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 <errno.h>
  53 #include <memory.h>
  54 #include <stdio.h>
  55 #include <stdlib.h>
  56 #include <string.h>
  57 #include <unistd.h>
  58 #include <limits.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_STRUCT_SOCKADDR_SA_LEN
  93 #define SA_LEN(addr)    ((addr)->sa_len)
  94 #else /* HAVE_STRUCT_SOCKADDR_SA_LEN */
  95 #define SA_LEN(addr)    (sizeof (struct sockaddr))
  96 #endif /* HAVE_STRUCT_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_list_t *devlistp, char *errbuf,
 136     int (*check_usable)(const char *), get_if_flags_func get_flags_func)
 137 {
 138         register int fd;
 139         register struct ifreq *ifrp, *ifend, *ifnext;
 140         size_t 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                 pcap_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
 158                     errno, "socket");
 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                 /*
 172                  * Don't let the buffer size get bigger than INT_MAX.
 173                  */
 174                 if (buf_size > INT_MAX) {
 175                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 176                             "interface information requires more than %u bytes",
 177                             INT_MAX);
 178                         (void)close(fd);
 179                         return (-1);
 180                 }
 181                 buf = malloc(buf_size);
 182                 if (buf == NULL) {
 183                         pcap_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
 184                             errno, "malloc");
 185                         (void)close(fd);
 186                         return (-1);
 187                 }
 188
 189                 ifc.ifc_len = buf_size;
 190                 ifc.ifc_buf = buf;
 191                 memset(buf, 0, buf_size);
 192                 if (ioctl(fd, SIOCGIFCONF, (char *)&ifc) < 0
 193                     && errno != EINVAL) {
 194                         pcap_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
 195                             errno, "SIOCGIFCONF");
 196                         (void)close(fd);
 197                         free(buf);
 198                         return (-1);
 199                 }
 200                 if (ifc.ifc_len < (int)buf_size &&
 201                     (buf_size - ifc.ifc_len) > sizeof(ifrp->ifr_name) + MAX_SA_LEN)
 202                         break;
 203                 free(buf);
 204                 buf_size *= 2;
 205         }
 206
 207         ifrp = (struct ifreq *)buf;
 208         ifend = (struct ifreq *)(buf + ifc.ifc_len);
 209
 210         for (; ifrp < ifend; ifrp = ifnext) {
 211                 /*
 212                  * XXX - what if this isn't an IPv4 address?  Can
 213                  * we still get the netmask, etc. with ioctls on
 214                  * an IPv4 socket?
 215                  *
 216                  * The answer is probably platform-dependent, and
 217                  * if the answer is "no" on more than one platform,
 218                  * the way you work around it is probably platform-
 219                  * dependent as well.
 220                  */
 221                 n = SA_LEN(&ifrp->ifr_addr) + sizeof(ifrp->ifr_name);
 222                 if (n < sizeof(*ifrp))
 223                         ifnext = ifrp + 1;
 224                 else
 225                         ifnext = (struct ifreq *)((char *)ifrp + n);
 226
 227                 /*
 228                  * XXX - The 32-bit compatibility layer for Linux on IA-64
 229                  * is slightly broken. It correctly converts the structures
 230                  * to and from kernel land from 64 bit to 32 bit but
 231                  * doesn't update ifc.ifc_len, leaving it larger than the
 232                  * amount really used. This means we read off the end
 233                  * of the buffer and encounter an interface with an
 234                  * "empty" name. Since this is highly unlikely to ever
 235                  * occur in a valid case we can just finish looking for
 236                  * interfaces if we see an empty name.
 237                  */
 238                 if (!(*ifrp->ifr_name))
 239                         break;
 240
 241                 /*
 242                  * Skip entries that begin with "dummy".
 243                  * XXX - what are these?  Is this Linux-specific?
 244                  * Are there platforms on which we shouldn't do this?
 245                  */
 246                 if (strncmp(ifrp->ifr_name, "dummy", 5) == 0)
 247                         continue;
 248
 249                 /*
 250                  * Can we capture on this device?
 251                  */
 252                 if (!(*check_usable)(ifrp->ifr_name)) {
 253                         /*
 254                          * No.
 255                          */
 256                         continue;
 257                 }
 258
 259                 /*
 260                  * Get the flags for this interface.
 261                  */
 262                 strncpy(ifrflags.ifr_name, ifrp->ifr_name,
 263                     sizeof(ifrflags.ifr_name));
 264                 if (ioctl(fd, SIOCGIFFLAGS, (char *)&ifrflags) < 0) {
 265                         if (errno == ENXIO)
 266                                 continue;
 267                         pcap_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
 268                             errno, "SIOCGIFFLAGS: %.*s",
 269                             (int)sizeof(ifrflags.ifr_name),
 270                             ifrflags.ifr_name);
 271                         ret = -1;
 272                         break;
 273                 }
 274
 275                 /*
 276                  * Get the netmask for this address on this interface.
 277                  */
 278                 strncpy(ifrnetmask.ifr_name, ifrp->ifr_name,
 279                     sizeof(ifrnetmask.ifr_name));
 280                 memcpy(&ifrnetmask.ifr_addr, &ifrp->ifr_addr,
 281                     sizeof(ifrnetmask.ifr_addr));
 282                 if (ioctl(fd, SIOCGIFNETMASK, (char *)&ifrnetmask) < 0) {
 283                         if (errno == EADDRNOTAVAIL) {
 284                                 /*
 285                                  * Not available.
 286                                  */
 287                                 netmask = NULL;
 288                                 netmask_size = 0;
 289                         } else {
 290                                 pcap_fmt_errmsg_for_errno(errbuf,
 291                                     PCAP_ERRBUF_SIZE, errno,
 292                                     "SIOCGIFNETMASK: %.*s",
 293                                     (int)sizeof(ifrnetmask.ifr_name),
 294                                     ifrnetmask.ifr_name);
 295                                 ret = -1;
 296                                 break;
 297                         }
 298                 } else {
 299                         netmask = &ifrnetmask.ifr_addr;
 300                         netmask_size = SA_LEN(netmask);
 301                 }
 302
 303                 /*
 304                  * Get the broadcast address for this address on this
 305                  * interface (if any).
 306                  */
 307                 if (ifrflags.ifr_flags & IFF_BROADCAST) {
 308                         strncpy(ifrbroadaddr.ifr_name, ifrp->ifr_name,
 309                             sizeof(ifrbroadaddr.ifr_name));
 310                         memcpy(&ifrbroadaddr.ifr_addr, &ifrp->ifr_addr,
 311                             sizeof(ifrbroadaddr.ifr_addr));
 312                         if (ioctl(fd, SIOCGIFBRDADDR,
 313                             (char *)&ifrbroadaddr) < 0) {
 314                                 if (errno == EADDRNOTAVAIL) {
 315                                         /*
 316                                          * Not available.
 317                                          */
 318                                         broadaddr = NULL;
 319                                         broadaddr_size = 0;
 320                                 } else {
 321                                         pcap_fmt_errmsg_for_errno(errbuf,
 322                                             PCAP_ERRBUF_SIZE, errno,
 323                                             "SIOCGIFBRDADDR: %.*s",
 324                                             (int)sizeof(ifrbroadaddr.ifr_name),
 325                                             ifrbroadaddr.ifr_name);
 326                                         ret = -1;
 327                                         break;
 328                                 }
 329                         } else {
 330                                 broadaddr = &ifrbroadaddr.ifr_broadaddr;
 331                                 broadaddr_size = SA_LEN(broadaddr);
 332                         }
 333                 } else {
 334                         /*
 335                          * Not a broadcast interface, so no broadcast
 336                          * address.
 337                          */
 338                         broadaddr = NULL;
 339                         broadaddr_size = 0;
 340                 }
 341
 342                 /*
 343                  * Get the destination address for this address on this
 344                  * interface (if any).
 345                  */
 346                 if (ifrflags.ifr_flags & IFF_POINTOPOINT) {
 347                         strncpy(ifrdstaddr.ifr_name, ifrp->ifr_name,
 348                             sizeof(ifrdstaddr.ifr_name));
 349                         memcpy(&ifrdstaddr.ifr_addr, &ifrp->ifr_addr,
 350                             sizeof(ifrdstaddr.ifr_addr));
 351                         if (ioctl(fd, SIOCGIFDSTADDR,
 352                             (char *)&ifrdstaddr) < 0) {
 353                                 if (errno == EADDRNOTAVAIL) {
 354                                         /*
 355                                          * Not available.
 356                                          */
 357                                         dstaddr = NULL;
 358                                         dstaddr_size = 0;
 359                                 } else {
 360                                         pcap_fmt_errmsg_for_errno(errbuf,
 361                                             PCAP_ERRBUF_SIZE, errno,
 362                                             "SIOCGIFDSTADDR: %.*s",
 363                                             (int)sizeof(ifrdstaddr.ifr_name),
 364                                             ifrdstaddr.ifr_name);
 365                                         ret = -1;
 366                                         break;
 367                                 }
 368                         } else {
 369                                 dstaddr = &ifrdstaddr.ifr_dstaddr;
 370                                 dstaddr_size = SA_LEN(dstaddr);
 371                         }
 372                 } else {
 373                         /*
 374                          * Not a point-to-point interface, so no destination
 375                          * address.
 376                          */
 377                         dstaddr = NULL;
 378                         dstaddr_size = 0;
 379                 }
 380
 381 #if defined (HAVE_SOLARIS) || defined (HAVE_HPUX10_20_OR_LATER)
 382                 /*
 383                  * If this entry has a colon followed by a number at
 384                  * the end, it's a logical interface.  Those are just
 385                  * the way you assign multiple IP addresses to a real
 386                  * interface, so an entry for a logical interface should
 387                  * be treated like the entry for the real interface;
 388                  * we do that by stripping off the ":" and the number.
 389                  */
 390                 p = strchr(ifrp->ifr_name, ':');
 391                 if (p != NULL) {
 392                         /*
 393                          * We have a ":"; is it followed by a number?
 394                          */
 395                         q = p + 1;
 396                         while (PCAP_ISDIGIT(*q))
 397                                 q++;
 398                         if (*q == '\0') {
 399                                 /*
 400                                  * All digits after the ":" until the end.
 401                                  * Strip off the ":" and everything after
 402                                  * it.
 403                                  */
 404                                 *p = '\0';
 405                         }
 406                 }
 407 #endif
 408
 409                 /*
 410                  * Add information for this address to the list.
 411                  */
 412                 if (add_addr_to_if(devlistp, ifrp->ifr_name,
 413                     ifrflags.ifr_flags, get_flags_func,
 414                     &ifrp->ifr_addr, SA_LEN(&ifrp->ifr_addr),
 415                     netmask, netmask_size, broadaddr, broadaddr_size,
 416                     dstaddr, dstaddr_size, errbuf) < 0) {
 417                         ret = -1;
 418                         break;
 419                 }
 420         }
 421         free(buf);
 422         (void)close(fd);
 423
 424         return (ret);
 425 }