#!/usr/bin/env perl
use warnings;
use strict;
use Term::ReadKey; # For the noecho
use GnuPG::Tie::Encrypt;
use GnuPG::Tie::Decrypt;

# Global vars here
my $message_separator = "!"; # Separate messages on !, because gpg will put newlines into the message, but never uses '!' in ascii-armor
# End of global vars

client( $ARGV[0], $ARGV[1] ) if( @ARGV == 2 );
daemon( $ARGV[0] ) if( @ARGV == 1 );
usage() if( @ARGV != 1 && @ARGV != 2 );

sub usage
{
	print "Usage:\n";
	print "$0 <port_number> # For listening as a daemon\n";
	print "$0 <ip_address> <port_number> # For connecting to other servers\n";
}

sub client
{
	my $target = shift;
	my $port = shift;
	my $status = `nc -z $target $port` or die "Can't open data connection (port closed or host unreachable)";
	print "Who do I encrypt to: ";
	my $keyname = <STDIN>;
	chomp( $keyname );
	ReadMode('noecho');
	print "PGP Key passphrase (not echoed): ";
	my $passphrase = <STDIN>;
	chomp $passphrase;
	print "\n"; # The user's return key won't be echoed
	ReadMode(0); # Reset term status
	open (NET, "|-", "nc $target $port") or die "Can't open netcat: $!";
	while( 0 == 0 )
	{
		my $message = encrypt( $keyname, $passphrase );
		last if $message eq "exit";
		select(NET); # We select NET so $| will effect it
		$| = 1; # We can't buffer because of interactions with netcat.
		print $message . $message_separator; # Send it through the tubes!
	}
	close NET;
	select(STDOUT);
	print "Connection Terminated.\n";
}

sub encrypt
{
	select(STDOUT);
	my $keyname = shift;
	my $passphrase = shift;
	print "Message: ";
	my $message = <STDIN>;
	chomp( $message );
	return "exit" if( length($message) == 0 ); # Quit if blank message
	tie *ENCRYPT, 'GnuPG::Tie::Encrypt', recipient => $keyname, sign => 1, passphrase => $passphrase, armor => 1;
	print ENCRYPT $message;
	local $/ = undef; # Don't stop reading from ENCRYPT at a newline like normal
	my $encrypted_message = <ENCRYPT>;
	close ENCRYPT;
	untie *ENCRYPT;
	return $encrypted_message;
}

sub daemon # Listen for incomming connections
{
	my $port = shift or die "Usage: $0 <port_number>";
	ReadMode('noecho');
	print "PGP Key passphrase (not echoed): ";
	my $passphrase = <STDIN>;
	chomp $passphrase;
	print "\n"; # The user's return key won't be echoed
	ReadMode(0); # Reset term status
	print( msg_time(), " Server started.\n");
	open (NET, "-|", "nc -k -l $port" ) or die "Can't open netcat!";
	local $/ = $message_separator; # Seperate off chosen symbol instead of newline
	while( <NET> )
	{
		my $plaintext = decrypt($passphrase, $_);
		print( msg_time(), " ", $plaintext);
	}
	close NET; 
}

sub msg_time
{
	my( $hours, $minutes, $seconds ) = (localtime)[2,1,0];
	return "$hours:$minutes:$seconds";
}

sub decrypt
{
	my $passphrase = shift;
	my $message = shift;
	tie *DECRYPT, 'GnuPG::Tie::Decrypt', passphrase => $passphrase;
	print DECRYPT $message; # Here's where I error out
	my $plaintext_message = <DECRYPT>;
	close DECRYPT;
	untie *DECRYPT;
	return $plaintext_message;
}