Log warning on mismatched slave or plugin versions

Log warning to the master log if a slave connects with a missmatched
version, missmatched plugins or missmatched plugin versions.

packages/master/src/Master.js

@@ -45,8 +45,8 @@ class Master {
 	constructor(clusterLogger, pluginInfos, configPath, config) {
 		this.clusterLogger = clusterLogger;
 		/**
-		 * Mapping of plugin name to info objects for known plugins
-		 * @type {Map<string, Object>}
+		 * Array of plugin info objects for known plugins
+		 * @type {Array<object>}
 		 */
 		this.pluginInfos = pluginInfos;
 		this.configPath = configPath;

packages/master/src/SlaveConnection.js

@@ -23,6 +23,7 @@ class SlaveConnection extends BaseConnection {
 		this._name = registerData.name;
 		this._version = registerData.version;
 		this.plugins = new Map(Object.entries(registerData.plugins));
+		this._checkPluginVersions();
 
 		this._master.slaves.set(this._id, {
 			agent: this._agent,
@@ -57,6 +58,30 @@ class SlaveConnection extends BaseConnection {
 		});
 	}
 
+	_checkPluginVersions() {
+		let pluginInfos = new Map(this._master.pluginInfos.map(i => [i.name, i]));
+		for (let [name, version] of this.plugins) {
+			let info = pluginInfos.get(name);
+			if (!info) {
+				logger.warn(`Slave ${this._name} has plugin ${name} ${version} which the master does not have`);
+				continue;
+			}
+
+			if (info.version !== version) {
+				logger.warn(
+					`Slave ${this._name} has plugin ${name} ${version} which does not match the version of this ` +
+					`plugin on the master (${info.version})`
+				);
+			}
+		}
+
+		for (let [name, info] of pluginInfos) {
+			if (!this.plugins.has(name)) {
+				logger.warn(`Slave ${this._name} is missing plugin ${name} ${info.version}`);
+			}
+		}
+	}
+
 	/**
 	 * ID of the slave this connection is connected to
 	 *

packages/master/src/WsServer.js

@@ -269,7 +269,16 @@ ${err.stack}`
 				await connection.disconnect(1008, "Registered from another connection");
 			}
 
-			logger.verbose(`WsServer | registered slave ${data.id} version ${data.version}`);
+			logger.info(
+				`WsServer | registered slave ${data.name} (${data.id}) using agent ${data.agent} ${data.version}`
+			);
+			if (data.agent === "Clusterio Slave" && data.version !== packageVersion) {
+				logger.warn(
+					`Slave ${data.name} (${data.id}) connected using version ${data.version} which does not match ` +
+					`the version of the master is currently running (${packageVersion}). It may not work as expected.`
+				);
+			}
+
 			connection = new SlaveConnection(data, connector, this.master);
 			connector.on("close", () => {
 				if (this.slaveConnections.get(data.id) === connection) {