model: Change NetDeviceFace into NetDeviceLinkService to match NFD 0.4+ Face model

ndnSIM (for now) intentionally uses LinkService instead of Transport for
optimization purposes and in order to preserve ns3::Packet Tags.  This
may be fixed in the future when there is a different mechanism to
propagate ns3 Tags or Tags are no longer necessary.

Change-Id: I2aeef8f37d587374a1c9fe04386e33b6fde83fe0
Refs: #3560
diff --git a/model/null-transport.hpp b/model/null-transport.hpp
new file mode 100644
index 0000000..42ef9c6
--- /dev/null
+++ b/model/null-transport.hpp
@@ -0,0 +1,70 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2011-2015  Regents of the University of California.
+ *
+ * This file is part of ndnSIM. See AUTHORS for complete list of ndnSIM authors and
+ * contributors.
+ *
+ * ndnSIM is free software: you can redistribute it and/or modify it under the terms
+ * of the GNU General Public License as published by the Free Software Foundation,
+ * either version 3 of the License, or (at your option) any later version.
+ *
+ * ndnSIM is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
+ * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
+ * PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * ndnSIM, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
+ **/
+
+#ifndef NDN_NULL_TRANSPORT_HPP
+#define NDN_NULL_TRANSPORT_HPP
+
+#include "ns3/ndnSIM/model/ndn-common.hpp"
+#include "ns3/ndnSIM/NFD/daemon/face/transport.hpp"
+
+namespace ns3 {
+namespace ndn {
+
+/**
+ * \ingroup ndn-face
+ * \brief Null transport (does nothing, just fulfills requirements of the interface)
+ */
+class NullTransport : public nfd::face::Transport
+{
+public:
+  NullTransport(const std::string& localUri, const std::string& remoteUri,
+                ::ndn::nfd::FaceScope scope = ::ndn::nfd::FACE_SCOPE_NON_LOCAL,
+                ::ndn::nfd::FacePersistency persistency = ::ndn::nfd::FACE_PERSISTENCY_PERSISTENT,
+                ::ndn::nfd::LinkType linkType = ::ndn::nfd::LINK_TYPE_POINT_TO_POINT)
+  {
+    this->setLocalUri(FaceUri(localUri));
+    this->setRemoteUri(FaceUri(remoteUri));
+    this->setScope(scope);
+    this->setPersistency(persistency);
+    this->setLinkType(linkType);
+    // this->setMtu(udp::computeMtu(m_socket.local_endpoint())); // not sure what should be here
+  }
+
+private:
+  virtual void
+  beforeChangePersistency(::ndn::nfd::FacePersistency newPersistency)
+  {
+  }
+
+  virtual void
+  doClose()
+  {
+    this->setState(nfd::face::TransportState::CLOSED);
+  }
+
+  virtual void
+  doSend(Packet&& packet)
+  {
+  }
+};
+
+} // namespace ndn
+} // namespace ns3
+
+#endif // NDN_NULL_TRANSPORT_HPP