fix ParseOptVIVC (#146)

2 files changed, 10 insertions, 3 deletions

diff --git a/dhcpv4/option_vivc.go b/dhcpv4/option_vivc.go
index 9be8557..7576637 100644
--- a/dhcpv4/option_vivc.go
+++ b/dhcpv4/option_vivc.go
@@ -30,12 +30,12 @@ func ParseOptVIVC(data []byte) (*OptVIVC, error) {
 	if code != OptionVendorIdentifyingVendorClass {
 		return nil, fmt.Errorf("expected code %v, got %v", OptionVendorIdentifyingVendorClass, code)
 	}
-	length := int(data[1])
-	data = data[2:]
 
-	if length != len(data) {
+	length := int(data[1])
+	if len(data) < 2+length {
 		return nil, ErrShortByteStream
 	}
+	data = data[2:length+2]
 
 	ids := []VIVCIdentifier{}
 	for len(data) > 5 {
diff --git a/dhcpv4/option_vivc_test.go b/dhcpv4/option_vivc_test.go
index 14ded61..b290da0 100644
--- a/dhcpv4/option_vivc_test.go
+++ b/dhcpv4/option_vivc_test.go
@@ -56,6 +56,13 @@ func TestParseOptVICO(t *testing.T) {
 	data[6] = 40
 	_, err = ParseOptVIVC(data)
 	require.Error(t, err, "should get error from bad length")
+
+	// Longer than length
+	data[1] = 10
+	data[6] = 5
+	o, err = ParseOptVIVC(data)
+	require.NoError(t, err)
+	require.Equal(t, o.Identifiers[0].Data, []byte("Cisco"))
 }
 
 func TestOptVIVCString(t *testing.T) {