unix4lyfe git - darkstat-debian/blob - localip.c

   1 /* darkstat 3
   2  * copyright (c) 2001-2011 Emil Mikulic.
   3  *
   4  * localip.c: determine local IP of our capture interface
   5  *
   6  * You may use, modify and redistribute this file under the terms of the
   7  * GNU General Public License version 2. (see COPYING.GPL)
   8  */
   9
  10 #include "addr.h"
  11 #include "config.h" /* for HAVE_IFADDRS_H */
  12 #include "err.h"
  13 #include "localip.h"
  14 #include "bsd.h" /* for strlcpy */
  15
  16 #include <sys/socket.h>
  17 #include <net/if.h>
  18 #include <errno.h>
  19 #include <string.h>
  20 #include <unistd.h>
  21
  22 #ifdef HAVE_IFADDRS_H
  23 # include <ifaddrs.h>
  24 #else
  25 # ifdef HAVE_SYS_SOCKIO_H
  26 #  include <sys/sockio.h> /* for SIOCGIFADDR, especially on Solaris */
  27 # endif
  28 # include <sys/ioctl.h>
  29 #endif
  30
  31 static const char *iface = NULL;
  32 struct addr localip4, localip6;
  33 static struct addr last_localip4, last_localip6;
  34
  35 void
  36 localip_init(const char *interface)
  37 {
  38    iface = interface;
  39
  40    /* defaults */
  41    localip4.family = IPv4;
  42    localip4.ip.v4 = 0;
  43
  44    localip6.family = IPv6;
  45    memset(&(localip6.ip.v6), 0, sizeof(localip6.ip.v6));
  46
  47    last_localip4 = localip4;
  48    last_localip6 = localip6;
  49
  50    /* initial update */
  51    localip_update();
  52 }
  53
  54 static void
  55 localip_update_helper(void)
  56 {
  57    /* defaults */
  58    localip4.family = IPv4;
  59    localip4.ip.v4 = 0;
  60
  61    localip6.family = IPv6;
  62    memset(&(localip6.ip.v6), 0, sizeof(localip6.ip.v6));
  63
  64    if (iface == NULL)
  65       return; /* reading from capfile */
  66
  67 #ifdef HAVE_IFADDRS_H
  68    {
  69       int got_v4 = 0, got_v6 = 0;
  70       struct ifaddrs *ifas, *ifa;
  71
  72       if (getifaddrs(&ifas) < 0) {
  73          warn("can't getifaddrs() on interface \"%s\"", iface);
  74          return;
  75       }
  76
  77       for (ifa = ifas; ifa; ifa = ifa->ifa_next) {
  78          if (got_v4 && got_v6)
  79             break;   /* Task is already complete. */
  80
  81          if (strncmp(ifa->ifa_name, iface, IFNAMSIZ))
  82             continue;   /* Wrong interface. */
  83
  84          if (!ifa->ifa_addr)
  85             continue;   /* This can be NULL, e.g. for ppp0. */
  86
  87          /* The first IPv4 name is always functional. */
  88          if ((ifa->ifa_addr->sa_family == AF_INET) && !got_v4)
  89          {
  90             /* Good IPv4 address. */
  91             localip4.ip.v4 =
  92                ((struct sockaddr_in *)ifa->ifa_addr)->sin_addr.s_addr;
  93             got_v4 = 1;
  94             continue;
  95          }
  96
  97          /* IPv6 needs some obvious exceptions. */
  98          if ( ifa->ifa_addr->sa_family == AF_INET6 ) {
  99             struct sockaddr_in6 *sa6 = (struct sockaddr_in6 *) ifa->ifa_addr;
 100
 101             if ( IN6_IS_ADDR_LINKLOCAL(&(sa6->sin6_addr))
 102                  || IN6_IS_ADDR_SITELOCAL(&(sa6->sin6_addr)) )
 103                continue;
 104
 105             /* Only standard IPv6 can reach this point. */
 106             memcpy(&(localip6.ip.v6), &sa6->sin6_addr, sizeof(localip6.ip.v6));
 107             got_v6 = 1;
 108          }
 109       }
 110
 111       freeifaddrs(ifas);
 112
 113       if (!got_v4)
 114           warnx("can't get own IPv4 address on interface \"%s\"", iface);
 115    }
 116 #else /* don't HAVE_IFADDRS_H */
 117    {
 118       int tmp = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP);
 119       struct ifreq ifr;
 120       struct sockaddr sa;
 121
 122       strlcpy(ifr.ifr_name, iface, IFNAMSIZ);
 123       ifr.ifr_addr.sa_family = AF_INET;
 124       if (ioctl(tmp, SIOCGIFADDR, &ifr) == -1) {
 125          if (errno == EADDRNOTAVAIL) {
 126             verbosef("lost local IP");
 127          } else
 128             warn("can't get own IP address on interface \"%s\"", iface);
 129       } else {
 130          /* success! */
 131          sa = ifr.ifr_addr;
 132          localip4.ip.v4 = ((struct sockaddr_in*)&sa)->sin_addr.s_addr;
 133       }
 134       close(tmp);
 135    }
 136 #endif
 137 }
 138
 139 void
 140 localip_update(void)
 141 {
 142    localip_update_helper();
 143
 144    if (!addr_equal(&last_localip4, &localip4)) {
 145       verbosef("%s ip4 update: %s", iface, addr_to_str(&localip4));
 146       last_localip4 = localip4;
 147    }
 148    if (!addr_equal(&last_localip6, &localip6)) {
 149       verbosef("%s ip6 update: %s", iface, addr_to_str(&localip6));
 150       last_localip6 = localip6;
 151    }
 152 }
 153
 154 /* vim:set ts=3 sw=3 tw=78 expandtab: */