TcpClient BeginConnect返回的ObjectDisposed

Question

如上所述，.EndConnect（）代码行返回ObjectDisposedException。

为什么呢？ 这是代码：

private TCPResult ConnectToHost(string hostname, int port) {
    IPAddress cachedDNS = DirectDNS.GetDNS(ref MainForm.DNS, hostname);
    TcpClient tcp = new TcpClient();
    try {
        #region Try connect
        IAsyncResult ar = tcp.BeginConnect(cachedDNS, port, (ari) => {
            TcpClient tcpi = (TcpClient)ari.AsyncState;
            try {
                tcpi.EndConnect(ari);
            } catch { }
            if (tcpi.Connected) {
                return; //return IAsyncResult and waitone will be true
            }
            tcpi.Close();
        }, tcp);
        #endregion
        #region If timed out, or not connected return null
        if(!ar.AsyncWaitHandle.WaitOne(_connectTimeout, false)) {
            return new TCPResult() {
                Result = null,
                Error = HttpError.ConnectToHostTimeout
            };
        }
        if (!tcp.Connected) {
            return new TCPResult() {
                Result = null,
                Error = HttpError.GeneralNotConnected
            };
        }
        #endregion
    } catch (Exception ex) {
        return new TCPResult() {
            Result = null,
            Error = HttpError.ConnectToHostException,
            Information = ex.GetType().Name + " - " + ex.Message
        };
    }
    tcp.SendTimeout = _readWriteTimeout;
    tcp.ReceiveTimeout = _readWriteTimeout;
    return new TCPResult() {
        Result = tcp,
        Error = HttpError.Success
    };
}

是什么原因导致ObjectDisposed异常，因为这里没有什么对我真正突出。

通过查看调用堆栈，我可以看到此异常是由.EndConnect对Client.EndConnect的内部调用（其中Client = Socket Object）引发的，然后由THAT的内部EndConnect调用引发的