SingleFile/extension/lib/single-file/fetch/bg/fetch.js

/*
 * Copyright 2010-2020 Gildas Lormeau
 * contact : gildas.lormeau <at> gmail.com
 * 
 * This file is part of SingleFile.
 *
 *   The code in this file is free software: you can redistribute it and/or 
 *   modify it under the terms of the GNU Affero General Public License 
 *   (GNU AGPL) as published by the Free Software Foundation, either version 3
 *   of the License, or (at your option) any later version.
 * 
 *   The code in this file is distributed in the hope that it will be useful, 
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of 
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero 
 *   General Public License for more details.
 *
 *   As additional permission under GNU AGPL version 3 section 7, you may 
 *   distribute UNMODIFIED VERSIONS OF THIS file without the copy of the GNU 
 *   AGPL normally required by section 4, provided you include this license 
 *   notice and a URL through which recipients can access the Corresponding 
 *   Source.
 */

/* global extension, browser, XMLHttpRequest */

(() => {

	browser.runtime.onMessage.addListener((message, sender) => {
		if (message.method && message.method.startsWith("singlefile.fetch")) {
			return new Promise(resolve => {
				onRequest(message, sender)
					.then(resolve)
					.catch(error => resolve({ error: error && error.toString() }));
			});
		}
	});

	function onRequest(message, sender) {
		if (message.method == "singlefile.fetch") {
			return fetchResource(message.url, { referrer: message.referrer });
		} else if (message.method == "singlefile.fetchFrame") {
			return browser.tabs.sendMessage(sender.tab.id, message);
		}
	}

	function fetchResource(url, options, includeRequestId) {
		return new Promise((resolve, reject) => {
			const xhrRequest = new XMLHttpRequest();
			xhrRequest.withCredentials = true;
			xhrRequest.responseType = "arraybuffer";
			xhrRequest.onerror = event => reject(new Error(event.detail));
			xhrRequest.onreadystatechange = () => {
				if (xhrRequest.readyState == XMLHttpRequest.DONE) {
					if (xhrRequest.status || xhrRequest.response.byteLength) {
						if ((xhrRequest.status == 401 || xhrRequest.status == 403 || xhrRequest.status == 404) && !includeRequestId) {
							fetchResource(url, options, true)
								.then(resolve)
								.catch(reject);
						} else {
							resolve({
								array: Array.from(new Uint8Array(xhrRequest.response)),
								headers: { "content-type": xhrRequest.getResponseHeader("Content-Type") },
								status: xhrRequest.status
							});
						}
					} else {
						reject();
					}
				}
			};
			xhrRequest.open("GET", url, true);
			if (includeRequestId) {
				const randomId = String(Math.random()).substring(2);
				extension.core.bg.requests.setReferrer(randomId, options.referrer);
				xhrRequest.setRequestHeader(extension.core.bg.requests.REQUEST_ID_HEADER_NAME, randomId);
			}
			xhrRequest.send();
		});
	}

})();