rackベースのoauth signatureチェック

gistfile1.rb

module Rack
  class SignatureCheck
    def initialize(app)
      @app = app
    end
    def call(env)
      return [ 401,{ 'Content-Type' => 'text/plain','Content-Length' => '0'},[]] unless ::OauthSignature.valid?(env)
      @app.call(env)
    end
  end
end
class OauthSignature
  CONSUMER_SECRET = {'stage' =>'????????????' , 'production' => '??????????' }
  def self.valid?(env)
    oauth = env["HTTP_AUTHORIZATION"].split(",")
    raw = []
    oauth_token_secret=""
    oauth_signature =""
    oauth.each do |item|
      e = item.gsub('"','').strip
      oauth_signature = e.split("=")[1]  if e =~ /oauth_signature[^_]/
      next if e =~ /OAuth realm|oauth_signature[^_]/
      raw.push(e)
      oauth_token_secret = e.split("=")[1] if e =~ /oauth_token_secret/
    end
    raw += env['QUERY_STRING'].split("&")
    raw += env['rack.input'].read.split('&') if env['CONTENT_TYPE'] == "application/x-www-form-urlencoded"
    raw = raw.sort
    base_str = [env['REQUEST_METHOD'],Rack::Utils.escape("http://"+env["HTTP_HOST"] + env['PATH_INFO']),Rack::Utils.escape(raw.join("&"))].join("&")
    key = sprintf('%s&',Rack::Utils.escape(CONSUMER_SECRET[Rails.env]))
    if oauth_token_secret != ""
      key += Rack::Utils.escape(oauth_token_secret)
    end
    Rack::Utils.escape(Base64.encode64(OpenSSL::HMAC.digest(OpenSSL::Digest::SHA1.new,key,base_str)).chomp) == oauth_signature
  end
end