/* connect to the remote host/service */
		if( connect( c->socket , (struct sockaddr*)&c->sin , sizeof(c->sin)) < 0 )
		{
		#if defined( NET_CONN_DEBUG )
			fprintf( stderr , "cannot connect to \"%s.%s\" in net_conn_open:  %s\n" , host , service , strerror( errno ) ) ;
		#endif
			net_conn_close( c ) ;
			return( -1 ) ;
		}

/*
	*** net_socket_open ***

	allocates an active or passive socket.  if the socket is active,
	then it connects to the desired host/service/transport.  if the
	socket is passive, then it binds the socket to the local
	service/transport.
	

	*** parameters ***
		ap:  NET_CONN_PASSIVE for passive , NET_CONN_ACTIVE
			for active
		host:  the host to connect to ( active sockets only , ignored
			for passive sockets )
		service:  the service associated with the desired port, or the
			port number represented as a string
		transport:  the name of the transport protocol to use
		qlen:  the maximum server request queue length ( passive
			sockets only , ignored for active sockets )
		portbase:  the offset to use in case a privileged port is
			requested, but sufficient privileges are not available
*/
struct net_conn* net_conn_alloc( int ap , const char* host , const char* service , const char* transport , int qlen , int portbase )
{
	/* pointer to net_socket struct to hold net_conn info */
	struct net_conn* c ;

	/* allocate a net_conn struct and check it for errors */
	if( (c = calloc( 1 , sizeof(struct net_conn) )) == 0 )
	{
	#if defined( NET_CONN_DEBUG )
		fprintf( stderr , "unable to allocate a struct net_conn in net_conn_alloc\n" ) ;
	#endif
		return( NULL ) ;
	}

	/* set the active/passive flag for the net_conn */
	c->ap = ap ;

	/* initialize the endpoint address */
	c->sin.sin_family = AF_INET ;
	c->sin.sin_addr.s_addr = INADDR_ANY ;

	if( c->ap != NET_CONN_PASSIVE && c->ap != NET_CONN_ACTIVE )
	{
	#if defined( NET_CONN_DEBUG )
		fprintf( stderr , "passed an illegal value for ap to net_conn_alloc:  %d\n" , c->ap ) ;
	#endif
		free( c ) ;
		return( NULL ) ;
	}

	/* Map service name to port number */
	if( (c->se = getservbyname( service , transport )) )
		c->sin.sin_port = htons( ntohs( (u_short) c->se->s_port ) + portbase ) ;
	else if( (c->sin.sin_port = htons((u_short)atoi(service))) == 0 )
	{
	#if defined( NET_CONN_DEBUG )
		fprintf( stderr , "cannot map service/port \"%s\" over transport \"%s\" in socket_alloc\n" , service , transport ) ;
	#endif
		free( c ) ;
		return( NULL ) ;
	}

	if( c->ap == NET_CONN_ACTIVE )
	{
		/* map the host name to an ip address.  allow dotted decimal notation */
		if( (c->he = gethostbyname( host )) )
			memcpy( &c->sin.sin_addr , c->he->h_addr , c->he->h_length ) ;
		else if( (c->sin.sin_addr.s_addr = inet_addr(host)) == INADDR_NONE )
		{
		#if defined( NET_CONN_DEBUG )
			fprintf( stderr , "host \"%s\" cannot be mapped in socket_alloc\n" , host ) ;
		#endif
			free( c ) ;
			return( NULL ) ;
		}
	}

	/* Map transport protocol name to protocol number */
	if( (c->pe = getprotobyname( transport )) == 0 )
	{
	#if defined( NET_CONN_DEBUG )
		fprintf( stderr , "cannot map transport \"%s\" to a protocol numer in socket_alloc\n" , transport ) ;
	#endif
		free( c ) ;
		return( NULL ) ;
	}

	/* Use protocol to choose a socket type */
	if( strcmp( transport , "udp" ) == 0 )
		c->type = SOCK_DGRAM ;
	else if( strcmp( transport , "tcp" ) == 0 )
		c->type = SOCK_STREAM ;
	else
	{
	#if defined( NET_CONN_DEBUG )
		fprintf( stderr , "bad transport \"%s\" in socket_alloc\n" , transport ) ;
	#endif
		free( c ) ;
		return( NULL ) ;
	}

	/* Allocate a socket */
	if( (c->socket = socket( PF_INET , c->type , c->pe->p_proto )) < 0 )
	{
	#if defined( NET_CONN_DEBUG )
		fprintf( stderr , "cannot create socket in socket_alloc:  %s\n" , strerror( errno ) ) ;
	#endif
		free( c ) ;
		return( NULL ) ;
	}

	if( c->ap == NET_CONN_ACTIVE )
	{
		/* connect to the remote host/service */
		if( connect( c->socket , (struct sockaddr*)&c->sin , sizeof(c->sin)) < 0 )
		{
		#if defined( NET_CONN_DEBUG )
			fprintf( stderr , "cannot connect to \"%s.%s\" in socket_alloc:  %s\n" , host , service , strerror( errno ) ) ;
		#endif
			free( c ) ;
			return( NULL ) ;
		}

		return( c ) ;
	}
	else
	{
		/* bind it to the correct transport/service port */
		if( bind( c->socket , (struct sockaddr*) &c->sin , sizeof(c->sin) ) < 0 )
		{
		#if defined( NET_CONN_DEBUG )
			fprintf( stderr , "cannot bind socket to \"%s\" port in socket_alloc:  %s\n" , service , strerror( errno ) ) ;
		#endif
			free( c ) ;
			return( NULL ) ;
		}

		/* set the queue length for the socket connection */
		c->qlen = qlen ;

		if( c->type == SOCK_STREAM && listen( c->socket , c->qlen ) < 0 )
		{
		#if defined( NET_CONN_DEBUG )
			fprintf( stderr , "cannot listen on port \"%s\" in socket_alloc:  %s\n" , service , strerror( errno ) ) ;
		#endif
			free( c ) ;
			return( NULL ) ;
		}

		return( c ) ;
	}
}