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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 #ifdef HAVE_CONFIG_H
36 #include "config.h"
37 #endif
38 
39 #include <sys/param.h>
40 #include <sys/ioctl.h>
41 #include <sys/socket.h>
42 #ifdef HAVE_SYS_SOCKIO_H
43 #include <sys/sockio.h>
44 #endif
45 #include <sys/time.h>				/* concession to AIX */
46 
47 struct mbuf;		/* Squelch compiler warnings on some platforms for */
48 struct rtentry;		/* declarations in <net/if.h> */
49 #include <net/if.h>
50 #include <netinet/in.h>
51 
52 #include <ctype.h>
53 #include <errno.h>
54 #include <memory.h>
55 #include <stdio.h>
56 #include <stdlib.h>
57 #include <string.h>
58 #include <unistd.h>
59 
60 #include "pcap-int.h"
61 
62 #ifdef HAVE_OS_PROTO_H
63 #include "os-proto.h"
64 #endif
65 
66 /*
67  * This is fun.
68  *
69  * In older BSD systems, socket addresses were fixed-length, and
70  * "sizeof (struct sockaddr)" gave the size of the structure.
71  * All addresses fit within a "struct sockaddr".
72  *
73  * In newer BSD systems, the socket address is variable-length, and
74  * there's an "sa_len" field giving the length of the structure;
75  * this allows socket addresses to be longer than 2 bytes of family
76  * and 14 bytes of data.
77  *
78  * Some commercial UNIXes use the old BSD scheme, some use the RFC 2553
79  * variant of the old BSD scheme (with "struct sockaddr_storage" rather
80  * than "struct sockaddr"), and some use the new BSD scheme.
81  *
82  * Some versions of GNU libc use neither scheme, but has an "SA_LEN()"
83  * macro that determines the size based on the address family.  Other
84  * versions don't have "SA_LEN()" (as it was in drafts of RFC 2553
85  * but not in the final version).
86  *
87  * We assume that a UNIX that doesn't have "getifaddrs()" and doesn't have
88  * SIOCGLIFCONF, but has SIOCGIFCONF, uses "struct sockaddr" for the
89  * address in an entry returned by SIOCGIFCONF.
90  */
91 #ifndef SA_LEN
92 #ifdef HAVE_SOCKADDR_SA_LEN
93 #define SA_LEN(addr)	((addr)->sa_len)
94 #else /* HAVE_SOCKADDR_SA_LEN */
95 #define SA_LEN(addr)	(sizeof (struct sockaddr))
96 #endif /* HAVE_SOCKADDR_SA_LEN */
97 #endif /* SA_LEN */
98 
99 /*
100  * This is also fun.
101  *
102  * There is no ioctl that returns the amount of space required for all
103  * the data that SIOCGIFCONF could return, and if a buffer is supplied
104  * that's not large enough for all the data SIOCGIFCONF could return,
105  * on at least some platforms it just returns the data that'd fit with
106  * no indication that there wasn't enough room for all the data, much
107  * less an indication of how much more room is required.
108  *
109  * The only way to ensure that we got all the data is to pass a buffer
110  * large enough that the amount of space in the buffer *not* filled in
111  * is greater than the largest possible entry.
112  *
113  * We assume that's "sizeof(ifreq.ifr_name)" plus 255, under the assumption
114  * that no address is more than 255 bytes (on systems where the "sa_len"
115  * field in a "struct sockaddr" is 1 byte, e.g. newer BSDs, that's the
116  * case, and addresses are unlikely to be bigger than that in any case).
117  */
118 #define MAX_SA_LEN	255
119 
120 /*
121  * Get a list of all interfaces that are up and that we can open.
122  * Returns -1 on error, 0 otherwise.
123  * The list, as returned through "alldevsp", may be null if no interfaces
124  * were up and could be opened.
125  *
126  * This is the implementation used on platforms that have SIOCGIFCONF but
127  * don't have any other mechanism for getting a list of interfaces.
128  *
129  * XXX - or platforms that have other, better mechanisms but for which
130  * we don't yet have code to use that mechanism; I think there's a better
131  * way on Linux, for example, but if that better way is "getifaddrs()",
132  * we already have that.
133  */
134 int
pcap_findalldevs_interfaces(pcap_if_t ** alldevsp,char * errbuf,int (* check_usable)(const char *))135 pcap_findalldevs_interfaces(pcap_if_t **alldevsp, char *errbuf,
136     int (*check_usable)(const char *))
137 {
138 	pcap_if_t *devlist = NULL;
139 	register int fd;
140 	register struct ifreq *ifrp, *ifend, *ifnext;
141 	size_t n;
142 	struct ifconf ifc;
143 	char *buf = NULL;
144 	unsigned buf_size;
145 #if defined (HAVE_SOLARIS) || defined (HAVE_HPUX10_20_OR_LATER)
146 	char *p, *q;
147 #endif
148 	struct ifreq ifrflags, ifrnetmask, ifrbroadaddr, ifrdstaddr;
149 	struct sockaddr *netmask, *broadaddr, *dstaddr;
150 	size_t netmask_size, broadaddr_size, dstaddr_size;
151 	int ret = 0;
152 
153 	/*
154 	 * Create a socket from which to fetch the list of interfaces.
155 	 */
156 	fd = socket(AF_INET, SOCK_DGRAM, 0);
157 	if (fd < 0) {
158 		(void)pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
159 		    "socket: %s", pcap_strerror(errno));
160 		return (-1);
161 	}
162 
163 	/*
164 	 * Start with an 8K buffer, and keep growing the buffer until
165 	 * we have more than "sizeof(ifrp->ifr_name) + MAX_SA_LEN"
166 	 * bytes left over in the buffer or we fail to get the
167 	 * interface list for some reason other than EINVAL (which is
168 	 * presumed here to mean "buffer is too small").
169 	 */
170 	buf_size = 8192;
171 	for (;;) {
172 		buf = malloc(buf_size);
173 		if (buf == NULL) {
174 			(void)pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
175 			    "malloc: %s", pcap_strerror(errno));
176 			(void)close(fd);
177 			return (-1);
178 		}
179 
180 		ifc.ifc_len = buf_size;
181 		ifc.ifc_buf = buf;
182 		memset(buf, 0, buf_size);
183 		if (ioctl(fd, SIOCGIFCONF, (char *)&ifc) < 0
184 		    && errno != EINVAL) {
185 			(void)pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
186 			    "SIOCGIFCONF: %s", pcap_strerror(errno));
187 			(void)close(fd);
188 			free(buf);
189 			return (-1);
190 		}
191 		if (ifc.ifc_len < buf_size &&
192 		    (buf_size - ifc.ifc_len) > sizeof(ifrp->ifr_name) + MAX_SA_LEN)
193 			break;
194 		free(buf);
195 		buf_size *= 2;
196 	}
197 
198 	ifrp = (struct ifreq *)buf;
199 	ifend = (struct ifreq *)(buf + ifc.ifc_len);
200 
201 	for (; ifrp < ifend; ifrp = ifnext) {
202 		/*
203 		 * XXX - what if this isn't an IPv4 address?  Can
204 		 * we still get the netmask, etc. with ioctls on
205 		 * an IPv4 socket?
206 		 *
207 		 * The answer is probably platform-dependent, and
208 		 * if the answer is "no" on more than one platform,
209 		 * the way you work around it is probably platform-
210 		 * dependent as well.
211 		 */
212 		n = SA_LEN(&ifrp->ifr_addr) + sizeof(ifrp->ifr_name);
213 		if (n < sizeof(*ifrp))
214 			ifnext = ifrp + 1;
215 		else
216 			ifnext = (struct ifreq *)((char *)ifrp + n);
217 
218 		/*
219 		 * XXX - The 32-bit compatibility layer for Linux on IA-64
220 		 * is slightly broken. It correctly converts the structures
221 		 * to and from kernel land from 64 bit to 32 bit but
222 		 * doesn't update ifc.ifc_len, leaving it larger than the
223 		 * amount really used. This means we read off the end
224 		 * of the buffer and encounter an interface with an
225 		 * "empty" name. Since this is highly unlikely to ever
226 		 * occur in a valid case we can just finish looking for
227 		 * interfaces if we see an empty name.
228 		 */
229 		if (!(*ifrp->ifr_name))
230 			break;
231 
232 		/*
233 		 * Skip entries that begin with "dummy".
234 		 * XXX - what are these?  Is this Linux-specific?
235 		 * Are there platforms on which we shouldn't do this?
236 		 */
237 		if (strncmp(ifrp->ifr_name, "dummy", 5) == 0)
238 			continue;
239 
240 		/*
241 		 * Can we capture on this device?
242 		 */
243 		if (!(*check_usable)(ifrp->ifr_name)) {
244 			/*
245 			 * No.
246 			 */
247 			continue;
248 		}
249 
250 		/*
251 		 * Get the flags for this interface.
252 		 */
253 		strncpy(ifrflags.ifr_name, ifrp->ifr_name,
254 		    sizeof(ifrflags.ifr_name));
255 		if (ioctl(fd, SIOCGIFFLAGS, (char *)&ifrflags) < 0) {
256 			if (errno == ENXIO)
257 				continue;
258 			(void)pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
259 			    "SIOCGIFFLAGS: %.*s: %s",
260 			    (int)sizeof(ifrflags.ifr_name),
261 			    ifrflags.ifr_name,
262 			    pcap_strerror(errno));
263 			ret = -1;
264 			break;
265 		}
266 
267 		/*
268 		 * Get the netmask for this address on this interface.
269 		 */
270 		strncpy(ifrnetmask.ifr_name, ifrp->ifr_name,
271 		    sizeof(ifrnetmask.ifr_name));
272 		memcpy(&ifrnetmask.ifr_addr, &ifrp->ifr_addr,
273 		    sizeof(ifrnetmask.ifr_addr));
274 		if (ioctl(fd, SIOCGIFNETMASK, (char *)&ifrnetmask) < 0) {
275 			if (errno == EADDRNOTAVAIL) {
276 				/*
277 				 * Not available.
278 				 */
279 				netmask = NULL;
280 				netmask_size = 0;
281 			} else {
282 				(void)pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
283 				    "SIOCGIFNETMASK: %.*s: %s",
284 				    (int)sizeof(ifrnetmask.ifr_name),
285 				    ifrnetmask.ifr_name,
286 				    pcap_strerror(errno));
287 				ret = -1;
288 				break;
289 			}
290 		} else {
291 			netmask = &ifrnetmask.ifr_addr;
292 			netmask_size = SA_LEN(netmask);
293 		}
294 
295 		/*
296 		 * Get the broadcast address for this address on this
297 		 * interface (if any).
298 		 */
299 		if (ifrflags.ifr_flags & IFF_BROADCAST) {
300 			strncpy(ifrbroadaddr.ifr_name, ifrp->ifr_name,
301 			    sizeof(ifrbroadaddr.ifr_name));
302 			memcpy(&ifrbroadaddr.ifr_addr, &ifrp->ifr_addr,
303 			    sizeof(ifrbroadaddr.ifr_addr));
304 			if (ioctl(fd, SIOCGIFBRDADDR,
305 			    (char *)&ifrbroadaddr) < 0) {
306 				if (errno == EADDRNOTAVAIL) {
307 					/*
308 					 * Not available.
309 					 */
310 					broadaddr = NULL;
311 					broadaddr_size = 0;
312 				} else {
313 					(void)pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
314 					    "SIOCGIFBRDADDR: %.*s: %s",
315 					    (int)sizeof(ifrbroadaddr.ifr_name),
316 					    ifrbroadaddr.ifr_name,
317 					    pcap_strerror(errno));
318 					ret = -1;
319 					break;
320 				}
321 			} else {
322 				broadaddr = &ifrbroadaddr.ifr_broadaddr;
323 				broadaddr_size = SA_LEN(broadaddr);
324 			}
325 		} else {
326 			/*
327 			 * Not a broadcast interface, so no broadcast
328 			 * address.
329 			 */
330 			broadaddr = NULL;
331 			broadaddr_size = 0;
332 		}
333 
334 		/*
335 		 * Get the destination address for this address on this
336 		 * interface (if any).
337 		 */
338 		if (ifrflags.ifr_flags & IFF_POINTOPOINT) {
339 			strncpy(ifrdstaddr.ifr_name, ifrp->ifr_name,
340 			    sizeof(ifrdstaddr.ifr_name));
341 			memcpy(&ifrdstaddr.ifr_addr, &ifrp->ifr_addr,
342 			    sizeof(ifrdstaddr.ifr_addr));
343 			if (ioctl(fd, SIOCGIFDSTADDR,
344 			    (char *)&ifrdstaddr) < 0) {
345 				if (errno == EADDRNOTAVAIL) {
346 					/*
347 					 * Not available.
348 					 */
349 					dstaddr = NULL;
350 					dstaddr_size = 0;
351 				} else {
352 					(void)pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
353 					    "SIOCGIFDSTADDR: %.*s: %s",
354 					    (int)sizeof(ifrdstaddr.ifr_name),
355 					    ifrdstaddr.ifr_name,
356 					    pcap_strerror(errno));
357 					ret = -1;
358 					break;
359 				}
360 			} else {
361 				dstaddr = &ifrdstaddr.ifr_dstaddr;
362 				dstaddr_size = SA_LEN(dstaddr);
363 			}
364 		} else {
365 			/*
366 			 * Not a point-to-point interface, so no destination
367 			 * address.
368 			 */
369 			dstaddr = NULL;
370 			dstaddr_size = 0;
371 		}
372 
373 #if defined (HAVE_SOLARIS) || defined (HAVE_HPUX10_20_OR_LATER)
374 		/*
375 		 * If this entry has a colon followed by a number at
376 		 * the end, it's a logical interface.  Those are just
377 		 * the way you assign multiple IP addresses to a real
378 		 * interface, so an entry for a logical interface should
379 		 * be treated like the entry for the real interface;
380 		 * we do that by stripping off the ":" and the number.
381 		 */
382 		p = strchr(ifrp->ifr_name, ':');
383 		if (p != NULL) {
384 			/*
385 			 * We have a ":"; is it followed by a number?
386 			 */
387 			q = p + 1;
388 			while (isdigit((unsigned char)*q))
389 				q++;
390 			if (*q == '\0') {
391 				/*
392 				 * All digits after the ":" until the end.
393 				 * Strip off the ":" and everything after
394 				 * it.
395 				 */
396 				*p = '\0';
397 			}
398 		}
399 #endif
400 
401 		/*
402 		 * Add information for this address to the list.
403 		 */
404 		if (add_addr_to_iflist(&devlist, ifrp->ifr_name,
405 		    if_flags_to_pcap_flags(ifrp->ifr_name, ifrflags.ifr_flags),
406 		    &ifrp->ifr_addr, SA_LEN(&ifrp->ifr_addr),
407 		    netmask, netmask_size, broadaddr, broadaddr_size,
408 		    dstaddr, dstaddr_size, errbuf) < 0) {
409 			ret = -1;
410 			break;
411 		}
412 	}
413 	free(buf);
414 	(void)close(fd);
415 
416 	if (ret == -1) {
417 		/*
418 		 * We had an error; free the list we've been constructing.
419 		 */
420 		if (devlist != NULL) {
421 			pcap_freealldevs(devlist);
422 			devlist = NULL;
423 		}
424 	}
425 
426 	*alldevsp = devlist;
427 	return (ret);
428 }
429