arp.c revision 344833 
1/*	$FreeBSD: stable/11/contrib/ipfilter/ipsend/arp.c 344833 2019-03-06 02:37:25Z cy $	*/
2
3/*
4 * arp.c (C) 1995-1998 Darren Reed
5 *
6 * See the IPFILTER.LICENCE file for details on licencing.
7 */
8#if !defined(lint)
9static const char sccsid[] = "@(#)arp.c	1.4 1/11/96 (C)1995 Darren Reed";
10static const char rcsid[] = "@(#)$Id$";
11#endif
12#include <sys/types.h>
13#include <sys/socket.h>
14#if !defined(ultrix) && !defined(hpux) && !defined(__hpux) && !defined(__osf__) && !defined(_AIX51)
15# include <sys/sockio.h>
16#endif
17#include <sys/ioctl.h>
18#include <netinet/in_systm.h>
19#include <netinet/in.h>
20#include <net/if.h>
21#include <netinet/if_ether.h>
22#ifndef	ultrix
23# include <net/if_arp.h>
24#endif
25#include <netinet/in.h>
26#include <netinet/ip.h>
27#include <netinet/ip_var.h>
28#include <netinet/tcp.h>
29#include <stdio.h>
30#include <errno.h>
31#include <netdb.h>
32#include "ipsend.h"
33#include "iplang/iplang.h"
34
35
36/*
37 * lookup host and return
38 * its IP address in address
39 * (4 bytes)
40 */
41int	resolve(host, address)
42	char	*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)
68	char	*ip;
69	char	*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	if ((hp = gethostbyaddr(ip, 4, AF_INET)))
92# if SOLARIS && (SOLARIS2 >= 10)
93		if (!(ether_hostton(hp->h_name, (struct ether_addr *)ether)))
94# else
95		if (!(ether_hostton(hp->h_name, ether)))
96# endif
97			goto savearp;
98
99	if (sfd == -1)
100		if ((sfd = socket(AF_INET, SOCK_DGRAM, 0)) == -1)
101		    {
102			perror("arp: socket");
103			return -1;
104		    }
105tryagain:
106	if (ioctl(sfd, SIOCGARP, (caddr_t)&ar) == -1)
107	    {
108		if (fd == -1)
109		    {
110			bzero((char *)&san, sizeof(san));
111			san.sin_family = AF_INET;
112			san.sin_port = htons(1);
113			bcopy(ip, &san.sin_addr.s_addr, 4);
114			fd = socket(AF_INET, SOCK_DGRAM, 0);
115			(void) sendto(fd, ip, 4, 0,
116				      (struct sockaddr *)&san, sizeof(san));
117			sleep(1);
118			(void) close(fd);
119			goto tryagain;
120		    }
121		fprintf(stderr, "(%s):", inet_ntoa(sin->sin_addr));
122		if (errno != ENXIO)
123			perror("SIOCGARP");
124		return -1;
125	    }
126
127	if ((ar.arp_ha.sa_data[0] == 0) && (ar.arp_ha.sa_data[1] == 0) &&
128	    (ar.arp_ha.sa_data[2] == 0) && (ar.arp_ha.sa_data[3] == 0) &&
129	    (ar.arp_ha.sa_data[4] == 0) && (ar.arp_ha.sa_data[5] == 0)) {
130		fprintf(stderr, "(%s):", inet_ntoa(sin->sin_addr));
131		return -1;
132	}
133
134	bcopy(ar.arp_ha.sa_data, ether, 6);
135savearp:
136	bcopy(ether, ethersave, 6);
137	bcopy(ip, ipsave, 4);
138	return 0;
139}
140