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1 | /* SCTP kernel implementation |
2 | * (C) Copyright IBM Corp. 2001, 2004 |
3 | * Copyright (c) 1999-2000 Cisco, Inc. |
4 | * Copyright (c) 1999-2001 Motorola, Inc. |
5 | * |
6 | * This file is part of the SCTP kernel implementation |
7 | * |
8 | * These functions handle output processing. |
9 | * |
10 | * This SCTP implementation is free software; |
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 | * |
16 | * This SCTP implementation is distributed in the hope that it |
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 <linux/slab.h> |
52 | #include <net/inet_ecn.h> |
53 | #include <net/ip.h> |
54 | #include <net/icmp.h> |
55 | #include <net/net_namespace.h> |
56 | |
57 | #include <linux/socket.h> /* for sa_family_t */ |
58 | #include <net/sock.h> |
59 | |
60 | #include <net/sctp/sctp.h> |
61 | #include <net/sctp/sm.h> |
62 | #include <net/sctp/checksum.h> |
63 | |
64 | /* Forward declarations for private helpers. */ |
65 | static sctp_xmit_t sctp_packet_can_append_data(struct sctp_packet *packet, |
66 | struct sctp_chunk *chunk); |
67 | static void sctp_packet_append_data(struct sctp_packet *packet, |
68 | struct sctp_chunk *chunk); |
69 | static sctp_xmit_t sctp_packet_will_fit(struct sctp_packet *packet, |
70 | struct sctp_chunk *chunk, |
71 | u16 chunk_len); |
72 | |
73 | static void sctp_packet_reset(struct sctp_packet *packet) |
74 | { |
75 | packet->size = packet->overhead; |
76 | packet->has_cookie_echo = 0; |
77 | packet->has_sack = 0; |
78 | packet->has_data = 0; |
79 | packet->has_auth = 0; |
80 | packet->ipfragok = 0; |
81 | packet->auth = NULL; |
82 | } |
83 | |
84 | /* Config a packet. |
85 | * This appears to be a followup set of initializations. |
86 | */ |
87 | struct sctp_packet *sctp_packet_config(struct sctp_packet *packet, |
88 | __u32 vtag, int ecn_capable) |
89 | { |
90 | struct sctp_chunk *chunk = NULL; |
91 | |
92 | SCTP_DEBUG_PRINTK("%s: packet:%p vtag:0x%x\n", __func__, |
93 | packet, vtag); |
94 | |
95 | sctp_packet_reset(packet); |
96 | packet->vtag = vtag; |
97 | |
98 | if (ecn_capable && sctp_packet_empty(packet)) { |
99 | chunk = sctp_get_ecne_prepend(packet->transport->asoc); |
100 | |
101 | /* If there a is a prepend chunk stick it on the list before |
102 | * any other chunks get appended. |
103 | */ |
104 | if (chunk) |
105 | sctp_packet_append_chunk(packet, chunk); |
106 | } |
107 | |
108 | return packet; |
109 | } |
110 | |
111 | /* Initialize the packet structure. */ |
112 | struct sctp_packet *sctp_packet_init(struct sctp_packet *packet, |
113 | struct sctp_transport *transport, |
114 | __u16 sport, __u16 dport) |
115 | { |
116 | struct sctp_association *asoc = transport->asoc; |
117 | size_t overhead; |
118 | |
119 | SCTP_DEBUG_PRINTK("%s: packet:%p transport:%p\n", __func__, |
120 | packet, transport); |
121 | |
122 | packet->transport = transport; |
123 | packet->source_port = sport; |
124 | packet->destination_port = dport; |
125 | INIT_LIST_HEAD(&packet->chunk_list); |
126 | if (asoc) { |
127 | struct sctp_sock *sp = sctp_sk(asoc->base.sk); |
128 | overhead = sp->pf->af->net_header_len; |
129 | } else { |
130 | overhead = sizeof(struct ipv6hdr); |
131 | } |
132 | overhead += sizeof(struct sctphdr); |
133 | packet->overhead = overhead; |
134 | sctp_packet_reset(packet); |
135 | packet->vtag = 0; |
136 | packet->malloced = 0; |
137 | return packet; |
138 | } |
139 | |
140 | /* Free a packet. */ |
141 | void sctp_packet_free(struct sctp_packet *packet) |
142 | { |
143 | struct sctp_chunk *chunk, *tmp; |
144 | |
145 | SCTP_DEBUG_PRINTK("%s: packet:%p\n", __func__, packet); |
146 | |
147 | list_for_each_entry_safe(chunk, tmp, &packet->chunk_list, list) { |
148 | list_del_init(&chunk->list); |
149 | sctp_chunk_free(chunk); |
150 | } |
151 | |
152 | if (packet->malloced) |
153 | kfree(packet); |
154 | } |
155 | |
156 | /* This routine tries to append the chunk to the offered packet. If adding |
157 | * the chunk causes the packet to exceed the path MTU and COOKIE_ECHO chunk |
158 | * is not present in the packet, it transmits the input packet. |
159 | * Data can be bundled with a packet containing a COOKIE_ECHO chunk as long |
160 | * as it can fit in the packet, but any more data that does not fit in this |
161 | * packet can be sent only after receiving the COOKIE_ACK. |
162 | */ |
163 | sctp_xmit_t sctp_packet_transmit_chunk(struct sctp_packet *packet, |
164 | struct sctp_chunk *chunk, |
165 | int one_packet) |
166 | { |
167 | sctp_xmit_t retval; |
168 | int error = 0; |
169 | |
170 | SCTP_DEBUG_PRINTK("%s: packet:%p chunk:%p\n", __func__, |
171 | packet, chunk); |
172 | |
173 | switch ((retval = (sctp_packet_append_chunk(packet, chunk)))) { |
174 | case SCTP_XMIT_PMTU_FULL: |
175 | if (!packet->has_cookie_echo) { |
176 | error = sctp_packet_transmit(packet); |
177 | if (error < 0) |
178 | chunk->skb->sk->sk_err = -error; |
179 | |
180 | /* If we have an empty packet, then we can NOT ever |
181 | * return PMTU_FULL. |
182 | */ |
183 | if (!one_packet) |
184 | retval = sctp_packet_append_chunk(packet, |
185 | chunk); |
186 | } |
187 | break; |
188 | |
189 | case SCTP_XMIT_RWND_FULL: |
190 | case SCTP_XMIT_OK: |
191 | case SCTP_XMIT_NAGLE_DELAY: |
192 | break; |
193 | } |
194 | |
195 | return retval; |
196 | } |
197 | |
198 | /* Try to bundle an auth chunk into the packet. */ |
199 | static sctp_xmit_t sctp_packet_bundle_auth(struct sctp_packet *pkt, |
200 | struct sctp_chunk *chunk) |
201 | { |
202 | struct sctp_association *asoc = pkt->transport->asoc; |
203 | struct sctp_chunk *auth; |
204 | sctp_xmit_t retval = SCTP_XMIT_OK; |
205 | |
206 | /* if we don't have an association, we can't do authentication */ |
207 | if (!asoc) |
208 | return retval; |
209 | |
210 | /* See if this is an auth chunk we are bundling or if |
211 | * auth is already bundled. |
212 | */ |
213 | if (chunk->chunk_hdr->type == SCTP_CID_AUTH || pkt->has_auth) |
214 | return retval; |
215 | |
216 | /* if the peer did not request this chunk to be authenticated, |
217 | * don't do it |
218 | */ |
219 | if (!chunk->auth) |
220 | return retval; |
221 | |
222 | auth = sctp_make_auth(asoc); |
223 | if (!auth) |
224 | return retval; |
225 | |
226 | retval = sctp_packet_append_chunk(pkt, auth); |
227 | |
228 | return retval; |
229 | } |
230 | |
231 | /* Try to bundle a SACK with the packet. */ |
232 | static sctp_xmit_t sctp_packet_bundle_sack(struct sctp_packet *pkt, |
233 | struct sctp_chunk *chunk) |
234 | { |
235 | sctp_xmit_t retval = SCTP_XMIT_OK; |
236 | |
237 | /* If sending DATA and haven't aleady bundled a SACK, try to |
238 | * bundle one in to the packet. |
239 | */ |
240 | if (sctp_chunk_is_data(chunk) && !pkt->has_sack && |
241 | !pkt->has_cookie_echo) { |
242 | struct sctp_association *asoc; |
243 | struct timer_list *timer; |
244 | asoc = pkt->transport->asoc; |
245 | timer = &asoc->timers[SCTP_EVENT_TIMEOUT_SACK]; |
246 | |
247 | /* If the SACK timer is running, we have a pending SACK */ |
248 | if (timer_pending(timer)) { |
249 | struct sctp_chunk *sack; |
250 | asoc->a_rwnd = asoc->rwnd; |
251 | sack = sctp_make_sack(asoc); |
252 | if (sack) { |
253 | retval = sctp_packet_append_chunk(pkt, sack); |
254 | asoc->peer.sack_needed = 0; |
255 | if (del_timer(timer)) |
256 | sctp_association_put(asoc); |
257 | } |
258 | } |
259 | } |
260 | return retval; |
261 | } |
262 | |
263 | /* Append a chunk to the offered packet reporting back any inability to do |
264 | * so. |
265 | */ |
266 | sctp_xmit_t sctp_packet_append_chunk(struct sctp_packet *packet, |
267 | struct sctp_chunk *chunk) |
268 | { |
269 | sctp_xmit_t retval = SCTP_XMIT_OK; |
270 | __u16 chunk_len = WORD_ROUND(ntohs(chunk->chunk_hdr->length)); |
271 | |
272 | SCTP_DEBUG_PRINTK("%s: packet:%p chunk:%p\n", __func__, packet, |
273 | chunk); |
274 | |
275 | /* Data chunks are special. Before seeing what else we can |
276 | * bundle into this packet, check to see if we are allowed to |
277 | * send this DATA. |
278 | */ |
279 | if (sctp_chunk_is_data(chunk)) { |
280 | retval = sctp_packet_can_append_data(packet, chunk); |
281 | if (retval != SCTP_XMIT_OK) |
282 | goto finish; |
283 | } |
284 | |
285 | /* Try to bundle AUTH chunk */ |
286 | retval = sctp_packet_bundle_auth(packet, chunk); |
287 | if (retval != SCTP_XMIT_OK) |
288 | goto finish; |
289 | |
290 | /* Try to bundle SACK chunk */ |
291 | retval = sctp_packet_bundle_sack(packet, chunk); |
292 | if (retval != SCTP_XMIT_OK) |
293 | goto finish; |
294 | |
295 | /* Check to see if this chunk will fit into the packet */ |
296 | retval = sctp_packet_will_fit(packet, chunk, chunk_len); |
297 | if (retval != SCTP_XMIT_OK) |
298 | goto finish; |
299 | |
300 | /* We believe that this chunk is OK to add to the packet */ |
301 | switch (chunk->chunk_hdr->type) { |
302 | case SCTP_CID_DATA: |
303 | /* Account for the data being in the packet */ |
304 | sctp_packet_append_data(packet, chunk); |
305 | /* Disallow SACK bundling after DATA. */ |
306 | packet->has_sack = 1; |
307 | /* Disallow AUTH bundling after DATA */ |
308 | packet->has_auth = 1; |
309 | /* Let it be knows that packet has DATA in it */ |
310 | packet->has_data = 1; |
311 | /* timestamp the chunk for rtx purposes */ |
312 | chunk->sent_at = jiffies; |
313 | break; |
314 | case SCTP_CID_COOKIE_ECHO: |
315 | packet->has_cookie_echo = 1; |
316 | break; |
317 | |
318 | case SCTP_CID_SACK: |
319 | packet->has_sack = 1; |
320 | break; |
321 | |
322 | case SCTP_CID_AUTH: |
323 | packet->has_auth = 1; |
324 | packet->auth = chunk; |
325 | break; |
326 | } |
327 | |
328 | /* It is OK to send this chunk. */ |
329 | list_add_tail(&chunk->list, &packet->chunk_list); |
330 | packet->size += chunk_len; |
331 | chunk->transport = packet->transport; |
332 | finish: |
333 | return retval; |
334 | } |
335 | |
336 | /* All packets are sent to the network through this function from |
337 | * sctp_outq_tail(). |
338 | * |
339 | * The return value is a normal kernel error return value. |
340 | */ |
341 | int sctp_packet_transmit(struct sctp_packet *packet) |
342 | { |
343 | struct sctp_transport *tp = packet->transport; |
344 | struct sctp_association *asoc = tp->asoc; |
345 | struct sctphdr *sh; |
346 | struct sk_buff *nskb; |
347 | struct sctp_chunk *chunk, *tmp; |
348 | struct sock *sk; |
349 | int err = 0; |
350 | int padding; /* How much padding do we need? */ |
351 | __u8 has_data = 0; |
352 | struct dst_entry *dst = tp->dst; |
353 | unsigned char *auth = NULL; /* pointer to auth in skb data */ |
354 | __u32 cksum_buf_len = sizeof(struct sctphdr); |
355 | |
356 | SCTP_DEBUG_PRINTK("%s: packet:%p\n", __func__, packet); |
357 | |
358 | /* Do NOT generate a chunkless packet. */ |
359 | if (list_empty(&packet->chunk_list)) |
360 | return err; |
361 | |
362 | /* Set up convenience variables... */ |
363 | chunk = list_entry(packet->chunk_list.next, struct sctp_chunk, list); |
364 | sk = chunk->skb->sk; |
365 | |
366 | /* Allocate the new skb. */ |
367 | nskb = alloc_skb(packet->size + LL_MAX_HEADER, GFP_ATOMIC); |
368 | if (!nskb) |
369 | goto nomem; |
370 | |
371 | /* Make sure the outbound skb has enough header room reserved. */ |
372 | skb_reserve(nskb, packet->overhead + LL_MAX_HEADER); |
373 | |
374 | /* Set the owning socket so that we know where to get the |
375 | * destination IP address. |
376 | */ |
377 | skb_set_owner_w(nskb, sk); |
378 | |
379 | /* The 'obsolete' field of dst is set to 2 when a dst is freed. */ |
380 | if (!dst || (dst->obsolete > 1)) { |
381 | dst_release(dst); |
382 | sctp_transport_route(tp, NULL, sctp_sk(sk)); |
383 | if (asoc && (asoc->param_flags & SPP_PMTUD_ENABLE)) { |
384 | sctp_assoc_sync_pmtu(asoc); |
385 | } |
386 | } |
387 | dst = dst_clone(tp->dst); |
388 | skb_dst_set(nskb, dst); |
389 | if (!dst) |
390 | goto no_route; |
391 | |
392 | /* Build the SCTP header. */ |
393 | sh = (struct sctphdr *)skb_push(nskb, sizeof(struct sctphdr)); |
394 | skb_reset_transport_header(nskb); |
395 | sh->source = htons(packet->source_port); |
396 | sh->dest = htons(packet->destination_port); |
397 | |
398 | /* From 6.8 Adler-32 Checksum Calculation: |
399 | * After the packet is constructed (containing the SCTP common |
400 | * header and one or more control or DATA chunks), the |
401 | * transmitter shall: |
402 | * |
403 | * 1) Fill in the proper Verification Tag in the SCTP common |
404 | * header and initialize the checksum field to 0's. |
405 | */ |
406 | sh->vtag = htonl(packet->vtag); |
407 | sh->checksum = 0; |
408 | |
409 | /** |
410 | * 6.10 Bundling |
411 | * |
412 | * An endpoint bundles chunks by simply including multiple |
413 | * chunks in one outbound SCTP packet. ... |
414 | */ |
415 | |
416 | /** |
417 | * 3.2 Chunk Field Descriptions |
418 | * |
419 | * The total length of a chunk (including Type, Length and |
420 | * Value fields) MUST be a multiple of 4 bytes. If the length |
421 | * of the chunk is not a multiple of 4 bytes, the sender MUST |
422 | * pad the chunk with all zero bytes and this padding is not |
423 | * included in the chunk length field. The sender should |
424 | * never pad with more than 3 bytes. |
425 | * |
426 | * [This whole comment explains WORD_ROUND() below.] |
427 | */ |
428 | SCTP_DEBUG_PRINTK("***sctp_transmit_packet***\n"); |
429 | list_for_each_entry_safe(chunk, tmp, &packet->chunk_list, list) { |
430 | list_del_init(&chunk->list); |
431 | if (sctp_chunk_is_data(chunk)) { |
432 | |
433 | if (!chunk->resent) { |
434 | |
435 | /* 6.3.1 C4) When data is in flight and when allowed |
436 | * by rule C5, a new RTT measurement MUST be made each |
437 | * round trip. Furthermore, new RTT measurements |
438 | * SHOULD be made no more than once per round-trip |
439 | * for a given destination transport address. |
440 | */ |
441 | |
442 | if (!tp->rto_pending) { |
443 | chunk->rtt_in_progress = 1; |
444 | tp->rto_pending = 1; |
445 | } |
446 | } |
447 | |
448 | chunk->resent = 1; |
449 | |
450 | has_data = 1; |
451 | } |
452 | |
453 | padding = WORD_ROUND(chunk->skb->len) - chunk->skb->len; |
454 | if (padding) |
455 | memset(skb_put(chunk->skb, padding), 0, padding); |
456 | |
457 | /* if this is the auth chunk that we are adding, |
458 | * store pointer where it will be added and put |
459 | * the auth into the packet. |
460 | */ |
461 | if (chunk == packet->auth) |
462 | auth = skb_tail_pointer(nskb); |
463 | |
464 | cksum_buf_len += chunk->skb->len; |
465 | memcpy(skb_put(nskb, chunk->skb->len), |
466 | chunk->skb->data, chunk->skb->len); |
467 | |
468 | SCTP_DEBUG_PRINTK("%s %p[%s] %s 0x%x, %s %d, %s %d, %s %d\n", |
469 | "*** Chunk", chunk, |
470 | sctp_cname(SCTP_ST_CHUNK( |
471 | chunk->chunk_hdr->type)), |
472 | chunk->has_tsn ? "TSN" : "No TSN", |
473 | chunk->has_tsn ? |
474 | ntohl(chunk->subh.data_hdr->tsn) : 0, |
475 | "length", ntohs(chunk->chunk_hdr->length), |
476 | "chunk->skb->len", chunk->skb->len, |
477 | "rtt_in_progress", chunk->rtt_in_progress); |
478 | |
479 | /* |
480 | * If this is a control chunk, this is our last |
481 | * reference. Free data chunks after they've been |
482 | * acknowledged or have failed. |
483 | */ |
484 | if (!sctp_chunk_is_data(chunk)) |
485 | sctp_chunk_free(chunk); |
486 | } |
487 | |
488 | /* SCTP-AUTH, Section 6.2 |
489 | * The sender MUST calculate the MAC as described in RFC2104 [2] |
490 | * using the hash function H as described by the MAC Identifier and |
491 | * the shared association key K based on the endpoint pair shared key |
492 | * described by the shared key identifier. The 'data' used for the |
493 | * computation of the AUTH-chunk is given by the AUTH chunk with its |
494 | * HMAC field set to zero (as shown in Figure 6) followed by all |
495 | * chunks that are placed after the AUTH chunk in the SCTP packet. |
496 | */ |
497 | if (auth) |
498 | sctp_auth_calculate_hmac(asoc, nskb, |
499 | (struct sctp_auth_chunk *)auth, |
500 | GFP_ATOMIC); |
501 | |
502 | /* 2) Calculate the Adler-32 checksum of the whole packet, |
503 | * including the SCTP common header and all the |
504 | * chunks. |
505 | * |
506 | * Note: Adler-32 is no longer applicable, as has been replaced |
507 | * by CRC32-C as described in <draft-ietf-tsvwg-sctpcsum-02.txt>. |
508 | */ |
509 | if (!sctp_checksum_disable && |
510 | !(dst->dev->features & (NETIF_F_NO_CSUM | NETIF_F_SCTP_CSUM))) { |
511 | __u32 crc32 = sctp_start_cksum((__u8 *)sh, cksum_buf_len); |
512 | |
513 | /* 3) Put the resultant value into the checksum field in the |
514 | * common header, and leave the rest of the bits unchanged. |
515 | */ |
516 | sh->checksum = sctp_end_cksum(crc32); |
517 | } else { |
518 | if (dst->dev->features & NETIF_F_SCTP_CSUM) { |
519 | /* no need to seed psuedo checksum for SCTP */ |
520 | nskb->ip_summed = CHECKSUM_PARTIAL; |
521 | nskb->csum_start = (skb_transport_header(nskb) - |
522 | nskb->head); |
523 | nskb->csum_offset = offsetof(struct sctphdr, checksum); |
524 | } else { |
525 | nskb->ip_summed = CHECKSUM_UNNECESSARY; |
526 | } |
527 | } |
528 | |
529 | /* IP layer ECN support |
530 | * From RFC 2481 |
531 | * "The ECN-Capable Transport (ECT) bit would be set by the |
532 | * data sender to indicate that the end-points of the |
533 | * transport protocol are ECN-capable." |
534 | * |
535 | * Now setting the ECT bit all the time, as it should not cause |
536 | * any problems protocol-wise even if our peer ignores it. |
537 | * |
538 | * Note: The works for IPv6 layer checks this bit too later |
539 | * in transmission. See IP6_ECN_flow_xmit(). |
540 | */ |
541 | (*tp->af_specific->ecn_capable)(nskb->sk); |
542 | |
543 | /* Set up the IP options. */ |
544 | /* BUG: not implemented |
545 | * For v4 this all lives somewhere in sk->sk_opt... |
546 | */ |
547 | |
548 | /* Dump that on IP! */ |
549 | if (asoc && asoc->peer.last_sent_to != tp) { |
550 | /* Considering the multiple CPU scenario, this is a |
551 | * "correcter" place for last_sent_to. --xguo |
552 | */ |
553 | asoc->peer.last_sent_to = tp; |
554 | } |
555 | |
556 | if (has_data) { |
557 | struct timer_list *timer; |
558 | unsigned long timeout; |
559 | |
560 | /* Restart the AUTOCLOSE timer when sending data. */ |
561 | if (sctp_state(asoc, ESTABLISHED) && asoc->autoclose) { |
562 | timer = &asoc->timers[SCTP_EVENT_TIMEOUT_AUTOCLOSE]; |
563 | timeout = asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE]; |
564 | |
565 | if (!mod_timer(timer, jiffies + timeout)) |
566 | sctp_association_hold(asoc); |
567 | } |
568 | } |
569 | |
570 | SCTP_DEBUG_PRINTK("***sctp_transmit_packet*** skb len %d\n", |
571 | nskb->len); |
572 | |
573 | nskb->local_df = packet->ipfragok; |
574 | (*tp->af_specific->sctp_xmit)(nskb, tp); |
575 | |
576 | out: |
577 | sctp_packet_reset(packet); |
578 | return err; |
579 | no_route: |
580 | kfree_skb(nskb); |
581 | IP_INC_STATS_BH(&init_net, IPSTATS_MIB_OUTNOROUTES); |
582 | |
583 | /* FIXME: Returning the 'err' will effect all the associations |
584 | * associated with a socket, although only one of the paths of the |
585 | * association is unreachable. |
586 | * The real failure of a transport or association can be passed on |
587 | * to the user via notifications. So setting this error may not be |
588 | * required. |
589 | */ |
590 | /* err = -EHOSTUNREACH; */ |
591 | err: |
592 | /* Control chunks are unreliable so just drop them. DATA chunks |
593 | * will get resent or dropped later. |
594 | */ |
595 | |
596 | list_for_each_entry_safe(chunk, tmp, &packet->chunk_list, list) { |
597 | list_del_init(&chunk->list); |
598 | if (!sctp_chunk_is_data(chunk)) |
599 | sctp_chunk_free(chunk); |
600 | } |
601 | goto out; |
602 | nomem: |
603 | err = -ENOMEM; |
604 | goto err; |
605 | } |
606 | |
607 | /******************************************************************** |
608 | * 2nd Level Abstractions |
609 | ********************************************************************/ |
610 | |
611 | /* This private function check to see if a chunk can be added */ |
612 | static sctp_xmit_t sctp_packet_can_append_data(struct sctp_packet *packet, |
613 | struct sctp_chunk *chunk) |
614 | { |
615 | sctp_xmit_t retval = SCTP_XMIT_OK; |
616 | size_t datasize, rwnd, inflight, flight_size; |
617 | struct sctp_transport *transport = packet->transport; |
618 | struct sctp_association *asoc = transport->asoc; |
619 | struct sctp_outq *q = &asoc->outqueue; |
620 | |
621 | /* RFC 2960 6.1 Transmission of DATA Chunks |
622 | * |
623 | * A) At any given time, the data sender MUST NOT transmit new data to |
624 | * any destination transport address if its peer's rwnd indicates |
625 | * that the peer has no buffer space (i.e. rwnd is 0, see Section |
626 | * 6.2.1). However, regardless of the value of rwnd (including if it |
627 | * is 0), the data sender can always have one DATA chunk in flight to |
628 | * the receiver if allowed by cwnd (see rule B below). This rule |
629 | * allows the sender to probe for a change in rwnd that the sender |
630 | * missed due to the SACK having been lost in transit from the data |
631 | * receiver to the data sender. |
632 | */ |
633 | |
634 | rwnd = asoc->peer.rwnd; |
635 | inflight = q->outstanding_bytes; |
636 | flight_size = transport->flight_size; |
637 | |
638 | datasize = sctp_data_size(chunk); |
639 | |
640 | if (datasize > rwnd) { |
641 | if (inflight > 0) { |
642 | /* We have (at least) one data chunk in flight, |
643 | * so we can't fall back to rule 6.1 B). |
644 | */ |
645 | retval = SCTP_XMIT_RWND_FULL; |
646 | goto finish; |
647 | } |
648 | } |
649 | |
650 | /* RFC 2960 6.1 Transmission of DATA Chunks |
651 | * |
652 | * B) At any given time, the sender MUST NOT transmit new data |
653 | * to a given transport address if it has cwnd or more bytes |
654 | * of data outstanding to that transport address. |
655 | */ |
656 | /* RFC 7.2.4 & the Implementers Guide 2.8. |
657 | * |
658 | * 3) ... |
659 | * When a Fast Retransmit is being performed the sender SHOULD |
660 | * ignore the value of cwnd and SHOULD NOT delay retransmission. |
661 | */ |
662 | if (chunk->fast_retransmit != SCTP_NEED_FRTX) |
663 | if (flight_size >= transport->cwnd) { |
664 | retval = SCTP_XMIT_RWND_FULL; |
665 | goto finish; |
666 | } |
667 | |
668 | /* Nagle's algorithm to solve small-packet problem: |
669 | * Inhibit the sending of new chunks when new outgoing data arrives |
670 | * if any previously transmitted data on the connection remains |
671 | * unacknowledged. |
672 | */ |
673 | if (!sctp_sk(asoc->base.sk)->nodelay && sctp_packet_empty(packet) && |
674 | inflight && sctp_state(asoc, ESTABLISHED)) { |
675 | unsigned max = transport->pathmtu - packet->overhead; |
676 | unsigned len = chunk->skb->len + q->out_qlen; |
677 | |
678 | /* Check whether this chunk and all the rest of pending |
679 | * data will fit or delay in hopes of bundling a full |
680 | * sized packet. |
681 | * Don't delay large message writes that may have been |
682 | * fragmeneted into small peices. |
683 | */ |
684 | if ((len < max) && (chunk->msg->msg_size < max)) { |
685 | retval = SCTP_XMIT_NAGLE_DELAY; |
686 | goto finish; |
687 | } |
688 | } |
689 | |
690 | finish: |
691 | return retval; |
692 | } |
693 | |
694 | /* This private function does management things when adding DATA chunk */ |
695 | static void sctp_packet_append_data(struct sctp_packet *packet, |
696 | struct sctp_chunk *chunk) |
697 | { |
698 | struct sctp_transport *transport = packet->transport; |
699 | size_t datasize = sctp_data_size(chunk); |
700 | struct sctp_association *asoc = transport->asoc; |
701 | u32 rwnd = asoc->peer.rwnd; |
702 | |
703 | /* Keep track of how many bytes are in flight over this transport. */ |
704 | transport->flight_size += datasize; |
705 | |
706 | /* Keep track of how many bytes are in flight to the receiver. */ |
707 | asoc->outqueue.outstanding_bytes += datasize; |
708 | |
709 | /* Update our view of the receiver's rwnd. Include sk_buff overhead |
710 | * while updating peer.rwnd so that it reduces the chances of a |
711 | * receiver running out of receive buffer space even when receive |
712 | * window is still open. This can happen when a sender is sending |
713 | * sending small messages. |
714 | */ |
715 | datasize += sizeof(struct sk_buff); |
716 | if (datasize < rwnd) |
717 | rwnd -= datasize; |
718 | else |
719 | rwnd = 0; |
720 | |
721 | asoc->peer.rwnd = rwnd; |
722 | /* Has been accepted for transmission. */ |
723 | if (!asoc->peer.prsctp_capable) |
724 | chunk->msg->can_abandon = 0; |
725 | sctp_chunk_assign_tsn(chunk); |
726 | sctp_chunk_assign_ssn(chunk); |
727 | } |
728 | |
729 | static sctp_xmit_t sctp_packet_will_fit(struct sctp_packet *packet, |
730 | struct sctp_chunk *chunk, |
731 | u16 chunk_len) |
732 | { |
733 | size_t psize; |
734 | size_t pmtu; |
735 | int too_big; |
736 | sctp_xmit_t retval = SCTP_XMIT_OK; |
737 | |
738 | psize = packet->size; |
739 | pmtu = ((packet->transport->asoc) ? |
740 | (packet->transport->asoc->pathmtu) : |
741 | (packet->transport->pathmtu)); |
742 | |
743 | too_big = (psize + chunk_len > pmtu); |
744 | |
745 | /* Decide if we need to fragment or resubmit later. */ |
746 | if (too_big) { |
747 | /* It's OK to fragmet at IP level if any one of the following |
748 | * is true: |
749 | * 1. The packet is empty (meaning this chunk is greater |
750 | * the MTU) |
751 | * 2. The chunk we are adding is a control chunk |
752 | * 3. The packet doesn't have any data in it yet and data |
753 | * requires authentication. |
754 | */ |
755 | if (sctp_packet_empty(packet) || !sctp_chunk_is_data(chunk) || |
756 | (!packet->has_data && chunk->auth)) { |
757 | /* We no longer do re-fragmentation. |
758 | * Just fragment at the IP layer, if we |
759 | * actually hit this condition |
760 | */ |
761 | packet->ipfragok = 1; |
762 | } else { |
763 | retval = SCTP_XMIT_PMTU_FULL; |
764 | } |
765 | } |
766 | |
767 | return retval; |
768 | } |
769 |
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od-2011-09-04
od-2011-09-18
v2.6.34-rc5
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v3.9