Send DAD event when DAD resolves immediately

Previously, a DAD event would not be sent if DAD was disabled.

This allows integrators to do some work when an IPv6 address is bound to
a NIC without special logic that checks if DAD is enabled.

Without this change, integrators would need to check if a NIC has DAD
enabled when an address is auto-generated. If DAD is enabled, it would
need to delay the work until the DAD completion event; otherwise, it
would need to do the work in the address auto-generated event handler.

Test: stack_test.TestDADDisabled
PiperOrigin-RevId: 293732914

1 files changed, 7 insertions, 0 deletions

diff --git a/pkg/tcpip/stack/ndp.go b/pkg/tcpip/stack/ndp.go
index fae5f5014..045409bda 100644
--- a/pkg/tcpip/stack/ndp.go
+++ b/pkg/tcpip/stack/ndp.go
@@ -448,6 +448,13 @@ func (ndp *ndpState) startDuplicateAddressDetection(addr tcpip.Address, ref *ref
 	remaining := ndp.configs.DupAddrDetectTransmits
 	if remaining == 0 {
 		ref.setKind(permanent)
+
+		// Consider DAD to have resolved even if no DAD messages were actually
+		// transmitted.
+		if ndpDisp := ndp.nic.stack.ndpDisp; ndpDisp != nil {
+			ndpDisp.OnDuplicateAddressDetectionStatus(ndp.nic.ID(), addr, true, nil)
+		}
+
 		return nil
 	}