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1 /*
2  * Copyright (c) 1988, 1989, 1990, 1991, 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 
22 /* \summary: Address Resolution Protocol (ARP) printer */
23 
24 #ifdef HAVE_CONFIG_H
25 #include "config.h"
26 #endif
27 
28 #include <netdissect-stdinc.h>
29 
30 #include <string.h>
31 
32 #include "netdissect.h"
33 #include "addrtoname.h"
34 #include "ether.h"
35 #include "ethertype.h"
36 #include "extract.h"
37 
38 static const char tstr[] = "[|ARP]";
39 
40 /*
41  * Address Resolution Protocol.
42  *
43  * See RFC 826 for protocol description.  ARP packets are variable
44  * in size; the arphdr structure defines the fixed-length portion.
45  * Protocol type values are the same as those for 10 Mb/s Ethernet.
46  * It is followed by the variable-sized fields ar_sha, arp_spa,
47  * arp_tha and arp_tpa in that order, according to the lengths
48  * specified.  Field names used correspond to RFC 826.
49  */
50 struct  arp_pkthdr {
51         u_short ar_hrd;         /* format of hardware address */
52 #define ARPHRD_ETHER    1       /* ethernet hardware format */
53 #define ARPHRD_IEEE802  6       /* token-ring hardware format */
54 #define ARPHRD_ARCNET   7       /* arcnet hardware format */
55 #define ARPHRD_FRELAY   15      /* frame relay hardware format */
56 #define ARPHRD_ATM2225  19      /* ATM (RFC 2225) */
57 #define ARPHRD_STRIP    23      /* Ricochet Starmode Radio hardware format */
58 #define ARPHRD_IEEE1394 24      /* IEEE 1394 (FireWire) hardware format */
59         u_short ar_pro;         /* format of protocol address */
60         u_char  ar_hln;         /* length of hardware address */
61         u_char  ar_pln;         /* length of protocol address */
62         u_short ar_op;          /* one of: */
63 #define ARPOP_REQUEST   1       /* request to resolve address */
64 #define ARPOP_REPLY     2       /* response to previous request */
65 #define ARPOP_REVREQUEST 3      /* request protocol address given hardware */
66 #define ARPOP_REVREPLY  4       /* response giving protocol address */
67 #define ARPOP_INVREQUEST 8      /* request to identify peer */
68 #define ARPOP_INVREPLY  9       /* response identifying peer */
69 #define ARPOP_NAK       10      /* NAK - only valif for ATM ARP */
70 
71 /*
72  * The remaining fields are variable in size,
73  * according to the sizes above.
74  */
75 #ifdef COMMENT_ONLY
76 	u_char	ar_sha[];	/* sender hardware address */
77 	u_char	ar_spa[];	/* sender protocol address */
78 	u_char	ar_tha[];	/* target hardware address */
79 	u_char	ar_tpa[];	/* target protocol address */
80 #endif
81 #define ar_sha(ap)	(((const u_char *)((ap)+1))+  0)
82 #define ar_spa(ap)	(((const u_char *)((ap)+1))+  (ap)->ar_hln)
83 #define ar_tha(ap)	(((const u_char *)((ap)+1))+  (ap)->ar_hln+(ap)->ar_pln)
84 #define ar_tpa(ap)	(((const u_char *)((ap)+1))+2*(ap)->ar_hln+(ap)->ar_pln)
85 };
86 
87 #define ARP_HDRLEN	8
88 
89 #define HRD(ap) EXTRACT_16BITS(&(ap)->ar_hrd)
90 #define HRD_LEN(ap) ((ap)->ar_hln)
91 #define PROTO_LEN(ap) ((ap)->ar_pln)
92 #define OP(ap)  EXTRACT_16BITS(&(ap)->ar_op)
93 #define PRO(ap) EXTRACT_16BITS(&(ap)->ar_pro)
94 #define SHA(ap) (ar_sha(ap))
95 #define SPA(ap) (ar_spa(ap))
96 #define THA(ap) (ar_tha(ap))
97 #define TPA(ap) (ar_tpa(ap))
98 
99 
100 static const struct tok arpop_values[] = {
101     { ARPOP_REQUEST, "Request" },
102     { ARPOP_REPLY, "Reply" },
103     { ARPOP_REVREQUEST, "Reverse Request" },
104     { ARPOP_REVREPLY, "Reverse Reply" },
105     { ARPOP_INVREQUEST, "Inverse Request" },
106     { ARPOP_INVREPLY, "Inverse Reply" },
107     { ARPOP_NAK, "NACK Reply" },
108     { 0, NULL }
109 };
110 
111 static const struct tok arphrd_values[] = {
112     { ARPHRD_ETHER, "Ethernet" },
113     { ARPHRD_IEEE802, "TokenRing" },
114     { ARPHRD_ARCNET, "ArcNet" },
115     { ARPHRD_FRELAY, "FrameRelay" },
116     { ARPHRD_STRIP, "Strip" },
117     { ARPHRD_IEEE1394, "IEEE 1394" },
118     { ARPHRD_ATM2225, "ATM" },
119     { 0, NULL }
120 };
121 
122 /*
123  * ATM Address Resolution Protocol.
124  *
125  * See RFC 2225 for protocol description.  ATMARP packets are similar
126  * to ARP packets, except that there are no length fields for the
127  * protocol address - instead, there are type/length fields for
128  * the ATM number and subaddress - and the hardware addresses consist
129  * of an ATM number and an ATM subaddress.
130  */
131 struct  atmarp_pkthdr {
132         u_short aar_hrd;        /* format of hardware address */
133         u_short aar_pro;        /* format of protocol address */
134         u_char  aar_shtl;       /* length of source ATM number */
135         u_char  aar_sstl;       /* length of source ATM subaddress */
136 #define ATMARP_IS_E164  0x40    /* bit in type/length for E.164 format */
137 #define ATMARP_LEN_MASK 0x3F    /* length of {sub}address in type/length */
138         u_short aar_op;         /* same as regular ARP */
139         u_char  aar_spln;       /* length of source protocol address */
140         u_char  aar_thtl;       /* length of target ATM number */
141         u_char  aar_tstl;       /* length of target ATM subaddress */
142         u_char  aar_tpln;       /* length of target protocol address */
143 /*
144  * The remaining fields are variable in size,
145  * according to the sizes above.
146  */
147 #ifdef COMMENT_ONLY
148 	u_char	aar_sha[];	/* source ATM number */
149 	u_char	aar_ssa[];	/* source ATM subaddress */
150 	u_char	aar_spa[];	/* sender protocol address */
151 	u_char	aar_tha[];	/* target ATM number */
152 	u_char	aar_tsa[];	/* target ATM subaddress */
153 	u_char	aar_tpa[];	/* target protocol address */
154 #endif
155 
156 #define ATMHRD(ap)  EXTRACT_16BITS(&(ap)->aar_hrd)
157 #define ATMSHRD_LEN(ap) ((ap)->aar_shtl & ATMARP_LEN_MASK)
158 #define ATMSSLN(ap) ((ap)->aar_sstl & ATMARP_LEN_MASK)
159 #define ATMSPROTO_LEN(ap) ((ap)->aar_spln)
160 #define ATMOP(ap)   EXTRACT_16BITS(&(ap)->aar_op)
161 #define ATMPRO(ap)  EXTRACT_16BITS(&(ap)->aar_pro)
162 #define ATMTHRD_LEN(ap) ((ap)->aar_thtl & ATMARP_LEN_MASK)
163 #define ATMTSLN(ap) ((ap)->aar_tstl & ATMARP_LEN_MASK)
164 #define ATMTPROTO_LEN(ap) ((ap)->aar_tpln)
165 #define aar_sha(ap)	((const u_char *)((ap)+1))
166 #define aar_ssa(ap)	(aar_sha(ap) + ATMSHRD_LEN(ap))
167 #define aar_spa(ap)	(aar_ssa(ap) + ATMSSLN(ap))
168 #define aar_tha(ap)	(aar_spa(ap) + ATMSPROTO_LEN(ap))
169 #define aar_tsa(ap)	(aar_tha(ap) + ATMTHRD_LEN(ap))
170 #define aar_tpa(ap)	(aar_tsa(ap) + ATMTSLN(ap))
171 };
172 
173 #define ATMSHA(ap) (aar_sha(ap))
174 #define ATMSSA(ap) (aar_ssa(ap))
175 #define ATMSPA(ap) (aar_spa(ap))
176 #define ATMTHA(ap) (aar_tha(ap))
177 #define ATMTSA(ap) (aar_tsa(ap))
178 #define ATMTPA(ap) (aar_tpa(ap))
179 
180 static int
isnonzero(const u_char * a,size_t len)181 isnonzero(const u_char *a, size_t len)
182 {
183 	while (len > 0) {
184 		if (*a != 0)
185 			return (1);
186 		a++;
187 		len--;
188 	}
189 	return (0);
190 }
191 
192 static void
tpaddr_print_ip(netdissect_options * ndo,const struct arp_pkthdr * ap,u_short pro)193 tpaddr_print_ip(netdissect_options *ndo,
194 	        const struct arp_pkthdr *ap, u_short pro)
195 {
196 	if (pro != ETHERTYPE_IP && pro != ETHERTYPE_TRAIL)
197 		ND_PRINT((ndo, "<wrong proto type>"));
198 	else if (PROTO_LEN(ap) != 4)
199 		ND_PRINT((ndo, "<wrong len>"));
200 	else
201 		ND_PRINT((ndo, "%s", ipaddr_string(ndo, TPA(ap))));
202 }
203 
204 static void
spaddr_print_ip(netdissect_options * ndo,const struct arp_pkthdr * ap,u_short pro)205 spaddr_print_ip(netdissect_options *ndo,
206 	        const struct arp_pkthdr *ap, u_short pro)
207 {
208 	if (pro != ETHERTYPE_IP && pro != ETHERTYPE_TRAIL)
209 		ND_PRINT((ndo, "<wrong proto type>"));
210 	else if (PROTO_LEN(ap) != 4)
211 		ND_PRINT((ndo, "<wrong len>"));
212 	else
213 		ND_PRINT((ndo, "%s", ipaddr_string(ndo, SPA(ap))));
214 }
215 
216 static void
atmarp_addr_print(netdissect_options * ndo,const u_char * ha,u_int ha_len,const u_char * srca,u_int srca_len)217 atmarp_addr_print(netdissect_options *ndo,
218 		  const u_char *ha, u_int ha_len, const u_char *srca,
219     u_int srca_len)
220 {
221 	if (ha_len == 0)
222 		ND_PRINT((ndo, "<No address>"));
223 	else {
224 		ND_PRINT((ndo, "%s", linkaddr_string(ndo, ha, LINKADDR_ATM, ha_len)));
225 		if (srca_len != 0)
226 			ND_PRINT((ndo, ",%s",
227 				  linkaddr_string(ndo, srca, LINKADDR_ATM, srca_len)));
228 	}
229 }
230 
231 static void
atmarp_tpaddr_print(netdissect_options * ndo,const struct atmarp_pkthdr * ap,u_short pro)232 atmarp_tpaddr_print(netdissect_options *ndo,
233 		    const struct atmarp_pkthdr *ap, u_short pro)
234 {
235 	if (pro != ETHERTYPE_IP && pro != ETHERTYPE_TRAIL)
236 		ND_PRINT((ndo, "<wrong proto type>"));
237 	else if (ATMTPROTO_LEN(ap) != 4)
238 		ND_PRINT((ndo, "<wrong tplen>"));
239 	else
240 		ND_PRINT((ndo, "%s", ipaddr_string(ndo, ATMTPA(ap))));
241 }
242 
243 static void
atmarp_spaddr_print(netdissect_options * ndo,const struct atmarp_pkthdr * ap,u_short pro)244 atmarp_spaddr_print(netdissect_options *ndo,
245 		    const struct atmarp_pkthdr *ap, u_short pro)
246 {
247 	if (pro != ETHERTYPE_IP && pro != ETHERTYPE_TRAIL)
248 		ND_PRINT((ndo, "<wrong proto type>"));
249 	else if (ATMSPROTO_LEN(ap) != 4)
250 		ND_PRINT((ndo, "<wrong splen>"));
251 	else
252 		ND_PRINT((ndo, "%s", ipaddr_string(ndo, ATMSPA(ap))));
253 }
254 
255 static void
atmarp_print(netdissect_options * ndo,const u_char * bp,u_int length,u_int caplen)256 atmarp_print(netdissect_options *ndo,
257 	     const u_char *bp, u_int length, u_int caplen)
258 {
259 	const struct atmarp_pkthdr *ap;
260 	u_short pro, hrd, op;
261 
262 	ap = (const struct atmarp_pkthdr *)bp;
263 	ND_TCHECK(*ap);
264 
265 	hrd = ATMHRD(ap);
266 	pro = ATMPRO(ap);
267 	op = ATMOP(ap);
268 
269 	if (!ND_TTEST2(*aar_tpa(ap), ATMTPROTO_LEN(ap))) {
270 		ND_PRINT((ndo, "%s", tstr));
271 		ND_DEFAULTPRINT((const u_char *)ap, length);
272 		return;
273 	}
274 
275         if (!ndo->ndo_eflag) {
276             ND_PRINT((ndo, "ARP, "));
277         }
278 
279 	if ((pro != ETHERTYPE_IP && pro != ETHERTYPE_TRAIL) ||
280 	    ATMSPROTO_LEN(ap) != 4 ||
281             ATMTPROTO_LEN(ap) != 4 ||
282             ndo->ndo_vflag) {
283                 ND_PRINT((ndo, "%s, %s (len %u/%u)",
284                           tok2str(arphrd_values, "Unknown Hardware (%u)", hrd),
285                           tok2str(ethertype_values, "Unknown Protocol (0x%04x)", pro),
286                           ATMSPROTO_LEN(ap),
287                           ATMTPROTO_LEN(ap)));
288 
289                 /* don't know know about the address formats */
290                 if (!ndo->ndo_vflag) {
291                     goto out;
292                 }
293 	}
294 
295         /* print operation */
296         ND_PRINT((ndo, "%s%s ",
297                ndo->ndo_vflag ? ", " : "",
298                tok2str(arpop_values, "Unknown (%u)", op)));
299 
300 	switch (op) {
301 
302 	case ARPOP_REQUEST:
303 		ND_PRINT((ndo, "who-has "));
304 		atmarp_tpaddr_print(ndo, ap, pro);
305 		if (ATMTHRD_LEN(ap) != 0) {
306 			ND_PRINT((ndo, " ("));
307 			atmarp_addr_print(ndo, ATMTHA(ap), ATMTHRD_LEN(ap),
308 			    ATMTSA(ap), ATMTSLN(ap));
309 			ND_PRINT((ndo, ")"));
310 		}
311 		ND_PRINT((ndo, " tell "));
312 		atmarp_spaddr_print(ndo, ap, pro);
313 		break;
314 
315 	case ARPOP_REPLY:
316 		atmarp_spaddr_print(ndo, ap, pro);
317 		ND_PRINT((ndo, " is-at "));
318 		atmarp_addr_print(ndo, ATMSHA(ap), ATMSHRD_LEN(ap), ATMSSA(ap),
319                                   ATMSSLN(ap));
320 		break;
321 
322 	case ARPOP_INVREQUEST:
323 		ND_PRINT((ndo, "who-is "));
324 		atmarp_addr_print(ndo, ATMTHA(ap), ATMTHRD_LEN(ap), ATMTSA(ap),
325 		    ATMTSLN(ap));
326 		ND_PRINT((ndo, " tell "));
327 		atmarp_addr_print(ndo, ATMSHA(ap), ATMSHRD_LEN(ap), ATMSSA(ap),
328 		    ATMSSLN(ap));
329 		break;
330 
331 	case ARPOP_INVREPLY:
332 		atmarp_addr_print(ndo, ATMSHA(ap), ATMSHRD_LEN(ap), ATMSSA(ap),
333 		    ATMSSLN(ap));
334 		ND_PRINT((ndo, "at "));
335 		atmarp_spaddr_print(ndo, ap, pro);
336 		break;
337 
338 	case ARPOP_NAK:
339 		ND_PRINT((ndo, "for "));
340 		atmarp_spaddr_print(ndo, ap, pro);
341 		break;
342 
343 	default:
344 		ND_DEFAULTPRINT((const u_char *)ap, caplen);
345 		return;
346 	}
347 
348  out:
349         ND_PRINT((ndo, ", length %u", length));
350         return;
351 
352 trunc:
353 	ND_PRINT((ndo, "%s", tstr));
354 }
355 
356 void
arp_print(netdissect_options * ndo,const u_char * bp,u_int length,u_int caplen)357 arp_print(netdissect_options *ndo,
358 	  const u_char *bp, u_int length, u_int caplen)
359 {
360 	const struct arp_pkthdr *ap;
361 	u_short pro, hrd, op, linkaddr;
362 
363 	ap = (const struct arp_pkthdr *)bp;
364 	ND_TCHECK(*ap);
365 
366 	hrd = HRD(ap);
367 	pro = PRO(ap);
368 	op = OP(ap);
369 
370 
371         /* if its ATM then call the ATM ARP printer
372            for Frame-relay ARP most of the fields
373            are similar to Ethernet so overload the Ethernet Printer
374            and set the linkaddr type for linkaddr_string(ndo, ) accordingly */
375 
376         switch(hrd) {
377         case ARPHRD_ATM2225:
378             atmarp_print(ndo, bp, length, caplen);
379             return;
380         case ARPHRD_FRELAY:
381             linkaddr = LINKADDR_FRELAY;
382             break;
383         default:
384             linkaddr = LINKADDR_ETHER;
385             break;
386 	}
387 
388 	if (!ND_TTEST2(*TPA(ap), PROTO_LEN(ap))) {
389 		ND_PRINT((ndo, "%s", tstr));
390 		ND_DEFAULTPRINT((const u_char *)ap, length);
391 		return;
392 	}
393 
394         if (!ndo->ndo_eflag) {
395             ND_PRINT((ndo, "ARP, "));
396         }
397 
398         /* print hardware type/len and proto type/len */
399         if ((pro != ETHERTYPE_IP && pro != ETHERTYPE_TRAIL) ||
400 	    PROTO_LEN(ap) != 4 ||
401             HRD_LEN(ap) == 0 ||
402             ndo->ndo_vflag) {
403             ND_PRINT((ndo, "%s (len %u), %s (len %u)",
404                       tok2str(arphrd_values, "Unknown Hardware (%u)", hrd),
405                       HRD_LEN(ap),
406                       tok2str(ethertype_values, "Unknown Protocol (0x%04x)", pro),
407                       PROTO_LEN(ap)));
408 
409             /* don't know know about the address formats */
410             if (!ndo->ndo_vflag) {
411                 goto out;
412             }
413 	}
414 
415         /* print operation */
416         ND_PRINT((ndo, "%s%s ",
417                ndo->ndo_vflag ? ", " : "",
418                tok2str(arpop_values, "Unknown (%u)", op)));
419 
420 	switch (op) {
421 
422 	case ARPOP_REQUEST:
423 		ND_PRINT((ndo, "who-has "));
424 		tpaddr_print_ip(ndo, ap, pro);
425 		if (isnonzero((const u_char *)THA(ap), HRD_LEN(ap)))
426 			ND_PRINT((ndo, " (%s)",
427 				  linkaddr_string(ndo, THA(ap), linkaddr, HRD_LEN(ap))));
428 		ND_PRINT((ndo, " tell "));
429 		spaddr_print_ip(ndo, ap, pro);
430 		break;
431 
432 	case ARPOP_REPLY:
433 		spaddr_print_ip(ndo, ap, pro);
434 		ND_PRINT((ndo, " is-at %s",
435                           linkaddr_string(ndo, SHA(ap), linkaddr, HRD_LEN(ap))));
436 		break;
437 
438 	case ARPOP_REVREQUEST:
439 		ND_PRINT((ndo, "who-is %s tell %s",
440 			  linkaddr_string(ndo, THA(ap), linkaddr, HRD_LEN(ap)),
441 			  linkaddr_string(ndo, SHA(ap), linkaddr, HRD_LEN(ap))));
442 		break;
443 
444 	case ARPOP_REVREPLY:
445 		ND_PRINT((ndo, "%s at ",
446 			  linkaddr_string(ndo, THA(ap), linkaddr, HRD_LEN(ap))));
447 		tpaddr_print_ip(ndo, ap, pro);
448 		break;
449 
450 	case ARPOP_INVREQUEST:
451 		ND_PRINT((ndo, "who-is %s tell %s",
452 			  linkaddr_string(ndo, THA(ap), linkaddr, HRD_LEN(ap)),
453 			  linkaddr_string(ndo, SHA(ap), linkaddr, HRD_LEN(ap))));
454 		break;
455 
456 	case ARPOP_INVREPLY:
457 		ND_PRINT((ndo,"%s at ",
458 			  linkaddr_string(ndo, SHA(ap), linkaddr, HRD_LEN(ap))));
459 		spaddr_print_ip(ndo, ap, pro);
460 		break;
461 
462 	default:
463 		ND_DEFAULTPRINT((const u_char *)ap, caplen);
464 		return;
465 	}
466 
467  out:
468         ND_PRINT((ndo, ", length %u", length));
469 
470 	return;
471 trunc:
472 	ND_PRINT((ndo, "%s", tstr));
473 }
474 
475 /*
476  * Local Variables:
477  * c-style: bsd
478  * End:
479  */
480 
481