The Tcpdump Group git mirrors - libpcap/blob - fad-gifc.c

   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.
 137  */
 138 int
 139 pcap_findalldevs(pcap_if_t **alldevsp, char *errbuf)
 140 {
 141         pcap_if_t *devlist = NULL;
 142         register int fd;
 143         register struct ifreq *ifrp, *ifend, *ifnext;
 144         int n;
 145         struct ifconf ifc;
 146         char *buf = NULL;
 147         unsigned buf_size;
 148 #if defined (HAVE_SOLARIS) || defined (HAVE_HPUX10_20_OR_LATER)
 149         char *p, *q;
 150 #endif
 151         struct ifreq ifrflags, ifrnetmask, ifrbroadaddr, ifrdstaddr;
 152         struct sockaddr *netmask, *broadaddr, *dstaddr;
 153         size_t netmask_size, broadaddr_size, dstaddr_size;
 154         int ret = 0;
 155
 156         /*
 157          * Create a socket from which to fetch the list of interfaces.
 158          */
 159         fd = socket(AF_INET, SOCK_DGRAM, 0);
 160         if (fd < 0) {
 161                 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 162                     "socket: %s", pcap_strerror(errno));
 163                 return (-1);
 164         }
 165
 166         /*
 167          * Start with an 8K buffer, and keep growing the buffer until
 168          * we have more than "sizeof(ifrp->ifr_name) + MAX_SA_LEN"
 169          * bytes left over in the buffer or we fail to get the
 170          * interface list for some reason other than EINVAL (which is
 171          * presumed here to mean "buffer is too small").
 172          */
 173         buf_size = 8192;
 174         for (;;) {
 175                 buf = malloc(buf_size);
 176                 if (buf == NULL) {
 177                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 178                             "malloc: %s", pcap_strerror(errno));
 179                         (void)close(fd);
 180                         return (-1);
 181                 }
 182
 183                 ifc.ifc_len = buf_size;
 184                 ifc.ifc_buf = buf;
 185                 memset(buf, 0, buf_size);
 186                 if (ioctl(fd, SIOCGIFCONF, (char *)&ifc) < 0
 187                     && errno != EINVAL) {
 188                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 189                             "SIOCGIFCONF: %s", pcap_strerror(errno));
 190                         (void)close(fd);
 191                         free(buf);
 192                         return (-1);
 193                 }
 194                 if (ifc.ifc_len < buf_size &&
 195                     (buf_size - ifc.ifc_len) > sizeof(ifrp->ifr_name) + MAX_SA_LEN)
 196                         break;
 197                 free(buf);
 198                 buf_size *= 2;
 199         }
 200
 201         ifrp = (struct ifreq *)buf;
 202         ifend = (struct ifreq *)(buf + ifc.ifc_len);
 203
 204         for (; ifrp < ifend; ifrp = ifnext) {
 205                 /*
 206                  * XXX - what if this isn't an IPv4 address?  Can
 207                  * we still get the netmask, etc. with ioctls on
 208                  * an IPv4 socket?
 209                  *
 210                  * The answer is probably platform-dependent, and
 211                  * if the answer is "no" on more than one platform,
 212                  * the way you work around it is probably platform-
 213                  * dependent as well.
 214                  */
 215                 n = SA_LEN(&ifrp->ifr_addr) + sizeof(ifrp->ifr_name);
 216                 if (n < sizeof(*ifrp))
 217                         ifnext = ifrp + 1;
 218                 else
 219                         ifnext = (struct ifreq *)((char *)ifrp + n);
 220
 221                 /*
 222                  * XXX - The 32-bit compatibility layer for Linux on IA-64
 223                  * is slightly broken. It correctly converts the structures
 224                  * to and from kernel land from 64 bit to 32 bit but
 225                  * doesn't update ifc.ifc_len, leaving it larger than the
 226                  * amount really used. This means we read off the end
 227                  * of the buffer and encounter an interface with an
 228                  * "empty" name. Since this is highly unlikely to ever
 229                  * occur in a valid case we can just finish looking for
 230                  * interfaces if we see an empty name.
 231                  */
 232                 if (!(*ifrp->ifr_name))
 233                         break;
 234
 235                 /*
 236                  * Skip entries that begin with "dummy".
 237                  * XXX - what are these?  Is this Linux-specific?
 238                  * Are there platforms on which we shouldn't do this?
 239                  */
 240                 if (strncmp(ifrp->ifr_name, "dummy", 5) == 0)
 241                         continue;
 242
 243                 /*
 244                  * Get the flags for this interface, and skip it if it's
 245                  * not up.
 246                  */
 247                 strncpy(ifrflags.ifr_name, ifrp->ifr_name,
 248                     sizeof(ifrflags.ifr_name));
 249                 if (ioctl(fd, SIOCGIFFLAGS, (char *)&ifrflags) < 0) {
 250                         if (errno == ENXIO)
 251                                 continue;
 252                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 253                             "SIOCGIFFLAGS: %.*s: %s",
 254                             (int)sizeof(ifrflags.ifr_name),
 255                             ifrflags.ifr_name,
 256                             pcap_strerror(errno));
 257                         ret = -1;
 258                         break;
 259                 }
 260                 if (!(ifrflags.ifr_flags & IFF_UP))
 261                         continue;
 262
 263                 /*
 264                  * Get the netmask for this address on this interface.
 265                  */
 266                 strncpy(ifrnetmask.ifr_name, ifrp->ifr_name,
 267                     sizeof(ifrnetmask.ifr_name));
 268                 memcpy(&ifrnetmask.ifr_addr, &ifrp->ifr_addr,
 269                     sizeof(ifrnetmask.ifr_addr));
 270                 if (ioctl(fd, SIOCGIFNETMASK, (char *)&ifrnetmask) < 0) {
 271                         if (errno == EADDRNOTAVAIL) {
 272                                 /*
 273                                  * Not available.
 274                                  */
 275                                 netmask = NULL;
 276                                 netmask_size = 0;
 277                         } else {
 278                                 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 279                                     "SIOCGIFNETMASK: %.*s: %s",
 280                                     (int)sizeof(ifrnetmask.ifr_name),
 281                                     ifrnetmask.ifr_name,
 282                                     pcap_strerror(errno));
 283                                 ret = -1;
 284                                 break;
 285                         }
 286                 } else {
 287                         netmask = &ifrnetmask.ifr_addr;
 288                         netmask_size = SA_LEN(netmask);
 289                 }
 290
 291                 /*
 292                  * Get the broadcast address for this address on this
 293                  * interface (if any).
 294                  */
 295                 if (ifrflags.ifr_flags & IFF_BROADCAST) {
 296                         strncpy(ifrbroadaddr.ifr_name, ifrp->ifr_name,
 297                             sizeof(ifrbroadaddr.ifr_name));
 298                         memcpy(&ifrbroadaddr.ifr_addr, &ifrp->ifr_addr,
 299                             sizeof(ifrbroadaddr.ifr_addr));
 300                         if (ioctl(fd, SIOCGIFBRDADDR,
 301                             (char *)&ifrbroadaddr) < 0) {
 302                                 if (errno == EADDRNOTAVAIL) {
 303                                         /*
 304                                          * Not available.
 305                                          */
 306                                         broadaddr = NULL;
 307                                         broadaddr_size = 0;
 308                                 } else {
 309                                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 310                                             "SIOCGIFBRDADDR: %.*s: %s",
 311                                             (int)sizeof(ifrbroadaddr.ifr_name),
 312                                             ifrbroadaddr.ifr_name,
 313                                             pcap_strerror(errno));
 314                                         ret = -1;
 315                                         break;
 316                                 }
 317                         } else {
 318                                 broadaddr = &ifrbroadaddr.ifr_broadaddr;
 319                                 broadaddr_size = SA_LEN(broadaddr);
 320                         }
 321                 } else {
 322                         /*
 323                          * Not a broadcast interface, so no broadcast
 324                          * address.
 325                          */
 326                         broadaddr = NULL;
 327                         broadaddr_size = 0;
 328                 }
 329
 330                 /*
 331                  * Get the destination address for this address on this
 332                  * interface (if any).
 333                  */
 334                 if (ifrflags.ifr_flags & IFF_POINTOPOINT) {
 335                         strncpy(ifrdstaddr.ifr_name, ifrp->ifr_name,
 336                             sizeof(ifrdstaddr.ifr_name));
 337                         memcpy(&ifrdstaddr.ifr_addr, &ifrp->ifr_addr,
 338                             sizeof(ifrdstaddr.ifr_addr));
 339                         if (ioctl(fd, SIOCGIFDSTADDR,
 340                             (char *)&ifrdstaddr) < 0) {
 341                                 if (errno == EADDRNOTAVAIL) {
 342                                         /*
 343                                          * Not available.
 344                                          */
 345                                         dstaddr = NULL;
 346                                         dstaddr_size = 0;
 347                                 } else {
 348                                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 349                                             "SIOCGIFDSTADDR: %.*s: %s",
 350                                             (int)sizeof(ifrdstaddr.ifr_name),
 351                                             ifrdstaddr.ifr_name,
 352                                             pcap_strerror(errno));
 353                                         ret = -1;
 354                                         break;
 355                                 }
 356                         } else {
 357                                 dstaddr = &ifrdstaddr.ifr_dstaddr;
 358                                 dstaddr_size = SA_LEN(dstaddr);
 359                         }
 360                 } else {
 361                         /*
 362                          * Not a point-to-point interface, so no destination
 363                          * address.
 364                          */
 365                         dstaddr = NULL;
 366                         dstaddr_size = 0;
 367                 }
 368
 369 #if defined (HAVE_SOLARIS) || defined (HAVE_HPUX10_20_OR_LATER)
 370                 /*
 371                  * If this entry has a colon followed by a number at
 372                  * the end, it's a logical interface.  Those are just
 373                  * the way you assign multiple IP addresses to a real
 374                  * interface, so an entry for a logical interface should
 375                  * be treated like the entry for the real interface;
 376                  * we do that by stripping off the ":" and the number.
 377                  */
 378                 p = strchr(ifrp->ifr_name, ':');
 379                 if (p != NULL) {
 380                         /*
 381                          * We have a ":"; is it followed by a number?
 382                          */
 383                         q = p + 1;
 384                         while (isdigit((unsigned char)*q))
 385                                 q++;
 386                         if (*q == '\0') {
 387                                 /*
 388                                  * All digits after the ":" until the end.
 389                                  * Strip off the ":" and everything after
 390                                  * it.
 391                                  */
 392                                 *p = '\0';
 393                         }
 394                 }
 395 #endif
 396
 397                 /*
 398                  * Add information for this address to the list.
 399                  */
 400                 if (add_addr_to_iflist(&devlist, ifrp->ifr_name,
 401                     ifrflags.ifr_flags, &ifrp->ifr_addr,
 402                     SA_LEN(&ifrp->ifr_addr), netmask, netmask_size,
 403                     broadaddr, broadaddr_size, dstaddr, dstaddr_size,
 404                     errbuf) < 0) {
 405                         ret = -1;
 406                         break;
 407                 }
 408         }
 409         free(buf);
 410         (void)close(fd);
 411
 412         if (ret != -1) {
 413                 /*
 414                  * We haven't had any errors yet; do any platform-specific
 415                  * operations to add devices.
 416                  */
 417                 if (pcap_platform_finddevs(&devlist, errbuf) < 0)
 418                         ret = -1;
 419         }
 420
 421         if (ret == -1) {
 422                 /*
 423                  * We had an error; free the list we've been constructing.
 424                  */
 425                 if (devlist != NULL) {
 426                         pcap_freealldevs(devlist);
 427                         devlist = NULL;
 428                 }
 429         }
 430
 431         *alldevsp = devlist;
 432         return (ret);
 433 }