// =====================================================================
// TLS support
// =====================================================================
/// <summary>
/// Send IMap STARTTLS command and initialize client side TLS
/// </summary>
/// <param name="uTag">
/// <c>0</c> when called by GetConnection to initialize imaps. Otherwise
/// a valid tag number causes the STARTTLS imap command to be sent.
/// </param>
/// <returns>
/// <c>true</c> if no problem occurred, <c>false</c> on errors.
/// For TLS related error a <see cref="ZIMapException"/> is thrown.
/// </returns>
/// <remarks>
/// This routine throws an exception when TLS is "Required" but not
/// availlable. In "Auto" mode invalid server certificates are accepted,
/// in mode "Required" an exception is thrown.
/// </remarks>
public bool StartTls(uint uTag)
{
if(uTag == 0)
MonitorInfo( "StartTls: TLS via imaps");
else
{ if (tlsmode == TlsModeEnum.Disabled || tlsmode == TlsModeEnum.IMaps)
return true; // nothing to do
MonitorInfo( "StartTls: send STARTLS");
transport.Send(uTag, "STARTTLS");
string tag, status, message;
while (true)
{ if (!transport.Receive(out tag, out status, out message)) break;
if (tag == uTag.ToString()) break;
}
if (status != "OK")
{ if (tlsmode == TlsModeEnum.Required)
{ RaiseError(ZIMapException.Error.CannotConnect,
"STARTTLS failed: " + message);
return false; // required but not ready
}
MonitorInfo( "StartTls: STARTTLS failed: " + message);
tlsmode = TlsModeEnum.Disabled;
return true;
}
}
// now get the TLS stream
Stream strm = null;
try // all errors throw...
{ strm = GetTlsStream();
if(strm == null) return true; // tls disabled
stream = strm;
}
catch(Exception ex)
{ if(tlsmode == TlsModeEnum.Required)
{ RaiseError(ZIMapException.Error.CannotConnect, ex.Message);
return false; // required but not ready
}
if(ex is ZIMapException) throw ex;
MonitorError("TLS failure: " + ex.Message);
return false;
}
if(uTag == 0)
tlsmode = TlsModeEnum.IMaps;
else
transport.Setup(socket, stream, timeout);
return true;
}
/// <summary>
/// Creates a connection instance and opens an IMap connection.
/// </summary>
/// <param name="server">
/// The server URL or IP Address.
/// </param>
/// <param name="port">
/// The port number to be used, see <see cref="GetIMapPort(string)"/>.
/// </param>
/// <param name="tlsMode">
/// Controls TLS (tranport layer security), see <see cref="TlsModeEnum"/>.
/// </param>
/// <param name="timeout">
/// Connection timeout, use <c>0</c> for no timeout.
/// </param>
/// <returns>
/// A new instance of <c>ZIMapConnection</c> that is connected to the
/// specified IMap server.
/// </returns>
/// <remarks>
/// The method raises an error of type <see cref="ZIMapException.Error.CannotConnect"/>
/// if no connection can be established.
/// </remarks>
public static ZIMapConnection GetConnection(string server, uint port,
TlsModeEnum tlsMode, uint timeout)
{ ZIMapConnection conn = new ZIMapConnection();
conn.tlsmode = tlsMode;
conn.timeout = timeout;
try
{ conn.socket = new System.Net.Sockets.Socket(System.Net.Sockets.AddressFamily.InterNetwork,
System.Net.Sockets.SocketType.Stream,
System.Net.Sockets.ProtocolType.IP);
// The socket timeouts will be reset by the transport layer!
if(timeout > 0)
{ conn.socket.ReceiveTimeout = (int)timeout * 1000;
conn.socket.SendTimeout = (int)timeout * 1000;
}
conn.socket.NoDelay = true; // nagle causes more windows trouble
conn.server = server;
conn.socket.Connect(server, (int)port);
conn.stream = new System.Net.Sockets.NetworkStream(conn.socket);
}
catch(Exception inner)
{ if(inner is System.Net.Sockets.SocketException)
conn.MonitorError("GetConnection: " + inner.Message);
else
conn.RaiseError(ZIMapException.Error.CannotConnect, inner.Message);
return null;
}
// init transport level and start async receive ...
if(port == 993 && !conn.StartTls(0))
return null; // after Throw()
conn.transport = new Transport(conn);
// start async receive and init protocol layer ...
conn.transport.Poll(0);
conn.protocol = new Protocol(conn, conn.transport);
return conn;
}
