forward.rb

require 'net/http'
require 'rack'

# todo
# - detect ssl
# - keepalive?

module Rack
  class Forwarder
    def initialize(host, port=80)
      @host, @port = host, port
    end

    def call(env)
      rackreq = Rack::Request.new(env)

      headers = Rack::Utils::HeaderHash.new
      env.each { |key, value|
        if key =~ /HTTP_(.*)/
          headers[$1] = value
        end
      }

      res = Net::HTTP.start(@host, @port) { |http|
        m = rackreq.request_method
        case m
        when "GET", "HEAD", "DELETE", "OPTIONS", "TRACE"
          req = Net::HTTP.const_get(m.capitalize).new(rackreq.fullpath, headers)
        when "PUT", "POST"
          req = Net::HTTP.const_get(m.capitalize).new(rackreq.fullpath, headers)
          req.body_stream = rackreq.body
        else
          raise "method not supported: #{method}"
        end

        http.request(req)
      }

      [res.code, Rack::Utils::HeaderHash.new(res.to_hash), [res.body]]
    end
  end
end