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 1.34 2000-07-11 00:37:04 assar Exp $ (LBL)";
  37 #endif
  38
  39 #ifdef HAVE_CONFIG_H
  40 #include "config.h"
  41 #endif
  42
  43 #include <sys/param.h>
  44 #include <sys/file.h>
  45 #include <sys/ioctl.h>
  46 #include <sys/socket.h>
  47 #ifdef HAVE_SYS_SOCKIO_H
  48 #include <sys/sockio.h>
  49 #endif
  50 #include <sys/time.h>                           /* concession to AIX */
  51
  52 struct mbuf;
  53 struct rtentry;
  54 #include <net/if.h>
  55 #include <netinet/in.h>
  56
  57 #include <ctype.h>
  58 #include <errno.h>
  59 #include <memory.h>
  60 #include <stdio.h>
  61 #include <stdlib.h>
  62 #include <string.h>
  63 #include <unistd.h>
  64 #ifdef HAVE_IFADDRS_H
  65 #include <ifaddrs.h>
  66 #endif
  67
  68 #include "pcap-int.h"
  69
  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)snprintf(errbuf, PCAP_ERRBUF_SIZE,
  99                     "getifaddrs: %s", pcap_strerror(errno));
 100                 return NULL;
 101         }
 102
 103         mp = NULL;
 104         minunit = 666;
 105         for (ifa = ifap; ifa; ifa = ifa->ifa_next) {
 106                 if ((ifa->ifa_flags & IFF_UP) == 0)
 107                         continue;
 108 #ifdef IFF_LOOPBACK
 109                 if ((ifa->ifa_flags & IFF_LOOPBACK) != 0)
 110                         continue;
 111 #else
 112                 if (strncmp(ifa->ifa_name, "lo", 2) == 0 &&
 113                     (ifa->ifa_name[2] == '\0' || isdigit(ifa->ifa_name[2]))) {
 114                         continue;
 115                 }
 116 #endif
 117
 118                 for (cp = ifa->ifa_name; !isdigit(*cp); ++cp)
 119                         continue;
 120                 n = atoi(cp);
 121                 if (n < minunit) {
 122                         minunit = n;
 123                         mp = ifa;
 124                 }
 125         }
 126         if (mp == NULL) {
 127                 (void)strlcpy(errbuf, "no suitable device found",
 128                     PCAP_ERRBUF_SIZE);
 129 #ifdef HAVE_FREEIFADDRS
 130                 freeifaddrs(ifap);
 131 #else
 132                 free(ifap);
 133 #endif
 134                 return (NULL);
 135         }
 136
 137         (void)strlcpy(device, mp->ifa_name, sizeof(device));
 138 #ifdef HAVE_FREEIFADDRS
 139         freeifaddrs(ifap);
 140 #else
 141         free(ifap);
 142 #endif
 143         return (device);
 144 #else
 145         register int fd, minunit, n;
 146         register char *cp;
 147         register struct ifreq *ifrp, *ifend, *ifnext, *mp;
 148         struct ifconf ifc;
 149         char *buf;
 150         struct ifreq ifr;
 151         static char device[sizeof(ifrp->ifr_name) + 1];
 152         unsigned buf_size;
 153
 154         fd = socket(AF_INET, SOCK_DGRAM, 0);
 155         if (fd < 0) {
 156                 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 157                     "socket: %s", pcap_strerror(errno));
 158                 return (NULL);
 159         }
 160
 161         buf_size = 8192;
 162
 163         for (;;) {
 164                 buf = malloc (buf_size);
 165                 if (buf == NULL) {
 166                         close (fd);
 167                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 168                             "out of memory");
 169                         return (NULL);
 170                 }
 171
 172                 ifc.ifc_len = buf_size;
 173                 ifc.ifc_buf = buf;
 174                 memset (buf, 0, buf_size);
 175                 if (ioctl(fd, SIOCGIFCONF, (char *)&ifc) < 0
 176                     && errno != EINVAL) {
 177                         free (buf);
 178                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 179                             "SIOCGIFCONF: %s", pcap_strerror(errno));
 180                         (void)close(fd);
 181                         return (NULL);
 182                 }
 183                 if (ifc.ifc_len < buf_size)
 184                         break;
 185                 free (buf);
 186                 buf_size *= 2;
 187         }
 188
 189         ifrp = (struct ifreq *)buf;
 190         ifend = (struct ifreq *)(buf + ifc.ifc_len);
 191
 192         mp = NULL;
 193         minunit = 666;
 194         for (; ifrp < ifend; ifrp = ifnext) {
 195 #ifdef HAVE_SOCKADDR_SA_LEN
 196                 n = ifrp->ifr_addr.sa_len + sizeof(ifrp->ifr_name);
 197                 if (n < sizeof(*ifrp))
 198                         ifnext = ifrp + 1;
 199                 else
 200                         ifnext = (struct ifreq *)((char *)ifrp + n);
 201                 if (ifrp->ifr_addr.sa_family != AF_INET)
 202                         continue;
 203 #else
 204                 ifnext = ifrp + 1;
 205 #endif
 206                 /*
 207                  * Need a template to preserve address info that is
 208                  * used below to locate the next entry.  (Otherwise,
 209                  * SIOCGIFFLAGS stomps over it because the requests
 210                  * are returned in a union.)
 211                  */
 212                 strncpy(ifr.ifr_name, ifrp->ifr_name, sizeof(ifr.ifr_name));
 213                 if (ioctl(fd, SIOCGIFFLAGS, (char *)&ifr) < 0) {
 214                         if (errno == ENXIO)
 215                                 continue;
 216                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 217                             "SIOCGIFFLAGS: %.*s: %s",
 218                             (int)sizeof(ifr.ifr_name), ifr.ifr_name,
 219                             pcap_strerror(errno));
 220                         (void)close(fd);
 221                         free (buf);
 222                         return (NULL);
 223                 }
 224
 225                 /* Must be up and not the loopback */
 226                 if ((ifr.ifr_flags & IFF_UP) == 0 || ISLOOPBACK(&ifr))
 227                         continue;
 228
 229                 for (cp = ifrp->ifr_name; !isdigit(*cp); ++cp)
 230                         continue;
 231                 n = atoi(cp);
 232                 if (n < minunit) {
 233                         minunit = n;
 234                         mp = ifrp;
 235                 }
 236         }
 237         (void)close(fd);
 238         if (mp == NULL) {
 239                 (void)strlcpy(errbuf, "no suitable device found",
 240                     PCAP_ERRBUF_SIZE);
 241                 free(buf);
 242                 return (NULL);
 243         }
 244
 245         (void)strlcpy(device, mp->ifr_name, sizeof(device));
 246         free(buf);
 247         return (device);
 248 #endif
 249 }
 250
 251 int
 252 pcap_lookupnet(device, netp, maskp, errbuf)
 253         register char *device;
 254         register bpf_u_int32 *netp, *maskp;
 255         register char *errbuf;
 256 {
 257         register int fd;
 258         register struct sockaddr_in *sin;
 259         struct ifreq ifr;
 260
 261         fd = socket(AF_INET, SOCK_DGRAM, 0);
 262         if (fd < 0) {
 263                 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, "socket: %s",
 264                     pcap_strerror(errno));
 265                 return (-1);
 266         }
 267         memset(&ifr, 0, sizeof(ifr));
 268 #ifdef linux
 269         /* XXX Work around Linux kernel bug */
 270         ifr.ifr_addr.sa_family = AF_INET;
 271 #endif
 272         (void)strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
 273         if (ioctl(fd, SIOCGIFADDR, (char *)&ifr) < 0) {
 274                 if (errno == EADDRNOTAVAIL) {
 275                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 276                             "%s: no IPv4 address assigned", device);
 277                 } else {
 278                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 279                             "SIOCGIFADDR: %s: %s",
 280                             device, pcap_strerror(errno));
 281                 }
 282                 (void)close(fd);
 283                 return (-1);
 284         }
 285         sin = (struct sockaddr_in *)&ifr.ifr_addr;
 286         *netp = sin->sin_addr.s_addr;
 287         if (ioctl(fd, SIOCGIFNETMASK, (char *)&ifr) < 0) {
 288                 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 289                     "SIOCGIFNETMASK: %s: %s", device, pcap_strerror(errno));
 290                 (void)close(fd);
 291                 return (-1);
 292         }
 293         (void)close(fd);
 294         *maskp = sin->sin_addr.s_addr;
 295         if (*maskp == 0) {
 296                 if (IN_CLASSA(*netp))
 297                         *maskp = IN_CLASSA_NET;
 298                 else if (IN_CLASSB(*netp))
 299                         *maskp = IN_CLASSB_NET;
 300                 else if (IN_CLASSC(*netp))
 301                         *maskp = IN_CLASSC_NET;
 302                 else {
 303                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 304                             "inet class for 0x%x unknown", *netp);
 305                         return (-1);
 306                 }
 307         }
 308         *netp &= *maskp;
 309         return (0);
 310 }