anouma/lib/meeting/signalingServer.ts

import type { WebSocket, WebSocketServer } from "ws";
import { verifyMeetingToken } from "./token";
import {
  broadcast,
  getParticipant,
  isKicked,
  joinRoom,
  kickFromRoom,
  leaveRoom,
  type Participant,
} from "./rooms";
import type { ClientToServerMessage, ParticipantSummary } from "./protocol";

// A connection has this long to send its "auth" message before being
// dropped. The token travels as the first WS message rather than a
// `?token=` query parameter so it doesn't end up persisted in reverse-proxy
// or access logs; it's still HMAC-signed and short-lived either way.
const AUTH_TIMEOUT_MS = 10_000;

function participantSummary(p: Participant): ParticipantSummary {
  return { participantId: p.participantId, name: p.name, role: p.role };
}

export function attachSignalingServer(wss: WebSocketServer) {
  wss.on("connection", (ws: WebSocket) => {
    let self: Participant | null = null;
    let eventSlug: string | null = null;

    const authTimeout = setTimeout(() => {
      if (!self) ws.close(4000, "auth-timeout");
    }, AUTH_TIMEOUT_MS);

    function handleAuth(token: string) {
      const payload = verifyMeetingToken(token);
      if (!payload) {
        ws.send(JSON.stringify({ type: "auth-error", reason: "invalid-token" }));
        ws.close(4000, "invalid-token");
        return;
      }
      if (isKicked(payload.eventSlug, payload.participantId, payload.clientId)) {
        ws.close(4001, "removed-by-host");
        return;
      }

      eventSlug = payload.eventSlug;
      self = {
        ws,
        participantId: payload.participantId,
        clientId: payload.clientId,
        name: payload.name,
        role: payload.role,
      };

      const existing = joinRoom(eventSlug, self);

      ws.send(
        JSON.stringify({
          type: "welcome",
          participantId: self.participantId,
          role: self.role,
          participants: existing.map(participantSummary),
        }),
      );

      broadcast(eventSlug, { type: "peer-joined", ...participantSummary(self) }, {
        exclude: self.participantId,
      });
    }

    ws.on("message", (raw) => {
      let message: ClientToServerMessage;
      try {
        message = JSON.parse(raw.toString());
      } catch {
        return;
      }

      if (message.type === "auth") {
        clearTimeout(authTimeout);
        if (self) return; // already authenticated on this connection
        handleAuth(message.token);
        return;
      }

      if (!self || !eventSlug) return; // no messages accepted before auth

      if (message.type === "offer" || message.type === "answer" || message.type === "ice-candidate") {
        const target = getParticipant(eventSlug, message.to);
        if (target && target.ws.readyState === target.ws.OPEN) {
          target.ws.send(
            JSON.stringify({ type: message.type, from: self.participantId, payload: message.payload }),
          );
        }
        return;
      }

      if (message.type === "kick") {
        if (self.role !== "host") return; // server-side authority, not client-claimed
        const target = getParticipant(eventSlug, message.targetParticipantId);
        if (!target) return;
        kickFromRoom(eventSlug, target.participantId);
        target.ws.send(JSON.stringify({ type: "kicked" }));
        target.ws.close(4001, "removed-by-host");
        broadcast(eventSlug, { type: "peer-left", participantId: target.participantId });
      }
    });

    ws.on("close", () => {
      clearTimeout(authTimeout);
      if (!self || !eventSlug) return;
      leaveRoom(eventSlug, self.participantId);
      broadcast(eventSlug, { type: "peer-left", participantId: self.participantId });
    });
  });
}