1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21
22 /*
23 * Copyright (c) 2004, 2010, Oracle and/or its affiliates. All rights reserved.
24 */
25
26 #include <sys/types.h>
27 #include <sys/systm.h>
28 #include <sys/stream.h>
29 #include <sys/cmn_err.h>
30 #define _SUN_TPI_VERSION 2
31 #include <sys/tihdr.h>
32 #include <sys/socket.h>
33 #include <sys/stropts.h>
34 #include <sys/strsun.h>
35 #include <sys/strsubr.h>
36 #include <sys/socketvar.h>
37 #include <inet/common.h>
38 #include <inet/mi.h>
39 #include <inet/ip.h>
40 #include <inet/ip_ire.h>
41 #include <inet/ip6.h>
42 #include <inet/sctp_ip.h>
43 #include <inet/ipclassifier.h>
44
45 /*
46 * PR-SCTP comments.
47 *
48 * A message can expire before it gets to the transmit list (i.e. it is still
49 * in the unsent list - unchunked), after it gets to the transmit list, but
50 * before transmission has actually started, or after transmission has begun.
51 * Accordingly, we check for the status of a message in sctp_chunkify() when
52 * the message is being transferred from the unsent list to the transmit list;
53 * in sctp_get_msg_to_send(), when we get the next chunk from the transmit
54 * list and in sctp_rexmit() when we get the next chunk to be (re)transmitted.
55 * When we nuke a message in sctp_chunkify(), all we need to do is take it
56 * out of the unsent list and update sctp_unsent; when a message is deemed
57 * timed-out in sctp_get_msg_to_send() we can just take it out of the transmit
58 * list, update sctp_unsent IFF transmission for the message has not yet begun
59 * (i.e. !SCTP_CHUNK_ISSENT(meta->b_cont)). However, if transmission for the
60 * message has started, then we cannot just take it out of the list, we need
61 * to send Forward TSN chunk to the peer so that the peer can clear its
62 * fragment list for this message. However, we cannot just send the Forward
63 * TSN in sctp_get_msg_to_send() because there might be unacked chunks for
64 * messages preceeding this abandoned message. So, we send a Forward TSN
65 * IFF all messages prior to this abandoned message has been SACKd, if not
66 * we defer sending the Forward TSN to sctp_cumack(), which will check for
67 * this condition and send the Forward TSN via sctp_check_abandoned_msg(). In
68 * sctp_rexmit() when we check for retransmissions, we need to determine if
69 * the advanced peer ack point can be moved ahead, and if so, send a Forward
70 * TSN to the peer instead of retransmitting the chunk. Note that when
71 * we send a Forward TSN for a message, there may be yet unsent chunks for
72 * this message; we need to mark all such chunks as abandoned, so that
73 * sctp_cumack() can take the message out of the transmit list, additionally
74 * sctp_unsent need to be adjusted. Whenever sctp_unsent is updated (i.e.
75 * decremented when a message/chunk is deemed abandoned), sockfs needs to
76 * be notified so that it can adjust its idea of the queued message.
77 */
78
79 #include "sctp_impl.h"
80
81 static struct kmem_cache *sctp_kmem_ftsn_set_cache;
82 static mblk_t *sctp_chunkify(sctp_t *, int, int, int);
83
84 #ifdef DEBUG
85 static boolean_t sctp_verify_chain(mblk_t *, mblk_t *);
86 #endif
87
88 /*
89 * Called to allocate a header mblk when sending data to SCTP.
90 * Data will follow in b_cont of this mblk.
91 */
92 mblk_t *
93 sctp_alloc_hdr(const char *name, int nlen, const char *control, int clen,
94 int flags)
95 {
96 mblk_t *mp;
97 struct T_unitdata_req *tudr;
98 size_t size;
99 int error;
100
101 size = sizeof (*tudr) + _TPI_ALIGN_TOPT(nlen) + clen;
102 size = MAX(size, sizeof (sctp_msg_hdr_t));
103 if (flags & SCTP_CAN_BLOCK) {
104 mp = allocb_wait(size, BPRI_MED, 0, &error);
105 } else {
106 mp = allocb(size, BPRI_MED);
107 }
108 if (mp) {
109 tudr = (struct T_unitdata_req *)mp->b_rptr;
110 tudr->PRIM_type = T_UNITDATA_REQ;
111 tudr->DEST_length = nlen;
112 tudr->DEST_offset = sizeof (*tudr);
113 tudr->OPT_length = clen;
114 tudr->OPT_offset = (t_scalar_t)(sizeof (*tudr) +
115 _TPI_ALIGN_TOPT(nlen));
116 if (nlen > 0)
117 bcopy(name, tudr + 1, nlen);
118 if (clen > 0)
119 bcopy(control, (char *)tudr + tudr->OPT_offset, clen);
120 mp->b_wptr += (tudr ->OPT_offset + clen);
121 mp->b_datap->db_type = M_PROTO;
122 }
123 return (mp);
124 }
125
126 /*ARGSUSED2*/
127 int
128 sctp_sendmsg(sctp_t *sctp, mblk_t *mp, int flags)
129 {
130 sctp_faddr_t *fp = NULL;
131 struct T_unitdata_req *tudr;
132 int error = 0;
133 mblk_t *mproto = mp;
134 in6_addr_t *addr;
135 in6_addr_t tmpaddr;
136 uint16_t sid = sctp->sctp_def_stream;
137 uint32_t ppid = sctp->sctp_def_ppid;
138 uint32_t context = sctp->sctp_def_context;
139 uint16_t msg_flags = sctp->sctp_def_flags;
140 sctp_msg_hdr_t *sctp_msg_hdr;
141 uint32_t msg_len = 0;
142 uint32_t timetolive = sctp->sctp_def_timetolive;
143 conn_t *connp = sctp->sctp_connp;
144
145 ASSERT(DB_TYPE(mproto) == M_PROTO);
146
147 mp = mp->b_cont;
148 ASSERT(mp == NULL || DB_TYPE(mp) == M_DATA);
149
150 tudr = (struct T_unitdata_req *)mproto->b_rptr;
151 ASSERT(tudr->PRIM_type == T_UNITDATA_REQ);
152
153 /* Get destination address, if specified */
154 if (tudr->DEST_length > 0) {
155 sin_t *sin;
156 sin6_t *sin6;
157
158 sin = (struct sockaddr_in *)
159 (mproto->b_rptr + tudr->DEST_offset);
160 switch (sin->sin_family) {
161 case AF_INET:
162 if (tudr->DEST_length < sizeof (*sin)) {
163 return (EINVAL);
164 }
165 IN6_IPADDR_TO_V4MAPPED(sin->sin_addr.s_addr, &tmpaddr);
166 addr = &tmpaddr;
167 break;
168 case AF_INET6:
169 if (tudr->DEST_length < sizeof (*sin6)) {
170 return (EINVAL);
171 }
172 sin6 = (struct sockaddr_in6 *)
173 (mproto->b_rptr + tudr->DEST_offset);
174 addr = &sin6->sin6_addr;
175 break;
176 default:
177 return (EAFNOSUPPORT);
178 }
179 fp = sctp_lookup_faddr(sctp, addr);
180 if (fp == NULL) {
181 return (EINVAL);
182 }
183 }
184 /* Ancillary Data? */
185 if (tudr->OPT_length > 0) {
186 struct cmsghdr *cmsg;
187 char *cend;
188 struct sctp_sndrcvinfo *sndrcv;
189
190 cmsg = (struct cmsghdr *)(mproto->b_rptr + tudr->OPT_offset);
191 cend = ((char *)cmsg + tudr->OPT_length);
192 ASSERT(cend <= (char *)mproto->b_wptr);
193
194 for (;;) {
195 if ((char *)(cmsg + 1) > cend ||
196 ((char *)cmsg + cmsg->cmsg_len) > cend) {
197 break;
198 }
199 if ((cmsg->cmsg_level == IPPROTO_SCTP) &&
200 (cmsg->cmsg_type == SCTP_SNDRCV)) {
201 if (cmsg->cmsg_len <
202 (sizeof (*sndrcv) + sizeof (*cmsg))) {
203 return (EINVAL);
204 }
205 sndrcv = (struct sctp_sndrcvinfo *)(cmsg + 1);
206 sid = sndrcv->sinfo_stream;
207 msg_flags = sndrcv->sinfo_flags;
208 ppid = sndrcv->sinfo_ppid;
209 context = sndrcv->sinfo_context;
210 timetolive = sndrcv->sinfo_timetolive;
211 break;
212 }
213 if (cmsg->cmsg_len > 0)
214 cmsg = CMSG_NEXT(cmsg);
215 else
216 break;
217 }
218 }
219 if (msg_flags & MSG_ABORT) {
220 if (mp && mp->b_cont) {
221 mblk_t *pump = msgpullup(mp, -1);
222 if (!pump) {
223 return (ENOMEM);
224 }
225 freemsg(mp);
226 mp = pump;
227 mproto->b_cont = mp;
228 }
229 RUN_SCTP(sctp);
230 sctp_user_abort(sctp, mp);
231 freemsg(mproto);
232 goto done2;
233 }
234 if (mp == NULL)
235 goto done;
236
237 RUN_SCTP(sctp);
238
239 /* Reject any new data requests if we are shutting down */
240 if (sctp->sctp_state > SCTPS_ESTABLISHED ||
241 (sctp->sctp_connp->conn_state_flags & CONN_CLOSING)) {
242 error = EPIPE;
243 goto unlock_done;
244 }
245
246 /* Re-use the mproto to store relevant info. */
247 ASSERT(MBLKSIZE(mproto) >= sizeof (*sctp_msg_hdr));
248
249 mproto->b_rptr = mproto->b_datap->db_base;
250 mproto->b_wptr = mproto->b_rptr + sizeof (*sctp_msg_hdr);
251
252 sctp_msg_hdr = (sctp_msg_hdr_t *)mproto->b_rptr;
253 bzero(sctp_msg_hdr, sizeof (*sctp_msg_hdr));
254 sctp_msg_hdr->smh_context = context;
255 sctp_msg_hdr->smh_sid = sid;
256 sctp_msg_hdr->smh_ppid = ppid;
257 sctp_msg_hdr->smh_flags = msg_flags;
258 sctp_msg_hdr->smh_ttl = MSEC_TO_TICK(timetolive);
259 sctp_msg_hdr->smh_tob = ddi_get_lbolt64();
260 for (; mp != NULL; mp = mp->b_cont)
261 msg_len += MBLKL(mp);
262 sctp_msg_hdr->smh_msglen = msg_len;
263
264 /* User requested specific destination */
265 SCTP_SET_CHUNK_DEST(mproto, fp);
266
267 if (sctp->sctp_state >= SCTPS_COOKIE_ECHOED &&
268 sid >= sctp->sctp_num_ostr) {
269 /* Send sendfail event */
270 sctp_sendfail_event(sctp, dupmsg(mproto), SCTP_ERR_BAD_SID,
271 B_FALSE);
272 error = EINVAL;
273 goto unlock_done;
274 }
275
276 /* no data */
277 if (msg_len == 0) {
278 sctp_sendfail_event(sctp, dupmsg(mproto),
279 SCTP_ERR_NO_USR_DATA, B_FALSE);
280 error = EINVAL;
281 goto unlock_done;
282 }
283
284 /* Add it to the unsent list */
285 if (sctp->sctp_xmit_unsent == NULL) {
286 sctp->sctp_xmit_unsent = sctp->sctp_xmit_unsent_tail = mproto;
287 } else {
288 sctp->sctp_xmit_unsent_tail->b_next = mproto;
289 sctp->sctp_xmit_unsent_tail = mproto;
290 }
291 sctp->sctp_unsent += msg_len;
292 BUMP_LOCAL(sctp->sctp_msgcount);
293 /*
294 * Notify sockfs if the tx queue is full.
295 */
296 if (SCTP_TXQ_LEN(sctp) >= connp->conn_sndbuf) {
297 sctp->sctp_txq_full = 1;
298 sctp->sctp_ulp_txq_full(sctp->sctp_ulpd, B_TRUE);
299 }
300 if (sctp->sctp_state == SCTPS_ESTABLISHED)
301 sctp_output(sctp, UINT_MAX);
302 done2:
303 WAKE_SCTP(sctp);
304 return (0);
305 unlock_done:
306 WAKE_SCTP(sctp);
307 done:
308 return (error);
309 }
310
311 /*
312 * While there are messages on sctp_xmit_unsent, detach each one. For each:
313 * allocate space for the chunk header, fill in the data chunk, and fill in
314 * the chunk header. Then append it to sctp_xmit_tail.
315 * Return after appending as many bytes as required (bytes_to_send).
316 * We also return if we've appended one or more chunks, and find a subsequent
317 * unsent message is too big to fit in the segment.
318 */
319 mblk_t *
320 sctp_chunkify(sctp_t *sctp, int mss, int firstseg_len, int bytes_to_send)
321 {
322 mblk_t *mp;
323 mblk_t *chunk_mp;
324 mblk_t *chunk_head;
325 mblk_t *chunk_hdr;
326 mblk_t *chunk_tail = NULL;
327 int count;
328 int chunksize;
329 sctp_data_hdr_t *sdc;
330 mblk_t *mdblk = sctp->sctp_xmit_unsent;
331 sctp_faddr_t *fp;
332 sctp_faddr_t *fp1;
333 size_t xtralen;
334 sctp_msg_hdr_t *msg_hdr;
335 sctp_stack_t *sctps = sctp->sctp_sctps;
336 sctp_msg_hdr_t *next_msg_hdr;
337 size_t nextlen;
338 int remaining_len = mss - firstseg_len;
339
340 ASSERT(remaining_len >= 0);
341
342 fp = SCTP_CHUNK_DEST(mdblk);
343 if (fp == NULL)
344 fp = sctp->sctp_current;
345 if (fp->sf_isv4)
346 xtralen = sctp->sctp_hdr_len + sctps->sctps_wroff_xtra +
347 sizeof (*sdc);
348 else
349 xtralen = sctp->sctp_hdr6_len + sctps->sctps_wroff_xtra +
350 sizeof (*sdc);
351 count = chunksize = remaining_len - sizeof (*sdc);
352 nextmsg:
353 next_msg_hdr = (sctp_msg_hdr_t *)sctp->sctp_xmit_unsent->b_rptr;
354 nextlen = next_msg_hdr->smh_msglen;
355 /*
356 * Will the entire next message fit in the current packet ?
357 * if not, leave it on the unsent list.
358 */
359 if ((firstseg_len != 0) && (nextlen > remaining_len))
360 return (NULL);
361
362 chunk_mp = mdblk->b_cont;
363
364 /*
365 * If this partially chunked, we ignore the next one for now and
366 * use the one already present. For the unchunked bits, we use the
367 * length of the last chunk.
368 */
369 if (SCTP_IS_MSG_CHUNKED(mdblk)) {
370 int chunk_len;
371
372 ASSERT(chunk_mp->b_next != NULL);
373 mdblk->b_cont = chunk_mp->b_next;
374 chunk_mp->b_next = NULL;
375 SCTP_MSG_CLEAR_CHUNKED(mdblk);
376 mp = mdblk->b_cont;
377 while (mp->b_next != NULL)
378 mp = mp->b_next;
379 chunk_len = ntohs(((sctp_data_hdr_t *)mp->b_rptr)->sdh_len);
380 if (fp->sf_pmss - chunk_len > sizeof (*sdc))
381 count = chunksize = fp->sf_pmss - chunk_len;
382 else
383 count = chunksize = fp->sf_pmss;
384 count = chunksize = count - sizeof (*sdc);
385 } else {
386 msg_hdr = (sctp_msg_hdr_t *)mdblk->b_rptr;
387 if (SCTP_MSG_TO_BE_ABANDONED(mdblk, msg_hdr, sctp)) {
388 sctp->sctp_xmit_unsent = mdblk->b_next;
389 if (sctp->sctp_xmit_unsent == NULL)
390 sctp->sctp_xmit_unsent_tail = NULL;
391 ASSERT(sctp->sctp_unsent >= msg_hdr->smh_msglen);
392 sctp->sctp_unsent -= msg_hdr->smh_msglen;
393 mdblk->b_next = NULL;
394 BUMP_LOCAL(sctp->sctp_prsctpdrop);
395 /*
396 * Update ULP the amount of queued data, which is
397 * sent-unack'ed + unsent.
398 */
399 if (!SCTP_IS_DETACHED(sctp))
400 SCTP_TXQ_UPDATE(sctp);
401 sctp_sendfail_event(sctp, mdblk, 0, B_FALSE);
402 goto try_next;
403 }
404 mdblk->b_cont = NULL;
405 }
406 msg_hdr = (sctp_msg_hdr_t *)mdblk->b_rptr;
407 nextchunk:
408 chunk_head = chunk_mp;
409 chunk_tail = NULL;
410
411 /* Skip as many mblk's as we need */
412 while (chunk_mp != NULL && ((count - MBLKL(chunk_mp)) >= 0)) {
413 count -= MBLKL(chunk_mp);
414 chunk_tail = chunk_mp;
415 chunk_mp = chunk_mp->b_cont;
416 }
417 /* Split the chain, if needed */
418 if (chunk_mp != NULL) {
419 if (count > 0) {
420 mblk_t *split_mp = dupb(chunk_mp);
421
422 if (split_mp == NULL) {
423 if (mdblk->b_cont == NULL) {
424 mdblk->b_cont = chunk_head;
425 } else {
426 SCTP_MSG_SET_CHUNKED(mdblk);
427 ASSERT(chunk_head->b_next == NULL);
428 chunk_head->b_next = mdblk->b_cont;
429 mdblk->b_cont = chunk_head;
430 }
431 return (sctp->sctp_xmit_tail);
432 }
433 if (chunk_tail != NULL) {
434 chunk_tail->b_cont = split_mp;
435 chunk_tail = chunk_tail->b_cont;
436 } else {
437 chunk_head = chunk_tail = split_mp;
438 }
439 chunk_tail->b_wptr = chunk_tail->b_rptr + count;
440 chunk_mp->b_rptr = chunk_tail->b_wptr;
441 count = 0;
442 } else if (chunk_tail == NULL) {
443 goto next;
444 } else {
445 chunk_tail->b_cont = NULL;
446 }
447 }
448 /* Alloc chunk hdr, if needed */
449 if (DB_REF(chunk_head) > 1 ||
450 ((intptr_t)chunk_head->b_rptr) & (SCTP_ALIGN - 1) ||
451 MBLKHEAD(chunk_head) < sizeof (*sdc)) {
452 if ((chunk_hdr = allocb(xtralen, BPRI_MED)) == NULL) {
453 if (mdblk->b_cont == NULL) {
454 if (chunk_mp != NULL)
455 linkb(chunk_head, chunk_mp);
456 mdblk->b_cont = chunk_head;
457 } else {
458 SCTP_MSG_SET_CHUNKED(mdblk);
459 if (chunk_mp != NULL)
460 linkb(chunk_head, chunk_mp);
461 ASSERT(chunk_head->b_next == NULL);
462 chunk_head->b_next = mdblk->b_cont;
463 mdblk->b_cont = chunk_head;
464 }
465 return (sctp->sctp_xmit_tail);
466 }
467 chunk_hdr->b_rptr += xtralen - sizeof (*sdc);
468 chunk_hdr->b_wptr = chunk_hdr->b_rptr + sizeof (*sdc);
469 chunk_hdr->b_cont = chunk_head;
470 } else {
471 chunk_hdr = chunk_head;
472 chunk_hdr->b_rptr -= sizeof (*sdc);
473 }
474 ASSERT(chunk_hdr->b_datap->db_ref == 1);
475 sdc = (sctp_data_hdr_t *)chunk_hdr->b_rptr;
476 sdc->sdh_id = CHUNK_DATA;
477 sdc->sdh_flags = 0;
478 sdc->sdh_len = htons(sizeof (*sdc) + chunksize - count);
479 ASSERT(sdc->sdh_len);
480 sdc->sdh_sid = htons(msg_hdr->smh_sid);
481 /*
482 * We defer assigning the SSN just before sending the chunk, else
483 * if we drop the chunk in sctp_get_msg_to_send(), we would need
484 * to send a Forward TSN to let the peer know. Some more comments
485 * about this in sctp_impl.h for SCTP_CHUNK_SENT.
486 */
487 sdc->sdh_payload_id = msg_hdr->smh_ppid;
488
489 if (mdblk->b_cont == NULL) {
490 mdblk->b_cont = chunk_hdr;
491 SCTP_DATA_SET_BBIT(sdc);
492 } else {
493 mp = mdblk->b_cont;
494 while (mp->b_next != NULL)
495 mp = mp->b_next;
496 mp->b_next = chunk_hdr;
497 }
498
499 bytes_to_send -= (chunksize - count);
500 if (chunk_mp != NULL) {
501 next:
502 count = chunksize = fp->sf_pmss - sizeof (*sdc);
503 goto nextchunk;
504 }
505 SCTP_DATA_SET_EBIT(sdc);
506 sctp->sctp_xmit_unsent = mdblk->b_next;
507 if (mdblk->b_next == NULL) {
508 sctp->sctp_xmit_unsent_tail = NULL;
509 }
510 mdblk->b_next = NULL;
511
512 if (sctp->sctp_xmit_tail == NULL) {
513 sctp->sctp_xmit_head = sctp->sctp_xmit_tail = mdblk;
514 } else {
515 mp = sctp->sctp_xmit_tail;
516 while (mp->b_next != NULL)
517 mp = mp->b_next;
518 mp->b_next = mdblk;
519 mdblk->b_prev = mp;
520 }
521 try_next:
522 if (bytes_to_send > 0 && sctp->sctp_xmit_unsent != NULL) {
523 mdblk = sctp->sctp_xmit_unsent;
524 fp1 = SCTP_CHUNK_DEST(mdblk);
525 if (fp1 == NULL)
526 fp1 = sctp->sctp_current;
527 if (fp == fp1) {
528 size_t len = MBLKL(mdblk->b_cont);
529 if ((count > 0) &&
530 ((len > fp->sf_pmss - sizeof (*sdc)) ||
531 (len <= count))) {
532 count -= sizeof (*sdc);
533 count = chunksize = count - (count & 0x3);
534 } else {
535 count = chunksize = fp->sf_pmss -
536 sizeof (*sdc);
537 }
538 } else {
539 if (fp1->sf_isv4)
540 xtralen = sctp->sctp_hdr_len;
541 else
542 xtralen = sctp->sctp_hdr6_len;
543 xtralen += sctps->sctps_wroff_xtra + sizeof (*sdc);
544 count = chunksize = fp1->sf_pmss - sizeof (*sdc);
545 fp = fp1;
546 }
547 goto nextmsg;
548 }
549 return (sctp->sctp_xmit_tail);
550 }
551
552 void
553 sctp_free_msg(mblk_t *ump)
554 {
555 mblk_t *mp, *nmp;
556
557 for (mp = ump->b_cont; mp; mp = nmp) {
558 nmp = mp->b_next;
559 mp->b_next = mp->b_prev = NULL;
560 freemsg(mp);
561 }
562 ASSERT(!ump->b_prev);
563 ump->b_next = NULL;
564 freeb(ump);
565 }
566
567 mblk_t *
568 sctp_add_proto_hdr(sctp_t *sctp, sctp_faddr_t *fp, mblk_t *mp, int sacklen,
569 int *error)
570 {
571 int hdrlen;
572 uchar_t *hdr;
573 int isv4 = fp->sf_isv4;
574 sctp_stack_t *sctps = sctp->sctp_sctps;
575
576 if (error != NULL)
577 *error = 0;
578
579 if (isv4) {
580 hdrlen = sctp->sctp_hdr_len;
581 hdr = sctp->sctp_iphc;
582 } else {
583 hdrlen = sctp->sctp_hdr6_len;
584 hdr = sctp->sctp_iphc6;
585 }
586 /*
587 * A reject|blackhole could mean that the address is 'down'. Similarly,
588 * it is possible that the address went down, we tried to send an
589 * heartbeat and ended up setting fp->sf_saddr as unspec because we
590 * didn't have any usable source address. In either case
591 * sctp_get_dest() will try find an IRE, if available, and set
592 * the source address, if needed. If we still don't have any
593 * usable source address, fp->sf_state will be SCTP_FADDRS_UNREACH and
594 * we return EHOSTUNREACH.
595 */
596 ASSERT(fp->sf_ixa->ixa_ire != NULL);
597 if ((fp->sf_ixa->ixa_ire->ire_flags & (RTF_REJECT|RTF_BLACKHOLE)) ||
598 SCTP_IS_ADDR_UNSPEC(fp->sf_isv4, fp->sf_saddr)) {
599 sctp_get_dest(sctp, fp);
600 if (fp->sf_state == SCTP_FADDRS_UNREACH) {
601 if (error != NULL)
602 *error = EHOSTUNREACH;
603 return (NULL);
604 }
605 }
606 /* Copy in IP header. */
607 if ((mp->b_rptr - mp->b_datap->db_base) <
608 (sctps->sctps_wroff_xtra + hdrlen + sacklen) || DB_REF(mp) > 2) {
609 mblk_t *nmp;
610
611 /*
612 * This can happen if IP headers are adjusted after
613 * data was moved into chunks, or during retransmission,
614 * or things like snoop is running.
615 */
616 nmp = allocb(sctps->sctps_wroff_xtra + hdrlen + sacklen,
617 BPRI_MED);
618 if (nmp == NULL) {
619 if (error != NULL)
620 *error = ENOMEM;
621 return (NULL);
622 }
623 nmp->b_rptr += sctps->sctps_wroff_xtra;
624 nmp->b_wptr = nmp->b_rptr + hdrlen + sacklen;
625 nmp->b_cont = mp;
626 mp = nmp;
627 } else {
628 mp->b_rptr -= (hdrlen + sacklen);
629 }
630 bcopy(hdr, mp->b_rptr, hdrlen);
631 if (sacklen) {
632 sctp_fill_sack(sctp, mp->b_rptr + hdrlen, sacklen);
633 }
634 if (fp != sctp->sctp_current) {
635 /* change addresses in header */
636 if (isv4) {
637 ipha_t *iph = (ipha_t *)mp->b_rptr;
638
639 IN6_V4MAPPED_TO_IPADDR(&fp->sf_faddr, iph->ipha_dst);
640 if (!IN6_IS_ADDR_V4MAPPED_ANY(&fp->sf_saddr)) {
641 IN6_V4MAPPED_TO_IPADDR(&fp->sf_saddr,
642 iph->ipha_src);
643 } else if (sctp->sctp_bound_to_all) {
644 iph->ipha_src = INADDR_ANY;
645 }
646 } else {
647 ip6_t *ip6h = (ip6_t *)mp->b_rptr;
648
649 ip6h->ip6_dst = fp->sf_faddr;
650 if (!IN6_IS_ADDR_UNSPECIFIED(&fp->sf_saddr)) {
651 ip6h->ip6_src = fp->sf_saddr;
652 } else if (sctp->sctp_bound_to_all) {
653 ip6h->ip6_src = ipv6_all_zeros;
654 }
655 }
656 }
657 return (mp);
658 }
659
660 /*
661 * SCTP requires every chunk to be padded so that the total length
662 * is a multiple of SCTP_ALIGN. This function returns a mblk with
663 * the specified pad length.
664 */
665 static mblk_t *
666 sctp_get_padding(sctp_t *sctp, int pad)
667 {
668 mblk_t *fill;
669
670 ASSERT(pad < SCTP_ALIGN);
671 ASSERT(sctp->sctp_pad_mp != NULL);
672 if ((fill = dupb(sctp->sctp_pad_mp)) != NULL) {
673 fill->b_wptr += pad;
674 return (fill);
675 }
676
677 /*
678 * The memory saving path of reusing the sctp_pad_mp
679 * fails may be because it has been dupb() too
680 * many times (DBLK_REFMAX). Use the memory consuming
681 * path of allocating the pad mblk.
682 */
683 if ((fill = allocb(SCTP_ALIGN, BPRI_MED)) != NULL) {
684 /* Zero it out. SCTP_ALIGN is sizeof (int32_t) */
685 *(int32_t *)fill->b_rptr = 0;
686 fill->b_wptr += pad;
687 }
688 return (fill);
689 }
690
691 static mblk_t *
692 sctp_find_fast_rexmit_mblks(sctp_t *sctp, int *total, sctp_faddr_t **fp)
693 {
694 mblk_t *meta;
695 mblk_t *start_mp = NULL;
696 mblk_t *end_mp = NULL;
697 mblk_t *mp, *nmp;
698 mblk_t *fill;
699 sctp_data_hdr_t *sdh;
700 int msglen;
701 int extra;
702 sctp_msg_hdr_t *msg_hdr;
703 sctp_faddr_t *old_fp = NULL;
704 sctp_faddr_t *chunk_fp;
705 sctp_stack_t *sctps = sctp->sctp_sctps;
706
707 for (meta = sctp->sctp_xmit_head; meta != NULL; meta = meta->b_next) {
708 msg_hdr = (sctp_msg_hdr_t *)meta->b_rptr;
709 if (SCTP_IS_MSG_ABANDONED(meta) ||
710 SCTP_MSG_TO_BE_ABANDONED(meta, msg_hdr, sctp)) {
711 continue;
712 }
713 for (mp = meta->b_cont; mp != NULL; mp = mp->b_next) {
714 if (SCTP_CHUNK_WANT_REXMIT(mp)) {
715 /*
716 * Use the same peer address to do fast
717 * retransmission. If the original peer
718 * address is dead, switch to the current
719 * one. Record the old one so that we
720 * will pick the chunks sent to the old
721 * one for fast retransmission.
722 */
723 chunk_fp = SCTP_CHUNK_DEST(mp);
724 if (*fp == NULL) {
725 *fp = chunk_fp;
726 if ((*fp)->sf_state !=
727 SCTP_FADDRS_ALIVE) {
728 old_fp = *fp;
729 *fp = sctp->sctp_current;
730 }
731 } else if (old_fp == NULL && *fp != chunk_fp) {
732 continue;
733 } else if (old_fp != NULL &&
734 old_fp != chunk_fp) {
735 continue;
736 }
737
738 sdh = (sctp_data_hdr_t *)mp->b_rptr;
739 msglen = ntohs(sdh->sdh_len);
740 if ((extra = msglen & (SCTP_ALIGN - 1)) != 0) {
741 extra = SCTP_ALIGN - extra;
742 }
743
744 /*
745 * We still return at least the first message
746 * even if that message cannot fit in as
747 * PMTU may have changed.
748 */
749 if (*total + msglen + extra >
750 (*fp)->sf_pmss && start_mp != NULL) {
751 return (start_mp);
752 }
753 if ((nmp = dupmsg(mp)) == NULL)
754 return (start_mp);
755 if (extra > 0) {
756 fill = sctp_get_padding(sctp, extra);
757 if (fill != NULL) {
758 linkb(nmp, fill);
759 } else {
760 return (start_mp);
761 }
762 }
763 SCTPS_BUMP_MIB(sctps, sctpOutFastRetrans);
764 BUMP_LOCAL(sctp->sctp_rxtchunks);
765 SCTP_CHUNK_CLEAR_REXMIT(mp);
766 if (start_mp == NULL) {
767 start_mp = nmp;
768 } else {
769 linkb(end_mp, nmp);
770 }
771 end_mp = nmp;
772 *total += msglen + extra;
773 dprint(2, ("sctp_find_fast_rexmit_mblks: "
774 "tsn %x\n", sdh->sdh_tsn));
775 }
776 }
777 }
778 /* Clear the flag as there is no more message to be fast rexmitted. */
779 sctp->sctp_chk_fast_rexmit = B_FALSE;
780 return (start_mp);
781 }
782
783 /* A debug function just to make sure that a mblk chain is not broken */
784 #ifdef DEBUG
785 static boolean_t
786 sctp_verify_chain(mblk_t *head, mblk_t *tail)
787 {
788 mblk_t *mp = head;
789
790 if (head == NULL || tail == NULL)
791 return (B_TRUE);
792 while (mp != NULL) {
793 if (mp == tail)
794 return (B_TRUE);
795 mp = mp->b_next;
796 }
797 return (B_FALSE);
798 }
799 #endif
800
801 /*
802 * Gets the next unsent chunk to transmit. Messages that are abandoned are
803 * skipped. A message can be abandoned if it has a non-zero timetolive and
804 * transmission has not yet started or if it is a partially reliable
805 * message and its time is up (assuming we are PR-SCTP aware).
806 * We only return a chunk if it will fit entirely in the current packet.
807 * 'cansend' is used to determine if need to try and chunkify messages from
808 * the unsent list, if any, and also as an input to sctp_chunkify() if so.
809 *
810 * firstseg_len indicates the space already used, cansend represents remaining
811 * space in the window, ((sf_pmss - firstseg_len) can therefore reasonably
812 * be used to compute the cansend arg).
813 */
814 mblk_t *
815 sctp_get_msg_to_send(sctp_t *sctp, mblk_t **mp, mblk_t *meta, int *error,
816 int32_t firstseg_len, uint32_t cansend, sctp_faddr_t *fp)
817 {
818 mblk_t *mp1;
819 sctp_msg_hdr_t *msg_hdr;
820 mblk_t *tmp_meta;
821 sctp_faddr_t *fp1;
822
823 ASSERT(error != NULL && mp != NULL);
824 *error = 0;
825
826 ASSERT(sctp->sctp_current != NULL);
827
828 chunkified:
829 while (meta != NULL) {
830 tmp_meta = meta->b_next;
831 msg_hdr = (sctp_msg_hdr_t *)meta->b_rptr;
832 mp1 = meta->b_cont;
833 if (SCTP_IS_MSG_ABANDONED(meta))
834 goto next_msg;
835 if (!SCTP_MSG_TO_BE_ABANDONED(meta, msg_hdr, sctp)) {
836 while (mp1 != NULL) {
837 if (SCTP_CHUNK_CANSEND(mp1)) {
838 *mp = mp1;
839 #ifdef DEBUG
840 ASSERT(sctp_verify_chain(
841 sctp->sctp_xmit_head, meta));
842 #endif
843 return (meta);
844 }
845 mp1 = mp1->b_next;
846 }
847 goto next_msg;
848 }
849 /*
850 * If we come here and the first chunk is sent, then we
851 * we are PR-SCTP aware, in which case if the cumulative
852 * TSN has moved upto or beyond the first chunk (which
853 * means all the previous messages have been cumulative
854 * SACK'd), then we send a Forward TSN with the last
855 * chunk that was sent in this message. If we can't send
856 * a Forward TSN because previous non-abandoned messages
857 * have not been acked then we will defer the Forward TSN
858 * to sctp_rexmit() or sctp_cumack().
859 */
860 if (SCTP_CHUNK_ISSENT(mp1)) {
861 *error = sctp_check_abandoned_msg(sctp, meta);
862 if (*error != 0) {
863 #ifdef DEBUG
864 ASSERT(sctp_verify_chain(sctp->sctp_xmit_head,
865 sctp->sctp_xmit_tail));
866 #endif
867 return (NULL);
868 }
869 goto next_msg;
870 }
871 BUMP_LOCAL(sctp->sctp_prsctpdrop);
872 ASSERT(sctp->sctp_unsent >= msg_hdr->smh_msglen);
873 if (meta->b_prev == NULL) {
874 ASSERT(sctp->sctp_xmit_head == meta);
875 sctp->sctp_xmit_head = tmp_meta;
876 if (sctp->sctp_xmit_tail == meta)
877 sctp->sctp_xmit_tail = tmp_meta;
878 meta->b_next = NULL;
879 if (tmp_meta != NULL)
880 tmp_meta->b_prev = NULL;
881 } else if (meta->b_next == NULL) {
882 if (sctp->sctp_xmit_tail == meta)
883 sctp->sctp_xmit_tail = meta->b_prev;
884 meta->b_prev->b_next = NULL;
885 meta->b_prev = NULL;
886 } else {
887 meta->b_prev->b_next = tmp_meta;
888 tmp_meta->b_prev = meta->b_prev;
889 if (sctp->sctp_xmit_tail == meta)
890 sctp->sctp_xmit_tail = tmp_meta;
891 meta->b_prev = NULL;
892 meta->b_next = NULL;
893 }
894 sctp->sctp_unsent -= msg_hdr->smh_msglen;
895 /*
896 * Update ULP the amount of queued data, which is
897 * sent-unack'ed + unsent.
898 */
899 if (!SCTP_IS_DETACHED(sctp))
900 SCTP_TXQ_UPDATE(sctp);
901 sctp_sendfail_event(sctp, meta, 0, B_TRUE);
902 next_msg:
903 meta = tmp_meta;
904 }
905 /* chunkify, if needed */
906 if (cansend > 0 && sctp->sctp_xmit_unsent != NULL) {
907 ASSERT(sctp->sctp_unsent > 0);
908 if (fp == NULL) {
909 fp = SCTP_CHUNK_DEST(sctp->sctp_xmit_unsent);
910 if (fp == NULL || fp->sf_state != SCTP_FADDRS_ALIVE)
911 fp = sctp->sctp_current;
912 } else {
913 /*
914 * If user specified destination, try to honor that.
915 */
916 fp1 = SCTP_CHUNK_DEST(sctp->sctp_xmit_unsent);
917 if (fp1 != NULL && fp1->sf_state == SCTP_FADDRS_ALIVE &&
918 fp1 != fp) {
919 goto chunk_done;
920 }
921 }
922 meta = sctp_chunkify(sctp, fp->sf_pmss, firstseg_len, cansend);
923 if (meta == NULL)
924 goto chunk_done;
925 /*
926 * sctp_chunkify() won't advance sctp_xmit_tail if it adds
927 * new chunk(s) to the tail, so we need to skip the
928 * sctp_xmit_tail, which would have already been processed.
929 * This could happen when there is unacked chunks, but
930 * nothing new to send.
931 * When sctp_chunkify() is called when the transmit queue
932 * is empty then we need to start from sctp_xmit_tail.
933 */
934 if (SCTP_CHUNK_ISSENT(sctp->sctp_xmit_tail->b_cont)) {
935 #ifdef DEBUG
936 mp1 = sctp->sctp_xmit_tail->b_cont;
937 while (mp1 != NULL) {
938 ASSERT(!SCTP_CHUNK_CANSEND(mp1));
939 mp1 = mp1->b_next;
940 }
941 #endif
942 if ((meta = sctp->sctp_xmit_tail->b_next) == NULL)
943 goto chunk_done;
944 }
945 goto chunkified;
946 }
947 chunk_done:
948 #ifdef DEBUG
949 ASSERT(sctp_verify_chain(sctp->sctp_xmit_head, sctp->sctp_xmit_tail));
950 #endif
951 return (NULL);
952 }
953
954 void
955 sctp_fast_rexmit(sctp_t *sctp)
956 {
957 mblk_t *mp, *head;
958 int pktlen = 0;
959 sctp_faddr_t *fp = NULL;
960 sctp_stack_t *sctps = sctp->sctp_sctps;
961
962 ASSERT(sctp->sctp_xmit_head != NULL);
963 mp = sctp_find_fast_rexmit_mblks(sctp, &pktlen, &fp);
964 if (mp == NULL) {
965 SCTP_KSTAT(sctps, sctp_fr_not_found);
966 return;
967 }
968 if ((head = sctp_add_proto_hdr(sctp, fp, mp, 0, NULL)) == NULL) {
969 freemsg(mp);
970 SCTP_KSTAT(sctps, sctp_fr_add_hdr);
971 return;
972 }
973 if ((pktlen > fp->sf_pmss) && fp->sf_isv4) {
974 ipha_t *iph = (ipha_t *)head->b_rptr;
975
976 iph->ipha_fragment_offset_and_flags = 0;
977 }
978
979 sctp_set_iplen(sctp, head, fp->sf_ixa);
980
981 DTRACE_SCTP5(send, mblk_t *, NULL, ip_xmit_attr_t *, fp->sf_ixa,
982 void_ip_t *, mp->b_rptr, sctp_t *, sctp, sctp_hdr_t *,
983 &mp->b_rptr[fp->sf_ixa->ixa_ip_hdr_length]);
984
985 (void) conn_ip_output(head, fp->sf_ixa);
986 BUMP_LOCAL(sctp->sctp_opkts);
987 sctp->sctp_active = fp->sf_lastactive = ddi_get_lbolt64();
988 }
989
990 void
991 sctp_output(sctp_t *sctp, uint_t num_pkt)
992 {
993 mblk_t *mp = NULL;
994 mblk_t *nmp;
995 mblk_t *head;
996 mblk_t *meta = sctp->sctp_xmit_tail;
997 mblk_t *fill = NULL;
998 uint16_t chunklen;
999 uint32_t cansend;
1000 int32_t seglen;
1001 int32_t xtralen;
1002 int32_t sacklen;
1003 int32_t pad = 0;
1004 int32_t pathmax;
1005 int extra;
1006 int64_t now = LBOLT_FASTPATH64;
1007 sctp_faddr_t *fp;
1008 sctp_faddr_t *lfp;
1009 sctp_data_hdr_t *sdc;
1010 int error;
1011 boolean_t notsent = B_TRUE;
1012 sctp_stack_t *sctps = sctp->sctp_sctps;
1013 uint32_t tsn;
1014
1015 if (sctp->sctp_ftsn == sctp->sctp_lastacked + 1) {
1016 sacklen = 0;
1017 } else {
1018 /* send a SACK chunk */
1019 sacklen = sizeof (sctp_chunk_hdr_t) +
1020 sizeof (sctp_sack_chunk_t) +
1021 (sizeof (sctp_sack_frag_t) * sctp->sctp_sack_gaps);
1022 lfp = sctp->sctp_lastdata;
1023 ASSERT(lfp != NULL);
1024 if (lfp->sf_state != SCTP_FADDRS_ALIVE)
1025 lfp = sctp->sctp_current;
1026 }
1027
1028 cansend = sctp->sctp_frwnd;
1029 if (sctp->sctp_unsent < cansend)
1030 cansend = sctp->sctp_unsent;
1031
1032 /*
1033 * Start persist timer if unable to send or when
1034 * trying to send into a zero window. This timer
1035 * ensures the blocked send attempt is retried.
1036 */
1037 if ((cansend < sctp->sctp_current->sf_pmss / 2) &&
1038 (sctp->sctp_unacked != 0) &&
1039 (sctp->sctp_unacked < sctp->sctp_current->sf_pmss) &&
1040 !sctp->sctp_ndelay ||
1041 (cansend == 0 && sctp->sctp_unacked == 0 &&
1042 sctp->sctp_unsent != 0)) {
1043 head = NULL;
1044 fp = sctp->sctp_current;
1045 goto unsent_data;
1046 }
1047 if (meta != NULL)
1048 mp = meta->b_cont;
1049 while (cansend > 0 && num_pkt-- != 0) {
1050 pad = 0;
1051
1052 /*
1053 * Find first segment eligible for transmit.
1054 */
1055 while (mp != NULL) {
1056 if (SCTP_CHUNK_CANSEND(mp))
1057 break;
1058 mp = mp->b_next;
1059 }
1060 if (mp == NULL) {
1061 meta = sctp_get_msg_to_send(sctp, &mp,
1062 meta == NULL ? NULL : meta->b_next, &error, sacklen,
1063 cansend, NULL);
1064 if (error != 0 || meta == NULL) {
1065 head = NULL;
1066 fp = sctp->sctp_current;
1067 goto unsent_data;
1068 }
1069 sctp->sctp_xmit_tail = meta;
1070 }
1071
1072 sdc = (sctp_data_hdr_t *)mp->b_rptr;
1073 seglen = ntohs(sdc->sdh_len);
1074 xtralen = sizeof (*sdc);
1075 chunklen = seglen - xtralen;
1076
1077 /*
1078 * Check rwnd.
1079 */
1080 if (chunklen > cansend) {
1081 head = NULL;
1082 fp = SCTP_CHUNK_DEST(meta);
1083 if (fp == NULL || fp->sf_state != SCTP_FADDRS_ALIVE)
1084 fp = sctp->sctp_current;
1085 goto unsent_data;
1086 }
1087 if ((extra = seglen & (SCTP_ALIGN - 1)) != 0)
1088 extra = SCTP_ALIGN - extra;
1089
1090 /*
1091 * Pick destination address, and check cwnd.
1092 */
1093 if (sacklen > 0 && (seglen + extra <= lfp->sf_cwnd -
1094 lfp->sf_suna) &&
1095 (seglen + sacklen + extra <= lfp->sf_pmss)) {
1096 /*
1097 * Only include SACK chunk if it can be bundled
1098 * with a data chunk, and sent to sctp_lastdata.
1099 */
1100 pathmax = lfp->sf_cwnd - lfp->sf_suna;
1101
1102 fp = lfp;
1103 if ((nmp = dupmsg(mp)) == NULL) {
1104 head = NULL;
1105 goto unsent_data;
1106 }
1107 SCTP_CHUNK_CLEAR_FLAGS(nmp);
1108 head = sctp_add_proto_hdr(sctp, fp, nmp, sacklen,
1109 &error);
1110 if (head == NULL) {
1111 /*
1112 * If none of the source addresses are
1113 * available (i.e error == EHOSTUNREACH),
1114 * pretend we have sent the data. We will
1115 * eventually time out trying to retramsmit
1116 * the data if the interface never comes up.
1117 * If we have already sent some stuff (i.e.,
1118 * notsent is B_FALSE) then we are fine, else
1119 * just mark this packet as sent.
1120 */
1121 if (notsent && error == EHOSTUNREACH) {
1122 SCTP_CHUNK_SENT(sctp, mp, sdc,
1123 fp, chunklen, meta);
1124 }
1125 freemsg(nmp);
1126 SCTP_KSTAT(sctps, sctp_output_failed);
1127 goto unsent_data;
1128 }
1129 seglen += sacklen;
1130 xtralen += sacklen;
1131 sacklen = 0;
1132 } else {
1133 fp = SCTP_CHUNK_DEST(meta);
1134 if (fp == NULL || fp->sf_state != SCTP_FADDRS_ALIVE)
1135 fp = sctp->sctp_current;
1136 /*
1137 * If we haven't sent data to this destination for
1138 * a while, do slow start again.
1139 */
1140 if (now - fp->sf_lastactive > fp->sf_rto) {
1141 SET_CWND(fp, fp->sf_pmss,
1142 sctps->sctps_slow_start_after_idle);
1143 }
1144
1145 pathmax = fp->sf_cwnd - fp->sf_suna;
1146 if (seglen + extra > pathmax) {
1147 head = NULL;
1148 goto unsent_data;
1149 }
1150 if ((nmp = dupmsg(mp)) == NULL) {
1151 head = NULL;
1152 goto unsent_data;
1153 }
1154 SCTP_CHUNK_CLEAR_FLAGS(nmp);
1155 head = sctp_add_proto_hdr(sctp, fp, nmp, 0, &error);
1156 if (head == NULL) {
1157 /*
1158 * If none of the source addresses are
1159 * available (i.e error == EHOSTUNREACH),
1160 * pretend we have sent the data. We will
1161 * eventually time out trying to retramsmit
1162 * the data if the interface never comes up.
1163 * If we have already sent some stuff (i.e.,
1164 * notsent is B_FALSE) then we are fine, else
1165 * just mark this packet as sent.
1166 */
1167 if (notsent && error == EHOSTUNREACH) {
1168 SCTP_CHUNK_SENT(sctp, mp, sdc,
1169 fp, chunklen, meta);
1170 }
1171 freemsg(nmp);
1172 SCTP_KSTAT(sctps, sctp_output_failed);
1173 goto unsent_data;
1174 }
1175 }
1176 fp->sf_lastactive = now;
1177 if (pathmax > fp->sf_pmss)
1178 pathmax = fp->sf_pmss;
1179 SCTP_CHUNK_SENT(sctp, mp, sdc, fp, chunklen, meta);
1180 mp = mp->b_next;
1181
1182 /*
1183 * Use this chunk to measure RTT?
1184 * Must not be a retransmision of an earlier chunk,
1185 * ensure the tsn is current.
1186 */
1187 tsn = ntohl(sdc->sdh_tsn);
1188 if (sctp->sctp_out_time == 0 && tsn == (sctp->sctp_ltsn - 1)) {
1189 sctp->sctp_out_time = now;
1190 sctp->sctp_rtt_tsn = tsn;
1191 }
1192 if (extra > 0) {
1193 fill = sctp_get_padding(sctp, extra);
1194 if (fill != NULL) {
1195 linkb(head, fill);
1196 pad = extra;
1197 seglen += extra;
1198 } else {
1199 goto unsent_data;
1200 }
1201 }
1202 /*
1203 * Bundle chunks. We linkb() the chunks together to send
1204 * downstream in a single packet.
1205 * Partial chunks MUST NOT be bundled with full chunks, so we
1206 * rely on sctp_get_msg_to_send() to only return messages that
1207 * will fit entirely in the current packet.
1208 */
1209 while (seglen < pathmax) {
1210 int32_t new_len;
1211 int32_t new_xtralen;
1212
1213 while (mp != NULL) {
1214 if (SCTP_CHUNK_CANSEND(mp))
1215 break;
1216 mp = mp->b_next;
1217 }
1218 if (mp == NULL) {
1219 meta = sctp_get_msg_to_send(sctp, &mp,
1220 meta->b_next, &error, seglen,
1221 (seglen - xtralen) >= cansend ? 0 :
1222 cansend - seglen, fp);
1223 if (error != 0)
1224 break;
1225 /* If no more eligible chunks, cease bundling */
1226 if (meta == NULL)
1227 break;
1228 sctp->sctp_xmit_tail = meta;
1229 }
1230 ASSERT(mp != NULL);
1231 if (!SCTP_CHUNK_ISSENT(mp) && SCTP_CHUNK_DEST(meta) &&
1232 fp != SCTP_CHUNK_DEST(meta)) {
1233 break;
1234 }
1235 sdc = (sctp_data_hdr_t *)mp->b_rptr;
1236 chunklen = ntohs(sdc->sdh_len);
1237 if ((extra = chunklen & (SCTP_ALIGN - 1)) != 0)
1238 extra = SCTP_ALIGN - extra;
1239
1240 new_len = seglen + chunklen;
1241 new_xtralen = xtralen + sizeof (*sdc);
1242 chunklen -= sizeof (*sdc);
1243
1244 if (new_len - new_xtralen > cansend ||
1245 new_len + extra > pathmax) {
1246 break;
1247 }
1248 if ((nmp = dupmsg(mp)) == NULL)
1249 break;
1250 if (extra > 0) {
1251 fill = sctp_get_padding(sctp, extra);
1252 if (fill != NULL) {
1253 pad += extra;
1254 new_len += extra;
1255 linkb(nmp, fill);
1256 } else {
1257 freemsg(nmp);
1258 break;
1259 }
1260 }
1261 seglen = new_len;
1262 xtralen = new_xtralen;
1263 SCTP_CHUNK_CLEAR_FLAGS(nmp);
1264 SCTP_CHUNK_SENT(sctp, mp, sdc, fp, chunklen, meta);
1265 linkb(head, nmp);
1266 mp = mp->b_next;
1267 }
1268 if ((seglen > fp->sf_pmss) && fp->sf_isv4) {
1269 ipha_t *iph = (ipha_t *)head->b_rptr;
1270
1271 /*
1272 * Path MTU is different from what we thought it would
1273 * be when we created chunks, or IP headers have grown.
1274 * Need to clear the DF bit.
1275 */
1276 iph->ipha_fragment_offset_and_flags = 0;
1277 }
1278 /* xmit segment */
1279 ASSERT(cansend >= seglen - pad - xtralen);
1280 cansend -= (seglen - pad - xtralen);
1281 dprint(2, ("sctp_output: Sending packet %d bytes, tsn %x "
1282 "ssn %d to %p (rwnd %d, cansend %d, lastack_rxd %x)\n",
1283 seglen - xtralen, ntohl(sdc->sdh_tsn),
1284 ntohs(sdc->sdh_ssn), (void *)fp, sctp->sctp_frwnd,
1285 cansend, sctp->sctp_lastack_rxd));
1286 sctp_set_iplen(sctp, head, fp->sf_ixa);
1287
1288 DTRACE_SCTP5(send, mblk_t *, NULL, ip_xmit_attr_t *, fp->sf_ixa,
1289 void_ip_t *, head->b_rptr, sctp_t *, sctp, sctp_hdr_t *,
1290 &head->b_rptr[fp->sf_ixa->ixa_ip_hdr_length]);
1291
1292 (void) conn_ip_output(head, fp->sf_ixa);
1293 BUMP_LOCAL(sctp->sctp_opkts);
1294 /* arm rto timer (if not set) */
1295 if (!fp->sf_timer_running)
1296 SCTP_FADDR_TIMER_RESTART(sctp, fp, fp->sf_rto);
1297 notsent = B_FALSE;
1298 }
1299 sctp->sctp_active = now;
1300 return;
1301 unsent_data:
1302 /* arm persist timer (if rto timer not set) */
1303 if (!fp->sf_timer_running)
1304 SCTP_FADDR_TIMER_RESTART(sctp, fp, fp->sf_rto);
1305 if (head != NULL)
1306 freemsg(head);
1307 }
1308
1309 /*
1310 * The following two functions initialize and destroy the cache
1311 * associated with the sets used for PR-SCTP.
1312 */
1313 void
1314 sctp_ftsn_sets_init(void)
1315 {
1316 sctp_kmem_ftsn_set_cache = kmem_cache_create("sctp_ftsn_set_cache",
1317 sizeof (sctp_ftsn_set_t), 0, NULL, NULL, NULL, NULL,
1318 NULL, 0);
1319 }
1320
1321 void
1322 sctp_ftsn_sets_fini(void)
1323 {
1324 kmem_cache_destroy(sctp_kmem_ftsn_set_cache);
1325 }
1326
1327
1328 /* Free PR-SCTP sets */
1329 void
1330 sctp_free_ftsn_set(sctp_ftsn_set_t *s)
1331 {
1332 sctp_ftsn_set_t *p;
1333
1334 while (s != NULL) {
1335 p = s->next;
1336 s->next = NULL;
1337 kmem_cache_free(sctp_kmem_ftsn_set_cache, s);
1338 s = p;
1339 }
1340 }
1341
1342 /*
1343 * Given a message meta block, meta, this routine creates or modifies
1344 * the set that will be used to generate a Forward TSN chunk. If the
1345 * entry for stream id, sid, for this message already exists, the
1346 * sequence number, ssn, is updated if it is greater than the existing
1347 * one. If an entry for this sid does not exist, one is created if
1348 * the size does not exceed fp->sf_pmss. We return false in case
1349 * or an error.
1350 */
1351 boolean_t
1352 sctp_add_ftsn_set(sctp_ftsn_set_t **s, sctp_faddr_t *fp, mblk_t *meta,
1353 uint_t *nsets, uint32_t *slen)
1354 {
1355 sctp_ftsn_set_t *p;
1356 sctp_msg_hdr_t *msg_hdr = (sctp_msg_hdr_t *)meta->b_rptr;
1357 uint16_t sid = htons(msg_hdr->smh_sid);
1358 /* msg_hdr->smh_ssn is already in NBO */
1359 uint16_t ssn = msg_hdr->smh_ssn;
1360
1361 ASSERT(s != NULL && nsets != NULL);
1362 ASSERT((*nsets == 0 && *s == NULL) || (*nsets > 0 && *s != NULL));
1363
1364 if (*s == NULL) {
1365 ASSERT((*slen + sizeof (uint32_t)) <= fp->sf_pmss);
1366 *s = kmem_cache_alloc(sctp_kmem_ftsn_set_cache, KM_NOSLEEP);
1367 if (*s == NULL)
1368 return (B_FALSE);
1369 (*s)->ftsn_entries.ftsn_sid = sid;
1370 (*s)->ftsn_entries.ftsn_ssn = ssn;
1371 (*s)->next = NULL;
1372 *nsets = 1;
1373 *slen += sizeof (uint32_t);
1374 return (B_TRUE);
1375 }
1376 for (p = *s; p->next != NULL; p = p->next) {
1377 if (p->ftsn_entries.ftsn_sid == sid) {
1378 if (SSN_GT(ssn, p->ftsn_entries.ftsn_ssn))
1379 p->ftsn_entries.ftsn_ssn = ssn;
1380 return (B_TRUE);
1381 }
1382 }
1383 /* the last one */
1384 if (p->ftsn_entries.ftsn_sid == sid) {
1385 if (SSN_GT(ssn, p->ftsn_entries.ftsn_ssn))
1386 p->ftsn_entries.ftsn_ssn = ssn;
1387 } else {
1388 if ((*slen + sizeof (uint32_t)) > fp->sf_pmss)
1389 return (B_FALSE);
1390 p->next = kmem_cache_alloc(sctp_kmem_ftsn_set_cache,
1391 KM_NOSLEEP);
1392 if (p->next == NULL)
1393 return (B_FALSE);
1394 p = p->next;
1395 p->ftsn_entries.ftsn_sid = sid;
1396 p->ftsn_entries.ftsn_ssn = ssn;
1397 p->next = NULL;
1398 (*nsets)++;
1399 *slen += sizeof (uint32_t);
1400 }
1401 return (B_TRUE);
1402 }
1403
1404 /*
1405 * Given a set of stream id - sequence number pairs, this routing creates
1406 * a Forward TSN chunk. The cumulative TSN (advanced peer ack point)
1407 * for the chunk is obtained from sctp->sctp_adv_pap. The caller
1408 * will add the IP/SCTP header.
1409 */
1410 mblk_t *
1411 sctp_make_ftsn_chunk(sctp_t *sctp, sctp_faddr_t *fp, sctp_ftsn_set_t *sets,
1412 uint_t nsets, uint32_t seglen)
1413 {
1414 mblk_t *ftsn_mp;
1415 sctp_chunk_hdr_t *ch_hdr;
1416 uint32_t *advtsn;
1417 uint16_t schlen;
1418 size_t xtralen;
1419 ftsn_entry_t *ftsn_entry;
1420 sctp_stack_t *sctps = sctp->sctp_sctps;
1421
1422 seglen += sizeof (sctp_chunk_hdr_t);
1423 if (fp->sf_isv4)
1424 xtralen = sctp->sctp_hdr_len + sctps->sctps_wroff_xtra;
1425 else
1426 xtralen = sctp->sctp_hdr6_len + sctps->sctps_wroff_xtra;
1427 ftsn_mp = allocb(xtralen + seglen, BPRI_MED);
1428 if (ftsn_mp == NULL)
1429 return (NULL);
1430 ftsn_mp->b_rptr += xtralen;
1431 ftsn_mp->b_wptr = ftsn_mp->b_rptr + seglen;
1432
1433 ch_hdr = (sctp_chunk_hdr_t *)ftsn_mp->b_rptr;
1434 ch_hdr->sch_id = CHUNK_FORWARD_TSN;
1435 ch_hdr->sch_flags = 0;
1436 /*
1437 * The cast here should not be an issue since seglen is
1438 * the length of the Forward TSN chunk.
1439 */
1440 schlen = (uint16_t)seglen;
1441 U16_TO_ABE16(schlen, &(ch_hdr->sch_len));
1442
1443 advtsn = (uint32_t *)(ch_hdr + 1);
1444 U32_TO_ABE32(sctp->sctp_adv_pap, advtsn);
1445 ftsn_entry = (ftsn_entry_t *)(advtsn + 1);
1446 while (nsets > 0) {
1447 ASSERT((uchar_t *)&ftsn_entry[1] <= ftsn_mp->b_wptr);
1448 ftsn_entry->ftsn_sid = sets->ftsn_entries.ftsn_sid;
1449 ftsn_entry->ftsn_ssn = sets->ftsn_entries.ftsn_ssn;
1450 ftsn_entry++;
1451 sets = sets->next;
1452 nsets--;
1453 }
1454 return (ftsn_mp);
1455 }
1456
1457 /*
1458 * Given a starting message, the routine steps through all the
1459 * messages whose TSN is less than sctp->sctp_adv_pap and creates
1460 * ftsn sets. The ftsn sets is then used to create an Forward TSN
1461 * chunk. All the messages, that have chunks that are included in the
1462 * ftsn sets, are flagged abandonded. If a message is partially sent
1463 * and is deemed abandoned, all remaining unsent chunks are marked
1464 * abandoned and are deducted from sctp_unsent.
1465 */
1466 void
1467 sctp_make_ftsns(sctp_t *sctp, mblk_t *meta, mblk_t *mp, mblk_t **nmp,
1468 sctp_faddr_t *fp, uint32_t *seglen)
1469 {
1470 mblk_t *mp1 = mp;
1471 mblk_t *mp_head = mp;
1472 mblk_t *meta_head = meta;
1473 mblk_t *head;
1474 sctp_ftsn_set_t *sets = NULL;
1475 uint_t nsets = 0;
1476 uint16_t clen;
1477 sctp_data_hdr_t *sdc;
1478 uint32_t sacklen;
1479 uint32_t adv_pap = sctp->sctp_adv_pap;
1480 uint32_t unsent = 0;
1481 boolean_t ubit;
1482 sctp_stack_t *sctps = sctp->sctp_sctps;
1483
1484 *seglen = sizeof (uint32_t);
1485
1486 sdc = (sctp_data_hdr_t *)mp1->b_rptr;
1487 while (meta != NULL &&
1488 SEQ_GEQ(sctp->sctp_adv_pap, ntohl(sdc->sdh_tsn))) {
1489 /*
1490 * Skip adding FTSN sets for un-ordered messages as they do
1491 * not have SSNs.
1492 */
1493 ubit = SCTP_DATA_GET_UBIT(sdc);
1494 if (!ubit &&
1495 !sctp_add_ftsn_set(&sets, fp, meta, &nsets, seglen)) {
1496 meta = NULL;
1497 sctp->sctp_adv_pap = adv_pap;
1498 goto ftsn_done;
1499 }
1500 while (mp1 != NULL && SCTP_CHUNK_ISSENT(mp1)) {
1501 sdc = (sctp_data_hdr_t *)mp1->b_rptr;
1502 adv_pap = ntohl(sdc->sdh_tsn);
1503 mp1 = mp1->b_next;
1504 }
1505 meta = meta->b_next;
1506 if (meta != NULL) {
1507 mp1 = meta->b_cont;
1508 if (!SCTP_CHUNK_ISSENT(mp1))
1509 break;
1510 sdc = (sctp_data_hdr_t *)mp1->b_rptr;
1511 }
1512 }
1513 ftsn_done:
1514 /*
1515 * Can't compare with sets == NULL, since we don't add any
1516 * sets for un-ordered messages.
1517 */
1518 if (meta == meta_head)
1519 return;
1520 *nmp = sctp_make_ftsn_chunk(sctp, fp, sets, nsets, *seglen);
1521 sctp_free_ftsn_set(sets);
1522 if (*nmp == NULL)
1523 return;
1524 if (sctp->sctp_ftsn == sctp->sctp_lastacked + 1) {
1525 sacklen = 0;
1526 } else {
1527 sacklen = sizeof (sctp_chunk_hdr_t) +
1528 sizeof (sctp_sack_chunk_t) +
1529 (sizeof (sctp_sack_frag_t) * sctp->sctp_sack_gaps);
1530 if (*seglen + sacklen > sctp->sctp_lastdata->sf_pmss) {
1531 /* piggybacked SACK doesn't fit */
1532 sacklen = 0;
1533 } else {
1534 fp = sctp->sctp_lastdata;
1535 }
1536 }
1537 head = sctp_add_proto_hdr(sctp, fp, *nmp, sacklen, NULL);
1538 if (head == NULL) {
1539 freemsg(*nmp);
1540 *nmp = NULL;
1541 SCTP_KSTAT(sctps, sctp_send_ftsn_failed);
1542 return;
1543 }
1544 *seglen += sacklen;
1545 *nmp = head;
1546
1547 /*
1548 * XXXNeed to optimise this, the reason it is done here is so
1549 * that we don't have to undo in case of failure.
1550 */
1551 mp1 = mp_head;
1552 sdc = (sctp_data_hdr_t *)mp1->b_rptr;
1553 while (meta_head != NULL &&
1554 SEQ_GEQ(sctp->sctp_adv_pap, ntohl(sdc->sdh_tsn))) {
1555 if (!SCTP_IS_MSG_ABANDONED(meta_head))
1556 SCTP_MSG_SET_ABANDONED(meta_head);
1557 while (mp1 != NULL && SCTP_CHUNK_ISSENT(mp1)) {
1558 sdc = (sctp_data_hdr_t *)mp1->b_rptr;
1559 if (!SCTP_CHUNK_ISACKED(mp1)) {
1560 clen = ntohs(sdc->sdh_len) - sizeof (*sdc);
1561 SCTP_CHUNK_SENT(sctp, mp1, sdc, fp, clen,
1562 meta_head);
1563 }
1564 mp1 = mp1->b_next;
1565 }
1566 while (mp1 != NULL) {
1567 sdc = (sctp_data_hdr_t *)mp1->b_rptr;
1568 if (!SCTP_CHUNK_ABANDONED(mp1)) {
1569 ASSERT(!SCTP_CHUNK_ISSENT(mp1));
1570 unsent += ntohs(sdc->sdh_len) - sizeof (*sdc);
1571 SCTP_ABANDON_CHUNK(mp1);
1572 }
1573 mp1 = mp1->b_next;
1574 }
1575 meta_head = meta_head->b_next;
1576 if (meta_head != NULL) {
1577 mp1 = meta_head->b_cont;
1578 if (!SCTP_CHUNK_ISSENT(mp1))
1579 break;
1580 sdc = (sctp_data_hdr_t *)mp1->b_rptr;
1581 }
1582 }
1583 if (unsent > 0) {
1584 ASSERT(sctp->sctp_unsent >= unsent);
1585 sctp->sctp_unsent -= unsent;
1586 /*
1587 * Update ULP the amount of queued data, which is
1588 * sent-unack'ed + unsent.
1589 */
1590 if (!SCTP_IS_DETACHED(sctp))
1591 SCTP_TXQ_UPDATE(sctp);
1592 }
1593 }
1594
1595 /*
1596 * This function steps through messages starting at meta and checks if
1597 * the message is abandoned. It stops when it hits an unsent chunk or
1598 * a message that has all its chunk acked. This is the only place
1599 * where the sctp_adv_pap is moved forward to indicated abandoned
1600 * messages.
1601 */
1602 void
1603 sctp_check_adv_ack_pt(sctp_t *sctp, mblk_t *meta, mblk_t *mp)
1604 {
1605 uint32_t tsn = sctp->sctp_adv_pap;
1606 sctp_data_hdr_t *sdc;
1607 sctp_msg_hdr_t *msg_hdr;
1608
1609 ASSERT(mp != NULL);
1610 sdc = (sctp_data_hdr_t *)mp->b_rptr;
1611 ASSERT(SEQ_GT(ntohl(sdc->sdh_tsn), sctp->sctp_lastack_rxd));
1612 msg_hdr = (sctp_msg_hdr_t *)meta->b_rptr;
1613 if (!SCTP_IS_MSG_ABANDONED(meta) &&
1614 !SCTP_MSG_TO_BE_ABANDONED(meta, msg_hdr, sctp)) {
1615 return;
1616 }
1617 while (meta != NULL) {
1618 while (mp != NULL && SCTP_CHUNK_ISSENT(mp)) {
1619 sdc = (sctp_data_hdr_t *)mp->b_rptr;
1620 tsn = ntohl(sdc->sdh_tsn);
1621 mp = mp->b_next;
1622 }
1623 if (mp != NULL)
1624 break;
1625 /*
1626 * We continue checking for successive messages only if there
1627 * is a chunk marked for retransmission. Else, we might
1628 * end up sending FTSN prematurely for chunks that have been
1629 * sent, but not yet acked.
1630 */
1631 if ((meta = meta->b_next) != NULL) {
1632 msg_hdr = (sctp_msg_hdr_t *)meta->b_rptr;
1633 if (!SCTP_IS_MSG_ABANDONED(meta) &&
1634 !SCTP_MSG_TO_BE_ABANDONED(meta, msg_hdr, sctp)) {
1635 break;
1636 }
1637 for (mp = meta->b_cont; mp != NULL; mp = mp->b_next) {
1638 if (!SCTP_CHUNK_ISSENT(mp)) {
1639 sctp->sctp_adv_pap = tsn;
1640 return;
1641 }
1642 if (SCTP_CHUNK_WANT_REXMIT(mp))
1643 break;
1644 }
1645 if (mp == NULL)
1646 break;
1647 }
1648 }
1649 sctp->sctp_adv_pap = tsn;
1650 }
1651
1652
1653 /*
1654 * Determine if we should bundle a data chunk with the chunk being
1655 * retransmitted. We bundle if
1656 *
1657 * - the chunk is sent to the same destination and unack'ed.
1658 *
1659 * OR
1660 *
1661 * - the chunk is unsent, i.e. new data.
1662 */
1663 #define SCTP_CHUNK_RX_CANBUNDLE(mp, fp) \
1664 (!SCTP_CHUNK_ABANDONED((mp)) && \
1665 ((SCTP_CHUNK_ISSENT((mp)) && (SCTP_CHUNK_DEST(mp) == (fp) && \
1666 !SCTP_CHUNK_ISACKED(mp))) || \
1667 (((mp)->b_flag & (SCTP_CHUNK_FLAG_REXMIT|SCTP_CHUNK_FLAG_SENT)) != \
1668 SCTP_CHUNK_FLAG_SENT)))
1669
1670 /*
1671 * Retransmit first segment which hasn't been acked with cumtsn or send
1672 * a Forward TSN chunk, if appropriate.
1673 */
1674 void
1675 sctp_rexmit(sctp_t *sctp, sctp_faddr_t *oldfp)
1676 {
1677 mblk_t *mp;
1678 mblk_t *nmp = NULL;
1679 mblk_t *head;
1680 mblk_t *meta = sctp->sctp_xmit_head;
1681 mblk_t *fill;
1682 uint32_t seglen = 0;
1683 uint32_t sacklen;
1684 uint16_t chunklen;
1685 int extra;
1686 sctp_data_hdr_t *sdc;
1687 sctp_faddr_t *fp;
1688 uint32_t adv_pap = sctp->sctp_adv_pap;
1689 boolean_t do_ftsn = B_FALSE;
1690 boolean_t ftsn_check = B_TRUE;
1691 uint32_t first_ua_tsn;
1692 sctp_msg_hdr_t *mhdr;
1693 sctp_stack_t *sctps = sctp->sctp_sctps;
1694 int error;
1695
1696 while (meta != NULL) {
1697 for (mp = meta->b_cont; mp != NULL; mp = mp->b_next) {
1698 uint32_t tsn;
1699
1700 if (!SCTP_CHUNK_ISSENT(mp))
1701 goto window_probe;
1702 /*
1703 * We break in the following cases -
1704 *
1705 * if the advanced peer ack point includes the next
1706 * chunk to be retransmited - possibly the Forward
1707 * TSN was lost.
1708 *
1709 * if we are PRSCTP aware and the next chunk to be
1710 * retransmitted is now abandoned
1711 *
1712 * if the next chunk to be retransmitted is for
1713 * the dest on which the timer went off. (this
1714 * message is not abandoned).
1715 *
1716 * We check for Forward TSN only for the first
1717 * eligible chunk to be retransmitted. The reason
1718 * being if the first eligible chunk is skipped (say
1719 * it was sent to a destination other than oldfp)
1720 * then we cannot advance the cum TSN via Forward
1721 * TSN chunk.
1722 *
1723 * Also, ftsn_check is B_TRUE only for the first
1724 * eligible chunk, it will be B_FALSE for all
1725 * subsequent candidate messages for retransmission.
1726 */
1727 sdc = (sctp_data_hdr_t *)mp->b_rptr;
1728 tsn = ntohl(sdc->sdh_tsn);
1729 if (SEQ_GT(tsn, sctp->sctp_lastack_rxd)) {
1730 if (sctp->sctp_prsctp_aware && ftsn_check) {
1731 if (SEQ_GEQ(sctp->sctp_adv_pap, tsn)) {
1732 ASSERT(sctp->sctp_prsctp_aware);
1733 do_ftsn = B_TRUE;
1734 goto out;
1735 } else {
1736 sctp_check_adv_ack_pt(sctp,
1737 meta, mp);
1738 if (SEQ_GT(sctp->sctp_adv_pap,
1739 adv_pap)) {
1740 do_ftsn = B_TRUE;
1741 goto out;
1742 }
1743 }
1744 ftsn_check = B_FALSE;
1745 }
1746 if (SCTP_CHUNK_DEST(mp) == oldfp)
1747 goto out;
1748 }
1749 }
1750 meta = meta->b_next;
1751 if (meta != NULL && sctp->sctp_prsctp_aware) {
1752 mhdr = (sctp_msg_hdr_t *)meta->b_rptr;
1753
1754 while (meta != NULL && (SCTP_IS_MSG_ABANDONED(meta) ||
1755 SCTP_MSG_TO_BE_ABANDONED(meta, mhdr, sctp))) {
1756 meta = meta->b_next;
1757 }
1758 }
1759 }
1760 window_probe:
1761 /*
1762 * Retransmit fired for a destination which didn't have
1763 * any unacked data pending.
1764 */
1765 if (sctp->sctp_unacked == 0 && sctp->sctp_unsent != 0) {
1766 /*
1767 * Send a window probe. Inflate frwnd to allow
1768 * sending one segment.
1769 */
1770 if (sctp->sctp_frwnd < (oldfp->sf_pmss - sizeof (*sdc)))
1771 sctp->sctp_frwnd = oldfp->sf_pmss - sizeof (*sdc);
1772
1773 /* next TSN to send */
1774 sctp->sctp_rxt_nxttsn = sctp->sctp_ltsn;
1775
1776 /*
1777 * The above sctp_frwnd adjustment is coarse. The "changed"
1778 * sctp_frwnd may allow us to send more than 1 packet. So
1779 * tell sctp_output() to send only 1 packet.
1780 */
1781 sctp_output(sctp, 1);
1782
1783 /* Last sent TSN */
1784 sctp->sctp_rxt_maxtsn = sctp->sctp_ltsn - 1;
1785 ASSERT(sctp->sctp_rxt_maxtsn >= sctp->sctp_rxt_nxttsn);
1786 sctp->sctp_zero_win_probe = B_TRUE;
1787 SCTPS_BUMP_MIB(sctps, sctpOutWinProbe);
1788 }
1789 return;
1790 out:
1791 /*
1792 * After a time out, assume that everything has left the network. So
1793 * we can clear rxt_unacked for the original peer address.
1794 */
1795 oldfp->sf_rxt_unacked = 0;
1796
1797 /*
1798 * If we were probing for zero window, don't adjust retransmission
1799 * variables, but the timer is still backed off.
1800 */
1801 if (sctp->sctp_zero_win_probe) {
1802 mblk_t *pkt;
1803 uint_t pkt_len;
1804
1805 /*
1806 * Get the Zero Win Probe for retrasmission, sctp_rxt_nxttsn
1807 * and sctp_rxt_maxtsn will specify the ZWP packet.
1808 */
1809 fp = oldfp;
1810 if (oldfp->sf_state != SCTP_FADDRS_ALIVE)
1811 fp = sctp_rotate_faddr(sctp, oldfp);
1812 pkt = sctp_rexmit_packet(sctp, &meta, &mp, fp, &pkt_len);
1813 if (pkt != NULL) {
1814 ASSERT(pkt_len <= fp->sf_pmss);
1815 sctp_set_iplen(sctp, pkt, fp->sf_ixa);
1816
1817 DTRACE_SCTP5(send, mblk_t *, NULL,
1818 ip_xmit_attr_t *, fp->sf_ixa,
1819 void_ip_t *, mp->b_rptr, sctp_t *, sctp, sctp_hdr_t *,
1820 &mp->b_rptr[fp->sf_ixa->ixa_ip_hdr_length]);
1821
1822 (void) conn_ip_output(pkt, fp->sf_ixa);
1823 BUMP_LOCAL(sctp->sctp_opkts);
1824 } else {
1825 SCTP_KSTAT(sctps, sctp_ss_rexmit_failed);
1826 }
1827
1828 /*
1829 * The strikes will be clear by sctp_faddr_alive() when the
1830 * other side sends us an ack.
1831 */
1832 oldfp->sf_strikes++;
1833 sctp->sctp_strikes++;
1834
1835 SCTP_CALC_RXT(sctp, oldfp, sctp->sctp_rto_max);
1836 if (oldfp != fp && oldfp->sf_suna != 0)
1837 SCTP_FADDR_TIMER_RESTART(sctp, oldfp, fp->sf_rto);
1838 SCTP_FADDR_TIMER_RESTART(sctp, fp, fp->sf_rto);
1839 SCTPS_BUMP_MIB(sctps, sctpOutWinProbe);
1840 return;
1841 }
1842
1843 /*
1844 * Enter slowstart for this destination
1845 */
1846 oldfp->sf_ssthresh = oldfp->sf_cwnd / 2;
1847 if (oldfp->sf_ssthresh < 2 * oldfp->sf_pmss)
1848 oldfp->sf_ssthresh = 2 * oldfp->sf_pmss;
1849 oldfp->sf_cwnd = oldfp->sf_pmss;
1850 oldfp->sf_pba = 0;
1851 fp = sctp_rotate_faddr(sctp, oldfp);
1852 ASSERT(fp != NULL);
1853 sdc = (sctp_data_hdr_t *)mp->b_rptr;
1854
1855 first_ua_tsn = ntohl(sdc->sdh_tsn);
1856 if (do_ftsn) {
1857 sctp_make_ftsns(sctp, meta, mp, &nmp, fp, &seglen);
1858 if (nmp == NULL) {
1859 sctp->sctp_adv_pap = adv_pap;
1860 goto restart_timer;
1861 }
1862 head = nmp;
1863 /*
1864 * Move to the next unabandoned chunk. XXXCheck if meta will
1865 * always be marked abandoned.
1866 */
1867 while (meta != NULL && SCTP_IS_MSG_ABANDONED(meta))
1868 meta = meta->b_next;
1869 if (meta != NULL)
1870 mp = mp->b_cont;
1871 else
1872 mp = NULL;
1873 goto try_bundle;
1874 }
1875 seglen = ntohs(sdc->sdh_len);
1876 chunklen = seglen - sizeof (*sdc);
1877 if ((extra = seglen & (SCTP_ALIGN - 1)) != 0)
1878 extra = SCTP_ALIGN - extra;
1879
1880 /* Find out if we need to piggyback SACK. */
1881 if (sctp->sctp_ftsn == sctp->sctp_lastacked + 1) {
1882 sacklen = 0;
1883 } else {
1884 sacklen = sizeof (sctp_chunk_hdr_t) +
1885 sizeof (sctp_sack_chunk_t) +
1886 (sizeof (sctp_sack_frag_t) * sctp->sctp_sack_gaps);
1887 if (seglen + sacklen > sctp->sctp_lastdata->sf_pmss) {
1888 /* piggybacked SACK doesn't fit */
1889 sacklen = 0;
1890 } else {
1891 /*
1892 * OK, we have room to send SACK back. But we
1893 * should send it back to the last fp where we
1894 * receive data from, unless sctp_lastdata equals
1895 * oldfp, then we should probably not send it
1896 * back to that fp. Also we should check that
1897 * the fp is alive.
1898 */
1899 if (sctp->sctp_lastdata != oldfp &&
1900 sctp->sctp_lastdata->sf_state ==
1901 SCTP_FADDRS_ALIVE) {
1902 fp = sctp->sctp_lastdata;
1903 }
1904 }
1905 }
1906
1907 /*
1908 * Cancel RTT measurement if the retransmitted TSN is before the
1909 * TSN used for timimg.
1910 */
1911 if (sctp->sctp_out_time != 0 &&
1912 SEQ_GEQ(sctp->sctp_rtt_tsn, sdc->sdh_tsn)) {
1913 sctp->sctp_out_time = 0;
1914 }
1915 /* Clear the counter as the RTT calculation may be off. */
1916 fp->sf_rtt_updates = 0;
1917 oldfp->sf_rtt_updates = 0;
1918
1919 /*
1920 * After a timeout, we should change the current faddr so that
1921 * new chunks will be sent to the alternate address.
1922 */
1923 sctp_set_faddr_current(sctp, fp);
1924
1925 nmp = dupmsg(mp);
1926 if (nmp == NULL)
1927 goto restart_timer;
1928 if (extra > 0) {
1929 fill = sctp_get_padding(sctp, extra);
1930 if (fill != NULL) {
1931 linkb(nmp, fill);
1932 seglen += extra;
1933 } else {
1934 freemsg(nmp);
1935 goto restart_timer;
1936 }
1937 }
1938 SCTP_CHUNK_CLEAR_FLAGS(nmp);
1939 head = sctp_add_proto_hdr(sctp, fp, nmp, sacklen, NULL);
1940 if (head == NULL) {
1941 freemsg(nmp);
1942 SCTP_KSTAT(sctps, sctp_rexmit_failed);
1943 goto restart_timer;
1944 }
1945 seglen += sacklen;
1946
1947 SCTP_CHUNK_SENT(sctp, mp, sdc, fp, chunklen, meta);
1948
1949 mp = mp->b_next;
1950
1951 try_bundle:
1952 /* We can at least and at most send 1 packet at timeout. */
1953 while (seglen < fp->sf_pmss) {
1954 int32_t new_len;
1955
1956 /* Go through the list to find more chunks to be bundled. */
1957 while (mp != NULL) {
1958 /* Check if the chunk can be bundled. */
1959 if (SCTP_CHUNK_RX_CANBUNDLE(mp, oldfp))
1960 break;
1961 mp = mp->b_next;
1962 }
1963 /* Go to the next message. */
1964 if (mp == NULL) {
1965 for (meta = meta->b_next; meta != NULL;
1966 meta = meta->b_next) {
1967 mhdr = (sctp_msg_hdr_t *)meta->b_rptr;
1968
1969 if (SCTP_IS_MSG_ABANDONED(meta) ||
1970 SCTP_MSG_TO_BE_ABANDONED(meta, mhdr,
1971 sctp)) {
1972 continue;
1973 }
1974
1975 mp = meta->b_cont;
1976 goto try_bundle;
1977 }
1978 /*
1979 * Check if there is a new message which potentially
1980 * could be bundled with this retransmission.
1981 */
1982 meta = sctp_get_msg_to_send(sctp, &mp, NULL, &error,
1983 seglen, fp->sf_pmss - seglen, NULL);
1984 if (error != 0 || meta == NULL) {
1985 /* No more chunk to be bundled. */
1986 break;
1987 } else {
1988 goto try_bundle;
1989 }
1990 }
1991
1992 sdc = (sctp_data_hdr_t *)mp->b_rptr;
1993 new_len = ntohs(sdc->sdh_len);
1994 chunklen = new_len - sizeof (*sdc);
1995
1996 if ((extra = new_len & (SCTP_ALIGN - 1)) != 0)
1997 extra = SCTP_ALIGN - extra;
1998 if ((new_len = seglen + new_len + extra) > fp->sf_pmss)
1999 break;
2000 if ((nmp = dupmsg(mp)) == NULL)
2001 break;
2002
2003 if (extra > 0) {
2004 fill = sctp_get_padding(sctp, extra);
2005 if (fill != NULL) {
2006 linkb(nmp, fill);
2007 } else {
2008 freemsg(nmp);
2009 break;
2010 }
2011 }
2012 linkb(head, nmp);
2013
2014 SCTP_CHUNK_CLEAR_FLAGS(nmp);
2015 SCTP_CHUNK_SENT(sctp, mp, sdc, fp, chunklen, meta);
2016
2017 seglen = new_len;
2018 mp = mp->b_next;
2019 }
2020 done_bundle:
2021 if ((seglen > fp->sf_pmss) && fp->sf_isv4) {
2022 ipha_t *iph = (ipha_t *)head->b_rptr;
2023
2024 /*
2025 * Path MTU is different from path we thought it would
2026 * be when we created chunks, or IP headers have grown.
2027 * Need to clear the DF bit.
2028 */
2029 iph->ipha_fragment_offset_and_flags = 0;
2030 }
2031 fp->sf_rxt_unacked += seglen;
2032
2033 dprint(2, ("sctp_rexmit: Sending packet %d bytes, tsn %x "
2034 "ssn %d to %p (rwnd %d, lastack_rxd %x)\n",
2035 seglen, ntohl(sdc->sdh_tsn), ntohs(sdc->sdh_ssn),
2036 (void *)fp, sctp->sctp_frwnd, sctp->sctp_lastack_rxd));
2037
2038 sctp->sctp_rexmitting = B_TRUE;
2039 sctp->sctp_rxt_nxttsn = first_ua_tsn;
2040 sctp->sctp_rxt_maxtsn = sctp->sctp_ltsn - 1;
2041 sctp_set_iplen(sctp, head, fp->sf_ixa);
2042
2043 DTRACE_SCTP5(send, mblk_t *, NULL, ip_xmit_attr_t *, fp->sf_ixa,
2044 void_ip_t *, mp->b_rptr, sctp_t *, sctp, sctp_hdr_t *,
2045 &mp->b_rptr[fp->sf_ixa->ixa_ip_hdr_length]);
2046
2047 (void) conn_ip_output(head, fp->sf_ixa);
2048 BUMP_LOCAL(sctp->sctp_opkts);
2049
2050 /*
2051 * Restart the oldfp timer with exponential backoff and
2052 * the new fp timer for the retransmitted chunks.
2053 */
2054 restart_timer:
2055 oldfp->sf_strikes++;
2056 sctp->sctp_strikes++;
2057 SCTP_CALC_RXT(sctp, oldfp, sctp->sctp_rto_max);
2058 /*
2059 * If there is still some data in the oldfp, restart the
2060 * retransmission timer. If there is no data, the heartbeat will
2061 * continue to run so it will do its job in checking the reachability
2062 * of the oldfp.
2063 */
2064 if (oldfp != fp && oldfp->sf_suna != 0)
2065 SCTP_FADDR_TIMER_RESTART(sctp, oldfp, oldfp->sf_rto);
2066
2067 /*
2068 * Should we restart the timer of the new fp? If there is
2069 * outstanding data to the new fp, the timer should be
2070 * running already. So restarting it means that the timer
2071 * will fire later for those outstanding data. But if
2072 * we don't restart it, the timer will fire too early for the
2073 * just retransmitted chunks to the new fp. The reason is that we
2074 * don't keep a timestamp on when a chunk is retransmitted.
2075 * So when the timer fires, it will just search for the
2076 * chunk with the earliest TSN sent to new fp. This probably
2077 * is the chunk we just retransmitted. So for now, let's
2078 * be conservative and restart the timer of the new fp.
2079 */
2080 SCTP_FADDR_TIMER_RESTART(sctp, fp, fp->sf_rto);
2081
2082 sctp->sctp_active = ddi_get_lbolt64();
2083 }
2084
2085 /*
2086 * This function is called by sctp_ss_rexmit() to create a packet
2087 * to be retransmitted to the given fp. The given meta and mp
2088 * parameters are respectively the sctp_msg_hdr_t and the mblk of the
2089 * first chunk to be retransmitted. This is also called when we want
2090 * to retransmit a zero window probe from sctp_rexmit() or when we
2091 * want to retransmit the zero window probe after the window has
2092 * opened from sctp_got_sack().
2093 */
2094 mblk_t *
2095 sctp_rexmit_packet(sctp_t *sctp, mblk_t **meta, mblk_t **mp, sctp_faddr_t *fp,
2096 uint_t *packet_len)
2097 {
2098 uint32_t seglen = 0;
2099 uint16_t chunklen;
2100 int extra;
2101 mblk_t *nmp;
2102 mblk_t *head;
2103 mblk_t *fill;
2104 sctp_data_hdr_t *sdc;
2105 sctp_msg_hdr_t *mhdr;
2106
2107 sdc = (sctp_data_hdr_t *)(*mp)->b_rptr;
2108 seglen = ntohs(sdc->sdh_len);
2109 chunklen = seglen - sizeof (*sdc);
2110 if ((extra = seglen & (SCTP_ALIGN - 1)) != 0)
2111 extra = SCTP_ALIGN - extra;
2112
2113 nmp = dupmsg(*mp);
2114 if (nmp == NULL)
2115 return (NULL);
2116 if (extra > 0) {
2117 fill = sctp_get_padding(sctp, extra);
2118 if (fill != NULL) {
2119 linkb(nmp, fill);
2120 seglen += extra;
2121 } else {
2122 freemsg(nmp);
2123 return (NULL);
2124 }
2125 }
2126 SCTP_CHUNK_CLEAR_FLAGS(nmp);
2127 head = sctp_add_proto_hdr(sctp, fp, nmp, 0, NULL);
2128 if (head == NULL) {
2129 freemsg(nmp);
2130 return (NULL);
2131 }
2132 SCTP_CHUNK_SENT(sctp, *mp, sdc, fp, chunklen, *meta);
2133 /*
2134 * Don't update the TSN if we are doing a Zero Win Probe.
2135 */
2136 if (!sctp->sctp_zero_win_probe)
2137 sctp->sctp_rxt_nxttsn = ntohl(sdc->sdh_tsn);
2138 *mp = (*mp)->b_next;
2139
2140 try_bundle:
2141 while (seglen < fp->sf_pmss) {
2142 int32_t new_len;
2143
2144 /*
2145 * Go through the list to find more chunks to be bundled.
2146 * We should only retransmit sent by unack'ed chunks. Since
2147 * they were sent before, the peer's receive window should
2148 * be able to receive them.
2149 */
2150 while (*mp != NULL) {
2151 /* Check if the chunk can be bundled. */
2152 if (SCTP_CHUNK_ISSENT(*mp) && !SCTP_CHUNK_ISACKED(*mp))
2153 break;
2154 *mp = (*mp)->b_next;
2155 }
2156 /* Go to the next message. */
2157 if (*mp == NULL) {
2158 for (*meta = (*meta)->b_next; *meta != NULL;
2159 *meta = (*meta)->b_next) {
2160 mhdr = (sctp_msg_hdr_t *)(*meta)->b_rptr;
2161
2162 if (SCTP_IS_MSG_ABANDONED(*meta) ||
2163 SCTP_MSG_TO_BE_ABANDONED(*meta, mhdr,
2164 sctp)) {
2165 continue;
2166 }
2167
2168 *mp = (*meta)->b_cont;
2169 goto try_bundle;
2170 }
2171 /* No more chunk to be bundled. */
2172 break;
2173 }
2174
2175 sdc = (sctp_data_hdr_t *)(*mp)->b_rptr;
2176 /* Don't bundle chunks beyond sctp_rxt_maxtsn. */
2177 if (SEQ_GT(ntohl(sdc->sdh_tsn), sctp->sctp_rxt_maxtsn))
2178 break;
2179 new_len = ntohs(sdc->sdh_len);
2180 chunklen = new_len - sizeof (*sdc);
2181
2182 if ((extra = new_len & (SCTP_ALIGN - 1)) != 0)
2183 extra = SCTP_ALIGN - extra;
2184 if ((new_len = seglen + new_len + extra) > fp->sf_pmss)
2185 break;
2186 if ((nmp = dupmsg(*mp)) == NULL)
2187 break;
2188
2189 if (extra > 0) {
2190 fill = sctp_get_padding(sctp, extra);
2191 if (fill != NULL) {
2192 linkb(nmp, fill);
2193 } else {
2194 freemsg(nmp);
2195 break;
2196 }
2197 }
2198 linkb(head, nmp);
2199
2200 SCTP_CHUNK_CLEAR_FLAGS(nmp);
2201 SCTP_CHUNK_SENT(sctp, *mp, sdc, fp, chunklen, *meta);
2202 /*
2203 * Don't update the TSN if we are doing a Zero Win Probe.
2204 */
2205 if (!sctp->sctp_zero_win_probe)
2206 sctp->sctp_rxt_nxttsn = ntohl(sdc->sdh_tsn);
2207
2208 seglen = new_len;
2209 *mp = (*mp)->b_next;
2210 }
2211 *packet_len = seglen;
2212 fp->sf_rxt_unacked += seglen;
2213 return (head);
2214 }
2215
2216 /*
2217 * sctp_ss_rexmit() is called when we get a SACK after a timeout which
2218 * advances the cum_tsn but the cum_tsn is still less than what we have sent
2219 * (sctp_rxt_maxtsn) at the time of the timeout. This SACK is a "partial"
2220 * SACK. We retransmit unacked chunks without having to wait for another
2221 * timeout. The rationale is that the SACK should not be "partial" if all the
2222 * lost chunks have been retransmitted. Since the SACK is "partial,"
2223 * the chunks between the cum_tsn and the sctp_rxt_maxtsn should still
2224 * be missing. It is better for us to retransmit them now instead
2225 * of waiting for a timeout.
2226 */
2227 void
2228 sctp_ss_rexmit(sctp_t *sctp)
2229 {
2230 mblk_t *meta;
2231 mblk_t *mp;
2232 mblk_t *pkt;
2233 sctp_faddr_t *fp;
2234 uint_t pkt_len;
2235 uint32_t tot_wnd;
2236 sctp_data_hdr_t *sdc;
2237 int burst;
2238 sctp_stack_t *sctps = sctp->sctp_sctps;
2239
2240 ASSERT(!sctp->sctp_zero_win_probe);
2241
2242 /*
2243 * If the last cum ack is smaller than what we have just
2244 * retransmitted, simply return.
2245 */
2246 if (SEQ_GEQ(sctp->sctp_lastack_rxd, sctp->sctp_rxt_nxttsn))
2247 sctp->sctp_rxt_nxttsn = sctp->sctp_lastack_rxd + 1;
2248 else
2249 return;
2250 ASSERT(SEQ_LEQ(sctp->sctp_rxt_nxttsn, sctp->sctp_rxt_maxtsn));
2251
2252 /*
2253 * After a timer fires, sctp_current should be set to the new
2254 * fp where the retransmitted chunks are sent.
2255 */
2256 fp = sctp->sctp_current;
2257
2258 /*
2259 * Since we are retransmitting, we only need to use cwnd to determine
2260 * how much we can send as we were allowed (by peer's receive window)
2261 * to send those retransmitted chunks previously when they are first
2262 * sent. If we record how much we have retransmitted but
2263 * unacknowledged using rxt_unacked, then the amount we can now send
2264 * is equal to cwnd minus rxt_unacked.
2265 *
2266 * The field rxt_unacked is incremented when we retransmit a packet
2267 * and decremented when we got a SACK acknowledging something. And
2268 * it is reset when the retransmission timer fires as we assume that
2269 * all packets have left the network after a timeout. If this
2270 * assumption is not true, it means that after a timeout, we can
2271 * get a SACK acknowledging more than rxt_unacked (its value only
2272 * contains what is retransmitted when the timer fires). So
2273 * rxt_unacked will become very big (it is an unsiged int so going
2274 * negative means that the value is huge). This is the reason we
2275 * always send at least 1 MSS bytes.
2276 *
2277 * The reason why we do not have an accurate count is that we
2278 * only know how many packets are outstanding (using the TSN numbers).
2279 * But we do not know how many bytes those packets contain. To
2280 * have an accurate count, we need to walk through the send list.
2281 * As it is not really important to have an accurate count during
2282 * retransmission, we skip this walk to save some time. This should
2283 * not make the retransmission too aggressive to cause congestion.
2284 */
2285 if (fp->sf_cwnd <= fp->sf_rxt_unacked)
2286 tot_wnd = fp->sf_pmss;
2287 else
2288 tot_wnd = fp->sf_cwnd - fp->sf_rxt_unacked;
2289
2290 /* Find the first unack'ed chunk */
2291 for (meta = sctp->sctp_xmit_head; meta != NULL; meta = meta->b_next) {
2292 sctp_msg_hdr_t *mhdr = (sctp_msg_hdr_t *)meta->b_rptr;
2293
2294 if (SCTP_IS_MSG_ABANDONED(meta) ||
2295 SCTP_MSG_TO_BE_ABANDONED(meta, mhdr, sctp)) {
2296 continue;
2297 }
2298
2299 for (mp = meta->b_cont; mp != NULL; mp = mp->b_next) {
2300 /* Again, this may not be possible */
2301 if (!SCTP_CHUNK_ISSENT(mp))
2302 return;
2303 sdc = (sctp_data_hdr_t *)mp->b_rptr;
2304 if (ntohl(sdc->sdh_tsn) == sctp->sctp_rxt_nxttsn)
2305 goto found_msg;
2306 }
2307 }
2308
2309 /* Everything is abandoned... */
2310 return;
2311
2312 found_msg:
2313 if (!fp->sf_timer_running)
2314 SCTP_FADDR_TIMER_RESTART(sctp, fp, fp->sf_rto);
2315 pkt = sctp_rexmit_packet(sctp, &meta, &mp, fp, &pkt_len);
2316 if (pkt == NULL) {
2317 SCTP_KSTAT(sctps, sctp_ss_rexmit_failed);
2318 return;
2319 }
2320 if ((pkt_len > fp->sf_pmss) && fp->sf_isv4) {
2321 ipha_t *iph = (ipha_t *)pkt->b_rptr;
2322
2323 /*
2324 * Path MTU is different from path we thought it would
2325 * be when we created chunks, or IP headers have grown.
2326 * Need to clear the DF bit.
2327 */
2328 iph->ipha_fragment_offset_and_flags = 0;
2329 }
2330 sctp_set_iplen(sctp, pkt, fp->sf_ixa);
2331
2332 DTRACE_SCTP5(send, mblk_t *, NULL, ip_xmit_attr_t *, fp->sf_ixa,
2333 void_ip_t *, mp->b_rptr, sctp_t *, sctp, sctp_hdr_t *,
2334 &mp->b_rptr[fp->sf_ixa->ixa_ip_hdr_length]);
2335
2336 (void) conn_ip_output(pkt, fp->sf_ixa);
2337 BUMP_LOCAL(sctp->sctp_opkts);
2338
2339 /* Check and see if there is more chunk to be retransmitted. */
2340 if (tot_wnd <= pkt_len || tot_wnd - pkt_len < fp->sf_pmss ||
2341 meta == NULL)
2342 return;
2343 if (mp == NULL)
2344 meta = meta->b_next;
2345 if (meta == NULL)
2346 return;
2347
2348 /* Retransmit another packet if the window allows. */
2349 for (tot_wnd -= pkt_len, burst = sctps->sctps_maxburst - 1;
2350 meta != NULL && burst > 0; meta = meta->b_next, burst--) {
2351 if (mp == NULL)
2352 mp = meta->b_cont;
2353 for (; mp != NULL; mp = mp->b_next) {
2354 /* Again, this may not be possible */
2355 if (!SCTP_CHUNK_ISSENT(mp))
2356 return;
2357 if (!SCTP_CHUNK_ISACKED(mp))
2358 goto found_msg;
2359 }
2360 }
2361 }