appended. |
93 | */ | |
1da177e4 LT |
94 | if (chunk) |
95 | sctp_packet_append_chunk(packet, chunk); | |
96 | } | |
97 | ||
98 | return packet; | |
99 | } | |
100 | ||
101 | /* Initialize the packet structure. */ | |
102 | struct sctp_packet *sctp_packet_init(struct sctp_packet *packet, | |
103 | struct sctp_transport *transport, | |
104 | __u16 sport, __u16 dport) | |
105 | { | |
106 | struct sctp_association *asoc = transport->asoc; | |
107 | size_t overhead; | |
108 | ||
0dc47877 | 109 | SCTP_DEBUG_PRINTK("%s: packet:%p transport:%p\n", __func__, |
1da177e4 LT |
110 | packet, transport); |
111 | ||
112 | packet->transport = transport; | |
113 | packet->source_port = sport; | |
114 | packet->destination_port = dport; | |
79af02c2 | 115 | INIT_LIST_HEAD(&packet->chunk_list); |
1da177e4 | 116 | if (asoc) { |
d808ad9a YH |
117 | struct sctp_sock *sp = sctp_sk(asoc->base.sk); |
118 | overhead = sp->pf->af->net_header_len; | |
1da177e4 LT |
119 | } else { |
120 | overhead = sizeof(struct ipv6hdr); | |
121 | } | |
122 | overhead += sizeof(struct sctphdr); | |
123 | packet->overhead = overhead; | |
124 | packet->size = overhead; | |
125 | packet->vtag = 0; | |
126 | packet->has_cookie_echo = 0; | |
127 | packet->has_sack = 0; | |
a29a5bd4 | 128 | packet->has_auth = 0; |
4cd57c80 | 129 | packet->has_data = 0; |
1da177e4 LT |
130 | packet->ipfragok = 0; |
131 | packet->malloced = 0; | |
a29a5bd4 | 132 | packet->auth = NULL; |
1da177e4 LT |
133 | return packet; |
134 | } | |
135 | ||
136 | /* Free a packet. */ | |
137 | void sctp_packet_free(struct sctp_packet *packet) | |
138 | { | |
79af02c2 | 139 | struct sctp_chunk *chunk, *tmp; |
1da177e4 | 140 | |
0dc47877 | 141 | SCTP_DEBUG_PRINTK("%s: packet:%p\n", __func__, packet); |
1da177e4 | 142 | |
79af02c2 DM |
143 | list_for_each_entry_safe(chunk, tmp, &packet->chunk_list, list) { |
144 | list_del_init(&chunk->list); | |
1da177e4 | 145 | sctp_chunk_free(chunk); |
79af02c2 | 146 | } |
1da177e4 LT |
147 | |
148 | if (packet->malloced) | |
149 | kfree(packet); | |
150 | } | |
151 | ||
152 | /* This routine tries to append the chunk to the offered packet. If adding | |
153 | * the chunk causes the packet to exceed the path MTU and COOKIE_ECHO chunk | |
154 | * is not present in the packet, it transmits the input packet. | |
155 | * Data can be bundled with a packet containing a COOKIE_ECHO chunk as long | |
156 | * as it can fit in the packet, but any more data that does not fit in this | |
157 | * packet can be sent only after receiving the COOKIE_ACK. | |
158 | */ | |
159 | sctp_xmit_t sctp_packet_transmit_chunk(struct sctp_packet *packet, | |
160 | struct sctp_chunk *chunk) | |
161 | { | |
162 | sctp_xmit_t retval; | |
163 | int error = 0; | |
164 | ||
0dc47877 | 165 | SCTP_DEBUG_PRINTK("%s: packet:%p chunk:%p\n", __func__, |
1da177e4 LT |
166 | packet, chunk); |
167 | ||
168 | switch ((retval = (sctp_packet_append_chunk(packet, chunk)))) { | |
169 | case SCTP_XMIT_PMTU_FULL: | |
170 | if (!packet->has_cookie_echo) { | |
171 | error = sctp_packet_transmit(packet); | |
172 | if (error < 0) | |
173 | chunk->skb->sk->sk_err = -error; | |
174 | ||
175 | /* If we have an empty packet, then we can NOT ever | |
176 | * return PMTU_FULL. | |
177 | */ | |
178 | retval = sctp_packet_append_chunk(packet, chunk); | |
179 | } | |
180 | break; | |
181 | ||
182 | case SCTP_XMIT_RWND_FULL: | |
183 | case SCTP_XMIT_OK: | |
184 | case SCTP_XMIT_NAGLE_DELAY: | |
185 | break; | |
3ff50b79 | 186 | } |
1da177e4 LT |
187 | |
188 | return retval; | |
189 | } | |
190 | ||
4cd57c80 VY |
191 | /* Try to bundle an auth chunk into the packet. */ |
192 | static sctp_xmit_t sctp_packet_bundle_auth(struct sctp_packet *pkt, | |
193 | struct sctp_chunk *chunk) | |
194 | { | |
195 | struct sctp_association *asoc = pkt->transport->asoc; | |
196 | struct sctp_chunk *auth; | |
197 | sctp_xmit_t retval = SCTP_XMIT_OK; | |
198 | ||
199 | /* if we don't have an association, we can't do authentication */ | |
200 | if (!asoc) | |
201 | return retval; | |
202 | ||
203 | /* See if this is an auth chunk we are bundling or if | |
204 | * auth is already bundled. | |
205 | */ | |
206 | if (chunk->chunk_hdr->type == SCTP_CID_AUTH || pkt->auth) | |
207 | return retval; | |
208 | ||
209 | /* if the peer did not request this chunk to be authenticated, | |
210 | * don't do it | |
211 | */ | |
212 | if (!chunk->auth) | |
213 | return retval; | |
214 | ||
215 | auth = sctp_make_auth(asoc); | |
216 | if (!auth) | |
217 | return retval; | |
218 | ||
219 | retval = sctp_packet_append_chunk(pkt, auth); | |
220 | ||
221 | return retval; | |
222 | } | |
223 | ||
1da177e4 LT |
224 | /* Try to bundle a SACK with the packet. */ |
225 | static sctp_xmit_t sctp_packet_bundle_sack(struct sctp_packet *pkt, | |
226 | struct sctp_chunk *chunk) | |
227 | { | |
228 | sctp_xmit_t retval = SCTP_XMIT_OK; | |
229 | ||
230 | /* If sending DATA and haven't aleady bundled a SACK, try to | |
231 | * bundle one in to the packet. | |
232 | */ | |
233 | if (sctp_chunk_is_data(chunk) && !pkt->has_sack && | |
234 | !pkt->has_cookie_echo) { | |
235 | struct sctp_association *asoc; | |
236 | asoc = pkt->transport->asoc; | |
237 | ||
238 | if (asoc->a_rwnd > asoc->rwnd) { | |
239 | struct sctp_chunk *sack; | |
240 | asoc->a_rwnd = asoc->rwnd; | |
241 | sack = sctp_make_sack(asoc); | |
242 | if (sack) { | |
243 | struct timer_list *timer; | |
244 | retval = sctp_packet_append_chunk(pkt, sack); | |
245 | asoc->peer.sack_needed = 0; | |
246 | timer = &asoc->timers[SCTP_EVENT_TIMEOUT_SACK]; | |
247 | if (timer_pending(timer) && del_timer(timer)) | |
248 | sctp_association_put(asoc); | |
249 | } | |
250 | } | |
251 | } | |
252 | return retval; | |
253 | } | |
254 | ||
255 | /* Append a chunk to the offered packet reporting back any inability to do | |
256 | * so. | |
257 | */ | |
258 | sctp_xmit_t sctp_packet_append_chunk(struct sctp_packet *packet, | |
259 | struct sctp_chunk *chunk) | |
260 | { | |
261 | sctp_xmit_t retval = SCTP_XMIT_OK; | |
262 | __u16 chunk_len = WORD_ROUND(ntohs(chunk->chunk_hdr->length)); | |
263 | size_t psize; | |
264 | size_t pmtu; | |
265 | int too_big; | |
266 | ||
0dc47877 | 267 | SCTP_DEBUG_PRINTK("%s: packet:%p chunk:%p\n", __func__, packet, |
1da177e4 LT |
268 | chunk); |
269 | ||
4cd57c80 VY |
270 | /* Try to bundle AUTH chunk */ |
271 | retval = sctp_packet_bundle_auth(packet, chunk); | |
272 | if (retval != SCTP_XMIT_OK) | |
273 | goto finish; | |
1da177e4 | 274 | |
4cd57c80 VY |
275 | /* Try to bundle SACK chunk */ |
276 | retval = sctp_packet_bundle_sack(packet, chunk); | |
1da177e4 LT |
277 | if (retval != SCTP_XMIT_OK) |
278 | goto finish; | |
279 | ||
4cd57c80 | 280 | psize = packet->size; |
1da177e4 | 281 | pmtu = ((packet->transport->asoc) ? |
52ccb8e9 FF |
282 | (packet->transport->asoc->pathmtu) : |
283 | (packet->transport->pathmtu)); | |
1da177e4 LT |
284 | |
285 | too_big = (psize + chunk_len > pmtu); | |
286 | ||
287 | /* Decide if we need to fragment or resubmit later. */ | |
288 | if (too_big) { | |
4cd57c80 VY |
289 | /* It's OK to fragmet at IP level if any one of the following |
290 | * is true: | |
291 | * 1. The packet is empty (meaning this chunk is greater | |
292 | * the MTU) | |
293 | * 2. The chunk we are adding is a control chunk | |
294 | * 3. The packet doesn't have any data in it yet and data | |
295 | * requires authentication. | |
1da177e4 | 296 | */ |
4cd57c80 VY |
297 | if (sctp_packet_empty(packet) || !sctp_chunk_is_data(chunk) || |
298 | (!packet->has_data && chunk->auth)) { | |
1da177e4 LT |
299 | /* We no longer do re-fragmentation. |
300 | * Just fragment at the IP layer, if we | |
301 | * actually hit this condition | |
302 | */ | |
303 | packet->ipfragok = 1; | |
304 | goto append; | |
305 | ||
306 | } else { | |
307 | retval = SCTP_XMIT_PMTU_FULL; | |
308 | goto finish; | |
309 | } | |
310 | } | |
311 | ||
312 | append: | |
313 | /* We believe that this chunk is OK to add to the packet (as | |
314 | * long as we have the cwnd for it). | |
315 | */ | |
316 | ||
317 | /* DATA is a special case since we must examine both rwnd and cwnd | |
318 | * before we send DATA. | |
319 | */ | |
4cd57c80 VY |
320 | switch (chunk->chunk_hdr->type) { |
321 | case SCTP_CID_DATA: | |
1da177e4 LT |
322 | retval = sctp_packet_append_data(packet, chunk); |
323 | /* Disallow SACK bundling after DATA. */ | |
324 | packet->has_sack = 1; | |
4cd57c80 VY |
325 | /* Disallow AUTH bundling after DATA */ |
326 | packet->has_auth = 1; | |
327 | /* Let it be knows that packet has DATA in it */ | |
328 | packet->has_data = 1; | |
1da177e4 LT |
329 | if (SCTP_XMIT_OK != retval) |
330 | goto finish; | |
4cd57c80 VY |
331 | break; |
332 | case SCTP_CID_COOKIE_ECHO: | |
1da177e4 | 333 | packet->has_cookie_echo = 1; |
4cd57c80 VY |
334 | break; |
335 | ||
336 | case SCTP_CID_SACK: | |
1da177e4 | 337 | packet->has_sack = 1; |
4cd57c80 VY |
338 | break; |
339 | ||
340 | case SCTP_CID_AUTH: | |
341 | packet->has_auth = 1; | |
342 | packet->auth = chunk; | |
343 | break; | |
344 | } | |
1da177e4 LT |
345 | |
346 | /* It is OK to send this chunk. */ | |
79af02c2 | 347 | list_add_tail(&chunk->list, &packet->chunk_list); |
1da177e4 LT |
348 | packet->size += chunk_len; |
349 | chunk->transport = packet->transport; | |
350 | finish: | |
351 | return retval; | |
352 | } | |
353 | ||
354 | /* All packets are sent to the network through this function from | |
355 | * sctp_outq_tail(). | |
356 | * | |
357 | * The return value is a normal kernel error return value. | |
358 | */ | |
359 | int sctp_packet_transmit(struct sctp_packet *packet) | |
360 | { | |
361 | struct sctp_transport *tp = packet->transport; | |
362 | struct sctp_association *asoc = tp->asoc; | |
363 | struct sctphdr *sh; | |
503b55fd | 364 | __u32 crc32 = 0; |
1da177e4 | 365 | struct sk_buff *nskb; |
79af02c2 | 366 | struct sctp_chunk *chunk, *tmp; |
1da177e4 LT |
367 | struct sock *sk; |
368 | int err = 0; | |
369 | int padding; /* How much padding do we need? */ | |
370 | __u8 has_data = 0; | |
503b55fd | 371 | struct dst_entry *dst = tp->dst; |
4cd57c80 VY |
372 | unsigned char *auth = NULL; /* pointer to auth in skb data */ |
373 | __u32 cksum_buf_len = sizeof(struct sctphdr); | |
1da177e4 | 374 | |
0dc47877 | 375 | SCTP_DEBUG_PRINTK("%s: packet:%p\n", __func__, packet); |
1da177e4 LT |
376 | |
377 | /* Do NOT generate a chunkless packet. */ | |
79af02c2 | 378 | if (list_empty(&packet->chunk_list)) |
1da177e4 LT |
379 | return err; |
380 | ||
381 | /* Set up convenience variables... */ | |
79af02c2 | 382 | chunk = list_entry(packet->chunk_list.next, struct sctp_chunk, list); |
1da177e4 LT |
383 | sk = chunk->skb->sk; |
384 | ||
385 | /* Allocate the new skb. */ | |
594ccc14 | 386 | nskb = alloc_skb(packet->size + LL_MAX_HEADER, GFP_ATOMIC); |
1da177e4 LT |
387 | if (!nskb) |
388 | goto nomem; | |
389 | ||
390 | /* Make sure the outbound skb has enough header room reserved. */ | |
594ccc14 | 391 | skb_reserve(nskb, packet->overhead + LL_MAX_HEADER); |
1da177e4 LT |
392 | |
393 | /* Set the owning socket so that we know where to get the | |
394 | * destination IP address. | |
395 | */ | |
396 | skb_set_owner_w(nskb, sk); | |
397 | ||
503b55fd SS |
398 | /* The 'obsolete' field of dst is set to 2 when a dst is freed. */ |
399 | if (!dst || (dst->obsolete > 1)) { | |
400 | dst_release(dst); | |
401 | sctp_transport_route(tp, NULL, sctp_sk(sk)); | |
402 | if (asoc && (asoc->param_flags & SPP_PMTUD_ENABLE)) { | |
403 | sctp_assoc_sync_pmtu(asoc); | |
404 | } | |
405 | } | |
406 | nskb->dst = dst_clone(tp->dst); | |
407 | if (!nskb->dst) | |
408 | goto no_route; | |
409 | dst = nskb->dst; | |
410 | ||
1da177e4 LT |
411 | /* Build the SCTP header. */ |
412 | sh = (struct sctphdr *)skb_push(nskb, sizeof(struct sctphdr)); | |
413 | sh->source = htons(packet->source_port); | |
414 | sh->dest = htons(packet->destination_port); | |
415 | ||
416 | /* From 6.8 Adler-32 Checksum Calculation: | |
417 | * After the packet is constructed (containing the SCTP common | |
418 | * header and one or more control or DATA chunks), the | |
419 | * transmitter shall: | |
420 | * | |
421 | * 1) Fill in the proper Verification Tag in the SCTP common | |
422 | * header and initialize the checksum field to 0's. | |
423 | */ | |
424 | sh->vtag = htonl(packet->vtag); | |
425 | sh->checksum = 0; | |
426 | ||
1da177e4 LT |
427 | /** |
428 | * 6.10 Bundling | |
429 | * | |
430 | * An endpoint bundles chunks by simply including multiple | |
431 | * chunks in one outbound SCTP packet. ... | |
432 | */ | |
433 | ||
434 | /** | |
435 | * 3.2 Chunk Field Descriptions | |
436 | * | |
437 | * The total length of a chunk (including Type, Length and | |
438 | * Value fields) MUST be a multiple of 4 bytes. If the length | |
439 | * of the chunk is not a multiple of 4 bytes, the sender MUST | |
440 | * pad the chunk with all zero bytes and this padding is not | |
441 | * included in the chunk length field. The sender should | |
442 | * never pad with more than 3 bytes. | |
443 | * | |
444 | * [This whole comment explains WORD_ROUND() below.] | |
445 | */ | |
446 | SCTP_DEBUG_PRINTK("***sctp_transmit_packet***\n"); | |
79af02c2 DM |
447 | list_for_each_entry_safe(chunk, tmp, &packet->chunk_list, list) { |
448 | list_del_init(&chunk->list); | |
1da177e4 LT |
449 | if (sctp_chunk_is_data(chunk)) { |
450 | ||
451 | if (!chunk->has_tsn) { | |
452 | sctp_chunk_assign_ssn(chunk); | |
453 | sctp_chunk_assign_tsn(chunk); | |
454 | ||
455 | /* 6.3.1 C4) When data is in flight and when allowed | |
456 | * by rule C5, a new RTT measurement MUST be made each | |
457 | * round trip. Furthermore, new RTT measurements | |
458 | * SHOULD be made no more than once per round-trip | |
459 | * for a given destination transport address. | |
460 | */ | |
461 | ||
462 | if (!tp->rto_pending) { | |
463 | chunk->rtt_in_progress = 1; | |
464 | tp->rto_pending = 1; | |
465 | } | |
466 | } else | |
467 | chunk->resent = 1; | |
468 | ||
469 | chunk->sent_at = jiffies; | |
470 | has_data = 1; | |
471 | } | |
472 | ||
473 | padding = WORD_ROUND(chunk->skb->len) - chunk->skb->len; | |
474 | if (padding) | |
475 | memset(skb_put(chunk->skb, padding), 0, padding); | |
476 | ||
4cd57c80 VY |
477 | /* if this is the auth chunk that we are adding, |
478 | * store pointer where it will be added and put | |
479 | * the auth into the packet. | |
480 | */ | |
481 | if (chunk == packet->auth) | |
482 | auth = skb_tail_pointer(nskb); | |
483 | ||
484 | cksum_buf_len += chunk->skb->len; | |
485 | memcpy(skb_put(nskb, chunk->skb->len), | |
503b55fd | 486 | chunk->skb->data, chunk->skb->len); |
1da177e4 LT |
487 | |
488 | SCTP_DEBUG_PRINTK("%s %p[%s] %s 0x%x, %s %d, %s %d, %s %d\n", | |
489 | "*** Chunk", chunk, | |
490 | sctp_cname(SCTP_ST_CHUNK( | |
491 | chunk->chunk_hdr->type)), | |
492 | chunk->has_tsn ? "TSN" : "No TSN", | |
493 | chunk->has_tsn ? | |
494 | ntohl(chunk->subh.data_hdr->tsn) : 0, | |
495 | "length", ntohs(chunk->chunk_hdr->length), | |
496 | "chunk->skb->len", chunk->skb->len, | |
497 | "rtt_in_progress", chunk->rtt_in_progress); | |
498 | ||
499 | /* | |
500 | * If this is a control chunk, this is our last | |
501 | * reference. Free data chunks after they've been | |
502 | * acknowledged or have failed. | |
503 | */ | |
504 | if (!sctp_chunk_is_data(chunk)) | |
d808ad9a | 505 | sctp_chunk_free(chunk); |
1da177e4 LT |
506 | } |
507 | ||
4cd57c80 VY |
508 | /* SCTP-AUTH, Section 6.2 |
509 | * The sender MUST calculate the MAC as described in RFC2104 [2] | |
510 | * using the hash function H as described by the MAC Identifier and | |
511 | * the shared association key K based on the endpoint pair shared key | |
512 | * described by the shared key identifier. The 'data' used for the | |
513 | * computation of the AUTH-chunk is given by the AUTH chunk with its | |
514 | * HMAC field set to zero (as shown in Figure 6) followed by all | |
515 | * chunks that are placed after the AUTH chunk in the SCTP packet. | |
516 | */ | |
517 | if (auth) | |
518 | sctp_auth_calculate_hmac(asoc, nskb, | |
519 | (struct sctp_auth_chunk *)auth, | |
520 | GFP_ATOMIC); | |
521 | ||
522 | /* 2) Calculate the Adler-32 checksum of the whole packet, | |
523 | * including the SCTP common header and all the | |
524 | * chunks. | |
525 | * | |
526 | * Note: Adler-32 is no longer applicable, as has been replaced | |
527 | * by CRC32-C as described in <draft-ietf-tsvwg-sctpcsum-02.txt>. | |
528 | */ | |
529 | if (!(dst->dev->features & NETIF_F_NO_CSUM)) { | |
530 | crc32 = sctp_start_cksum((__u8 *)sh, cksum_buf_len); | |
503b55fd | 531 | crc32 = sctp_end_cksum(crc32); |
4cd57c80 | 532 | } |
1da177e4 LT |
533 | |
534 | /* 3) Put the resultant value into the checksum field in the | |
535 | * common header, and leave the rest of the bits unchanged. | |
536 | */ | |
537 | sh->checksum = htonl(crc32); | |
538 | ||
539 | /* IP layer ECN support | |
540 | * From RFC 2481 | |
541 | * "The ECN-Capable Transport (ECT) bit would be set by the | |
542 | * data sender to indicate that the end-points of the | |
543 | * transport protocol are ECN-capable." | |
544 | * | |
545 | * Now setting the ECT bit all the time, as it should not cause | |
546 | * any problems protocol-wise even if our peer ignores it. | |
547 | * | |
548 | * Note: The works for IPv6 layer checks this bit too later | |
549 | * in transmission. See IP6_ECN_flow_xmit(). | |
550 | */ | |
b9031d9d | 551 | (*tp->af_specific->ecn_capable)(nskb->sk); |
1da177e4 LT |
552 | |
553 | /* Set up the IP options. */ | |
554 | /* BUG: not implemented | |
555 | * For v4 this all lives somewhere in sk->sk_opt... | |
556 | */ | |
557 | ||
558 | /* Dump that on IP! */ | |
559 | if (asoc && asoc->peer.last_sent_to != tp) { | |
560 | /* Considering the multiple CPU scenario, this is a | |
561 | * "correcter" place for last_sent_to. --xguo | |
562 | */ | |
563 | asoc->peer.last_sent_to = tp; | |
564 | } | |
565 | ||
566 | if (has_data) { | |
567 | struct timer_list *timer; | |
568 | unsigned long timeout; | |
569 | ||
570 | tp->last_time_used = jiffies; | |
571 | ||
572 | /* Restart the AUTOCLOSE timer when sending data. */ | |
573 | if (sctp_state(asoc, ESTABLISHED) && asoc->autoclose) { | |
574 | timer = &asoc->timers[SCTP_EVENT_TIMEOUT_AUTOCLOSE]; | |
575 | timeout = asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE]; | |
576 | ||
577 | if (!mod_timer(timer, jiffies + timeout)) | |
578 | sctp_association_hold(asoc); | |
579 | } | |
580 | } | |
581 | ||
1da177e4 LT |
582 | SCTP_DEBUG_PRINTK("***sctp_transmit_packet*** skb len %d\n", |
583 | nskb->len); | |
584 | ||
52ccb8e9 FF |
585 | if (tp->param_flags & SPP_PMTUD_ENABLE) |
586 | (*tp->af_specific->sctp_xmit)(nskb, tp, packet->ipfragok); | |
587 | else | |
588 | (*tp->af_specific->sctp_xmit)(nskb, tp, 1); | |
1da177e4 LT |
589 | |
590 | out: | |
591 | packet->size = packet->overhead; | |
592 | return err; | |
593 | no_route: | |
594 | kfree_skb(nskb); | |
595 | IP_INC_STATS_BH(IPSTATS_MIB_OUTNOROUTES); | |
596 | ||
597 | /* FIXME: Returning the 'err' will effect all the associations | |
598 | * associated with a socket, although only one of the paths of the | |
599 | * association is unreachable. | |
600 | * The real failure of a transport or association can be passed on | |
601 | * to the user via notifications. So setting this error may not be | |
602 | * required. | |
603 | */ | |
604 | /* err = -EHOSTUNREACH; */ | |
605 | err: | |
606 | /* Control chunks are unreliable so just drop them. DATA chunks | |
607 | * will get resent or dropped later. | |
608 | */ | |
609 | ||
79af02c2 DM |
610 | list_for_each_entry_safe(chunk, tmp, &packet->chunk_list, list) { |
611 | list_del_init(&chunk->list); | |
1da177e4 | 612 | if (!sctp_chunk_is_data(chunk)) |
d808ad9a | 613 | sctp_chunk_free(chunk); |
1da177e4 LT |
614 | } |
615 | goto out; | |
616 | nomem: | |
617 | err = -ENOMEM; | |
618 | goto err; | |
619 | } | |
620 | ||
621 | /******************************************************************** | |
622 | * 2nd Level Abstractions | |
623 | ********************************************************************/ | |
624 | ||
625 | /* This private function handles the specifics of appending DATA chunks. */ | |
626 | static sctp_xmit_t sctp_packet_append_data(struct sctp_packet *packet, | |
627 | struct sctp_chunk *chunk) | |
628 | { | |
629 | sctp_xmit_t retval = SCTP_XMIT_OK; | |
630 | size_t datasize, rwnd, inflight; | |
631 | struct sctp_transport *transport = packet->transport; | |
632 | __u32 max_burst_bytes; | |
633 | struct sctp_association *asoc = transport->asoc; | |
634 | struct sctp_sock *sp = sctp_sk(asoc->base.sk); | |
635 | struct sctp_outq *q = &asoc->outqueue; | |
636 | ||
637 | /* RFC 2960 6.1 Transmission of DATA Chunks | |
638 | * | |
639 | * A) At any given time, the data sender MUST NOT transmit new data to | |
640 | * any destination transport address if its peer's rwnd indicates | |
641 | * that the peer has no buffer space (i.e. rwnd is 0, see Section | |
642 | * 6.2.1). However, regardless of the value of rwnd (including if it | |
643 | * is 0), the data sender can always have one DATA chunk in flight to | |
644 | * the receiver if allowed by cwnd (see rule B below). This rule | |
645 | * allows the sender to probe for a change in rwnd that the sender | |
646 | * missed due to the SACK having been lost in transit from the data | |
647 | * receiver to the data sender. | |
648 | */ | |
649 | ||
650 | rwnd = asoc->peer.rwnd; | |
651 | inflight = asoc->outqueue.outstanding_bytes; | |
652 | ||
653 | datasize = sctp_data_size(chunk); | |
654 | ||
655 | if (datasize > rwnd) { | |
656 | if (inflight > 0) { | |
657 | /* We have (at least) one data chunk in flight, | |
658 | * so we can't fall back to rule 6.1 B). | |
659 | */ | |
660 | retval = SCTP_XMIT_RWND_FULL; | |
661 | goto finish; | |
662 | } | |
663 | } | |
664 | ||
665 | /* sctpimpguide-05 2.14.2 | |
666 | * D) When the time comes for the sender to | |
667 | * transmit new DATA chunks, the protocol parameter Max.Burst MUST | |
668 | * first be applied to limit how many new DATA chunks may be sent. | |
669 | * The limit is applied by adjusting cwnd as follows: | |
670 | * if ((flightsize + Max.Burst * MTU) < cwnd) | |
671 | * cwnd = flightsize + Max.Burst * MTU | |
672 | */ | |
52ccb8e9 | 673 | max_burst_bytes = asoc->max_burst * asoc->pathmtu; |
1da177e4 LT |
674 | if ((transport->flight_size + max_burst_bytes) < transport->cwnd) { |
675 | transport->cwnd = transport->flight_size + max_burst_bytes; | |
676 | SCTP_DEBUG_PRINTK("%s: cwnd limited by max_burst: " | |
677 | "transport: %p, cwnd: %d, " | |
678 | "ssthresh: %d, flight_size: %d, " | |
679 | "pba: %d\n", | |
0dc47877 | 680 | __func__, transport, |
1da177e4 LT |
681 | transport->cwnd, |
682 | transport->ssthresh, | |
683 | transport->flight_size, | |
684 | transport->partial_bytes_acked); | |
685 | } | |
686 | ||
687 | /* RFC 2960 6.1 Transmission of DATA Chunks | |
688 | * | |
689 | * B) At any given time, the sender MUST NOT transmit new data | |
690 | * to a given transport address if it has cwnd or more bytes | |
691 | * of data outstanding to that transport address. | |
692 | */ | |
693 | /* RFC 7.2.4 & the Implementers Guide 2.8. | |
694 | * | |
695 | * 3) ... | |
696 | * When a Fast Retransmit is being performed the sender SHOULD | |
697 | * ignore the value of cwnd and SHOULD NOT delay retransmission. | |
698 | */ | |
27852c26 | 699 | if (chunk->fast_retransmit <= 0) |
1da177e4 LT |
700 | if (transport->flight_size >= transport->cwnd) { |
701 | retval = SCTP_XMIT_RWND_FULL; | |
702 | goto finish; | |
703 | } | |
704 | ||
705 | /* Nagle's algorithm to solve small-packet problem: | |
706 | * Inhibit the sending of new chunks when new outgoing data arrives | |
707 | * if any previously transmitted data on the connection remains | |
708 | * unacknowledged. | |
709 | */ | |
710 | if (!sp->nodelay && sctp_packet_empty(packet) && | |
711 | q->outstanding_bytes && sctp_state(asoc, ESTABLISHED)) { | |
712 | unsigned len = datasize + q->out_qlen; | |
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. | |
717 | */ | |
cd497885 | 718 | if (len < asoc->frag_point) { |
1da177e4 LT |
719 | retval = SCTP_XMIT_NAGLE_DELAY; |
720 | goto finish; | |
721 | } | |
722 | } | |
723 | ||
724 | /* Keep track of how many bytes are in flight over this transport. */ | |
725 | transport->flight_size += datasize; | |
726 | ||
727 | /* Keep track of how many bytes are in flight to the receiver. */ | |
728 | asoc->outqueue.outstanding_bytes += datasize; | |
729 | ||
cd497885 SS |
730 | /* Update our view of the receiver's rwnd. Include sk_buff overhead |
731 | * while updating peer.rwnd so that it reduces the chances of a | |
732 | * receiver running out of receive buffer space even when receive | |
733 | * window is still open. This can happen when a sender is sending | |
734 | * sending small messages. | |
735 | */ | |
736 | datasize += sizeof(struct sk_buff); | |
1da177e4 LT |
737 | if (datasize < rwnd) |
738 | rwnd -= datasize; | |
739 | else | |
740 | rwnd = 0; | |
741 | ||
742 | asoc->peer.rwnd = rwnd; | |
743 | /* Has been accepted for transmission. */ | |
744 | if (!asoc->peer.prsctp_capable) | |
745 | chunk->msg->can_abandon = 0; | |
746 | ||
747 | finish: | |
748 | return retval; | |
749 | } |