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#include <sys/cdefs.h>
23#ifndef lint
24__RCSID("$NetBSD: print-sl.c,v 1.10 2023/08/17 20:19:40 christos Exp $");
25#endif
26
27/* \summary: Compressed Serial Line Internet Protocol printer */
28
29#ifdef HAVE_CONFIG_H
30#include <config.h>
31#endif
32
33#include "netdissect-stdinc.h"
34
35#define ND_LONGJMP_FROM_TCHECK
36#include "netdissect.h"
37#include "extract.h"
38
39#include "ip.h"
40#include "tcp.h"
41#include "slcompress.h"
42
43/*
44 * definitions of the pseudo- link-level header attached to slip
45 * packets grabbed by the packet filter (bpf) traffic monitor.
46 */
47#define SLIP_HDRLEN 16
48
49#define SLX_DIR 0
50#define SLX_CHDR 1
51
52#define SLIPDIR_IN 0
53#define SLIPDIR_OUT 1
54
55
56static u_int lastlen[2][256];
57static u_int lastconn = 255;
58
59static void sliplink_print(netdissect_options *, const u_char *, const struct ip *, u_int);
60static void compressed_sl_print(netdissect_options *, const u_char *, const struct ip *, u_int, int);
61
62void
63sl_if_print(netdissect_options *ndo,
64            const struct pcap_pkthdr *h, const u_char *p)
65{
66	u_int length = h->len;
67	const struct ip *ip;
68
69	ndo->ndo_protocol = "slip";
70	ND_TCHECK_LEN(p, SLIP_HDRLEN);
71	ndo->ndo_ll_hdr_len += SLIP_HDRLEN;
72
73	length -= SLIP_HDRLEN;
74
75	ip = (const struct ip *)(p + SLIP_HDRLEN);
76
77	if (ndo->ndo_eflag)
78		sliplink_print(ndo, p, ip, length);
79
80	switch (IP_V(ip)) {
81	case 4:
82	        ip_print(ndo, (const u_char *)ip, length);
83		break;
84	case 6:
85		ip6_print(ndo, (const u_char *)ip, length);
86		break;
87	default:
88		ND_PRINT("ip v%u", IP_V(ip));
89	}
90}
91
92void
93sl_bsdos_if_print(netdissect_options *ndo,
94                  const struct pcap_pkthdr *h, const u_char *p)
95{
96	u_int length = h->len;
97	const struct ip *ip;
98
99	ndo->ndo_protocol = "slip_bsdos";
100	ND_TCHECK_LEN(p, SLIP_HDRLEN);
101	ndo->ndo_ll_hdr_len += SLIP_HDRLEN;
102
103	length -= SLIP_HDRLEN;
104
105	ip = (const struct ip *)(p + SLIP_HDRLEN);
106
107#ifdef notdef
108	if (ndo->ndo_eflag)
109		sliplink_print(ndo, p, ip, length);
110#endif
111
112	ip_print(ndo, (const u_char *)ip, length);
113}
114
115static void
116sliplink_print(netdissect_options *ndo,
117               const u_char *p, const struct ip *ip,
118               u_int length)
119{
120	int dir;
121	u_int hlen;
122
123	dir = GET_U_1(p + SLX_DIR);
124	switch (dir) {
125
126	case SLIPDIR_IN:
127		ND_PRINT("I ");
128		break;
129
130	case SLIPDIR_OUT:
131		ND_PRINT("O ");
132		break;
133
134	default:
135		ND_PRINT("Invalid direction %d ", dir);
136		dir = -1;
137		break;
138	}
139	switch (GET_U_1(p + SLX_CHDR) & 0xf0) {
140
141	case TYPE_IP:
142		ND_PRINT("ip %u: ", length + SLIP_HDRLEN);
143		break;
144
145	case TYPE_UNCOMPRESSED_TCP:
146		/*
147		 * The connection id is stored in the IP protocol field.
148		 * Get it from the link layer since sl_uncompress_tcp()
149		 * has restored the IP header copy to IPPROTO_TCP.
150		 */
151		lastconn = GET_U_1(((const struct ip *)(p + SLX_CHDR))->ip_p);
152		ND_PRINT("utcp %u: ", lastconn);
153		if (dir == -1) {
154			/* Direction is bogus, don't use it */
155			return;
156		}
157		ND_TCHECK_SIZE(ip);
158		hlen = IP_HL(ip);
159		ND_TCHECK_SIZE((const struct tcphdr *)&((const int *)ip)[hlen]);
160		hlen += TH_OFF((const struct tcphdr *)&((const int *)ip)[hlen]);
161		lastlen[dir][lastconn] = length - (hlen << 2);
162		break;
163
164	default:
165		if (dir == -1) {
166			/* Direction is bogus, don't use it */
167			return;
168		}
169		if (GET_U_1(p + SLX_CHDR) & TYPE_COMPRESSED_TCP) {
170			compressed_sl_print(ndo, p + SLX_CHDR, ip, length, dir);
171			ND_PRINT(": ");
172		} else
173			ND_PRINT("slip-%u!: ", GET_U_1(p + SLX_CHDR));
174	}
175}
176
177static const u_char *
178print_sl_change(netdissect_options *ndo,
179                const char *str, const u_char *cp)
180{
181	u_int i;
182
183	if ((i = GET_U_1(cp)) == 0) {
184		cp++;
185		i = GET_BE_U_2(cp);
186		cp += 2;
187	}
188	ND_PRINT(" %s%u", str, i);
189	return (cp);
190}
191
192static const u_char *
193print_sl_winchange(netdissect_options *ndo,
194                   const u_char *cp)
195{
196	int16_t i;
197
198	if ((i = GET_U_1(cp)) == 0) {
199		cp++;
200		i = GET_BE_S_2(cp);
201		cp += 2;
202	}
203	if (i >= 0)
204		ND_PRINT(" W+%d", i);
205	else
206		ND_PRINT(" W%d", i);
207	return (cp);
208}
209
210static void
211compressed_sl_print(netdissect_options *ndo,
212                    const u_char *chdr, const struct ip *ip,
213                    u_int length, int dir)
214{
215	const u_char *cp = chdr;
216	u_int flags, hlen;
217
218	flags = GET_U_1(cp);
219	cp++;
220	if (flags & NEW_C) {
221		lastconn = GET_U_1(cp);
222		cp++;
223		ND_PRINT("ctcp %u", lastconn);
224	} else
225		ND_PRINT("ctcp *");
226
227	/* skip tcp checksum */
228	cp += 2;
229
230	switch (flags & SPECIALS_MASK) {
231	case SPECIAL_I:
232		ND_PRINT(" *SA+%u", lastlen[dir][lastconn]);
233		break;
234
235	case SPECIAL_D:
236		ND_PRINT(" *S+%u", lastlen[dir][lastconn]);
237		break;
238
239	default:
240		if (flags & NEW_U)
241			cp = print_sl_change(ndo, "U=", cp);
242		if (flags & NEW_W)
243			cp = print_sl_winchange(ndo, cp);
244		if (flags & NEW_A)
245			cp = print_sl_change(ndo, "A+", cp);
246		if (flags & NEW_S)
247			cp = print_sl_change(ndo, "S+", cp);
248		break;
249	}
250	if (flags & NEW_I)
251		cp = print_sl_change(ndo, "I+", cp);
252
253	/*
254	 * 'hlen' is the length of the uncompressed TCP/IP header (in words).
255	 * 'cp - chdr' is the length of the compressed header.
256	 * 'length - hlen' is the amount of data in the packet.
257	 */
258	ND_TCHECK_SIZE(ip);
259	hlen = IP_HL(ip);
260	ND_TCHECK_SIZE((const struct tcphdr *)&((const int32_t *)ip)[hlen]);
261	hlen += TH_OFF((const struct tcphdr *)&((const int32_t *)ip)[hlen]);
262	lastlen[dir][lastconn] = length - (hlen << 2);
263	ND_PRINT(" %u (%ld)", lastlen[dir][lastconn], (long)(cp - chdr));
264}
265