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, see
24 * <http://www.gnu.org/licenses/>.
26 * Please send any bug reports or fixes you make to the
28 * lksctp developers <linux-sctp@vger.kernel.org>
30 * Written or modified by:
31 * La Monte H.P. Yarroll <piggy@acm.org>
32 * Karl Knutson <karl@athena.chicago.il.us>
33 * Jon Grimm <jgrimm@austin.ibm.com>
34 * Sridhar Samudrala <sri@us.ibm.com>
37 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
39 #include <linux/types.h>
40 #include <linux/kernel.h>
41 #include <linux/wait.h>
42 #include <linux/time.h>
44 #include <linux/ipv6.h>
45 #include <linux/init.h>
46 #include <linux/slab.h>
47 #include <net/inet_ecn.h>
50 #include <net/net_namespace.h>
52 #include <linux/socket.h> /* for sa_family_t */
55 #include <net/sctp/sctp.h>
56 #include <net/sctp/sm.h>
57 #include <net/sctp/checksum.h>
59 /* Forward declarations for private helpers. */
60 static sctp_xmit_t
__sctp_packet_append_chunk(struct sctp_packet
*packet
,
61 struct sctp_chunk
*chunk
);
62 static sctp_xmit_t
sctp_packet_can_append_data(struct sctp_packet
*packet
,
63 struct sctp_chunk
*chunk
);
64 static void sctp_packet_append_data(struct sctp_packet
*packet
,
65 struct sctp_chunk
*chunk
);
66 static sctp_xmit_t
sctp_packet_will_fit(struct sctp_packet
*packet
,
67 struct sctp_chunk
*chunk
,
70 static void sctp_packet_reset(struct sctp_packet
*packet
)
72 packet
->size
= packet
->overhead
;
73 packet
->has_cookie_echo
= 0;
82 * This appears to be a followup set of initializations.
84 struct sctp_packet
*sctp_packet_config(struct sctp_packet
*packet
,
85 __u32 vtag
, int ecn_capable
)
87 struct sctp_transport
*tp
= packet
->transport
;
88 struct sctp_association
*asoc
= tp
->asoc
;
90 pr_debug("%s: packet:%p vtag:0x%x\n", __func__
, packet
, vtag
);
94 if (asoc
&& tp
->dst
) {
95 struct sock
*sk
= asoc
->base
.sk
;
98 if (__sk_dst_get(sk
) != tp
->dst
) {
100 sk_setup_caps(sk
, tp
->dst
);
103 if (sk_can_gso(sk
)) {
104 struct net_device
*dev
= tp
->dst
->dev
;
106 packet
->max_size
= dev
->gso_max_size
;
108 packet
->max_size
= asoc
->pathmtu
;
113 packet
->max_size
= tp
->pathmtu
;
116 if (ecn_capable
&& sctp_packet_empty(packet
)) {
117 struct sctp_chunk
*chunk
;
119 /* If there a is a prepend chunk stick it on the list before
120 * any other chunks get appended.
122 chunk
= sctp_get_ecne_prepend(asoc
);
124 sctp_packet_append_chunk(packet
, chunk
);
130 /* Initialize the packet structure. */
131 struct sctp_packet
*sctp_packet_init(struct sctp_packet
*packet
,
132 struct sctp_transport
*transport
,
133 __u16 sport
, __u16 dport
)
135 struct sctp_association
*asoc
= transport
->asoc
;
138 pr_debug("%s: packet:%p transport:%p\n", __func__
, packet
, transport
);
140 packet
->transport
= transport
;
141 packet
->source_port
= sport
;
142 packet
->destination_port
= dport
;
143 INIT_LIST_HEAD(&packet
->chunk_list
);
145 struct sctp_sock
*sp
= sctp_sk(asoc
->base
.sk
);
146 overhead
= sp
->pf
->af
->net_header_len
;
148 overhead
= sizeof(struct ipv6hdr
);
150 overhead
+= sizeof(struct sctphdr
);
151 packet
->overhead
= overhead
;
152 sctp_packet_reset(packet
);
159 void sctp_packet_free(struct sctp_packet
*packet
)
161 struct sctp_chunk
*chunk
, *tmp
;
163 pr_debug("%s: packet:%p\n", __func__
, packet
);
165 list_for_each_entry_safe(chunk
, tmp
, &packet
->chunk_list
, list
) {
166 list_del_init(&chunk
->list
);
167 sctp_chunk_free(chunk
);
171 /* This routine tries to append the chunk to the offered packet. If adding
172 * the chunk causes the packet to exceed the path MTU and COOKIE_ECHO chunk
173 * is not present in the packet, it transmits the input packet.
174 * Data can be bundled with a packet containing a COOKIE_ECHO chunk as long
175 * as it can fit in the packet, but any more data that does not fit in this
176 * packet can be sent only after receiving the COOKIE_ACK.
178 sctp_xmit_t
sctp_packet_transmit_chunk(struct sctp_packet
*packet
,
179 struct sctp_chunk
*chunk
,
180 int one_packet
, gfp_t gfp
)
185 pr_debug("%s: packet:%p size:%Zu chunk:%p size:%d\n", __func__
,
186 packet
, packet
->size
, chunk
, chunk
->skb
? chunk
->skb
->len
: -1);
188 switch ((retval
= (sctp_packet_append_chunk(packet
, chunk
)))) {
189 case SCTP_XMIT_PMTU_FULL
:
190 if (!packet
->has_cookie_echo
) {
191 error
= sctp_packet_transmit(packet
, gfp
);
193 chunk
->skb
->sk
->sk_err
= -error
;
195 /* If we have an empty packet, then we can NOT ever
199 retval
= sctp_packet_append_chunk(packet
,
204 case SCTP_XMIT_RWND_FULL
:
206 case SCTP_XMIT_DELAY
:
213 /* Try to bundle an auth chunk into the packet. */
214 static sctp_xmit_t
sctp_packet_bundle_auth(struct sctp_packet
*pkt
,
215 struct sctp_chunk
*chunk
)
217 struct sctp_association
*asoc
= pkt
->transport
->asoc
;
218 struct sctp_chunk
*auth
;
219 sctp_xmit_t retval
= SCTP_XMIT_OK
;
221 /* if we don't have an association, we can't do authentication */
225 /* See if this is an auth chunk we are bundling or if
226 * auth is already bundled.
228 if (chunk
->chunk_hdr
->type
== SCTP_CID_AUTH
|| pkt
->has_auth
)
231 /* if the peer did not request this chunk to be authenticated,
237 auth
= sctp_make_auth(asoc
);
241 retval
= __sctp_packet_append_chunk(pkt
, auth
);
243 if (retval
!= SCTP_XMIT_OK
)
244 sctp_chunk_free(auth
);
249 /* Try to bundle a SACK with the packet. */
250 static sctp_xmit_t
sctp_packet_bundle_sack(struct sctp_packet
*pkt
,
251 struct sctp_chunk
*chunk
)
253 sctp_xmit_t retval
= SCTP_XMIT_OK
;
255 /* If sending DATA and haven't aleady bundled a SACK, try to
256 * bundle one in to the packet.
258 if (sctp_chunk_is_data(chunk
) && !pkt
->has_sack
&&
259 !pkt
->has_cookie_echo
) {
260 struct sctp_association
*asoc
;
261 struct timer_list
*timer
;
262 asoc
= pkt
->transport
->asoc
;
263 timer
= &asoc
->timers
[SCTP_EVENT_TIMEOUT_SACK
];
265 /* If the SACK timer is running, we have a pending SACK */
266 if (timer_pending(timer
)) {
267 struct sctp_chunk
*sack
;
269 if (pkt
->transport
->sack_generation
!=
270 pkt
->transport
->asoc
->peer
.sack_generation
)
273 asoc
->a_rwnd
= asoc
->rwnd
;
274 sack
= sctp_make_sack(asoc
);
276 retval
= __sctp_packet_append_chunk(pkt
, sack
);
277 if (retval
!= SCTP_XMIT_OK
) {
278 sctp_chunk_free(sack
);
281 asoc
->peer
.sack_needed
= 0;
282 if (del_timer(timer
))
283 sctp_association_put(asoc
);
292 /* Append a chunk to the offered packet reporting back any inability to do
295 static sctp_xmit_t
__sctp_packet_append_chunk(struct sctp_packet
*packet
,
296 struct sctp_chunk
*chunk
)
298 sctp_xmit_t retval
= SCTP_XMIT_OK
;
299 __u16 chunk_len
= WORD_ROUND(ntohs(chunk
->chunk_hdr
->length
));
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;
327 chunk
->asoc
->stats
.osacks
++;
331 packet
->has_auth
= 1;
332 packet
->auth
= chunk
;
336 /* It is OK to send this chunk. */
337 list_add_tail(&chunk
->list
, &packet
->chunk_list
);
338 packet
->size
+= chunk_len
;
339 chunk
->transport
= packet
->transport
;
344 /* Append a chunk to the offered packet reporting back any inability to do
347 sctp_xmit_t
sctp_packet_append_chunk(struct sctp_packet
*packet
,
348 struct sctp_chunk
*chunk
)
350 sctp_xmit_t retval
= SCTP_XMIT_OK
;
352 pr_debug("%s: packet:%p chunk:%p\n", __func__
, packet
, chunk
);
354 /* Data chunks are special. Before seeing what else we can
355 * bundle into this packet, check to see if we are allowed to
358 if (sctp_chunk_is_data(chunk
)) {
359 retval
= sctp_packet_can_append_data(packet
, chunk
);
360 if (retval
!= SCTP_XMIT_OK
)
364 /* Try to bundle AUTH chunk */
365 retval
= sctp_packet_bundle_auth(packet
, chunk
);
366 if (retval
!= SCTP_XMIT_OK
)
369 /* Try to bundle SACK chunk */
370 retval
= sctp_packet_bundle_sack(packet
, chunk
);
371 if (retval
!= SCTP_XMIT_OK
)
374 retval
= __sctp_packet_append_chunk(packet
, chunk
);
380 static void sctp_packet_release_owner(struct sk_buff
*skb
)
385 static void sctp_packet_set_owner_w(struct sk_buff
*skb
, struct sock
*sk
)
389 skb
->destructor
= sctp_packet_release_owner
;
392 * The data chunks have already been accounted for in sctp_sendmsg(),
393 * therefore only reserve a single byte to keep socket around until
394 * the packet has been transmitted.
396 atomic_inc(&sk
->sk_wmem_alloc
);
399 /* All packets are sent to the network through this function from
402 * The return value is a normal kernel error return value.
404 int sctp_packet_transmit(struct sctp_packet
*packet
, gfp_t gfp
)
406 struct sctp_transport
*tp
= packet
->transport
;
407 struct sctp_association
*asoc
= tp
->asoc
;
409 struct sk_buff
*nskb
= NULL
, *head
= NULL
;
410 struct sctp_chunk
*chunk
, *tmp
;
413 int padding
; /* How much padding do we need? */
418 struct dst_entry
*dst
;
419 unsigned char *auth
= NULL
; /* pointer to auth in skb data */
421 pr_debug("%s: packet:%p\n", __func__
, packet
);
423 /* Do NOT generate a chunkless packet. */
424 if (list_empty(&packet
->chunk_list
))
427 /* Set up convenience variables... */
428 chunk
= list_entry(packet
->chunk_list
.next
, struct sctp_chunk
, list
);
431 /* Allocate the head skb, or main one if not in GSO */
432 if (packet
->size
> tp
->pathmtu
&& !packet
->ipfragok
) {
433 if (sk_can_gso(sk
)) {
435 pkt_size
= packet
->overhead
;
437 /* If this happens, we trash this packet and try
438 * to build a new one, hopefully correct this
439 * time. Application may notice this error.
441 pr_err_once("Trying to GSO but underlying device doesn't support it.");
445 pkt_size
= packet
->size
;
447 head
= alloc_skb(pkt_size
+ MAX_HEADER
, gfp
);
451 NAPI_GRO_CB(head
)->last
= head
;
452 skb_shinfo(head
)->gso_type
= sk
->sk_gso_type
;
455 /* Make sure the outbound skb has enough header room reserved. */
456 skb_reserve(head
, packet
->overhead
+ MAX_HEADER
);
458 /* Set the owning socket so that we know where to get the
459 * destination IP address.
461 sctp_packet_set_owner_w(head
, sk
);
463 if (!sctp_transport_dst_check(tp
)) {
464 sctp_transport_route(tp
, NULL
, sctp_sk(sk
));
465 if (asoc
&& (asoc
->param_flags
& SPP_PMTUD_ENABLE
)) {
466 sctp_assoc_sync_pmtu(sk
, asoc
);
469 dst
= dst_clone(tp
->dst
);
472 skb_dst_set(head
, dst
);
474 /* Build the SCTP header. */
475 sh
= (struct sctphdr
*)skb_push(head
, sizeof(struct sctphdr
));
476 skb_reset_transport_header(head
);
477 sh
->source
= htons(packet
->source_port
);
478 sh
->dest
= htons(packet
->destination_port
);
480 /* From 6.8 Adler-32 Checksum Calculation:
481 * After the packet is constructed (containing the SCTP common
482 * header and one or more control or DATA chunks), the
485 * 1) Fill in the proper Verification Tag in the SCTP common
486 * header and initialize the checksum field to 0's.
488 sh
->vtag
= htonl(packet
->vtag
);
491 pr_debug("***sctp_transmit_packet***\n");
494 /* Set up convenience variables... */
495 chunk
= list_entry(packet
->chunk_list
.next
, struct sctp_chunk
, list
);
498 /* Calculate packet size, so it fits in PMTU. Leave
499 * other chunks for the next packets.
502 pkt_size
= packet
->overhead
;
503 list_for_each_entry(chunk
, &packet
->chunk_list
, list
) {
504 int padded
= WORD_ROUND(chunk
->skb
->len
);
506 if (pkt_size
+ padded
> tp
->pathmtu
)
511 /* Allocate a new skb. */
512 nskb
= alloc_skb(pkt_size
+ MAX_HEADER
, gfp
);
516 /* Make sure the outbound skb has enough header
519 skb_reserve(nskb
, packet
->overhead
+ MAX_HEADER
);
525 * 3.2 Chunk Field Descriptions
527 * The total length of a chunk (including Type, Length and
528 * Value fields) MUST be a multiple of 4 bytes. If the length
529 * of the chunk is not a multiple of 4 bytes, the sender MUST
530 * pad the chunk with all zero bytes and this padding is not
531 * included in the chunk length field. The sender should
532 * never pad with more than 3 bytes.
534 * [This whole comment explains WORD_ROUND() below.]
537 pkt_size
-= packet
->overhead
;
538 list_for_each_entry_safe(chunk
, tmp
, &packet
->chunk_list
, list
) {
539 list_del_init(&chunk
->list
);
540 if (sctp_chunk_is_data(chunk
)) {
541 /* 6.3.1 C4) When data is in flight and when allowed
542 * by rule C5, a new RTT measurement MUST be made each
543 * round trip. Furthermore, new RTT measurements
544 * SHOULD be made no more than once per round-trip
545 * for a given destination transport address.
548 if (!chunk
->resent
&& !tp
->rto_pending
) {
549 chunk
->rtt_in_progress
= 1;
556 padding
= WORD_ROUND(chunk
->skb
->len
) - chunk
->skb
->len
;
558 memset(skb_put(chunk
->skb
, padding
), 0, padding
);
560 /* if this is the auth chunk that we are adding,
561 * store pointer where it will be added and put
562 * the auth into the packet.
564 if (chunk
== packet
->auth
)
565 auth
= skb_tail_pointer(nskb
);
567 memcpy(skb_put(nskb
, chunk
->skb
->len
),
568 chunk
->skb
->data
, chunk
->skb
->len
);
570 pr_debug("*** Chunk:%p[%s] %s 0x%x, length:%d, chunk->skb->len:%d, rtt_in_progress:%d\n",
572 sctp_cname(SCTP_ST_CHUNK(chunk
->chunk_hdr
->type
)),
573 chunk
->has_tsn
? "TSN" : "No TSN",
574 chunk
->has_tsn
? ntohl(chunk
->subh
.data_hdr
->tsn
) : 0,
575 ntohs(chunk
->chunk_hdr
->length
), chunk
->skb
->len
,
576 chunk
->rtt_in_progress
);
578 /* If this is a control chunk, this is our last
579 * reference. Free data chunks after they've been
580 * acknowledged or have failed.
581 * Re-queue auth chunks if needed.
583 pkt_size
-= WORD_ROUND(chunk
->skb
->len
);
585 if (chunk
== packet
->auth
&& !list_empty(&packet
->chunk_list
))
586 list_add(&chunk
->list
, &packet
->chunk_list
);
587 else if (!sctp_chunk_is_data(chunk
))
588 sctp_chunk_free(chunk
);
594 /* SCTP-AUTH, Section 6.2
595 * The sender MUST calculate the MAC as described in RFC2104 [2]
596 * using the hash function H as described by the MAC Identifier and
597 * the shared association key K based on the endpoint pair shared key
598 * described by the shared key identifier. The 'data' used for the
599 * computation of the AUTH-chunk is given by the AUTH chunk with its
600 * HMAC field set to zero (as shown in Figure 6) followed by all
601 * chunks that are placed after the AUTH chunk in the SCTP packet.
604 sctp_auth_calculate_hmac(asoc
, nskb
,
605 (struct sctp_auth_chunk
*)auth
,
611 if (skb_gro_receive(&head
, nskb
))
614 if (WARN_ON_ONCE(skb_shinfo(head
)->gso_segs
>=
615 sk
->sk_gso_max_segs
))
617 } while (!list_empty(&packet
->chunk_list
));
619 /* 2) Calculate the Adler-32 checksum of the whole packet,
620 * including the SCTP common header and all the
623 * Note: Adler-32 is no longer applicable, as has been replaced
624 * by CRC32-C as described in <draft-ietf-tsvwg-sctpcsum-02.txt>.
626 * If it's a GSO packet, it's postponed to sctp_skb_segment.
628 if (!sctp_checksum_disable
|| gso
) {
629 if (!gso
&& (!(dst
->dev
->features
& NETIF_F_SCTP_CRC
) ||
630 dst_xfrm(dst
) || packet
->ipfragok
)) {
631 sh
->checksum
= sctp_compute_cksum(head
, 0);
633 /* no need to seed pseudo checksum for SCTP */
634 head
->ip_summed
= CHECKSUM_PARTIAL
;
635 head
->csum_start
= skb_transport_header(head
) - head
->head
;
636 head
->csum_offset
= offsetof(struct sctphdr
, checksum
);
640 /* IP layer ECN support
642 * "The ECN-Capable Transport (ECT) bit would be set by the
643 * data sender to indicate that the end-points of the
644 * transport protocol are ECN-capable."
646 * Now setting the ECT bit all the time, as it should not cause
647 * any problems protocol-wise even if our peer ignores it.
649 * Note: The works for IPv6 layer checks this bit too later
650 * in transmission. See IP6_ECN_flow_xmit().
652 tp
->af_specific
->ecn_capable(sk
);
654 /* Set up the IP options. */
655 /* BUG: not implemented
656 * For v4 this all lives somewhere in sk->sk_opt...
659 /* Dump that on IP! */
661 asoc
->stats
.opackets
+= pktcount
;
662 if (asoc
->peer
.last_sent_to
!= tp
)
663 /* Considering the multiple CPU scenario, this is a
664 * "correcter" place for last_sent_to. --xguo
666 asoc
->peer
.last_sent_to
= tp
;
670 struct timer_list
*timer
;
671 unsigned long timeout
;
673 /* Restart the AUTOCLOSE timer when sending data. */
674 if (sctp_state(asoc
, ESTABLISHED
) &&
675 asoc
->timeouts
[SCTP_EVENT_TIMEOUT_AUTOCLOSE
]) {
676 timer
= &asoc
->timers
[SCTP_EVENT_TIMEOUT_AUTOCLOSE
];
677 timeout
= asoc
->timeouts
[SCTP_EVENT_TIMEOUT_AUTOCLOSE
];
679 if (!mod_timer(timer
, jiffies
+ timeout
))
680 sctp_association_hold(asoc
);
684 pr_debug("***sctp_transmit_packet*** skb->len:%d\n", head
->len
);
687 /* Cleanup our debris for IP stacks */
688 memset(head
->cb
, 0, max(sizeof(struct inet_skb_parm
),
689 sizeof(struct inet6_skb_parm
)));
691 skb_shinfo(head
)->gso_segs
= pktcount
;
692 skb_shinfo(head
)->gso_size
= GSO_BY_FRAGS
;
694 /* We have to refresh this in case we are xmiting to
695 * more than one transport at a time
698 if (__sk_dst_get(sk
) != tp
->dst
) {
700 sk_setup_caps(sk
, tp
->dst
);
704 head
->ignore_df
= packet
->ipfragok
;
705 tp
->af_specific
->sctp_xmit(head
, tp
);
708 sctp_packet_reset(packet
);
716 IP_INC_STATS(sock_net(asoc
->base
.sk
), IPSTATS_MIB_OUTNOROUTES
);
718 /* FIXME: Returning the 'err' will effect all the associations
719 * associated with a socket, although only one of the paths of the
720 * association is unreachable.
721 * The real failure of a transport or association can be passed on
722 * to the user via notifications. So setting this error may not be
725 /* err = -EHOSTUNREACH; */
727 /* Control chunks are unreliable so just drop them. DATA chunks
728 * will get resent or dropped later.
731 list_for_each_entry_safe(chunk
, tmp
, &packet
->chunk_list
, list
) {
732 list_del_init(&chunk
->list
);
733 if (!sctp_chunk_is_data(chunk
))
734 sctp_chunk_free(chunk
);
742 /********************************************************************
743 * 2nd Level Abstractions
744 ********************************************************************/
746 /* This private function check to see if a chunk can be added */
747 static sctp_xmit_t
sctp_packet_can_append_data(struct sctp_packet
*packet
,
748 struct sctp_chunk
*chunk
)
750 size_t datasize
, rwnd
, inflight
, flight_size
;
751 struct sctp_transport
*transport
= packet
->transport
;
752 struct sctp_association
*asoc
= transport
->asoc
;
753 struct sctp_outq
*q
= &asoc
->outqueue
;
755 /* RFC 2960 6.1 Transmission of DATA Chunks
757 * A) At any given time, the data sender MUST NOT transmit new data to
758 * any destination transport address if its peer's rwnd indicates
759 * that the peer has no buffer space (i.e. rwnd is 0, see Section
760 * 6.2.1). However, regardless of the value of rwnd (including if it
761 * is 0), the data sender can always have one DATA chunk in flight to
762 * the receiver if allowed by cwnd (see rule B below). This rule
763 * allows the sender to probe for a change in rwnd that the sender
764 * missed due to the SACK having been lost in transit from the data
765 * receiver to the data sender.
768 rwnd
= asoc
->peer
.rwnd
;
769 inflight
= q
->outstanding_bytes
;
770 flight_size
= transport
->flight_size
;
772 datasize
= sctp_data_size(chunk
);
774 if (datasize
> rwnd
&& inflight
> 0)
775 /* We have (at least) one data chunk in flight,
776 * so we can't fall back to rule 6.1 B).
778 return SCTP_XMIT_RWND_FULL
;
780 /* RFC 2960 6.1 Transmission of DATA Chunks
782 * B) At any given time, the sender MUST NOT transmit new data
783 * to a given transport address if it has cwnd or more bytes
784 * of data outstanding to that transport address.
786 /* RFC 7.2.4 & the Implementers Guide 2.8.
789 * When a Fast Retransmit is being performed the sender SHOULD
790 * ignore the value of cwnd and SHOULD NOT delay retransmission.
792 if (chunk
->fast_retransmit
!= SCTP_NEED_FRTX
&&
793 flight_size
>= transport
->cwnd
)
794 return SCTP_XMIT_RWND_FULL
;
796 /* Nagle's algorithm to solve small-packet problem:
797 * Inhibit the sending of new chunks when new outgoing data arrives
798 * if any previously transmitted data on the connection remains
802 if (sctp_sk(asoc
->base
.sk
)->nodelay
)
806 if (!sctp_packet_empty(packet
))
807 /* Append to packet */
811 /* Nothing unacked */
814 if (!sctp_state(asoc
, ESTABLISHED
))
817 /* Check whether this chunk and all the rest of pending data will fit
818 * or delay in hopes of bundling a full sized packet.
820 if (chunk
->skb
->len
+ q
->out_qlen
>
821 transport
->pathmtu
- packet
->overhead
- sizeof(sctp_data_chunk_t
) - 4)
822 /* Enough data queued to fill a packet */
825 /* Don't delay large message writes that may have been fragmented */
826 if (!chunk
->msg
->can_delay
)
829 /* Defer until all data acked or packet full */
830 return SCTP_XMIT_DELAY
;
833 /* This private function does management things when adding DATA chunk */
834 static void sctp_packet_append_data(struct sctp_packet
*packet
,
835 struct sctp_chunk
*chunk
)
837 struct sctp_transport
*transport
= packet
->transport
;
838 size_t datasize
= sctp_data_size(chunk
);
839 struct sctp_association
*asoc
= transport
->asoc
;
840 u32 rwnd
= asoc
->peer
.rwnd
;
842 /* Keep track of how many bytes are in flight over this transport. */
843 transport
->flight_size
+= datasize
;
845 /* Keep track of how many bytes are in flight to the receiver. */
846 asoc
->outqueue
.outstanding_bytes
+= datasize
;
848 /* Update our view of the receiver's rwnd. */
854 asoc
->peer
.rwnd
= rwnd
;
855 /* Has been accepted for transmission. */
856 if (!asoc
->peer
.prsctp_capable
)
857 chunk
->msg
->can_abandon
= 0;
858 sctp_chunk_assign_tsn(chunk
);
859 sctp_chunk_assign_ssn(chunk
);
862 static sctp_xmit_t
sctp_packet_will_fit(struct sctp_packet
*packet
,
863 struct sctp_chunk
*chunk
,
867 sctp_xmit_t retval
= SCTP_XMIT_OK
;
869 psize
= packet
->size
;
870 if (packet
->transport
->asoc
)
871 pmtu
= packet
->transport
->asoc
->pathmtu
;
873 pmtu
= packet
->transport
->pathmtu
;
875 /* Decide if we need to fragment or resubmit later. */
876 if (psize
+ chunk_len
> pmtu
) {
877 /* It's OK to fragment at IP level if any one of the following
879 * 1. The packet is empty (meaning this chunk is greater
881 * 2. The packet doesn't have any data in it yet and data
882 * requires authentication.
884 if (sctp_packet_empty(packet
) ||
885 (!packet
->has_data
&& chunk
->auth
)) {
886 /* We no longer do re-fragmentation.
887 * Just fragment at the IP layer, if we
888 * actually hit this condition
890 packet
->ipfragok
= 1;
894 /* It is also okay to fragment if the chunk we are
895 * adding is a control chunk, but only if current packet
896 * is not a GSO one otherwise it causes fragmentation of
897 * a large frame. So in this case we allow the
898 * fragmentation by forcing it to be in a new packet.
900 if (!sctp_chunk_is_data(chunk
) && packet
->has_data
)
901 retval
= SCTP_XMIT_PMTU_FULL
;
903 if (psize
+ chunk_len
> packet
->max_size
)
904 /* Hit GSO/PMTU limit, gotta flush */
905 retval
= SCTP_XMIT_PMTU_FULL
;
907 if (!packet
->transport
->burst_limited
&&
908 psize
+ chunk_len
> (packet
->transport
->cwnd
>> 1))
909 /* Do not allow a single GSO packet to use more
912 retval
= SCTP_XMIT_PMTU_FULL
;
914 if (packet
->transport
->burst_limited
&&
915 psize
+ chunk_len
> (packet
->transport
->burst_limited
>> 1))
916 /* Do not allow a single GSO packet to use more
917 * than half of original cwnd.
919 retval
= SCTP_XMIT_PMTU_FULL
;
920 /* Otherwise it will fit in the GSO packet */