base: add PacketBase to provide wrappers for congestion tags

refs #3797

Change-Id: I8747bb4fcbc11bfd1731516896b8aef1ec181c36
diff --git a/src/data.hpp b/src/data.hpp
index 2729e0d..e0a8466 100644
--- a/src/data.hpp
+++ b/src/data.hpp
@@ -24,15 +24,15 @@
 
 #include "meta-info.hpp"
 #include "name.hpp"
+#include "packet-base.hpp"
 #include "signature.hpp"
-#include "tag-host.hpp"
 #include "encoding/block.hpp"
 
 namespace ndn {
 
 /** @brief Represents a Data packet
  */
-class Data : public TagHost, public enable_shared_from_this<Data>
+class Data : public PacketBase, public enable_shared_from_this<Data>
 {
 public:
   class Error : public tlv::Error
diff --git a/src/interest.hpp b/src/interest.hpp
index 52cabf7..15a1501 100644
--- a/src/interest.hpp
+++ b/src/interest.hpp
@@ -24,8 +24,8 @@
 
 #include "delegation-list.hpp"
 #include "name.hpp"
+#include "packet-base.hpp"
 #include "selectors.hpp"
-#include "tag-host.hpp"
 #include "util/time.hpp"
 
 namespace ndn {
@@ -39,7 +39,7 @@
 
 /** @brief represents an Interest packet
  */
-class Interest : public TagHost, public enable_shared_from_this<Interest>
+class Interest : public PacketBase, public enable_shared_from_this<Interest>
 {
 public:
   class Error : public tlv::Error
diff --git a/src/lp/nack.cpp b/src/lp/nack.cpp
index c31a114..56b183d 100644
--- a/src/lp/nack.cpp
+++ b/src/lp/nack.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
-/**
- * Copyright (c) 2013-2015 Regents of the University of California.
+/*
+ * Copyright (c) 2013-2017 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -26,6 +26,8 @@
 namespace ndn {
 namespace lp {
 
+Nack::Nack() = default;
+
 Nack::Nack(const Interest& interest)
   : m_interest(interest)
 {
@@ -37,4 +39,4 @@
 }
 
 } // namespace lp
-} // namespace ndn
\ No newline at end of file
+} // namespace ndn
diff --git a/src/lp/nack.hpp b/src/lp/nack.hpp
index 3b23cf6..2a60e64 100644
--- a/src/lp/nack.hpp
+++ b/src/lp/nack.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
-/**
- * Copyright (c) 2013-2015 Regents of the University of California.
+/*
+ * Copyright (c) 2013-2017 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -25,8 +25,8 @@
 #define NDN_CXX_LP_NACK_HPP
 
 #include "../common.hpp"
-#include "../tag-host.hpp"
 #include "../interest.hpp"
+#include "../packet-base.hpp"
 
 #include "nack-header.hpp"
 
@@ -37,10 +37,10 @@
  *
  *  This type binds a NackHeader and an Interest, and is intended for use in network layer.
  */
-class Nack : public TagHost
+class Nack : public PacketBase
 {
 public:
-  Nack() = default;
+  Nack();
 
   explicit
   Nack(const Interest& interest);
diff --git a/src/packet-base.cpp b/src/packet-base.cpp
new file mode 100644
index 0000000..173a8d9
--- /dev/null
+++ b/src/packet-base.cpp
@@ -0,0 +1,52 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/*
+ * Copyright (c) 2013-2017 Regents of the University of California.
+ *
+ * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
+ *
+ * ndn-cxx library is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU Lesser General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later version.
+ *
+ * ndn-cxx library 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 Lesser General Public License for more details.
+ *
+ * You should have received copies of the GNU General Public License and GNU Lesser
+ * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
+ */
+
+#include "packet-base.hpp"
+#include "lp/tags.hpp"
+
+namespace ndn {
+
+uint64_t
+PacketBase::getCongestionMark() const
+{
+  auto mark = this->getTag<lp::CongestionMarkTag>();
+
+  if (mark == nullptr) {
+    return 0;
+  }
+  else {
+    return *mark;
+  }
+}
+
+void
+PacketBase::setCongestionMark(uint64_t mark)
+{
+  if (mark != 0) {
+    auto tag = make_shared<lp::CongestionMarkTag>(mark);
+    this->setTag(std::move(tag));
+  }
+  else {
+    this->removeTag<lp::CongestionMarkTag>();
+  }
+}
+
+} // namespace ndn
diff --git a/src/packet-base.hpp b/src/packet-base.hpp
new file mode 100644
index 0000000..ff76732
--- /dev/null
+++ b/src/packet-base.hpp
@@ -0,0 +1,47 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/*
+ * Copyright (c) 2013-2017 Regents of the University of California.
+ *
+ * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
+ *
+ * ndn-cxx library is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU Lesser General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later version.
+ *
+ * ndn-cxx library 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 Lesser General Public License for more details.
+ *
+ * You should have received copies of the GNU General Public License and GNU Lesser
+ * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
+ */
+
+#ifndef NDN_PACKET_BASE_HPP
+#define NDN_PACKET_BASE_HPP
+
+#include "tag-host.hpp"
+
+namespace ndn {
+
+/** \brief base class to allow simple management of packet tags
+ */
+class PacketBase : public TagHost
+{
+public:
+  /** \brief get the value of the CongestionMark tag
+   */
+  uint64_t
+  getCongestionMark() const;
+
+  /** \brief set the CongestionMark tag to the specified value
+   */
+  void
+  setCongestionMark(uint64_t mark);
+};
+
+} // namespace ndn
+
+#endif // NDN_PACKET_BASE_HPP
diff --git a/tests/unit-tests/packet-base.t.cpp b/tests/unit-tests/packet-base.t.cpp
new file mode 100644
index 0000000..99b7e8a
--- /dev/null
+++ b/tests/unit-tests/packet-base.t.cpp
@@ -0,0 +1,64 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/*
+ * Copyright (c) 2013-2017 Regents of the University of California.
+ *
+ * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
+ *
+ * ndn-cxx library is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU Lesser General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later version.
+ *
+ * ndn-cxx library 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 Lesser General Public License for more details.
+ *
+ * You should have received copies of the GNU General Public License and GNU Lesser
+ * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
+ */
+
+#include "packet-base.hpp"
+
+#include "../boost-test.hpp"
+#include "interest.hpp"
+#include "lp/tags.hpp"
+
+namespace ndn {
+namespace tests {
+
+BOOST_AUTO_TEST_SUITE(TestPacketBase)
+
+BOOST_AUTO_TEST_CASE(CongestionMark)
+{
+  Interest interest;
+
+  BOOST_CHECK_EQUAL(interest.getCongestionMark(), 0);
+
+  auto tag = interest.getTag<lp::CongestionMarkTag>();
+  BOOST_CHECK(!tag);
+
+  interest.setCongestionMark(true);
+  tag = interest.getTag<lp::CongestionMarkTag>();
+  BOOST_REQUIRE(tag);
+  BOOST_CHECK_EQUAL(*tag, 1);
+
+  interest.setCongestionMark(false);
+  tag = interest.getTag<lp::CongestionMarkTag>();
+  BOOST_CHECK(!tag);
+
+  interest.setCongestionMark(300);
+  tag = interest.getTag<lp::CongestionMarkTag>();
+  BOOST_REQUIRE(tag);
+  BOOST_CHECK_EQUAL(*tag, 300);
+
+  interest.setCongestionMark(0);
+  tag = interest.getTag<lp::CongestionMarkTag>();
+  BOOST_CHECK(!tag);
+}
+
+BOOST_AUTO_TEST_SUITE_END() // TestPacketBase
+
+} // namespace tests
+} // namespace ndn