sflsock.c
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sflsock.c
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	/* ----------------------------------------------------------------<Prolog>-
	Name: sflsock.c
	Title: TCP/IP, UDP/IP socket functions
	Package: Standard Function Library (SFL)

	Written: 1996/02/03 iMatix SFL project team <sfl@imatix.com>
	Revised: 2000/01/19

	Notes: The BeOS port of sflsock is incomplete: at last testing,
	BeOS 4.5 gave consistent errors on its select() function,
	apparently due to timer interrupt signals.

	Copyright: Copyright (c) 1996-2000 iMatix Corporation
	License: This is free software; you can redistribute it and/or modify
	it under the terms of the SFL License Agreement as provided
	in the file LICENSE.TXT. This software is distributed in
	the hope that it will be useful, but without any warranty.
	------------------------------------------------------------------</Prolog>-*/

	#include "prelude.h" /* Universal header file */
	#include "sfllist.h" /* List-management functions */
	#include "sflmem.h" /* Memory-allocation functions */
	#include "sflsymb.h" /* Symbol-table functions */
	#include "sfltok.h" /* Token-handling functions */
	#include "sfluid.h" /* User/group functions */
	#include "sflcons.h" /* Console i/o functions */
	#include "sflfile.h" /* File handling functions */
	#include "sflprint.h" /* snprintf functions */
	#include "sflsock.h" /* Prototypes for functions */

	/* Implementation notes
	*
	* These functions work on 16-bit Windows, 32-bit Windows, 32-bit UNIX,
	* 64-bit UNIX, Digital OpenVMS. The size of a socket handle varies from
	* 16 bits to 64 bits. All native socket functions define a socket handle
	* as 'int'. However, we need a fixed-length external representation. So,
	* we define a type, 'sock_t', which is a qbyte (32 bits). Outside this
	* package, sockets are always a 'sock_t'. Internally, we always use an
	* (SOCKET) cast when passing s sock_t to a system function like connect().
	* If the system does not support sockets we fake them just a little.
	*
	* Modifications Oct 7 1998 for Unix by Grant McDorman <grant@isgtec.com> to
	* allow running with the program suid root; it will run as the user until
	* the socket must be opened; at that time, it will briefly switch to root
	* and then return to the actual user id.
	*/

	/* Global variables */

	int
	ip_portbase = 0; /* Base for created services */
	Bool
	ip_nonblock = TRUE; /* Create non-blocking sockets */
	qbyte
	ip_passive = INADDR_ANY; /* IP address for passive connects */
	int
	ip_sockets = 0; /* Number of open sockets */


	/* The connect_error_value holds the last recorded error cause after a */
	/* connection attempt. */

	static int
	connect_error_value = 0;
	char
	connect_errlist [] = { / Corresponding error messages */
	"No errors",
	"System does not support sockets",
	"Host is not known",
	"Service or port not known",
	"Protocol not known",
	"Connection failed on socket()",
	"Connection failed on connect()",
	"Port is already used by another server",
	"Connection failed on listen()"
	};

	/* Internal functions used to create passive and active connections */

	#if (defined (DOES_SOCKETS))
	static void prepare_socket (sock_t handle);
	# if (defined (__WINDOWS__))
	static int win_error (int rc);
	# endif
	#endif


	/* ---------------------------------------------------------------------[<]-
	Function: sock_init

	Synopsis: Initialise the internet protocol. On most systems this is a
	null call. On some systems this loads dynamic libraries. Returns 0
	0 if everything was okay, else returns SOCKET_ERROR. You should call
	sock_term() when your program ends.
	---------------------------------------------------------------------[>]-*/

	int
	sock_init (void)
	{
	#if (defined (__WINDOWS__))
	WORD
	wVersionRequested; /* We really want Winsock 1.1 */
	WSADATA
	wsaData;

	wVersionRequested = 0x0101; /* ... but we'll take 1.1 */
	if (WSAStartup (wVersionRequested, &wsaData) == 0)
	return (0);
	else
	return ((int) SOCKET_ERROR);

	#elif (defined (__UTYPE_BEOS))
	/* BeOS numbers sockets from 0 upwards, but this causes havoc with
	* programs that expect a BSD-style numbering of 1 or higher. We
	* force compatibility by creating (and wasting) one socket so that
	* further socket handles are guaranteed >0.
	*/
	create_socket ("tcp");
	return (0);

	#elif (defined (DOES_SOCKETS))
	return (0);

	#elif (defined (FAKE_SOCKETS))
	return (0);

	#else
	connect_error_value = IP_NOSOCKETS;
	return ((int) SOCKET_ERROR); /* Sockets not supported */
	#endif
	}


	/* ---------------------------------------------------------------------[<]-
	Function: sock_term

	Synopsis: Shuts-down the internet protocol. On most systems this is a
	null call. On some systems this unloads dynamic libraries. Returns -1
	if there was an error, or 0 if everything was okay. See sock_init().
	---------------------------------------------------------------------[>]-*/

	int
	sock_term (void)
	{
	#if (defined (__WINDOWS__))
	WSACleanup ();
	#endif
	return (0);
	}


	/* ---------------------------------------------------------------------[<]-
	Function: passive_TCP

	Synopsis: Creates a passive bound TCP socket for the specified service.
	Returns socket number or INVALID_SOCKET. If it returns INVALID_SOCKET,
	you can get the reason for the error by calling connect_error (). This
	may be one of:
	<TABLE>
	IP_NOSOCKETS Sockets not supported on this system
	IP_BADSERVICE Service cannot be converted to port number
	IP_BADPROTOCOL Cannot understand protocol name
	IP_SOCKETERROR Cannot create the passive socket
	IP_BINDERROR Cannot bind to the port
	IP_LISTENERROR Cannot listen to port
	</TABLE>
	---------------------------------------------------------------------[>]-*/

	sock_t
	passive_TCP (
	const char service, / Service name or port as string */
	int queue_length /* Queue length for listen() */
	)
	{
	ASSERT (service && *service);
	ASSERT (queue_length > 0);
	return (passive_socket (service, "tcp", queue_length));
	}


	/* ---------------------------------------------------------------------[<]-
	Function: passive_UDP

	Synopsis: Creates a passive UDP socket for the specified service.
	Returns socket number or INVALID_SOCKET. If it returns INVALID_SOCKET,
	you can get the reason for the error by calling connect_error (). This
	may be one of:
	<TABLE>
	IP_NOSOCKETS Sockets not supported on this system
	IP_BADSERVICE Service cannot be converted to port number
	IP_BADPROTOCOL Cannot understand protocol name
	IP_SOCKETERROR Cannot create the passive socket
	IP_BINDERROR Cannot bind to the port
	</TABLE>
	---------------------------------------------------------------------[>]-*/

	sock_t
	passive_UDP (
	const char service / Service name or port as string */
	)
	{
	ASSERT (service && *service);
	return (passive_socket (service, "udp", 0));
	}


	/* ---------------------------------------------------------------------[<]-
	Function: passive_socket

	Synopsis:
	Creates a passive TCP or UDP socket. This function allows a server
	program to create a master socket, so that connections can be accepted.
	Used by the passive_TCP and passive_UDP functions. Returns a socket
	number or INVALID_SOCKET. If it returns INVALID_SOCKET, you can get the
	reason for the error by calling connect_error (). This may be one of:
	<TABLE>
	IP_NOSOCKETS Sockets not supported on this system
	IP_BADSERVICE Service cannot be converted to port number
	IP_BADPROTOCOL Cannot understand protocol name
	IP_SOCKETERROR Cannot create the passive socket
	IP_BINDERROR Cannot bind to the port
	IP_LISTENERROR Cannot listen to port
	</TABLE>
	By default, opens a socket on all available IP addresses. You can open
	the socket on a specific address, by setting the global variable
	ip_passive to the address (in network order). This variable is reset
	to INADDR_ANY after each call to passive_socket or one of the functions
	that calls it.
	---------------------------------------------------------------------[>]-*/

	sock_t
	passive_socket (
	const char service, / Service name or port as string */
	const char protocol, / Protocol "tcp" or "udp" */
	int queue_length /* Queue length for TCP sockets */
	)
	{
	#if (defined (DOES_SOCKETS))
	struct servent
	pse; / Service information entry */
	struct sockaddr_in
	sin; /* Internet end-point address */
	sock_t
	handle; /* Socket from socket() call */

	ASSERT (service && *service);
	ASSERT (protocol && *protocol);

	connect_error_value = IP_NOERROR; /* Assume no errors */

	memset ((void *) &sin, 0, sizeof (sin));
	sin.sin_family = AF_INET;
	sin.sin_addr.s_addr = ip_passive;
	ip_passive = INADDR_ANY; /* Reset passive address */

	/* To allow privileged operations, if possible */
	set_uid_root ();

	/* Map service name to port number */
	pse = getservbyname (service, protocol);
	if (pse)
	sin.sin_port = htons ((dbyte) (ntohs (pse-> s_port) + ip_portbase));
	else
	{
	sin.sin_port = atoi (service);
	if (sin.sin_port + ip_portbase > 0)
	sin.sin_port = htons ((dbyte) (sin.sin_port + ip_portbase));
	else
	{
	connect_error_value = IP_BADSERVICE;
	set_uid_user ();
	return (INVALID_SOCKET);
	}
	}
	handle = create_socket (protocol);
	if (handle == INVALID_SOCKET) /* Cannot create the socket */
	{
	set_uid_user ();
	return (INVALID_SOCKET);
	}

	/* Bind the socket */
	if (bind ((SOCKET) handle, (struct sockaddr *) &sin,
	sizeof (sin)) == SOCKET_ERROR)
	{
	connect_error_value = IP_BINDERROR;
	set_uid_user ();
	return (INVALID_SOCKET); /* Cannot bind to port */
	}
	set_uid_user ();

	/* Specify incoming queue length for stream socket */
	if (streq (protocol, "tcp")
	&& listen ((SOCKET) handle, queue_length) == SOCKET_ERROR)
	{
	connect_error_value = IP_LISTENERROR;
	return (INVALID_SOCKET); /* Cannot listen on port */
	}
	return (handle);

	#elif (defined (FAKE_SOCKETS))
	return (1); /* Return dummy handle */

	#else
	connect_error_value = IP_NOSOCKETS;
	return (INVALID_SOCKET); /* Sockets not supported */
	#endif
	}


	/* ---------------------------------------------------------------------[<]-
	Function: create_socket

	Synopsis:
	Creates a TCP or UDP socket. The socket is not connected. To use
	with TCP services you must bind or connect the socket. You can use
	the socket with UDP services - e.g. read_UDP () - immediately. Returns
	a socket number or INVALID_SOCKET, in which case you can get the reason
	for the error by calling connect_error (). This may be one of:
	<TABLE>
	IP_NOSOCKETS Sockets not supported on this system
	IP_BADPROTOCOL Cannot understand protocol name
	IP_SOCKETERROR Cannot create the socket
	</TABLE>
	---------------------------------------------------------------------[>]-*/

	sock_t
	create_socket (
	const char protocol / Protocol "tcp" or "udp" */
	)
	{
	#if (defined (DOES_SOCKETS))
	struct protoent
	ppe; / Protocol information entry */
	int
	# if (!defined (__WINDOWS__))
	true_value = 1, /* Boolean value for setsockopt() */
	# endif
	sock_type; /* Type of socket we want */
	sock_t
	handle; /* Socket from socket() call */

	ASSERT (protocol && *protocol);
	connect_error_value = IP_NOERROR; /* Assume no errors */

	/* Map protocol name to protocol number */
	ppe = getprotobyname (protocol);
	if (ppe == NULL) /* Cannot get protocol entry */
	{
	connect_error_value = IP_BADPROTOCOL;
	return (INVALID_SOCKET);
	}
	/* Use protocol string to choose a socket type */
	if (streq (protocol, "udp"))
	sock_type = SOCK_DGRAM;
	else
	sock_type = SOCK_STREAM;

	/* Allocate a socket */
	handle = (sock_t) socket (AF_INET, sock_type, ppe-> p_proto);
	if (handle == INVALID_SOCKET) /* Cannot create passive socket */
	{
	connect_error_value = IP_SOCKETERROR;
	return (INVALID_SOCKET);
	}
	# if (!defined (__WINDOWS__))
	/* On BSD-socket systems we need to do this to allow the server to
	* restart on a previously-used socket, without an annoying timeout
	* of several minutes. With winsock the reuseaddr option lets the
	* server work with an already-used socket (!), so we don't do it.
	*/
	setsockopt ((SOCKET) handle, SOL_SOCKET, SO_REUSEADDR,
	(char *) &true_value, sizeof (true_value));
	# endif
	prepare_socket (handle); /* Ready socket for use */
	ip_sockets++;
	return (handle);

	#elif (defined (FAKE_SOCKETS))
	return (1); /* Return dummy handle */

	#else
	connect_error_value = IP_NOSOCKETS;
	return (INVALID_SOCKET); /* Sockets not supported */
	#endif
	}


	#if (defined (DOES_SOCKETS))
	/* -------------------------------------------------------------------------
	* prepare_socket -- internal
	*
	* Does any system-specific work required to prepare a socket for normal
	* use. In Windows we have to set the socket to nonblocking mode. In
	* UNIX we do this if the ip_nonblock flag is set.
	*/

	static void
	prepare_socket (sock_t handle)
	{
	#if (defined (__WINDOWS__))
	u_long
	command = ip_nonblock? 1: 0;

	/* Redirect events and set non-blocking mode */
	if (handle != INVALID_SOCKET)
	ioctlsocket ((SOCKET) handle, FIONBIO, &command);

	#elif (defined (__UTYPE_BEOS))
	setsockopt ((SOCKET) handle, SOL_SOCKET, SO_NONBLOCK,
	(void *) &ip_nonblock, sizeof (ip_nonblock));

	#elif (defined (__UNIX__) \|\| defined (__OS2__))
	if (ip_nonblock)
	fcntl ((SOCKET) handle, F_SETFL, O_NONBLOCK
	\| fcntl (handle, F_GETFL, 0));
	#endif
	}
	#endif


	/* ---------------------------------------------------------------------[<]-
	Function: connect_TCP

	Synopsis:
	Creates a TCP socket and connects it to a specified host and service.
	Returns a socket number or INVALID_SOCKET. In that case you can get
	the reason for the error by calling connect_error (). This may be:
	<TABLE>
	IP_NOSOCKETS Sockets not supported on this system
	IP_BADHOST Host is not known
	IP_BADPROTOCOL Cannot understand protocol name
	IP_SOCKETERROR Cannot open a socket
	IP_CONNECTERROR Cannot connect socket
	</TABLE>
	The host name may be a full name, NULL or "" meaning the current host,
	or a dotted-decimal number. The service may be a defined service, e.g.
	"echo", or a port number, specified as an ASCII string. See
	connect_socket() for details.

	Single-threaded clients may set ip_nonblock to FALSE and block on all
	read and write operations. They may use select() if they need to be
	able to time-out during reading/writing.

	Multi-threaded servers should set ip_nonblock to TRUE, and use select()
	to multiplex socket access. When ip_nonblock is TRUE, connect calls
	will return immediately, and the server should use select() to wait until
	the socket is ready for writing. On some systems (early Linux?), the
	select() call will fail in this situation. If you compile with
	-DBLOCKING_CONNECT, connects are done synchronously in all cases.

	Examples:
	sock_t handle;
	handle = connect_TCP ("", "8080");
	handle = connect_TCP (NULL, "echo");
	handle = connect_TCP ("www.imatix.com", "http");
	---------------------------------------------------------------------[>]-*/

	sock_t
	connect_TCP (
	const char host, / Host name */
	const char service / Service name */
	)
	{
	ASSERT (service && *service);
	return (connect_socket (host, /* We have a host name */
	service, /* We have a service name */
	"tcp", /* Protocol is TCP */
	NULL, /* No prepared address */
	3, 0)); /* 3 retries, no waiting */
	}


	/* ---------------------------------------------------------------------[<]-
	Function: connect_UDP

	Synopsis:
	Creates a UDP socket and connects it to a specified host and service.
	Returns a socket number or INVALID_SOCKET. In that case you can get
	the reason for the error by calling connect_error (). This may be:
	<TABLE>
	IP_NOSOCKETS Sockets not supported on this system
	IP_BADHOST Host is not known
	IP_BADPROTOCOL Cannot understand protocol name
	IP_SOCKETERROR Cannot open a socket
	IP_CONNECTERROR Cannot connect socket
	</TABLE>
	The host name may be a full name, NULL or "" meaning the current host,
	or a dotted-decimal number. The service may be a defined service, e.g.
	"echo", or a port number, specified as an ASCII string. See
	connect_socket() for details.

	Single-threaded clients may set ip_nonblock to FALSE and block on all
	read and write operations. They may use select() if they need to be
	able to time-out during reading/writing.

	Multi-threaded servers should set ip_nonblock to TRUE, and use select()
	to multiplex socket access. When ip_nonblock is TRUE, connect calls
	will return immediately, and the server should use select() to wait until
	the socket is ready for writing. On some systems (early Linux?), the
	select() call will fail in this situation. If you compile with
	-DBLOCKING_CONNECT, connects are done synchronously in all cases.

	Examples:
	sock_t handle;
	handle = connect_UDP ("", "7");
	handle = connect_UDP (NULL, "echo");
	handle = connect_UDP ("imatix.com", "echo");
	---------------------------------------------------------------------[>]-*/

	sock_t
	connect_UDP (
	const char host, / Host name */
	const char service / Service name */
	)
	{
	ASSERT (service && *service);
	return (connect_socket (host, /* We have a host name */
	service, /* We have a service name */
	"udp", /* Protocol is UDP */
	NULL, /* No prepared address */
	3, 0)); /* 3 retries, no waiting */
	}


	/* ---------------------------------------------------------------------[<]-
	Function: connect_TCP_fast

	Synopsis: Creates a TCP socket and connects it to a specified host/port
	address. Returns a socket number or INVALID_SOCKET. In that case you
	can get the reason for the error by calling connect_error (). This may
	be:
	<TABLE>
	IP_NOSOCKETS Sockets not supported on this system
	IP_BADHOST Host is not known
	IP_BADPROTOCOL Cannot understand protocol name
	IP_SOCKETERROR Cannot open a socket
	IP_CONNECTERROR Cannot connect socket
	</TABLE>
	This function is faster, if you know the host system address and port,
	than connect_TCP() because no translation is needed.
	You can get the host/address structure by calling address_end_point()
	or get_peer_addr(). See connect_socket() for details.
	---------------------------------------------------------------------[>]-*/

	sock_t
	connect_TCP_fast (
	const struct sockaddr_in sin / Socket address structure */
	)
	{
	ASSERT (sin);
	return (connect_socket (NULL, /* No host name */
	NULL, /* No service name */
	"tcp", /* Protocol is TCP */
	sin, /* We have a prepared address */
	1, 0)); /* 1 retry, no waiting */
	}


	/* ---------------------------------------------------------------------[<]-
	Function: connect_UDP_fast

	Synopsis:
	Creates a UDP socket and connects it to a specified host/port address.
	Returns a socket number or INVALID_SOCKET. In that case you can get
	the reason for the error by calling connect_error (). This may be:
	<TABLE>
	IP_NOSOCKETS Sockets not supported on this system
	IP_BADHOST Host is not known
	IP_BADPROTOCOL Cannot understand protocol name
	IP_SOCKETERROR Cannot open a socket
	IP_CONNECTERROR Cannot connect socket
	</TABLE>
	This function is faster, if you know the host system address and port,
	than connect_UDP() because no translation is needed.
	You can get the host/address structure by calling address_end_point()
	or get_peer_addr(). See connect_socket() for details.
	---------------------------------------------------------------------[>]-*/

	sock_t
	connect_UDP_fast (
	const struct sockaddr_in sin / Socket address structure */
	)
	{
	ASSERT (sin);
	return (connect_socket (NULL, /* No host name */
	NULL, /* No service name */
	"udp", /* Protocol is UDP */
	sin, /* We have a prepared address */
	1, 0)); /* 1 retry, no waiting */
	}


	/* ---------------------------------------------------------------------[<]-
	Function: connect_socket

	Synopsis:
	Makes a connection to a remote TCP or UDP port. This allows a client
	program to start sending information to a server. Used by the
	connect_TCP and connect_UDP functions. Returns a socket number or
	INVALID_SOCKET. If it returns INVALID_SOCKET, you can get the reason
	for the error by calling connect_error (). This may be one of:
	<TABLE>
	IP_NOSOCKETS Sockets not supported on this system
	IP_BADHOST Host is not known
	IP_BADPROTOCOL Cannot understand protocol name
	IP_SOCKETERROR Cannot open a socket
	IP_CONNECTERROR Cannot connect socket
	</TABLE>
	Always blocks until the connection has been made; i.e. when this
	function returns you can start to read and write on the socket.

	The host name may be a full name, NULL or "" meaning the current host,
	or a dotted-decimal number. The service may be a defined service, e.g.
	"echo", or a port number, specified as an ASCII string. Alternatively,
	both these values may be NULL or "", in which case the function uses
	the host_addr argument to supply an address. If you want to build the
	host_addr structure yourself, use build_sockaddr().

	Single-threaded clients may set ip_nonblock to FALSE and block on all
	read and write operations. They may use select() if they need to be
	able to time-out during reading/writing.

	Multi-threaded servers should set ip_nonblock to TRUE, and use select()
	to multiplex socket access. When ip_nonblock is TRUE, connect calls
	will return immediately, and the server should use select() to wait until
	the socket is ready for writing. On some systems (early Linux?), the
	select() call will fail in this situation. If you compile with
	-DBLOCKING_CONNECT, connects are done synchronously in all cases.

	Examples:
	struct sockaddr_in
	host_addr;
	sock_t
	handle;
	build_sockaddr (&host_addr, 32_bit_host, 16_bit_port);
	handle = connect_socket (NULL, NULL, "tcp", &host_addr, 3, 0);
	---------------------------------------------------------------------[>]-*/

	sock_t
	connect_socket (
	const char host, / Name of host, "" = localhost */
	const char service, / Service name or port as string */
	const char protocol, / Protocol "tcp" or "udp" */
	const struct sockaddr_in host_addr, / Socket address structure */
	int retries_left, /* Max. number of retries */
	int retry_delay /* Delay between retries */
	)
	{
	#if (defined (DOES_SOCKETS))
	struct sockaddr_in
	sin; /* Internet end-point address */
	sock_t
	handle = 0; /* Created socket */
	int
	rc; /* Return code from call */
	Bool
	old_nonblock; /* Create non-blocking sockets */

	connect_error_value = IP_NOERROR; /* Assume no errors */

	/* Format sockaddr_in port and hostname, and quit if that failed */
	if (service && strused (service))
	{
	ASSERT (protocol && *protocol);
	if (address_end_point (host, service, protocol, &sin))
	return (INVALID_SOCKET);
	}
	else
	{
	ASSERT (host_addr);
	sin = host_addr; / Fast connect requested */
	}
	/* Connect socket and maybe retry a few times... */
	old_nonblock = ip_nonblock;
	# if (defined (BLOCKING_CONNECT))
	ip_nonblock = FALSE; /* Block on this socket */
	# endif

	while (retries_left)
	{
	handle = create_socket (protocol);
	if (handle == INVALID_SOCKET) /* Unable to open a socket */
	{
	ip_nonblock = old_nonblock;
	return (INVALID_SOCKET);
	}
	rc = connect ((SOCKET) handle, (struct sockaddr *) &sin, sizeof (sin));
	if (rc == 0)
	break; /* Connected okay */
	else
	{
	# if (defined (__WINDOWS__))
	if (WSAGetLastError () == WSAEWOULDBLOCK)
	# else
	if (errno == EINPROGRESS)
	# endif
	break; /* Still connecting, but okay */
	}
	/* Retry if we have any attempts left */
	close_socket (handle);
	if (--retries_left == 0) /* Connection failed */
	{
	connect_error_value = IP_CONNECTERROR;
	ip_nonblock = old_nonblock;
	return (INVALID_SOCKET);
	}
	sleep (retry_delay);
	}
	ip_nonblock = old_nonblock;
	prepare_socket (handle); /* Set final blocking mode */
	return (handle);

	#elif (defined (FAKE_SOCKETS))
	return (1); /* Return dummy handle */

	#else
	connect_error_value = IP_NOSOCKETS;
	return (INVALID_SOCKET); /* Sockets not supported */
	#endif
	}


	/* ---------------------------------------------------------------------[<]-
	Function: connect_to_peer

	Synopsis:
	Connects an unconnected TCP or UDP socket to a peer specified by a
	sockaddr structure. Returns 0 if the connection succeeded, or
	SOCKET_ERROR if there was a problem. In the latter case you can
	get the reason for the error by calling sockmsg().
	---------------------------------------------------------------------[>]-*/

	int
	connect_to_peer (
	sock_t handle, /* Socket to connect */
	const struct sockaddr_in sin / Socket address structure */
	)
	{
	#if (defined (DOES_SOCKETS))
	int
	rc; /* Return code from call */
	Bool
	old_nonblock; /* Create non-blocking sockets */

	ASSERT (sin);
	old_nonblock = ip_nonblock;
	# if (defined (BLOCKING_CONNECT))
	ip_nonblock = FALSE; /* Block on this socket */
	# endif

	rc = connect ((SOCKET) handle, (struct sockaddr ) sin, sizeof (sin));

	ip_nonblock = old_nonblock;
	prepare_socket (handle); /* Set final blocking mode */

	# if (defined (__WINDOWS__))
	return (win_error (rc));
	# else
	return (rc);
	# endif

	#else
	connect_error_value = IP_NOSOCKETS;
	return ((int) SOCKET_ERROR); /* Sockets not supported */
	#endif
	}


	/* ---------------------------------------------------------------------[<]-
	Function: address_end_point

	Synopsis:
	Formats an address block (struct sockaddr_in) for the specified host
	and service (port) information. Returns 0 if okay, SOCKET_ERROR if
	there was an error, in which case you can call connect_error () to get
	the reason for the error. This may be one of:
	<TABLE>
	IP_NOSOCKETS Sockets not supported on this system
	IP_BADHOST Host is not known
	</TABLE>
	---------------------------------------------------------------------[>]-*/

	int
	address_end_point (
	const char host, / Name of host, "" = localhost */
	const char service, / Service name or port as string */
	const char protocol, / Protocol "tcp" or "udp" */
	struct sockaddr_in sin / Block for formatted address */
	)
	{
	#if (defined (DOES_SOCKETS))
	struct hostent
	phe; / Host information entry */
	struct servent
	pse; / Service information entry */
	char
	hostname [MAXHOSTNAMELEN + 1]; /* Name of this system */
	int
	feedback = 0; /* Assume everything works */

	ASSERT (service && *service);
	ASSERT (protocol && *protocol);
	ASSERT (sin);

	connect_error_value = IP_NOERROR; /* Assume no errors */
	memset ((void ) sin, 0, sizeof (sin));
	sin-> sin_family = AF_INET;

	/* Map service name to a port number */
	pse = getservbyname (service, protocol);
	if (pse)
	sin-> sin_port = htons ((short) (ntohs (pse-> s_port)));
	else
	sin-> sin_port = htons ((short) (atoi (service)));

	/* Map host name to IP address, allowing for dotted decimal */
	if (host && strused (host))
	strcpy (hostname, host);
	else
	strcpy (hostname, "127.0.0.1");

	/* Check if it's a valid IP address first */
	sin-> sin_addr.s_addr = inet_addr (hostname);
	if (sin-> sin_addr.s_addr == INADDR_NONE)
	{
	/* Not a dotted address -- try to translate the name */
	phe = gethostbyname (hostname);
	if (phe)
	memcpy ((void *) &sin-> sin_addr, phe-> h_addr, phe-> h_length);
	else
	{ /* Cannot map to host */
	connect_error_value = IP_BADHOST;
	feedback = (int) SOCKET_ERROR;
	}
	}
	return (feedback);

	#else
	connect_error_value = IP_NOSOCKETS;
	return ((int) SOCKET_ERROR); /* Sockets not supported */
	#endif
	}


	/* ---------------------------------------------------------------------[<]-
	Function: build_sockaddr

	Synopsis:
	Builds a socket address structure from the specified host and port
	addresses. Does not return any value except the built structure.
	---------------------------------------------------------------------[>]-*/

	void
	build_sockaddr (
	struct sockaddr_in sin, / Socket address structure */
	qbyte host, /* 32-bit host address */
	dbyte port /* 16-bit port number */
	)
	{
	ASSERT (sin);

	sin-> sin_family = AF_INET;
	sin-> sin_addr.s_addr = htonl (host);
	sin-> sin_port = htons (port);
	}


	/* ---------------------------------------------------------------------[<]-
	Function: socket_localaddr

	Synopsis: Returns a string containing the local host address for the
	specified connected socket. The string is formatted as a string
	"n.n.n.n". Returns the address of a static string or a buffer that
	is overwritten by each call. If sockets are not supported, or there
	was an error, returns the loopback address "127.0.0.1".
	---------------------------------------------------------------------[>]-*/

	char *
	socket_localaddr (
	sock_t handle)
	{
	#define NTOA_MAX 16
	#if (defined (DOES_SOCKETS))
	static char
	localaddr [NTOA_MAX + 1]; /* xxx.xxx.xxx.xxx */
	struct sockaddr_in
	sin; /* Address of local system */

	if (get_sock_addr (handle, &sin, NULL, 0))
	return ("127.0.0.1");
	else
	{
	strncpy (localaddr, inet_ntoa (sin.sin_addr), NTOA_MAX);
	return (localaddr);
	}
	#else
	return ("127.0.0.1");
	#endif
	}


	/* ---------------------------------------------------------------------[<]-
	Function: socket_peeraddr

	Synopsis: Returns a string containing the peer host address for the
	specified connected socket. The string is formatted as a string
	"n.n.n.n". Returns the address of a static string or a buffer that
	is overwritten by each call. If sockets are not supported, or there
	was an error, returns the loopback address "127.0.0.1".
	---------------------------------------------------------------------[>]-*/

	char *
	socket_peeraddr (
	sock_t handle)
	{
	#if (defined (DOES_SOCKETS))
	static char
	peeraddr [NTOA_MAX + 1]; /* xxx.xxx.xxx.xxx */
	struct sockaddr_in
	sin; /* Address of peer system */

	if (get_peer_addr (handle, &sin, NULL, 0))
	return ("127.0.0.1");
	else
	{
	strncpy (peeraddr, inet_ntoa (sin.sin_addr), NTOA_MAX);
	return (peeraddr);
	}
	#else
	return ("127.0.0.1");
	#endif
	}


	/* ---------------------------------------------------------------------[<]-
	Function: socket_nodelay

	Synopsis: Disables Nagle's algorithm for the specified socket; use this
	when you want to ensure that data is sent outwards as fast as possible,
	and when you are certain that Nagle's algorithm is causing a slowdown in
	performance. Recommended for HTTP, but not recommended for telnet.
	Returns 0 if okay, SOCKET_ERROR if there was a problem.
	---------------------------------------------------------------------[>]-*/

	int
	socket_nodelay (
	sock_t handle)
	{
	#if (defined (__WINDOWS__))
	int
	true_value = 1; /* Boolean value for setsockopt() */

	return (setsockopt ((SOCKET) handle, IPPROTO_TCP, TCP_NODELAY,
	(char *) &true_value, sizeof (true_value)));

	#elif (defined (TCP_NODELAY) && defined (SOL_TCP))
	int
	true_value = 1; /* Boolean value for setsockopt() */

	return (setsockopt ((SOCKET) handle, SOL_TCP, TCP_NODELAY,
	(char *) &true_value, sizeof (true_value)));
	#else
	return (0); /* Not applicable to this system */
	#endif
	}


	/* ---------------------------------------------------------------------[<]-
	Function: socket_is_alive

	Synopsis:
	Returns TRUE if the socket is open. Returns FALSE if the socket is no
	longer accessible. You can use this function to check that a socket has
	not been closed by the other party, before doing reading or writing.
	---------------------------------------------------------------------[>]-*/

	Bool
	socket_is_alive (
	sock_t handle)
	{
	#if (defined (__UTYPE_BEOS))
	/* BeOS 4.5 does not support the getsockopt() function */
	int
	rc;

	rc = setsockopt ((SOCKET) handle, SOL_SOCKET, SO_NONBLOCK,
	(void *) &ip_nonblock, sizeof (ip_nonblock));
	return (rc == 0);

	#elif (defined (DOES_SOCKETS))
	int
	socket_type,
	rc;
	argsize_t
	socket_type_size = sizeof (SOCKET);

	rc = getsockopt ((SOCKET) handle, SOL_SOCKET, SO_TYPE,
	(char *) &socket_type, &socket_type_size);
	return (rc == 0);

	#else
	return (FALSE);
	#endif
	}


	/* ---------------------------------------------------------------------[<]-
	Function: socket_error

	Synopsis: Returns an errno value for the socket, or 0 if no error was
	outstanding on the socket. This function is useful if you are handling
	sockets using the select() function: this may return error indicators
	on sockets, without precision on the type of error. This function will
	return the precise error number. Errors like EINPROGRESS, EAGAIN, and
	EWOULDBLOCK can usually be ignored or handled by retrying.
	---------------------------------------------------------------------[>]-*/

	int
	socket_error (
	sock_t handle)
	{
	#if (defined (DOES_SOCKETS))
	# if (defined (__UTYPE_BEOS))
	return (errno);
	# else
	return (getsockopt ((SOCKET) handle, SOL_SOCKET, SO_ERROR, 0, 0));
	# endif
	#else
	return (0);
	#endif
	}


	/* ---------------------------------------------------------------------[<]-
	Function: accept_socket

	Synopsis: Accepts a connection on a specified master socket. If you
	do not want to wait on this call, use select() to poll the socket until
	there is an incoming request, then call accept_socket. Returns the
	number of the new slave socket, or INVALID_SOCKET if there was an error
	on the accept call. You can handle errors as fatal except for EAGAIN
	which indicates that the operation would cause a non-blocking socket to
	block (treat EWOULDBLOCK in the same way).
	---------------------------------------------------------------------[>]-*/

	sock_t
	accept_socket (
	sock_t master_socket)
	{
	#if (defined (DOES_SOCKETS))
	sock_t
	slave_socket; /* Connected slave socket */
	struct sockaddr_in
	sin; /* Address of connecting party */
	argsize_t
	sin_length; /* Length of address */

	connect_error_value = IP_NOERROR; /* Assume no errors */

	sin_length = (int) sizeof (sin);
	slave_socket = accept ((SOCKET) master_socket,
	(struct sockaddr *) &sin, &sin_length);

	/* On non-Windows systems, accept returns -1 in case of error, which */
	/* is the same as INVALID_SOCKET. */
	# if (defined (__WINDOWS__))
	if (slave_socket == INVALID_SOCKET)
	{
	int sock_errno = WSAGetLastError ();
	if (sock_errno == WSAEWOULDBLOCK \|\| sock_errno == WSAEINPROGRESS)
	errno = EAGAIN;
	}
	# endif
	if (slave_socket != INVALID_SOCKET)
	{
	prepare_socket (slave_socket);
	ip_sockets++;
	}
	return (slave_socket);
	#else
	connect_error_value = IP_NOSOCKETS;
	return (INVALID_SOCKET); /* Sockets not supported */
	#endif
	}


	/* ---------------------------------------------------------------------[<]-
	Function: connect_error

	Synopsis:
	Returns the last error code from one of the connection functions. For
	portability in a multithreaded environment, call immediately after the
	call to the connection function.
	---------------------------------------------------------------------[>]-*/

	int
	connect_error (void)
	{
	return (connect_error_value);
	}


	/* ---------------------------------------------------------------------[<]-
	Function: get_sock_addr

	Synopsis: Builds an address block (struct sockaddr_in) for the local
	end of the specified connected socket. Returns 0 if okay, SOCKET_ERROR
	if there was an error. If the name argument is not null, looks-up the
	host name and returns it. The name is truncated to namesize characters,
	including a trailing null character.
	---------------------------------------------------------------------[>]-*/

	int
	get_sock_addr (
	sock_t handle, /* Socket to get address for */
	struct sockaddr_in sin, / Block for formatted address */
	char name, / Buffer for host name, or NULL */
	int namesize /* Size of host name buffer */
	)
	{
	#if (defined (DOES_SOCKETS))
	int
	rc; /* Return code from call */
	struct hostent
	phe; / Host information entry */
	argsize_t
	sin_length; /* Length of address */

	ASSERT (sin);

	/* Get address for local connected socket */
	sin_length = sizeof (struct sockaddr_in);

	rc = getsockname ((SOCKET) handle, (struct sockaddr *) sin, &sin_length);

	/* Translate into host name string, only if wanted */
	if (name != NULL && rc == 0)
	{
	phe = gethostbyaddr ((char *) &sin-> sin_addr,
	sizeof (sin-> sin_addr), AF_INET);
	if (phe)
	{
	strncpy (name, phe-> h_name, namesize);
	name [namesize - 1] = '\0';
	}
	}
	# if (defined (__WINDOWS__))
	return (win_error (rc));
	# else
	return (rc);
	# endif
	#else
	return ((int) SOCKET_ERROR); /* Sockets not supported */
	#endif
	}


	/* ---------------------------------------------------------------------[<]-
	Function: get_peer_addr

	Synopsis: Builds an address block (struct sockaddr_in) for the remote
	end of the specified connected socket. Returns 0 if okay, SOCKET_ERROR
	if there was an error. If the name argument is not null, looks-up the
	host name and returns it. The name is truncated to namesize characters,
	including a trailing null character.
	---------------------------------------------------------------------[>]-*/

	int
	get_peer_addr (
	sock_t handle, /* Socket to get address for */
	struct sockaddr_in sin, / Block for formatted address */
	char name, / Buffer for host name, or NULL */
	int namesize /* Size of host name buffer */
	)
	{
	#if (defined (DOES_SOCKETS))
	int
	rc; /* Return code from call */
	struct hostent
	phe; / Host information entry */
	argsize_t
	sin_length; /* Length of address */

	ASSERT (sin);

	/* Get address for connected socket peer */
	sin_length = sizeof (struct sockaddr_in);
	rc = getpeername ((SOCKET) handle, (struct sockaddr *) sin, &sin_length);

	/* Translate into host name string, only if wanted */
	if (name != NULL && rc == 0)
	{
	phe = gethostbyaddr ((char *) &sin-> sin_addr,
	sizeof (sin-> sin_addr), AF_INET);
	if (phe)
	{
	strncpy (name, phe-> h_name, namesize);
	name [namesize - 1] = '\0';
	}
	}
	# if (defined (__WINDOWS__))
	return (win_error (rc));
	# else
	return (rc);
	# endif
	#else
	return ((int) SOCKET_ERROR); /* Sockets not supported */
	#endif
	}


	/* ---------------------------------------------------------------------[<]-
	Function: read_TCP

	Synopsis:
	Reads data from the socket. On UNIX, VMS, OS/2, passes through to the
	standard read function; some other systems have particular ways of
	accessing sockets. If there is an error on the read this function
	returns SOCKET_ERROR. You can handle errors (in sockerrno) as fatal except
	for EAGAIN which indicates that the operation would cause a non-blocking
	socket to block, and EPIPE or ECONNRESET which indicate that the socket
	was closed at the other end. Treat EWOULDBLOCK as EAGAIN.
	---------------------------------------------------------------------[>]-*/

	int
	read_TCP (
	sock_t handle, /* Socket handle */
	void buffer, / Buffer to receive data */
	size_t length /* Maximum amount of data to read */
	)
	{
	#if (defined (DOES_SOCKETS))
	# if (defined (__UTYPE_BEOS))
	return (recv ((SOCKET) handle, buffer, length, 0));

	# elif (defined (__UNIX__) \|\| defined (__VMS__) \|\| defined (__OS2__))
	return (read ((SOCKET) handle, buffer, length));

	# elif (defined (__WINDOWS__))
	int
	rc; /* Return code from call */

	ASSERT (buffer);
	rc = recv ((SOCKET) handle, buffer, length, 0);
	return (win_error (rc));
	# else
	# error "No code for function body."
	# endif
	#else
	return ((int) SOCKET_ERROR); /* Sockets not supported */
	#endif
	}


	#if (defined (__WINDOWS__))
	/* -------------------------------------------------------------------------
	* win_error -- internal
	*
	* For Winsockets only: fetches real error code and sticks it in errno,
	* if the return code from the last call was SOCKET_ERROR. Returns rc.
	*/

	static int
	win_error (int rc)
	{
	if (rc == (int) SOCKET_ERROR)
	errno = winsock_last_error ();

	return (rc);
	}
	#endif


	/* ---------------------------------------------------------------------[<]-
	Function: write_TCP

	Synopsis:
	Writes data to the socket. On UNIX, VMS, OS/2, calls the standard
	write function; some other systems have particular ways of accessing
	sockets. If there is an error on the write this function returns
	SOCKET_ERROR. You can handle errors (in sockerrno) as fatal except for
	EAGAIN which indicates that the operation would cause a non-blocking
	socket to block, and EPIPE or ECONNRESET which indicate that the socket
	was closed at the other end. Treat EWOULDBLOCK as EAGAIN.
	---------------------------------------------------------------------[>]-*/

	int
	write_TCP (
	sock_t handle, /* Socket handle */
	const void buffer, / Buffer containing data */
	size_t length /* Amount of data to write */
	)
	{
	#if (defined (DOES_SOCKETS))
	# if (defined (__UTYPE_BEOS))
	return (send ((SOCKET) handle, buffer, length, 0));

	# elif (defined (__UNIX__) \|\| defined (__VMS__) \|\| defined (__OS2__))
	return (write ((SOCKET) handle, buffer, length));

	# elif (defined (__WINDOWS__))
	int
	rc; /* Return code from call */

	ASSERT (buffer);
	rc = send ((SOCKET) handle, buffer, length, 0);
	return (win_error (rc));
	# else
	# error "No code for function body."
	# endif
	#else
	return ((int) SOCKET_ERROR); /* Sockets not supported */
	#endif
	}


	/* ---------------------------------------------------------------------[<]-
	Function: read_UDP

	Synopsis:
	Reads data from a connected or unconnected UDP socket. To prepare a
	connected UDP socket you call connect_UDP (). This makes a connection
	to a specific port on a specific host, and returns a socket handle.
	When you call this function with a null value for the address argument,
	it assumes you are using a connected UDP socket.

	To prepare an unconnected UDP socket, call create_socket () with the
	string "udp" as argument. This returns a sock_t handle that you can
	use in this function. If you use an unconnected UDP socket you must
	provide an address structure. The function places the remote host and
	port in this structure. This lets you reply using write_UDP ().

	Generally a server can use unconnected sockets, and a client can use
	connected sockets. You can also format an address for a specific host
	and port using the address_end_point () function.

	If there is an error on the read this function returns SOCKET_ERROR.
	You can handle errors (in sockerrno) as fatal except for EAGAIN which
	indicates that the operation would cause a non-blocking socket to block.
	Treat EWOULDBLOCK as EAGAIN.
	---------------------------------------------------------------------[>]-*/

	int
	read_UDP (
	sock_t handle, /* Socket handle */
	void buffer, / Buffer to receive data */
	size_t length, /* Maximum amount of data to read */
	const struct sockaddr_in sin / Block for address, or null */
	)
	{
	#if (defined (DOES_SOCKETS))
	argsize_t
	sin_length; /* Length of address */
	int
	flags = 0, /* Flags for call */
	rc; /* Return code from call */

	ASSERT (buffer);
	ASSERT (sin);
	sin_length = (int) sizeof (*sin);
	if (sin)
	/* Read from unconnected UDP socket; we accept the address of the */
	/* sending party in the sin argument. */
	rc = recvfrom ((SOCKET) handle, buffer, length, flags,
	(struct sockaddr *) sin, &sin_length);
	else
	/* Read from a connected UDP socket; we don't need to get the */
	/* address, since we already know it. */
	rc = recv ((SOCKET) handle, buffer, length, flags);

	# if (defined (__WINDOWS__))
	return (win_error (rc));
	# else
	return (rc);
	# endif
	#else
	return ((int) SOCKET_ERROR); /* Sockets not supported */
	#endif
	}


	/* ---------------------------------------------------------------------[<]-
	Function: write_UDP

	Synopsis:
	Writes data to a connected or unconnected UDP socket. To prepare a
	connected UDP socket you call connect_UDP (). This makes a connection
	to a specific port on a specific host, and returns a socket handle.
	When you call this function with a null value for the address argument,
	it assumes you are using a connected UDP socket.

	To prepare an unconnected UDP socket, call create_socket () with the
	string "udp" as argument. This returns a sock_t handle that you can
	use in this function. If you use an unconnected UDP socket you must
	provide an address structure containing a valid host and port. You can
	get this information from a read_UDP () or through address_end_point ().

	If there is an error on the write this function returns SOCKET_ERROR.
	You can handle errors as fatal except for EAGAIN which indicates that
	the operation would cause a non-blocking socket to block. Treat
	EWOULDBLOCK as EAGAIN.
	---------------------------------------------------------------------[>]-*/

	int
	write_UDP (
	sock_t handle, /* Socket handle */
	const void buffer, / Buffer containing data */
	size_t length, /* Amount of data to write */
	const struct sockaddr_in sin / Address to send to, or null */
	)
	{
	#if (defined (DOES_SOCKETS))
	int
	sin_length, /* Length of address */
	flags = 0, /* Flags for call */
	rc; /* Return code from call */

	ASSERT (buffer);
	ASSERT (sin);
	sin_length = (int) sizeof (*sin);
	if (sin)
	/* Write to unconnected UDP socket; we provide the address of */
	/* the receiving party in the sin argument. */
	rc = sendto ((SOCKET) handle, buffer, length, flags,
	(struct sockaddr *) sin, sin_length);
	else
	/* Write to a connected UDP socket; we don't need to supply */
	/* the address, since we already know it. */
	rc = send ((SOCKET) handle, buffer, length, flags);

	# if (defined (__WINDOWS__))
	return (win_error (rc));
	# else
	return (rc);
	# endif
	#else
	return ((int) SOCKET_ERROR); /* Sockets not supported */
	#endif
	}


	/* ---------------------------------------------------------------------[<]-
	Function: close_socket

	Synopsis:
	Closes the socket. On UNIX, VMS, OS/2 calls the standard close
	function; some other systems have particular ways of accessing sockets.
	If there is an error on the close this function returns SOCKET_ERROR.
	You can handle errors (in sockerrno) as fatal except for EAGAIN which
	indicates that the operation would cause a non-blocking socket to block.
	Treat EWOULDBLOCK as EAGAIN.
	---------------------------------------------------------------------[>]-*/

	int
	close_socket (
	sock_t handle /* Socket handle */
	)
	{
	#if (defined (DOES_SOCKETS))
	# if (defined (__UNIX__) \|\| defined (__VMS__) \|\| defined (__OS2__))
	if (!socket_is_alive (handle))
	return (0);
	ip_sockets--;
	shutdown (handle, 2);
	return (close ((SOCKET) handle));

	# elif (defined (__WINDOWS__))
	int
	rc;

	if (!socket_is_alive (handle))
	return (0);
	ip_sockets--;
	shutdown ((SOCKET) handle, 2);
	rc = closesocket ((SOCKET) handle);
	return (win_error (rc));

	# else
	# error "No code for function body."
	# endif

	#elif (defined (FAKE_SOCKETS))
	return (0); /* Okay, closed */

	#else
	return ((int) SOCKET_ERROR); /* Sockets not supported */
	#endif
	}

	/* ---------------------------------------------------------------------[<]-
	Function: sock_select

	Synopsis: Performs the standard select() call. Use this in preference
	to select(), as some systems may not be 100% compatible with BSD sockets,
	Uses the same arguments as the select() call, and gives the same return
	codes. If sockets are not supported, always returns 0.
	---------------------------------------------------------------------[>]-*/

	int
	sock_select (int nfds, fd_set readfds, fd_set writefds,
	fd_set errorfds, struct timeval timeout)
	{
	#if (defined (DOES_SOCKETS))
	int
	rc = 0; /* Return code from select() */
	ASSERT (timeout);

	# if (defined (__UTYPE_BEOS))
	/* BeOS only supports the readfds argument */
	rc = select (nfds, FD_SETTYPE readfds, NULL, NULL, timeout);
	if (rc == -1)
	coprintf ("Error after select(): %s", strerror (errno));
	return (rc);

	# elif (defined (WIN32))
	/* Windows occasionally aborts during the select call... */
	__try {
	rc = select (nfds, FD_SETTYPE readfds, FD_SETTYPE writefds,
	FD_SETTYPE errorfds, timeout);
	}
	__except (1) {
	coprintf ("select() aborted - arguments: %d, %p, %p, %p, %p",
	nfds, FD_SETTYPE readfds, FD_SETTYPE writefds,
	FD_SETTYPE errorfds, timeout);
	}
	return (rc);

	# else
	rc = select (nfds, FD_SETTYPE readfds, FD_SETTYPE writefds,
	FD_SETTYPE errorfds, timeout);
	return (rc);
	# endif
	#else
	return (0);
	#endif
	}


	/* ---------------------------------------------------------------------[<]-
	Function: get_hostname

	Synopsis: Returns a string containing the local hostname. The returned
	string is in a static area. Only performs the local hostname lookup one
	time; the returned value is cached for later repeated calls to this
	function. If sockets are not supported, returns the value "localhost".
	---------------------------------------------------------------------[>]-*/

	char *
	get_hostname (void)
	{
	#if (defined (DOES_SOCKETS))
	static char
	host_name [LINE_MAX + 1] = "";

	if (strnull (host_name))
	if (gethostname (host_name, LINE_MAX))
	strcpy (host_name, "localhost");
	return (host_name);
	#else
	return ("localhost");
	#endif
	}


	/* ---------------------------------------------------------------------[<]-
	Function: get_hostaddr

	Synopsis: Returns the current the host address as a 4-byte value in
	host format (not network format). Returns 0x7f000001 (loopback) if
	sockets are not supported or there was an error getting the current
	host IP address. If there are several IP addresses on the system,
	returns one arbitrary address.
	---------------------------------------------------------------------[>]-*/

	qbyte
	get_hostaddr (void)
	{
	#if (defined (DOES_SOCKETS))
	struct hostent
	phe; / Host information entry */

	phe = gethostbyname (get_hostname ());
	if (phe)
	return ((qbyte ) (phe-> h_addr_list [0]));
	else
	return (htonl (SOCKET_LOOPBACK));
	#else
	return (htonl (SOCKET_LOOPBACK));
	#endif
	}


	/* ---------------------------------------------------------------------[<]-
	Function: get_hostaddrs

	Synopsis: Returns a table of all host IP addresses. The table ends in
	a zero address. Each address is a 4-byte value in host format. Returns
	NULL if there was an error. If sockets are not supported, returns a
	table with the loopback address (127.0.0.1) and a null address. The
	caller must free the table using mem_free() when finished using it.
	---------------------------------------------------------------------[>]-*/

	qbyte *
	get_hostaddrs (void)
	{
	#if (defined (DOES_SOCKETS))
	int
	addr_count; /* How many addresses do we have */
	qbyte
	addr_table; / Where we store the addresses */
	struct hostent
	phe; / Host information entry */

	if ((phe = gethostbyname (get_hostname ())) == NULL)
	return (NULL);

	/* Count the addresses */
	for (addr_count = 0; phe-> h_addr_list [addr_count]; addr_count++);

	/* Allocate a table; socket addresses are 4 bytes */
	addr_table = mem_alloc (4 * (addr_count + 1));

	/* Store the addresses */
	for (addr_count = 0; phe-> h_addr_list [addr_count]; addr_count++)
	addr_table [addr_count]
	= (qbyte ) (phe-> h_addr_list [addr_count]);

	addr_table [addr_count] = 0;
	return (addr_table);

	#else
	qbyte
	addr_table; / Where we store the addresses */

	addr_table = mem_alloc (8); /* Addresses are 4 bytes */
	addr_table [0] = htonl (SOCKET_LOOPBACK);
	addr_table [1] = 0;
	return (addr_table);
	#endif
	}


	/* ---------------------------------------------------------------------[<]-
	Function: sock_ntoa

	Synopsis: Converts an IP address in network order to a string in dotted
	format. The string is stored in a statically-allocated buffer that is
	overwritten by each call.
	---------------------------------------------------------------------[>]-*/

	char *
	sock_ntoa (qbyte address)
	{
	static char
	string [16]; /* xxx.xxx.xxx.xxx */
	byte
	*part;

	/* Network order is high-low so we can address the bytes in order */
	part = (byte *) &address;
	snprintf (string, sizeof (string),
	"%d.%d.%d.%d", part [0], part [1], part [2], part [3]);
	return (string);
	}


	/* ---------------------------------------------------------------------[<]-
	Function: sockmsg

	Synopsis:
	Returns a string describing the cause of the last fatal error to occur
	a socket. Should be called directly after a socket i/o operation; if you
	do other i/o operations or allow other threads to proceed in the meantime,
	the returned string may be incorrect.
	---------------------------------------------------------------------[>]-*/

	const char *
	sockmsg (void)
	{
	#if (defined (__WINDOWS__))
	char
	*message;

	switch (WSAGetLastError ())
	{
	case WSAEINTR: message = "WSAEINTR"; break;
	case WSAEBADF: message = "WSAEBADF"; break;
	case WSAEACCES: message = "WSAEACCES"; break;
	case WSAEFAULT: message = "WSAEFAULT"; break;
	case WSAEINVAL: message = "WSAEINVAL"; break;
	case WSAEMFILE: message = "WSAEMFILE"; break;
	case WSAEWOULDBLOCK: message = "WSAEWOULDBLOCK"; break;
	case WSAEINPROGRESS: message = "WSAEINPROGRESS"; break;
	case WSAEALREADY: message = "WSAEALREADY"; break;
	case WSAENOTSOCK: message = "WSAENOTSOCK"; break;
	case WSAEDESTADDRREQ: message = "WSAEDESTADDRREQ"; break;
	case WSAEMSGSIZE: message = "WSAEMSGSIZE"; break;
	case WSAEPROTOTYPE: message = "WSAEPROTOTYPE"; break;
	case WSAENOPROTOOPT: message = "WSAENOPROTOOPT"; break;
	case WSAEPROTONOSUPPORT: message = "WSAEPROTONOSUPPORT"; break;
	case WSAESOCKTNOSUPPORT: message = "WSAESOCKTNOSUPPORT"; break;
	case WSAEOPNOTSUPP: message = "WSAEOPNOTSUPP"; break;
	case WSAEPFNOSUPPORT: message = "WSAEPFNOSUPPORT"; break;
	case WSAEAFNOSUPPORT: message = "WSAEAFNOSUPPORT"; break;
	case WSAEADDRINUSE: message = "WSAEADDRINUSE"; break;
	case WSAEADDRNOTAVAIL: message = "WSAEADDRNOTAVAIL"; break;
	case WSAENETDOWN: message = "WSAENETDOWN"; break;
	case WSAENETUNREACH: message = "WSAENETUNREACH"; break;
	case WSAENETRESET: message = "WSAENETRESET"; break;
	case WSAECONNABORTED: message = "WSAECONNABORTED"; break;
	case WSAECONNRESET: message = "WSAECONNRESET"; break;
	case WSAENOBUFS: message = "WSAENOBUFS"; break;
	case WSAEISCONN: message = "WSAEISCONN"; break;
	case WSAENOTCONN: message = "WSAENOTCONN"; break;
	case WSAESHUTDOWN: message = "WSAESHUTDOWN"; break;
	case WSAETOOMANYREFS: message = "WSAETOOMANYREFS"; break;
	case WSAETIMEDOUT: message = "WSAETIMEDOUT"; break;
	case WSAECONNREFUSED: message = "WSAECONNREFUSED"; break;
	case WSAELOOP: message = "WSAELOOP"; break;
	case WSAENAMETOOLONG: message = "WSAENAMETOOLONG"; break;
	case WSAEHOSTDOWN: message = "WSAEHOSTDOWN"; break;
	case WSAEHOSTUNREACH: message = "WSAEHOSTUNREACH"; break;
	case WSAENOTEMPTY: message = "WSAENOTEMPTY"; break;
	case WSAEPROCLIM: message = "WSAEPROCLIM"; break;
	case WSAEUSERS: message = "WSAEUSERS"; break;
	case WSAEDQUOT: message = "WSAEDQUOT"; break;
	case WSAESTALE: message = "WSAESTALE"; break;
	case WSAEREMOTE: message = "WSAEREMOTE"; break;
	case WSAEDISCON: message = "WSAEDISCON"; break;
	case WSASYSNOTREADY: message = "WSASYSNOTREADY"; break;
	case WSAVERNOTSUPPORTED: message = "WSAVERNOTSUPPORTED"; break;
	case WSANOTINITIALISED: message = "WSANOTINITIALISED"; break;
	default: message = "No error";
	}
	return (message);
	#else
	return (strerror (errno));
	#endif
	}


	#if (defined (__WINDOWS__))
	/* ---------------------------------------------------------------------[<]-
	Function: winsock_last_error

	Synopsis: Convert a winsock error into a errno value.
	---------------------------------------------------------------------[>]-*/

	int
	winsock_last_error (void)
	{
	int
	error = 0;

	switch (WSAGetLastError ())
	{
	case WSAEINTR: error = EINTR; break;
	case WSAEBADF: error = EBADF; break;
	case WSAEWOULDBLOCK: error = EAGAIN; break;
	case WSAEINPROGRESS: error = EAGAIN; break;
	case WSAENETDOWN: error = EAGAIN; break;
	case WSAECONNRESET: error = ECONNRESET; break;
	case WSAECONNABORTED: error = EPIPE; break;
	case WSAESHUTDOWN: error = ECONNRESET; break;
	case WSAEINVAL: error = EPIPE; break;
	# if defined (WIN32)
	default: error = GetLastError ();
	# else
	default: error = errno;
	# endif
	}
	return (error);
	}
	#endif


	/* ---------------------------------------------------------------------[<]-
	Function: socket_is_permitted

	Synopsis: Compares the specified address with a mask and returns
	TRUE if the address matches the mask, or FALSE if it does not. The
	address is formatted as a string "xxx.xxx.xxx.xxx". The mask is
	formatted as zero or more patterns, delimited by whitespace or commas.
	A pattern is an address string, with zero or more of the last
	components replaced by '*'. The pattern may also be prefixed by '!'
	to indicate exclusion. This is an example of a mask: "127.0.0.1,
	253.34., !253.35.". This mask allows all addresses: "*". To get
	the string address for a remote socket, use socket_peer_address().
	---------------------------------------------------------------------[>]-*/

	Bool
	socket_is_permitted (const char address, const char mask)
	{
	char
	addrptr, / Pointer into address */
	maskptr; / Pointer into mask */
	Bool
	negate, /* If !pattern */
	feedback = FALSE; /* False unless matched */

	ASSERT (address);
	ASSERT (mask);

	maskptr = (char *) mask;
	while (*maskptr)
	{
	while (isspace (maskptr) \|\| maskptr == ',')
	maskptr++;

	/* Get negation if necessary */
	if (*maskptr == '!')
	{
	negate = TRUE;
	maskptr++;
	}
	else
	negate = FALSE;

	/* Compare pattern with address up to the end of the pattern */
	for (addrptr = (char ) address; addrptr; addrptr++)
	{
	if (maskptr == '') /* Matched address up to * */
	return (!negate); /* So either accepted or failed */
	else
	if (maskptr == '\0') / Did not match address */
	return (negate); /* so fail unless negated */
	else
	if (addrptr != maskptr) /* Some difference */
	break; /* so stop comparing */

	maskptr++;
	}
	if (addrptr == '\0' / Matched exact address? */
	&& (maskptr == '\0' \|\| isspace (maskptr) \|\| *maskptr == ','))
	return (!negate); /* Either accepted or failed */

	until (maskptr == '\0' \|\| isspace (maskptr) \|\| *maskptr == ',')
	maskptr++; /* Skip to end of this pattern */
	}
	return (feedback);
	}


	/* ---------------------------------------------------------------------[<]-
	Function: get_host_file

	Synopsis: returns the full path name of the host lookup file, if provided
	by the OS, and found. If not found, returns "hosts". The returned string
	is held in a static area of memory that may be overwritten by each call.
	---------------------------------------------------------------------[>]-*/

	char *
	get_host_file (void)
	{
	#if (defined (WIN32))
	static OSVERSIONINFO
	version_info;
	static char
	name [LINE_MAX + 1];

	strclr (name);
	GetWindowsDirectory (name, LINE_MAX);
	version_info.dwOSVersionInfoSize = sizeof (OSVERSIONINFO);
	if (GetVersionEx (&version_info))
	/* On Windows NT the hosts file is well-hidden; on Win95 it's
	* more visible */
	if (version_info.dwPlatformId == VER_PLATFORM_WIN32_NT)
	strcat (name, "\\system32\\drivers\\etc\\hosts");
	else
	strcat (name, "\\hosts");
	return (name);

	#elif (defined (__UNIX__))
	return ("/etc/hosts");

	#elif (defined (__VMS__))
	return ("/etc/hosts"); /* Not correct -- needs more work */

	#elif (defined (__OS2__))
	/* Under OS/2 the hosts information is stored in the "hosts" file which
	* is in the directory pointed at by the %ETC% environment variable.
	* If that environment variable is not set, then TCP/IP support is not
	* properly installed. In that instance we return "/mptn/etc/hosts"
	* (the likely value on OS/2 Warp 3 Connect and OS/2 Warp 4) and hope
	* for the best.
	*/

	/* A static array is used only because the other versions use a static
	* array. If the resulting file name will not fit in the space allowed
	* then "/mtpn/etc/hosts" is used as before.
	*/
	static char
	name [LINE_MAX + 1];
	char
	*etcenv = NULL;

	etcenv = getenv ("ETC");
	if (etcenv != NULL && strlen (etcenv) < (LINE_MAX - 6))
	{ /* We've already checked it will all fit. */
	strcpy (name, etcenv);
	strcat (name, "/hosts");
	return (name);
	}
	else
	return ("/mptn/etc/hosts");

	#else
	return ("hosts");
	#endif
	}


	/* ---------------------------------------------------------------------[<]-
	Function: get_name_server

	Synopsis: gets the addresses of the DNS servers defined in the TCP/IP
	configuration. The addresses are returned in a user-provided struct
	sockaddr_in array. The maximum number of addresses in this array is
	supplied as the ns_max argument. Return the number of address found.
	---------------------------------------------------------------------[>]-*/

	int
	get_name_server (struct sockaddr_in *ns_address, int ns_max)
	{
	int
	ns_count = 0; /* Number of servers that we found */

	#if (defined (WIN32))
	static OSVERSIONINFO
	version_info;
	HKEY
	hkey; /* Handle to returned reg. key */
	static char
	registry_value [LINE_MAX + 1]; /* DNS server info from registry */
	long
	size = LINE_MAX; /* Max. size of returned value */
	DWORD
	type;
	char
	*key,
	**address_list = NULL;
	int
	address_nbr;

	/* Look in registry; this sometimes works, but not always */
	version_info.dwOSVersionInfoSize = sizeof (OSVERSIONINFO);
	if (GetVersionEx (&version_info)
	&& version_info.dwPlatformId == VER_PLATFORM_WIN32_NT)
	key = "SYSTEM\\CurrentControlSet\\Services\\Tcpip\\Parameters";
	else
	key = "SYSTEM\\CurrentControlSet\\Services\\Vxd\\Mstcp\\Parameters";

	if (RegOpenKeyEx (HKEY_LOCAL_MACHINE, key, 0,
	KEY_QUERY_VALUE, &hkey) == ERROR_SUCCESS
	&& RegQueryValueEx (hkey, "NameServer", NULL, (LPDWORD) &type,
	(LPBYTE) registry_value, (LPDWORD) &size) == ERROR_SUCCESS)
	{
	address_list = tok_split (registry_value);
	for (address_nbr = 0; address_list [address_nbr]; address_nbr++)
	{
	if (ns_count >= ns_max)
	break;

	ns_address [ns_count].sin_family = AF_INET;
	ns_address [ns_count].sin_port = htons (DNS_PORT);
	ns_address [ns_count].sin_addr.s_addr =
	inet_addr (address_list [address_nbr]);
	ns_count++;
	}
	tok_free (address_list);
	RegCloseKey (hkey);
	}

	#elif (defined (__UNIX__))
	static char
	buffer [LINE_MAX + 1],
	address [16];
	FILE
	*resolver;
	int
	rc;

	resolver = file_open ("/etc/resolv.conf", 'r');
	if (resolver)
	{
	while (file_read (resolver, buffer))
	{
	rc = sscanf (buffer, "nameserver %s", address);
	if (rc > 0 && rc != EOF)
	{
	if (ns_count >= ns_max)
	break;

	ns_address [ns_count].sin_family = AF_INET;
	ns_address [ns_count].sin_port = htons (DNS_PORT);
	ns_address [ns_count].sin_addr.s_addr = inet_addr (address);
	ns_count++;
	}
	}
	file_close (resolver);
	}

	#elif (defined (__OS2__))
	static char
	buffer [LINE_MAX + 1],
	address [16];
	char
	*etcenv = NULL,
	*filename = NULL;
	FILE
	*resolver = NULL;
	int
	rc;

	/* Under OS/2 the file controlling the resolver is stored in the */
	/* directory pointed at by the ETC environment variable. It is called */
	/* resolv2 or resolv (I think that is the order of preference), so we */
	/* try those two file names in that order. */

	/* If the ETC environment variable is not set we try the /mptn/etc */
	/* directory since that is a likely default location for it. */

	etcenv = getenv ("ETC");
	if (etcenv)
	{
	filename = mem_alloc (strlen(etcenv) + 10);
	if (!filename)
	return 0; /* Cannot allocate memory for filename */

	strcpy (filename, etcenv);
	strcat (filename, "/resolv2");

	resolver = file_open (filename, 'r');

	if (! resolver)
	{ /* Not available under that filename, let's try the other one */
	strcpy (filename, etcenv);
	strcat (filename, "/resolv");

	resolver = file_open (filename, 'r');
	}
	mem_free (filename);
	}
	else
	{ /* No environment variable around, try using the defaults */
	resolver = file_open ("/mptn/etc/resolv2", 'r');
	if (! resolver)
	resolver = file_open ("/mptn/etc/resolv", 'r');
	}
	if (resolver)
	{
	while (file_read (resolver, buffer))
	{
	rc = sscanf (buffer, "nameserver %s", address);
	if (rc > 0 && rc != EOF)
	{
	if (ns_count >= ns_max)
	break;

	ns_address [ns_count].sin_family = AF_INET;
	ns_address [ns_count].sin_port = htons (DNS_PORT);
	ns_address [ns_count].sin_addr.s_addr = inet_addr (address);
	ns_count++;
	}
	}
	file_close (resolver);
	}
	#endif

	return (ns_count);
	}


	/* We fake some BSD functions that are missing on some systems */
	#if (defined (__VMS__) \|\| defined (__UTYPE_BEOS))
	struct protoent getprotobyname (const char protocol)
	{
	static struct protoent
	proto = { NULL, NULL, 0 };

	if (streq (protocol, "udp"))
	proto.p_proto = IPPROTO_UDP;
	else
	if (streq (protocol, "tcp"))
	proto.p_proto = IPPROTO_TCP;
	else
	if (streq (protocol, "icmp"))
	proto.p_proto = IPPROTO_ICMP;

	return (&proto);
	}

	struct protoent *getprotobynumber (int protocol)
	{
	static struct protoent
	proto = { NULL, NULL, 0 };

	if (protocol == IPPROTO_UDP)
	proto.p_name = "udp";
	else
	if (protocol == IPPROTO_TCP)
	proto.p_name = "tcp";
	else
	if (protocol == IPPROTO_ICMP)
	proto.p_name = "icmp";

	return (&proto);
	}

	struct servent getservbyport (int port, const char protocol)
	{
	static char
	fmtnumber [9];
	static struct servent
	service = { NULL, NULL, 0, NULL };
	sprintf (fmtnumber, "%d", port);
	service.s_name = fmtnumber;
	return (&service);
	}
	#endif

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