From 85e122b1a9b37a3b0cb26ee9ca1c2e5b521f1969 Mon Sep 17 00:00:00 2001
From: Michal Hruby <michal@axiom.co>
Date: Mon, 29 Nov 2021 23:17:53 +0000
Subject: [PATCH] [internal-branch.go1.17-vendor] net/http2: Fix handling of
 expect continue

Recent refactoring in the http2 package broke handling of ExpectContinueTimeout, where the client was always waiting for the timeout to pass before sending the body.

For golang/go#49677
Fixes golang/go#49905

Change-Id: I565299e48313bb905b2655bd52084ea49ab742f3
GitHub-Last-Rev: 587b48407932d44b26399b6c0b4ac228e6889ac8
GitHub-Pull-Request: golang/net#118
Reviewed-on: https://go-review.googlesource.com/c/net/+/363914
Reviewed-by: Damien Neil <dneil@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Trust: Damien Neil <dneil@google.com>
Run-TryBot: Damien Neil <dneil@google.com>
(cherry picked from commit 0a0e4e1bb54c236434124a1fa7b0a400de92f2cc)
Reviewed-on: https://go-review.googlesource.com/c/net/+/368475
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
---
 http2/transport.go      | 12 +++---
 http2/transport_test.go | 90 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 96 insertions(+), 6 deletions(-)

diff --git a/http2/transport.go b/http2/transport.go
index fa715836d..2f5830456 100644
--- a/http2/transport.go
+++ b/http2/transport.go
@@ -1161,12 +1161,12 @@ func (cs *clientStream) writeRequest(req *http.Request) (err error) {
 	}
 
 	continueTimeout := cc.t.expectContinueTimeout()
-	if continueTimeout != 0 &&
-		!httpguts.HeaderValuesContainsToken(
-			req.Header["Expect"],
-			"100-continue") {
-		continueTimeout = 0
-		cs.on100 = make(chan struct{}, 1)
+	if continueTimeout != 0 {
+		if !httpguts.HeaderValuesContainsToken(req.Header["Expect"], "100-continue") {
+			continueTimeout = 0
+		} else {
+			cs.on100 = make(chan struct{}, 1)
+		}
 	}
 
 	// Past this point (where we send request headers), it is possible for
diff --git a/http2/transport_test.go b/http2/transport_test.go
index ea51dbbb7..87e6f8db3 100644
--- a/http2/transport_test.go
+++ b/http2/transport_test.go
@@ -5109,6 +5109,96 @@ func TestTransportServerResetStreamAtHeaders(t *testing.T) {
 	res.Body.Close()
 }
 
+type trackingReader struct {
+	rdr     io.Reader
+	wasRead uint32
+}
+
+func (tr *trackingReader) Read(p []byte) (int, error) {
+	atomic.StoreUint32(&tr.wasRead, 1)
+	return tr.rdr.Read(p)
+}
+
+func (tr *trackingReader) WasRead() bool {
+	return atomic.LoadUint32(&tr.wasRead) != 0
+}
+
+func TestTransportExpectContinue(t *testing.T) {
+	st := newServerTester(t, func(w http.ResponseWriter, r *http.Request) {
+		switch r.URL.Path {
+		case "/reject":
+			w.WriteHeader(403)
+		default:
+			io.Copy(io.Discard, r.Body)
+		}
+	}, optOnlyServer)
+	defer st.Close()
+
+	tr := &http.Transport{
+		TLSClientConfig:       tlsConfigInsecure,
+		MaxConnsPerHost:       1,
+		ExpectContinueTimeout: 10 * time.Second,
+	}
+
+	err := ConfigureTransport(tr)
+	if err != nil {
+		t.Fatal(err)
+	}
+	client := &http.Client{
+		Transport: tr,
+	}
+
+	testCases := []struct {
+		Name         string
+		Path         string
+		Body         *trackingReader
+		ExpectedCode int
+		ShouldRead   bool
+	}{
+		{
+			Name:         "read-all",
+			Path:         "/",
+			Body:         &trackingReader{rdr: strings.NewReader("hello")},
+			ExpectedCode: 200,
+			ShouldRead:   true,
+		},
+		{
+			Name:         "reject",
+			Path:         "/reject",
+			Body:         &trackingReader{rdr: strings.NewReader("hello")},
+			ExpectedCode: 403,
+			ShouldRead:   false,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.Name, func(t *testing.T) {
+			startTime := time.Now()
+
+			req, err := http.NewRequest("POST", st.ts.URL+tc.Path, tc.Body)
+			if err != nil {
+				t.Fatal(err)
+			}
+			req.Header.Set("Expect", "100-continue")
+			res, err := client.Do(req)
+			if err != nil {
+				t.Fatal(err)
+			}
+			res.Body.Close()
+
+			if delta := time.Since(startTime); delta >= tr.ExpectContinueTimeout {
+				t.Error("Request didn't finish before expect continue timeout")
+			}
+			if res.StatusCode != tc.ExpectedCode {
+				t.Errorf("Unexpected status code, got %d, expected %d", res.StatusCode, tc.ExpectedCode)
+			}
+			if tc.Body.WasRead() != tc.ShouldRead {
+				t.Errorf("Unexpected read status, got %v, expected %v", tc.Body.WasRead(), tc.ShouldRead)
+			}
+		})
+	}
+}
+
 type closeChecker struct {
 	io.ReadCloser
 	closed chan struct{}