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 chunk:%p\n", __func__
, packet
, chunk
);
187 switch ((retval
= (sctp_packet_append_chunk(packet
, chunk
)))) {
188 case SCTP_XMIT_PMTU_FULL
:
189 if (!packet
->has_cookie_echo
) {
190 error
= sctp_packet_transmit(packet
, gfp
);
192 chunk
->skb
->sk
->sk_err
= -error
;
194 /* If we have an empty packet, then we can NOT ever
198 retval
= sctp_packet_append_chunk(packet
,
203 case SCTP_XMIT_RWND_FULL
:
205 case SCTP_XMIT_DELAY
:
212 /* Try to bundle an auth chunk into the packet. */
213 static sctp_xmit_t
sctp_packet_bundle_auth(struct sctp_packet
*pkt
,
214 struct sctp_chunk
*chunk
)
216 struct sctp_association
*asoc
= pkt
->transport
->asoc
;
217 struct sctp_chunk
*auth
;
218 sctp_xmit_t retval
= SCTP_XMIT_OK
;
220 /* if we don't have an association, we can't do authentication */
224 /* See if this is an auth chunk we are bundling or if
225 * auth is already bundled.
227 if (chunk
->chunk_hdr
->type
== SCTP_CID_AUTH
|| pkt
->has_auth
)
230 /* if the peer did not request this chunk to be authenticated,
236 auth
= sctp_make_auth(asoc
);
240 retval
= __sctp_packet_append_chunk(pkt
, auth
);
242 if (retval
!= SCTP_XMIT_OK
)
243 sctp_chunk_free(auth
);
248 /* Try to bundle a SACK with the packet. */
249 static sctp_xmit_t
sctp_packet_bundle_sack(struct sctp_packet
*pkt
,
250 struct sctp_chunk
*chunk
)
252 sctp_xmit_t retval
= SCTP_XMIT_OK
;
254 /* If sending DATA and haven't aleady bundled a SACK, try to
255 * bundle one in to the packet.
257 if (sctp_chunk_is_data(chunk
) && !pkt
->has_sack
&&
258 !pkt
->has_cookie_echo
) {
259 struct sctp_association
*asoc
;
260 struct timer_list
*timer
;
261 asoc
= pkt
->transport
->asoc
;
262 timer
= &asoc
->timers
[SCTP_EVENT_TIMEOUT_SACK
];
264 /* If the SACK timer is running, we have a pending SACK */
265 if (timer_pending(timer
)) {
266 struct sctp_chunk
*sack
;
268 if (pkt
->transport
->sack_generation
!=
269 pkt
->transport
->asoc
->peer
.sack_generation
)
272 asoc
->a_rwnd
= asoc
->rwnd
;
273 sack
= sctp_make_sack(asoc
);
275 retval
= __sctp_packet_append_chunk(pkt
, sack
);
276 if (retval
!= SCTP_XMIT_OK
) {
277 sctp_chunk_free(sack
);
280 asoc
->peer
.sack_needed
= 0;
281 if (del_timer(timer
))
282 sctp_association_put(asoc
);
291 /* Append a chunk to the offered packet reporting back any inability to do
294 static sctp_xmit_t
__sctp_packet_append_chunk(struct sctp_packet
*packet
,
295 struct sctp_chunk
*chunk
)
297 sctp_xmit_t retval
= SCTP_XMIT_OK
;
298 __u16 chunk_len
= WORD_ROUND(ntohs(chunk
->chunk_hdr
->length
));
300 /* Check to see if this chunk will fit into the packet */
301 retval
= sctp_packet_will_fit(packet
, chunk
, chunk_len
);
302 if (retval
!= SCTP_XMIT_OK
)
305 /* We believe that this chunk is OK to add to the packet */
306 switch (chunk
->chunk_hdr
->type
) {
308 /* Account for the data being in the packet */
309 sctp_packet_append_data(packet
, chunk
);
310 /* Disallow SACK bundling after DATA. */
311 packet
->has_sack
= 1;
312 /* Disallow AUTH bundling after DATA */
313 packet
->has_auth
= 1;
314 /* Let it be knows that packet has DATA in it */
315 packet
->has_data
= 1;
316 /* timestamp the chunk for rtx purposes */
317 chunk
->sent_at
= jiffies
;
319 case SCTP_CID_COOKIE_ECHO
:
320 packet
->has_cookie_echo
= 1;
324 packet
->has_sack
= 1;
326 chunk
->asoc
->stats
.osacks
++;
330 packet
->has_auth
= 1;
331 packet
->auth
= chunk
;
335 /* It is OK to send this chunk. */
336 list_add_tail(&chunk
->list
, &packet
->chunk_list
);
337 packet
->size
+= chunk_len
;
338 chunk
->transport
= packet
->transport
;
343 /* Append a chunk to the offered packet reporting back any inability to do
346 sctp_xmit_t
sctp_packet_append_chunk(struct sctp_packet
*packet
,
347 struct sctp_chunk
*chunk
)
349 sctp_xmit_t retval
= SCTP_XMIT_OK
;
351 pr_debug("%s: packet:%p chunk:%p\n", __func__
, packet
, chunk
);
353 /* Data chunks are special. Before seeing what else we can
354 * bundle into this packet, check to see if we are allowed to
357 if (sctp_chunk_is_data(chunk
)) {
358 retval
= sctp_packet_can_append_data(packet
, chunk
);
359 if (retval
!= SCTP_XMIT_OK
)
363 /* Try to bundle AUTH chunk */
364 retval
= sctp_packet_bundle_auth(packet
, chunk
);
365 if (retval
!= SCTP_XMIT_OK
)
368 /* Try to bundle SACK chunk */
369 retval
= sctp_packet_bundle_sack(packet
, chunk
);
370 if (retval
!= SCTP_XMIT_OK
)
373 retval
= __sctp_packet_append_chunk(packet
, chunk
);
379 static void sctp_packet_release_owner(struct sk_buff
*skb
)
384 static void sctp_packet_set_owner_w(struct sk_buff
*skb
, struct sock
*sk
)
388 skb
->destructor
= sctp_packet_release_owner
;
391 * The data chunks have already been accounted for in sctp_sendmsg(),
392 * therefore only reserve a single byte to keep socket around until
393 * the packet has been transmitted.
395 atomic_inc(&sk
->sk_wmem_alloc
);
398 /* All packets are sent to the network through this function from
401 * The return value is a normal kernel error return value.
403 int sctp_packet_transmit(struct sctp_packet
*packet
, gfp_t gfp
)
405 struct sctp_transport
*tp
= packet
->transport
;
406 struct sctp_association
*asoc
= tp
->asoc
;
408 struct sk_buff
*nskb
= NULL
, *head
= NULL
;
409 struct sctp_chunk
*chunk
, *tmp
;
412 int padding
; /* How much padding do we need? */
417 struct dst_entry
*dst
;
418 unsigned char *auth
= NULL
; /* pointer to auth in skb data */
420 pr_debug("%s: packet:%p\n", __func__
, packet
);
422 /* Do NOT generate a chunkless packet. */
423 if (list_empty(&packet
->chunk_list
))
426 /* Set up convenience variables... */
427 chunk
= list_entry(packet
->chunk_list
.next
, struct sctp_chunk
, list
);
430 /* Allocate the head skb, or main one if not in GSO */
431 if (packet
->size
> tp
->pathmtu
&& !packet
->ipfragok
) {
432 if (sk_can_gso(sk
)) {
434 pkt_size
= packet
->overhead
;
436 /* If this happens, we trash this packet and try
437 * to build a new one, hopefully correct this
438 * time. Application may notice this error.
440 pr_err_once("Trying to GSO but underlying device doesn't support it.");
444 pkt_size
= packet
->size
;
446 head
= alloc_skb(pkt_size
+ MAX_HEADER
, gfp
);
450 NAPI_GRO_CB(head
)->last
= head
;
451 skb_shinfo(head
)->gso_type
= sk
->sk_gso_type
;
454 /* Make sure the outbound skb has enough header room reserved. */
455 skb_reserve(head
, packet
->overhead
+ MAX_HEADER
);
457 /* Set the owning socket so that we know where to get the
458 * destination IP address.
460 sctp_packet_set_owner_w(head
, sk
);
462 if (!sctp_transport_dst_check(tp
)) {
463 sctp_transport_route(tp
, NULL
, sctp_sk(sk
));
464 if (asoc
&& (asoc
->param_flags
& SPP_PMTUD_ENABLE
)) {
465 sctp_assoc_sync_pmtu(sk
, asoc
);
468 dst
= dst_clone(tp
->dst
);
471 skb_dst_set(head
, dst
);
473 /* Build the SCTP header. */
474 sh
= (struct sctphdr
*)skb_push(head
, sizeof(struct sctphdr
));
475 skb_reset_transport_header(head
);
476 sh
->source
= htons(packet
->source_port
);
477 sh
->dest
= htons(packet
->destination_port
);
479 /* From 6.8 Adler-32 Checksum Calculation:
480 * After the packet is constructed (containing the SCTP common
481 * header and one or more control or DATA chunks), the
484 * 1) Fill in the proper Verification Tag in the SCTP common
485 * header and initialize the checksum field to 0's.
487 sh
->vtag
= htonl(packet
->vtag
);
490 pr_debug("***sctp_transmit_packet***\n");
493 /* Set up convenience variables... */
494 chunk
= list_entry(packet
->chunk_list
.next
, struct sctp_chunk
, list
);
497 /* Calculate packet size, so it fits in PMTU. Leave
498 * other chunks for the next packets.
501 pkt_size
= packet
->overhead
;
502 list_for_each_entry(chunk
, &packet
->chunk_list
, list
) {
503 int padded
= WORD_ROUND(chunk
->skb
->len
);
505 if (pkt_size
+ padded
> tp
->pathmtu
)
510 /* Allocate a new skb. */
511 nskb
= alloc_skb(pkt_size
+ MAX_HEADER
, gfp
);
515 /* Make sure the outbound skb has enough header
518 skb_reserve(nskb
, packet
->overhead
+ MAX_HEADER
);
524 * 3.2 Chunk Field Descriptions
526 * The total length of a chunk (including Type, Length and
527 * Value fields) MUST be a multiple of 4 bytes. If the length
528 * of the chunk is not a multiple of 4 bytes, the sender MUST
529 * pad the chunk with all zero bytes and this padding is not
530 * included in the chunk length field. The sender should
531 * never pad with more than 3 bytes.
533 * [This whole comment explains WORD_ROUND() below.]
536 pkt_size
-= packet
->overhead
;
537 list_for_each_entry_safe(chunk
, tmp
, &packet
->chunk_list
, list
) {
538 list_del_init(&chunk
->list
);
539 if (sctp_chunk_is_data(chunk
)) {
540 /* 6.3.1 C4) When data is in flight and when allowed
541 * by rule C5, a new RTT measurement MUST be made each
542 * round trip. Furthermore, new RTT measurements
543 * SHOULD be made no more than once per round-trip
544 * for a given destination transport address.
547 if (!chunk
->resent
&& !tp
->rto_pending
) {
548 chunk
->rtt_in_progress
= 1;
555 padding
= WORD_ROUND(chunk
->skb
->len
) - chunk
->skb
->len
;
557 memset(skb_put(chunk
->skb
, padding
), 0, padding
);
559 /* if this is the auth chunk that we are adding,
560 * store pointer where it will be added and put
561 * the auth into the packet.
563 if (chunk
== packet
->auth
)
564 auth
= skb_tail_pointer(nskb
);
566 memcpy(skb_put(nskb
, chunk
->skb
->len
),
567 chunk
->skb
->data
, chunk
->skb
->len
);
569 pr_debug("*** Chunk:%p[%s] %s 0x%x, length:%d, chunk->skb->len:%d, rtt_in_progress:%d\n",
571 sctp_cname(SCTP_ST_CHUNK(chunk
->chunk_hdr
->type
)),
572 chunk
->has_tsn
? "TSN" : "No TSN",
573 chunk
->has_tsn
? ntohl(chunk
->subh
.data_hdr
->tsn
) : 0,
574 ntohs(chunk
->chunk_hdr
->length
), chunk
->skb
->len
,
575 chunk
->rtt_in_progress
);
577 /* If this is a control chunk, this is our last
578 * reference. Free data chunks after they've been
579 * acknowledged or have failed.
580 * Re-queue auth chunks if needed.
582 pkt_size
-= WORD_ROUND(chunk
->skb
->len
);
584 if (chunk
== packet
->auth
&& !list_empty(&packet
->chunk_list
))
585 list_add(&chunk
->list
, &packet
->chunk_list
);
586 else if (!sctp_chunk_is_data(chunk
))
587 sctp_chunk_free(chunk
);
593 /* SCTP-AUTH, Section 6.2
594 * The sender MUST calculate the MAC as described in RFC2104 [2]
595 * using the hash function H as described by the MAC Identifier and
596 * the shared association key K based on the endpoint pair shared key
597 * described by the shared key identifier. The 'data' used for the
598 * computation of the AUTH-chunk is given by the AUTH chunk with its
599 * HMAC field set to zero (as shown in Figure 6) followed by all
600 * chunks that are placed after the AUTH chunk in the SCTP packet.
603 sctp_auth_calculate_hmac(asoc
, nskb
,
604 (struct sctp_auth_chunk
*)auth
,
610 if (skb_gro_receive(&head
, nskb
))
613 if (WARN_ON_ONCE(skb_shinfo(head
)->gso_segs
>=
614 sk
->sk_gso_max_segs
))
616 } while (!list_empty(&packet
->chunk_list
));
618 /* 2) Calculate the Adler-32 checksum of the whole packet,
619 * including the SCTP common header and all the
622 * Note: Adler-32 is no longer applicable, as has been replaced
623 * by CRC32-C as described in <draft-ietf-tsvwg-sctpcsum-02.txt>.
625 * If it's a GSO packet, it's postponed to sctp_skb_segment.
627 if (!sctp_checksum_disable
|| gso
) {
628 if (!gso
&& (!(dst
->dev
->features
& NETIF_F_SCTP_CRC
) ||
629 dst_xfrm(dst
) || packet
->ipfragok
)) {
630 sh
->checksum
= sctp_compute_cksum(head
, 0);
632 /* no need to seed pseudo checksum for SCTP */
633 head
->ip_summed
= CHECKSUM_PARTIAL
;
634 head
->csum_start
= skb_transport_header(head
) - head
->head
;
635 head
->csum_offset
= offsetof(struct sctphdr
, checksum
);
639 /* IP layer ECN support
641 * "The ECN-Capable Transport (ECT) bit would be set by the
642 * data sender to indicate that the end-points of the
643 * transport protocol are ECN-capable."
645 * Now setting the ECT bit all the time, as it should not cause
646 * any problems protocol-wise even if our peer ignores it.
648 * Note: The works for IPv6 layer checks this bit too later
649 * in transmission. See IP6_ECN_flow_xmit().
651 tp
->af_specific
->ecn_capable(sk
);
653 /* Set up the IP options. */
654 /* BUG: not implemented
655 * For v4 this all lives somewhere in sk->sk_opt...
658 /* Dump that on IP! */
660 asoc
->stats
.opackets
+= pktcount
;
661 if (asoc
->peer
.last_sent_to
!= tp
)
662 /* Considering the multiple CPU scenario, this is a
663 * "correcter" place for last_sent_to. --xguo
665 asoc
->peer
.last_sent_to
= tp
;
669 struct timer_list
*timer
;
670 unsigned long timeout
;
672 /* Restart the AUTOCLOSE timer when sending data. */
673 if (sctp_state(asoc
, ESTABLISHED
) &&
674 asoc
->timeouts
[SCTP_EVENT_TIMEOUT_AUTOCLOSE
]) {
675 timer
= &asoc
->timers
[SCTP_EVENT_TIMEOUT_AUTOCLOSE
];
676 timeout
= asoc
->timeouts
[SCTP_EVENT_TIMEOUT_AUTOCLOSE
];
678 if (!mod_timer(timer
, jiffies
+ timeout
))
679 sctp_association_hold(asoc
);
683 pr_debug("***sctp_transmit_packet*** skb->len:%d\n", head
->len
);
686 /* Cleanup our debris for IP stacks */
687 memset(head
->cb
, 0, max(sizeof(struct inet_skb_parm
),
688 sizeof(struct inet6_skb_parm
)));
690 skb_shinfo(head
)->gso_segs
= pktcount
;
691 skb_shinfo(head
)->gso_size
= GSO_BY_FRAGS
;
693 /* We have to refresh this in case we are xmiting to
694 * more than one transport at a time
697 if (__sk_dst_get(sk
) != tp
->dst
) {
699 sk_setup_caps(sk
, tp
->dst
);
703 head
->ignore_df
= packet
->ipfragok
;
704 tp
->af_specific
->sctp_xmit(head
, tp
);
707 sctp_packet_reset(packet
);
715 IP_INC_STATS(sock_net(asoc
->base
.sk
), IPSTATS_MIB_OUTNOROUTES
);
717 /* FIXME: Returning the 'err' will effect all the associations
718 * associated with a socket, although only one of the paths of the
719 * association is unreachable.
720 * The real failure of a transport or association can be passed on
721 * to the user via notifications. So setting this error may not be
724 /* err = -EHOSTUNREACH; */
726 /* Control chunks are unreliable so just drop them. DATA chunks
727 * will get resent or dropped later.
730 list_for_each_entry_safe(chunk
, tmp
, &packet
->chunk_list
, list
) {
731 list_del_init(&chunk
->list
);
732 if (!sctp_chunk_is_data(chunk
))
733 sctp_chunk_free(chunk
);
741 /********************************************************************
742 * 2nd Level Abstractions
743 ********************************************************************/
745 /* This private function check to see if a chunk can be added */
746 static sctp_xmit_t
sctp_packet_can_append_data(struct sctp_packet
*packet
,
747 struct sctp_chunk
*chunk
)
749 size_t datasize
, rwnd
, inflight
, flight_size
;
750 struct sctp_transport
*transport
= packet
->transport
;
751 struct sctp_association
*asoc
= transport
->asoc
;
752 struct sctp_outq
*q
= &asoc
->outqueue
;
754 /* RFC 2960 6.1 Transmission of DATA Chunks
756 * A) At any given time, the data sender MUST NOT transmit new data to
757 * any destination transport address if its peer's rwnd indicates
758 * that the peer has no buffer space (i.e. rwnd is 0, see Section
759 * 6.2.1). However, regardless of the value of rwnd (including if it
760 * is 0), the data sender can always have one DATA chunk in flight to
761 * the receiver if allowed by cwnd (see rule B below). This rule
762 * allows the sender to probe for a change in rwnd that the sender
763 * missed due to the SACK having been lost in transit from the data
764 * receiver to the data sender.
767 rwnd
= asoc
->peer
.rwnd
;
768 inflight
= q
->outstanding_bytes
;
769 flight_size
= transport
->flight_size
;
771 datasize
= sctp_data_size(chunk
);
773 if (datasize
> rwnd
&& inflight
> 0)
774 /* We have (at least) one data chunk in flight,
775 * so we can't fall back to rule 6.1 B).
777 return SCTP_XMIT_RWND_FULL
;
779 /* RFC 2960 6.1 Transmission of DATA Chunks
781 * B) At any given time, the sender MUST NOT transmit new data
782 * to a given transport address if it has cwnd or more bytes
783 * of data outstanding to that transport address.
785 /* RFC 7.2.4 & the Implementers Guide 2.8.
788 * When a Fast Retransmit is being performed the sender SHOULD
789 * ignore the value of cwnd and SHOULD NOT delay retransmission.
791 if (chunk
->fast_retransmit
!= SCTP_NEED_FRTX
&&
792 flight_size
>= transport
->cwnd
)
793 return SCTP_XMIT_RWND_FULL
;
795 /* Nagle's algorithm to solve small-packet problem:
796 * Inhibit the sending of new chunks when new outgoing data arrives
797 * if any previously transmitted data on the connection remains
801 if (sctp_sk(asoc
->base
.sk
)->nodelay
)
805 if (!sctp_packet_empty(packet
))
806 /* Append to packet */
810 /* Nothing unacked */
813 if (!sctp_state(asoc
, ESTABLISHED
))
816 /* Check whether this chunk and all the rest of pending data will fit
817 * or delay in hopes of bundling a full sized packet.
819 if (chunk
->skb
->len
+ q
->out_qlen
>
820 transport
->pathmtu
- packet
->overhead
- sizeof(sctp_data_chunk_t
) - 4)
821 /* Enough data queued to fill a packet */
824 /* Don't delay large message writes that may have been fragmented */
825 if (!chunk
->msg
->can_delay
)
828 /* Defer until all data acked or packet full */
829 return SCTP_XMIT_DELAY
;
832 /* This private function does management things when adding DATA chunk */
833 static void sctp_packet_append_data(struct sctp_packet
*packet
,
834 struct sctp_chunk
*chunk
)
836 struct sctp_transport
*transport
= packet
->transport
;
837 size_t datasize
= sctp_data_size(chunk
);
838 struct sctp_association
*asoc
= transport
->asoc
;
839 u32 rwnd
= asoc
->peer
.rwnd
;
841 /* Keep track of how many bytes are in flight over this transport. */
842 transport
->flight_size
+= datasize
;
844 /* Keep track of how many bytes are in flight to the receiver. */
845 asoc
->outqueue
.outstanding_bytes
+= datasize
;
847 /* Update our view of the receiver's rwnd. */
853 asoc
->peer
.rwnd
= rwnd
;
854 /* Has been accepted for transmission. */
855 if (!asoc
->peer
.prsctp_capable
)
856 chunk
->msg
->can_abandon
= 0;
857 sctp_chunk_assign_tsn(chunk
);
858 sctp_chunk_assign_ssn(chunk
);
861 static sctp_xmit_t
sctp_packet_will_fit(struct sctp_packet
*packet
,
862 struct sctp_chunk
*chunk
,
866 sctp_xmit_t retval
= SCTP_XMIT_OK
;
868 psize
= packet
->size
;
869 if (packet
->transport
->asoc
)
870 pmtu
= packet
->transport
->asoc
->pathmtu
;
872 pmtu
= packet
->transport
->pathmtu
;
874 /* Decide if we need to fragment or resubmit later. */
875 if (psize
+ chunk_len
> pmtu
) {
876 /* It's OK to fragment at IP level if any one of the following
878 * 1. The packet is empty (meaning this chunk is greater
880 * 2. The packet doesn't have any data in it yet and data
881 * requires authentication.
883 if (sctp_packet_empty(packet
) ||
884 (!packet
->has_data
&& chunk
->auth
)) {
885 /* We no longer do re-fragmentation.
886 * Just fragment at the IP layer, if we
887 * actually hit this condition
889 packet
->ipfragok
= 1;
893 /* It is also okay to fragment if the chunk we are
894 * adding is a control chunk, but only if current packet
895 * is not a GSO one otherwise it causes fragmentation of
896 * a large frame. So in this case we allow the
897 * fragmentation by forcing it to be in a new packet.
899 if (!sctp_chunk_is_data(chunk
) && packet
->has_data
)
900 retval
= SCTP_XMIT_PMTU_FULL
;
902 if (psize
+ chunk_len
> packet
->max_size
)
903 /* Hit GSO/PMTU limit, gotta flush */
904 retval
= SCTP_XMIT_PMTU_FULL
;
906 if (!packet
->transport
->burst_limited
&&
907 psize
+ chunk_len
> (packet
->transport
->cwnd
>> 1))
908 /* Do not allow a single GSO packet to use more
911 retval
= SCTP_XMIT_PMTU_FULL
;
913 if (packet
->transport
->burst_limited
&&
914 psize
+ chunk_len
> (packet
->transport
->burst_limited
>> 1))
915 /* Do not allow a single GSO packet to use more
916 * than half of original cwnd.
918 retval
= SCTP_XMIT_PMTU_FULL
;
919 /* Otherwise it will fit in the GSO packet */