net/http/httputil: clarify the contract on ReverseProxy's Director.

Avoid potential race conditions by clarifying to implemntors of the
ReverseProxy interface, the lifetime of provided http.Request structs.

Fixes #18456
Change-Id: I46aa60322226ecc3a0d30fa1ef108e504171957a
Reviewed-on: https://go-review.googlesource.com/34720
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

diff --git a/src/net/http/httputil/reverseproxy.go b/src/net/http/httputil/reverseproxy.go
index 78675057085c23bce6c5282af50ff67bf7aaf520..79c8fe27702fbbece3b81451c9aa23db5891ecfc 100644 (file)
--- a/src/net/http/httputil/reverseproxy.go
+++ b/src/net/http/httputil/reverseproxy.go
@@ -30,6 +30,8 @@ type ReverseProxy struct {
        // the request into a new request to be sent
        // using Transport. Its response is then copied
        // back to the original client unmodified.
+       // Director must not access the provided Request
+       // after returning.
        Director func(*http.Request)
 
        // The transport used to perform proxy requests.