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1da177e4 LT |
1 | /* SCTP kernel reference 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 reference Implementation | |
7 | * | |
8 | * These functions handle output processing. | |
9 | * | |
10 | * The SCTP reference 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 | * The SCTP reference 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 <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> | |
63 | ||
64 | /* Forward declarations for private helpers. */ | |
65 | static sctp_xmit_t sctp_packet_append_data(struct sctp_packet *packet, | |
66 | struct sctp_chunk *chunk); | |
67 | ||
68 | /* Config a packet. | |
69 | * This appears to be a followup set of initializations. | |
70 | */ | |
71 | struct sctp_packet *sctp_packet_config(struct sctp_packet *packet, | |
72 | __u32 vtag, int ecn_capable) | |
73 | { | |
74 | struct sctp_chunk *chunk = NULL; | |
75 | ||
76 | SCTP_DEBUG_PRINTK("%s: packet:%p vtag:0x%x\n", __FUNCTION__, | |
77 | packet, vtag); | |
78 | ||
79 | packet->vtag = vtag; | |
80 | packet->has_cookie_echo = 0; | |
81 | packet->has_sack = 0; | |
82 | packet->ipfragok = 0; | |
83 | ||
84 | if (ecn_capable && sctp_packet_empty(packet)) { | |
85 | chunk = sctp_get_ecne_prepend(packet->transport->asoc); | |
86 | ||
87 | /* If there a is a prepend chunk stick it on the list before | |
88 | * any other chunks get appended. | |
89 | */ | |
90 | if (chunk) | |
91 | sctp_packet_append_chunk(packet, chunk); | |
92 | } | |
93 | ||
94 | return packet; | |
95 | } | |
96 | ||
97 | /* Initialize the packet structure. */ | |
98 | struct sctp_packet *sctp_packet_init(struct sctp_packet *packet, | |
99 | struct sctp_transport *transport, | |
100 | __u16 sport, __u16 dport) | |
101 | { | |
102 | struct sctp_association *asoc = transport->asoc; | |
103 | size_t overhead; | |
104 | ||
105 | SCTP_DEBUG_PRINTK("%s: packet:%p transport:%p\n", __FUNCTION__, | |
106 | packet, transport); | |
107 | ||
108 | packet->transport = transport; | |
109 | packet->source_port = sport; | |
110 | packet->destination_port = dport; | |
111 | skb_queue_head_init(&packet->chunks); | |
112 | if (asoc) { | |
113 | struct sctp_sock *sp = sctp_sk(asoc->base.sk); | |
114 | overhead = sp->pf->af->net_header_len; | |
115 | } else { | |
116 | overhead = sizeof(struct ipv6hdr); | |
117 | } | |
118 | overhead += sizeof(struct sctphdr); | |
119 | packet->overhead = overhead; | |
120 | packet->size = overhead; | |
121 | packet->vtag = 0; | |
122 | packet->has_cookie_echo = 0; | |
123 | packet->has_sack = 0; | |
124 | packet->ipfragok = 0; | |
125 | packet->malloced = 0; | |
126 | return packet; | |
127 | } | |
128 | ||
129 | /* Free a packet. */ | |
130 | void sctp_packet_free(struct sctp_packet *packet) | |
131 | { | |
132 | struct sctp_chunk *chunk; | |
133 | ||
134 | SCTP_DEBUG_PRINTK("%s: packet:%p\n", __FUNCTION__, packet); | |
135 | ||
136 | while ((chunk = (struct sctp_chunk *)__skb_dequeue(&packet->chunks)) != NULL) | |
137 | sctp_chunk_free(chunk); | |
138 | ||
139 | if (packet->malloced) | |
140 | kfree(packet); | |
141 | } | |
142 | ||
143 | /* This routine tries to append the chunk to the offered packet. If adding | |
144 | * the chunk causes the packet to exceed the path MTU and COOKIE_ECHO chunk | |
145 | * is not present in the packet, it transmits the input packet. | |
146 | * Data can be bundled with a packet containing a COOKIE_ECHO chunk as long | |
147 | * as it can fit in the packet, but any more data that does not fit in this | |
148 | * packet can be sent only after receiving the COOKIE_ACK. | |
149 | */ | |
150 | sctp_xmit_t sctp_packet_transmit_chunk(struct sctp_packet *packet, | |
151 | struct sctp_chunk *chunk) | |
152 | { | |
153 | sctp_xmit_t retval; | |
154 | int error = 0; | |
155 | ||
156 | SCTP_DEBUG_PRINTK("%s: packet:%p chunk:%p\n", __FUNCTION__, | |
157 | packet, chunk); | |
158 | ||
159 | switch ((retval = (sctp_packet_append_chunk(packet, chunk)))) { | |
160 | case SCTP_XMIT_PMTU_FULL: | |
161 | if (!packet->has_cookie_echo) { | |
162 | error = sctp_packet_transmit(packet); | |
163 | if (error < 0) | |
164 | chunk->skb->sk->sk_err = -error; | |
165 | ||
166 | /* If we have an empty packet, then we can NOT ever | |
167 | * return PMTU_FULL. | |
168 | */ | |
169 | retval = sctp_packet_append_chunk(packet, chunk); | |
170 | } | |
171 | break; | |
172 | ||
173 | case SCTP_XMIT_RWND_FULL: | |
174 | case SCTP_XMIT_OK: | |
175 | case SCTP_XMIT_NAGLE_DELAY: | |
176 | break; | |
177 | }; | |
178 | ||
179 | return retval; | |
180 | } | |
181 | ||
182 | /* Try to bundle a SACK with the packet. */ | |
183 | static sctp_xmit_t sctp_packet_bundle_sack(struct sctp_packet *pkt, | |
184 | struct sctp_chunk *chunk) | |
185 | { | |
186 | sctp_xmit_t retval = SCTP_XMIT_OK; | |
187 | ||
188 | /* If sending DATA and haven't aleady bundled a SACK, try to | |
189 | * bundle one in to the packet. | |
190 | */ | |
191 | if (sctp_chunk_is_data(chunk) && !pkt->has_sack && | |
192 | !pkt->has_cookie_echo) { | |
193 | struct sctp_association *asoc; | |
194 | asoc = pkt->transport->asoc; | |
195 | ||
196 | if (asoc->a_rwnd > asoc->rwnd) { | |
197 | struct sctp_chunk *sack; | |
198 | asoc->a_rwnd = asoc->rwnd; | |
199 | sack = sctp_make_sack(asoc); | |
200 | if (sack) { | |
201 | struct timer_list *timer; | |
202 | retval = sctp_packet_append_chunk(pkt, sack); | |
203 | asoc->peer.sack_needed = 0; | |
204 | timer = &asoc->timers[SCTP_EVENT_TIMEOUT_SACK]; | |
205 | if (timer_pending(timer) && del_timer(timer)) | |
206 | sctp_association_put(asoc); | |
207 | } | |
208 | } | |
209 | } | |
210 | return retval; | |
211 | } | |
212 | ||
213 | /* Append a chunk to the offered packet reporting back any inability to do | |
214 | * so. | |
215 | */ | |
216 | sctp_xmit_t sctp_packet_append_chunk(struct sctp_packet *packet, | |
217 | struct sctp_chunk *chunk) | |
218 | { | |
219 | sctp_xmit_t retval = SCTP_XMIT_OK; | |
220 | __u16 chunk_len = WORD_ROUND(ntohs(chunk->chunk_hdr->length)); | |
221 | size_t psize; | |
222 | size_t pmtu; | |
223 | int too_big; | |
224 | ||
225 | SCTP_DEBUG_PRINTK("%s: packet:%p chunk:%p\n", __FUNCTION__, packet, | |
226 | chunk); | |
227 | ||
228 | retval = sctp_packet_bundle_sack(packet, chunk); | |
229 | psize = packet->size; | |
230 | ||
231 | if (retval != SCTP_XMIT_OK) | |
232 | goto finish; | |
233 | ||
234 | pmtu = ((packet->transport->asoc) ? | |
235 | (packet->transport->asoc->pmtu) : | |
236 | (packet->transport->pmtu)); | |
237 | ||
238 | too_big = (psize + chunk_len > pmtu); | |
239 | ||
240 | /* Decide if we need to fragment or resubmit later. */ | |
241 | if (too_big) { | |
242 | /* Both control chunks and data chunks with TSNs are | |
243 | * non-fragmentable. | |
244 | */ | |
245 | if (sctp_packet_empty(packet) || !sctp_chunk_is_data(chunk)) { | |
246 | /* We no longer do re-fragmentation. | |
247 | * Just fragment at the IP layer, if we | |
248 | * actually hit this condition | |
249 | */ | |
250 | packet->ipfragok = 1; | |
251 | goto append; | |
252 | ||
253 | } else { | |
254 | retval = SCTP_XMIT_PMTU_FULL; | |
255 | goto finish; | |
256 | } | |
257 | } | |
258 | ||
259 | append: | |
260 | /* We believe that this chunk is OK to add to the packet (as | |
261 | * long as we have the cwnd for it). | |
262 | */ | |
263 | ||
264 | /* DATA is a special case since we must examine both rwnd and cwnd | |
265 | * before we send DATA. | |
266 | */ | |
267 | if (sctp_chunk_is_data(chunk)) { | |
268 | retval = sctp_packet_append_data(packet, chunk); | |
269 | /* Disallow SACK bundling after DATA. */ | |
270 | packet->has_sack = 1; | |
271 | if (SCTP_XMIT_OK != retval) | |
272 | goto finish; | |
273 | } else if (SCTP_CID_COOKIE_ECHO == chunk->chunk_hdr->type) | |
274 | packet->has_cookie_echo = 1; | |
275 | else if (SCTP_CID_SACK == chunk->chunk_hdr->type) | |
276 | packet->has_sack = 1; | |
277 | ||
278 | /* It is OK to send this chunk. */ | |
279 | __skb_queue_tail(&packet->chunks, (struct sk_buff *)chunk); | |
280 | packet->size += chunk_len; | |
281 | chunk->transport = packet->transport; | |
282 | finish: | |
283 | return retval; | |
284 | } | |
285 | ||
286 | /* All packets are sent to the network through this function from | |
287 | * sctp_outq_tail(). | |
288 | * | |
289 | * The return value is a normal kernel error return value. | |
290 | */ | |
291 | int sctp_packet_transmit(struct sctp_packet *packet) | |
292 | { | |
293 | struct sctp_transport *tp = packet->transport; | |
294 | struct sctp_association *asoc = tp->asoc; | |
295 | struct sctphdr *sh; | |
296 | __u32 crc32; | |
297 | struct sk_buff *nskb; | |
298 | struct sctp_chunk *chunk; | |
299 | struct sock *sk; | |
300 | int err = 0; | |
301 | int padding; /* How much padding do we need? */ | |
302 | __u8 has_data = 0; | |
303 | struct dst_entry *dst; | |
304 | ||
305 | SCTP_DEBUG_PRINTK("%s: packet:%p\n", __FUNCTION__, packet); | |
306 | ||
307 | /* Do NOT generate a chunkless packet. */ | |
308 | chunk = (struct sctp_chunk *)skb_peek(&packet->chunks); | |
309 | if (unlikely(!chunk)) | |
310 | return err; | |
311 | ||
312 | /* Set up convenience variables... */ | |
313 | sk = chunk->skb->sk; | |
314 | ||
315 | /* Allocate the new skb. */ | |
594ccc14 | 316 | nskb = alloc_skb(packet->size + LL_MAX_HEADER, GFP_ATOMIC); |
1da177e4 LT |
317 | if (!nskb) |
318 | goto nomem; | |
319 | ||
320 | /* Make sure the outbound skb has enough header room reserved. */ | |
594ccc14 | 321 | skb_reserve(nskb, packet->overhead + LL_MAX_HEADER); |
1da177e4 LT |
322 | |
323 | /* Set the owning socket so that we know where to get the | |
324 | * destination IP address. | |
325 | */ | |
326 | skb_set_owner_w(nskb, sk); | |
327 | ||
328 | /* Build the SCTP header. */ | |
329 | sh = (struct sctphdr *)skb_push(nskb, sizeof(struct sctphdr)); | |
330 | sh->source = htons(packet->source_port); | |
331 | sh->dest = htons(packet->destination_port); | |
332 | ||
333 | /* From 6.8 Adler-32 Checksum Calculation: | |
334 | * After the packet is constructed (containing the SCTP common | |
335 | * header and one or more control or DATA chunks), the | |
336 | * transmitter shall: | |
337 | * | |
338 | * 1) Fill in the proper Verification Tag in the SCTP common | |
339 | * header and initialize the checksum field to 0's. | |
340 | */ | |
341 | sh->vtag = htonl(packet->vtag); | |
342 | sh->checksum = 0; | |
343 | ||
344 | /* 2) Calculate the Adler-32 checksum of the whole packet, | |
345 | * including the SCTP common header and all the | |
346 | * chunks. | |
347 | * | |
348 | * Note: Adler-32 is no longer applicable, as has been replaced | |
349 | * by CRC32-C as described in <draft-ietf-tsvwg-sctpcsum-02.txt>. | |
350 | */ | |
351 | crc32 = sctp_start_cksum((__u8 *)sh, sizeof(struct sctphdr)); | |
352 | ||
353 | /** | |
354 | * 6.10 Bundling | |
355 | * | |
356 | * An endpoint bundles chunks by simply including multiple | |
357 | * chunks in one outbound SCTP packet. ... | |
358 | */ | |
359 | ||
360 | /** | |
361 | * 3.2 Chunk Field Descriptions | |
362 | * | |
363 | * The total length of a chunk (including Type, Length and | |
364 | * Value fields) MUST be a multiple of 4 bytes. If the length | |
365 | * of the chunk is not a multiple of 4 bytes, the sender MUST | |
366 | * pad the chunk with all zero bytes and this padding is not | |
367 | * included in the chunk length field. The sender should | |
368 | * never pad with more than 3 bytes. | |
369 | * | |
370 | * [This whole comment explains WORD_ROUND() below.] | |
371 | */ | |
372 | SCTP_DEBUG_PRINTK("***sctp_transmit_packet***\n"); | |
373 | while ((chunk = (struct sctp_chunk *)__skb_dequeue(&packet->chunks)) != NULL) { | |
374 | if (sctp_chunk_is_data(chunk)) { | |
375 | ||
376 | if (!chunk->has_tsn) { | |
377 | sctp_chunk_assign_ssn(chunk); | |
378 | sctp_chunk_assign_tsn(chunk); | |
379 | ||
380 | /* 6.3.1 C4) When data is in flight and when allowed | |
381 | * by rule C5, a new RTT measurement MUST be made each | |
382 | * round trip. Furthermore, new RTT measurements | |
383 | * SHOULD be made no more than once per round-trip | |
384 | * for a given destination transport address. | |
385 | */ | |
386 | ||
387 | if (!tp->rto_pending) { | |
388 | chunk->rtt_in_progress = 1; | |
389 | tp->rto_pending = 1; | |
390 | } | |
391 | } else | |
392 | chunk->resent = 1; | |
393 | ||
394 | chunk->sent_at = jiffies; | |
395 | has_data = 1; | |
396 | } | |
397 | ||
398 | padding = WORD_ROUND(chunk->skb->len) - chunk->skb->len; | |
399 | if (padding) | |
400 | memset(skb_put(chunk->skb, padding), 0, padding); | |
401 | ||
402 | crc32 = sctp_update_copy_cksum(skb_put(nskb, chunk->skb->len), | |
403 | chunk->skb->data, | |
404 | chunk->skb->len, crc32); | |
405 | ||
406 | SCTP_DEBUG_PRINTK("%s %p[%s] %s 0x%x, %s %d, %s %d, %s %d\n", | |
407 | "*** Chunk", chunk, | |
408 | sctp_cname(SCTP_ST_CHUNK( | |
409 | chunk->chunk_hdr->type)), | |
410 | chunk->has_tsn ? "TSN" : "No TSN", | |
411 | chunk->has_tsn ? | |
412 | ntohl(chunk->subh.data_hdr->tsn) : 0, | |
413 | "length", ntohs(chunk->chunk_hdr->length), | |
414 | "chunk->skb->len", chunk->skb->len, | |
415 | "rtt_in_progress", chunk->rtt_in_progress); | |
416 | ||
417 | /* | |
418 | * If this is a control chunk, this is our last | |
419 | * reference. Free data chunks after they've been | |
420 | * acknowledged or have failed. | |
421 | */ | |
422 | if (!sctp_chunk_is_data(chunk)) | |
423 | sctp_chunk_free(chunk); | |
424 | } | |
425 | ||
426 | /* Perform final transformation on checksum. */ | |
427 | crc32 = sctp_end_cksum(crc32); | |
428 | ||
429 | /* 3) Put the resultant value into the checksum field in the | |
430 | * common header, and leave the rest of the bits unchanged. | |
431 | */ | |
432 | sh->checksum = htonl(crc32); | |
433 | ||
434 | /* IP layer ECN support | |
435 | * From RFC 2481 | |
436 | * "The ECN-Capable Transport (ECT) bit would be set by the | |
437 | * data sender to indicate that the end-points of the | |
438 | * transport protocol are ECN-capable." | |
439 | * | |
440 | * Now setting the ECT bit all the time, as it should not cause | |
441 | * any problems protocol-wise even if our peer ignores it. | |
442 | * | |
443 | * Note: The works for IPv6 layer checks this bit too later | |
444 | * in transmission. See IP6_ECN_flow_xmit(). | |
445 | */ | |
446 | INET_ECN_xmit(nskb->sk); | |
447 | ||
448 | /* Set up the IP options. */ | |
449 | /* BUG: not implemented | |
450 | * For v4 this all lives somewhere in sk->sk_opt... | |
451 | */ | |
452 | ||
453 | /* Dump that on IP! */ | |
454 | if (asoc && asoc->peer.last_sent_to != tp) { | |
455 | /* Considering the multiple CPU scenario, this is a | |
456 | * "correcter" place for last_sent_to. --xguo | |
457 | */ | |
458 | asoc->peer.last_sent_to = tp; | |
459 | } | |
460 | ||
461 | if (has_data) { | |
462 | struct timer_list *timer; | |
463 | unsigned long timeout; | |
464 | ||
465 | tp->last_time_used = jiffies; | |
466 | ||
467 | /* Restart the AUTOCLOSE timer when sending data. */ | |
468 | if (sctp_state(asoc, ESTABLISHED) && asoc->autoclose) { | |
469 | timer = &asoc->timers[SCTP_EVENT_TIMEOUT_AUTOCLOSE]; | |
470 | timeout = asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE]; | |
471 | ||
472 | if (!mod_timer(timer, jiffies + timeout)) | |
473 | sctp_association_hold(asoc); | |
474 | } | |
475 | } | |
476 | ||
477 | dst = tp->dst; | |
478 | /* The 'obsolete' field of dst is set to 2 when a dst is freed. */ | |
479 | if (!dst || (dst->obsolete > 1)) { | |
480 | dst_release(dst); | |
481 | sctp_transport_route(tp, NULL, sctp_sk(sk)); | |
482 | sctp_assoc_sync_pmtu(asoc); | |
483 | } | |
484 | ||
485 | nskb->dst = dst_clone(tp->dst); | |
486 | if (!nskb->dst) | |
487 | goto no_route; | |
488 | ||
489 | SCTP_DEBUG_PRINTK("***sctp_transmit_packet*** skb len %d\n", | |
490 | nskb->len); | |
491 | ||
492 | (*tp->af_specific->sctp_xmit)(nskb, tp, packet->ipfragok); | |
493 | ||
494 | out: | |
495 | packet->size = packet->overhead; | |
496 | return err; | |
497 | no_route: | |
498 | kfree_skb(nskb); | |
499 | IP_INC_STATS_BH(IPSTATS_MIB_OUTNOROUTES); | |
500 | ||
501 | /* FIXME: Returning the 'err' will effect all the associations | |
502 | * associated with a socket, although only one of the paths of the | |
503 | * association is unreachable. | |
504 | * The real failure of a transport or association can be passed on | |
505 | * to the user via notifications. So setting this error may not be | |
506 | * required. | |
507 | */ | |
508 | /* err = -EHOSTUNREACH; */ | |
509 | err: | |
510 | /* Control chunks are unreliable so just drop them. DATA chunks | |
511 | * will get resent or dropped later. | |
512 | */ | |
513 | ||
514 | while ((chunk = (struct sctp_chunk *)__skb_dequeue(&packet->chunks)) != NULL) { | |
515 | if (!sctp_chunk_is_data(chunk)) | |
516 | sctp_chunk_free(chunk); | |
517 | } | |
518 | goto out; | |
519 | nomem: | |
520 | err = -ENOMEM; | |
521 | goto err; | |
522 | } | |
523 | ||
524 | /******************************************************************** | |
525 | * 2nd Level Abstractions | |
526 | ********************************************************************/ | |
527 | ||
528 | /* This private function handles the specifics of appending DATA chunks. */ | |
529 | static sctp_xmit_t sctp_packet_append_data(struct sctp_packet *packet, | |
530 | struct sctp_chunk *chunk) | |
531 | { | |
532 | sctp_xmit_t retval = SCTP_XMIT_OK; | |
533 | size_t datasize, rwnd, inflight; | |
534 | struct sctp_transport *transport = packet->transport; | |
535 | __u32 max_burst_bytes; | |
536 | struct sctp_association *asoc = transport->asoc; | |
537 | struct sctp_sock *sp = sctp_sk(asoc->base.sk); | |
538 | struct sctp_outq *q = &asoc->outqueue; | |
539 | ||
540 | /* RFC 2960 6.1 Transmission of DATA Chunks | |
541 | * | |
542 | * A) At any given time, the data sender MUST NOT transmit new data to | |
543 | * any destination transport address if its peer's rwnd indicates | |
544 | * that the peer has no buffer space (i.e. rwnd is 0, see Section | |
545 | * 6.2.1). However, regardless of the value of rwnd (including if it | |
546 | * is 0), the data sender can always have one DATA chunk in flight to | |
547 | * the receiver if allowed by cwnd (see rule B below). This rule | |
548 | * allows the sender to probe for a change in rwnd that the sender | |
549 | * missed due to the SACK having been lost in transit from the data | |
550 | * receiver to the data sender. | |
551 | */ | |
552 | ||
553 | rwnd = asoc->peer.rwnd; | |
554 | inflight = asoc->outqueue.outstanding_bytes; | |
555 | ||
556 | datasize = sctp_data_size(chunk); | |
557 | ||
558 | if (datasize > rwnd) { | |
559 | if (inflight > 0) { | |
560 | /* We have (at least) one data chunk in flight, | |
561 | * so we can't fall back to rule 6.1 B). | |
562 | */ | |
563 | retval = SCTP_XMIT_RWND_FULL; | |
564 | goto finish; | |
565 | } | |
566 | } | |
567 | ||
568 | /* sctpimpguide-05 2.14.2 | |
569 | * D) When the time comes for the sender to | |
570 | * transmit new DATA chunks, the protocol parameter Max.Burst MUST | |
571 | * first be applied to limit how many new DATA chunks may be sent. | |
572 | * The limit is applied by adjusting cwnd as follows: | |
573 | * if ((flightsize + Max.Burst * MTU) < cwnd) | |
574 | * cwnd = flightsize + Max.Burst * MTU | |
575 | */ | |
576 | max_burst_bytes = asoc->max_burst * asoc->pmtu; | |
577 | if ((transport->flight_size + max_burst_bytes) < transport->cwnd) { | |
578 | transport->cwnd = transport->flight_size + max_burst_bytes; | |
579 | SCTP_DEBUG_PRINTK("%s: cwnd limited by max_burst: " | |
580 | "transport: %p, cwnd: %d, " | |
581 | "ssthresh: %d, flight_size: %d, " | |
582 | "pba: %d\n", | |
583 | __FUNCTION__, transport, | |
584 | transport->cwnd, | |
585 | transport->ssthresh, | |
586 | transport->flight_size, | |
587 | transport->partial_bytes_acked); | |
588 | } | |
589 | ||
590 | /* RFC 2960 6.1 Transmission of DATA Chunks | |
591 | * | |
592 | * B) At any given time, the sender MUST NOT transmit new data | |
593 | * to a given transport address if it has cwnd or more bytes | |
594 | * of data outstanding to that transport address. | |
595 | */ | |
596 | /* RFC 7.2.4 & the Implementers Guide 2.8. | |
597 | * | |
598 | * 3) ... | |
599 | * When a Fast Retransmit is being performed the sender SHOULD | |
600 | * ignore the value of cwnd and SHOULD NOT delay retransmission. | |
601 | */ | |
602 | if (!chunk->fast_retransmit) | |
603 | if (transport->flight_size >= transport->cwnd) { | |
604 | retval = SCTP_XMIT_RWND_FULL; | |
605 | goto finish; | |
606 | } | |
607 | ||
608 | /* Nagle's algorithm to solve small-packet problem: | |
609 | * Inhibit the sending of new chunks when new outgoing data arrives | |
610 | * if any previously transmitted data on the connection remains | |
611 | * unacknowledged. | |
612 | */ | |
613 | if (!sp->nodelay && sctp_packet_empty(packet) && | |
614 | q->outstanding_bytes && sctp_state(asoc, ESTABLISHED)) { | |
615 | unsigned len = datasize + q->out_qlen; | |
616 | ||
617 | /* Check whether this chunk and all the rest of pending | |
618 | * data will fit or delay in hopes of bundling a full | |
619 | * sized packet. | |
620 | */ | |
621 | if (len < asoc->pmtu - packet->overhead) { | |
622 | retval = SCTP_XMIT_NAGLE_DELAY; | |
623 | goto finish; | |
624 | } | |
625 | } | |
626 | ||
627 | /* Keep track of how many bytes are in flight over this transport. */ | |
628 | transport->flight_size += datasize; | |
629 | ||
630 | /* Keep track of how many bytes are in flight to the receiver. */ | |
631 | asoc->outqueue.outstanding_bytes += datasize; | |
632 | ||
633 | /* Update our view of the receiver's rwnd. */ | |
634 | if (datasize < rwnd) | |
635 | rwnd -= datasize; | |
636 | else | |
637 | rwnd = 0; | |
638 | ||
639 | asoc->peer.rwnd = rwnd; | |
640 | /* Has been accepted for transmission. */ | |
641 | if (!asoc->peer.prsctp_capable) | |
642 | chunk->msg->can_abandon = 0; | |
643 | ||
644 | finish: | |
645 | return retval; | |
646 | } |