basic version working

src/auth.ts

@@ -0,0 +1,87 @@
+import {
+  buildCommand,
+  buildError,
+  Command,
+  parseCommand,
+} from "./commandbuilder.ts";
+import { Device } from "./device.ts";
+
+function toHex(data: Uint8Array): string {
+  return Array.from(data).map((b) => ("00" + b.toString(16)).slice(-2)).join(
+    "",
+  );
+}
+async function generateHMAC(key: string, message: string) {
+  const encoder = new TextEncoder();
+  const keyData = encoder.encode(key);
+  const messageData = encoder.encode(message);
+
+  const cryptoKey = await crypto.subtle.importKey(
+    "raw",
+    keyData,
+    { name: "HMAC", hash: { name: "SHA-256" } },
+    false,
+    ["sign"],
+  );
+
+  const signature = await crypto.subtle.sign(
+    "HMAC",
+    cryptoKey,
+    messageData,
+  );
+
+  return toHex(new Uint8Array(signature));
+}
+
+export class Authentication {
+  _socket: WebSocket;
+  _encoder: TextEncoder;
+  nonce: string;
+  device: Device | undefined;
+  signature: string | undefined;
+
+  constructor(socket: WebSocket) {
+    this._socket = socket;
+    this._encoder = new TextEncoder();
+    this.nonce = toHex(crypto.getRandomValues(new Uint8Array(32)));
+  }
+
+  async authenticate(message: Command) { // ugh, js doesn't have async constructors, hence the seeprate init function.
+    if (
+      message.d == undefined || !("id" in message.d) ||
+      typeof (message.d.id) !== "string" || !(message.d.id in Device.devices)
+    ) {
+      this._socket.send(buildError(1, "Invalid packet. Missing ID"));
+      this._socket.close();
+      return;
+    }
+
+    this._socket.addEventListener("message", (msg) => this._validate(msg));
+    this.device = Device.devices[message.d.id];
+    this.signature = await generateHMAC(this.device.password, this.nonce);
+
+    this._socket.send(
+      buildCommand("auth_nonce", { nonce: this.nonce }),
+    );
+  }
+
+  _validate(msg: MessageEvent<any>) {
+    if (!this.device || !this.signature) return;
+
+    const parsed = parseCommand(msg.data);
+    if (
+      parsed === null || parsed.c !== "auth_validate" ||
+      parsed.d === undefined || !("signature" in parsed.d)
+    ) return;
+
+    if (this.signature !== parsed.d.signature) {
+      this._socket.send(buildError(2, "Invalid signature."));
+      this._socket.close;
+      return;
+    }
+
+    this._socket.send(buildCommand("auth_ok"));
+    this.device?.connect(this._socket);
+    this._socket.removeEventListener("message", this._validate);
+  }
+}