#!/usr/local/cpanel/3rdparty/bin/perl

# cpanel - scripts/fixrndc                         Copyright 2022 cPanel, L.L.C.
#                                                           All rights reserved.
# copyright@cpanel.net                                         http://cpanel.net
# This code is subject to the cPanel license. Unauthorized copying is prohibited

######[ This script will rebuild the rndc.key and rndc.conf files unless ]######
######[ an existing, working config is found                             ]######

use strict;
use Cpanel::Config::LoadCpConf   ();
use Cpanel::StringFunc::Count    ();
use Cpanel::CommentKiller        ();
use Cpanel::SafetyBits           ();
use Cpanel::PwCache              ();
use Cpanel::SafeRun::Errors      ();
use Cpanel::SafeRun::Simple      ();
use Cpanel::FileUtils::TouchFile ();
use Cpanel::FindBin              ();

use Getopt::Long ();

umask 0022;

######[ declare globals ]##########################################################################

# default location of zone files used for rebuilding named.conf
my $def_basedir = '/var/named';

# default location of named.conf
my $def_namedconf = '/etc/named.conf';

my $needrndckey = 0;

my $options = {};

Getopt::Long::Configure("bundling");
Getopt::Long::GetOptions(
    'force|f'   => \$options->{force},
    'verbose|v' => \$options->{verbose},

    # If -s is passed as an arg, it's saying that fixrndc was started by rebuilddnsconfig and should not reinvoke its parent.
    'rebuilddnsconfig|s' => \$options->{rebuilddnsconfig},
    'html|h'             => \$options->{html},
);

# Verbose variable, if set to "1" actions are reported to STDOUT.
my $cpverbose                    = $options->{verbose}          || 0;
my $called_from_rebuilddnsconfig = $options->{rebuilddnsconfig} || 0;

if ( !-e $def_namedconf || -z _ ) {
    if ( !$called_from_rebuilddnsconfig ) {
        print "The named configuration file is missing, running /usr/local/cpanel/scripts/rebuilddnsconfig to repair it.\n" if $cpverbose;
        my $opts = $cpverbose ? '-fv' : '-f';
        exec( '/usr/local/cpanel/scripts/rebuilddnsconfig', $opts );
        exit 0;    #unreached
    }
    else {
        print "WARNING: $def_namedconf appears to be invalid but the problem could not be corrected automatically!\n";
        exit 1;
    }
}

my $local_nameserver_type = Cpanel::Config::LoadCpConf::loadcpconf_not_copy()->{'local_nameserver_type'};
if ( $local_nameserver_type ne 'bind' ) {
    print "$local_nameserver_type is configured as the local nameserver.  RNDC key is not in use.\n" if $cpverbose;
    exit;
}

require Cpanel::Services::Enabled;
unless ( Cpanel::Services::Enabled::is_enabled('dns') ) {
    print "Named is currently disabled.\n" if $cpverbose;
    exit;
}

require Cpanel::DNSLib;
my $dnslib = Cpanel::DNSLib->new( 'force' => ( $options->{'force'} ? 1 : 0 ) );

######[ try to ensure named is actually running, fixrndc will always fail if not.                           ]######
######[ try starting named, but always allow it to continue and try to force new keys even if we can't test ]######
######[ this all does basically the same thing, but gives a little more information about problem so techs  ]######
######[ can know where to start ]##################################################################################

my @html_args = $options->{html} ? ('--html') : ();

my $check_output = Cpanel::SafeRun::Errors::saferunallerrors( '/usr/local/cpanel/scripts/restartsrv_named', '--check', @html_args );
my $status_code  = $?;

# Try to restart
if ( $status_code != 0 ) {
    print "Named looks down but should be up.  Attempting restart...\n" if $cpverbose;
    $check_output = Cpanel::SafeRun::Errors::saferunallerrors( '/usr/local/cpanel/scripts/restartsrv_named', @html_args );
    print $check_output if $cpverbose;
    for ( 1 .. 10 ) {
        $check_output = Cpanel::SafeRun::Errors::saferunallerrors( '/usr/local/cpanel/scripts/restartsrv_named', '--check', @html_args );
        $status_code  = $?;
        last                                                   if $status_code == 0;
        print "Waiting 5 seconds for named to start ($_/10)\n" if $cpverbose;
        sleep(5);
    }
    if ( $status_code != 0 ) {
        print "Named could not be restarted, any obvious config errors should show up below this line. \n";
        my ( $ret_status, $status_info ) = $dnslib->checknamedconf($def_namedconf);
        my $found_error = 0;
        if ( $ret_status == 1 || $status_info =~ /rndc\.key/ ) {

            #  No error was detected, needs manual inspection
            my $rndckey_file  = $def_namedconf;
            my $rndcconf_file = $def_namedconf;
            $rndckey_file  =~ s/\/named\.conf$/\/rndc.key/;
            $rndcconf_file =~ s/\/named\.conf$/\/rndc.conf/;
            foreach my $key_loc_file ( $rndckey_file, $def_namedconf ) {
                if ( -s $key_loc_file == 0 ) {
                    print "Detected empty file at $key_loc_file \n";
                    $needrndckey = 1;
                    $found_error = 1;
                    last;
                }
                if ( open( my $keyf, '<', $key_loc_file ) ) {
                    while ( my $line = readline($keyf) ) {
                        if ( $line =~ m/secret\s+\"(.*)\"/i ) {
                            my $base64ok = is_base64($1);
                            if ( $base64ok != 1 ) {
                                print "There appears to be a problem with the base64 encoding of the rndckey in $key_loc_file .\n";
                                print "Will try to rebuild those files, \"connection refused\" errors are to be expected. \n";
                                $needrndckey = 1;
                                $found_error = 1;
                                last;
                            }
                        }
                    }
                    close($keyf);
                }
                else {
                    print "Could not open $key_loc_file : $! \n";
                    $needrndckey = 1;
                }
            }
            if ( $found_error != 1 ) {
                print "No critical problems found, will attempt to regenerate keys regardless.\n";
                $needrndckey = 1;
            }
        }
        elsif ( !$called_from_rebuilddnsconfig ) {
            print "The named configuration appears to have errors:\n\t$status_info\n\nRunning /usr/local/cpanel/scripts/rebuilddnsconfig to repair it..\n";

            # some config problem..  let's force a rebuild of named.conf and let it try again
            my $opts = $cpverbose ? '-fv' : '-f';
            exec( '/usr/local/cpanel/scripts/rebuilddnsconfig', $opts );
            exit 0;    # unreached
        }
        else {
            print "WARNING: $def_namedconf appears to contain errors which could not be corrected automatically!\n";
            print $status_info . "\n";
            print "Please correct these errors manually and rerun /usr/local/cpanel/scripts/fixrndc\n";
            exit 1;
        }
    }
}

######[ fix rndc info if needed ]##################################################################

# check if `rndc status` reports ok, fix if not or if -f flag is given to force it
if ( !defined( $options->{'force'} ) ) {
    if ($cpverbose) {
        print "Checking rndc by querying status\n";
    }

    # If "rndc status" does not report a failed connection, exit
    if ( $dnslib->checkrndc() ) {
        if ($cpverbose) {
            print '!' x 50 . "\n";
            print "rndc reported success. No changes will be made.\nUse the \"-f\" flag to force a check.\n";
            print '!' x 50 . "\n";
        }
        exit;
    }
}

my $removenamedconfkey      = 0;
my $neednamedconfcontrols   = 0;
my $removenamedconfcontrols = 0;

# rndc variables from rndc.conf
my ( $r_secret, $r_keyname );
my $rndcconf    = $dnslib->find_rndcconf();
my $namedconf   = $dnslib->{'namedconf'};
my $rndckeyfile = $dnslib->find_rndckey();
my $chrootdir   = $dnslib->{'data'}{'chrootdir'};
my $zonedir     = $dnslib->{'data'}{'zonefiledir'};
my $binduser    = $dnslib->{'data'}{'binduser'};
my $bindgrp     = $dnslib->{'data'}{'bindgroup'};
my $binduid     = ( Cpanel::PwCache::getpwnam_noshadow($binduser) )[2];
my $bindgid     = ( getgrnam($bindgrp) )[2];
$dnslib->{'data'}{'cpverbose'} = 1;

if ($zonedir) {
    if ( !-e $zonedir . '/named.ca' ) {
        system 'cp', '-fv', '/usr/local/cpanel/etc/named.ca', $zonedir . '/named.ca';
        Cpanel::SafetyBits::safe_chown( $binduser, $bindgrp, $zonedir . '/named.ca' );
        Cpanel::SafetyBits::safe_chmod( oct('0644'), $binduser, $zonedir . '/named.ca' );
    }
}

# rndc variables from named.conf
my $key      = 0;
my $controls = 0;
my ( $keykeyname, $keysecret, $inet, $allow, $controlskeyname, $rndc_include );
my ( $confstatus, $confresult ) = $dnslib->checknamedconf($namedconf);

######[ bail out if named.conf is currently fubar ]################################################

# Only bypass this check if there's only one error line and it matches the
# regex.
if ( !$confstatus && $confresult !~ /^.*rndc[.-]key.*$/ ) {
    print <<"EOM";

!! fixrndc requires a syntactically correct $namedconf.
!! No changes were made to $namedconf. Problem was:
!! $confresult

EOM
    exit();
}

######[ Make sure chroot directory is created ]####################################################

if ( $chrootdir ne '' ) {
    print "Setting up chroot environment in $chrootdir\n" if $cpverbose;
    $dnslib->setupbindchroot();
}

######[ Check rndc.conf for necessary settings ]###################################################

if ($rndckeyfile) {
    ( $r_secret, $r_keyname ) = $dnslib->loadrndckey();
    if (   $r_secret eq ''
        || $r_keyname eq '' ) {
        $needrndckey = 1;
    }
}
else {
    $needrndckey = 1;
}

#my $namedconf = $def_namedconf;

######[ Cannot proceed if named.conf is not located at this point ]################################

if ( !-e $namedconf ) {
    die "named.conf not found, exiting";
}

######[ Check in existing named.conf to rcs ]######################################################

print "Checking in $namedconf to rcs system\n" if $cpverbose;

######[ If rndc.key needs to be generated, remove settings from named.conf ]#######################

if ($needrndckey) {
    print "Need to create rndc.conf\n" if $cpverbose;

    ( $key, $keykeyname, $keysecret, $controls, $inet, $allow, $controlskeyname, $rndc_include ) = $dnslib->getrndcsettings($rndckeyfile);

    # include line may already exist
    $removenamedconfkey = 1 unless $rndc_include;

    # check for broken control section
    if ( $controlskeyname ne 'rndc-key' || $inet ne '127.0.0.1' || $allow ne 'localhost' ) {
        $removenamedconfcontrols = 1;
        $neednamedconfcontrols   = 1;
    }
}
else {

    # Make sure named.conf rndc settings match
    ( $key, $keykeyname, $keysecret, $controls, $inet, $allow, $controlskeyname, $rndc_include ) = $dnslib->getrndcsettings($rndckeyfile);

    if ( $keykeyname && $keysecret ) {

        # if keyname in rndc.conf does not match keyname in named.conf,
        # redo key clause in named.conf
        if ( $keykeyname ne $r_keyname || $keysecret ne $r_secret ) {
            $removenamedconfkey = 1;
        }
    }
    elsif ( !$rndc_include ) {
        $removenamedconfkey = 1;
    }

    # Controls section is needed by default
    if ( $controlskeyname ne $r_keyname ) {
        $removenamedconfcontrols = 1;
        $neednamedconfcontrols   = 1;
        if ( $controlskeyname eq '' ) {
            print "Controls section not found, adding ...\n" if $cpverbose;
        }
        else {
            print "Controls keyname does not match rndc.conf keyname\n" if $cpverbose;
        }
    }
}

######[ Create rndc.key if needed ]###############################################################

if ($needrndckey) {
    print "Creating rndc.conf\n";

    my $named = Cpanel::FindBin::findbin('named');
    unless ($named) {
        die "named not located on system, please check the Bind installation";
    }

    my $rndcconfgen = $dnslib->find_rndcconfgen();
    if ( $rndcconfgen eq '' ) {
        die "rndc-confgen not located on system, please check the Bind installation";
    }

    my @rndc_confgen_args = (
        '-a',
        '-c', $rndckeyfile,
        '-k', 'rndc-key',
        '-r', '/dev/urandom',
    );

    # Bind < 9.10 (CentOS 6) does not support alternate hashing functions for the rndc key.

    if ( Cpanel::SafeRun::Simple::saferun( $named, "-v" ) =~ /^BIND\s(\d+)\.(\d+)/ ) {
        if ( $1 >= 9 && $2 >= 10 ) {
            push @rndc_confgen_args, ( '-A', 'hmac-sha256' );
        }
    }

    Cpanel::SafeRun::Errors::saferunallerrors( $rndcconfgen, @rndc_confgen_args );
    Cpanel::SafetyBits::safe_chown( $binduser, $bindgrp, $rndckeyfile );
    Cpanel::SafetyBits::safe_chmod( oct('0660'), $binduser, $rndckeyfile );
    ( $r_secret, $r_keyname ) = $dnslib->loadrndckey();
}

######[ Remove rndc.conf if needed ]################################################################

unlink $rndcconf if length $rndcconf && -f $rndcconf;

if ( $removenamedconfkey || $neednamedconfcontrols || $removenamedconfcontrols ) {

    # open our tmp file to populate with rndc key controls and named.conf

    open( NDF, ">", $namedconf . '.fixrndc' );
    Cpanel::SafetyBits::safe_chown( $binduser, $bindgrp, "$namedconf.fixrndc" );

    if ($removenamedconfkey) {
        print "Including rndc key file to named.conf\n";
        print NDF "include \"$rndckeyfile\"\;\n";
    }

    if ($neednamedconfcontrols) {
        print "Adding controls clause\n";
        print NDF "\ncontrols {\n";
        print NDF "\tinet 127.0.0.1 allow { localhost; } keys { \"$r_keyname\"\; }\;\n";
        print NDF "}\;\n\n";
    }

######[ append entire named.conf to tmp file ]#####################################################

    open( my $cur_ndc, '<', $namedconf );
    my $in_removed_section = 0;
    my $numbrace           = 0;
    my $commentkiller      = Cpanel::CommentKiller->new;
    while ( readline($cur_ndc) ) {
        if ( $removenamedconfcontrols || $removenamedconfkey ) {

            # Remove broken controls or keys sections if necessary
            my $parsed = $commentkiller->parse($_) or next;

            if ($in_removed_section) {
                $numbrace += Cpanel::StringFunc::Count::get_curly_brace_count($parsed);
                if ( $numbrace <= 0 ) {
                    $in_removed_section = 0;
                }
                next;
            }
            elsif ( $numbrace == 0 && ( ( $removenamedconfcontrols && $parsed =~ /^\s*controls/ ) || ( $removenamedconfkey && $parsed =~ /^\s*key/ ) ) ) {
                $numbrace += Cpanel::StringFunc::Count::get_curly_brace_count($parsed);
                $in_removed_section = 1;
                next;
            }
            $numbrace += Cpanel::StringFunc::Count::get_curly_brace_count($parsed);
        }
        print NDF;
    }
    close($cur_ndc);
    close(NDF);

    if ( -e $namedconf . '.cache' ) {
        unlink( $namedconf . '.cache' );
        unlink( $namedconf . '.zonedir.cache' );
    }

######[ move the fixrndc tmp file into place now that it is complete (once verified as ok) ]#######

    ( $confstatus, $confresult ) = $dnslib->checknamedconf( $namedconf . '.fixrndc' );
    if ($confstatus) {
        rename( $namedconf . '.fixrndc', $namedconf ) || print "Failed to copy $namedconf . '.fixrndc' to $namedconf : $!\n";
    }
    else {
        print "New named.conf file does not pass syntax check.  Leaving old file in place.\n" if $cpverbose;
    }
}
######[ check rndc status again, restart named if needed ]#########################################

if ( $needrndckey || !$dnslib->checkrndc() ) {
    print "Restarting named\n";
    system( '/usr/local/cpanel/scripts/restartsrv_named', @html_args );

    my $ok;
    my $suspend = '/var/run/chkservd.suspend';
    my $exists  = -e $suspend;

    # Suspend chkservd temporarily in case this takes longer than 5 minutes so
    # we don't end up in a restart-restart loop.
    Cpanel::FileUtils::TouchFile::touchfile($suspend);
    for ( 1 .. 300 ) {
        sleep(2);
        $ok = $dnslib->checkrndc();
        last if $ok;
    }
    unlink $suspend unless $exists;
    if ( !$ok ) {
        print "/usr/local/cpanel/scripts/fixrndc failed to fix the rndc key (or named is otherwise broken), please investigate manually\n";
        exit 1;
    }
}
print "The rndc key has been fixed successfully!\n" if $cpverbose;
exit;

sub is_base64 {
    my $string = shift;

    # Bail out if string length isn't in mutiples of 4 ...
    return if length($string) % 4;

    # Or if the string contains any unpermitted characters ...
    return if $string !~ /^[=\+\/a-z0-9]+$/i;
    return 1;
}