fw: Add Random Forwarding Strategy

Implement a forwarding strategy that chooses a random outgoing face,
excluding the incoming face of an Interest packet.

Refs: #4992
Change-Id: I056cd0f05463f5f0742c6adcb32ec1df8ef7529b
diff --git a/daemon/fw/random-strategy.hpp b/daemon/fw/random-strategy.hpp
new file mode 100644
index 0000000..6837e29
--- /dev/null
+++ b/daemon/fw/random-strategy.hpp
@@ -0,0 +1,66 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/*
+ * Copyright (c) 2014-2019,  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/>.
+ */
+
+#ifndef NFD_DAEMON_FW_RANDOM_STRATEGY_HPP
+#define NFD_DAEMON_FW_RANDOM_STRATEGY_HPP
+
+#include "strategy.hpp"
+#include "process-nack-traits.hpp"
+
+namespace nfd {
+namespace fw {
+
+/** \brief Randomly chooses a nexthop
+ *
+ * Sends an incoming interest to a random outgoing face,
+ * excluding the incoming face.
+ *
+ */
+class RandomStrategy : public Strategy
+                     , public ProcessNackTraits<RandomStrategy>
+{
+public:
+  explicit
+  RandomStrategy(Forwarder& forwarder, const Name& name = getStrategyName());
+
+  static const Name&
+  getStrategyName();
+
+  void
+  afterReceiveInterest(const FaceEndpoint& ingress, const Interest& interest,
+                       const shared_ptr<pit::Entry>& pitEntry) override;
+
+  void
+  afterReceiveNack(const FaceEndpoint& ingress, const lp::Nack& nack,
+                   const shared_ptr<pit::Entry>& pitEntry) override;
+
+private:
+  friend ProcessNackTraits<RandomStrategy>;
+};
+
+} // namespace fw
+} // namespace nfd
+
+#endif // NFD_DAEMON_FW_RANDOM_STRATEGY_HPP