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 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
18 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
19 * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
20 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
21 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
22 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
24 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
25 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
26 * POSSIBILITY OF SUCH DAMAGE.
27 */
28
29 /* \summary: Generic Routing Encapsulation (GRE) printer */
30
31 /*
32 * netdissect printer for GRE - Generic Routing Encapsulation
33 * RFC1701 (GRE), RFC1702 (GRE IPv4), and RFC2637 (Enhanced GRE)
34 */
35
36 #ifdef HAVE_CONFIG_H
37 #include <config.h>
38 #endif
39
40 #include "netdissect-stdinc.h"
41
42 #include "netdissect.h"
43 #include "addrtostr.h"
44 #include "extract.h"
45 #include "ethertype.h"
46
47
48 #define GRE_CP 0x8000 /* checksum present */
49 #define GRE_RP 0x4000 /* routing present */
50 #define GRE_KP 0x2000 /* key present */
51 #define GRE_SP 0x1000 /* sequence# present */
52 #define GRE_sP 0x0800 /* source routing */
53 #define GRE_AP 0x0080 /* acknowledgment# present */
54
55 static const struct tok gre_flag_values[] = {
56 { GRE_CP, "checksum present"},
57 { GRE_RP, "routing present"},
58 { GRE_KP, "key present"},
59 { GRE_SP, "sequence# present"},
60 { GRE_sP, "source routing present"},
61 { GRE_AP, "ack present"},
62 { 0, NULL }
63 };
64
65 #define GRE_RECRS_MASK 0x0700 /* recursion count */
66 #define GRE_VERS_MASK 0x0007 /* protocol version */
67
68 /* source route entry types */
69 #define GRESRE_IP 0x0800 /* IP */
70 #define GRESRE_ASN 0xfffe /* ASN */
71
72 static void gre_print_0(netdissect_options *, const u_char *, u_int);
73 static void gre_print_1(netdissect_options *, const u_char *, u_int);
74 static int gre_sre_print(netdissect_options *, uint16_t, uint8_t, uint8_t, const u_char *, u_int);
75 static int gre_sre_ip_print(netdissect_options *, uint8_t, uint8_t, const u_char *, u_int);
76 static int gre_sre_asn_print(netdissect_options *, uint8_t, uint8_t, const u_char *, u_int);
77
78 void
gre_print(netdissect_options * ndo,const u_char * bp,u_int length)79 gre_print(netdissect_options *ndo, const u_char *bp, u_int length)
80 {
81 u_int len = length, vers;
82
83 ndo->ndo_protocol = "gre";
84 ND_TCHECK_2(bp);
85 if (len < 2)
86 goto trunc;
87 vers = GET_BE_U_2(bp) & GRE_VERS_MASK;
88 ND_PRINT("GREv%u",vers);
89
90 switch(vers) {
91 case 0:
92 gre_print_0(ndo, bp, len);
93 break;
94 case 1:
95 gre_print_1(ndo, bp, len);
96 break;
97 default:
98 ND_PRINT(" ERROR: unknown-version");
99 break;
100 }
101 return;
102
103 trunc:
104 nd_print_trunc(ndo);
105 }
106
107 static void
gre_print_0(netdissect_options * ndo,const u_char * bp,u_int length)108 gre_print_0(netdissect_options *ndo, const u_char *bp, u_int length)
109 {
110 u_int len = length;
111 uint16_t flags, prot;
112
113 /* 16 bits ND_TCHECKed in gre_print() */
114 flags = GET_BE_U_2(bp);
115 if (ndo->ndo_vflag)
116 ND_PRINT(", Flags [%s]",
117 bittok2str(gre_flag_values,"none",flags));
118
119 len -= 2;
120 bp += 2;
121
122 ND_TCHECK_2(bp);
123 if (len < 2)
124 goto trunc;
125 prot = GET_BE_U_2(bp);
126 len -= 2;
127 bp += 2;
128
129 if ((flags & GRE_CP) | (flags & GRE_RP)) {
130 ND_TCHECK_2(bp);
131 if (len < 2)
132 goto trunc;
133 if (ndo->ndo_vflag)
134 ND_PRINT(", sum 0x%x", GET_BE_U_2(bp));
135 bp += 2;
136 len -= 2;
137
138 ND_TCHECK_2(bp);
139 if (len < 2)
140 goto trunc;
141 ND_PRINT(", off 0x%x", GET_BE_U_2(bp));
142 bp += 2;
143 len -= 2;
144 }
145
146 if (flags & GRE_KP) {
147 ND_TCHECK_4(bp);
148 if (len < 4)
149 goto trunc;
150 ND_PRINT(", key=0x%x", GET_BE_U_4(bp));
151 bp += 4;
152 len -= 4;
153 }
154
155 if (flags & GRE_SP) {
156 ND_TCHECK_4(bp);
157 if (len < 4)
158 goto trunc;
159 ND_PRINT(", seq %u", GET_BE_U_4(bp));
160 bp += 4;
161 len -= 4;
162 }
163
164 if (flags & GRE_RP) {
165 for (;;) {
166 uint16_t af;
167 uint8_t sreoff;
168 uint8_t srelen;
169
170 ND_TCHECK_4(bp);
171 if (len < 4)
172 goto trunc;
173 af = GET_BE_U_2(bp);
174 sreoff = GET_U_1(bp + 2);
175 srelen = GET_U_1(bp + 3);
176 bp += 4;
177 len -= 4;
178
179 if (af == 0 && srelen == 0)
180 break;
181
182 if (!gre_sre_print(ndo, af, sreoff, srelen, bp, len))
183 goto trunc;
184
185 if (len < srelen)
186 goto trunc;
187 bp += srelen;
188 len -= srelen;
189 }
190 }
191
192 if (ndo->ndo_eflag)
193 ND_PRINT(", proto %s (0x%04x)",
194 tok2str(ethertype_values,"unknown",prot), prot);
195
196 ND_PRINT(", length %u",length);
197
198 if (ndo->ndo_vflag < 1)
199 ND_PRINT(": "); /* put in a colon as protocol demarc */
200 else
201 ND_PRINT("\n\t"); /* if verbose go multiline */
202
203 switch (prot) {
204 case ETHERTYPE_IP:
205 ip_print(ndo, bp, len);
206 break;
207 case ETHERTYPE_IPV6:
208 ip6_print(ndo, bp, len);
209 break;
210 case ETHERTYPE_MPLS:
211 mpls_print(ndo, bp, len);
212 break;
213 case ETHERTYPE_IPX:
214 ipx_print(ndo, bp, len);
215 break;
216 case ETHERTYPE_ATALK:
217 atalk_print(ndo, bp, len);
218 break;
219 case ETHERTYPE_GRE_ISO:
220 isoclns_print(ndo, bp, len);
221 break;
222 case ETHERTYPE_TEB:
223 ether_print(ndo, bp, len, ND_BYTES_AVAILABLE_AFTER(bp), NULL, NULL);
224 break;
225 default:
226 ND_PRINT("gre-proto-0x%x", prot);
227 }
228 return;
229
230 trunc:
231 nd_print_trunc(ndo);
232 }
233
234 static void
gre_print_1(netdissect_options * ndo,const u_char * bp,u_int length)235 gre_print_1(netdissect_options *ndo, const u_char *bp, u_int length)
236 {
237 u_int len = length;
238 uint16_t flags, prot;
239
240 /* 16 bits ND_TCHECKed in gre_print() */
241 flags = GET_BE_U_2(bp);
242 len -= 2;
243 bp += 2;
244
245 if (ndo->ndo_vflag)
246 ND_PRINT(", Flags [%s]",
247 bittok2str(gre_flag_values,"none",flags));
248
249 ND_TCHECK_2(bp);
250 if (len < 2)
251 goto trunc;
252 prot = GET_BE_U_2(bp);
253 len -= 2;
254 bp += 2;
255
256
257 if (flags & GRE_KP) {
258 uint32_t k;
259
260 ND_TCHECK_4(bp);
261 if (len < 4)
262 goto trunc;
263 k = GET_BE_U_4(bp);
264 ND_PRINT(", call %u", k & 0xffff);
265 len -= 4;
266 bp += 4;
267 }
268
269 if (flags & GRE_SP) {
270 ND_TCHECK_4(bp);
271 if (len < 4)
272 goto trunc;
273 ND_PRINT(", seq %u", GET_BE_U_4(bp));
274 bp += 4;
275 len -= 4;
276 }
277
278 if (flags & GRE_AP) {
279 ND_TCHECK_4(bp);
280 if (len < 4)
281 goto trunc;
282 ND_PRINT(", ack %u", GET_BE_U_4(bp));
283 bp += 4;
284 len -= 4;
285 }
286
287 if ((flags & GRE_SP) == 0)
288 ND_PRINT(", no-payload");
289
290 if (ndo->ndo_eflag)
291 ND_PRINT(", proto %s (0x%04x)",
292 tok2str(ethertype_values,"unknown",prot), prot);
293
294 ND_PRINT(", length %u",length);
295
296 if ((flags & GRE_SP) == 0)
297 return;
298
299 if (ndo->ndo_vflag < 1)
300 ND_PRINT(": "); /* put in a colon as protocol demarc */
301 else
302 ND_PRINT("\n\t"); /* if verbose go multiline */
303
304 switch (prot) {
305 case ETHERTYPE_PPP:
306 ppp_print(ndo, bp, len);
307 break;
308 default:
309 ND_PRINT("gre-proto-0x%x", prot);
310 break;
311 }
312 return;
313
314 trunc:
315 nd_print_trunc(ndo);
316 }
317
318 static int
gre_sre_print(netdissect_options * ndo,uint16_t af,uint8_t sreoff,uint8_t srelen,const u_char * bp,u_int len)319 gre_sre_print(netdissect_options *ndo, uint16_t af, uint8_t sreoff,
320 uint8_t srelen, const u_char *bp, u_int len)
321 {
322 int ret;
323
324 switch (af) {
325 case GRESRE_IP:
326 ND_PRINT(", (rtaf=ip");
327 ret = gre_sre_ip_print(ndo, sreoff, srelen, bp, len);
328 ND_PRINT(")");
329 break;
330 case GRESRE_ASN:
331 ND_PRINT(", (rtaf=asn");
332 ret = gre_sre_asn_print(ndo, sreoff, srelen, bp, len);
333 ND_PRINT(")");
334 break;
335 default:
336 ND_PRINT(", (rtaf=0x%x)", af);
337 ret = 1;
338 }
339 return (ret);
340 }
341
342 static int
gre_sre_ip_print(netdissect_options * ndo,uint8_t sreoff,uint8_t srelen,const u_char * bp,u_int len)343 gre_sre_ip_print(netdissect_options *ndo, uint8_t sreoff, uint8_t srelen,
344 const u_char *bp, u_int len)
345 {
346 const u_char *up = bp;
347 char buf[INET_ADDRSTRLEN];
348
349 if (sreoff & 3) {
350 ND_PRINT(", badoffset=%u", sreoff);
351 return (1);
352 }
353 if (srelen & 3) {
354 ND_PRINT(", badlength=%u", srelen);
355 return (1);
356 }
357 if (sreoff >= srelen) {
358 ND_PRINT(", badoff/len=%u/%u", sreoff, srelen);
359 return (1);
360 }
361
362 while (srelen != 0) {
363 ND_TCHECK_4(bp);
364 if (len < 4)
365 return (0);
366
367 addrtostr(bp, buf, sizeof(buf));
368 ND_PRINT(" %s%s",
369 ((bp - up) == sreoff) ? "*" : "", buf);
370
371 bp += 4;
372 len -= 4;
373 srelen -= 4;
374 }
375 return (1);
376 trunc:
377 return 0;
378 }
379
380 static int
gre_sre_asn_print(netdissect_options * ndo,uint8_t sreoff,uint8_t srelen,const u_char * bp,u_int len)381 gre_sre_asn_print(netdissect_options *ndo, uint8_t sreoff, uint8_t srelen,
382 const u_char *bp, u_int len)
383 {
384 const u_char *up = bp;
385
386 if (sreoff & 1) {
387 ND_PRINT(", badoffset=%u", sreoff);
388 return (1);
389 }
390 if (srelen & 1) {
391 ND_PRINT(", badlength=%u", srelen);
392 return (1);
393 }
394 if (sreoff >= srelen) {
395 ND_PRINT(", badoff/len=%u/%u", sreoff, srelen);
396 return (1);
397 }
398
399 while (srelen != 0) {
400 ND_TCHECK_2(bp);
401 if (len < 2)
402 return (0);
403
404 ND_PRINT(" %s%x",
405 ((bp - up) == sreoff) ? "*" : "", GET_BE_U_2(bp));
406
407 bp += 2;
408 len -= 2;
409 srelen -= 2;
410 }
411 return (1);
412 trunc:
413 return 0;
414 }
415