1 /* $OpenBSD: print-arp.c,v 1.17 2021/12/01 18:28:45 deraadt Exp $ */
2
3 /*
4 * Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997
5 * The Regents of the University of California. All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that: (1) source code distributions
9 * retain the above copyright notice and this paragraph in its entirety, (2)
10 * distributions including binary code include the above copyright notice and
11 * this paragraph in its entirety in the documentation or other materials
12 * provided with the distribution, and (3) all advertising materials mentioning
13 * features or use of this software display the following acknowledgement:
14 * ``This product includes software developed by the University of California,
15 * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
16 * the University nor the names of its contributors may be used to endorse
17 * or promote products derived from this software without specific prior
18 * written permission.
19 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
20 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
21 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
22 */
23
24 #include <sys/time.h>
25 #include <sys/socket.h>
26
27 #include <net/if.h>
28
29 #include <netinet/in.h>
30 #include <netinet/if_ether.h>
31
32 #include <stdio.h>
33 #include <string.h>
34
35 #include "interface.h"
36 #include "addrtoname.h"
37 #include "ethertype.h"
38 #include "extract.h" /* must come after interface.h */
39
40 /* Compatibility */
41 #ifndef REVARP_REQUEST
42 #define REVARP_REQUEST 3
43 #endif
44 #ifndef REVARP_REPLY
45 #define REVARP_REPLY 4
46 #endif
47
48 static u_char ezero[6];
49
50 void
arp_print(const u_char * bp,u_int length,u_int caplen)51 arp_print(const u_char *bp, u_int length, u_int caplen)
52 {
53 const struct ether_arp *ap;
54 const struct ether_header *eh;
55 u_short pro, hrd, op;
56
57 ap = (struct ether_arp *)bp;
58 if ((u_char *)(ap + 1) > snapend) {
59 printf("[|arp]");
60 return;
61 }
62 if (length < sizeof(struct ether_arp)) {
63 printf("truncated-arp");
64 default_print((u_char *)ap, length);
65 return;
66 }
67
68 pro = EXTRACT_16BITS(&ap->arp_pro);
69 hrd = EXTRACT_16BITS(&ap->arp_hrd);
70 op = EXTRACT_16BITS(&ap->arp_op);
71
72 if ((pro != ETHERTYPE_IP && pro != ETHERTYPE_TRAIL)
73 || ap->arp_hln != sizeof(SHA(ap))
74 || ap->arp_pln != sizeof(SPA(ap))) {
75 printf("arp-#%d for proto #%d (%d) hardware #%d (%d)",
76 op, pro, ap->arp_pln, hrd, ap->arp_hln);
77 return;
78 }
79 if (pro == ETHERTYPE_TRAIL)
80 printf("trailer-");
81 eh = (struct ether_header *)packetp;
82 switch (op) {
83
84 case ARPOP_REQUEST:
85 printf("arp who-has %s", ipaddr_string(TPA(ap)));
86 if (memcmp((char *)ezero, (char *)THA(ap), 6) != 0)
87 printf(" (%s)", etheraddr_string(THA(ap)));
88 printf(" tell %s", ipaddr_string(SPA(ap)));
89 if (memcmp((char *)ESRC(eh), (char *)SHA(ap), 6) != 0)
90 printf(" (%s)", etheraddr_string(SHA(ap)));
91 break;
92
93 case ARPOP_REPLY:
94 printf("arp reply %s", ipaddr_string(SPA(ap)));
95 if (memcmp((char *)ESRC(eh), (char *)SHA(ap), 6) != 0)
96 printf(" (%s)", etheraddr_string(SHA(ap)));
97 printf(" is-at %s", etheraddr_string(SHA(ap)));
98 if (memcmp((char *)EDST(eh), (char *)THA(ap), 6) != 0)
99 printf(" (%s)", etheraddr_string(THA(ap)));
100 break;
101
102 case REVARP_REQUEST:
103 printf("rarp who-is %s tell %s",
104 etheraddr_string(THA(ap)),
105 etheraddr_string(SHA(ap)));
106 break;
107
108 case REVARP_REPLY:
109 printf("rarp reply %s at %s",
110 etheraddr_string(THA(ap)),
111 ipaddr_string(TPA(ap)));
112 break;
113
114 default:
115 printf("arp-#%d", op);
116 default_print((u_char *)ap, caplen);
117 return;
118 }
119 if (hrd != ARPHRD_ETHER)
120 printf(" hardware #%d", hrd);
121 }
122