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 <errno.h>
53 #include <memory.h>
54 #include <stdio.h>
55 #include <stdlib.h>
56 #include <string.h>
57 #include <unistd.h>
58 #include <limits.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_STRUCT_SOCKADDR_SA_LEN
93 #define SA_LEN(addr) ((addr)->sa_len)
94 #else /* HAVE_STRUCT_SOCKADDR_SA_LEN */
95 #define SA_LEN(addr) (sizeof (struct sockaddr))
96 #endif /* HAVE_STRUCT_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_list_t * devlistp,char * errbuf,int (* check_usable)(const char *),get_if_flags_func get_flags_func)135 pcap_findalldevs_interfaces(pcap_if_list_t *devlistp, char *errbuf,
136 int (*check_usable)(const char *), get_if_flags_func get_flags_func)
137 {
138 register int fd;
139 register struct ifreq *ifrp, *ifend, *ifnext;
140 size_t n;
141 struct ifconf ifc;
142 char *buf = NULL;
143 unsigned buf_size;
144 #if defined (HAVE_SOLARIS) || defined (HAVE_HPUX10_20_OR_LATER)
145 char *p, *q;
146 #endif
147 struct ifreq ifrflags, ifrnetmask, ifrbroadaddr, ifrdstaddr;
148 struct sockaddr *netmask, *broadaddr, *dstaddr;
149 size_t netmask_size, broadaddr_size, dstaddr_size;
150 int ret = 0;
151
152 /*
153 * Create a socket from which to fetch the list of interfaces.
154 */
155 fd = socket(AF_INET, SOCK_DGRAM, 0);
156 if (fd < 0) {
157 pcap_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
158 errno, "socket");
159 return (-1);
160 }
161
162 /*
163 * Start with an 8K buffer, and keep growing the buffer until
164 * we have more than "sizeof(ifrp->ifr_name) + MAX_SA_LEN"
165 * bytes left over in the buffer or we fail to get the
166 * interface list for some reason other than EINVAL (which is
167 * presumed here to mean "buffer is too small").
168 */
169 buf_size = 8192;
170 for (;;) {
171 /*
172 * Don't let the buffer size get bigger than INT_MAX.
173 */
174 if (buf_size > INT_MAX) {
175 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
176 "interface information requires more than %u bytes",
177 INT_MAX);
178 (void)close(fd);
179 return (-1);
180 }
181 buf = malloc(buf_size);
182 if (buf == NULL) {
183 pcap_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
184 errno, "malloc");
185 (void)close(fd);
186 return (-1);
187 }
188
189 ifc.ifc_len = buf_size;
190 ifc.ifc_buf = buf;
191 memset(buf, 0, buf_size);
192 if (ioctl(fd, SIOCGIFCONF, (char *)&ifc) < 0
193 && errno != EINVAL) {
194 pcap_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
195 errno, "SIOCGIFCONF");
196 (void)close(fd);
197 free(buf);
198 return (-1);
199 }
200 if (ifc.ifc_len < (int)buf_size &&
201 (buf_size - ifc.ifc_len) > sizeof(ifrp->ifr_name) + MAX_SA_LEN)
202 break;
203 free(buf);
204 buf_size *= 2;
205 }
206
207 ifrp = (struct ifreq *)buf;
208 ifend = (struct ifreq *)(buf + ifc.ifc_len);
209
210 for (; ifrp < ifend; ifrp = ifnext) {
211 /*
212 * XXX - what if this isn't an IPv4 address? Can
213 * we still get the netmask, etc. with ioctls on
214 * an IPv4 socket?
215 *
216 * The answer is probably platform-dependent, and
217 * if the answer is "no" on more than one platform,
218 * the way you work around it is probably platform-
219 * dependent as well.
220 */
221 n = SA_LEN(&ifrp->ifr_addr) + sizeof(ifrp->ifr_name);
222 if (n < sizeof(*ifrp))
223 ifnext = ifrp + 1;
224 else
225 ifnext = (struct ifreq *)((char *)ifrp + n);
226
227 /*
228 * XXX - The 32-bit compatibility layer for Linux on IA-64
229 * is slightly broken. It correctly converts the structures
230 * to and from kernel land from 64 bit to 32 bit but
231 * doesn't update ifc.ifc_len, leaving it larger than the
232 * amount really used. This means we read off the end
233 * of the buffer and encounter an interface with an
234 * "empty" name. Since this is highly unlikely to ever
235 * occur in a valid case we can just finish looking for
236 * interfaces if we see an empty name.
237 */
238 if (!(*ifrp->ifr_name))
239 break;
240
241 /*
242 * Skip entries that begin with "dummy".
243 * XXX - what are these? Is this Linux-specific?
244 * Are there platforms on which we shouldn't do this?
245 */
246 if (strncmp(ifrp->ifr_name, "dummy", 5) == 0)
247 continue;
248
249 /*
250 * Can we capture on this device?
251 */
252 if (!(*check_usable)(ifrp->ifr_name)) {
253 /*
254 * No.
255 */
256 continue;
257 }
258
259 /*
260 * Get the flags for this interface.
261 */
262 strncpy(ifrflags.ifr_name, ifrp->ifr_name,
263 sizeof(ifrflags.ifr_name));
264 if (ioctl(fd, SIOCGIFFLAGS, (char *)&ifrflags) < 0) {
265 if (errno == ENXIO)
266 continue;
267 pcap_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
268 errno, "SIOCGIFFLAGS: %.*s",
269 (int)sizeof(ifrflags.ifr_name),
270 ifrflags.ifr_name);
271 ret = -1;
272 break;
273 }
274
275 /*
276 * Get the netmask for this address on this interface.
277 */
278 strncpy(ifrnetmask.ifr_name, ifrp->ifr_name,
279 sizeof(ifrnetmask.ifr_name));
280 memcpy(&ifrnetmask.ifr_addr, &ifrp->ifr_addr,
281 sizeof(ifrnetmask.ifr_addr));
282 if (ioctl(fd, SIOCGIFNETMASK, (char *)&ifrnetmask) < 0) {
283 if (errno == EADDRNOTAVAIL) {
284 /*
285 * Not available.
286 */
287 netmask = NULL;
288 netmask_size = 0;
289 } else {
290 pcap_fmt_errmsg_for_errno(errbuf,
291 PCAP_ERRBUF_SIZE, errno,
292 "SIOCGIFNETMASK: %.*s",
293 (int)sizeof(ifrnetmask.ifr_name),
294 ifrnetmask.ifr_name);
295 ret = -1;
296 break;
297 }
298 } else {
299 netmask = &ifrnetmask.ifr_addr;
300 netmask_size = SA_LEN(netmask);
301 }
302
303 /*
304 * Get the broadcast address for this address on this
305 * interface (if any).
306 */
307 if (ifrflags.ifr_flags & IFF_BROADCAST) {
308 strncpy(ifrbroadaddr.ifr_name, ifrp->ifr_name,
309 sizeof(ifrbroadaddr.ifr_name));
310 memcpy(&ifrbroadaddr.ifr_addr, &ifrp->ifr_addr,
311 sizeof(ifrbroadaddr.ifr_addr));
312 if (ioctl(fd, SIOCGIFBRDADDR,
313 (char *)&ifrbroadaddr) < 0) {
314 if (errno == EADDRNOTAVAIL) {
315 /*
316 * Not available.
317 */
318 broadaddr = NULL;
319 broadaddr_size = 0;
320 } else {
321 pcap_fmt_errmsg_for_errno(errbuf,
322 PCAP_ERRBUF_SIZE, errno,
323 "SIOCGIFBRDADDR: %.*s",
324 (int)sizeof(ifrbroadaddr.ifr_name),
325 ifrbroadaddr.ifr_name);
326 ret = -1;
327 break;
328 }
329 } else {
330 broadaddr = &ifrbroadaddr.ifr_broadaddr;
331 broadaddr_size = SA_LEN(broadaddr);
332 }
333 } else {
334 /*
335 * Not a broadcast interface, so no broadcast
336 * address.
337 */
338 broadaddr = NULL;
339 broadaddr_size = 0;
340 }
341
342 /*
343 * Get the destination address for this address on this
344 * interface (if any).
345 */
346 if (ifrflags.ifr_flags & IFF_POINTOPOINT) {
347 strncpy(ifrdstaddr.ifr_name, ifrp->ifr_name,
348 sizeof(ifrdstaddr.ifr_name));
349 memcpy(&ifrdstaddr.ifr_addr, &ifrp->ifr_addr,
350 sizeof(ifrdstaddr.ifr_addr));
351 if (ioctl(fd, SIOCGIFDSTADDR,
352 (char *)&ifrdstaddr) < 0) {
353 if (errno == EADDRNOTAVAIL) {
354 /*
355 * Not available.
356 */
357 dstaddr = NULL;
358 dstaddr_size = 0;
359 } else {
360 pcap_fmt_errmsg_for_errno(errbuf,
361 PCAP_ERRBUF_SIZE, errno,
362 "SIOCGIFDSTADDR: %.*s",
363 (int)sizeof(ifrdstaddr.ifr_name),
364 ifrdstaddr.ifr_name);
365 ret = -1;
366 break;
367 }
368 } else {
369 dstaddr = &ifrdstaddr.ifr_dstaddr;
370 dstaddr_size = SA_LEN(dstaddr);
371 }
372 } else {
373 /*
374 * Not a point-to-point interface, so no destination
375 * address.
376 */
377 dstaddr = NULL;
378 dstaddr_size = 0;
379 }
380
381 #if defined (HAVE_SOLARIS) || defined (HAVE_HPUX10_20_OR_LATER)
382 /*
383 * If this entry has a colon followed by a number at
384 * the end, it's a logical interface. Those are just
385 * the way you assign multiple IP addresses to a real
386 * interface, so an entry for a logical interface should
387 * be treated like the entry for the real interface;
388 * we do that by stripping off the ":" and the number.
389 */
390 p = strchr(ifrp->ifr_name, ':');
391 if (p != NULL) {
392 /*
393 * We have a ":"; is it followed by a number?
394 */
395 q = p + 1;
396 while (PCAP_ISDIGIT(*q))
397 q++;
398 if (*q == '\0') {
399 /*
400 * All digits after the ":" until the end.
401 * Strip off the ":" and everything after
402 * it.
403 */
404 *p = '\0';
405 }
406 }
407 #endif
408
409 /*
410 * Add information for this address to the list.
411 */
412 if (add_addr_to_if(devlistp, ifrp->ifr_name,
413 ifrflags.ifr_flags, get_flags_func,
414 &ifrp->ifr_addr, SA_LEN(&ifrp->ifr_addr),
415 netmask, netmask_size, broadaddr, broadaddr_size,
416 dstaddr, dstaddr_size, errbuf) < 0) {
417 ret = -1;
418 break;
419 }
420 }
421 free(buf);
422 (void)close(fd);
423
424 return (ret);
425 }
426