net: move network-related files to src/net

Some namespaces are changed:

* ndn::util::FaceUri is now ndn::FaceUri
* ndn::util::ethernet is now ndn::ethernet
* ndn::util::NetworkMonitor and related classes are now in ndn::net

refs #3940

Change-Id: Ia4754caef9726efc73f5a303cec46fc95c744d70
diff --git a/src/net/ethernet.hpp b/src/net/ethernet.hpp
new file mode 100644
index 0000000..d4b8f47
--- /dev/null
+++ b/src/net/ethernet.hpp
@@ -0,0 +1,125 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2014-2017 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 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_NET_ETHERNET_HPP
+#define NDN_NET_ETHERNET_HPP
+
+#include <array>
+#include <cstdint>
+#include <functional>
+#include <string>
+
+namespace ndn {
+namespace ethernet {
+
+const uint16_t ETHERTYPE_NDN = 0x8624;
+
+const size_t ADDR_LEN     = 6;      ///< Octets in one Ethernet address
+const size_t TYPE_LEN     = 2;      ///< Octets in Ethertype field
+const size_t HDR_LEN      = 14;     ///< Total octets in Ethernet header (without 802.1Q tag)
+const size_t TAG_LEN      = 4;      ///< Octets in 802.1Q tag (TPID + priority + VLAN)
+const size_t MIN_DATA_LEN = 46;     ///< Min octets in Ethernet payload (assuming no 802.1Q tag)
+const size_t MAX_DATA_LEN = 1500;   ///< Max octets in Ethernet payload
+const size_t CRC_LEN      = 4;      ///< Octets in Ethernet frame check sequence
+
+
+/** \brief represents an Ethernet hardware address
+ */
+class Address : public std::array<uint8_t, ADDR_LEN>
+{
+public:
+  /// Constructs a null Ethernet address (00:00:00:00:00:00)
+  Address();
+
+  /// Constructs a new Ethernet address with the given octets
+  Address(uint8_t a1, uint8_t a2, uint8_t a3,
+          uint8_t a4, uint8_t a5, uint8_t a6);
+
+  /// Constructs a new Ethernet address with the given octets
+  explicit
+  Address(const uint8_t octets[ADDR_LEN]);
+
+  /// True if this is a broadcast address (ff:ff:ff:ff:ff:ff)
+  bool
+  isBroadcast() const;
+
+  /// True if this is a multicast address
+  bool
+  isMulticast() const;
+
+  /// True if this is a null address (00:00:00:00:00:00)
+  bool
+  isNull() const;
+
+  /**
+   * \brief Converts the address to a human-readable string
+   *
+   * \param sep A character used to visually separate the octets,
+   *            usually ':' (the default value) or '-'
+   */
+  std::string
+  toString(char sep = ':') const;
+
+  /**
+   * \brief Creates an Address from a string containing an Ethernet address
+   *        in hexadecimal notation, with colons or hyphens as separators
+   *
+   * \param str The string to be parsed
+   * \return Always an instance of Address, which will be null
+   *         if the parsing fails
+   */
+  static Address
+  fromString(const std::string& str);
+};
+
+/// Returns the Ethernet broadcast address (ff:ff:ff:ff:ff:ff)
+Address
+getBroadcastAddress();
+
+/// Returns the default Ethernet multicast address for NDN
+Address
+getDefaultMulticastAddress();
+
+std::ostream&
+operator<<(std::ostream& o, const Address& a);
+
+} // namespace ethernet
+} // namespace ndn
+
+namespace std {
+
+// specialize std::hash<> for ethernet::Address
+template<>
+struct hash<ndn::ethernet::Address>
+{
+  size_t
+  operator()(const ndn::ethernet::Address& a) const noexcept;
+};
+
+} // namespace std
+
+#endif // NDN_NET_ETHERNET_HPP