pass frame / stream type parsing errors to the hijacker callbacks

When a stream is reset, we might not have received the frame / stream
type yet. The callback might be able to identify if it was a stream
intended for that application by analyzing the stream reset error.

http3/frames_test.go

@@ -2,6 +2,7 @@ package http3
 
 import (
 	"bytes"
+	"errors"
 	"fmt"
 	"io"
 
@@ -11,6 +12,10 @@ import (
 	. "github.com/onsi/gomega"
 )
 
+type errReader struct{ err error }
+
+func (e errReader) Read([]byte) (int, error) { return 0, e.err }
+
 var _ = Describe("Frames", func() {
 	appendVarInt := func(b []byte, val uint64) []byte {
 		buf := &bytes.Buffer{}
@@ -189,7 +194,8 @@ var _ = Describe("Frames", func() {
 			buf.Write(customFrameContents)
 
 			var called bool
-			_, err := parseNextFrame(buf, func(ft FrameType) (hijacked bool, err error) {
+			_, err := parseNextFrame(buf, func(ft FrameType, e error) (hijacked bool, err error) {
+				Expect(e).ToNot(HaveOccurred())
 				Expect(ft).To(BeEquivalentTo(1337))
 				called = true
 				b := make([]byte, 3)
@@ -202,6 +208,19 @@ var _ = Describe("Frames", func() {
 			Expect(called).To(BeTrue())
 		})
 
+		It("passes on errors that occur when reading the frame type", func() {
+			testErr := errors.New("test error")
+			var called bool
+			_, err := parseNextFrame(errReader{err: testErr}, func(ft FrameType, e error) (hijacked bool, err error) {
+				Expect(e).To(MatchError(testErr))
+				Expect(ft).To(BeZero())
+				called = true
+				return true, nil
+			})
+			Expect(err).To(MatchError(errHijacked))
+			Expect(called).To(BeTrue())
+		})
+
 		It("reads a frame without hijacking the stream", func() {
 			buf := &bytes.Buffer{}
 			quicvarint.Write(buf, 1337)
@@ -212,7 +231,8 @@ var _ = Describe("Frames", func() {
 			buf.WriteString("foobar")
 
 			var called bool
-			frame, err := parseNextFrame(buf, func(ft FrameType) (hijacked bool, err error) {
+			frame, err := parseNextFrame(buf, func(ft FrameType, e error) (hijacked bool, err error) {
+				Expect(e).ToNot(HaveOccurred())
 				Expect(ft).To(BeEquivalentTo(1337))
 				called = true
 				return false, nil