Rack Middleware to proxy requests to a remote server. This is usefull for proxying AJAX request to remote services.

proxy.rb

require "net/http"
require "enumerator"

# Example Usage:
#
# use Rack::Proxy do |req|
#   if req.path =~ %r{^/remote/service.php$}
#     URI.parse("http://remote-service-provider.com/service-end-point.php?#{req.query}")
#   end
# end
#
# run proc{|env| [200, {"Content-Type" => "text/plain"}, ["Ha ha ha"]] }
#
class Rack::Proxy
  def initialize(app, &block)
    self.class.send(:define_method, :uri_for, &block)
    @app = app
  end

  def call(env)
    req = Rack::Request.new(env)
    method = req.request_method.downcase
    method[0..0] = method[0..0].upcase

    return @app.call(env) unless uri = uri_for(req)

    sub_request = Net::HTTP.const_get(method).new("#{uri.path}#{"?" if uri.query}#{uri.query}")

    if sub_request.request_body_permitted? and req.body
      sub_request.body_stream = req.body
      sub_request.content_length = req.content_length
      sub_request.content_type = req.content_type
    end

    sub_request["X-Forwarded-For"] = (req.env["X-Forwarded-For"].to_s.split(/, +/) + [req.env['REMOTE_ADDR']]).join(", ")
    sub_request["Accept-Encoding"] = req.accept_encoding
    sub_request["Referer"] = req.referer

    sub_response = Net::HTTP.start(uri.host, uri.port) do |http|
      http.request(sub_request)
    end

    headers = {}
    sub_response.each_header do |k,v|
      headers[k] = v unless k.to_s =~ /cookie|content-length|transfer-encoding/i
    end

    [sub_response.code.to_i, headers, [sub_response.read_body]]
  end
end

Does Rack::Request validate the method? Probably not - so an attacker could execute some custom code here. Better to explicitely check the allowed method names.

Great piece of code. Thanks!

will this work for proxying websocket request?

In don’t think so, as it’s rebuilding the request.

…

On 29 Apr 2020, at 19:40, Rahul Bennapalan ***@***.***> wrote: ***@***.*** commented on this gist. will this work for proxying websocket request? — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub, or unsubscribe.

is there any other module that you are aware, in RoR, to proxy WebSocket requests?

You’re probably going to want the we sockets to bypass rails all together, so I’d expect you can do this in your nginx config or similar. I’ve not worked on this kind of thing for a VERY long time, so pure speculation.

…

On 30 Apr 2020, at 04:33, Rahul Bennapalan ***@***.***> wrote: ***@***.*** commented on this gist. is there any other module that you are aware, in RoR, to proxy WebSocket requests? — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub, or unsubscribe.

ok, got it. thanks, Tom Lea.