From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Pratyush <39559233+empratyush@users.noreply.github.com>
Date: Thu, 20 May 2021 13:21:31 +0530
Subject: [PATCH] avoid reusing DHCP state for full MAC randomization

---
 src/android/net/dhcp/DhcpClient.java | 29 +++++++++++++++++++++++++++-
 1 file changed, 28 insertions(+), 1 deletion(-)

diff --git a/src/android/net/dhcp/DhcpClient.java b/src/android/net/dhcp/DhcpClient.java
index c88b6532..c9f65d0d 100644
--- a/src/android/net/dhcp/DhcpClient.java
+++ b/src/android/net/dhcp/DhcpClient.java
@@ -75,6 +75,9 @@ import android.net.networkstack.aidl.dhcp.DhcpOption;
 import android.net.util.HostnameTransliterator;
 import android.net.util.NetworkStackUtils;
 import android.net.util.SocketUtils;
+import android.net.wifi.WifiConfiguration;
+import android.net.wifi.WifiInfo;
+import android.net.wifi.WifiManager;
 import android.os.Build;
 import android.os.Handler;
 import android.os.Message;
@@ -116,6 +119,7 @@ import java.net.SocketAddress;
 import java.net.SocketException;
 import java.nio.ByteBuffer;
 import java.util.Arrays;
+import java.util.ArrayList;
 import java.util.List;
 import java.util.Random;
 
@@ -1250,7 +1254,7 @@ public class DhcpClient extends StateMachine {
                                 + " lease expiry: "  + attributes.assignedV4AddressExpiry
                                 + " current time: "  + currentTime);
                     }
-                    if (currentTime >= attributes.assignedV4AddressExpiry) {
+                    if (currentTime >= attributes.assignedV4AddressExpiry || shouldAvoidStateReuse()) {
                         // Lease has expired.
                         transitionTo(mDhcpInitState);
                         return HANDLED;
@@ -1284,6 +1288,29 @@ public class DhcpClient extends StateMachine {
         return true;
     }
 
+    private static final int RANDOMIZATION_ALWAYS = 100;
+
+    private boolean shouldAvoidStateReuse() {
+        try {
+            WifiManager wifiManager = (WifiManager) mContext.getSystemService(Context.WIFI_SERVICE);
+            WifiInfo wifiInfo =  wifiManager.getConnectionInfo();
+            if (wifiInfo != null) {
+                int connectedNetworkId = wifiInfo.getNetworkId();
+                List<WifiConfiguration> configurationList = wifiManager.getConfiguredNetworks();
+                for (WifiConfiguration configuration : configurationList){
+                    if (configuration.networkId == connectedNetworkId){
+                        return configuration.macRandomizationSetting == RANDOMIZATION_ALWAYS;
+                    }
+                }
+            }
+        } catch (Exception e) {
+            loge(e.getLocalizedMessage(), e);
+        }
+
+        loge("ConfiguredNetworks should contain Connected network id config");
+        return true;
+    }
+
     private void receiveOfferOrAckPacket(final DhcpPacket packet, final boolean acceptRapidCommit) {
         if (!isValidPacket(packet)) return;