inet.c revision 56889 
1/*
2 * Copyright (c) 1994, 1995, 1996, 1997, 1998
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: /tcpdump/master/libpcap/inet.c,v 1.24.2.1 2000/01/14 18:00:50 mcr 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) ((p)->ifr_name[0] == 'l' && (p)->ifr_name[1] == 'o' && \
76    (isdigit((p)->ifr_name[2]) || (p)->ifr_name[2] == '\0'))
77#endif
78
79/*
80 * Return the name of a network interface attached to the system, or NULL
81 * if none can be found.  The interface must be configured up; the
82 * lowest unit number is preferred; loopback is ignored.
83 */
84char *
85pcap_lookupdev(errbuf)
86	register char *errbuf;
87{
88	register int fd, minunit, n;
89	register char *cp;
90	register struct ifreq *ifrp, *ifend, *ifnext, *mp;
91	struct ifconf ifc;
92	char *buf;
93	struct ifreq ifr;
94	static char device[sizeof(ifrp->ifr_name) + 1];
95	unsigned buf_size;
96
97	fd = socket(AF_INET, SOCK_DGRAM, 0);
98	if (fd < 0) {
99		(void)sprintf(errbuf, "socket: %s", pcap_strerror(errno));
100		return (NULL);
101	}
102
103	buf_size = 8192;
104
105	for (;;) {
106		buf = malloc (buf_size);
107		if (buf == NULL) {
108			close (fd);
109			(void)sprintf(errbuf, "out of memory");
110			return (NULL);
111		}
112
113		ifc.ifc_len = buf_size;
114		ifc.ifc_buf = buf;
115		memset (buf, 0, buf_size);
116		if (ioctl(fd, SIOCGIFCONF, (char *)&ifc) < 0) {
117			free (buf);
118			(void)sprintf(errbuf, "SIOCGIFCONF: %s",
119				      pcap_strerror(errno));
120			(void)close(fd);
121			return (NULL);
122		}
123		if (ifc.ifc_len < buf_size)
124			break;
125		free (buf);
126		buf_size *= 2;
127	}
128
129	ifrp = (struct ifreq *)buf;
130	ifend = (struct ifreq *)(buf + ifc.ifc_len);
131
132	mp = NULL;
133	minunit = 666;
134	for (; ifrp < ifend; ifrp = ifnext) {
135#ifdef HAVE_SOCKADDR_SA_LEN
136		n = ifrp->ifr_addr.sa_len + sizeof(ifrp->ifr_name);
137		if (n < sizeof(*ifrp))
138			ifnext = ifrp + 1;
139		else
140			ifnext = (struct ifreq *)((char *)ifrp + n);
141		if (ifrp->ifr_addr.sa_family != AF_INET)
142			continue;
143#else
144		ifnext = ifrp + 1;
145#endif
146		/*
147		 * Need a template to preserve address info that is
148		 * used below to locate the next entry.  (Otherwise,
149		 * SIOCGIFFLAGS stomps over it because the requests
150		 * are returned in a union.)
151		 */
152		strncpy(ifr.ifr_name, ifrp->ifr_name, sizeof(ifr.ifr_name));
153		if (ioctl(fd, SIOCGIFFLAGS, (char *)&ifr) < 0) {
154			if (errno == ENXIO)
155				continue;
156			(void)sprintf(errbuf, "SIOCGIFFLAGS: %.*s: %s",
157			    (int)sizeof(ifr.ifr_name), ifr.ifr_name,
158			    pcap_strerror(errno));
159			(void)close(fd);
160			free (buf);
161			return (NULL);
162		}
163
164		/* Must be up and not the loopback */
165		if ((ifr.ifr_flags & IFF_UP) == 0 || ISLOOPBACK(&ifr))
166			continue;
167
168		for (cp = ifrp->ifr_name; !isdigit(*cp); ++cp)
169			continue;
170		n = atoi(cp);
171		if (n < minunit) {
172			minunit = n;
173			mp = ifrp;
174		}
175	}
176	free(buf);
177	(void)close(fd);
178	if (mp == NULL) {
179		(void)strcpy(errbuf, "no suitable device found");
180		return (NULL);
181	}
182
183	(void)strncpy(device, mp->ifr_name, sizeof(device) - 1);
184	device[sizeof(device) - 1] = '\0';
185	return (device);
186}
187
188int
189pcap_lookupnet(device, netp, maskp, errbuf)
190	register char *device;
191	register bpf_u_int32 *netp, *maskp;
192	register char *errbuf;
193{
194	register int fd;
195	register struct sockaddr_in *sin;
196	struct ifreq ifr;
197
198	fd = socket(AF_INET, SOCK_DGRAM, 0);
199	if (fd < 0) {
200		(void)sprintf(errbuf, "socket: %s", pcap_strerror(errno));
201		return (-1);
202	}
203	memset(&ifr, 0, sizeof(ifr));
204#ifdef linux
205	/* XXX Work around Linux kernel bug */
206	ifr.ifr_addr.sa_family = AF_INET;
207#endif
208	(void)strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
209	if (ioctl(fd, SIOCGIFADDR, (char *)&ifr) < 0) {
210		if (errno == EADDRNOTAVAIL) {
211			(void)sprintf(errbuf, "%s: no IPv4 address assigned",
212			    device);
213		} else {
214			(void)sprintf(errbuf, "SIOCGIFADDR: %s: %s",
215			    device, pcap_strerror(errno));
216		}
217		(void)close(fd);
218		return (-1);
219	}
220	sin = (struct sockaddr_in *)&ifr.ifr_addr;
221	*netp = sin->sin_addr.s_addr;
222	if (ioctl(fd, SIOCGIFNETMASK, (char *)&ifr) < 0) {
223		(void)sprintf(errbuf, "SIOCGIFNETMASK: %s: %s",
224		    device, pcap_strerror(errno));
225		(void)close(fd);
226		return (-1);
227	}
228	(void)close(fd);
229	*maskp = sin->sin_addr.s_addr;
230	if (*maskp == 0) {
231		if (IN_CLASSA(*netp))
232			*maskp = IN_CLASSA_NET;
233		else if (IN_CLASSB(*netp))
234			*maskp = IN_CLASSB_NET;
235		else if (IN_CLASSC(*netp))
236			*maskp = IN_CLASSC_NET;
237		else {
238			(void)sprintf(errbuf, "inet class for 0x%x unknown",
239			    *netp);
240			return (-1);
241		}
242	}
243	*netp &= *maskp;
244	return (0);
245}
246