From f813acbff144fa649d152838957c321894c1cbba Mon Sep 17 00:00:00 2001
From: Sebastian Harl <sh@tokkee.org>
Date: Sun, 22 Feb 2015 16:46:30 +0100
Subject: [PATCH] frontend: Added the SERVER_VERSION command.

This command sends back the server version.
---
 src/frontend/connection.c         | 20 ++++++++++++++++++++
 src/include/frontend/connection.h | 11 +++++++++++
 src/include/frontend/proto.h      | 19 +++++++++++++++++++
 3 files changed, 50 insertions(+)

diff --git a/src/frontend/connection.c b/src/frontend/connection.c
index 64f2cb2..117c6ae 100644
--- a/src/frontend/connection.c
+++ b/src/frontend/connection.c
@@ -284,6 +284,7 @@ command_handle(sdb_conn_t *conn)
 		status = sdb_connection_ping(conn);
 	else if (conn->cmd == SDB_CONNECTION_STARTUP)
 		status = sdb_fe_session_start(conn);
+
 	else if (conn->cmd == SDB_CONNECTION_QUERY)
 		status = sdb_fe_query(conn);
 	else if (conn->cmd == SDB_CONNECTION_FETCH)
@@ -294,6 +295,10 @@ command_handle(sdb_conn_t *conn)
 		status = sdb_fe_lookup(conn);
 	else if (conn->cmd == SDB_CONNECTION_STORE)
 		status = sdb_fe_store(conn);
+
+	else if (conn->cmd == SDB_CONNECTION_SERVER_VERSION)
+		status = sdb_connection_server_version(conn);
+
 	else {
 		sdb_log(SDB_LOG_WARNING, "frontend: Ignoring invalid command %#x",
 				conn->cmd);
@@ -532,5 +537,20 @@ sdb_connection_ping(sdb_conn_t *conn)
 	return 0;
 } /* sdb_connection_ping */
 
+int
+sdb_connection_server_version(sdb_conn_t *conn)
+{
+	char msg[sizeof(uint32_t) + strlen(SDB_VERSION_EXTRA) + 1];
+
+	if ((! conn) || (conn->cmd != SDB_CONNECTION_SERVER_VERSION))
+		return -1;
+
+	sdb_proto_marshal_int32(msg, sizeof(msg), (uint32_t)SDB_VERSION);
+	strncpy(msg + sizeof(uint32_t), SDB_VERSION_EXTRA,
+			sizeof(msg) - sizeof(uint32_t));
+	sdb_connection_send(conn, SDB_CONNECTION_OK, (uint32_t)sizeof(msg), msg);
+	return 0;
+} /* sdb_connection_server_version */
+
 /* vim: set tw=78 sw=4 ts=4 noexpandtab : */
 
diff --git a/src/include/frontend/connection.h b/src/include/frontend/connection.h
index c4f2bc7..0397e50 100644
--- a/src/include/frontend/connection.h
+++ b/src/include/frontend/connection.h
@@ -135,6 +135,17 @@ sdb_connection_send(sdb_conn_t *conn, uint32_t code,
 int
 sdb_connection_ping(sdb_conn_t *conn);
 
+/*
+ * sdb_connection_server_version:
+ * Send back the backend server version to the connected client.
+ *
+ * Returns:
+ *  - 0 on success
+ *  - a negative value else
+ */
+int
+sdb_connection_server_version(sdb_conn_t *conn);
+
 /*
  * sdb_fe_parse:
  * Parse the query text specified in 'query' of length 'len' and return a list
diff --git a/src/include/frontend/proto.h b/src/include/frontend/proto.h
index 833762d..ade3a7c 100644
--- a/src/include/frontend/proto.h
+++ b/src/include/frontend/proto.h
@@ -298,6 +298,25 @@ typedef enum {
 	 * A parsed expression. Only used internally.
 	 */
 	SDB_CONNECTION_EXPR,
+
+	/*
+	 * Server status queries.
+	 */
+
+	/*
+	 * SDB_CONNECTION_SERVER_VERSION:
+	 * Retrieve the server version. The server replies with SDB_CONNECTION_OK
+	 * on success and the server version as an unsigned 32-bit integer,
+	 * optionally followed by a string describing extra version components.
+	 * The integer server version is encoded as 100000 * major + 100 * minor +
+	 * patch.
+	 *
+	 * 0               32              64
+	 * +---------------+---------------+
+	 * | SERVER_VERSION| 0             |
+	 * +---------------+---------------+
+	 */
+	SDB_CONNECTION_SERVER_VERSION = 1000,
 } sdb_conn_state_t;
 
 #define SDB_CONN_MSGTYPE_TO_STRING(t) \
-- 
2.30.2