#!/usr/bin/perl

package DNS;

use strict;
use warnings;
use OpenBSD::Pledge;
use OpenBSD::Unveil;
use Data::Dumper;
use File::Copy qw(copy);

my %conf = %main::conf;
my $chans = $conf{chans};
my $staff = $conf{staff};
my $key = $conf{key};
my $hash = $conf{hash};
my $hostname = $conf{hostname};
my $verbose = $conf{verbose};
my $ip4 = $conf{ip4};
my $ip6 = $conf{ip6};
my $ip6subnet = $conf{ip6subnet};
my $zonedir = $conf{zonedir};
my $hostnameif = $conf{hostnameif};
if (host($hostname) =~ /(\d+\.){3,}\d+/) {
	$ip4 = $&;
}
main::cbind("msg", "-", "setrdns", \&msetrdns);
main::cbind("msg", "-", "delrdns", \&mdelrdns);
main::cbind("msg", "-", "setdns", \&msetdns);
main::cbind("msg", "-", "deldns", \&mdeldns);
main::cbind("msg", "-", "host", \&mhost);
main::cbind("msg", "-", "nextdns", \&mnextdns);
main::cbind("msg", "-", "readip6s", \&mreadip6s);

sub init {
	unveil("$zonedir", "rwc") or die "Unable to unveil $!";
	unveil("/usr/bin/doas", "rx") or die "Unable to unveil $!";
	unveil("/usr/bin/host", "rx") or die "Unable to unveil $!";
	unveil("$hostnameif", "rwc") or die "Unable to unveil $!";
}

# !setrdns 2001:bd8:: username.example.com
sub msetrdns {
	my ($bot, $nick, $host, $hand, $text) = @_;
	if (! (main::isstaff($bot, $nick))) { return; }
	if ($text =~ /^([0-9A-Fa-f:\.]{3,})\s+([-0-9A-Za-z\.]+)$/) {
		my ($ip, $hostname) = ($1, $2);
		if (setrdns($ip, $ip6subnet, $hostname)) {
			main::putserv($bot, "PRIVMSG $nick :$hostname set to $ip");
		} else {
			main::putserv($bot, "PRIVMSG $nick :ERROR: failed to set rDNS");
		}
	}
}

# !delrdns 2001:bd8::
sub mdelrdns {
	my ($bot, $nick, $host, $hand, $text) = @_;
	if (! (main::isstaff($bot, $nick))) { return; }
	if ($text =~ /^([0-9A-Fa-f:\.]{3,})$/) {
		my ($ip) = ($1);
		if (delrdns($ip, $ip6subnet)) {
			main::putserv($bot, "PRIVMSG $nick :$ip rDNS deleted");
		} else {
			main::putserv($bot, "PRIVMSG $nick :ERROR: failed to set rDNS");
		}
	}
}
# !setdns username 1.2.3.4
sub msetdns {
	my ($bot, $nick, $host, $hand, $text) = @_;
	if (! (main::isstaff($bot, $nick))) { return; }
	if ($text =~ /^([-0-9A-Za-z\.]+)\s+([0-9A-Fa-f:\.]+)/) {
		my ($name, $value) = ($1, $2);
		if ($value =~ /:/ and setdns($name, $hostname, "AAAA", $value)) {
			main::putserv($bot, "PRIVMSG $nick :$name.$hostname AAAA set to $value");
		} elsif (setdns($name, $hostname, "A", $value)) {
			main::putserv($bot, "PRIVMSG $nick :$name.$hostname A set to $value");
		} else {
			main::putserv($bot, "PRIVMSG $nick :ERROR: failed to set DNS");
		}
	}
}

# !deldns username
sub mdeldns {
	my ($bot, $nick, $host, $hand, $text) = @_;
	if (! (main::isstaff($bot, $nick))) { return; }
	if ($text =~ /^([-0-9A-Za-z\.]+)$/) {
		my ($name) = ($1);
		if (setdns($name, $hostname)) {
			main::putserv($bot, "PRIVMSG $nick :$text deleted");
		} else {
			main::putserv($bot, "PRIVMSG $nick :ERROR: failed to delete DNS records");
		}
	}
}

# !host username
sub mhost {
	my ($bot, $nick, $host, $hand, $text) = @_;
	if (! (main::isstaff($bot, $nick))) { return; }
	if ($text =~ /^([-0-9A-Za-z:\.]{3,})/) {
		my ($hostname) = ($1);
		main::putserv($bot, "PRIVMSG $nick :".host($hostname));
	}
}

# !nextdns username
sub mnextdns {
	my ($bot, $nick, $host, $hand, $text) = @_;
	if (! (main::isstaff($bot, $nick))) { return; }
	if ($text =~ /^([-0-9a-zA-Z]+)/) {
		main::putserv($bot, "PRIVMSG $nick :$text set to ".nextdns($text));
	}
}

# !readip6s
sub mreadip6s {
	my ($bot, $nick, $host, $hand, $text) = @_;
	if (! (main::isstaff($bot, $nick))) { return; }
	foreach my $line (readip6s($hostnameif)) {
		print "$line\n"
	}
}

# Return list of ipv6 addresses from filename
sub readip6s {
	my ($filename) = @_;
	my @lines = main::readarray($filename);
	my @ipv6s;
	foreach my $line (@lines) {
		if ($line =~ /^\s*inet6\s+(alias\s+)?([0-9a-f:]{4,})\s+[0-9]+\s*$/i) {
			push(@ipv6s, $2);
		} elsif ($line =~ /^\s*([0-9a-f:]{4,})\s*$/i) {
			push(@ipv6s, $1);
		}
	}
	return @ipv6s;
}

# set rdns of $ip6 to $hostname given $subnet
# return true on success; false on failure
sub setrdns {
	my ($ip6, $subnet, $hostname) = @_;
	my $digits = ip6full($ip6);
	$digits =~ tr/://d;
	my $reversed = reverse($digits);
	my $origin = substr($reversed, 32-$subnet/4);
	$origin = join('.', split(//, $origin)).".ip6.arpa";
	my $name = substr($reversed, 0, 32-$subnet/4);
	$name = join('.', split(//, $name));
	# delete old PTR records, then set new one
	return setdns($name, $origin) && setdns($name, $origin, "PTR", $hostname);
}
# delete rdns of $ip6 given $subnet
# return true on success; false on failure
sub delrdns {
	my ($ip6, $subnet) = @_;
	return setrdns($ip6, $subnet);
}

# given $origin. create $name RR of $type and set to $value if provided;
# if $value is missing, delete $domain
# returns true upon success, false upon failure
sub setdns {
	my ($name, $origin, $type, $value) = @_;
	my $filename = "$zonedir/$origin";
	my @lines = main::readarray($filename);
	foreach my $line (@lines) {
		# increment the zone's serial number
		if ($line =~ /(\d{8})(\d{2})((\s+\d+){4}\s*\))/) {
			my $date = main::date();
			my $serial = 0;
			if ($date <= $1) { $serial = $2+1; }
			$line = $`.$date.sprintf("%02d",$serial).$3.$';
		}
	}
	if (!defined($value)) { # delete records
		@lines = grep !/\b$name\s*3600\s*IN/, @lines;
	} else {
        	push(@lines, "$name	3600	IN	$type	$value");
	}
	# trailing newline necessary
	main::writefile("$filename.bak", join("\n", @lines)."\n");
	copy "$filename.bak", $filename;
	if (system("doas -u _nsd nsd-control reload")) {
		return 0;
	} else {
        	return 1;
	}
}

# given hostname, return IP addresses; or given IP address, return hostname
sub host {
	my ($name) = @_;
	my @matches;
	my @lines = split /\n/m, `host $name`;
	if ($name =~ /^[0-9\.]+$/ or $name =~ /:/) { # IP address
		foreach my $line (@lines) {
			if ($line =~ /([\d\.]+).(in-addr|ip6).arpa domain name pointer (.*)/) {
				push(@matches, $3);
			}
		}
	} else { # hostname
		foreach my $line (@lines) {
			if ($line =~ /$name has (IPv6 )?address ([0-9a-fA-F\.:]+)/) {
				push(@matches, $2);
			}
		}
	}
	return join(' ', @matches);
}

# Return an ipv6 address with all zeroes filled in
sub ip6full {
	my ($ip6) = @_;
	my $left = substr($ip6, 0, index($ip6, "::"));
	my $leftcolons = ($left =~ tr/://);
	$ip6 =~ s{::}{:};
	my @quartets = split(':', $ip6);
	my $length = scalar(@quartets);
	for (my $n = 1; $n <= 8 - $length; $n++) {
		splice(@quartets, $leftcolons+1, 0, "0000");
	}
	my @newquartets = map(sprintf('%04s', $_), @quartets);
	my $full = join(':',@newquartets);
	return $full;
}
# Returns the network part of the first IPv6 address (indicated by subnet)
# with the host part of the second IPv6 address
sub ip6mask {
        my ($ip6net, $subnet, $ip6host) = @_;
        my $netdigits = ip6full($ip6net);
        $netdigits =~ tr/://d;
        my $hostdigits = ip6full($ip6host);
        $hostdigits =~ tr/://d;
        my $digits = substr($netdigits,0,($subnet/4)).substr($hostdigits,($subnet/4));
        my $ip6;
        for (my $n = 0; $n < 32; $n++) {
                if ($n > 0 && $n % 4 == 0) {
                        $ip6 .= ":";
                }
                $ip6 .= substr($digits,$n,1);
        }
        return $ip6;
}
sub randip6 {
        return join ':', map { sprintf '%04x', rand 0x10000 } (1 .. 8);
}

# create A and AAAA records for subdomain, set the rDNS,
# and return the new ipv6 address
sub nextdns {
	my ($subdomain) = @_;
	my $newip6 = $ip6;
	my @allip6s = readip6s($hostnameif);
	while (grep(/$newip6/, @allip6s)) {
		$newip6 = ip6mask($ip6, $ip6subnet,randip6());
	}
	main::appendfile($hostnameif, "inet6 alias $newip6 48\n");
	`doas ifconfig vio0 inet6 $newip6/48`;
	if (setdns($subdomain, $hostname, "A", $ip4) && setdns($subdomain, $hostname, "AAAA", $newip6) && setrdns($newip6, $ip6subnet, "$subdomain.$hostname")) {
		return "$newip6";
	}
	return "false";
}

1; # MUST BE LAST STATEMENT IN FILE