src/include/libpq/pqcomm.h

   1 /*-------------------------------------------------------------------------
   2  *
   3  * pqcomm.h
   4  *              Definitions common to frontends and backends.
   5  *
   6  * NOTE: for historical reasons, this does not correspond to pqcomm.c.
   7  * pqcomm.c's routines are declared in libpq.h.
   8  *
   9  * Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
  10  * Portions Copyright (c) 1994, Regents of the University of California
  11  *
  12  * src/include/libpq/pqcomm.h
  13  *
  14  *-------------------------------------------------------------------------
  15  */
  16 #ifndef PQCOMM_H
  17 #define PQCOMM_H
  18
  19 #include <sys/socket.h>
  20 #include <sys/un.h>
  21 #include <netdb.h>
  22 #include <netinet/in.h>
  23
  24 typedef struct
  25 {
  26         struct sockaddr_storage addr;
  27         socklen_t       salen;
  28 } SockAddr;
  29
  30 /* Configure the UNIX socket location for the well known port. */
  31
  32 #define UNIXSOCK_PATH(path, port, sockdir) \
  33            (AssertMacro(sockdir), \
  34                 AssertMacro(*(sockdir) != '\0'), \
  35                 snprintf(path, sizeof(path), "%s/.s.PGSQL.%d", \
  36                                  (sockdir), (port)))
  37
  38 /*
  39  * The maximum workable length of a socket path is what will fit into
  40  * struct sockaddr_un.  This is usually only 100 or so bytes :-(.
  41  *
  42  * For consistency, always pass a MAXPGPATH-sized buffer to UNIXSOCK_PATH(),
  43  * then complain if the resulting string is >= UNIXSOCK_PATH_BUFLEN bytes.
  44  * (Because the standard API for getaddrinfo doesn't allow it to complain in
  45  * a useful way when the socket pathname is too long, we have to test for
  46  * this explicitly, instead of just letting the subroutine return an error.)
  47  */
  48 #define UNIXSOCK_PATH_BUFLEN sizeof(((struct sockaddr_un *) NULL)->sun_path)
  49
  50 /*
  51  * A host that looks either like an absolute path or starts with @ is
  52  * interpreted as a Unix-domain socket address.
  53  */
  54 static inline bool
  55 is_unixsock_path(const char *path)
  56 {
  57         return is_absolute_path(path) || path[0] == '@';
  58 }
  59
  60 /*
  61  * These manipulate the frontend/backend protocol version number.
  62  *
  63  * The major number should be incremented for incompatible changes.  The minor
  64  * number should be incremented for compatible changes (eg. additional
  65  * functionality).
  66  *
  67  * If a backend supports version m.n of the protocol it must actually support
  68  * versions m.[0..n].  Backend support for version m-1 can be dropped after a
  69  * `reasonable' length of time.
  70  *
  71  * A frontend isn't required to support anything other than the current
  72  * version.
  73  */
  74
  75 #define PG_PROTOCOL_MAJOR(v)    ((v) >> 16)
  76 #define PG_PROTOCOL_MINOR(v)    ((v) & 0x0000ffff)
  77 #define PG_PROTOCOL(m,n)        (((m) << 16) | (n))
  78
  79 /*
  80  * The earliest and latest frontend/backend protocol version supported.
  81  * (Only protocol version 3 is currently supported)
  82  */
  83
  84 #define PG_PROTOCOL_EARLIEST    PG_PROTOCOL(3,0)
  85 #define PG_PROTOCOL_LATEST              PG_PROTOCOL(3,0)
  86
  87 typedef uint32 ProtocolVersion; /* FE/BE protocol version number */
  88
  89 typedef ProtocolVersion MsgType;
  90
  91
  92 /*
  93  * Packet lengths are 4 bytes in network byte order.
  94  *
  95  * The initial length is omitted from the packet layouts appearing below.
  96  */
  97
  98 typedef uint32 PacketLen;
  99
 100 extern PGDLLIMPORT bool Db_user_namespace;
 101
 102 /*
 103  * In protocol 3.0 and later, the startup packet length is not fixed, but
 104  * we set an arbitrary limit on it anyway.  This is just to prevent simple
 105  * denial-of-service attacks via sending enough data to run the server
 106  * out of memory.
 107  */
 108 #define MAX_STARTUP_PACKET_LENGTH 10000
 109
 110
 111 /* These are the authentication request codes sent by the backend. */
 112
 113 #define AUTH_REQ_OK                     0       /* User is authenticated  */
 114 #define AUTH_REQ_KRB4           1       /* Kerberos V4. Not supported any more. */
 115 #define AUTH_REQ_KRB5           2       /* Kerberos V5. Not supported any more. */
 116 #define AUTH_REQ_PASSWORD       3       /* Password */
 117 #define AUTH_REQ_CRYPT          4       /* crypt password. Not supported any more. */
 118 #define AUTH_REQ_MD5            5       /* md5 password */
 119 #define AUTH_REQ_SCM_CREDS      6       /* transfer SCM credentials */
 120 #define AUTH_REQ_GSS            7       /* GSSAPI without wrap() */
 121 #define AUTH_REQ_GSS_CONT       8       /* Continue GSS exchanges */
 122 #define AUTH_REQ_SSPI           9       /* SSPI negotiate without wrap() */
 123 #define AUTH_REQ_SASL      10   /* Begin SASL authentication */
 124 #define AUTH_REQ_SASL_CONT 11   /* Continue SASL authentication */
 125 #define AUTH_REQ_SASL_FIN  12   /* Final SASL message */
 126
 127 typedef uint32 AuthRequest;
 128
 129
 130 /*
 131  * A client can also send a cancel-current-operation request to the postmaster.
 132  * This is uglier than sending it directly to the client's backend, but it
 133  * avoids depending on out-of-band communication facilities.
 134  *
 135  * The cancel request code must not match any protocol version number
 136  * we're ever likely to use.  This random choice should do.
 137  */
 138 #define CANCEL_REQUEST_CODE PG_PROTOCOL(1234,5678)
 139
 140 typedef struct CancelRequestPacket
 141 {
 142         /* Note that each field is stored in network byte order! */
 143         MsgType         cancelRequestCode;      /* code to identify a cancel request */
 144         uint32          backendPID;             /* PID of client's backend */
 145         uint32          cancelAuthCode; /* secret key to authorize cancel */
 146 } CancelRequestPacket;
 147
 148
 149 /*
 150  * A client can also start by sending a SSL or GSSAPI negotiation request to
 151  * get a secure channel.
 152  */
 153 #define NEGOTIATE_SSL_CODE PG_PROTOCOL(1234,5679)
 154 #define NEGOTIATE_GSS_CODE PG_PROTOCOL(1234,5680)
 155
 156 #endif                                                  /* PQCOMM_H */