#!/usr/local/bin/perl

# Copyright Rainer Wichmann (2004)
#
# License Information:
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
#

use warnings;
use strict;
use Getopt::Long;
use File::Basename;
use File::Copy;
use File::stat;
use File::Temp qw/ tempfile tempdir unlink0 /;
use IO::Handle;
use Fcntl qw(:DEFAULT :flock);
use Tie::File;

# Do I/O to the data file in binary mode (so it 
# wouldn't complain about invalid UTF-8 characters).
use bytes;

File::Temp->safe_level( File::Temp::HIGH );

my %opts = ();
my $action;
my $file1;
my $file2;
my $passphrase;
my $secretkey;
my $return_from_sign = 0;
my $no_print_examine = 0;
my $no_remove_lock   = 0;
my $base = basename($0);

my $cfgfile  = "@myconffile@";
my $datafile = "@mydatafile@";
my $daemon   = "@sbindir@/@install_name@";
my $signify  = "@mysignify@";

my $SIGDIR   = "$ENV{'HOME'}/.signify";
my $KEYID    = "@install_name@";

$cfgfile  =~ s/^REQ_FROM_SERVER//;
$datafile =~ s/^REQ_FROM_SERVER//;

$signify = "signify-openbsd" if ($signify eq "");

sub usage() {
    print "Usage:\n";
    print "  $base { -m F | --create-cfgfile }    [options] [in.cfgfile]\n";
    print "    Sign the configuration file. If in.cfgfile is given, sign it\n";
    print "    and install it as configuration file.\n\n";

    print "  $base { -m f | --print-cfgfile }     [options] \n";
    print "    Print the configuration file to stdout. Signatures are removed.\n\n";

    print "  $base { -m D | --create-datafile }   [options] [in.datafile]\n";
    print "    Sign the database file. If in.datafile is given, sign it\n";
    print "    and install it as database file.\n\n";

    print "  $base { -m d | --print-datafile }    [options] \n";
    print "    Print the database file to stdout. Signatures are removed. Use\n";
    print "    option --list to list files in database rather than printing the raw file.\n\n";

    print "  $base { -m R | --remove-signature }  [options] file1 [file2 ...]\n";
    print "    Remove cleartext signature from input file(s). The file\n";
    print "    is replaced by the non-signed file.\n\n";

    print "  $base { -m E | --sign }              [options] file1 [file2 ...]\n";
    print "    Sign file(s) with a cleartext signature. The file\n";
    print "    is replaced by the signed file.\n\n";

    print "  $base { -m e | --examine }           [options] file1 [file2 ...]\n";
    print "    Report signature status of file(s).\n\n";

    print "  $base { -m G | --generate-keys }     [options] \n";
    print "    Generate a signify keypair to use for signing.\n\n";

    print "Options:\n";
    print "  -c cfgfile    --cfgfile cfgfile\n";
    print "    Select an alternate configuration file.\n\n";

    print "  -d datafile   --datafile datafile\n";
    print "    Select an alternate database file.\n\n";

    print "  -p passphrase --passphrase passphrase\n";
    print "    Set the passphrase for signify. By default, signify will ask.\n\n";

    print "  -s signify_dir --signify-dir signify_dir\n";
    print "    Select an alternate directory to locate the secret keyring.\n";
    print "    Will use '$ENV{'HOME'}/.signify/' by default.\n\n";

    print "  -k keyid      --keyid keyid\n";
    print "   Select the keyid to use for signing.\n\n";

    print "  -l            --list\n";
    print "    List the files in database rather than printing the raw file.\n\n";

    print "  -v            --verbose\n";
    print "    Verbose output.\n\n";
    return;
}

sub check_signify_uid () {
    if (0 != $>) {
	print "--------------------------------------------------\n";
	print "\n";
	print " You are not root. Please remember that samhain/yule\n";
	print " will use the public key of root to verify a signature.\n";
	print "\n";
	print "--------------------------------------------------\n";
    } else {
	if (!("@yulectl_prg@" =~ //)) {
	    print "--------------------------------------------------\n";
	    print "\n";
	    print " Please remember that yule will drop root after startup. Signature\n";
	    print " verification on SIGHUP will fail if you do not import the public key\n";
	    print " into the ~/.signify/ directory of the non-root yule user.\n";
	    print "\n";
	    print "--------------------------------------------------\n";
	}
    }
}
    
sub check_signify_sign () {
    if ( defined($secretkey)) {
        if ( (!-d "$secretkey")){
            print "--------------------------------------------------\n";
            print "\n";
            print " Secret key $secretkey not found!\n";
            print "\n";
            print " Please check the path/name of the alternate secret key.\n";
            print "\n";
            print "--------------------------------------------------\n";
            print "\n";
            exit;
        }
    } else {
        if ( (!-d "$SIGDIR") || (!-e "${SIGDIR}/${KEYID}.sec")) {
	    print "--------------------------------------------------\n";
	    print "\n";
	    if (!-d "$SIGDIR") {
	        print " Directory $SIGDIR not found!\n";
	    } else {
	        print " Secret key ${SIGDIR}/${KEYID}.sec not found!\n";
	    }
	    print "\n";
	    print " This indicates that you have never created a \n";
	    print " public/private keypair, and thus cannot sign.\n";
	    print " \n";
	    print " Please use $0 --generate-keys or\n";
	    print " $signify -G -s ${SIGDIR}/${KEYID}.sec -p ${SIGDIR}/${KEYID}.pub\n";
	    print " to generate a public/private keypair first.\n";
	    print "\n";
	    print "--------------------------------------------------\n";
	    print "\n";
	    exit;
        }
    }
}

sub check_signify_verify () {
    if ( (!-d "${SIGDIR}") || (!-e "${SIGDIR}/${KEYID}.pub")) {
	print "--------------------------------------------------\n";
	print "\n";
	if (!-d "$SIGDIR") {
	    print " Directory $SIGDIR not found!\n";
	} else {
	    print " Public key ${SIGDIR}/${KEYID}.pub not found!\n";
	}
	print "\n";
	print " This indicates that you have no public key\n";
	print " to verify signatures.\n";
	print " \n";
	print " Please copy the public key ${KEYID}.pub of\n";
	print " the user who is signing the configuration/database files\n";
	print " into the directory $SIGDIR.\n";
	print "\n";
	print "--------------------------------------------------\n";
	print "\n";
	exit;
    }
}


sub generate () {
    my $command = "$signify -G -s ${SIGDIR}/${KEYID}.sec -p ${SIGDIR}/${KEYID}.pub";
    if (!-d "${SIGDIR}") {
	unless(mkdir "$SIGDIR", 0750) {
	    die "Creating directory $SIGDIR failed: $?";
	}
    }
    check_signify_uid();
    system ($command) == 0 
	or die "system $command failed: $?";
    exit;
}

sub examine () {
    my $iscfg = 0;
    my $have_fp  = 0;
    my $have_sig = 0;
    my $message = '';
    my $retval  = 9;
    my $fh;
    my $filename;

    if (!($file1 =~ /^\-$/)) {
	die ("Cannot open $file1 for read: $!") unless ((-e $file1) && (-r _));
    }
    open FIN,  "<$file1" or die "Cannot open $file1 for read: $!";

    my $dir = tempdir( CLEANUP => 1 );
    $filename = $dir . "/exa_jhfdbilw." . $$;
    open $fh, ">$filename" or die "Cannot open $filename";
    autoflush $fh 1;

    while (<FIN>) {
	print $fh $_;
	if ($_ =~ /^\s*\[Misc\]/) {
	    $iscfg = 1;
	}
    }
    if ($iscfg == 1) {
	$message .=  "File $file1 is a configuration file\n\n";
    } else {
	$message .=  "File $file1 is a database file\n\n";
    }


    my $command = "$signify -Vem /dev/null -p ${SIGDIR}/${KEYID}.pub ";
    $command .= "-x $filename ";
    if (defined($opts{'v'})) {
	$command .= "2>&1";
    } else {
	$command .= "2>/dev/null";
    }

    print STDOUT "Using: $command\n\n" if (defined($opts{'v'}));
    open  SIGIN, "$command |" or die "Cannot fork: $!";

    while (<SIGIN>) {
	chomp ($_);
	if ($_ =~ /^Signature Verified$/) {
	    $message .= "GOOD signature with key: ${SIGDIR}/${KEYID}.pub\n";
	    $have_sig = 1;
	    $retval   = 0;
	}
	print STDOUT $_ if (defined($opts{'v'}));
    }
    close (SIGIN);
    print STDOUT "\n" if (defined($opts{'v'}));
    if ($have_sig == 0) {
	$message .=  "NO valid signature found\n";
    }
    close (FIN);
    if ($no_print_examine == 0) {
	print STDOUT $message;
    }
    unlink0( $fh, $filename ) or die "Cannot unlink $filename safely";
    return $retval;
}

sub wstrip ($) {
    $_ = shift;
    $_ =~ s/\s+//g;
    return $_;
}

sub remove () {
    my $bodystart = 1;
    my $sigstart  = 0;
    my $sigend    = 0;
    my $filename  = "";
    my $fh;
    my $stats;

    open FH, "<$file1" or die "Cannot open file $file1 for read: $!";
    if (!($file1 =~ /^\-$/)) {
	flock(FH, LOCK_EX) unless ($no_remove_lock == 1);
	my $dir = tempdir( CLEANUP => 1 ) or die "Tempdir failed";
	$filename = $dir . "/rem_iqegBCQb." . $$;
	open $fh, ">$filename" or die "Cannot open $filename";
	$stats = stat($file1);
    } else {
	open $fh, ">$file1" or die "Cannot open file $file1 for write: $!";
    }
    autoflush $fh 1;
    while (<FH>) {
	if ($_ =~ /^untrusted comment: /) {
	    $sigstart = 1;
	    $bodystart = 0;
	    next;
	} elsif (($sigstart == 1) && (wstrip($_) =~ m{^(?: [A-Za-z0-9+/]{4} )*(?:[A-Za-z0-9+/]{2} [AEIMQUYcgkosw048]=|[A-Za-z0-9+/][AQgw]==)?$}xm )) {
	    $sigstart = 0;
	    $bodystart = 1;
	    next;
	} elsif (($sigstart == 1) && ($bodystart == 0)) {
	    # comment NOT followed by signature
	    $sigstart = 0;
	    next;
	}

	if ($bodystart == 1) {
	    print $fh $_;
	}
    }
    if (!($file1 =~ /^\-$/)) {
	copy("$filename", "$file1") 
	    or die "Copy $filename to $file1 failed: $!";
	chmod $stats->mode, $file1;
	chown $stats->uid, $stats->gid, $file1;
	flock(FH, LOCK_UN) unless ($no_remove_lock == 1);
	close FH;
    }
    unlink0( $fh, $filename ) or die "Cannot unlink $filename safely";
    return;
}

sub print_cfgfile () {
    my $bodystart = 0;
    my $sigstart  = 0;

    if (!defined($file2)) {
	$file2 = '-';
    }

    open FH, "<$file1" or die "Cannot open file $file1 for read: $!";
    open FO, ">$file2" or die "Cannot open file $file2 for write: $!";
    while (<FH>) {
	if ($_ =~ /^untrusted comment: /) {
	    $sigstart = 1;
	    $bodystart = 0;
	    next;
	} elsif (($sigstart == 1) && (wstrip($_) =~ m{^(?: [A-Za-z0-9+/]{4} )*(?:[A-Za-z0-9+/]{2} [AEIMQUYcgkosw048]=|[A-Za-z0-9+/][AQgw]==)?$}xm )) {
	    $sigstart = 0;
	    $bodystart = 1;
	    next;
	} elsif (($sigstart == 1) && ($bodystart == 0)) {
	    # comment NOT followed by signature 
	    $sigstart = 0;
	    next;
	}
	if ($bodystart == 1) {
	    print FO $_;
	}
    }
    exit;
}

sub print_datafile () {
    die ("Cannot find program $daemon") 
	unless (-e $daemon);
    if (defined($opts{'v'})) {
	open FH, "$daemon --full-detail -d $datafile |" 
	    or die "Cannot open datafile $datafile for read: $!";
    } else {
	open FH, "$daemon -d $datafile |" 
	    or die "Cannot open datafile $datafile for read: $!";
    }
    while (<FH>) {
	print $_;
    }
    exit;
}

sub sign_file () {

    my $fileout = '';
    my $bodystart = 1;
    my $sigstart  = 0;
    my $sigend    = 0;
    my $stats;
    my $fh1;
    my $filename1;
    my $flag1     = 0;

    check_signify_uid();

    if (!defined($file2)) {
	$file2 = $file1;
    }

    if ($file1 =~ /^\-$/) {
	my $dir = tempdir( CLEANUP => 1 ) or die "Tempdir failed";
	$filename1 = $dir . "/sig_vs8827sd." . $$;
	open $fh1, ">$filename1" or die "Cannot open $filename1";
	$flag1 = 1;
	# my ($fh1, $filename1) = tempfile(UNLINK => 1);

	while (<STDIN>) {
	    if ($_ =~ /^untrusted comment: /) {
		$sigstart = 1;
		$bodystart = 0;
		next;
	    } elsif (($sigstart == 1) && (wstrip($_) =~ m{^(?: [A-Za-z0-9+/]{4} )*(?:[A-Za-z0-9+/]{2} [AEIMQUYcgkosw048]=|[A-Za-z0-9+/][AQgw]==)?$}xm )) {
		$sigstart = 0;
		$bodystart = 1;
		next;
	    } elsif (($sigstart == 1) && ($bodystart == 0)) {
		#comment NOT followed by signature 
		$sigstart = 0;
		next;
	    }

	    if ($bodystart == 1) {
		print $fh1 $_;
	    }
	}
	$file1 = $filename1;
	$fileout = '-';
    } else {
	open (LOCKFILE, "<$file1") or die "Cannot open $file1: $!";
	flock(LOCKFILE, LOCK_EX);
	$no_print_examine = 1;
	$no_remove_lock   = 1;
	if (examine() < 2) {
	    remove();
	}
	$fileout = $file1 . ".sig";
	$stats   = stat($file1)
	    or die "No file $file1: $!";
    }

    my $command = "$signify -Se ";
    $command .= "-s ${SIGDIR}/${KEYID}.sec ";
    $command .= "-x ${fileout} ";
    $command .= "-m $file1";

    if (defined($passphrase)) {
	local $SIG{PIPE} = 'IGNORE';
	open (FH, "|$command")  or die "can't fork: $!";
	print FH "$passphrase"  or die "can't write: $!";
	close FH                or die "can't close: status=$?";
    } else {
	system("$command") == 0 
	    or die "system $command failed: $?";
    }

    if (!($fileout =~ /^\-$/)) {
	my $st_old = stat($file1) 
	    or die "No file $file1: $!";
	my $st_new = stat($fileout) 
	    or die "No file $fileout: $!";
	die ("Signed file is smaller than unsigned file") 
	    unless ($st_new->size > $st_old->size);
	move("$fileout", "$file2") 
	    or die "Move $fileout to $file2 failed: $!";
	chmod $stats->mode, $file2;
	chown $stats->uid, $stats->gid, $file2;
	flock(LOCKFILE, LOCK_UN);
    }

    if ($flag1 == 1) {
	unlink0( $fh1, $filename1 ) or die "Cannot unlink $filename1 safely";
    }
    if ($return_from_sign == 1) {
	return;
    }
    exit;
}

Getopt::Long::Configure ("posix_default");
Getopt::Long::Configure ("bundling");
# Getopt::Long::Configure ("debug");

GetOptions (\%opts, 'm=s', 'h|help', 'v|verbose', 'l|list',
	    'c|cfgfile=s',
	    'd|datafile=s',
	    'p|passphrase=s',
	    's|secretkey=s',
            'k|keyid=s',
	    'create-cfgfile',  # -m F
	    'print-cfgfile',   # -m f
	    'create-datafile', # -m D
	    'print-datafile',  # -m d
	    'remove-signature',# -m R
	    'sign',            # -m E
	    'examine',         # -m e
	    'generate-keys');  # -m G

if (defined ($opts{'h'})) {
    usage();
    exit;
}

if (defined($opts{'k'})) {
    $KEYID = $opts{'k'};
}
if (defined($opts{'c'})) {
    $cfgfile = $opts{'c'};
}
if (defined($opts{'d'})) {
    $datafile = $opts{'d'};
}
if (defined($opts{'p'})) {
    $passphrase = $opts{'p'};
}
if (defined($opts{'s'})) {
    $SIGDIR = $opts{'s'};
}

if (defined ($opts{'m'}) && ($opts{'m'} =~ /[FfDdREeG]{1}/) ) {
    $action = $opts{'m'};
}
elsif (defined ($opts{'create-cfgfile'})) {
    $action = 'F';
}
elsif (defined ($opts{'print-cfgfile'})) {
    $action = 'f';
}
elsif (defined ($opts{'create-datafile'})) {
    $action = 'D';
}
elsif (defined ($opts{'print-datafile'})) {
    $action = 'd';
}
elsif (defined ($opts{'remove-signature'})) {
    $action = 'R';
}
elsif (defined ($opts{'sign'})) {
    $action = 'E';
}
elsif (defined ($opts{'examine'})) {
    $action = 'e';
}
elsif (defined ($opts{'generate-keys'})) {
    $action = 'G';
}
else {
    usage();
    die ("No valid action specified !");
}

if (defined($ARGV[0])) {
    $file1 = $ARGV[0];
} 
if (defined($ARGV[1])) {
    $file2 = $ARGV[1];
} 


if (($action =~ /[REe]{1}/) && !defined($file1)) {
    usage();
    die("Option -m $action requires a filename (or '-' for stdio)\n");
}

if ($action =~ /^F$/) {
    if (!defined($file1)) {
	$file1 = $cfgfile;
    }
    $file2 = $cfgfile;
    sign_file ();
}

if ($action =~ /^D$/) {
    if (!defined($file1)) {
	$file1 = $datafile;
    }
    $file2 = $datafile;
    sign_file ();
}

if ($action =~ /^R$/) {
    # $file1 defined
    my $i = 0;
    while (defined($ARGV[$i])) {
	$file1 = $ARGV[$i];
	remove ();
	++$i;
    }
}

if ($action =~ /^E$/) {
    # $file1 defined
    # default: $file2 = $file1
    check_signify_sign();
    my $i = 0;
    while (defined($ARGV[$i])) {
	$file1 = $ARGV[$i];
	$file2 = $file1;
	$return_from_sign = 1;
	sign_file ();
	++$i;
    }
}

if ($action =~ /^e$/) {
    # $file1 defined
    # default: $file2 = stdout
    check_signify_verify();
    my $i = 0;
    my $ret = 0;
    while (defined($ARGV[$i])) {
	print "\n";
	$file1 = $ARGV[$i];
	$ret += examine ();
	++$i;
	print "\n--------------------------------\n" if (defined($ARGV[$i]));
    }
    exit($ret);
}

if ($action =~ /^f$/) {
    $file1 = $cfgfile;
    $file2 = "-";
    print_cfgfile ();
}

if ($action =~ /^d$/) {
    # $file1 irrelevant
    if (defined($opts{'l'})) {
	print_datafile ();
    } else {
	$file1 = $datafile;
	$file2 = "-";
	print_cfgfile ();
    }
}