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 1.33 2000-07-01 03:34:10 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 struct mbuf;
  49 struct rtentry;
  50 #include <net/if.h>
  51 #include <netinet/in.h>
  52
  53 #include <ctype.h>
  54 #include <errno.h>
  55 #include <memory.h>
  56 #include <stdio.h>
  57 #include <stdlib.h>
  58 #include <string.h>
  59 #include <unistd.h>
  60 #ifdef HAVE_IFADDRS_H
  61 #include <ifaddrs.h>
  62 #endif
  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 #ifdef HAVE_IFADDRS_H
  89         struct ifaddrs *ifap, *ifa, *mp;
  90         int n, minunit;
  91         char *cp;
  92         static char device[IF_NAMESIZE + 1];
  93
  94         if (getifaddrs(&ifap) != 0) {
  95                 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
  96                     "getifaddrs: %s", pcap_strerror(errno));
  97                 return NULL;
  98         }
  99
 100         mp = NULL;
 101         minunit = 666;
 102         for (ifa = ifap; ifa; ifa = ifa->ifa_next) {
 103                 if ((ifa->ifa_flags & IFF_UP) == 0)
 104                         continue;
 105 #ifdef IFF_LOOPBACK
 106                 if ((ifa->ifa_flags & IFF_LOOPBACK) != 0)
 107                         continue;
 108 #else
 109                 if (strncmp(ifa->ifa_name, "lo", 2) == 0 &&
 110                     (ifa->ifa_name[2] == '\0' || isdigit(ifa->ifa_name[2]))) {
 111                         continue;
 112                 }
 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)strlcpy(errbuf, "no suitable device found",
 125                     PCAP_ERRBUF_SIZE);
 126 #ifdef HAVE_FREEIFADDRS
 127                 freeifaddrs(ifap);
 128 #else
 129                 free(ifap);
 130 #endif
 131                 return (NULL);
 132         }
 133
 134         (void)strlcpy(device, mp->ifa_name, sizeof(device));
 135 #ifdef HAVE_FREEIFADDRS
 136         freeifaddrs(ifap);
 137 #else
 138         free(ifap);
 139 #endif
 140         return (device);
 141 #else
 142         register int fd, minunit, n;
 143         register char *cp;
 144         register struct ifreq *ifrp, *ifend, *ifnext, *mp;
 145         struct ifconf ifc;
 146         char *buf;
 147         struct ifreq ifr;
 148         static char device[sizeof(ifrp->ifr_name) + 1];
 149         unsigned buf_size;
 150
 151         fd = socket(AF_INET, SOCK_DGRAM, 0);
 152         if (fd < 0) {
 153                 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 154                     "socket: %s", pcap_strerror(errno));
 155                 return (NULL);
 156         }
 157
 158         buf_size = 8192;
 159
 160         for (;;) {
 161                 buf = malloc (buf_size);
 162                 if (buf == NULL) {
 163                         close (fd);
 164                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 165                             "out of memory");
 166                         return (NULL);
 167                 }
 168
 169                 ifc.ifc_len = buf_size;
 170                 ifc.ifc_buf = buf;
 171                 memset (buf, 0, buf_size);
 172                 if (ioctl(fd, SIOCGIFCONF, (char *)&ifc) < 0
 173                     && errno != EINVAL) {
 174                         free (buf);
 175                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 176                             "SIOCGIFCONF: %s", pcap_strerror(errno));
 177                         (void)close(fd);
 178                         return (NULL);
 179                 }
 180                 if (ifc.ifc_len < buf_size)
 181                         break;
 182                 free (buf);
 183                 buf_size *= 2;
 184         }
 185
 186         ifrp = (struct ifreq *)buf;
 187         ifend = (struct ifreq *)(buf + ifc.ifc_len);
 188
 189         mp = NULL;
 190         minunit = 666;
 191         for (; ifrp < ifend; ifrp = ifnext) {
 192 #ifdef HAVE_SOCKADDR_SA_LEN
 193                 n = ifrp->ifr_addr.sa_len + sizeof(ifrp->ifr_name);
 194                 if (n < sizeof(*ifrp))
 195                         ifnext = ifrp + 1;
 196                 else
 197                         ifnext = (struct ifreq *)((char *)ifrp + n);
 198                 if (ifrp->ifr_addr.sa_family != AF_INET)
 199                         continue;
 200 #else
 201                 ifnext = ifrp + 1;
 202 #endif
 203                 /*
 204                  * Need a template to preserve address info that is
 205                  * used below to locate the next entry.  (Otherwise,
 206                  * SIOCGIFFLAGS stomps over it because the requests
 207                  * are returned in a union.)
 208                  */
 209                 strncpy(ifr.ifr_name, ifrp->ifr_name, sizeof(ifr.ifr_name));
 210                 if (ioctl(fd, SIOCGIFFLAGS, (char *)&ifr) < 0) {
 211                         if (errno == ENXIO)
 212                                 continue;
 213                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 214                             "SIOCGIFFLAGS: %.*s: %s",
 215                             (int)sizeof(ifr.ifr_name), ifr.ifr_name,
 216                             pcap_strerror(errno));
 217                         (void)close(fd);
 218                         free (buf);
 219                         return (NULL);
 220                 }
 221
 222                 /* Must be up and not the loopback */
 223                 if ((ifr.ifr_flags & IFF_UP) == 0 || ISLOOPBACK(&ifr))
 224                         continue;
 225
 226                 for (cp = ifrp->ifr_name; !isdigit(*cp); ++cp)
 227                         continue;
 228                 n = atoi(cp);
 229                 if (n < minunit) {
 230                         minunit = n;
 231                         mp = ifrp;
 232                 }
 233         }
 234         (void)close(fd);
 235         if (mp == NULL) {
 236                 (void)strlcpy(errbuf, "no suitable device found",
 237                     PCAP_ERRBUF_SIZE);
 238                 free(buf);
 239                 return (NULL);
 240         }
 241
 242         (void)strlcpy(device, mp->ifr_name, sizeof(device));
 243         free(buf);
 244         return (device);
 245 #endif
 246 }
 247
 248 int
 249 pcap_lookupnet(device, netp, maskp, errbuf)
 250         register char *device;
 251         register bpf_u_int32 *netp, *maskp;
 252         register char *errbuf;
 253 {
 254         register int fd;
 255         register struct sockaddr_in *sin;
 256         struct ifreq ifr;
 257
 258         fd = socket(AF_INET, SOCK_DGRAM, 0);
 259         if (fd < 0) {
 260                 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, "socket: %s",
 261                     pcap_strerror(errno));
 262                 return (-1);
 263         }
 264         memset(&ifr, 0, sizeof(ifr));
 265 #ifdef linux
 266         /* XXX Work around Linux kernel bug */
 267         ifr.ifr_addr.sa_family = AF_INET;
 268 #endif
 269         (void)strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
 270         if (ioctl(fd, SIOCGIFADDR, (char *)&ifr) < 0) {
 271                 if (errno == EADDRNOTAVAIL) {
 272                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 273                             "%s: no IPv4 address assigned", device);
 274                 } else {
 275                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 276                             "SIOCGIFADDR: %s: %s",
 277                             device, pcap_strerror(errno));
 278                 }
 279                 (void)close(fd);
 280                 return (-1);
 281         }
 282         sin = (struct sockaddr_in *)&ifr.ifr_addr;
 283         *netp = sin->sin_addr.s_addr;
 284         if (ioctl(fd, SIOCGIFNETMASK, (char *)&ifr) < 0) {
 285                 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 286                     "SIOCGIFNETMASK: %s: %s", device, pcap_strerror(errno));
 287                 (void)close(fd);
 288                 return (-1);
 289         }
 290         (void)close(fd);
 291         *maskp = sin->sin_addr.s_addr;
 292         if (*maskp == 0) {
 293                 if (IN_CLASSA(*netp))
 294                         *maskp = IN_CLASSA_NET;
 295                 else if (IN_CLASSB(*netp))
 296                         *maskp = IN_CLASSB_NET;
 297                 else if (IN_CLASSC(*netp))
 298                         *maskp = IN_CLASSC_NET;
 299                 else {
 300                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 301                             "inet class for 0x%x unknown", *netp);
 302                         return (-1);
 303                 }
 304         }
 305         *netp &= *maskp;
 306         return (0);
 307 }