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 #include <config.h>
  36
  37 #include <sys/param.h>
  38 #include <sys/ioctl.h>
  39 #include <sys/socket.h>
  40 #ifdef HAVE_SYS_SOCKIO_H
  41 #include <sys/sockio.h>
  42 #endif
  43
  44 #include <net/if.h>
  45 #include <netinet/in.h>
  46
  47 #include <errno.h>
  48 #include <memory.h>
  49 #include <stdio.h>
  50 #include <stdlib.h>
  51 #include <string.h>
  52 #include <unistd.h>
  53 #include <limits.h>
  54
  55 #include "pcap-int.h"
  56
  57 #ifdef HAVE_OS_PROTO_H
  58 #include "os-proto.h"
  59 #endif
  60
  61 /*
  62  * This is fun.
  63  *
  64  * In older BSD systems, socket addresses were fixed-length, and
  65  * "sizeof (struct sockaddr)" gave the size of the structure.
  66  * All addresses fit within a "struct sockaddr".
  67  *
  68  * In newer BSD systems, the socket address is variable-length, and
  69  * there's an "sa_len" field giving the length of the structure;
  70  * this allows socket addresses to be longer than 2 bytes of family
  71  * and 14 bytes of data.
  72  *
  73  * Some commercial UNIXes use the old BSD scheme, some use the RFC 2553
  74  * variant of the old BSD scheme (with "struct sockaddr_storage" rather
  75  * than "struct sockaddr"), and some use the new BSD scheme.
  76  *
  77  * Some versions of GNU libc use neither scheme, but has an "SA_LEN()"
  78  * macro that determines the size based on the address family.  Other
  79  * versions don't have "SA_LEN()" (as it was in drafts of RFC 2553
  80  * but not in the final version).
  81  *
  82  * We assume that a UNIX that doesn't have "getifaddrs()" and doesn't have
  83  * SIOCGLIFCONF, but has SIOCGIFCONF, uses "struct sockaddr" for the
  84  * address in an entry returned by SIOCGIFCONF.
  85  *
  86  * OSes that use this file are:
  87  * - AIX 7 (SA_LEN() is not defined, HAVE_STRUCT_SOCKADDR_SA_LEN is defined)
  88  * - HP-UX 11 (HAVE_STRUCT_SOCKADDR_SA_LEN is not defined)
  89  */
  90 #ifndef SA_LEN
  91 #ifdef HAVE_STRUCT_SOCKADDR_SA_LEN
  92 #define SA_LEN(addr)    ((addr)->sa_len)
  93 #else /* HAVE_STRUCT_SOCKADDR_SA_LEN */
  94 #define SA_LEN(addr)    (sizeof (struct sockaddr))
  95 #endif /* HAVE_STRUCT_SOCKADDR_SA_LEN */
  96 #endif /* SA_LEN */
  97
  98 /*
  99  * This is also fun.
 100  *
 101  * There is no ioctl that returns the amount of space required for all
 102  * the data that SIOCGIFCONF could return, and if a buffer is supplied
 103  * that's not large enough for all the data SIOCGIFCONF could return,
 104  * on at least some platforms it just returns the data that'd fit with
 105  * no indication that there wasn't enough room for all the data, much
 106  * less an indication of how much more room is required.
 107  *
 108  * The only way to ensure that we got all the data is to pass a buffer
 109  * large enough that the amount of space in the buffer *not* filled in
 110  * is greater than the largest possible entry.
 111  *
 112  * We assume that's "sizeof(ifreq.ifr_name)" plus 255, under the assumption
 113  * that no address is more than 255 bytes (on systems where the "sa_len"
 114  * field in a "struct sockaddr" is 1 byte, e.g. newer BSDs, that's the
 115  * case, and addresses are unlikely to be bigger than that in any case).
 116  */
 117 #define MAX_SA_LEN      255
 118
 119 /*
 120  * Get a list of all interfaces that are up and that we can open.
 121  * Returns -1 on error, 0 otherwise.
 122  * The list, as returned through "alldevsp", may be null if no interfaces
 123  * were up and could be opened.
 124  *
 125  * This is the implementation used on platforms that have SIOCGIFCONF but
 126  * don't have any other mechanism for getting a list of interfaces.
 127  *
 128  * XXX - or platforms that have other, better mechanisms but for which
 129  * we don't yet have code to use that mechanism; I think there's a better
 130  * way on Linux, for example, but if that better way is "getifaddrs()",
 131  * we already have that.
 132  */
 133 int
 134 pcapint_findalldevs_interfaces(pcap_if_list_t *devlistp, char *errbuf,
 135     int (*check_usable)(const char *), get_if_flags_func get_flags_func)
 136 {
 137         register int fd;
 138         register struct ifreq *ifrp, *ifend, *ifnext;
 139         size_t n;
 140         struct ifconf ifc;
 141         char *buf = NULL;
 142         unsigned buf_size;
 143 #if defined (HAVE_SOLARIS) || defined (HAVE_HPUX10_20_OR_LATER)
 144         char *p, *q;
 145 #endif
 146         struct ifreq ifrflags, ifrnetmask, ifrbroadaddr, ifrdstaddr;
 147         struct sockaddr *netmask, *broadaddr, *dstaddr;
 148         size_t netmask_size, broadaddr_size, dstaddr_size;
 149         int ret = 0;
 150
 151         /*
 152          * Create a socket from which to fetch the list of interfaces.
 153          */
 154         fd = socket(AF_INET, SOCK_DGRAM, 0);
 155         if (fd < 0) {
 156                 pcapint_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
 157                     errno, "socket");
 158                 return (-1);
 159         }
 160
 161         /*
 162          * Start with an 8K buffer, and keep growing the buffer until
 163          * we have more than "sizeof(ifrp->ifr_name) + MAX_SA_LEN"
 164          * bytes left over in the buffer or we fail to get the
 165          * interface list for some reason other than EINVAL (which is
 166          * presumed here to mean "buffer is too small").
 167          */
 168         buf_size = 8192;
 169         for (;;) {
 170                 /*
 171                  * Don't let the buffer size get bigger than INT_MAX.
 172                  */
 173                 if (buf_size > INT_MAX) {
 174                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 175                             "interface information requires more than %u bytes",
 176                             INT_MAX);
 177                         (void)close(fd);
 178                         return (-1);
 179                 }
 180                 buf = malloc(buf_size);
 181                 if (buf == NULL) {
 182                         pcapint_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
 183                             errno, "malloc");
 184                         (void)close(fd);
 185                         return (-1);
 186                 }
 187
 188                 ifc.ifc_len = buf_size;
 189                 ifc.ifc_buf = buf;
 190                 memset(buf, 0, buf_size);
 191                 if (ioctl(fd, SIOCGIFCONF, (char *)&ifc) < 0
 192                     && errno != EINVAL) {
 193                         pcapint_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
 194                             errno, "SIOCGIFCONF");
 195                         (void)close(fd);
 196                         free(buf);
 197                         return (-1);
 198                 }
 199                 if (ifc.ifc_len < (int)buf_size &&
 200                     (buf_size - ifc.ifc_len) > sizeof(ifrp->ifr_name) + MAX_SA_LEN)
 201                         break;
 202                 free(buf);
 203                 buf_size *= 2;
 204         }
 205
 206         ifrp = (struct ifreq *)buf;
 207         ifend = (struct ifreq *)(buf + ifc.ifc_len);
 208
 209         for (; ifrp < ifend; ifrp = ifnext) {
 210                 /*
 211                  * XXX - what if this isn't an IPv4 address?  Can
 212                  * we still get the netmask, etc. with ioctls on
 213                  * an IPv4 socket?
 214                  *
 215                  * The answer is probably platform-dependent, and
 216                  * if the answer is "no" on more than one platform,
 217                  * the way you work around it is probably platform-
 218                  * dependent as well.
 219                  */
 220                 n = SA_LEN(&ifrp->ifr_addr) + sizeof(ifrp->ifr_name);
 221                 if (n < sizeof(*ifrp))
 222                         ifnext = ifrp + 1;
 223                 else
 224                         ifnext = (struct ifreq *)((char *)ifrp + n);
 225
 226                 /*
 227                  * XXX - The 32-bit compatibility layer for Linux on IA-64
 228                  * is slightly broken. It correctly converts the structures
 229                  * to and from kernel land from 64 bit to 32 bit but
 230                  * doesn't update ifc.ifc_len, leaving it larger than the
 231                  * amount really used. This means we read off the end
 232                  * of the buffer and encounter an interface with an
 233                  * "empty" name. Since this is highly unlikely to ever
 234                  * occur in a valid case we can just finish looking for
 235                  * interfaces if we see an empty name.
 236                  */
 237                 if (!(*ifrp->ifr_name))
 238                         break;
 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                 pcapint_strlcpy(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                         pcapint_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
 259                             errno, "SIOCGIFFLAGS: %.*s",
 260                             (int)sizeof(ifrflags.ifr_name),
 261                             ifrflags.ifr_name);
 262                         ret = -1;
 263                         break;
 264                 }
 265
 266                 /*
 267                  * Get the netmask for this address on this interface.
 268                  */
 269                 pcapint_strlcpy(ifrnetmask.ifr_name, ifrp->ifr_name,
 270                     sizeof(ifrnetmask.ifr_name));
 271                 memcpy(&ifrnetmask.ifr_addr, &ifrp->ifr_addr,
 272                     sizeof(ifrnetmask.ifr_addr));
 273                 if (ioctl(fd, SIOCGIFNETMASK, (char *)&ifrnetmask) < 0) {
 274                         if (errno == EADDRNOTAVAIL) {
 275                                 /*
 276                                  * Not available.
 277                                  */
 278                                 netmask = NULL;
 279                                 netmask_size = 0;
 280                         } else {
 281                                 pcapint_fmt_errmsg_for_errno(errbuf,
 282                                     PCAP_ERRBUF_SIZE, errno,
 283                                     "SIOCGIFNETMASK: %.*s",
 284                                     (int)sizeof(ifrnetmask.ifr_name),
 285                                     ifrnetmask.ifr_name);
 286                                 ret = -1;
 287                                 break;
 288                         }
 289                 } else {
 290                         netmask = &ifrnetmask.ifr_addr;
 291                         netmask_size = SA_LEN(netmask);
 292                 }
 293
 294                 /*
 295                  * Get the broadcast address for this address on this
 296                  * interface (if any).
 297                  */
 298                 if (ifrflags.ifr_flags & IFF_BROADCAST) {
 299                         pcapint_strlcpy(ifrbroadaddr.ifr_name, ifrp->ifr_name,
 300                             sizeof(ifrbroadaddr.ifr_name));
 301                         memcpy(&ifrbroadaddr.ifr_addr, &ifrp->ifr_addr,
 302                             sizeof(ifrbroadaddr.ifr_addr));
 303                         if (ioctl(fd, SIOCGIFBRDADDR,
 304                             (char *)&ifrbroadaddr) < 0) {
 305                                 if (errno == EADDRNOTAVAIL) {
 306                                         /*
 307                                          * Not available.
 308                                          */
 309                                         broadaddr = NULL;
 310                                         broadaddr_size = 0;
 311                                 } else {
 312                                         pcapint_fmt_errmsg_for_errno(errbuf,
 313                                             PCAP_ERRBUF_SIZE, errno,
 314                                             "SIOCGIFBRDADDR: %.*s",
 315                                             (int)sizeof(ifrbroadaddr.ifr_name),
 316                                             ifrbroadaddr.ifr_name);
 317                                         ret = -1;
 318                                         break;
 319                                 }
 320                         } else {
 321                                 broadaddr = &ifrbroadaddr.ifr_broadaddr;
 322                                 broadaddr_size = SA_LEN(broadaddr);
 323                         }
 324                 } else {
 325                         /*
 326                          * Not a broadcast interface, so no broadcast
 327                          * address.
 328                          */
 329                         broadaddr = NULL;
 330                         broadaddr_size = 0;
 331                 }
 332
 333                 /*
 334                  * Get the destination address for this address on this
 335                  * interface (if any).
 336                  */
 337                 if (ifrflags.ifr_flags & IFF_POINTOPOINT) {
 338                         pcapint_strlcpy(ifrdstaddr.ifr_name, ifrp->ifr_name,
 339                             sizeof(ifrdstaddr.ifr_name));
 340                         memcpy(&ifrdstaddr.ifr_addr, &ifrp->ifr_addr,
 341                             sizeof(ifrdstaddr.ifr_addr));
 342                         if (ioctl(fd, SIOCGIFDSTADDR,
 343                             (char *)&ifrdstaddr) < 0) {
 344                                 if (errno == EADDRNOTAVAIL) {
 345                                         /*
 346                                          * Not available.
 347                                          */
 348                                         dstaddr = NULL;
 349                                         dstaddr_size = 0;
 350                                 } else {
 351                                         pcapint_fmt_errmsg_for_errno(errbuf,
 352                                             PCAP_ERRBUF_SIZE, errno,
 353                                             "SIOCGIFDSTADDR: %.*s",
 354                                             (int)sizeof(ifrdstaddr.ifr_name),
 355                                             ifrdstaddr.ifr_name);
 356                                         ret = -1;
 357                                         break;
 358                                 }
 359                         } else {
 360                                 dstaddr = &ifrdstaddr.ifr_dstaddr;
 361                                 dstaddr_size = SA_LEN(dstaddr);
 362                         }
 363                 } else {
 364                         /*
 365                          * Not a point-to-point interface, so no destination
 366                          * address.
 367                          */
 368                         dstaddr = NULL;
 369                         dstaddr_size = 0;
 370                 }
 371
 372 #if defined (HAVE_SOLARIS) || defined (HAVE_HPUX10_20_OR_LATER)
 373                 /*
 374                  * If this entry has a colon followed by a number at
 375                  * the end, it's a logical interface.  Those are just
 376                  * the way you assign multiple IP addresses to a real
 377                  * interface, so an entry for a logical interface should
 378                  * be treated like the entry for the real interface;
 379                  * we do that by stripping off the ":" and the number.
 380                  */
 381                 p = strchr(ifrp->ifr_name, ':');
 382                 if (p != NULL) {
 383                         /*
 384                          * We have a ":"; is it followed by a number?
 385                          */
 386                         q = p + 1;
 387                         while (PCAP_ISDIGIT(*q))
 388                                 q++;
 389                         if (*q == '\0') {
 390                                 /*
 391                                  * All digits after the ":" until the end.
 392                                  * Strip off the ":" and everything after
 393                                  * it.
 394                                  */
 395                                 *p = '\0';
 396                         }
 397                 }
 398 #endif
 399
 400                 /*
 401                  * Add information for this address to the list.
 402                  */
 403                 if (pcapint_add_addr_to_if(devlistp, ifrp->ifr_name,
 404                     ifrflags.ifr_flags, get_flags_func,
 405                     &ifrp->ifr_addr, SA_LEN(&ifrp->ifr_addr),
 406                     netmask, netmask_size, broadaddr, broadaddr_size,
 407                     dstaddr, dstaddr_size, errbuf) < 0) {
 408                         ret = -1;
 409                         break;
 410                 }
 411         }
 412         free(buf);
 413         (void)close(fd);
 414
 415         return (ret);
 416 }