初始化

node_modules/undici/lib/web/websocket/websocket.js

@@ -0,0 +1,739 @@
+'use strict'
+
+const { isArrayBuffer } = require('node:util/types')
+const { webidl } = require('../webidl')
+const { URLSerializer } = require('../fetch/data-url')
+const { environmentSettingsObject } = require('../fetch/util')
+const { staticPropertyDescriptors, states, sentCloseFrameState, sendHints, opcodes } = require('./constants')
+const {
+  isConnecting,
+  isEstablished,
+  isClosing,
+  isClosed,
+  isValidSubprotocol,
+  fireEvent,
+  utf8Decode,
+  toArrayBuffer,
+  getURLRecord
+} = require('./util')
+const { establishWebSocketConnection, closeWebSocketConnection, failWebsocketConnection } = require('./connection')
+const { ByteParser } = require('./receiver')
+const { kEnumerableProperty } = require('../../core/util')
+const { getGlobalDispatcher } = require('../../global')
+const { ErrorEvent, CloseEvent, createFastMessageEvent } = require('./events')
+const { SendQueue } = require('./sender')
+const { WebsocketFrameSend } = require('./frame')
+const { channels } = require('../../core/diagnostics')
+
+/**
+ * @typedef {object} Handler
+ * @property {(response: any, extensions?: string[]) => void} onConnectionEstablished
+ * @property {(opcode: number, data: Buffer) => void} onMessage
+ * @property {(error: Error) => void} onParserError
+ * @property {() => void} onParserDrain
+ * @property {(chunk: Buffer) => void} onSocketData
+ * @property {(err: Error) => void} onSocketError
+ * @property {() => void} onSocketClose
+ * @property {(body: Buffer) => void} onPing
+ * @property {(body: Buffer) => void} onPong
+ *
+ * @property {number} readyState
+ * @property {import('stream').Duplex} socket
+ * @property {Set<number>} closeState
+ * @property {import('../fetch/index').Fetch} controller
+ * @property {boolean} [wasEverConnected=false]
+ */
+
+// https://websockets.spec.whatwg.org/#interface-definition
+class WebSocket extends EventTarget {
+  #events = {
+    open: null,
+    error: null,
+    close: null,
+    message: null
+  }
+
+  #bufferedAmount = 0
+  #protocol = ''
+  #extensions = ''
+
+  /** @type {SendQueue} */
+  #sendQueue
+
+  /** @type {Handler} */
+  #handler = {
+    onConnectionEstablished: (response, extensions) => this.#onConnectionEstablished(response, extensions),
+    onMessage: (opcode, data) => this.#onMessage(opcode, data),
+    onParserError: (err) => failWebsocketConnection(this.#handler, null, err.message),
+    onParserDrain: () => this.#onParserDrain(),
+    onSocketData: (chunk) => {
+      if (!this.#parser.write(chunk)) {
+        this.#handler.socket.pause()
+      }
+    },
+    onSocketError: (err) => {
+      this.#handler.readyState = states.CLOSING
+
+      if (channels.socketError.hasSubscribers) {
+        channels.socketError.publish(err)
+      }
+
+      this.#handler.socket.destroy()
+    },
+    onSocketClose: () => this.#onSocketClose(),
+    onPing: (body) => {
+      if (channels.ping.hasSubscribers) {
+        channels.ping.publish({
+          payload: body,
+          websocket: this
+        })
+      }
+    },
+    onPong: (body) => {
+      if (channels.pong.hasSubscribers) {
+        channels.pong.publish({
+          payload: body,
+          websocket: this
+        })
+      }
+    },
+
+    readyState: states.CONNECTING,
+    socket: null,
+    closeState: new Set(),
+    controller: null,
+    wasEverConnected: false
+  }
+
+  #url
+  #binaryType
+  /** @type {import('./receiver').ByteParser} */
+  #parser
+
+  /**
+   * @param {string} url
+   * @param {string|string[]} protocols
+   */
+  constructor (url, protocols = []) {
+    super()
+
+    webidl.util.markAsUncloneable(this)
+
+    const prefix = 'WebSocket constructor'
+    webidl.argumentLengthCheck(arguments, 1, prefix)
+
+    const options = webidl.converters['DOMString or sequence<DOMString> or WebSocketInit'](protocols, prefix, 'options')
+
+    url = webidl.converters.USVString(url)
+    protocols = options.protocols
+
+    // 1. Let baseURL be this's relevant settings object's API base URL.
+    const baseURL = environmentSettingsObject.settingsObject.baseUrl
+
+    // 2. Let urlRecord be the result of getting a URL record given url and baseURL.
+    const urlRecord = getURLRecord(url, baseURL)
+
+    // 3. If protocols is a string, set protocols to a sequence consisting
+    //    of just that string.
+    if (typeof protocols === 'string') {
+      protocols = [protocols]
+    }
+
+    // 4. If any of the values in protocols occur more than once or otherwise
+    //    fail to match the requirements for elements that comprise the value
+    //    of `Sec-WebSocket-Protocol` fields as defined by The WebSocket
+    //    protocol, then throw a "SyntaxError" DOMException.
+    if (protocols.length !== new Set(protocols.map(p => p.toLowerCase())).size) {
+      throw new DOMException('Invalid Sec-WebSocket-Protocol value', 'SyntaxError')
+    }
+
+    if (protocols.length > 0 && !protocols.every(p => isValidSubprotocol(p))) {
+      throw new DOMException('Invalid Sec-WebSocket-Protocol value', 'SyntaxError')
+    }
+
+    // 5. Set this's url to urlRecord.
+    this.#url = new URL(urlRecord.href)
+
+    // 6. Let client be this's relevant settings object.
+    const client = environmentSettingsObject.settingsObject
+
+    // 7. Run this step in parallel:
+    // 7.1. Establish a WebSocket connection given urlRecord, protocols,
+    //      and client.
+    this.#handler.controller = establishWebSocketConnection(
+      urlRecord,
+      protocols,
+      client,
+      this.#handler,
+      options
+    )
+
+    // Each WebSocket object has an associated ready state, which is a
+    // number representing the state of the connection. Initially it must
+    // be CONNECTING (0).
+    this.#handler.readyState = WebSocket.CONNECTING
+
+    // The extensions attribute must initially return the empty string.
+
+    // The protocol attribute must initially return the empty string.
+
+    // Each WebSocket object has an associated binary type, which is a
+    // BinaryType. Initially it must be "blob".
+    this.#binaryType = 'blob'
+  }
+
+  /**
+   * @see https://websockets.spec.whatwg.org/#dom-websocket-close
+   * @param {number|undefined} code
+   * @param {string|undefined} reason
+   */
+  close (code = undefined, reason = undefined) {
+    webidl.brandCheck(this, WebSocket)
+
+    const prefix = 'WebSocket.close'
+
+    if (code !== undefined) {
+      code = webidl.converters['unsigned short'](code, prefix, 'code', webidl.attributes.Clamp)
+    }
+
+    if (reason !== undefined) {
+      reason = webidl.converters.USVString(reason)
+    }
+
+    // 1. If code is the special value "missing", then set code to null.
+    code ??= null
+
+    // 2. If reason is the special value "missing", then set reason to the empty string.
+    reason ??= ''
+
+    // 3. Close the WebSocket with this, code, and reason.
+    closeWebSocketConnection(this.#handler, code, reason, true)
+  }
+
+  /**
+   * @see https://websockets.spec.whatwg.org/#dom-websocket-send
+   * @param {NodeJS.TypedArray|ArrayBuffer|Blob|string} data
+   */
+  send (data) {
+    webidl.brandCheck(this, WebSocket)
+
+    const prefix = 'WebSocket.send'
+    webidl.argumentLengthCheck(arguments, 1, prefix)
+
+    data = webidl.converters.WebSocketSendData(data, prefix, 'data')
+
+    // 1. If this's ready state is CONNECTING, then throw an
+    //    "InvalidStateError" DOMException.
+    if (isConnecting(this.#handler.readyState)) {
+      throw new DOMException('Sent before connected.', 'InvalidStateError')
+    }
+
+    // 2. Run the appropriate set of steps from the following list:
+    // https://datatracker.ietf.org/doc/html/rfc6455#section-6.1
+    // https://datatracker.ietf.org/doc/html/rfc6455#section-5.2
+
+    if (!isEstablished(this.#handler.readyState) || isClosing(this.#handler.readyState)) {
+      return
+    }
+
+    // If data is a string
+    if (typeof data === 'string') {
+      // If the WebSocket connection is established and the WebSocket
+      // closing handshake has not yet started, then the user agent
+      // must send a WebSocket Message comprised of the data argument
+      // using a text frame opcode; if the data cannot be sent, e.g.
+      // because it would need to be buffered but the buffer is full,
+      // the user agent must flag the WebSocket as full and then close
+      // the WebSocket connection. Any invocation of this method with a
+      // string argument that does not throw an exception must increase
+      // the bufferedAmount attribute by the number of bytes needed to
+      // express the argument as UTF-8.
+
+      const buffer = Buffer.from(data)
+
+      this.#bufferedAmount += buffer.byteLength
+      this.#sendQueue.add(buffer, () => {
+        this.#bufferedAmount -= buffer.byteLength
+      }, sendHints.text)
+    } else if (isArrayBuffer(data)) {
+      // If the WebSocket connection is established, and the WebSocket
+      // closing handshake has not yet started, then the user agent must
+      // send a WebSocket Message comprised of data using a binary frame
+      // opcode; if the data cannot be sent, e.g. because it would need
+      // to be buffered but the buffer is full, the user agent must flag
+      // the WebSocket as full and then close the WebSocket connection.
+      // The data to be sent is the data stored in the buffer described
+      // by the ArrayBuffer object. Any invocation of this method with an
+      // ArrayBuffer argument that does not throw an exception must
+      // increase the bufferedAmount attribute by the length of the
+      // ArrayBuffer in bytes.
+
+      this.#bufferedAmount += data.byteLength
+      this.#sendQueue.add(data, () => {
+        this.#bufferedAmount -= data.byteLength
+      }, sendHints.arrayBuffer)
+    } else if (ArrayBuffer.isView(data)) {
+      // If the WebSocket connection is established, and the WebSocket
+      // closing handshake has not yet started, then the user agent must
+      // send a WebSocket Message comprised of data using a binary frame
+      // opcode; if the data cannot be sent, e.g. because it would need to
+      // be buffered but the buffer is full, the user agent must flag the
+      // WebSocket as full and then close the WebSocket connection. The
+      // data to be sent is the data stored in the section of the buffer
+      // described by the ArrayBuffer object that data references. Any
+      // invocation of this method with this kind of argument that does
+      // not throw an exception must increase the bufferedAmount attribute
+      // by the length of data’s buffer in bytes.
+
+      this.#bufferedAmount += data.byteLength
+      this.#sendQueue.add(data, () => {
+        this.#bufferedAmount -= data.byteLength
+      }, sendHints.typedArray)
+    } else if (webidl.is.Blob(data)) {
+      // If the WebSocket connection is established, and the WebSocket
+      // closing handshake has not yet started, then the user agent must
+      // send a WebSocket Message comprised of data using a binary frame
+      // opcode; if the data cannot be sent, e.g. because it would need to
+      // be buffered but the buffer is full, the user agent must flag the
+      // WebSocket as full and then close the WebSocket connection. The data
+      // to be sent is the raw data represented by the Blob object. Any
+      // invocation of this method with a Blob argument that does not throw
+      // an exception must increase the bufferedAmount attribute by the size
+      // of the Blob object’s raw data, in bytes.
+
+      this.#bufferedAmount += data.size
+      this.#sendQueue.add(data, () => {
+        this.#bufferedAmount -= data.size
+      }, sendHints.blob)
+    }
+  }
+
+  get readyState () {
+    webidl.brandCheck(this, WebSocket)
+
+    // The readyState getter steps are to return this's ready state.
+    return this.#handler.readyState
+  }
+
+  get bufferedAmount () {
+    webidl.brandCheck(this, WebSocket)
+
+    return this.#bufferedAmount
+  }
+
+  get url () {
+    webidl.brandCheck(this, WebSocket)
+
+    // The url getter steps are to return this's url, serialized.
+    return URLSerializer(this.#url)
+  }
+
+  get extensions () {
+    webidl.brandCheck(this, WebSocket)
+
+    return this.#extensions
+  }
+
+  get protocol () {
+    webidl.brandCheck(this, WebSocket)
+
+    return this.#protocol
+  }
+
+  get onopen () {
+    webidl.brandCheck(this, WebSocket)
+
+    return this.#events.open
+  }
+
+  set onopen (fn) {
+    webidl.brandCheck(this, WebSocket)
+
+    if (this.#events.open) {
+      this.removeEventListener('open', this.#events.open)
+    }
+
+    const listener = webidl.converters.EventHandlerNonNull(fn)
+
+    if (listener !== null) {
+      this.addEventListener('open', listener)
+      this.#events.open = fn
+    } else {
+      this.#events.open = null
+    }
+  }
+
+  get onerror () {
+    webidl.brandCheck(this, WebSocket)
+
+    return this.#events.error
+  }
+
+  set onerror (fn) {
+    webidl.brandCheck(this, WebSocket)
+
+    if (this.#events.error) {
+      this.removeEventListener('error', this.#events.error)
+    }
+
+    const listener = webidl.converters.EventHandlerNonNull(fn)
+
+    if (listener !== null) {
+      this.addEventListener('error', listener)
+      this.#events.error = fn
+    } else {
+      this.#events.error = null
+    }
+  }
+
+  get onclose () {
+    webidl.brandCheck(this, WebSocket)
+
+    return this.#events.close
+  }
+
+  set onclose (fn) {
+    webidl.brandCheck(this, WebSocket)
+
+    if (this.#events.close) {
+      this.removeEventListener('close', this.#events.close)
+    }
+
+    const listener = webidl.converters.EventHandlerNonNull(fn)
+
+    if (listener !== null) {
+      this.addEventListener('close', listener)
+      this.#events.close = fn
+    } else {
+      this.#events.close = null
+    }
+  }
+
+  get onmessage () {
+    webidl.brandCheck(this, WebSocket)
+
+    return this.#events.message
+  }
+
+  set onmessage (fn) {
+    webidl.brandCheck(this, WebSocket)
+
+    if (this.#events.message) {
+      this.removeEventListener('message', this.#events.message)
+    }
+
+    const listener = webidl.converters.EventHandlerNonNull(fn)
+
+    if (listener !== null) {
+      this.addEventListener('message', listener)
+      this.#events.message = fn
+    } else {
+      this.#events.message = null
+    }
+  }
+
+  get binaryType () {
+    webidl.brandCheck(this, WebSocket)
+
+    return this.#binaryType
+  }
+
+  set binaryType (type) {
+    webidl.brandCheck(this, WebSocket)
+
+    if (type !== 'blob' && type !== 'arraybuffer') {
+      this.#binaryType = 'blob'
+    } else {
+      this.#binaryType = type
+    }
+  }
+
+  /**
+   * @see https://websockets.spec.whatwg.org/#feedback-from-the-protocol
+   */
+  #onConnectionEstablished (response, parsedExtensions) {
+    // processResponse is called when the "response’s header list has been received and initialized."
+    // once this happens, the connection is open
+    this.#handler.socket = response.socket
+
+    const parser = new ByteParser(this.#handler, parsedExtensions)
+    parser.on('drain', () => this.#handler.onParserDrain())
+    parser.on('error', (err) => this.#handler.onParserError(err))
+
+    this.#parser = parser
+    this.#sendQueue = new SendQueue(response.socket)
+
+    // 1. Change the ready state to OPEN (1).
+    this.#handler.readyState = states.OPEN
+
+    // 2. Change the extensions attribute’s value to the extensions in use, if
+    //    it is not the null value.
+    // https://datatracker.ietf.org/doc/html/rfc6455#section-9.1
+    const extensions = response.headersList.get('sec-websocket-extensions')
+
+    if (extensions !== null) {
+      this.#extensions = extensions
+    }
+
+    // 3. Change the protocol attribute’s value to the subprotocol in use, if
+    //    it is not the null value.
+    // https://datatracker.ietf.org/doc/html/rfc6455#section-1.9
+    const protocol = response.headersList.get('sec-websocket-protocol')
+
+    if (protocol !== null) {
+      this.#protocol = protocol
+    }
+
+    // 4. Fire an event named open at the WebSocket object.
+    fireEvent('open', this)
+
+    if (channels.open.hasSubscribers) {
+      // Convert headers to a plain object for the event
+      const headers = response.headersList.entries
+      channels.open.publish({
+        address: response.socket.address(),
+        protocol: this.#protocol,
+        extensions: this.#extensions,
+        websocket: this,
+        handshakeResponse: {
+          status: response.status,
+          statusText: response.statusText,
+          headers
+        }
+      })
+    }
+  }
+
+  #onMessage (type, data) {
+    // 1. If ready state is not OPEN (1), then return.
+    if (this.#handler.readyState !== states.OPEN) {
+      return
+    }
+
+    // 2. Let dataForEvent be determined by switching on type and binary type:
+    let dataForEvent
+
+    if (type === opcodes.TEXT) {
+      // -> type indicates that the data is Text
+      //      a new DOMString containing data
+      try {
+        dataForEvent = utf8Decode(data)
+      } catch {
+        failWebsocketConnection(this.#handler, 1007, 'Received invalid UTF-8 in text frame.')
+        return
+      }
+    } else if (type === opcodes.BINARY) {
+      if (this.#binaryType === 'blob') {
+        // -> type indicates that the data is Binary and binary type is "blob"
+        //      a new Blob object, created in the relevant Realm of the WebSocket
+        //      object, that represents data as its raw data
+        dataForEvent = new Blob([data])
+      } else {
+        // -> type indicates that the data is Binary and binary type is "arraybuffer"
+        //      a new ArrayBuffer object, created in the relevant Realm of the
+        //      WebSocket object, whose contents are data
+        dataForEvent = toArrayBuffer(data)
+      }
+    }
+
+    // 3. Fire an event named message at the WebSocket object, using MessageEvent,
+    //    with the origin attribute initialized to the serialization of the WebSocket
+    //    object’s url's origin, and the data attribute initialized to dataForEvent.
+    fireEvent('message', this, createFastMessageEvent, {
+      origin: this.#url.origin,
+      data: dataForEvent
+    })
+  }
+
+  #onParserDrain () {
+    this.#handler.socket.resume()
+  }
+
+  /**
+   * @see https://websockets.spec.whatwg.org/#feedback-from-the-protocol
+   * @see https://datatracker.ietf.org/doc/html/rfc6455#section-7.1.4
+   */
+  #onSocketClose () {
+    // If the TCP connection was closed after the
+    // WebSocket closing handshake was completed, the WebSocket connection
+    // is said to have been closed _cleanly_.
+    const wasClean =
+      this.#handler.closeState.has(sentCloseFrameState.SENT) &&
+      this.#handler.closeState.has(sentCloseFrameState.RECEIVED)
+
+    let code = 1005
+    let reason = ''
+
+    const result = this.#parser?.closingInfo
+
+    if (result && !result.error) {
+      code = result.code ?? 1005
+      reason = result.reason
+    }
+
+    // 1. Change the ready state to CLOSED (3).
+    this.#handler.readyState = states.CLOSED
+
+    // 2. If the user agent was required to fail the WebSocket
+    //    connection, or if the WebSocket connection was closed
+    //    after being flagged as full, fire an event named error
+    //    at the WebSocket object.
+    if (!this.#handler.closeState.has(sentCloseFrameState.RECEIVED)) {
+      // If _The WebSocket
+      // Connection is Closed_ and no Close control frame was received by the
+      // endpoint (such as could occur if the underlying transport connection
+      // is lost), _The WebSocket Connection Close Code_ is considered to be
+      // 1006.
+      code = 1006
+
+      fireEvent('error', this, (type, init) => new ErrorEvent(type, init), {
+        error: new TypeError(reason)
+      })
+    }
+
+    // 3. Fire an event named close at the WebSocket object,
+    //    using CloseEvent, with the wasClean attribute
+    //    initialized to true if the connection closed cleanly
+    //    and false otherwise, the code attribute initialized to
+    //    the WebSocket connection close code, and the reason
+    //    attribute initialized to the result of applying UTF-8
+    //    decode without BOM to the WebSocket connection close
+    //    reason.
+    // TODO: process.nextTick
+    fireEvent('close', this, (type, init) => new CloseEvent(type, init), {
+      wasClean, code, reason
+    })
+
+    if (channels.close.hasSubscribers) {
+      channels.close.publish({
+        websocket: this,
+        code,
+        reason
+      })
+    }
+  }
+
+  /**
+   * @param {WebSocket} ws
+   * @param {Buffer|undefined} buffer
+   */
+  static ping (ws, buffer) {
+    if (Buffer.isBuffer(buffer)) {
+      if (buffer.length > 125) {
+        throw new TypeError('A PING frame cannot have a body larger than 125 bytes.')
+      }
+    } else if (buffer !== undefined) {
+      throw new TypeError('Expected buffer payload')
+    }
+
+    // An endpoint MAY send a Ping frame any time after the connection is
+    // established and before the connection is closed.
+    const readyState = ws.#handler.readyState
+
+    if (isEstablished(readyState) && !isClosing(readyState) && !isClosed(readyState)) {
+      const frame = new WebsocketFrameSend(buffer)
+      ws.#handler.socket.write(frame.createFrame(opcodes.PING))
+    }
+  }
+}
+
+const { ping } = WebSocket
+Reflect.deleteProperty(WebSocket, 'ping')
+
+// https://websockets.spec.whatwg.org/#dom-websocket-connecting
+WebSocket.CONNECTING = WebSocket.prototype.CONNECTING = states.CONNECTING
+// https://websockets.spec.whatwg.org/#dom-websocket-open
+WebSocket.OPEN = WebSocket.prototype.OPEN = states.OPEN
+// https://websockets.spec.whatwg.org/#dom-websocket-closing
+WebSocket.CLOSING = WebSocket.prototype.CLOSING = states.CLOSING
+// https://websockets.spec.whatwg.org/#dom-websocket-closed
+WebSocket.CLOSED = WebSocket.prototype.CLOSED = states.CLOSED
+
+Object.defineProperties(WebSocket.prototype, {
+  CONNECTING: staticPropertyDescriptors,
+  OPEN: staticPropertyDescriptors,
+  CLOSING: staticPropertyDescriptors,
+  CLOSED: staticPropertyDescriptors,
+  url: kEnumerableProperty,
+  readyState: kEnumerableProperty,
+  bufferedAmount: kEnumerableProperty,
+  onopen: kEnumerableProperty,
+  onerror: kEnumerableProperty,
+  onclose: kEnumerableProperty,
+  close: kEnumerableProperty,
+  onmessage: kEnumerableProperty,
+  binaryType: kEnumerableProperty,
+  send: kEnumerableProperty,
+  extensions: kEnumerableProperty,
+  protocol: kEnumerableProperty,
+  [Symbol.toStringTag]: {
+    value: 'WebSocket',
+    writable: false,
+    enumerable: false,
+    configurable: true
+  }
+})
+
+Object.defineProperties(WebSocket, {
+  CONNECTING: staticPropertyDescriptors,
+  OPEN: staticPropertyDescriptors,
+  CLOSING: staticPropertyDescriptors,
+  CLOSED: staticPropertyDescriptors
+})
+
+webidl.converters['sequence<DOMString>'] = webidl.sequenceConverter(
+  webidl.converters.DOMString
+)
+
+webidl.converters['DOMString or sequence<DOMString>'] = function (V, prefix, argument) {
+  if (webidl.util.Type(V) === webidl.util.Types.OBJECT && Symbol.iterator in V) {
+    return webidl.converters['sequence<DOMString>'](V)
+  }
+
+  return webidl.converters.DOMString(V, prefix, argument)
+}
+
+// This implements the proposal made in https://github.com/whatwg/websockets/issues/42
+webidl.converters.WebSocketInit = webidl.dictionaryConverter([
+  {
+    key: 'protocols',
+    converter: webidl.converters['DOMString or sequence<DOMString>'],
+    defaultValue: () => []
+  },
+  {
+    key: 'dispatcher',
+    converter: webidl.converters.any,
+    defaultValue: () => getGlobalDispatcher()
+  },
+  {
+    key: 'headers',
+    converter: webidl.nullableConverter(webidl.converters.HeadersInit)
+  }
+])
+
+webidl.converters['DOMString or sequence<DOMString> or WebSocketInit'] = function (V) {
+  if (webidl.util.Type(V) === webidl.util.Types.OBJECT && !(Symbol.iterator in V)) {
+    return webidl.converters.WebSocketInit(V)
+  }
+
+  return { protocols: webidl.converters['DOMString or sequence<DOMString>'](V) }
+}
+
+webidl.converters.WebSocketSendData = function (V) {
+  if (webidl.util.Type(V) === webidl.util.Types.OBJECT) {
+    if (webidl.is.Blob(V)) {
+      return V
+    }
+
+    if (webidl.is.BufferSource(V)) {
+      return V
+    }
+  }
+
+  return webidl.converters.USVString(V)
+}
+
+module.exports = {
+  WebSocket,
+  ping
+}