333 lines
10 KiB
JavaScript
333 lines
10 KiB
JavaScript
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'use strict'
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const { Writable } = require('node:stream')
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const { parserStates, opcodes, states, emptyBuffer, sentCloseFrameState } = require('./constants')
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const { kReadyState, kSentClose, kResponse, kReceivedClose } = require('./symbols')
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const { channels } = require('../../core/diagnostics')
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const { isValidStatusCode, failWebsocketConnection, websocketMessageReceived, utf8Decode } = require('./util')
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const { WebsocketFrameSend } = require('./frame')
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// This code was influenced by ws released under the MIT license.
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// Copyright (c) 2011 Einar Otto Stangvik <einaros@gmail.com>
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// Copyright (c) 2013 Arnout Kazemier and contributors
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// Copyright (c) 2016 Luigi Pinca and contributors
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class ByteParser extends Writable {
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#buffers = []
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#byteOffset = 0
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#state = parserStates.INFO
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#info = {}
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#fragments = []
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constructor (ws) {
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super()
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this.ws = ws
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}
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/**
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* @param {Buffer} chunk
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* @param {() => void} callback
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*/
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_write (chunk, _, callback) {
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this.#buffers.push(chunk)
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this.#byteOffset += chunk.length
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this.run(callback)
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}
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/**
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* Runs whenever a new chunk is received.
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* Callback is called whenever there are no more chunks buffering,
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* or not enough bytes are buffered to parse.
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*/
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run (callback) {
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while (true) {
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if (this.#state === parserStates.INFO) {
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// If there aren't enough bytes to parse the payload length, etc.
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if (this.#byteOffset < 2) {
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return callback()
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}
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const buffer = this.consume(2)
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this.#info.fin = (buffer[0] & 0x80) !== 0
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this.#info.opcode = buffer[0] & 0x0F
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// If we receive a fragmented message, we use the type of the first
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// frame to parse the full message as binary/text, when it's terminated
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this.#info.originalOpcode ??= this.#info.opcode
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this.#info.fragmented = !this.#info.fin && this.#info.opcode !== opcodes.CONTINUATION
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if (this.#info.fragmented && this.#info.opcode !== opcodes.BINARY && this.#info.opcode !== opcodes.TEXT) {
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// Only text and binary frames can be fragmented
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failWebsocketConnection(this.ws, 'Invalid frame type was fragmented.')
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return
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}
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const payloadLength = buffer[1] & 0x7F
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if (payloadLength <= 125) {
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this.#info.payloadLength = payloadLength
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this.#state = parserStates.READ_DATA
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} else if (payloadLength === 126) {
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this.#state = parserStates.PAYLOADLENGTH_16
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} else if (payloadLength === 127) {
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this.#state = parserStates.PAYLOADLENGTH_64
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}
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if (this.#info.fragmented && payloadLength > 125) {
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// A fragmented frame can't be fragmented itself
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failWebsocketConnection(this.ws, 'Fragmented frame exceeded 125 bytes.')
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return
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} else if (
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(this.#info.opcode === opcodes.PING ||
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this.#info.opcode === opcodes.PONG ||
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this.#info.opcode === opcodes.CLOSE) &&
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payloadLength > 125
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) {
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// Control frames can have a payload length of 125 bytes MAX
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failWebsocketConnection(this.ws, 'Payload length for control frame exceeded 125 bytes.')
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return
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} else if (this.#info.opcode === opcodes.CLOSE) {
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if (payloadLength === 1) {
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failWebsocketConnection(this.ws, 'Received close frame with a 1-byte body.')
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return
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}
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const body = this.consume(payloadLength)
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this.#info.closeInfo = this.parseCloseBody(body)
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if (this.ws[kSentClose] !== sentCloseFrameState.SENT) {
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// If an endpoint receives a Close frame and did not previously send a
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// Close frame, the endpoint MUST send a Close frame in response. (When
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// sending a Close frame in response, the endpoint typically echos the
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// status code it received.)
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let body = emptyBuffer
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if (this.#info.closeInfo.code) {
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body = Buffer.allocUnsafe(2)
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body.writeUInt16BE(this.#info.closeInfo.code, 0)
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}
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const closeFrame = new WebsocketFrameSend(body)
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this.ws[kResponse].socket.write(
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closeFrame.createFrame(opcodes.CLOSE),
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(err) => {
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if (!err) {
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this.ws[kSentClose] = sentCloseFrameState.SENT
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}
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}
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)
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}
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// Upon either sending or receiving a Close control frame, it is said
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// that _The WebSocket Closing Handshake is Started_ and that the
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// WebSocket connection is in the CLOSING state.
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this.ws[kReadyState] = states.CLOSING
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this.ws[kReceivedClose] = true
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this.end()
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return
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} else if (this.#info.opcode === opcodes.PING) {
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// Upon receipt of a Ping frame, an endpoint MUST send a Pong frame in
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// response, unless it already received a Close frame.
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// A Pong frame sent in response to a Ping frame must have identical
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// "Application data"
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const body = this.consume(payloadLength)
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if (!this.ws[kReceivedClose]) {
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const frame = new WebsocketFrameSend(body)
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this.ws[kResponse].socket.write(frame.createFrame(opcodes.PONG))
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if (channels.ping.hasSubscribers) {
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channels.ping.publish({
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payload: body
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})
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}
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}
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this.#state = parserStates.INFO
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if (this.#byteOffset > 0) {
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continue
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} else {
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callback()
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return
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}
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} else if (this.#info.opcode === opcodes.PONG) {
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// A Pong frame MAY be sent unsolicited. This serves as a
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// unidirectional heartbeat. A response to an unsolicited Pong frame is
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// not expected.
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const body = this.consume(payloadLength)
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if (channels.pong.hasSubscribers) {
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channels.pong.publish({
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payload: body
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})
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}
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if (this.#byteOffset > 0) {
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continue
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} else {
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callback()
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return
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}
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}
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} else if (this.#state === parserStates.PAYLOADLENGTH_16) {
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if (this.#byteOffset < 2) {
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return callback()
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}
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const buffer = this.consume(2)
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this.#info.payloadLength = buffer.readUInt16BE(0)
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this.#state = parserStates.READ_DATA
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} else if (this.#state === parserStates.PAYLOADLENGTH_64) {
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if (this.#byteOffset < 8) {
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return callback()
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}
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const buffer = this.consume(8)
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const upper = buffer.readUInt32BE(0)
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// 2^31 is the maxinimum bytes an arraybuffer can contain
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// on 32-bit systems. Although, on 64-bit systems, this is
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// 2^53-1 bytes.
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// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Errors/Invalid_array_length
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// https://source.chromium.org/chromium/chromium/src/+/main:v8/src/common/globals.h;drc=1946212ac0100668f14eb9e2843bdd846e510a1e;bpv=1;bpt=1;l=1275
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// https://source.chromium.org/chromium/chromium/src/+/main:v8/src/objects/js-array-buffer.h;l=34;drc=1946212ac0100668f14eb9e2843bdd846e510a1e
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if (upper > 2 ** 31 - 1) {
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failWebsocketConnection(this.ws, 'Received payload length > 2^31 bytes.')
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return
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}
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const lower = buffer.readUInt32BE(4)
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this.#info.payloadLength = (upper << 8) + lower
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this.#state = parserStates.READ_DATA
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} else if (this.#state === parserStates.READ_DATA) {
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if (this.#byteOffset < this.#info.payloadLength) {
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// If there is still more data in this chunk that needs to be read
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return callback()
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} else if (this.#byteOffset >= this.#info.payloadLength) {
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// If the server sent multiple frames in a single chunk
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const body = this.consume(this.#info.payloadLength)
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this.#fragments.push(body)
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// If the frame is unfragmented, or a fragmented frame was terminated,
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// a message was received
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if (!this.#info.fragmented || (this.#info.fin && this.#info.opcode === opcodes.CONTINUATION)) {
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const fullMessage = Buffer.concat(this.#fragments)
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websocketMessageReceived(this.ws, this.#info.originalOpcode, fullMessage)
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this.#info = {}
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this.#fragments.length = 0
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}
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this.#state = parserStates.INFO
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}
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}
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if (this.#byteOffset === 0) {
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callback()
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break
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}
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}
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}
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/**
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* Take n bytes from the buffered Buffers
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* @param {number} n
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* @returns {Buffer|null}
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*/
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consume (n) {
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if (n > this.#byteOffset) {
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return null
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} else if (n === 0) {
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return emptyBuffer
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}
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if (this.#buffers[0].length === n) {
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this.#byteOffset -= this.#buffers[0].length
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return this.#buffers.shift()
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}
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const buffer = Buffer.allocUnsafe(n)
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let offset = 0
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while (offset !== n) {
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const next = this.#buffers[0]
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const { length } = next
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if (length + offset === n) {
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buffer.set(this.#buffers.shift(), offset)
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break
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} else if (length + offset > n) {
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buffer.set(next.subarray(0, n - offset), offset)
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this.#buffers[0] = next.subarray(n - offset)
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break
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} else {
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buffer.set(this.#buffers.shift(), offset)
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offset += next.length
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}
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}
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this.#byteOffset -= n
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return buffer
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}
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parseCloseBody (data) {
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// https://datatracker.ietf.org/doc/html/rfc6455#section-7.1.5
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/** @type {number|undefined} */
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let code
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if (data.length >= 2) {
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// _The WebSocket Connection Close Code_ is
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// defined as the status code (Section 7.4) contained in the first Close
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// control frame received by the application
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code = data.readUInt16BE(0)
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}
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// https://datatracker.ietf.org/doc/html/rfc6455#section-7.1.6
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/** @type {Buffer} */
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let reason = data.subarray(2)
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// Remove BOM
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if (reason[0] === 0xEF && reason[1] === 0xBB && reason[2] === 0xBF) {
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reason = reason.subarray(3)
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}
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if (code !== undefined && !isValidStatusCode(code)) {
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return null
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}
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try {
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reason = utf8Decode(reason)
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} catch {
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return null
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}
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return { code, reason }
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}
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get closingInfo () {
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return this.#info.closeInfo
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}
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}
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module.exports = {
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ByteParser
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}
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