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 #include <limits.h>
  60
  61 #include "pcap-int.h"
  62
  63 #ifdef HAVE_OS_PROTO_H
  64 #include "os-proto.h"
  65 #endif
  66
  67 /*
  68  * This is fun.
  69  *
  70  * In older BSD systems, socket addresses were fixed-length, and
  71  * "sizeof (struct sockaddr)" gave the size of the structure.
  72  * All addresses fit within a "struct sockaddr".
  73  *
  74  * In newer BSD systems, the socket address is variable-length, and
  75  * there's an "sa_len" field giving the length of the structure;
  76  * this allows socket addresses to be longer than 2 bytes of family
  77  * and 14 bytes of data.
  78  *
  79  * Some commercial UNIXes use the old BSD scheme, some use the RFC 2553
  80  * variant of the old BSD scheme (with "struct sockaddr_storage" rather
  81  * than "struct sockaddr"), and some use the new BSD scheme.
  82  *
  83  * Some versions of GNU libc use neither scheme, but has an "SA_LEN()"
  84  * macro that determines the size based on the address family.  Other
  85  * versions don't have "SA_LEN()" (as it was in drafts of RFC 2553
  86  * but not in the final version).
  87  *
  88  * We assume that a UNIX that doesn't have "getifaddrs()" and doesn't have
  89  * SIOCGLIFCONF, but has SIOCGIFCONF, uses "struct sockaddr" for the
  90  * address in an entry returned by SIOCGIFCONF.
  91  */
  92 #ifndef SA_LEN
  93 #ifdef HAVE_STRUCT_SOCKADDR_SA_LEN
  94 #define SA_LEN(addr)    ((addr)->sa_len)
  95 #else /* HAVE_STRUCT_SOCKADDR_SA_LEN */
  96 #define SA_LEN(addr)    (sizeof (struct sockaddr))
  97 #endif /* HAVE_STRUCT_SOCKADDR_SA_LEN */
  98 #endif /* SA_LEN */
  99
 100 /*
 101  * This is also fun.
 102  *
 103  * There is no ioctl that returns the amount of space required for all
 104  * the data that SIOCGIFCONF could return, and if a buffer is supplied
 105  * that's not large enough for all the data SIOCGIFCONF could return,
 106  * on at least some platforms it just returns the data that'd fit with
 107  * no indication that there wasn't enough room for all the data, much
 108  * less an indication of how much more room is required.
 109  *
 110  * The only way to ensure that we got all the data is to pass a buffer
 111  * large enough that the amount of space in the buffer *not* filled in
 112  * is greater than the largest possible entry.
 113  *
 114  * We assume that's "sizeof(ifreq.ifr_name)" plus 255, under the assumption
 115  * that no address is more than 255 bytes (on systems where the "sa_len"
 116  * field in a "struct sockaddr" is 1 byte, e.g. newer BSDs, that's the
 117  * case, and addresses are unlikely to be bigger than that in any case).
 118  */
 119 #define MAX_SA_LEN      255
 120
 121 /*
 122  * Get a list of all interfaces that are up and that we can open.
 123  * Returns -1 on error, 0 otherwise.
 124  * The list, as returned through "alldevsp", may be null if no interfaces
 125  * were up and could be opened.
 126  *
 127  * This is the implementation used on platforms that have SIOCGIFCONF but
 128  * don't have any other mechanism for getting a list of interfaces.
 129  *
 130  * XXX - or platforms that have other, better mechanisms but for which
 131  * we don't yet have code to use that mechanism; I think there's a better
 132  * way on Linux, for example, but if that better way is "getifaddrs()",
 133  * we already have that.
 134  */
 135 int
 136 pcap_findalldevs_interfaces(pcap_if_list_t *devlistp, char *errbuf,
 137     int (*check_usable)(const char *), get_if_flags_func get_flags_func)
 138 {
 139         register int fd;
 140         register struct ifreq *ifrp, *ifend, *ifnext;
 141         size_t n;
 142         struct ifconf ifc;
 143         char *buf = NULL;
 144         unsigned buf_size;
 145 #if defined (HAVE_SOLARIS) || defined (HAVE_HPUX10_20_OR_LATER)
 146         char *p, *q;
 147 #endif
 148         struct ifreq ifrflags, ifrnetmask, ifrbroadaddr, ifrdstaddr;
 149         struct sockaddr *netmask, *broadaddr, *dstaddr;
 150         size_t netmask_size, broadaddr_size, dstaddr_size;
 151         int ret = 0;
 152
 153         /*
 154          * Create a socket from which to fetch the list of interfaces.
 155          */
 156         fd = socket(AF_INET, SOCK_DGRAM, 0);
 157         if (fd < 0) {
 158                 pcap_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
 159                     errno, "socket");
 160                 return (-1);
 161         }
 162
 163         /*
 164          * Start with an 8K buffer, and keep growing the buffer until
 165          * we have more than "sizeof(ifrp->ifr_name) + MAX_SA_LEN"
 166          * bytes left over in the buffer or we fail to get the
 167          * interface list for some reason other than EINVAL (which is
 168          * presumed here to mean "buffer is too small").
 169          */
 170         buf_size = 8192;
 171         for (;;) {
 172                 /*
 173                  * Don't let the buffer size get bigger than INT_MAX.
 174                  */
 175                 if (buf_size > INT_MAX) {
 176                         (void)pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
 177                             "interface information requires more than %u bytes",
 178                             INT_MAX);
 179                         (void)close(fd);
 180                         return (-1);
 181                 }
 182                 buf = malloc(buf_size);
 183                 if (buf == NULL) {
 184                         pcap_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
 185                             errno, "malloc");
 186                         (void)close(fd);
 187                         return (-1);
 188                 }
 189
 190                 ifc.ifc_len = buf_size;
 191                 ifc.ifc_buf = buf;
 192                 memset(buf, 0, buf_size);
 193                 if (ioctl(fd, SIOCGIFCONF, (char *)&ifc) < 0
 194                     && errno != EINVAL) {
 195                         pcap_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
 196                             errno, "SIOCGIFCONF");
 197                         (void)close(fd);
 198                         free(buf);
 199                         return (-1);
 200                 }
 201                 if (ifc.ifc_len < (int)buf_size &&
 202                     (buf_size - ifc.ifc_len) > sizeof(ifrp->ifr_name) + MAX_SA_LEN)
 203                         break;
 204                 free(buf);
 205                 buf_size *= 2;
 206         }
 207
 208         ifrp = (struct ifreq *)buf;
 209         ifend = (struct ifreq *)(buf + ifc.ifc_len);
 210
 211         for (; ifrp < ifend; ifrp = ifnext) {
 212                 /*
 213                  * XXX - what if this isn't an IPv4 address?  Can
 214                  * we still get the netmask, etc. with ioctls on
 215                  * an IPv4 socket?
 216                  *
 217                  * The answer is probably platform-dependent, and
 218                  * if the answer is "no" on more than one platform,
 219                  * the way you work around it is probably platform-
 220                  * dependent as well.
 221                  */
 222                 n = SA_LEN(&ifrp->ifr_addr) + sizeof(ifrp->ifr_name);
 223                 if (n < sizeof(*ifrp))
 224                         ifnext = ifrp + 1;
 225                 else
 226                         ifnext = (struct ifreq *)((char *)ifrp + n);
 227
 228                 /*
 229                  * XXX - The 32-bit compatibility layer for Linux on IA-64
 230                  * is slightly broken. It correctly converts the structures
 231                  * to and from kernel land from 64 bit to 32 bit but
 232                  * doesn't update ifc.ifc_len, leaving it larger than the
 233                  * amount really used. This means we read off the end
 234                  * of the buffer and encounter an interface with an
 235                  * "empty" name. Since this is highly unlikely to ever
 236                  * occur in a valid case we can just finish looking for
 237                  * interfaces if we see an empty name.
 238                  */
 239                 if (!(*ifrp->ifr_name))
 240                         break;
 241
 242                 /*
 243                  * Skip entries that begin with "dummy".
 244                  * XXX - what are these?  Is this Linux-specific?
 245                  * Are there platforms on which we shouldn't do this?
 246                  */
 247                 if (strncmp(ifrp->ifr_name, "dummy", 5) == 0)
 248                         continue;
 249
 250                 /*
 251                  * Can we capture on this device?
 252                  */
 253                 if (!(*check_usable)(ifrp->ifr_name)) {
 254                         /*
 255                          * No.
 256                          */
 257                         continue;
 258                 }
 259
 260                 /*
 261                  * Get the flags for this interface.
 262                  */
 263                 strncpy(ifrflags.ifr_name, ifrp->ifr_name,
 264                     sizeof(ifrflags.ifr_name));
 265                 if (ioctl(fd, SIOCGIFFLAGS, (char *)&ifrflags) < 0) {
 266                         if (errno == ENXIO)
 267                                 continue;
 268                         pcap_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
 269                             errno, "SIOCGIFFLAGS: %.*s",
 270                             (int)sizeof(ifrflags.ifr_name),
 271                             ifrflags.ifr_name);
 272                         ret = -1;
 273                         break;
 274                 }
 275
 276                 /*
 277                  * Get the netmask for this address on this interface.
 278                  */
 279                 strncpy(ifrnetmask.ifr_name, ifrp->ifr_name,
 280                     sizeof(ifrnetmask.ifr_name));
 281                 memcpy(&ifrnetmask.ifr_addr, &ifrp->ifr_addr,
 282                     sizeof(ifrnetmask.ifr_addr));
 283                 if (ioctl(fd, SIOCGIFNETMASK, (char *)&ifrnetmask) < 0) {
 284                         if (errno == EADDRNOTAVAIL) {
 285                                 /*
 286                                  * Not available.
 287                                  */
 288                                 netmask = NULL;
 289                                 netmask_size = 0;
 290                         } else {
 291                                 pcap_fmt_errmsg_for_errno(errbuf,
 292                                     PCAP_ERRBUF_SIZE, errno,
 293                                     "SIOCGIFNETMASK: %.*s",
 294                                     (int)sizeof(ifrnetmask.ifr_name),
 295                                     ifrnetmask.ifr_name);
 296                                 ret = -1;
 297                                 break;
 298                         }
 299                 } else {
 300                         netmask = &ifrnetmask.ifr_addr;
 301                         netmask_size = SA_LEN(netmask);
 302                 }
 303
 304                 /*
 305                  * Get the broadcast address for this address on this
 306                  * interface (if any).
 307                  */
 308                 if (ifrflags.ifr_flags & IFF_BROADCAST) {
 309                         strncpy(ifrbroadaddr.ifr_name, ifrp->ifr_name,
 310                             sizeof(ifrbroadaddr.ifr_name));
 311                         memcpy(&ifrbroadaddr.ifr_addr, &ifrp->ifr_addr,
 312                             sizeof(ifrbroadaddr.ifr_addr));
 313                         if (ioctl(fd, SIOCGIFBRDADDR,
 314                             (char *)&ifrbroadaddr) < 0) {
 315                                 if (errno == EADDRNOTAVAIL) {
 316                                         /*
 317                                          * Not available.
 318                                          */
 319                                         broadaddr = NULL;
 320                                         broadaddr_size = 0;
 321                                 } else {
 322                                         pcap_fmt_errmsg_for_errno(errbuf,
 323                                             PCAP_ERRBUF_SIZE, errno,
 324                                             "SIOCGIFBRDADDR: %.*s",
 325                                             (int)sizeof(ifrbroadaddr.ifr_name),
 326                                             ifrbroadaddr.ifr_name);
 327                                         ret = -1;
 328                                         break;
 329                                 }
 330                         } else {
 331                                 broadaddr = &ifrbroadaddr.ifr_broadaddr;
 332                                 broadaddr_size = SA_LEN(broadaddr);
 333                         }
 334                 } else {
 335                         /*
 336                          * Not a broadcast interface, so no broadcast
 337                          * address.
 338                          */
 339                         broadaddr = NULL;
 340                         broadaddr_size = 0;
 341                 }
 342
 343                 /*
 344                  * Get the destination address for this address on this
 345                  * interface (if any).
 346                  */
 347                 if (ifrflags.ifr_flags & IFF_POINTOPOINT) {
 348                         strncpy(ifrdstaddr.ifr_name, ifrp->ifr_name,
 349                             sizeof(ifrdstaddr.ifr_name));
 350                         memcpy(&ifrdstaddr.ifr_addr, &ifrp->ifr_addr,
 351                             sizeof(ifrdstaddr.ifr_addr));
 352                         if (ioctl(fd, SIOCGIFDSTADDR,
 353                             (char *)&ifrdstaddr) < 0) {
 354                                 if (errno == EADDRNOTAVAIL) {
 355                                         /*
 356                                          * Not available.
 357                                          */
 358                                         dstaddr = NULL;
 359                                         dstaddr_size = 0;
 360                                 } else {
 361                                         pcap_fmt_errmsg_for_errno(errbuf,
 362                                             PCAP_ERRBUF_SIZE, errno,
 363                                             "SIOCGIFDSTADDR: %.*s",
 364                                             (int)sizeof(ifrdstaddr.ifr_name),
 365                                             ifrdstaddr.ifr_name);
 366                                         ret = -1;
 367                                         break;
 368                                 }
 369                         } else {
 370                                 dstaddr = &ifrdstaddr.ifr_dstaddr;
 371                                 dstaddr_size = SA_LEN(dstaddr);
 372                         }
 373                 } else {
 374                         /*
 375                          * Not a point-to-point interface, so no destination
 376                          * address.
 377                          */
 378                         dstaddr = NULL;
 379                         dstaddr_size = 0;
 380                 }
 381
 382 #if defined (HAVE_SOLARIS) || defined (HAVE_HPUX10_20_OR_LATER)
 383                 /*
 384                  * If this entry has a colon followed by a number at
 385                  * the end, it's a logical interface.  Those are just
 386                  * the way you assign multiple IP addresses to a real
 387                  * interface, so an entry for a logical interface should
 388                  * be treated like the entry for the real interface;
 389                  * we do that by stripping off the ":" and the number.
 390                  */
 391                 p = strchr(ifrp->ifr_name, ':');
 392                 if (p != NULL) {
 393                         /*
 394                          * We have a ":"; is it followed by a number?
 395                          */
 396                         q = p + 1;
 397                         while (isdigit((unsigned char)*q))
 398                                 q++;
 399                         if (*q == '\0') {
 400                                 /*
 401                                  * All digits after the ":" until the end.
 402                                  * Strip off the ":" and everything after
 403                                  * it.
 404                                  */
 405                                 *p = '\0';
 406                         }
 407                 }
 408 #endif
 409
 410                 /*
 411                  * Add information for this address to the list.
 412                  */
 413                 if (add_addr_to_if(devlistp, ifrp->ifr_name,
 414                     ifrflags.ifr_flags, get_flags_func,
 415                     &ifrp->ifr_addr, SA_LEN(&ifrp->ifr_addr),
 416                     netmask, netmask_size, broadaddr, broadaddr_size,
 417                     dstaddr, dstaddr_size, errbuf) < 0) {
 418                         ret = -1;
 419                         break;
 420                 }
 421         }
 422         free(buf);
 423         (void)close(fd);
 424
 425         return (ret);
 426 }