webap.js

var res = new MyBuf(msg);
      res.skip(2);  // length
      res.skip(2);  // uri
      res.skip(2);  // server_type
      res.skip(4);  // flag
      var code = parseInt(res.readUInt32LE());  // code
      if (code > 0) { // error code
        var exe_error_str = VOCS_CODE_MAP[code];
        if (exe_error_str) {
          return callback(exe_error_str);
        } else {
          var err = `UNKNOWN_ERROR_${code}`;
          return callback(err);
        }
      }
      var cid = res.readUInt32LE();
      var uid = res.readUInt32LE();
      res.skip(4);
      res.skip(4);  // time stamp
      var len = res.readUInt16LE();
      var channel_name = res.read(len);
      var gateway_count = res.readUInt16LE();
      // Logger.info(`Return from gwcs - cname: ${channel_name}, cid: ${cid}, uid: ${uid}`);

      // get gateway list from the response
      var gateway_list = [];
      for (var i = 0; i < gateway_count; i++) {
        var gateway_info = {};
        var ip_len = res.readUInt16LE();  // len
        var ip_str = res.read(ip_len);
        gateway_info.port = parseInt(ip_str.split(":")[1]);  // port
        if (!gateway_info.port) {
          Logger.error(`Error IP:port ${ip_str}`);
          continue;
        }
        gateway_info.ip = ip_str.split(":")[0];  // ip
        gateway_list.push(gateway_info);
      }

      var details = {};

      res.skip(6); // whatever
      var unilbs_ip_len = res.readUInt16LE();
      details["unilbs_ip"] = res.read(unilbs_ip_len);

      res.skip(4); // whatever
      var carrier_len = res.readUInt16LE();
      details["carrier"] = res.read(carrier_len);

      res.skip(4); // whatever
      var region_len = res.readUInt16LE();
      details["region"] = res.read(region_len);

      // process gateway_list
      var available_gateway_list = gateway_list.map(function(gateway_info){
        var domain = details.region == "CN" ? GATEWAY_DOMAIN_CN : GATEWAY_DOMAIN;
        var host = `webrtc-${gateway_info.ip.split(".").join("-")}.${domain}:${gateway_info.port}`;
        return host;
      });
      if (available_gateway_list.length) {
        var result = {
          'gateway_addr': available_gateway_list,
          'cid': cid,
          'uid': uid
        };
        callback(null, result);
      } else {
        callback(NO_GATEWAY_AVAILABLE);
      }