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_append_chunk(struct sctp_packet
*packet
,
68 struct sctp_chunk
*chunk
);
69 static sctp_xmit_t
sctp_packet_can_append_data(struct sctp_packet
*packet
,
70 struct sctp_chunk
*chunk
);
71 static void sctp_packet_append_data(struct sctp_packet
*packet
,
72 struct sctp_chunk
*chunk
);
73 static sctp_xmit_t
sctp_packet_will_fit(struct sctp_packet
*packet
,
74 struct sctp_chunk
*chunk
,
77 static void sctp_packet_reset(struct sctp_packet
*packet
)
79 packet
->size
= packet
->overhead
;
80 packet
->has_cookie_echo
= 0;
89 * This appears to be a followup set of initializations.
91 struct sctp_packet
*sctp_packet_config(struct sctp_packet
*packet
,
92 __u32 vtag
, int ecn_capable
)
94 struct sctp_chunk
*chunk
= NULL
;
96 SCTP_DEBUG_PRINTK("%s: packet:%p vtag:0x%x\n", __func__
,
101 if (ecn_capable
&& sctp_packet_empty(packet
)) {
102 chunk
= sctp_get_ecne_prepend(packet
->transport
->asoc
);
104 /* If there a is a prepend chunk stick it on the list before
105 * any other chunks get appended.
108 sctp_packet_append_chunk(packet
, chunk
);
114 /* Initialize the packet structure. */
115 struct sctp_packet
*sctp_packet_init(struct sctp_packet
*packet
,
116 struct sctp_transport
*transport
,
117 __u16 sport
, __u16 dport
)
119 struct sctp_association
*asoc
= transport
->asoc
;
122 SCTP_DEBUG_PRINTK("%s: packet:%p transport:%p\n", __func__
,
125 packet
->transport
= transport
;
126 packet
->source_port
= sport
;
127 packet
->destination_port
= dport
;
128 INIT_LIST_HEAD(&packet
->chunk_list
);
130 struct sctp_sock
*sp
= sctp_sk(asoc
->base
.sk
);
131 overhead
= sp
->pf
->af
->net_header_len
;
133 overhead
= sizeof(struct ipv6hdr
);
135 overhead
+= sizeof(struct sctphdr
);
136 packet
->overhead
= overhead
;
137 sctp_packet_reset(packet
);
139 packet
->malloced
= 0;
144 void sctp_packet_free(struct sctp_packet
*packet
)
146 struct sctp_chunk
*chunk
, *tmp
;
148 SCTP_DEBUG_PRINTK("%s: packet:%p\n", __func__
, packet
);
150 list_for_each_entry_safe(chunk
, tmp
, &packet
->chunk_list
, list
) {
151 list_del_init(&chunk
->list
);
152 sctp_chunk_free(chunk
);
155 if (packet
->malloced
)
159 /* This routine tries to append the chunk to the offered packet. If adding
160 * the chunk causes the packet to exceed the path MTU and COOKIE_ECHO chunk
161 * is not present in the packet, it transmits the input packet.
162 * Data can be bundled with a packet containing a COOKIE_ECHO chunk as long
163 * as it can fit in the packet, but any more data that does not fit in this
164 * packet can be sent only after receiving the COOKIE_ACK.
166 sctp_xmit_t
sctp_packet_transmit_chunk(struct sctp_packet
*packet
,
167 struct sctp_chunk
*chunk
,
173 SCTP_DEBUG_PRINTK("%s: packet:%p chunk:%p\n", __func__
,
176 switch ((retval
= (sctp_packet_append_chunk(packet
, chunk
)))) {
177 case SCTP_XMIT_PMTU_FULL
:
178 if (!packet
->has_cookie_echo
) {
179 error
= sctp_packet_transmit(packet
);
181 chunk
->skb
->sk
->sk_err
= -error
;
183 /* If we have an empty packet, then we can NOT ever
187 retval
= sctp_packet_append_chunk(packet
,
192 case SCTP_XMIT_RWND_FULL
:
194 case SCTP_XMIT_NAGLE_DELAY
:
201 /* Try to bundle an auth chunk into the packet. */
202 static sctp_xmit_t
sctp_packet_bundle_auth(struct sctp_packet
*pkt
,
203 struct sctp_chunk
*chunk
)
205 struct sctp_association
*asoc
= pkt
->transport
->asoc
;
206 struct sctp_chunk
*auth
;
207 sctp_xmit_t retval
= SCTP_XMIT_OK
;
209 /* if we don't have an association, we can't do authentication */
213 /* See if this is an auth chunk we are bundling or if
214 * auth is already bundled.
216 if (chunk
->chunk_hdr
->type
== SCTP_CID_AUTH
|| pkt
->has_auth
)
219 /* if the peer did not request this chunk to be authenticated,
225 auth
= sctp_make_auth(asoc
);
229 retval
= __sctp_packet_append_chunk(pkt
, auth
);
231 if (retval
!= SCTP_XMIT_OK
)
232 sctp_chunk_free(auth
);
237 /* Try to bundle a SACK with the packet. */
238 static sctp_xmit_t
sctp_packet_bundle_sack(struct sctp_packet
*pkt
,
239 struct sctp_chunk
*chunk
)
241 sctp_xmit_t retval
= SCTP_XMIT_OK
;
243 /* If sending DATA and haven't aleady bundled a SACK, try to
244 * bundle one in to the packet.
246 if (sctp_chunk_is_data(chunk
) && !pkt
->has_sack
&&
247 !pkt
->has_cookie_echo
) {
248 struct sctp_association
*asoc
;
249 struct timer_list
*timer
;
250 asoc
= pkt
->transport
->asoc
;
251 timer
= &asoc
->timers
[SCTP_EVENT_TIMEOUT_SACK
];
253 /* If the SACK timer is running, we have a pending SACK */
254 if (timer_pending(timer
)) {
255 struct sctp_chunk
*sack
;
257 if (pkt
->transport
->sack_generation
!=
258 pkt
->transport
->asoc
->peer
.sack_generation
)
261 asoc
->a_rwnd
= asoc
->rwnd
;
262 sack
= sctp_make_sack(asoc
);
264 retval
= __sctp_packet_append_chunk(pkt
, sack
);
265 if (retval
!= SCTP_XMIT_OK
) {
266 sctp_chunk_free(sack
);
269 asoc
->peer
.sack_needed
= 0;
270 if (del_timer(timer
))
271 sctp_association_put(asoc
);
280 /* Append a chunk to the offered packet reporting back any inability to do
283 static sctp_xmit_t
__sctp_packet_append_chunk(struct sctp_packet
*packet
,
284 struct sctp_chunk
*chunk
)
286 sctp_xmit_t retval
= SCTP_XMIT_OK
;
287 __u16 chunk_len
= WORD_ROUND(ntohs(chunk
->chunk_hdr
->length
));
289 /* Check to see if this chunk will fit into the packet */
290 retval
= sctp_packet_will_fit(packet
, chunk
, chunk_len
);
291 if (retval
!= SCTP_XMIT_OK
)
294 /* We believe that this chunk is OK to add to the packet */
295 switch (chunk
->chunk_hdr
->type
) {
297 /* Account for the data being in the packet */
298 sctp_packet_append_data(packet
, chunk
);
299 /* Disallow SACK bundling after DATA. */
300 packet
->has_sack
= 1;
301 /* Disallow AUTH bundling after DATA */
302 packet
->has_auth
= 1;
303 /* Let it be knows that packet has DATA in it */
304 packet
->has_data
= 1;
305 /* timestamp the chunk for rtx purposes */
306 chunk
->sent_at
= jiffies
;
308 case SCTP_CID_COOKIE_ECHO
:
309 packet
->has_cookie_echo
= 1;
313 packet
->has_sack
= 1;
317 packet
->has_auth
= 1;
318 packet
->auth
= chunk
;
322 /* It is OK to send this chunk. */
323 list_add_tail(&chunk
->list
, &packet
->chunk_list
);
324 packet
->size
+= chunk_len
;
325 chunk
->transport
= packet
->transport
;
330 /* Append a chunk to the offered packet reporting back any inability to do
333 sctp_xmit_t
sctp_packet_append_chunk(struct sctp_packet
*packet
,
334 struct sctp_chunk
*chunk
)
336 sctp_xmit_t retval
= SCTP_XMIT_OK
;
338 SCTP_DEBUG_PRINTK("%s: packet:%p chunk:%p\n", __func__
, packet
,
341 /* Data chunks are special. Before seeing what else we can
342 * bundle into this packet, check to see if we are allowed to
345 if (sctp_chunk_is_data(chunk
)) {
346 retval
= sctp_packet_can_append_data(packet
, chunk
);
347 if (retval
!= SCTP_XMIT_OK
)
351 /* Try to bundle AUTH chunk */
352 retval
= sctp_packet_bundle_auth(packet
, chunk
);
353 if (retval
!= SCTP_XMIT_OK
)
356 /* Try to bundle SACK chunk */
357 retval
= sctp_packet_bundle_sack(packet
, chunk
);
358 if (retval
!= SCTP_XMIT_OK
)
361 retval
= __sctp_packet_append_chunk(packet
, chunk
);
367 static void sctp_packet_release_owner(struct sk_buff
*skb
)
372 static void sctp_packet_set_owner_w(struct sk_buff
*skb
, struct sock
*sk
)
376 skb
->destructor
= sctp_packet_release_owner
;
379 * The data chunks have already been accounted for in sctp_sendmsg(),
380 * therefore only reserve a single byte to keep socket around until
381 * the packet has been transmitted.
383 atomic_inc(&sk
->sk_wmem_alloc
);
386 /* All packets are sent to the network through this function from
389 * The return value is a normal kernel error return value.
391 int sctp_packet_transmit(struct sctp_packet
*packet
)
393 struct sctp_transport
*tp
= packet
->transport
;
394 struct sctp_association
*asoc
= tp
->asoc
;
396 struct sk_buff
*nskb
;
397 struct sctp_chunk
*chunk
, *tmp
;
400 int padding
; /* How much padding do we need? */
402 struct dst_entry
*dst
= tp
->dst
;
403 unsigned char *auth
= NULL
; /* pointer to auth in skb data */
404 __u32 cksum_buf_len
= sizeof(struct sctphdr
);
406 SCTP_DEBUG_PRINTK("%s: packet:%p\n", __func__
, packet
);
408 /* Do NOT generate a chunkless packet. */
409 if (list_empty(&packet
->chunk_list
))
412 /* Set up convenience variables... */
413 chunk
= list_entry(packet
->chunk_list
.next
, struct sctp_chunk
, list
);
416 /* Allocate the new skb. */
417 nskb
= alloc_skb(packet
->size
+ LL_MAX_HEADER
, GFP_ATOMIC
);
421 /* Make sure the outbound skb has enough header room reserved. */
422 skb_reserve(nskb
, packet
->overhead
+ LL_MAX_HEADER
);
424 /* Set the owning socket so that we know where to get the
425 * destination IP address.
427 sctp_packet_set_owner_w(nskb
, sk
);
429 if (!sctp_transport_dst_check(tp
)) {
430 sctp_transport_route(tp
, NULL
, sctp_sk(sk
));
431 if (asoc
&& (asoc
->param_flags
& SPP_PMTUD_ENABLE
)) {
432 sctp_assoc_sync_pmtu(sk
, asoc
);
435 dst
= dst_clone(tp
->dst
);
436 skb_dst_set(nskb
, dst
);
440 /* Build the SCTP header. */
441 sh
= (struct sctphdr
*)skb_push(nskb
, sizeof(struct sctphdr
));
442 skb_reset_transport_header(nskb
);
443 sh
->source
= htons(packet
->source_port
);
444 sh
->dest
= htons(packet
->destination_port
);
446 /* From 6.8 Adler-32 Checksum Calculation:
447 * After the packet is constructed (containing the SCTP common
448 * header and one or more control or DATA chunks), the
451 * 1) Fill in the proper Verification Tag in the SCTP common
452 * header and initialize the checksum field to 0's.
454 sh
->vtag
= htonl(packet
->vtag
);
460 * An endpoint bundles chunks by simply including multiple
461 * chunks in one outbound SCTP packet. ...
465 * 3.2 Chunk Field Descriptions
467 * The total length of a chunk (including Type, Length and
468 * Value fields) MUST be a multiple of 4 bytes. If the length
469 * of the chunk is not a multiple of 4 bytes, the sender MUST
470 * pad the chunk with all zero bytes and this padding is not
471 * included in the chunk length field. The sender should
472 * never pad with more than 3 bytes.
474 * [This whole comment explains WORD_ROUND() below.]
476 SCTP_DEBUG_PRINTK("***sctp_transmit_packet***\n");
477 list_for_each_entry_safe(chunk
, tmp
, &packet
->chunk_list
, list
) {
478 list_del_init(&chunk
->list
);
479 if (sctp_chunk_is_data(chunk
)) {
480 /* 6.3.1 C4) When data is in flight and when allowed
481 * by rule C5, a new RTT measurement MUST be made each
482 * round trip. Furthermore, new RTT measurements
483 * SHOULD be made no more than once per round-trip
484 * for a given destination transport address.
487 if (!tp
->rto_pending
) {
488 chunk
->rtt_in_progress
= 1;
494 padding
= WORD_ROUND(chunk
->skb
->len
) - chunk
->skb
->len
;
496 memset(skb_put(chunk
->skb
, padding
), 0, padding
);
498 /* if this is the auth chunk that we are adding,
499 * store pointer where it will be added and put
500 * the auth into the packet.
502 if (chunk
== packet
->auth
)
503 auth
= skb_tail_pointer(nskb
);
505 cksum_buf_len
+= chunk
->skb
->len
;
506 memcpy(skb_put(nskb
, chunk
->skb
->len
),
507 chunk
->skb
->data
, chunk
->skb
->len
);
509 SCTP_DEBUG_PRINTK("%s %p[%s] %s 0x%x, %s %d, %s %d, %s %d\n",
511 sctp_cname(SCTP_ST_CHUNK(
512 chunk
->chunk_hdr
->type
)),
513 chunk
->has_tsn
? "TSN" : "No TSN",
515 ntohl(chunk
->subh
.data_hdr
->tsn
) : 0,
516 "length", ntohs(chunk
->chunk_hdr
->length
),
517 "chunk->skb->len", chunk
->skb
->len
,
518 "rtt_in_progress", chunk
->rtt_in_progress
);
521 * If this is a control chunk, this is our last
522 * reference. Free data chunks after they've been
523 * acknowledged or have failed.
525 if (!sctp_chunk_is_data(chunk
))
526 sctp_chunk_free(chunk
);
529 /* SCTP-AUTH, Section 6.2
530 * The sender MUST calculate the MAC as described in RFC2104 [2]
531 * using the hash function H as described by the MAC Identifier and
532 * the shared association key K based on the endpoint pair shared key
533 * described by the shared key identifier. The 'data' used for the
534 * computation of the AUTH-chunk is given by the AUTH chunk with its
535 * HMAC field set to zero (as shown in Figure 6) followed by all
536 * chunks that are placed after the AUTH chunk in the SCTP packet.
539 sctp_auth_calculate_hmac(asoc
, nskb
,
540 (struct sctp_auth_chunk
*)auth
,
543 /* 2) Calculate the Adler-32 checksum of the whole packet,
544 * including the SCTP common header and all the
547 * Note: Adler-32 is no longer applicable, as has been replaced
548 * by CRC32-C as described in <draft-ietf-tsvwg-sctpcsum-02.txt>.
550 if (!sctp_checksum_disable
) {
551 if (!(dst
->dev
->features
& NETIF_F_SCTP_CSUM
)) {
552 __u32 crc32
= sctp_start_cksum((__u8
*)sh
, cksum_buf_len
);
554 /* 3) Put the resultant value into the checksum field in the
555 * common header, and leave the rest of the bits unchanged.
557 sh
->checksum
= sctp_end_cksum(crc32
);
559 /* no need to seed pseudo checksum for SCTP */
560 nskb
->ip_summed
= CHECKSUM_PARTIAL
;
561 nskb
->csum_start
= (skb_transport_header(nskb
) -
563 nskb
->csum_offset
= offsetof(struct sctphdr
, checksum
);
567 /* IP layer ECN support
569 * "The ECN-Capable Transport (ECT) bit would be set by the
570 * data sender to indicate that the end-points of the
571 * transport protocol are ECN-capable."
573 * Now setting the ECT bit all the time, as it should not cause
574 * any problems protocol-wise even if our peer ignores it.
576 * Note: The works for IPv6 layer checks this bit too later
577 * in transmission. See IP6_ECN_flow_xmit().
579 (*tp
->af_specific
->ecn_capable
)(nskb
->sk
);
581 /* Set up the IP options. */
582 /* BUG: not implemented
583 * For v4 this all lives somewhere in sk->sk_opt...
586 /* Dump that on IP! */
587 if (asoc
&& asoc
->peer
.last_sent_to
!= tp
) {
588 /* Considering the multiple CPU scenario, this is a
589 * "correcter" place for last_sent_to. --xguo
591 asoc
->peer
.last_sent_to
= tp
;
595 struct timer_list
*timer
;
596 unsigned long timeout
;
598 /* Restart the AUTOCLOSE timer when sending data. */
599 if (sctp_state(asoc
, ESTABLISHED
) && asoc
->autoclose
) {
600 timer
= &asoc
->timers
[SCTP_EVENT_TIMEOUT_AUTOCLOSE
];
601 timeout
= asoc
->timeouts
[SCTP_EVENT_TIMEOUT_AUTOCLOSE
];
603 if (!mod_timer(timer
, jiffies
+ timeout
))
604 sctp_association_hold(asoc
);
608 SCTP_DEBUG_PRINTK("***sctp_transmit_packet*** skb len %d\n",
611 nskb
->local_df
= packet
->ipfragok
;
612 (*tp
->af_specific
->sctp_xmit
)(nskb
, tp
);
615 sctp_packet_reset(packet
);
619 IP_INC_STATS_BH(&init_net
, IPSTATS_MIB_OUTNOROUTES
);
621 /* FIXME: Returning the 'err' will effect all the associations
622 * associated with a socket, although only one of the paths of the
623 * association is unreachable.
624 * The real failure of a transport or association can be passed on
625 * to the user via notifications. So setting this error may not be
628 /* err = -EHOSTUNREACH; */
630 /* Control chunks are unreliable so just drop them. DATA chunks
631 * will get resent or dropped later.
634 list_for_each_entry_safe(chunk
, tmp
, &packet
->chunk_list
, list
) {
635 list_del_init(&chunk
->list
);
636 if (!sctp_chunk_is_data(chunk
))
637 sctp_chunk_free(chunk
);
645 /********************************************************************
646 * 2nd Level Abstractions
647 ********************************************************************/
649 /* This private function check to see if a chunk can be added */
650 static sctp_xmit_t
sctp_packet_can_append_data(struct sctp_packet
*packet
,
651 struct sctp_chunk
*chunk
)
653 sctp_xmit_t retval
= SCTP_XMIT_OK
;
654 size_t datasize
, rwnd
, inflight
, flight_size
;
655 struct sctp_transport
*transport
= packet
->transport
;
656 struct sctp_association
*asoc
= transport
->asoc
;
657 struct sctp_outq
*q
= &asoc
->outqueue
;
659 /* RFC 2960 6.1 Transmission of DATA Chunks
661 * A) At any given time, the data sender MUST NOT transmit new data to
662 * any destination transport address if its peer's rwnd indicates
663 * that the peer has no buffer space (i.e. rwnd is 0, see Section
664 * 6.2.1). However, regardless of the value of rwnd (including if it
665 * is 0), the data sender can always have one DATA chunk in flight to
666 * the receiver if allowed by cwnd (see rule B below). This rule
667 * allows the sender to probe for a change in rwnd that the sender
668 * missed due to the SACK having been lost in transit from the data
669 * receiver to the data sender.
672 rwnd
= asoc
->peer
.rwnd
;
673 inflight
= q
->outstanding_bytes
;
674 flight_size
= transport
->flight_size
;
676 datasize
= sctp_data_size(chunk
);
678 if (datasize
> rwnd
) {
680 /* We have (at least) one data chunk in flight,
681 * so we can't fall back to rule 6.1 B).
683 retval
= SCTP_XMIT_RWND_FULL
;
688 /* RFC 2960 6.1 Transmission of DATA Chunks
690 * B) At any given time, the sender MUST NOT transmit new data
691 * to a given transport address if it has cwnd or more bytes
692 * of data outstanding to that transport address.
694 /* RFC 7.2.4 & the Implementers Guide 2.8.
697 * When a Fast Retransmit is being performed the sender SHOULD
698 * ignore the value of cwnd and SHOULD NOT delay retransmission.
700 if (chunk
->fast_retransmit
!= SCTP_NEED_FRTX
)
701 if (flight_size
>= transport
->cwnd
) {
702 retval
= SCTP_XMIT_RWND_FULL
;
706 /* Nagle's algorithm to solve small-packet problem:
707 * Inhibit the sending of new chunks when new outgoing data arrives
708 * if any previously transmitted data on the connection remains
711 if (!sctp_sk(asoc
->base
.sk
)->nodelay
&& sctp_packet_empty(packet
) &&
712 inflight
&& sctp_state(asoc
, ESTABLISHED
)) {
713 unsigned int max
= transport
->pathmtu
- packet
->overhead
;
714 unsigned int len
= chunk
->skb
->len
+ q
->out_qlen
;
716 /* Check whether this chunk and all the rest of pending
717 * data will fit or delay in hopes of bundling a full
719 * Don't delay large message writes that may have been
720 * fragmeneted into small peices.
722 if ((len
< max
) && chunk
->msg
->can_delay
) {
723 retval
= SCTP_XMIT_NAGLE_DELAY
;
732 /* This private function does management things when adding DATA chunk */
733 static void sctp_packet_append_data(struct sctp_packet
*packet
,
734 struct sctp_chunk
*chunk
)
736 struct sctp_transport
*transport
= packet
->transport
;
737 size_t datasize
= sctp_data_size(chunk
);
738 struct sctp_association
*asoc
= transport
->asoc
;
739 u32 rwnd
= asoc
->peer
.rwnd
;
741 /* Keep track of how many bytes are in flight over this transport. */
742 transport
->flight_size
+= datasize
;
744 /* Keep track of how many bytes are in flight to the receiver. */
745 asoc
->outqueue
.outstanding_bytes
+= datasize
;
747 /* Update our view of the receiver's rwnd. */
753 asoc
->peer
.rwnd
= rwnd
;
754 /* Has been accepted for transmission. */
755 if (!asoc
->peer
.prsctp_capable
)
756 chunk
->msg
->can_abandon
= 0;
757 sctp_chunk_assign_tsn(chunk
);
758 sctp_chunk_assign_ssn(chunk
);
761 static sctp_xmit_t
sctp_packet_will_fit(struct sctp_packet
*packet
,
762 struct sctp_chunk
*chunk
,
768 sctp_xmit_t retval
= SCTP_XMIT_OK
;
770 psize
= packet
->size
;
771 pmtu
= ((packet
->transport
->asoc
) ?
772 (packet
->transport
->asoc
->pathmtu
) :
773 (packet
->transport
->pathmtu
));
775 too_big
= (psize
+ chunk_len
> pmtu
);
777 /* Decide if we need to fragment or resubmit later. */
779 /* It's OK to fragmet at IP level if any one of the following
781 * 1. The packet is empty (meaning this chunk is greater
783 * 2. The chunk we are adding is a control chunk
784 * 3. The packet doesn't have any data in it yet and data
785 * requires authentication.
787 if (sctp_packet_empty(packet
) || !sctp_chunk_is_data(chunk
) ||
788 (!packet
->has_data
&& chunk
->auth
)) {
789 /* We no longer do re-fragmentation.
790 * Just fragment at the IP layer, if we
791 * actually hit this condition
793 packet
->ipfragok
= 1;
795 retval
= SCTP_XMIT_PMTU_FULL
;