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 1.28 2000-04-09 20:59:31 assar 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 (strcmp(ifa->ifa_name, "lo0") == 0)
 112                         continue;
 113 #endif
 114
 115                 for (cp = ifa->ifa_name; !isdigit(*cp); ++cp)
 116                         continue;
 117                 n = atoi(cp);
 118                 if (n < minunit) {
 119                         minunit = n;
 120                         mp = ifa;
 121                 }
 122         }
 123         if (mp == NULL) {
 124                 (void)strcpy(errbuf, "no suitable device found");
 125                 free(ifap);
 126                 return (NULL);
 127         }
 128
 129         (void)strncpy(device, mp->ifa_name, sizeof(device) - 1);
 130         device[sizeof(device) - 1] = '\0';
 131         free(ifap);
 132         return (device);
 133 #else
 134         register int fd, minunit, n;
 135         register char *cp;
 136         register struct ifreq *ifrp, *ifend, *ifnext, *mp;
 137         struct ifconf ifc;
 138         char *buf;
 139         struct ifreq ifr;
 140         static char device[sizeof(ifrp->ifr_name) + 1];
 141         unsigned buf_size;
 142
 143         fd = socket(AF_INET, SOCK_DGRAM, 0);
 144         if (fd < 0) {
 145                 (void)sprintf(errbuf, "socket: %s", pcap_strerror(errno));
 146                 return (NULL);
 147         }
 148
 149         buf_size = 8192;
 150
 151         for (;;) {
 152                 buf = malloc (buf_size);
 153                 if (buf == NULL) {
 154                         close (fd);
 155                         (void)sprintf(errbuf, "out of memory");
 156                         return (NULL);
 157                 }
 158
 159                 ifc.ifc_len = buf_size;
 160                 ifc.ifc_buf = buf;
 161                 memset (buf, 0, buf_size);
 162                 if (ioctl(fd, SIOCGIFCONF, (char *)&ifc) < 0
 163                     && errno != EINVAL) {
 164                         free (buf);
 165                         (void)sprintf(errbuf, "SIOCGIFCONF: %s",
 166                                       pcap_strerror(errno));
 167                         (void)close(fd);
 168                         return (NULL);
 169                 }
 170                 if (ifc.ifc_len < buf_size)
 171                         break;
 172                 free (buf);
 173                 buf_size *= 2;
 174         }
 175
 176         ifrp = (struct ifreq *)buf;
 177         ifend = (struct ifreq *)(buf + ifc.ifc_len);
 178
 179         mp = NULL;
 180         minunit = 666;
 181         for (; ifrp < ifend; ifrp = ifnext) {
 182 #ifdef HAVE_SOCKADDR_SA_LEN
 183                 n = ifrp->ifr_addr.sa_len + sizeof(ifrp->ifr_name);
 184                 if (n < sizeof(*ifrp))
 185                         ifnext = ifrp + 1;
 186                 else
 187                         ifnext = (struct ifreq *)((char *)ifrp + n);
 188                 if (ifrp->ifr_addr.sa_family != AF_INET)
 189                         continue;
 190 #else
 191                 ifnext = ifrp + 1;
 192 #endif
 193                 /*
 194                  * Need a template to preserve address info that is
 195                  * used below to locate the next entry.  (Otherwise,
 196                  * SIOCGIFFLAGS stomps over it because the requests
 197                  * are returned in a union.)
 198                  */
 199                 strncpy(ifr.ifr_name, ifrp->ifr_name, sizeof(ifr.ifr_name));
 200                 if (ioctl(fd, SIOCGIFFLAGS, (char *)&ifr) < 0) {
 201                         if (errno == ENXIO)
 202                                 continue;
 203                         (void)sprintf(errbuf, "SIOCGIFFLAGS: %.*s: %s",
 204                             (int)sizeof(ifr.ifr_name), ifr.ifr_name,
 205                             pcap_strerror(errno));
 206                         (void)close(fd);
 207                         free (buf);
 208                         return (NULL);
 209                 }
 210
 211                 /* Must be up and not the loopback */
 212                 if ((ifr.ifr_flags & IFF_UP) == 0 || ISLOOPBACK(&ifr))
 213                         continue;
 214
 215                 for (cp = ifrp->ifr_name; !isdigit(*cp); ++cp)
 216                         continue;
 217                 n = atoi(cp);
 218                 if (n < minunit) {
 219                         minunit = n;
 220                         mp = ifrp;
 221                 }
 222         }
 223         (void)close(fd);
 224         if (mp == NULL) {
 225                 (void)strcpy(errbuf, "no suitable device found");
 226                 free(buf);
 227                 return (NULL);
 228         }
 229
 230         (void)strncpy(device, mp->ifr_name, sizeof(device) - 1);
 231         device[sizeof(device) - 1] = '\0';
 232         free(buf);
 233         return (device);
 234 #endif
 235 }
 236
 237 int
 238 pcap_lookupnet(device, netp, maskp, errbuf)
 239         register char *device;
 240         register bpf_u_int32 *netp, *maskp;
 241         register char *errbuf;
 242 {
 243         register int fd;
 244         register struct sockaddr_in *sin;
 245         struct ifreq ifr;
 246
 247         fd = socket(AF_INET, SOCK_DGRAM, 0);
 248         if (fd < 0) {
 249                 (void)sprintf(errbuf, "socket: %s", pcap_strerror(errno));
 250                 return (-1);
 251         }
 252         memset(&ifr, 0, sizeof(ifr));
 253 #ifdef linux
 254         /* XXX Work around Linux kernel bug */
 255         ifr.ifr_addr.sa_family = AF_INET;
 256 #endif
 257         (void)strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
 258         if (ioctl(fd, SIOCGIFADDR, (char *)&ifr) < 0) {
 259                 if (errno == EADDRNOTAVAIL) {
 260                         (void)sprintf(errbuf, "%s: no IPv4 address assigned",
 261                             device);
 262                 } else {
 263                         (void)sprintf(errbuf, "SIOCGIFADDR: %s: %s",
 264                             device, pcap_strerror(errno));
 265                 }
 266                 (void)close(fd);
 267                 return (-1);
 268         }
 269         sin = (struct sockaddr_in *)&ifr.ifr_addr;
 270         *netp = sin->sin_addr.s_addr;
 271         if (ioctl(fd, SIOCGIFNETMASK, (char *)&ifr) < 0) {
 272                 (void)sprintf(errbuf, "SIOCGIFNETMASK: %s: %s",
 273                     device, pcap_strerror(errno));
 274                 (void)close(fd);
 275                 return (-1);
 276         }
 277         (void)close(fd);
 278         *maskp = sin->sin_addr.s_addr;
 279         if (*maskp == 0) {
 280                 if (IN_CLASSA(*netp))
 281                         *maskp = IN_CLASSA_NET;
 282                 else if (IN_CLASSB(*netp))
 283                         *maskp = IN_CLASSB_NET;
 284                 else if (IN_CLASSC(*netp))
 285                         *maskp = IN_CLASSC_NET;
 286                 else {
 287                         (void)sprintf(errbuf, "inet class for 0x%x unknown",
 288                             *netp);
 289                         return (-1);
 290                 }
 291         }
 292         *netp &= *maskp;
 293         return (0);
 294 }