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
  41 #include <net/if.h>
  42 #include <netinet/in.h>
  43
  44 #include <errno.h>
  45 #include <memory.h>
  46 #include <stdio.h>
  47 #include <stdlib.h>
  48 #include <string.h>
  49 #include <unistd.h>
  50 #include <limits.h>
  51
  52 #include "pcap-int.h"
  53
  54 #ifdef HAVE_OS_PROTO_H
  55 #include "os-proto.h"
  56 #endif
  57
  58 /*
  59  * This is fun.
  60  *
  61  * In older BSD systems, socket addresses were fixed-length, and
  62  * "sizeof (struct sockaddr)" gave the size of the structure.
  63  * All addresses fit within a "struct sockaddr".
  64  *
  65  * In newer BSD systems, the socket address is variable-length, and
  66  * there's an "sa_len" field giving the length of the structure;
  67  * this allows socket addresses to be longer than 2 bytes of family
  68  * and 14 bytes of data.
  69  *
  70  * Some commercial UNIXes use the old BSD scheme, some use the RFC 2553
  71  * variant of the old BSD scheme (with "struct sockaddr_storage" rather
  72  * than "struct sockaddr"), and some use the new BSD scheme.
  73  *
  74  * Some versions of GNU libc use neither scheme, but has an "SA_LEN()"
  75  * macro that determines the size based on the address family.  Other
  76  * versions don't have "SA_LEN()" (as it was in drafts of RFC 2553
  77  * but not in the final version).
  78  *
  79  * We assume that a UNIX that doesn't have "getifaddrs()" and doesn't have
  80  * SIOCGLIFCONF, but has SIOCGIFCONF, uses "struct sockaddr" for the
  81  * address in an entry returned by SIOCGIFCONF.
  82  *
  83  * OSes that use this file are:
  84  * - AIX 7 (SA_LEN() is not defined, HAVE_STRUCT_SOCKADDR_SA_LEN is defined)
  85  * - HP-UX 11 (HAVE_STRUCT_SOCKADDR_SA_LEN is not defined)
  86  */
  87 #ifndef SA_LEN
  88 #ifdef HAVE_STRUCT_SOCKADDR_SA_LEN
  89 #define SA_LEN(addr)    ((addr)->sa_len)
  90 #else /* HAVE_STRUCT_SOCKADDR_SA_LEN */
  91 #define SA_LEN(addr)    (sizeof (struct sockaddr))
  92 #endif /* HAVE_STRUCT_SOCKADDR_SA_LEN */
  93 #endif /* SA_LEN */
  94
  95 /*
  96  * This is also fun.
  97  *
  98  * There is no ioctl that returns the amount of space required for all
  99  * the data that SIOCGIFCONF could return, and if a buffer is supplied
 100  * that's not large enough for all the data SIOCGIFCONF could return,
 101  * on at least some platforms it just returns the data that'd fit with
 102  * no indication that there wasn't enough room for all the data, much
 103  * less an indication of how much more room is required.
 104  *
 105  * The only way to ensure that we got all the data is to pass a buffer
 106  * large enough that the amount of space in the buffer *not* filled in
 107  * is greater than the largest possible entry.
 108  *
 109  * We assume that's "sizeof(ifreq.ifr_name)" plus 255, under the assumption
 110  * that no address is more than 255 bytes (on systems where the "sa_len"
 111  * field in a "struct sockaddr" is 1 byte, e.g. newer BSDs, that's the
 112  * case, and addresses are unlikely to be bigger than that in any case).
 113  */
 114 #define MAX_SA_LEN      255
 115
 116 /*
 117  * Get a list of all interfaces that are up and that we can open.
 118  * Returns -1 on error, 0 otherwise.
 119  * The list, as returned through "alldevsp", may be null if no interfaces
 120  * were up and could be opened.
 121  *
 122  * This is the implementation used on platforms that have SIOCGIFCONF but
 123  * don't have any other mechanism for getting a list of interfaces.
 124  *
 125  * XXX - or platforms that have other, better mechanisms but for which
 126  * we don't yet have code to use that mechanism; I think there's a better
 127  * way on Linux, for example, but if that better way is "getifaddrs()",
 128  * we already have that.
 129  */
 130 int
 131 pcapint_findalldevs_interfaces(pcap_if_list_t *devlistp, char *errbuf,
 132     int (*check_usable)(const char *), get_if_flags_func get_flags_func)
 133 {
 134         register int fd;
 135         register struct ifreq *ifrp, *ifend, *ifnext;
 136         size_t n;
 137         struct ifconf ifc;
 138         char *buf = NULL;
 139         unsigned buf_size;
 140 #if defined (HAVE_SOLARIS) || defined (HAVE_HPUX10_20_OR_LATER)
 141         char *p, *q;
 142 #endif
 143         struct ifreq ifrflags, ifrnetmask, ifrbroadaddr, ifrdstaddr;
 144         struct sockaddr *netmask, *broadaddr, *dstaddr;
 145         size_t netmask_size, broadaddr_size, dstaddr_size;
 146         int ret = 0;
 147
 148         /*
 149          * Create a socket from which to fetch the list of interfaces.
 150          */
 151         fd = socket(AF_INET, SOCK_DGRAM, 0);
 152         if (fd < 0) {
 153                 pcapint_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
 154                     errno, "socket");
 155                 return (-1);
 156         }
 157
 158         /*
 159          * Start with an 8K buffer, and keep growing the buffer until
 160          * we have more than "sizeof(ifrp->ifr_name) + MAX_SA_LEN"
 161          * bytes left over in the buffer or we fail to get the
 162          * interface list for some reason other than EINVAL (which is
 163          * presumed here to mean "buffer is too small").
 164          */
 165         buf_size = 8192;
 166         for (;;) {
 167                 /*
 168                  * Don't let the buffer size get bigger than INT_MAX.
 169                  */
 170                 if (buf_size > INT_MAX) {
 171                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 172                             "interface information requires more than %u bytes",
 173                             INT_MAX);
 174                         (void)close(fd);
 175                         return (-1);
 176                 }
 177                 buf = malloc(buf_size);
 178                 if (buf == NULL) {
 179                         pcapint_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
 180                             errno, "malloc");
 181                         (void)close(fd);
 182                         return (-1);
 183                 }
 184
 185                 ifc.ifc_len = buf_size;
 186                 ifc.ifc_buf = buf;
 187                 memset(buf, 0, buf_size);
 188                 if (ioctl(fd, SIOCGIFCONF, (char *)&ifc) < 0
 189                     && errno != EINVAL) {
 190                         pcapint_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
 191                             errno, "SIOCGIFCONF");
 192                         (void)close(fd);
 193                         free(buf);
 194                         return (-1);
 195                 }
 196                 if (ifc.ifc_len < (int)buf_size &&
 197                     (buf_size - ifc.ifc_len) > sizeof(ifrp->ifr_name) + MAX_SA_LEN)
 198                         break;
 199                 free(buf);
 200                 buf_size *= 2;
 201         }
 202
 203         ifrp = (struct ifreq *)buf;
 204         ifend = (struct ifreq *)(buf + ifc.ifc_len);
 205
 206         for (; ifrp < ifend; ifrp = ifnext) {
 207                 /*
 208                  * XXX - what if this isn't an IPv4 address?  Can
 209                  * we still get the netmask, etc. with ioctls on
 210                  * an IPv4 socket?
 211                  *
 212                  * The answer is probably platform-dependent, and
 213                  * if the answer is "no" on more than one platform,
 214                  * the way you work around it is probably platform-
 215                  * dependent as well.
 216                  */
 217                 n = SA_LEN(&ifrp->ifr_addr) + sizeof(ifrp->ifr_name);
 218                 if (n < sizeof(*ifrp))
 219                         ifnext = ifrp + 1;
 220                 else
 221                         ifnext = (struct ifreq *)((char *)ifrp + n);
 222
 223                 /*
 224                  * XXX - The 32-bit compatibility layer for Linux on IA-64
 225                  * is slightly broken. It correctly converts the structures
 226                  * to and from kernel land from 64 bit to 32 bit but
 227                  * doesn't update ifc.ifc_len, leaving it larger than the
 228                  * amount really used. This means we read off the end
 229                  * of the buffer and encounter an interface with an
 230                  * "empty" name. Since this is highly unlikely to ever
 231                  * occur in a valid case we can just finish looking for
 232                  * interfaces if we see an empty name.
 233                  */
 234                 if (!(*ifrp->ifr_name))
 235                         break;
 236
 237                 /*
 238                  * Can we capture on this device?
 239                  */
 240                 if (!(*check_usable)(ifrp->ifr_name)) {
 241                         /*
 242                          * No.
 243                          */
 244                         continue;
 245                 }
 246
 247                 /*
 248                  * Get the flags for this interface.
 249                  */
 250                 pcapint_strlcpy(ifrflags.ifr_name, ifrp->ifr_name,
 251                     sizeof(ifrflags.ifr_name));
 252                 if (ioctl(fd, SIOCGIFFLAGS, (char *)&ifrflags) < 0) {
 253                         if (errno == ENXIO)
 254                                 continue;
 255                         pcapint_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
 256                             errno, "SIOCGIFFLAGS: %.*s",
 257                             (int)sizeof(ifrflags.ifr_name),
 258                             ifrflags.ifr_name);
 259                         ret = -1;
 260                         break;
 261                 }
 262
 263                 /*
 264                  * Get the netmask for this address on this interface.
 265                  */
 266                 pcapint_strlcpy(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                                 pcapint_fmt_errmsg_for_errno(errbuf,
 279                                     PCAP_ERRBUF_SIZE, errno,
 280                                     "SIOCGIFNETMASK: %.*s",
 281                                     (int)sizeof(ifrnetmask.ifr_name),
 282                                     ifrnetmask.ifr_name);
 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                         pcapint_strlcpy(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                                         pcapint_fmt_errmsg_for_errno(errbuf,
 310                                             PCAP_ERRBUF_SIZE, errno,
 311                                             "SIOCGIFBRDADDR: %.*s",
 312                                             (int)sizeof(ifrbroadaddr.ifr_name),
 313                                             ifrbroadaddr.ifr_name);
 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                         pcapint_strlcpy(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                                         pcapint_fmt_errmsg_for_errno(errbuf,
 349                                             PCAP_ERRBUF_SIZE, errno,
 350                                             "SIOCGIFDSTADDR: %.*s",
 351                                             (int)sizeof(ifrdstaddr.ifr_name),
 352                                             ifrdstaddr.ifr_name);
 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 (PCAP_ISDIGIT(*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 (pcapint_add_addr_to_if(devlistp, ifrp->ifr_name,
 401                     ifrflags.ifr_flags, get_flags_func,
 402                     &ifrp->ifr_addr, SA_LEN(&ifrp->ifr_addr),
 403                     netmask, netmask_size, broadaddr, broadaddr_size,
 404                     dstaddr, dstaddr_size, errbuf) < 0) {
 405                         ret = -1;
 406                         break;
 407                 }
 408         }
 409         free(buf);
 410         (void)close(fd);
 411
 412         return (ret);
 413 }