em-proxy-http.rb

require 'rubygems'
require 'em-proxy'
require 'http_tools'
require 'uuid'

# > ruby em-proxy-http.rb
# > curl --proxy localhost:8080 www.google.com

host = "0.0.0.0"
port = 8080
puts "listening on #{host}:#{port}..."

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

  @req_parser = HTTPTools::Parser.new
  @req_parser.on(:finish) do
    session = UUID.generate
    host, port = @req_parser.header['Host'].split(':')
    conn.server session, :host => host, :port => (port || 80)
    @req_parser.header.delete("Host")
    @req_parser.header["Connection"]       = "close"
    @req_parser.header["Proxy-Connection"] = "close"
    conn.relay_to_servers HTTPTools::Builder.request(@req_parser.request_method, "#{host}:#{port}", @req_parser.path_info, @req_parser.header)
    conn.relay_to_servers @req_parser.body
  end

  conn.on_connect do |data,b|
    puts [:on_connect, data, b].inspect
  end

  conn.on_data do |data|
    @req_parser << data
    data
  end

  @resp_parser = HTTPTools::Parser.new
  @resp_parser.on(:finish) do
    @resp_parser.header["Connection"]        = "close"
    @resp_parser.header["Transfer-Encoding"] = "identity"
    header = HTTPTools::Builder.response(@resp_parser.status_code, @resp_parser.header)
    conn.send_data header
    conn.send_data @resp_parser.body if @resp_parser.body
    puts [:on_response, header, @resp_parser.body].inspect
  end
  conn.on_response do |backend, resp|
    @resp_parser << resp
    nil
  end

  conn.on_finish do |backend, name|
    puts [:on_finish, name].inspect
  end
end