lighthouse-core/gather/connections/cri.js

/**
 * @license Copyright 2016 Google Inc. All Rights Reserved.
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
 * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.
 */
'use strict';

const Connection = require('./connection.js');
const WebSocket = require('ws');
const http = require('http');
const log = require('lighthouse-logger');

const DEFAULT_HOSTNAME = 'localhost';
const CONNECT_TIMEOUT = 10000;
const DEFAULT_PORT = 9222;

class CriConnection extends Connection {
  /**
   * @param {number=} port Optional port number. Defaults to 9222;
   * @param {string=} hostname Optional hostname. Defaults to localhost.
   * @constructor
   */
  constructor(port = DEFAULT_PORT, hostname = DEFAULT_HOSTNAME) {
    super();
    this.port = port;
    this.hostname = hostname;
  }

  /**
   * @override
   * @return {!Promise}
   */
  connect() {
    return this._runJsonCommand('new')
      .then(response => this._connectToSocket(response))
      .catch(_ => {
        // Compat: headless didn't support `/json/new` before m59. (#970, crbug.com/699392)
        // If no support, we fallback and reuse an existing open tab
        log.warn('CriConnection', 'Cannot create new tab; reusing open tab.');
        return this._runJsonCommand('list').then(tabs => {
          const firstTab = tabs[0];
          if (!Array.isArray(tabs) || !firstTab) {
            return Promise.reject(new Error('Cannot create new tab, and no tabs already open.'));
          }
          // first, we activate it to a foreground tab, then we connect
          return this._runJsonCommand(`activate/${firstTab.id}`)
              .then(_ => this._connectToSocket(firstTab));
        });
      });
  }

  /**
   * @param {!Object} response
   * @return {!Promise}
   */
  _connectToSocket(response) {
    const url = response.webSocketDebuggerUrl;
    this._pageId = response.id;

    return new Promise((resolve, reject) => {
      const ws = new WebSocket(url, {
        perMessageDeflate: false,
      });
      ws.on('open', () => {
        this._ws = ws;
        resolve();
      });
      ws.on('message', data => this.handleRawMessage(data));
      ws.on('close', this.dispose.bind(this));
      ws.on('error', reject);
    });
  }

  /**
   * @param {!string} command
   * @return {!Promise<string>}
   */
  _runJsonCommand(command) {
    return new Promise((resolve, reject) => {
      const request = http.get({
        hostname: this.hostname,
        port: this.port,
        path: '/json/' + command,
      }, response => {
        let data = '';
        response.on('data', chunk => {
          data += chunk;
        });
        response.on('end', _ => {
          if (response.statusCode === 200) {
            try {
              resolve(JSON.parse(data));
              return;
            } catch (e) {
              // In the case of 'close' & 'activate' Chromium returns a string rather than JSON: goo.gl/7v27xD
              if (data === 'Target is closing' || data === 'Target activated') {
                return resolve({message: data});
              }
              return reject(e);
            }
          }
          reject(new Error(`Protocol JSON API error (${command}), status: ${response.statusCode}`));
        });
      });

      request.setTimeout(CONNECT_TIMEOUT, _ => {
        request.abort();

        // After aborting, we expect an ECONNRESET error. Ignore.
        request.on('error', err => {
          if (err.code !== 'ECONNRESET') {
            throw err;
          }
        });

        // Reject on error with code specifically indicating timeout in connection setup.
        const err = new Error('Timeout waiting for initial Debugger Protocol connection.');
        err.code = 'CRI_TIMEOUT';
        log.error('CriConnection', err.message);
        reject(err);
      });
    });
  }

  /**
   * @override
   */
  disconnect() {
    if (!this._ws) {
      log.warn('CriConnection', 'disconnect() was called without an established connection.');
      return Promise.resolve();
    }
    return this._runJsonCommand(`close/${this._pageId}`).then(_ => {
      this._ws.removeAllListeners();
      this._ws.close();
      this._ws = null;
      this._pageId = null;
    });
  }

  /**
   * @override
   * @param {string} message
   */
  sendRawMessage(message) {
    this._ws.send(message);
  }
}

module.exports = CriConnection;