From 972870da11bb4ddd3df393473c494bd2b546cc56 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?K=C3=A9vin=20Dunglas?= Date: Tue, 30 Aug 2022 10:18:50 +0000 Subject: [PATCH] net/http/httputil: forward 1xx responses in ReverseProxy Support for 1xx responses has recently been merged in net/http (CL 269997). As discussed in this CL (https://go-review.googlesource.com/c/go/+/269997/comments/1ff70bef_c25a829a), support for forwarding 1xx responses in ReverseProxy has been extracted in this separate patch. According to RFC 7231, "a proxy MUST forward 1xx responses unless the proxy itself requested the generation of the 1xx response". Consequently, all received 1xx responses are automatically forwarded as long as the underlying transport supports ClientTrace.Got1xxResponse. Fixes #26088 Fixes #51914 Change-Id: I3a35ea023b798bfe56b7fb8696d5a49695229cfd GitHub-Last-Rev: dab8a461fb65b547306cae9b4c664e60020a8fa6 GitHub-Pull-Request: golang/go#53164 Reviewed-on: https://go-review.googlesource.com/c/go/+/409536 Reviewed-by: Damien Neil Auto-Submit: Dmitri Shuralyov TryBot-Result: Gopher Robot Reviewed-by: Dmitri Shuralyov Reviewed-by: Rhys Hiltner Run-TryBot: hopehook --- src/net/http/httputil/reverseproxy.go | 20 ++++++ src/net/http/httputil/reverseproxy_test.go | 82 ++++++++++++++++++++++ 2 files changed, 102 insertions(+) diff --git a/src/net/http/httputil/reverseproxy.go b/src/net/http/httputil/reverseproxy.go index 9ab7367eb2a9e..677b12bf26b0b 100644 --- a/src/net/http/httputil/reverseproxy.go +++ b/src/net/http/httputil/reverseproxy.go @@ -15,6 +15,7 @@ import ( "mime" "net" "net/http" + "net/http/httptrace" "net/http/internal/ascii" "net/textproto" "net/url" @@ -96,6 +97,9 @@ func (r *ProxyRequest) SetXForwarded() { // ReverseProxy is an HTTP Handler that takes an incoming request and // sends it to another server, proxying the response back to the // client. +// +// 1xx responses are forwarded to the client if the underlying +// transport supports ClientTrace.Got1xxResponse. type ReverseProxy struct { // Rewrite must be a function which modifies // the request into a new request to be sent @@ -449,6 +453,22 @@ func (p *ReverseProxy) ServeHTTP(rw http.ResponseWriter, req *http.Request) { outreq.Header.Set("User-Agent", "") } + trace := &httptrace.ClientTrace{ + Got1xxResponse: func(code int, header textproto.MIMEHeader) error { + h := rw.Header() + copyHeader(h, http.Header(header)) + rw.WriteHeader(code) + + // Clear headers, it's not automatically done by ResponseWriter.WriteHeader() for 1xx responses + for k := range h { + delete(h, k) + } + + return nil + }, + } + outreq = outreq.WithContext(httptrace.WithClientTrace(outreq.Context(), trace)) + res, err := transport.RoundTrip(outreq) if err != nil { p.getErrorHandler()(rw, outreq, err) diff --git a/src/net/http/httputil/reverseproxy_test.go b/src/net/http/httputil/reverseproxy_test.go index 549bc67b879c4..680526275506b 100644 --- a/src/net/http/httputil/reverseproxy_test.go +++ b/src/net/http/httputil/reverseproxy_test.go @@ -16,7 +16,9 @@ import ( "log" "net/http" "net/http/httptest" + "net/http/httptrace" "net/http/internal/ascii" + "net/textproto" "net/url" "os" "reflect" @@ -1671,3 +1673,83 @@ func TestReverseProxyRewriteReplacesOut(t *testing.T) { t.Errorf("got response %q, want %q", got, want) } } + +func Test1xxResponses(t *testing.T) { + backend := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { + h := w.Header() + h.Add("Link", "; rel=preload; as=style") + h.Add("Link", "; rel=preload; as=script") + w.WriteHeader(http.StatusEarlyHints) + + h.Add("Link", "; rel=preload; as=script") + w.WriteHeader(http.StatusProcessing) + + w.Write([]byte("Hello")) + })) + defer backend.Close() + backendURL, err := url.Parse(backend.URL) + if err != nil { + t.Fatal(err) + } + proxyHandler := NewSingleHostReverseProxy(backendURL) + proxyHandler.ErrorLog = log.New(io.Discard, "", 0) // quiet for tests + frontend := httptest.NewServer(proxyHandler) + defer frontend.Close() + frontendClient := frontend.Client() + + checkLinkHeaders := func(t *testing.T, expected, got []string) { + t.Helper() + + if len(expected) != len(got) { + t.Errorf("Expected %d link headers; got %d", len(expected), len(got)) + } + + for i := range expected { + if i >= len(got) { + t.Errorf("Expected %q link header; got nothing", expected[i]) + + continue + } + + if expected[i] != got[i] { + t.Errorf("Expected %q link header; got %q", expected[i], got[i]) + } + } + } + + var respCounter uint8 + trace := &httptrace.ClientTrace{ + Got1xxResponse: func(code int, header textproto.MIMEHeader) error { + switch code { + case http.StatusEarlyHints: + checkLinkHeaders(t, []string{"; rel=preload; as=style", "; rel=preload; as=script"}, header["Link"]) + case http.StatusProcessing: + checkLinkHeaders(t, []string{"; rel=preload; as=style", "; rel=preload; as=script", "; rel=preload; as=script"}, header["Link"]) + default: + t.Error("Unexpected 1xx response") + } + + respCounter++ + + return nil + }, + } + req, _ := http.NewRequestWithContext(httptrace.WithClientTrace(context.Background(), trace), "GET", frontend.URL, nil) + + res, err := frontendClient.Do(req) + if err != nil { + t.Fatalf("Get: %v", err) + } + + defer res.Body.Close() + + if respCounter != 2 { + t.Errorf("Expected 2 1xx responses; got %d", respCounter) + } + checkLinkHeaders(t, []string{"; rel=preload; as=style", "; rel=preload; as=script", "; rel=preload; as=script"}, res.Header["Link"]) + + body, _ := io.ReadAll(res.Body) + if string(body) != "Hello" { + t.Errorf("Read body %q; want Hello", body) + } +}