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 1.25 2000-01-13 17:08:59 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
  64 #include "pcap-int.h"
  65
  66 #include "gnuc.h"
  67 #ifdef HAVE_OS_PROTO_H
  68 #include "os-proto.h"
  69 #endif
  70
  71 /* Not all systems have IFF_LOOPBACK */
  72 #ifdef IFF_LOOPBACK
  73 #define ISLOOPBACK(p) ((p)->ifr_flags & IFF_LOOPBACK)
  74 #else
  75 #define ISLOOPBACK(p) ((p)->ifr_name[0] == 'l' && (p)->ifr_name[1] == 'o' && \
  76     (isdigit((p)->ifr_name[2]) || (p)->ifr_name[2] == '\0'))
  77 #endif
  78
  79 /*
  80  * Return the name of a network interface attached to the system, or NULL
  81  * if none can be found.  The interface must be configured up; the
  82  * lowest unit number is preferred; loopback is ignored.
  83  */
  84 char *
  85 pcap_lookupdev(errbuf)
  86         register char *errbuf;
  87 {
  88         register int fd, minunit, n;
  89         register char *cp;
  90         register struct ifreq *ifrp, *ifend, *ifnext, *mp;
  91         struct ifconf ifc;
  92         char *buf;
  93         struct ifreq ifr;
  94         static char device[sizeof(ifrp->ifr_name) + 1];
  95         unsigned buf_size;
  96
  97         fd = socket(AF_INET, SOCK_DGRAM, 0);
  98         if (fd < 0) {
  99                 (void)sprintf(errbuf, "socket: %s", pcap_strerror(errno));
 100                 return (NULL);
 101         }
 102
 103         buf_size = 8192;
 104
 105         for (;;) {
 106                 buf = malloc (buf_size);
 107                 if (buf == NULL) {
 108                         close (fd);
 109                         (void)sprintf(errbuf, "out of memory");
 110                         return (NULL);
 111                 }
 112
 113                 ifc.ifc_len = buf_size;
 114                 ifc.ifc_buf = buf;
 115                 memset (buf, 0, buf_size);
 116                 if (ioctl(fd, SIOCGIFCONF, (char *)&ifc) < 0) {
 117                         free (buf);
 118                         (void)sprintf(errbuf, "SIOCGIFCONF: %s",
 119                                       pcap_strerror(errno));
 120                         (void)close(fd);
 121                         return (NULL);
 122                 }
 123                 if (ifc.ifc_len < buf_size)
 124                         break;
 125                 free (buf);
 126                 buf_size *= 2;
 127         }
 128
 129         ifrp = (struct ifreq *)buf;
 130         ifend = (struct ifreq *)(buf + ifc.ifc_len);
 131
 132         mp = NULL;
 133         minunit = 666;
 134         for (; ifrp < ifend; ifrp = ifnext) {
 135 #ifdef HAVE_SOCKADDR_SA_LEN
 136                 n = ifrp->ifr_addr.sa_len + sizeof(ifrp->ifr_name);
 137                 if (n < sizeof(*ifrp))
 138                         ifnext = ifrp + 1;
 139                 else
 140                         ifnext = (struct ifreq *)((char *)ifrp + n);
 141                 if (ifrp->ifr_addr.sa_family != AF_INET)
 142                         continue;
 143 #else
 144                 ifnext = ifrp + 1;
 145 #endif
 146                 /*
 147                  * Need a template to preserve address info that is
 148                  * used below to locate the next entry.  (Otherwise,
 149                  * SIOCGIFFLAGS stomps over it because the requests
 150                  * are returned in a union.)
 151                  */
 152                 strncpy(ifr.ifr_name, ifrp->ifr_name, sizeof(ifr.ifr_name));
 153                 if (ioctl(fd, SIOCGIFFLAGS, (char *)&ifr) < 0) {
 154                         if (errno == ENXIO)
 155                                 continue;
 156                         (void)sprintf(errbuf, "SIOCGIFFLAGS: %.*s: %s",
 157                             (int)sizeof(ifr.ifr_name), ifr.ifr_name,
 158                             pcap_strerror(errno));
 159                         (void)close(fd);
 160                         free (buf);
 161                         return (NULL);
 162                 }
 163
 164                 /* Must be up and not the loopback */
 165                 if ((ifr.ifr_flags & IFF_UP) == 0 || ISLOOPBACK(&ifr))
 166                         continue;
 167
 168                 for (cp = ifrp->ifr_name; !isdigit(*cp); ++cp)
 169                         continue;
 170                 n = atoi(cp);
 171                 if (n < minunit) {
 172                         minunit = n;
 173                         mp = ifrp;
 174                 }
 175         }
 176         free(buf);
 177         (void)close(fd);
 178         if (mp == NULL) {
 179                 (void)strcpy(errbuf, "no suitable device found");
 180                 return (NULL);
 181         }
 182
 183         (void)strncpy(device, mp->ifr_name, sizeof(device) - 1);
 184         device[sizeof(device) - 1] = '\0';
 185         return (device);
 186 }
 187
 188 int
 189 pcap_lookupnet(device, netp, maskp, errbuf)
 190         register char *device;
 191         register bpf_u_int32 *netp, *maskp;
 192         register char *errbuf;
 193 {
 194         register int fd;
 195         register struct sockaddr_in *sin;
 196         struct ifreq ifr;
 197
 198         fd = socket(AF_INET, SOCK_DGRAM, 0);
 199         if (fd < 0) {
 200                 (void)sprintf(errbuf, "socket: %s", pcap_strerror(errno));
 201                 return (-1);
 202         }
 203         memset(&ifr, 0, sizeof(ifr));
 204 #ifdef linux
 205         /* XXX Work around Linux kernel bug */
 206         ifr.ifr_addr.sa_family = AF_INET;
 207 #endif
 208         (void)strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
 209         if (ioctl(fd, SIOCGIFADDR, (char *)&ifr) < 0) {
 210                 if (errno == EADDRNOTAVAIL) {
 211                         (void)sprintf(errbuf, "%s: no IPv4 address assigned",
 212                             device);
 213                 } else {
 214                         (void)sprintf(errbuf, "SIOCGIFADDR: %s: %s",
 215                             device, pcap_strerror(errno));
 216                 }
 217                 (void)close(fd);
 218                 return (-1);
 219         }
 220         sin = (struct sockaddr_in *)&ifr.ifr_addr;
 221         *netp = sin->sin_addr.s_addr;
 222         if (ioctl(fd, SIOCGIFNETMASK, (char *)&ifr) < 0) {
 223                 (void)sprintf(errbuf, "SIOCGIFNETMASK: %s: %s",
 224                     device, pcap_strerror(errno));
 225                 (void)close(fd);
 226                 return (-1);
 227         }
 228         (void)close(fd);
 229         *maskp = sin->sin_addr.s_addr;
 230         if (*maskp == 0) {
 231                 if (IN_CLASSA(*netp))
 232                         *maskp = IN_CLASSA_NET;
 233                 else if (IN_CLASSB(*netp))
 234                         *maskp = IN_CLASSB_NET;
 235                 else if (IN_CLASSC(*netp))
 236                         *maskp = IN_CLASSC_NET;
 237                 else {
 238                         (void)sprintf(errbuf, "inet class for 0x%x unknown",
 239                             *netp);
 240                         return (-1);
 241                 }
 242         }
 243         *netp &= *maskp;
 244         return (0);
 245 }