em-proxy.rb

require 'rubygems'
require 'em-proxy'
require 'http_parser.rb'
require 'uuid'
require 'uri'

Proxy.start(:host => "127.0.0.1", :port => 9001) do |conn|

 @p = Http::Parser.new
  @p.on_headers_complete = proc do |h|
   session = UUID.generate


   @request_host, request_port = h['Host'].split(':')


   File.open("blocked_external_urls.log", 'a') {|f| f.write("#{@request_host}\n")}

   @request_host = "127.0.0.1"

   conn.server session, :host => @request_host, :port => (request_port || 80)
   conn.relay_to_servers @buffer

   @buffer = ''
  end

  @buffer = ''

  conn.on_connect do |data,b|

  end

  conn.on_data do |data|
   @buffer << data
   @p << data
   data
  end

  conn.on_response do |backend, resp|
   resp
  end

  conn.on_finish do |backend, name|

  end

end