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