The Tcpdump Group git mirrors - libpcap/blob - inet.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[] =
  37     "@(#) $Header: /tcpdump/master/libpcap/inet.c,v 1.58 2003-09-25 22:22:25 guy Exp $ (LBL)";
  38 #endif
  39
  40 #ifdef HAVE_CONFIG_H
  41 #include "config.h"
  42 #endif
  43
  44 #ifdef WIN32
  45 #include <pcap-stdinc.h>
  46 #else /* WIN32 */
  47
  48 #include <sys/param.h>
  49 #include <sys/file.h>
  50 #include <sys/ioctl.h>
  51 #include <sys/socket.h>
  52 #ifdef HAVE_SYS_SOCKIO_H
  53 #include <sys/sockio.h>
  54 #endif
  55 #include <sys/time.h>                           /* concession to AIX */
  56
  57 struct mbuf;            /* Squelch compiler warnings on some platforms for */
  58 struct rtentry;         /* declarations in <net/if.h> */
  59 #include <net/if.h>
  60 #include <netinet/in.h>
  61 #endif /* WIN32 */
  62
  63 #include <ctype.h>
  64 #include <errno.h>
  65 #include <memory.h>
  66 #include <stdio.h>
  67 #include <stdlib.h>
  68 #include <string.h>
  69 #ifndef WIN32
  70 #include <unistd.h>
  71 #endif /* WIN32 */
  72 #ifdef HAVE_LIMITS_H
  73 #include <limits.h>
  74 #else
  75 #define INT_MAX         2147483647
  76 #endif
  77 #ifdef HAVE_IFADDRS_H
  78 #include <ifaddrs.h>
  79 #endif
  80
  81 #include "pcap-int.h"
  82
  83 #ifdef HAVE_OS_PROTO_H
  84 #include "os-proto.h"
  85 #endif
  86
  87 /* Not all systems have IFF_LOOPBACK */
  88 #ifdef IFF_LOOPBACK
  89 #define ISLOOPBACK(name, flags) ((flags) & IFF_LOOPBACK)
  90 #else
  91 #define ISLOOPBACK(name, flags) ((name)[0] == 'l' && (name)[1] == 'o' && \
  92     (isdigit((unsigned char)((name)[2])) || (name)[2] == '\0'))
  93 #endif
  94
  95 struct sockaddr *
  96 dup_sockaddr(struct sockaddr *sa, size_t sa_length)
  97 {
  98         struct sockaddr *newsa;
  99
 100         if ((newsa = malloc(sa_length)) == NULL)
 101                 return (NULL);
 102         return (memcpy(newsa, sa, sa_length));
 103 }
 104
 105 static int
 106 get_instance(const char *name)
 107 {
 108         const char *cp, *endcp;
 109         int n;
 110
 111         if (strcmp(name, "any") == 0) {
 112                 /*
 113                  * Give the "any" device an artificially high instance
 114                  * number, so it shows up after all other non-loopback
 115                  * interfaces.
 116                  */
 117                 return INT_MAX;
 118         }
 119
 120         endcp = name + strlen(name);
 121         for (cp = name; cp < endcp && !isdigit((unsigned char)*cp); ++cp)
 122                 continue;
 123
 124         if (isdigit((unsigned char)*cp))
 125                 n = atoi(cp);
 126         else
 127                 n = 0;
 128         return (n);
 129 }
 130
 131 int
 132 add_or_find_if(pcap_if_t **curdev_ret, pcap_if_t **alldevs, const char *name,
 133     u_int flags, const char *description, char *errbuf)
 134 {
 135         pcap_if_t *curdev, *prevdev, *nextdev;
 136         int this_instance;
 137
 138         /*
 139          * Is there already an entry in the list for this interface?
 140          */
 141         for (curdev = *alldevs; curdev != NULL; curdev = curdev->next) {
 142                 if (strcmp(name, curdev->name) == 0)
 143                         break;  /* yes, we found it */
 144         }
 145         if (curdev == NULL) {
 146                 /*
 147                  * No, we didn't find it.
 148                  * Allocate a new entry.
 149                  */
 150                 curdev = malloc(sizeof(pcap_if_t));
 151                 if (curdev == NULL) {
 152                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 153                             "malloc: %s", pcap_strerror(errno));
 154                         return (-1);
 155                 }
 156
 157                 /*
 158                  * Fill in the entry.
 159                  */
 160                 curdev->next = NULL;
 161                 curdev->name = malloc(strlen(name) + 1);
 162                 strcpy(curdev->name, name);
 163                 if (description != NULL) {
 164                         /*
 165                          * We have a description for this interface.
 166                          */
 167                         curdev->description = malloc(strlen(description) + 1);
 168                         strcpy(curdev->description, description);
 169                 } else {
 170                         /*
 171                          * We don't.
 172                          */
 173                         curdev->description = NULL;
 174                 }
 175                 curdev->addresses = NULL;       /* list starts out as empty */
 176                 curdev->flags = 0;
 177                 if (ISLOOPBACK(name, flags))
 178                         curdev->flags |= PCAP_IF_LOOPBACK;
 179
 180                 /*
 181                  * Add it to the list, in the appropriate location.
 182                  * First, get the instance number of this interface.
 183                  */
 184                 this_instance = get_instance(name);
 185
 186                 /*
 187                  * Now look for the last interface with an instance number
 188                  * less than or equal to the new interface's instance
 189                  * number - except that non-loopback interfaces are
 190                  * arbitrarily treated as having interface numbers less
 191                  * than those of loopback interfaces, so the loopback
 192                  * interfaces are put at the end of the list.
 193                  *
 194                  * We start with "prevdev" being NULL, meaning we're before
 195                  * the first element in the list.
 196                  */
 197                 prevdev = NULL;
 198                 for (;;) {
 199                         /*
 200                          * Get the interface after this one.
 201                          */
 202                         if (prevdev == NULL) {
 203                                 /*
 204                                  * The next element is the first element.
 205                                  */
 206                                 nextdev = *alldevs;
 207                         } else
 208                                 nextdev = prevdev->next;
 209
 210                         /*
 211                          * Are we at the end of the list?
 212                          */
 213                         if (nextdev == NULL) {
 214                                 /*
 215                                  * Yes - we have to put the new entry
 216                                  * after "prevdev".
 217                                  */
 218                                 break;
 219                         }
 220
 221                         /*
 222                          * Is the new interface a non-loopback interface
 223                          * and the next interface a loopback interface?
 224                          */
 225                         if (!(curdev->flags & PCAP_IF_LOOPBACK) &&
 226                             (nextdev->flags & PCAP_IF_LOOPBACK)) {
 227                                 /*
 228                                  * Yes, we should put the new entry
 229                                  * before "nextdev", i.e. after "prevdev".
 230                                  */
 231                                 break;
 232                         }
 233
 234                         /*
 235                          * Is the new interface's instance number less
 236                          * than the next interface's instance number,
 237                          * and is it the case that the new interface is a
 238                          * non-loopback interface or the next interface is
 239                          * a loopback interface?
 240                          *
 241                          * (The goal of both loopback tests is to make
 242                          * sure that we never put a loopback interface
 243                          * before any non-loopback interface and that we
 244                          * always put a non-loopback interface before all
 245                          * loopback interfaces.)
 246                          */
 247                         if (this_instance < get_instance(nextdev->name) &&
 248                             (!(curdev->flags & PCAP_IF_LOOPBACK) ||
 249                                (nextdev->flags & PCAP_IF_LOOPBACK))) {
 250                                 /*
 251                                  * Yes - we should put the new entry
 252                                  * before "nextdev", i.e. after "prevdev".
 253                                  */
 254                                 break;
 255                         }
 256
 257                         prevdev = nextdev;
 258                 }
 259
 260                 /*
 261                  * Insert before "nextdev".
 262                  */
 263                 curdev->next = nextdev;
 264
 265                 /*
 266                  * Insert after "prevdev" - unless "prevdev" is null,
 267                  * in which case this is the first interface.
 268                  */
 269                 if (prevdev == NULL) {
 270                         /*
 271                          * This is the first interface.  Pass back a
 272                          * pointer to it, and put "curdev" before
 273                          * "nextdev".
 274                          */
 275                         *alldevs = curdev;
 276                 } else
 277                         prevdev->next = curdev;
 278         }
 279
 280         *curdev_ret = curdev;
 281         return (0);
 282 }
 283
 284 int
 285 add_addr_to_iflist(pcap_if_t **alldevs, char *name, u_int flags,
 286     struct sockaddr *addr, size_t addr_size,
 287     struct sockaddr *netmask, size_t netmask_size,
 288     struct sockaddr *broadaddr, size_t broadaddr_size,
 289     struct sockaddr *dstaddr, size_t dstaddr_size,
 290     char *errbuf)
 291 {
 292         pcap_if_t *curdev;
 293         pcap_addr_t *curaddr, *prevaddr, *nextaddr;
 294
 295         if (add_or_find_if(&curdev, alldevs, name, flags, NULL, errbuf) == -1) {
 296                 /*
 297                  * Error - give up.
 298                  */
 299                 return (-1);
 300         }
 301         if (curdev == NULL) {
 302                 /*
 303                  * Device wasn't added because it can't be opened.
 304                  * Not a fatal error.
 305                  */
 306                 return (0);
 307         }
 308
 309         /*
 310          * "curdev" is an entry for this interface; add an entry for this
 311          * address to its list of addresses.
 312          *
 313          * Allocate the new entry and fill it in.
 314          */
 315         curaddr = malloc(sizeof(pcap_addr_t));
 316         if (curaddr == NULL) {
 317                 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 318                     "malloc: %s", pcap_strerror(errno));
 319                 return (-1);
 320         }
 321
 322         curaddr->next = NULL;
 323         if (addr != NULL) {
 324                 curaddr->addr = dup_sockaddr(addr, addr_size);
 325                 if (curaddr->addr == NULL) {
 326                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 327                             "malloc: %s", pcap_strerror(errno));
 328                         free(curaddr);
 329                         return (-1);
 330                 }
 331         } else
 332                 curaddr->addr = NULL;
 333
 334         if (netmask != NULL) {
 335                 curaddr->netmask = dup_sockaddr(netmask, netmask_size);
 336                 if (curaddr->netmask == NULL) {
 337                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 338                             "malloc: %s", pcap_strerror(errno));
 339                         free(curaddr);
 340                         return (-1);
 341                 }
 342         } else
 343                 curaddr->netmask = NULL;
 344
 345         if (broadaddr != NULL) {
 346                 curaddr->broadaddr = dup_sockaddr(broadaddr, broadaddr_size);
 347                 if (curaddr->broadaddr == NULL) {
 348                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 349                             "malloc: %s", pcap_strerror(errno));
 350                         free(curaddr);
 351                         return (-1);
 352                 }
 353         } else
 354                 curaddr->broadaddr = NULL;
 355
 356         if (dstaddr != NULL) {
 357                 curaddr->dstaddr = dup_sockaddr(dstaddr, dstaddr_size);
 358                 if (curaddr->dstaddr == NULL) {
 359                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 360                             "malloc: %s", pcap_strerror(errno));
 361                         free(curaddr);
 362                         return (-1);
 363                 }
 364         } else
 365                 curaddr->dstaddr = NULL;
 366
 367         /*
 368          * Find the end of the list of addresses.
 369          */
 370         for (prevaddr = curdev->addresses; prevaddr != NULL; prevaddr = nextaddr) {
 371                 nextaddr = prevaddr->next;
 372                 if (nextaddr == NULL) {
 373                         /*
 374                          * This is the end of the list.
 375                          */
 376                         break;
 377                 }
 378         }
 379
 380         if (prevaddr == NULL) {
 381                 /*
 382                  * The list was empty; this is the first member.
 383                  */
 384                 curdev->addresses = curaddr;
 385         } else {
 386                 /*
 387                  * "prevaddr" is the last member of the list; append
 388                  * this member to it.
 389                  */
 390                 prevaddr->next = curaddr;
 391         }
 392
 393         return (0);
 394 }
 395
 396 int
 397 pcap_add_if(pcap_if_t **devlist, char *name, u_int flags,
 398     const char *description, char *errbuf)
 399 {
 400         pcap_if_t *curdev;
 401
 402         return (add_or_find_if(&curdev, devlist, name, flags, description,
 403             errbuf));
 404 }
 405
 406
 407 /*
 408  * Free a list of interfaces.
 409  */
 410 void
 411 pcap_freealldevs(pcap_if_t *alldevs)
 412 {
 413         pcap_if_t *curdev, *nextdev;
 414         pcap_addr_t *curaddr, *nextaddr;
 415
 416         for (curdev = alldevs; curdev != NULL; curdev = nextdev) {
 417                 nextdev = curdev->next;
 418
 419                 /*
 420                  * Free all addresses.
 421                  */
 422                 for (curaddr = curdev->addresses; curaddr != NULL; curaddr = nextaddr) {
 423                         nextaddr = curaddr->next;
 424                         if (curaddr->addr)
 425                                 free(curaddr->addr);
 426                         if (curaddr->netmask)
 427                                 free(curaddr->netmask);
 428                         if (curaddr->broadaddr)
 429                                 free(curaddr->broadaddr);
 430                         if (curaddr->dstaddr)
 431                                 free(curaddr->dstaddr);
 432                         free(curaddr);
 433                 }
 434
 435                 /*
 436                  * Free the name string.
 437                  */
 438                 free(curdev->name);
 439
 440                 /*
 441                  * Free the description string, if any.
 442                  */
 443                 if (curdev->description != NULL)
 444                         free(curdev->description);
 445
 446                 /*
 447                  * Free the interface.
 448                  */
 449                 free(curdev);
 450         }
 451 }
 452
 453 #ifndef WIN32
 454
 455 /*
 456  * Return the name of a network interface attached to the system, or NULL
 457  * if none can be found.  The interface must be configured up; the
 458  * lowest unit number is preferred; loopback is ignored.
 459  */
 460 char *
 461 pcap_lookupdev(errbuf)
 462         register char *errbuf;
 463 {
 464         pcap_if_t *alldevs;
 465 /* for old BSD systems, including bsdi3 */
 466 #ifndef IF_NAMESIZE
 467 #define IF_NAMESIZE IFNAMSIZ
 468 #endif
 469         static char device[IF_NAMESIZE + 1];
 470         char *ret;
 471
 472         if (pcap_findalldevs(&alldevs, errbuf) == -1)
 473                 return (NULL);
 474
 475         if (alldevs == NULL || (alldevs->flags & PCAP_IF_LOOPBACK)) {
 476                 /*
 477                  * There are no devices on the list, or the first device
 478                  * on the list is a loopback device, which means there
 479                  * are no non-loopback devices on the list.  This means
 480                  * we can't return any device.
 481                  *
 482                  * XXX - why not return a loopback device?  If we can't
 483                  * capture on it, it won't be on the list, and if it's
 484                  * on the list, there aren't any non-loopback devices,
 485                  * so why not just supply it as the default device?
 486                  */
 487                 (void)strlcpy(errbuf, "no suitable device found",
 488                     PCAP_ERRBUF_SIZE);
 489                 ret = NULL;
 490         } else {
 491                 /*
 492                  * Return the name of the first device on the list.
 493                  */
 494                 (void)strlcpy(device, alldevs->name, sizeof(device));
 495                 ret = device;
 496         }
 497
 498         pcap_freealldevs(alldevs);
 499         return (ret);
 500 }
 501
 502 int
 503 pcap_lookupnet(device, netp, maskp, errbuf)
 504         register const char *device;
 505         register bpf_u_int32 *netp, *maskp;
 506         register char *errbuf;
 507 {
 508         register int fd;
 509         register struct sockaddr_in *sin;
 510         struct ifreq ifr;
 511
 512         /*
 513          * The pseudo-device "any" listens on all interfaces and therefore
 514          * has the network address and -mask "0.0.0.0" therefore catching
 515          * all traffic. Using NULL for the interface is the same as "any".
 516          */
 517         if (!device || strcmp(device, "any") == 0
 518 #ifdef HAVE_DAG_API
 519             || strstr(device, "dag") != NULL
 520 #endif
 521             ) {
 522                 *netp = *maskp = 0;
 523                 return 0;
 524         }
 525
 526         fd = socket(AF_INET, SOCK_DGRAM, 0);
 527         if (fd < 0) {
 528                 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, "socket: %s",
 529                     pcap_strerror(errno));
 530                 return (-1);
 531         }
 532         memset(&ifr, 0, sizeof(ifr));
 533 #ifdef linux
 534         /* XXX Work around Linux kernel bug */
 535         ifr.ifr_addr.sa_family = AF_INET;
 536 #endif
 537         (void)strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
 538         if (ioctl(fd, SIOCGIFADDR, (char *)&ifr) < 0) {
 539                 if (errno == EADDRNOTAVAIL) {
 540                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 541                             "%s: no IPv4 address assigned", device);
 542                 } else {
 543                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 544                             "SIOCGIFADDR: %s: %s",
 545                             device, pcap_strerror(errno));
 546                 }
 547                 (void)close(fd);
 548                 return (-1);
 549         }
 550         sin = (struct sockaddr_in *)&ifr.ifr_addr;
 551         *netp = sin->sin_addr.s_addr;
 552         if (ioctl(fd, SIOCGIFNETMASK, (char *)&ifr) < 0) {
 553                 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 554                     "SIOCGIFNETMASK: %s: %s", device, pcap_strerror(errno));
 555                 (void)close(fd);
 556                 return (-1);
 557         }
 558         (void)close(fd);
 559         *maskp = sin->sin_addr.s_addr;
 560         if (*maskp == 0) {
 561                 if (IN_CLASSA(*netp))
 562                         *maskp = IN_CLASSA_NET;
 563                 else if (IN_CLASSB(*netp))
 564                         *maskp = IN_CLASSB_NET;
 565                 else if (IN_CLASSC(*netp))
 566                         *maskp = IN_CLASSC_NET;
 567                 else {
 568                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 569                             "inet class for 0x%x unknown", *netp);
 570                         return (-1);
 571                 }
 572         }
 573         *netp &= *maskp;
 574         return (0);
 575 }
 576
 577 #else /* WIN32 */
 578
 579 /*
 580  * Return the name of a network interface attached to the system, or NULL
 581  * if none can be found.  The interface must be configured up; the
 582  * lowest unit number is preferred; loopback is ignored.
 583  */
 584 char *
 585 pcap_lookupdev(errbuf)
 586         register char *errbuf;
 587 {
 588         DWORD dwVersion;
 589         DWORD dwWindowsMajorVersion;
 590         dwVersion = GetVersion();       /* get the OS version */
 591         dwWindowsMajorVersion = (DWORD)(LOBYTE(LOWORD(dwVersion)));
 592
 593         if (dwVersion >= 0x80000000 && dwWindowsMajorVersion >= 4) {
 594                 /*
 595                  * Windows 95, 98, ME.
 596                  */
 597                 ULONG NameLength = 8192;
 598                 static char AdaptersName[8192];
 599
 600                 PacketGetAdapterNames(AdaptersName,&NameLength);
 601
 602                 return (AdaptersName);
 603         } else {
 604                 /*
 605                  * Windows NT (NT 4.0, W2K, WXP). Convert the names to UNICODE for backward compatibility
 606                  */
 607                 ULONG NameLength = 8192;
 608                 static WCHAR AdaptersName[8192];
 609                 char *tAstr;
 610                 WCHAR *tUstr;
 611                 WCHAR *TAdaptersName = (WCHAR*)malloc(8192 * sizeof(WCHAR));
 612                 int NAdapts = 0;
 613
 614                 if(TAdaptersName == NULL)
 615                 {
 616                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, "memory allocation failure");
 617                         return NULL;
 618                 }
 619
 620                 PacketGetAdapterNames((PTSTR)TAdaptersName,&NameLength);
 621
 622                 tAstr = (char*)TAdaptersName;
 623                 tUstr = (WCHAR*)AdaptersName;
 624
 625                 /*
 626                  * Convert and copy the device names
 627                  */
 628                 while(sscanf(tAstr, "%S", tUstr) > 0)
 629                 {
 630                         tAstr += strlen(tAstr) + 1;
 631                         tUstr += wcslen(tUstr) + 1;
 632                         NAdapts ++;
 633                 }
 634
 635                 tAstr++;
 636                 *tUstr = 0;
 637                 tUstr++;
 638
 639                 /*
 640                  * Copy the descriptions
 641                  */
 642                 while(NAdapts--)
 643                 {
 644                         strcpy((char*)tUstr, tAstr);
 645                         (char*)tUstr += strlen(tAstr) + 1;;
 646                         tAstr += strlen(tAstr) + 1;
 647                 }
 648
 649                 return (char *)(AdaptersName);
 650         }
 651 }
 652
 653
 654 int
 655 pcap_lookupnet(device, netp, maskp, errbuf)
 656         const register char *device;
 657         register bpf_u_int32 *netp, *maskp;
 658         register char *errbuf;
 659 {
 660         /*
 661          * We need only the first IPv4 address, so we must scan the array returned by PacketGetNetInfo()
 662          * in order to skip non IPv4 (i.e. IPv6 addresses)
 663          */
 664         npf_if_addr if_addrs[MAX_NETWORK_ADDRESSES];
 665         LONG if_addr_size = 1;
 666         struct sockaddr_in *t_addr;
 667         unsigned int i;
 668
 669         if (!PacketGetNetInfoEx((void *)device, if_addrs, &if_addr_size)) {
 670                 *netp = *maskp = 0;
 671                 return (0);
 672         }
 673
 674         for(i=0; i<MAX_NETWORK_ADDRESSES; i++)
 675         {
 676                 if(if_addrs[i].IPAddress.ss_family == AF_INET)
 677                 {
 678                         t_addr = (struct sockaddr_in *) &(if_addrs[i].IPAddress);
 679                         *netp = t_addr->sin_addr.S_un.S_addr;
 680                         t_addr = (struct sockaddr_in *) &(if_addrs[i].SubnetMask);
 681                         *maskp = t_addr->sin_addr.S_un.S_addr;
 682
 683                         *netp &= *maskp;
 684                         return (0);
 685                 }
 686
 687         }
 688
 689         *netp = *maskp = 0;
 690         return (0);
 691 }
 692
 693 #endif /* WIN32 */