Creating a proxy that routes through the clients computer

Question

I am making a service which is basically just a UI for another services api that only allows a specific number of requests to be made per machine for a certain period of time.

Because I would be making api requests for lots of people, I would quickly hit these limits, so to get around this I wanted to use JQuery to make the api calls on the client side, however because of javascripts same-origin policy this is proving to be quite difficult.

So I was wondering, would it be possible to create a server side proxy which routed api requests through the clients ip address? And if so, how could I go about implementing this? I've looked at things like node-http-proxy's proxy tables but I'm still unsure if it would work with the clients ip address.

Answer 1

Unfortunately you cannot "use the clients IP" as a source when routing through such a server proxy.

However you might be lucky if the service accepts an X-Forwarded-For HTTP Header. You can set that header in the proxy when sending the request to the service. The value of the header should be the clients IP.

Read more about X-Forwarded-For here: http://en.wikipedia.org/wiki/X-Forwarded-For

Answer 2

As mentioned by @HallvarHelleseth you cannot do what you are wanting. However, if the service in question supports JSONP or CORS, you should be able to do what you are wanting direct from the client.

jQuery supports CORS and JSONP, if you are using that. The limitation is IE < 10 has a different model than other browsers in support of CORS. For those implementing API services meant to be widely available, I would suggest supporting both.