The Tcpdump Group git mirrors - libpcap/blob - inet.c

   1 /*
   2  * Copyright (c) 1994, 1995, 1996, 1997, 1998
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the Computer Systems
  16  *      Engineering Group at Lawrence Berkeley Laboratory.
  17  * 4. Neither the name of the University nor of the Laboratory may be used
  18  *    to endorse or promote products derived from this software without
  19  *    specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 #ifndef lint
  35 static const char rcsid[] =
  36     "@(#) $Header: /tcpdump/master/libpcap/inet.c,v 1.29 2000-04-13 04:58:09 itojun Exp $ (LBL)";
  37 #endif
  38
  39 #include <sys/param.h>
  40 #include <sys/file.h>
  41 #include <sys/ioctl.h>
  42 #include <sys/socket.h>
  43 #ifdef HAVE_SYS_SOCKIO_H
  44 #include <sys/sockio.h>
  45 #endif
  46 #include <sys/time.h>                           /* concession to AIX */
  47
  48 #if __STDC__
  49 struct mbuf;
  50 struct rtentry;
  51 #endif
  52
  53 #include <net/if.h>
  54 #include <netinet/in.h>
  55
  56 #include <ctype.h>
  57 #include <errno.h>
  58 #include <memory.h>
  59 #include <stdio.h>
  60 #include <stdlib.h>
  61 #include <string.h>
  62 #include <unistd.h>
  63 #ifdef HAVE_IFADDRS_H
  64 #include <ifaddrs.h>
  65 #endif
  66
  67 #include "pcap-int.h"
  68
  69 #include "gnuc.h"
  70 #ifdef HAVE_OS_PROTO_H
  71 #include "os-proto.h"
  72 #endif
  73
  74 /* Not all systems have IFF_LOOPBACK */
  75 #ifdef IFF_LOOPBACK
  76 #define ISLOOPBACK(p) ((p)->ifr_flags & IFF_LOOPBACK)
  77 #else
  78 #define ISLOOPBACK(p) ((p)->ifr_name[0] == 'l' && (p)->ifr_name[1] == 'o' && \
  79     (isdigit((p)->ifr_name[2]) || (p)->ifr_name[2] == '\0'))
  80 #endif
  81
  82 /*
  83  * Return the name of a network interface attached to the system, or NULL
  84  * if none can be found.  The interface must be configured up; the
  85  * lowest unit number is preferred; loopback is ignored.
  86  */
  87 char *
  88 pcap_lookupdev(errbuf)
  89         register char *errbuf;
  90 {
  91 #ifdef HAVE_IFADDRS_H
  92         struct ifaddrs *ifap, *ifa, *mp;
  93         int n, minunit;
  94         char *cp;
  95         static char device[IF_NAMESIZE + 1];
  96
  97         if (getifaddrs(&ifap) != 0) {
  98                 (void)sprintf(errbuf, "getifaddrs: %s", pcap_strerror(errno));
  99                 return NULL;
 100         }
 101
 102         mp = NULL;
 103         minunit = 666;
 104         for (ifa = ifap; ifa; ifa = ifa->ifa_next) {
 105                 if ((ifa->ifa_flags & IFF_UP) == 0)
 106                         continue;
 107 #ifdef IFF_LOOPBACK
 108                 if ((ifa->ifa_flags & IFF_LOOPBACK) != 0)
 109                         continue;
 110 #else
 111                 if (strncmp(ifa->ifa_name, "lo", 2) == 0 &&
 112                     (ifa->ifa_name[2] == '\0' || isdigit(ifa->ifa_name[2]))) {
 113                         continue;
 114                 }
 115 #endif
 116
 117                 for (cp = ifa->ifa_name; !isdigit(*cp); ++cp)
 118                         continue;
 119                 n = atoi(cp);
 120                 if (n < minunit) {
 121                         minunit = n;
 122                         mp = ifa;
 123                 }
 124         }
 125         if (mp == NULL) {
 126                 (void)strcpy(errbuf, "no suitable device found");
 127                 free(ifap);
 128                 return (NULL);
 129         }
 130
 131         (void)strncpy(device, mp->ifa_name, sizeof(device) - 1);
 132         device[sizeof(device) - 1] = '\0';
 133         free(ifap);
 134         return (device);
 135 #else
 136         register int fd, minunit, n;
 137         register char *cp;
 138         register struct ifreq *ifrp, *ifend, *ifnext, *mp;
 139         struct ifconf ifc;
 140         char *buf;
 141         struct ifreq ifr;
 142         static char device[sizeof(ifrp->ifr_name) + 1];
 143         unsigned buf_size;
 144
 145         fd = socket(AF_INET, SOCK_DGRAM, 0);
 146         if (fd < 0) {
 147                 (void)sprintf(errbuf, "socket: %s", pcap_strerror(errno));
 148                 return (NULL);
 149         }
 150
 151         buf_size = 8192;
 152
 153         for (;;) {
 154                 buf = malloc (buf_size);
 155                 if (buf == NULL) {
 156                         close (fd);
 157                         (void)sprintf(errbuf, "out of memory");
 158                         return (NULL);
 159                 }
 160
 161                 ifc.ifc_len = buf_size;
 162                 ifc.ifc_buf = buf;
 163                 memset (buf, 0, buf_size);
 164                 if (ioctl(fd, SIOCGIFCONF, (char *)&ifc) < 0
 165                     && errno != EINVAL) {
 166                         free (buf);
 167                         (void)sprintf(errbuf, "SIOCGIFCONF: %s",
 168                                       pcap_strerror(errno));
 169                         (void)close(fd);
 170                         return (NULL);
 171                 }
 172                 if (ifc.ifc_len < buf_size)
 173                         break;
 174                 free (buf);
 175                 buf_size *= 2;
 176         }
 177
 178         ifrp = (struct ifreq *)buf;
 179         ifend = (struct ifreq *)(buf + ifc.ifc_len);
 180
 181         mp = NULL;
 182         minunit = 666;
 183         for (; ifrp < ifend; ifrp = ifnext) {
 184 #ifdef HAVE_SOCKADDR_SA_LEN
 185                 n = ifrp->ifr_addr.sa_len + sizeof(ifrp->ifr_name);
 186                 if (n < sizeof(*ifrp))
 187                         ifnext = ifrp + 1;
 188                 else
 189                         ifnext = (struct ifreq *)((char *)ifrp + n);
 190                 if (ifrp->ifr_addr.sa_family != AF_INET)
 191                         continue;
 192 #else
 193                 ifnext = ifrp + 1;
 194 #endif
 195                 /*
 196                  * Need a template to preserve address info that is
 197                  * used below to locate the next entry.  (Otherwise,
 198                  * SIOCGIFFLAGS stomps over it because the requests
 199                  * are returned in a union.)
 200                  */
 201                 strncpy(ifr.ifr_name, ifrp->ifr_name, sizeof(ifr.ifr_name));
 202                 if (ioctl(fd, SIOCGIFFLAGS, (char *)&ifr) < 0) {
 203                         if (errno == ENXIO)
 204                                 continue;
 205                         (void)sprintf(errbuf, "SIOCGIFFLAGS: %.*s: %s",
 206                             (int)sizeof(ifr.ifr_name), ifr.ifr_name,
 207                             pcap_strerror(errno));
 208                         (void)close(fd);
 209                         free (buf);
 210                         return (NULL);
 211                 }
 212
 213                 /* Must be up and not the loopback */
 214                 if ((ifr.ifr_flags & IFF_UP) == 0 || ISLOOPBACK(&ifr))
 215                         continue;
 216
 217                 for (cp = ifrp->ifr_name; !isdigit(*cp); ++cp)
 218                         continue;
 219                 n = atoi(cp);
 220                 if (n < minunit) {
 221                         minunit = n;
 222                         mp = ifrp;
 223                 }
 224         }
 225         (void)close(fd);
 226         if (mp == NULL) {
 227                 (void)strcpy(errbuf, "no suitable device found");
 228                 free(buf);
 229                 return (NULL);
 230         }
 231
 232         (void)strncpy(device, mp->ifr_name, sizeof(device) - 1);
 233         device[sizeof(device) - 1] = '\0';
 234         free(buf);
 235         return (device);
 236 #endif
 237 }
 238
 239 int
 240 pcap_lookupnet(device, netp, maskp, errbuf)
 241         register char *device;
 242         register bpf_u_int32 *netp, *maskp;
 243         register char *errbuf;
 244 {
 245         register int fd;
 246         register struct sockaddr_in *sin;
 247         struct ifreq ifr;
 248
 249         fd = socket(AF_INET, SOCK_DGRAM, 0);
 250         if (fd < 0) {
 251                 (void)sprintf(errbuf, "socket: %s", pcap_strerror(errno));
 252                 return (-1);
 253         }
 254         memset(&ifr, 0, sizeof(ifr));
 255 #ifdef linux
 256         /* XXX Work around Linux kernel bug */
 257         ifr.ifr_addr.sa_family = AF_INET;
 258 #endif
 259         (void)strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
 260         if (ioctl(fd, SIOCGIFADDR, (char *)&ifr) < 0) {
 261                 if (errno == EADDRNOTAVAIL) {
 262                         (void)sprintf(errbuf, "%s: no IPv4 address assigned",
 263                             device);
 264                 } else {
 265                         (void)sprintf(errbuf, "SIOCGIFADDR: %s: %s",
 266                             device, pcap_strerror(errno));
 267                 }
 268                 (void)close(fd);
 269                 return (-1);
 270         }
 271         sin = (struct sockaddr_in *)&ifr.ifr_addr;
 272         *netp = sin->sin_addr.s_addr;
 273         if (ioctl(fd, SIOCGIFNETMASK, (char *)&ifr) < 0) {
 274                 (void)sprintf(errbuf, "SIOCGIFNETMASK: %s: %s",
 275                     device, pcap_strerror(errno));
 276                 (void)close(fd);
 277                 return (-1);
 278         }
 279         (void)close(fd);
 280         *maskp = sin->sin_addr.s_addr;
 281         if (*maskp == 0) {
 282                 if (IN_CLASSA(*netp))
 283                         *maskp = IN_CLASSA_NET;
 284                 else if (IN_CLASSB(*netp))
 285                         *maskp = IN_CLASSB_NET;
 286                 else if (IN_CLASSC(*netp))
 287                         *maskp = IN_CLASSC_NET;
 288                 else {
 289                         (void)sprintf(errbuf, "inet class for 0x%x unknown",
 290                             *netp);
 291                         return (-1);
 292                 }
 293         }
 294         *netp &= *maskp;
 295         return (0);
 296 }