Hide neighbor table kind from NetworkEndpoint

The network endpoint should not need to have logic to handle different
kinds of neighbor tables. Network endpoints can let the NIC know about
differnt neighbor discovery messages and let the NIC decide which table
to update.

This allows us to remove the LinkAddressCache interface.

PiperOrigin-RevId: 354812584

1 files changed, 65 insertions, 3 deletions

diff --git a/pkg/tcpip/stack/linkaddrcache.go b/pkg/tcpip/stack/linkaddrcache.go
index cd2bb3417..4504db752 100644
--- a/pkg/tcpip/stack/linkaddrcache.go
+++ b/pkg/tcpip/stack/linkaddrcache.go
@@ -24,8 +24,6 @@ import (
 
 const linkAddrCacheSize = 512 // max cache entries
 
-var _ LinkAddressCache = (*linkAddrCache)(nil)
-
 // linkAddrCache is a fixed-sized cache mapping IP addresses to link addresses.
 //
 // The entries are stored in a ring buffer, oldest entry replaced first.
@@ -140,7 +138,7 @@ func (e *linkAddrEntry) changeStateLocked(ns entryState, expiration time.Time) {
 }
 
 // add adds a k -> v mapping to the cache.
-func (c *linkAddrCache) AddLinkAddress(k tcpip.Address, v tcpip.LinkAddress) {
+func (c *linkAddrCache) add(k tcpip.Address, v tcpip.LinkAddress) {
 	// Calculate expiration time before acquiring the lock, since expiration is
 	// relative to the time when information was learned, rather than when it
 	// happened to be inserted into the cache.
@@ -290,3 +288,67 @@ func newLinkAddrCache(nic *NIC, ageLimit, resolutionTimeout time.Duration, resol
 	c.mu.table = make(map[tcpip.Address]*linkAddrEntry, linkAddrCacheSize)
 	return c
 }
+
+var _ neighborTable = (*linkAddrCache)(nil)
+
+func (*linkAddrCache) neighbors() ([]NeighborEntry, tcpip.Error) {
+	return nil, &tcpip.ErrNotSupported{}
+}
+
+func (c *linkAddrCache) addStaticEntry(addr tcpip.Address, linkAddr tcpip.LinkAddress) {
+	c.add(addr, linkAddr)
+}
+
+func (*linkAddrCache) remove(addr tcpip.Address) tcpip.Error {
+	return &tcpip.ErrNotSupported{}
+}
+
+func (*linkAddrCache) removeAll() tcpip.Error {
+	return &tcpip.ErrNotSupported{}
+}
+
+func (c *linkAddrCache) handleProbe(addr tcpip.Address, linkAddr tcpip.LinkAddress, _ LinkAddressResolver) {
+	if len(linkAddr) != 0 {
+		// NUD allows probes without a link address but linkAddrCache
+		// is a simple neighbor table which does not implement NUD.
+		//
+		// As per RFC 4861 section 4.3,
+		//
+		//   Source link-layer address
+		//               The link-layer address for the sender. MUST NOT be
+		//               included when the source IP address is the
+		//               unspecified address. Otherwise, on link layers
+		//               that have addresses this option MUST be included in
+		//               multicast solicitations and SHOULD be included in
+		//               unicast solicitations.
+		c.add(addr, linkAddr)
+	}
+}
+
+func (c *linkAddrCache) handleConfirmation(addr tcpip.Address, linkAddr tcpip.LinkAddress, flags ReachabilityConfirmationFlags) {
+	if len(linkAddr) != 0 {
+		// NUD allows confirmations without a link address but linkAddrCache
+		// is a simple neighbor table which does not implement NUD.
+		//
+		// As per RFC 4861 section 4.4,
+		//
+		//   Target link-layer address
+		//               The link-layer address for the target, i.e., the
+		//               sender of the advertisement. This option MUST be
+		//               included on link layers that have addresses when
+		//               responding to multicast solicitations. When
+		//               responding to a unicast Neighbor Solicitation this
+		//               option SHOULD be included.
+		c.add(addr, linkAddr)
+	}
+}
+
+func (c *linkAddrCache) handleUpperLevelConfirmation(tcpip.Address) {}
+
+func (*linkAddrCache) nudConfig() (NUDConfigurations, tcpip.Error) {
+	return NUDConfigurations{}, &tcpip.ErrNotSupported{}
+}
+
+func (*linkAddrCache) setNUDConfig(NUDConfigurations) tcpip.Error {
+	return &tcpip.ErrNotSupported{}
+}