mirror of
https://git.FreeBSD.org/src.git
synced 2024-12-17 10:26:15 +00:00
d593906199
PR: 32717 Submitted by: MORI Kouji <moriko@hh.iij4u.or.jp> MFC after: 2 weeks
186 lines
5.0 KiB
C
186 lines
5.0 KiB
C
/*-
|
|
* Copyright (c) 2000 Ruslan Ermilov and Brian Somers <brian@Awfulhak.org>
|
|
* 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.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
|
|
*
|
|
* $FreeBSD$
|
|
*/
|
|
|
|
#include <sys/param.h>
|
|
|
|
#include <sys/socket.h>
|
|
#include <net/route.h>
|
|
#include <netinet/in_systm.h>
|
|
#include <netinet/in.h>
|
|
#include <netinet/ip.h>
|
|
#include <netinet/tcp.h>
|
|
#include <sys/un.h>
|
|
|
|
#include <termios.h>
|
|
|
|
#include "layer.h"
|
|
#include "defs.h"
|
|
#include "log.h"
|
|
#include "timer.h"
|
|
#include "fsm.h"
|
|
#include "mbuf.h"
|
|
#include "throughput.h"
|
|
#include "lqr.h"
|
|
#include "hdlc.h"
|
|
#include "lcp.h"
|
|
#include "ccp.h"
|
|
#include "link.h"
|
|
#include "iplist.h"
|
|
#include "slcompress.h"
|
|
#include "ncpaddr.h"
|
|
#include "ipcp.h"
|
|
#include "filter.h"
|
|
#include "descriptor.h"
|
|
#include "mp.h"
|
|
#include "iface.h"
|
|
#ifndef NORADIUS
|
|
#include "radius.h"
|
|
#endif
|
|
#include "ipv6cp.h"
|
|
#include "ncp.h"
|
|
#include "bundle.h"
|
|
|
|
|
|
/*-
|
|
* We are in a liberal position about MSS
|
|
* (RFC 879, section 7).
|
|
*/
|
|
#define MAXMSS(mtu) ((mtu) - sizeof(struct ip) - sizeof(struct tcphdr) - 12)
|
|
|
|
|
|
/*-
|
|
* The following macro is used to update an
|
|
* internet checksum. "acc" is a 32-bit
|
|
* accumulation of all the changes to the
|
|
* checksum (adding in old 16-bit words and
|
|
* subtracting out new words), and "cksum"
|
|
* is the checksum value to be updated.
|
|
*/
|
|
#define ADJUST_CHECKSUM(acc, cksum) { \
|
|
acc += cksum; \
|
|
if (acc < 0) { \
|
|
acc = -acc; \
|
|
acc = (acc >> 16) + (acc & 0xffff); \
|
|
acc += acc >> 16; \
|
|
cksum = (u_short) ~acc; \
|
|
} else { \
|
|
acc = (acc >> 16) + (acc & 0xffff); \
|
|
acc += acc >> 16; \
|
|
cksum = (u_short) acc; \
|
|
} \
|
|
}
|
|
|
|
static void
|
|
MSSFixup(struct tcphdr *tc, ssize_t pktlen, u_int16_t maxmss)
|
|
{
|
|
int hlen, olen, optlen;
|
|
u_char *opt;
|
|
u_int16_t *mss;
|
|
int accumulate;
|
|
|
|
hlen = tc->th_off << 2;
|
|
|
|
/* Invalid header length or header without options. */
|
|
if (hlen <= sizeof(struct tcphdr) || hlen > pktlen)
|
|
return;
|
|
|
|
/* MSS option only allowed within SYN packets. */
|
|
if (!(tc->th_flags & TH_SYN))
|
|
return;
|
|
|
|
for (olen = hlen - sizeof(struct tcphdr), opt = (u_char *)(tc + 1);
|
|
olen > 0; olen -= optlen, opt += optlen) {
|
|
if (*opt == TCPOPT_EOL)
|
|
break;
|
|
else if (*opt == TCPOPT_NOP)
|
|
optlen = 1;
|
|
else {
|
|
optlen = *(opt + 1);
|
|
if (optlen <= 0 || optlen > olen)
|
|
break;
|
|
if (*opt == TCPOPT_MAXSEG) {
|
|
if (optlen != TCPOLEN_MAXSEG)
|
|
continue;
|
|
mss = (u_int16_t *)(opt + 2);
|
|
if (ntohs(*mss) > maxmss) {
|
|
log_Printf(LogDEBUG, "MSS: %u -> %u\n",
|
|
ntohs(*mss), maxmss);
|
|
accumulate = *mss;
|
|
*mss = htons(maxmss);
|
|
accumulate -= *mss;
|
|
ADJUST_CHECKSUM(accumulate, tc->th_sum);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
static struct mbuf *
|
|
tcpmss_Check(struct bundle *bundle, struct mbuf *bp)
|
|
{
|
|
struct ip *pip;
|
|
int hlen, plen;
|
|
|
|
if (!Enabled(bundle, OPT_TCPMSSFIXUP))
|
|
return bp;
|
|
|
|
bp = m_pullup(bp);
|
|
plen = m_length(bp);
|
|
pip = (struct ip *)MBUF_CTOP(bp);
|
|
hlen = pip->ip_hl << 2;
|
|
|
|
/*
|
|
* Check for MSS option only for TCP packets with zero fragment offsets
|
|
* and correct total and header lengths.
|
|
*/
|
|
if (pip->ip_p == IPPROTO_TCP && (ntohs(pip->ip_off) & IP_OFFMASK) == 0 &&
|
|
ntohs(pip->ip_len) == plen && hlen <= plen &&
|
|
plen - hlen >= sizeof(struct tcphdr))
|
|
MSSFixup((struct tcphdr *)(MBUF_CTOP(bp) + hlen), plen - hlen,
|
|
MAXMSS(bundle->iface->mtu));
|
|
|
|
return bp;
|
|
}
|
|
|
|
static struct mbuf *
|
|
tcpmss_LayerPush(struct bundle *bundle, struct link *l, struct mbuf *bp,
|
|
int pri, u_short *proto)
|
|
{
|
|
return tcpmss_Check(bundle, bp);
|
|
}
|
|
|
|
static struct mbuf *
|
|
tcpmss_LayerPull(struct bundle *bundle, struct link *l, struct mbuf *bp,
|
|
u_short *proto)
|
|
{
|
|
return tcpmss_Check(bundle, bp);
|
|
}
|
|
|
|
struct layer tcpmsslayer =
|
|
{ LAYER_PROTO, "tcpmss", tcpmss_LayerPush, tcpmss_LayerPull };
|