// by Doug Lyons for MinGW
// To Compile use: gcc GetInterfaceInfo.c -liphlpapi -o gii.exe

#include <winsock2.h>
#include <iphlpapi.h>
#include <stdio.h>
#include <stdlib.h>

#pragma comment(lib, "iphlpapi.lib")
#define MALLOC(x) HeapAlloc(GetProcessHeap(), 0, (x))
#define FREE(x) HeapFree(GetProcessHeap(), 0, (x))
const int ERROR_BUFFER_OVERFLOW = 111;
const int ERROR_INSUFFICIENT_BUFFER = 122;
const int ERROR_NO_DATA = 232;
const int NO_ERROR = 0;


int main()
{
	
/* Declare and initialize variables */

PIP_INTERFACE_INFO pInfo;
pInfo = (IP_INTERFACE_INFO *) malloc( sizeof(IP_INTERFACE_INFO) );
ULONG ulOutBufLen = 0;
DWORD dwRetVal = 0;

// Make an initial call to GetInterfaceInfo to get
// the necessary size in the ulOutBufLen variable
if ( GetInterfaceInfo(pInfo, &ulOutBufLen) == ERROR_INSUFFICIENT_BUFFER)
{
  free(pInfo);
  pInfo = (IP_INTERFACE_INFO *) malloc (ulOutBufLen);
}

			
// Make a second call to GetInterfaceInfo to get
// the actual data we need
if ((dwRetVal = GetInterfaceInfo(pInfo, &ulOutBufLen)) == NO_ERROR )
{
  printf("\tAdapter Name: %ws\n", pInfo->Adapter[0].Name);
  printf("\tAdapter Index: %ld\n", pInfo->Adapter[0].Index);
  printf("\tNum Adapters: %ld\n", pInfo->NumAdapters);

  // free memory allocated
  free(pInfo);
  pInfo = NULL;
}  
else if (dwRetVal == ERROR_NO_DATA) {
  printf("There are no network adapters with IPv4 enabled on the local system\n");
}

else
{
  printf("GetInterfaceInfo failed.\n");
  LPVOID lpMsgBuf;
            
  if (FormatMessage( 
    FORMAT_MESSAGE_ALLOCATE_BUFFER | 
    FORMAT_MESSAGE_FROM_SYSTEM | 
    FORMAT_MESSAGE_IGNORE_INSERTS,
    NULL,
    dwRetVal,
    MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), // Default language
    (LPTSTR) &lpMsgBuf,
    0,
    NULL ))
  {
    printf("\tError: %s", lpMsgBuf);
  }
  LocalFree( lpMsgBuf );
}

return 0;

}