From a2ec1932c9b76d80d3af93aa74acf945829cd582 Mon Sep 17 00:00:00 2001
From: Ghanan Gowripalan <ghanan@google.com>
Date: Tue, 19 Jan 2021 12:06:08 -0800
Subject: [PATCH] Drop CheckLocalAddress from LinkAddressCache

PiperOrigin-RevId: 352623277
---
 pkg/tcpip/network/arp/arp.go        | 24 +++++++++---------------
 pkg/tcpip/network/ipv6/icmp_test.go | 11 +++--------
 pkg/tcpip/stack/registration.go     |  4 ----
 3 files changed, 12 insertions(+), 27 deletions(-)

diff --git a/pkg/tcpip/network/arp/arp.go b/pkg/tcpip/network/arp/arp.go
index 3259d052f..d54e7fe86 100644
--- a/pkg/tcpip/network/arp/arp.go
+++ b/pkg/tcpip/network/arp/arp.go
@@ -138,23 +138,17 @@ func (e *endpoint) HandlePacket(pkt *stack.PacketBuffer) {
 		stats.RequestsReceived.Increment()
 		localAddr := tcpip.Address(h.ProtocolAddressTarget())
 
+		if e.protocol.stack.CheckLocalAddress(e.nic.ID(), header.IPv4ProtocolNumber, localAddr) == 0 {
+			stats.RequestsReceivedUnknownTargetAddress.Increment()
+			return // we have no useful answer, ignore the request
+		}
+
+		remoteAddr := tcpip.Address(h.ProtocolAddressSender())
+		remoteLinkAddr := tcpip.LinkAddress(h.HardwareAddressSender())
+
 		if e.nud == nil {
-			if e.linkAddrCache.CheckLocalAddress(e.nic.ID(), header.IPv4ProtocolNumber, localAddr) == 0 {
-				stats.RequestsReceivedUnknownTargetAddress.Increment()
-				return // we have no useful answer, ignore the request
-			}
-
-			addr := tcpip.Address(h.ProtocolAddressSender())
-			linkAddr := tcpip.LinkAddress(h.HardwareAddressSender())
-			e.linkAddrCache.AddLinkAddress(e.nic.ID(), addr, linkAddr)
+			e.linkAddrCache.AddLinkAddress(e.nic.ID(), remoteAddr, remoteLinkAddr)
 		} else {
-			if e.protocol.stack.CheckLocalAddress(e.nic.ID(), header.IPv4ProtocolNumber, localAddr) == 0 {
-				stats.RequestsReceivedUnknownTargetAddress.Increment()
-				return // we have no useful answer, ignore the request
-			}
-
-			remoteAddr := tcpip.Address(h.ProtocolAddressSender())
-			remoteLinkAddr := tcpip.LinkAddress(h.HardwareAddressSender())
 			e.nud.HandleProbe(remoteAddr, ProtocolNumber, remoteLinkAddr, e.protocol)
 		}
 
diff --git a/pkg/tcpip/network/ipv6/icmp_test.go b/pkg/tcpip/network/ipv6/icmp_test.go
index b1e6a70a2..a660a1cea 100644
--- a/pkg/tcpip/network/ipv6/icmp_test.go
+++ b/pkg/tcpip/network/ipv6/icmp_test.go
@@ -91,16 +91,11 @@ func (*stubDispatcher) DeliverTransportPacket(tcpip.TransportProtocolNumber, *st
 	return stack.TransportPacketHandled
 }
 
-type stubLinkAddressCache struct {
-	stack.LinkAddressCache
-}
+var _ stack.LinkAddressCache = (*stubLinkAddressCache)(nil)
 
-func (*stubLinkAddressCache) CheckLocalAddress(tcpip.NICID, tcpip.NetworkProtocolNumber, tcpip.Address) tcpip.NICID {
-	return 0
-}
+type stubLinkAddressCache struct{}
 
-func (*stubLinkAddressCache) AddLinkAddress(tcpip.NICID, tcpip.Address, tcpip.LinkAddress) {
-}
+func (*stubLinkAddressCache) AddLinkAddress(tcpip.NICID, tcpip.Address, tcpip.LinkAddress) {}
 
 type stubNUDHandler struct {
 	probeCount        int
diff --git a/pkg/tcpip/stack/registration.go b/pkg/tcpip/stack/registration.go
index 68c113b6a..a73bc7007 100644
--- a/pkg/tcpip/stack/registration.go
+++ b/pkg/tcpip/stack/registration.go
@@ -829,10 +829,6 @@ type LinkAddressResolver interface {
 
 // A LinkAddressCache caches link addresses.
 type LinkAddressCache interface {
-	// CheckLocalAddress determines if the given local address exists, and if it
-	// does not exist.
-	CheckLocalAddress(nicID tcpip.NICID, protocol tcpip.NetworkProtocolNumber, addr tcpip.Address) tcpip.NICID
-
 	// AddLinkAddress adds a link address to the cache.
 	AddLinkAddress(nicID tcpip.NICID, addr tcpip.Address, linkAddr tcpip.LinkAddress)
 }