Add DHCPv6 relevant constants such as port and multicast group address.

Bug: 260934173
Test: m
Change-Id: Ice5e9c7fa3f2250654a6a9822d05786831bd66c4
diff --git a/staticlibs/framework/com/android/net/module/util/NetworkStackConstants.java b/staticlibs/framework/com/android/net/module/util/NetworkStackConstants.java
index 287473e..7b3943c 100644
--- a/staticlibs/framework/com/android/net/module/util/NetworkStackConstants.java
+++ b/staticlibs/framework/com/android/net/module/util/NetworkStackConstants.java
@@ -210,6 +210,17 @@
     public static final int DHCP4_CLIENT_PORT = 68;
 
     /**
+     * DHCPv6 constants.
+     *
+     * See also:
+     *     - https://datatracker.ietf.org/doc/html/rfc8415
+     */
+    public static final int DHCP6_CLIENT_PORT = 546;
+    public static final int DHCP6_SERVER_PORT = 547;
+    public static final Inet6Address ALL_DHCP_RELAY_AGENTS_AND_SERVERS =
+            (Inet6Address) InetAddresses.parseNumericAddress("ff02::1:2");
+
+    /**
      * IEEE802.11 standard constants.
      *
      * See also: