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/**
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* This file is part of Haketilo.
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*
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* Function: Allow other parts of the extension to bypass CORS by routing their
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* requests through this background script using one-off messages.
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*
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* Copyright (C) 2022 Wojtek Kosior <koszko@koszko.org>
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* As additional permission under GNU GPL version 3 section 7, you
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* may distribute forms of that code without the copy of the GNU
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* GPL normally required by section 4, provided you include this
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* license notice and, in case of non-source distribution, a URL
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* through which recipients can access the Corresponding Source.
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* If you modify file(s) with this exception, you may extend this
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* exception to your version of the file(s), but you are not
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* obligated to do so. If you do not wish to do so, delete this
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* exception statement from your version.
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*
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* As a special exception to the GPL, any HTML file which merely
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* makes function calls to this code, and for that purpose
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* includes it by reference shall be deemed a separate work for
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* copyright law purposes. If you modify this code, you may extend
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* this exception to your version of the code, but you are not
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* obligated to do so. If you do not wish to do so, delete this
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* exception statement from your version.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <https://www.gnu.org/licenses/>.
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*
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* I, Wojtek Kosior, thereby promise not to sue for violation of this file's
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* license. Although I request that you do not make use of this code in a
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* proprietary program, I am not going to enforce this in court.
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*/
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#FROM common/browser.js IMPORT browser
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#FROM common/misc.js IMPORT uint8_to_hex, error_data_jsonifiable
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/*
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* In this file we implement a fetch()-from-background-script service. Code in
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* other parts of the extension shall call sendMessage() with arguments to
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* fetch() and code here will call fetch() with those arguments and send back
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* the response.
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*
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* We have to convert the Response from fetch() into a JSON-ifiable value and
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* then convert it back (using Response() constructor) due (among others) the
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* limitations of Chromium's messaging API:
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* https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/Chrome_incompatibilities#data_cloning_algorithm
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*
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* We also catch possible errors from fetch() (e.g. in case of an invalid URL)
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* and send their data in JSON-ifiable form so that the error object can be
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* later re-created.
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*/
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/* Make it possible to serialize Response object. */
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async function response_data_jsonifiable(response) {
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return {
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status: response.status,
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statusText: response.statusText,
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headers: [...response.headers.entries()],
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body: uint8_to_hex(new Uint8Array(await response.arrayBuffer()))
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};
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}
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async function perform_download(fetch_data) {
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try {
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const response = await fetch(fetch_data.url, fetch_data.init);
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return response_data_jsonifiable(response);
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} catch(e) {
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return {error: error_data_jsonifiable(e)};
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}
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}
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function on_CORS_bypass_request([type, fetch_data], sender, respond_cb) {
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if (type !== "CORS_bypass")
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return;
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perform_download(fetch_data).then(respond_cb);
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return true;
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}
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function start() {
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browser.runtime.onMessage.addListener(on_CORS_bypass_request);
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}
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#EXPORT start
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