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Handle reserved WebSocket close codes in proxy #259

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Handle reserved WebSocket close codes in proxy #259

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34 changes: 30 additions & 4 deletions src/index.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -47,6 +47,32 @@ function transformErrorMessage(message: string, host: string): string {
return message;
}

function isSendableWsCloseCode(code: number): boolean {
// RFC 6455: 1005/1006/1015 are reserved and MUST NOT be sent in close frames.
if (!Number.isInteger(code)) return false;
if (code === 1005 || code === 1006 || code === 1015) return false;
if (code < 1000 || code >= 5000) return false;
if (code <= 1014) return true;
return code >= 3000 && code <= 4999;
}

function safeCloseWebSocket(ws: WebSocket, code: number, reason: string, fallbackCode = 1000): void {
if (ws.readyState === WebSocket.CLOSING || ws.readyState === WebSocket.CLOSED) return;

const safeCode = isSendableWsCloseCode(code) ? code : fallbackCode;
const safeReason = reason.length > 123 ? `${reason.slice(0, 120)}...` : reason;

try {
ws.close(safeCode, safeReason);
} catch {
try {
ws.close(fallbackCode, '');
} catch {
// ignore secondary close errors
}
}
}

export { Sandbox };

/**
Expand Down Expand Up @@ -390,7 +416,7 @@ app.all('*', async (c) => {
if (debugLogs) {
console.log('[WS] Client closed:', event.code, event.reason);
}
containerWs.close(event.code, event.reason);
safeCloseWebSocket(containerWs, event.code, event.reason, 1000);
});

containerWs.addEventListener('close', (event) => {
Expand All @@ -405,18 +431,18 @@ app.all('*', async (c) => {
if (debugLogs) {
console.log('[WS] Transformed close reason:', reason);
}
serverWs.close(event.code, reason);
safeCloseWebSocket(serverWs, event.code, reason, 1000);
});

// Handle errors
serverWs.addEventListener('error', (event) => {
console.error('[WS] Client error:', event);
containerWs.close(1011, 'Client error');
safeCloseWebSocket(containerWs, 1011, 'Client error', 1011);
});

containerWs.addEventListener('error', (event) => {
console.error('[WS] Container error:', event);
serverWs.close(1011, 'Container error');
safeCloseWebSocket(serverWs, 1011, 'Container error', 1011);
});

if (debugLogs) {
Expand Down