Add fuzzing for client hello

mtglib/internal/faketls/client_hello_fuzz_test.go

@@ -0,0 +1,21 @@
+package faketls_test
+
+import (
+	"testing"
+
+	"github.com/9seconds/mtg/v2/mtglib/internal/faketls"
+	"github.com/stretchr/testify/require"
+)
+
+var FuzzClientHelloSecret = []byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
+
+func FuzzClientHello(f *testing.F) {
+	f.Add([]byte{1, 2, 3})
+
+	f.Fuzz(func(t *testing.T, frame []byte) {
+		_, err := faketls.ParseClientHello(FuzzClientHelloSecret, frame)
+
+		// a probability of having != err is almost negligible
+		require.Error(t, err)
+	})
+}

mtglib/internal/faketls/init.go

@@ -19,7 +19,7 @@ const (
 
 	// ClientHelloMinLen is a minimal possible length of
 	// ClientHello record.
-	ClientHelloMinLen = 4
+	ClientHelloMinLen = 6
 
 	// WelcomePacketRandomOffset is an offset of random in ServerHello
 	// packet (including record envelope).