#ifndef _X_H_f10b1303_
#define _X_H_f10b1303_

/* This file is in the public domain. */

/*
 * X stuff.  This stuff is used by the client and server code to handle
 *  X forwarding.
 */

/*
 * A CFXREQ is an X forwarding request on the client side; SFXREQ is
 *  the same thing on the server side.  These are opaque handles to
 *  everyone outside of x.c - they are created and returned by
 *  X_forward_req and X_fwdreq_start and are passed to other functions.
 */
typedef struct cfxreq CFXREQ;
typedef struct sfxreq SFXREQ;

/*
 * Client-side stuff.
 *
 * X_forward_req creates and returns a CFXREQ suitable for forwarding
 *  local X connections to a remote server.  It returns a nil pointer
 *  if this cannot be done (eg, if there is no $DISPLAY).
 *
 * X_forward_done destroys a CFXREQ, cleaning up any nascent forwarded
 *  connections based on it.
 *
 * X_fwdreq_gen generates the X-specific part of an X forwarding
 *  request.  (This is just the screen number, but nobody outside x.c
 *  knows enough about X to know that X even *has* screen numbers.)
 *  The first arg points to the space to generate into; the returned
 *  value points just beyond the generated data.
 *
 * X_start_connect is called to initiate the connection to the real
 *  server when a forwarded X connection is received.  The second arg
 *  points to the first six bytes of data on the connection, the
 *  beginning of the header.  The third and fourth args are callbacks,
 *  called when the connection succeeds or fails, respectively; the
 *  fifth arg is passed to the callbacks.  (The success callback's
 *  first arg is a connected file descriptor.)
 */
extern CFXREQ *X_forward_req(void);
extern void X_forward_done(CFXREQ *);
extern void *X_fwdreq_gen(void *, CFXREQ *);
extern void X_start_connect(CFXREQ *, const unsigned char *, void (*)(int, void *), void (*)(void *), void *);

/*
 * Server-side stuff.
 *
 * X_fwdreq_start sets up the server-side stuff for a forwarded X
 *  connection.  Its args are:
 *	data
 *	datalen
 *		These describe the packet beginning with the X-specific
 *		data (the screen number - this is the converse of
 *		X_fwdreq_gen).
 *	restp
 *	restlenp
 *		These receive the part of the packet following the
 *		X-specific data.
 *	fail
 *		A callback called in case of parsing failure.  This
 *		must be something suitable for passing as the third arg
 *		to parse_data().  It is expected to never return.
 *	gotfd
 *		A callback called when an incoming X connection is
 *		received for this forwarding.  Args:
 *			fd	File descriptor on the new connection
 *			chdr	Pointer to the first six bytes of
 *				  protocol data received.
 *			arg	See below.
 *	arg
 *		Passed as the third arg to the gotfd callback.
 *	flags
 *		Zero or more of the XFF_* flags.
 *  This does not actually set up the local X listener; it just
 *  prepares to do so.
 *
 * X_fwdreq_abort aborts the X forwarding request, tearing down any
 *  nascent forwarded connections associated with it.
 *
 * X_fwdreq_go sets up the local X listener.  It is separated from
 *  X_fwdreq_start because there is some non-X-related checking that
 *  needs to happen in between them.
 *
 * X_fwdreq_env is used to set whatever is appropriate in the local
 *  environment for the forwarded X connection.  (In our
 *  implementation, this means just setting $DISPLAY.)  The second arg
 *  is a callback, called for eacn environment variable to be set; its
 *  args are the variable name and the value it is to be set to.
 */
extern SFXREQ *X_fwdreq_start(
	const void *, int,
	const void **, int *,
	void (*)(const void *, const char *, ...),
	void (*)(int, unsigned char *, void *),
	void *,
	unsigned int );
extern void X_fwdreq_abort(SFXREQ *);
extern void X_fwdreq_go(SFXREQ *);
extern void X_fwdreq_env(SFXREQ *, void (*)(const char *, const char *));
/*
 * Flags for the flags argument to X_fwdreq_start().
 *
 * XFF_TCPONLY
 *	This forwarding should be established for TCP only.  This is
 *	necessary to support the stock X forwarding semantics, which
 *	have the assumption that the connection is TCP wired fairly
 *	deeply into them.
 *
 * XFF_SINGLE
 *	This forwarding should be established for only a single
 *	connection; after one connection, it should automatically be
 *	torn down.
 */
#define XFF_TCPONLY 0x00000001
#define XFF_SINGLE  0x00000002

/*
 * General utility stuff.
 *
 * X_put_2(char bo, void *dp, unsigned short int v) puts v, as a 2-byte
 *  integer, to the two bytes pointed to by dp, in byte order as
 *  determined by bo (which must be ASCII 'B' or 'l', per the X
 *  protocol spec).
 *
 * X_auth_len takes a pointer to the 12-byte header at the beginning of
 *  an X data stream and returns the number of bytes following it that
 *  constitute authentication information.
 *
 * X_auth_match takes a pointer to the header at the beginning of an X
 *  data stream (12+X_auth_len() bytes), and the expected protocol and
 *  cookie (each as a pointer-and-length), and returns true if the data
 *  matches or false if it does not.
 *
 * X_pad_roundup takes a byte count and returns it rounded up to a
 *  multiple of 4.  X uses this kind of padding in many places.
 */

extern void X_put_2(char, void *, unsigned short int);
extern int X_auth_len(const unsigned char *);
extern int X_auth_match(const unsigned char *, const void *, int, const void *, int);
extern unsigned int X_pad_roundup(unsigned int);

#endif