120 lines
2.7 KiB
C
120 lines
2.7 KiB
C
/*
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* arp.c (C) 1995 Darren Reed
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*
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* The author provides this program as-is, with no gaurantee for its
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* suitability for any specific purpose. The author takes no responsibility
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* for the misuse/abuse of this program and provides it for the sole purpose
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* of testing packet filter policies. This file maybe distributed freely
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* providing it is not modified and that this notice remains in tact.
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*/
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#if !defined(lint) && defined(LIBC_SCCS)
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static char sccsid[] = "@(#)arp.c 1.4 1/11/96 (C)1995 Darren Reed";
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#endif
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#include <stdio.h>
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#include <errno.h>
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <sys/sockio.h>
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#include <sys/ioctl.h>
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#include <netdb.h>
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#include <netinet/in.h>
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#include <net/if.h>
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#include <net/if_arp.h>
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#if defined(__SVR4) || defined(__svr4__)
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#define bcopy(a,b,c) memmove(b,a,c)
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#define bzero(a,c) memset(a,0,c)
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#define bcmp(a,b,c) memcmp(a,b,c)
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#endif
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/*
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* lookup host and return
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* its IP address in address
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* (4 bytes)
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*/
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int resolve(host, address)
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char *host, *address;
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{
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struct hostent *hp;
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u_long add;
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add = inet_addr(host);
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if (add == -1)
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{
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if (!(hp = gethostbyname(host)))
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{
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fprintf(stderr, "unknown host: %s\n", host);
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return -1;
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}
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bcopy((char *)hp->h_addr, (char *)address, 4);
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return 0;
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}
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bcopy((char*)&add, address, 4);
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return 0;
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}
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/*
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* ARP for the MAC address corresponding
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* to the IP address. This taken from
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* some BSD program, I cant remember which.
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*/
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int arp(ip, ether)
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char *ip;
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char *ether;
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{
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static int sfd = -1;
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static char ethersave[6], ipsave[4];
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struct arpreq ar;
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struct sockaddr_in *sin, san;
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struct hostent *hp;
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char *inet_ntoa();
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int fd;
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if (!bcmp(ipsave, ip, 4)) {
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bcopy(ethersave, ether, 6);
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return 0;
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}
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fd = -1;
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bzero((char *)&ar, sizeof(ar));
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sin = (struct sockaddr_in *)&ar.arp_pa;
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sin->sin_family = AF_INET;
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bcopy(ip, (char *)&sin->sin_addr.s_addr, 4);
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if ((hp = gethostbyaddr(ip, 4, AF_INET)))
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if (!(ether_hostton(hp->h_name, ether)))
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goto savearp;
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if (sfd == -1)
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if ((sfd = socket(AF_INET, SOCK_DGRAM, 0)) == -1)
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{
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perror("arp: socket");
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return -1;
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}
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tryagain:
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if (ioctl(sfd, SIOCGARP, (caddr_t)&ar) == -1)
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{
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if (fd == -1)
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{
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bzero((char *)&san, sizeof(san));
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san.sin_family = AF_INET;
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san.sin_port = htons(1);
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bcopy(ip, &san.sin_addr.s_addr, 4);
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fd = socket(AF_INET, SOCK_DGRAM, 0);
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(void) sendto(fd, ip, 4, 0,
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(struct sockaddr *)&san, sizeof(san));
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sleep(1);
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(void) close(fd);
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goto tryagain;
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}
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fprintf(stderr, "(%s):", inet_ntoa(sin->sin_addr));
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if (errno != ENXIO)
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perror("SIOCGARP");
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return -1;
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}
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bcopy(ar.arp_ha.sa_data, ether, 6);
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savearp:
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bcopy(ether, ethersave, 6);
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bcopy(ip, ipsave, 4);
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return 0;
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}
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