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 | 30 +++++++++++++++++++++++++++-
 1 file changed, 29 insertions(+), 1 deletion(-)

diff --git a/src/android/net/dhcp/DhcpClient.java b/src/android/net/dhcp/DhcpClient.java
index c45fc82..b62239c 100644
--- a/src/android/net/dhcp/DhcpClient.java
+++ b/src/android/net/dhcp/DhcpClient.java
@@ -60,6 +60,9 @@ import android.net.metrics.IpConnectivityLog;
 import android.net.util.InterfaceParams;
 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.Message;
 import android.os.SystemClock;
 import android.system.ErrnoException;
@@ -84,6 +87,8 @@ 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;
 
 /**
@@ -917,7 +922,7 @@ 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;
@@ -941,6 +946,29 @@ public class DhcpClient extends StateMachine {
         }
     }
 
+    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;
+    }
+
     class DhcpInitState extends PacketRetransmittingState {
         public DhcpInitState() {
             super();