unix4lyfe git - darkstat/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 "conv.h" /* for strlcpy */
  12 #include "err.h"
  13 #include "localip.h"
  14
  15 #include <sys/socket.h>
  16 #include <net/if.h>
  17 #include <ifaddrs.h>
  18 #include <errno.h>
  19 #include <string.h>
  20 #include <unistd.h>
  21
  22 static const char *iface = NULL;
  23 struct addr localip4, localip6;
  24 static struct addr last_localip4, last_localip6;
  25
  26 void
  27 localip_init(const char *interface)
  28 {
  29    iface = interface;
  30    localip_update();
  31 }
  32
  33 void
  34 localip_update(void)
  35 {
  36    struct ifaddrs *ifas, *ifa;
  37    int got_v4 = 0, got_v6 = 0;
  38
  39    localip4.family = IPv4;
  40    localip6.family = IPv6;
  41
  42    if (iface == NULL) {
  43       /* reading from capfile */
  44       localip4.ip.v4 = 0;
  45       memset(&(localip6.ip.v6), 0, sizeof(localip6.ip.v6));
  46       return;
  47    }
  48
  49    if (getifaddrs(&ifas) < 0)
  50       err(1, "can't get own IP address on interface \"%s\"", iface);
  51
  52    for (ifa = ifas; ifa; ifa = ifa->ifa_next) {
  53       if (got_v4 && got_v6)
  54          break;   /* Task is already complete. */
  55
  56       if (strncmp(ifa->ifa_name, iface, IFNAMSIZ))
  57          continue;   /* Wrong interface. */
  58
  59       /* The first IPv4 name is always functional. */
  60       if ((ifa->ifa_addr->sa_family == AF_INET) && !got_v4)
  61       {
  62          /* Good IPv4 address. */
  63          localip4.ip.v4 =
  64             ((struct sockaddr_in *)ifa->ifa_addr)->sin_addr.s_addr;
  65          got_v4 = 1;
  66          continue;
  67       }
  68
  69       /* IPv6 needs some obvious exceptions. */
  70       if ( ifa->ifa_addr->sa_family == AF_INET6 ) {
  71          struct sockaddr_in6 *sa6 = (struct sockaddr_in6 *) ifa->ifa_addr;
  72
  73          if ( IN6_IS_ADDR_LINKLOCAL(&(sa6->sin6_addr))
  74               || IN6_IS_ADDR_SITELOCAL(&(sa6->sin6_addr)) )
  75             continue;
  76
  77          /* Only standard IPv6 can reach this point. */
  78          memcpy(&(localip6.ip.v6), &sa6->sin6_addr, sizeof(localip6.ip.v6));
  79          got_v6 = 1;
  80       }
  81    }
  82
  83    freeifaddrs(ifas);
  84
  85    /* Report an error if IPv4 address could not be found. */
  86    if (!got_v4)
  87        err(1, "can't get own IPv4 address on interface \"%s\"", iface);
  88
  89    if (!addr_equal(&last_localip4, &localip4)) {
  90       verbosef("localip4 update(%s) = %s", iface, addr_to_str(&localip4));
  91       last_localip4 = localip4;
  92    }
  93    if (!addr_equal(&last_localip6, &localip6)) {
  94       verbosef("localip6 update(%s) = %s", iface, addr_to_str(&localip6));
  95       last_localip6 = localip6;
  96    }
  97 }
  98
  99 /* vim:set ts=3 sw=3 tw=78 expandtab: */