face: Implement WebSocket channel, face, and factory.

Change-Id: Ic4dbb1abdbbdbec028746ba14b11be8ab9cc1edb
Refs: #1468
diff --git a/daemon/face/websocket-channel.hpp b/daemon/face/websocket-channel.hpp
new file mode 100644
index 0000000..05d8f99
--- /dev/null
+++ b/daemon/face/websocket-channel.hpp
@@ -0,0 +1,122 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2014  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_FACE_WEBSOCKET_CHANNEL_HPP
+#define NFD_DAEMON_FACE_WEBSOCKET_CHANNEL_HPP
+
+#include "channel.hpp"
+#include "core/global-io.hpp"
+#include "core/scheduler.hpp"
+#include "websocket-face.hpp"
+
+namespace nfd {
+
+/**
+ * \brief Class implementing WebSocket-based channel to create faces
+ *
+ *
+ */
+class WebSocketChannel : public Channel
+{
+public:
+  /**
+   * \brief Exception of WebSocketChannel
+   */
+  class Error : public std::runtime_error
+  {
+  public:
+    explicit
+    Error(const std::string& what)
+      : runtime_error(what)
+    {
+    }
+  };
+
+  /**
+   * \brief Create WebSocket channel for the local endpoint
+   *
+   * To enable creation of faces upon incoming connections,
+   * one needs to explicitly call WebSocketChannel::listen method.
+   * The created socket is bound to the localEndpoint.
+   *
+   * \throw WebSocketChannel::Error if bind on the socket fails
+   */
+  explicit
+  WebSocketChannel(const websocket::Endpoint& localEndpoint);
+
+  virtual
+  ~WebSocketChannel();
+
+  /**
+   * \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
+   *
+   * \throws WebSocketChannel::Error if called multiple times
+   */
+  void
+  listen(const FaceCreatedCallback& onFaceCreated);
+
+  /**
+   * \brief Get number of faces in the channel
+   */
+  size_t
+  size() const;
+
+private:
+  void
+  handleMessage(websocketpp::connection_hdl hdl, websocket::Server::message_ptr msg);
+
+  void
+  handleOpen(websocketpp::connection_hdl hdl);
+
+  void
+  handleClose(websocketpp::connection_hdl hdl);
+
+private:
+  websocket::Endpoint m_localEndpoint;
+
+  websocket::Server m_server;
+
+  /**
+   * 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 m_onFaceCreatedCallback;
+
+  typedef std::map< websocketpp::connection_hdl, shared_ptr<WebSocketFace> > ChannelFaceMap;
+  ChannelFaceMap m_channelFaces;
+
+  /**
+   * \brief If true, it means the function listen has already been called
+   */
+  bool m_isListening;
+
+};
+
+} // namespace nfd
+
+#endif // NFD_DAEMON_FACE_WEBSOCKET_CHANNEL_HPP