Always accept discovered configurations from NDP

Before this change, the NDPDispatcher was allowed to "cancel" the
discovery of default routers/prefixes and auto-generate addresses.
No use case exists for this today so we drop this for now. If a
use case comes up in the future, we should instead invalidate the
discovered configuration through the stack instead of during
discovery.

PiperOrigin-RevId: 379327009

2 files changed, 12 insertions, 31 deletions

diff --git a/pkg/tcpip/network/ipv6/ndp.go b/pkg/tcpip/network/ipv6/ndp.go
index 851cd6e75..70b699b2e 100644
--- a/pkg/tcpip/network/ipv6/ndp.go
+++ b/pkg/tcpip/network/ipv6/ndp.go
@@ -215,12 +215,11 @@ type NDPDispatcher interface {
 	OnDuplicateAddressDetectionResult(tcpip.NICID, tcpip.Address, stack.DADResult)
 
 	// OnDefaultRouterDiscovered is called when a new default router is
-	// discovered. Implementations must return true if the newly discovered
-	// router should be remembered.
+	// discovered.
 	//
 	// This function is not permitted to block indefinitely. This function
 	// is also not permitted to call into the stack.
-	OnDefaultRouterDiscovered(tcpip.NICID, tcpip.Address) bool
+	OnDefaultRouterDiscovered(tcpip.NICID, tcpip.Address)
 
 	// OnDefaultRouterInvalidated is called when a discovered default router that
 	// was remembered is invalidated.
@@ -230,12 +229,10 @@ type NDPDispatcher interface {
 	OnDefaultRouterInvalidated(tcpip.NICID, tcpip.Address)
 
 	// OnOnLinkPrefixDiscovered is called when a new on-link prefix is discovered.
-	// Implementations must return true if the newly discovered on-link prefix
-	// should be remembered.
 	//
 	// This function is not permitted to block indefinitely. This function
 	// is also not permitted to call into the stack.
-	OnOnLinkPrefixDiscovered(tcpip.NICID, tcpip.Subnet) bool
+	OnOnLinkPrefixDiscovered(tcpip.NICID, tcpip.Subnet)
 
 	// OnOnLinkPrefixInvalidated is called when a discovered on-link prefix that
 	// was remembered is invalidated.
@@ -245,13 +242,11 @@ type NDPDispatcher interface {
 	OnOnLinkPrefixInvalidated(tcpip.NICID, tcpip.Subnet)
 
 	// OnAutoGenAddress is called when a new prefix with its autonomous address-
-	// configuration flag set is received and SLAAC was performed. Implementations
-	// may prevent the stack from assigning the address to the NIC by returning
-	// false.
+	// configuration flag set is received and SLAAC was performed.
 	//
 	// This function is not permitted to block indefinitely. It must not
 	// call functions on the stack itself.
-	OnAutoGenAddress(tcpip.NICID, tcpip.AddressWithPrefix) bool
+	OnAutoGenAddress(tcpip.NICID, tcpip.AddressWithPrefix)
 
 	// OnAutoGenAddressDeprecated is called when an auto-generated address (SLAAC)
 	// is deprecated, but is still considered valid. Note, if an address is
@@ -848,11 +843,7 @@ func (ndp *ndpState) rememberDefaultRouter(ip tcpip.Address, rl time.Duration) {
 	}
 
 	// Inform the integrator when we discovered a default router.
-	if !ndpDisp.OnDefaultRouterDiscovered(ndp.ep.nic.ID(), ip) {
-		// Informed by the integrator to not remember the router, do
-		// nothing further.
-		return
-	}
+	ndpDisp.OnDefaultRouterDiscovered(ndp.ep.nic.ID(), ip)
 
 	state := defaultRouterState{
 		invalidationJob: ndp.ep.protocol.stack.NewJob(&ndp.ep.mu, func() {
@@ -878,11 +869,7 @@ func (ndp *ndpState) rememberOnLinkPrefix(prefix tcpip.Subnet, l time.Duration)
 	}
 
 	// Inform the integrator when we discovered an on-link prefix.
-	if !ndpDisp.OnOnLinkPrefixDiscovered(ndp.ep.nic.ID(), prefix) {
-		// Informed by the integrator to not remember the prefix, do
-		// nothing further.
-		return
-	}
+	ndpDisp.OnOnLinkPrefixDiscovered(ndp.ep.nic.ID(), prefix)
 
 	state := onLinkPrefixState{
 		invalidationJob: ndp.ep.protocol.stack.NewJob(&ndp.ep.mu, func() {
@@ -1096,16 +1083,13 @@ func (ndp *ndpState) addAndAcquireSLAACAddr(addr tcpip.AddressWithPrefix, config
 		return nil
 	}
 
-	if !ndpDisp.OnAutoGenAddress(ndp.ep.nic.ID(), addr) {
-		// Informed by the integrator not to add the address.
-		return nil
-	}
-
 	addressEndpoint, err := ndp.ep.addAndAcquirePermanentAddressLocked(addr, stack.FirstPrimaryEndpoint, configType, deprecated)
 	if err != nil {
 		panic(fmt.Sprintf("ndp: error when adding SLAAC address %+v: %s", addr, err))
 	}
 
+	ndpDisp.OnAutoGenAddress(ndp.ep.nic.ID(), addr)
+
 	return addressEndpoint
 }
 
diff --git a/pkg/tcpip/network/ipv6/ndp_test.go b/pkg/tcpip/network/ipv6/ndp_test.go
index 3438deb79..7b4774abb 100644
--- a/pkg/tcpip/network/ipv6/ndp_test.go
+++ b/pkg/tcpip/network/ipv6/ndp_test.go
@@ -42,24 +42,21 @@ type testNDPDispatcher struct {
 func (*testNDPDispatcher) OnDuplicateAddressDetectionResult(tcpip.NICID, tcpip.Address, stack.DADResult) {
 }
 
-func (t *testNDPDispatcher) OnDefaultRouterDiscovered(_ tcpip.NICID, addr tcpip.Address) bool {
+func (t *testNDPDispatcher) OnDefaultRouterDiscovered(_ tcpip.NICID, addr tcpip.Address) {
 	t.addr = addr
-	return true
 }
 
 func (t *testNDPDispatcher) OnDefaultRouterInvalidated(_ tcpip.NICID, addr tcpip.Address) {
 	t.addr = addr
 }
 
-func (*testNDPDispatcher) OnOnLinkPrefixDiscovered(tcpip.NICID, tcpip.Subnet) bool {
-	return false
+func (*testNDPDispatcher) OnOnLinkPrefixDiscovered(tcpip.NICID, tcpip.Subnet) {
 }
 
 func (*testNDPDispatcher) OnOnLinkPrefixInvalidated(tcpip.NICID, tcpip.Subnet) {
 }
 
-func (*testNDPDispatcher) OnAutoGenAddress(tcpip.NICID, tcpip.AddressWithPrefix) bool {
-	return false
+func (*testNDPDispatcher) OnAutoGenAddress(tcpip.NICID, tcpip.AddressWithPrefix) {
 }
 
 func (*testNDPDispatcher) OnAutoGenAddressDeprecated(tcpip.NICID, tcpip.AddressWithPrefix) {