Future Request - Support Multiple Upstream Proxies

[0xtavian]

Problem:
Currently Proxify cant handle multiple upstream proxies at once. For example, running
proxify -http-proxy http://127.0.0.1:8080 -http-proxy http://127.0.0.1:8081 -addr 127.0.0.1:8888 curl https://google.com -x 127.0.0.1:8888

This will forward the request to last http-proxy provided via the command line. So in the above example, the curl would only use http://127.0.0.1:8081 as the upstream proxy.

Suggested result:
Ideally when specifying multiple upstream proxies, Proxify should forward the request to both proxies and subsequently forward both responses back to the client.

Once this is implemented, another feature or cli argument can be created to specify how many requests to forward to one proxy, before switching to the other. The use case for this could be a proxy rotator that round-robins the requests based on a user provider integer. For example, adding a --count/-c argument.

In this hypothetical example, proxfiy would forward one http request to one proxy before switching to the next proxy (optionally it could read from a file of http-proxies).

proxify -http-proxy http://127.0.0.1:8080 -http-proxy http://127.0.0.1:8081 -addr 127.0.0.1:8888 -c 1
curl https://google.com -x 127.0.0.1:8888 >> forwards request to http://127.0.0.1:8081
curl https://google.com -x 127.0.0.1:8888 >> forwards request to http://127.0.0.1:8080
curl https://google.com -x 127.0.0.1:8888 >> forwards request to http://127.0.0.1:8081

and so on.

[Mzack9999]

@0xtavian Thanks for opening the issue. The functionality is almost implemented at #66 (WIP). I'm not sure that the http client would be able to parse two responses (according to rfc2616 one request is associated with one response only).
Did you mean that you want every request sent in parallel by every upstream proxy to the destination but return only one response, for example, according to matching conditions?

[0xtavian]

@Mzack9999 @ehsandeep sorry for the late reply, just seeing this and this looks wonderful!

Did you mean that you want every request sent in parallel by every upstream proxy to the destination but return only one response, for example, according to matching conditions?

No I meant sending the same request to both upstream proxies and returning both responses. So the http client would parse two responses, but would have both requests so maybe it should work?

The most important feature from my request IMO is the ability to provide Proxify a list of upstream proxies, which for example, could send one request and parse one response each before moving onto the next one, something similar to IPRotate_Burp_Extension but in this case instead of using AWS API Gateway to change your IP on every request, users could use a bunch of cloud VSIs under their control ( axiom) or other proxies.

Thanks again. Super excited for this <3

[Mzack9999]

@0xtavian, I think that the scenario that you are describing would make standard http clients (respecting the RFC paradigm of one request => one response) parse only the first received request and ignore the second one. Probably the most similar thing would be using a request count for rotation equal to 1 and sending the same request many times equal to the number of upstream proxies, so you would be able to collect all of them without any custom implementation.
To test this functionality, the syntax is like before. Still, you need to provide comma-separated upstreams proxies as follows (-c controls the number of requests before switching to the next http proxy):

go run . -http-proxy http://127.0.0.1:8080,http://127.0.0.1:8081 -c 5

I was also thinking of adding request signing capability for each request passing through the proxy (e.g., aws as we are doing in nuclei https://github.com/projectdiscovery/nuclei/pull/1247).