Use rack-cors

We will only return Access-Control headers if request includes an
Origin header

Fixes #18

Gemfile

@@ -7,6 +7,7 @@ ruby '2.3.1'
 gem 'fixer'
 gem 'newrelic_rpm'
 gem 'oj'
+gem 'rack-cors'
 gem 'rake'
 gem 'sequel_pg'
 gem 'sinatra'

Gemfile.lock

@@ -22,6 +22,7 @@ GEM
       method_source (~> 0.8.1)
       slop (~> 3.4)
     rack (1.6.4)
+    rack-cors (0.4.0)
     rack-protection (1.5.3)
       rack
     rack-test (0.6.3)
@@ -57,6 +58,7 @@ DEPENDENCIES
   newrelic_rpm
   oj
   pry
+  rack-cors
   rack-test
   rake
   sequel_pg

lib/api.rb

@@ -2,22 +2,9 @@
 
 require 'oj'
 require 'sinatra'
+require 'rack/cors'
 require 'quote'
 
-configure do
-  set :options_response_headers,
-      'Allow'                            => 'GET, HEAD, OPTIONS',
-      'Access-Control-Allow-Headers'     => 'X-Requested-With, X-HTTP-Method-Override, Content-Type, Cache-Control, Accept'
-
-  set :cors_response_headers,
-      'Access-Control-Allow-Credentials' => 'true',
-      'Access-Control-Allow-Headers'     => '*, Content-Type, Accept, AUTHORIZATION, Cache-Control',
-      'Access-Control-Allow-Methods'     => 'GET, HEAD, OPTIONS',
-      'Access-Control-Allow-Origin'      => '*',
-      'Access-Control-Expose-Headers'    => 'Cache-Control, Content-Language, Content-Type, Expires, Last-Modified, Pragma',
-      'Access-Control-Max-Age'           => '1728000'
-end
-
 configure :development do
   set :show_exceptions, :after_handler
 end
@@ -60,26 +47,28 @@ helpers do
   end
 end
 
-# https://developer.mozilla.org/en-US/docs/Web/HTTP/Access_control_CORS#Preflighted_requests
+use Rack::Cors do
+  allow do
+    origins '*'
+    resource '*'
+  end
+end
+
 options '*' do
-  headers settings.options_response_headers
   200
 end
 
 get '/' do
-  enable_cross_origin
   last_modified App.released_at
   jsonp details: 'http://fixer.io', version: App.version
 end
 
 get '/latest' do
-  enable_cross_origin
   last_modified quote[:date]
   jsonp quote
 end
 
 get(/(?<date>\d{4}-\d{2}-\d{2})/) do
-  enable_cross_origin
   last_modified quote[:date]
   jsonp quote
 end

spec/api_spec.rb

@@ -51,16 +51,17 @@ describe 'the API' do
 
   it 'allows cross-origin requests' do
     %w(/ /latest /2012-11-20).each do |path|
+      header 'Origin', '*'
       get path
-      assert_equal '*', headers['Access-Control-Allow-Origin']
       refute_empty headers['Access-Control-Allow-Methods']
     end
   end
 
   it 'responds to preflight requests' do
-    options '/'
-    refute_empty headers['Allow']
-    refute_empty headers['Access-Control-Allow-Headers']
-    last_response.must_be :ok?
+    %w(/ /latest /2012-11-20).each do |path|
+      header 'Origin', '*'
+      options path
+      refute_empty headers['Access-Control-Allow-Methods']
+    end
   end
 end