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 #ifndef lint
  36 static const char rcsid[] _U_ =
  37     "@(#) $Header: /tcpdump/master/libpcap/fad-gifc.c,v 1.6 2004-02-27 08:03:05 guy Exp $ (LBL)";
  38 #endif
  39
  40 #ifdef HAVE_CONFIG_H
  41 #include "config.h"
  42 #endif
  43
  44 #include <sys/param.h>
  45 #include <sys/file.h>
  46 #include <sys/ioctl.h>
  47 #include <sys/socket.h>
  48 #ifdef HAVE_SYS_SOCKIO_H
  49 #include <sys/sockio.h>
  50 #endif
  51 #include <sys/time.h>                           /* concession to AIX */
  52
  53 struct mbuf;            /* Squelch compiler warnings on some platforms for */
  54 struct rtentry;         /* declarations in <net/if.h> */
  55 #include <net/if.h>
  56 #include <netinet/in.h>
  57
  58 #include <ctype.h>
  59 #include <errno.h>
  60 #include <memory.h>
  61 #include <stdio.h>
  62 #include <stdlib.h>
  63 #include <string.h>
  64 #include <unistd.h>
  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 #ifdef HAVE_PROC_NET_DEV
 106 /*
 107  * Get from "/proc/net/dev" all interfaces listed there; if they're
 108  * already in the list of interfaces we have, that won't add another
 109  * instance, but if they're not, that'll add them.
 110  *
 111  * We don't bother getting any addresses for them; it appears you can't
 112  * use SIOCGIFADDR on Linux to get IPv6 addresses for interfaces, and,
 113  * although some other types of addresses can be fetched with SIOCGIFADDR,
 114  * we don't bother with them for now.
 115  *
 116  * We also don't fail if we couldn't open "/proc/net/dev"; we just leave
 117  * the list of interfaces as is.
 118  */
 119 static int
 120 scan_proc_net_dev(pcap_if_t **devlistp, int fd, char *errbuf)
 121 {
 122         FILE *proc_net_f;
 123         char linebuf[512];
 124         int linenum;
 125         unsigned char *p;
 126         char name[512]; /* XXX - pick a size */
 127         char *q, *saveq;
 128         struct ifreq ifrflags;
 129         int ret = 0;
 130
 131         proc_net_f = fopen("/proc/net/dev", "r");
 132         if (proc_net_f == NULL)
 133                 return (0);
 134
 135         for (linenum = 1;
 136             fgets(linebuf, sizeof linebuf, proc_net_f) != NULL; linenum++) {
 137                 /*
 138                  * Skip the first two lines - they're headers.
 139                  */
 140                 if (linenum <= 2)
 141                         continue;
 142
 143                 p = &linebuf[0];
 144
 145                 /*
 146                  * Skip leading white space.
 147                  */
 148                 while (*p != '\0' && isspace(*p))
 149                         p++;
 150                 if (*p == '\0' || *p == '\n')
 151                         continue;       /* blank line */
 152
 153                 /*
 154                  * Get the interface name.
 155                  */
 156                 q = &name[0];
 157                 while (*p != '\0' && !isspace(*p)) {
 158                         if (*p == ':') {
 159                                 /*
 160                                  * This could be the separator between a
 161                                  * name and an alias number, or it could be
 162                                  * the separator between a name with no
 163                                  * alias number and the next field.
 164                                  *
 165                                  * If there's a colon after digits, it
 166                                  * separates the name and the alias number,
 167                                  * otherwise it separates the name and the
 168                                  * next field.
 169                                  */
 170                                 saveq = q;
 171                                 while (isdigit(*p))
 172                                         *q++ = *p++;
 173                                 if (*p != ':') {
 174                                         /*
 175                                          * That was the next field,
 176                                          * not the alias number.
 177                                          */
 178                                         q = saveq;
 179                                 }
 180                                 break;
 181                         } else
 182                                 *q++ = *p++;
 183                 }
 184                 *q = '\0';
 185
 186                 /*
 187                  * Get the flags for this interface, and skip it if
 188                  * it's not up.
 189                  */
 190                 strncpy(ifrflags.ifr_name, name, sizeof(ifrflags.ifr_name));
 191                 if (ioctl(fd, SIOCGIFFLAGS, (char *)&ifrflags) < 0) {
 192                         if (errno == ENXIO)
 193                                 continue;
 194                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 195                             "SIOCGIFFLAGS: %.*s: %s",
 196                             (int)sizeof(ifrflags.ifr_name),
 197                             ifrflags.ifr_name,
 198                             pcap_strerror(errno));
 199                         ret = -1;
 200                         break;
 201                 }
 202                 if (!(ifrflags.ifr_flags & IFF_UP))
 203                         continue;
 204
 205                 /*
 206                  * Add an entry for this interface, with no addresses.
 207                  */
 208                 if (pcap_add_if(devlistp, name, ifrflags.ifr_flags, NULL,
 209                     errbuf) == -1) {
 210                         /*
 211                          * Failure.
 212                          */
 213                         ret = -1;
 214                         break;
 215                 }
 216         }
 217         if (ret != -1) {
 218                 /*
 219                  * Well, we didn't fail for any other reason; did we
 220                  * fail due to an error reading the file?
 221                  */
 222                 if (ferror(proc_net_f)) {
 223                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 224                             "Error reading /proc/net/dev: %s",
 225                             pcap_strerror(errno));
 226                         ret = -1;
 227                 }
 228         }
 229
 230         (void)fclose(proc_net_f);
 231         return (ret);
 232 }
 233 #endif /* HAVE_PROC_NET_DEV */
 234
 235 /*
 236  * Get a list of all interfaces that are up and that we can open.
 237  * Returns -1 on error, 0 otherwise.
 238  * The list, as returned through "alldevsp", may be null if no interfaces
 239  * were up and could be opened.
 240  *
 241  * This is the implementation used on platforms that have SIOCGIFCONF but
 242  * don't have any other mechanism for getting a list of interfaces.
 243  *
 244  * XXX - or platforms that have other, better mechanisms but for which
 245  * we don't yet have code to use that mechanism; I think there's a better
 246  * way on Linux, for example.
 247  */
 248 int
 249 pcap_findalldevs(pcap_if_t **alldevsp, char *errbuf)
 250 {
 251         pcap_if_t *devlist = NULL;
 252         register int fd;
 253         register struct ifreq *ifrp, *ifend, *ifnext;
 254         int n;
 255         struct ifconf ifc;
 256         char *buf = NULL;
 257         unsigned buf_size;
 258         struct ifreq ifrflags, ifrnetmask, ifrbroadaddr, ifrdstaddr;
 259         struct sockaddr *netmask, *broadaddr, *dstaddr;
 260         size_t netmask_size, broadaddr_size, dstaddr_size;
 261         int ret = 0;
 262
 263         /*
 264          * Create a socket from which to fetch the list of interfaces.
 265          */
 266         fd = socket(AF_INET, SOCK_DGRAM, 0);
 267         if (fd < 0) {
 268                 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 269                     "socket: %s", pcap_strerror(errno));
 270                 return (-1);
 271         }
 272
 273         /*
 274          * Start with an 8K buffer, and keep growing the buffer until
 275          * we get the entire interface list or fail to get it for some
 276          * reason other than EINVAL (which is presumed here to mean
 277          * "buffer is too small").
 278          */
 279         buf_size = 8192;
 280         for (;;) {
 281                 buf = malloc(buf_size);
 282                 if (buf == NULL) {
 283                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 284                             "malloc: %s", pcap_strerror(errno));
 285                         (void)close(fd);
 286                         return (-1);
 287                 }
 288
 289                 ifc.ifc_len = buf_size;
 290                 ifc.ifc_buf = buf;
 291                 memset(buf, 0, buf_size);
 292                 if (ioctl(fd, SIOCGIFCONF, (char *)&ifc) < 0
 293                     && errno != EINVAL) {
 294                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 295                             "SIOCGIFCONF: %s", pcap_strerror(errno));
 296                         (void)close(fd);
 297                         free(buf);
 298                         return (-1);
 299                 }
 300                 if (ifc.ifc_len < buf_size)
 301                         break;
 302                 free(buf);
 303                 buf_size *= 2;
 304         }
 305
 306         ifrp = (struct ifreq *)buf;
 307         ifend = (struct ifreq *)(buf + ifc.ifc_len);
 308
 309         for (; ifrp < ifend; ifrp = ifnext) {
 310                 /*
 311                  * XXX - what if this isn't an IPv4 address?  Can
 312                  * we still get the netmask, etc. with ioctls on
 313                  * an IPv4 socket?
 314                  *
 315                  * The answer is probably platform-dependent, and
 316                  * if the answer is "no" on more than one platform,
 317                  * the way you work around it is probably platform-
 318                  * dependent as well.
 319                  */
 320                 n = SA_LEN(&ifrp->ifr_addr) + sizeof(ifrp->ifr_name);
 321                 if (n < sizeof(*ifrp))
 322                         ifnext = ifrp + 1;
 323                 else
 324                         ifnext = (struct ifreq *)((char *)ifrp + n);
 325
 326                 /*
 327                  * XXX - The 32-bit compatibility layer for Linux on IA-64
 328                  * is slightly broken. It correctly converts the structures
 329                  * to and from kernel land from 64 bit to 32 bit but
 330                  * doesn't update ifc.ifc_len, leaving it larger than the
 331                  * amount really used. This means we read off the end
 332                  * of the buffer and encounter an interface with an
 333                  * "empty" name. Since this is highly unlikely to ever
 334                  * occur in a valid case we can just finish looking for
 335                  * interfaces if we see an empty name.
 336                  */
 337                 if (!(*ifrp->ifr_name))
 338                         break;
 339
 340                 /*
 341                  * Get the flags for this interface, and skip it if it's
 342                  * not up.
 343                  */
 344                 strncpy(ifrflags.ifr_name, ifrp->ifr_name,
 345                     sizeof(ifrflags.ifr_name));
 346                 if (ioctl(fd, SIOCGIFFLAGS, (char *)&ifrflags) < 0) {
 347                         if (errno == ENXIO)
 348                                 continue;
 349                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 350                             "SIOCGIFFLAGS: %.*s: %s",
 351                             (int)sizeof(ifrflags.ifr_name),
 352                             ifrflags.ifr_name,
 353                             pcap_strerror(errno));
 354                         ret = -1;
 355                         break;
 356                 }
 357                 if (!(ifrflags.ifr_flags & IFF_UP))
 358                         continue;
 359
 360                 /*
 361                  * Get the netmask for this address on this interface.
 362                  */
 363                 strncpy(ifrnetmask.ifr_name, ifrp->ifr_name,
 364                     sizeof(ifrnetmask.ifr_name));
 365                 memcpy(&ifrnetmask.ifr_addr, &ifrp->ifr_addr,
 366                     sizeof(ifrnetmask.ifr_addr));
 367                 if (ioctl(fd, SIOCGIFNETMASK, (char *)&ifrnetmask) < 0) {
 368                         if (errno == EADDRNOTAVAIL) {
 369                                 /*
 370                                  * Not available.
 371                                  */
 372                                 netmask = NULL;
 373                                 netmask_size = 0;
 374                         } else {
 375                                 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 376                                     "SIOCGIFNETMASK: %.*s: %s",
 377                                     (int)sizeof(ifrnetmask.ifr_name),
 378                                     ifrnetmask.ifr_name,
 379                                     pcap_strerror(errno));
 380                                 ret = -1;
 381                                 break;
 382                         }
 383                 } else {
 384                         netmask = &ifrnetmask.ifr_addr;
 385                         netmask_size = SA_LEN(netmask);
 386                 }
 387
 388                 /*
 389                  * Get the broadcast address for this address on this
 390                  * interface (if any).
 391                  */
 392                 if (ifrflags.ifr_flags & IFF_BROADCAST) {
 393                         strncpy(ifrbroadaddr.ifr_name, ifrp->ifr_name,
 394                             sizeof(ifrbroadaddr.ifr_name));
 395                         memcpy(&ifrbroadaddr.ifr_addr, &ifrp->ifr_addr,
 396                             sizeof(ifrbroadaddr.ifr_addr));
 397                         if (ioctl(fd, SIOCGIFBRDADDR,
 398                             (char *)&ifrbroadaddr) < 0) {
 399                                 if (errno == EADDRNOTAVAIL) {
 400                                         /*
 401                                          * Not available.
 402                                          */
 403                                         broadaddr = NULL;
 404                                         broadaddr_size = 0;
 405                                 } else {
 406                                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 407                                             "SIOCGIFBRDADDR: %.*s: %s",
 408                                             (int)sizeof(ifrbroadaddr.ifr_name),
 409                                             ifrbroadaddr.ifr_name,
 410                                             pcap_strerror(errno));
 411                                         ret = -1;
 412                                         break;
 413                                 }
 414                         } else {
 415                                 broadaddr = &ifrbroadaddr.ifr_broadaddr;
 416                                 broadaddr_size = SA_LEN(broadaddr);
 417                         }
 418                 } else {
 419                         /*
 420                          * Not a broadcast interface, so no broadcast
 421                          * address.
 422                          */
 423                         broadaddr = NULL;
 424                         broadaddr_size = 0;
 425                 }
 426
 427                 /*
 428                  * Get the destination address for this address on this
 429                  * interface (if any).
 430                  */
 431                 if (ifrflags.ifr_flags & IFF_POINTOPOINT) {
 432                         strncpy(ifrdstaddr.ifr_name, ifrp->ifr_name,
 433                             sizeof(ifrdstaddr.ifr_name));
 434                         memcpy(&ifrdstaddr.ifr_addr, &ifrp->ifr_addr,
 435                             sizeof(ifrdstaddr.ifr_addr));
 436                         if (ioctl(fd, SIOCGIFDSTADDR,
 437                             (char *)&ifrdstaddr) < 0) {
 438                                 if (errno == EADDRNOTAVAIL) {
 439                                         /*
 440                                          * Not available.
 441                                          */
 442                                         dstaddr = NULL;
 443                                         dstaddr_size = 0;
 444                                 } else {
 445                                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 446                                             "SIOCGIFDSTADDR: %.*s: %s",
 447                                             (int)sizeof(ifrdstaddr.ifr_name),
 448                                             ifrdstaddr.ifr_name,
 449                                             pcap_strerror(errno));
 450                                         ret = -1;
 451                                         break;
 452                                 }
 453                         } else {
 454                                 dstaddr = &ifrdstaddr.ifr_dstaddr;
 455                                 dstaddr_size = SA_LEN(dstaddr);
 456                         }
 457                 } else {
 458                         /*
 459                          * Not a point-to-point interface, so no destination
 460                          * address.
 461                          */
 462                         dstaddr = NULL;
 463                         dstaddr_size = 0;
 464                 }
 465
 466                 /*
 467                  * Add information for this address to the list.
 468                  */
 469                 if (add_addr_to_iflist(&devlist, ifrp->ifr_name,
 470                     ifrflags.ifr_flags, &ifrp->ifr_addr,
 471                     SA_LEN(&ifrp->ifr_addr), netmask, netmask_size,
 472                     broadaddr, broadaddr_size, dstaddr, dstaddr_size,
 473                     errbuf) < 0) {
 474                         ret = -1;
 475                         break;
 476                 }
 477         }
 478         free(buf);
 479
 480 #ifdef HAVE_PROC_NET_DEV
 481         if (ret != -1) {
 482                 /*
 483                  * We haven't had any errors yet; now read "/proc/net/dev",
 484                  * and add to the list of interfaces all interfaces listed
 485                  * there that we don't already have, because, on Linux,
 486                  * SIOCGIFCONF reports only interfaces with IPv4 addresses,
 487                  * so you need to read "/proc/net/dev" to get the names of
 488                  * the rest of the interfaces.
 489                  */
 490                 ret = scan_proc_net_dev(&devlist, fd, errbuf);
 491         }
 492 #endif
 493         (void)close(fd);
 494
 495         if (ret != -1) {
 496                 /*
 497                  * We haven't had any errors yet; do any platform-specific
 498                  * operations to add devices.
 499                  */
 500                 if (pcap_platform_finddevs(&devlist, errbuf) < 0)
 501                         ret = -1;
 502         }
 503
 504         if (ret == -1) {
 505                 /*
 506                  * We had an error; free the list we've been constructing.
 507                  */
 508                 if (devlist != NULL) {
 509                         pcap_freealldevs(devlist);
 510                         devlist = NULL;
 511                 }
 512         }
 513
 514         *alldevsp = devlist;
 515         return (ret);
 516 }