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