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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) 1996-2026, 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 : : /*
25 : : * The definitions for the request/response codes are kept in a separate file
26 : : * for ease of use in third party programs.
27 : : */
28 : : #include "libpq/protocol.h"
29 : :
30 : : typedef struct
31 : : {
32 : : struct sockaddr_storage addr;
33 : : socklen_t salen;
34 : : } SockAddr;
35 : :
36 : : typedef struct
37 : : {
38 : : int family;
39 : : SockAddr addr;
40 : : } AddrInfo;
41 : :
42 : : /* Configure the UNIX socket location for the well known port. */
43 : : #define UNIXSOCK_PATH(path, port, sockdir) \
44 : : (AssertMacro(sockdir), \
45 : : AssertMacro(*(sockdir) != '\0'), \
46 : : snprintf(path, sizeof(path), "%s/.s.PGSQL.%d", \
47 : : (sockdir), (port)))
48 : :
49 : : /*
50 : : * The maximum workable length of a socket path is what will fit into
51 : : * struct sockaddr_un. This is usually only 100 or so bytes :-(.
52 : : *
53 : : * For consistency, always pass a MAXPGPATH-sized buffer to UNIXSOCK_PATH(),
54 : : * then complain if the resulting string is >= UNIXSOCK_PATH_BUFLEN bytes.
55 : : * (Because the standard API for getaddrinfo doesn't allow it to complain in
56 : : * a useful way when the socket pathname is too long, we have to test for
57 : : * this explicitly, instead of just letting the subroutine return an error.)
58 : : */
59 : : #define UNIXSOCK_PATH_BUFLEN sizeof(((struct sockaddr_un *) NULL)->sun_path)
60 : :
61 : : /*
62 : : * A host that looks either like an absolute path or starts with @ is
63 : : * interpreted as a Unix-domain socket address.
64 : : */
65 : : static inline bool
66 : 636 : is_unixsock_path(const char *path)
67 : : {
68 [ + - ]: 636 : return is_absolute_path(path) || path[0] == '@';
69 : : }
70 : :
71 : :
72 : : /*
73 : : * These manipulate the frontend/backend protocol version number.
74 : : *
75 : : * The major number should be incremented for incompatible changes. The minor
76 : : * number should be incremented for compatible changes (eg. additional
77 : : * functionality).
78 : : *
79 : : * If a backend supports version m.n of the protocol it must actually support
80 : : * versions m.[0..n]. Backend support for version m-1 can be dropped after a
81 : : * `reasonable' length of time.
82 : : *
83 : : * A frontend isn't required to support anything other than the current
84 : : * version.
85 : : */
86 : : #define PG_PROTOCOL_MAJOR(v) ((v) >> 16)
87 : : #define PG_PROTOCOL_MINOR(v) ((v) & 0x0000ffff)
88 : : #define PG_PROTOCOL_FULL(v) (PG_PROTOCOL_MAJOR(v) * 10000 + PG_PROTOCOL_MINOR(v))
89 : : #define PG_PROTOCOL(m,n) (((m) << 16) | (n))
90 : :
91 : : /*
92 : : * The earliest and latest frontend/backend protocol version supported.
93 : : */
94 : : #define PG_PROTOCOL_EARLIEST PG_PROTOCOL(3,0)
95 : : #define PG_PROTOCOL_LATEST PG_PROTOCOL(3,2)
96 : :
97 : : /*
98 : : * Reserved protocol numbers, which have special semantics:
99 : : */
100 : :
101 : : /*
102 : : * 3.1 would have collided with old pgbouncer deployments, and was skipped. We
103 : : * neither emit it nor accept it on the wire.
104 : : */
105 : : #define PG_PROTOCOL_RESERVED_31 PG_PROTOCOL(3,1)
106 : :
107 : : /*
108 : : * A client can send a cancel-current-operation request to the postmaster.
109 : : * This is uglier than sending it directly to the client's backend, but it
110 : : * avoids depending on out-of-band communication facilities.
111 : : */
112 : : #define CANCEL_REQUEST_CODE PG_PROTOCOL(1234,5678)
113 : :
114 : : /*
115 : : * A client can also start by sending a SSL or GSSAPI negotiation request to
116 : : * get a secure channel.
117 : : */
118 : : #define NEGOTIATE_SSL_CODE PG_PROTOCOL(1234,5679)
119 : : #define NEGOTIATE_GSS_CODE PG_PROTOCOL(1234,5680)
120 : :
121 : :
122 : : typedef uint32 ProtocolVersion; /* FE/BE protocol version number */
123 : :
124 : :
125 : : /*
126 : : * Packet lengths are 4 bytes in network byte order.
127 : : *
128 : : * The initial length is omitted from the packet layouts appearing below.
129 : : */
130 : : typedef uint32 PacketLen;
131 : :
132 : : /*
133 : : * In protocol 3.0 and later, the startup packet length is not fixed, but
134 : : * we set an arbitrary limit on it anyway. This is just to prevent simple
135 : : * denial-of-service attacks via sending enough data to run the server
136 : : * out of memory.
137 : : */
138 : : #define MAX_STARTUP_PACKET_LENGTH 10000
139 : :
140 : :
141 : : typedef uint32 AuthRequest; /* an AUTH_REQ_* code */
142 : :
143 : :
144 : : /*
145 : : * The packet used with a CANCEL_REQUEST_CODE.
146 : : *
147 : : * Before PostgreSQL v18 and the protocol version bump from 3.0 to 3.2, the
148 : : * cancel key was always 4 bytes. With protocol version 3.2, it's variable
149 : : * length.
150 : : */
151 : : typedef struct CancelRequestPacket
152 : : {
153 : : /* Note that each field is stored in network byte order! */
154 : : ProtocolVersion cancelRequestCode; /* code to identify a cancel request */
155 : : uint32 backendPID; /* PID of client's backend */
156 : : uint8 cancelAuthCode[FLEXIBLE_ARRAY_MEMBER]; /* secret key to
157 : : * authorize cancel */
158 : : } CancelRequestPacket;
159 : :
160 : :
161 : : /*
162 : : * Application-Layer Protocol Negotiation is required for direct connections
163 : : * to avoid protocol confusion attacks (e.g https://alpaca-attack.com/).
164 : : *
165 : : * ALPN is specified in RFC 7301
166 : : *
167 : : * This string should be registered at:
168 : : * https://www.iana.org/assignments/tls-extensiontype-values/tls-extensiontype-values.xhtml#alpn-protocol-ids
169 : : *
170 : : * OpenSSL uses this wire-format for the list of alpn protocols even in the
171 : : * API. Both server and client take the same format parameter but the client
172 : : * actually sends it to the server as-is and the server it specifies the
173 : : * preference order to use to choose the one selected to send back.
174 : : *
175 : : * c.f. https://www.openssl.org/docs/manmaster/man3/SSL_CTX_set_alpn_select_cb.html
176 : : *
177 : : * The #define can be used to initialize a char[] vector to use directly in the API
178 : : */
179 : : #define PG_ALPN_PROTOCOL "postgresql"
180 : : #define PG_ALPN_PROTOCOL_VECTOR { 10, 'p','o','s','t','g','r','e','s','q','l' }
181 : :
182 : : #endif /* PQCOMM_H */
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