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1 /*
2  * Copyright (c) 1992, 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  * Code by Gert Doering, SpaceNet GmbH, gert@space.net
22  *
23  * Reference documentation:
24  *    http://www.cisco.com/univercd/cc/td/doc/product/lan/trsrb/frames.htm
25  */
26 
27 /* \summary: Cisco Discovery Protocol (CDP) printer */
28 
29 #ifdef HAVE_CONFIG_H
30 #include "config.h"
31 #endif
32 
33 #include <netdissect-stdinc.h>
34 
35 #include <string.h>
36 
37 #include "netdissect.h"
38 #include "addrtoname.h"
39 #include "extract.h"
40 #include "nlpid.h"
41 
42 static const char tstr[] = "[|cdp]";
43 
44 #define CDP_HEADER_LEN             4
45 #define CDP_HEADER_VERSION_OFFSET  0
46 #define CDP_HEADER_TTL_OFFSET      1
47 #define CDP_HEADER_CHECKSUM_OFFSET 2
48 
49 #define CDP_TLV_HEADER_LEN  4
50 #define CDP_TLV_TYPE_OFFSET 0
51 #define CDP_TLV_LEN_OFFSET  2
52 
53 static const struct tok cdp_tlv_values[] = {
54     { 0x01,             "Device-ID"},
55     { 0x02,             "Address"},
56     { 0x03,             "Port-ID"},
57     { 0x04,             "Capability"},
58     { 0x05,             "Version String"},
59     { 0x06,             "Platform"},
60     { 0x07,             "Prefixes"},
61     { 0x08,             "Protocol-Hello option"},
62     { 0x09,             "VTP Management Domain"},
63     { 0x0a,             "Native VLAN ID"},
64     { 0x0b,             "Duplex"},
65     { 0x0e,             "ATA-186 VoIP VLAN request"},
66     { 0x0f,             "ATA-186 VoIP VLAN assignment"},
67     { 0x10,             "power consumption"},
68     { 0x11,             "MTU"},
69     { 0x12,             "AVVID trust bitmap"},
70     { 0x13,             "AVVID untrusted ports CoS"},
71     { 0x14,             "System Name"},
72     { 0x15,             "System Object ID (not decoded)"},
73     { 0x16,             "Management Addresses"},
74     { 0x17,             "Physical Location"},
75     { 0, NULL}
76 };
77 
78 static const struct tok cdp_capability_values[] = {
79     { 0x01,             "Router" },
80     { 0x02,             "Transparent Bridge" },
81     { 0x04,             "Source Route Bridge" },
82     { 0x08,             "L2 Switch" },
83     { 0x10,             "L3 capable" },
84     { 0x20,             "IGMP snooping" },
85     { 0x40,             "L1 capable" },
86     { 0, NULL }
87 };
88 
89 static int cdp_print_addr(netdissect_options *, const u_char *, int);
90 static int cdp_print_prefixes(netdissect_options *, const u_char *, int);
91 static unsigned long cdp_get_number(const u_char *, int);
92 
93 void
cdp_print(netdissect_options * ndo,const u_char * pptr,u_int length,u_int caplen)94 cdp_print(netdissect_options *ndo,
95           const u_char *pptr, u_int length, u_int caplen)
96 {
97 	int type, len, i, j;
98 	const u_char *tptr;
99 
100 	if (caplen < CDP_HEADER_LEN) {
101 		ND_PRINT((ndo, "%s", tstr));
102 		return;
103 	}
104 
105 	tptr = pptr; /* temporary pointer */
106 
107 	ND_TCHECK2(*tptr, CDP_HEADER_LEN);
108 	ND_PRINT((ndo, "CDPv%u, ttl: %us", *(tptr + CDP_HEADER_VERSION_OFFSET),
109 					   *(tptr + CDP_HEADER_TTL_OFFSET)));
110 	if (ndo->ndo_vflag)
111 		ND_PRINT((ndo, ", checksum: 0x%04x (unverified), length %u", EXTRACT_16BITS(tptr+CDP_HEADER_CHECKSUM_OFFSET), length));
112 	tptr += CDP_HEADER_LEN;
113 
114 	while (tptr < (pptr+length)) {
115 		ND_TCHECK2(*tptr, CDP_TLV_HEADER_LEN); /* read out Type and Length */
116 		type = EXTRACT_16BITS(tptr+CDP_TLV_TYPE_OFFSET);
117 		len  = EXTRACT_16BITS(tptr+CDP_TLV_LEN_OFFSET); /* object length includes the 4 bytes header length */
118 		if (len < CDP_TLV_HEADER_LEN) {
119 		    if (ndo->ndo_vflag)
120 			ND_PRINT((ndo, "\n\t%s (0x%02x), TLV length: %u byte%s (too short)",
121 			       tok2str(cdp_tlv_values,"unknown field type", type),
122 			       type,
123 			       len,
124 			       PLURAL_SUFFIX(len))); /* plural */
125 		    else
126 			ND_PRINT((ndo, ", %s TLV length %u too short",
127 			       tok2str(cdp_tlv_values,"unknown field type", type),
128 			       len));
129 		    break;
130 		}
131 		tptr += CDP_TLV_HEADER_LEN;
132 		len -= CDP_TLV_HEADER_LEN;
133 
134 		ND_TCHECK2(*tptr, len);
135 
136 		if (ndo->ndo_vflag || type == 1) { /* in non-verbose mode just print Device-ID */
137 
138 		    if (ndo->ndo_vflag)
139 			ND_PRINT((ndo, "\n\t%s (0x%02x), value length: %u byte%s: ",
140 			       tok2str(cdp_tlv_values,"unknown field type", type),
141 			       type,
142 			       len,
143 			       PLURAL_SUFFIX(len))); /* plural */
144 
145 		    switch (type) {
146 
147 		    case 0x01: /* Device-ID */
148 			if (!ndo->ndo_vflag)
149 			    ND_PRINT((ndo, ", Device-ID "));
150 			ND_PRINT((ndo, "'"));
151 			(void)fn_printn(ndo, tptr, len, NULL);
152 			ND_PRINT((ndo, "'"));
153 			break;
154 		    case 0x02: /* Address */
155 			if (cdp_print_addr(ndo, tptr, len) < 0)
156 			    goto trunc;
157 			break;
158 		    case 0x03: /* Port-ID */
159 			ND_PRINT((ndo, "'"));
160 			(void)fn_printn(ndo, tptr, len, NULL);
161 			ND_PRINT((ndo, "'"));
162 			break;
163 		    case 0x04: /* Capabilities */
164 			if (len < 4)
165 			    goto trunc;
166 			ND_PRINT((ndo, "(0x%08x): %s",
167 			       EXTRACT_32BITS(tptr),
168 			       bittok2str(cdp_capability_values, "none", EXTRACT_32BITS(tptr))));
169 			break;
170 		    case 0x05: /* Version */
171 			ND_PRINT((ndo, "\n\t  "));
172 			for (i=0;i<len;i++) {
173 			    j = *(tptr+i);
174 			    if (j == '\n') /* lets rework the version string to
175 					      get a nice indentation */
176 				ND_PRINT((ndo, "\n\t  "));
177 			    else
178 				fn_print_char(ndo, j);
179 			}
180 			break;
181 		    case 0x06: /* Platform */
182 			ND_PRINT((ndo, "'"));
183 			(void)fn_printn(ndo, tptr, len, NULL);
184 			ND_PRINT((ndo, "'"));
185 			break;
186 		    case 0x07: /* Prefixes */
187 			if (cdp_print_prefixes(ndo, tptr, len) < 0)
188 			    goto trunc;
189 			break;
190 		    case 0x08: /* Protocol Hello Option - not documented */
191 			break;
192 		    case 0x09: /* VTP Mgmt Domain  - CDPv2 */
193 			ND_PRINT((ndo, "'"));
194 			(void)fn_printn(ndo, tptr, len, NULL);
195 			ND_PRINT((ndo, "'"));
196 			break;
197 		    case 0x0a: /* Native VLAN ID - CDPv2 */
198 			if (len < 2)
199 			    goto trunc;
200 			ND_PRINT((ndo, "%d", EXTRACT_16BITS(tptr)));
201 			break;
202 		    case 0x0b: /* Duplex - CDPv2 */
203 			if (len < 1)
204 			    goto trunc;
205 			ND_PRINT((ndo, "%s", *(tptr) ? "full": "half"));
206 			break;
207 
208 		    /* http://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cata/186/2_12_m/english/release/notes/186rn21m.html
209 		     * plus more details from other sources
210 		     */
211 		    case 0x0e: /* ATA-186 VoIP VLAN request - incomplete doc. */
212 			if (len < 3)
213 			    goto trunc;
214 			ND_PRINT((ndo, "app %d, vlan %d", *(tptr), EXTRACT_16BITS(tptr + 1)));
215 			break;
216 		    case 0x10: /* ATA-186 VoIP VLAN assignment - incomplete doc. */
217 			ND_PRINT((ndo, "%1.2fW", cdp_get_number(tptr, len) / 1000.0));
218 			break;
219 		    case 0x11: /* MTU - not documented */
220 			if (len < 4)
221 			    goto trunc;
222 			ND_PRINT((ndo, "%u bytes", EXTRACT_32BITS(tptr)));
223 			break;
224 		    case 0x12: /* AVVID trust bitmap - not documented */
225 			if (len < 1)
226 			    goto trunc;
227 			ND_PRINT((ndo, "0x%02x", *(tptr)));
228 			break;
229 		    case 0x13: /* AVVID untrusted port CoS - not documented */
230 			if (len < 1)
231 			    goto trunc;
232 			ND_PRINT((ndo, "0x%02x", *(tptr)));
233 			break;
234 		    case 0x14: /* System Name - not documented */
235 			ND_PRINT((ndo, "'"));
236 			(void)fn_printn(ndo, tptr, len, NULL);
237 			ND_PRINT((ndo, "'"));
238 			break;
239 		    case 0x16: /* System Object ID - not documented */
240 			if (cdp_print_addr(ndo, tptr, len) < 0)
241 				goto trunc;
242 			break;
243 		    case 0x17: /* Physical Location - not documented */
244 			if (len < 1)
245 			    goto trunc;
246 			ND_PRINT((ndo, "0x%02x", *(tptr)));
247 			if (len > 1) {
248 				ND_PRINT((ndo, "/"));
249 				(void)fn_printn(ndo, tptr + 1, len - 1, NULL);
250 			}
251 			break;
252 		    default:
253 			print_unknown_data(ndo, tptr, "\n\t  ", len);
254 			break;
255 		    }
256 		}
257 		tptr = tptr+len;
258 	}
259 	if (ndo->ndo_vflag < 1)
260 	    ND_PRINT((ndo, ", length %u", caplen));
261 
262 	return;
263 trunc:
264 	ND_PRINT((ndo, "%s", tstr));
265 }
266 
267 /*
268  * Protocol type values.
269  *
270  * PT_NLPID means that the protocol type field contains an OSI NLPID.
271  *
272  * PT_IEEE_802_2 means that the protocol type field contains an IEEE 802.2
273  * LLC header that specifies that the payload is for that protocol.
274  */
275 #define PT_NLPID		1	/* OSI NLPID */
276 #define PT_IEEE_802_2		2	/* IEEE 802.2 LLC header */
277 
278 static int
cdp_print_addr(netdissect_options * ndo,const u_char * p,int l)279 cdp_print_addr(netdissect_options *ndo,
280 	       const u_char * p, int l)
281 {
282 	int pt, pl, al, num;
283 	const u_char *endp = p + l;
284 	static const u_char prot_ipv6[] = {
285 		0xaa, 0xaa, 0x03, 0x00, 0x00, 0x00, 0x86, 0xdd
286 	};
287 
288 	ND_TCHECK2(*p, 4);
289 	if (p + 4 > endp)
290 		goto trunc;
291 	num = EXTRACT_32BITS(p);
292 	p += 4;
293 
294 	while (p < endp && num >= 0) {
295 		ND_TCHECK2(*p, 2);
296 		if (p + 2 > endp)
297 			goto trunc;
298 		pt = p[0];		/* type of "protocol" field */
299 		pl = p[1];		/* length of "protocol" field */
300 		p += 2;
301 
302 		ND_TCHECK2(p[pl], 2);
303 		if (p + pl + 2 > endp)
304 			goto trunc;
305 		al = EXTRACT_16BITS(&p[pl]);	/* address length */
306 
307 		if (pt == PT_NLPID && pl == 1 && *p == NLPID_IP && al == 4) {
308 			/*
309 			 * IPv4: protocol type = NLPID, protocol length = 1
310 			 * (1-byte NLPID), protocol = 0xcc (NLPID for IPv4),
311 			 * address length = 4
312 			 */
313 			p += 3;
314 
315 			ND_TCHECK2(*p, 4);
316 			if (p + 4 > endp)
317 				goto trunc;
318 			ND_PRINT((ndo, "IPv4 (%u) %s", num, ipaddr_string(ndo, p)));
319 			p += 4;
320 		}
321 		else if (pt == PT_IEEE_802_2 && pl == 8 &&
322 		    memcmp(p, prot_ipv6, 8) == 0 && al == 16) {
323 			/*
324 			 * IPv6: protocol type = IEEE 802.2 header,
325 			 * protocol length = 8 (size of LLC+SNAP header),
326 			 * protocol = LLC+SNAP header with the IPv6
327 			 * Ethertype, address length = 16
328 			 */
329 			p += 10;
330 			ND_TCHECK2(*p, al);
331 			if (p + al > endp)
332 				goto trunc;
333 
334 			ND_PRINT((ndo, "IPv6 (%u) %s", num, ip6addr_string(ndo, p)));
335 			p += al;
336 		}
337 		else {
338 			/*
339 			 * Generic case: just print raw data
340 			 */
341 			ND_TCHECK2(*p, pl);
342 			if (p + pl > endp)
343 				goto trunc;
344 			ND_PRINT((ndo, "pt=0x%02x, pl=%d, pb=", *(p - 2), pl));
345 			while (pl-- > 0)
346 				ND_PRINT((ndo, " %02x", *p++));
347 			ND_TCHECK2(*p, 2);
348 			if (p + 2 > endp)
349 				goto trunc;
350 			al = (*p << 8) + *(p + 1);
351 			ND_PRINT((ndo, ", al=%d, a=", al));
352 			p += 2;
353 			ND_TCHECK2(*p, al);
354 			if (p + al > endp)
355 				goto trunc;
356 			while (al-- > 0)
357 				ND_PRINT((ndo, " %02x", *p++));
358 		}
359 		num--;
360 		if (num)
361 			ND_PRINT((ndo, " "));
362 	}
363 
364 	return 0;
365 
366 trunc:
367 	return -1;
368 }
369 
370 
371 static int
cdp_print_prefixes(netdissect_options * ndo,const u_char * p,int l)372 cdp_print_prefixes(netdissect_options *ndo,
373 		   const u_char * p, int l)
374 {
375 	if (l % 5)
376 		goto trunc;
377 
378 	ND_PRINT((ndo, " IPv4 Prefixes (%d):", l / 5));
379 
380 	while (l > 0) {
381 		ND_PRINT((ndo, " %u.%u.%u.%u/%u", p[0], p[1], p[2], p[3], p[4]));
382 		l -= 5;
383 		p += 5;
384 	}
385 
386 	return 0;
387 
388 trunc:
389 	return -1;
390 }
391 
392 /* read in a <n>-byte number, MSB first
393  * (of course this can handle max sizeof(long))
394  */
cdp_get_number(const u_char * p,int l)395 static unsigned long cdp_get_number(const u_char * p, int l)
396 {
397     unsigned long res=0;
398     while( l>0 )
399     {
400 	res = (res<<8) + *p;
401 	p++; l--;
402     }
403     return res;
404 }
405