inet.c revision 26175 
1/*
2 * Copyright (c) 1994, 1995, 1996
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 *    must display the following acknowledgement:
15 *	This product includes software developed by the Computer Systems
16 *	Engineering Group at Lawrence Berkeley Laboratory.
17 * 4. Neither the name of the University nor of the Laboratory may be used
18 *    to endorse or promote products derived from this software without
19 *    specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34#ifndef lint
35static const char rcsid[] =
36    "@(#) $Header: inet.c,v 1.20 96/10/19 14:58:47 leres Exp $ (LBL)";
37#endif
38
39#include <sys/param.h>
40#include <sys/file.h>
41#include <sys/ioctl.h>
42#include <sys/socket.h>
43#ifdef HAVE_SYS_SOCKIO_H
44#include <sys/sockio.h>
45#endif
46#include <sys/time.h>				/* concession to AIX */
47
48#if __STDC__
49struct mbuf;
50struct rtentry;
51#endif
52
53#include <net/if.h>
54#include <netinet/in.h>
55
56#include <ctype.h>
57#include <errno.h>
58#include <memory.h>
59#include <stdio.h>
60#include <stdlib.h>
61#include <string.h>
62#include <unistd.h>
63
64#include "pcap-int.h"
65
66#include "gnuc.h"
67#ifdef HAVE_OS_PROTO_H
68#include "os-proto.h"
69#endif
70
71/* Not all systems have IFF_LOOPBACK */
72#ifdef IFF_LOOPBACK
73#define ISLOOPBACK(p) ((p)->ifr_flags & IFF_LOOPBACK)
74#else
75#define ISLOOPBACK(p) (strcmp((p)->ifr_name, "lo0") == 0)
76#endif
77
78/*
79 * Return the name of a network interface attached to the system, or NULL
80 * if none can be found.  The interface must be configured up; the
81 * lowest unit number is preferred; loopback is ignored.
82 */
83char *
84pcap_lookupdev(errbuf)
85	register char *errbuf;
86{
87	register int fd, minunit, n;
88	register char *cp;
89	register struct ifreq *ifrp, *ifend, *ifnext, *mp;
90	struct ifconf ifc;
91	struct ifreq ibuf[16], ifr;
92	static char device[sizeof(ifrp->ifr_name) + 1];
93
94	fd = socket(AF_INET, SOCK_DGRAM, 0);
95	if (fd < 0) {
96		(void)sprintf(errbuf, "socket: %s", pcap_strerror(errno));
97		return (NULL);
98	}
99	ifc.ifc_len = sizeof ibuf;
100	ifc.ifc_buf = (caddr_t)ibuf;
101
102	if (ioctl(fd, SIOCGIFCONF, (char *)&ifc) < 0 ||
103	    ifc.ifc_len < sizeof(struct ifreq)) {
104		(void)sprintf(errbuf, "SIOCGIFCONF: %s", pcap_strerror(errno));
105		(void)close(fd);
106		return (NULL);
107	}
108	ifrp = ibuf;
109	ifend = (struct ifreq *)((char *)ibuf + ifc.ifc_len);
110
111	mp = NULL;
112	minunit = 666;
113	for (; ifrp < ifend; ifrp = ifnext) {
114#ifdef HAVE_SOCKADDR_SA_LEN
115		n = ifrp->ifr_addr.sa_len + sizeof(ifrp->ifr_name);
116		if (n < sizeof(*ifrp))
117			ifnext = ifrp + 1;
118		else
119			ifnext = (struct ifreq *)((char *)ifrp + n);
120		if (ifrp->ifr_addr.sa_family != AF_INET)
121			continue;
122#else
123		ifnext = ifrp + 1;
124#endif
125		/*
126		 * Need a template to preserve address info that is
127		 * used below to locate the next entry.  (Otherwise,
128		 * SIOCGIFFLAGS stomps over it because the requests
129		 * are returned in a union.)
130		 */
131		strncpy(ifr.ifr_name, ifrp->ifr_name, sizeof(ifr.ifr_name));
132		if (ioctl(fd, SIOCGIFFLAGS, (char *)&ifr) < 0) {
133			if (errno == ENXIO)
134				continue;
135			(void)sprintf(errbuf, "SIOCGIFFLAGS: %.*s: %s",
136			    (int)sizeof(ifr.ifr_name), ifr.ifr_name,
137			    pcap_strerror(errno));
138			(void)close(fd);
139			return (NULL);
140		}
141
142		/* Must be up and not the loopback */
143		if ((ifr.ifr_flags & IFF_UP) == 0 || ISLOOPBACK(&ifr))
144			continue;
145
146		for (cp = ifrp->ifr_name; !isdigit(*cp); ++cp)
147			continue;
148		n = atoi(cp);
149		if (n < minunit) {
150			minunit = n;
151			mp = ifrp;
152		}
153	}
154	(void)close(fd);
155	if (mp == NULL) {
156		(void)strcpy(errbuf, "no suitable device found");
157		return (NULL);
158	}
159
160	(void)strncpy(device, mp->ifr_name, sizeof(device) - 1);
161	device[sizeof(device) - 1] = '\0';
162	return (device);
163}
164
165int
166pcap_lookupnet(device, netp, maskp, errbuf)
167	register char *device;
168	register bpf_u_int32 *netp, *maskp;
169	register char *errbuf;
170{
171	register int fd;
172	register struct sockaddr_in *sin;
173	struct ifreq ifr;
174
175	fd = socket(AF_INET, SOCK_DGRAM, 0);
176	if (fd < 0) {
177		(void)sprintf(errbuf, "socket: %s", pcap_strerror(errno));
178		return (-1);
179	}
180	memset(&ifr, 0, sizeof(ifr));
181#ifdef linux
182	/* XXX Work around Linux kernel bug */
183	ifr.ifr_addr.sa_family = AF_INET;
184#endif
185	(void)strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
186	if (ioctl(fd, SIOCGIFADDR, (char *)&ifr) < 0) {
187		(void)sprintf(errbuf, "SIOCGIFADDR: %s: %s",
188		    device, pcap_strerror(errno));
189		(void)close(fd);
190		return (-1);
191	}
192	sin = (struct sockaddr_in *)&ifr.ifr_addr;
193	*netp = sin->sin_addr.s_addr;
194	if (ioctl(fd, SIOCGIFNETMASK, (char *)&ifr) < 0) {
195		(void)sprintf(errbuf, "SIOCGIFNETMASK: %s: %s",
196		    device, pcap_strerror(errno));
197		(void)close(fd);
198		return (-1);
199	}
200	(void)close(fd);
201	*maskp = sin->sin_addr.s_addr;
202	if (*maskp == 0) {
203		if (IN_CLASSA(*netp))
204			*maskp = IN_CLASSA_NET;
205		else if (IN_CLASSB(*netp))
206			*maskp = IN_CLASSB_NET;
207		else if (IN_CLASSC(*netp))
208			*maskp = IN_CLASSC_NET;
209		else {
210			(void)sprintf(errbuf, "inet class for 0x%x unknown",
211			    *netp);
212			return (-1);
213		}
214	}
215	*netp &= *maskp;
216	return (0);
217}
218