Return only primary addresses in Stack.NICInfo()

Non-primary addresses are used for endpoints created to accept multicast and
broadcast packets, as well as "helper" endpoints (0.0.0.0) that allow sending
packets when no proper address has been assigned yet (e.g., for DHCP). These
addresses are not real addresses from a user point of view and should not be
part of the NICInfo() value. Also see b/127321246 for more info.

This switches NICInfo() to call a new NIC.PrimaryAddresses() function. To still
allow an option to get all addresses (mostly for testing) I added
Stack.GetAllAddresses() and NIC.AllAddresses().

In addition, the return value for GetMainNICAddress() was changed for the case
where the NIC has no primary address. Instead of returning an error here,
it now returns an empty AddressWithPrefix() value. The rational for this
change is that it is a valid case for a NIC to have no primary addresses.

Lastly, I refactored the code based on the new additions.

PiperOrigin-RevId: 270971764

1 files changed, 26 insertions, 8 deletions

diff --git a/pkg/tcpip/stack/stack.go b/pkg/tcpip/stack/stack.go
index 1fe21b68e..f7ba3cb0f 100644
--- a/pkg/tcpip/stack/stack.go
+++ b/pkg/tcpip/stack/stack.go
@@ -738,7 +738,7 @@ func (s *Stack) NICInfo() map[tcpip.NICID]NICInfo {
 		nics[id] = NICInfo{
 			Name:              nic.name,
 			LinkAddress:       nic.linkEP.LinkAddress(),
-			ProtocolAddresses: nic.Addresses(),
+			ProtocolAddresses: nic.PrimaryAddresses(),
 			Flags:             flags,
 			MTU:               nic.linkEP.MTU(),
 			Stats:             nic.stats,
@@ -845,19 +845,37 @@ func (s *Stack) RemoveAddress(id tcpip.NICID, addr tcpip.Address) *tcpip.Error {
 	return tcpip.ErrUnknownNICID
 }
 
-// GetMainNICAddress returns the first primary address (and the subnet that
-// contains it) for the given NIC and protocol. Returns an arbitrary endpoint's
-// address if no primary addresses exist. Returns an error if the NIC doesn't
-// exist or has no endpoints.
+// AllAddresses returns a map of NICIDs to their protocol addresses (primary
+// and non-primary).
+func (s *Stack) AllAddresses() map[tcpip.NICID][]tcpip.ProtocolAddress {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+
+	nics := make(map[tcpip.NICID][]tcpip.ProtocolAddress)
+	for id, nic := range s.nics {
+		nics[id] = nic.AllAddresses()
+	}
+	return nics
+}
+
+// GetMainNICAddress returns the first primary address and prefix for the given
+// NIC and protocol. Returns an error if the NIC doesn't exist and an empty
+// value if the NIC doesn't have a primary address for the given protocol.
 func (s *Stack) GetMainNICAddress(id tcpip.NICID, protocol tcpip.NetworkProtocolNumber) (tcpip.AddressWithPrefix, *tcpip.Error) {
 	s.mu.RLock()
 	defer s.mu.RUnlock()
 
-	if nic, ok := s.nics[id]; ok {
-		return nic.getMainNICAddress(protocol)
+	nic, ok := s.nics[id]
+	if !ok {
+		return tcpip.AddressWithPrefix{}, tcpip.ErrUnknownNICID
 	}
 
-	return tcpip.AddressWithPrefix{}, tcpip.ErrUnknownNICID
+	for _, a := range nic.PrimaryAddresses() {
+		if a.Protocol == protocol {
+			return a.AddressWithPrefix, nil
+		}
+	}
+	return tcpip.AddressWithPrefix{}, nil
 }
 
 func (s *Stack) getRefEP(nic *NIC, localAddr tcpip.Address, netProto tcpip.NetworkProtocolNumber) (ref *referencedNetworkEndpoint) {