wire: implement frame classification into probing / non-probing (#4901)

* wire: implement frame classification into probing / non-probing

* wire: consolidate files

* check if frame is ack eliciting and path probing in frames fuzz test

fuzzing/frames/fuzz.go

@@ -3,6 +3,7 @@ package frames
 import (
 	"fmt"
 
+	"github.com/quic-go/quic-go/internal/ackhandler"
 	"github.com/quic-go/quic-go/internal/protocol"
 	"github.com/quic-go/quic-go/internal/wire"
 )
@@ -49,6 +50,8 @@ func Fuzz(data []byte) int {
 		if f == nil { // PADDING frame
 			continue
 		}
+		wire.IsProbingFrame(f)
+		ackhandler.IsFrameAckEliciting(f)
 		// We accept empty STREAM frames, but we don't write them.
 		if sf, ok := f.(*wire.StreamFrame); ok {
 			if sf.DataLen() == 0 {

internal/wire/frame.go

@@ -0,0 +1,21 @@
+package wire
+
+import (
+	"github.com/quic-go/quic-go/internal/protocol"
+)
+
+// A Frame in QUIC
+type Frame interface {
+	Append(b []byte, version protocol.Version) ([]byte, error)
+	Length(version protocol.Version) protocol.ByteCount
+}
+
+// IsProbingFrame returns true if the frame is a probing frame.
+// See section 9.1 of RFC 9000.
+func IsProbingFrame(f Frame) bool {
+	switch f.(type) {
+	case *PathChallengeFrame, *PathResponseFrame, *NewConnectionIDFrame:
+		return true
+	}
+	return false
+}

internal/wire/frame_test.go

@@ -0,0 +1,29 @@
+package wire
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestProbingFrames(t *testing.T) {
+	testCases := map[Frame]bool{
+		&AckFrame{}:             false,
+		&ConnectionCloseFrame{}: false,
+		&DataBlockedFrame{}:     false,
+		&PingFrame{}:            false,
+		&ResetStreamFrame{}:     false,
+		&StreamFrame{}:          false,
+		&DatagramFrame{}:        false,
+		&MaxDataFrame{}:         false,
+		&MaxStreamDataFrame{}:   false,
+		&StopSendingFrame{}:     false,
+		&PathChallengeFrame{}:   true,
+		&PathResponseFrame{}:    true,
+		&NewConnectionIDFrame{}: true,
+	}
+
+	for f, expected := range testCases {
+		require.Equal(t, expected, IsProbingFrame(f))
+	}
+}

internal/wire/interface.go

@@ -1,11 +0,0 @@
-package wire
-
-import (
-	"github.com/quic-go/quic-go/internal/protocol"
-)
-
-// A Frame in QUIC
-type Frame interface {
-	Append(b []byte, version protocol.Version) ([]byte, error)
-	Length(version protocol.Version) protocol.ByteCount
-}