#!/usr/bin/perl
# SMTPman - the MANual SMTP server
# Ryan Doyle 2009

use Term::ANSIColor qw(:constants);
use IO::Socket;
use Switch;

my $tcp_port = '2500';

if($ARGV[0] eq "-h" or $ARGV[0] eq "--help"){
  print "Usage: smtpman.pl\n\n";
  print "Change the port by editing smtpman.pl. Default is 2500\n\n";
  print "smtpman is a MANual SMTP server. That's right, you will need to manually\n";
  print "enter in the SMTP commands to receive email. A fantastic  advantage of\n";
  print "running a manual mail server is the 100% effectiveness against spam. NO\n";
  print "filtering software can successfully claim that it is 100% effective. Now\n";
  print "all the postmaster has to do is sit infront of a terminal window and accept\n";
  print "email on behalf of its users\n\n";
  print "ryandoyle.net - 2009\n\n";
  exit;
}

print "\n\tsmtpman - The MANual SMTP Server v0.1\n";
print "\t        ryandoyle.net - 2009\n\n";


print "Opening socket...\n";

# Create new socket
my $sock = new IO::Socket::INET (
				LocalPort => $tcp_port,
				Proto => 'tcp',
				Listen => 1,
				Reuse => 1
				);
# Check socket was created
if(!$sock){
print "ERROR Creating socket!!";
die();
}
# Let user know new socket was created
print "Socket created. Listening for new SMTP connections on port $tcp_port\n\n";

print "At any time if you want to end the connection, send a 5XX error\n";
print "(part of SMTP) such as 554 to gracefully end the SMTP conversation\n";
print "or send KILL (smtpman specific) to sever the TCP connection\n\n\n";
# Accept new connections
while($new_sock = $sock->accept()){

		
  print BLINK, "***A new client has connected!***\n\n", RESET;
  print BLUE, "  Send a greeting banner. This needs to be atleast 220 \n  and should also include the host name\n", RESET;
  print BLUE, "  EG: \"220 mail.example.com\"\n\n", RESET;
  print GREEN, "smtp> ", RESET;
  $greeting = <>;
  $new_sock->send($greeting);
  # Now we need to loop until we end the conversation
  while(defined($cmd = <$new_sock>)){
    # If the client is sending data, then we don't want to process commands
    if($dataactive != 1){
      # Print out the client's command 
      print RED, "\n\n".$cmd."\n", RESET;

      switch($cmd){
        case(m/DATA/i) {
          print BLUE, "  Client wants to send data, send a 354\n", RESET;
	  print BLUE, "  EG: \"354 go ahead, end with . on a new line\"\n\n";
	  # Now that the client is sending data, let the program know
          $dataactive = 1;
	}
        case(m/HELO/i){
	  print BLUE, "  Client is saying hello, check to make sure this greeting is correct\n";
	  print BLUE, "  and that you want to accept mail using a 250 command\n", RESET;
	  print BLUE, "  EG: \"250 Hello outmail.example.net, hows it going??\"\n\n", RESET;
        }
        case(m/EHLO/i){
	  print BLUE, "  Client is sending a EHLO (simmilar to a HELO). If you want to accept\n";
          print BLUE, "  its mail, send a 250 command\n", RESET;
          print BLUE, "  EG: \"250 Hello outmail.example.net, hows it going??\"\n\n", RESET;
        }
	case(m/MAIL/i){
	  print BLUE, "  Client wants to send an email from the address listed above. Make sure\n";
	  print BLUE, "  that this email address is allowed to send email to your organisation\n";
	  print BLUE, "  and send a 250 back\n", RESET;
	  print BLUE, "  EG: \"250 bob\@example.net? got it.\"\n\n";
	}
	case(m/RCPT/i){
	  print BLUE, "  Client wants to send its email to the address listed above. Make sure\n";
	  print BLUE, "  that this address exists in your organisation and send a 250 if you want\n";
	  print BLUE, "  to receive it\n", RESET;
	  print BLUE, "  EG: \"250 alright got it. You can send to noni\@example.com\"\n\n", RESET;
	}
	case(m/RSET/i){
	  print BLUE, "  Client wants to reset the current SMTP conversation, send a 250 if its ok\n";
	  print BLUE, "  EG: \"250 forgetting about to and from address and clearing the email data\"\n\n", RESET;
	  $msgdata = 0;
	}
	case(m/NOOP/i){
	  print BLUE, "  Client is sending a NOOP, no operation. Send a 250 back to confirm\n";
	  print BLUE, "  EG: \"250 stop wasting my time\"\n\n";
	}
	case(m/QUIT/i){
	  print BLUE, "  Client wants to quit the connection, send a 250 to confirm\n";
	  print BLUE, "  EG: \"250 ending connection now\"\n\n";
	}
	else{
	  print BLUE, "  The client is sending a command that smtpman does not know\n";
	  print BLUE, "  send a 500 command to terminate the connection\n\n", RESET;
	}
      }
      # Get our command and then send it back
      print GREEN, "smtp> ", RESET;
      $retcmd = <>;
      if($retcmd =~ /^KILL/i){
        print BLINK, "Closing socket!\n\n", RESET;
        close($new_sock);
	# Flush the message data
	$msgdata = 0;
      }
      else{
        $new_sock->send($retcmd);
      }
      # If the command was to quit, then close the socket and prompt to save the message
      if($cmd =~ m/QUIT/i){
	# Check if there was an email and give the option to save it if there was
	if($msgdata){
	  print BLUE, "  Do you want to save the data from the email? (y/n)\n\n", RESET;
	  print "Save? ";
	  $save = <>;
	  if($save =~ m/y/i){
	    $time = time;
	    open(MSG, ">$time.msg");
	    print MSG $msgdata;
	    close(MSG);
	    print "Message saved to $time.msg\n\n"
	  }
	  # Flush the message data
	  $msgdata = 0;
	}
	print BLINK, "*** Socket Closed ***!\n\n", RESET;
        close($new_sock);
	print "Waiting for new client...\n\n";
      }
    }
    # We are in the process of recieving data
    else{
      if($cmd =~ m/^\.\r\n/){
         $dataactive = 0;
	 print BLUE, "End of message, send a 250 to the client to confirm\n", RESET;
	 print BLUE, "EG: \"250 okay got the email\"\n\n";
	 print GREEN, "smtp> ", RESET;
         $retcmd = <>;
         $new_sock->send($retcmd);
      }
      else{
	print RED, $cmd, RESET;
        $msgdata = $msgdata.$cmd;
      }
    }
  }		
}