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linux-zen-server/net/sctp/outqueue.c

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// SPDX-License-Identifier: GPL-2.0-or-later
/* SCTP kernel implementation
* (C) Copyright IBM Corp. 2001, 2004
* Copyright (c) 1999-2000 Cisco, Inc.
* Copyright (c) 1999-2001 Motorola, Inc.
* Copyright (c) 2001-2003 Intel Corp.
*
* This file is part of the SCTP kernel implementation
*
* These functions implement the sctp_outq class. The outqueue handles
* bundling and queueing of outgoing SCTP chunks.
*
* Please send any bug reports or fixes you make to the
* email address(es):
* lksctp developers <linux-sctp@vger.kernel.org>
*
* Written or modified by:
* La Monte H.P. Yarroll <piggy@acm.org>
* Karl Knutson <karl@athena.chicago.il.us>
* Perry Melange <pmelange@null.cc.uic.edu>
* Xingang Guo <xingang.guo@intel.com>
* Hui Huang <hui.huang@nokia.com>
* Sridhar Samudrala <sri@us.ibm.com>
* Jon Grimm <jgrimm@us.ibm.com>
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/types.h>
#include <linux/list.h> /* For struct list_head */
#include <linux/socket.h>
#include <linux/ip.h>
#include <linux/slab.h>
#include <net/sock.h> /* For skb_set_owner_w */
#include <net/sctp/sctp.h>
#include <net/sctp/sm.h>
#include <net/sctp/stream_sched.h>
#include <trace/events/sctp.h>
/* Declare internal functions here. */
static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn);
static void sctp_check_transmitted(struct sctp_outq *q,
struct list_head *transmitted_queue,
struct sctp_transport *transport,
union sctp_addr *saddr,
struct sctp_sackhdr *sack,
__u32 *highest_new_tsn);
static void sctp_mark_missing(struct sctp_outq *q,
struct list_head *transmitted_queue,
struct sctp_transport *transport,
__u32 highest_new_tsn,
int count_of_newacks);
static void sctp_outq_flush(struct sctp_outq *q, int rtx_timeout, gfp_t gfp);
/* Add data to the front of the queue. */
static inline void sctp_outq_head_data(struct sctp_outq *q,
struct sctp_chunk *ch)
{
struct sctp_stream_out_ext *oute;
__u16 stream;
list_add(&ch->list, &q->out_chunk_list);
q->out_qlen += ch->skb->len;
stream = sctp_chunk_stream_no(ch);
oute = SCTP_SO(&q->asoc->stream, stream)->ext;
list_add(&ch->stream_list, &oute->outq);
}
/* Take data from the front of the queue. */
static inline struct sctp_chunk *sctp_outq_dequeue_data(struct sctp_outq *q)
{
return q->sched->dequeue(q);
}
/* Add data chunk to the end of the queue. */
static inline void sctp_outq_tail_data(struct sctp_outq *q,
struct sctp_chunk *ch)
{
struct sctp_stream_out_ext *oute;
__u16 stream;
list_add_tail(&ch->list, &q->out_chunk_list);
q->out_qlen += ch->skb->len;
stream = sctp_chunk_stream_no(ch);
oute = SCTP_SO(&q->asoc->stream, stream)->ext;
list_add_tail(&ch->stream_list, &oute->outq);
}
/*
* SFR-CACC algorithm:
* D) If count_of_newacks is greater than or equal to 2
* and t was not sent to the current primary then the
* sender MUST NOT increment missing report count for t.
*/
static inline int sctp_cacc_skip_3_1_d(struct sctp_transport *primary,
struct sctp_transport *transport,
int count_of_newacks)
{
if (count_of_newacks >= 2 && transport != primary)
return 1;
return 0;
}
/*
* SFR-CACC algorithm:
* F) If count_of_newacks is less than 2, let d be the
* destination to which t was sent. If cacc_saw_newack
* is 0 for destination d, then the sender MUST NOT
* increment missing report count for t.
*/
static inline int sctp_cacc_skip_3_1_f(struct sctp_transport *transport,
int count_of_newacks)
{
if (count_of_newacks < 2 &&
(transport && !transport->cacc.cacc_saw_newack))
return 1;
return 0;
}
/*
* SFR-CACC algorithm:
* 3.1) If CYCLING_CHANGEOVER is 0, the sender SHOULD
* execute steps C, D, F.
*
* C has been implemented in sctp_outq_sack
*/
static inline int sctp_cacc_skip_3_1(struct sctp_transport *primary,
struct sctp_transport *transport,
int count_of_newacks)
{
if (!primary->cacc.cycling_changeover) {
if (sctp_cacc_skip_3_1_d(primary, transport, count_of_newacks))
return 1;
if (sctp_cacc_skip_3_1_f(transport, count_of_newacks))
return 1;
return 0;
}
return 0;
}
/*
* SFR-CACC algorithm:
* 3.2) Else if CYCLING_CHANGEOVER is 1, and t is less
* than next_tsn_at_change of the current primary, then
* the sender MUST NOT increment missing report count
* for t.
*/
static inline int sctp_cacc_skip_3_2(struct sctp_transport *primary, __u32 tsn)
{
if (primary->cacc.cycling_changeover &&
TSN_lt(tsn, primary->cacc.next_tsn_at_change))
return 1;
return 0;
}
/*
* SFR-CACC algorithm:
* 3) If the missing report count for TSN t is to be
* incremented according to [RFC2960] and
* [SCTP_STEWART-2002], and CHANGEOVER_ACTIVE is set,
* then the sender MUST further execute steps 3.1 and
* 3.2 to determine if the missing report count for
* TSN t SHOULD NOT be incremented.
*
* 3.3) If 3.1 and 3.2 do not dictate that the missing
* report count for t should not be incremented, then
* the sender SHOULD increment missing report count for
* t (according to [RFC2960] and [SCTP_STEWART_2002]).
*/
static inline int sctp_cacc_skip(struct sctp_transport *primary,
struct sctp_transport *transport,
int count_of_newacks,
__u32 tsn)
{
if (primary->cacc.changeover_active &&
(sctp_cacc_skip_3_1(primary, transport, count_of_newacks) ||
sctp_cacc_skip_3_2(primary, tsn)))
return 1;
return 0;
}
/* Initialize an existing sctp_outq. This does the boring stuff.
* You still need to define handlers if you really want to DO
* something with this structure...
*/
void sctp_outq_init(struct sctp_association *asoc, struct sctp_outq *q)
{
memset(q, 0, sizeof(struct sctp_outq));
q->asoc = asoc;
INIT_LIST_HEAD(&q->out_chunk_list);
INIT_LIST_HEAD(&q->control_chunk_list);
INIT_LIST_HEAD(&q->retransmit);
INIT_LIST_HEAD(&q->sacked);
INIT_LIST_HEAD(&q->abandoned);
sctp_sched_set_sched(asoc, sctp_sk(asoc->base.sk)->default_ss);
}
/* Free the outqueue structure and any related pending chunks.
*/
static void __sctp_outq_teardown(struct sctp_outq *q)
{
struct sctp_transport *transport;
struct list_head *lchunk, *temp;
struct sctp_chunk *chunk, *tmp;
/* Throw away unacknowledged chunks. */
list_for_each_entry(transport, &q->asoc->peer.transport_addr_list,
transports) {
while ((lchunk = sctp_list_dequeue(&transport->transmitted)) != NULL) {
chunk = list_entry(lchunk, struct sctp_chunk,
transmitted_list);
/* Mark as part of a failed message. */
sctp_chunk_fail(chunk, q->error);
sctp_chunk_free(chunk);
}
}
/* Throw away chunks that have been gap ACKed. */
list_for_each_safe(lchunk, temp, &q->sacked) {
list_del_init(lchunk);
chunk = list_entry(lchunk, struct sctp_chunk,
transmitted_list);
sctp_chunk_fail(chunk, q->error);
sctp_chunk_free(chunk);
}
/* Throw away any chunks in the retransmit queue. */
list_for_each_safe(lchunk, temp, &q->retransmit) {
list_del_init(lchunk);
chunk = list_entry(lchunk, struct sctp_chunk,
transmitted_list);
sctp_chunk_fail(chunk, q->error);
sctp_chunk_free(chunk);
}
/* Throw away any chunks that are in the abandoned queue. */
list_for_each_safe(lchunk, temp, &q->abandoned) {
list_del_init(lchunk);
chunk = list_entry(lchunk, struct sctp_chunk,
transmitted_list);
sctp_chunk_fail(chunk, q->error);
sctp_chunk_free(chunk);
}
/* Throw away any leftover data chunks. */
while ((chunk = sctp_outq_dequeue_data(q)) != NULL) {
sctp_sched_dequeue_done(q, chunk);
/* Mark as send failure. */
sctp_chunk_fail(chunk, q->error);
sctp_chunk_free(chunk);
}
/* Throw away any leftover control chunks. */
list_for_each_entry_safe(chunk, tmp, &q->control_chunk_list, list) {
list_del_init(&chunk->list);
sctp_chunk_free(chunk);
}
}
void sctp_outq_teardown(struct sctp_outq *q)
{
__sctp_outq_teardown(q);
sctp_outq_init(q->asoc, q);
}
/* Free the outqueue structure and any related pending chunks. */
void sctp_outq_free(struct sctp_outq *q)
{
/* Throw away leftover chunks. */
__sctp_outq_teardown(q);
}
/* Put a new chunk in an sctp_outq. */
void sctp_outq_tail(struct sctp_outq *q, struct sctp_chunk *chunk, gfp_t gfp)
{
struct net *net = q->asoc->base.net;
pr_debug("%s: outq:%p, chunk:%p[%s]\n", __func__, q, chunk,
chunk && chunk->chunk_hdr ?
sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)) :
"illegal chunk");
/* If it is data, queue it up, otherwise, send it
* immediately.
*/
if (sctp_chunk_is_data(chunk)) {
pr_debug("%s: outqueueing: outq:%p, chunk:%p[%s])\n",
__func__, q, chunk, chunk && chunk->chunk_hdr ?
sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)) :
"illegal chunk");
sctp_outq_tail_data(q, chunk);
if (chunk->asoc->peer.prsctp_capable &&
SCTP_PR_PRIO_ENABLED(chunk->sinfo.sinfo_flags))
chunk->asoc->sent_cnt_removable++;
if (chunk->chunk_hdr->flags & SCTP_DATA_UNORDERED)
SCTP_INC_STATS(net, SCTP_MIB_OUTUNORDERCHUNKS);
else
SCTP_INC_STATS(net, SCTP_MIB_OUTORDERCHUNKS);
} else {
list_add_tail(&chunk->list, &q->control_chunk_list);
SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
}
if (!q->cork)
sctp_outq_flush(q, 0, gfp);
}
/* Insert a chunk into the sorted list based on the TSNs. The retransmit list
* and the abandoned list are in ascending order.
*/
static void sctp_insert_list(struct list_head *head, struct list_head *new)
{
struct list_head *pos;
struct sctp_chunk *nchunk, *lchunk;
__u32 ntsn, ltsn;
int done = 0;
nchunk = list_entry(new, struct sctp_chunk, transmitted_list);
ntsn = ntohl(nchunk->subh.data_hdr->tsn);
list_for_each(pos, head) {
lchunk = list_entry(pos, struct sctp_chunk, transmitted_list);
ltsn = ntohl(lchunk->subh.data_hdr->tsn);
if (TSN_lt(ntsn, ltsn)) {
list_add(new, pos->prev);
done = 1;
break;
}
}
if (!done)
list_add_tail(new, head);
}
static int sctp_prsctp_prune_sent(struct sctp_association *asoc,
struct sctp_sndrcvinfo *sinfo,
struct list_head *queue, int msg_len)
{
struct sctp_chunk *chk, *temp;
list_for_each_entry_safe(chk, temp, queue, transmitted_list) {
struct sctp_stream_out *streamout;
if (!chk->msg->abandoned &&
(!SCTP_PR_PRIO_ENABLED(chk->sinfo.sinfo_flags) ||
chk->sinfo.sinfo_timetolive <= sinfo->sinfo_timetolive))
continue;
chk->msg->abandoned = 1;
list_del_init(&chk->transmitted_list);
sctp_insert_list(&asoc->outqueue.abandoned,
&chk->transmitted_list);
streamout = SCTP_SO(&asoc->stream, chk->sinfo.sinfo_stream);
asoc->sent_cnt_removable--;
asoc->abandoned_sent[SCTP_PR_INDEX(PRIO)]++;
streamout->ext->abandoned_sent[SCTP_PR_INDEX(PRIO)]++;
if (queue != &asoc->outqueue.retransmit &&
!chk->tsn_gap_acked) {
if (chk->transport)
chk->transport->flight_size -=
sctp_data_size(chk);
asoc->outqueue.outstanding_bytes -= sctp_data_size(chk);
}
msg_len -= chk->skb->truesize + sizeof(struct sctp_chunk);
if (msg_len <= 0)
break;
}
return msg_len;
}
static int sctp_prsctp_prune_unsent(struct sctp_association *asoc,
struct sctp_sndrcvinfo *sinfo, int msg_len)
{
struct sctp_outq *q = &asoc->outqueue;
struct sctp_chunk *chk, *temp;
struct sctp_stream_out *sout;
q->sched->unsched_all(&asoc->stream);
list_for_each_entry_safe(chk, temp, &q->out_chunk_list, list) {
if (!chk->msg->abandoned &&
(!(chk->chunk_hdr->flags & SCTP_DATA_FIRST_FRAG) ||
!SCTP_PR_PRIO_ENABLED(chk->sinfo.sinfo_flags) ||
chk->sinfo.sinfo_timetolive <= sinfo->sinfo_timetolive))
continue;
chk->msg->abandoned = 1;
sctp_sched_dequeue_common(q, chk);
asoc->sent_cnt_removable--;
asoc->abandoned_unsent[SCTP_PR_INDEX(PRIO)]++;
sout = SCTP_SO(&asoc->stream, chk->sinfo.sinfo_stream);
sout->ext->abandoned_unsent[SCTP_PR_INDEX(PRIO)]++;
/* clear out_curr if all frag chunks are pruned */
if (asoc->stream.out_curr == sout &&
list_is_last(&chk->frag_list, &chk->msg->chunks))
asoc->stream.out_curr = NULL;
msg_len -= chk->skb->truesize + sizeof(struct sctp_chunk);
sctp_chunk_free(chk);
if (msg_len <= 0)
break;
}
q->sched->sched_all(&asoc->stream);
return msg_len;
}
/* Abandon the chunks according their priorities */
void sctp_prsctp_prune(struct sctp_association *asoc,
struct sctp_sndrcvinfo *sinfo, int msg_len)
{
struct sctp_transport *transport;
if (!asoc->peer.prsctp_capable || !asoc->sent_cnt_removable)
return;
msg_len = sctp_prsctp_prune_sent(asoc, sinfo,
&asoc->outqueue.retransmit,
msg_len);
if (msg_len <= 0)
return;
list_for_each_entry(transport, &asoc->peer.transport_addr_list,
transports) {
msg_len = sctp_prsctp_prune_sent(asoc, sinfo,
&transport->transmitted,
msg_len);
if (msg_len <= 0)
return;
}
sctp_prsctp_prune_unsent(asoc, sinfo, msg_len);
}
/* Mark all the eligible packets on a transport for retransmission. */
void sctp_retransmit_mark(struct sctp_outq *q,
struct sctp_transport *transport,
__u8 reason)
{
struct list_head *lchunk, *ltemp;
struct sctp_chunk *chunk;
/* Walk through the specified transmitted queue. */
list_for_each_safe(lchunk, ltemp, &transport->transmitted) {
chunk = list_entry(lchunk, struct sctp_chunk,
transmitted_list);
/* If the chunk is abandoned, move it to abandoned list. */
if (sctp_chunk_abandoned(chunk)) {
list_del_init(lchunk);
sctp_insert_list(&q->abandoned, lchunk);
/* If this chunk has not been previousely acked,
* stop considering it 'outstanding'. Our peer
* will most likely never see it since it will
* not be retransmitted
*/
if (!chunk->tsn_gap_acked) {
if (chunk->transport)
chunk->transport->flight_size -=
sctp_data_size(chunk);
q->outstanding_bytes -= sctp_data_size(chunk);
q->asoc->peer.rwnd += sctp_data_size(chunk);
}
continue;
}
/* If we are doing retransmission due to a timeout or pmtu
* discovery, only the chunks that are not yet acked should
* be added to the retransmit queue.
*/
if ((reason == SCTP_RTXR_FAST_RTX &&
(chunk->fast_retransmit == SCTP_NEED_FRTX)) ||
(reason != SCTP_RTXR_FAST_RTX && !chunk->tsn_gap_acked)) {
/* RFC 2960 6.2.1 Processing a Received SACK
*
* C) Any time a DATA chunk is marked for
* retransmission (via either T3-rtx timer expiration
* (Section 6.3.3) or via fast retransmit
* (Section 7.2.4)), add the data size of those
* chunks to the rwnd.
*/
q->asoc->peer.rwnd += sctp_data_size(chunk);
q->outstanding_bytes -= sctp_data_size(chunk);
if (chunk->transport)
transport->flight_size -= sctp_data_size(chunk);
/* sctpimpguide-05 Section 2.8.2
* M5) If a T3-rtx timer expires, the
* 'TSN.Missing.Report' of all affected TSNs is set
* to 0.
*/
chunk->tsn_missing_report = 0;
/* If a chunk that is being used for RTT measurement
* has to be retransmitted, we cannot use this chunk
* anymore for RTT measurements. Reset rto_pending so
* that a new RTT measurement is started when a new
* data chunk is sent.
*/
if (chunk->rtt_in_progress) {
chunk->rtt_in_progress = 0;
transport->rto_pending = 0;
}
/* Move the chunk to the retransmit queue. The chunks
* on the retransmit queue are always kept in order.
*/
list_del_init(lchunk);
sctp_insert_list(&q->retransmit, lchunk);
}
}
pr_debug("%s: transport:%p, reason:%d, cwnd:%d, ssthresh:%d, "
"flight_size:%d, pba:%d\n", __func__, transport, reason,
transport->cwnd, transport->ssthresh, transport->flight_size,
transport->partial_bytes_acked);
}
/* Mark all the eligible packets on a transport for retransmission and force
* one packet out.
*/
void sctp_retransmit(struct sctp_outq *q, struct sctp_transport *transport,
enum sctp_retransmit_reason reason)
{
struct net *net = q->asoc->base.net;
switch (reason) {
case SCTP_RTXR_T3_RTX:
SCTP_INC_STATS(net, SCTP_MIB_T3_RETRANSMITS);
sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_T3_RTX);
/* Update the retran path if the T3-rtx timer has expired for
* the current retran path.
*/
if (transport == transport->asoc->peer.retran_path)
sctp_assoc_update_retran_path(transport->asoc);
transport->asoc->rtx_data_chunks +=
transport->asoc->unack_data;
if (transport->pl.state == SCTP_PL_COMPLETE &&
transport->asoc->unack_data)
sctp_transport_reset_probe_timer(transport);
break;
case SCTP_RTXR_FAST_RTX:
SCTP_INC_STATS(net, SCTP_MIB_FAST_RETRANSMITS);
sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_FAST_RTX);
q->fast_rtx = 1;
break;
case SCTP_RTXR_PMTUD:
SCTP_INC_STATS(net, SCTP_MIB_PMTUD_RETRANSMITS);
break;
case SCTP_RTXR_T1_RTX:
SCTP_INC_STATS(net, SCTP_MIB_T1_RETRANSMITS);
transport->asoc->init_retries++;
break;
default:
BUG();
}
sctp_retransmit_mark(q, transport, reason);
/* PR-SCTP A5) Any time the T3-rtx timer expires, on any destination,
* the sender SHOULD try to advance the "Advanced.Peer.Ack.Point" by
* following the procedures outlined in C1 - C5.
*/
if (reason == SCTP_RTXR_T3_RTX)
q->asoc->stream.si->generate_ftsn(q, q->asoc->ctsn_ack_point);
/* Flush the queues only on timeout, since fast_rtx is only
* triggered during sack processing and the queue
* will be flushed at the end.
*/
if (reason != SCTP_RTXR_FAST_RTX)
sctp_outq_flush(q, /* rtx_timeout */ 1, GFP_ATOMIC);
}
/*
* Transmit DATA chunks on the retransmit queue. Upon return from
* __sctp_outq_flush_rtx() the packet 'pkt' may contain chunks which
* need to be transmitted by the caller.
* We assume that pkt->transport has already been set.
*
* The return value is a normal kernel error return value.
*/
static int __sctp_outq_flush_rtx(struct sctp_outq *q, struct sctp_packet *pkt,
int rtx_timeout, int *start_timer, gfp_t gfp)
{
struct sctp_transport *transport = pkt->transport;
struct sctp_chunk *chunk, *chunk1;
struct list_head *lqueue;
enum sctp_xmit status;
int error = 0;
int timer = 0;
int done = 0;
int fast_rtx;
lqueue = &q->retransmit;
fast_rtx = q->fast_rtx;
/* This loop handles time-out retransmissions, fast retransmissions,
* and retransmissions due to opening of whindow.
*
* RFC 2960 6.3.3 Handle T3-rtx Expiration
*
* E3) Determine how many of the earliest (i.e., lowest TSN)
* outstanding DATA chunks for the address for which the
* T3-rtx has expired will fit into a single packet, subject
* to the MTU constraint for the path corresponding to the
* destination transport address to which the retransmission
* is being sent (this may be different from the address for
* which the timer expires [see Section 6.4]). Call this value
* K. Bundle and retransmit those K DATA chunks in a single
* packet to the destination endpoint.
*
* [Just to be painfully clear, if we are retransmitting
* because a timeout just happened, we should send only ONE
* packet of retransmitted data.]
*
* For fast retransmissions we also send only ONE packet. However,
* if we are just flushing the queue due to open window, we'll
* try to send as much as possible.
*/
list_for_each_entry_safe(chunk, chunk1, lqueue, transmitted_list) {
/* If the chunk is abandoned, move it to abandoned list. */
if (sctp_chunk_abandoned(chunk)) {
list_del_init(&chunk->transmitted_list);
sctp_insert_list(&q->abandoned,
&chunk->transmitted_list);
continue;
}
/* Make sure that Gap Acked TSNs are not retransmitted. A
* simple approach is just to move such TSNs out of the
* way and into a 'transmitted' queue and skip to the
* next chunk.
*/
if (chunk->tsn_gap_acked) {
list_move_tail(&chunk->transmitted_list,
&transport->transmitted);
continue;
}
/* If we are doing fast retransmit, ignore non-fast_rtransmit
* chunks
*/
if (fast_rtx && !chunk->fast_retransmit)
continue;
redo:
/* Attempt to append this chunk to the packet. */
status = sctp_packet_append_chunk(pkt, chunk);
switch (status) {
case SCTP_XMIT_PMTU_FULL:
if (!pkt->has_data && !pkt->has_cookie_echo) {
/* If this packet did not contain DATA then
* retransmission did not happen, so do it
* again. We'll ignore the error here since
* control chunks are already freed so there
* is nothing we can do.
*/
sctp_packet_transmit(pkt, gfp);
goto redo;
}
/* Send this packet. */
error = sctp_packet_transmit(pkt, gfp);
/* If we are retransmitting, we should only
* send a single packet.
* Otherwise, try appending this chunk again.
*/
if (rtx_timeout || fast_rtx)
done = 1;
else
goto redo;
/* Bundle next chunk in the next round. */
break;
case SCTP_XMIT_RWND_FULL:
/* Send this packet. */
error = sctp_packet_transmit(pkt, gfp);
/* Stop sending DATA as there is no more room
* at the receiver.
*/
done = 1;
break;
case SCTP_XMIT_DELAY:
/* Send this packet. */
error = sctp_packet_transmit(pkt, gfp);
/* Stop sending DATA because of nagle delay. */
done = 1;
break;
default:
/* The append was successful, so add this chunk to
* the transmitted list.
*/
list_move_tail(&chunk->transmitted_list,
&transport->transmitted);
/* Mark the chunk as ineligible for fast retransmit
* after it is retransmitted.
*/
if (chunk->fast_retransmit == SCTP_NEED_FRTX)
chunk->fast_retransmit = SCTP_DONT_FRTX;
q->asoc->stats.rtxchunks++;
break;
}
/* Set the timer if there were no errors */
if (!error && !timer)
timer = 1;
if (done)
break;
}
/* If we are here due to a retransmit timeout or a fast
* retransmit and if there are any chunks left in the retransmit
* queue that could not fit in the PMTU sized packet, they need
* to be marked as ineligible for a subsequent fast retransmit.
*/
if (rtx_timeout || fast_rtx) {
list_for_each_entry(chunk1, lqueue, transmitted_list) {
if (chunk1->fast_retransmit == SCTP_NEED_FRTX)
chunk1->fast_retransmit = SCTP_DONT_FRTX;
}
}
*start_timer = timer;
/* Clear fast retransmit hint */
if (fast_rtx)
q->fast_rtx = 0;
return error;
}
/* Cork the outqueue so queued chunks are really queued. */
void sctp_outq_uncork(struct sctp_outq *q, gfp_t gfp)
{
if (q->cork)
q->cork = 0;
sctp_outq_flush(q, 0, gfp);
}
static int sctp_packet_singleton(struct sctp_transport *transport,
struct sctp_chunk *chunk, gfp_t gfp)
{
const struct sctp_association *asoc = transport->asoc;
const __u16 sport = asoc->base.bind_addr.port;
const __u16 dport = asoc->peer.port;
const __u32 vtag = asoc->peer.i.init_tag;
struct sctp_packet singleton;
sctp_packet_init(&singleton, transport, sport, dport);
sctp_packet_config(&singleton, vtag, 0);
if (sctp_packet_append_chunk(&singleton, chunk) != SCTP_XMIT_OK) {
list_del_init(&chunk->list);
sctp_chunk_free(chunk);
return -ENOMEM;
}
return sctp_packet_transmit(&singleton, gfp);
}
/* Struct to hold the context during sctp outq flush */
struct sctp_flush_ctx {
struct sctp_outq *q;
/* Current transport being used. It's NOT the same as curr active one */
struct sctp_transport *transport;
/* These transports have chunks to send. */
struct list_head transport_list;
struct sctp_association *asoc;
/* Packet on the current transport above */
struct sctp_packet *packet;
gfp_t gfp;
};
/* transport: current transport */
static void sctp_outq_select_transport(struct sctp_flush_ctx *ctx,
struct sctp_chunk *chunk)
{
struct sctp_transport *new_transport = chunk->transport;
if (!new_transport) {
if (!sctp_chunk_is_data(chunk)) {
/* If we have a prior transport pointer, see if
* the destination address of the chunk
* matches the destination address of the
* current transport. If not a match, then
* try to look up the transport with a given
* destination address. We do this because
* after processing ASCONFs, we may have new
* transports created.
*/
if (ctx->transport && sctp_cmp_addr_exact(&chunk->dest,
&ctx->transport->ipaddr))
new_transport = ctx->transport;
else
new_transport = sctp_assoc_lookup_paddr(ctx->asoc,
&chunk->dest);
}
/* if we still don't have a new transport, then
* use the current active path.
*/
if (!new_transport)
new_transport = ctx->asoc->peer.active_path;
} else {
__u8 type;
switch (new_transport->state) {
case SCTP_INACTIVE:
case SCTP_UNCONFIRMED:
case SCTP_PF:
/* If the chunk is Heartbeat or Heartbeat Ack,
* send it to chunk->transport, even if it's
* inactive.
*
* 3.3.6 Heartbeat Acknowledgement:
* ...
* A HEARTBEAT ACK is always sent to the source IP
* address of the IP datagram containing the
* HEARTBEAT chunk to which this ack is responding.
* ...
*
* ASCONF_ACKs also must be sent to the source.
*/
type = chunk->chunk_hdr->type;
if (type != SCTP_CID_HEARTBEAT &&
type != SCTP_CID_HEARTBEAT_ACK &&
type != SCTP_CID_ASCONF_ACK)
new_transport = ctx->asoc->peer.active_path;
break;
default:
break;
}
}
/* Are we switching transports? Take care of transport locks. */
if (new_transport != ctx->transport) {
ctx->transport = new_transport;
ctx->packet = &ctx->transport->packet;
if (list_empty(&ctx->transport->send_ready))
list_add_tail(&ctx->transport->send_ready,
&ctx->transport_list);
sctp_packet_config(ctx->packet,
ctx->asoc->peer.i.init_tag,
ctx->asoc->peer.ecn_capable);
/* We've switched transports, so apply the
* Burst limit to the new transport.
*/
sctp_transport_burst_limited(ctx->transport);
}
}
static void sctp_outq_flush_ctrl(struct sctp_flush_ctx *ctx)
{
struct sctp_chunk *chunk, *tmp;
enum sctp_xmit status;
int one_packet, error;
list_for_each_entry_safe(chunk, tmp, &ctx->q->control_chunk_list, list) {
one_packet = 0;
/* RFC 5061, 5.3
* F1) This means that until such time as the ASCONF
* containing the add is acknowledged, the sender MUST
* NOT use the new IP address as a source for ANY SCTP
* packet except on carrying an ASCONF Chunk.
*/
if (ctx->asoc->src_out_of_asoc_ok &&
chunk->chunk_hdr->type != SCTP_CID_ASCONF)
continue;
list_del_init(&chunk->list);
/* Pick the right transport to use. Should always be true for
* the first chunk as we don't have a transport by then.
*/
sctp_outq_select_transport(ctx, chunk);
switch (chunk->chunk_hdr->type) {
/* 6.10 Bundling
* ...
* An endpoint MUST NOT bundle INIT, INIT ACK or SHUTDOWN
* COMPLETE with any other chunks. [Send them immediately.]
*/
case SCTP_CID_INIT:
case SCTP_CID_INIT_ACK:
case SCTP_CID_SHUTDOWN_COMPLETE:
error = sctp_packet_singleton(ctx->transport, chunk,
ctx->gfp);
if (error < 0) {
ctx->asoc->base.sk->sk_err = -error;
return;
}
ctx->asoc->stats.octrlchunks++;
break;
case SCTP_CID_ABORT:
if (sctp_test_T_bit(chunk))
ctx->packet->vtag = ctx->asoc->c.my_vtag;
fallthrough;
/* The following chunks are "response" chunks, i.e.
* they are generated in response to something we
* received. If we are sending these, then we can
* send only 1 packet containing these chunks.
*/
case SCTP_CID_HEARTBEAT_ACK:
case SCTP_CID_SHUTDOWN_ACK:
case SCTP_CID_COOKIE_ACK:
case SCTP_CID_COOKIE_ECHO:
case SCTP_CID_ERROR:
case SCTP_CID_ECN_CWR:
case SCTP_CID_ASCONF_ACK:
one_packet = 1;
fallthrough;
case SCTP_CID_HEARTBEAT:
if (chunk->pmtu_probe) {
error = sctp_packet_singleton(ctx->transport,
chunk, ctx->gfp);
if (!error)
ctx->asoc->stats.octrlchunks++;
break;
}
fallthrough;
case SCTP_CID_SACK:
case SCTP_CID_SHUTDOWN:
case SCTP_CID_ECN_ECNE:
case SCTP_CID_ASCONF:
case SCTP_CID_FWD_TSN:
case SCTP_CID_I_FWD_TSN:
case SCTP_CID_RECONF:
status = sctp_packet_transmit_chunk(ctx->packet, chunk,
one_packet, ctx->gfp);
if (status != SCTP_XMIT_OK) {
/* put the chunk back */
list_add(&chunk->list, &ctx->q->control_chunk_list);
break;
}
ctx->asoc->stats.octrlchunks++;
/* PR-SCTP C5) If a FORWARD TSN is sent, the
* sender MUST assure that at least one T3-rtx
* timer is running.
*/
if (chunk->chunk_hdr->type == SCTP_CID_FWD_TSN ||
chunk->chunk_hdr->type == SCTP_CID_I_FWD_TSN) {
sctp_transport_reset_t3_rtx(ctx->transport);
ctx->transport->last_time_sent = jiffies;
}
if (chunk == ctx->asoc->strreset_chunk)
sctp_transport_reset_reconf_timer(ctx->transport);
break;
default:
/* We built a chunk with an illegal type! */
BUG();
}
}
}
/* Returns false if new data shouldn't be sent */
static bool sctp_outq_flush_rtx(struct sctp_flush_ctx *ctx,
int rtx_timeout)
{
int error, start_timer = 0;
if (ctx->asoc->peer.retran_path->state == SCTP_UNCONFIRMED)
return false;
if (ctx->transport != ctx->asoc->peer.retran_path) {
/* Switch transports & prepare the packet. */
ctx->transport = ctx->asoc->peer.retran_path;
ctx->packet = &ctx->transport->packet;
if (list_empty(&ctx->transport->send_ready))
list_add_tail(&ctx->transport->send_ready,
&ctx->transport_list);
sctp_packet_config(ctx->packet, ctx->asoc->peer.i.init_tag,
ctx->asoc->peer.ecn_capable);
}
error = __sctp_outq_flush_rtx(ctx->q, ctx->packet, rtx_timeout,
&start_timer, ctx->gfp);
if (error < 0)
ctx->asoc->base.sk->sk_err = -error;
if (start_timer) {
sctp_transport_reset_t3_rtx(ctx->transport);
ctx->transport->last_time_sent = jiffies;
}
/* This can happen on COOKIE-ECHO resend. Only
* one chunk can get bundled with a COOKIE-ECHO.
*/
if (ctx->packet->has_cookie_echo)
return false;
/* Don't send new data if there is still data
* waiting to retransmit.
*/
if (!list_empty(&ctx->q->retransmit))
return false;
return true;
}
static void sctp_outq_flush_data(struct sctp_flush_ctx *ctx,
int rtx_timeout)
{
struct sctp_chunk *chunk;
enum sctp_xmit status;
/* Is it OK to send data chunks? */
switch (ctx->asoc->state) {
case SCTP_STATE_COOKIE_ECHOED:
/* Only allow bundling when this packet has a COOKIE-ECHO
* chunk.
*/
if (!ctx->packet || !ctx->packet->has_cookie_echo)
return;
fallthrough;
case SCTP_STATE_ESTABLISHED:
case SCTP_STATE_SHUTDOWN_PENDING:
case SCTP_STATE_SHUTDOWN_RECEIVED:
break;
default:
/* Do nothing. */
return;
}
/* RFC 2960 6.1 Transmission of DATA Chunks
*
* C) When the time comes for the sender to transmit,
* before sending new DATA chunks, the sender MUST
* first transmit any outstanding DATA chunks which
* are marked for retransmission (limited by the
* current cwnd).
*/
if (!list_empty(&ctx->q->retransmit) &&
!sctp_outq_flush_rtx(ctx, rtx_timeout))
return;
/* Apply Max.Burst limitation to the current transport in
* case it will be used for new data. We are going to
* rest it before we return, but we want to apply the limit
* to the currently queued data.
*/
if (ctx->transport)
sctp_transport_burst_limited(ctx->transport);
/* Finally, transmit new packets. */
while ((chunk = sctp_outq_dequeue_data(ctx->q)) != NULL) {
__u32 sid = ntohs(chunk->subh.data_hdr->stream);
__u8 stream_state = SCTP_SO(&ctx->asoc->stream, sid)->state;
/* Has this chunk expired? */
if (sctp_chunk_abandoned(chunk)) {
sctp_sched_dequeue_done(ctx->q, chunk);
sctp_chunk_fail(chunk, 0);
sctp_chunk_free(chunk);
continue;
}
if (stream_state == SCTP_STREAM_CLOSED) {
sctp_outq_head_data(ctx->q, chunk);
break;
}
sctp_outq_select_transport(ctx, chunk);
pr_debug("%s: outq:%p, chunk:%p[%s], tx-tsn:0x%x skb->head:%p skb->users:%d\n",
__func__, ctx->q, chunk, chunk && chunk->chunk_hdr ?
sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)) :
"illegal chunk", ntohl(chunk->subh.data_hdr->tsn),
chunk->skb ? chunk->skb->head : NULL, chunk->skb ?
refcount_read(&chunk->skb->users) : -1);
/* Add the chunk to the packet. */
status = sctp_packet_transmit_chunk(ctx->packet, chunk, 0,
ctx->gfp);
if (status != SCTP_XMIT_OK) {
/* We could not append this chunk, so put
* the chunk back on the output queue.
*/
pr_debug("%s: could not transmit tsn:0x%x, status:%d\n",
__func__, ntohl(chunk->subh.data_hdr->tsn),
status);
sctp_outq_head_data(ctx->q, chunk);
break;
}
/* The sender is in the SHUTDOWN-PENDING state,
* The sender MAY set the I-bit in the DATA
* chunk header.
*/
if (ctx->asoc->state == SCTP_STATE_SHUTDOWN_PENDING)
chunk->chunk_hdr->flags |= SCTP_DATA_SACK_IMM;
if (chunk->chunk_hdr->flags & SCTP_DATA_UNORDERED)
ctx->asoc->stats.ouodchunks++;
else
ctx->asoc->stats.oodchunks++;
/* Only now it's safe to consider this
* chunk as sent, sched-wise.
*/
sctp_sched_dequeue_done(ctx->q, chunk);
list_add_tail(&chunk->transmitted_list,
&ctx->transport->transmitted);
sctp_transport_reset_t3_rtx(ctx->transport);
ctx->transport->last_time_sent = jiffies;
/* Only let one DATA chunk get bundled with a
* COOKIE-ECHO chunk.
*/
if (ctx->packet->has_cookie_echo)
break;
}
}
static void sctp_outq_flush_transports(struct sctp_flush_ctx *ctx)
{
struct sock *sk = ctx->asoc->base.sk;
struct list_head *ltransport;
struct sctp_packet *packet;
struct sctp_transport *t;
int error = 0;
while ((ltransport = sctp_list_dequeue(&ctx->transport_list)) != NULL) {
t = list_entry(ltransport, struct sctp_transport, send_ready);
packet = &t->packet;
if (!sctp_packet_empty(packet)) {
rcu_read_lock();
if (t->dst && __sk_dst_get(sk) != t->dst) {
dst_hold(t->dst);
sk_setup_caps(sk, t->dst);
}
rcu_read_unlock();
error = sctp_packet_transmit(packet, ctx->gfp);
if (error < 0)
ctx->q->asoc->base.sk->sk_err = -error;
}
/* Clear the burst limited state, if any */
sctp_transport_burst_reset(t);
}
}
/* Try to flush an outqueue.
*
* Description: Send everything in q which we legally can, subject to
* congestion limitations.
* * Note: This function can be called from multiple contexts so appropriate
* locking concerns must be made. Today we use the sock lock to protect
* this function.
*/
static void sctp_outq_flush(struct sctp_outq *q, int rtx_timeout, gfp_t gfp)
{
struct sctp_flush_ctx ctx = {
.q = q,
.transport = NULL,
.transport_list = LIST_HEAD_INIT(ctx.transport_list),
.asoc = q->asoc,
.packet = NULL,
.gfp = gfp,
};
/* 6.10 Bundling
* ...
* When bundling control chunks with DATA chunks, an
* endpoint MUST place control chunks first in the outbound
* SCTP packet. The transmitter MUST transmit DATA chunks
* within a SCTP packet in increasing order of TSN.
* ...
*/
sctp_outq_flush_ctrl(&ctx);
if (q->asoc->src_out_of_asoc_ok)
goto sctp_flush_out;
sctp_outq_flush_data(&ctx, rtx_timeout);
sctp_flush_out:
sctp_outq_flush_transports(&ctx);
}
/* Update unack_data based on the incoming SACK chunk */
static void sctp_sack_update_unack_data(struct sctp_association *assoc,
struct sctp_sackhdr *sack)
{
union sctp_sack_variable *frags;
__u16 unack_data;
int i;
unack_data = assoc->next_tsn - assoc->ctsn_ack_point - 1;
frags = sack->variable;
for (i = 0; i < ntohs(sack->num_gap_ack_blocks); i++) {
unack_data -= ((ntohs(frags[i].gab.end) -
ntohs(frags[i].gab.start) + 1));
}
assoc->unack_data = unack_data;
}
/* This is where we REALLY process a SACK.
*
* Process the SACK against the outqueue. Mostly, this just frees
* things off the transmitted queue.
*/
int sctp_outq_sack(struct sctp_outq *q, struct sctp_chunk *chunk)
{
struct sctp_association *asoc = q->asoc;
struct sctp_sackhdr *sack = chunk->subh.sack_hdr;
struct sctp_transport *transport;
struct sctp_chunk *tchunk = NULL;
struct list_head *lchunk, *transport_list, *temp;
union sctp_sack_variable *frags = sack->variable;
__u32 sack_ctsn, ctsn, tsn;
__u32 highest_tsn, highest_new_tsn;
__u32 sack_a_rwnd;
unsigned int outstanding;
struct sctp_transport *primary = asoc->peer.primary_path;
int count_of_newacks = 0;
int gap_ack_blocks;
u8 accum_moved = 0;
/* Grab the association's destination address list. */
transport_list = &asoc->peer.transport_addr_list;
/* SCTP path tracepoint for congestion control debugging. */
if (trace_sctp_probe_path_enabled()) {
list_for_each_entry(transport, transport_list, transports)
trace_sctp_probe_path(transport, asoc);
}
sack_ctsn = ntohl(sack->cum_tsn_ack);
gap_ack_blocks = ntohs(sack->num_gap_ack_blocks);
asoc->stats.gapcnt += gap_ack_blocks;
/*
* SFR-CACC algorithm:
* On receipt of a SACK the sender SHOULD execute the
* following statements.
*
* 1) If the cumulative ack in the SACK passes next tsn_at_change
* on the current primary, the CHANGEOVER_ACTIVE flag SHOULD be
* cleared. The CYCLING_CHANGEOVER flag SHOULD also be cleared for
* all destinations.
* 2) If the SACK contains gap acks and the flag CHANGEOVER_ACTIVE
* is set the receiver of the SACK MUST take the following actions:
*
* A) Initialize the cacc_saw_newack to 0 for all destination
* addresses.
*
* Only bother if changeover_active is set. Otherwise, this is
* totally suboptimal to do on every SACK.
*/
if (primary->cacc.changeover_active) {
u8 clear_cycling = 0;
if (TSN_lte(primary->cacc.next_tsn_at_change, sack_ctsn)) {
primary->cacc.changeover_active = 0;
clear_cycling = 1;
}
if (clear_cycling || gap_ack_blocks) {
list_for_each_entry(transport, transport_list,
transports) {
if (clear_cycling)
transport->cacc.cycling_changeover = 0;
if (gap_ack_blocks)
transport->cacc.cacc_saw_newack = 0;
}
}
}
/* Get the highest TSN in the sack. */
highest_tsn = sack_ctsn;
if (gap_ack_blocks)
highest_tsn += ntohs(frags[gap_ack_blocks - 1].gab.end);
if (TSN_lt(asoc->highest_sacked, highest_tsn))
asoc->highest_sacked = highest_tsn;
highest_new_tsn = sack_ctsn;
/* Run through the retransmit queue. Credit bytes received
* and free those chunks that we can.
*/
sctp_check_transmitted(q, &q->retransmit, NULL, NULL, sack, &highest_new_tsn);
/* Run through the transmitted queue.
* Credit bytes received and free those chunks which we can.
*
* This is a MASSIVE candidate for optimization.
*/
list_for_each_entry(transport, transport_list, transports) {
sctp_check_transmitted(q, &transport->transmitted,
transport, &chunk->source, sack,
&highest_new_tsn);
/*
* SFR-CACC algorithm:
* C) Let count_of_newacks be the number of
* destinations for which cacc_saw_newack is set.
*/
if (transport->cacc.cacc_saw_newack)
count_of_newacks++;
}
/* Move the Cumulative TSN Ack Point if appropriate. */
if (TSN_lt(asoc->ctsn_ack_point, sack_ctsn)) {
asoc->ctsn_ack_point = sack_ctsn;
accum_moved = 1;
}
if (gap_ack_blocks) {
if (asoc->fast_recovery && accum_moved)
highest_new_tsn = highest_tsn;
list_for_each_entry(transport, transport_list, transports)
sctp_mark_missing(q, &transport->transmitted, transport,
highest_new_tsn, count_of_newacks);
}
/* Update unack_data field in the assoc. */
sctp_sack_update_unack_data(asoc, sack);
ctsn = asoc->ctsn_ack_point;
/* Throw away stuff rotting on the sack queue. */
list_for_each_safe(lchunk, temp, &q->sacked) {
tchunk = list_entry(lchunk, struct sctp_chunk,
transmitted_list);
tsn = ntohl(tchunk->subh.data_hdr->tsn);
if (TSN_lte(tsn, ctsn)) {
list_del_init(&tchunk->transmitted_list);
if (asoc->peer.prsctp_capable &&
SCTP_PR_PRIO_ENABLED(chunk->sinfo.sinfo_flags))
asoc->sent_cnt_removable--;
sctp_chunk_free(tchunk);
}
}
/* ii) Set rwnd equal to the newly received a_rwnd minus the
* number of bytes still outstanding after processing the
* Cumulative TSN Ack and the Gap Ack Blocks.
*/
sack_a_rwnd = ntohl(sack->a_rwnd);
asoc->peer.zero_window_announced = !sack_a_rwnd;
outstanding = q->outstanding_bytes;
if (outstanding < sack_a_rwnd)
sack_a_rwnd -= outstanding;
else
sack_a_rwnd = 0;
asoc->peer.rwnd = sack_a_rwnd;
asoc->stream.si->generate_ftsn(q, sack_ctsn);
pr_debug("%s: sack cumulative tsn ack:0x%x\n", __func__, sack_ctsn);
pr_debug("%s: cumulative tsn ack of assoc:%p is 0x%x, "
"advertised peer ack point:0x%x\n", __func__, asoc, ctsn,
asoc->adv_peer_ack_point);
return sctp_outq_is_empty(q);
}
/* Is the outqueue empty?
* The queue is empty when we have not pending data, no in-flight data
* and nothing pending retransmissions.
*/
int sctp_outq_is_empty(const struct sctp_outq *q)
{
return q->out_qlen == 0 && q->outstanding_bytes == 0 &&
list_empty(&q->retransmit);
}
/********************************************************************
* 2nd Level Abstractions
********************************************************************/
/* Go through a transport's transmitted list or the association's retransmit
* list and move chunks that are acked by the Cumulative TSN Ack to q->sacked.
* The retransmit list will not have an associated transport.
*
* I added coherent debug information output. --xguo
*
* Instead of printing 'sacked' or 'kept' for each TSN on the
* transmitted_queue, we print a range: SACKED: TSN1-TSN2, TSN3, TSN4-TSN5.
* KEPT TSN6-TSN7, etc.
*/
static void sctp_check_transmitted(struct sctp_outq *q,
struct list_head *transmitted_queue,
struct sctp_transport *transport,
union sctp_addr *saddr,
struct sctp_sackhdr *sack,
__u32 *highest_new_tsn_in_sack)
{
struct list_head *lchunk;
struct sctp_chunk *tchunk;
struct list_head tlist;
__u32 tsn;
__u32 sack_ctsn;
__u32 rtt;
__u8 restart_timer = 0;
int bytes_acked = 0;
int migrate_bytes = 0;
bool forward_progress = false;
sack_ctsn = ntohl(sack->cum_tsn_ack);
INIT_LIST_HEAD(&tlist);
/* The while loop will skip empty transmitted queues. */
while (NULL != (lchunk = sctp_list_dequeue(transmitted_queue))) {
tchunk = list_entry(lchunk, struct sctp_chunk,
transmitted_list);
if (sctp_chunk_abandoned(tchunk)) {
/* Move the chunk to abandoned list. */
sctp_insert_list(&q->abandoned, lchunk);
/* If this chunk has not been acked, stop
* considering it as 'outstanding'.
*/
if (transmitted_queue != &q->retransmit &&
!tchunk->tsn_gap_acked) {
if (tchunk->transport)
tchunk->transport->flight_size -=
sctp_data_size(tchunk);
q->outstanding_bytes -= sctp_data_size(tchunk);
}
continue;
}
tsn = ntohl(tchunk->subh.data_hdr->tsn);
if (sctp_acked(sack, tsn)) {
/* If this queue is the retransmit queue, the
* retransmit timer has already reclaimed
* the outstanding bytes for this chunk, so only
* count bytes associated with a transport.
*/
if (transport && !tchunk->tsn_gap_acked) {
/* If this chunk is being used for RTT
* measurement, calculate the RTT and update
* the RTO using this value.
*
* 6.3.1 C5) Karn's algorithm: RTT measurements
* MUST NOT be made using packets that were
* retransmitted (and thus for which it is
* ambiguous whether the reply was for the
* first instance of the packet or a later
* instance).
*/
if (!sctp_chunk_retransmitted(tchunk) &&
tchunk->rtt_in_progress) {
tchunk->rtt_in_progress = 0;
rtt = jiffies - tchunk->sent_at;
sctp_transport_update_rto(transport,
rtt);
}
if (TSN_lte(tsn, sack_ctsn)) {
/*
* SFR-CACC algorithm:
* 2) If the SACK contains gap acks
* and the flag CHANGEOVER_ACTIVE is
* set the receiver of the SACK MUST
* take the following action:
*
* B) For each TSN t being acked that
* has not been acked in any SACK so
* far, set cacc_saw_newack to 1 for
* the destination that the TSN was
* sent to.
*/
if (sack->num_gap_ack_blocks &&
q->asoc->peer.primary_path->cacc.
changeover_active)
transport->cacc.cacc_saw_newack
= 1;
}
}
/* If the chunk hasn't been marked as ACKED,
* mark it and account bytes_acked if the
* chunk had a valid transport (it will not
* have a transport if ASCONF had deleted it
* while DATA was outstanding).
*/
if (!tchunk->tsn_gap_acked) {
tchunk->tsn_gap_acked = 1;
if (TSN_lt(*highest_new_tsn_in_sack, tsn))
*highest_new_tsn_in_sack = tsn;
bytes_acked += sctp_data_size(tchunk);
if (!tchunk->transport)
migrate_bytes += sctp_data_size(tchunk);
forward_progress = true;
}
if (TSN_lte(tsn, sack_ctsn)) {
/* RFC 2960 6.3.2 Retransmission Timer Rules
*
* R3) Whenever a SACK is received
* that acknowledges the DATA chunk
* with the earliest outstanding TSN
* for that address, restart T3-rtx
* timer for that address with its
* current RTO.
*/
restart_timer = 1;
forward_progress = true;
list_add_tail(&tchunk->transmitted_list,
&q->sacked);
} else {
/* RFC2960 7.2.4, sctpimpguide-05 2.8.2
* M2) Each time a SACK arrives reporting
* 'Stray DATA chunk(s)' record the highest TSN
* reported as newly acknowledged, call this
* value 'HighestTSNinSack'. A newly
* acknowledged DATA chunk is one not
* previously acknowledged in a SACK.
*
* When the SCTP sender of data receives a SACK
* chunk that acknowledges, for the first time,
* the receipt of a DATA chunk, all the still
* unacknowledged DATA chunks whose TSN is
* older than that newly acknowledged DATA
* chunk, are qualified as 'Stray DATA chunks'.
*/
list_add_tail(lchunk, &tlist);
}
} else {
if (tchunk->tsn_gap_acked) {
pr_debug("%s: receiver reneged on data TSN:0x%x\n",
__func__, tsn);
tchunk->tsn_gap_acked = 0;
if (tchunk->transport)
bytes_acked -= sctp_data_size(tchunk);
/* RFC 2960 6.3.2 Retransmission Timer Rules
*
* R4) Whenever a SACK is received missing a
* TSN that was previously acknowledged via a
* Gap Ack Block, start T3-rtx for the
* destination address to which the DATA
* chunk was originally
* transmitted if it is not already running.
*/
restart_timer = 1;
}
list_add_tail(lchunk, &tlist);
}
}
if (transport) {
if (bytes_acked) {
struct sctp_association *asoc = transport->asoc;
/* We may have counted DATA that was migrated
* to this transport due to DEL-IP operation.
* Subtract those bytes, since the were never
* send on this transport and shouldn't be
* credited to this transport.
*/
bytes_acked -= migrate_bytes;
/* 8.2. When an outstanding TSN is acknowledged,
* the endpoint shall clear the error counter of
* the destination transport address to which the
* DATA chunk was last sent.
* The association's overall error counter is
* also cleared.
*/
transport->error_count = 0;
transport->asoc->overall_error_count = 0;
forward_progress = true;
/*
* While in SHUTDOWN PENDING, we may have started
* the T5 shutdown guard timer after reaching the
* retransmission limit. Stop that timer as soon
* as the receiver acknowledged any data.
*/
if (asoc->state == SCTP_STATE_SHUTDOWN_PENDING &&
del_timer(&asoc->timers
[SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD]))
sctp_association_put(asoc);
/* Mark the destination transport address as
* active if it is not so marked.
*/
if ((transport->state == SCTP_INACTIVE ||
transport->state == SCTP_UNCONFIRMED) &&
sctp_cmp_addr_exact(&transport->ipaddr, saddr)) {
sctp_assoc_control_transport(
transport->asoc,
transport,
SCTP_TRANSPORT_UP,
SCTP_RECEIVED_SACK);
}
sctp_transport_raise_cwnd(transport, sack_ctsn,
bytes_acked);
transport->flight_size -= bytes_acked;
if (transport->flight_size == 0)
transport->partial_bytes_acked = 0;
q->outstanding_bytes -= bytes_acked + migrate_bytes;
} else {
/* RFC 2960 6.1, sctpimpguide-06 2.15.2
* When a sender is doing zero window probing, it
* should not timeout the association if it continues
* to receive new packets from the receiver. The
* reason is that the receiver MAY keep its window
* closed for an indefinite time.
* A sender is doing zero window probing when the
* receiver's advertised window is zero, and there is
* only one data chunk in flight to the receiver.
*
* Allow the association to timeout while in SHUTDOWN
* PENDING or SHUTDOWN RECEIVED in case the receiver
* stays in zero window mode forever.
*/
if (!q->asoc->peer.rwnd &&
!list_empty(&tlist) &&
(sack_ctsn+2 == q->asoc->next_tsn) &&
q->asoc->state < SCTP_STATE_SHUTDOWN_PENDING) {
pr_debug("%s: sack received for zero window "
"probe:%u\n", __func__, sack_ctsn);
q->asoc->overall_error_count = 0;
transport->error_count = 0;
}
}
/* RFC 2960 6.3.2 Retransmission Timer Rules
*
* R2) Whenever all outstanding data sent to an address have
* been acknowledged, turn off the T3-rtx timer of that
* address.
*/
if (!transport->flight_size) {
if (del_timer(&transport->T3_rtx_timer))
sctp_transport_put(transport);
} else if (restart_timer) {
if (!mod_timer(&transport->T3_rtx_timer,
jiffies + transport->rto))
sctp_transport_hold(transport);
}
if (forward_progress) {
if (transport->dst)
sctp_transport_dst_confirm(transport);
}
}
list_splice(&tlist, transmitted_queue);
}
/* Mark chunks as missing and consequently may get retransmitted. */
static void sctp_mark_missing(struct sctp_outq *q,
struct list_head *transmitted_queue,
struct sctp_transport *transport,
__u32 highest_new_tsn_in_sack,
int count_of_newacks)
{
struct sctp_chunk *chunk;
__u32 tsn;
char do_fast_retransmit = 0;
struct sctp_association *asoc = q->asoc;
struct sctp_transport *primary = asoc->peer.primary_path;
list_for_each_entry(chunk, transmitted_queue, transmitted_list) {
tsn = ntohl(chunk->subh.data_hdr->tsn);
/* RFC 2960 7.2.4, sctpimpguide-05 2.8.2 M3) Examine all
* 'Unacknowledged TSN's', if the TSN number of an
* 'Unacknowledged TSN' is smaller than the 'HighestTSNinSack'
* value, increment the 'TSN.Missing.Report' count on that
* chunk if it has NOT been fast retransmitted or marked for
* fast retransmit already.
*/
if (chunk->fast_retransmit == SCTP_CAN_FRTX &&
!chunk->tsn_gap_acked &&
TSN_lt(tsn, highest_new_tsn_in_sack)) {
/* SFR-CACC may require us to skip marking
* this chunk as missing.
*/
if (!transport || !sctp_cacc_skip(primary,
chunk->transport,
count_of_newacks, tsn)) {
chunk->tsn_missing_report++;
pr_debug("%s: tsn:0x%x missing counter:%d\n",
__func__, tsn, chunk->tsn_missing_report);
}
}
/*
* M4) If any DATA chunk is found to have a
* 'TSN.Missing.Report'
* value larger than or equal to 3, mark that chunk for
* retransmission and start the fast retransmit procedure.
*/
if (chunk->tsn_missing_report >= 3) {
chunk->fast_retransmit = SCTP_NEED_FRTX;
do_fast_retransmit = 1;
}
}
if (transport) {
if (do_fast_retransmit)
sctp_retransmit(q, transport, SCTP_RTXR_FAST_RTX);
pr_debug("%s: transport:%p, cwnd:%d, ssthresh:%d, "
"flight_size:%d, pba:%d\n", __func__, transport,
transport->cwnd, transport->ssthresh,
transport->flight_size, transport->partial_bytes_acked);
}
}
/* Is the given TSN acked by this packet? */
static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn)
{
__u32 ctsn = ntohl(sack->cum_tsn_ack);
union sctp_sack_variable *frags;
__u16 tsn_offset, blocks;
int i;
if (TSN_lte(tsn, ctsn))
goto pass;
/* 3.3.4 Selective Acknowledgment (SACK) (3):
*
* Gap Ack Blocks:
* These fields contain the Gap Ack Blocks. They are repeated
* for each Gap Ack Block up to the number of Gap Ack Blocks
* defined in the Number of Gap Ack Blocks field. All DATA
* chunks with TSNs greater than or equal to (Cumulative TSN
* Ack + Gap Ack Block Start) and less than or equal to
* (Cumulative TSN Ack + Gap Ack Block End) of each Gap Ack
* Block are assumed to have been received correctly.
*/
frags = sack->variable;
blocks = ntohs(sack->num_gap_ack_blocks);
tsn_offset = tsn - ctsn;
for (i = 0; i < blocks; ++i) {
if (tsn_offset >= ntohs(frags[i].gab.start) &&
tsn_offset <= ntohs(frags[i].gab.end))
goto pass;
}
return 0;
pass:
return 1;
}
static inline int sctp_get_skip_pos(struct sctp_fwdtsn_skip *skiplist,
int nskips, __be16 stream)
{
int i;
for (i = 0; i < nskips; i++) {
if (skiplist[i].stream == stream)
return i;
}
return i;
}
/* Create and add a fwdtsn chunk to the outq's control queue if needed. */
void sctp_generate_fwdtsn(struct sctp_outq *q, __u32 ctsn)
{
struct sctp_association *asoc = q->asoc;
struct sctp_chunk *ftsn_chunk = NULL;
struct sctp_fwdtsn_skip ftsn_skip_arr[10];
int nskips = 0;
int skip_pos = 0;
__u32 tsn;
struct sctp_chunk *chunk;
struct list_head *lchunk, *temp;
if (!asoc->peer.prsctp_capable)
return;
/* PR-SCTP C1) Let SackCumAck be the Cumulative TSN ACK carried in the
* received SACK.
*
* If (Advanced.Peer.Ack.Point < SackCumAck), then update
* Advanced.Peer.Ack.Point to be equal to SackCumAck.
*/
if (TSN_lt(asoc->adv_peer_ack_point, ctsn))
asoc->adv_peer_ack_point = ctsn;
/* PR-SCTP C2) Try to further advance the "Advanced.Peer.Ack.Point"
* locally, that is, to move "Advanced.Peer.Ack.Point" up as long as
* the chunk next in the out-queue space is marked as "abandoned" as
* shown in the following example:
*
* Assuming that a SACK arrived with the Cumulative TSN ACK 102
* and the Advanced.Peer.Ack.Point is updated to this value:
*
* out-queue at the end of ==> out-queue after Adv.Ack.Point
* normal SACK processing local advancement
* ... ...
* Adv.Ack.Pt-> 102 acked 102 acked
* 103 abandoned 103 abandoned
* 104 abandoned Adv.Ack.P-> 104 abandoned
* 105 105
* 106 acked 106 acked
* ... ...
*
* In this example, the data sender successfully advanced the
* "Advanced.Peer.Ack.Point" from 102 to 104 locally.
*/
list_for_each_safe(lchunk, temp, &q->abandoned) {
chunk = list_entry(lchunk, struct sctp_chunk,
transmitted_list);
tsn = ntohl(chunk->subh.data_hdr->tsn);
/* Remove any chunks in the abandoned queue that are acked by
* the ctsn.
*/
if (TSN_lte(tsn, ctsn)) {
list_del_init(lchunk);
sctp_chunk_free(chunk);
} else {
if (TSN_lte(tsn, asoc->adv_peer_ack_point+1)) {
asoc->adv_peer_ack_point = tsn;
if (chunk->chunk_hdr->flags &
SCTP_DATA_UNORDERED)
continue;
skip_pos = sctp_get_skip_pos(&ftsn_skip_arr[0],
nskips,
chunk->subh.data_hdr->stream);
ftsn_skip_arr[skip_pos].stream =
chunk->subh.data_hdr->stream;
ftsn_skip_arr[skip_pos].ssn =
chunk->subh.data_hdr->ssn;
if (skip_pos == nskips)
nskips++;
if (nskips == 10)
break;
} else
break;
}
}
/* PR-SCTP C3) If, after step C1 and C2, the "Advanced.Peer.Ack.Point"
* is greater than the Cumulative TSN ACK carried in the received
* SACK, the data sender MUST send the data receiver a FORWARD TSN
* chunk containing the latest value of the
* "Advanced.Peer.Ack.Point".
*
* C4) For each "abandoned" TSN the sender of the FORWARD TSN SHOULD
* list each stream and sequence number in the forwarded TSN. This
* information will enable the receiver to easily find any
* stranded TSN's waiting on stream reorder queues. Each stream
* SHOULD only be reported once; this means that if multiple
* abandoned messages occur in the same stream then only the
* highest abandoned stream sequence number is reported. If the
* total size of the FORWARD TSN does NOT fit in a single MTU then
* the sender of the FORWARD TSN SHOULD lower the
* Advanced.Peer.Ack.Point to the last TSN that will fit in a
* single MTU.
*/
if (asoc->adv_peer_ack_point > ctsn)
ftsn_chunk = sctp_make_fwdtsn(asoc, asoc->adv_peer_ack_point,
nskips, &ftsn_skip_arr[0]);
if (ftsn_chunk) {
list_add_tail(&ftsn_chunk->list, &q->control_chunk_list);
SCTP_INC_STATS(asoc->base.net, SCTP_MIB_OUTCTRLCHUNKS);
}
}
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