proxy.rb

require 'socket'
require 'uri'

class Proxy
  def initialize(port)
    @port = port
  end

  attr_reader :port

  def start
    print "Starting proxy on port #{port}\n"
    socket = TCPServer.new port
    loop do
      client_socket = socket.accept
      Thread.new(client_socket, &method(:proxy_request))
    end
  ensure
    socket && socket.close
  end

  private

  def proxy_request(client_socket)
    print "Got client\n"

    request_line = client_socket.readline
    print request_line

    verb    = request_line[/^\w+/]
    url     = request_line[/^\w+\s+(\S+)/, 1]
    version = request_line[/HTTP\/(1\.\d)\s*$/, 1]
    uri     = URI::parse url

    to_socket = TCPSocket.new(uri.host, (uri.port.nil? ? 80 : uri.port))
    to_socket.write("#{verb} #{uri.path}?#{uri.query} HTTP/#{version}\r\n")

    content_len = 0

    loop do
      line = client_socket.readline
      print line
      to_socket.write(line)
      break if line.strip.empty?
    end

    answer = to_socket.read
    client_socket.write(answer)

    client_socket.close
    print "Socket closed\n"

  rescue Exception => e
    p e
  end
end

Proxy
  .new(3001)
  .start