ids-functions.pl: Introduce merge_classifications() function.

This function is used to merge the individual classification files
provided by the providers.

The result will be written to the classification.config which will be
used by the IDS.

Fixes #11884.

Signed-off-by: Stefan Schantl <stefan.schantl@ipfire.org>

config/cfgroot/ids-functions.pl

@@ -80,6 +80,9 @@ our $ids_page_lock_file = "/tmp/ids_page_locked";
 # Location where the rulefiles are stored.
 our $rulespath = "/var/lib/suricata";
 
+# Location of the classification file.
+our $classification_file = "$rulespath/classification.config";
+
 # Location to store local rules. This file will not be touched.
 our $local_rules_file = "$rulespath/local.rules";
 
@@ -539,6 +542,71 @@ sub oinkmaster () {
 	closelog();
 }
 
+#
+## Function to merge the classifications for a given amount of providers and write them
+## to the classifications file.
+#
+sub merge_classifications(@) {
+	my @providers = @_;
+
+	# Hash to store all collected classifications.
+	my %classifications = ();
+
+	# Loop through the given array of providers.
+	foreach my $provider (@providers) {
+		# Generate full path to classification file.
+		my $classification_file = "$tmp_directory/conf/$provider\-classification.config";
+
+		# Skip provider if no classification file exists.
+		next unless (-f "$classification_file");
+
+		# Open the classification file.
+		open(CLASSIFICATION, $classification_file) or die "Could not open file $classification_file. $!\n";
+
+		# Loop through the file content.
+		while(<CLASSIFICATION>) {
+			# Parse the file and grab the classification details.
+			if ($_ =~/.*config classification\: (.*)/) {
+				# Split the grabbed details.
+				my ($short_name, $short_desc, $priority) = split("\,", $1);
+
+				# Check if the grabbed classification is allready known and the priority value is greater
+				# than the stored one (which causes less priority in the IDS).
+				if (($classifications{$short_name}) && ($classifications{$short_name}[1] >= $priority)) {
+					#Change the priority value to the stricter one.
+					$classifications{$short_name} = [ "$classifications{$short_name}[0]", "$priority" ];
+				} else {
+					# Add the classification to the hash.
+					$classifications{$short_name} = [ "$short_desc", "$priority" ];
+				}
+			}
+		}
+
+		# Close the file.
+		close(CLASSIFICATION);
+	}
+
+	# Open classification file for writing.
+	open(FILE, ">", "$classification_file") or die "Could not write to $classification_file. $!\n";
+
+	# Print notice about autogenerated file.
+	print FILE "#Autogenerated file. Any custom changes will be overwritten!\n\n";
+
+	# Sort and loop through the hash of classifications.
+	foreach my $key (sort keys %classifications) {
+		# Assign some nice variable names for the items.
+		my $short_name = $key;
+		my $short_desc = $classifications{$key}[0];
+		my $priority = $classifications{$key}[1];
+
+		# Write the classification to the file.
+		print FILE "config classification: $short_name,$short_desc,$priority\n";
+	}
+
+	# Close file handle.
+	close(FILE);
+}
+
 #
 ## Function to do all the logging stuff if the downloading or updating of the ruleset fails.
 #