reverseproxy: Restore request's original host and header (fix #3509)

We already restore them within the retry loop, but after successful proxy we didn't reset them, so as handlers bubble back up, they would see the values used for proxying. Thanks to @ziddey for identifying the cause.

Matthew Holt committed Jul 17, 2020 at 17:54 UTC 246a31aacd7159acc009ff6d6497596a96533f73

1 file changed +10 -3

modules/caddyhttp/reverseproxy/reverseproxy.go

+10 -3

@@ -329,10 +329,17 @@ func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request, next caddyht

329 fmt.Errorf("preparing request for upstream round-trip: %v", err))

330 }

331

332 - // we will need the original headers and Host

333 - // value if header operations are configured

334 - reqHeader := r.Header

332 + // we will need the original headers and Host value if

333 + // header operations are configured; and we should

334 + // restore them after we're done if they are changed

335 + // (for example, changing the outbound Host header

336 + // should not permanently change r.Host; issue #3509)

337 reqHost := r.Host

338 + reqHeader := r.Header

339 + defer func() {

340 + r.Host = reqHost

341 + r.Header = reqHeader

342 + }()

343

344 start := time.Now()

345