111 lines
4.1 KiB
JavaScript
111 lines
4.1 KiB
JavaScript
/*
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* Vencord, a modification for Discord's desktop app
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* Copyright (c) 2022 Vendicated and contributors
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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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* 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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function fetchOptions(url) {
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return new Promise((resolve, reject) => {
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const opt = {
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method: "OPTIONS",
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url: url,
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};
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opt.onload = resp => resolve(resp.responseHeaders);
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opt.ontimeout = () => reject("fetch timeout");
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opt.onerror = () => reject("fetch error");
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opt.onabort = () => reject("fetch abort");
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GM_xmlhttpRequest(opt);
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});
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}
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function parseHeaders(headers) {
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if (!headers)
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return {};
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const result = {};
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const headersArr = headers.trim().split("\n");
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for (var i = 0; i < headersArr.length; i++) {
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var row = headersArr[i];
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var index = row.indexOf(":")
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, key = row.slice(0, index).trim().toLowerCase()
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, value = row.slice(index + 1).trim();
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if (result[key] === undefined) {
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result[key] = value;
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} else if (Array.isArray(result[key])) {
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result[key].push(value);
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} else {
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result[key] = [result[key], value];
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}
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}
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return result;
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}
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// returns true if CORS permits request
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async function checkCors(url, method) {
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const headers = parseHeaders(await fetchOptions(url));
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const origin = headers["access-control-allow-origin"];
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if (origin !== "*" && origin !== window.location.origin) return false;
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const methods = headers["access-control-allow-methods"]?.toLowerCase()
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.split(",")
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.map(s => s.trim());
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if (methods && !methods.includes(method.toLowerCase())) return false;
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return true;
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}
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function blobTo(to, blob) {
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if (to === "arrayBuffer" && blob.arrayBuffer) return blob.arrayBuffer();
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return new Promise((resolve, reject) => {
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var fileReader = new FileReader();
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fileReader.onload = event => resolve(event.target.result);
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if (to === "arrayBuffer") fileReader.readAsArrayBuffer(blob);
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else if (to === "text") fileReader.readAsText(blob, "utf-8");
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else reject("unknown to");
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});
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}
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function GM_fetch(url, opt) {
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return new Promise((resolve, reject) => {
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checkCors(url, opt?.method || "GET")
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.then(can => {
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if (can) {
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// https://www.tampermonkey.net/documentation.php?ext=dhdg#GM_xmlhttpRequest
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const options = opt || {};
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options.url = url;
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options.data = options.body;
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options.responseType = "blob";
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options.onload = resp => {
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var blob = resp.response;
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resp.blob = () => Promise.resolve(blob);
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resp.arrayBuffer = () => blobTo("arrayBuffer", blob);
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resp.text = () => blobTo("text", blob);
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resp.json = async () => JSON.parse(await blobTo("text", blob));
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resp.headers = new Headers(parseHeaders(resp.responseHeaders));
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resolve(resp);
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};
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options.ontimeout = () => reject("fetch timeout");
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options.onerror = () => reject("fetch error");
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options.onabort = () => reject("fetch abort");
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GM_xmlhttpRequest(options);
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} else {
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reject("CORS issue");
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}
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});
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});
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}
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export const fetch = GM_fetch;
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