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