1/*-
2 * Copyright (c) 2000 Ruslan Ermilov and Brian Somers <brian@Awfulhak.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 *
| 1/*-
2 * Copyright (c) 2000 Ruslan Ermilov and Brian Somers <brian@Awfulhak.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 *
|
26 * $FreeBSD: head/usr.sbin/ppp/tcpmss.c 69303 2000-11-28 13:18:35Z brian $
| 26 * $FreeBSD: head/usr.sbin/ppp/tcpmss.c 78410 2001-06-18 14:59:36Z brian $
|
27 */
28
29#include <sys/param.h>
30
| 27 */
28
29#include <sys/param.h>
30
|
| 31#include <sys/socket.h>
32#include <net/route.h>
|
31#include <netinet/in_systm.h>
32#include <netinet/in.h>
33#include <netinet/ip.h>
34#include <netinet/tcp.h>
35#include <sys/un.h>
36
37#include <termios.h>
38
39#include "layer.h"
40#include "defs.h"
41#include "log.h"
42#include "timer.h"
43#include "fsm.h"
44#include "mbuf.h"
45#include "throughput.h"
46#include "lqr.h"
47#include "hdlc.h"
48#include "lcp.h"
49#include "ccp.h"
50#include "link.h"
51#include "iplist.h"
52#include "slcompress.h"
53#include "ipcp.h"
54#include "filter.h"
55#include "descriptor.h"
56#include "mp.h"
| 33#include <netinet/in_systm.h>
34#include <netinet/in.h>
35#include <netinet/ip.h>
36#include <netinet/tcp.h>
37#include <sys/un.h>
38
39#include <termios.h>
40
41#include "layer.h"
42#include "defs.h"
43#include "log.h"
44#include "timer.h"
45#include "fsm.h"
46#include "mbuf.h"
47#include "throughput.h"
48#include "lqr.h"
49#include "hdlc.h"
50#include "lcp.h"
51#include "ccp.h"
52#include "link.h"
53#include "iplist.h"
54#include "slcompress.h"
55#include "ipcp.h"
56#include "filter.h"
57#include "descriptor.h"
58#include "mp.h"
|
| 59#include "iface.h"
|
57#ifndef NORADIUS
58#include "radius.h"
59#endif
60#include "bundle.h"
61
62
63/*-
64 * We are in a liberal position about MSS
65 * (RFC 879, section 7).
66 */
67#define MAXMSS(mtu) (mtu - sizeof(struct ip) - sizeof(struct tcphdr))
68
69
70static void MSSFixup(struct tcphdr *, ssize_t, u_int16_t);
71
72
73static struct mbuf *
74tcpmss_LayerPush(struct bundle *bundle, struct link *l, struct mbuf *bp,
75 int pri, u_short *proto)
76{
77 struct ip *pip;
78 int hlen, plen;
79
80 if (!Enabled(bundle, OPT_TCPMSSFIXUP))
81 return bp;
82
83 bp = m_pullup(bp);
84 plen = m_length(bp);
85 pip = (struct ip *)MBUF_CTOP(bp);
86 hlen = pip->ip_hl << 2;
87
88 /*
89 * Check for MSS option only for TCP packets with zero fragment offsets
90 * and correct total and header lengths.
91 */
92 if (pip->ip_p == IPPROTO_TCP && (ntohs(pip->ip_off) & IP_OFFMASK) == 0 &&
93 ntohs(pip->ip_len) == plen && hlen <= plen &&
94 plen - hlen >= sizeof(struct tcphdr))
95 MSSFixup((struct tcphdr *)(MBUF_CTOP(bp) + hlen), plen - hlen,
| 60#ifndef NORADIUS
61#include "radius.h"
62#endif
63#include "bundle.h"
64
65
66/*-
67 * We are in a liberal position about MSS
68 * (RFC 879, section 7).
69 */
70#define MAXMSS(mtu) (mtu - sizeof(struct ip) - sizeof(struct tcphdr))
71
72
73static void MSSFixup(struct tcphdr *, ssize_t, u_int16_t);
74
75
76static struct mbuf *
77tcpmss_LayerPush(struct bundle *bundle, struct link *l, struct mbuf *bp,
78 int pri, u_short *proto)
79{
80 struct ip *pip;
81 int hlen, plen;
82
83 if (!Enabled(bundle, OPT_TCPMSSFIXUP))
84 return bp;
85
86 bp = m_pullup(bp);
87 plen = m_length(bp);
88 pip = (struct ip *)MBUF_CTOP(bp);
89 hlen = pip->ip_hl << 2;
90
91 /*
92 * Check for MSS option only for TCP packets with zero fragment offsets
93 * and correct total and header lengths.
94 */
95 if (pip->ip_p == IPPROTO_TCP && (ntohs(pip->ip_off) & IP_OFFMASK) == 0 &&
96 ntohs(pip->ip_len) == plen && hlen <= plen &&
97 plen - hlen >= sizeof(struct tcphdr))
98 MSSFixup((struct tcphdr *)(MBUF_CTOP(bp) + hlen), plen - hlen,
|
96 MAXMSS(bundle->mtu));
| 99 MAXMSS(bundle->iface->mtu));
|
97
98 return bp;
99}
100
101/*-
102 * The following macro is used to update an
103 * internet checksum. "acc" is a 32-bit
104 * accumulation of all the changes to the
105 * checksum (adding in old 16-bit words and
106 * subtracting out new words), and "cksum"
107 * is the checksum value to be updated.
108 */
109#define ADJUST_CHECKSUM(acc, cksum) { \
110 acc += cksum; \
111 if (acc < 0) { \
112 acc = -acc; \
113 acc = (acc >> 16) + (acc & 0xffff); \
114 acc += acc >> 16; \
115 cksum = (u_short) ~acc; \
116 } else { \
117 acc = (acc >> 16) + (acc & 0xffff); \
118 acc += acc >> 16; \
119 cksum = (u_short) acc; \
120 } \
121}
122
123static void
124MSSFixup(struct tcphdr *tc, ssize_t pktlen, u_int16_t maxmss)
125{
126 int hlen, olen, optlen;
127 u_char *opt;
128 u_int16_t *mss;
129 int accumulate;
130
131 hlen = tc->th_off << 2;
132
133 /* Invalid header length or header without options. */
134 if (hlen <= sizeof(struct tcphdr) || hlen > pktlen)
135 return;
136
137 /* MSS option only allowed within SYN packets. */
138 if (!(tc->th_flags & TH_SYN))
139 return;
140
141 for (olen = hlen - sizeof(struct tcphdr), opt = (u_char *)(tc + 1);
142 olen > 0; olen -= optlen, opt += optlen) {
143 if (*opt == TCPOPT_EOL)
144 break;
145 else if (*opt == TCPOPT_NOP)
146 optlen = 1;
147 else {
148 optlen = *(opt + 1);
149 if (optlen <= 0 || optlen > olen)
150 break;
151 if (*opt == TCPOPT_MAXSEG) {
152 if (optlen != TCPOLEN_MAXSEG)
153 continue;
154 mss = (u_int16_t *)(opt + 2);
155 if (ntohs(*mss) > maxmss) {
156 log_Printf(LogDEBUG, "MSS: %u -> %u\n",
157 ntohs(*mss), maxmss);
158 accumulate = *mss;
159 *mss = htons(maxmss);
160 accumulate -= *mss;
161 ADJUST_CHECKSUM(accumulate, tc->th_sum);
162 }
163 }
164 }
165 }
166}
167
168struct layer tcpmsslayer = { LAYER_PROTO, "tcpmss", tcpmss_LayerPush, NULL };
| 100
101 return bp;
102}
103
104/*-
105 * The following macro is used to update an
106 * internet checksum. "acc" is a 32-bit
107 * accumulation of all the changes to the
108 * checksum (adding in old 16-bit words and
109 * subtracting out new words), and "cksum"
110 * is the checksum value to be updated.
111 */
112#define ADJUST_CHECKSUM(acc, cksum) { \
113 acc += cksum; \
114 if (acc < 0) { \
115 acc = -acc; \
116 acc = (acc >> 16) + (acc & 0xffff); \
117 acc += acc >> 16; \
118 cksum = (u_short) ~acc; \
119 } else { \
120 acc = (acc >> 16) + (acc & 0xffff); \
121 acc += acc >> 16; \
122 cksum = (u_short) acc; \
123 } \
124}
125
126static void
127MSSFixup(struct tcphdr *tc, ssize_t pktlen, u_int16_t maxmss)
128{
129 int hlen, olen, optlen;
130 u_char *opt;
131 u_int16_t *mss;
132 int accumulate;
133
134 hlen = tc->th_off << 2;
135
136 /* Invalid header length or header without options. */
137 if (hlen <= sizeof(struct tcphdr) || hlen > pktlen)
138 return;
139
140 /* MSS option only allowed within SYN packets. */
141 if (!(tc->th_flags & TH_SYN))
142 return;
143
144 for (olen = hlen - sizeof(struct tcphdr), opt = (u_char *)(tc + 1);
145 olen > 0; olen -= optlen, opt += optlen) {
146 if (*opt == TCPOPT_EOL)
147 break;
148 else if (*opt == TCPOPT_NOP)
149 optlen = 1;
150 else {
151 optlen = *(opt + 1);
152 if (optlen <= 0 || optlen > olen)
153 break;
154 if (*opt == TCPOPT_MAXSEG) {
155 if (optlen != TCPOLEN_MAXSEG)
156 continue;
157 mss = (u_int16_t *)(opt + 2);
158 if (ntohs(*mss) > maxmss) {
159 log_Printf(LogDEBUG, "MSS: %u -> %u\n",
160 ntohs(*mss), maxmss);
161 accumulate = *mss;
162 *mss = htons(maxmss);
163 accumulate -= *mss;
164 ADJUST_CHECKSUM(accumulate, tc->th_sum);
165 }
166 }
167 }
168 }
169}
170
171struct layer tcpmsslayer = { LAYER_PROTO, "tcpmss", tcpmss_LayerPush, NULL };
|