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 #include <linux/types.h>
45 #include <linux/kernel.h>
46 #include <linux/wait.h>
47 #include <linux/time.h>
49 #include <linux/ipv6.h>
50 #include <linux/init.h>
51 #include <net/inet_ecn.h>
54 #include <net/net_namespace.h>
56 #include <linux/socket.h> /* for sa_family_t */
59 #include <net/sctp/sctp.h>
60 #include <net/sctp/sm.h>
61 #include <net/sctp/checksum.h>
63 /* Forward declarations for private helpers. */
64 static sctp_xmit_t
sctp_packet_can_append_data(struct sctp_packet
*packet
,
65 struct sctp_chunk
*chunk
);
66 static void sctp_packet_append_data(struct sctp_packet
*packet
,
67 struct sctp_chunk
*chunk
);
68 static sctp_xmit_t
sctp_packet_will_fit(struct sctp_packet
*packet
,
69 struct sctp_chunk
*chunk
,
72 static void sctp_packet_reset(struct sctp_packet
*packet
)
74 packet
->size
= packet
->overhead
;
75 packet
->has_cookie_echo
= 0;
84 * This appears to be a followup set of initializations.
86 struct sctp_packet
*sctp_packet_config(struct sctp_packet
*packet
,
87 __u32 vtag
, int ecn_capable
)
89 struct sctp_chunk
*chunk
= NULL
;
91 SCTP_DEBUG_PRINTK("%s: packet:%p vtag:0x%x\n", __func__
,
94 sctp_packet_reset(packet
);
97 if (ecn_capable
&& sctp_packet_empty(packet
)) {
98 chunk
= sctp_get_ecne_prepend(packet
->transport
->asoc
);
100 /* If there a is a prepend chunk stick it on the list before
101 * any other chunks get appended.
104 sctp_packet_append_chunk(packet
, chunk
);
110 /* Initialize the packet structure. */
111 struct sctp_packet
*sctp_packet_init(struct sctp_packet
*packet
,
112 struct sctp_transport
*transport
,
113 __u16 sport
, __u16 dport
)
115 struct sctp_association
*asoc
= transport
->asoc
;
118 SCTP_DEBUG_PRINTK("%s: packet:%p transport:%p\n", __func__
,
121 packet
->transport
= transport
;
122 packet
->source_port
= sport
;
123 packet
->destination_port
= dport
;
124 INIT_LIST_HEAD(&packet
->chunk_list
);
126 struct sctp_sock
*sp
= sctp_sk(asoc
->base
.sk
);
127 overhead
= sp
->pf
->af
->net_header_len
;
129 overhead
= sizeof(struct ipv6hdr
);
131 overhead
+= sizeof(struct sctphdr
);
132 packet
->overhead
= overhead
;
133 sctp_packet_reset(packet
);
135 packet
->malloced
= 0;
140 void sctp_packet_free(struct sctp_packet
*packet
)
142 struct sctp_chunk
*chunk
, *tmp
;
144 SCTP_DEBUG_PRINTK("%s: packet:%p\n", __func__
, packet
);
146 list_for_each_entry_safe(chunk
, tmp
, &packet
->chunk_list
, list
) {
147 list_del_init(&chunk
->list
);
148 sctp_chunk_free(chunk
);
151 if (packet
->malloced
)
155 /* This routine tries to append the chunk to the offered packet. If adding
156 * the chunk causes the packet to exceed the path MTU and COOKIE_ECHO chunk
157 * is not present in the packet, it transmits the input packet.
158 * Data can be bundled with a packet containing a COOKIE_ECHO chunk as long
159 * as it can fit in the packet, but any more data that does not fit in this
160 * packet can be sent only after receiving the COOKIE_ACK.
162 sctp_xmit_t
sctp_packet_transmit_chunk(struct sctp_packet
*packet
,
163 struct sctp_chunk
*chunk
,
169 SCTP_DEBUG_PRINTK("%s: packet:%p chunk:%p\n", __func__
,
172 switch ((retval
= (sctp_packet_append_chunk(packet
, chunk
)))) {
173 case SCTP_XMIT_PMTU_FULL
:
174 if (!packet
->has_cookie_echo
) {
175 error
= sctp_packet_transmit(packet
);
177 chunk
->skb
->sk
->sk_err
= -error
;
179 /* If we have an empty packet, then we can NOT ever
183 retval
= sctp_packet_append_chunk(packet
,
188 case SCTP_XMIT_RWND_FULL
:
190 case SCTP_XMIT_NAGLE_DELAY
:
197 /* Try to bundle an auth chunk into the packet. */
198 static sctp_xmit_t
sctp_packet_bundle_auth(struct sctp_packet
*pkt
,
199 struct sctp_chunk
*chunk
)
201 struct sctp_association
*asoc
= pkt
->transport
->asoc
;
202 struct sctp_chunk
*auth
;
203 sctp_xmit_t retval
= SCTP_XMIT_OK
;
205 /* if we don't have an association, we can't do authentication */
209 /* See if this is an auth chunk we are bundling or if
210 * auth is already bundled.
212 if (chunk
->chunk_hdr
->type
== SCTP_CID_AUTH
|| pkt
->has_auth
)
215 /* if the peer did not request this chunk to be authenticated,
221 auth
= sctp_make_auth(asoc
);
225 retval
= sctp_packet_append_chunk(pkt
, auth
);
230 /* Try to bundle a SACK with the packet. */
231 static sctp_xmit_t
sctp_packet_bundle_sack(struct sctp_packet
*pkt
,
232 struct sctp_chunk
*chunk
)
234 sctp_xmit_t retval
= SCTP_XMIT_OK
;
236 /* If sending DATA and haven't aleady bundled a SACK, try to
237 * bundle one in to the packet.
239 if (sctp_chunk_is_data(chunk
) && !pkt
->has_sack
&&
240 !pkt
->has_cookie_echo
) {
241 struct sctp_association
*asoc
;
242 struct timer_list
*timer
;
243 asoc
= pkt
->transport
->asoc
;
244 timer
= &asoc
->timers
[SCTP_EVENT_TIMEOUT_SACK
];
246 /* If the SACK timer is running, we have a pending SACK */
247 if (timer_pending(timer
)) {
248 struct sctp_chunk
*sack
;
249 asoc
->a_rwnd
= asoc
->rwnd
;
250 sack
= sctp_make_sack(asoc
);
252 retval
= sctp_packet_append_chunk(pkt
, sack
);
253 asoc
->peer
.sack_needed
= 0;
254 if (del_timer(timer
))
255 sctp_association_put(asoc
);
262 /* Append a chunk to the offered packet reporting back any inability to do
265 sctp_xmit_t
sctp_packet_append_chunk(struct sctp_packet
*packet
,
266 struct sctp_chunk
*chunk
)
268 sctp_xmit_t retval
= SCTP_XMIT_OK
;
269 __u16 chunk_len
= WORD_ROUND(ntohs(chunk
->chunk_hdr
->length
));
271 SCTP_DEBUG_PRINTK("%s: packet:%p chunk:%p\n", __func__
, packet
,
274 /* Data chunks are special. Before seeing what else we can
275 * bundle into this packet, check to see if we are allowed to
278 if (sctp_chunk_is_data(chunk
)) {
279 retval
= sctp_packet_can_append_data(packet
, chunk
);
280 if (retval
!= SCTP_XMIT_OK
)
284 /* Try to bundle AUTH chunk */
285 retval
= sctp_packet_bundle_auth(packet
, chunk
);
286 if (retval
!= SCTP_XMIT_OK
)
289 /* Try to bundle SACK chunk */
290 retval
= sctp_packet_bundle_sack(packet
, chunk
);
291 if (retval
!= SCTP_XMIT_OK
)
294 /* Check to see if this chunk will fit into the packet */
295 retval
= sctp_packet_will_fit(packet
, chunk
, chunk_len
);
296 if (retval
!= SCTP_XMIT_OK
)
299 /* We believe that this chunk is OK to add to the packet */
300 switch (chunk
->chunk_hdr
->type
) {
302 /* Account for the data being in the packet */
303 sctp_packet_append_data(packet
, chunk
);
304 /* Disallow SACK bundling after DATA. */
305 packet
->has_sack
= 1;
306 /* Disallow AUTH bundling after DATA */
307 packet
->has_auth
= 1;
308 /* Let it be knows that packet has DATA in it */
309 packet
->has_data
= 1;
310 /* timestamp the chunk for rtx purposes */
311 chunk
->sent_at
= jiffies
;
313 case SCTP_CID_COOKIE_ECHO
:
314 packet
->has_cookie_echo
= 1;
318 packet
->has_sack
= 1;
322 packet
->has_auth
= 1;
323 packet
->auth
= chunk
;
327 /* It is OK to send this chunk. */
328 list_add_tail(&chunk
->list
, &packet
->chunk_list
);
329 packet
->size
+= chunk_len
;
330 chunk
->transport
= packet
->transport
;
335 /* All packets are sent to the network through this function from
338 * The return value is a normal kernel error return value.
340 int sctp_packet_transmit(struct sctp_packet
*packet
)
342 struct sctp_transport
*tp
= packet
->transport
;
343 struct sctp_association
*asoc
= tp
->asoc
;
345 struct sk_buff
*nskb
;
346 struct sctp_chunk
*chunk
, *tmp
;
349 int padding
; /* How much padding do we need? */
351 struct dst_entry
*dst
= tp
->dst
;
352 unsigned char *auth
= NULL
; /* pointer to auth in skb data */
353 __u32 cksum_buf_len
= sizeof(struct sctphdr
);
355 SCTP_DEBUG_PRINTK("%s: packet:%p\n", __func__
, packet
);
357 /* Do NOT generate a chunkless packet. */
358 if (list_empty(&packet
->chunk_list
))
361 /* Set up convenience variables... */
362 chunk
= list_entry(packet
->chunk_list
.next
, struct sctp_chunk
, list
);
365 /* Allocate the new skb. */
366 nskb
= alloc_skb(packet
->size
+ LL_MAX_HEADER
, GFP_ATOMIC
);
370 /* Make sure the outbound skb has enough header room reserved. */
371 skb_reserve(nskb
, packet
->overhead
+ LL_MAX_HEADER
);
373 /* Set the owning socket so that we know where to get the
374 * destination IP address.
376 skb_set_owner_w(nskb
, sk
);
378 /* The 'obsolete' field of dst is set to 2 when a dst is freed. */
379 if (!dst
|| (dst
->obsolete
> 1)) {
381 sctp_transport_route(tp
, NULL
, sctp_sk(sk
));
382 if (asoc
&& (asoc
->param_flags
& SPP_PMTUD_ENABLE
)) {
383 sctp_assoc_sync_pmtu(asoc
);
386 dst
= dst_clone(tp
->dst
);
387 skb_dst_set(nskb
, dst
);
391 /* Build the SCTP header. */
392 sh
= (struct sctphdr
*)skb_push(nskb
, sizeof(struct sctphdr
));
393 skb_reset_transport_header(nskb
);
394 sh
->source
= htons(packet
->source_port
);
395 sh
->dest
= htons(packet
->destination_port
);
397 /* From 6.8 Adler-32 Checksum Calculation:
398 * After the packet is constructed (containing the SCTP common
399 * header and one or more control or DATA chunks), the
402 * 1) Fill in the proper Verification Tag in the SCTP common
403 * header and initialize the checksum field to 0's.
405 sh
->vtag
= htonl(packet
->vtag
);
411 * An endpoint bundles chunks by simply including multiple
412 * chunks in one outbound SCTP packet. ...
416 * 3.2 Chunk Field Descriptions
418 * The total length of a chunk (including Type, Length and
419 * Value fields) MUST be a multiple of 4 bytes. If the length
420 * of the chunk is not a multiple of 4 bytes, the sender MUST
421 * pad the chunk with all zero bytes and this padding is not
422 * included in the chunk length field. The sender should
423 * never pad with more than 3 bytes.
425 * [This whole comment explains WORD_ROUND() below.]
427 SCTP_DEBUG_PRINTK("***sctp_transmit_packet***\n");
428 list_for_each_entry_safe(chunk
, tmp
, &packet
->chunk_list
, list
) {
429 list_del_init(&chunk
->list
);
430 if (sctp_chunk_is_data(chunk
)) {
432 if (!chunk
->resent
) {
434 /* 6.3.1 C4) When data is in flight and when allowed
435 * by rule C5, a new RTT measurement MUST be made each
436 * round trip. Furthermore, new RTT measurements
437 * SHOULD be made no more than once per round-trip
438 * for a given destination transport address.
441 if (!tp
->rto_pending
) {
442 chunk
->rtt_in_progress
= 1;
452 padding
= WORD_ROUND(chunk
->skb
->len
) - chunk
->skb
->len
;
454 memset(skb_put(chunk
->skb
, padding
), 0, padding
);
456 /* if this is the auth chunk that we are adding,
457 * store pointer where it will be added and put
458 * the auth into the packet.
460 if (chunk
== packet
->auth
)
461 auth
= skb_tail_pointer(nskb
);
463 cksum_buf_len
+= chunk
->skb
->len
;
464 memcpy(skb_put(nskb
, chunk
->skb
->len
),
465 chunk
->skb
->data
, chunk
->skb
->len
);
467 SCTP_DEBUG_PRINTK("%s %p[%s] %s 0x%x, %s %d, %s %d, %s %d\n",
469 sctp_cname(SCTP_ST_CHUNK(
470 chunk
->chunk_hdr
->type
)),
471 chunk
->has_tsn
? "TSN" : "No TSN",
473 ntohl(chunk
->subh
.data_hdr
->tsn
) : 0,
474 "length", ntohs(chunk
->chunk_hdr
->length
),
475 "chunk->skb->len", chunk
->skb
->len
,
476 "rtt_in_progress", chunk
->rtt_in_progress
);
479 * If this is a control chunk, this is our last
480 * reference. Free data chunks after they've been
481 * acknowledged or have failed.
483 if (!sctp_chunk_is_data(chunk
))
484 sctp_chunk_free(chunk
);
487 /* SCTP-AUTH, Section 6.2
488 * The sender MUST calculate the MAC as described in RFC2104 [2]
489 * using the hash function H as described by the MAC Identifier and
490 * the shared association key K based on the endpoint pair shared key
491 * described by the shared key identifier. The 'data' used for the
492 * computation of the AUTH-chunk is given by the AUTH chunk with its
493 * HMAC field set to zero (as shown in Figure 6) followed by all
494 * chunks that are placed after the AUTH chunk in the SCTP packet.
497 sctp_auth_calculate_hmac(asoc
, nskb
,
498 (struct sctp_auth_chunk
*)auth
,
501 /* 2) Calculate the Adler-32 checksum of the whole packet,
502 * including the SCTP common header and all the
505 * Note: Adler-32 is no longer applicable, as has been replaced
506 * by CRC32-C as described in <draft-ietf-tsvwg-sctpcsum-02.txt>.
508 if (!sctp_checksum_disable
&&
509 !(dst
->dev
->features
& (NETIF_F_NO_CSUM
| NETIF_F_SCTP_CSUM
))) {
510 __u32 crc32
= sctp_start_cksum((__u8
*)sh
, cksum_buf_len
);
512 /* 3) Put the resultant value into the checksum field in the
513 * common header, and leave the rest of the bits unchanged.
515 sh
->checksum
= sctp_end_cksum(crc32
);
517 if (dst
->dev
->features
& NETIF_F_SCTP_CSUM
) {
518 /* no need to seed psuedo checksum for SCTP */
519 nskb
->ip_summed
= CHECKSUM_PARTIAL
;
520 nskb
->csum_start
= (skb_transport_header(nskb
) -
522 nskb
->csum_offset
= offsetof(struct sctphdr
, checksum
);
524 nskb
->ip_summed
= CHECKSUM_UNNECESSARY
;
528 /* IP layer ECN support
530 * "The ECN-Capable Transport (ECT) bit would be set by the
531 * data sender to indicate that the end-points of the
532 * transport protocol are ECN-capable."
534 * Now setting the ECT bit all the time, as it should not cause
535 * any problems protocol-wise even if our peer ignores it.
537 * Note: The works for IPv6 layer checks this bit too later
538 * in transmission. See IP6_ECN_flow_xmit().
540 (*tp
->af_specific
->ecn_capable
)(nskb
->sk
);
542 /* Set up the IP options. */
543 /* BUG: not implemented
544 * For v4 this all lives somewhere in sk->sk_opt...
547 /* Dump that on IP! */
548 if (asoc
&& asoc
->peer
.last_sent_to
!= tp
) {
549 /* Considering the multiple CPU scenario, this is a
550 * "correcter" place for last_sent_to. --xguo
552 asoc
->peer
.last_sent_to
= tp
;
556 struct timer_list
*timer
;
557 unsigned long timeout
;
559 /* Restart the AUTOCLOSE timer when sending data. */
560 if (sctp_state(asoc
, ESTABLISHED
) && asoc
->autoclose
) {
561 timer
= &asoc
->timers
[SCTP_EVENT_TIMEOUT_AUTOCLOSE
];
562 timeout
= asoc
->timeouts
[SCTP_EVENT_TIMEOUT_AUTOCLOSE
];
564 if (!mod_timer(timer
, jiffies
+ timeout
))
565 sctp_association_hold(asoc
);
569 SCTP_DEBUG_PRINTK("***sctp_transmit_packet*** skb len %d\n",
572 nskb
->local_df
= packet
->ipfragok
;
573 (*tp
->af_specific
->sctp_xmit
)(nskb
, tp
);
576 sctp_packet_reset(packet
);
580 IP_INC_STATS_BH(&init_net
, IPSTATS_MIB_OUTNOROUTES
);
582 /* FIXME: Returning the 'err' will effect all the associations
583 * associated with a socket, although only one of the paths of the
584 * association is unreachable.
585 * The real failure of a transport or association can be passed on
586 * to the user via notifications. So setting this error may not be
589 /* err = -EHOSTUNREACH; */
591 /* Control chunks are unreliable so just drop them. DATA chunks
592 * will get resent or dropped later.
595 list_for_each_entry_safe(chunk
, tmp
, &packet
->chunk_list
, list
) {
596 list_del_init(&chunk
->list
);
597 if (!sctp_chunk_is_data(chunk
))
598 sctp_chunk_free(chunk
);
606 /********************************************************************
607 * 2nd Level Abstractions
608 ********************************************************************/
610 /* This private function check to see if a chunk can be added */
611 static sctp_xmit_t
sctp_packet_can_append_data(struct sctp_packet
*packet
,
612 struct sctp_chunk
*chunk
)
614 sctp_xmit_t retval
= SCTP_XMIT_OK
;
615 size_t datasize
, rwnd
, inflight
, flight_size
;
616 struct sctp_transport
*transport
= packet
->transport
;
617 struct sctp_association
*asoc
= transport
->asoc
;
618 struct sctp_outq
*q
= &asoc
->outqueue
;
620 /* RFC 2960 6.1 Transmission of DATA Chunks
622 * A) At any given time, the data sender MUST NOT transmit new data to
623 * any destination transport address if its peer's rwnd indicates
624 * that the peer has no buffer space (i.e. rwnd is 0, see Section
625 * 6.2.1). However, regardless of the value of rwnd (including if it
626 * is 0), the data sender can always have one DATA chunk in flight to
627 * the receiver if allowed by cwnd (see rule B below). This rule
628 * allows the sender to probe for a change in rwnd that the sender
629 * missed due to the SACK having been lost in transit from the data
630 * receiver to the data sender.
633 rwnd
= asoc
->peer
.rwnd
;
634 inflight
= q
->outstanding_bytes
;
635 flight_size
= transport
->flight_size
;
637 datasize
= sctp_data_size(chunk
);
639 if (datasize
> rwnd
) {
641 /* We have (at least) one data chunk in flight,
642 * so we can't fall back to rule 6.1 B).
644 retval
= SCTP_XMIT_RWND_FULL
;
649 /* RFC 2960 6.1 Transmission of DATA Chunks
651 * B) At any given time, the sender MUST NOT transmit new data
652 * to a given transport address if it has cwnd or more bytes
653 * of data outstanding to that transport address.
655 /* RFC 7.2.4 & the Implementers Guide 2.8.
658 * When a Fast Retransmit is being performed the sender SHOULD
659 * ignore the value of cwnd and SHOULD NOT delay retransmission.
661 if (chunk
->fast_retransmit
!= SCTP_NEED_FRTX
)
662 if (flight_size
>= transport
->cwnd
) {
663 retval
= SCTP_XMIT_RWND_FULL
;
667 /* Nagle's algorithm to solve small-packet problem:
668 * Inhibit the sending of new chunks when new outgoing data arrives
669 * if any previously transmitted data on the connection remains
672 if (!sctp_sk(asoc
->base
.sk
)->nodelay
&& sctp_packet_empty(packet
) &&
673 inflight
&& sctp_state(asoc
, ESTABLISHED
)) {
674 unsigned max
= transport
->pathmtu
- packet
->overhead
;
675 unsigned len
= chunk
->skb
->len
+ q
->out_qlen
;
677 /* Check whether this chunk and all the rest of pending
678 * data will fit or delay in hopes of bundling a full
680 * Don't delay large message writes that may have been
681 * fragmeneted into small peices.
683 if ((len
< max
) && (chunk
->msg
->msg_size
< max
)) {
684 retval
= SCTP_XMIT_NAGLE_DELAY
;
693 /* This private function does management things when adding DATA chunk */
694 static void sctp_packet_append_data(struct sctp_packet
*packet
,
695 struct sctp_chunk
*chunk
)
697 struct sctp_transport
*transport
= packet
->transport
;
698 size_t datasize
= sctp_data_size(chunk
);
699 struct sctp_association
*asoc
= transport
->asoc
;
700 u32 rwnd
= asoc
->peer
.rwnd
;
702 /* Keep track of how many bytes are in flight over this transport. */
703 transport
->flight_size
+= datasize
;
705 /* Keep track of how many bytes are in flight to the receiver. */
706 asoc
->outqueue
.outstanding_bytes
+= datasize
;
708 /* Update our view of the receiver's rwnd. Include sk_buff overhead
709 * while updating peer.rwnd so that it reduces the chances of a
710 * receiver running out of receive buffer space even when receive
711 * window is still open. This can happen when a sender is sending
712 * sending small messages.
714 datasize
+= sizeof(struct sk_buff
);
720 asoc
->peer
.rwnd
= rwnd
;
721 /* Has been accepted for transmission. */
722 if (!asoc
->peer
.prsctp_capable
)
723 chunk
->msg
->can_abandon
= 0;
724 sctp_chunk_assign_tsn(chunk
);
725 sctp_chunk_assign_ssn(chunk
);
728 static sctp_xmit_t
sctp_packet_will_fit(struct sctp_packet
*packet
,
729 struct sctp_chunk
*chunk
,
735 sctp_xmit_t retval
= SCTP_XMIT_OK
;
737 psize
= packet
->size
;
738 pmtu
= ((packet
->transport
->asoc
) ?
739 (packet
->transport
->asoc
->pathmtu
) :
740 (packet
->transport
->pathmtu
));
742 too_big
= (psize
+ chunk_len
> pmtu
);
744 /* Decide if we need to fragment or resubmit later. */
746 /* It's OK to fragmet at IP level if any one of the following
748 * 1. The packet is empty (meaning this chunk is greater
750 * 2. The chunk we are adding is a control chunk
751 * 3. The packet doesn't have any data in it yet and data
752 * requires authentication.
754 if (sctp_packet_empty(packet
) || !sctp_chunk_is_data(chunk
) ||
755 (!packet
->has_data
&& chunk
->auth
)) {
756 /* We no longer do re-fragmentation.
757 * Just fragment at the IP layer, if we
758 * actually hit this condition
760 packet
->ipfragok
= 1;
762 retval
= SCTP_XMIT_PMTU_FULL
;