Cleaned up file layout

nodejs/utils/unix_socket_json.js

@@ -0,0 +1,114 @@
+'use strict';
+
+const net = require('net');
+const fs = require('fs');
+const {CallbackQueue} = require('../utils/callback_queue');
+
+/**
+ * SocketServerJson
+ *
+ * A generic Unix socket server that handles JSON message communication.
+ * Automatically manages socket file lifecycle (cleanup, permissions).
+ * Uses callback queues for event handling to support multiple listeners.
+ *
+ * Features:
+ * - Automatic socket file cleanup on startup
+ * - Configurable file permissions (default 777 for container use)
+ * - JSON message parsing with buffering for partial data
+ * - Event callbacks for data, errors, and connection lifecycle
+ */
+class SocketServerJson {
+	constructor(args){
+		this.socketFile = args.socketFile;
+		this.onData = new CallbackQueue(args.onData, this);
+		this.onListen = new CallbackQueue(args.onListen, this);
+		this.onError = new CallbackQueue(args.onError);
+		this.onClientNew = new CallbackQueue(args.onClientNew);
+		this.onClientClose = new CallbackQueue(args.onClientClose);
+		this.onClientError = new CallbackQueue(args.onClientError);
+
+		// Set socket file permissions after listening
+		// 777 is acceptable here for single-use container environments
+		this.onListen.push(function(){
+			fs.chmodSync(args.socketFile, '777');
+		});
+
+		this.listen();
+	}
+
+	/**
+	 * Removes existing socket file if present before creating new server.
+	 * Prevents "address already in use" errors from stale socket files.
+	 */
+	__resetSocketFile(callback){
+		let instance = this;
+
+		fs.stat(this.socketFile, function (err, stats) {
+			if (stats) {
+				fs.unlink(instance.socketFile, function(err){
+					if(err){
+						// This should never happen
+						console.error(err);
+					}
+					callback(...arguments);
+				});
+			}else{
+				callback();
+			}
+		});
+	}
+
+	/**
+	 * Sets up the Unix socket server and registers event handlers.
+	 *
+	 * Data handling:
+	 * - Buffers incoming data to handle partial JSON messages
+	 * - Attempts to parse buffer as JSON after each data event
+	 * - Clears buffer only after successful parse
+	 * - Silent failure on parse errors (waits for more data)
+	 */
+	__setUpServer(){
+		let instance = this;
+		this.socket = net.createServer();
+
+		this.socket.on('connection', function(clientSocket){
+			let buffer = '';
+
+			clientSocket.on('data', function(data){
+				buffer += data.toString();
+				try{
+					// Parse buffer (not just current data chunk) to handle partial messages
+					instance.onData.call(JSON.parse(buffer), clientSocket);
+					buffer = '';
+				}catch(error){
+					// Parse failed - likely incomplete JSON, wait for more data
+					// Buffer persists until complete JSON is received
+				}
+			});
+
+			clientSocket.on('close', instance.onClientClose.call.bind(instance.onClientClose));
+
+			clientSocket.on('error', instance.onClientError.call.bind(instance.onClientError));
+		});
+
+		this.socket.on('error', this.onError.call.bind(this.onError));
+
+		this.socket.on('listening', this.onListen.call.bind(this.onListen));
+	}
+
+	/**
+	 * Starts the Unix socket server.
+	 * Cleans up any existing socket file before listening.
+	 */
+	listen(){
+		let instance = this;
+
+		this.__setUpServer();
+
+		this.__resetSocketFile(function(){
+			instance.socket.listen(instance.socketFile);
+		});
+	}
+}
+
+module.exports = {SocketServerJson};