Function closeWebSocketConnection

lib/web/websocket/connection.js:227–297

* @see https://whatpr.org/websockets/48.html#close-the-websocket * @param {import('./websocket').Handler} object * @param {number} [code=null] * @param {string} [reason='']

(object, code, reason, validate = false)

 * @param {string} [reason='']
 */
function closeWebSocketConnection (object, code, reason, validate = false) {
  // 1. If code was not supplied, let code be null.
  code ??= null

  // 2. If reason was not supplied, let reason be the empty string.
  reason ??= ''

  // 3. Validate close code and reason with code and reason.
  if (validate) validateCloseCodeAndReason(code, reason)

  // 4. Run the first matching steps from the following list:
  //     - If object’s ready state is CLOSING (2) or CLOSED (3)
  //     - If the WebSocket connection is not yet established [WSP]
  //     - If the WebSocket closing handshake has not yet been started [WSP]
  //     - Otherwise
  if (isClosed(object.readyState) || isClosing(object.readyState)) {
    // Do nothing.
  } else if (!isEstablished(object.readyState)) {
    // Fail the WebSocket connection and set object’s ready state to CLOSING (2). [WSP]
    failWebsocketConnection(object)
    object.readyState = states.CLOSING
  } else if (!object.closeState.has(sentCloseFrameState.SENT) && !object.closeState.has(sentCloseFrameState.RECEIVED)) {
    // Upon either sending or receiving a Close control frame, it is said
    // that _The WebSocket Closing Handshake is Started_ and that the
    // WebSocket connection is in the CLOSING state.

    const frame = new WebsocketFrameSend()

    // If neither code nor reason is present, the WebSocket Close
    // message must not have a body.

    // If code is present, then the status code to use in the
    // WebSocket Close message must be the integer given by code.
    // If code is null and reason is the empty string, the WebSocket Close frame must not have a body.
    // If reason is non-empty but code is null, then set code to 1000 ("Normal Closure").
    if (reason.length !== 0 && code === null) {
      code = 1000
    }

    // If code is set, then the status code to use in the WebSocket Close frame must be the integer given by code.
    assert(code === null || Number.isInteger(code))

    if (code === null && reason.length === 0) {
      frame.frameData = emptyBuffer
    } else if (code !== null && reason === null) {
      frame.frameData = Buffer.allocUnsafe(2)
      frame.frameData.writeUInt16BE(code, 0)
    } else if (code !== null && reason !== null) {
      // If reason is also present, then reasonBytes must be
      // provided in the Close message after the status code.
      frame.frameData = Buffer.allocUnsafe(2 + Buffer.byteLength(reason))
      frame.frameData.writeUInt16BE(code, 0)
      // the body MAY contain UTF-8-encoded data with value /reason/
      frame.frameData.write(reason, 2, 'utf-8')
    } else {
      frame.frameData = emptyBuffer
    }