C언어로 IP 주소 읽기

 //------------------------------------------------------------------------------
//
// Get machine ip addresses by sockaddr for sockaddr_in/sockaddr_in6.
//
// AUTHOR  : Yubin Lim
// DATE    : 2004-11-05
// EMAIL   : purewell at purewell dot biz
// REQUIRE : Linux,
//                  GNU C/C++ Compiler
//
//------------------------------------------------------------------------------


# include <sys/types.h>
# include <sys/socket.h>
# include <sys/select.h>
# include <sys/ioctl.h>
# include <netdb.h>
# include <netinet/in.h>
# include <netinet/tcp.h>
# include <arpa/inet.h>
# include <pthread.h>
# include <unistd.h>
# include <sys/epoll.h>
# include <net/if.h>
# include <linux/sockios.h>

static bool linux_getMyIP(int nFamily)
{
  int             sock;
  int             nRet;

  size_t          nNIC;
  const size_t    nMaxNIC = 256;

  struct ifconf   ifc;
  struct ifreq    ifr[nMaxNIC];

  struct sockaddr* pAddr(NULL);
  struct sockaddr_in addr4;
  struct sockaddr_in6 addr6;

  sock = socket(nFamily, SOCK_STREAM, 0);
  if ( sock == -1 ) return false;

  ifc.ifc_len = sizeof(ifr);
  ifc.ifc_ifcu.ifcu_req = ifr;

  nRet = ioctl(sock, SIOCGIFCONF, &ifc);
  if ( nRet == -1) return false;

  close(sock);

  nNIC = ifc.ifc_len / sizeof(struct ifreq);

  addr_buf.nIPVersion = nFamily;

  for ( size_t i = 0 ; i < nNIC; i ++ )
  {
    if ( nFamily == ifc.ifc_ifcu.ifcu_req[i].ifr_ifru.ifru_addr.sa_family )
    {
      // todo convert binary to string...
      // if nFamily is AF_INET then pAddr is struct sockaddr_in*.
      // else if nFamily is AF_INET6 then pAddr is struct sockaddr_in6*.
      pAddr = (&ifc.ifc_ifcu.ifcu_req[i].ifr_ifru.ifru_addr);
    }
  }

  return true;
}