/*
 ============================================================================
 Name        : test-gethostbyname.c
 Author      : 
 Version     :
 Copyright   : Your copyright notice
 Description : Hello World in C, Ansi-style
 ============================================================================
 */

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

//gethostbyname()
#include <netdb.h>

//inet_ntoa()
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

//sleep()
#include <unistd.h>


void print_error( int h_error )
{
   switch( h_error )
   {
   case HOST_NOT_FOUND:
      printf("%s HOST_NOT_FOUND The specified host is unknown.\n", __func__ );
      break;
   case NO_ADDRESS:
   //case NO_DATA:
      printf("%s NO_ADDRESS or NO_DATA The requested name is valid but does not have an IP address.\n", __func__ );
      break;
   case NO_RECOVERY:
      printf("%s NO_RECOVERY A nonrecoverable name server error occurred.\n", __func__ );
      break;
   case TRY_AGAIN:
      printf("%s TRY_AGAIN, name server could not be connected.\n", __func__ );
      break;
   default:
      printf("%s unknown state (h_error %d).\n", __func__, h_error );
   }
}


int main(void)
{
int idx;
struct hostent* p_hostent;

	printf("%s start.\n", __func__ );

#define TEST01 //also TEST02
#ifdef TEST01
#ifdef MYHOSTENT
   /* Description of data base entry for a single host.  */
   struct hostent
   {
     char *h_name;         /* Official name of host.  */
     char **h_aliases;     /* Alias list.  */
     int h_addrtype;    /* Host address type.  */
     int h_length;         /* Length of address.  */
     char **h_addr_list;      /* List of addresses from name server.  */
     p_aline
   #ifdef __USE_MISC
   # define h_addr   h_addr_list[0] /* Address, for backward compatibility.*/
   #endif
   };
#endif //MYHOSTENT
   //https://man7.org/linux/man-pages/man3/gethostbyname.3.html
   p_hostent = gethostbyname( "www.msn.com" );
   //p_hostent = gethostbyname( "www.teledyne.com" );
   //p_hostent = gethostbyname( "www.google.com" );
   //p_hostent = gethostbyname( "www.yahoo.com" );

   if( p_hostent == NULL )
   {
      printf("%s p_hostent is NULL\n", __func__ );
      print_error( h_errno );
   }
   else
   {
      if( p_hostent->h_name )
         printf("%s h_name %s\n", __func__, p_hostent->h_name );
      idx = 0;
      while( p_hostent->h_aliases[ idx ] != NULL )
      {
         printf("%s h_aliases[%d] %s\n", __func__, idx, p_hostent->h_aliases[ idx ] );
         idx++;
      }
      printf("%s h_addrtype %d\n", __func__, (int)p_hostent->h_addrtype );
      printf("%s h_length %d\n", __func__, (int)p_hostent->h_length);
      idx = 0;
      while( p_hostent->h_addr_list[ idx ] != NULL )
      {
         printf("%s h_addr_list[%d] %s\n", __func__, idx, inet_ntoa( *( struct in_addr* )p_hostent->h_addr_list[ idx ] ) );
         idx++;
      }
   }
#endif //TEST01

   printf("%s finished.\n", __func__ );
	return EXIT_SUCCESS;
}