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bliveproxy

B站直播websocket hook框架

Dieses Skript sollte nicht direkt installiert werden. Es handelt sich hier um eine Bibliothek für andere Skripte, welche über folgenden Befehl in den Metadaten eines Skriptes eingebunden wird // @require https://update.greasyfork.org/scripts/417560/1045452/bliveproxy.js 

// ==UserScript==
// @name         bliveproxy
// @namespace    http://tampermonkey.net/
// @version      0.5
// @description  B站直播websocket hook框架
// @author       xfgryujk
// @include      /https?:\/\/live\.bilibili\.com\/?\??.*/
// @include      /https?:\/\/live\.bilibili\.com\/\d+\??.*/
// @include      /https?:\/\/live\.bilibili\.com\/(blanc\/)?\d+\??.*/
// @run-at       document-start
// @require      https://cdn.jsdelivr.net/gh/google/brotli@5692e422da6af1e991f9182345d58df87866bc5e/js/decode.js
// @grant        none
// ==/UserScript==

// 使用方法：
// bliveproxy.addCommandHandler('DANMU_MSG', command => {
//   console.log(command)
//   let info = command.info
//   info[1] = '测试'
// })
//
// 如果@grant不是none，则要使用unsafeWindow.bliveproxy

(function() {
  const HEADER_SIZE = 16

  const WS_BODY_PROTOCOL_VERSION_NORMAL = 0
  const WS_BODY_PROTOCOL_VERSION_HEARTBEAT = 1
  const WS_BODY_PROTOCOL_VERSION_BROTLI = 3

  const OP_HEARTBEAT_REPLY = 3 // WS_OP_HEARTBEAT_REPLY
  const OP_SEND_MSG_REPLY = 5 // WS_OP_MESSAGE
  const OP_AUTH_REPLY = 8 // WS_OP_CONNECT_SUCCESS

  // 兼容@grant不是none的情况
  let pageWindow = window
  if (typeof unsafeWindow !== 'undefined') {
    pageWindow = unsafeWindow
  }

  let textEncoder = new TextEncoder()
  let textDecoder = new TextDecoder()

  function main() {
    if (pageWindow.bliveproxy) {
      // 防止多次加载
      return
    }
    initApi()
    hook()
  }

  function initApi() {
    pageWindow.bliveproxy = api
  }

  let api = {
    addCommandHandler(cmd, handler) {
      let handlers = this._commandHandlers[cmd]
      if (!handlers) {
        handlers = this._commandHandlers[cmd] = []
      }
      handlers.push(handler)
    },
    removeCommandHandler(cmd, handler) {
      let handlers = this._commandHandlers[cmd]
      if (!handlers) {
        return
      }
      this._commandHandlers[cmd] = handlers.filter(item => item !== handler)
    },

    // 私有API
    _commandHandlers: {},
    _getCommandHandlers(cmd) {
      return this._commandHandlers[cmd] || null
    }
  }

  function hook() {
    pageWindow.WebSocket = new Proxy(pageWindow.WebSocket, {
      construct(target, args) {
        let obj = new target(...args)
        return new Proxy(obj, proxyHandler)
      }
    })
  }

  let proxyHandler = {
    get(target, property) {
      let value = target[property]
      if ((typeof value) === 'function') {
        value = value.bind(target)
      }
      return value
    },
    set(target, property, value) {
      if (property === 'onmessage') {
        let realOnMessage = value
        value = function(event) {
          myOnMessage(event, realOnMessage)
        }
      }
      target[property] = value
      return value
    }
  }

  function myOnMessage(event, realOnMessage) {
    if (!(event.data instanceof ArrayBuffer)) {
      realOnMessage(event)
      return
    }

    let data = new Uint8Array(event.data)
    function callRealOnMessageByPacket(packet) {
      realOnMessage({...event, data: packet})
    }
    handleMessage(data, callRealOnMessageByPacket)
  }

  function makePacketFromCommand(command) {
    let body = textEncoder.encode(JSON.stringify(command))
    return makePacketFromUint8Array(body, OP_SEND_MSG_REPLY)
  }

  function makePacketFromUint8Array(body, operation) {
    let packLen = HEADER_SIZE + body.byteLength
    let packet = new ArrayBuffer(packLen)

    // 不需要压缩
    let ver = operation === OP_HEARTBEAT_REPLY ? WS_BODY_PROTOCOL_VERSION_HEARTBEAT : WS_BODY_PROTOCOL_VERSION_NORMAL
    let packetView = new DataView(packet)
    packetView.setUint32(0, packLen)        // pack_len
    packetView.setUint16(4, HEADER_SIZE)    // raw_header_size
    packetView.setUint16(6, ver)            // ver
    packetView.setUint32(8, operation)      // operation
    packetView.setUint32(12, 1)             // seq_id

    let packetBody = new Uint8Array(packet, HEADER_SIZE, body.byteLength)
    for (let i = 0; i < body.byteLength; i++) {
      packetBody[i] = body[i]
    }
    return packet
  }

  function handleMessage(data, callRealOnMessageByPacket) {
    let dataView = new DataView(data.buffer)
    let operation = dataView.getUint32(8)

    switch (operation) {
    case OP_AUTH_REPLY:
    case OP_SEND_MSG_REPLY: {
      // 可能有多个包一起发，需要分包
      let offset = 0
      while (offset < data.byteLength) {
        let dataView = new DataView(data.buffer, offset)
        let packLen = dataView.getUint32(0)
        let rawHeaderSize = dataView.getUint16(4)
        let ver = dataView.getUint16(6)
        let operation = dataView.getUint32(8)
        // let seqId = dataView.getUint32(12)

        let body = new Uint8Array(data.buffer, offset + rawHeaderSize, packLen - rawHeaderSize)
        if (operation === OP_SEND_MSG_REPLY) {
          // 业务消息
          switch (ver) {
          case WS_BODY_PROTOCOL_VERSION_NORMAL: {
            // body是单个JSON消息
            body = textDecoder.decode(body)
            body = JSON.parse(body)
            handleCommand(body, callRealOnMessageByPacket)
            break
          }
          case WS_BODY_PROTOCOL_VERSION_BROTLI: {
            // body是压缩过的多个消息
            body = BrotliDecode(body)
            handleMessage(body, callRealOnMessageByPacket)
            break
          }
          default: {
            // 未知的body格式
            let packet = makePacketFromUint8Array(body, operation)
            callRealOnMessageByPacket(packet)
            break
          }
          }
        } else {
          // 非业务消息
          let packet = makePacketFromUint8Array(body, operation)
          callRealOnMessageByPacket(packet)
        }

        offset += packLen
      }
      break
    }

    // 服务器心跳包，前4字节是人气值，后面是客户端发的心跳包内容
    // packLen不包括客户端发的心跳包内容，不知道是不是服务器BUG
    // 这里没用到心跳包就不处理了
    // case OP_HEARTBEAT_REPLY:
    default: {
      // 只有一个包
      let packLen = dataView.getUint32(0)
      let rawHeaderSize = dataView.getUint16(4)

      let body = new Uint8Array(data.buffer, rawHeaderSize, packLen - rawHeaderSize)
      let packet = makePacketFromUint8Array(body, operation)
      callRealOnMessageByPacket(packet)
      break
    }
    }
  }

  function handleCommand(command, callRealOnMessageByPacket) {
    if (command instanceof Array) {
      for (let oneCommand of command) {
        this.handleCommand(oneCommand)
      }
      return
    }

    let cmd = command.cmd || ''
    let pos = cmd.indexOf(':')
    if (pos != -1) {
      cmd = cmd.substr(0, pos)
    }
    let handlers = api._getCommandHandlers(cmd)
    if (handlers) {
      for (let handler of handlers) {
        handler(command)
      }
    }
    // console.log(command)

    let packet = makePacketFromCommand(command)
    callRealOnMessageByPacket(packet)
  }

  main()
})();