package GPGWrapper;
use IPC::Open2;
use IO::File;
use POSIX qw(tmpnam);
use strict;

our @ISA            = qw(Exporter);
our @EXPORT         = qw(GPG_Encrypt GPG_Decrypt
                         GPG_Encrypt_Asym GPG_Decrypt_Asym);
our $VERSION        = 1.0;

# The regular encrypt methods are not in current use because they require me to write 
# the data out to a file.  This incurs a I/O penalty for no good reason.  
# The asymmetric methods do this too, but I only call those each once, 
# so I don't care about the penalty.
#
# Actually, there is a good reason: I am unable to pipe in the data stream to GPG (although
# I _can_ pipe in other things, like the passphrase).  Attempting to do so hangs the program
# indefinately.  Incidentally, none of GPG package on CPAN (GPG, GnuPG, and Crypt::GPG)
# solve this problem: GPG also hangs indefinately, GnuPG writes the data to IPC (which Windows lacks), and
# Crypt::GPG won't compile on Windows systems.

sub GPG_Encrypt($$)
{
    my $passphrase = shift;
    my $data = shift;
    my @result;
    
    $passphrase .= "\n" if $passphrase !~ /\n$/;
    my $hackname;
    my $fh;
    do { $hackname = tmpnam(); }
    until $fh = IO::File->new($hackname, O_RDWR | O_CREAT | O_EXCL);
    binmode($fh);
    print $fh $data;
    close $fh;
    
    if (eval { open2(*README, *WRITEME, "gpg --no-tty --passphrase-fd 0 --output - --symmetric $hackname"); }) {
        binmode(README);
        binmode(WRITEME);
        print WRITEME $passphrase;
        close WRITEME;
        @result = <README>;
        close README;
    }
    wait();
    unlink $hackname;
    return join("", @result);
}

sub GPG_Decrypt($$)
{
    my $passphrase = shift;
    my $data = shift;
    my @result;
    
    $passphrase .= "\n" if $passphrase !~ /\n$/;
    my $hackname;
    my $fh;
    do { $hackname = tmpnam(); }
    until $fh = IO::File->new($hackname, O_RDWR | O_CREAT | O_EXCL);
    binmode($fh);
    print $fh $data;
    close $fh;
    
    if (eval { open2(*README, *WRITEME, "gpg --no-tty --passphrase-fd 0 --output - --decrypt $hackname"); }) {
        binmode(README);
        binmode(WRITEME);
        print WRITEME $passphrase;
        close WRITEME;
        @result = <README>;
        close README;
    }
    wait();
    unlink $hackname;
    return join("", @result);
}

# Asymmetric encryption.  Used for the handshake.
sub GPG_Encrypt_Asym($$)
{
    my $user = shift;    # We will encrypt using this user's public key
    my $data = shift;
    my @result;
    my $hackname;
    my $fh;
    
    do { $hackname = tmpnam(); }
    until $fh = IO::File->new($hackname, O_RDWR | O_CREAT | O_EXCL);
    binmode($fh);
    print $fh $data;
    close $fh;
    open(README, "gpg --no-tty --quiet --output - --recipient \"$user\" --encrypt $hackname |") 
        || die "Error on asymmetric encryption with user $user: $!\n";
    binmode(README);
    @result = <README>;
    close README;
    unlink $hackname;
    return join("", @result);
}

sub GPG_Decrypt_Asym($)
{
    my $data = shift;
    my @result;
    my $hackname;
    my $fh;
    
    do { $hackname = tmpnam(); }
    until $fh = IO::File->new($hackname, O_RDWR | O_CREAT | O_EXCL);
    binmode($fh);
    print $fh $data;
    close $fh;
    open(README, "gpg --no-tty --quiet --output - --decrypt $hackname |")
        || die "Error on asymmetric decryption: $!\n";
    binmode(README);
    @result = <README>;
    close README;
    unlink $hackname;
    return join("", @result);
}

1;