1/*
2 * Copyright (c) 1989, 1990, 1991, 1993, 1994, 1995, 1996, 1997
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that: (1) source code distributions
7 * retain the above copyright notice and this paragraph in its entirety, (2)
8 * distributions including binary code include the above copyright notice and
9 * this paragraph in its entirety in the documentation or other materials
10 * provided with the distribution, and (3) all advertising materials mentioning
11 * features or use of this software display the following acknowledgement:
12 * ``This product includes software developed by the University of California,
13 * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
14 * the University nor the names of its contributors may be used to endorse
15 * or promote products derived from this software without specific prior
16 * written permission.
17 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
18 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
19 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
20 */
21
22/* \summary: Compressed Serial Line Internet Protocol printer */
23
24#ifdef HAVE_CONFIG_H
25#include <config.h>
26#endif
27
28#include "netdissect-stdinc.h"
29
30#define ND_LONGJMP_FROM_TCHECK
31#include "netdissect.h"
32#include "extract.h"
33
34#include "ip.h"
35#include "tcp.h"
36#include "slcompress.h"
37
38/*
39 * definitions of the pseudo- link-level header attached to slip
40 * packets grabbed by the packet filter (bpf) traffic monitor.
41 */
42#define SLIP_HDRLEN 16
43
44#define SLX_DIR 0
45#define SLX_CHDR 1
46
47#define SLIPDIR_IN 0
48#define SLIPDIR_OUT 1
49
50
51static u_int lastlen[2][256];
52static u_int lastconn = 255;
53
54static void sliplink_print(netdissect_options *, const u_char *, const struct ip *, u_int);
55static void compressed_sl_print(netdissect_options *, const u_char *, const struct ip *, u_int, int);
56
57void
58sl_if_print(netdissect_options *ndo,
59            const struct pcap_pkthdr *h, const u_char *p)
60{
61	u_int length = h->len;
62	const struct ip *ip;
63
64	ndo->ndo_protocol = "slip";
65	ND_TCHECK_LEN(p, SLIP_HDRLEN);
66	ndo->ndo_ll_hdr_len += SLIP_HDRLEN;
67
68	length -= SLIP_HDRLEN;
69
70	ip = (const struct ip *)(p + SLIP_HDRLEN);
71
72	if (ndo->ndo_eflag)
73		sliplink_print(ndo, p, ip, length);
74
75	switch (IP_V(ip)) {
76	case 4:
77	        ip_print(ndo, (const u_char *)ip, length);
78		break;
79	case 6:
80		ip6_print(ndo, (const u_char *)ip, length);
81		break;
82	default:
83		ND_PRINT("ip v%u", IP_V(ip));
84	}
85}
86
87void
88sl_bsdos_if_print(netdissect_options *ndo,
89                  const struct pcap_pkthdr *h, const u_char *p)
90{
91	u_int length = h->len;
92	const struct ip *ip;
93
94	ndo->ndo_protocol = "slip_bsdos";
95	ND_TCHECK_LEN(p, SLIP_HDRLEN);
96	ndo->ndo_ll_hdr_len += SLIP_HDRLEN;
97
98	length -= SLIP_HDRLEN;
99
100	ip = (const struct ip *)(p + SLIP_HDRLEN);
101
102#ifdef notdef
103	if (ndo->ndo_eflag)
104		sliplink_print(ndo, p, ip, length);
105#endif
106
107	ip_print(ndo, (const u_char *)ip, length);
108}
109
110static void
111sliplink_print(netdissect_options *ndo,
112               const u_char *p, const struct ip *ip,
113               u_int length)
114{
115	int dir;
116	u_int hlen;
117
118	dir = GET_U_1(p + SLX_DIR);
119	switch (dir) {
120
121	case SLIPDIR_IN:
122		ND_PRINT("I ");
123		break;
124
125	case SLIPDIR_OUT:
126		ND_PRINT("O ");
127		break;
128
129	default:
130		ND_PRINT("Invalid direction %d ", dir);
131		dir = -1;
132		break;
133	}
134	switch (GET_U_1(p + SLX_CHDR) & 0xf0) {
135
136	case TYPE_IP:
137		ND_PRINT("ip %u: ", length + SLIP_HDRLEN);
138		break;
139
140	case TYPE_UNCOMPRESSED_TCP:
141		/*
142		 * The connection id is stored in the IP protocol field.
143		 * Get it from the link layer since sl_uncompress_tcp()
144		 * has restored the IP header copy to IPPROTO_TCP.
145		 */
146		lastconn = GET_U_1(((const struct ip *)(p + SLX_CHDR))->ip_p);
147		ND_PRINT("utcp %u: ", lastconn);
148		if (dir == -1) {
149			/* Direction is bogus, don't use it */
150			return;
151		}
152		ND_TCHECK_SIZE(ip);
153		hlen = IP_HL(ip);
154		ND_TCHECK_SIZE((const struct tcphdr *)&((const int *)ip)[hlen]);
155		hlen += TH_OFF((const struct tcphdr *)&((const int *)ip)[hlen]);
156		lastlen[dir][lastconn] = length - (hlen << 2);
157		break;
158
159	default:
160		if (dir == -1) {
161			/* Direction is bogus, don't use it */
162			return;
163		}
164		if (GET_U_1(p + SLX_CHDR) & TYPE_COMPRESSED_TCP) {
165			compressed_sl_print(ndo, p + SLX_CHDR, ip, length, dir);
166			ND_PRINT(": ");
167		} else
168			ND_PRINT("slip-%u!: ", GET_U_1(p + SLX_CHDR));
169	}
170}
171
172static const u_char *
173print_sl_change(netdissect_options *ndo,
174                const char *str, const u_char *cp)
175{
176	u_int i;
177
178	if ((i = GET_U_1(cp)) == 0) {
179		cp++;
180		i = GET_BE_U_2(cp);
181		cp += 2;
182	}
183	ND_PRINT(" %s%u", str, i);
184	return (cp);
185}
186
187static const u_char *
188print_sl_winchange(netdissect_options *ndo,
189                   const u_char *cp)
190{
191	int16_t i;
192
193	if ((i = GET_U_1(cp)) == 0) {
194		cp++;
195		i = GET_BE_S_2(cp);
196		cp += 2;
197	}
198	if (i >= 0)
199		ND_PRINT(" W+%d", i);
200	else
201		ND_PRINT(" W%d", i);
202	return (cp);
203}
204
205static void
206compressed_sl_print(netdissect_options *ndo,
207                    const u_char *chdr, const struct ip *ip,
208                    u_int length, int dir)
209{
210	const u_char *cp = chdr;
211	u_int flags, hlen;
212
213	flags = GET_U_1(cp);
214	cp++;
215	if (flags & NEW_C) {
216		lastconn = GET_U_1(cp);
217		cp++;
218		ND_PRINT("ctcp %u", lastconn);
219	} else
220		ND_PRINT("ctcp *");
221
222	/* skip tcp checksum */
223	cp += 2;
224
225	switch (flags & SPECIALS_MASK) {
226	case SPECIAL_I:
227		ND_PRINT(" *SA+%u", lastlen[dir][lastconn]);
228		break;
229
230	case SPECIAL_D:
231		ND_PRINT(" *S+%u", lastlen[dir][lastconn]);
232		break;
233
234	default:
235		if (flags & NEW_U)
236			cp = print_sl_change(ndo, "U=", cp);
237		if (flags & NEW_W)
238			cp = print_sl_winchange(ndo, cp);
239		if (flags & NEW_A)
240			cp = print_sl_change(ndo, "A+", cp);
241		if (flags & NEW_S)
242			cp = print_sl_change(ndo, "S+", cp);
243		break;
244	}
245	if (flags & NEW_I)
246		cp = print_sl_change(ndo, "I+", cp);
247
248	/*
249	 * 'hlen' is the length of the uncompressed TCP/IP header (in words).
250	 * 'cp - chdr' is the length of the compressed header.
251	 * 'length - hlen' is the amount of data in the packet.
252	 */
253	ND_TCHECK_SIZE(ip);
254	hlen = IP_HL(ip);
255	ND_TCHECK_SIZE((const struct tcphdr *)&((const int32_t *)ip)[hlen]);
256	hlen += TH_OFF((const struct tcphdr *)&((const int32_t *)ip)[hlen]);
257	lastlen[dir][lastconn] = length - (hlen << 2);
258	ND_PRINT(" %u (%ld)", lastlen[dir][lastconn], (long)(cp - chdr));
259}
260