/// <summary>
/// Sends the welcome greeting to the client.
/// </summary>
private void SendWelcomeMessage(SMTPContext context)
{
context.WriteLine(WelcomeMessage);
}
/// <summary>
/// Handles the command input from the client. This
/// message returns when the client issues the quit command.
/// </summary>
private void ProcessCommands(SMTPContext context)
{
bool isRunning = true;
// Loop until the client quits.
while (isRunning)
{
try
{
String inputLine = context.ReadLine();
if (inputLine == null)
{
isRunning = false;
context.Close();
continue;
}
Log.DebugFormat(Resources.Log_ProcessCommands_ProcessCommands_Read_0, inputLine);
String[] inputs = inputLine.Split(" ".ToCharArray());
var messageUnknownCommand = Resources.Protocol_MESSAGE_UNKNOWN_COMMAND_500_Command_Unrecognized;
switch (inputs[0].ToLower())
{
case "helo":
Helo(context, inputs);
break;
case "rset":
Rset(context);
break;
case "noop":
context.WriteLine(Resources.Protocol_MESSAGE_OK_250_OK);
break;
case "quit":
isRunning = false;
context.WriteLine(Resources.Protocol_MESSAGE_GOODBYE_221_Goodbye);
context.Close();
break;
case "mail":
if (inputs[1].ToLower().StartsWith("from"))
{
Mail(context, inputLine.Substring(inputLine.IndexOf(" ", StringComparison.Ordinal)));
break;
}
context.WriteLine(messageUnknownCommand);
break;
case "rcpt":
if (inputs[1].ToLower().StartsWith("to"))
{
Rcpt(context, inputLine.Substring(inputLine.IndexOf(" ", StringComparison.Ordinal)));
break;
}
context.WriteLine(messageUnknownCommand);
break;
case "data":
Data(context);
break;
default:
context.WriteLine(messageUnknownCommand);
break;
}
}
catch (Exception exception)
{
Log.ErrorFormat(
Resources.Log_ProcessCommands_Connection_0_Exception_occured_while_processing_commands_1,
context.ConnectionId, exception, exception);
context.WriteLine(Resources.Protocol_MESSAGE_SYSTEM_ERROR_554_Transaction_failed);
}
}
}
/// <summary>
/// Handle the RCPT TO:<address> command.
/// </summary>
private void Rcpt(SMTPContext context, string argument)
{
if (context.LastCommand == CommandMail || context.LastCommand == CommandRcpt)
{
string address = ParseAddress(argument);
var messageInvalidAddress = Resources.Protocol_MESSAGE_INVALID_ADDRESS_451_Address_is_invalid;
if (address != null)
{
try
{
var emailAddress = new MailAddress(address);
// Check to make sure we want to accept this message.
if (_recipientFilter.AcceptRecipient(context, emailAddress))
{
context.Message.AddToAddress(emailAddress);
context.LastCommand = CommandRcpt;
context.WriteLine(Resources.Protocol_MESSAGE_OK_250_OK);
if (Log.IsDebugEnabled)
Log.DebugFormat(Resources.Log_Connection_0_RcptTo_address_1_accepted,
context.ConnectionId, address);
}
else
{
context.WriteLine(Resources.Protocol_MESSAGE_UNKNOWN_USER_550_User_does_not_exist);
if (Log.IsDebugEnabled)
Log.DebugFormat(
Resources.Log_Connection_0_RcptTo_address_1_rejected_Did_not_pass_Address_Filter,
context.ConnectionId, address);
}
}
catch (FormatException)
{
if (Log.IsDebugEnabled)
Log.DebugFormat(
Resources.Log_Connection_0_RcptTo_argument_1_rejected_Should_be_from_username_domain_com,
context.ConnectionId, argument);
context.WriteLine(messageInvalidAddress);
}
}
else
{
if (Log.IsDebugEnabled)
Log.DebugFormat(
Resources.Log_Connection_0_RcptTo_argument_1_rejected_Should_be_from_username_domain_com,
context.ConnectionId, argument);
context.WriteLine(messageInvalidAddress);
}
}
else
{
context.WriteLine(Resources.Protocol_MESSAGE_INVALID_COMMAND_ORDER_503_Command_not_allowed_here);
}
}
/// <summary>
/// Handles the HELO command.
/// </summary>
private void Helo(SMTPContext context, IList<string> inputs)
{
if (context.LastCommand == -1)
{
if (inputs.Count == 2)
{
context.ClientDomain = inputs[1];
context.LastCommand = CommandHelo;
context.WriteLine(HeloResponse);
}
else
{
context.WriteLine(Resources.Protocol_MESSAGE_INVALID_ARGUMENT_COUNT__501_Incorrect_number_of_arguments);
}
}
else
{
context.WriteLine(Resources.Protocol_MESSAGE_INVALID_COMMAND_ORDER_503_Command_not_allowed_here);
}
}
private void Data(SMTPContext context)
{
context.WriteLine(Resources.Protocol_MESSAGE_START_DATA__354_Start_mail_input_end_with_CRLF_CRLF);
SMTPMessage message = context.Message;
var clientEndPoint = (IPEndPoint)context.Socket.RemoteEndPoint;
var header = new StringBuilder();
header.AppendFormat(Resources.EMAIL_Received_from_0_0_1, context.ClientDomain, clientEndPoint.Address);
header.AppendLine();
header.AppendFormat(Resources.EMAIL_by_0_Eric_Daugherty_s_C_Email_Server, _domain);
header.AppendLine();
header.Append(" " + DateTime.Now);
header.AppendLine();
message.AddData(header.ToString());
String line = context.ReadLine();
while (!line.Equals("."))
{
message.AddData(line);
message.AddData("\r\n");
line = context.ReadLine();
}
// Spool the message
_messageSpool.SpoolMessage(message);
context.WriteLine(Resources.Protocol_MESSAGE_OK_250_OK);
// Reset the connection.
context.Reset();
}
/// <summary>
/// Reset the connection state.
/// </summary>
private static void Rset(SMTPContext context)
{
if (context.LastCommand != -1)
{
// Dump the message and reset the context.
context.Reset();
context.WriteLine(Resources.Protocol_MESSAGE_OK_250_OK);
}
else
{
context.WriteLine(Resources.Protocol_MESSAGE_INVALID_COMMAND_ORDER_503_Command_not_allowed_here);
}
}
/// <summary>
/// Handle the MAIL FROM:<address> command.
/// </summary>
private static void Mail(SMTPContext context, string argument)
{
bool addressValid = false;
if (context.LastCommand == CommandHelo)
{
string address = ParseAddress(argument);
if (address != null)
{
try
{
var emailAddress = new MailAddress(address);
context.Message.FromAddress = emailAddress;
context.LastCommand = CommandMail;
addressValid = true;
context.WriteLine(Resources.Protocol_MESSAGE_OK_250_OK);
if (Log.IsDebugEnabled)
Log.DebugFormat(Resources.Log_Mail_Connection_0_MailFrom_address_1_accepted,
context.ConnectionId, address);
}
catch (FormatException ex)
{
Log.Warn(Resources.Log_Invalid_E_Mail_address_detected, ex);
}
catch (Exception ex)
{
Log.Error(Resources.Log_Unknown_exception_occured, ex);
}
}
// If the address is invalid, inform the client.
if (!addressValid)
{
if (Log.IsDebugEnabled)
Log.DebugFormat(
Resources.Log_Connection_0_MailFrom_argument_1_rejected_Should_be_from_username_domain_com,
context.ConnectionId, argument);
context.WriteLine(Resources.Protocol_MESSAGE_INVALID_ADDRESS_451_Address_is_invalid);
}
}
else
{
context.WriteLine(Resources.Protocol_MESSAGE_INVALID_COMMAND_ORDER_503_Command_not_allowed_here);
}
}
/// <summary>
/// ProcessConnection handles a connected TCP Client
/// and performs all necessary interaction with this
/// client to comply with RFC821. This method is thread
/// safe.
/// </summary>
public void ProcessConnection(Socket socket)
{
long currentConnectionId;
// Really only need to lock on the long, but that is not
// allowed. Is there a better way to do this?
lock (this)
{
currentConnectionId = _connectionId++;
}
using (SMTPContext context = new SMTPContext(currentConnectionId, socket))
{
try
{
SendWelcomeMessage(context);
ProcessCommands(context);
}
catch (Exception exception)
{
Log.ErrorFormat(
Resources.Log_ProcessConnection_Connection_0_Error_1,
context.ConnectionId,
exception);
}
}
}