From b8f36f35d51abf5ce1800114cc4ff72546606b16 Mon Sep 17 00:00:00 2001
From: Marten Seemann <martenseemann@gmail.com>
Date: Wed, 1 Jul 2020 15:31:24 +0700
Subject: [PATCH] fix HTTP request writing if the Request.Body reads data and
 returns EOF

---
 http3/request_writer.go      | 23 +++++++++++++++--------
 http3/request_writer_test.go | 23 +++++++++++++++++++++++
 2 files changed, 38 insertions(+), 8 deletions(-)

diff --git a/http3/request_writer.go b/http3/request_writer.go
index 1b99002d5..6720ff52f 100644
--- a/http3/request_writer.go
+++ b/http3/request_writer.go
@@ -57,14 +57,13 @@ func (w *requestWriter) WriteRequest(str quic.Stream, req *http.Request, gzip bo
 		defer req.Body.Close()
 		b := make([]byte, bodyCopyBufferSize)
 		for {
-			n, err := req.Body.Read(b)
-			if err == io.EOF {
-				break
-			}
-			if err != nil {
-				str.CancelWrite(quic.ErrorCode(errorRequestCanceled))
-				w.logger.Errorf("Error writing request: %s", err)
-				return
+			n, rerr := req.Body.Read(b)
+			if n == 0 {
+				if rerr == nil {
+					continue
+				} else if rerr == io.EOF {
+					break
+				}
 			}
 			buf := &bytes.Buffer{}
 			(&dataFrame{Length: uint64(n)}).Write(buf)
@@ -76,6 +75,14 @@ func (w *requestWriter) WriteRequest(str quic.Stream, req *http.Request, gzip bo
 				w.logger.Errorf("Error writing request: %s", err)
 				return
 			}
+			if rerr != nil {
+				if rerr == io.EOF {
+					break
+				}
+				str.CancelWrite(quic.ErrorCode(errorRequestCanceled))
+				w.logger.Errorf("Error writing request: %s", rerr)
+				return
+			}
 		}
 		str.Close()
 	}()
diff --git a/http3/request_writer_test.go b/http3/request_writer_test.go
index 28a18790a..83c77204b 100644
--- a/http3/request_writer_test.go
+++ b/http3/request_writer_test.go
@@ -16,6 +16,12 @@ import (
 	. "github.com/onsi/gomega"
 )
 
+type foobarReader struct{}
+
+func (r *foobarReader) Read(b []byte) (int, error) {
+	return copy(b, []byte("foobar")), io.EOF
+}
+
 var _ = Describe("Request Writer", func() {
 	var (
 		rw     *requestWriter
@@ -85,6 +91,23 @@ var _ = Describe("Request Writer", func() {
 		Expect(frame.(*dataFrame).Length).To(BeEquivalentTo(6))
 	})
 
+	It("writes a POST request, if the Body returns an EOF immediately", func() {
+		closed := make(chan struct{})
+		str.EXPECT().Close().Do(func() { close(closed) })
+		req, err := http.NewRequest("POST", "https://quic.clemente.io/upload.html", &foobarReader{})
+		Expect(err).ToNot(HaveOccurred())
+		Expect(rw.WriteRequest(str, req, false)).To(Succeed())
+
+		Eventually(closed).Should(BeClosed())
+		headerFields := decode(strBuf)
+		Expect(headerFields).To(HaveKeyWithValue(":method", "POST"))
+
+		frame, err := parseNextFrame(strBuf)
+		Expect(err).ToNot(HaveOccurred())
+		Expect(frame).To(BeAssignableToTypeOf(&dataFrame{}))
+		Expect(frame.(*dataFrame).Length).To(BeEquivalentTo(6))
+	})
+
 	It("sends cookies", func() {
 		str.EXPECT().Close()
 		req, err := http.NewRequest("GET", "https://quic.clemente.io/", nil)