Function createSignatureMiddleware

packages/cli/src/actions/proxy.ts:315–384

* Creates an Express middleware that verifies the ed25519 signature on every request. * * The signature header format is: `t= ,v1= ` * * The signed message is constructed as: * - GET requests: ` [ ]` * - Oth

(publicKey: string, toleranceSeconds: number)

 * `authorizationToken` is the bearer token value from the `Authorization` header (if present).
 */
function createSignatureMiddleware(publicKey: string, toleranceSeconds: number) {
    // Throttle invalid-signature warnings to at most once per 60 seconds.
    let lastInvalidSigWarnAt = 0;
    const WARN_THROTTLE_SECS = 60;

    function warnInvalidSignature() {
        const now = Math.floor(Date.now() / 1000);
        if (now - lastInvalidSigWarnAt >= WARN_THROTTLE_SECS) {
            lastInvalidSigWarnAt = now;
            console.warn(
                colors.yellow(
                    'Warning: Received a request with an invalid signature. ' +
                        'Please double-check whether you have the correct public API key configured.',
                ),
            );
        }
    }

    return (req: express.Request, res: express.Response, next: express.NextFunction) => {
        const signatureHeader = req.headers['x-zenstack-signature'];
        if (!signatureHeader || typeof signatureHeader !== 'string') {
            return rejectAuth(res, 'MISSING_SIGNATURE_HEADER');
        }

        const parts = signatureHeader.split(',');
        const timestampPart = parts.find((p) => p.startsWith('t='));
        const sigPart = parts.find((p) => p.startsWith('v1='));
        if (!timestampPart || !sigPart) {
            return rejectAuth(res, 'INVALID_SIGNATURE_FORMAT');
        }
        const timestamp = timestampPart.substring(2);
        const sig = sigPart.substring(3);

        // Replay-attack prevention: reject requests whose timestamp deviates
        // from server time by more than the configured tolerance.
        const requestTime = parseInt(timestamp, 10);
        const now = Math.floor(Date.now() / 1000);
        if (isNaN(requestTime) || Math.abs(now - requestTime) > toleranceSeconds) {
            return rejectAuth(res, 'INVALID_TIMESTAMP');
        }

        // Payload: raw query string for GET/DELETE, raw body for other methods.
        let payload: string;
        if (req.method === 'GET' || req.method === 'DELETE') {
            const qMark = req.originalUrl.indexOf('?');
            payload = qMark >= 0 ? req.originalUrl.substring(qMark + 1) : '';
        } else {
            payload = (req as express.Request & { rawBody?: string }).rawBody ?? '';
        }

        // authorizationToken is the bearer token value (if present).
        const authHeader = req.headers['authorization'];
        const authorizationToken = authHeader && authHeader.startsWith('Bearer ') ? authHeader.substring(7) : undefined;

        const message = authorizationToken ? `${payload}${timestamp}${authorizationToken}` : `${payload}${timestamp}`;

        try {
            const isValid = verify(null, Buffer.from(message, 'utf8'), publicKey, Buffer.from(sig, 'base64url'));