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 1.57 2003-09-22 11:51:37 risso 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_t *p;
 136         pcap_if_t *curdev, *prevdev, *nextdev;
 137         int this_instance;
 138
 139         /*
 140          * Is there already an entry in the list for this interface?
 141          */
 142         for (curdev = *alldevs; curdev != NULL; curdev = curdev->next) {
 143                 if (strcmp(name, curdev->name) == 0)
 144                         break;  /* yes, we found it */
 145         }
 146         if (curdev == NULL) {
 147                 /*
 148                  * No, we didn't find it.
 149                  * Allocate a new entry.
 150                  */
 151                 curdev = malloc(sizeof(pcap_if_t));
 152                 if (curdev == NULL) {
 153                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 154                             "malloc: %s", pcap_strerror(errno));
 155                         return (-1);
 156                 }
 157
 158                 /*
 159                  * Fill in the entry.
 160                  */
 161                 curdev->next = NULL;
 162                 curdev->name = malloc(strlen(name) + 1);
 163                 strcpy(curdev->name, name);
 164                 if (description != NULL) {
 165                         /*
 166                          * We have a description for this interface.
 167                          */
 168                         curdev->description = malloc(strlen(description) + 1);
 169                         strcpy(curdev->description, description);
 170                 } else {
 171                         /*
 172                          * We don't.
 173                          */
 174                         curdev->description = NULL;
 175                 }
 176                 curdev->addresses = NULL;       /* list starts out as empty */
 177                 curdev->flags = 0;
 178                 if (ISLOOPBACK(name, flags))
 179                         curdev->flags |= PCAP_IF_LOOPBACK;
 180
 181                 /*
 182                  * Add it to the list, in the appropriate location.
 183                  * First, get the instance number of this interface.
 184                  */
 185                 this_instance = get_instance(name);
 186
 187                 /*
 188                  * Now look for the last interface with an instance number
 189                  * less than or equal to the new interface's instance
 190                  * number - except that non-loopback interfaces are
 191                  * arbitrarily treated as having interface numbers less
 192                  * than those of loopback interfaces, so the loopback
 193                  * interfaces are put at the end of the list.
 194                  *
 195                  * We start with "prevdev" being NULL, meaning we're before
 196                  * the first element in the list.
 197                  */
 198                 prevdev = NULL;
 199                 for (;;) {
 200                         /*
 201                          * Get the interface after this one.
 202                          */
 203                         if (prevdev == NULL) {
 204                                 /*
 205                                  * The next element is the first element.
 206                                  */
 207                                 nextdev = *alldevs;
 208                         } else
 209                                 nextdev = prevdev->next;
 210
 211                         /*
 212                          * Are we at the end of the list?
 213                          */
 214                         if (nextdev == NULL) {
 215                                 /*
 216                                  * Yes - we have to put the new entry
 217                                  * after "prevdev".
 218                                  */
 219                                 break;
 220                         }
 221
 222                         /*
 223                          * Is the new interface a non-loopback interface
 224                          * and the next interface a loopback interface?
 225                          */
 226                         if (!(curdev->flags & PCAP_IF_LOOPBACK) &&
 227                             (nextdev->flags & PCAP_IF_LOOPBACK)) {
 228                                 /*
 229                                  * Yes, we should put the new entry
 230                                  * before "nextdev", i.e. after "prevdev".
 231                                  */
 232                                 break;
 233                         }
 234
 235                         /*
 236                          * Is the new interface's instance number less
 237                          * than the next interface's instance number,
 238                          * and is it the case that the new interface is a
 239                          * non-loopback interface or the next interface is
 240                          * a loopback interface?
 241                          *
 242                          * (The goal of both loopback tests is to make
 243                          * sure that we never put a loopback interface
 244                          * before any non-loopback interface and that we
 245                          * always put a non-loopback interface before all
 246                          * loopback interfaces.)
 247                          */
 248                         if (this_instance < get_instance(nextdev->name) &&
 249                             (!(curdev->flags & PCAP_IF_LOOPBACK) ||
 250                                (nextdev->flags & PCAP_IF_LOOPBACK))) {
 251                                 /*
 252                                  * Yes - we should put the new entry
 253                                  * before "nextdev", i.e. after "prevdev".
 254                                  */
 255                                 break;
 256                         }
 257
 258                         prevdev = nextdev;
 259                 }
 260
 261                 /*
 262                  * Insert before "nextdev".
 263                  */
 264                 curdev->next = nextdev;
 265
 266                 /*
 267                  * Insert after "prevdev" - unless "prevdev" is null,
 268                  * in which case this is the first interface.
 269                  */
 270                 if (prevdev == NULL) {
 271                         /*
 272                          * This is the first interface.  Pass back a
 273                          * pointer to it, and put "curdev" before
 274                          * "nextdev".
 275                          */
 276                         *alldevs = curdev;
 277                 } else
 278                         prevdev->next = curdev;
 279         }
 280
 281         *curdev_ret = curdev;
 282         return (0);
 283 }
 284
 285 int
 286 add_addr_to_iflist(pcap_if_t **alldevs, char *name, u_int flags,
 287     struct sockaddr *addr, size_t addr_size,
 288     struct sockaddr *netmask, size_t netmask_size,
 289     struct sockaddr *broadaddr, size_t broadaddr_size,
 290     struct sockaddr *dstaddr, size_t dstaddr_size,
 291     char *errbuf)
 292 {
 293         pcap_if_t *curdev;
 294         pcap_addr_t *curaddr, *prevaddr, *nextaddr;
 295
 296         if (add_or_find_if(&curdev, alldevs, name, flags, NULL, errbuf) == -1) {
 297                 /*
 298                  * Error - give up.
 299                  */
 300                 return (-1);
 301         }
 302         if (curdev == NULL) {
 303                 /*
 304                  * Device wasn't added because it can't be opened.
 305                  * Not a fatal error.
 306                  */
 307                 return (0);
 308         }
 309
 310         /*
 311          * "curdev" is an entry for this interface; add an entry for this
 312          * address to its list of addresses.
 313          *
 314          * Allocate the new entry and fill it in.
 315          */
 316         curaddr = malloc(sizeof(pcap_addr_t));
 317         if (curaddr == NULL) {
 318                 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 319                     "malloc: %s", pcap_strerror(errno));
 320                 return (-1);
 321         }
 322
 323         curaddr->next = NULL;
 324         if (addr != NULL) {
 325                 curaddr->addr = dup_sockaddr(addr, addr_size);
 326                 if (curaddr->addr == NULL) {
 327                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 328                             "malloc: %s", pcap_strerror(errno));
 329                         free(curaddr);
 330                         return (-1);
 331                 }
 332         } else
 333                 curaddr->addr = NULL;
 334
 335         if (netmask != NULL) {
 336                 curaddr->netmask = dup_sockaddr(netmask, netmask_size);
 337                 if (curaddr->netmask == NULL) {
 338                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 339                             "malloc: %s", pcap_strerror(errno));
 340                         free(curaddr);
 341                         return (-1);
 342                 }
 343         } else
 344                 curaddr->netmask = NULL;
 345
 346         if (broadaddr != NULL) {
 347                 curaddr->broadaddr = dup_sockaddr(broadaddr, broadaddr_size);
 348                 if (curaddr->broadaddr == NULL) {
 349                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 350                             "malloc: %s", pcap_strerror(errno));
 351                         free(curaddr);
 352                         return (-1);
 353                 }
 354         } else
 355                 curaddr->broadaddr = NULL;
 356
 357         if (dstaddr != NULL) {
 358                 curaddr->dstaddr = dup_sockaddr(dstaddr, dstaddr_size);
 359                 if (curaddr->dstaddr == NULL) {
 360                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 361                             "malloc: %s", pcap_strerror(errno));
 362                         free(curaddr);
 363                         return (-1);
 364                 }
 365         } else
 366                 curaddr->dstaddr = NULL;
 367
 368         /*
 369          * Find the end of the list of addresses.
 370          */
 371         for (prevaddr = curdev->addresses; prevaddr != NULL; prevaddr = nextaddr) {
 372                 nextaddr = prevaddr->next;
 373                 if (nextaddr == NULL) {
 374                         /*
 375                          * This is the end of the list.
 376                          */
 377                         break;
 378                 }
 379         }
 380
 381         if (prevaddr == NULL) {
 382                 /*
 383                  * The list was empty; this is the first member.
 384                  */
 385                 curdev->addresses = curaddr;
 386         } else {
 387                 /*
 388                  * "prevaddr" is the last member of the list; append
 389                  * this member to it.
 390                  */
 391                 prevaddr->next = curaddr;
 392         }
 393
 394         return (0);
 395 }
 396
 397 int
 398 pcap_add_if(pcap_if_t **devlist, char *name, u_int flags,
 399     const char *description, char *errbuf)
 400 {
 401         pcap_if_t *curdev;
 402
 403         return (add_or_find_if(&curdev, devlist, name, flags, description,
 404             errbuf));
 405 }
 406
 407
 408 /*
 409  * Free a list of interfaces.
 410  */
 411 void
 412 pcap_freealldevs(pcap_if_t *alldevs)
 413 {
 414         pcap_if_t *curdev, *nextdev;
 415         pcap_addr_t *curaddr, *nextaddr;
 416
 417         for (curdev = alldevs; curdev != NULL; curdev = nextdev) {
 418                 nextdev = curdev->next;
 419
 420                 /*
 421                  * Free all addresses.
 422                  */
 423                 for (curaddr = curdev->addresses; curaddr != NULL; curaddr = nextaddr) {
 424                         nextaddr = curaddr->next;
 425                         if (curaddr->addr)
 426                                 free(curaddr->addr);
 427                         if (curaddr->netmask)
 428                                 free(curaddr->netmask);
 429                         if (curaddr->broadaddr)
 430                                 free(curaddr->broadaddr);
 431                         if (curaddr->dstaddr)
 432                                 free(curaddr->dstaddr);
 433                         free(curaddr);
 434                 }
 435
 436                 /*
 437                  * Free the name string.
 438                  */
 439                 free(curdev->name);
 440
 441                 /*
 442                  * Free the description string, if any.
 443                  */
 444                 if (curdev->description != NULL)
 445                         free(curdev->description);
 446
 447                 /*
 448                  * Free the interface.
 449                  */
 450                 free(curdev);
 451         }
 452 }
 453
 454 #ifndef WIN32
 455
 456 /*
 457  * Return the name of a network interface attached to the system, or NULL
 458  * if none can be found.  The interface must be configured up; the
 459  * lowest unit number is preferred; loopback is ignored.
 460  */
 461 char *
 462 pcap_lookupdev(errbuf)
 463         register char *errbuf;
 464 {
 465         pcap_if_t *alldevs;
 466 /* for old BSD systems, including bsdi3 */
 467 #ifndef IF_NAMESIZE
 468 #define IF_NAMESIZE IFNAMSIZ
 469 #endif
 470         static char device[IF_NAMESIZE + 1];
 471         char *ret;
 472
 473         if (pcap_findalldevs(&alldevs, errbuf) == -1)
 474                 return (NULL);
 475
 476         if (alldevs == NULL || (alldevs->flags & PCAP_IF_LOOPBACK)) {
 477                 /*
 478                  * There are no devices on the list, or the first device
 479                  * on the list is a loopback device, which means there
 480                  * are no non-loopback devices on the list.  This means
 481                  * we can't return any device.
 482                  *
 483                  * XXX - why not return a loopback device?  If we can't
 484                  * capture on it, it won't be on the list, and if it's
 485                  * on the list, there aren't any non-loopback devices,
 486                  * so why not just supply it as the default device?
 487                  */
 488                 (void)strlcpy(errbuf, "no suitable device found",
 489                     PCAP_ERRBUF_SIZE);
 490                 ret = NULL;
 491         } else {
 492                 /*
 493                  * Return the name of the first device on the list.
 494                  */
 495                 (void)strlcpy(device, alldevs->name, sizeof(device));
 496                 ret = device;
 497         }
 498
 499         pcap_freealldevs(alldevs);
 500         return (ret);
 501 }
 502
 503 int
 504 pcap_lookupnet(device, netp, maskp, errbuf)
 505         register const char *device;
 506         register bpf_u_int32 *netp, *maskp;
 507         register char *errbuf;
 508 {
 509         register int fd;
 510         register struct sockaddr_in *sin;
 511         struct ifreq ifr;
 512
 513         /*
 514          * The pseudo-device "any" listens on all interfaces and therefore
 515          * has the network address and -mask "0.0.0.0" therefore catching
 516          * all traffic. Using NULL for the interface is the same as "any".
 517          */
 518         if (!device || strcmp(device, "any") == 0
 519 #ifdef HAVE_DAG_API
 520             || strstr(device, "dag") != NULL
 521 #endif
 522             ) {
 523                 *netp = *maskp = 0;
 524                 return 0;
 525         }
 526
 527         fd = socket(AF_INET, SOCK_DGRAM, 0);
 528         if (fd < 0) {
 529                 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, "socket: %s",
 530                     pcap_strerror(errno));
 531                 return (-1);
 532         }
 533         memset(&ifr, 0, sizeof(ifr));
 534 #ifdef linux
 535         /* XXX Work around Linux kernel bug */
 536         ifr.ifr_addr.sa_family = AF_INET;
 537 #endif
 538         (void)strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
 539         if (ioctl(fd, SIOCGIFADDR, (char *)&ifr) < 0) {
 540                 if (errno == EADDRNOTAVAIL) {
 541                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 542                             "%s: no IPv4 address assigned", device);
 543                 } else {
 544                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 545                             "SIOCGIFADDR: %s: %s",
 546                             device, pcap_strerror(errno));
 547                 }
 548                 (void)close(fd);
 549                 return (-1);
 550         }
 551         sin = (struct sockaddr_in *)&ifr.ifr_addr;
 552         *netp = sin->sin_addr.s_addr;
 553         if (ioctl(fd, SIOCGIFNETMASK, (char *)&ifr) < 0) {
 554                 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 555                     "SIOCGIFNETMASK: %s: %s", device, pcap_strerror(errno));
 556                 (void)close(fd);
 557                 return (-1);
 558         }
 559         (void)close(fd);
 560         *maskp = sin->sin_addr.s_addr;
 561         if (*maskp == 0) {
 562                 if (IN_CLASSA(*netp))
 563                         *maskp = IN_CLASSA_NET;
 564                 else if (IN_CLASSB(*netp))
 565                         *maskp = IN_CLASSB_NET;
 566                 else if (IN_CLASSC(*netp))
 567                         *maskp = IN_CLASSC_NET;
 568                 else {
 569                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 570                             "inet class for 0x%x unknown", *netp);
 571                         return (-1);
 572                 }
 573         }
 574         *netp &= *maskp;
 575         return (0);
 576 }
 577
 578 #else /* WIN32 */
 579
 580 /*
 581  * Return the name of a network interface attached to the system, or NULL
 582  * if none can be found.  The interface must be configured up; the
 583  * lowest unit number is preferred; loopback is ignored.
 584  */
 585 char *
 586 pcap_lookupdev(errbuf)
 587         register char *errbuf;
 588 {
 589         DWORD dwVersion;
 590         DWORD dwWindowsMajorVersion;
 591         dwVersion = GetVersion();       /* get the OS version */
 592         dwWindowsMajorVersion = (DWORD)(LOBYTE(LOWORD(dwVersion)));
 593
 594         if (dwVersion >= 0x80000000 && dwWindowsMajorVersion >= 4) {
 595                 /*
 596                  * Windows 95, 98, ME.
 597                  */
 598                 ULONG NameLength = 8192;
 599                 static char AdaptersName[8192];
 600
 601                 PacketGetAdapterNames(AdaptersName,&NameLength);
 602
 603                 return (AdaptersName);
 604         } else {
 605                 /*
 606                  * Windows NT (NT 4.0, W2K, WXP). Convert the names to UNICODE for backward compatibility
 607                  */
 608                 ULONG NameLength = 8192;
 609                 static WCHAR AdaptersName[8192];
 610                 char *tAstr;
 611                 WCHAR *tUstr;
 612                 WCHAR *TAdaptersName = (WCHAR*)malloc(8192 * sizeof(WCHAR));
 613                 int NAdapts = 0;
 614
 615                 if(TAdaptersName == NULL)
 616                 {
 617                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, "memory allocation failure");
 618                         return NULL;
 619                 }
 620
 621                 PacketGetAdapterNames((PTSTR)TAdaptersName,&NameLength);
 622
 623                 tAstr = (char*)TAdaptersName;
 624                 tUstr = (WCHAR*)AdaptersName;
 625
 626                 /*
 627                  * Convert and copy the device names
 628                  */
 629                 while(sscanf(tAstr, "%S", tUstr) > 0)
 630                 {
 631                         tAstr += strlen(tAstr) + 1;
 632                         tUstr += wcslen(tUstr) + 1;
 633                         NAdapts ++;
 634                 }
 635
 636                 tAstr++;
 637                 *tUstr = 0;
 638                 tUstr++;
 639
 640                 /*
 641                  * Copy the descriptions
 642                  */
 643                 while(NAdapts--)
 644                 {
 645                         strcpy((char*)tUstr, tAstr);
 646                         (char*)tUstr += strlen(tAstr) + 1;;
 647                         tAstr += strlen(tAstr) + 1;
 648                 }
 649
 650                 return (char *)(AdaptersName);
 651         }
 652 }
 653
 654
 655 int
 656 pcap_lookupnet(device, netp, maskp, errbuf)
 657         const register char *device;
 658         register bpf_u_int32 *netp, *maskp;
 659         register char *errbuf;
 660 {
 661         /*
 662          * We need only the first IPv4 address, so we must scan the array returned by PacketGetNetInfo()
 663          * in order to skip non IPv4 (i.e. IPv6 addresses)
 664          */
 665         npf_if_addr if_addrs[MAX_NETWORK_ADDRESSES];
 666         LONG if_addr_size = 1;
 667         struct sockaddr_in *t_addr;
 668         unsigned int i;
 669
 670         if (!PacketGetNetInfoEx((void *)device, if_addrs, &if_addr_size)) {
 671                 *netp = *maskp = 0;
 672                 return (0);
 673         }
 674
 675         for(i=0; i<MAX_NETWORK_ADDRESSES; i++)
 676         {
 677                 if(if_addrs[i].IPAddress.ss_family == AF_INET)
 678                 {
 679                         t_addr = (struct sockaddr_in *) &(if_addrs[i].IPAddress);
 680                         *netp = t_addr->sin_addr.S_un.S_addr;
 681                         t_addr = (struct sockaddr_in *) &(if_addrs[i].SubnetMask);
 682                         *maskp = t_addr->sin_addr.S_un.S_addr;
 683
 684                         *netp &= *maskp;
 685                         return (0);
 686                 }
 687
 688         }
 689
 690         *netp = *maskp = 0;
 691         return (0);
 692 }
 693
 694 #endif /* WIN32 */