src/libpq/include/libpq/pqcomm.h

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/*-------------------------------------------------------------------------
 *
 * 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) 1996-2005, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * $PostgreSQL: pgsql/src/include/libpq/pqcomm.h,v 1.98 2005/10/15 02:49:44 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   PGERROR
#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 */

#ifdef HAVE_STRUCT_SOCKADDR_STORAGE

#ifndef 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

#ifdef HAVE_STRUCT_SOCKADDR_STORAGE___SS_LEN
#define ss_len __ss_len
#define HAVE_STRUCT_SOCKADDR_STORAGE_SS_LEN 1
#endif
#else                                                   /* !HAVE_STRUCT_SOCKADDR_STORAGE */

/* Define a struct sockaddr_storage if we don't have one. */

struct sockaddr_storage
{
        union
        {
                struct sockaddr sa;             /* get the system-dependent fields */
                int64           ss_align;       /* ensures struct is properly aligned */
                char            ss_pad[128];    /* ensures struct has desired size */
        }                       ss_stuff;
};

#define ss_family       ss_stuff.sa.sa_family
/* It should have an ss_len field if sockaddr has sa_len. */
#ifdef HAVE_STRUCT_SOCKADDR_SA_LEN
#define ss_len          ss_stuff.sa.sa_len
#define HAVE_STRUCT_SOCKADDR_STORAGE_SS_LEN 1
#endif
#endif   /* HAVE_STRUCT_SOCKADDR_STORAGE */

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

/* 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. Not supported any more. */
#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 */