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outqueue.c
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/* 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.
*
* This SCTP implementation is free software;
* you can redistribute it and/or modify it under the terms of
* the GNU General Public License as published by
* the Free Software Foundation; either version 2, or (at your option)
* any later version.
*
* This SCTP implementation is distributed in the hope that it
* will be useful, but WITHOUT ANY WARRANTY; without even the implied
* ************************
* warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
* See the GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GNU CC; see the file COPYING. If not, write to
* the Free Software Foundation, 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*
* Please send any bug reports or fixes you make to the
* email address(es):
* lksctp developers <[email protected]>
*
* Or submit a bug report through the following website:
* http://www.sf.net/projects/lksctp
*
* Written or modified by:
* La Monte H.P. Yarroll <[email protected]>
* Karl Knutson <[email protected]>
* Perry Melange <[email protected]>
* Xingang Guo <[email protected]>
* Hui Huang <[email protected]>
* Sridhar Samudrala <[email protected]>
* Jon Grimm <[email protected]>
*
* Any bugs reported given to us we will try to fix... any fixes shared will
* be incorporated into the next SCTP release.
*/
#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>
/* 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,
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_generate_fwdtsn(struct sctp_outq *q, __u32 sack_ctsn);
static int sctp_outq_flush(struct sctp_outq *q, int rtx_timeout);
/* Add data to the front of the queue. */
static inline void sctp_outq_head_data(struct sctp_outq *q,
struct sctp_chunk *ch)
{
list_add(&ch->list, &q->out_chunk_list);
q->out_qlen += ch->skb->len;
}
/* Take data from the front of the queue. */
static inline struct sctp_chunk *sctp_outq_dequeue_data(struct sctp_outq *q)
{
struct sctp_chunk *ch = NULL;
if (!list_empty(&q->out_chunk_list)) {
struct list_head *entry = q->out_chunk_list.next;
ch = list_entry(entry, struct sctp_chunk, list);
list_del_init(entry);
q->out_qlen -= ch->skb->len;
}
return ch;
}
/* Add data chunk to the end of the queue. */
static inline void sctp_outq_tail_data(struct sctp_outq *q,
struct sctp_chunk *ch)
{
list_add_tail(&ch->list, &q->out_chunk_list);
q->out_qlen += ch->skb->len;
}
/*
* 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->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 futher 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 SOULD 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)
{
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);
q->fast_rtx = 0;
q->outstanding_bytes = 0;
q->empty = 1;
q->cork = 0;
q->malloced = 0;
q->out_qlen = 0;
}
/* Free the outqueue structure and any related pending chunks.
*/
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) {
/* Mark as send failure. */
sctp_chunk_fail(chunk, q->error);
sctp_chunk_free(chunk);
}
q->error = 0;
/* 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);
}
}
/* 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);
/* If we were kmalloc()'d, free the memory. */
if (q->malloced)
kfree(q);
}
/* Put a new chunk in an sctp_outq. */
int sctp_outq_tail(struct sctp_outq *q, struct sctp_chunk *chunk)
{
int error = 0;
SCTP_DEBUG_PRINTK("sctp_outq_tail(%p, %p[%s])\n",
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)) {
/* Is it OK to queue data chunks? */
/* From 9. Termination of Association
*
* When either endpoint performs a shutdown, the
* association on each peer will stop accepting new
* data from its user and only deliver data in queue
* at the time of sending or receiving the SHUTDOWN
* chunk.
*/
switch (q->asoc->state) {
case SCTP_STATE_EMPTY:
case SCTP_STATE_CLOSED:
case SCTP_STATE_SHUTDOWN_PENDING:
case SCTP_STATE_SHUTDOWN_SENT:
case SCTP_STATE_SHUTDOWN_RECEIVED:
case SCTP_STATE_SHUTDOWN_ACK_SENT:
/* Cannot send after transport endpoint shutdown */
error = -ESHUTDOWN;
break;
default:
SCTP_DEBUG_PRINTK("outqueueing (%p, %p[%s])\n",
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->chunk_hdr->flags & SCTP_DATA_UNORDERED)
SCTP_INC_STATS(SCTP_MIB_OUTUNORDERCHUNKS);
else
SCTP_INC_STATS(SCTP_MIB_OUTORDERCHUNKS);
q->empty = 0;
break;
}
} else {
list_add_tail(&chunk->list, &q->control_chunk_list);
SCTP_INC_STATS(SCTP_MIB_OUTCTRLCHUNKS);
}
if (error < 0)
return error;
if (!q->cork)
error = sctp_outq_flush(q, 0);
return error;
}
/* 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);
}
/* 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) +
sizeof(struct sk_buff));
}
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) +
sizeof(struct sk_buff));
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);
}
}
SCTP_DEBUG_PRINTK("%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,
sctp_retransmit_reason_t reason)
{
int error = 0;
switch(reason) {
case SCTP_RTXR_T3_RTX:
SCTP_INC_STATS(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;
break;
case SCTP_RTXR_FAST_RTX:
SCTP_INC_STATS(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(SCTP_MIB_PMTUD_RETRANSMITS);
break;
case SCTP_RTXR_T1_RTX:
SCTP_INC_STATS(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)
sctp_generate_fwdtsn(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)
error = sctp_outq_flush(q, /* rtx_timeout */ 1);
if (error)
q->asoc->base.sk->sk_err = -error;
}
/*
* 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)
{
struct list_head *lqueue;
struct sctp_transport *transport = pkt->transport;
sctp_xmit_t status;
struct sctp_chunk *chunk, *chunk1;
struct sctp_association *asoc;
int fast_rtx;
int error = 0;
int timer = 0;
int done = 0;
asoc = q->asoc;
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) {
/* 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_del(&chunk->transmitted_list);
list_add_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);
goto redo;
}
/* Send this packet. */
error = sctp_packet_transmit(pkt);
/* If we are retransmitting, we should only
* send a single packet.
*/
if (rtx_timeout || fast_rtx)
done = 1;
/* Bundle next chunk in the next round. */
break;
case SCTP_XMIT_RWND_FULL:
/* Send this packet. */
error = sctp_packet_transmit(pkt);
/* Stop sending DATA as there is no more room
* at the receiver.
*/
done = 1;
break;
case SCTP_XMIT_NAGLE_DELAY:
/* Send this packet. */
error = sctp_packet_transmit(pkt);
/* Stop sending DATA because of nagle delay. */
done = 1;
break;
default:
/* The append was successful, so add this chunk to
* the transmitted list.
*/
list_del(&chunk->transmitted_list);
list_add_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->empty = 0;
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. */
int sctp_outq_uncork(struct sctp_outq *q)
{
int error = 0;
if (q->cork)
q->cork = 0;
error = sctp_outq_flush(q, 0);
return error;
}
/*
* 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 int sctp_outq_flush(struct sctp_outq *q, int rtx_timeout)
{
struct sctp_packet *packet;
struct sctp_packet singleton;
struct sctp_association *asoc = q->asoc;
__u16 sport = asoc->base.bind_addr.port;
__u16 dport = asoc->peer.port;
__u32 vtag = asoc->peer.i.init_tag;
struct sctp_transport *transport = NULL;
struct sctp_transport *new_transport;
struct sctp_chunk *chunk, *tmp;
sctp_xmit_t status;
int error = 0;
int start_timer = 0;
int one_packet = 0;
/* These transports have chunks to send. */
struct list_head transport_list;
struct list_head *ltransport;
INIT_LIST_HEAD(&transport_list);
packet = NULL;
/*
* 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.
* ...
*/
list_for_each_entry_safe(chunk, tmp, &q->control_chunk_list, list) {
list_del_init(&chunk->list);
/* Pick the right transport to use. */
new_transport = chunk->transport;
if (!new_transport) {
/*
* 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 (transport &&
sctp_cmp_addr_exact(&chunk->dest,
&transport->ipaddr))
new_transport = transport;
else
new_transport = sctp_assoc_lookup_paddr(asoc,
&chunk->dest);
/* if we still don't have a new transport, then
* use the current active path.
*/
if (!new_transport)
new_transport = asoc->peer.active_path;
} else if ((new_transport->state == SCTP_INACTIVE) ||
(new_transport->state == SCTP_UNCONFIRMED)) {
/* 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.
*/
if (chunk->chunk_hdr->type != SCTP_CID_HEARTBEAT &&
chunk->chunk_hdr->type != SCTP_CID_HEARTBEAT_ACK &&
chunk->chunk_hdr->type != SCTP_CID_ASCONF_ACK)
new_transport = asoc->peer.active_path;
}
/* Are we switching transports?
* Take care of transport locks.
*/
if (new_transport != transport) {
transport = new_transport;
if (list_empty(&transport->send_ready)) {
list_add_tail(&transport->send_ready,
&transport_list);
}
packet = &transport->packet;
sctp_packet_config(packet, vtag,
asoc->peer.ecn_capable);
}
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:
sctp_packet_init(&singleton, transport, sport, dport);
sctp_packet_config(&singleton, vtag, 0);
sctp_packet_append_chunk(&singleton, chunk);
error = sctp_packet_transmit(&singleton);
if (error < 0)
return error;
break;
case SCTP_CID_ABORT:
if (sctp_test_T_bit(chunk)) {
packet->vtag = asoc->c.my_vtag;
}
/* 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;
/* Fall throught */
case SCTP_CID_SACK:
case SCTP_CID_HEARTBEAT:
case SCTP_CID_SHUTDOWN:
case SCTP_CID_ECN_ECNE:
case SCTP_CID_ASCONF:
case SCTP_CID_FWD_TSN:
status = sctp_packet_transmit_chunk(packet, chunk,
one_packet);
if (status != SCTP_XMIT_OK) {
/* put the chunk back */
list_add(&chunk->list, &q->control_chunk_list);
} else if (chunk->chunk_hdr->type == SCTP_CID_FWD_TSN) {
/* PR-SCTP C5) If a FORWARD TSN is sent, the
* sender MUST assure that at least one T3-rtx
* timer is running.
*/
sctp_transport_reset_timers(transport);
}
break;
default:
/* We built a chunk with an illegal type! */
BUG();
}
}
/* Is it OK to send data chunks? */
switch (asoc->state) {
case SCTP_STATE_COOKIE_ECHOED:
/* Only allow bundling when this packet has a COOKIE-ECHO
* chunk.
*/
if (!packet || !packet->has_cookie_echo)
break;
/* fallthru */
case SCTP_STATE_ESTABLISHED:
case SCTP_STATE_SHUTDOWN_PENDING:
case SCTP_STATE_SHUTDOWN_RECEIVED:
/*
* 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(&q->retransmit)) {
if (transport == asoc->peer.retran_path)
goto retran;
/* Switch transports & prepare the packet. */
transport = asoc->peer.retran_path;
if (list_empty(&transport->send_ready)) {
list_add_tail(&transport->send_ready,
&transport_list);
}
packet = &transport->packet;
sctp_packet_config(packet, vtag,
asoc->peer.ecn_capable);
retran:
error = sctp_outq_flush_rtx(q, packet,
rtx_timeout, &start_timer);
if (start_timer)
sctp_transport_reset_timers(transport);
/* This can happen on COOKIE-ECHO resend. Only
* one chunk can get bundled with a COOKIE-ECHO.
*/
if (packet->has_cookie_echo)
goto sctp_flush_out;
/* Don't send new data if there is still data
* waiting to retransmit.
*/
if (!list_empty(&q->retransmit))
goto sctp_flush_out;
}
/* 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 (transport)
sctp_transport_burst_limited(transport);
/* Finally, transmit new packets. */
while ((chunk = sctp_outq_dequeue_data(q)) != NULL) {
/* RFC 2960 6.5 Every DATA chunk MUST carry a valid
* stream identifier.
*/
if (chunk->sinfo.sinfo_stream >=
asoc->c.sinit_num_ostreams) {
/* Mark as failed send. */
sctp_chunk_fail(chunk, SCTP_ERROR_INV_STRM);
sctp_chunk_free(chunk);
continue;
}
/* Has this chunk expired? */
if (sctp_chunk_abandoned(chunk)) {
sctp_chunk_fail(chunk, 0);
sctp_chunk_free(chunk);
continue;
}
/* If there is a specified transport, use it.
* Otherwise, we want to use the active path.
*/
new_transport = chunk->transport;
if (!new_transport ||
((new_transport->state == SCTP_INACTIVE) ||
(new_transport->state == SCTP_UNCONFIRMED)))
new_transport = asoc->peer.active_path;
/* Change packets if necessary. */
if (new_transport != transport) {
transport = new_transport;
/* Schedule to have this transport's
* packet flushed.
*/
if (list_empty(&transport->send_ready)) {
list_add_tail(&transport->send_ready,
&transport_list);
}
packet = &transport->packet;
sctp_packet_config(packet, vtag,
asoc->peer.ecn_capable);
/* We've switched transports, so apply the
* Burst limit to the new transport.
*/
sctp_transport_burst_limited(transport);
}
SCTP_DEBUG_PRINTK("sctp_outq_flush(%p, %p[%s]), ",
q, chunk,
chunk && chunk->chunk_hdr ?
sctp_cname(SCTP_ST_CHUNK(
chunk->chunk_hdr->type))
: "Illegal Chunk");
SCTP_DEBUG_PRINTK("TX TSN 0x%x skb->head "