1 files changed, 16 insertions, 11 deletions
diff --git a/ryu/lib/packet/icmpv6.py b/ryu/lib/packet/icmpv6.py
index fe94c77f..53d5ec3a 100644
--- a/ryu/lib/packet/icmpv6.py
+++ b/ryu/lib/packet/icmpv6.py
@@ -112,7 +112,7 @@ class icmpv6(packet_base.PacketBase):
             return cls
         return _register_icmpv6_type
 
-    def __init__(self, type_=0, code=0, csum=0, data=None):
+    def __init__(self, type_=0, code=0, csum=0, data=b''):
         super(icmpv6, self).__init__()
         self.type_ = type_
         self.code = code
@@ -137,8 +137,9 @@ class icmpv6(packet_base.PacketBase):
         hdr = bytearray(struct.pack(icmpv6._PACK_STR, self.type_,
                                     self.code, self.csum))
 
-        if self.data is not None:
+        if self.data:
             if self.type_ in icmpv6._ICMPV6_TYPES:
+                assert isinstance(self.data, _ICMPv6Payload)
                 hdr += self.data.serialize()
             else:
                 hdr += self.data
@@ -149,14 +150,18 @@ class icmpv6(packet_base.PacketBase):
         return hdr
 
     def __len__(self):
-        length = self._MIN_LEN
-        if self.data is not None:
-            length += len(self.data)
-        return length
+        return self._MIN_LEN + len(self.data)
+
+
+@six.add_metaclass(abc.ABCMeta)
+class _ICMPv6Payload(stringify.StringifyMixin):
+    """
+    Base class for the payload of ICMPv6 packet.
+    """
 
 
 @icmpv6.register_icmpv6_type(ND_NEIGHBOR_SOLICIT, ND_NEIGHBOR_ADVERT)
-class nd_neighbor(stringify.StringifyMixin):
+class nd_neighbor(_ICMPv6Payload):
     """ICMPv6 sub encoder/decoder class for Neighbor Solicitation and
     Neighbor Advertisement messages. (RFC 4861)
 
@@ -237,7 +242,7 @@ class nd_neighbor(stringify.StringifyMixin):
 
 
 @icmpv6.register_icmpv6_type(ND_ROUTER_SOLICIT)
-class nd_router_solicit(stringify.StringifyMixin):
+class nd_router_solicit(_ICMPv6Payload):
     """ICMPv6 sub encoder/decoder class for Router Solicitation messages.
     (RFC 4861)
 
@@ -308,7 +313,7 @@ class nd_router_solicit(stringify.StringifyMixin):
 
 
 @icmpv6.register_icmpv6_type(ND_ROUTER_ADVERT)
-class nd_router_advert(stringify.StringifyMixin):
+class nd_router_advert(_ICMPv6Payload):
     """ICMPv6 sub encoder/decoder class for Router Advertisement messages.
     (RFC 4861)
 
@@ -619,7 +624,7 @@ class nd_option_pi(nd_option):
 
 
 @icmpv6.register_icmpv6_type(ICMPV6_ECHO_REPLY, ICMPV6_ECHO_REQUEST)
-class echo(stringify.StringifyMixin):
+class echo(_ICMPv6Payload):
     """ICMPv6 sub encoder/decoder class for Echo Request and Echo Reply
     messages.
 
@@ -675,7 +680,7 @@ class echo(stringify.StringifyMixin):
 
 @icmpv6.register_icmpv6_type(
     MLD_LISTENER_QUERY, MLD_LISTENER_REPOR, MLD_LISTENER_DONE)
-class mld(stringify.StringifyMixin):
+class mld(_ICMPv6Payload):
     """ICMPv6 sub encoder/decoder class for MLD Lister Query,
     MLD Listener Report, and MLD Listener Done messages. (RFC 2710)