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/*
Spacebar: A FOSS re-implementation and extension of the Discord.com backend.
Copyright (C) 2023 Spacebar and Spacebar Contributors
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero 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 Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
import { Config, JimpType } from "@spacebar/util";
import { Request, Response } from "express";
import { yellow } from "picocolors";
import crypto from "crypto";
import fetch from "node-fetch-commonjs";
let sharp: undefined | false | { default: typeof import("sharp") } = undefined;
let Jimp: JimpType | undefined = undefined;
try {
Jimp = require("jimp") as JimpType;
} catch {
// empty
}
let sentImageProxyWarning = false;
const sharpSupported = new Set([
"image/jpeg",
"image/png",
"image/bmp",
"image/tiff",
"image/gif",
"image/webp",
"image/avif",
"image/svg+xml",
]);
const jimpSupported = new Set([
"image/jpeg",
"image/png",
"image/bmp",
"image/tiff",
"image/gif",
]);
const resizeSupported = new Set([...sharpSupported, ...jimpSupported]);
export async function ImageProxy(req: Request, res: Response) {
const path = req.originalUrl.split("/").slice(2);
// src/api/util/utility/EmbedHandlers.ts getProxyUrl
const hash = crypto
.createHmac("sha1", Config.get().security.requestSignature)
.update(path.slice(1).join("/"))
.digest("base64")
.replace(/\+/g, "-")
.replace(/\//g, "_");
try {
if (!crypto.timingSafeEqual(Buffer.from(hash), Buffer.from(path[0])))
throw new Error("Invalid signature");
} catch {
console.log(
"[ImageProxy] Invalid signature, expected " +
hash +
" but got " +
path[0],
);
res.status(403).send("Invalid signature");
return;
}
const abort = new AbortController();
setTimeout(() => abort.abort(), 5000);
const request = await fetch("https://" + path.slice(2).join("/"), {
headers: {
"User-Agent": "SpacebarImageProxy/1.0.0 (https://spacebar.chat)",
},
signal: abort.signal,
}).catch((e) => {
if (e.name === "AbortError") res.status(504).send("Request timed out");
else res.status(500).send("Unable to proxy origin: " + e.message);
});
if (!request) return;
if (request.status !== 200) {
res.status(request.status).send(
"Origin failed to respond: " +
request.status +
" " +
request.statusText,
);
return;
}
if (
!request.headers.get("Content-Type") ||
!request.headers.get("Content-Length")
) {
res.status(500).send(
"Origin did not provide a Content-Type or Content-Length header",
);
return;
}
// @ts-expect-error TS doesn't believe that the header cannot be null (it's checked for falsiness above)
if (parseInt(request.headers.get("Content-Length")) > 1024 * 1024 * 10) {
res.status(500).send(
"Origin provided a Content-Length header that is too large",
);
return;
}
// @ts-expect-error TS doesn't believe that the header cannot be null (it's checked for falsiness above)
let contentType: string = request.headers.get("Content-Type");
const arrayBuffer = await request.arrayBuffer();
let resultBuffer = Buffer.from(arrayBuffer);
if (
!sentImageProxyWarning &&
resizeSupported.has(contentType) &&
/^\d+x\d+$/.test(path[1])
) {
if (sharp !== false) {
try {
sharp = await import("sharp");
} catch {
sharp = false;
}
}
if (sharp === false && !Jimp) {
try {
// eslint-disable-next-line @typescript-eslint/ban-ts-comment
// @ts-ignore Typings don't fit
Jimp = await import("jimp");
} catch {
sentImageProxyWarning = true;
console.log(
`[ImageProxy] ${yellow(
'Neither "sharp" or "jimp" NPM packages are installed, image resizing will be disabled',
)}`,
);
}
}
const [width, height] = path[1].split("x").map((x) => parseInt(x));
const buffer = Buffer.from(arrayBuffer);
if (sharp && sharpSupported.has(contentType)) {
resultBuffer = Buffer.from(
await sharp
.default(buffer)
// Sharp doesn't support "scaleToFit"
.resize(width)
.toBuffer(),
);
} else if (Jimp && jimpSupported.has(contentType)) {
resultBuffer = await Jimp.read(buffer).then((image) => {
contentType = image.getMIME();
return (
image
.scaleToFit(width, height)
// @ts-expect-error Jimp is defined at this point
.getBufferAsync(Jimp.AUTO)
);
});
}
}
res.header("Content-Type", contentType);
res.setHeader(
"Cache-Control",
"public, max-age=" + Config.get().cdn.proxyCacheHeaderSeconds,
);
res.send(resultBuffer);
}
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