From 202dddd51ece92f41c655d6d212c877288338aab Mon Sep 17 00:00:00 2001
From: Marten Seemann <martenseemann@gmail.com>
Date: Mon, 20 Jan 2025 22:26:04 -0800
Subject: [PATCH] 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 +++
 internal/wire/frame.go      | 21 +++++++++++++++++++++
 internal/wire/frame_test.go | 29 +++++++++++++++++++++++++++++
 internal/wire/interface.go  | 11 -----------
 4 files changed, 53 insertions(+), 11 deletions(-)
 create mode 100644 internal/wire/frame.go
 create mode 100644 internal/wire/frame_test.go
 delete mode 100644 internal/wire/interface.go

diff --git a/fuzzing/frames/fuzz.go b/fuzzing/frames/fuzz.go
index 7229f488..0f4e9033 100644
--- a/fuzzing/frames/fuzz.go
+++ b/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 {
diff --git a/internal/wire/frame.go b/internal/wire/frame.go
new file mode 100644
index 00000000..10d4eebc
--- /dev/null
+++ b/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
+}
diff --git a/internal/wire/frame_test.go b/internal/wire/frame_test.go
new file mode 100644
index 00000000..3012b558
--- /dev/null
+++ b/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))
+	}
+}
diff --git a/internal/wire/interface.go b/internal/wire/interface.go
deleted file mode 100644
index bc17883b..00000000
--- a/internal/wire/interface.go
+++ /dev/null
@@ -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
-}