syslog: restructure code

syslog/server.js

@@ -8,29 +8,34 @@ exports = module.exports = {
 const LOG_FILENAME = 'app.log';
 
 const assert = require('assert'),
+    debug = require('debug')('syslog:server'),
     dgram = require('dgram'),
     fs = require('fs'),
     path = require('path'),
-    parser = require('nsyslog-parser');
+    parser = require('nsyslog-parser'),
+    util = require('util');
 
 let server = null;
 
-function start(options, callback) {
+async function start(options) {
     assert.strictEqual(typeof options, 'object');
     assert.strictEqual(typeof options.port, 'number');
     assert.strictEqual(typeof options.logFolder, 'string');
-    assert.strictEqual(typeof callback, 'function');
+
+    debug('==========================================');
+    debug('          Cloudron Syslog Daemon          ');
+    debug('==========================================');
 
     server = dgram.createSocket('udp4');
 
     server.on('error', function (error) {
-        callback(error);
-    }).on('listening', function () {
-        callback();
-    }).on('message', function (msg /*, rinfo */) {
+        console.error(`socket error: ${error}`);
+    });
+
+    server.on('message', function (msg /*, rinfo */) {
         const info = parser(msg.toString());
 
-        if (!info || !info.appName) return console.log('Ignore unknown app log:', msg.toString());
+        if (!info || !info.appName) return debug('Ignore unknown app log:', msg.toString());
 
         // remove line breaks to avoid holes in the log file
         // we do not ignore empty log lines, to allow gaps for potential ease of readability
@@ -45,17 +50,15 @@ function start(options, callback) {
         } catch (error) {
             console.error(error);
         }
-    }).bind(options.port);
+    });
+
+    await util.promisify(server.bind.bind(server))(options.port); // intentional double "bind"
+
+    debug(`Listening on port ${options.port}`);
 }
 
-function stop(callback) {
-    assert.strictEqual(typeof callback, 'function');
-
-    if (!server) return callback();
-
-    server.close();
-
+async function stop() {
+    if (!server) return;
+    await util.promisify(server.close.bind(server))();
     server = null;
-
-    callback();
-}
+}