fix for weird last_modified behavior, and duplicative work

fix for issue #180
The api should be passed an object that supports .to_time. If it happens
to be something else, make a best effort to convert it to a time object (such
as if a string is passed in -- which happens in a few of the tests).

Failing conversion, the rescue stanza will result in an http 200
response, which should be a 'safe' thing to do.

Signed-off-by: Konstantin Haase <konstantin.mailinglists@googlemail.com>

lib/sinatra/base.rb

@@ -324,10 +324,17 @@ module Sinatra
     # with a '304 Not Modified' response.
     def last_modified(time)
       return unless time
-      time = time.to_time if time.respond_to?(:to_time)
-      time = Time.parse time.strftime('%FT%T%:z') if time.respond_to?(:strftime)
-      response['Last-Modified'] = time.respond_to?(:httpdate) ? time.httpdate : time.to_s
-      halt 304 if Time.httpdate(request.env['HTTP_IF_MODIFIED_SINCE']) >= time
+      if time.respond_to?(:to_time)
+          time = time.to_time
+      else
+          ## make a best effort to convert something else to a time object
+          ## if this fails, this should throw an ArgumentError, then the
+          # rescue will result in an http 200, which should be safe
+          time = Time.parse(time.to_s).to_time
+      end
+      response['Last-Modified'] = time.httpdate
+      # compare based on seconds since epoch
+      halt 304 if Time.httpdate(request.env['HTTP_IF_MODIFIED_SINCE']).to_i >= time.to_i
     rescue ArgumentError
     end
 

test/helpers_test.rb

@@ -599,6 +599,9 @@ class HelpersTest < Test::Unit::TestCase
             get '/compare', {}, { 'HTTP_IF_MODIFIED_SINCE' => 'Sun, 26 Sep 2010 23:43:52 GMT' }
             assert_equal 200, status
             assert_equal 'foo', body
+            get '/compare', {}, { 'HTTP_IF_MODIFIED_SINCE' => 'Sun, 26 Sep 2100 23:43:52 GMT' }
+            assert_equal 304, status
+            assert_equal '', body
           end
         end