1 files changed, 85 insertions, 0 deletions
diff --git a/app/services/packages/debian/extract_metadata_service.rb b/app/services/packages/debian/extract_metadata_service.rb
new file mode 100644
index 00000000000..fd5832bc0ba
--- /dev/null
+++ b/app/services/packages/debian/extract_metadata_service.rb
@@ -0,0 +1,85 @@
+# frozen_string_literal: true
+
+module Packages
+  module Debian
+    class ExtractMetadataService
+      include Gitlab::Utils::StrongMemoize
+
+      ExtractionError = Class.new(StandardError)
+
+      def initialize(package_file)
+        @package_file = package_file
+      end
+
+      def execute
+        raise ExtractionError.new('invalid package file') unless valid_package_file?
+
+        extract_metadata
+      end
+
+      private
+
+      attr_reader :package_file
+
+      def valid_package_file?
+        package_file &&
+          package_file.package&.debian? &&
+          package_file.file.size > 0 # rubocop:disable Style/ZeroLengthPredicate
+      end
+
+      def file_type_basic
+        %i[dsc deb udeb buildinfo changes].each do |format|
+          return format if package_file.file_name.end_with?(".#{format}")
+        end
+
+        nil
+      end
+
+      def file_type_source
+        # https://manpages.debian.org/buster/dpkg-dev/dpkg-source.1.en.html
+        %i[gzip bzip2 lzma xz].each do |format|
+          return :source if package_file.file_name.end_with?(".tar.#{format}")
+        end
+
+        nil
+      end
+
+      def file_type
+        strong_memoize(:file_type) do
+          file_type_basic || file_type_source || :unknown
+        end
+      end
+
+      def file_type_debian?
+        file_type == :deb || file_type == :udeb
+      end
+
+      def file_type_meta?
+        file_type == :dsc || file_type == :buildinfo || file_type == :changes
+      end
+
+      def extracted_fields
+        if file_type_debian?
+          package_file.file.use_file do |file_path|
+            ::Packages::Debian::ExtractDebMetadataService.new(file_path).execute
+          end
+        elsif file_type_meta?
+          package_file.file.use_file do |file_path|
+            ::Packages::Debian::ParseDebian822Service.new(File.read(file_path)).execute.each_value.first
+          end
+        end
+      end
+
+      def extract_metadata
+        fields = extracted_fields
+        architecture = fields.delete(:Architecture) if file_type_debian?
+
+        {
+          file_type: file_type,
+          architecture: architecture,
+          fields: fields
+        }
+      end
+    end
+  end
+end