1 /* -*- Mode: c; tab-width: 8; indent-tabs-mode: 1; c-basic-offset: 8; -*- */
2 /*
3  * Copyright (c) 1994, 1995, 1996, 1997, 1998
4  *	The Regents of the University of California.  All rights reserved.
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  * 1. Redistributions of source code must retain the above copyright
10  *    notice, this list of conditions and the following disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in the
13  *    documentation and/or other materials provided with the distribution.
14  * 3. All advertising materials mentioning features or use of this software
15  *    must display the following acknowledgement:
16  *	This product includes software developed by the Computer Systems
17  *	Engineering Group at Lawrence Berkeley Laboratory.
18  * 4. Neither the name of the University nor of the Laboratory may be used
19  *    to endorse or promote products derived from this software without
20  *    specific prior written permission.
21  *
22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32  * SUCH DAMAGE.
33  */
34 
35 #ifndef lint
36 static const char rcsid[] _U_ =
37     "@(#) $Header: /tcpdump/master/libpcap/fad-gifc.c,v 1.12 2008-08-06 07:34:09 guy Exp $ (LBL)";
38 #endif
39 
40 #ifdef HAVE_CONFIG_H
41 #include "config.h"
42 #endif
43 
44 #include <sys/param.h>
45 #include <sys/ioctl.h>
46 #include <sys/socket.h>
47 #ifdef HAVE_SYS_SOCKIO_H
48 #include <sys/sockio.h>
49 #endif
50 #include <sys/time.h>				/* concession to AIX */
51 
52 struct mbuf;		/* Squelch compiler warnings on some platforms for */
53 struct rtentry;		/* declarations in <net/if.h> */
54 #include <net/if.h>
55 #include <netinet/in.h>
56 
57 #include <ctype.h>
58 #include <errno.h>
59 #include <memory.h>
60 #include <stdio.h>
61 #include <stdlib.h>
62 #include <string.h>
63 #include <unistd.h>
64 
65 #include "pcap-int.h"
66 
67 #ifdef HAVE_OS_PROTO_H
68 #include "os-proto.h"
69 #endif
70 
71 /*
72  * This is fun.
73  *
74  * In older BSD systems, socket addresses were fixed-length, and
75  * "sizeof (struct sockaddr)" gave the size of the structure.
76  * All addresses fit within a "struct sockaddr".
77  *
78  * In newer BSD systems, the socket address is variable-length, and
79  * there's an "sa_len" field giving the length of the structure;
80  * this allows socket addresses to be longer than 2 bytes of family
81  * and 14 bytes of data.
82  *
83  * Some commercial UNIXes use the old BSD scheme, some use the RFC 2553
84  * variant of the old BSD scheme (with "struct sockaddr_storage" rather
85  * than "struct sockaddr"), and some use the new BSD scheme.
86  *
87  * Some versions of GNU libc use neither scheme, but has an "SA_LEN()"
88  * macro that determines the size based on the address family.  Other
89  * versions don't have "SA_LEN()" (as it was in drafts of RFC 2553
90  * but not in the final version).
91  *
92  * We assume that a UNIX that doesn't have "getifaddrs()" and doesn't have
93  * SIOCGLIFCONF, but has SIOCGIFCONF, uses "struct sockaddr" for the
94  * address in an entry returned by SIOCGIFCONF.
95  */
96 #ifndef SA_LEN
97 #ifdef HAVE_SOCKADDR_SA_LEN
98 #define SA_LEN(addr)	((addr)->sa_len)
99 #else /* HAVE_SOCKADDR_SA_LEN */
100 #define SA_LEN(addr)	(sizeof (struct sockaddr))
101 #endif /* HAVE_SOCKADDR_SA_LEN */
102 #endif /* SA_LEN */
103 
104 /*
105  * This is also fun.
106  *
107  * There is no ioctl that returns the amount of space required for all
108  * the data that SIOCGIFCONF could return, and if a buffer is supplied
109  * that's not large enough for all the data SIOCGIFCONF could return,
110  * on at least some platforms it just returns the data that'd fit with
111  * no indication that there wasn't enough room for all the data, much
112  * less an indication of how much more room is required.
113  *
114  * The only way to ensure that we got all the data is to pass a buffer
115  * large enough that the amount of space in the buffer *not* filled in
116  * is greater than the largest possible entry.
117  *
118  * We assume that's "sizeof(ifreq.ifr_name)" plus 255, under the assumption
119  * that no address is more than 255 bytes (on systems where the "sa_len"
120  * field in a "struct sockaddr" is 1 byte, e.g. newer BSDs, that's the
121  * case, and addresses are unlikely to be bigger than that in any case).
122  */
123 #define MAX_SA_LEN	255
124 
125 /*
126  * Get a list of all interfaces that are up and that we can open.
127  * Returns -1 on error, 0 otherwise.
128  * The list, as returned through "alldevsp", may be null if no interfaces
129  * were up and could be opened.
130  *
131  * This is the implementation used on platforms that have SIOCGIFCONF but
132  * don't have any other mechanism for getting a list of interfaces.
133  *
134  * XXX - or platforms that have other, better mechanisms but for which
135  * we don't yet have code to use that mechanism; I think there's a better
136  * way on Linux, for example, but if that better way is "getifaddrs()",
137  * we already have that.
138  */
139 int
pcap_findalldevs_interfaces(pcap_if_t ** alldevsp,char * errbuf)140 pcap_findalldevs_interfaces(pcap_if_t **alldevsp, char *errbuf)
141 {
142 	pcap_if_t *devlist = NULL;
143 	register int fd;
144 	register struct ifreq *ifrp, *ifend, *ifnext;
145 	int n;
146 	struct ifconf ifc;
147 	char *buf = NULL;
148 	unsigned buf_size;
149 #if defined (HAVE_SOLARIS) || defined (HAVE_HPUX10_20_OR_LATER)
150 	char *p, *q;
151 #endif
152 	struct ifreq ifrflags, ifrnetmask, ifrbroadaddr, ifrdstaddr;
153 	struct sockaddr *netmask, *broadaddr, *dstaddr;
154 	size_t netmask_size, broadaddr_size, dstaddr_size;
155 	int ret = 0;
156 
157 	/*
158 	 * Create a socket from which to fetch the list of interfaces.
159 	 */
160 	fd = socket(AF_INET, SOCK_DGRAM, 0);
161 	if (fd < 0) {
162 		(void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
163 		    "socket: %s", pcap_strerror(errno));
164 		return (-1);
165 	}
166 
167 	/*
168 	 * Start with an 8K buffer, and keep growing the buffer until
169 	 * we have more than "sizeof(ifrp->ifr_name) + MAX_SA_LEN"
170 	 * bytes left over in the buffer or we fail to get the
171 	 * interface list for some reason other than EINVAL (which is
172 	 * presumed here to mean "buffer is too small").
173 	 */
174 	buf_size = 8192;
175 	for (;;) {
176 		buf = malloc(buf_size);
177 		if (buf == NULL) {
178 			(void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
179 			    "malloc: %s", pcap_strerror(errno));
180 			(void)close(fd);
181 			return (-1);
182 		}
183 
184 		ifc.ifc_len = buf_size;
185 		ifc.ifc_buf = buf;
186 		memset(buf, 0, buf_size);
187 		if (ioctl(fd, SIOCGIFCONF, (char *)&ifc) < 0
188 		    && errno != EINVAL) {
189 			(void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
190 			    "SIOCGIFCONF: %s", pcap_strerror(errno));
191 			(void)close(fd);
192 			free(buf);
193 			return (-1);
194 		}
195 		if (ifc.ifc_len < buf_size &&
196 		    (buf_size - ifc.ifc_len) > sizeof(ifrp->ifr_name) + MAX_SA_LEN)
197 			break;
198 		free(buf);
199 		buf_size *= 2;
200 	}
201 
202 	ifrp = (struct ifreq *)buf;
203 	ifend = (struct ifreq *)(buf + ifc.ifc_len);
204 
205 	for (; ifrp < ifend; ifrp = ifnext) {
206 		/*
207 		 * XXX - what if this isn't an IPv4 address?  Can
208 		 * we still get the netmask, etc. with ioctls on
209 		 * an IPv4 socket?
210 		 *
211 		 * The answer is probably platform-dependent, and
212 		 * if the answer is "no" on more than one platform,
213 		 * the way you work around it is probably platform-
214 		 * dependent as well.
215 		 */
216 		n = SA_LEN(&ifrp->ifr_addr) + sizeof(ifrp->ifr_name);
217 		if (n < sizeof(*ifrp))
218 			ifnext = ifrp + 1;
219 		else
220 			ifnext = (struct ifreq *)((char *)ifrp + n);
221 
222 		/*
223 		 * XXX - The 32-bit compatibility layer for Linux on IA-64
224 		 * is slightly broken. It correctly converts the structures
225 		 * to and from kernel land from 64 bit to 32 bit but
226 		 * doesn't update ifc.ifc_len, leaving it larger than the
227 		 * amount really used. This means we read off the end
228 		 * of the buffer and encounter an interface with an
229 		 * "empty" name. Since this is highly unlikely to ever
230 		 * occur in a valid case we can just finish looking for
231 		 * interfaces if we see an empty name.
232 		 */
233 		if (!(*ifrp->ifr_name))
234 			break;
235 
236 		/*
237 		 * Skip entries that begin with "dummy".
238 		 * XXX - what are these?  Is this Linux-specific?
239 		 * Are there platforms on which we shouldn't do this?
240 		 */
241 		if (strncmp(ifrp->ifr_name, "dummy", 5) == 0)
242 			continue;
243 
244 		/*
245 		 * Get the flags for this interface, and skip it if it's
246 		 * not up.
247 		 */
248 		strncpy(ifrflags.ifr_name, ifrp->ifr_name,
249 		    sizeof(ifrflags.ifr_name));
250 		if (ioctl(fd, SIOCGIFFLAGS, (char *)&ifrflags) < 0) {
251 			if (errno == ENXIO)
252 				continue;
253 			(void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
254 			    "SIOCGIFFLAGS: %.*s: %s",
255 			    (int)sizeof(ifrflags.ifr_name),
256 			    ifrflags.ifr_name,
257 			    pcap_strerror(errno));
258 			ret = -1;
259 			break;
260 		}
261 		if (!(ifrflags.ifr_flags & IFF_UP))
262 			continue;
263 
264 		/*
265 		 * Get the netmask for this address on this interface.
266 		 */
267 		strncpy(ifrnetmask.ifr_name, ifrp->ifr_name,
268 		    sizeof(ifrnetmask.ifr_name));
269 		memcpy(&ifrnetmask.ifr_addr, &ifrp->ifr_addr,
270 		    sizeof(ifrnetmask.ifr_addr));
271 		if (ioctl(fd, SIOCGIFNETMASK, (char *)&ifrnetmask) < 0) {
272 			if (errno == EADDRNOTAVAIL) {
273 				/*
274 				 * Not available.
275 				 */
276 				netmask = NULL;
277 				netmask_size = 0;
278 			} else {
279 				(void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
280 				    "SIOCGIFNETMASK: %.*s: %s",
281 				    (int)sizeof(ifrnetmask.ifr_name),
282 				    ifrnetmask.ifr_name,
283 				    pcap_strerror(errno));
284 				ret = -1;
285 				break;
286 			}
287 		} else {
288 			netmask = &ifrnetmask.ifr_addr;
289 			netmask_size = SA_LEN(netmask);
290 		}
291 
292 		/*
293 		 * Get the broadcast address for this address on this
294 		 * interface (if any).
295 		 */
296 		if (ifrflags.ifr_flags & IFF_BROADCAST) {
297 			strncpy(ifrbroadaddr.ifr_name, ifrp->ifr_name,
298 			    sizeof(ifrbroadaddr.ifr_name));
299 			memcpy(&ifrbroadaddr.ifr_addr, &ifrp->ifr_addr,
300 			    sizeof(ifrbroadaddr.ifr_addr));
301 			if (ioctl(fd, SIOCGIFBRDADDR,
302 			    (char *)&ifrbroadaddr) < 0) {
303 				if (errno == EADDRNOTAVAIL) {
304 					/*
305 					 * Not available.
306 					 */
307 					broadaddr = NULL;
308 					broadaddr_size = 0;
309 				} else {
310 					(void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
311 					    "SIOCGIFBRDADDR: %.*s: %s",
312 					    (int)sizeof(ifrbroadaddr.ifr_name),
313 					    ifrbroadaddr.ifr_name,
314 					    pcap_strerror(errno));
315 					ret = -1;
316 					break;
317 				}
318 			} else {
319 				broadaddr = &ifrbroadaddr.ifr_broadaddr;
320 				broadaddr_size = SA_LEN(broadaddr);
321 			}
322 		} else {
323 			/*
324 			 * Not a broadcast interface, so no broadcast
325 			 * address.
326 			 */
327 			broadaddr = NULL;
328 			broadaddr_size = 0;
329 		}
330 
331 		/*
332 		 * Get the destination address for this address on this
333 		 * interface (if any).
334 		 */
335 		if (ifrflags.ifr_flags & IFF_POINTOPOINT) {
336 			strncpy(ifrdstaddr.ifr_name, ifrp->ifr_name,
337 			    sizeof(ifrdstaddr.ifr_name));
338 			memcpy(&ifrdstaddr.ifr_addr, &ifrp->ifr_addr,
339 			    sizeof(ifrdstaddr.ifr_addr));
340 			if (ioctl(fd, SIOCGIFDSTADDR,
341 			    (char *)&ifrdstaddr) < 0) {
342 				if (errno == EADDRNOTAVAIL) {
343 					/*
344 					 * Not available.
345 					 */
346 					dstaddr = NULL;
347 					dstaddr_size = 0;
348 				} else {
349 					(void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
350 					    "SIOCGIFDSTADDR: %.*s: %s",
351 					    (int)sizeof(ifrdstaddr.ifr_name),
352 					    ifrdstaddr.ifr_name,
353 					    pcap_strerror(errno));
354 					ret = -1;
355 					break;
356 				}
357 			} else {
358 				dstaddr = &ifrdstaddr.ifr_dstaddr;
359 				dstaddr_size = SA_LEN(dstaddr);
360 			}
361 		} else {
362 			/*
363 			 * Not a point-to-point interface, so no destination
364 			 * address.
365 			 */
366 			dstaddr = NULL;
367 			dstaddr_size = 0;
368 		}
369 
370 #if defined (HAVE_SOLARIS) || defined (HAVE_HPUX10_20_OR_LATER)
371 		/*
372 		 * If this entry has a colon followed by a number at
373 		 * the end, it's a logical interface.  Those are just
374 		 * the way you assign multiple IP addresses to a real
375 		 * interface, so an entry for a logical interface should
376 		 * be treated like the entry for the real interface;
377 		 * we do that by stripping off the ":" and the number.
378 		 */
379 		p = strchr(ifrp->ifr_name, ':');
380 		if (p != NULL) {
381 			/*
382 			 * We have a ":"; is it followed by a number?
383 			 */
384 			q = p + 1;
385 			while (isdigit((unsigned char)*q))
386 				q++;
387 			if (*q == '\0') {
388 				/*
389 				 * All digits after the ":" until the end.
390 				 * Strip off the ":" and everything after
391 				 * it.
392 				 */
393 				*p = '\0';
394 			}
395 		}
396 #endif
397 
398 		/*
399 		 * Add information for this address to the list.
400 		 */
401 		if (add_addr_to_iflist(&devlist, ifrp->ifr_name,
402 		    ifrflags.ifr_flags, &ifrp->ifr_addr,
403 		    SA_LEN(&ifrp->ifr_addr), netmask, netmask_size,
404 		    broadaddr, broadaddr_size, dstaddr, dstaddr_size,
405 		    errbuf) < 0) {
406 			ret = -1;
407 			break;
408 		}
409 	}
410 	free(buf);
411 	(void)close(fd);
412 
413 	if (ret == -1) {
414 		/*
415 		 * We had an error; free the list we've been constructing.
416 		 */
417 		if (devlist != NULL) {
418 			pcap_freealldevs(devlist);
419 			devlist = NULL;
420 		}
421 	}
422 
423 	*alldevsp = devlist;
424 	return (ret);
425 }
426