/*-------------------------------------------------------------------------
 *
 * pqcomm.h
 *		Definitions common to frontends and backends.
 *
 * NOTE: for historical reasons, this does not correspond to pqcomm.c.
 * pqcomm.c's routines are declared in libpq.h.
 *
 * Copyright (c) 1994, Regents of the University of California
 *
 * $Id: pqcomm.h,v 1.37 1999/07/15 23:03:50 momjian Exp $
 *
 *-------------------------------------------------------------------------
 */
#ifndef PQCOMM_H
#define PQCOMM_H

#include "postgres.h"

#include <stdio.h>
#include <sys/types.h>
#ifdef WIN32
#include "winsock.h"
#else
#include <sys/socket.h>
#include <sys/un.h>
#include <netinet/in.h>
#endif

/*
 * Internal send/receive buffers in libpq.
 */
#define PQ_BUFFER_SIZE 8192

/* Define a generic socket address type. */

typedef union SockAddr
{
	struct sockaddr sa;
	struct sockaddr_in in;
#ifndef WIN32
	struct sockaddr_un un;
#endif
} SockAddr;


/* Configure the UNIX socket address for the well known port. */

#if defined(SUN_LEN)
#define UNIXSOCK_PATH(sun,port) \
	(sprintf((sun).sun_path, "/tmp/.s.PGSQL.%d", (port)), SUN_LEN(&(sun)))
#else
#define UNIXSOCK_PATH(sun,port) \
	(sprintf((sun).sun_path, "/tmp/.s.PGSQL.%d", (port)), \
	 strlen((sun).sun_path)+ offsetof(struct sockaddr_un, sun_path))
#endif

/*
 *		We do this because sun_len is in BSD's struct, while others don't.
 *		We never actually set BSD's sun_len, and I can't think of a
 *		platform-safe way of doing it, but the code still works. bjm
 */

/*
 * These manipulate the frontend/backend protocol version number.
 *
 * The major number should be incremented for incompatible changes.  The minor
 * number should be incremented for compatible changes (eg. additional
 * functionality).
 *
 * If a backend supports version m.n of the protocol it must actually support
 * versions m.0..n].  Backend support for version m-1 can be dropped after a
 * `reasonable' length of time.
 *
 * A frontend isn't required to support anything other than the current
 * version.
 */

#define PG_PROTOCOL_MAJOR(v)	((v) >> 16)
#define PG_PROTOCOL_MINOR(v)	((v) & 0x0000ffff)
#define PG_PROTOCOL(m,n)	(((m) << 16) | (n))

/* The earliest and latest frontend/backend protocol version supported. */

#define PG_PROTOCOL_EARLIEST	PG_PROTOCOL(0,0)
#define PG_PROTOCOL_LATEST	PG_PROTOCOL(2,0)

/*
 * All packets sent to the postmaster start with the length.  This is omitted
 * from the different packet definitions specified below.
 */

typedef uint32 PacketLen;


/*
 * Startup message parameters sizes.  These must not be changed without changing
 * the protcol version.  These are all strings that are '\0' terminated only if
 * there is room.
 */

#define SM_DATABASE		64
#define SM_USER			32
#define SM_OPTIONS		64
#define SM_UNUSED		64
#define SM_TTY			64

typedef uint32 ProtocolVersion; /* Fe/Be protocol version nr. */

typedef struct StartupPacket
{
	ProtocolVersion protoVersion;		/* Protocol version */
	char		database[SM_DATABASE];	/* Database name */
	char		user[SM_USER];	/* User name */
	char		options[SM_OPTIONS];	/* Optional additional args */
	char		unused[SM_UNUSED];		/* Unused */
	char		tty[SM_TTY];	/* Tty for debug output */
} StartupPacket;


/* These are the authentication requests sent by the backend. */

#define AUTH_REQ_OK		0		/* User is authenticated  */
#define AUTH_REQ_KRB4		1	/* Kerberos V4 */
#define AUTH_REQ_KRB5		2	/* Kerberos V5 */
#define AUTH_REQ_PASSWORD	3	/* Password */
#define AUTH_REQ_CRYPT		4	/* Encrypted password */

typedef uint32 AuthRequest;


/* This next section is to maintain compatibility with protocol v0.0. */

#define STARTUP_MSG		7		/* Initialise a connection */
#define STARTUP_KRB4_MSG	10	/* krb4 session follows */
#define STARTUP_KRB5_MSG	11	/* krb5 session follows */
#define STARTUP_PASSWORD_MSG	14		/* Password follows */

typedef ProtocolVersion MsgType;


/* A client can also send a cancel-current-operation request to the postmaster.
 * This is uglier than sending it directly to the client's backend, but it
 * avoids depending on out-of-band communication facilities.
 */

/* The cancel request code must not match any protocol version number
 * we're ever likely to use.  This random choice should do.
 */
#define CANCEL_REQUEST_CODE PG_PROTOCOL(1234,5678)

typedef struct CancelRequestPacket
{
	/* Note that each field is stored in network byte order! */
	MsgType		cancelRequestCode;		/* code to identify a cancel
										 * request */
	uint32		backendPID;		/* PID of client's backend */
	uint32		cancelAuthCode; /* secret key to authorize cancel */
} CancelRequestPacket;

#endif	 /* PQCOMM_H */
