Add support for long values in StructNlAttr

Test: atest NetworkStaticLibTests:com.android.net.moduletests.util.netlink.StructNlAttrTest
Change-Id: Iaaa7f63a2b550f017a8c75f84b9d69bf9e829a8c

staticlibs/device/com/android/net/module/util/netlink/StructNlAttr.java

@@ -21,6 +21,8 @@ import android.net.MacAddress;
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 
+import static java.nio.ByteOrder.nativeOrder;
+
 import java.io.UnsupportedEncodingException;
 import java.net.InetAddress;
 import java.net.UnknownHostException;
@@ -152,12 +154,12 @@ public class StructNlAttr {
         nla_type = type;
         setValue(new byte[Short.BYTES]);
         final ByteBuffer buf = getValueAsByteBuffer();
-        final ByteOrder originalOrder = buf.order();
+        // ByteBuffer returned by getValueAsByteBuffer is always in native byte order.
         try {
             buf.order(order);
             buf.putShort(value);
         } finally {
-            buf.order(originalOrder);
+            buf.order(nativeOrder());
         }
     }
 
@@ -169,12 +171,29 @@ public class StructNlAttr {
         nla_type = type;
         setValue(new byte[Integer.BYTES]);
         final ByteBuffer buf = getValueAsByteBuffer();
-        final ByteOrder originalOrder = buf.order();
+        // ByteBuffer returned by getValueAsByteBuffer is always in native byte order.
         try {
             buf.order(order);
             buf.putInt(value);
         } finally {
-            buf.order(originalOrder);
+            buf.order(nativeOrder());
+        }
+    }
+
+    public StructNlAttr(short type, long value) {
+        this(type, value, ByteOrder.nativeOrder());
+    }
+
+    public StructNlAttr(short type, long value, ByteOrder order) {
+        nla_type = type;
+        setValue(new byte[Long.BYTES]);
+        final ByteBuffer buf = getValueAsByteBuffer();
+        // ByteBuffer returned by getValueAsByteBuffer is always in native byte order.
+        try {
+            buf.order(order);
+            buf.putLong(value);
+        } finally {
+            buf.order(nativeOrder());
         }
     }
 
@@ -288,6 +307,7 @@ public class StructNlAttr {
 
     /**
      * Get attribute value as Integer, or null if malformed (e.g., length is not 4 bytes).
+     * The attribute value is assumed to be in native byte order.
      */
     public Integer getValueAsInteger() {
         final ByteBuffer byteBuffer = getValueAsByteBuffer();
@@ -297,6 +317,18 @@ public class StructNlAttr {
         return byteBuffer.getInt();
     }
 
+    /**
+     * Get attribute value as Long, or null if malformed (e.g., length is not 8 bytes).
+     * The attribute value is assumed to be in native byte order.
+     */
+    public Long getValueAsLong() {
+        final ByteBuffer byteBuffer = getValueAsByteBuffer();
+        if (byteBuffer == null || byteBuffer.remaining() != Long.BYTES) {
+            return null;
+        }
+        return byteBuffer.getLong();
+    }
+
     /**
      * Get attribute value as Int, default value if malformed.
      */

staticlibs/tests/unit/src/com/android/net/module/util/netlink/StructNlAttrTest.java

@@ -92,4 +92,26 @@ public class StructNlAttrTest {
         assertNull(integer3);
         assertEquals(int3, 0x08 /* default value */);
     }
+
+    @Test
+    public void testGetValueAsLong() {
+        final Long input = 1234567L;
+        // Not a real netlink attribute, just for testing
+        final StructNlAttr attr = new StructNlAttr(IFA_FLAGS, input);
+
+        final Long output = attr.getValueAsLong();
+
+        assertEquals(input, output);
+    }
+
+    @Test
+    public void testGetValueAsLong_malformed() {
+        final int input = 1234567;
+        // Not a real netlink attribute, just for testing
+        final StructNlAttr attr = new StructNlAttr(IFA_FLAGS, input);
+
+        final Long output = attr.getValueAsLong();
+
+        assertNull(output);
+    }
 }