Query parameter smuggling occurs when a proxy's interpretation
of query parameters differs from that of a downstream server.
Change ReverseProxy to avoid forwarding ignored query parameters.
Remove unparsable query parameters from the outbound request
* if req.Form != nil after calling ReverseProxy.Director; and
* before calling ReverseProxy.Rewrite.
This change preserves the existing behavior of forwarding the
raw query untouched if a Director hook does not parse the query
by calling Request.ParseForm (possibly indirectly).
Fixes #54663
Fixes CVE-2022-2880
Change-Id: If1621f6b0e73a49d79059dae9e6b256e0ff18ca9
Reviewed-on: https://go-review.googlesource.com/c/go/+/432976 Reviewed-by: Roland Shoemaker <roland@golang.org> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Damien Neil <dneil@google.com>