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| 1 | +import "@tanstack/react-start/server-only"; |
| 2 | +import { DurableObject } from "cloudflare:workers"; |
| 3 | + |
| 4 | +type SubscribeMessage = { |
| 5 | + type: "subscribe"; |
| 6 | + keys: string[]; |
| 7 | +}; |
| 8 | + |
| 9 | +function isSubscribeMessage(data: unknown): data is SubscribeMessage { |
| 10 | + return ( |
| 11 | + typeof data === "object" && |
| 12 | + data !== null && |
| 13 | + "type" in data && |
| 14 | + data.type === "subscribe" && |
| 15 | + "keys" in data && |
| 16 | + Array.isArray(data.keys) && |
| 17 | + data.keys.every((k: unknown) => typeof k === "string") |
| 18 | + ); |
| 19 | +} |
| 20 | + |
| 21 | +export class SignalRelay extends DurableObject { |
| 22 | + private subscriptions = new Map<WebSocket, Set<string>>(); |
| 23 | + |
| 24 | + async fetch(request: Request): Promise<Response> { |
| 25 | + const url = new URL(request.url); |
| 26 | + |
| 27 | + if (url.pathname === "/broadcast" && request.method === "POST") { |
| 28 | + return this.handleBroadcast(request); |
| 29 | + } |
| 30 | + |
| 31 | + if (url.pathname === "/connect") { |
| 32 | + return this.handleConnect(request); |
| 33 | + } |
| 34 | + |
| 35 | + return new Response("Not found", { status: 404 }); |
| 36 | + } |
| 37 | + |
| 38 | + private handleConnect(request: Request): Response { |
| 39 | + const upgradeHeader = request.headers.get("Upgrade"); |
| 40 | + if (upgradeHeader !== "websocket") { |
| 41 | + return new Response("Expected WebSocket upgrade", { status: 426 }); |
| 42 | + } |
| 43 | + |
| 44 | + const pair = new WebSocketPair(); |
| 45 | + const [client, server] = Object.values(pair); |
| 46 | + |
| 47 | + server.accept(); |
| 48 | + this.subscriptions.set(server, new Set()); |
| 49 | + |
| 50 | + server.addEventListener("message", (event) => { |
| 51 | + if (typeof event.data !== "string") return; |
| 52 | + |
| 53 | + try { |
| 54 | + const message: unknown = JSON.parse(event.data); |
| 55 | + if (isSubscribeMessage(message)) { |
| 56 | + this.subscriptions.set(server, new Set(message.keys)); |
| 57 | + } |
| 58 | + } catch { |
| 59 | + // ignore malformed messages |
| 60 | + } |
| 61 | + }); |
| 62 | + |
| 63 | + server.addEventListener("close", () => { |
| 64 | + this.subscriptions.delete(server); |
| 65 | + }); |
| 66 | + |
| 67 | + server.addEventListener("error", () => { |
| 68 | + this.subscriptions.delete(server); |
| 69 | + }); |
| 70 | + |
| 71 | + return new Response(null, { |
| 72 | + status: 101, |
| 73 | + webSocket: client, |
| 74 | + } as ResponseInit); |
| 75 | + } |
| 76 | + |
| 77 | + private async handleBroadcast(request: Request): Promise<Response> { |
| 78 | + const body = (await request.json()) as { signalKeys?: string[] }; |
| 79 | + const signalKeys = body.signalKeys; |
| 80 | + if (!Array.isArray(signalKeys) || signalKeys.length === 0) { |
| 81 | + return new Response("Missing signalKeys", { status: 400 }); |
| 82 | + } |
| 83 | + |
| 84 | + const signalSet = new Set(signalKeys); |
| 85 | + const payload = JSON.stringify({ type: "signals", keys: signalKeys }); |
| 86 | + let notified = 0; |
| 87 | + |
| 88 | + for (const [ws, subscribedKeys] of this.subscriptions) { |
| 89 | + const hasMatch = [...subscribedKeys].some((key) => signalSet.has(key)); |
| 90 | + if (!hasMatch) continue; |
| 91 | + |
| 92 | + try { |
| 93 | + ws.send(payload); |
| 94 | + notified++; |
| 95 | + } catch { |
| 96 | + this.subscriptions.delete(ws); |
| 97 | + } |
| 98 | + } |
| 99 | + |
| 100 | + return Response.json({ ok: true, notified }); |
| 101 | + } |
| 102 | +} |
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