/* 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 <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);
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;
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->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_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 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) {
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 > 0)) ||
(reason != SCTP_RTXR_FAST_RTX && !chunk->tsn_gap_acked)) {
/* If this chunk was sent less then 1 rto ago, do not
* retransmit this chunk, but give the peer time
* to acknowlege it. Do this only when
* retransmitting due to T3 timeout.
*/
if (reason == SCTP_RTXR_T3_RTX &&
(jiffies - chunk->sent_at) < transport->last_rto)
continue;
/* 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);
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;
/* 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. */
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 > 0)
chunk->fast_retransmit = -1;
/* Force start T3-rtx timer when fast retransmitting
* the earliest outstanding TSN
*/
if (!timer && fast_rtx &&
ntohl(chunk->subh.data_hdr->tsn) ==
asoc->ctsn_ack_point + 1)
timer = 2;
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 > 0)
chunk1->fast_retransmit = -1;
}
}
*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);
}
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,
start_timer-1);
/* 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, 0);
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, start_timer-1);
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 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_entry(transport, transport_list, transports) {
list_for_each_entry(chunk, &transport->transmitted,
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, *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_entry(transport, transport_list,
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 &&
primary->cacc.changeover_active) {
list_for_each_entry(transport, transport_list, 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_entry(transport, transport_list, 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_entry(transport, transport_list, 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)) {
list_del_init(&tchunk->transmitted_list);
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",
__func__, sack_ctsn);
SCTP_DEBUG_PRINTK("%s: Cumulative TSN Ack of association, "
"%p is 0x%x. Adv peer ack point: 0x%x\n",
__func__, 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->retransmit));
if (!q->empty)
goto finish;
list_for_each_entry(transport, transport_list, 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);
/* If this chunk has not been acked, stop
* considering it as 'outstanding'.
*/
if (!tchunk->tsn_gap_acked) {
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) {
/* 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",
__func__,
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;
if (transport->flight_size == 0)
transport->partial_bytes_acked = 0;
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",
__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 (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;
__u32 tsn;
char do_fast_retransmit = 0;
struct sctp_transport *primary = q->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 &&
!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",
__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 = 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",
__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)
{
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, __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. */
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);
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);
}
}
