Core Update 139: fix syntax of generated Suricata DNS server file

  The YAML syntax of /var/ipfire/suricata/suricata-dns-servers.yaml was
invalid and caused Suricata to crash after upgrading to Core Update 139.

Due to strange NFQUEUE behaviour, this caused IPsec traffic to be
emitted to the internet directly. While this patch represents a quick
solution for Core Update 139, another one is needed for changing the
IPtables chain order to avoid similar information leaks in future.

Thanks to Michael for his debugging effort.

Fixes #12260
Partially fixes #12257

Cc: Michael Tremer <michael.tremer@ipfire.org>
Cc: Stefan Schantl <stefan.schantl@ipfire.org>
Signed-off-by: Peter Müller <peter.mueller@ipfire.org>
---
 config/cfgroot/ids-functions.pl | 51 +++++++++++++++++++++--------------------
 1 file changed, 26 insertions(+), 25 deletions(-)
  

Looks good for me.

Reviewed-by: Stefan Schantl <stefan.schantl@ipfire.org>
> The YAML syntax of /var/ipfire/suricata/suricata-dns-servers.yaml was
> invalid and caused Suricata to crash after upgrading to Core Update
> 139.
> 
> Due to strange NFQUEUE behaviour, this caused IPsec traffic to be
> emitted to the internet directly. While this patch represents a quick
> solution for Core Update 139, another one is needed for changing the
> IPtables chain order to avoid similar information leaks in future.
> 
> Thanks to Michael for his debugging effort.
> 
> Fixes #12260
> Partially fixes #12257
> 
> Cc: Michael Tremer <michael.tremer@ipfire.org>
> Cc: Stefan Schantl <stefan.schantl@ipfire.org>
> Signed-off-by: Peter Müller <peter.mueller@ipfire.org>
> ---
>  config/cfgroot/ids-functions.pl | 51 +++++++++++++++++++++--------
> ------------
>  1 file changed, 26 insertions(+), 25 deletions(-)
> 
> diff --git a/config/cfgroot/ids-functions.pl b/config/cfgroot/ids-
> functions.pl
> index 54d86f70f..89ad90c2e 100644
> --- a/config/cfgroot/ids-functions.pl
> +++ b/config/cfgroot/ids-functions.pl
> @@ -17,7 +17,7 @@
>  # along with IPFire; if not, write to the Free
> Software                    #
>  # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-
> 1307 USA #
>  #                                                                   
>        #
> -# Copyright (C) 2018 IPFire Team <info@ipfire.org>.                 
>        #
> +# Copyright (C) 2018-2019 IPFire Team <info@ipfire.org>             
>        #
>  #                                                                   
>        #
>  ####################################################################
> ########
>  
> @@ -706,7 +706,7 @@ sub generate_dns_servers_file() {
>  	open (FILE, "${General::swroot}/red/dns") or die "Could not
> read DNS configuration from ${General::swroot}/red/dns. $!\n";
>  
>  	# Read-in whole file content and store it in a temporary array.
> -	my @file_content = <FILE>;
> +	my @file_content = split(' ', <FILE>);
>  
>  	# Close file handle.
>  	close(FILE);
> @@ -714,31 +714,32 @@ sub generate_dns_servers_file() {
>  	# Format dns servers declaration.
>  	my $line = "\"\[";
>  
> -	# Loop through the array which contains the file content.
> -	foreach my $server (@file_content) {
> -		# Remove newlines.
> -		chomp($server);
> -
> -		# Check if the current DNS configuration is using the
> local recursor mode.
> -		if ($server eq "local recursor") {
> -			# The responsible DNS servers on red are
> directly used, and because we are not able
> -			# to specify each single DNS server address
> here, we currently have to thread each
> -			# address which is not part of the HOME_NET as
> possible DNS server.
> -			$line = "$line" . "!\$HOME_NET";
> -		} else {
> +	# Check if the current DNS configuration is using the local
> recursor mode.
> +	if ($file_content[0] eq "local" && $file_content[1] eq
> "recursor") {
> +		# The responsible DNS servers on red are directly used,
> and because we are not able
> +		# to specify each single DNS server address here, we
> currently have to thread each
> +		# address which is not part of the HOME_NET as possible
> DNS server.
> +		$line = "$line" . "!\$HOME_NET";
> +
> +	} else {
> +		# Loop through the array which contains the file
> content.
> +		foreach my $server (@file_content) {
> +			# Remove newlines.
> +			chomp($server);
> +
>  			# Add the DNS server to the line.
>  			$line = "$line" . "$server";
> +
> +			# Check if the current DNS server was the last
> in the array.
> +			if ($server ne $file_content[-1]) {
> +				# Add "," for the next DNS server.
> +				$line = "$line" . "\,";
> +			}
>  		}
> +	}
>  
> -                # Check if the current DNS server was the last in
> the array.
> -                if ($server eq $file_content[-1]) {
> -                        # Close the line.
> -                        $line = "$line" . "\]\"";
> -                } else {
> -                        # Add "," for the next DNS server.
> -                        $line = "$line" . "\,";
> -                }
> -        }
> +	# Close the line...
> +	$line = "$line" . "\]\"";
>  
>  	# Open file to store the used DNS server addresses.
>  	open(FILE, ">$dns_servers_file") or die "Could not open
> $dns_servers_file. $!\n";
> @@ -866,7 +867,7 @@ sub get_suricata_version($) {
>  	# Remove newlines.
>          chomp($version_string);
>  
> -	# Grab the version from the version string. 
> +	# Grab the version from the version string.
>  	$version_string =~ /([0-9]+([.][0-9]+)+)/;
>  
>  	# Splitt the version into single chunks.
> @@ -882,7 +883,7 @@ sub get_suricata_version($) {
>  	} else {
>  		# Return the full version string.
>  		return "$major_ver.$minor_ver.$patchlevel";
> -	} 
> +	}
>  }
>  
>  #