System.Net.Sockets.MultipleConnectAsync.DoDnsCallback C# (CSharp) Method

        private bool DoDnsCallback(IAsyncResult result, bool sync)
        {
            Exception exception = null;

            lock (_lockObject)
            {
                // If the connection attempt was canceled during the dns query, the user's callback has already been
                // called asynchronously and we simply need to return.
                if (_state == State.Canceled)
                {
                    return true;
                }

                if (_state != State.DnsQuery)
                {
                    NetEventSource.Fail(this, "MultipleConnectAsync.DoDnsCallback(): Unexpected object state");
                }

                try
                {
                    _addressList = DnsAPMExtensions.EndGetHostAddresses(result);
                    if (_addressList == null)
                    {
                        NetEventSource.Fail(this, "MultipleConnectAsync.DoDnsCallback(): EndGetHostAddresses returned null!");
                    }
                }
                catch (Exception e)
                {
                    _state = State.Completed;
                    exception = e;
                }

                // If the dns query succeeded, try to connect to the first address
                if (exception == null)
                {
                    _state = State.ConnectAttempt;

                    _internalArgs = new SocketAsyncEventArgs();
                    _internalArgs.Completed += InternalConnectCallback;

                    if (!RequiresUserConnectAttempt)
                    {
                        _internalArgs.SetBuffer(_userArgs.Buffer, _userArgs.Offset, _userArgs.Count);
                    }

                    exception = AttemptConnection();

                    if (exception != null)
                    {
                        // There was a synchronous error while connecting
                        _state = State.Completed;
                    }
                }
            }

            // Call this outside of the lock because it might call the user's callback.
            if (exception != null)
            {
                return Fail(sync, exception);
            }
            else
            {
                return true;
            }
        }