Introduce macros for protocol characters.

This commit introduces descriptively-named macros for the
identifiers used in wire protocol messages.  These new macros are
placed in a new header file so that they can be easily used by
third-party code.

Author: Dave Cramer
Reviewed-by: Alvaro Herrera, Tatsuo Ishii, Peter Smith, Robert Haas, Tom Lane, Peter Eisentraut, Michael Paquier
Discussion: https://postgr.es/m/CADK3HHKbBmK-PKf1bPNFoMC%2BoBt%2BpD9PH8h5nvmBQskEHm-Ehw%40mail.gmail.com

4 files changed, 94 insertions, 18 deletions

diff --git a/src/include/Makefile b/src/include/Makefile
index 5d213187e24..2d5242561cd 100644
--- a/src/include/Makefile
+++ b/src/include/Makefile
@@ -40,6 +40,7 @@ install: all installdirs
 	$(INSTALL_DATA) $(srcdir)/port.h         '$(DESTDIR)$(includedir_internal)'
 	$(INSTALL_DATA) $(srcdir)/postgres_fe.h  '$(DESTDIR)$(includedir_internal)'
 	$(INSTALL_DATA) $(srcdir)/libpq/pqcomm.h '$(DESTDIR)$(includedir_internal)/libpq'
+	$(INSTALL_DATA) $(srcdir)/libpq/protocol.h '$(DESTDIR)$(includedir_internal)/libpq'
 # These headers are needed for server-side development
 	$(INSTALL_DATA) pg_config.h     '$(DESTDIR)$(includedir_server)'
 	$(INSTALL_DATA) pg_config_ext.h '$(DESTDIR)$(includedir_server)'
@@ -65,7 +66,7 @@ installdirs:
 
 uninstall:
 	rm -f $(addprefix '$(DESTDIR)$(includedir)'/, pg_config.h pg_config_ext.h pg_config_os.h pg_config_manual.h postgres_ext.h libpq/libpq-fs.h)
-	rm -f $(addprefix '$(DESTDIR)$(includedir_internal)'/, c.h port.h postgres_fe.h libpq/pqcomm.h)
+	rm -f $(addprefix '$(DESTDIR)$(includedir_internal)'/, c.h port.h postgres_fe.h libpq/pqcomm.h libpq/protocol.h)
 # heuristic...
 	rm -rf $(addprefix '$(DESTDIR)$(includedir_server)'/, $(SUBDIRS) *.h)
 
diff --git a/src/include/libpq/pqcomm.h b/src/include/libpq/pqcomm.h
index 3da00f79839..46a0946b8b2 100644
--- a/src/include/libpq/pqcomm.h
+++ b/src/include/libpq/pqcomm.h
@@ -21,6 +21,12 @@
 #include <netdb.h>
 #include <netinet/in.h>
 
+/*
+ * The definitions for the request/response codes are kept in a separate file
+ * for ease of use in third party programs.
+ */
+#include "libpq/protocol.h"
+
 typedef struct
 {
 	struct sockaddr_storage addr;
@@ -112,23 +118,6 @@ typedef uint32 PacketLen;
 #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. Not supported any more. */
-#define AUTH_REQ_PASSWORD	3	/* Password */
-#define AUTH_REQ_CRYPT		4	/* crypt password. Not supported any more. */
-#define AUTH_REQ_MD5		5	/* md5 password */
-/* 6 is available.  It was used for SCM creds, not supported any more. */
-#define AUTH_REQ_GSS		7	/* GSSAPI without wrap() */
-#define AUTH_REQ_GSS_CONT	8	/* Continue GSS exchanges */
-#define AUTH_REQ_SSPI		9	/* SSPI negotiate without wrap() */
-#define AUTH_REQ_SASL	   10	/* Begin SASL authentication */
-#define AUTH_REQ_SASL_CONT 11	/* Continue SASL authentication */
-#define AUTH_REQ_SASL_FIN  12	/* Final SASL message */
-#define AUTH_REQ_MAX	   AUTH_REQ_SASL_FIN	/* maximum AUTH_REQ_* value */
-
 typedef uint32 AuthRequest;
 
 
diff --git a/src/include/libpq/protocol.h b/src/include/libpq/protocol.h
new file mode 100644
index 00000000000..cc46f4b586a
--- /dev/null
+++ b/src/include/libpq/protocol.h
@@ -0,0 +1,85 @@
+/*-------------------------------------------------------------------------
+ *
+ * protocol.h
+ *		Definitions of the request/response codes for the wire protocol.
+ *
+ *
+ * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/libpq/protocol.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef PROTOCOL_H
+#define PROTOCOL_H
+
+/* These are the request codes sent by the frontend. */
+
+#define PqMsg_Bind					'B'
+#define PqMsg_Close					'C'
+#define PqMsg_Describe				'D'
+#define PqMsg_Execute				'E'
+#define PqMsg_FunctionCall			'F'
+#define PqMsg_Flush					'H'
+#define PqMsg_Parse					'P'
+#define PqMsg_Query					'Q'
+#define PqMsg_Sync					'S'
+#define PqMsg_Terminate				'X'
+#define PqMsg_CopyFail				'f'
+#define PqMsg_GSSResponse			'p'
+#define PqMsg_PasswordMessage		'p'
+#define PqMsg_SASLInitialResponse	'p'
+#define PqMsg_SASLResponse			'p'
+
+
+/* These are the response codes sent by the backend. */
+
+#define PqMsg_ParseComplete			'1'
+#define PqMsg_BindComplete			'2'
+#define PqMsg_CloseComplete			'3'
+#define PqMsg_NotificationResponse	'A'
+#define PqMsg_CommandComplete		'C'
+#define PqMsg_DataRow				'D'
+#define PqMsg_ErrorResponse			'E'
+#define PqMsg_CopyInResponse		'G'
+#define PqMsg_CopyOutResponse		'H'
+#define PqMsg_EmptyQueryResponse	'I'
+#define PqMsg_BackendKeyData		'K'
+#define PqMsg_NoticeResponse		'N'
+#define PqMsg_AuthenticationRequest 'R'
+#define PqMsg_ParameterStatus		'S'
+#define PqMsg_RowDescription		'T'
+#define PqMsg_FunctionCallResponse	'V'
+#define PqMsg_CopyBothResponse		'W'
+#define PqMsg_ReadyForQuery			'Z'
+#define PqMsg_NoData				'n'
+#define PqMsg_PortalSuspended		's'
+#define PqMsg_ParameterDescription	't'
+#define PqMsg_NegotiateProtocolVersion 'v'
+
+
+/* These are the codes sent by both the frontend and backend. */
+
+#define PqMsg_CopyDone				'c'
+#define PqMsg_CopyData				'd'
+
+
+/* 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. Not supported any more. */
+#define AUTH_REQ_PASSWORD	3	/* Password */
+#define AUTH_REQ_CRYPT		4	/* crypt password. Not supported any more. */
+#define AUTH_REQ_MD5		5	/* md5 password */
+/* 6 is available.  It was used for SCM creds, not supported any more. */
+#define AUTH_REQ_GSS		7	/* GSSAPI without wrap() */
+#define AUTH_REQ_GSS_CONT	8	/* Continue GSS exchanges */
+#define AUTH_REQ_SSPI		9	/* SSPI negotiate without wrap() */
+#define AUTH_REQ_SASL	   10	/* Begin SASL authentication */
+#define AUTH_REQ_SASL_CONT 11	/* Continue SASL authentication */
+#define AUTH_REQ_SASL_FIN  12	/* Final SASL message */
+#define AUTH_REQ_MAX	   AUTH_REQ_SASL_FIN	/* maximum AUTH_REQ_* value */
+
+#endif							/* PROTOCOL_H */
diff --git a/src/include/meson.build b/src/include/meson.build
index d7e1ecd4c96..d50897c9fda 100644
--- a/src/include/meson.build
+++ b/src/include/meson.build
@@ -94,6 +94,7 @@ install_headers(
 
 install_headers(
   'libpq/pqcomm.h',
+  'libpq/protocol.h',
   install_dir: dir_include_internal / 'libpq',
 )