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/*
* Vencord, a modification for Discord's desktop app
* Copyright (c) 2022 Vendicated and contributors
*
* 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.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
function fetchOptions(url) {
return new Promise((resolve, reject) => {
const opt = {
method: "OPTIONS",
url: url,
};
opt.onload = resp => resolve(resp.responseHeaders);
opt.ontimeout = () => reject("fetch timeout");
opt.onerror = () => reject("fetch error");
opt.onabort = () => reject("fetch abort");
GM_xmlhttpRequest(opt);
});
}
function parseHeaders(headers) {
if (!headers)
return {};
const result = {};
const headersArr = headers.trim().split("\n");
for (var i = 0; i < headersArr.length; i++) {
var row = headersArr[i];
var index = row.indexOf(":")
, key = row.slice(0, index).trim().toLowerCase()
, value = row.slice(index + 1).trim();
if (result[key] === undefined) {
result[key] = value;
} else if (Array.isArray(result[key])) {
result[key].push(value);
} else {
result[key] = [result[key], value];
}
}
return result;
}
// returns true if CORS permits request
async function checkCors(url, method) {
const headers = parseHeaders(await fetchOptions(url));
const origin = headers["access-control-allow-origin"];
if (origin !== "*" && origin !== window.location.origin) return false;
const methods = headers["access-control-allow-methods"]?.toLowerCase()
.split(",")
.map(s => s.trim());
if (methods && !methods.includes(method.toLowerCase())) return false;
return true;
}
function blobTo(to, blob) {
if (to === "arrayBuffer" && blob.arrayBuffer) return blob.arrayBuffer();
return new Promise((resolve, reject) => {
var fileReader = new FileReader();
fileReader.onload = event => resolve(event.target.result);
if (to === "arrayBuffer") fileReader.readAsArrayBuffer(blob);
else if (to === "text") fileReader.readAsText(blob, "utf-8");
else reject("unknown to");
});
}
function GM_fetch(url, opt) {
return new Promise((resolve, reject) => {
checkCors(url, opt?.method || "GET")
.then(can => {
if (can) {
// https://www.tampermonkey.net/documentation.php?ext=dhdg#GM_xmlhttpRequest
const options = opt || {};
options.url = url;
options.data = options.body;
options.responseType = "blob";
options.onload = resp => {
var blob = resp.response;
resp.blob = () => Promise.resolve(blob);
resp.arrayBuffer = () => blobTo("arrayBuffer", blob);
resp.text = () => blobTo("text", blob);
resp.json = async () => JSON.parse(await blobTo("text", blob));
resp.headers = new Headers(parseHeaders(resp.responseHeaders));
resolve(resp);
};
options.ontimeout = () => reject("fetch timeout");
options.onerror = () => reject("fetch error");
options.onabort = () => reject("fetch abort");
GM_xmlhttpRequest(options);
} else {
reject("CORS issue");
}
});
});
}
export const fetch = GM_fetch;
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