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kernel-ark/net/sctp/outqueue.c
Sridhar Samudrala ac0b046272 [SCTP]: Extend /proc/net/sctp/snmp to provide more statistics. 
This patch adds more statistics info under /proc/net/sctp/snmp
that should be useful for debugging. The additional events that
are counted now include timer expirations, retransmits, packet
and data chunk discards.

The Data chunk discards include all the cases where a data chunk
is discarded including high tsn, bad stream, dup tsn and the most
useful one(out of receive buffer/rwnd).

Also moved the SCTP MIB data structures from the generic include
directories to include/sctp/sctp.h.

Signed-off-by: Sridhar Samudrala <sri@us.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2006-09-22 14:55:16 -07:00

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/* SCTP kernel reference 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 reference Implementation
*
* These functions implement the sctp_outq class. The outqueue handles
* bundling and queueing of outgoing SCTP chunks.
*
* The SCTP reference 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.
*
* The SCTP reference 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 <lksctp-developers@lists.sourceforge.net>
*
* Or submit a bug report through the following website:
* http://www.sf.net/projects/lksctp
*
* 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>
*
* Any bugs reported given to us we will try to fix... any fixes shared will
* be incorporated into the next SCTP release.
*/
#include <linux/types.h>
#include <linux/list.h> /* For struct list_head */
#include <linux/socket.h>
#include <linux/ip.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);
/* 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;
return;
}
/* 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;
return;
}
/*
* 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->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, *pos, *temp;
struct sctp_chunk *chunk, *tmp;
/* Throw away unacknowledged chunks. */
list_for_each(pos, &q->asoc->peer.transport_addr_list) {
transport = list_entry(pos, struct sctp_transport, 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_CID_DATA == chunk->chunk_hdr->type) {
/* 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 fast_retransmit)
{
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);
continue;
}
/* If we are doing retransmission due to a fast retransmit,
* only the chunk's that are marked for fast retransmit
* should be added to the retransmit queue. 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 ((fast_retransmit && (chunk->fast_retransmit > 0)) ||
(!fast_retransmit && !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);
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, fast_retransmit: %d, "
"cwnd: %d, ssthresh: %d, flight_size: %d, "
"pba: %d\n", __FUNCTION__,
transport, fast_retransmit,
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;
__u8 fast_retransmit = 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);
break;
case SCTP_RTXR_FAST_RTX:
SCTP_INC_STATS(SCTP_MIB_FAST_RETRANSMITS);
sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_FAST_RTX);
fast_retransmit = 1;
break;
case SCTP_RTXR_PMTUD:
SCTP_INC_STATS(SCTP_MIB_PMTUD_RETRANSMITS);
break;
default:
BUG();
}
sctp_retransmit_mark(q, transport, fast_retransmit);
/* 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.
*/
sctp_generate_fwdtsn(q, q->asoc->ctsn_ack_point);
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 list_head *lchunk, *lchunk1;
struct sctp_transport *transport = pkt->transport;
sctp_xmit_t status;
struct sctp_chunk *chunk, *chunk1;
struct sctp_association *asoc;
int error = 0;
asoc = q->asoc;
lqueue = &q->retransmit;
/* 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.]
*/
lchunk = sctp_list_dequeue(lqueue);
while (lchunk) {
chunk = list_entry(lchunk, struct sctp_chunk,
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_add_tail(lchunk, &transport->transmitted);
lchunk = sctp_list_dequeue(lqueue);
continue;
}
/* Attempt to append this chunk to the packet. */
status = sctp_packet_append_chunk(pkt, chunk);
switch (status) {
case SCTP_XMIT_PMTU_FULL:
/* Send this packet. */
if ((error = sctp_packet_transmit(pkt)) == 0)
*start_timer = 1;
/* If we are retransmitting, we should only
* send a single packet.
*/
if (rtx_timeout) {
list_add(lchunk, lqueue);
lchunk = NULL;
}
/* Bundle lchunk in the next round. */
break;
case SCTP_XMIT_RWND_FULL:
/* Send this packet. */
if ((error = sctp_packet_transmit(pkt)) == 0)
*start_timer = 1;
/* Stop sending DATA as there is no more room
* at the receiver.
*/
list_add(lchunk, lqueue);
lchunk = NULL;
break;
case SCTP_XMIT_NAGLE_DELAY:
/* Send this packet. */
if ((error = sctp_packet_transmit(pkt)) == 0)
*start_timer = 1;
/* Stop sending DATA because of nagle delay. */
list_add(lchunk, lqueue);
lchunk = NULL;
break;
default:
/* The append was successful, so add this chunk to
* the transmitted list.
*/
list_add_tail(lchunk, &transport->transmitted);
/* Mark the chunk as ineligible for fast retransmit
* after it is retransmitted.
*/
if (chunk->fast_retransmit > 0)
chunk->fast_retransmit = -1;
*start_timer = 1;
q->empty = 0;
/* Retrieve a new chunk to bundle. */
lchunk = sctp_list_dequeue(lqueue);
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 && !lchunk) {
list_for_each(lchunk1, lqueue) {
chunk1 = list_entry(lchunk1, struct sctp_chunk,
transmitted_list);
if (chunk1->fast_retransmit > 0)
chunk1->fast_retransmit = -1;
}
}
}
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.
*/
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;
/* 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) {
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.
* ...
*/
if (chunk->chunk_hdr->type != SCTP_CID_HEARTBEAT &&
chunk->chunk_hdr->type != SCTP_CID_HEARTBEAT_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:
case SCTP_CID_SACK:
case SCTP_CID_HEARTBEAT:
case SCTP_CID_HEARTBEAT_ACK:
case SCTP_CID_SHUTDOWN:
case SCTP_CID_SHUTDOWN_ACK:
case SCTP_CID_ERROR:
case SCTP_CID_COOKIE_ECHO:
case SCTP_CID_COOKIE_ACK:
case SCTP_CID_ECN_ECNE:
case SCTP_CID_ECN_CWR:
case SCTP_CID_ASCONF:
case SCTP_CID_ASCONF_ACK:
case SCTP_CID_FWD_TSN:
sctp_packet_transmit_chunk(packet, chunk);
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;
}
/* Finally, transmit new packets. */
start_timer = 0;
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);
}
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 "
"%p skb->users %d.\n",
ntohl(chunk->subh.data_hdr->tsn),
chunk->skb ?chunk->skb->head : NULL,
chunk->skb ?
atomic_read(&chunk->skb->users) : -1);
/* Add the chunk to the packet. */
status = sctp_packet_transmit_chunk(packet, chunk);
switch (status) {
case SCTP_XMIT_PMTU_FULL:
case SCTP_XMIT_RWND_FULL:
case SCTP_XMIT_NAGLE_DELAY:
/* We could not append this chunk, so put
* the chunk back on the output queue.
*/
SCTP_DEBUG_PRINTK("sctp_outq_flush: could "
"not transmit TSN: 0x%x, status: %d\n",
ntohl(chunk->subh.data_hdr->tsn),
status);
sctp_outq_head_data(q, chunk);
goto sctp_flush_out;
break;
case SCTP_XMIT_OK:
break;
default:
BUG();
}
/* BUG: We assume that the sctp_packet_transmit()
* call below will succeed all the time and add the
* chunk to the transmitted list and restart the
* timers.
* It is possible that the call can fail under OOM
* conditions.
*
* Is this really a problem? Won't this behave
* like a lost TSN?
*/
list_add_tail(&chunk->transmitted_list,
&transport->transmitted);
sctp_transport_reset_timers(transport);
q->empty = 0;
/* Only let one DATA chunk get bundled with a
* COOKIE-ECHO chunk.
*/
if (packet->has_cookie_echo)
goto sctp_flush_out;
}
break;
default:
/* Do nothing. */
break;
}
sctp_flush_out:
/* Before returning, examine all the transports touched in
* this call. Right now, we bluntly force clear all the
* transports. Things might change after we implement Nagle.
* But such an examination is still required.
*
* --xguo
*/
while ((ltransport = sctp_list_dequeue(&transport_list)) != NULL ) {
struct sctp_transport *t = list_entry(ltransport,
struct sctp_transport,
send_ready);
packet = &t->packet;
if (!sctp_packet_empty(packet))
error = sctp_packet_transmit(packet);
}
return error;
}
/* Update unack_data based on the incoming SACK chunk */
static void sctp_sack_update_unack_data(struct sctp_association *assoc,
struct sctp_sackhdr *sack)
{
sctp_sack_variable_t *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;
}
/* Return the highest new tsn that is acknowledged by the given SACK chunk. */
static __u32 sctp_highest_new_tsn(struct sctp_sackhdr *sack,
struct sctp_association *asoc)
{
struct list_head *ltransport, *lchunk;
struct sctp_transport *transport;
struct sctp_chunk *chunk;
__u32 highest_new_tsn, tsn;
struct list_head *transport_list = &asoc->peer.transport_addr_list;
highest_new_tsn = ntohl(sack->cum_tsn_ack);
list_for_each(ltransport, transport_list) {
transport = list_entry(ltransport, struct sctp_transport,
transports);
list_for_each(lchunk, &transport->transmitted) {
chunk = list_entry(lchunk, struct sctp_chunk,
transmitted_list);
tsn = ntohl(chunk->subh.data_hdr->tsn);
if (!chunk->tsn_gap_acked &&
TSN_lt(highest_new_tsn, tsn) &&
sctp_acked(sack, tsn))
highest_new_tsn = tsn;
}
}
return highest_new_tsn;
}
/* 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_sackhdr *sack)
{
struct sctp_association *asoc = q->asoc;
struct sctp_transport *transport;
struct sctp_chunk *tchunk = NULL;
struct list_head *lchunk, *transport_list, *pos, *temp;
sctp_sack_variable_t *frags = sack->variable;
__u32 sack_ctsn, ctsn, tsn;
__u32 highest_tsn, highest_new_tsn;
__u32 sack_a_rwnd;
unsigned outstanding;
struct sctp_transport *primary = asoc->peer.primary_path;
int count_of_newacks = 0;
/* Grab the association's destination address list. */
transport_list = &asoc->peer.transport_addr_list;
sack_ctsn = ntohl(sack->cum_tsn_ack);
/*
* 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.
*/
if (TSN_lte(primary->cacc.next_tsn_at_change, sack_ctsn)) {
primary->cacc.changeover_active = 0;
list_for_each(pos, transport_list) {
transport = list_entry(pos, struct sctp_transport,
transports);
transport->cacc.cycling_changeover = 0;
}
}
/*
* 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 actions:
*
* A) Initialize the cacc_saw_newack to 0 for all destination
* addresses.
*/
if (sack->num_gap_ack_blocks > 0 &&
primary->cacc.changeover_active) {
list_for_each(pos, transport_list) {
transport = list_entry(pos, struct sctp_transport,
transports);
transport->cacc.cacc_saw_newack = 0;
}
}
/* Get the highest TSN in the sack. */
highest_tsn = sack_ctsn;
if (sack->num_gap_ack_blocks)
highest_tsn +=
ntohs(frags[ntohs(sack->num_gap_ack_blocks) - 1].gab.end);
if (TSN_lt(asoc->highest_sacked, highest_tsn)) {
highest_new_tsn = highest_tsn;
asoc->highest_sacked = highest_tsn;
} else {
highest_new_tsn = sctp_highest_new_tsn(sack, asoc);
}
/* Run through the retransmit queue. Credit bytes received
* and free those chunks that we can.
*/
sctp_check_transmitted(q, &q->retransmit, NULL, sack, highest_new_tsn);
sctp_mark_missing(q, &q->retransmit, NULL, highest_new_tsn, 0);
/* 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(pos, transport_list) {
transport = list_entry(pos, struct sctp_transport,
transports);
sctp_check_transmitted(q, &transport->transmitted,
transport, 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 ++;
}
list_for_each(pos, transport_list) {
transport = list_entry(pos, struct sctp_transport,
transports);
sctp_mark_missing(q, &transport->transmitted, transport,
highest_new_tsn, 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;
/* 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))
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);
outstanding = q->outstanding_bytes;
if (outstanding < sack_a_rwnd)
sack_a_rwnd -= outstanding;
else
sack_a_rwnd = 0;
asoc->peer.rwnd = sack_a_rwnd;
sctp_generate_fwdtsn(q, sack_ctsn);
SCTP_DEBUG_PRINTK("%s: sack Cumulative TSN Ack is 0x%x.\n",
__FUNCTION__, sack_ctsn);
SCTP_DEBUG_PRINTK("%s: Cumulative TSN Ack of association, "
"%p is 0x%x. Adv peer ack point: 0x%x\n",
__FUNCTION__, asoc, ctsn, asoc->adv_peer_ack_point);
/* See if all chunks are acked.
* Make sure the empty queue handler will get run later.
*/
q->empty = (list_empty(&q->out_chunk_list) &&
list_empty(&q->control_chunk_list) &&
list_empty(&q->retransmit));
if (!q->empty)
goto finish;
list_for_each(pos, transport_list) {
transport = list_entry(pos, struct sctp_transport,
transports);
q->empty = q->empty && list_empty(&transport->transmitted);
if (!q->empty)
goto finish;
}
SCTP_DEBUG_PRINTK("sack queue is empty.\n");
finish:
return q->empty;
}
/* Is the outqueue empty? */
int sctp_outq_is_empty(const struct sctp_outq *q)
{
return q->empty;
}
/********************************************************************
* 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,
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;
/* These state variables are for coherent debug output. --xguo */
#if SCTP_DEBUG
__u32 dbg_ack_tsn = 0; /* An ACKed TSN range starts here... */
__u32 dbg_last_ack_tsn = 0; /* ...and finishes here. */
__u32 dbg_kept_tsn = 0; /* An un-ACKed range starts here... */
__u32 dbg_last_kept_tsn = 0; /* ...and finishes here. */
/* 0 : The last TSN was ACKed.
* 1 : The last TSN was NOT ACKed (i.e. KEPT).
* -1: We need to initialize.
*/
int dbg_prt_state = -1;
#endif /* SCTP_DEBUG */
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);
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) {
/* 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 (!tchunk->tsn_gap_acked &&
!tchunk->resent &&
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)) {
/* 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;
if (!tchunk->tsn_gap_acked) {
tchunk->tsn_gap_acked = 1;
bytes_acked += sctp_data_size(tchunk);
/*
* 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 (transport &&
sack->num_gap_ack_blocks &&
q->asoc->peer.primary_path->cacc.
changeover_active)
transport->cacc.cacc_saw_newack
= 1;
}
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'.
*/
if (!tchunk->tsn_gap_acked) {
tchunk->tsn_gap_acked = 1;
bytes_acked += sctp_data_size(tchunk);
}
list_add_tail(lchunk, &tlist);
}
#if SCTP_DEBUG
switch (dbg_prt_state) {
case 0: /* last TSN was ACKed */
if (dbg_last_ack_tsn + 1 == tsn) {
/* This TSN belongs to the
* current ACK range.
*/
break;
}
if (dbg_last_ack_tsn != dbg_ack_tsn) {
/* Display the end of the
* current range.
*/
SCTP_DEBUG_PRINTK("-%08x",
dbg_last_ack_tsn);
}
/* Start a new range. */
SCTP_DEBUG_PRINTK(",%08x", tsn);
dbg_ack_tsn = tsn;
break;
case 1: /* The last TSN was NOT ACKed. */
if (dbg_last_kept_tsn != dbg_kept_tsn) {
/* Display the end of current range. */
SCTP_DEBUG_PRINTK("-%08x",
dbg_last_kept_tsn);
}
SCTP_DEBUG_PRINTK("\n");
/* FALL THROUGH... */
default:
/* This is the first-ever TSN we examined. */
/* Start a new range of ACK-ed TSNs. */
SCTP_DEBUG_PRINTK("ACKed: %08x", tsn);
dbg_prt_state = 0;
dbg_ack_tsn = tsn;
};
dbg_last_ack_tsn = tsn;
#endif /* SCTP_DEBUG */
} else {
if (tchunk->tsn_gap_acked) {
SCTP_DEBUG_PRINTK("%s: Receiver reneged on "
"data TSN: 0x%x\n",
__FUNCTION__,
tsn);
tchunk->tsn_gap_acked = 0;
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 SCTP_DEBUG
/* See the above comments on ACK-ed TSNs. */
switch (dbg_prt_state) {
case 1:
if (dbg_last_kept_tsn + 1 == tsn)
break;
if (dbg_last_kept_tsn != dbg_kept_tsn)
SCTP_DEBUG_PRINTK("-%08x",
dbg_last_kept_tsn);
SCTP_DEBUG_PRINTK(",%08x", tsn);
dbg_kept_tsn = tsn;
break;
case 0:
if (dbg_last_ack_tsn != dbg_ack_tsn)
SCTP_DEBUG_PRINTK("-%08x",
dbg_last_ack_tsn);
SCTP_DEBUG_PRINTK("\n");
/* FALL THROUGH... */
default:
SCTP_DEBUG_PRINTK("KEPT: %08x",tsn);
dbg_prt_state = 1;
dbg_kept_tsn = tsn;
};
dbg_last_kept_tsn = tsn;
#endif /* SCTP_DEBUG */
}
}
#if SCTP_DEBUG
/* Finish off the last range, displaying its ending TSN. */
switch (dbg_prt_state) {
case 0:
if (dbg_last_ack_tsn != dbg_ack_tsn) {
SCTP_DEBUG_PRINTK("-%08x\n", dbg_last_ack_tsn);
} else {
SCTP_DEBUG_PRINTK("\n");
}
break;
case 1:
if (dbg_last_kept_tsn != dbg_kept_tsn) {
SCTP_DEBUG_PRINTK("-%08x\n", dbg_last_kept_tsn);
} else {
SCTP_DEBUG_PRINTK("\n");
}
};
#endif /* SCTP_DEBUG */
if (transport) {
if (bytes_acked) {
/* 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;
/* Mark the destination transport address as
* active if it is not so marked.
*/
if ((transport->state == SCTP_INACTIVE) ||
(transport->state == SCTP_UNCONFIRMED)) {
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;
q->outstanding_bytes -= bytes_acked;
} 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.
*/
if (!q->asoc->peer.rwnd &&
!list_empty(&tlist) &&
(sack_ctsn+2 == q->asoc->next_tsn)) {
SCTP_DEBUG_PRINTK("%s: SACK received for zero "
"window probe: %u\n",
__FUNCTION__, 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 (timer_pending(&transport->T3_rtx_timer) &&
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);
}
}
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;
struct list_head *pos;
__u32 tsn;
char do_fast_retransmit = 0;
struct sctp_transport *primary = q->asoc->peer.primary_path;
list_for_each(pos, transmitted_queue) {
chunk = list_entry(pos, struct sctp_chunk, 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 &&
!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, transport,
count_of_newacks, tsn)) {
chunk->tsn_missing_report++;
SCTP_DEBUG_PRINTK(
"%s: TSN 0x%x missing counter: %d\n",
__FUNCTION__, 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 = 1;
do_fast_retransmit = 1;
}
}
if (transport) {
if (do_fast_retransmit)
sctp_retransmit(q, transport, SCTP_RTXR_FAST_RTX);
SCTP_DEBUG_PRINTK("%s: transport: %p, cwnd: %d, "
"ssthresh: %d, flight_size: %d, pba: %d\n",
__FUNCTION__, 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)
{
int i;
sctp_sack_variable_t *frags;
__u16 gap;
__u32 ctsn = ntohl(sack->cum_tsn_ack);
if (TSN_lte(tsn, ctsn))
goto pass;
/* 3.3.4 Selective Acknowledgement (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;
gap = tsn - ctsn;
for (i = 0; i < ntohs(sack->num_gap_ack_blocks); ++i) {
if (TSN_lte(ntohs(frags[i].gab.start), gap) &&
TSN_lte(gap, 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, __u16 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. */
static 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;
/* 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);
if (!chunk->tsn_gap_acked) {
chunk->transport->flight_size -=
sctp_data_size(chunk);
q->outstanding_bytes -= sctp_data_size(chunk);
}
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(SCTP_MIB_OUTCTRLCHUNKS);
}
}
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