print-sl.c revision 356341 
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#include "netdissect.h"
31#include "extract.h"
32
33#include "ip.h"
34#include "tcp.h"
35#include "slcompress.h"
36
37/*
38 * definitions of the pseudo- link-level header attached to slip
39 * packets grabbed by the packet filter (bpf) traffic monitor.
40 */
41#define SLIP_HDRLEN 16
42
43#define SLX_DIR 0
44#define SLX_CHDR 1
45#define CHDR_LEN 15
46
47#define SLIPDIR_IN 0
48#define SLIPDIR_OUT 1
49
50static const char tstr[] = "[|slip]";
51
52static u_int lastlen[2][256];
53static u_int lastconn = 255;
54
55static int sliplink_print(netdissect_options *, const u_char *, const struct ip *, u_int);
56static int compressed_sl_print(netdissect_options *, const u_char *, const struct ip *, u_int, int);
57
58u_int
59sl_if_print(netdissect_options *ndo,
60            const struct pcap_pkthdr *h, const u_char *p)
61{
62	register u_int caplen = h->caplen;
63	register u_int length = h->len;
64	register const struct ip *ip;
65
66	if (caplen < SLIP_HDRLEN || length < SLIP_HDRLEN) {
67		ND_PRINT((ndo, "%s", tstr));
68		return (caplen);
69	}
70
71	caplen -= SLIP_HDRLEN;
72	length -= SLIP_HDRLEN;
73
74	ip = (const struct ip *)(p + SLIP_HDRLEN);
75
76	if (ndo->ndo_eflag)
77		if (sliplink_print(ndo, p, ip, length) == -1) {
78			ND_PRINT((ndo, "%s", tstr));
79			return (caplen + SLIP_HDRLEN);
80	}
81
82	if (caplen < 1 || length < 1) {
83		ND_PRINT((ndo, "%s", tstr));
84		return (caplen + SLIP_HDRLEN);
85	}
86
87	switch (IP_V(ip)) {
88	case 4:
89	        ip_print(ndo, (const u_char *)ip, length);
90		break;
91	case 6:
92		ip6_print(ndo, (const u_char *)ip, length);
93		break;
94	default:
95		ND_PRINT((ndo, "ip v%d", IP_V(ip)));
96	}
97
98	return (SLIP_HDRLEN);
99}
100
101u_int
102sl_bsdos_if_print(netdissect_options *ndo,
103                  const struct pcap_pkthdr *h, const u_char *p)
104{
105	register u_int caplen = h->caplen;
106	register u_int length = h->len;
107	register const struct ip *ip;
108
109	if (caplen < SLIP_HDRLEN) {
110		ND_PRINT((ndo, "%s", tstr));
111		return (caplen);
112	}
113
114	length -= SLIP_HDRLEN;
115
116	ip = (const struct ip *)(p + SLIP_HDRLEN);
117
118#ifdef notdef
119	if (ndo->ndo_eflag)
120		sliplink_print(ndo, p, ip, length);
121#endif
122
123	ip_print(ndo, (const u_char *)ip, length);
124
125	return (SLIP_HDRLEN);
126}
127
128static int
129sliplink_print(netdissect_options *ndo,
130               register const u_char *p, register const struct ip *ip,
131               register u_int length)
132{
133	int dir;
134	u_int hlen;
135
136	dir = p[SLX_DIR];
137	switch (dir) {
138
139	case SLIPDIR_IN:
140		ND_PRINT((ndo, "I "));
141		break;
142
143	case SLIPDIR_OUT:
144		ND_PRINT((ndo, "O "));
145		break;
146
147	default:
148		ND_PRINT((ndo, "Invalid direction %d ", dir));
149		dir = -1;
150		break;
151	}
152	if (ndo->ndo_nflag) {
153		/* XXX just dump the header */
154		register int i;
155
156		for (i = SLX_CHDR; i < SLX_CHDR + CHDR_LEN - 1; ++i)
157			ND_PRINT((ndo, "%02x.", p[i]));
158		ND_PRINT((ndo, "%02x: ", p[SLX_CHDR + CHDR_LEN - 1]));
159		return 0;
160	}
161	switch (p[SLX_CHDR] & 0xf0) {
162
163	case TYPE_IP:
164		ND_PRINT((ndo, "ip %d: ", length + SLIP_HDRLEN));
165		break;
166
167	case TYPE_UNCOMPRESSED_TCP:
168		/*
169		 * The connection id is stored in the IP protocol field.
170		 * Get it from the link layer since sl_uncompress_tcp()
171		 * has restored the IP header copy to IPPROTO_TCP.
172		 */
173		lastconn = ((const struct ip *)&p[SLX_CHDR])->ip_p;
174		ND_PRINT((ndo, "utcp %d: ", lastconn));
175		if (dir == -1) {
176			/* Direction is bogus, don't use it */
177			return 0;
178		}
179		ND_TCHECK(*ip);
180		hlen = IP_HL(ip);
181		ND_TCHECK(*((const struct tcphdr *)&((const int *)ip)[hlen]));
182		hlen += TH_OFF((const struct tcphdr *)&((const int *)ip)[hlen]);
183		lastlen[dir][lastconn] = length - (hlen << 2);
184		break;
185
186	default:
187		if (dir == -1) {
188			/* Direction is bogus, don't use it */
189			return 0;
190		}
191		if (p[SLX_CHDR] & TYPE_COMPRESSED_TCP) {
192			if (compressed_sl_print(ndo, &p[SLX_CHDR], ip,
193						length, dir) == -1)
194				goto trunc;
195			ND_PRINT((ndo, ": "));
196		} else
197			ND_PRINT((ndo, "slip-%d!: ", p[SLX_CHDR]));
198	}
199	return 0;
200trunc:
201	return -1;
202}
203
204static const u_char *
205print_sl_change(netdissect_options *ndo,
206                const char *str, register const u_char *cp)
207{
208	register u_int i;
209
210	if ((i = *cp++) == 0) {
211		i = EXTRACT_16BITS(cp);
212		cp += 2;
213	}
214	ND_PRINT((ndo, " %s%d", str, i));
215	return (cp);
216}
217
218static const u_char *
219print_sl_winchange(netdissect_options *ndo,
220                   register const u_char *cp)
221{
222	register short i;
223
224	if ((i = *cp++) == 0) {
225		i = EXTRACT_16BITS(cp);
226		cp += 2;
227	}
228	if (i >= 0)
229		ND_PRINT((ndo, " W+%d", i));
230	else
231		ND_PRINT((ndo, " W%d", i));
232	return (cp);
233}
234
235static int
236compressed_sl_print(netdissect_options *ndo,
237                    const u_char *chdr, const struct ip *ip,
238                    u_int length, int dir)
239{
240	register const u_char *cp = chdr;
241	register u_int flags, hlen;
242
243	flags = *cp++;
244	if (flags & NEW_C) {
245		lastconn = *cp++;
246		ND_PRINT((ndo, "ctcp %d", lastconn));
247	} else
248		ND_PRINT((ndo, "ctcp *"));
249
250	/* skip tcp checksum */
251	cp += 2;
252
253	switch (flags & SPECIALS_MASK) {
254	case SPECIAL_I:
255		ND_PRINT((ndo, " *SA+%d", lastlen[dir][lastconn]));
256		break;
257
258	case SPECIAL_D:
259		ND_PRINT((ndo, " *S+%d", lastlen[dir][lastconn]));
260		break;
261
262	default:
263		if (flags & NEW_U)
264			cp = print_sl_change(ndo, "U=", cp);
265		if (flags & NEW_W)
266			cp = print_sl_winchange(ndo, cp);
267		if (flags & NEW_A)
268			cp = print_sl_change(ndo, "A+", cp);
269		if (flags & NEW_S)
270			cp = print_sl_change(ndo, "S+", cp);
271		break;
272	}
273	if (flags & NEW_I)
274		cp = print_sl_change(ndo, "I+", cp);
275
276	/*
277	 * 'hlen' is the length of the uncompressed TCP/IP header (in words).
278	 * 'cp - chdr' is the length of the compressed header.
279	 * 'length - hlen' is the amount of data in the packet.
280	 */
281	ND_TCHECK(*ip);
282	hlen = IP_HL(ip);
283	ND_TCHECK(*((const struct tcphdr *)&((const int32_t *)ip)[hlen]));
284	hlen += TH_OFF((const struct tcphdr *)&((const int32_t *)ip)[hlen]);
285	lastlen[dir][lastconn] = length - (hlen << 2);
286	ND_PRINT((ndo, " %d (%ld)", lastlen[dir][lastconn], (long)(cp - chdr)));
287	return 0;
288trunc:
289	return -1;
290}
291