/* * Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997 * The Regents of the University of California. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that: (1) source code distributions * retain the above copyright notice and this paragraph in its entirety, (2) * distributions including binary code include the above copyright notice and * this paragraph in its entirety in the documentation or other materials * provided with the distribution, and (3) all advertising materials mentioning * features or use of this software display the following acknowledgement: * ``This product includes software developed by the University of California, * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of * the University nor the names of its contributors may be used to endorse * or promote products derived from this software without specific prior * written permission. * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. * * $FreeBSD$ */ #ifndef lint static const char rcsid[] = "@(#) $Header: /tcpdump/master/tcpdump/print-arp.c,v 1.49 2000/10/10 05:05:07 guy Exp $ (LBL)"; #endif #ifdef HAVE_CONFIG_H #include "config.h" #endif #include #include #include #include #include #include "interface.h" #include "addrtoname.h" #include "ether.h" #include "ethertype.h" #include "extract.h" /* must come after interface.h */ /* * Address Resolution Protocol. * * See RFC 826 for protocol description. ARP packets are variable * in size; the arphdr structure defines the fixed-length portion. * Protocol type values are the same as those for 10 Mb/s Ethernet. * It is followed by the variable-sized fields ar_sha, arp_spa, * arp_tha and arp_tpa in that order, according to the lengths * specified. Field names used correspond to RFC 826. */ struct arphdr { u_short ar_hrd; /* format of hardware address */ #define ARPHRD_ETHER 1 /* ethernet hardware format */ #define ARPHRD_IEEE802 6 /* token-ring hardware format */ #define ARPHRD_FRELAY 15 /* frame relay hardware format */ u_short ar_pro; /* format of protocol address */ u_char ar_hln; /* length of hardware address */ u_char ar_pln; /* length of protocol address */ u_short ar_op; /* one of: */ #define ARPOP_REQUEST 1 /* request to resolve address */ #define ARPOP_REPLY 2 /* response to previous request */ #define ARPOP_REVREQUEST 3 /* request protocol address given hardware */ #define ARPOP_REVREPLY 4 /* response giving protocol address */ #define ARPOP_INVREQUEST 8 /* request to identify peer */ #define ARPOP_INVREPLY 9 /* response identifying peer */ /* * The remaining fields are variable in size, * according to the sizes above. */ #ifdef COMMENT_ONLY u_char ar_sha[]; /* sender hardware address */ u_char ar_spa[]; /* sender protocol address */ u_char ar_tha[]; /* target hardware address */ u_char ar_tpa[]; /* target protocol address */ #endif }; #define ARP_HDRLEN 8 /* * Ethernet Address Resolution Protocol. * * See RFC 826 for protocol description. Structure below is adapted * to resolving internet addresses. Field names used correspond to * RFC 826. */ struct ether_arp { struct arphdr ea_hdr; /* fixed-size header */ u_char arp_sha[6]; /* sender hardware address */ u_char arp_spa[4]; /* sender protocol address */ u_char arp_tha[6]; /* target hardware address */ u_char arp_tpa[4]; /* target protocol address */ }; #define arp_hrd ea_hdr.ar_hrd #define arp_pro ea_hdr.ar_pro #define arp_hln ea_hdr.ar_hln #define arp_pln ea_hdr.ar_pln #define arp_op ea_hdr.ar_op #define ETHER_ARP_HDRLEN (ARP_HDRLEN + 6 + 4 + 6 + 4) #define SHA(ap) ((ap)->arp_sha) #define THA(ap) ((ap)->arp_tha) #define SPA(ap) ((ap)->arp_spa) #define TPA(ap) ((ap)->arp_tpa) /* Compatibility */ #ifndef REVARP_REQUEST #define REVARP_REQUEST 3 #endif #ifndef REVARP_REPLY #define REVARP_REPLY 4 #endif static u_char ezero[6]; void arp_print(register const u_char *bp, u_int length, u_int caplen) { register const struct ether_arp *ap; register const struct ether_header *eh; register u_short pro, hrd, op; ap = (struct ether_arp *)bp; if ((u_char *)(ap + 1) > snapend) { printf("[|arp]"); return; } if (length < ETHER_ARP_HDRLEN) { (void)printf("truncated-arp"); default_print((u_char *)ap, length); return; } pro = EXTRACT_16BITS(&ap->arp_pro); hrd = EXTRACT_16BITS(&ap->arp_hrd); op = EXTRACT_16BITS(&ap->arp_op); if ((pro != ETHERTYPE_IP && pro != ETHERTYPE_TRAIL) || ap->arp_hln != sizeof(SHA(ap)) || ap->arp_pln != sizeof(SPA(ap))) { (void)printf("arp-#%d for proto #%d (%d) hardware #%d (%d)", op, pro, ap->arp_pln, hrd, ap->arp_hln); return; } if (pro == ETHERTYPE_TRAIL) (void)printf("trailer-"); eh = (struct ether_header *)packetp; switch (op) { case ARPOP_REQUEST: (void)printf("arp who-has %s", ipaddr_string(TPA(ap))); if (memcmp((char *)ezero, (char *)THA(ap), 6) != 0) (void)printf(" (%s)", etheraddr_string(THA(ap))); (void)printf(" tell %s", ipaddr_string(SPA(ap))); if (memcmp((char *)ESRC(eh), (char *)SHA(ap), 6) != 0) (void)printf(" (%s)", etheraddr_string(SHA(ap))); break; case ARPOP_REPLY: (void)printf("arp reply %s", ipaddr_string(SPA(ap))); if (memcmp((char *)ESRC(eh), (char *)SHA(ap), 6) != 0) (void)printf(" (%s)", etheraddr_string(SHA(ap))); (void)printf(" is-at %s", etheraddr_string(SHA(ap))); if (memcmp((char *)EDST(eh), (char *)THA(ap), 6) != 0) (void)printf(" (%s)", etheraddr_string(THA(ap))); break; case REVARP_REQUEST: (void)printf("rarp who-is %s tell %s", etheraddr_string(THA(ap)), etheraddr_string(SHA(ap))); break; case REVARP_REPLY: (void)printf("rarp reply %s at %s", etheraddr_string(THA(ap)), ipaddr_string(TPA(ap))); break; default: (void)printf("arp-#%d", op); default_print((u_char *)ap, caplen); return; } if (hrd != ARPHRD_ETHER) printf(" hardware #%d", hrd); }