Make User-Agent configurable (#3255)

Fixes #3253 

Adds a configuration option to overwrite the default `User-Agent` header
that is send at least by the calendar and news module. Allows other
modules to use the individual user agent as well.

The configuration accepts either a string or a function:
```
var config =
	{
		...
		userAgent: 'Mozilla/5.0 (My User Agent)',
		...
	}
```
or
```
var config =
	{
		...
		userAgent: () => 'Mozilla/5.0 (My User Agent)',
		...
	}
```

---------

Co-authored-by: Veeck <github@veeck.de>
Co-authored-by: veeck <gitkraken@veeck.de>
Co-authored-by: Karsten Hassel <hassel@gmx.de>
Co-authored-by: Kristjan ESPERANTO <35647502+KristjanESPERANTO@users.noreply.github.com>

js/app.js

@@ -9,10 +9,9 @@ const Log = require("logger");
 const Server = require(`${__dirname}/server`);
 const Utils = require(`${__dirname}/utils`);
 const defaultModules = require(`${__dirname}/../modules/default/defaultmodules`);
-const { getEnvVarsAsObj } = require(`${__dirname}/server_functions`);
-
 // used to control fetch timeout for node_helpers
 const { setGlobalDispatcher, Agent } = require("undici");
+const { getEnvVarsAsObj } = require("#server_functions");
 // common timeout value, provide environment override in case
 const fetch_timeout = process.env.mmFetchTimeout !== undefined ? process.env.mmFetchTimeout : 30000;
 

js/server.js

@@ -7,7 +7,7 @@ const ipfilter = require("express-ipfilter").IpFilter;
 const helmet = require("helmet");
 const socketio = require("socket.io");
 const Log = require("logger");
-const { cors, getConfig, getHtml, getVersion, getStartup, getEnvVars } = require("./server_functions");
+const { cors, getConfig, getHtml, getVersion, getStartup, getEnvVars } = require("#server_functions");
 
 const vendor = require(`${__dirname}/vendor`);
 

js/server_functions.js

@@ -69,7 +69,7 @@ async function cors (req, res) {
  * @returns {object} An object specifying name and value of the headers.
  */
 function getHeadersToSend (url) {
-	const headersToSend = { "User-Agent": `Mozilla/5.0 MagicMirror/${global.version}` };
+	const headersToSend = { "User-Agent": getUserAgent() };
 	const headersToSendMatch = new RegExp("sendheaders=(.+?)(&|$)", "g").exec(url);
 	if (headersToSendMatch) {
 		const headers = headersToSendMatch[1].split(",");
@@ -129,6 +129,27 @@ function getVersion (req, res) {
 	res.send(global.version);
 }
 
+/**
+ * Gets the preferred `User-Agent`
+ * @returns {string} `User-Agent` to be used
+ */
+function getUserAgent () {
+	const defaultUserAgent = `Mozilla/5.0 (Node.js ${Number(process.version.match(/^v(\d+\.\d+)/)[1])}) MagicMirror/${global.version}`;
+
+	if (typeof config === "undefined") {
+		return defaultUserAgent;
+	}
+
+	switch (typeof config.userAgent) {
+		case "function":
+			return config.userAgent();
+		case "string":
+			return config.userAgent;
+		default:
+			return defaultUserAgent;
+	}
+}
+
 /**
  * Gets environment variables needed in the browser.
  * @returns {object} environment variables key: values
@@ -155,4 +176,4 @@ function getEnvVars (req, res) {
 	res.send(obj);
 }
 
-module.exports = { cors, getConfig, getHtml, getVersion, getStartup, getEnvVars, getEnvVarsAsObj };
+module.exports = { cors, getConfig, getHtml, getVersion, getStartup, getEnvVars, getEnvVarsAsObj, getUserAgent };