101 lines
3.5 KiB
TypeScript
101 lines
3.5 KiB
TypeScript
import { createHmac, randomUUID, timingSafeEqual } from "node:crypto";
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export type MeetingRole = "host" | "participant";
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export type MeetingTokenPayload = {
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eventSlug: string;
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participantId: string;
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// Self-declared, persisted client-side (localStorage, not sessionStorage)
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// identity for participants — participantId is fresh per /join call, so
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// without this a kick could always be undone by simply rejoining. Only
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// used to make a kick stick across a rejoin (see rooms.ts kickedClientIds);
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// never used to key live room membership, so a client choosing an
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// arbitrary/colliding value can only affect their own future kick status,
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// never another participant's connection. Still bypassable by clearing
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// localStorage or joining from a different browser — there's no real
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// identity to anchor to for an unauthenticated participant.
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clientId?: string;
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name: string;
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role: MeetingRole;
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accessVersion?: string;
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testRoom?: boolean;
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exp: number; // unix ms
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};
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function secret(): string {
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const value = process.env.MEETING_SESSION_SECRET;
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if (!value) throw new Error("MEETING_SESSION_SECRET is not set");
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return value;
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}
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function base64url(input: Buffer | string): string {
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return Buffer.from(input).toString("base64url");
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}
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function sign(data: string): string {
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return createHmac("sha256", secret()).update(data).digest("base64url");
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}
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/** Issues a short-lived, self-contained, signed token for one meeting session. */
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export function createMeetingToken(args: {
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eventSlug: string;
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name: string;
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role: MeetingRole;
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clientId?: string;
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ttlMs?: number;
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accessVersion?: string;
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testRoom?: boolean;
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}): { token: string; participantId: string } {
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const participantId = randomUUID();
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const clientId =
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typeof args.clientId === "string" && args.clientId.length > 0 && args.clientId.length <= 100
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? args.clientId
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: undefined;
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const payload: MeetingTokenPayload = {
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eventSlug: args.eventSlug,
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participantId,
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clientId,
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name: args.name,
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role: args.role,
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accessVersion: args.accessVersion,
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testRoom: args.testRoom,
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exp: Date.now() + (args.ttlMs ?? 6 * 60 * 60 * 1000), // 6h default
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};
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const body = base64url(JSON.stringify(payload));
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const signature = sign(body);
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return { token: `${body}.${signature}`, participantId };
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}
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/** Verifies signature + expiry. Returns null if invalid/expired/tampered. */
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export function verifyMeetingToken(token: unknown): MeetingTokenPayload | null {
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if (typeof token !== "string" || token.length > 4096) return null;
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const parts = token.split(".");
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if (parts.length !== 2) return null;
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const [body, signature] = parts;
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const expected = sign(body);
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const a = Buffer.from(signature);
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const b = Buffer.from(expected);
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if (a.length !== b.length || !timingSafeEqual(a, b)) return null;
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try {
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const payload = JSON.parse(Buffer.from(body, "base64url").toString("utf8")) as MeetingTokenPayload;
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if (
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!Number.isFinite(payload.exp) ||
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payload.exp <= Date.now() ||
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(payload.accessVersion !== undefined && !/^[0-9a-f]{64}$/.test(payload.accessVersion)) ||
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(payload.testRoom !== undefined && typeof payload.testRoom !== "boolean") ||
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typeof payload.eventSlug !== "string" ||
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payload.eventSlug.length > 200 ||
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typeof payload.participantId !== "string" ||
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payload.participantId.length > 100 ||
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typeof payload.name !== "string" ||
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payload.name.length > 120 ||
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(payload.role !== "host" && payload.role !== "participant")
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) return null;
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return payload;
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} catch {
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return null;
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}
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}
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