fix: ApplyAction.Unmarshal for 2-octet input

internal/report/report.go

@@ -491,14 +491,13 @@ type ApplyAction struct {
 }
 
 func (a *ApplyAction) Unmarshal(b []byte) error {
-	var v []byte
 	if len(b) < 1 {
 		return errors.Errorf("ApplyAction Unmarshal: less than 1 bytes")
-	} else if len(b) < 2 {
-		// slice len might be 1 or 2; enlarge slice to 2 bytes at least
-		v = make([]byte, len(b)+1)
-		copy(v, b)
 	}
+
+	// slice len might be 1 or 2; enlarge slice to 2 bytes at least
+	v := make([]byte, max(2, len(b)))
+	copy(v, b)
 	a.Flags = binary.LittleEndian.Uint16(v)
 	return nil
 }

internal/report/report_test.go

@@ -0,0 +1,55 @@
+package report_test
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"github.com/free5gc/go-upf/internal/report"
+)
+
+func TestApplyAction0(t *testing.T) {
+	var act report.ApplyAction
+	e := act.Unmarshal([]byte{})
+	assert.Error(t, e)
+}
+
+func TestApplyAction1(t *testing.T) {
+	var act report.ApplyAction
+	e := act.Unmarshal([]byte{0x02})
+	assert.NoError(t, e)
+	assert.Equal(t, uint16(0x0002), act.Flags)
+	assert.False(t, act.DROP())
+	assert.True(t, act.FORW())
+	assert.False(t, act.BUFF())
+	assert.False(t, act.NOCP())
+	assert.False(t, act.DUPL())
+	assert.False(t, act.IPMA())
+	assert.False(t, act.IPMD())
+	assert.False(t, act.DFRT())
+	assert.False(t, act.EDRT())
+	assert.False(t, act.BDPN())
+	assert.False(t, act.DDPN())
+	assert.False(t, act.FSSM())
+	assert.False(t, act.MBSU())
+}
+
+func TestApplyAction2(t *testing.T) {
+	var act report.ApplyAction
+	e := act.Unmarshal([]byte{0x0C, 0x00})
+	assert.NoError(t, e)
+	assert.Equal(t, uint16(0x000C), act.Flags)
+	assert.False(t, act.DROP())
+	assert.False(t, act.FORW())
+	assert.True(t, act.BUFF())
+	assert.True(t, act.NOCP())
+	assert.False(t, act.DUPL())
+	assert.False(t, act.IPMA())
+	assert.False(t, act.IPMD())
+	assert.False(t, act.DFRT())
+	assert.False(t, act.EDRT())
+	assert.False(t, act.BDPN())
+	assert.False(t, act.DDPN())
+	assert.False(t, act.FSSM())
+	assert.False(t, act.MBSU())
+}