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freebsd/sys/netinet/tcp_reass.c
Gleb Smirnoff c669105d17 - Remove net.inet.tcp.reass.overflows sysctl. It counts exactly
same events that tcpstat's tcps_rcvmemdrop counter counts.
- Rename tcps_rcvmemdrop to tcps_rcvreassfull and improve its
  description in netstat(1) output.

Sponsored by:	Netflix
Sponsored by:	Nginx, Inc.
2014-05-06 00:00:07 +00:00

262 lines
6.9 KiB
C

/*-
* 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_input.c 8.12 (Berkeley) 5/24/95
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_inet.h"
#include "opt_inet6.h"
#include "opt_tcpdebug.h"
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/sysctl.h>
#include <sys/syslog.h>
#include <sys/systm.h>
#include <vm/uma.h>
#include <net/if.h>
#include <net/if_var.h>
#include <net/route.h>
#include <net/vnet.h>
#include <netinet/in.h>
#include <netinet/in_pcb.h>
#include <netinet/in_systm.h>
#include <netinet/in_var.h>
#include <netinet/ip.h>
#include <netinet/ip_var.h>
#include <netinet/ip_options.h>
#include <netinet/ip6.h>
#include <netinet6/in6_pcb.h>
#include <netinet6/ip6_var.h>
#include <netinet6/nd6.h>
#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 <netinet6/tcp6_var.h>
#include <netinet/tcpip.h>
void
tcp_reass_flush(struct tcpcb *tp)
{
struct mbuf *m;
INP_WLOCK_ASSERT(tp->t_inpcb);
while ((m = tp->t_segq) != NULL) {
tp->t_segq = m->m_nextpkt;
tp->t_segqlen -= m->m_pkthdr.len;
m_freem(m);
}
KASSERT((tp->t_segqlen == 0),
("TCP reass queue %p length is %d instead of 0 after flush.",
tp, tp->t_segqlen));
}
#define M_TCPHDR(m) ((struct tcphdr *)((m)->m_pkthdr.pkt_tcphdr))
int
tcp_reass(struct tcpcb *tp, struct tcphdr *th, int *tlenp, struct mbuf *m)
{
struct socket *so = tp->t_inpcb->inp_socket;
struct mbuf *mq, *mp;
int flags, wakeup;
INP_WLOCK_ASSERT(tp->t_inpcb);
/*
* XXX: tcp_reass() is rather inefficient with its data structures
* and should be rewritten (see NetBSD for optimizations).
*/
/*
* Call with th==NULL after become established to
* force pre-ESTABLISHED data up to user socket.
*/
if (th == NULL)
goto present;
M_ASSERTPKTHDR(m);
KASSERT(*tlenp == m->m_pkthdr.len, ("%s: tlenp %u len %u", __func__,
*tlenp, m->m_pkthdr.len));
/*
* Limit the number of segments that can be queued to reduce the
* potential for mbuf exhaustion. For best performance, we want to be
* able to queue a full window's worth of segments. The size of the
* socket receive buffer determines our advertised window and grows
* automatically when socket buffer autotuning is enabled. Use it as the
* basis for our queue limit.
* Always let the missing segment through which caused this queue.
* NB: Access to the socket buffer is left intentionally unlocked as we
* can tolerate stale information here.
*/
if ((th->th_seq != tp->rcv_nxt || !TCPS_HAVEESTABLISHED(tp->t_state)) &&
tp->t_segqlen + m->m_pkthdr.len >= sbspace(&so->so_rcv)) {
char *s;
TCPSTAT_INC(tcps_rcvreassfull);
*tlenp = 0;
if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL,
NULL))) {
log(LOG_DEBUG, "%s; %s: queue limit reached, "
"segment dropped\n", s, __func__);
free(s, M_TCPLOG);
}
m_freem(m);
return (0);
}
/*
* Find a segment which begins after this one does.
*/
mp = NULL;
for (mq = tp->t_segq; mq != NULL; mq = mq->m_nextpkt) {
if (SEQ_GT(M_TCPHDR(mq)->th_seq, th->th_seq))
break;
mp = mq;
}
/*
* If there is a preceding segment, it may provide some of
* our data already. If so, drop the data from the incoming
* segment. If it provides all of our data, drop us.
*/
if (mp != NULL) {
int i;
/* conversion to int (in i) handles seq wraparound */
i = M_TCPHDR(mp)->th_seq + mp->m_pkthdr.len - th->th_seq;
if (i > 0) {
if (i >= *tlenp) {
TCPSTAT_INC(tcps_rcvduppack);
TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp);
m_freem(m);
/*
* Try to present any queued data
* at the left window edge to the user.
* This is needed after the 3-WHS
* completes.
*/
goto present; /* ??? */
}
m_adj(m, i);
*tlenp -= i;
th->th_seq += i;
}
}
tp->t_rcvoopack++;
TCPSTAT_INC(tcps_rcvoopack);
TCPSTAT_ADD(tcps_rcvoobyte, *tlenp);
/*
* While we overlap succeeding segments trim them or,
* if they are completely covered, dequeue them.
*/
while (mq) {
struct mbuf *nq;
int i;
i = (th->th_seq + *tlenp) - M_TCPHDR(mq)->th_seq;
if (i <= 0)
break;
if (i < mq->m_pkthdr.len) {
M_TCPHDR(mq)->th_seq += i;
m_adj(mq, i);
tp->t_segqlen -= i;
break;
}
nq = mq->m_nextpkt;
tp->t_segqlen -= mq->m_pkthdr.len;
m_freem(mq);
if (mp)
mp->m_nextpkt = nq;
else
tp->t_segq = nq;
mq = nq;
}
/* Insert the new segment queue entry into place. */
if (mp) {
m->m_nextpkt = mp->m_nextpkt;
mp->m_nextpkt = m;
} else {
m->m_nextpkt = tp->t_segq;
tp->t_segq = m ;
}
m->m_pkthdr.pkt_tcphdr = th;
tp->t_segqlen += m->m_pkthdr.len;
present:
/*
* Present data to user, advancing rcv_nxt through
* completed sequence space.
*/
if (!TCPS_HAVEESTABLISHED(tp->t_state))
return (0);
flags = 0;
wakeup = 0;
SOCKBUF_LOCK(&so->so_rcv);
while ((mq = tp->t_segq) != NULL &&
M_TCPHDR(mq)->th_seq == tp->rcv_nxt) {
tp->t_segq = mq->m_nextpkt;
tp->rcv_nxt += mq->m_pkthdr.len;
tp->t_segqlen -= mq->m_pkthdr.len;
flags = M_TCPHDR(mq)->th_flags & TH_FIN;
if (so->so_rcv.sb_state & SBS_CANTRCVMORE)
m_freem(mq);
else {
mq->m_nextpkt = NULL;
sbappendstream_locked(&so->so_rcv, mq);
wakeup = 1;
}
}
ND6_HINT(tp);
if (wakeup)
sorwakeup_locked(so);
else
SOCKBUF_UNLOCK(&so->so_rcv);
return (flags);
}