dhcpv6: allow using OptIAPrefix without initializing

Set the IPv6 prefix field to zero if the prefix is invalid
or not initialized.

Signed-off-by: Mikael Magnusson <mikma@users.sourceforge.net>

2 files changed, 21 insertions, 1 deletions

diff --git a/dhcpv6/option_iaprefix.go b/dhcpv6/option_iaprefix.go
index abd7a34..c66b242 100644
--- a/dhcpv6/option_iaprefix.go
+++ b/dhcpv6/option_iaprefix.go
@@ -34,7 +34,12 @@ func (op *OptIAPrefix) ToBytes() []byte {
 	t2.Marshal(buf)
 
 	buf.Write8(op.prefixLength)
-	buf.WriteBytes(op.ipv6Prefix.To16())
+	prefix := op.ipv6Prefix.To16()
+	if prefix != nil {
+		buf.WriteBytes(prefix)
+	} else {
+		buf.WriteBytes(make([]byte, net.IPv6len))
+	}
 	buf.WriteBytes(op.Options.ToBytes())
 	return buf.Data()
 }
diff --git a/dhcpv6/option_iaprefix_test.go b/dhcpv6/option_iaprefix_test.go
index 7a24d2b..a1c140e 100644
--- a/dhcpv6/option_iaprefix_test.go
+++ b/dhcpv6/option_iaprefix_test.go
@@ -56,6 +56,21 @@ func TestOptIAPrefixToBytes(t *testing.T) {
 	}
 }
 
+func TestOptIAPrefixToBytesDefault(t *testing.T) {
+	buf := []byte{
+		0, 0, 0, 0, // preferredLifetime
+		0, 0, 0, 0, // validLifetime
+		0,                                              // prefixLength
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // ipv6Prefix
+	}
+	opt := OptIAPrefix{
+	}
+	toBytes := opt.ToBytes()
+	if !bytes.Equal(toBytes, buf) {
+		t.Fatalf("Invalid ToBytes result. Expected %v, got %v", buf, toBytes)
+	}
+}
+
 func TestOptIAPrefixParseInvalidTooShort(t *testing.T) {
 	buf := []byte{
 		0xaa, 0xbb, 0xcc, 0xdd, // preferredLifetime