simple EM TCP proxy

em_proxy.rb

require 'rubygems'
require 'eventmachine'

Port = (ARGV[0] && ARGV[0].to_i) || 4567
Host = ARGV[1] || '10.0.2.4'

p ['starting proxy', Host, Port]

EM.run{

  module Client
    def initialize server
      @server = server
    end

    def connection_completed
      @connected = true
      send_data @buf if @buf

      p [:c, :connection_completed]
    end

    def receive_data data
      p [:c, :receive, data]
      @server.send_data data
    end

    def send data
      unless @connected
        (@buf ||= '') << data
      else
        send_data data
      end
    end

    def unbind
      p [:c, :unbind]
      @server.close_connection_after_writing if @server
      @server = nil
    end
  end

  module Proxy
    def post_init
      p [:s, :post_init]
      connect_client
    end

    def receive_data data
      p [:s, :receive, data]
      @client.send data      
    end

    def unbind
      p [:s, :unbind]
      @client.close_connection_after_writing if @client
      @client = nil
    end
    
    def connect_client
      @client = EM.connect Host, Port, Client, self
    end
  end

  EM.start_server '0.0.0.0', Port, Proxy
  
}