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 1.36 2000-09-20 15:10:29 torsten 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 #define ISLOOPBACK_IFA(p) ((p)->ifa_flags & IFF_LOOPBACK)
  78 #else
  79 #define ISLOOPBACK(p) ((p)->ifr_name[0] == 'l' && (p)->ifr_name[1] == 'o' && \
  80     (isdigit((p)->ifr_name[2]) || (p)->ifr_name[2] == '\0'))
  81 #define ISLOOPBACK_IFA(p) ((p)->ifa_name[0] == 'l' && (p)->ifa_name[1] == 'o' && \
  82     (isdigit((p)->ifa_name[2]) || (p)->ifa_name[2] == '\0'))
  83 #endif
  84
  85 /*
  86  * Return the name of a network interface attached to the system, or NULL
  87  * if none can be found.  The interface must be configured up; the
  88  * lowest unit number is preferred; loopback is ignored.
  89  */
  90 char *
  91 pcap_lookupdev(errbuf)
  92         register char *errbuf;
  93 {
  94 #ifdef HAVE_IFADDRS_H
  95         struct ifaddrs *ifap, *ifa, *mp;
  96         int n, minunit;
  97         char *cp;
  98         static char device[IF_NAMESIZE + 1];
  99
 100         if (getifaddrs(&ifap) != 0) {
 101                 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 102                     "getifaddrs: %s", pcap_strerror(errno));
 103                 return NULL;
 104         }
 105
 106         mp = NULL;
 107         minunit = 666;
 108         for (ifa = ifap; ifa; ifa = ifa->ifa_next) {
 109                 const char *endcp;
 110
 111                 if ((ifa->ifa_flags & IFF_UP) == 0 || ISLOOPBACK_IFA(ifa))
 112                         continue;
 113
 114                 endcp = ifa->ifa_name + strlen(ifa->ifa_name);
 115                 for (cp = ifa->ifa_name; cp < endcp && !isdigit(*cp); ++cp)
 116                         continue;
 117
 118                 if (isdigit (*cp)) {
 119                         n = atoi(cp);
 120                 } else {
 121                         n = 0;
 122                 }
 123                 if (n < minunit) {
 124                         minunit = n;
 125                         mp = ifa;
 126                 }
 127         }
 128         if (mp == NULL) {
 129                 (void)strlcpy(errbuf, "no suitable device found",
 130                     PCAP_ERRBUF_SIZE);
 131 #ifdef HAVE_FREEIFADDRS
 132                 freeifaddrs(ifap);
 133 #else
 134                 free(ifap);
 135 #endif
 136                 return (NULL);
 137         }
 138
 139         (void)strlcpy(device, mp->ifa_name, sizeof(device));
 140 #ifdef HAVE_FREEIFADDRS
 141         freeifaddrs(ifap);
 142 #else
 143         free(ifap);
 144 #endif
 145         return (device);
 146 #else
 147         register int fd, minunit, n;
 148         register char *cp;
 149         register struct ifreq *ifrp, *ifend, *ifnext, *mp;
 150         struct ifconf ifc;
 151         char *buf;
 152         struct ifreq ifr;
 153         static char device[sizeof(ifrp->ifr_name) + 1];
 154         unsigned buf_size;
 155
 156         fd = socket(AF_INET, SOCK_DGRAM, 0);
 157         if (fd < 0) {
 158                 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 159                     "socket: %s", pcap_strerror(errno));
 160                 return (NULL);
 161         }
 162
 163         buf_size = 8192;
 164
 165         for (;;) {
 166                 buf = malloc (buf_size);
 167                 if (buf == NULL) {
 168                         close (fd);
 169                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 170                             "out of memory");
 171                         return (NULL);
 172                 }
 173
 174                 ifc.ifc_len = buf_size;
 175                 ifc.ifc_buf = buf;
 176                 memset (buf, 0, buf_size);
 177                 if (ioctl(fd, SIOCGIFCONF, (char *)&ifc) < 0
 178                     && errno != EINVAL) {
 179                         free (buf);
 180                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 181                             "SIOCGIFCONF: %s", pcap_strerror(errno));
 182                         (void)close(fd);
 183                         return (NULL);
 184                 }
 185                 if (ifc.ifc_len < buf_size)
 186                         break;
 187                 free (buf);
 188                 buf_size *= 2;
 189         }
 190
 191         ifrp = (struct ifreq *)buf;
 192         ifend = (struct ifreq *)(buf + ifc.ifc_len);
 193
 194         mp = NULL;
 195         minunit = 666;
 196         for (; ifrp < ifend; ifrp = ifnext) {
 197                 const char *endcp;
 198
 199 #ifdef HAVE_SOCKADDR_SA_LEN
 200                 n = ifrp->ifr_addr.sa_len + sizeof(ifrp->ifr_name);
 201                 if (n < sizeof(*ifrp))
 202                         ifnext = ifrp + 1;
 203                 else
 204                         ifnext = (struct ifreq *)((char *)ifrp + n);
 205                 if (ifrp->ifr_addr.sa_family != AF_INET)
 206                         continue;
 207 #else
 208                 ifnext = ifrp + 1;
 209 #endif
 210                 /*
 211                  * Need a template to preserve address info that is
 212                  * used below to locate the next entry.  (Otherwise,
 213                  * SIOCGIFFLAGS stomps over it because the requests
 214                  * are returned in a union.)
 215                  */
 216                 strncpy(ifr.ifr_name, ifrp->ifr_name, sizeof(ifr.ifr_name));
 217                 if (ioctl(fd, SIOCGIFFLAGS, (char *)&ifr) < 0) {
 218                         if (errno == ENXIO)
 219                                 continue;
 220                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 221                             "SIOCGIFFLAGS: %.*s: %s",
 222                             (int)sizeof(ifr.ifr_name), ifr.ifr_name,
 223                             pcap_strerror(errno));
 224                         (void)close(fd);
 225                         free (buf);
 226                         return (NULL);
 227                 }
 228
 229                 /* Must be up and not the loopback */
 230                 if ((ifr.ifr_flags & IFF_UP) == 0 || ISLOOPBACK(&ifr))
 231                         continue;
 232
 233                 endcp = ifrp->ifr_name + strlen(ifrp->ifr_name);
 234                 for (cp = ifrp->ifr_name; cp < endcp && !isdigit(*cp); ++cp)
 235                         continue;
 236
 237                 if (isdigit (*cp)) {
 238                         n = atoi(cp);
 239                 } else {
 240                         n = 0;
 241                 }
 242                 if (n < minunit) {
 243                         minunit = n;
 244                         mp = ifrp;
 245                 }
 246         }
 247         (void)close(fd);
 248         if (mp == NULL) {
 249                 (void)strlcpy(errbuf, "no suitable device found",
 250                     PCAP_ERRBUF_SIZE);
 251                 free(buf);
 252                 return (NULL);
 253         }
 254
 255         (void)strlcpy(device, mp->ifr_name, sizeof(device));
 256         free(buf);
 257         return (device);
 258 #endif
 259 }
 260
 261 int
 262 pcap_lookupnet(device, netp, maskp, errbuf)
 263         register char *device;
 264         register bpf_u_int32 *netp, *maskp;
 265         register char *errbuf;
 266 {
 267         register int fd;
 268         register struct sockaddr_in *sin;
 269         struct ifreq ifr;
 270
 271         /*
 272          * The pseudo-device "any" listens on all interfaces and therefore
 273          * has the network address and -mask "0.0.0.0" therefore catching
 274          * all traffic. Using NULL for the interface is the same as "any".
 275          */
 276         if (!device || strcmp(device, "any") == 0) {
 277                 *netp = *maskp = 0;
 278                 return 0;
 279         }
 280
 281         fd = socket(AF_INET, SOCK_DGRAM, 0);
 282         if (fd < 0) {
 283                 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE, "socket: %s",
 284                     pcap_strerror(errno));
 285                 return (-1);
 286         }
 287         memset(&ifr, 0, sizeof(ifr));
 288 #ifdef linux
 289         /* XXX Work around Linux kernel bug */
 290         ifr.ifr_addr.sa_family = AF_INET;
 291 #endif
 292         (void)strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
 293         if (ioctl(fd, SIOCGIFADDR, (char *)&ifr) < 0) {
 294                 if (errno == EADDRNOTAVAIL) {
 295                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 296                             "%s: no IPv4 address assigned", device);
 297                 } else {
 298                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 299                             "SIOCGIFADDR: %s: %s",
 300                             device, pcap_strerror(errno));
 301                 }
 302                 (void)close(fd);
 303                 return (-1);
 304         }
 305         sin = (struct sockaddr_in *)&ifr.ifr_addr;
 306         *netp = sin->sin_addr.s_addr;
 307         if (ioctl(fd, SIOCGIFNETMASK, (char *)&ifr) < 0) {
 308                 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 309                     "SIOCGIFNETMASK: %s: %s", device, pcap_strerror(errno));
 310                 (void)close(fd);
 311                 return (-1);
 312         }
 313         (void)close(fd);
 314         *maskp = sin->sin_addr.s_addr;
 315         if (*maskp == 0) {
 316                 if (IN_CLASSA(*netp))
 317                         *maskp = IN_CLASSA_NET;
 318                 else if (IN_CLASSB(*netp))
 319                         *maskp = IN_CLASSB_NET;
 320                 else if (IN_CLASSC(*netp))
 321                         *maskp = IN_CLASSC_NET;
 322                 else {
 323                         (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
 324                             "inet class for 0x%x unknown", *netp);
 325                         return (-1);
 326                 }
 327         }
 328         *netp &= *maskp;
 329         return (0);
 330 }