//
// UDP Server
//

#include "netlib.h"

int udp_server( const char *host, const char *service )
{
  /* socket stuff */
  int    sock;       /* tcp socket */
  
  /* dual stack listener */
  struct addrinfo hints;
  struct addrinfo *res, *ressave;
  
  /* set-up hints structure */
  bzero(&hints, sizeof(hints));
  hints.ai_family = AF_UNSPEC;
  hints.ai_flags = AI_PASSIVE;
  hints.ai_socktype = SOCK_DGRAM;
  if ( getaddrinfo(host, service, &hints, &res) )
  {
    log_error( "getaddrinfo" );
    return -1;
  }
  ressave = res;
  
  /*
   * "res" has a chain of addrinfo structure filled with
   * 0.0.0.0 (for IPv4), 0:0:0:0:0:0:0:0 (for IPv6) and alike,
   * with port filled for "myservice".
   */
  while (res)
  {
    /* bind() and listen() to res->ai_addr */
    sock = socket(res->ai_family, res->ai_socktype, res->ai_protocol );
    if ( sock < 0 )
      continue;
    
    /* bind */
    if ( bind(sock, res->ai_addr, res->ai_addrlen) == 0 )
      break;  // success
      
      /* error, try again */
      close( sock );
    res = res->ai_next;
  }
  
  freeaddrinfo( ressave );
  
  /* able to bind? */
  if ( !res )
  {
    log_error( "server" );
    return -1;
  }    
  
  return sock;
}