Rename the *Nat64Prefix to *Nat64PrefixFromDns.

This just a rename with no functional changes at all. It is
preparation for supporting getting the NAT64 prefix from the
RA.

Bug: 150648313
Test: covered by existing ConnectivityServiceTest and Nat464XlatTest
Change-Id: Ia9a09a708870827b1e4cf068f930fa9542dd116c

services/core/java/com/android/server/ConnectivityService.java

@@ -3144,7 +3144,7 @@ public class ConnectivityService extends IConnectivityManager.Stub
             }
         }
 
-        nai.clatd.setNat64Prefix(prefix);
+        nai.clatd.setNat64PrefixFromDns(prefix);
         handleUpdateLinkProperties(nai, new LinkProperties(nai.linkProperties));
     }
 
@@ -5856,9 +5856,9 @@ public class ConnectivityService extends IConnectivityManager.Stub
             @NonNull LinkProperties oldLp) {
         int netId = networkAgent.network.netId;
 
-        // The NetworkAgentInfo does not know whether clatd is running on its network or not, or
+        // The NetworkAgent does not know whether clatd is running on its network or not, or whether
-        // whether there is a NAT64 prefix. Before we do anything else, make sure its LinkProperties
+        // a NAT64 prefix was discovered by the DNS resolver. Before we do anything else, make sure
-        // are accurate.
+        // the LinkProperties for the network are accurate.
         networkAgent.clatd.fixupLinkProperties(oldLp, newLp);
 
         updateInterfaces(newLp, oldLp, netId, networkAgent.networkCapabilities,

services/core/java/com/android/server/connectivity/Nat464Xlat.java

@@ -81,7 +81,7 @@ public class Nat464Xlat extends BaseNetworkObserver {
         RUNNING,      // start() called, and the stacked iface is known to be up.
     }
 
-    private IpPrefix mNat64Prefix;
+    private IpPrefix mNat64PrefixFromDns;
     private String mBaseIface;
     private String mIface;
     private Inet6Address mIPv6Address;
@@ -100,7 +100,7 @@ public class Nat464Xlat extends BaseNetworkObserver {
      * currently connected and where the NetworkAgent has not disabled 464xlat. It is the signal to
      * enable NAT64 prefix discovery.
      *
-     * @param network the NetworkAgentInfo corresponding to the network.
+     * @param nai the NetworkAgentInfo corresponding to the network.
      * @return true if the network requires clat, false otherwise.
      */
     @VisibleForTesting
@@ -180,7 +180,7 @@ public class Nat464Xlat extends BaseNetworkObserver {
 
         String addrStr = null;
         try {
-            addrStr = mNetd.clatdStart(baseIface, mNat64Prefix.toString());
+            addrStr = mNetd.clatdStart(baseIface, getNat64Prefix().toString());
         } catch (RemoteException | ServiceSpecificException e) {
             Slog.e(TAG, "Error starting clatd on " + baseIface + ": " + e);
         }
@@ -318,8 +318,12 @@ public class Nat464Xlat extends BaseNetworkObserver {
         }
     }
 
-    public void setNat64Prefix(IpPrefix nat64Prefix) {
+    private IpPrefix getNat64Prefix() {
-        mNat64Prefix = nat64Prefix;
+        return mNat64PrefixFromDns;
+    }
+
+    public void setNat64PrefixFromDns(IpPrefix prefix) {
+        mNat64PrefixFromDns = prefix;
     }
 
     /**
@@ -328,7 +332,7 @@ public class Nat464Xlat extends BaseNetworkObserver {
      * has no idea that 464xlat is running on top of it.
      */
     public void fixupLinkProperties(@NonNull LinkProperties oldLp, @NonNull LinkProperties lp) {
-        lp.setNat64Prefix(mNat64Prefix);
+        lp.setNat64Prefix(getNat64Prefix());
 
         if (!isRunning()) {
             return;

tests/net/java/com/android/server/connectivity/Nat464XlatTest.java

@@ -181,7 +181,7 @@ public class Nat464XlatTest {
         Nat464Xlat nat = makeNat464Xlat();
         ArgumentCaptor<LinkProperties> c = ArgumentCaptor.forClass(LinkProperties.class);
 
-        nat.setNat64Prefix(new IpPrefix(NAT64_PREFIX));
+        nat.setNat64PrefixFromDns(new IpPrefix(NAT64_PREFIX));
 
         // Start clat.
         nat.start();
@@ -222,7 +222,7 @@ public class Nat464XlatTest {
         ArgumentCaptor<LinkProperties> c = ArgumentCaptor.forClass(LinkProperties.class);
         InOrder inOrder = inOrder(mNetd, mConnectivity);
 
-        nat.setNat64Prefix(new IpPrefix(NAT64_PREFIX));
+        nat.setNat64PrefixFromDns(new IpPrefix(NAT64_PREFIX));
 
         nat.start();
 
@@ -309,7 +309,7 @@ public class Nat464XlatTest {
         Nat464Xlat nat = makeNat464Xlat();
         ArgumentCaptor<LinkProperties> c = ArgumentCaptor.forClass(LinkProperties.class);
 
-        nat.setNat64Prefix(new IpPrefix(NAT64_PREFIX));
+        nat.setNat64PrefixFromDns(new IpPrefix(NAT64_PREFIX));
 
         nat.start();
 
@@ -348,7 +348,7 @@ public class Nat464XlatTest {
     public void testStopBeforeClatdStarts() throws Exception {
         Nat464Xlat nat = makeNat464Xlat();
 
-        nat.setNat64Prefix(new IpPrefix(NAT64_PREFIX));
+        nat.setNat64PrefixFromDns(new IpPrefix(NAT64_PREFIX));
 
         nat.start();
 
@@ -380,7 +380,7 @@ public class Nat464XlatTest {
     public void testStopAndClatdNeverStarts() throws Exception {
         Nat464Xlat nat = makeNat464Xlat();
 
-        nat.setNat64Prefix(new IpPrefix(NAT64_PREFIX));
+        nat.setNat64PrefixFromDns(new IpPrefix(NAT64_PREFIX));
 
         nat.start();