arp.c revision 92686 
1/*
2 * arp.c (C) 1995-1998 Darren Reed
3 *
4 * See the IPFILTER.LICENCE file for details on licencing.
5 */
6#ifdef __sgi
7# include <sys/ptimers.h>
8#endif
9#include <stdio.h>
10#include <errno.h>
11#include <sys/types.h>
12#include <sys/socket.h>
13#if !defined(ultrix) && !defined(hpux)
14#include <sys/sockio.h>
15#endif
16#include <sys/ioctl.h>
17#include <netdb.h>
18#include <netinet/in.h>
19#include <net/if.h>
20#include <netinet/if_ether.h>
21#ifndef	ultrix
22#include <net/if_arp.h>
23#endif
24#include <netinet/in.h>
25#include <netinet/ip_var.h>
26#include <netinet/tcp.h>
27#include "ipsend.h"
28#include "iplang/iplang.h"
29
30#if !defined(lint)
31static const char sccsid[] = "@(#)arp.c	1.4 1/11/96 (C)1995 Darren Reed";
32static const char rcsid[] = "@(#)$Id: arp.c,v 2.1.4.3 2002/02/22 15:32:57 darrenr Exp $";
33#endif
34
35
36/*
37 * lookup host and return
38 * its IP address in address
39 * (4 bytes)
40 */
41int	resolve(host, address)
42char	*host, *address;
43{
44        struct	hostent	*hp;
45        u_long	add;
46
47	add = inet_addr(host);
48	if (add == -1)
49	    {
50		if (!(hp = gethostbyname(host)))
51		    {
52			fprintf(stderr, "unknown host: %s\n", host);
53			return -1;
54		    }
55		bcopy((char *)hp->h_addr, (char *)address, 4);
56		return 0;
57	}
58	bcopy((char*)&add, address, 4);
59	return 0;
60}
61
62/*
63 * ARP for the MAC address corresponding
64 * to the IP address.  This taken from
65 * some BSD program, I cant remember which.
66 */
67int	arp(ip, ether)
68char	*ip;
69char	*ether;
70{
71	static	int	sfd = -1;
72	static	char	ethersave[6], ipsave[4];
73	struct	arpreq	ar;
74	struct	sockaddr_in	*sin, san;
75	struct	hostent	*hp;
76	int	fd;
77
78#ifdef	IPSEND
79	if (arp_getipv4(ip, ether) == 0)
80		return 0;
81#endif
82	if (!bcmp(ipsave, ip, 4)) {
83		bcopy(ethersave, ether, 6);
84		return 0;
85	}
86	fd = -1;
87	bzero((char *)&ar, sizeof(ar));
88	sin = (struct sockaddr_in *)&ar.arp_pa;
89	sin->sin_family = AF_INET;
90	bcopy(ip, (char *)&sin->sin_addr.s_addr, 4);
91#ifndef	hpux
92	if ((hp = gethostbyaddr(ip, 4, AF_INET)))
93		if (!(ether_hostton(hp->h_name, ether)))
94			goto savearp;
95#endif
96
97	if (sfd == -1)
98		if ((sfd = socket(AF_INET, SOCK_DGRAM, 0)) == -1)
99		    {
100			perror("arp: socket");
101			return -1;
102		    }
103tryagain:
104	if (ioctl(sfd, SIOCGARP, (caddr_t)&ar) == -1)
105	    {
106		if (fd == -1)
107		    {
108			bzero((char *)&san, sizeof(san));
109			san.sin_family = AF_INET;
110			san.sin_port = htons(1);
111			bcopy(ip, &san.sin_addr.s_addr, 4);
112			fd = socket(AF_INET, SOCK_DGRAM, 0);
113			(void) sendto(fd, ip, 4, 0,
114				      (struct sockaddr *)&san, sizeof(san));
115			sleep(1);
116			(void) close(fd);
117			goto tryagain;
118		    }
119		fprintf(stderr, "(%s):", inet_ntoa(sin->sin_addr));
120		if (errno != ENXIO)
121			perror("SIOCGARP");
122		return -1;
123	    }
124
125	bcopy(ar.arp_ha.sa_data, ether, 6);
126savearp:
127	bcopy(ether, ethersave, 6);
128	bcopy(ip, ipsave, 4);
129	return 0;
130}
131