MAC Randomization: Store Randomized MAC Address in WifiConfiguration

Store randomized MAC address for each network in mMacAddress field, so
that we don't have to create a new MAC address when connecting to a
saved network.

Bug: 63905794
Bug: 71548300
Test: Unittest
Change-Id: I05a50d3c3bc94e5ac4a0ec7cbd1f192a6d4c0b11

wifi/java/android/net/wifi/WifiConfiguration.java

@@ -20,6 +20,7 @@ import android.annotation.SystemApi;
 import android.content.pm.PackageManager;
 import android.net.IpConfiguration;
 import android.net.IpConfiguration.ProxySettings;
+import android.net.MacAddress;
 import android.net.ProxyInfo;
 import android.net.StaticIpConfiguration;
 import android.net.Uri;
@@ -852,6 +853,52 @@ public class WifiConfiguration implements Parcelable {
     @SystemApi
     public int numAssociation;
 
+    /**
+     * @hide
+     * Randomized MAC address to use with this particular network
+     */
+    private MacAddress mRandomizedMacAddress;
+
+    /**
+     * @hide
+     * Checks if the given MAC address can be used for Connected Mac Randomization
+     * by verifying that it is non-null, unicast, and locally assigned.
+     * @param mac MacAddress to check
+     * @return true if mac is good to use
+     */
+    private boolean isValidMacAddressForRandomization(MacAddress mac) {
+        return mac != null && !mac.isMulticastAddress() && mac.isLocallyAssigned();
+    }
+
+    /**
+     * @hide
+     * Returns Randomized MAC address to use with the network.
+     * If it is not set/valid, create a new randomized address.
+     */
+    public MacAddress getOrCreateRandomizedMacAddress() {
+        if (!isValidMacAddressForRandomization(mRandomizedMacAddress)) {
+            mRandomizedMacAddress = MacAddress.createRandomUnicastAddress();
+        }
+        return mRandomizedMacAddress;
+    }
+
+    /**
+     * @hide
+     * Returns MAC address set to be the local randomized MAC address.
+     * Does not guarantee that the returned address is valid for use.
+     */
+    public MacAddress getRandomizedMacAddress() {
+        return mRandomizedMacAddress;
+    }
+
+    /**
+     * @hide
+     * @param mac MacAddress to change into
+     */
+    public void setRandomizedMacAddress(MacAddress mac) {
+        mRandomizedMacAddress = mac;
+    }
+
     /** @hide
      * Boost given to RSSI on a home network for the purpose of calculating the score
      * This adds stickiness to home networks, as defined by:
@@ -2124,6 +2171,7 @@ public class WifiConfiguration implements Parcelable {
             updateTime = source.updateTime;
             shared = source.shared;
             recentFailure.setAssociationStatus(source.recentFailure.getAssociationStatus());
+            mRandomizedMacAddress = source.mRandomizedMacAddress;
         }
     }
 
@@ -2191,6 +2239,7 @@ public class WifiConfiguration implements Parcelable {
         dest.writeInt(shared ? 1 : 0);
         dest.writeString(mPasspointManagementObjectTree);
         dest.writeInt(recentFailure.getAssociationStatus());
+        dest.writeParcelable(mRandomizedMacAddress, flags);
     }
 
     /** Implement the Parcelable interface {@hide} */
@@ -2259,6 +2308,7 @@ public class WifiConfiguration implements Parcelable {
                 config.shared = in.readInt() != 0;
                 config.mPasspointManagementObjectTree = in.readString();
                 config.recentFailure.setAssociationStatus(in.readInt());
+                config.mRandomizedMacAddress = in.readParcelable(null);
                 return config;
             }
 

wifi/tests/src/android/net/wifi/WifiConfigurationTest.java

@@ -22,6 +22,7 @@ import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.assertFalse;
 
 import android.os.Parcel;
+import android.net.MacAddress;
 import android.net.wifi.WifiConfiguration.NetworkSelectionStatus;
 
 import org.junit.Before;
@@ -49,6 +50,7 @@ public class WifiConfigurationTest {
         String cookie = "C O.o |<IE";
         WifiConfiguration config = new WifiConfiguration();
         config.setPasspointManagementObjectTree(cookie);
+        MacAddress macBeforeParcel = config.getOrCreateRandomizedMacAddress();
         Parcel parcelW = Parcel.obtain();
         config.writeToParcel(parcelW, 0);
         byte[] bytes = parcelW.marshall();
@@ -59,8 +61,9 @@ public class WifiConfigurationTest {
         parcelR.setDataPosition(0);
         WifiConfiguration reconfig = WifiConfiguration.CREATOR.createFromParcel(parcelR);
 
-        // lacking a useful config.equals, check one field near the end.
+        // lacking a useful config.equals, check two fields near the end.
         assertEquals(cookie, reconfig.getMoTree());
+        assertEquals(macBeforeParcel, reconfig.getOrCreateRandomizedMacAddress());
 
         Parcel parcelWW = Parcel.obtain();
         reconfig.writeToParcel(parcelWW, 0);
@@ -169,4 +172,48 @@ public class WifiConfigurationTest {
 
         assertFalse(config.isOpenNetwork());
     }
+
+    @Test
+    public void testGetOrCreateRandomizedMacAddress_SavesAndReturnsSameAddress() {
+        WifiConfiguration config = new WifiConfiguration();
+        MacAddress firstMacAddress = config.getOrCreateRandomizedMacAddress();
+        MacAddress secondMacAddress = config.getOrCreateRandomizedMacAddress();
+
+        assertEquals(firstMacAddress, secondMacAddress);
+    }
+
+    @Test
+    public void testSetRandomizedMacAddress_ChangesSavedAddress() {
+        WifiConfiguration config = new WifiConfiguration();
+        MacAddress macToChangeInto = MacAddress.createRandomUnicastAddress();
+        config.setRandomizedMacAddress(macToChangeInto);
+        MacAddress macAfterChange = config.getOrCreateRandomizedMacAddress();
+
+        assertEquals(macToChangeInto, macAfterChange);
+    }
+
+    @Test
+    public void testGetOrCreateRandomizedMacAddress_ReRandomizesInvalidAddress() {
+        WifiConfiguration config =  new WifiConfiguration();
+
+        MacAddress macAddressZeroes = MacAddress.ALL_ZEROS_ADDRESS;
+        MacAddress macAddressMulticast = MacAddress.fromString("03:ff:ff:ff:ff:ff");
+        MacAddress macAddressGlobal = MacAddress.fromString("fc:ff:ff:ff:ff:ff");
+
+        config.setRandomizedMacAddress(null);
+        MacAddress macAfterChange = config.getOrCreateRandomizedMacAddress();
+        assertFalse(macAfterChange.equals(null));
+
+        config.setRandomizedMacAddress(macAddressZeroes);
+        macAfterChange = config.getOrCreateRandomizedMacAddress();
+        assertFalse(macAfterChange.equals(macAddressZeroes));
+
+        config.setRandomizedMacAddress(macAddressMulticast);
+        macAfterChange = config.getOrCreateRandomizedMacAddress();
+        assertFalse(macAfterChange.equals(macAddressMulticast));
+
+        config.setRandomizedMacAddress(macAddressGlobal);
+        macAfterChange = config.getOrCreateRandomizedMacAddress();
+        assertFalse(macAfterChange.equals(macAddressGlobal));
+    }
 }