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NetBSD/sys/netinet/tcp_sack.c

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/* $NetBSD: tcp_sack.c,v 1.14 2005/12/11 12:24:58 christos Exp $ */
/*
* Copyright (c) 2005 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Kentaro A. Kurahone.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the NetBSD
* Foundation, Inc. and its contributors.
* 4. Neither the name of The NetBSD Foundation nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/*
* Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)tcp_sack.c 8.12 (Berkeley) 5/24/95
* $FreeBSD: src/sys/netinet/tcp_sack.c,v 1.3.2.2 2004/12/25 23:02:57 rwatson Exp $
*/
/*
* @@(#)COPYRIGHT 1.1 (NRL) 17 January 1995
*
* NRL grants permission for redistribution and use in source and binary
* forms, with or without modification, of the software and documentation
* created at NRL provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgements:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* This product includes software developed at the Information
* Technology Division, US Naval Research Laboratory.
* 4. Neither the name of the NRL nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THE SOFTWARE PROVIDED BY NRL IS PROVIDED BY NRL AND CONTRIBUTORS ``AS
* IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL NRL OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* The views and conclusions contained in the software and documentation
* are those of the authors and should not be interpreted as representing
* official policies, either expressed or implied, of the US Naval
* Research Laboratory (NRL).
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: tcp_sack.c,v 1.14 2005/12/11 12:24:58 christos Exp $");
#include "opt_inet.h"
#include "opt_ipsec.h"
#include "opt_inet_csum.h"
#include "opt_tcp_debug.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/errno.h>
#include <sys/syslog.h>
#include <sys/pool.h>
#include <sys/domain.h>
#include <sys/kernel.h>
#include <net/if.h>
#include <net/route.h>
#include <net/if_types.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/in_pcb.h>
#include <netinet/in_var.h>
#include <netinet/ip_var.h>
#ifdef INET6
#ifndef INET
#include <netinet/in.h>
#endif
#include <netinet/ip6.h>
#include <netinet6/ip6_var.h>
#include <netinet6/in6_pcb.h>
#include <netinet6/ip6_var.h>
#include <netinet6/in6_var.h>
#include <netinet/icmp6.h>
#include <netinet6/nd6.h>
#endif
#ifndef INET6
/* always need ip6.h for IP6_EXTHDR_GET */
#include <netinet/ip6.h>
#endif
#include <netinet/tcp.h>
#include <netinet/tcp_fsm.h>
#include <netinet/tcp_seq.h>
#include <netinet/tcp_timer.h>
#include <netinet/tcp_var.h>
#include <netinet/tcpip.h>
#include <netinet/tcp_debug.h>
#include <machine/stdarg.h>
/* SACK block pool. */
POOL_INIT(sackhole_pool, sizeof(struct sackhole), 0, 0, 0, "sackholepl", NULL);
void
tcp_new_dsack(struct tcpcb *tp, tcp_seq seq, u_int32_t len)
{
if (TCP_SACK_ENABLED(tp)) {
tp->rcv_dsack_block.left = seq;
tp->rcv_dsack_block.right = seq + len;
tp->rcv_sack_flags |= TCPSACK_HAVED;
}
}
void
tcp_sack_option(struct tcpcb *tp, struct tcphdr *th, u_char *cp, int optlen)
{
struct sackblk
t_sack_block[(MAX_TCPOPTLEN - 2) / (sizeof(u_int32_t) * 2)];
struct sackblk *sack = NULL;
struct sackhole *cur = NULL;
struct sackhole *tmp = NULL;
u_int32_t *lp = (u_int32_t *) (cp + 2);
int i, j, num_sack_blks;
tcp_seq left, right, acked;
/*
* If we aren't processing SACK responses, this is not an ACK
* or the peer sends us a sack option with invalid length, don't
* update the scoreboard.
*/
if (!TCP_SACK_ENABLED(tp) || ((th->th_flags & TH_ACK) == 0) ||
(optlen % 8 != 2 || optlen < 10)) {
return;
}
/*
* If we don't want any SACK holes to be allocated, just return.
*/
if (tcp_sack_globalmaxholes == 0 || tcp_sack_tp_maxholes == 0) {
return;
}
/* If the ACK is outside [snd_una, snd_max], ignore the SACK options. */
if (SEQ_LT(th->th_ack, tp->snd_una) || SEQ_GT(th->th_ack, tp->snd_max))
return;
/*
* Extract SACK blocks.
*
* Note that t_sack_block is sorted so that we only need to do
* one pass over the sequence number space. (SACK "fast-path")
*/
num_sack_blks = optlen / 8;
acked = (SEQ_GT(th->th_ack, tp->snd_una)) ? th->th_ack : tp->snd_una;
for (i = 0; i < num_sack_blks; i++, lp += 2) {
memcpy(&left, lp, sizeof(*lp));
memcpy(&right, lp + 1, sizeof(*lp));
left = ntohl(left);
right = ntohl(right);
if (SEQ_LEQ(right, acked) || SEQ_GT(right, tp->snd_max) ||
SEQ_GEQ(left, right)) {
/* SACK entry that's old, or invalid. */
i--;
num_sack_blks--;
continue;
}
/* Insertion sort. */
for (j = i; (j > 0) && SEQ_LT(left, t_sack_block[j - 1].left);
j--) {
t_sack_block[j].left = t_sack_block[j - 1].left;
t_sack_block[j].right = t_sack_block[j - 1].right;
}
t_sack_block[j].left = left;
t_sack_block[j].right = right;
}
/* Update the scoreboard. */
cur = TAILQ_FIRST(&tp->snd_holes);
for (i = 0; i < num_sack_blks; i++) {
sack = &t_sack_block[i];
/*
* FACK TCP. Update snd_fack so we can enter Fast
* Recovery early.
*/
if (SEQ_GEQ(sack->right, tp->snd_fack))
tp->snd_fack = sack->right;
if (TAILQ_EMPTY(&tp->snd_holes)) {
/* First hole. */
if (tcp_sack_globalholes >= tcp_sack_globalmaxholes) {
return;
}
cur = (struct sackhole *)
pool_get(&sackhole_pool, PR_NOWAIT);
if (cur == NULL) {
/* ENOBUFS, bail out*/
return;
}
cur->start = th->th_ack;
cur->end = sack->left;
cur->rxmit = cur->start;
tp->rcv_lastsack = sack->right;
tp->snd_numholes++;
tcp_sack_globalholes++;
TAILQ_INSERT_HEAD(&tp->snd_holes, cur, sackhole_q);
continue; /* With next sack block */
}
/* Go through the list of holes. */
while (cur) {
if (SEQ_LEQ(sack->right, cur->start))
/* SACKs data before the current hole */
break; /* No use going through more holes */
if (SEQ_GEQ(sack->left, cur->end)) {
/* SACKs data beyond the current hole */
cur = TAILQ_NEXT(cur, sackhole_q);
continue;
}
if (SEQ_LEQ(sack->left, cur->start)) {
/* Data acks at least the beginning of hole */
if (SEQ_GEQ(sack->right, cur->end)) {
/* Acks entire hole, so delete hole */
tmp = cur;
cur = TAILQ_NEXT(cur, sackhole_q);
tp->snd_numholes--;
tcp_sack_globalholes--;
TAILQ_REMOVE(&tp->snd_holes, tmp,
sackhole_q);
pool_put(&sackhole_pool, tmp);
break;
}
/* Otherwise, move start of hole forward */
cur->start = sack->right;
cur->rxmit = SEQ_MAX(cur->rxmit, cur->start);
break;
}
if (SEQ_GEQ(sack->right, cur->end)) {
/* Move end of hole backward. */
cur->end = sack->left;
cur->rxmit = SEQ_MIN(cur->rxmit, cur->end);
cur = TAILQ_NEXT(cur, sackhole_q);
break;
}
if (SEQ_LT(cur->start, sack->left) &&
SEQ_GT(cur->end, sack->right)) {
/*
* ACKs some data in middle of a hole; need to
* split current hole
*/
if (tcp_sack_globalholes >=
tcp_sack_globalmaxholes ||
tp->snd_numholes >=
tcp_sack_tp_maxholes) {
return;
}
tmp = (struct sackhole *)
pool_get(&sackhole_pool, PR_NOWAIT);
if (tmp == NULL) {
/* ENOBUFS, bail out. */
return;
}
tmp->start = sack->right;
tmp->end = cur->end;
tmp->rxmit = SEQ_MAX(cur->rxmit, tmp->start);
cur->end = sack->left;
cur->rxmit = SEQ_MIN(cur->rxmit, cur->end);
tp->snd_numholes++;
tcp_sack_globalholes++;
TAILQ_INSERT_AFTER(&tp->snd_holes, cur, tmp,
sackhole_q);
cur = tmp;
break;
}
}
/* At this point, we have reached the tail of the list. */
if (SEQ_LT(tp->rcv_lastsack, sack->left)) {
/*
* Need to append new hole at end.
*/
if (tcp_sack_globalholes >=
tcp_sack_globalmaxholes ||
tp->snd_numholes >=
tcp_sack_tp_maxholes) {
return;
}
tmp = (struct sackhole *)
pool_get(&sackhole_pool, PR_NOWAIT);
if (tmp == NULL)
continue; /* ENOBUFS */
tmp->start = tp->rcv_lastsack;
tmp->end = sack->left;
tmp->rxmit = tmp->start;
tp->snd_numholes++;
tcp_sack_globalholes++;
TAILQ_INSERT_TAIL(&tp->snd_holes, tmp, sackhole_q);
cur = tmp;
}
if (SEQ_LT(tp->rcv_lastsack, sack->right)) {
tp->rcv_lastsack = sack->right;
}
}
}
void
tcp_del_sackholes(struct tcpcb *tp, struct tcphdr *th)
{
/* Max because this could be an older ack that just arrived. */
tcp_seq lastack = SEQ_GT(th->th_ack, tp->snd_una) ?
th->th_ack : tp->snd_una;
struct sackhole *cur = TAILQ_FIRST(&tp->snd_holes);
struct sackhole *tmp;
while (cur) {
if (SEQ_LEQ(cur->end, lastack)) {
tmp = cur;
cur = TAILQ_NEXT(cur, sackhole_q);
tp->snd_numholes--;
tcp_sack_globalholes--;
TAILQ_REMOVE(&tp->snd_holes, tmp, sackhole_q);
pool_put(&sackhole_pool, tmp);
} else if (SEQ_LT(cur->start, lastack)) {
cur->start = lastack;
if (SEQ_LT(cur->rxmit, cur->start))
cur->rxmit = cur->start;
break;
} else
break;
}
}
void
tcp_free_sackholes(struct tcpcb *tp)
{
struct sackhole *sack;
/* Free up the SACK hole list. */
while (!TAILQ_EMPTY(&tp->snd_holes)) {
sack = TAILQ_FIRST(&tp->snd_holes);
tcp_sack_globalholes--;
TAILQ_REMOVE(&tp->snd_holes, sack, sackhole_q);
pool_put(&sackhole_pool, sack);
}
tp->snd_numholes = 0;
}
/*
* Implements the SACK response to a new ack, checking for partial acks
* in fast recovery.
*/
void
tcp_sack_newack(struct tcpcb *tp, struct tcphdr *th)
{
if (tp->t_partialacks < 0) {
/*
* Not in fast recovery. Reset the duplicate ack
* counter.
*/
tp->t_dupacks = 0;
} else if (SEQ_LT(th->th_ack, tp->snd_recover)) {
/*
* Partial ack handling within a sack recovery episode.
* Keeping this very simple for now. When a partial ack
* is received, force snd_cwnd to a value that will allow
* the sender to transmit no more than 2 segments.
* If necessary, a fancier scheme can be adopted at a
* later point, but for now, the goal is to prevent the
* sender from bursting a large amount of data in the midst
* of sack recovery.
*/
int num_segs = 1;
int sack_bytes_rxmt = 0;
tp->t_partialacks++;
TCP_TIMER_DISARM(tp, TCPT_REXMT);
tp->t_rtttime = 0;
/*
* send one or 2 segments based on how much new data was acked
*/
if (((th->th_ack - tp->snd_una) / tp->t_segsz) > 2)
num_segs = 2;
(void)tcp_sack_output(tp, &sack_bytes_rxmt);
tp->snd_cwnd = sack_bytes_rxmt +
(tp->snd_nxt - tp->sack_newdata) + num_segs * tp->t_segsz;
tp->t_flags |= TF_ACKNOW;
(void) tcp_output(tp);
} else {
/*
* Complete ack, inflate the congestion window to
* ssthresh and exit fast recovery.
*
* Window inflation should have left us with approx.
* snd_ssthresh outstanding data. But in case we
* would be inclined to send a burst, better to do
* it via the slow start mechanism.
*/
if (SEQ_SUB(tp->snd_max, th->th_ack) < tp->snd_ssthresh)
tp->snd_cwnd = SEQ_SUB(tp->snd_max, th->th_ack)
+ tp->t_segsz;
else
tp->snd_cwnd = tp->snd_ssthresh;
tp->t_partialacks = -1;
tp->t_dupacks = 0;
if (SEQ_GT(th->th_ack, tp->snd_fack))
tp->snd_fack = th->th_ack;
}
}
/*
* Returns pointer to a sackhole if there are any pending retransmissions;
* NULL otherwise.
*/
struct sackhole *
tcp_sack_output(struct tcpcb *tp, int *sack_bytes_rexmt)
{
struct sackhole *cur = NULL;
if(!TCP_SACK_ENABLED(tp))
return (NULL);
*sack_bytes_rexmt = 0;
TAILQ_FOREACH(cur, &tp->snd_holes, sackhole_q) {
if (SEQ_LT(cur->rxmit, cur->end)) {
if (SEQ_LT(cur->rxmit, tp->snd_una)) {
/* old SACK hole */
continue;
}
*sack_bytes_rexmt += (cur->rxmit - cur->start);
break;
}
*sack_bytes_rexmt += (cur->rxmit - cur->start);
}
return (cur);
}
/*
* After a timeout, the SACK list may be rebuilt. This SACK information
* should be used to avoid retransmitting SACKed data. This function
* traverses the SACK list to see if snd_nxt should be moved forward.
*/
void
tcp_sack_adjust(struct tcpcb *tp)
{
struct sackhole *cur = TAILQ_FIRST(&tp->snd_holes);
struct sackhole *n = NULL;
if (TAILQ_EMPTY(&tp->snd_holes))
return; /* No holes */
if (SEQ_GEQ(tp->snd_nxt, tp->rcv_lastsack))
return; /* We're already beyond any SACKed blocks */
/*
* Two cases for which we want to advance snd_nxt:
* i) snd_nxt lies between end of one hole and beginning of another
* ii) snd_nxt lies between end of last hole and rcv_lastsack
*/
while ((n = TAILQ_NEXT(cur, sackhole_q)) != NULL) {
if (SEQ_LT(tp->snd_nxt, cur->end))
return;
if (SEQ_GEQ(tp->snd_nxt, n->start))
cur = n;
else {
tp->snd_nxt = n->start;
return;
}
}
if (SEQ_LT(tp->snd_nxt, cur->end))
return;
tp->snd_nxt = tp->rcv_lastsack;
return;
}
int
tcp_sack_numblks(const struct tcpcb *tp)
{
int numblks;
if (!TCP_SACK_ENABLED(tp)) {
return 0;
}
numblks = (((tp->rcv_sack_flags & TCPSACK_HAVED) != 0) ? 1 : 0) +
tp->t_segqlen;
if (numblks == 0) {
return 0;
}
if (numblks > TCP_SACK_MAX) {
numblks = TCP_SACK_MAX;
}
return numblks;
}
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