feat: init

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

@@ -0,0 +1,332 @@
+'use strict'
+
+const { Writable } = require('node:stream')
+const { parserStates, opcodes, states, emptyBuffer, sentCloseFrameState } = require('./constants')
+const { kReadyState, kSentClose, kResponse, kReceivedClose } = require('./symbols')
+const { channels } = require('../../core/diagnostics')
+const { isValidStatusCode, failWebsocketConnection, websocketMessageReceived, utf8Decode } = require('./util')
+const { WebsocketFrameSend } = require('./frame')
+
+// This code was influenced by ws released under the MIT license.
+// Copyright (c) 2011 Einar Otto Stangvik <einaros@gmail.com>
+// Copyright (c) 2013 Arnout Kazemier and contributors
+// Copyright (c) 2016 Luigi Pinca and contributors
+
+class ByteParser extends Writable {
+  #buffers = []
+  #byteOffset = 0
+
+  #state = parserStates.INFO
+
+  #info = {}
+  #fragments = []
+
+  constructor (ws) {
+    super()
+
+    this.ws = ws
+  }
+
+  /**
+   * @param {Buffer} chunk
+   * @param {() => void} callback
+   */
+  _write (chunk, _, callback) {
+    this.#buffers.push(chunk)
+    this.#byteOffset += chunk.length
+
+    this.run(callback)
+  }
+
+  /**
+   * Runs whenever a new chunk is received.
+   * Callback is called whenever there are no more chunks buffering,
+   * or not enough bytes are buffered to parse.
+   */
+  run (callback) {
+    while (true) {
+      if (this.#state === parserStates.INFO) {
+        // If there aren't enough bytes to parse the payload length, etc.
+        if (this.#byteOffset < 2) {
+          return callback()
+        }
+
+        const buffer = this.consume(2)
+
+        this.#info.fin = (buffer[0] & 0x80) !== 0
+        this.#info.opcode = buffer[0] & 0x0F
+
+        // If we receive a fragmented message, we use the type of the first
+        // frame to parse the full message as binary/text, when it's terminated
+        this.#info.originalOpcode ??= this.#info.opcode
+
+        this.#info.fragmented = !this.#info.fin && this.#info.opcode !== opcodes.CONTINUATION
+
+        if (this.#info.fragmented && this.#info.opcode !== opcodes.BINARY && this.#info.opcode !== opcodes.TEXT) {
+          // Only text and binary frames can be fragmented
+          failWebsocketConnection(this.ws, 'Invalid frame type was fragmented.')
+          return
+        }
+
+        const payloadLength = buffer[1] & 0x7F
+
+        if (payloadLength <= 125) {
+          this.#info.payloadLength = payloadLength
+          this.#state = parserStates.READ_DATA
+        } else if (payloadLength === 126) {
+          this.#state = parserStates.PAYLOADLENGTH_16
+        } else if (payloadLength === 127) {
+          this.#state = parserStates.PAYLOADLENGTH_64
+        }
+
+        if (this.#info.fragmented && payloadLength > 125) {
+          // A fragmented frame can't be fragmented itself
+          failWebsocketConnection(this.ws, 'Fragmented frame exceeded 125 bytes.')
+          return
+        } else if (
+          (this.#info.opcode === opcodes.PING ||
+            this.#info.opcode === opcodes.PONG ||
+            this.#info.opcode === opcodes.CLOSE) &&
+          payloadLength > 125
+        ) {
+          // Control frames can have a payload length of 125 bytes MAX
+          failWebsocketConnection(this.ws, 'Payload length for control frame exceeded 125 bytes.')
+          return
+        } else if (this.#info.opcode === opcodes.CLOSE) {
+          if (payloadLength === 1) {
+            failWebsocketConnection(this.ws, 'Received close frame with a 1-byte body.')
+            return
+          }
+
+          const body = this.consume(payloadLength)
+
+          this.#info.closeInfo = this.parseCloseBody(body)
+
+          if (this.ws[kSentClose] !== sentCloseFrameState.SENT) {
+            // If an endpoint receives a Close frame and did not previously send a
+            // Close frame, the endpoint MUST send a Close frame in response.  (When
+            // sending a Close frame in response, the endpoint typically echos the
+            // status code it received.)
+            let body = emptyBuffer
+            if (this.#info.closeInfo.code) {
+              body = Buffer.allocUnsafe(2)
+              body.writeUInt16BE(this.#info.closeInfo.code, 0)
+            }
+            const closeFrame = new WebsocketFrameSend(body)
+
+            this.ws[kResponse].socket.write(
+              closeFrame.createFrame(opcodes.CLOSE),
+              (err) => {
+                if (!err) {
+                  this.ws[kSentClose] = sentCloseFrameState.SENT
+                }
+              }
+            )
+          }
+
+          // 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.
+          this.ws[kReadyState] = states.CLOSING
+          this.ws[kReceivedClose] = true
+
+          this.end()
+
+          return
+        } else if (this.#info.opcode === opcodes.PING) {
+          // Upon receipt of a Ping frame, an endpoint MUST send a Pong frame in
+          // response, unless it already received a Close frame.
+          // A Pong frame sent in response to a Ping frame must have identical
+          // "Application data"
+
+          const body = this.consume(payloadLength)
+
+          if (!this.ws[kReceivedClose]) {
+            const frame = new WebsocketFrameSend(body)
+
+            this.ws[kResponse].socket.write(frame.createFrame(opcodes.PONG))
+
+            if (channels.ping.hasSubscribers) {
+              channels.ping.publish({
+                payload: body
+              })
+            }
+          }
+
+          this.#state = parserStates.INFO
+
+          if (this.#byteOffset > 0) {
+            continue
+          } else {
+            callback()
+            return
+          }
+        } else if (this.#info.opcode === opcodes.PONG) {
+          // A Pong frame MAY be sent unsolicited.  This serves as a
+          // unidirectional heartbeat.  A response to an unsolicited Pong frame is
+          // not expected.
+
+          const body = this.consume(payloadLength)
+
+          if (channels.pong.hasSubscribers) {
+            channels.pong.publish({
+              payload: body
+            })
+          }
+
+          if (this.#byteOffset > 0) {
+            continue
+          } else {
+            callback()
+            return
+          }
+        }
+      } else if (this.#state === parserStates.PAYLOADLENGTH_16) {
+        if (this.#byteOffset < 2) {
+          return callback()
+        }
+
+        const buffer = this.consume(2)
+
+        this.#info.payloadLength = buffer.readUInt16BE(0)
+        this.#state = parserStates.READ_DATA
+      } else if (this.#state === parserStates.PAYLOADLENGTH_64) {
+        if (this.#byteOffset < 8) {
+          return callback()
+        }
+
+        const buffer = this.consume(8)
+        const upper = buffer.readUInt32BE(0)
+
+        // 2^31 is the maxinimum bytes an arraybuffer can contain
+        // on 32-bit systems. Although, on 64-bit systems, this is
+        // 2^53-1 bytes.
+        // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Errors/Invalid_array_length
+        // https://source.chromium.org/chromium/chromium/src/+/main:v8/src/common/globals.h;drc=1946212ac0100668f14eb9e2843bdd846e510a1e;bpv=1;bpt=1;l=1275
+        // https://source.chromium.org/chromium/chromium/src/+/main:v8/src/objects/js-array-buffer.h;l=34;drc=1946212ac0100668f14eb9e2843bdd846e510a1e
+        if (upper > 2 ** 31 - 1) {
+          failWebsocketConnection(this.ws, 'Received payload length > 2^31 bytes.')
+          return
+        }
+
+        const lower = buffer.readUInt32BE(4)
+
+        this.#info.payloadLength = (upper << 8) + lower
+        this.#state = parserStates.READ_DATA
+      } else if (this.#state === parserStates.READ_DATA) {
+        if (this.#byteOffset < this.#info.payloadLength) {
+          // If there is still more data in this chunk that needs to be read
+          return callback()
+        } else if (this.#byteOffset >= this.#info.payloadLength) {
+          // If the server sent multiple frames in a single chunk
+
+          const body = this.consume(this.#info.payloadLength)
+
+          this.#fragments.push(body)
+
+          // If the frame is unfragmented, or a fragmented frame was terminated,
+          // a message was received
+          if (!this.#info.fragmented || (this.#info.fin && this.#info.opcode === opcodes.CONTINUATION)) {
+            const fullMessage = Buffer.concat(this.#fragments)
+
+            websocketMessageReceived(this.ws, this.#info.originalOpcode, fullMessage)
+
+            this.#info = {}
+            this.#fragments.length = 0
+          }
+
+          this.#state = parserStates.INFO
+        }
+      }
+
+      if (this.#byteOffset === 0) {
+        callback()
+        break
+      }
+    }
+  }
+
+  /**
+   * Take n bytes from the buffered Buffers
+   * @param {number} n
+   * @returns {Buffer|null}
+   */
+  consume (n) {
+    if (n > this.#byteOffset) {
+      return null
+    } else if (n === 0) {
+      return emptyBuffer
+    }
+
+    if (this.#buffers[0].length === n) {
+      this.#byteOffset -= this.#buffers[0].length
+      return this.#buffers.shift()
+    }
+
+    const buffer = Buffer.allocUnsafe(n)
+    let offset = 0
+
+    while (offset !== n) {
+      const next = this.#buffers[0]
+      const { length } = next
+
+      if (length + offset === n) {
+        buffer.set(this.#buffers.shift(), offset)
+        break
+      } else if (length + offset > n) {
+        buffer.set(next.subarray(0, n - offset), offset)
+        this.#buffers[0] = next.subarray(n - offset)
+        break
+      } else {
+        buffer.set(this.#buffers.shift(), offset)
+        offset += next.length
+      }
+    }
+
+    this.#byteOffset -= n
+
+    return buffer
+  }
+
+  parseCloseBody (data) {
+    // https://datatracker.ietf.org/doc/html/rfc6455#section-7.1.5
+    /** @type {number|undefined} */
+    let code
+
+    if (data.length >= 2) {
+      // _The WebSocket Connection Close Code_ is
+      // defined as the status code (Section 7.4) contained in the first Close
+      // control frame received by the application
+      code = data.readUInt16BE(0)
+    }
+
+    // https://datatracker.ietf.org/doc/html/rfc6455#section-7.1.6
+    /** @type {Buffer} */
+    let reason = data.subarray(2)
+
+    // Remove BOM
+    if (reason[0] === 0xEF && reason[1] === 0xBB && reason[2] === 0xBF) {
+      reason = reason.subarray(3)
+    }
+
+    if (code !== undefined && !isValidStatusCode(code)) {
+      return null
+    }
+
+    try {
+      reason = utf8Decode(reason)
+    } catch {
+      return null
+    }
+
+    return { code, reason }
+  }
+
+  get closingInfo () {
+    return this.#info.closeInfo
+  }
+}
+
+module.exports = {
+  ByteParser
+}