1 /* $OpenBSD: print-gre.c,v 1.6 2002/10/30 03:04:04 fgsch Exp $ */
2
3 /*
4 * Copyright (c) 2002 Jason L. Wright (jason@thought.net)
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. All advertising materials mentioning features or use of this software
16 * must display the following acknowledgement:
17 * This product includes software developed by Jason L. Wright
18 * 4. The name of the author may not be used to endorse or promote products
19 * derived from this software without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
22 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
23 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
24 * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
25 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
26 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
27 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
29 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
30 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
31 * POSSIBILITY OF SUCH DAMAGE.
32 */
33
34 /* \summary: Generic Routing Encapsulation (GRE) printer */
35
36 /*
37 * netdissect printer for GRE - Generic Routing Encapsulation
38 * RFC1701 (GRE), RFC1702 (GRE IPv4), and RFC2637 (Enhanced GRE)
39 */
40
41 #ifdef HAVE_CONFIG_H
42 #include "config.h"
43 #endif
44
45 #include <netdissect-stdinc.h>
46
47 #include <string.h>
48
49 #include "netdissect.h"
50 #include "addrtostr.h"
51 #include "extract.h"
52 #include "ethertype.h"
53
54 static const char tstr[] = "[|gre]";
55
56 #define GRE_CP 0x8000 /* checksum present */
57 #define GRE_RP 0x4000 /* routing present */
58 #define GRE_KP 0x2000 /* key present */
59 #define GRE_SP 0x1000 /* sequence# present */
60 #define GRE_sP 0x0800 /* source routing */
61 #define GRE_RECRS 0x0700 /* recursion count */
62 #define GRE_AP 0x0080 /* acknowledgment# present */
63
64 static const struct tok gre_flag_values[] = {
65 { GRE_CP, "checksum present"},
66 { GRE_RP, "routing present"},
67 { GRE_KP, "key present"},
68 { GRE_SP, "sequence# present"},
69 { GRE_sP, "source routing present"},
70 { GRE_RECRS, "recursion count"},
71 { GRE_AP, "ack present"},
72 { 0, NULL }
73 };
74
75 #define GRE_VERS_MASK 0x0007 /* protocol version */
76
77 /* source route entry types */
78 #define GRESRE_IP 0x0800 /* IP */
79 #define GRESRE_ASN 0xfffe /* ASN */
80
81 static void gre_print_0(netdissect_options *, const u_char *, u_int);
82 static void gre_print_1(netdissect_options *, const u_char *, u_int);
83 static int gre_sre_print(netdissect_options *, uint16_t, uint8_t, uint8_t, const u_char *, u_int);
84 static int gre_sre_ip_print(netdissect_options *, uint8_t, uint8_t, const u_char *, u_int);
85 static int gre_sre_asn_print(netdissect_options *, uint8_t, uint8_t, const u_char *, u_int);
86
87 void
gre_print(netdissect_options * ndo,const u_char * bp,u_int length)88 gre_print(netdissect_options *ndo, const u_char *bp, u_int length)
89 {
90 u_int len = length, vers;
91
92 ND_TCHECK2(*bp, 2);
93 if (len < 2)
94 goto trunc;
95 vers = EXTRACT_16BITS(bp) & GRE_VERS_MASK;
96 ND_PRINT((ndo, "GREv%u",vers));
97
98 switch(vers) {
99 case 0:
100 gre_print_0(ndo, bp, len);
101 break;
102 case 1:
103 gre_print_1(ndo, bp, len);
104 break;
105 default:
106 ND_PRINT((ndo, " ERROR: unknown-version"));
107 break;
108 }
109 return;
110
111 trunc:
112 ND_PRINT((ndo, "%s", tstr));
113 return;
114 }
115
116 static void
gre_print_0(netdissect_options * ndo,const u_char * bp,u_int length)117 gre_print_0(netdissect_options *ndo, const u_char *bp, u_int length)
118 {
119 u_int len = length;
120 uint16_t flags, prot;
121
122 flags = EXTRACT_16BITS(bp);
123 if (ndo->ndo_vflag)
124 ND_PRINT((ndo, ", Flags [%s]",
125 bittok2str(gre_flag_values,"none",flags)));
126
127 len -= 2;
128 bp += 2;
129
130 ND_TCHECK2(*bp, 2);
131 if (len < 2)
132 goto trunc;
133 prot = EXTRACT_16BITS(bp);
134 len -= 2;
135 bp += 2;
136
137 if ((flags & GRE_CP) | (flags & GRE_RP)) {
138 ND_TCHECK2(*bp, 2);
139 if (len < 2)
140 goto trunc;
141 if (ndo->ndo_vflag)
142 ND_PRINT((ndo, ", sum 0x%x", EXTRACT_16BITS(bp)));
143 bp += 2;
144 len -= 2;
145
146 ND_TCHECK2(*bp, 2);
147 if (len < 2)
148 goto trunc;
149 ND_PRINT((ndo, ", off 0x%x", EXTRACT_16BITS(bp)));
150 bp += 2;
151 len -= 2;
152 }
153
154 if (flags & GRE_KP) {
155 ND_TCHECK2(*bp, 4);
156 if (len < 4)
157 goto trunc;
158 ND_PRINT((ndo, ", key=0x%x", EXTRACT_32BITS(bp)));
159 bp += 4;
160 len -= 4;
161 }
162
163 if (flags & GRE_SP) {
164 ND_TCHECK2(*bp, 4);
165 if (len < 4)
166 goto trunc;
167 ND_PRINT((ndo, ", seq %u", EXTRACT_32BITS(bp)));
168 bp += 4;
169 len -= 4;
170 }
171
172 if (flags & GRE_RP) {
173 for (;;) {
174 uint16_t af;
175 uint8_t sreoff;
176 uint8_t srelen;
177
178 ND_TCHECK2(*bp, 4);
179 if (len < 4)
180 goto trunc;
181 af = EXTRACT_16BITS(bp);
182 sreoff = *(bp + 2);
183 srelen = *(bp + 3);
184 bp += 4;
185 len -= 4;
186
187 if (af == 0 && srelen == 0)
188 break;
189
190 if (!gre_sre_print(ndo, af, sreoff, srelen, bp, len))
191 goto trunc;
192
193 if (len < srelen)
194 goto trunc;
195 bp += srelen;
196 len -= srelen;
197 }
198 }
199
200 if (ndo->ndo_eflag)
201 ND_PRINT((ndo, ", proto %s (0x%04x)",
202 tok2str(ethertype_values,"unknown",prot),
203 prot));
204
205 ND_PRINT((ndo, ", length %u",length));
206
207 if (ndo->ndo_vflag < 1)
208 ND_PRINT((ndo, ": ")); /* put in a colon as protocol demarc */
209 else
210 ND_PRINT((ndo, "\n\t")); /* if verbose go multiline */
211
212 switch (prot) {
213 case ETHERTYPE_IP:
214 ip_print(ndo, bp, len);
215 break;
216 case ETHERTYPE_IPV6:
217 ip6_print(ndo, bp, len);
218 break;
219 case ETHERTYPE_MPLS:
220 mpls_print(ndo, bp, len);
221 break;
222 case ETHERTYPE_IPX:
223 ipx_print(ndo, bp, len);
224 break;
225 case ETHERTYPE_ATALK:
226 atalk_print(ndo, bp, len);
227 break;
228 case ETHERTYPE_GRE_ISO:
229 isoclns_print(ndo, bp, len);
230 break;
231 case ETHERTYPE_TEB:
232 ether_print(ndo, bp, len, ndo->ndo_snapend - bp, NULL, NULL);
233 break;
234 default:
235 ND_PRINT((ndo, "gre-proto-0x%x", prot));
236 }
237 return;
238
239 trunc:
240 ND_PRINT((ndo, "%s", tstr));
241 }
242
243 static void
gre_print_1(netdissect_options * ndo,const u_char * bp,u_int length)244 gre_print_1(netdissect_options *ndo, const u_char *bp, u_int length)
245 {
246 u_int len = length;
247 uint16_t flags, prot;
248
249 flags = EXTRACT_16BITS(bp);
250 len -= 2;
251 bp += 2;
252
253 if (ndo->ndo_vflag)
254 ND_PRINT((ndo, ", Flags [%s]",
255 bittok2str(gre_flag_values,"none",flags)));
256
257 ND_TCHECK2(*bp, 2);
258 if (len < 2)
259 goto trunc;
260 prot = EXTRACT_16BITS(bp);
261 len -= 2;
262 bp += 2;
263
264
265 if (flags & GRE_KP) {
266 uint32_t k;
267
268 ND_TCHECK2(*bp, 4);
269 if (len < 4)
270 goto trunc;
271 k = EXTRACT_32BITS(bp);
272 ND_PRINT((ndo, ", call %d", k & 0xffff));
273 len -= 4;
274 bp += 4;
275 }
276
277 if (flags & GRE_SP) {
278 ND_TCHECK2(*bp, 4);
279 if (len < 4)
280 goto trunc;
281 ND_PRINT((ndo, ", seq %u", EXTRACT_32BITS(bp)));
282 bp += 4;
283 len -= 4;
284 }
285
286 if (flags & GRE_AP) {
287 ND_TCHECK2(*bp, 4);
288 if (len < 4)
289 goto trunc;
290 ND_PRINT((ndo, ", ack %u", EXTRACT_32BITS(bp)));
291 bp += 4;
292 len -= 4;
293 }
294
295 if ((flags & GRE_SP) == 0)
296 ND_PRINT((ndo, ", no-payload"));
297
298 if (ndo->ndo_eflag)
299 ND_PRINT((ndo, ", proto %s (0x%04x)",
300 tok2str(ethertype_values,"unknown",prot),
301 prot));
302
303 ND_PRINT((ndo, ", length %u",length));
304
305 if ((flags & GRE_SP) == 0)
306 return;
307
308 if (ndo->ndo_vflag < 1)
309 ND_PRINT((ndo, ": ")); /* put in a colon as protocol demarc */
310 else
311 ND_PRINT((ndo, "\n\t")); /* if verbose go multiline */
312
313 switch (prot) {
314 case ETHERTYPE_PPP:
315 ppp_print(ndo, bp, len);
316 break;
317 default:
318 ND_PRINT((ndo, "gre-proto-0x%x", prot));
319 break;
320 }
321 return;
322
323 trunc:
324 ND_PRINT((ndo, "%s", tstr));
325 }
326
327 static int
gre_sre_print(netdissect_options * ndo,uint16_t af,uint8_t sreoff,uint8_t srelen,const u_char * bp,u_int len)328 gre_sre_print(netdissect_options *ndo, uint16_t af, uint8_t sreoff,
329 uint8_t srelen, const u_char *bp, u_int len)
330 {
331 int ret;
332
333 switch (af) {
334 case GRESRE_IP:
335 ND_PRINT((ndo, ", (rtaf=ip"));
336 ret = gre_sre_ip_print(ndo, sreoff, srelen, bp, len);
337 ND_PRINT((ndo, ")"));
338 break;
339 case GRESRE_ASN:
340 ND_PRINT((ndo, ", (rtaf=asn"));
341 ret = gre_sre_asn_print(ndo, sreoff, srelen, bp, len);
342 ND_PRINT((ndo, ")"));
343 break;
344 default:
345 ND_PRINT((ndo, ", (rtaf=0x%x)", af));
346 ret = 1;
347 }
348 return (ret);
349 }
350
351 static int
gre_sre_ip_print(netdissect_options * ndo,uint8_t sreoff,uint8_t srelen,const u_char * bp,u_int len)352 gre_sre_ip_print(netdissect_options *ndo, uint8_t sreoff, uint8_t srelen,
353 const u_char *bp, u_int len)
354 {
355 const u_char *up = bp;
356 char buf[INET_ADDRSTRLEN];
357
358 if (sreoff & 3) {
359 ND_PRINT((ndo, ", badoffset=%u", sreoff));
360 return (1);
361 }
362 if (srelen & 3) {
363 ND_PRINT((ndo, ", badlength=%u", srelen));
364 return (1);
365 }
366 if (sreoff >= srelen) {
367 ND_PRINT((ndo, ", badoff/len=%u/%u", sreoff, srelen));
368 return (1);
369 }
370
371 while (srelen != 0) {
372 if (!ND_TTEST2(*bp, 4))
373 return (0);
374 if (len < 4)
375 return (0);
376
377 addrtostr(bp, buf, sizeof(buf));
378 ND_PRINT((ndo, " %s%s",
379 ((bp - up) == sreoff) ? "*" : "", buf));
380
381 bp += 4;
382 len -= 4;
383 srelen -= 4;
384 }
385 return (1);
386 }
387
388 static int
gre_sre_asn_print(netdissect_options * ndo,uint8_t sreoff,uint8_t srelen,const u_char * bp,u_int len)389 gre_sre_asn_print(netdissect_options *ndo, uint8_t sreoff, uint8_t srelen,
390 const u_char *bp, u_int len)
391 {
392 const u_char *up = bp;
393
394 if (sreoff & 1) {
395 ND_PRINT((ndo, ", badoffset=%u", sreoff));
396 return (1);
397 }
398 if (srelen & 1) {
399 ND_PRINT((ndo, ", badlength=%u", srelen));
400 return (1);
401 }
402 if (sreoff >= srelen) {
403 ND_PRINT((ndo, ", badoff/len=%u/%u", sreoff, srelen));
404 return (1);
405 }
406
407 while (srelen != 0) {
408 if (!ND_TTEST2(*bp, 2))
409 return (0);
410 if (len < 2)
411 return (0);
412
413 ND_PRINT((ndo, " %s%x",
414 ((bp - up) == sreoff) ? "*" : "",
415 EXTRACT_16BITS(bp)));
416
417 bp += 2;
418 len -= 2;
419 srelen -= 2;
420 }
421 return (1);
422 }
423