postgresql/src/include/libpq/pqcomm.h

/*-------------------------------------------------------------------------
 *
 * 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.
 *
 * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * $Id: pqcomm.h,v 1.87 2003/06/23 23:51:59 momjian Exp $
 *
 *-------------------------------------------------------------------------
 */
#ifndef PQCOMM_H
#define PQCOMM_H

#ifdef WIN32
#include <winsock.h>
/* workaround for clashing defines of "ERROR" */
#ifdef ELOG_H
#undef ERROR
#define ERROR	(-1)
#endif
#else							/* not WIN32 */
#include <sys/socket.h>
#include <netdb.h>
#ifdef HAVE_SYS_UN_H
#include <sys/un.h>
#endif
#include <netinet/in.h>
#endif   /* not WIN32 */

#ifndef	HAVE_STRUCT_SOCKADDR_STORAGE
/* Define a struct sockaddr_storage if we don't have one. */
/*
 * Desired design of maximum size and alignment
 */
#define _SS_MAXSIZE    128  /* Implementation specific max size */
#define _SS_ALIGNSIZE  (sizeof (int64_t))
                         /* Implementation specific desired alignment */
/*
 * Definitions used for sockaddr_storage structure paddings design.
 */
#define	_SS_PAD1SIZE	(_SS_ALIGNSIZE - sizeof (sa_family_t))
#define	_SS_PAD2SIZE	(_SS_MAXSIZE - (sizeof (sa_family_t) + \
				_SS_PAD1SIZE + _SS_ALIGNSIZE))

struct sockaddr_storage {
#ifdef SALEN
    uint8_t	__ss_len;        /* address length */
#endif
    sa_family_t	ss_family;	/* address family */

    char	__ss_pad1[_SS_PAD1SIZE];
		/* 6 byte pad, this is to make implementation
		 * specific pad up to alignment field that
		 * follows explicit in the data structure */
    int64_t	__ss_align;
		/* field to force desired structure
		 * storage alignment */
    char	__ss_pad2[_SS_PAD2SIZE];
		/* 112 byte pad to achieve desired size,
		 * _SS_MAXSIZE value minus size of ss_family
		 * __ss_pad1, __ss_align fields is 112 */
};
#elif !defined(HAVE_STRUCT_SOCKADDR_STORAGE_SS_FAMILY)
# ifdef HAVE_STRUCT_SOCKADDR_STORAGE___SS_FAMILY
#  define ss_family __ss_family
# else
#  error struct sockaddr_storage does not provide an ss_family member
# endif
#endif

typedef struct {
	struct sockaddr_storage	addr;
	ACCEPT_TYPE_ARG3	salen;
} SockAddr;

/* Some systems don't have it, so default it to 0 so it doesn't
 * have any effect on those systems. */
#ifndef	AI_ADDRCONFIG
#define	AI_ADDRCONFIG 0
#endif

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

#define UNIXSOCK_PATH(path,port,defpath) \
		snprintf(path, sizeof(path), "%s/.s.PGSQL.%d", \
				((defpath) && *(defpath) != '\0') ? (defpath) : \
				DEFAULT_PGSOCKET_DIR, \
				(port))

/*
 * 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(1,0)
#define PG_PROTOCOL_LATEST		PG_PROTOCOL(3,0)

typedef uint32 ProtocolVersion; /* FE/BE protocol version number */

typedef ProtocolVersion MsgType;


/*
 * Packet lengths are 4 bytes in network byte order.
 *
 * The initial length is omitted from the packet layouts appearing below.
 */

typedef uint32 PacketLen;


/*
 * Old-style startup packet layout with fixed-width fields.  This is used in
 * protocol 1.0 and 2.0, but not in later versions.  Note that the fields
 * in this layout are '\0' terminated only if there is room.
 */

#define SM_DATABASE		64
#define SM_USER			32
/* We append database name if db_user_namespace true. */
#define SM_DATABASE_USER (SM_DATABASE+SM_USER+1)		/* +1 for @ */
#define SM_OPTIONS		64
#define SM_UNUSED		64
#define SM_TTY			64

typedef struct StartupPacket
{
	ProtocolVersion protoVersion;		/* Protocol version */
	char		database[SM_DATABASE];	/* Database name */
	/* Db_user_namespace appends dbname */
	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;

extern bool Db_user_namespace;

/*
 * In protocol 3.0 and later, the startup packet length is not fixed, but
 * we set an arbitrary limit on it anyway.  This is just to prevent simple
 * denial-of-service attacks via sending enough data to run the server
 * out of memory.
 */
#define MAX_STARTUP_PACKET_LENGTH 10000


/* These are the authentication request codes 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	/* crypt password */
#define AUTH_REQ_MD5		5	/* md5 password */
#define AUTH_REQ_SCM_CREDS	6	/* transfer SCM credentials */

typedef uint32 AuthRequest;


/*
 * 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;


/*
 * A client can also start by sending a SSL negotiation request, to get a
 * secure channel.
 */
#define NEGOTIATE_SSL_CODE PG_PROTOCOL(1234,5679)

#endif   /* PQCOMM_H */