escape filename in the multipart/form-data Content-Disposition header

Author: motoyasu-saburi

lib/httparty/request/body.rb

@@ -32,6 +32,13 @@ def multipart?
 
       private
 
+      # https://html.spec.whatwg.org/#multipart-form-data
+      MULTIPART_FORM_DATA_REPLACEMENT_TABLE = {
+        '"'  => '%22',
+        "\r" => '%0D',
+        "\n" => '%0A'
+      }.freeze
+
       def generate_multipart
         normalized_params = params.flat_map { |key, value| HashConversions.normalize_keys(key, value) }
 
@@ -40,7 +47,7 @@ def generate_multipart
           memo << %(Content-Disposition: form-data; name="#{key}")
           # value.path is used to support ActionDispatch::Http::UploadedFile
           # https://github.com/jnunemaker/httparty/pull/585
-          memo << %(; filename="#{file_name(value)}") if file?(value)
+          memo << %(; filename="#{file_name(value).gsub(/["\r\n]/, MULTIPART_FORM_DATA_REPLACEMENT_TABLE)}") if file?(value)
           memo << NEWLINE
           memo << "Content-Type: #{content_type(value)}#{NEWLINE}" if file?(value)
           memo << NEWLINE

spec/httparty/request/body_spec.rb

@@ -105,6 +105,38 @@
 
           it { is_expected.to eq multipart_params }
         end
+
+        context 'when file name contains [ " \r \n ]' do
+          let(:options) { { force_multipart: true } }
+          let(:some_temp_file) { Tempfile.new(['basefile', '.txt']) }
+          let(:file_content) { 'test' }
+          let(:raw_filename) { "dummy=tampering.sh\"; \r\ndummy=a.txt" }
+          let(:expected_file_name) { 'dummy=tampering.sh%22; %0D%0Adummy=a.txt' }
+          let(:file) { double(:mocked_action_dispatch, path: some_temp_file.path, original_filename: raw_filename, read: file_content) }
+          let(:params) do
+            {
+              user: {
+                attachment_file: file,
+                enabled: true
+              }
+            }
+          end
+          let(:multipart_params) do
+            "--------------------------c772861a5109d5ef\r\n" \
+            "Content-Disposition: form-data; name=\"user[attachment_file]\"; filename=\"#{expected_file_name}\"\r\n" \
+            "Content-Type: text/plain\r\n" \
+            "\r\n" \
+            "test\r\n" \
+            "--------------------------c772861a5109d5ef\r\n" \
+            "Content-Disposition: form-data; name=\"user[enabled]\"\r\n" \
+            "\r\n" \
+            "true\r\n" \
+            "--------------------------c772861a5109d5ef--\r\n"
+          end
+
+          it { is_expected.to eq multipart_params }
+
+        end
       end
     end
   end