face: UDP face/channel/factory

Change-Id: I4683b45378637133982efd23edd16a0c35148948
refs #1189
diff --git a/daemon/face/udp-channel.hpp b/daemon/face/udp-channel.hpp
new file mode 100644
index 0000000..b987b5e
--- /dev/null
+++ b/daemon/face/udp-channel.hpp
@@ -0,0 +1,164 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (C) 2014 Named Data Networking Project
+ * See COPYING for copyright and distribution information.
+ */
+
+#ifndef NFD_FACE_UDP_CHANNEL_HPP
+#define NFD_FACE_UDP_CHANNEL_HPP
+
+#include "common.hpp"
+#include "core/time.hpp"
+#include "udp-face.hpp"
+
+namespace nfd {
+
+namespace udp {
+  typedef boost::asio::ip::udp::endpoint Endpoint;
+} // namespace udp
+
+/**
+ * \brief Class implementing UDP-based channel to create faces
+ *
+ *
+ */
+class UdpChannel
+{
+public:
+  
+  /**
+   * \brief Exception of UdpChannel
+   */
+  struct Error : public std::runtime_error
+  {
+    Error(const std::string& what) : runtime_error(what) {}
+  };
+  
+  /**
+   * \brief Prototype for the callback called when face is created
+   *        (as a response to new incoming communication not managed
+   *        by any faces yet or after the connect function is created)
+   */
+  typedef function<void(const shared_ptr<UdpFace>& newFace)> FaceCreatedCallback;
+
+  /**
+   * \brief Prototype for the callback that is called when face is failed to
+   *        get created
+   */
+  typedef function<void(const std::string& reason)> ConnectFailedCallback;
+
+  /**
+   * \brief Create UDP channel for the local endpoint
+   *
+   * To enable creation of faces upon incoming connections,
+   * one needs to explicitly call UdpChannel::listen method.
+   * The created socket is bound to the localEndpoint.
+   * reuse_address option is set
+   *
+   * \throw UdpChannel::Error if bind on the socket fails
+   */
+  UdpChannel(const udp::Endpoint& localEndpoint,
+             const time::Duration& timeout);
+
+  /**
+   * \brief Enable listening on the local endpoint, accept connections,
+   *        and create faces when remote host makes a connection
+   * \param onFaceCreated  Callback to notify successful creation of the face
+   * \param onAcceptFailed Callback to notify when channel fails
+   *
+   * \throws UdpChannel::Error if called multiple times
+   */
+  void
+  listen(const FaceCreatedCallback& onFaceCreated,
+         const ConnectFailedCallback& onAcceptFailed);
+
+  /**
+   * \brief Create a face by establishing connection to remote endpoint
+   *
+   * \throw UdpChannel::Error if bind or connect on the socket fail
+   */
+  void
+  connect(const udp::Endpoint& remoteEndpoint,
+          const FaceCreatedCallback& onFaceCreated);
+  /**
+   * \brief Create a face by establishing connection to the specified
+   *        remote host and remote port
+   *
+   * This method will never block and will return immediately. All
+   * necessary hostname and port resolution and connection will happen
+   * in asynchronous mode.
+   *
+   * If connection cannot be established within specified timeout, it
+   * will be aborted.
+   */
+  void
+  connect(const std::string& remoteHost, const std::string& remotePort,
+          const FaceCreatedCallback& onFaceCreated,
+          const ConnectFailedCallback& onConnectFailed);
+
+  /**
+   * \brief Get number of faces in the channel
+   */
+  size_t
+  size() const;
+
+private:
+  shared_ptr<UdpFace>
+  createFace(const shared_ptr<boost::asio::ip::udp::socket>& socket,
+             const FaceCreatedCallback& onFaceCreated);
+  void
+  afterFaceFailed(udp::Endpoint& endpoint);
+
+  /**
+   * \brief The UdpChannel has received a new pkt from a remote endpoint not yet 
+   *        associated with any UdpFace
+   */
+  void
+  newPeer(const boost::system::error_code& error,
+                   std::size_t nBytesReceived);
+
+  void
+  handleEndpointResolution(const boost::system::error_code& error,
+                           boost::asio::ip::udp::resolver::iterator remoteEndpoint,
+                           const FaceCreatedCallback& onFaceCreated,
+                           const ConnectFailedCallback& onConnectFailed,
+                           const shared_ptr<boost::asio::ip::udp::resolver>& resolver);
+
+private:
+  udp::Endpoint m_localEndpoint;
+
+  /**
+   * \brief Endpoint used to store the information about the last new remote endpoint
+   */
+  udp::Endpoint m_newRemoteEndpoint;
+
+  /**
+   * Callbacks for face creation.
+   * New communications are detected using async_receive_from.
+   * Its handler has a fixed signature. No space for the face callback
+   */
+  FaceCreatedCallback onFaceCreatedNewPeerCallback;
+  
+  // @todo remove the onConnectFailedNewPeerCallback if it remains unused
+  ConnectFailedCallback onConnectFailedNewPeerCallback;
+
+  /**
+   * \brief Socket used to "accept" new communication
+   **/
+  shared_ptr<boost::asio::ip::udp::socket> m_socket;
+
+  uint8_t m_inputBuffer[MAX_NDN_PACKET_SIZE];
+
+  typedef std::map< udp::Endpoint, shared_ptr<UdpFace> > ChannelFaceMap;
+  ChannelFaceMap m_channelFaces;
+
+  /**
+   * \brief If true, it means the function listen has already been called
+   */
+  bool m_isListening;
+
+};
+
+} // namespace nfd
+
+#endif // NFD_FACE_UDP_CHANNEL_HPP