readmongo/node_modules/engine.io-client/lib/transports/websocket.js

const Transport = require("../transport");
const parser = require("engine.io-parser");
const parseqs = require("parseqs");
const yeast = require("yeast");
const { pick } = require("../util");
const {
  WebSocket,
  usingBrowserWebSocket,
  defaultBinaryType
} = require("./websocket-constructor");

const debug = require("debug")("engine.io-client:websocket");

// detect ReactNative environment
const isReactNative =
  typeof navigator !== "undefined" &&
  typeof navigator.product === "string" &&
  navigator.product.toLowerCase() === "reactnative";

class WS extends Transport {
  /**
   * WebSocket transport constructor.
   *
   * @api {Object} connection options
   * @api public
   */
  constructor(opts) {
    super(opts);

    this.supportsBinary = !opts.forceBase64;
  }

  /**
   * Transport name.
   *
   * @api public
   */
  get name() {
    return "websocket";
  }

  /**
   * Opens socket.
   *
   * @api private
   */
  doOpen() {
    if (!this.check()) {
      // let probe timeout
      return;
    }

    const uri = this.uri();
    const protocols = this.opts.protocols;

    // React Native only supports the 'headers' option, and will print a warning if anything else is passed
    const opts = isReactNative
      ? {}
      : pick(
          this.opts,
          "agent",
          "perMessageDeflate",
          "pfx",
          "key",
          "passphrase",
          "cert",
          "ca",
          "ciphers",
          "rejectUnauthorized",
          "localAddress"
        );

    if (this.opts.extraHeaders) {
      opts.headers = this.opts.extraHeaders;
    }

    try {
      this.ws =
        usingBrowserWebSocket && !isReactNative
          ? protocols
            ? new WebSocket(uri, protocols)
            : new WebSocket(uri)
          : new WebSocket(uri, protocols, opts);
    } catch (err) {
      return this.emit("error", err);
    }

    this.ws.binaryType = this.socket.binaryType || defaultBinaryType;

    this.addEventListeners();
  }

  /**
   * Adds event listeners to the socket
   *
   * @api private
   */
  addEventListeners() {
    const self = this;

    this.ws.onopen = function() {
      self.onOpen();
    };
    this.ws.onclose = function() {
      self.onClose();
    };
    this.ws.onmessage = function(ev) {
      self.onData(ev.data);
    };
    this.ws.onerror = function(e) {
      self.onError("websocket error", e);
    };
  }

  /**
   * Writes data to socket.
   *
   * @param {Array} array of packets.
   * @api private
   */
  write(packets) {
    const self = this;
    this.writable = false;

    // encodePacket efficient as it uses WS framing
    // no need for encodePayload
    let total = packets.length;
    let i = 0;
    const l = total;
    for (; i < l; i++) {
      (function(packet) {
        parser.encodePacket(packet, self.supportsBinary, function(data) {
          // always create a new object (GH-437)
          const opts = {};
          if (!usingBrowserWebSocket) {
            if (packet.options) {
              opts.compress = packet.options.compress;
            }

            if (self.opts.perMessageDeflate) {
              const len =
                "string" === typeof data
                  ? Buffer.byteLength(data)
                  : data.length;
              if (len < self.opts.perMessageDeflate.threshold) {
                opts.compress = false;
              }
            }
          }

          // Sometimes the websocket has already been closed but the browser didn't
          // have a chance of informing us about it yet, in that case send will
          // throw an error
          try {
            if (usingBrowserWebSocket) {
              // TypeError is thrown when passing the second argument on Safari
              self.ws.send(data);
            } else {
              self.ws.send(data, opts);
            }
          } catch (e) {
            debug("websocket closed before onclose event");
          }

          --total || done();
        });
      })(packets[i]);
    }

    function done() {
      self.emit("flush");

      // fake drain
      // defer to next tick to allow Socket to clear writeBuffer
      setTimeout(function() {
        self.writable = true;
        self.emit("drain");
      }, 0);
    }
  }

  /**
   * Called upon close
   *
   * @api private
   */
  onClose() {
    Transport.prototype.onClose.call(this);
  }

  /**
   * Closes socket.
   *
   * @api private
   */
  doClose() {
    if (typeof this.ws !== "undefined") {
      this.ws.close();
    }
  }

  /**
   * Generates uri for connection.
   *
   * @api private
   */
  uri() {
    let query = this.query || {};
    const schema = this.opts.secure ? "wss" : "ws";
    let port = "";

    // avoid port if default for schema
    if (
      this.opts.port &&
      (("wss" === schema && Number(this.opts.port) !== 443) ||
        ("ws" === schema && Number(this.opts.port) !== 80))
    ) {
      port = ":" + this.opts.port;
    }

    // append timestamp to URI
    if (this.opts.timestampRequests) {
      query[this.opts.timestampParam] = yeast();
    }

    // communicate binary support capabilities
    if (!this.supportsBinary) {
      query.b64 = 1;
    }

    query = parseqs.encode(query);

    // prepend ? to query
    if (query.length) {
      query = "?" + query;
    }

    const ipv6 = this.opts.hostname.indexOf(":") !== -1;
    return (
      schema +
      "://" +
      (ipv6 ? "[" + this.opts.hostname + "]" : this.opts.hostname) +
      port +
      this.opts.path +
      query
    );
  }

  /**
   * Feature detection for WebSocket.
   *
   * @return {Boolean} whether this transport is available.
   * @api public
   */
  check() {
    return (
      !!WebSocket &&
      !("__initialize" in WebSocket && this.name === WS.prototype.name)
    );
  }
}

module.exports = WS;