From dc3a7a39d462cd758d2c483dcb80c1b5ed57447d Mon Sep 17 00:00:00 2001
From: Junyu Lai <junyulai@google.com>
Date: Wed, 26 May 2021 12:23:56 +0000
Subject: [PATCH] Consider NetworkOffer is unneeded if it cannot satisfy the
 request

Currently, to prevent from network connect-teardown-loops that
caused by inaccurate reports, e.g. the provider always provides
a better network than the offer, the NetworkOffer is considered
needed if its provider is currently serving the request. This
is because there is no accurate way to know whether the offer is
corresponding to the network that is currently serving the
request.

However, if the offer cannot even satisfies the request, consider
the offer is needed does not make any sense. Since it can
never be the one that currently serving the request, nor be
the one that might beat current satisfier.

Test: android.net.NetworkProviderTest
Bug: 189074532
Change-Id: Ie3ea59f980c3767782b8e6b03e401c02f664f9bd
---
 .../src/com/android/server/ConnectivityService.java  | 12 ++++++------
 .../android/server/connectivity/NetworkOffer.java    |  2 +-
 tests/common/java/android/net/NetworkProviderTest.kt | 10 ++++------
 3 files changed, 11 insertions(+), 13 deletions(-)

diff --git a/service/src/com/android/server/ConnectivityService.java b/service/src/com/android/server/ConnectivityService.java
index 05bacfaeaf..f76ed85533 100644
--- a/service/src/com/android/server/ConnectivityService.java
+++ b/service/src/com/android/server/ConnectivityService.java
@@ -8322,13 +8322,13 @@ public class ConnectivityService extends IConnectivityManager.Stub
         // Second phase : deal with the active request (if any)
         if (null != activeRequest && activeRequest.isRequest()) {
             final boolean oldNeeded = offer.neededFor(activeRequest);
-            // An offer is needed if it is currently served by this provider or if this offer
-            // can beat the current satisfier.
+            // If an offer can satisfy the request, it is considered needed if it is currently
+            // served by this provider or if this offer can beat the current satisfier.
             final boolean currentlyServing = satisfier != null
-                    && satisfier.factorySerialNumber == offer.providerId;
-            final boolean newNeeded = (currentlyServing
-                    || (activeRequest.canBeSatisfiedBy(offer.caps)
-                            && networkRanker.mightBeat(activeRequest, satisfier, offer)));
+                    && satisfier.factorySerialNumber == offer.providerId
+                    && activeRequest.canBeSatisfiedBy(offer.caps);
+            final boolean newNeeded = currentlyServing
+                    || networkRanker.mightBeat(activeRequest, satisfier, offer);
             if (newNeeded != oldNeeded) {
                 if (newNeeded) {
                     offer.onNetworkNeeded(activeRequest);
diff --git a/service/src/com/android/server/connectivity/NetworkOffer.java b/service/src/com/android/server/connectivity/NetworkOffer.java
index 8285e7a8a3..1e975dde15 100644
--- a/service/src/com/android/server/connectivity/NetworkOffer.java
+++ b/service/src/com/android/server/connectivity/NetworkOffer.java
@@ -143,6 +143,6 @@ public class NetworkOffer implements NetworkRanker.Scoreable {
 
     @Override
     public String toString() {
-        return "NetworkOffer [ Score " + score + " ]";
+        return "NetworkOffer [ Score " + score + " Caps " + caps + "]";
     }
 }
diff --git a/tests/common/java/android/net/NetworkProviderTest.kt b/tests/common/java/android/net/NetworkProviderTest.kt
index 8cea12e0ea..ff5de1df33 100644
--- a/tests/common/java/android/net/NetworkProviderTest.kt
+++ b/tests/common/java/android/net/NetworkProviderTest.kt
@@ -315,9 +315,7 @@ class NetworkProviderTest {
                 LinkProperties(), scoreWeaker, config, provider) {}
         agent.register()
         agent.markConnected()
-        // TODO: The request is satisying by offer 2 instead of offer 1, thus it should not be
-        //  considered as needed.
-        offerCallback1.expectOnNetworkNeeded(ncFilter2)
+        offerCallback1.assertNoCallback()  // Still unneeded.
         offerCallback2.assertNoCallback()  // Still needed.
         offerCallback3.assertNoCallback()  // Still needed.
         offerCallback4.expectOnNetworkUnneeded(ncFilter4)
@@ -326,7 +324,7 @@ class NetworkProviderTest {
         // if a request is currently satisfied by the network provided by the same provider.
         // TODO: Consider offers with weaker score are unneeded.
         agent.sendNetworkScore(scoreStronger)
-        offerCallback1.assertNoCallback()
+        offerCallback1.assertNoCallback()  // Still unneeded.
         offerCallback2.assertNoCallback()  // Still needed.
         offerCallback3.assertNoCallback()  // Still needed.
         offerCallback4.assertNoCallback()  // Still unneeded.
@@ -334,7 +332,7 @@ class NetworkProviderTest {
         // Verify that offer callbacks cannot receive any event if offer is unregistered.
         provider2.unregisterNetworkOffer(offerCallback4)
         agent.unregister()
-        offerCallback1.assertNoCallback()  // Still needed.
+        offerCallback1.assertNoCallback()  // Still unneeded.
         offerCallback2.assertNoCallback()  // Still needed.
         offerCallback3.assertNoCallback()  // Still needed.
         // Since the agent is unregistered, and the offer has chance to satisfy the request,
@@ -344,7 +342,7 @@ class NetworkProviderTest {
         // Verify that offer callbacks cannot receive any event if provider is unregistered.
         mCm.unregisterNetworkProvider(provider)
         mCm.unregisterNetworkCallback(cb2)
-        offerCallback1.assertNoCallback()  // Should be unneeded if not unregistered.
+        offerCallback1.assertNoCallback()  // No callback since it is still unneeded.
         offerCallback2.assertNoCallback()  // Should be unneeded if not unregistered.
         offerCallback3.assertNoCallback()  // Should be unneeded if not unregistered.
         offerCallback4.assertNoCallback()  // Already unregistered.