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opt
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ruby19
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lib64
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ruby
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gems
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1.9.1
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gems
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rack-1.6.4
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lib
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rack
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Filename :
conditionalget.rb
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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: # https://github.com/wycats/merb/blob/master/merb-core/lib/merb-core/rack/middleware/conditional_get.rb class ConditionalGet def initialize(app) @app = app end def call(env) case env[REQUEST_METHOD] when "GET", "HEAD" status, headers, body = @app.call(env) headers = Utils::HeaderHash.new(headers) if status == 200 && fresh?(env, headers) status = 304 headers.delete(CONTENT_TYPE) headers.delete(CONTENT_LENGTH) original_body = body body = Rack::BodyProxy.new([]) do original_body.close if original_body.respond_to?(:close) end end [status, headers, body] else @app.call(env) end end private def fresh?(env, headers) modified_since = env['HTTP_IF_MODIFIED_SINCE'] none_match = env['HTTP_IF_NONE_MATCH'] return false unless modified_since || none_match success = true success &&= modified_since?(to_rfc2822(modified_since), headers) if modified_since success &&= etag_matches?(none_match, headers) if none_match success end def etag_matches?(none_match, headers) etag = headers['ETag'] and etag == none_match end def modified_since?(modified_since, headers) last_modified = to_rfc2822(headers['Last-Modified']) and modified_since and modified_since >= last_modified end def to_rfc2822(since) # shortest possible valid date is the obsolete: 1 Nov 97 09:55 A # anything shorter is invalid, this avoids exceptions for common cases # most common being the empty string if since && since.length >= 16 # NOTE: there is no trivial way to write this in a non execption way # _rfc2822 returns a hash but is not that usable Time.rfc2822(since) rescue nil else nil end end end end