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 1.22 1999-10-07 23:46:40 mcr 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         struct ifreq ibuf[16], ifr;
  93         static char device[sizeof(ifrp->ifr_name) + 1];
  94
  95         fd = socket(AF_INET, SOCK_DGRAM, 0);
  96         if (fd < 0) {
  97                 (void)sprintf(errbuf, "socket: %s", pcap_strerror(errno));
  98                 return (NULL);
  99         }
 100         ifc.ifc_len = sizeof ibuf;
 101         ifc.ifc_buf = (caddr_t)ibuf;
 102
 103         memset((char *)ibuf, 0, sizeof(ibuf));
 104         if (ioctl(fd, SIOCGIFCONF, (char *)&ifc) < 0 ||
 105             ifc.ifc_len < sizeof(struct ifreq)) {
 106                 (void)sprintf(errbuf, "SIOCGIFCONF: %s", pcap_strerror(errno));
 107                 (void)close(fd);
 108                 return (NULL);
 109         }
 110         ifrp = ibuf;
 111         ifend = (struct ifreq *)((char *)ibuf + ifc.ifc_len);
 112
 113         mp = NULL;
 114         minunit = 666;
 115         for (; ifrp < ifend; ifrp = ifnext) {
 116 #ifdef HAVE_SOCKADDR_SA_LEN
 117                 n = ifrp->ifr_addr.sa_len + sizeof(ifrp->ifr_name);
 118                 if (n < sizeof(*ifrp))
 119                         ifnext = ifrp + 1;
 120                 else
 121                         ifnext = (struct ifreq *)((char *)ifrp + n);
 122                 if (ifrp->ifr_addr.sa_family != AF_INET)
 123                         continue;
 124 #else
 125                 ifnext = ifrp + 1;
 126 #endif
 127                 /*
 128                  * Need a template to preserve address info that is
 129                  * used below to locate the next entry.  (Otherwise,
 130                  * SIOCGIFFLAGS stomps over it because the requests
 131                  * are returned in a union.)
 132                  */
 133                 strncpy(ifr.ifr_name, ifrp->ifr_name, sizeof(ifr.ifr_name));
 134                 if (ioctl(fd, SIOCGIFFLAGS, (char *)&ifr) < 0) {
 135                         if (errno == ENXIO)
 136                                 continue;
 137                         (void)sprintf(errbuf, "SIOCGIFFLAGS: %.*s: %s",
 138                             (int)sizeof(ifr.ifr_name), ifr.ifr_name,
 139                             pcap_strerror(errno));
 140                         (void)close(fd);
 141                         return (NULL);
 142                 }
 143
 144                 /* Must be up and not the loopback */
 145                 if ((ifr.ifr_flags & IFF_UP) == 0 || ISLOOPBACK(&ifr))
 146                         continue;
 147
 148                 for (cp = ifrp->ifr_name; !isdigit(*cp); ++cp)
 149                         continue;
 150                 n = atoi(cp);
 151                 if (n < minunit) {
 152                         minunit = n;
 153                         mp = ifrp;
 154                 }
 155         }
 156         (void)close(fd);
 157         if (mp == NULL) {
 158                 (void)strcpy(errbuf, "no suitable device found");
 159                 return (NULL);
 160         }
 161
 162         (void)strncpy(device, mp->ifr_name, sizeof(device) - 1);
 163         device[sizeof(device) - 1] = '\0';
 164         return (device);
 165 }
 166
 167 int
 168 pcap_lookupnet(device, netp, maskp, errbuf)
 169         register char *device;
 170         register bpf_u_int32 *netp, *maskp;
 171         register char *errbuf;
 172 {
 173         register int fd;
 174         register struct sockaddr_in *sin;
 175         struct ifreq ifr;
 176
 177         fd = socket(AF_INET, SOCK_DGRAM, 0);
 178         if (fd < 0) {
 179                 (void)sprintf(errbuf, "socket: %s", pcap_strerror(errno));
 180                 return (-1);
 181         }
 182         memset(&ifr, 0, sizeof(ifr));
 183 #ifdef linux
 184         /* XXX Work around Linux kernel bug */
 185         ifr.ifr_addr.sa_family = AF_INET;
 186 #endif
 187         (void)strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
 188         if (ioctl(fd, SIOCGIFADDR, (char *)&ifr) < 0) {
 189                 (void)sprintf(errbuf, "SIOCGIFADDR: %s: %s",
 190                     device, pcap_strerror(errno));
 191                 (void)close(fd);
 192                 return (-1);
 193         }
 194         sin = (struct sockaddr_in *)&ifr.ifr_addr;
 195         *netp = sin->sin_addr.s_addr;
 196         if (ioctl(fd, SIOCGIFNETMASK, (char *)&ifr) < 0) {
 197                 (void)sprintf(errbuf, "SIOCGIFNETMASK: %s: %s",
 198                     device, pcap_strerror(errno));
 199                 (void)close(fd);
 200                 return (-1);
 201         }
 202         (void)close(fd);
 203         *maskp = sin->sin_addr.s_addr;
 204         if (*maskp == 0) {
 205                 if (IN_CLASSA(*netp))
 206                         *maskp = IN_CLASSA_NET;
 207                 else if (IN_CLASSB(*netp))
 208                         *maskp = IN_CLASSB_NET;
 209                 else if (IN_CLASSC(*netp))
 210                         *maskp = IN_CLASSC_NET;
 211                 else {
 212                         (void)sprintf(errbuf, "inet class for 0x%x unknown",
 213                             *netp);
 214                         return (-1);
 215                 }
 216         }
 217         *netp &= *maskp;
 218         return (0);
 219 }