unix4lyfe git - darkstat/blob - localip.c

   1 /* darkstat 3
   2  * copyright (c) 2001-2008 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 "darkstat.h"
  11 #include "addr.h"
  12 #include "conv.h" /* for strlcpy */
  13 #include "err.h"
  14 #include "localip.h"
  15
  16 #include <sys/socket.h>
  17 #include <net/if.h>
  18 #include <ifaddrs.h>
  19 #include <errno.h>
  20 #include <string.h>
  21 #include <unistd.h>
  22
  23 static const char *iface = NULL;
  24 struct addr localip4, localip6;
  25 static struct addr last_localip4, last_localip6;
  26
  27 void
  28 localip_init(const char *interface)
  29 {
  30    iface = interface;
  31    localip_update();
  32 }
  33
  34 void
  35 localip_update(void)
  36 {
  37    struct ifaddrs *ifas, *ifa;
  38    int got_v4 = 0, got_v6 = 0;
  39
  40    localip4.family = IPv4;
  41    localip6.family = IPv6;
  42
  43    if (iface == NULL) {
  44       /* reading from capfile */
  45       localip4.ip.v4 = 0;
  46       memset(&(localip6.ip.v6), 0, sizeof(localip6.ip.v6));
  47       return;
  48    }
  49
  50    if (getifaddrs(&ifas) < 0)
  51       err(1, "can't get own IP address on interface \"%s\"", iface);
  52
  53    for (ifa = ifas; ifa; ifa = ifa->ifa_next) {
  54       if (got_v4 && got_v6)
  55          break;   /* Task is already complete. */
  56
  57       if (strncmp(ifa->ifa_name, iface, IFNAMSIZ))
  58          continue;   /* Wrong interface. */
  59
  60       /* The first IPv4 name is always functional. */
  61       if ((ifa->ifa_addr->sa_family == AF_INET) && !got_v4)
  62       {
  63          /* Good IPv4 address. */
  64          localip4.ip.v4 =
  65             ((struct sockaddr_in *)ifa->ifa_addr)->sin_addr.s_addr;
  66          got_v4 = 1;
  67          continue;
  68       }
  69
  70       /* IPv6 needs some obvious exceptions. */
  71       if ( ifa->ifa_addr->sa_family == AF_INET6 ) {
  72          struct sockaddr_in6 *sa6 = (struct sockaddr_in6 *) ifa->ifa_addr;
  73
  74          if ( IN6_IS_ADDR_LINKLOCAL(&(sa6->sin6_addr))
  75               || IN6_IS_ADDR_SITELOCAL(&(sa6->sin6_addr)) )
  76             continue;
  77
  78          /* Only standard IPv6 can reach this point. */
  79          memcpy(&(localip6.ip.v6), &sa6->sin6_addr, sizeof(localip6.ip.v6));
  80          got_v6 = 1;
  81       }
  82    }
  83
  84    freeifaddrs(ifas);
  85
  86    /* Report an error if IPv4 address could not be found. */
  87    if (!got_v4)
  88        err(1, "can't get own IPv4 address on interface \"%s\"", iface);
  89
  90    if (!addr_equal(&last_localip4, &localip4)) {
  91       verbosef("localip4 update(%s) = %s", iface, addr_to_str(&localip4));
  92       last_localip4 = localip4;
  93    }
  94    if (!addr_equal(&last_localip6, &localip6)) {
  95       verbosef("localip6 update(%s) = %s", iface, addr_to_str(&localip6));
  96       last_localip6 = localip6;
  97    }
  98 }
  99
 100 /* vim:set ts=3 sw=3 tw=78 expandtab: */