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 "conv.h" /* for strlcpy */
  12 #include "decode.h" /* for ip_to_str, ip6_to_str */
  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
  25 in_addr_t localip = 0;
  26 static in_addr_t last_localip = 0;
  27
  28 struct in6_addr localip6;
  29 static struct in6_addr last_localip6;
  30
  31 void
  32 localip_init(const char *interface)
  33 {
  34    iface = interface;
  35    localip_update();
  36 }
  37
  38 void
  39 localip_update(void)
  40 {
  41    struct ifaddrs *ifas, *ifa;
  42    int flags = 0;
  43
  44 #define HAS_IPV4  0x01
  45 #define HAS_IPV6  0x02
  46
  47    if (iface == NULL) {
  48       /* reading from capfile */
  49       localip = 0;
  50       memset(&localip6, '\0', sizeof(localip6));
  51       return;
  52    }
  53
  54    if (getifaddrs(&ifas) < 0)
  55       err(1, "can't get own IP address on interface \"%s\"", iface);
  56
  57    for (ifa = ifas; ifa; ifa = ifa->ifa_next) {
  58       if (flags == (HAS_IPV4 | HAS_IPV6))
  59          break;   /* Task is already complete. */
  60
  61       if (strncmp(ifa->ifa_name, iface, IFNAMSIZ))
  62          continue;   /* Wrong interface. */
  63
  64       /* The first IPv4 name is always functional. */
  65       if ( (ifa->ifa_addr->sa_family == AF_INET)
  66             && ! (flags & HAS_IPV4) ) {
  67          /* Good IPv4 address. */
  68          localip = ((struct sockaddr_in *) ifa->ifa_addr)->sin_addr.s_addr;
  69          flags |= HAS_IPV4;
  70          continue;
  71       }
  72
  73       /* IPv6 needs some obvious exceptions. */
  74       if( ifa->ifa_addr->sa_family == AF_INET6 ) {
  75          struct sockaddr_in6 *sa6 = (struct sockaddr_in6 *) ifa->ifa_addr;
  76
  77 #ifdef __FreeBSD__
  78          if( IN6_IS_ADDR_LINKLOCAL(&(sa6->sin6_addr))
  79             || IN6_IS_ADDR_SITELOCAL(&(sa6->sin6_addr)) )
  80 #else
  81          if( IN6_IS_ADDR_LINKLOCAL(&(sa6->sin6_addr.s6_addr))
  82             || IN6_IS_ADDR_SITELOCAL(&(sa6->sin6_addr.s6_addr)) )
  83 #endif
  84             continue;
  85          else
  86             /* Only standard IPv6 can reach this point. */
  87             memcpy(&localip6, &sa6->sin6_addr, sizeof(localip6));
  88             flags |= HAS_IPV6;
  89       }
  90    }
  91
  92    freeifaddrs(ifas);
  93
  94    /* Repport an error if IPv4 address could not be found. */
  95    if ( !(flags & HAS_IPV4) )
  96        err(1, "can't get own IPv4 address on interface \"%s\"", iface);
  97
  98    /* struct sockaddr {
  99     *      sa_family_t     sa_family;      * address family, AF_xxx
 100     *      char            sa_data[14];    * 14 bytes of protocol address
 101     *
 102     * struct sockaddr_in {
 103     *      sa_family_t           sin_family;     * Address family
 104     *      unsigned short int    sin_port;       * Port number
 105     *      struct in_addr        sin_addr;       * Internet address
 106     *
 107     * struct in_addr {
 108     *      __u32   s_addr;
 109     */
 110
 111    if (last_localip != localip) {
 112       verbosef("local_ip update(%s) = %s", iface, ip_to_str(localip));
 113       last_localip = localip;
 114    }
 115    if (memcmp(&last_localip6, &localip6, sizeof(localip6))) {
 116       verbosef("local_ip6 update(%s) = %s", iface, ip6_to_str(&localip6));
 117       memcpy(&last_localip6, &localip6, sizeof(localip6));
 118    }
 119 }
 120
 121 /* vim:set ts=3 sw=3 tw=78 expandtab: */