ClatdController - disable IPv6 on clatd tun interface

Test: we *continue* to not get clatd complaints about unknown packets
  even with a revert in clatd to ignore them
Bug: 129305844
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: If6961a9856cfd3b9a041eb155688b5a18d2b5223
diff --git a/server/ClatdController.cpp b/server/ClatdController.cpp
index d82198b..c2b3449 100644
--- a/server/ClatdController.cpp
+++ b/server/ClatdController.cpp
@@ -33,6 +33,7 @@
 #include <log/log.h>
 
 #include "ClatdController.h"
+#include "InterfaceController.h"
 
 #include "android-base/properties.h"
 #include "android-base/scopeguard.h"
@@ -438,6 +439,10 @@
         return -res;
     }
 
+    // disable IPv6 on it - failing to do so is not a critical error
+    res = InterfaceController::setEnableIPv6(v4interface.c_str(), 0);
+    if (res) ALOGE("setEnableIPv6 %s failed (%s)", v4interface.c_str(), strerror(res));
+
     // 5. initialize tracker object
     ClatdTracker tracker;
     int ret = tracker.init(networkId, interface, v4interface, nat64Prefix);