ClientModeImpl: Disconnect if network is marked metered

1) If the network is marked metered from unmetered/none by either the
app or user post connection, trigger a disconnect to ensure that all
apps re-read the meteredness of the network (when connected back again).
2) If the network is marked unmetered/none from metered by either the
app or user post connection, just update the network capabilities.

Also,
a) Modified the onNetworkUpdated() WifiConfigManager callback to include
both the previous and new config to help clients compare what has changed.
b) If a suggestion is being updated and the network is cached in
WifiConfigManager (either because we're connected to that or was connectable
in the recent past), trigger an immediate update of configuration. This ensures
that any metered changes take effect immediately.
c) Similarly for passpoint networks cached in WifiConfigManager, trigger
an immediate of configuration. This ensures that any metered changes take
effect immediately.
d) Removed update of existing config in NetworkSuggestionNominator which
is redundant with (b)
e) Ensure that all configs sent out from WifiConfigManager callbacks
have their passwords masked to ensure they're not accidentally sent out
of the stack.
f) Added a shell command to just add/update network config without
triggering a connect immediately.

Bug: 153127005
Test: atest com.android.server.wifi
Test: Manual steps
Suggestion Metered change (unmetered->metered):
adb shell cmd wifi add-suggestion <ssid> open
adb shell cmd wifi start-scan
adb shell cmd wifi status -> connected as unmetered
adb shell cmd wifi add-suggestion GoogleGuest open -m
adb shell cmd wifi status -> disconnected
adb shell cmd wifi status -> connected back as metered
adb shell cmd wifi add-suggestion GoogleGuest open
adb shell cmd wifi status -> remained connected, but changed to unmetered

Saved network Metered change (unmetered->metered):
adb shell cmd wifi add-network <ssid> open
adb shell cmd wifi start-scan
adb shell cmd wifi status -> connected as unmetered
adb shell cmd wifi add-network GoogleGuest open -m
adb shell cmd wifi status -> disconnected
adb shell cmd wifi status -> connected back as metered
adb shell cmd wifi add-network GoogleGuest open
adb shell cmd wifi status -> remained connected, but changed to unmetered

Change-Id: Id313a302dc529fcafa8e2d1a8442f748896cab89

9 files changed, 178 insertions, 52 deletions

diff --git a/service/java/com/android/server/wifi/ClientModeImpl.java b/service/java/com/android/server/wifi/ClientModeImpl.java
index 85eeb22fa..2b391050c 100644
--- a/service/java/com/android/server/wifi/ClientModeImpl.java
+++ b/service/java/com/android/server/wifi/ClientModeImpl.java
@@ -1105,12 +1105,31 @@ public class ClientModeImpl extends StateMachine {
             mWifiNative.removeNetworkCachedData(config.networkId);
         }
 
-
         @Override
-        public void onNetworkUpdated(WifiConfiguration config) {
-            // User might have changed meteredOverride, so update capabilities
-            if (config.networkId == mLastNetworkId) {
-                updateCapabilities();
+        public void onNetworkUpdated(WifiConfiguration newConfig, WifiConfiguration oldConfig) {
+            // Check if user/app change meteredOverride for connected network.
+            if (newConfig.networkId != mLastNetworkId
+                    || newConfig.meteredOverride == oldConfig.meteredOverride) {
+                // nothing to do.
+                return;
+            }
+            boolean isMetered = WifiConfiguration.isMetered(newConfig, mWifiInfo);
+            boolean wasMetered = WifiConfiguration.isMetered(oldConfig, mWifiInfo);
+            if (isMetered == wasMetered) {
+                // no meteredness change, nothing to do.
+                if (mVerboseLoggingEnabled) {
+                    Log.v(TAG, "User/app changed meteredOverride, but no change in meteredness");
+                }
+                return;
+            }
+            // If unmetered->metered trigger a disconnect.
+            // If metered->unmetered update capabilities.
+            if (isMetered) {
+                Log.w(TAG, "Network marked metered, triggering disconnect");
+                sendMessage(CMD_DISCONNECT);
+            } else {
+                Log.i(TAG, "Network marked unmetered, triggering capabilities update");
+                updateCapabilities(newConfig);
             }
         }
 
@@ -4446,10 +4465,14 @@ public class ClientModeImpl extends StateMachine {
     }
 
     private void updateCapabilities(WifiConfiguration currentWifiConfiguration) {
+        updateCapabilities(getCapabilities(currentWifiConfiguration));
+    }
+
+    private void updateCapabilities(NetworkCapabilities networkCapabilities) {
         if (mNetworkAgent == null) {
             return;
         }
-        mNetworkAgent.sendNetworkCapabilities(getCapabilities(currentWifiConfiguration));
+        mNetworkAgent.sendNetworkCapabilities(networkCapabilities);
     }
 
     private void handleEapAuthFailure(int networkId, int errorCode) {
diff --git a/service/java/com/android/server/wifi/NetworkSuggestionNominator.java b/service/java/com/android/server/wifi/NetworkSuggestionNominator.java
index a8d181fdc..c4fd6a908 100644
--- a/service/java/com/android/server/wifi/NetworkSuggestionNominator.java
+++ b/service/java/com/android/server/wifi/NetworkSuggestionNominator.java
@@ -196,19 +196,6 @@ public class NetworkSuggestionNominator implements WifiNetworkSelector.NetworkNo
                 if (matchingExtNetworkSuggestionsFromSamePackage.isEmpty()) {
                     continue;
                 }
-                ExtendedWifiNetworkSuggestion matchingExtNetworkSuggestion =
-                        matchingExtNetworkSuggestionsFromSamePackage.stream().findFirst().get();
-                // Update the WifiConfigManager with the latest WifiConfig
-                WifiConfiguration config =
-                        matchingExtNetworkSuggestion.createInternalWifiConfiguration();
-                NetworkUpdateResult result = mWifiConfigManager.addOrUpdateNetwork(
-                        config,
-                        matchingExtNetworkSuggestion.perAppInfo.uid,
-                        matchingExtNetworkSuggestion.perAppInfo.packageName);
-                if (result.isSuccess()) {
-                    wCmConfiguredNetwork = mWifiConfigManager.getConfiguredNetwork(
-                            result.getNetworkId());
-                }
                 // If the network is currently blacklisted, ignore.
                 if (!wCmConfiguredNetwork.getNetworkSelectionStatus().isNetworkEnabled()
                         && !mWifiConfigManager.tryEnableNetwork(wCmConfiguredNetwork.networkId)) {
diff --git a/service/java/com/android/server/wifi/WifiConfigManager.java b/service/java/com/android/server/wifi/WifiConfigManager.java
index 4e4f51d60..91ebe6bc7 100644
--- a/service/java/com/android/server/wifi/WifiConfigManager.java
+++ b/service/java/com/android/server/wifi/WifiConfigManager.java
@@ -107,6 +107,8 @@ public class WifiConfigManager {
     /**
      * Interface for other modules to listen to the network updated
      * events.
+     * Note: Credentials are masked to avoid accidentally sending credentials outside the stack.
+     * Use WifiConfigManager#getConfiguredNetworkWithPassword() to retrieve credentials.
      */
     public interface OnNetworkUpdateListener {
         /**
@@ -131,8 +133,12 @@ public class WifiConfigManager {
         void onNetworkTemporarilyDisabled(@NonNull WifiConfiguration config, int disableReason);
         /**
          * Invoked on network being updated.
+         *
+         * @param newConfig Updated WifiConfiguration object.
+         * @param oldConfig Prev WifiConfiguration object.
          */
-        void onNetworkUpdated(@NonNull WifiConfiguration config);
+        void onNetworkUpdated(
+                @NonNull WifiConfiguration newConfig, @NonNull WifiConfiguration oldConfig);
     }
     /**
      * Max size of scan details to cache in {@link #mScanDetailCaches}.
@@ -1323,9 +1329,9 @@ public class WifiConfigManager {
             Log.e(TAG, "Cannot add/update network before store is read!");
             return new NetworkUpdateResult(WifiConfiguration.INVALID_NETWORK_ID);
         }
+        WifiConfiguration existingConfig = getInternalConfiguredNetwork(config);
         if (!config.isEphemeral()) {
             // Removes the existing ephemeral network if it exists to add this configuration.
-            WifiConfiguration existingConfig = getConfiguredNetwork(config.getKey());
             if (existingConfig != null && existingConfig.isEphemeral()) {
                 // In this case, new connection for this config won't happen because same
                 // network is already registered as an ephemeral network.
@@ -1352,11 +1358,13 @@ public class WifiConfigManager {
         }
 
         for (OnNetworkUpdateListener listener : mListeners) {
-            WifiConfiguration configForListener = new WifiConfiguration(newConfig);
             if (result.isNewNetwork()) {
-                listener.onNetworkAdded(configForListener);
+                listener.onNetworkAdded(
+                        createExternalWifiConfiguration(newConfig, true, Process.WIFI_UID));
             } else {
-                listener.onNetworkUpdated(configForListener);
+                listener.onNetworkUpdated(
+                        createExternalWifiConfiguration(newConfig, true, Process.WIFI_UID),
+                        createExternalWifiConfiguration(existingConfig, true, Process.WIFI_UID));
             }
         }
         return result;
@@ -1445,8 +1453,8 @@ public class WifiConfigManager {
             saveToStore(true);
         }
         for (OnNetworkUpdateListener listener : mListeners) {
-            WifiConfiguration configForListener = new WifiConfiguration(config);
-            listener.onNetworkRemoved(configForListener);
+            listener.onNetworkRemoved(
+                    createExternalWifiConfiguration(config, true, Process.WIFI_UID));
         }
         return true;
     }
@@ -1606,8 +1614,8 @@ public class WifiConfigManager {
         // Clear out all the disable reason counters.
         status.clearDisableReasonCounter();
         for (OnNetworkUpdateListener listener : mListeners) {
-            WifiConfiguration configForListener = new WifiConfiguration(config);
-            listener.onNetworkEnabled(configForListener);
+            listener.onNetworkEnabled(
+                    createExternalWifiConfiguration(config, true, Process.WIFI_UID));
         }
     }
 
@@ -1623,8 +1631,8 @@ public class WifiConfigManager {
         status.setDisableTime(mClock.getElapsedSinceBootMillis());
         status.setNetworkSelectionDisableReason(disableReason);
         for (OnNetworkUpdateListener listener : mListeners) {
-            WifiConfiguration configForListener = new WifiConfiguration(config);
-            listener.onNetworkTemporarilyDisabled(configForListener, disableReason);
+            listener.onNetworkTemporarilyDisabled(
+                    createExternalWifiConfiguration(config, true, Process.WIFI_UID), disableReason);
         }
     }
 
@@ -1641,7 +1649,8 @@ public class WifiConfigManager {
         status.setNetworkSelectionDisableReason(disableReason);
         for (OnNetworkUpdateListener listener : mListeners) {
             WifiConfiguration configForListener = new WifiConfiguration(config);
-            listener.onNetworkPermanentlyDisabled(configForListener, disableReason);
+            listener.onNetworkPermanentlyDisabled(
+                    createExternalWifiConfiguration(config, true, Process.WIFI_UID), disableReason);
         }
     }
 
diff --git a/service/java/com/android/server/wifi/WifiConnectivityManager.java b/service/java/com/android/server/wifi/WifiConnectivityManager.java
index 712dbcd7f..59b3e3d86 100644
--- a/service/java/com/android/server/wifi/WifiConnectivityManager.java
+++ b/service/java/com/android/server/wifi/WifiConnectivityManager.java
@@ -709,7 +709,7 @@ public class WifiConnectivityManager {
             updateScan();
         }
         @Override
-        public void onNetworkUpdated(WifiConfiguration config) {
+        public void onNetworkUpdated(WifiConfiguration newConfig, WifiConfiguration oldConfig) {
             updateScan();
         }
         @Override
diff --git a/service/java/com/android/server/wifi/WifiHealthMonitor.java b/service/java/com/android/server/wifi/WifiHealthMonitor.java
index 123c576bd..0b0c68d88 100644
--- a/service/java/com/android/server/wifi/WifiHealthMonitor.java
+++ b/service/java/com/android/server/wifi/WifiHealthMonitor.java
@@ -965,7 +965,7 @@ public class WifiHealthMonitor {
         }
 
         @Override
-        public void onNetworkUpdated(WifiConfiguration config) {
+        public void onNetworkUpdated(WifiConfiguration newConfig, WifiConfiguration oldConfig) {
         }
     }
 
diff --git a/service/java/com/android/server/wifi/WifiNetworkSuggestionsManager.java b/service/java/com/android/server/wifi/WifiNetworkSuggestionsManager.java
index 19c9da156..ef05ccb58 100644
--- a/service/java/com/android/server/wifi/WifiNetworkSuggestionsManager.java
+++ b/service/java/com/android/server/wifi/WifiNetworkSuggestionsManager.java
@@ -264,6 +264,17 @@ public class WifiNetworkSuggestionsManager {
                     && TextUtils.equals(perAppInfo.packageName, other.perAppInfo.packageName);
         }
 
+        /**
+         * Helper method to set the carrier Id.
+         */
+        public void setCarrierId(int carrierId) {
+            if (wns.passpointConfiguration == null) {
+                wns.wifiConfiguration.carrierId = carrierId;
+            } else {
+                wns.passpointConfiguration.setCarrierId(carrierId);
+            }
+        }
+
         @Override
         public String toString() {
             return new StringBuilder(wns.toString())
@@ -794,6 +805,29 @@ public class WifiNetworkSuggestionsManager {
                         Collectors.toSet()));
     }
 
+    private void updateWifiConfigInWcmIfPresent(
+            WifiConfiguration newConfig, int uid, String packageName) {
+        WifiConfiguration configInWcm =
+                mWifiConfigManager.getConfiguredNetwork(newConfig.getKey());
+        if (configInWcm == null) return;
+        // !suggestion
+        if (!configInWcm.fromWifiNetworkSuggestion) return;
+        // is suggestion from same app.
+        if (configInWcm.creatorUid != uid
+                || !TextUtils.equals(configInWcm.creatorName, packageName)) {
+            return;
+        }
+        NetworkUpdateResult result = mWifiConfigManager.addOrUpdateNetwork(
+                newConfig, uid, packageName);
+        if (!result.isSuccess()) {
+            Log.e(TAG, "Failed to update config in WifiConfigManager");
+        } else {
+            if (mVerboseLoggingEnabled) {
+                Log.v(TAG, "Updated config in WifiConfigManager");
+            }
+        }
+    }
+
     /**
      * Add the provided list of network suggestions from the corresponding app's active list.
      */
@@ -862,10 +896,20 @@ public class WifiNetworkSuggestionsManager {
         }
 
         for (ExtendedWifiNetworkSuggestion ewns: extNetworkSuggestions) {
-            if (ewns.wns.passpointConfiguration == null) {
-                if (carrierId != TelephonyManager.UNKNOWN_CARRIER_ID) {
-                    ewns.wns.wifiConfiguration.carrierId = carrierId;
+            if (carrierId != TelephonyManager.UNKNOWN_CARRIER_ID) {
+                ewns.setCarrierId(carrierId);
+            }
+            // If network has no IMSI protection and user didn't approve exemption, make it initial
+            // auto join disabled
+            if (isSimBasedSuggestion(ewns)) {
+                int subId = mTelephonyUtil.getMatchingSubId(getCarrierIdFromSuggestion(ewns));
+                if (!(mTelephonyUtil.requiresImsiEncryption(subId)
+                        || hasUserApprovedImsiPrivacyExemptionForCarrier(
+                        getCarrierIdFromSuggestion(ewns)))) {
+                    ewns.isAutojoinEnabled = false;
                 }
+            }
+            if (ewns.wns.passpointConfiguration == null) {
                 if (ewns.wns.wifiConfiguration.isEnterprise()) {
                     if (!mWifiKeyStore.updateNetworkKeys(ewns.wns.wifiConfiguration, null)) {
                         Log.e(TAG, "Enterprise network install failure for SSID: "
@@ -873,11 +917,13 @@ public class WifiNetworkSuggestionsManager {
                         continue;
                     }
                 }
+                // If we have a config in WifiConfigManager for this suggestion, update
+                // WifiConfigManager with the latest WifiConfig.
+                // Note: Similar logic is present in PasspointManager for passpoint networks.
+                updateWifiConfigInWcmIfPresent(
+                        ewns.createInternalWifiConfiguration(), uid, packageName);
                 addToScanResultMatchInfoMap(ewns);
             } else {
-                if (carrierId != TelephonyManager.UNKNOWN_CARRIER_ID) {
-                    ewns.wns.passpointConfiguration.setCarrierId(carrierId);
-                }
                 ewns.wns.passpointConfiguration.setAutojoinEnabled(ewns.isAutojoinEnabled);
                 // Install Passpoint config, if failure, ignore that suggestion
                 if (!mWifiInjector.getPasspointManager().addOrUpdateProvider(
@@ -889,16 +935,6 @@ public class WifiNetworkSuggestionsManager {
                 }
                 addToPasspointInfoMap(ewns);
             }
-            // If network has no IMSI protection and user didn't approve exemption, make it initial
-            // auto join disabled
-            if (isSimBasedSuggestion(ewns)) {
-                int subId = mTelephonyUtil.getMatchingSubId(getCarrierIdFromSuggestion(ewns));
-                if (!(mTelephonyUtil.requiresImsiEncryption(subId)
-                        || hasUserApprovedImsiPrivacyExemptionForCarrier(
-                                getCarrierIdFromSuggestion(ewns)))) {
-                    ewns.isAutojoinEnabled = false;
-                }
-            }
             perAppInfo.extNetworkSuggestions.remove(ewns);
             perAppInfo.extNetworkSuggestions.add(ewns);
         }
diff --git a/service/java/com/android/server/wifi/WifiShellCommand.java b/service/java/com/android/server/wifi/WifiShellCommand.java
index cbab50cd4..37f8d10c8 100644
--- a/service/java/com/android/server/wifi/WifiShellCommand.java
+++ b/service/java/com/android/server/wifi/WifiShellCommand.java
@@ -25,6 +25,8 @@ import android.content.Context;
 import android.content.pm.ParceledListSlice;
 import android.net.ConnectivityManager;
 import android.net.MacAddress;
+import android.net.Network;
+import android.net.NetworkCapabilities;
 import android.net.NetworkRequest;
 import android.net.wifi.IActionListener;
 import android.net.wifi.ScanResult;
@@ -77,6 +79,7 @@ public class WifiShellCommand extends BasicShellCommandHandler {
     // However, these do perform permission checks in the corresponding WifiService methods.
     private static final String[] NON_PRIVILEGED_COMMANDS = {
             "add-suggestion",
+            "add-network",
             "connect-network",
             "forget-network",
             "get-country-code",
@@ -410,6 +413,28 @@ public class WifiShellCommand extends BasicShellCommandHandler {
                     countDownLatch.await(500, TimeUnit.MILLISECONDS);
                     break;
                 }
+                case "add-network": {
+                    CountDownLatch countDownLatch = new CountDownLatch(1);
+                    IActionListener.Stub actionListener = new IActionListener.Stub() {
+                        @Override
+                        public void onSuccess() throws RemoteException {
+                            pw.println("Save successful");
+                            countDownLatch.countDown();
+                        }
+
+                        @Override
+                        public void onFailure(int i) throws RemoteException {
+                            pw.println("Save failed");
+                            countDownLatch.countDown();
+                        }
+                    };
+                    mWifiService.save(
+                            buildWifiConfiguration(pw), new Binder(), actionListener,
+                            actionListener.hashCode());
+                    // wait for status.
+                    countDownLatch.await(500, TimeUnit.MILLISECONDS);
+                    break;
+                }
                 case "forget-network": {
                     String networkId = getNextArgRequired();
                     CountDownLatch countDownLatch = new CountDownLatch(1);
@@ -444,7 +469,11 @@ public class WifiShellCommand extends BasicShellCommandHandler {
                     if (wifiEnabled) {
                         if (info.getSupplicantState() == SupplicantState.COMPLETED) {
                             pw.println("Wifi is connected to " + info.getSSID());
-                            pw.println("Connection Details: " + info);
+                            pw.println("WifiInfo: " + info);
+                            Network network = mWifiService.getCurrentNetwork();
+                            NetworkCapabilities capabilities =
+                                    mConnectivityManager.getNetworkCapabilities(network);
+                            pw.println("NetworkCapabilities: " + capabilities);
                         } else {
                             pw.println("Wifi is not connected");
                         }
@@ -762,7 +791,18 @@ public class WifiShellCommand extends BasicShellCommandHandler {
         pw.println("  list-networks");
         pw.println("    Lists the saved networks");
         pw.println("  connect-network <ssid> open|owe|wpa2|wpa3 [<passphrase>] [-m]");
-        pw.println("    Connect to a network with provided params and save");
+        pw.println("    Connect to a network with provided params and add to saved networks list");
+        pw.println("    <ssid> - SSID of the network");
+        pw.println("    open|owe|wpa2|wpa3 - Security type of the network.");
+        pw.println("        - Use 'open' or 'owe' for networks with no passphrase");
+        pw.println("           - 'open' - Open networks (Most prevalent)");
+        pw.println("           - 'owe' - Enhanced open networks");
+        pw.println("        - Use 'wpa2' or 'wpa3' for networks with passphrase");
+        pw.println("           - 'wpa2' - WPA-2 PSK networks (Most prevalent)");
+        pw.println("           - 'wpa3' - WPA-3 PSK networks");
+        pw.println("    -m - Mark the network metered.");
+        pw.println("  add-network <ssid> open|owe|wpa2|wpa3 [<passphrase>] [-m]");
+        pw.println("    Add/update saved network with provided params");
         pw.println("    <ssid> - SSID of the network");
         pw.println("    open|owe|wpa2|wpa3 - Security type of the network.");
         pw.println("        - Use 'open' or 'owe' for networks with no passphrase");
diff --git a/service/java/com/android/server/wifi/hotspot2/PasspointManager.java b/service/java/com/android/server/wifi/hotspot2/PasspointManager.java
index d3e405b1d..14f326ef0 100644
--- a/service/java/com/android/server/wifi/hotspot2/PasspointManager.java
+++ b/service/java/com/android/server/wifi/hotspot2/PasspointManager.java
@@ -51,6 +51,7 @@ import android.util.Log;
 import android.util.Pair;
 
 import com.android.server.wifi.Clock;
+import com.android.server.wifi.NetworkUpdateResult;
 import com.android.server.wifi.WifiConfigManager;
 import com.android.server.wifi.WifiConfigStore;
 import com.android.server.wifi.WifiInjector;
@@ -375,6 +376,30 @@ public class PasspointManager {
         }
     }
 
+    private void updateWifiConfigInWcmIfPresent(
+            WifiConfiguration newConfig, int uid, String packageName, boolean isFromSuggestion) {
+        WifiConfiguration configInWcm =
+                mWifiConfigManager.getConfiguredNetwork(newConfig.getKey());
+        if (configInWcm == null) return;
+        // suggestion != saved
+        if (isFromSuggestion != configInWcm.fromWifiNetworkSuggestion) return;
+        // is suggestion from same app.
+        if (isFromSuggestion
+                && (configInWcm.creatorUid != uid
+                || !TextUtils.equals(configInWcm.creatorName, packageName))) {
+            return;
+        }
+        NetworkUpdateResult result = mWifiConfigManager.addOrUpdateNetwork(
+                newConfig, uid, packageName);
+        if (!result.isSuccess()) {
+            Log.e(TAG, "Failed to update config in WifiConfigManager");
+        } else {
+            if (mVerboseLoggingEnabled) {
+                Log.v(TAG, "Updated config in WifiConfigManager");
+            }
+        }
+    }
+
     /**
      * Add or update a Passpoint provider with the given configuration.
      *
@@ -423,7 +448,7 @@ public class PasspointManager {
         if (mProviders.containsKey(config.getUniqueId())) {
             PasspointProvider old = mProviders.get(config.getUniqueId());
             // If new profile is from suggestion and from a different App, ignore new profile,
-            // return true.
+            // return false.
             // If from same app, update it.
             if (isFromSuggestion && !old.getPackageName().equals(packageName)) {
                 newProvider.uninstallCertsAndKeys();
@@ -437,6 +462,10 @@ public class PasspointManager {
             if (!old.equals(newProvider)) {
                 mWifiConfigManager.removePasspointConfiguredNetwork(
                         newProvider.getWifiConfig().getKey());
+            } else {
+                // If there is a config cached in WifiConfigManager, update it with new info.
+                updateWifiConfigInWcmIfPresent(
+                        newProvider.getWifiConfig(), uid, packageName, isFromSuggestion);
             }
         }
         newProvider.enableVerboseLogging(mVerboseLoggingEnabled ? 1 : 0);
diff --git a/service/java/com/android/server/wifi/hotspot2/PasspointNetworkNominateHelper.java b/service/java/com/android/server/wifi/hotspot2/PasspointNetworkNominateHelper.java
index 27c8331ec..22ce2f07a 100644
--- a/service/java/com/android/server/wifi/hotspot2/PasspointNetworkNominateHelper.java
+++ b/service/java/com/android/server/wifi/hotspot2/PasspointNetworkNominateHelper.java
@@ -202,6 +202,8 @@ public class PasspointNetworkNominateHelper {
         }
 
         // Add or update with the newly created WifiConfiguration to WifiConfigManager.
+        // NOTE: if existingNetwork != null, this update is a no-op in most cases if the SSID is the
+        // same (since we update the cached config in PasspointManager#addOrUpdateProvider().
         NetworkUpdateResult result;
         if (config.fromWifiNetworkSuggestion) {
             result = mWifiConfigManager.addOrUpdateNetwork(