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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
atmarp_addr_print(netdissect_options * ndo,const u_char * ha,u_int ha_len,const u_char * srca,u_int srca_len)193 atmarp_addr_print(netdissect_options *ndo,
194 		  const u_char *ha, u_int ha_len, const u_char *srca,
195     u_int srca_len)
196 {
197 	if (ha_len == 0)
198 		ND_PRINT((ndo, "<No address>"));
199 	else {
200 		ND_PRINT((ndo, "%s", linkaddr_string(ndo, ha, LINKADDR_ATM, ha_len)));
201 		if (srca_len != 0)
202 			ND_PRINT((ndo, ",%s",
203 				  linkaddr_string(ndo, srca, LINKADDR_ATM, srca_len)));
204 	}
205 }
206 
207 static void
atmarp_print(netdissect_options * ndo,const u_char * bp,u_int length,u_int caplen)208 atmarp_print(netdissect_options *ndo,
209 	     const u_char *bp, u_int length, u_int caplen)
210 {
211 	const struct atmarp_pkthdr *ap;
212 	u_short pro, hrd, op;
213 
214 	ap = (const struct atmarp_pkthdr *)bp;
215 	ND_TCHECK(*ap);
216 
217 	hrd = ATMHRD(ap);
218 	pro = ATMPRO(ap);
219 	op = ATMOP(ap);
220 
221 	if (!ND_TTEST2(*aar_tpa(ap), ATMTPROTO_LEN(ap))) {
222 		ND_PRINT((ndo, "%s", tstr));
223 		ND_DEFAULTPRINT((const u_char *)ap, length);
224 		return;
225 	}
226 
227         if (!ndo->ndo_eflag) {
228             ND_PRINT((ndo, "ARP, "));
229         }
230 
231 	if ((pro != ETHERTYPE_IP && pro != ETHERTYPE_TRAIL) ||
232 	    ATMSPROTO_LEN(ap) != 4 ||
233             ATMTPROTO_LEN(ap) != 4 ||
234             ndo->ndo_vflag) {
235                 ND_PRINT((ndo, "%s, %s (len %u/%u)",
236                           tok2str(arphrd_values, "Unknown Hardware (%u)", hrd),
237                           tok2str(ethertype_values, "Unknown Protocol (0x%04x)", pro),
238                           ATMSPROTO_LEN(ap),
239                           ATMTPROTO_LEN(ap)));
240 
241                 /* don't know know about the address formats */
242                 if (!ndo->ndo_vflag) {
243                     goto out;
244                 }
245 	}
246 
247         /* print operation */
248         ND_PRINT((ndo, "%s%s ",
249                ndo->ndo_vflag ? ", " : "",
250                tok2str(arpop_values, "Unknown (%u)", op)));
251 
252 	switch (op) {
253 
254 	case ARPOP_REQUEST:
255 		ND_PRINT((ndo, "who-has %s", ipaddr_string(ndo, ATMTPA(ap))));
256 		if (ATMTHRD_LEN(ap) != 0) {
257 			ND_PRINT((ndo, " ("));
258 			atmarp_addr_print(ndo, ATMTHA(ap), ATMTHRD_LEN(ap),
259 			    ATMTSA(ap), ATMTSLN(ap));
260 			ND_PRINT((ndo, ")"));
261 		}
262 		ND_PRINT((ndo, "tell %s", ipaddr_string(ndo, ATMSPA(ap))));
263 		break;
264 
265 	case ARPOP_REPLY:
266 		ND_PRINT((ndo, "%s is-at ", ipaddr_string(ndo, ATMSPA(ap))));
267 		atmarp_addr_print(ndo, ATMSHA(ap), ATMSHRD_LEN(ap), ATMSSA(ap),
268                                   ATMSSLN(ap));
269 		break;
270 
271 	case ARPOP_INVREQUEST:
272 		ND_PRINT((ndo, "who-is "));
273 		atmarp_addr_print(ndo, ATMTHA(ap), ATMTHRD_LEN(ap), ATMTSA(ap),
274 		    ATMTSLN(ap));
275 		ND_PRINT((ndo, " tell "));
276 		atmarp_addr_print(ndo, ATMSHA(ap), ATMSHRD_LEN(ap), ATMSSA(ap),
277 		    ATMSSLN(ap));
278 		break;
279 
280 	case ARPOP_INVREPLY:
281 		atmarp_addr_print(ndo, ATMSHA(ap), ATMSHRD_LEN(ap), ATMSSA(ap),
282 		    ATMSSLN(ap));
283 		ND_PRINT((ndo, "at %s", ipaddr_string(ndo, ATMSPA(ap))));
284 		break;
285 
286 	case ARPOP_NAK:
287 		ND_PRINT((ndo, "for %s", ipaddr_string(ndo, ATMSPA(ap))));
288 		break;
289 
290 	default:
291 		ND_DEFAULTPRINT((const u_char *)ap, caplen);
292 		return;
293 	}
294 
295  out:
296         ND_PRINT((ndo, ", length %u", length));
297         return;
298 
299 trunc:
300 	ND_PRINT((ndo, "%s", tstr));
301 }
302 
303 void
arp_print(netdissect_options * ndo,const u_char * bp,u_int length,u_int caplen)304 arp_print(netdissect_options *ndo,
305 	  const u_char *bp, u_int length, u_int caplen)
306 {
307 	const struct arp_pkthdr *ap;
308 	u_short pro, hrd, op, linkaddr;
309 
310 	ap = (const struct arp_pkthdr *)bp;
311 	ND_TCHECK(*ap);
312 
313 	hrd = HRD(ap);
314 	pro = PRO(ap);
315 	op = OP(ap);
316 
317 
318         /* if its ATM then call the ATM ARP printer
319            for Frame-relay ARP most of the fields
320            are similar to Ethernet so overload the Ethernet Printer
321            and set the linkaddr type for linkaddr_string(ndo, ) accordingly */
322 
323         switch(hrd) {
324         case ARPHRD_ATM2225:
325             atmarp_print(ndo, bp, length, caplen);
326             return;
327         case ARPHRD_FRELAY:
328             linkaddr = LINKADDR_FRELAY;
329             break;
330         default:
331             linkaddr = LINKADDR_ETHER;
332             break;
333 	}
334 
335 	if (!ND_TTEST2(*ar_tpa(ap), PROTO_LEN(ap))) {
336 		ND_PRINT((ndo, "%s", tstr));
337 		ND_DEFAULTPRINT((const u_char *)ap, length);
338 		return;
339 	}
340 
341         if (!ndo->ndo_eflag) {
342             ND_PRINT((ndo, "ARP, "));
343         }
344 
345         /* print hardware type/len and proto type/len */
346         if ((pro != ETHERTYPE_IP && pro != ETHERTYPE_TRAIL) ||
347 	    PROTO_LEN(ap) != 4 ||
348             HRD_LEN(ap) == 0 ||
349             ndo->ndo_vflag) {
350             ND_PRINT((ndo, "%s (len %u), %s (len %u)",
351                       tok2str(arphrd_values, "Unknown Hardware (%u)", hrd),
352                       HRD_LEN(ap),
353                       tok2str(ethertype_values, "Unknown Protocol (0x%04x)", pro),
354                       PROTO_LEN(ap)));
355 
356             /* don't know know about the address formats */
357             if (!ndo->ndo_vflag) {
358                 goto out;
359             }
360 	}
361 
362         /* print operation */
363         ND_PRINT((ndo, "%s%s ",
364                ndo->ndo_vflag ? ", " : "",
365                tok2str(arpop_values, "Unknown (%u)", op)));
366 
367 	switch (op) {
368 
369 	case ARPOP_REQUEST:
370 		ND_PRINT((ndo, "who-has %s", ipaddr_string(ndo, TPA(ap))));
371 		if (isnonzero((const u_char *)THA(ap), HRD_LEN(ap)))
372 			ND_PRINT((ndo, " (%s)",
373 				  linkaddr_string(ndo, THA(ap), linkaddr, HRD_LEN(ap))));
374 		ND_PRINT((ndo, " tell %s", ipaddr_string(ndo, SPA(ap))));
375 		break;
376 
377 	case ARPOP_REPLY:
378 		ND_PRINT((ndo, "%s is-at %s",
379                           ipaddr_string(ndo, SPA(ap)),
380                           linkaddr_string(ndo, SHA(ap), linkaddr, HRD_LEN(ap))));
381 		break;
382 
383 	case ARPOP_REVREQUEST:
384 		ND_PRINT((ndo, "who-is %s tell %s",
385 			  linkaddr_string(ndo, THA(ap), linkaddr, HRD_LEN(ap)),
386 			  linkaddr_string(ndo, SHA(ap), linkaddr, HRD_LEN(ap))));
387 		break;
388 
389 	case ARPOP_REVREPLY:
390 		ND_PRINT((ndo, "%s at %s",
391 			  linkaddr_string(ndo, THA(ap), linkaddr, HRD_LEN(ap)),
392 			  ipaddr_string(ndo, TPA(ap))));
393 		break;
394 
395 	case ARPOP_INVREQUEST:
396 		ND_PRINT((ndo, "who-is %s tell %s",
397 			  linkaddr_string(ndo, THA(ap), linkaddr, HRD_LEN(ap)),
398 			  linkaddr_string(ndo, SHA(ap), linkaddr, HRD_LEN(ap))));
399 		break;
400 
401 	case ARPOP_INVREPLY:
402 		ND_PRINT((ndo,"%s at %s",
403 			  linkaddr_string(ndo, SHA(ap), linkaddr, HRD_LEN(ap)),
404 			  ipaddr_string(ndo, SPA(ap))));
405 		break;
406 
407 	default:
408 		ND_DEFAULTPRINT((const u_char *)ap, caplen);
409 		return;
410 	}
411 
412  out:
413         ND_PRINT((ndo, ", length %u", length));
414 
415 	return;
416 trunc:
417 	ND_PRINT((ndo, "%s", tstr));
418 }
419 
420 /*
421  * Local Variables:
422  * c-style: bsd
423  * End:
424  */
425 
426