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 #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 #ifdef HAVE_LIMITS_H
  61 #include <limits.h>
  62 #else
  63 #define INT_MAX         2147483647
  64 #endif
  65
  66 #include "pcap-int.h"
  67
  68 #ifdef HAVE_OS_PROTO_H
  69 #include "os-proto.h"
  70 #endif
  71
  72 /*
  73  * This is fun.
  74  *
  75  * In older BSD systems, socket addresses were fixed-length, and
  76  * "sizeof (struct sockaddr)" gave the size of the structure.
  77  * All addresses fit within a "struct sockaddr".
  78  *
  79  * In newer BSD systems, the socket address is variable-length, and
  80  * there's an "sa_len" field giving the length of the structure;
  81  * this allows socket addresses to be longer than 2 bytes of family
  82  * and 14 bytes of data.
  83  *
  84  * Some commercial UNIXes use the old BSD scheme, some use the RFC 2553
  85  * variant of the old BSD scheme (with "struct sockaddr_storage" rather
  86  * than "struct sockaddr"), and some use the new BSD scheme.
  87  *
  88  * Some versions of GNU libc use neither scheme, but has an "SA_LEN()"
  89  * macro that determines the size based on the address family.  Other
  90  * versions don't have "SA_LEN()" (as it was in drafts of RFC 2553
  91  * but not in the final version).
  92  *
  93  * We assume that a UNIX that doesn't have "getifaddrs()" and doesn't have
  94  * SIOCGLIFCONF, but has SIOCGIFCONF, uses "struct sockaddr" for the
  95  * address in an entry returned by SIOCGIFCONF.
  96  */
  97 #ifndef SA_LEN
  98 #ifdef HAVE_SOCKADDR_SA_LEN
  99 #define SA_LEN(addr)    ((addr)->sa_len)
 100 #else /* HAVE_SOCKADDR_SA_LEN */
 101 #define SA_LEN(addr)    (sizeof (struct sockaddr))
 102 #endif /* HAVE_SOCKADDR_SA_LEN */
 103 #endif /* SA_LEN */
 104
 105 /*
 106  * This is also fun.
 107  *
 108  * There is no ioctl that returns the amount of space required for all
 109  * the data that SIOCGIFCONF could return, and if a buffer is supplied
 110  * that's not large enough for all the data SIOCGIFCONF could return,
 111  * on at least some platforms it just returns the data that'd fit with
 112  * no indication that there wasn't enough room for all the data, much
 113  * less an indication of how much more room is required.
 114  *
 115  * The only way to ensure that we got all the data is to pass a buffer
 116  * large enough that the amount of space in the buffer *not* filled in
 117  * is greater than the largest possible entry.
 118  *
 119  * We assume that's "sizeof(ifreq.ifr_name)" plus 255, under the assumption
 120  * that no address is more than 255 bytes (on systems where the "sa_len"
 121  * field in a "struct sockaddr" is 1 byte, e.g. newer BSDs, that's the
 122  * case, and addresses are unlikely to be bigger than that in any case).
 123  */
 124 #define MAX_SA_LEN      255
 125
 126 /*
 127  * Get a list of all interfaces that are up and that we can open.
 128  * Returns -1 on error, 0 otherwise.
 129  * The list, as returned through "alldevsp", may be null if no interfaces
 130  * were up and could be opened.
 131  *
 132  * This is the implementation used on platforms that have SIOCGIFCONF but
 133  * don't have any other mechanism for getting a list of interfaces.
 134  *
 135  * XXX - or platforms that have other, better mechanisms but for which
 136  * we don't yet have code to use that mechanism; I think there's a better
 137  * way on Linux, for example, but if that better way is "getifaddrs()",
 138  * we already have that.
 139  */
 140 int
 141 pcap_findalldevs_interfaces(pcap_if_list_t *devlistp, char *errbuf,
 142     int (*check_usable)(const char *))
 143 {
 144         register int fd;
 145         register struct ifreq *ifrp, *ifend, *ifnext;
 146         size_t n;
 147         struct ifconf ifc;
 148         char *buf = NULL;
 149         unsigned buf_size;
 150 #if defined (HAVE_SOLARIS) || defined (HAVE_HPUX10_20_OR_LATER)
 151         char *p, *q;
 152 #endif
 153         struct ifreq ifrflags, ifrnetmask, ifrbroadaddr, ifrdstaddr;
 154         struct sockaddr *netmask, *broadaddr, *dstaddr;
 155         size_t netmask_size, broadaddr_size, dstaddr_size;
 156         int ret = 0;
 157
 158         /*
 159          * Create a socket from which to fetch the list of interfaces.
 160          */
 161         fd = socket(AF_INET, SOCK_DGRAM, 0);
 162         if (fd < 0) {
 163                 (void)pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
 164                     "socket: %s", pcap_strerror(errno));
 165                 return (-1);
 166         }
 167
 168         /*
 169          * Start with an 8K buffer, and keep growing the buffer until
 170          * we have more than "sizeof(ifrp->ifr_name) + MAX_SA_LEN"
 171          * bytes left over in the buffer or we fail to get the
 172          * interface list for some reason other than EINVAL (which is
 173          * presumed here to mean "buffer is too small").
 174          */
 175         buf_size = 8192;
 176         for (;;) {
 177                 /*
 178                  * Don't let the buffer size get bigger than INT_MAX.
 179                  */
 180                 if (buf_size > INT_MAX) {
 181                         (void)pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
 182                             "interface information requires more than %u bytes",
 183                             INT_MAX);
 184                         (void)close(fd);
 185                         return (-1);
 186                 }
 187                 buf = malloc(buf_size);
 188                 if (buf == NULL) {
 189                         (void)pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
 190                             "malloc: %s", pcap_strerror(errno));
 191                         (void)close(fd);
 192                         return (-1);
 193                 }
 194
 195                 ifc.ifc_len = buf_size;
 196                 ifc.ifc_buf = buf;
 197                 memset(buf, 0, buf_size);
 198                 if (ioctl(fd, SIOCGIFCONF, (char *)&ifc) < 0
 199                     && errno != EINVAL) {
 200                         (void)pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
 201                             "SIOCGIFCONF: %s", pcap_strerror(errno));
 202                         (void)close(fd);
 203                         free(buf);
 204                         return (-1);
 205                 }
 206                 if (ifc.ifc_len < (int)buf_size &&
 207                     (buf_size - ifc.ifc_len) > sizeof(ifrp->ifr_name) + MAX_SA_LEN)
 208                         break;
 209                 free(buf);
 210                 buf_size *= 2;
 211         }
 212
 213         ifrp = (struct ifreq *)buf;
 214         ifend = (struct ifreq *)(buf + ifc.ifc_len);
 215
 216         for (; ifrp < ifend; ifrp = ifnext) {
 217                 /*
 218                  * XXX - what if this isn't an IPv4 address?  Can
 219                  * we still get the netmask, etc. with ioctls on
 220                  * an IPv4 socket?
 221                  *
 222                  * The answer is probably platform-dependent, and
 223                  * if the answer is "no" on more than one platform,
 224                  * the way you work around it is probably platform-
 225                  * dependent as well.
 226                  */
 227                 n = SA_LEN(&ifrp->ifr_addr) + sizeof(ifrp->ifr_name);
 228                 if (n < sizeof(*ifrp))
 229                         ifnext = ifrp + 1;
 230                 else
 231                         ifnext = (struct ifreq *)((char *)ifrp + n);
 232
 233                 /*
 234                  * XXX - The 32-bit compatibility layer for Linux on IA-64
 235                  * is slightly broken. It correctly converts the structures
 236                  * to and from kernel land from 64 bit to 32 bit but
 237                  * doesn't update ifc.ifc_len, leaving it larger than the
 238                  * amount really used. This means we read off the end
 239                  * of the buffer and encounter an interface with an
 240                  * "empty" name. Since this is highly unlikely to ever
 241                  * occur in a valid case we can just finish looking for
 242                  * interfaces if we see an empty name.
 243                  */
 244                 if (!(*ifrp->ifr_name))
 245                         break;
 246
 247                 /*
 248                  * Skip entries that begin with "dummy".
 249                  * XXX - what are these?  Is this Linux-specific?
 250                  * Are there platforms on which we shouldn't do this?
 251                  */
 252                 if (strncmp(ifrp->ifr_name, "dummy", 5) == 0)
 253                         continue;
 254
 255                 /*
 256                  * Can we capture on this device?
 257                  */
 258                 if (!(*check_usable)(ifrp->ifr_name)) {
 259                         /*
 260                          * No.
 261                          */
 262                         continue;
 263                 }
 264
 265                 /*
 266                  * Get the flags for this interface.
 267                  */
 268                 strncpy(ifrflags.ifr_name, ifrp->ifr_name,
 269                     sizeof(ifrflags.ifr_name));
 270                 if (ioctl(fd, SIOCGIFFLAGS, (char *)&ifrflags) < 0) {
 271                         if (errno == ENXIO)
 272                                 continue;
 273                         (void)pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
 274                             "SIOCGIFFLAGS: %.*s: %s",
 275                             (int)sizeof(ifrflags.ifr_name),
 276                             ifrflags.ifr_name,
 277                             pcap_strerror(errno));
 278                         ret = -1;
 279                         break;
 280                 }
 281
 282                 /*
 283                  * Get the netmask for this address on this interface.
 284                  */
 285                 strncpy(ifrnetmask.ifr_name, ifrp->ifr_name,
 286                     sizeof(ifrnetmask.ifr_name));
 287                 memcpy(&ifrnetmask.ifr_addr, &ifrp->ifr_addr,
 288                     sizeof(ifrnetmask.ifr_addr));
 289                 if (ioctl(fd, SIOCGIFNETMASK, (char *)&ifrnetmask) < 0) {
 290                         if (errno == EADDRNOTAVAIL) {
 291                                 /*
 292                                  * Not available.
 293                                  */
 294                                 netmask = NULL;
 295                                 netmask_size = 0;
 296                         } else {
 297                                 (void)pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
 298                                     "SIOCGIFNETMASK: %.*s: %s",
 299                                     (int)sizeof(ifrnetmask.ifr_name),
 300                                     ifrnetmask.ifr_name,
 301                                     pcap_strerror(errno));
 302                                 ret = -1;
 303                                 break;
 304                         }
 305                 } else {
 306                         netmask = &ifrnetmask.ifr_addr;
 307                         netmask_size = SA_LEN(netmask);
 308                 }
 309
 310                 /*
 311                  * Get the broadcast address for this address on this
 312                  * interface (if any).
 313                  */
 314                 if (ifrflags.ifr_flags & IFF_BROADCAST) {
 315                         strncpy(ifrbroadaddr.ifr_name, ifrp->ifr_name,
 316                             sizeof(ifrbroadaddr.ifr_name));
 317                         memcpy(&ifrbroadaddr.ifr_addr, &ifrp->ifr_addr,
 318                             sizeof(ifrbroadaddr.ifr_addr));
 319                         if (ioctl(fd, SIOCGIFBRDADDR,
 320                             (char *)&ifrbroadaddr) < 0) {
 321                                 if (errno == EADDRNOTAVAIL) {
 322                                         /*
 323                                          * Not available.
 324                                          */
 325                                         broadaddr = NULL;
 326                                         broadaddr_size = 0;
 327                                 } else {
 328                                         (void)pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
 329                                             "SIOCGIFBRDADDR: %.*s: %s",
 330                                             (int)sizeof(ifrbroadaddr.ifr_name),
 331                                             ifrbroadaddr.ifr_name,
 332                                             pcap_strerror(errno));
 333                                         ret = -1;
 334                                         break;
 335                                 }
 336                         } else {
 337                                 broadaddr = &ifrbroadaddr.ifr_broadaddr;
 338                                 broadaddr_size = SA_LEN(broadaddr);
 339                         }
 340                 } else {
 341                         /*
 342                          * Not a broadcast interface, so no broadcast
 343                          * address.
 344                          */
 345                         broadaddr = NULL;
 346                         broadaddr_size = 0;
 347                 }
 348
 349                 /*
 350                  * Get the destination address for this address on this
 351                  * interface (if any).
 352                  */
 353                 if (ifrflags.ifr_flags & IFF_POINTOPOINT) {
 354                         strncpy(ifrdstaddr.ifr_name, ifrp->ifr_name,
 355                             sizeof(ifrdstaddr.ifr_name));
 356                         memcpy(&ifrdstaddr.ifr_addr, &ifrp->ifr_addr,
 357                             sizeof(ifrdstaddr.ifr_addr));
 358                         if (ioctl(fd, SIOCGIFDSTADDR,
 359                             (char *)&ifrdstaddr) < 0) {
 360                                 if (errno == EADDRNOTAVAIL) {
 361                                         /*
 362                                          * Not available.
 363                                          */
 364                                         dstaddr = NULL;
 365                                         dstaddr_size = 0;
 366                                 } else {
 367                                         (void)pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
 368                                             "SIOCGIFDSTADDR: %.*s: %s",
 369                                             (int)sizeof(ifrdstaddr.ifr_name),
 370                                             ifrdstaddr.ifr_name,
 371                                             pcap_strerror(errno));
 372                                         ret = -1;
 373                                         break;
 374                                 }
 375                         } else {
 376                                 dstaddr = &ifrdstaddr.ifr_dstaddr;
 377                                 dstaddr_size = SA_LEN(dstaddr);
 378                         }
 379                 } else {
 380                         /*
 381                          * Not a point-to-point interface, so no destination
 382                          * address.
 383                          */
 384                         dstaddr = NULL;
 385                         dstaddr_size = 0;
 386                 }
 387
 388 #if defined (HAVE_SOLARIS) || defined (HAVE_HPUX10_20_OR_LATER)
 389                 /*
 390                  * If this entry has a colon followed by a number at
 391                  * the end, it's a logical interface.  Those are just
 392                  * the way you assign multiple IP addresses to a real
 393                  * interface, so an entry for a logical interface should
 394                  * be treated like the entry for the real interface;
 395                  * we do that by stripping off the ":" and the number.
 396                  */
 397                 p = strchr(ifrp->ifr_name, ':');
 398                 if (p != NULL) {
 399                         /*
 400                          * We have a ":"; is it followed by a number?
 401                          */
 402                         q = p + 1;
 403                         while (isdigit((unsigned char)*q))
 404                                 q++;
 405                         if (*q == '\0') {
 406                                 /*
 407                                  * All digits after the ":" until the end.
 408                                  * Strip off the ":" and everything after
 409                                  * it.
 410                                  */
 411                                 *p = '\0';
 412                         }
 413                 }
 414 #endif
 415
 416                 /*
 417                  * Add information for this address to the list.
 418                  */
 419                 if (add_addr_to_if(devlistp, ifrp->ifr_name,
 420                     ifrflags.ifr_flags,
 421                     &ifrp->ifr_addr, SA_LEN(&ifrp->ifr_addr),
 422                     netmask, netmask_size, broadaddr, broadaddr_size,
 423                     dstaddr, dstaddr_size, errbuf) < 0) {
 424                         ret = -1;
 425                         break;
 426                 }
 427         }
 428         free(buf);
 429         (void)close(fd);
 430
 431         return (ret);
 432 }