private void EndResolve()
{
if (State != ClientState.Disconnected)
{
try
{
_hostEntry = Dns.EndResolve(_currentAsyncResult);
}
catch (Exception e)
{
if (!HandleException(e))
{
throw new AsyncTcpClientException(this, e);
}
OnResolveFailed();
return;
}
try
{
State = ClientState.Connecting;
_socket = new SecureSocket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
if (_ssl3Enabled)
{
_socket.ChangeSecurityProtocol(new SecurityOptions(SecureProtocol.Ssl3));
}
_socket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.SendTimeout, Timeout);
_socket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReceiveTimeout, Timeout);
_endPoint = new IPEndPoint(_hostEntry.AddressList[0], _port);
if (_traceProtocol)
{
Trace("Connecting to " + _endPoint.Address.ToString() + ':' + _endPoint.Port.ToString());
}
CloseAsyncWaitHandle();
_currentAsyncResult = _socket.BeginConnect(_endPoint, null, null);
InvokeAfterWait(new MethodInvoker(EndConnect), _currentAsyncResult.AsyncWaitHandle);
}
catch (Exception e)
{
if (!HandleException(e))
{
throw new AsyncTcpClientException(this, e);
}
OnConnectFailed();
return;
}
}
}
public void Start()
{
try {
// ask the user for SMTP server, port and the type of connection
Console.Write("Host to connect to: ");
string server = Console.ReadLine().Trim();
Console.Write("Port: ");
string port = Console.ReadLine().Trim();
Console.Write("Connection type [0 = normal connection, 1 = direct TLS connection, 2 = indirect TLS connection (using STARTTLS command)]: ");
string type = Console.ReadLine().Trim();
if (Array.IndexOf(new string[] { "0", "1", "2" }, type) == -1)
{
Console.WriteLine("Invalid connection type.");
return;
}
Console.WriteLine("Please enter the email address you wish to send an email to:");
string address = Console.ReadLine().Trim();
// create a new SecurityOptions instance
SecurityOptions options = new SecurityOptions(SecureProtocol.None);
// allow only secure ciphers to be used. Currently, the seure ciphers are:
// the AES algorithm [128 or 256 bit keys], the RC4 algorithm [128 bit keys]
// or TipleDES [168 bit keys]
options.AllowedAlgorithms = SslAlgorithms.SECURE_CIPHERS;
// the SecureSocket should be a client socket
options.Entity = ConnectionEnd.Client;
// we will use manual verification of the server certificate
options.VerificationType = CredentialVerification.Manual;
// when the server certificate is receives, the SecureSocket should call
// the OnVerify method
options.Verifier = new CertVerifyEventHandler(OnVerify);
// use the default flags
options.Flags = SecurityFlags.Default;
// the common name is the domain name or IP address of the server
options.CommonName = server;
// if the user chose a direct TLS connection, set the protocol to TLS1
if (type == "1")
{
options.Protocol = SecureProtocol.Tls1;
}
// create the new secure socket
Connection = new SecureSocket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp, options);
// connect to the SMTP server
Connection.Connect(new IPEndPoint(Dns.Resolve(server).AddressList[0], int.Parse(port)));
// wait for the server hello message
if (!IsReplyOK(Receive()))
{
Console.WriteLine("Server disallowed connection.");
return;
}
// if the user selected an indirect TLS connection, issue
// a EHLO command. Otherwise, stick to the standard HELO command.
if (type == "2") // STARTTLS connection
{
Send("EHLO SmtpClient.Mentalis.org\r\n");
}
else
{
Send("HELO SmtpClient.Mentalis.org\r\n");
}
if (!IsReplyOK(Receive()))
{
Console.WriteLine("HELLO failed.");
return;
}
// if the user selected an indirect TLS connection, issue
// the STARTTLS command
if (type == "2")
{
// send the STARTTLS command to the server
Send("STARTTLS\r\n");
// make sure the server supports the STARTTLS command
if (!IsReplyOK(Receive()))
{
Console.WriteLine("STARTTLS failed.");
return;
}
// change the protocol from SecureProtocol.None
// to SecureProtocol.Tls1
options.Protocol = SecureProtocol.Tls1;
// start the TLS handshake
Connection.ChangeSecurityProtocol(options);
// after this line, we're using an encrypted TLS connection
}
// from here on, act as if the SecureSocket is a normal Socket
Send("MAIL FROM: [email protected]\r\n"); // [email protected] is not a real email address
if (!IsReplyOK(Receive()))
{
Console.WriteLine("MAIL FROM failed.");
return;
}
Send("RCPT TO:" + address + "\r\n");
if (!IsReplyOK(Receive()))
{
Console.WriteLine("RCPT TO failed.");
return;
}
Send("DATA\r\n");
if (!IsReplyOK(Receive()))
{
Console.WriteLine("DATA failed.");
return;
}
Send(TestMail.Replace("#ADDRESS#", address) + "\r\n.\r\n");
if (!IsReplyOK(Receive()))
{
Console.WriteLine("Sending of e-mail failed.");
return;
}
Send("QUIT\r\n");
if (!IsReplyOK(Receive()))
{
Console.WriteLine("QUIT failed.");
}
Connection.Shutdown(SocketShutdown.Both);
} catch (Exception e) {
Console.WriteLine("An error occurred [" + e.Message + "]");
Console.WriteLine(e);
} finally {
if (Connection != null)
{
Connection.Close();
}
}
}
private void StartTLS()
{
SendAndWaitResponse("STARTTLS");
options.Protocol = SecureProtocol.Tls1;
connection.ChangeSecurityProtocol(options);
}
