Sanitize snippet file name in raw headers

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

app/controllers/projects/snippets_controller.rb

@@ -68,7 +68,7 @@ class Projects::SnippetsController < Projects::ApplicationController
       @snippet.content,
       type: 'text/plain; charset=utf-8',
       disposition: 'inline',
-      filename: @snippet.file_name
+      filename: @snippet.sanitized_file_name
     )
   end

app/controllers/snippets_controller.rb

@@ -79,7 +79,7 @@ class SnippetsController < ApplicationController
       @snippet.content,
       type: 'text/plain; charset=utf-8',
       disposition: 'inline',
-      filename: @snippet.file_name
+      filename: @snippet.sanitized_file_name
     )
   end

app/models/snippet.rb

@@ -64,6 +64,10 @@ class Snippet < ActiveRecord::Base
     file_name
   end
+  def sanitized_file_name
+    file_name.gsub(/[^a-zA-Z0-9_\-\.]+/, '')
+  end
+
   def mode
     nil
   end