Add exponential backoff on the network level

Use the number of BSSIDs in the BSSID blocklist to determine how long we
should temporarily disable networks.

This check to re-enable networks is done every time before network
selection:
- if the elapsed time from now to the time the network was disabled is
greater than or equal to a timeout then re-enable the network.

The timeout calculated based on how many BSSIDs are in the BSSID
blocklist:
- 0 BSSID = 0ms (re-enable immediately)
- 1 BSSID = 5 minutes
- 2 BSSIDs = 10 minutes
- 3 BSSIDS = 20 minutes
...

Bug: 139287182
Test: atest FrameworksWifiTests
Change-Id: I009c5410898b09045b42adf4a1f48c05a268fba3

4 files changed, 105 insertions, 27 deletions

diff --git a/service/java/com/android/server/wifi/BssidBlocklistMonitor.java b/service/java/com/android/server/wifi/BssidBlocklistMonitor.java
index 7aab09cc5..2f0ba5ff1 100644
--- a/service/java/com/android/server/wifi/BssidBlocklistMonitor.java
+++ b/service/java/com/android/server/wifi/BssidBlocklistMonitor.java
@@ -283,6 +283,15 @@ public class BssidBlocklistMonitor {
     }
 
     /**
+     * @param ssid
+     * @return the number of BSSIDs currently in the blocklist for the |ssid|.
+     */
+    public int getNumBlockedBssidsForSsid(@NonNull String ssid) {
+        return (int) updateAndGetBssidBlocklistInternal()
+                .filter(entry -> ssid.equals(entry.ssid)).count();
+    }
+
+    /**
      * Gets the BSSIDs that are currently in the blocklist.
      * @return Set of BSSIDs currently in the blocklist
      */
diff --git a/service/java/com/android/server/wifi/WifiConfigManager.java b/service/java/com/android/server/wifi/WifiConfigManager.java
index 18b5562b3..e2dd98522 100644
--- a/service/java/com/android/server/wifi/WifiConfigManager.java
+++ b/service/java/com/android/server/wifi/WifiConfigManager.java
@@ -219,6 +219,12 @@ public class WifiConfigManager {
     private static final int SCAN_RESULT_MAXIMUM_AGE_MS = 40000;
 
     /**
+     * Maximum number of blocked BSSIDs per SSID used for calcualting the duration of temporarily
+     * disabling a network.
+     */
+    private static final int MAX_BLOCKED_BSSID_PER_NETWORK = 10;
+
+    /**
      * Maximum age of frequencies last seen to be included in pno scans. (30 days)
      */
     @VisibleForTesting
@@ -1892,7 +1898,16 @@ public class WifiConfigManager {
             long timeDifferenceMs =
                     mClock.getElapsedSinceBootMillis() - networkStatus.getDisableTime();
             int disableReason = networkStatus.getNetworkSelectionDisableReason();
-            long disableTimeoutMs = NETWORK_SELECTION_DISABLE_TIMEOUT_MS[disableReason];
+            int blockedBssids = Math.min(MAX_BLOCKED_BSSID_PER_NETWORK,
+                    mWifiInjector.getBssidBlocklistMonitor()
+                            .getNumBlockedBssidsForSsid(config.SSID));
+            // if no BSSIDs are blocked then we should keep trying to connect to something
+            long disableTimeoutMs = 0;
+            if (blockedBssids > 0) {
+                double multiplier = Math.pow(2.0, blockedBssids - 1.0);
+                disableTimeoutMs = (long) (NETWORK_SELECTION_DISABLE_TIMEOUT_MS[disableReason]
+                        * multiplier);
+            }
             if (timeDifferenceMs >= disableTimeoutMs) {
                 return updateNetworkSelectionStatus(
                         config, NetworkSelectionStatus.NETWORK_SELECTION_ENABLE);
diff --git a/tests/wifitests/src/com/android/server/wifi/BssidBlocklistMonitorTest.java b/tests/wifitests/src/com/android/server/wifi/BssidBlocklistMonitorTest.java
index 118e3d0df..068859c78 100644
--- a/tests/wifitests/src/com/android/server/wifi/BssidBlocklistMonitorTest.java
+++ b/tests/wifitests/src/com/android/server/wifi/BssidBlocklistMonitorTest.java
@@ -108,6 +108,16 @@ public class BssidBlocklistMonitorTest {
     }
 
     /**
+     * Verify getNumBlockedBssidsForSsid returns the correct number of blocked BSSIDs.
+     */
+    @Test
+    public void testGetNumBlockedBssidsForSsid() {
+        verifyAddMultipleBssidsToBlocklist();
+        assertEquals(2, mBssidBlocklistMonitor.getNumBlockedBssidsForSsid(TEST_SSID_1));
+        assertEquals(1, mBssidBlocklistMonitor.getNumBlockedBssidsForSsid(TEST_SSID_2));
+    }
+
+    /**
      * Verify that updateAndGetBssidBlocklist removes expired blocklist entries and clears
      * all failure counters for those networks.
      */
diff --git a/tests/wifitests/src/com/android/server/wifi/WifiConfigManagerTest.java b/tests/wifitests/src/com/android/server/wifi/WifiConfigManagerTest.java
index 203250e9f..dd1f46db4 100644
--- a/tests/wifitests/src/com/android/server/wifi/WifiConfigManagerTest.java
+++ b/tests/wifitests/src/com/android/server/wifi/WifiConfigManagerTest.java
@@ -113,6 +113,7 @@ public class WifiConfigManagerTest extends WifiBaseTest {
     private static final int TEST_FREQUENCY_1 = 2412;
     private static final int TEST_FREQUENCY_2 = 5180;
     private static final int TEST_FREQUENCY_3 = 5240;
+    private static final int MAX_BLOCKED_BSSID_PER_NETWORK = 10;
     private static final MacAddress TEST_RANDOMIZED_MAC =
             MacAddress.fromString("d2:11:19:34:a5:20");
     private static final int DATA_SUBID = 1;
@@ -139,6 +140,7 @@ public class WifiConfigManagerTest extends WifiBaseTest {
     @Mock private DeviceConfigFacade mDeviceConfigFacade;
     @Mock private CarrierNetworkConfig mCarrierNetworkConfig;
     @Mock private MacAddressUtil mMacAddressUtil;
+    @Mock private BssidBlocklistMonitor mBssidBlocklistMonitor;
 
     private MockResources mResources;
     private InOrder mContextConfigStoreMockOrder;
@@ -218,6 +220,7 @@ public class WifiConfigManagerTest extends WifiBaseTest {
         when(mWifiPermissionsUtil.checkNetworkSettingsPermission(anyInt())).thenReturn(true);
         when(mWifiPermissionsUtil.isDeviceOwner(anyInt(), any())).thenReturn(false);
         when(mWifiPermissionsUtil.isProfileOwner(anyInt(), any())).thenReturn(false);
+        when(mWifiInjector.getBssidBlocklistMonitor()).thenReturn(mBssidBlocklistMonitor);
         when(mWifiInjector.getWifiLastResortWatchdog()).thenReturn(mWifiLastResortWatchdog);
         when(mWifiInjector.getWifiLastResortWatchdog().shouldIgnoreSsidUpdate())
                 .thenReturn(false);
@@ -1152,6 +1155,36 @@ public class WifiConfigManagerTest extends WifiBaseTest {
         assertFalse(retrievedNetwork.getNetworkSelectionStatus().isNotRecommended());
     }
 
+    private void verifyDisableNetwork(NetworkUpdateResult result, int reason) {
+        // First set it to enabled.
+        verifyUpdateNetworkSelectionStatus(
+                result.getNetworkId(), NetworkSelectionStatus.NETWORK_SELECTION_ENABLE, 0);
+
+        int disableThreshold =
+                WifiConfigManager.NETWORK_SELECTION_DISABLE_THRESHOLD[reason];
+        for (int i = 1; i <= disableThreshold; i++) {
+            verifyUpdateNetworkSelectionStatus(result.getNetworkId(), reason, i);
+        }
+    }
+
+    private void verifyNetworkIsEnabledAfter(int networkId, long timeout) {
+        // try enabling this network 1 second earlier than the expected timeout. This
+        // should fail and the status should remain temporarily disabled.
+        when(mClock.getElapsedSinceBootMillis()).thenReturn(timeout - 1);
+        assertFalse(mWifiConfigManager.tryEnableNetwork(networkId));
+        NetworkSelectionStatus retrievedStatus =
+                mWifiConfigManager.getConfiguredNetwork(networkId).getNetworkSelectionStatus();
+        assertTrue(retrievedStatus.isNetworkTemporaryDisabled());
+
+        // Now advance time by the timeout for association rejection and ensure that the
+        // network is now enabled.
+        when(mClock.getElapsedSinceBootMillis()).thenReturn(timeout);
+        assertTrue(mWifiConfigManager.tryEnableNetwork(networkId));
+        retrievedStatus = mWifiConfigManager.getConfiguredNetwork(networkId)
+                .getNetworkSelectionStatus();
+        assertTrue(retrievedStatus.isNetworkEnabled());
+    }
+
     /**
      * Verifies the enabling of temporarily disabled network using
      * {@link WifiConfigManager#tryEnableNetwork(int)}.
@@ -1159,39 +1192,50 @@ public class WifiConfigManagerTest extends WifiBaseTest {
     @Test
     public void testTryEnableNetwork() {
         WifiConfiguration openNetwork = WifiConfigurationTestUtil.createOpenNetwork();
-
         NetworkUpdateResult result = verifyAddNetworkToWifiConfigManager(openNetwork);
 
-        // First set it to enabled.
-        verifyUpdateNetworkSelectionStatus(
-                result.getNetworkId(), NetworkSelectionStatus.NETWORK_SELECTION_ENABLE, 0);
-
-        // Now set it to temporarily disabled. The threshold for association rejection is 5, so
-        // disable it 5 times to actually mark it temporarily disabled.
-        int assocRejectReason = NetworkSelectionStatus.DISABLED_ASSOCIATION_REJECTION;
-        int assocRejectThreshold =
-                WifiConfigManager.NETWORK_SELECTION_DISABLE_THRESHOLD[assocRejectReason];
-        for (int i = 1; i <= assocRejectThreshold; i++) {
-            verifyUpdateNetworkSelectionStatus(result.getNetworkId(), assocRejectReason, i);
+        // Verify exponential backoff on the disable duration based on number of BSSIDs in the
+        // BSSID blocklist
+        long multiplier = 1;
+        int disableReason = NetworkSelectionStatus.DISABLED_ASSOCIATION_REJECTION;
+        long timeout = 0;
+        for (int i = 1; i < MAX_BLOCKED_BSSID_PER_NETWORK + 1; i++) {
+            verifyDisableNetwork(result, disableReason);
+            int numBssidsInBlocklist = i;
+            when(mBssidBlocklistMonitor.getNumBlockedBssidsForSsid(anyString()))
+                    .thenReturn(numBssidsInBlocklist);
+            timeout = WifiConfigManager.NETWORK_SELECTION_DISABLE_TIMEOUT_MS[disableReason]
+                    * multiplier;
+            multiplier *= 2;
+            verifyNetworkIsEnabledAfter(result.getNetworkId(),
+                    TEST_ELAPSED_UPDATE_NETWORK_SELECTION_TIME_MILLIS + timeout);
         }
 
-        // Now let's try enabling this network without changing the time, this should fail and the
-        // status remains temporarily disabled.
-        assertFalse(mWifiConfigManager.tryEnableNetwork(result.getNetworkId()));
-        NetworkSelectionStatus retrievedStatus =
-                mWifiConfigManager.getConfiguredNetwork(result.getNetworkId())
-                        .getNetworkSelectionStatus();
-        assertTrue(retrievedStatus.isNetworkTemporaryDisabled());
+        // Verify one last time that the disable duration is capped at some maximum.
+        verifyDisableNetwork(result, disableReason);
+        when(mBssidBlocklistMonitor.getNumBlockedBssidsForSsid(anyString()))
+                .thenReturn(MAX_BLOCKED_BSSID_PER_NETWORK + 1);
+        verifyNetworkIsEnabledAfter(result.getNetworkId(),
+                TEST_ELAPSED_UPDATE_NETWORK_SELECTION_TIME_MILLIS + timeout);
+    }
 
-        // Now advance time by the timeout for association rejection and ensure that the network
-        // is now enabled.
-        int assocRejectTimeout =
-                WifiConfigManager.NETWORK_SELECTION_DISABLE_TIMEOUT_MS[assocRejectReason];
-        when(mClock.getElapsedSinceBootMillis())
-                .thenReturn(TEST_ELAPSED_UPDATE_NETWORK_SELECTION_TIME_MILLIS + assocRejectTimeout);
+    /**
+     * Verifies that when no BSSIDs for a network is inside the BSSID blocklist then we
+     * re-enable a network.
+     */
+    @Test
+    public void testTryEnableNetworkNoBssidsInBlocklist() {
+        WifiConfiguration openNetwork = WifiConfigurationTestUtil.createOpenNetwork();
+        NetworkUpdateResult result = verifyAddNetworkToWifiConfigManager(openNetwork);
+        int disableReason = NetworkSelectionStatus.DISABLED_ASSOCIATION_REJECTION;
 
+        // Verify that with 0 BSSIDs in blocklist we enable the network immediately
+        verifyDisableNetwork(result, disableReason);
+        when(mBssidBlocklistMonitor.getNumBlockedBssidsForSsid(anyString())).thenReturn(0);
+        when(mClock.getElapsedSinceBootMillis())
+                .thenReturn(TEST_ELAPSED_UPDATE_NETWORK_SELECTION_TIME_MILLIS);
         assertTrue(mWifiConfigManager.tryEnableNetwork(result.getNetworkId()));
-        retrievedStatus =
+        NetworkSelectionStatus retrievedStatus =
                 mWifiConfigManager.getConfiguredNetwork(result.getNetworkId())
                         .getNetworkSelectionStatus();
         assertTrue(retrievedStatus.isNetworkEnabled());