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 1.30 2000-04-27 09:11:12 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)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)strncpy(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)strncpy(device, mp->ifa_name, sizeof(device) - 1);
 138         device[sizeof(device) - 1] = '\0';
 139 #ifdef HAVE_FREEIFADDRS
 140         freeifaddrs(ifap);
 141 #else
 142         free(ifap);
 143 #endif
 144         return (device);
 145 #else
 146         register int fd, minunit, n;
 147         register char *cp;
 148         register struct ifreq *ifrp, *ifend, *ifnext, *mp;
 149         struct ifconf ifc;
 150         char *buf;
 151         struct ifreq ifr;
 152         static char device[sizeof(ifrp->ifr_name) + 1];
 153         unsigned buf_size;
 154
 155         fd = socket(AF_INET, SOCK_DGRAM, 0);
 156         if (fd < 0) {
 157                 (void)snprintf(errbuf, PCAP_ERRBUFF_SIZE,
 158                     "socket: %s", pcap_strerror(errno));
 159                 return (NULL);
 160         }
 161
 162         buf_size = 8192;
 163
 164         for (;;) {
 165                 buf = malloc (buf_size);
 166                 if (buf == NULL) {
 167                         close (fd);
 168                         (void)snprintf(errbuf, PCAP_ERRBUFF_SIZE,
 169                             "out of memory");
 170                         return (NULL);
 171                 }
 172
 173                 ifc.ifc_len = buf_size;
 174                 ifc.ifc_buf = buf;
 175                 memset (buf, 0, buf_size);
 176                 if (ioctl(fd, SIOCGIFCONF, (char *)&ifc) < 0
 177                     && errno != EINVAL) {
 178                         free (buf);
 179                         (void)snprintf(errbuf, PCAP_ERRBUFF_SIZE,
 180                             "SIOCGIFCONF: %s", pcap_strerror(errno));
 181                         (void)close(fd);
 182                         return (NULL);
 183                 }
 184                 if (ifc.ifc_len < buf_size)
 185                         break;
 186                 free (buf);
 187                 buf_size *= 2;
 188         }
 189
 190         ifrp = (struct ifreq *)buf;
 191         ifend = (struct ifreq *)(buf + ifc.ifc_len);
 192
 193         mp = NULL;
 194         minunit = 666;
 195         for (; ifrp < ifend; ifrp = ifnext) {
 196 #ifdef HAVE_SOCKADDR_SA_LEN
 197                 n = ifrp->ifr_addr.sa_len + sizeof(ifrp->ifr_name);
 198                 if (n < sizeof(*ifrp))
 199                         ifnext = ifrp + 1;
 200                 else
 201                         ifnext = (struct ifreq *)((char *)ifrp + n);
 202                 if (ifrp->ifr_addr.sa_family != AF_INET)
 203                         continue;
 204 #else
 205                 ifnext = ifrp + 1;
 206 #endif
 207                 /*
 208                  * Need a template to preserve address info that is
 209                  * used below to locate the next entry.  (Otherwise,
 210                  * SIOCGIFFLAGS stomps over it because the requests
 211                  * are returned in a union.)
 212                  */
 213                 strncpy(ifr.ifr_name, ifrp->ifr_name, sizeof(ifr.ifr_name));
 214                 if (ioctl(fd, SIOCGIFFLAGS, (char *)&ifr) < 0) {
 215                         if (errno == ENXIO)
 216                                 continue;
 217                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 218                             "SIOCGIFFLAGS: %.*s: %s",
 219                             (int)sizeof(ifr.ifr_name), ifr.ifr_name,
 220                             pcap_strerror(errno));
 221                         (void)close(fd);
 222                         free (buf);
 223                         return (NULL);
 224                 }
 225
 226                 /* Must be up and not the loopback */
 227                 if ((ifr.ifr_flags & IFF_UP) == 0 || ISLOOPBACK(&ifr))
 228                         continue;
 229
 230                 for (cp = ifrp->ifr_name; !isdigit(*cp); ++cp)
 231                         continue;
 232                 n = atoi(cp);
 233                 if (n < minunit) {
 234                         minunit = n;
 235                         mp = ifrp;
 236                 }
 237         }
 238         (void)close(fd);
 239         if (mp == NULL) {
 240                 (void)strlcpy(errbuf, "no suitable device found",
 241                     PCAP_ERRBUF_SIZE);
 242                 free(buf);
 243                 return (NULL);
 244         }
 245
 246         (void)strncpy(device, mp->ifr_name, sizeof(device) - 1);
 247         device[sizeof(device) - 1] = '\0';
 248         free(buf);
 249         return (device);
 250 #endif
 251 }
 252
 253 int
 254 pcap_lookupnet(device, netp, maskp, errbuf)
 255         register char *device;
 256         register bpf_u_int32 *netp, *maskp;
 257         register char *errbuf;
 258 {
 259         register int fd;
 260         register struct sockaddr_in *sin;
 261         struct ifreq ifr;
 262
 263         fd = socket(AF_INET, SOCK_DGRAM, 0);
 264         if (fd < 0) {
 265                 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, "socket: %s",
 266                     pcap_strerror(errno));
 267                 return (-1);
 268         }
 269         memset(&ifr, 0, sizeof(ifr));
 270 #ifdef linux
 271         /* XXX Work around Linux kernel bug */
 272         ifr.ifr_addr.sa_family = AF_INET;
 273 #endif
 274         (void)strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
 275         if (ioctl(fd, SIOCGIFADDR, (char *)&ifr) < 0) {
 276                 if (errno == EADDRNOTAVAIL) {
 277                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 278                             "%s: no IPv4 address assigned", device);
 279                 } else {
 280                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 281                             "SIOCGIFADDR: %s: %s",
 282                             device, pcap_strerror(errno));
 283                 }
 284                 (void)close(fd);
 285                 return (-1);
 286         }
 287         sin = (struct sockaddr_in *)&ifr.ifr_addr;
 288         *netp = sin->sin_addr.s_addr;
 289         if (ioctl(fd, SIOCGIFNETMASK, (char *)&ifr) < 0) {
 290                 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 291                     "SIOCGIFNETMASK: %s: %s", device, pcap_strerror(errno));
 292                 (void)close(fd);
 293                 return (-1);
 294         }
 295         (void)close(fd);
 296         *maskp = sin->sin_addr.s_addr;
 297         if (*maskp == 0) {
 298                 if (IN_CLASSA(*netp))
 299                         *maskp = IN_CLASSA_NET;
 300                 else if (IN_CLASSB(*netp))
 301                         *maskp = IN_CLASSB_NET;
 302                 else if (IN_CLASSC(*netp))
 303                         *maskp = IN_CLASSC_NET;
 304                 else {
 305                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 306                             "inet class for 0x%x unknown", *netp);
 307                         return (-1);
 308                 }
 309         }
 310         *netp &= *maskp;
 311         return (0);
 312 }