49 lines
2.3 KiB
JavaScript
49 lines
2.3 KiB
JavaScript
import { createHash } from "node:crypto";
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import { createServer } from "node:http";
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import { createServer as createNetServer } from "node:net";
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export async function freePort() {
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const server = createNetServer();
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await new Promise((resolve, reject) => { server.once("error", reject); server.listen(0, "127.0.0.1", resolve); });
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const port = server.address().port;
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await new Promise(resolve => server.close(resolve));
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return port;
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}
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// Accepts the WebSocket upgrade handshake so the frontend's real decoder-connect path
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// (src/decoder_runtime.js) reaches `connected: true` without a physical AMMC decoder.
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// No frames are sent or parsed: scenarios using this only need an established socket,
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// not lap data.
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export async function startFakeDecoder() {
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const port = await freePort();
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const server = createServer();
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// The upgraded sockets are intentionally left open (no decoder frames needed), so a
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// plain server.close() would wait forever for them to end; track and destroy them
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// explicitly instead. closeAllConnections() does not reach upgraded sockets.
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const sockets = new Set();
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let totalConnections = 0;
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server.on("upgrade", (req, socket) => {
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totalConnections += 1;
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sockets.add(socket);
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socket.on("close", () => sockets.delete(socket));
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const key = req.headers["sec-websocket-key"];
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if (!key) { socket.destroy(); return; }
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const accept = createHash("sha1").update(key + "258EAFA5-E914-47DA-95CA-C5AB0DC85B11").digest("base64");
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socket.write(["HTTP/1.1 101 Switching Protocols", "Upgrade: websocket", "Connection: Upgrade", `Sec-WebSocket-Accept: ${accept}`, "", ""].join("\r\n"));
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});
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await new Promise((resolve, reject) => { server.once("error", reject); server.listen(port, "127.0.0.1", resolve); });
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return {
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port,
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activeConnections: () => sockets.size,
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totalConnections: () => totalConnections,
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// Drops every currently-open socket with a raw TCP reset (not a clean WS close
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// handshake) to simulate a decoder/network interruption, while the server keeps
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// listening so the frontend's own reconnect logic has somewhere to reconnect to.
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dropConnections: () => { for (const socket of sockets) socket.destroy(); },
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close: () => new Promise(resolve => {
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for (const socket of sockets) socket.destroy();
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server.close(() => resolve());
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}),
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};
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}
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