Rat Hole is a handy library for creating a rack compliant http proxy that allows you to modify the request from the user and the response from the server. The name is inspired by why’s mousehole

Use Rat Hole to proxy site A into the namespace of site B.

Along the way you can modify the request from the user (example: proxy to an ip and set the Host header to support virtual hosts without DNS).

You can also modify the response from the server to cleanup html tweak headers etc.

require 'rat_hole'
require 'hpricot'

class PoliticalAgendaRatHole < RatHole
  def process_user_request(rack_request)
    # optionally munge the request before passing it to the old server
  end

  def process_server_response(rack_response, rack_request)
    # For any html pages proxied replace all links with http://ronpaul.com and
    # add a Ron-Paul header.

    if(rack_response.content_type == 'text/html')

      # dump the body into hpricot so we can use hpricot's search/replace goodness
      doc = Hpricot(rack_response.body.first)

      # update all links to help spread our political views
      (doc/"a").set('href', 'http://ronpaul.com')

      # update the original string with our modified html
      rack_response.body.first.replace(doc.to_html)

      rack_response.headers['Ron-Paul'] = 'wish I could have voted for this guy'
    end
  end
end

app = Rack::Builder.new do
  use Rack::CommonLogger # display apache style common logs
  use Rack::ShowExceptions # show exceptions
  use Rack::Reloader # reload app when an included file changes
  run PoliticalAgendaRatHole.new('www.google.com')
end

Rack::Handler::Mongrel.run(app, {:Host => 'localhost', :Port => 5001})

class PoliticalAgendaRatHoleTest < RatHoleTest
  def test_has_proper_response
    through_the(PoliticalAgendaRatHole, 'terralien.com') do |raw_response, app_response|
      assert_equal raw_response.status.to_i, app_response.status.to_i
      assert !raw_response.headers.has_key?('Ron-Paul')
      assert app_response.headers.has_key?('Ron-Paul')

      assert !raw_response.body.to_s.include?('http://ronpaul.com')
      assert app_response.body.to_s.include?('http://ronpaul.com')
    end
  end
end

* sudo gem install mikehale-rat-hole

User Request  --->
    ---  RatHoleProxy.process_user_request(rack_request) --->
                                                              <==========> OLD SERVER
    <---  RatHoleProxy.process_server_response(rack_response, rack_request) ---
User Response  <---

• handle server down

• handle gziped content (accept-encoding, transfer-encoding)

• maybe use a pool of Net::HTTP connections to speed things up

• write up some rathole’s for common tasks (logging)

• move to rspec?

• support post, head, delete, etc?

• add caching? can apache do this for us?

• Michael Hale (halethegeek.com)

• David Bogus

The MIT License

Copyright © 2008-2009 Michael Hale & David Bogus

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.