Stop reading rejected save uploads to the controller

When a host pushes a save to a stream that is gone, or that timed out
before anyone downloaded it, the controller answers 404 or 500 without
reading the body. Node then reads and throws away the rest of the body
to keep the connection open, so a proxy in front of the controller that
keeps passing the upload on made the whole save get uploaded for
nothing. Close the connection if the body hasn't ended a second after
the response.

Document turning off request buffering in reverse proxies, as a
buffering proxy holds the upload back until all of it has arrived.

packages/controller/src/routes.ts

@@ -344,10 +344,36 @@ export async function createProxyStream(app: Application): Promise<ProxyStream>
 	return stream;
 }
 
+/** Time a rejected upload is read and thrown away before its connection is closed */
+const rejectedUploadDrainMs = 1000;
+
+/**
+ * Reject an upload without reading the rest of its body
+ *
+ * Node reads and discards the body of a request answered before it was
+ * read to keep the connection open. A client, or a proxy in front of the
+ * controller, that keeps sending would upload the whole body for nothing,
+ * so the connection is closed if the body hasn't ended shortly after the
+ * response. Closing it right away could make the client lose the response.
+ * @param req - The upload.
+ * @param res - Response to the upload.
+ * @param status - HTTP status to respond with.
+ */
+function rejectUpload(req: Request, res: Response, status: number) {
+	res.sendStatus(status);
+	if (req.complete) {
+		return;
+	}
+	const socket = req.socket;
+	const timeout = setTimeout(() => socket.destroy(), rejectedUploadDrainMs);
+	req.once("end", () => clearTimeout(timeout));
+	socket.once("close", () => clearTimeout(timeout));
+}
+
 async function putStream(req: Request<{ id: string }>, res: Response) {
 	const stream = req.app.locals.streams.get(req.params.id);
 	if (!stream || stream.source) {
-		res.sendStatus(404);
+		rejectUpload(req, res, 404);
 		return;
 	}
 	stream.source = req;
@@ -357,8 +383,7 @@ async function putStream(req: Request<{ id: string }>, res: Response) {
 	stream.events.emit("source");
 	stream.events.on("close", () => {
 		if (!stream.flowing) {
-			req.resume();
-			res.sendStatus(500);
+			rejectUpload(req, res, 500);
 		} else {
 			res.sendStatus(200);
 		}