face: Refactor Face as LinkService+Transport

LpFace: new Face implementation
LpFaceWrapper: allows new Face system to work with old Face system

Eventually, LpFace will be renamed to Face and LpFaceWrapper will be removed.

refs #3088 #3179

Change-Id: Ia4ad7c84631e65b444d4f24e1d7593392927c8db
diff --git a/daemon/face/generic-link-service.cpp b/daemon/face/generic-link-service.cpp
new file mode 100644
index 0000000..79010e6
--- /dev/null
+++ b/daemon/face/generic-link-service.cpp
@@ -0,0 +1,93 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2014-2015,  Regents of the University of California,
+ *                           Arizona Board of Regents,
+ *                           Colorado State University,
+ *                           University Pierre & Marie Curie, Sorbonne University,
+ *                           Washington University in St. Louis,
+ *                           Beijing Institute of Technology,
+ *                           The University of Memphis.
+ *
+ * This file is part of NFD (Named Data Networking Forwarding Daemon).
+ * See AUTHORS.md for complete list of NFD authors and contributors.
+ *
+ * NFD 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.
+ *
+ * NFD 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
+ * NFD, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "generic-link-service.hpp"
+
+namespace nfd {
+namespace face {
+
+NFD_LOG_INIT("GenericLinkService");
+
+void
+GenericLinkService::doSendInterest(const Interest& interest)
+{
+  lp::Packet lpPacket(interest.wireEncode());
+  Transport::Packet packet;
+  packet.packet = lpPacket.wireEncode();
+  sendPacket(std::move(packet));
+}
+
+void
+GenericLinkService::doSendData(const Data& data)
+{
+  lp::Packet lpPacket(data.wireEncode());
+  Transport::Packet packet;
+  packet.packet = lpPacket.wireEncode();
+  sendPacket(std::move(packet));
+}
+
+void
+GenericLinkService::doSendNack(const lp::Nack& nack)
+{
+  lp::Packet lpPacket(nack.getInterest().wireEncode());
+  lpPacket.add<lp::NackField>(nack.getHeader());
+  Transport::Packet packet;
+  packet.packet = lpPacket.wireEncode();
+  sendPacket(std::move(packet));
+}
+
+void
+GenericLinkService::doReceivePacket(Transport::Packet&& packet)
+{
+  lp::Packet lpPacket(packet.packet);
+  ndn::Buffer::const_iterator fragBegin, fragEnd;
+  std::tie(fragBegin, fragEnd) = lpPacket.get<lp::FragmentField>();
+  Block netPacket(&*fragBegin, std::distance(fragBegin, fragEnd));
+
+  // Forwarding expects Interest and Data to be created with make_shared,
+  // but has no such requirement on Nack.
+  switch (netPacket.type()) {
+    case tlv::Interest: {
+      auto interest = make_shared<Interest>(netPacket);
+      if (lpPacket.has<lp::NackField>()) {
+        lp::Nack nack(std::move(*interest));
+        nack.setHeader(lpPacket.get<lp::NackField>());
+        receiveNack(nack);
+      }
+      else {
+        receiveInterest(*interest);
+      }
+      break;
+    }
+    case tlv::Data: {
+      auto data = make_shared<Data>(netPacket);
+      receiveData(*data);
+      break;
+    }
+  }
+}
+
+} // namespace face
+} // namespace nfd