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, 32 insertions, 33 deletions

diff --git a/pkg/tcpip/stack/nic.go b/pkg/tcpip/stack/nic.go
index a719058b4..0e8a23f00 100644
--- a/pkg/tcpip/stack/nic.go
+++ b/pkg/tcpip/stack/nic.go
@@ -148,37 +148,6 @@ func (n *NIC) setSpoofing(enable bool) {
 	n.mu.Unlock()
 }
 
-func (n *NIC) getMainNICAddress(protocol tcpip.NetworkProtocolNumber) (tcpip.AddressWithPrefix, *tcpip.Error) {
-	n.mu.RLock()
-	defer n.mu.RUnlock()
-
-	var r *referencedNetworkEndpoint
-
-	// Check for a primary endpoint.
-	if list, ok := n.primary[protocol]; ok {
-		for e := list.Front(); e != nil; e = e.Next() {
-			ref := e.(*referencedNetworkEndpoint)
-			if ref.getKind() == permanent && ref.tryIncRef() {
-				r = ref
-				break
-			}
-		}
-
-	}
-
-	if r == nil {
-		return tcpip.AddressWithPrefix{}, tcpip.ErrNoLinkAddress
-	}
-
-	addressWithPrefix := tcpip.AddressWithPrefix{
-		Address:   r.ep.ID().LocalAddress,
-		PrefixLen: r.ep.PrefixLen(),
-	}
-	r.decRef()
-
-	return addressWithPrefix, nil
-}
-
 // primaryEndpoint returns the primary endpoint of n for the given network
 // protocol.
 func (n *NIC) primaryEndpoint(protocol tcpip.NetworkProtocolNumber) *referencedNetworkEndpoint {
@@ -398,10 +367,12 @@ func (n *NIC) AddAddress(protocolAddress tcpip.ProtocolAddress, peb PrimaryEndpo
 	return err
 }
 
-// Addresses returns the addresses associated with this NIC.
-func (n *NIC) Addresses() []tcpip.ProtocolAddress {
+// AllAddresses returns all addresses (primary and non-primary) associated with
+// this NIC.
+func (n *NIC) AllAddresses() []tcpip.ProtocolAddress {
 	n.mu.RLock()
 	defer n.mu.RUnlock()
+
 	addrs := make([]tcpip.ProtocolAddress, 0, len(n.endpoints))
 	for nid, ref := range n.endpoints {
 		// Don't include expired or tempory endpoints to avoid confusion and
@@ -421,6 +392,34 @@ func (n *NIC) Addresses() []tcpip.ProtocolAddress {
 	return addrs
 }
 
+// PrimaryAddresses returns the primary addresses associated with this NIC.
+func (n *NIC) PrimaryAddresses() []tcpip.ProtocolAddress {
+	n.mu.RLock()
+	defer n.mu.RUnlock()
+
+	var addrs []tcpip.ProtocolAddress
+	for proto, list := range n.primary {
+		for e := list.Front(); e != nil; e = e.Next() {
+			ref := e.(*referencedNetworkEndpoint)
+			// Don't include expired or tempory endpoints to avoid confusion and
+			// prevent the caller from using those.
+			switch ref.getKind() {
+			case permanentExpired, temporary:
+				continue
+			}
+
+			addrs = append(addrs, tcpip.ProtocolAddress{
+				Protocol: proto,
+				AddressWithPrefix: tcpip.AddressWithPrefix{
+					Address:   ref.ep.ID().LocalAddress,
+					PrefixLen: ref.ep.PrefixLen(),
+				},
+			})
+		}
+	}
+	return addrs
+}
+
 // AddAddressRange adds a range of addresses to n, so that it starts accepting
 // packets targeted at the given addresses and network protocol. The range is
 // given by a subnet address, and all addresses contained in the subnet are