Allow NetworkAgent "immutable updates" to NetworkCapabilities

This patch loosens the validation checks when a NetworkAgent updates it
NetworkCapabilities: instead of checking that capabilities labeled as
"immutable" stay identical across updates, it is now accepted to change
immutable capabilities in a way that the new NetworkCapabilities
satisfies the old NetworkCapabilities.

This allows a NetworkAgent to update itself in order to match more
requests, but will still catch NetworkAgents that sends degradation
updates causing potentially requests to not match anymore.

Bug: 64125969
Test: runtest frameworks-net
Merged-In: I2a1b3f9c0be6415e40edc989d0c1b03b5631f7b1
Merged-In: I0ab76de59e87c46a6961229399ff7200bce49838
Merged-In: Ied592bf6112574399a1e808da337004e1c35f244
Merged-In: I01e287b4df82a53a522566d33b3166f7801badca
Merged-In: I7ee60daa9c4266e9b9179032815dd7267e06377f
Merged-In: I31ef741eb83d64c476e5930d5762514b5d4cb16f

(cherry picked from commit bae105a5ccd11430bab14721d1325e2303a673da)

Change-Id: I9d630d63336f4db69f3eb52faa8483f1b1e35d16

2 files changed, 7 insertions, 4 deletions

diff --git a/core/java/android/net/NetworkCapabilities.java b/core/java/android/net/NetworkCapabilities.java
index 0b9289345dbe..4bb884405360 100644
--- a/core/java/android/net/NetworkCapabilities.java
+++ b/core/java/android/net/NetworkCapabilities.java
@@ -770,7 +770,6 @@ public final class NetworkCapabilities implements Parcelable {
 
         StringJoiner joiner = new StringJoiner(", ");
 
-        // TODO: consider only enforcing that capabilities are not removed, allowing addition.
         // Ignore NOT_METERED being added or removed as it is effectively dynamic. http://b/63326103
         // TODO: properly support NOT_METERED as a mutable and requestable capability.
         final long mask = ~MUTABLE_CAPABILITIES & ~(1 << NET_CAPABILITY_NOT_METERED);
diff --git a/services/core/java/com/android/server/ConnectivityService.java b/services/core/java/com/android/server/ConnectivityService.java
index ac41079e5237..5110929bb947 100644
--- a/services/core/java/com/android/server/ConnectivityService.java
+++ b/services/core/java/com/android/server/ConnectivityService.java
@@ -4582,11 +4582,15 @@ public class ConnectivityService extends IConnectivityManager.Stub
      */
     private void updateCapabilities(
             int oldScore, NetworkAgentInfo nai, NetworkCapabilities networkCapabilities) {
-        // Sanity check: a NetworkAgent should not change its static capabilities or parameters.
-        if (nai.everConnected) {
+        // Once a NetworkAgent is connected, complain if some immutable capabilities are removed.
+        if (nai.everConnected &&
+                !nai.networkCapabilities.satisfiedByNetworkCapabilities(networkCapabilities)) {
+            // TODO: consider not complaining when a network agent degrade its capabilities if this
+            // does not cause any request (that is not a listen) currently matching that agent to
+            // stop being matched by the updated agent.
             String diff = nai.networkCapabilities.describeImmutableDifferences(networkCapabilities);
             if (!TextUtils.isEmpty(diff)) {
-                Slog.wtf(TAG, "BUG: " + nai + " changed immutable capabilities:" + diff);
+                Slog.wtf(TAG, "BUG: " + nai + " lost immutable capabilities:" + diff);
             }
         }