correctly set multipart param encoding

lib/rack/multipart/parser.rb

@@ -56,6 +56,8 @@ def parse
           end
 
           get_data(filename, body, content_type, name, head) do |data|
+            tag_multipart_encoding(filename, content_type, name, data)
+
             Utils.normalize_params(@params, name, data)
           end
 
@@ -165,9 +167,40 @@ def scrub_filename(filename)
             filename.encode!(:invalid => :replace, :undef => :replace)
           end
         end
+
+        CHARSET    = "charset"
+        TEXT_PLAIN = "text/plain"
+
+        def tag_multipart_encoding(filename, content_type, name, body)
+          name.force_encoding Encoding::UTF_8
+
+          return if filename
+
+          encoding = Encoding::UTF_8
+
+          if content_type
+            list         = content_type.split(';')
+            type_subtype = list.first
+            type_subtype.strip!
+            if TEXT_PLAIN == type_subtype
+              rest         = list.drop 1
+              rest.each do |param|
+                k,v = param.split('=', 2)
+                k.strip!
+                v.strip!
+                encoding = Encoding.find v if k == CHARSET
+              end
+            end
+          end
+
+          name.force_encoding encoding
+          body.force_encoding encoding
+        end
       else
         def scrub_filename(filename)
         end
+        def tag_multipart_encoding(filename, content_type, name, body)
+        end
       end
 
       def get_data(filename, body, content_type, name, head)

test/spec_multipart.rb

@@ -30,6 +30,42 @@ def multipart_file(name)
     params["text"].should.equal "contents"
   end
 
+  should "set US_ASCII encoding based on charset" do
+    env = Rack::MockRequest.env_for("/", multipart_fixture(:content_type_and_no_filename))
+    params = Rack::Multipart.parse_multipart(env)
+    params["text"].encoding.should.equal Encoding::US_ASCII
+
+    # I'm not 100% sure if making the param name encoding match the
+    # Content-Type charset is the right thing to do.  We should revisit this.
+    params.keys.each do |key|
+      key.encoding.should.equal Encoding::US_ASCII
+    end
+  end
+
+  should "set BINARY encoding on things without content type" do
+    env = Rack::MockRequest.env_for("/", multipart_fixture(:none))
+    params = Rack::Multipart.parse_multipart(env)
+    params["submit-name"].encoding.should.equal Encoding::UTF_8
+  end
+
+  should "set UTF8 encoding on names of things without content type" do
+    env = Rack::MockRequest.env_for("/", multipart_fixture(:none))
+    params = Rack::Multipart.parse_multipart(env)
+    params.keys.each do |key|
+      key.encoding.should.equal Encoding::UTF_8
+    end
+  end
+
+  should "default text to UTF8" do
+    env = Rack::MockRequest.env_for("/", multipart_fixture(:text))
+    params = Rack::Multipart.parse_multipart(env)
+    params['submit-name'].encoding.should.equal Encoding::UTF_8
+    params['submit-name-with-content'].encoding.should.equal Encoding::UTF_8
+    params.keys.each do |key|
+      key.encoding.should.equal Encoding::UTF_8
+    end
+  end
+
   should "raise RangeError if the key space is exhausted" do
     env = Rack::MockRequest.env_for("/", multipart_fixture(:content_type_and_no_filename))
 
@@ -196,6 +232,14 @@ def rd.length
     params["files"].size.should.equal 252
   end
 
+  should "parse multipart/mixed" do
+    env = Rack::MockRequest.env_for("/", multipart_fixture(:mixed_files))
+    params = Rack::Utils::Multipart.parse_multipart(env)
+    params["foo"].should.equal "bar"
+    params["files"].should.be.instance_of String
+    params["files"].size.should.equal 252
+  end
+
   should "parse IE multipart upload and clean up filename" do
     env = Rack::MockRequest.env_for("/", multipart_fixture(:ie))
     params = Rack::Multipart.parse_multipart(env)