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package RT::Interface::Email::Auth::GnuPG;

use strict;
use warnings;

=head2 GetCurrentUser

To use the gnupg-secured mail gateway, you need to do the following:

Set up a GnuPG key directory with a pubring containing only the keys
you care about and specify the following in your SiteConfig.pm

    Set(%GnuPGOptions, homedir => '/opt/rt4/var/data/GnuPG');
    Set(@MailPlugins, 'Auth::MailFrom', 'Auth::GnuPG', ...other filter...);

=cut

sub ApplyBeforeDecode { return 1 }

use RT::Crypt::GnuPG;
use RT::EmailParser ();

sub GetCurrentUser {
    my %args = (
        Message       => undef,
        RawMessageRef => undef,
        @_
    );

    foreach my $p ( $args{'Message'}->parts_DFS ) {
        $p->head->delete($_) for qw(
            X-RT-GnuPG-Status X-RT-Incoming-Encryption
            X-RT-Incoming-Signature X-RT-Privacy
            X-RT-Sign X-RT-Encrypt
        );
    }

    my $msg = $args{'Message'}->dup;

    my ($status, @res) = VerifyDecrypt(
        Entity => $args{'Message'}, AddStatus => 1,
    );
    if ( $status && !@res ) {
        $args{'Message'}->head->replace(
            'X-RT-Incoming-Encryption' => 'Not encrypted'
        );

        return 1;
    }

    # FIXME: Check if the message is encrypted to the address of
    # _this_ queue. send rejecting mail otherwise.

    unless ( $status ) {
        $RT::Logger->error("Had a problem during decrypting and verifying");
        my $reject = HandleErrors( Message => $args{'Message'}, Result => \@res );
        return (0, 'rejected because of problems during decrypting and verifying')
            if $reject;
    }

    # attach the original encrypted message
    $args{'Message'}->attach(
        Type        => 'application/x-rt-original-message',
        Disposition => 'inline',
        Data        => ${ $args{'RawMessageRef'} },
    );

    $args{'Message'}->head->replace( 'X-RT-Privacy' => 'PGP' );

    foreach my $part ( $args{'Message'}->parts_DFS ) {
        my $decrypted;

        my $status = $part->head->get( 'X-RT-GnuPG-Status' );
        if ( $status ) {
            for ( RT::Crypt::GnuPG::ParseStatus( $status ) ) {
                if ( $_->{Operation} eq 'Decrypt' && $_->{Status} eq 'DONE' ) {
                    $decrypted = 1;
                }
                if ( $_->{Operation} eq 'Verify' && $_->{Status} eq 'DONE' ) {
                    $part->head->replace(
                        'X-RT-Incoming-Signature' => $_->{UserString}
                    );
                }
            }
        }

        $part->head->replace(
            'X-RT-Incoming-Encryption' => 
                $decrypted ? 'Success' : 'Not encrypted'
        );
    }

    return 1;
}

sub HandleErrors {
    my %args = (
        Message => undef,
        Result => [],
        @_
    );

    my $reject = 0;

    my %sent_once = ();
    foreach my $run ( @{ $args{'Result'} } ) {
        my @status = RT::Crypt::GnuPG::ParseStatus( $run->{'status'} );
        unless ( $sent_once{'NoPrivateKey'} ) {
            unless ( CheckNoPrivateKey( Message => $args{'Message'}, Status => \@status ) ) {
                $sent_once{'NoPrivateKey'}++;
                $reject = 1 if RT->Config->Get('GnuPG')->{'RejectOnMissingPrivateKey'};
            }
        }
        unless ( $sent_once{'BadData'} ) {
            unless ( CheckBadData( Message => $args{'Message'}, Status => \@status ) ) {
                $sent_once{'BadData'}++;
                $reject = 1 if RT->Config->Get('GnuPG')->{'RejectOnBadData'};
            }
        }
    }
    return $reject;
}

sub CheckNoPrivateKey {
    my %args = (Message => undef, Status => [], @_ );
    my @status = @{ $args{'Status'} };

    my @decrypts = grep $_->{'Operation'} eq 'Decrypt', @status;
    return 1 unless @decrypts;
    foreach my $action ( @decrypts ) {
        # if at least one secrete key exist then it's another error
        return 1 if
            grep !$_->{'User'}{'SecretKeyMissing'},
                @{ $action->{'EncryptedTo'} };
    }

    $RT::Logger->error("Couldn't decrypt a message: have no private key");

    my $address = (RT::Interface::Email::ParseSenderAddressFromHead( $args{'Message'}->head ))[0];
    my ($status) = RT::Interface::Email::SendEmailUsingTemplate(
        To        => $address,
        Template  => 'Error: no private key',
        Arguments => {
            Message   => $args{'Message'},
            TicketObj => $args{'Ticket'},
        },
        InReplyTo => $args{'Message'},
    );
    unless ( $status ) {
        $RT::Logger->error("Couldn't send 'Error: no private key'");
    }
    return 0;
}

sub CheckBadData {
    my %args = (Message => undef, Status => [], @_ );
    my @bad_data_messages = 
        map $_->{'Message'},
        grep $_->{'Status'} ne 'DONE' && $_->{'Operation'} eq 'Data',
        @{ $args{'Status'} };
    return 1 unless @bad_data_messages;

    $RT::Logger->error("Couldn't process a message: ". join ', ', @bad_data_messages );

    my $address = (RT::Interface::Email::ParseSenderAddressFromHead( $args{'Message'}->head ))[0];
    my ($status) = RT::Interface::Email::SendEmailUsingTemplate(
        To        => $address,
        Template  => 'Error: bad GnuPG data',
        Arguments => {
            Messages  => [ @bad_data_messages ],
            TicketObj => $args{'Ticket'},
        },
        InReplyTo => $args{'Message'},
    );
    unless ( $status ) {
        $RT::Logger->error("Couldn't send 'Error: bad GnuPG data'");
    }
    return 0;
}

sub VerifyDecrypt {
    my %args = (
        Entity => undef,
        @_
    );

    my @res = RT::Crypt::GnuPG::VerifyDecrypt( %args );
    unless ( @res ) {
        $RT::Logger->debug("No more encrypted/signed parts");
        return 1;
    }

    $RT::Logger->debug('Found GnuPG protected parts');

    # return on any error
    if ( grep $_->{'exit_code'}, @res ) {
        $RT::Logger->debug("Error during verify/decrypt operation");
        return (0, @res);
    }

    # nesting
    my ($status, @nested) = VerifyDecrypt( %args );
    return $status, @res, @nested;
}

RT::Base->_ImportOverlays();

1;

