fix "invalid byte sequence in US-ASCII" in topic attachment

test plan:
 - create a new discussion
 - attach a non-ASCII file
 - save the discussion
 - it shouldn't explode

Change-Id: I9ada9dbf2bf25e63baab22f6117171436d4808c6
Reviewed-on: https://gerrit.instructure.com/27832
Tested-by: Jenkins <jenkins@instructure.com>
QA-Review: Matt Fairbourn <mfairbourn@instructure.com>
Reviewed-by: Bracken Mosbacker <bracken@instructure.com>
Product-Review: Bracken Mosbacker <bracken@instructure.com>

config/initializers/rack.rb

@@ -1,3 +1,5 @@
+#encoding:ASCII-8BIT
+
 Rack::Utils.key_space_limit = 128.kilobytes # default is 64KB
 
 if CANVAS_RAILS2

spec/fixtures/multipart-request

@@ -0,0 +1,86 @@
+------WebKitFormBoundary2raDSu0SsqTAphBU
+Content-Disposition: form-data; name="reply_count_tooltip[other]"
+
+%{count} replies
+------WebKitFormBoundary2raDSu0SsqTAphBU
+Content-Disposition: form-data; name="reply_count_tooltip[one]"
+
+1 reply
+------WebKitFormBoundary2raDSu0SsqTAphBU
+Content-Disposition: form-data; name="reply_count_tooltip[zero]"
+
+No replies
+------WebKitFormBoundary2raDSu0SsqTAphBU
+Content-Disposition: form-data; name="unread_count_tooltip[other]"
+
+%{count} unread replies
+------WebKitFormBoundary2raDSu0SsqTAphBU
+Content-Disposition: form-data; name="unread_count_tooltip[one]"
+
+1 unread reply
+------WebKitFormBoundary2raDSu0SsqTAphBU
+Content-Disposition: form-data; name="unread_count_tooltip[zero]"
+
+No unread replies
+------WebKitFormBoundary2raDSu0SsqTAphBU
+Content-Disposition: form-data; name="summary"
+
+blah
+------WebKitFormBoundary2raDSu0SsqTAphBU
+Content-Disposition: form-data; name="threaded"
+
+0
+------WebKitFormBoundary2raDSu0SsqTAphBU
+Content-Disposition: form-data; name="attachment"; filename="test.txt"
+Content-Type: text/plain
+
+blah blah bláh <- non-ascii is important here :P
+------WebKitFormBoundary2raDSu0SsqTAphBU
+Content-Disposition: form-data; name="message"
+
+<p>blah</p>
+------WebKitFormBoundary2raDSu0SsqTAphBU
+Content-Disposition: form-data; name="title"
+
+test thing
+------WebKitFormBoundary2raDSu0SsqTAphBU
+Content-Disposition: form-data; name="set_assignment"
+
+false
+------WebKitFormBoundary2raDSu0SsqTAphBU
+Content-Disposition: form-data; name="user_can_see_posts"
+
+true
+------WebKitFormBoundary2raDSu0SsqTAphBU
+Content-Disposition: form-data; name="subscribed"
+
+false
+------WebKitFormBoundary2raDSu0SsqTAphBU
+Content-Disposition: form-data; name="require_initial_post"
+
+0
+------WebKitFormBoundary2raDSu0SsqTAphBU
+Content-Disposition: form-data; name="podcast_has_student_posts"
+
+false
+------WebKitFormBoundary2raDSu0SsqTAphBU
+Content-Disposition: form-data; name="podcast_enabled"
+
+0
+------WebKitFormBoundary2raDSu0SsqTAphBU
+Content-Disposition: form-data; name="discussion_type"
+
+side_comment
+------WebKitFormBoundary2raDSu0SsqTAphBU
+Content-Disposition: form-data; name="is_announcement"
+
+false
+------WebKitFormBoundary2raDSu0SsqTAphBU
+Content-Disposition: form-data; name="_method"
+
+POST
+------WebKitFormBoundary2raDSu0SsqTAphBU
+Content-Disposition: form-data; name="authenticity_token"
+
+11PqRxNnjVRnG6zc6m5aLh+t/ahMI9V1KSGKPprHfibFmldZQPsmhZhPK1vDoc3h1nK0F1XcqSlvRBwHDHXsxQ==
+------WebKitFormBoundary2raDSu0SsqTAphBU--

spec/initializers/rack_spec.rb

@@ -28,5 +28,14 @@ this one really is a file
       params["file"][:filename].should eql "filename.frd"
       params["file"][:tempfile].read.should eql "this one really is a file"
     end
+
+    it "should not explode with a non-ASCII file attachment" do
+      request_file = File.open( File.expand_path('../fixtures/multipart-request', File.dirname(__FILE__)) )
+      env = { 'CONTENT_TYPE' => 'multipart/form-data; boundary=----WebKitFormBoundary2raDSu0SsqTAphBU',
+              'CONTENT_LENGTH' => request_file.size,
+              'rack.input' => request_file
+      }
+      lambda { Rack::Utils::Multipart.parse_multipart(env) }.should_not raise_error
+    end
   end
 end