/* * 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 1.51.4.2 2002/07/10 07:09:53 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 arp_pkthdr { 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_ARCNET 7 /* arcnet hardware format */ #define ARPHRD_FRELAY 15 /* frame relay hardware format */ #define ARPHRD_STRIP 23 /* Ricochet Starmode Radio hardware format */ #define ARPHRD_IEEE1394 24 /* IEEE 1394 (FireWire) 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 ar_sha(ap) (((const u_char *)((ap)+1))+0) #define ar_spa(ap) (((const u_char *)((ap)+1))+ (ap)->ar_hln) #define ar_tha(ap) (((const u_char *)((ap)+1))+ (ap)->ar_hln+(ap)->ar_pln) #define ar_tpa(ap) (((const u_char *)((ap)+1))+2*(ap)->ar_hln+(ap)->ar_pln) }; #define ARP_HDRLEN 8 #define HRD(ap) ((ap)->ar_hrd) #define HLN(ap) ((ap)->ar_hln) #define PLN(ap) ((ap)->ar_pln) #define OP(ap) ((ap)->ar_op) #define PRO(ap) ((ap)->ar_pro) #define SHA(ap) (ar_sha(ap)) #define SPA(ap) (ar_spa(ap)) #define THA(ap) (ar_tha(ap)) #define TPA(ap) (ar_tpa(ap)) static u_char ezero[6]; void arp_print(const u_char *bp, u_int length, u_int caplen) { const struct arp_pkthdr *ap; u_short pro, hrd, op; ap = (const struct arp_pkthdr *)bp; TCHECK(*ap); if ((const u_char *)(ar_tpa(ap) + PLN(ap)) > snapend) { (void)printf("truncated-arp"); default_print((const u_char *)ap, length); return; } pro = EXTRACT_16BITS(&PRO(ap)); hrd = EXTRACT_16BITS(&HRD(ap)); op = EXTRACT_16BITS(&OP(ap)); if (pro != ETHERTYPE_IP && pro != ETHERTYPE_TRAIL) { (void)printf("arp-#%d for proto #%d (%d) hardware #%d (%d)", op, pro, PLN(ap), hrd, HLN(ap)); return; } if (pro == ETHERTYPE_TRAIL) (void)printf("trailer-"); switch (op) { case ARPOP_REQUEST: (void)printf("arp who-has %s", ipaddr_string(TPA(ap))); if (memcmp((const char *)ezero, (const char *)THA(ap), HLN(ap)) != 0) (void)printf(" (%s)", linkaddr_string(THA(ap), HLN(ap))); (void)printf(" tell %s", ipaddr_string(SPA(ap))); break; case ARPOP_REPLY: (void)printf("arp reply %s", ipaddr_string(SPA(ap))); (void)printf(" is-at %s", linkaddr_string(SHA(ap), HLN(ap))); break; case ARPOP_REVREQUEST: (void)printf("rarp who-is %s tell %s", linkaddr_string(THA(ap), HLN(ap)), linkaddr_string(SHA(ap), HLN(ap))); break; case ARPOP_REVREPLY: (void)printf("rarp reply %s at %s", linkaddr_string(THA(ap), HLN(ap)), ipaddr_string(TPA(ap))); break; default: (void)printf("arp-#%d", op); default_print((const u_char *)ap, caplen); return; } if (hrd != ARPHRD_ETHER) printf(" hardware #%d", hrd); return; trunc: (void)printf("[|arp]"); }