Assign specific client address to dhcp server

Bug: 141256482
Test: manual
      atest TetheringTests

Merged-In: Ief76c98c843ba5420224cbf0f34464f366c891b7
Change-Id: Ief76c98c843ba5420224cbf0f34464f366c891b7
diff --git a/Tethering/src/android/net/dhcp/DhcpServingParamsParcelExt.java b/Tethering/src/android/net/dhcp/DhcpServingParamsParcelExt.java
index d6bc063..82a26be 100644
--- a/Tethering/src/android/net/dhcp/DhcpServingParamsParcelExt.java
+++ b/Tethering/src/android/net/dhcp/DhcpServingParamsParcelExt.java
@@ -18,10 +18,12 @@
 
 import static android.net.shared.Inet4AddressUtils.inet4AddressToIntHTH;
 
-import android.annotation.NonNull;
 import android.net.LinkAddress;
 import android.util.ArraySet;
 
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
 import java.net.Inet4Address;
 import java.util.Collection;
 import java.util.Collections;
@@ -160,6 +162,17 @@
         return this;
     }
 
+    /**
+     * Set the client address to tell DHCP server only offer this address.
+     * The client's prefix length is the same as server's.
+     *
+     * <p>If not set, the default value is null.
+     */
+    public DhcpServingParamsParcelExt setSingleClientAddr(@Nullable Inet4Address clientAddr) {
+        this.clientAddr = clientAddr == null ? 0 : inet4AddressToIntHTH(clientAddr);
+        return this;
+    }
+
     private static int[] toIntArray(@NonNull Collection<Inet4Address> addrs) {
         int[] res = new int[addrs.size()];
         int i = 0;