Validate incoming NDP Router Advertisements, as per RFC 4861 section 6.1.2

This change validates incoming NDP Router Advertisements as per RFC 4861 section
6.1.2. It also includes the skeleton to handle Router Advertiements that arrive
on some NIC.

Tests: Unittest to make sure only valid NDP Router Advertisements are received/
not dropped.
PiperOrigin-RevId: 278891972

1 files changed, 16 insertions, 0 deletions

diff --git a/pkg/tcpip/stack/stack.go b/pkg/tcpip/stack/stack.go
index 115a6fcb8..8b141cafd 100644
--- a/pkg/tcpip/stack/stack.go
+++ b/pkg/tcpip/stack/stack.go
@@ -1557,6 +1557,22 @@ func (s *Stack) SetNDPConfigurations(id tcpip.NICID, c NDPConfigurations) *tcpip
 	return nil
 }
 
+// HandleNDPRA provides a NIC with ID id a validated NDP Router Advertisement
+// message that it needs to handle.
+func (s *Stack) HandleNDPRA(id tcpip.NICID, ip tcpip.Address, ra header.NDPRouterAdvert) *tcpip.Error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	nic, ok := s.nics[id]
+	if !ok {
+		return tcpip.ErrUnknownNICID
+	}
+
+	nic.handleNDPRA(ip, ra)
+
+	return nil
+}
+
 // PortSeed returns a 32 bit value that can be used as a seed value for port
 // picking.
 //