revert: restore CORS proxy for newsfeed and 3rd-party module compatibility

Author: KristjanESPERANTO

js/server.js

@@ -6,7 +6,7 @@ const express = require("express");
 const helmet = require("helmet");
 const socketio = require("socket.io");
 const Log = require("logger");
-const { getHtml, getVersion, getEnvVars } = require("#server_functions");
+const { getHtml, getVersion, getEnvVars, cors } = require("#server_functions");
 
 const { ipAccessControl } = require(`${__dirname}/ip_access_control`);
 
@@ -118,6 +118,8 @@ function Server (configObj) {
 			};
 			app.get("/config", (req, res) => getConfig(req, res));
 
+			app.get("/cors", async (req, res) => await cors(req, res));
+
 			app.get("/version", (req, res) => getVersion(req, res));
 
 			app.get("/startup", (req, res) => getStartup(req, res));

js/server_functions.js

@@ -2,6 +2,90 @@ const fs = require("node:fs");
 const path = require("node:path");
 const Log = require("logger");
 
+/**
+ * A method that forwards HTTP Get-methods to the internet to avoid CORS-errors.
+ * Example input request url: /cors?sendheaders=header1:value1,header2:value2&expectedheaders=header1,header2&url=http://www.test.com/path?param1=value1
+ * @param {Request} req - the request
+ * @param {Response} res - the response
+ * @returns {Promise<void>} Promise that resolves when response is sent
+ */
+async function cors (req, res) {
+	try {
+		const urlRegEx = "url=(.+?)$";
+		let url;
+
+		const match = new RegExp(urlRegEx, "g").exec(req.url);
+		if (!match) {
+			url = `invalid url: ${req.url}`;
+			Log.error(url);
+			return res.status(400).send(url);
+		} else {
+			url = match[1];
+
+			const headersToSend = getHeadersToSend(req.url);
+			const expectedReceivedHeaders = geExpectedReceivedHeaders(req.url);
+
+			Log.log(`cors url: ${url}`);
+
+			const response = await fetch(url, { headers: headersToSend });
+			if (response.ok) {
+				for (const header of expectedReceivedHeaders) {
+					const headerValue = response.headers.get(header);
+					if (header) res.set(header, headerValue);
+				}
+				const data = await response.text();
+				res.send(data);
+			} else {
+				throw new Error(`Response status: ${response.status}`);
+			}
+		}
+	} catch (error) {
+		// Only log errors in non-test environments to keep test output clean
+		if (process.env.mmTestMode !== "true") {
+			Log.error(`Error in CORS request: ${error}`);
+		}
+		res.status(500).json({ error: error.message });
+	}
+}
+
+/**
+ * Gets headers and values to attach to the web request.
+ * @param {string} url - The url containing the headers and values to send.
+ * @returns {object} An object specifying name and value of the headers.
+ */
+function getHeadersToSend (url) {
+	const headersToSend = { "User-Agent": getUserAgent() };
+	const headersToSendMatch = new RegExp("sendheaders=(.+?)(&|$)", "g").exec(url);
+	if (headersToSendMatch) {
+		const headers = headersToSendMatch[1].split(",");
+		for (const header of headers) {
+			const keyValue = header.split(":");
+			if (keyValue.length !== 2) {
+				throw new Error(`Invalid format for header ${header}`);
+			}
+			headersToSend[keyValue[0]] = decodeURIComponent(keyValue[1]);
+		}
+	}
+	return headersToSend;
+}
+
+/**
+ * Gets the headers expected from the response.
+ * @param {string} url - The url containing the expected headers from the response.
+ * @returns {string[]} headers - The name of the expected headers.
+ */
+function geExpectedReceivedHeaders (url) {
+	const expectedReceivedHeaders = ["Content-Type"];
+	const expectedReceivedHeadersMatch = new RegExp("expectedheaders=(.+?)(&|$)", "g").exec(url);
+	if (expectedReceivedHeadersMatch) {
+		const headers = expectedReceivedHeadersMatch[1].split(",");
+		for (const header of headers) {
+			expectedReceivedHeaders.push(header);
+		}
+	}
+	return expectedReceivedHeaders;
+}
+
 /**
  * Gets the HTML to display the magic mirror.
  * @param {Request} req - the request
@@ -89,4 +173,4 @@ function getConfigFilePath () {
 	return path.resolve(global.configuration_file || `${global.root_path}/config/config.js`);
 }
 
-module.exports = { getHtml, getVersion, getEnvVars, getEnvVarsAsObj, getUserAgent, getConfigFilePath };
+module.exports = { cors, getHtml, getVersion, getEnvVars, getEnvVarsAsObj, getUserAgent, getConfigFilePath };