1 /* SCTP kernel implementation
2 * (C) Copyright IBM Corp. 2001, 2004
3 * Copyright (c) 1999-2000 Cisco, Inc.
4 * Copyright (c) 1999-2001 Motorola, Inc.
6 * This file is part of the SCTP kernel implementation
8 * These functions handle output processing.
10 * This SCTP implementation is free software;
11 * you can redistribute it and/or modify it under the terms of
12 * the GNU General Public License as published by
13 * the Free Software Foundation; either version 2, or (at your option)
16 * This SCTP implementation is distributed in the hope that it
17 * will be useful, but WITHOUT ANY WARRANTY; without even the implied
18 * ************************
19 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
20 * See the GNU General Public License for more details.
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.
27 * Please send any bug reports or fixes you make to the
29 * lksctp developers <lksctp-developers@lists.sourceforge.net>
31 * Or submit a bug report through the following website:
32 * http://www.sf.net/projects/lksctp
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>
40 * Any bugs reported given to us we will try to fix... any fixes shared will
41 * be incorporated into the next SCTP release.
44 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
46 #include <linux/types.h>
47 #include <linux/kernel.h>
48 #include <linux/wait.h>
49 #include <linux/time.h>
51 #include <linux/ipv6.h>
52 #include <linux/init.h>
53 #include <linux/slab.h>
54 #include <net/inet_ecn.h>
57 #include <net/net_namespace.h>
59 #include <linux/socket.h> /* for sa_family_t */
62 #include <net/sctp/sctp.h>
63 #include <net/sctp/sm.h>
64 #include <net/sctp/checksum.h>
66 /* Forward declarations for private helpers. */
67 static sctp_xmit_t
sctp_packet_can_append_data(struct sctp_packet
*packet
,
68 struct sctp_chunk
*chunk
);
69 static void sctp_packet_append_data(struct sctp_packet
*packet
,
70 struct sctp_chunk
*chunk
);
71 static sctp_xmit_t
sctp_packet_will_fit(struct sctp_packet
*packet
,
72 struct sctp_chunk
*chunk
,
75 static void sctp_packet_reset(struct sctp_packet
*packet
)
77 packet
->size
= packet
->overhead
;
78 packet
->has_cookie_echo
= 0;
87 * This appears to be a followup set of initializations.
89 struct sctp_packet
*sctp_packet_config(struct sctp_packet
*packet
,
90 __u32 vtag
, int ecn_capable
)
92 struct sctp_chunk
*chunk
= NULL
;
94 SCTP_DEBUG_PRINTK("%s: packet:%p vtag:0x%x\n", __func__
,
99 if (ecn_capable
&& sctp_packet_empty(packet
)) {
100 chunk
= sctp_get_ecne_prepend(packet
->transport
->asoc
);
102 /* If there a is a prepend chunk stick it on the list before
103 * any other chunks get appended.
106 sctp_packet_append_chunk(packet
, chunk
);
112 /* Initialize the packet structure. */
113 struct sctp_packet
*sctp_packet_init(struct sctp_packet
*packet
,
114 struct sctp_transport
*transport
,
115 __u16 sport
, __u16 dport
)
117 struct sctp_association
*asoc
= transport
->asoc
;
120 SCTP_DEBUG_PRINTK("%s: packet:%p transport:%p\n", __func__
,
123 packet
->transport
= transport
;
124 packet
->source_port
= sport
;
125 packet
->destination_port
= dport
;
126 INIT_LIST_HEAD(&packet
->chunk_list
);
128 struct sctp_sock
*sp
= sctp_sk(asoc
->base
.sk
);
129 overhead
= sp
->pf
->af
->net_header_len
;
131 overhead
= sizeof(struct ipv6hdr
);
133 overhead
+= sizeof(struct sctphdr
);
134 packet
->overhead
= overhead
;
135 sctp_packet_reset(packet
);
137 packet
->malloced
= 0;
142 void sctp_packet_free(struct sctp_packet
*packet
)
144 struct sctp_chunk
*chunk
, *tmp
;
146 SCTP_DEBUG_PRINTK("%s: packet:%p\n", __func__
, packet
);
148 list_for_each_entry_safe(chunk
, tmp
, &packet
->chunk_list
, list
) {
149 list_del_init(&chunk
->list
);
150 sctp_chunk_free(chunk
);
153 if (packet
->malloced
)
157 /* This routine tries to append the chunk to the offered packet. If adding
158 * the chunk causes the packet to exceed the path MTU and COOKIE_ECHO chunk
159 * is not present in the packet, it transmits the input packet.
160 * Data can be bundled with a packet containing a COOKIE_ECHO chunk as long
161 * as it can fit in the packet, but any more data that does not fit in this
162 * packet can be sent only after receiving the COOKIE_ACK.
164 sctp_xmit_t
sctp_packet_transmit_chunk(struct sctp_packet
*packet
,
165 struct sctp_chunk
*chunk
,
171 SCTP_DEBUG_PRINTK("%s: packet:%p chunk:%p\n", __func__
,
174 switch ((retval
= (sctp_packet_append_chunk(packet
, chunk
)))) {
175 case SCTP_XMIT_PMTU_FULL
:
176 if (!packet
->has_cookie_echo
) {
177 error
= sctp_packet_transmit(packet
);
179 chunk
->skb
->sk
->sk_err
= -error
;
181 /* If we have an empty packet, then we can NOT ever
185 retval
= sctp_packet_append_chunk(packet
,
190 case SCTP_XMIT_RWND_FULL
:
192 case SCTP_XMIT_NAGLE_DELAY
:
199 /* Try to bundle an auth chunk into the packet. */
200 static sctp_xmit_t
sctp_packet_bundle_auth(struct sctp_packet
*pkt
,
201 struct sctp_chunk
*chunk
)
203 struct sctp_association
*asoc
= pkt
->transport
->asoc
;
204 struct sctp_chunk
*auth
;
205 sctp_xmit_t retval
= SCTP_XMIT_OK
;
207 /* if we don't have an association, we can't do authentication */
211 /* See if this is an auth chunk we are bundling or if
212 * auth is already bundled.
214 if (chunk
->chunk_hdr
->type
== SCTP_CID_AUTH
|| pkt
->has_auth
)
217 /* if the peer did not request this chunk to be authenticated,
223 auth
= sctp_make_auth(asoc
);
227 retval
= sctp_packet_append_chunk(pkt
, auth
);
232 /* Try to bundle a SACK with the packet. */
233 static sctp_xmit_t
sctp_packet_bundle_sack(struct sctp_packet
*pkt
,
234 struct sctp_chunk
*chunk
)
236 sctp_xmit_t retval
= SCTP_XMIT_OK
;
238 /* If sending DATA and haven't aleady bundled a SACK, try to
239 * bundle one in to the packet.
241 if (sctp_chunk_is_data(chunk
) && !pkt
->has_sack
&&
242 !pkt
->has_cookie_echo
) {
243 struct sctp_association
*asoc
;
244 struct timer_list
*timer
;
245 asoc
= pkt
->transport
->asoc
;
246 timer
= &asoc
->timers
[SCTP_EVENT_TIMEOUT_SACK
];
248 /* If the SACK timer is running, we have a pending SACK */
249 if (timer_pending(timer
)) {
250 struct sctp_chunk
*sack
;
252 if (pkt
->transport
->sack_generation
!=
253 pkt
->transport
->asoc
->peer
.sack_generation
)
256 asoc
->a_rwnd
= asoc
->rwnd
;
257 sack
= sctp_make_sack(asoc
);
259 retval
= sctp_packet_append_chunk(pkt
, sack
);
260 asoc
->peer
.sack_needed
= 0;
261 if (del_timer(timer
))
262 sctp_association_put(asoc
);
269 /* Append a chunk to the offered packet reporting back any inability to do
272 sctp_xmit_t
sctp_packet_append_chunk(struct sctp_packet
*packet
,
273 struct sctp_chunk
*chunk
)
275 sctp_xmit_t retval
= SCTP_XMIT_OK
;
276 __u16 chunk_len
= WORD_ROUND(ntohs(chunk
->chunk_hdr
->length
));
278 SCTP_DEBUG_PRINTK("%s: packet:%p chunk:%p\n", __func__
, packet
,
281 /* Data chunks are special. Before seeing what else we can
282 * bundle into this packet, check to see if we are allowed to
285 if (sctp_chunk_is_data(chunk
)) {
286 retval
= sctp_packet_can_append_data(packet
, chunk
);
287 if (retval
!= SCTP_XMIT_OK
)
291 /* Try to bundle AUTH chunk */
292 retval
= sctp_packet_bundle_auth(packet
, chunk
);
293 if (retval
!= SCTP_XMIT_OK
)
296 /* Try to bundle SACK chunk */
297 retval
= sctp_packet_bundle_sack(packet
, chunk
);
298 if (retval
!= SCTP_XMIT_OK
)
301 /* Check to see if this chunk will fit into the packet */
302 retval
= sctp_packet_will_fit(packet
, chunk
, chunk_len
);
303 if (retval
!= SCTP_XMIT_OK
)
306 /* We believe that this chunk is OK to add to the packet */
307 switch (chunk
->chunk_hdr
->type
) {
309 /* Account for the data being in the packet */
310 sctp_packet_append_data(packet
, chunk
);
311 /* Disallow SACK bundling after DATA. */
312 packet
->has_sack
= 1;
313 /* Disallow AUTH bundling after DATA */
314 packet
->has_auth
= 1;
315 /* Let it be knows that packet has DATA in it */
316 packet
->has_data
= 1;
317 /* timestamp the chunk for rtx purposes */
318 chunk
->sent_at
= jiffies
;
320 case SCTP_CID_COOKIE_ECHO
:
321 packet
->has_cookie_echo
= 1;
325 packet
->has_sack
= 1;
329 packet
->has_auth
= 1;
330 packet
->auth
= chunk
;
334 /* It is OK to send this chunk. */
335 list_add_tail(&chunk
->list
, &packet
->chunk_list
);
336 packet
->size
+= chunk_len
;
337 chunk
->transport
= packet
->transport
;
342 /* All packets are sent to the network through this function from
345 * The return value is a normal kernel error return value.
347 int sctp_packet_transmit(struct sctp_packet
*packet
)
349 struct sctp_transport
*tp
= packet
->transport
;
350 struct sctp_association
*asoc
= tp
->asoc
;
352 struct sk_buff
*nskb
;
353 struct sctp_chunk
*chunk
, *tmp
;
356 int padding
; /* How much padding do we need? */
358 struct dst_entry
*dst
= tp
->dst
;
359 unsigned char *auth
= NULL
; /* pointer to auth in skb data */
360 __u32 cksum_buf_len
= sizeof(struct sctphdr
);
362 SCTP_DEBUG_PRINTK("%s: packet:%p\n", __func__
, packet
);
364 /* Do NOT generate a chunkless packet. */
365 if (list_empty(&packet
->chunk_list
))
368 /* Set up convenience variables... */
369 chunk
= list_entry(packet
->chunk_list
.next
, struct sctp_chunk
, list
);
372 /* Allocate the new skb. */
373 nskb
= alloc_skb(packet
->size
+ LL_MAX_HEADER
, GFP_ATOMIC
);
377 /* Make sure the outbound skb has enough header room reserved. */
378 skb_reserve(nskb
, packet
->overhead
+ LL_MAX_HEADER
);
380 /* Set the owning socket so that we know where to get the
381 * destination IP address.
383 skb_set_owner_w(nskb
, sk
);
385 if (!sctp_transport_dst_check(tp
)) {
386 sctp_transport_route(tp
, NULL
, sctp_sk(sk
));
387 if (asoc
&& (asoc
->param_flags
& SPP_PMTUD_ENABLE
)) {
388 sctp_assoc_sync_pmtu(asoc
);
391 dst
= dst_clone(tp
->dst
);
392 skb_dst_set(nskb
, dst
);
396 /* Build the SCTP header. */
397 sh
= (struct sctphdr
*)skb_push(nskb
, sizeof(struct sctphdr
));
398 skb_reset_transport_header(nskb
);
399 sh
->source
= htons(packet
->source_port
);
400 sh
->dest
= htons(packet
->destination_port
);
402 /* From 6.8 Adler-32 Checksum Calculation:
403 * After the packet is constructed (containing the SCTP common
404 * header and one or more control or DATA chunks), the
407 * 1) Fill in the proper Verification Tag in the SCTP common
408 * header and initialize the checksum field to 0's.
410 sh
->vtag
= htonl(packet
->vtag
);
416 * An endpoint bundles chunks by simply including multiple
417 * chunks in one outbound SCTP packet. ...
421 * 3.2 Chunk Field Descriptions
423 * The total length of a chunk (including Type, Length and
424 * Value fields) MUST be a multiple of 4 bytes. If the length
425 * of the chunk is not a multiple of 4 bytes, the sender MUST
426 * pad the chunk with all zero bytes and this padding is not
427 * included in the chunk length field. The sender should
428 * never pad with more than 3 bytes.
430 * [This whole comment explains WORD_ROUND() below.]
432 SCTP_DEBUG_PRINTK("***sctp_transmit_packet***\n");
433 list_for_each_entry_safe(chunk
, tmp
, &packet
->chunk_list
, list
) {
434 list_del_init(&chunk
->list
);
435 if (sctp_chunk_is_data(chunk
)) {
436 /* 6.3.1 C4) When data is in flight and when allowed
437 * by rule C5, a new RTT measurement MUST be made each
438 * round trip. Furthermore, new RTT measurements
439 * SHOULD be made no more than once per round-trip
440 * for a given destination transport address.
443 if (!tp
->rto_pending
) {
444 chunk
->rtt_in_progress
= 1;
450 padding
= WORD_ROUND(chunk
->skb
->len
) - chunk
->skb
->len
;
452 memset(skb_put(chunk
->skb
, padding
), 0, padding
);
454 /* if this is the auth chunk that we are adding,
455 * store pointer where it will be added and put
456 * the auth into the packet.
458 if (chunk
== packet
->auth
)
459 auth
= skb_tail_pointer(nskb
);
461 cksum_buf_len
+= chunk
->skb
->len
;
462 memcpy(skb_put(nskb
, chunk
->skb
->len
),
463 chunk
->skb
->data
, chunk
->skb
->len
);
465 SCTP_DEBUG_PRINTK("%s %p[%s] %s 0x%x, %s %d, %s %d, %s %d\n",
467 sctp_cname(SCTP_ST_CHUNK(
468 chunk
->chunk_hdr
->type
)),
469 chunk
->has_tsn
? "TSN" : "No TSN",
471 ntohl(chunk
->subh
.data_hdr
->tsn
) : 0,
472 "length", ntohs(chunk
->chunk_hdr
->length
),
473 "chunk->skb->len", chunk
->skb
->len
,
474 "rtt_in_progress", chunk
->rtt_in_progress
);
477 * If this is a control chunk, this is our last
478 * reference. Free data chunks after they've been
479 * acknowledged or have failed.
481 if (!sctp_chunk_is_data(chunk
))
482 sctp_chunk_free(chunk
);
485 /* SCTP-AUTH, Section 6.2
486 * The sender MUST calculate the MAC as described in RFC2104 [2]
487 * using the hash function H as described by the MAC Identifier and
488 * the shared association key K based on the endpoint pair shared key
489 * described by the shared key identifier. The 'data' used for the
490 * computation of the AUTH-chunk is given by the AUTH chunk with its
491 * HMAC field set to zero (as shown in Figure 6) followed by all
492 * chunks that are placed after the AUTH chunk in the SCTP packet.
495 sctp_auth_calculate_hmac(asoc
, nskb
,
496 (struct sctp_auth_chunk
*)auth
,
499 /* 2) Calculate the Adler-32 checksum of the whole packet,
500 * including the SCTP common header and all the
503 * Note: Adler-32 is no longer applicable, as has been replaced
504 * by CRC32-C as described in <draft-ietf-tsvwg-sctpcsum-02.txt>.
506 if (!sctp_checksum_disable
) {
507 if (!(dst
->dev
->features
& NETIF_F_SCTP_CSUM
)) {
508 __u32 crc32
= sctp_start_cksum((__u8
*)sh
, cksum_buf_len
);
510 /* 3) Put the resultant value into the checksum field in the
511 * common header, and leave the rest of the bits unchanged.
513 sh
->checksum
= sctp_end_cksum(crc32
);
515 /* no need to seed pseudo checksum for SCTP */
516 nskb
->ip_summed
= CHECKSUM_PARTIAL
;
517 nskb
->csum_start
= (skb_transport_header(nskb
) -
519 nskb
->csum_offset
= offsetof(struct sctphdr
, checksum
);
523 /* IP layer ECN support
525 * "The ECN-Capable Transport (ECT) bit would be set by the
526 * data sender to indicate that the end-points of the
527 * transport protocol are ECN-capable."
529 * Now setting the ECT bit all the time, as it should not cause
530 * any problems protocol-wise even if our peer ignores it.
532 * Note: The works for IPv6 layer checks this bit too later
533 * in transmission. See IP6_ECN_flow_xmit().
535 (*tp
->af_specific
->ecn_capable
)(nskb
->sk
);
537 /* Set up the IP options. */
538 /* BUG: not implemented
539 * For v4 this all lives somewhere in sk->sk_opt...
542 /* Dump that on IP! */
543 if (asoc
&& asoc
->peer
.last_sent_to
!= tp
) {
544 /* Considering the multiple CPU scenario, this is a
545 * "correcter" place for last_sent_to. --xguo
547 asoc
->peer
.last_sent_to
= tp
;
551 struct timer_list
*timer
;
552 unsigned long timeout
;
554 /* Restart the AUTOCLOSE timer when sending data. */
555 if (sctp_state(asoc
, ESTABLISHED
) && asoc
->autoclose
) {
556 timer
= &asoc
->timers
[SCTP_EVENT_TIMEOUT_AUTOCLOSE
];
557 timeout
= asoc
->timeouts
[SCTP_EVENT_TIMEOUT_AUTOCLOSE
];
559 if (!mod_timer(timer
, jiffies
+ timeout
))
560 sctp_association_hold(asoc
);
564 SCTP_DEBUG_PRINTK("***sctp_transmit_packet*** skb len %d\n",
567 nskb
->local_df
= packet
->ipfragok
;
568 (*tp
->af_specific
->sctp_xmit
)(nskb
, tp
);
571 sctp_packet_reset(packet
);
575 IP_INC_STATS_BH(&init_net
, IPSTATS_MIB_OUTNOROUTES
);
577 /* FIXME: Returning the 'err' will effect all the associations
578 * associated with a socket, although only one of the paths of the
579 * association is unreachable.
580 * The real failure of a transport or association can be passed on
581 * to the user via notifications. So setting this error may not be
584 /* err = -EHOSTUNREACH; */
586 /* Control chunks are unreliable so just drop them. DATA chunks
587 * will get resent or dropped later.
590 list_for_each_entry_safe(chunk
, tmp
, &packet
->chunk_list
, list
) {
591 list_del_init(&chunk
->list
);
592 if (!sctp_chunk_is_data(chunk
))
593 sctp_chunk_free(chunk
);
601 /********************************************************************
602 * 2nd Level Abstractions
603 ********************************************************************/
605 /* This private function check to see if a chunk can be added */
606 static sctp_xmit_t
sctp_packet_can_append_data(struct sctp_packet
*packet
,
607 struct sctp_chunk
*chunk
)
609 sctp_xmit_t retval
= SCTP_XMIT_OK
;
610 size_t datasize
, rwnd
, inflight
, flight_size
;
611 struct sctp_transport
*transport
= packet
->transport
;
612 struct sctp_association
*asoc
= transport
->asoc
;
613 struct sctp_outq
*q
= &asoc
->outqueue
;
615 /* RFC 2960 6.1 Transmission of DATA Chunks
617 * A) At any given time, the data sender MUST NOT transmit new data to
618 * any destination transport address if its peer's rwnd indicates
619 * that the peer has no buffer space (i.e. rwnd is 0, see Section
620 * 6.2.1). However, regardless of the value of rwnd (including if it
621 * is 0), the data sender can always have one DATA chunk in flight to
622 * the receiver if allowed by cwnd (see rule B below). This rule
623 * allows the sender to probe for a change in rwnd that the sender
624 * missed due to the SACK having been lost in transit from the data
625 * receiver to the data sender.
628 rwnd
= asoc
->peer
.rwnd
;
629 inflight
= q
->outstanding_bytes
;
630 flight_size
= transport
->flight_size
;
632 datasize
= sctp_data_size(chunk
);
634 if (datasize
> rwnd
) {
636 /* We have (at least) one data chunk in flight,
637 * so we can't fall back to rule 6.1 B).
639 retval
= SCTP_XMIT_RWND_FULL
;
644 /* RFC 2960 6.1 Transmission of DATA Chunks
646 * B) At any given time, the sender MUST NOT transmit new data
647 * to a given transport address if it has cwnd or more bytes
648 * of data outstanding to that transport address.
650 /* RFC 7.2.4 & the Implementers Guide 2.8.
653 * When a Fast Retransmit is being performed the sender SHOULD
654 * ignore the value of cwnd and SHOULD NOT delay retransmission.
656 if (chunk
->fast_retransmit
!= SCTP_NEED_FRTX
)
657 if (flight_size
>= transport
->cwnd
) {
658 retval
= SCTP_XMIT_RWND_FULL
;
662 /* Nagle's algorithm to solve small-packet problem:
663 * Inhibit the sending of new chunks when new outgoing data arrives
664 * if any previously transmitted data on the connection remains
667 if (!sctp_sk(asoc
->base
.sk
)->nodelay
&& sctp_packet_empty(packet
) &&
668 inflight
&& sctp_state(asoc
, ESTABLISHED
)) {
669 unsigned int max
= transport
->pathmtu
- packet
->overhead
;
670 unsigned int len
= chunk
->skb
->len
+ q
->out_qlen
;
672 /* Check whether this chunk and all the rest of pending
673 * data will fit or delay in hopes of bundling a full
675 * Don't delay large message writes that may have been
676 * fragmeneted into small peices.
678 if ((len
< max
) && chunk
->msg
->can_delay
) {
679 retval
= SCTP_XMIT_NAGLE_DELAY
;
688 /* This private function does management things when adding DATA chunk */
689 static void sctp_packet_append_data(struct sctp_packet
*packet
,
690 struct sctp_chunk
*chunk
)
692 struct sctp_transport
*transport
= packet
->transport
;
693 size_t datasize
= sctp_data_size(chunk
);
694 struct sctp_association
*asoc
= transport
->asoc
;
695 u32 rwnd
= asoc
->peer
.rwnd
;
697 /* Keep track of how many bytes are in flight over this transport. */
698 transport
->flight_size
+= datasize
;
700 /* Keep track of how many bytes are in flight to the receiver. */
701 asoc
->outqueue
.outstanding_bytes
+= datasize
;
703 /* Update our view of the receiver's rwnd. */
709 asoc
->peer
.rwnd
= rwnd
;
710 /* Has been accepted for transmission. */
711 if (!asoc
->peer
.prsctp_capable
)
712 chunk
->msg
->can_abandon
= 0;
713 sctp_chunk_assign_tsn(chunk
);
714 sctp_chunk_assign_ssn(chunk
);
717 static sctp_xmit_t
sctp_packet_will_fit(struct sctp_packet
*packet
,
718 struct sctp_chunk
*chunk
,
724 sctp_xmit_t retval
= SCTP_XMIT_OK
;
726 psize
= packet
->size
;
727 pmtu
= ((packet
->transport
->asoc
) ?
728 (packet
->transport
->asoc
->pathmtu
) :
729 (packet
->transport
->pathmtu
));
731 too_big
= (psize
+ chunk_len
> pmtu
);
733 /* Decide if we need to fragment or resubmit later. */
735 /* It's OK to fragmet at IP level if any one of the following
737 * 1. The packet is empty (meaning this chunk is greater
739 * 2. The chunk we are adding is a control chunk
740 * 3. The packet doesn't have any data in it yet and data
741 * requires authentication.
743 if (sctp_packet_empty(packet
) || !sctp_chunk_is_data(chunk
) ||
744 (!packet
->has_data
&& chunk
->auth
)) {
745 /* We no longer do re-fragmentation.
746 * Just fragment at the IP layer, if we
747 * actually hit this condition
749 packet
->ipfragok
= 1;
751 retval
= SCTP_XMIT_PMTU_FULL
;