48 lines
1.5 KiB
Ruby
48 lines
1.5 KiB
Ruby
require 'rack/utils'
|
|
|
|
module Rack
|
|
|
|
# Middleware that enables conditional GET using If-None-Match and
|
|
# If-Modified-Since. The application should set either or both of the
|
|
# Last-Modified or Etag response headers according to RFC 2616. When
|
|
# either of the conditions is met, the response body is set to be zero
|
|
# length and the response status is set to 304 Not Modified.
|
|
#
|
|
# Applications that defer response body generation until the body's each
|
|
# message is received will avoid response body generation completely when
|
|
# a conditional GET matches.
|
|
#
|
|
# Adapted from Michael Klishin's Merb implementation:
|
|
# http://github.com/wycats/merb-core/tree/master/lib/merb-core/rack/middleware/conditional_get.rb
|
|
class ConditionalGet
|
|
def initialize(app)
|
|
@app = app
|
|
end
|
|
|
|
def call(env)
|
|
return @app.call(env) unless %w[GET HEAD].include?(env['REQUEST_METHOD'])
|
|
|
|
status, headers, body = @app.call(env)
|
|
headers = Utils::HeaderHash.new(headers)
|
|
if etag_matches?(env, headers) || modified_since?(env, headers)
|
|
status = 304
|
|
headers.delete('Content-Type')
|
|
headers.delete('Content-Length')
|
|
body = []
|
|
end
|
|
[status, headers, body]
|
|
end
|
|
|
|
private
|
|
def etag_matches?(env, headers)
|
|
etag = headers['Etag'] and etag == env['HTTP_IF_NONE_MATCH']
|
|
end
|
|
|
|
def modified_since?(env, headers)
|
|
last_modified = headers['Last-Modified'] and
|
|
last_modified == env['HTTP_IF_MODIFIED_SINCE']
|
|
end
|
|
end
|
|
|
|
end
|