1 files changed, 65 insertions, 0 deletions
diff --git a/lib/gitlab/github_import/attachments_downloader.rb b/lib/gitlab/github_import/attachments_downloader.rb
new file mode 100644
index 00000000000..b71d5f753f2
--- /dev/null
+++ b/lib/gitlab/github_import/attachments_downloader.rb
@@ -0,0 +1,65 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module GithubImport
+    class AttachmentsDownloader
+      include ::Gitlab::ImportExport::CommandLineUtil
+      include ::BulkImports::FileDownloads::FilenameFetch
+      include ::BulkImports::FileDownloads::Validations
+
+      DownloadError = Class.new(StandardError)
+
+      FILENAME_SIZE_LIMIT = 255 # chars before the extension
+      DEFAULT_FILE_SIZE_LIMIT = 25.megabytes
+      TMP_DIR = File.join(Dir.tmpdir, 'github_attachments').freeze
+
+      attr_reader :file_url, :filename, :file_size_limit
+
+      def initialize(file_url, file_size_limit: DEFAULT_FILE_SIZE_LIMIT)
+        @file_url = file_url
+        @file_size_limit = file_size_limit
+
+        filename = URI(file_url).path.split('/').last
+        @filename = ensure_filename_size(filename)
+      end
+
+      def perform
+        validate_content_length
+        validate_filepath
+
+        file = download
+        validate_symlink
+        file
+      end
+
+      def delete
+        FileUtils.rm_rf File.dirname(filepath)
+      end
+
+      private
+
+      def raise_error(message)
+        raise DownloadError, message
+      end
+
+      def response_headers
+        @response_headers ||=
+          Gitlab::HTTP.perform_request(Net::HTTP::Head, file_url, {}).headers
+      end
+
+      def download
+        file = File.open(filepath, 'wb')
+        Gitlab::HTTP.perform_request(Net::HTTP::Get, file_url, stream_body: true) { |batch| file.write(batch) }
+        file
+      end
+
+      def filepath
+        @filepath ||= begin
+          dir = File.join(TMP_DIR, SecureRandom.uuid)
+          mkdir_p dir
+          File.join(dir, filename)
+        end
+      end
+    end
+  end
+end