face: Stop using shared_ptr to manage acceptors

This commit also includes a major cleanup of all channels.

Change-Id: I10db9709e0cba6a0691a86482c60b5dbb2956f68
Refs: #2613
diff --git a/daemon/face/tcp-channel.cpp b/daemon/face/tcp-channel.cpp
index 0a6ce78..637cfa3 100644
--- a/daemon/face/tcp-channel.cpp
+++ b/daemon/face/tcp-channel.cpp
@@ -24,6 +24,7 @@
  */
 
 #include "tcp-channel.hpp"
+#include "tcp-face.hpp"
 #include "core/global-io.hpp"
 
 namespace nfd {
@@ -33,14 +34,10 @@
 using namespace boost::asio;
 
 TcpChannel::TcpChannel(const tcp::Endpoint& localEndpoint)
-  : m_localEndpoint(localEndpoint)
-  , m_isListening(false)
+  : m_acceptor(getGlobalIoService())
+  , m_localEndpoint(localEndpoint)
 {
-  this->setUri(FaceUri(localEndpoint));
-}
-
-TcpChannel::~TcpChannel()
-{
+  setUri(FaceUri(m_localEndpoint));
 }
 
 void
@@ -48,24 +45,21 @@
                    const ConnectFailedCallback& onAcceptFailed,
                    int backlog/* = tcp::acceptor::max_connections*/)
 {
-  m_acceptor = make_shared<ip::tcp::acceptor>(ref(getGlobalIoService()));
-  m_acceptor->open(m_localEndpoint.protocol());
-  m_acceptor->set_option(ip::tcp::acceptor::reuse_address(true));
+  if (isListening()) {
+    NFD_LOG_WARN("[" << m_localEndpoint << "] Already listening");
+    return;
+  }
+
+  m_acceptor.open(m_localEndpoint.protocol());
+  m_acceptor.set_option(ip::tcp::acceptor::reuse_address(true));
   if (m_localEndpoint.address().is_v6())
-    {
-      m_acceptor->set_option(ip::v6_only(true));
-    }
-  m_acceptor->bind(m_localEndpoint);
-  m_acceptor->listen(backlog);
+    m_acceptor.set_option(ip::v6_only(true));
 
-  shared_ptr<ip::tcp::socket> clientSocket =
-    make_shared<ip::tcp::socket>(ref(getGlobalIoService()));
-  m_acceptor->async_accept(*clientSocket,
-                           bind(&TcpChannel::handleSuccessfulAccept, this, _1,
-                                clientSocket,
-                                onFaceCreated, onAcceptFailed));
+  m_acceptor.bind(m_localEndpoint);
+  m_acceptor.listen(backlog);
 
-  m_isListening = true;
+  // start accepting connections
+  accept(onFaceCreated, onAcceptFailed);
 }
 
 void
@@ -74,9 +68,9 @@
                     const TcpChannel::ConnectFailedCallback& onConnectFailed,
                     const time::seconds& timeout/* = time::seconds(4)*/)
 {
-  ChannelFaceMap::iterator i = m_channelFaces.find(remoteEndpoint);
-  if (i != m_channelFaces.end()) {
-    onFaceCreated(i->second);
+  auto it = m_channelFaces.find(remoteEndpoint);
+  if (it != m_channelFaces.end()) {
+    onFaceCreated(it->second);
     return;
   }
 
@@ -84,10 +78,11 @@
     make_shared<ip::tcp::socket>(ref(getGlobalIoService()));
 
   scheduler::EventId connectTimeoutEvent = scheduler::schedule(timeout,
-      bind(&TcpChannel::handleFailedConnect, this, clientSocket, onConnectFailed));
+      bind(&TcpChannel::handleConnectTimeout, this, clientSocket, onConnectFailed));
 
   clientSocket->async_connect(remoteEndpoint,
-                              bind(&TcpChannel::handleSuccessfulConnect, this, _1,
+                              bind(&TcpChannel::handleConnect, this,
+                                   boost::asio::placeholders::error,
                                    clientSocket, connectTimeoutEvent,
                                    onFaceCreated, onConnectFailed));
 }
@@ -107,22 +102,25 @@
 
   shared_ptr<Face> face;
 
-  ChannelFaceMap::iterator faceMapPos = m_channelFaces.find(remoteEndpoint);
-  if (faceMapPos == m_channelFaces.end())
+  auto it = m_channelFaces.find(remoteEndpoint);
+  if (it == m_channelFaces.end())
     {
       if (socket->local_endpoint().address().is_loopback())
         face = make_shared<TcpLocalFace>(socket, isOnDemand);
       else
         face = make_shared<TcpFace>(socket, isOnDemand);
 
-      face->onFail.connectSingleShot(bind(&TcpChannel::afterFaceFailed, this, remoteEndpoint));
+      face->onFail.connectSingleShot([this, remoteEndpoint] (const std::string&) {
+        NFD_LOG_TRACE("Erasing " << remoteEndpoint << " from channel face map");
+        m_channelFaces.erase(remoteEndpoint);
+      });
 
       m_channelFaces[remoteEndpoint] = face;
     }
   else
     {
       // we've already created a a face for this endpoint, just reuse it
-      face = faceMapPos->second;
+      face = it->second;
 
       boost::system::error_code error;
       socket->shutdown(ip::tcp::socket::shutdown_both, error);
@@ -135,50 +133,47 @@
 }
 
 void
-TcpChannel::afterFaceFailed(tcp::Endpoint &remoteEndpoint)
+TcpChannel::accept(const FaceCreatedCallback& onFaceCreated,
+                   const ConnectFailedCallback& onAcceptFailed)
 {
-  NFD_LOG_DEBUG("afterFaceFailed: " << remoteEndpoint);
-  m_channelFaces.erase(remoteEndpoint);
+  auto socket = make_shared<ip::tcp::socket>(ref(getGlobalIoService()));
+
+  m_acceptor.async_accept(*socket,
+                          bind(&TcpChannel::handleAccept, this,
+                               boost::asio::placeholders::error,
+                               socket, onFaceCreated, onAcceptFailed));
 }
 
 void
-TcpChannel::handleSuccessfulAccept(const boost::system::error_code& error,
-                                   const shared_ptr<boost::asio::ip::tcp::socket>& socket,
-                                   const FaceCreatedCallback& onFaceCreated,
-                                   const ConnectFailedCallback& onAcceptFailed)
+TcpChannel::handleAccept(const boost::system::error_code& error,
+                         const shared_ptr<boost::asio::ip::tcp::socket>& socket,
+                         const FaceCreatedCallback& onFaceCreated,
+                         const ConnectFailedCallback& onAcceptFailed)
 {
   if (error) {
-    if (error == boost::system::errc::operation_canceled) // when socket is closed by someone
+    if (error == boost::asio::error::operation_aborted) // when the socket is closed by someone
       return;
 
-    NFD_LOG_DEBUG("Connect to remote endpoint failed: "
-                  << error.category().message(error.value()));
-
-    if (static_cast<bool>(onAcceptFailed))
-      onAcceptFailed("Connect to remote endpoint failed: " +
-                     error.category().message(error.value()));
+    NFD_LOG_DEBUG("[" << m_localEndpoint << "] Accept failed: " << error.message());
+    if (onAcceptFailed)
+      onAcceptFailed(error.message());
     return;
   }
 
-  // prepare accepting the next connection
-  shared_ptr<ip::tcp::socket> clientSocket =
-    make_shared<ip::tcp::socket>(ref(getGlobalIoService()));
-  m_acceptor->async_accept(*clientSocket,
-                           bind(&TcpChannel::handleSuccessfulAccept, this, _1,
-                                clientSocket,
-                                onFaceCreated, onAcceptFailed));
+  NFD_LOG_DEBUG("[" << m_localEndpoint << "] Connection from " << socket->remote_endpoint());
 
-  NFD_LOG_DEBUG("[" << m_localEndpoint << "] "
-                "<< Connection from " << socket->remote_endpoint());
+  // prepare accepting the next connection
+  accept(onFaceCreated, onAcceptFailed);
+
   createFace(socket, onFaceCreated, true);
 }
 
 void
-TcpChannel::handleSuccessfulConnect(const boost::system::error_code& error,
-                                    const shared_ptr<ip::tcp::socket>& socket,
-                                    const scheduler::EventId& connectTimeoutEvent,
-                                    const FaceCreatedCallback& onFaceCreated,
-                                    const ConnectFailedCallback& onConnectFailed)
+TcpChannel::handleConnect(const boost::system::error_code& error,
+                          const shared_ptr<ip::tcp::socket>& socket,
+                          const scheduler::EventId& connectTimeoutEvent,
+                          const FaceCreatedCallback& onFaceCreated,
+                          const ConnectFailedCallback& onConnectFailed)
 {
   scheduler::cancel(connectTimeoutEvent);
 
@@ -191,33 +186,34 @@
 #else
   if (error) {
 #endif
-
-    if (error == boost::system::errc::operation_canceled) // when socket is closed by someone
+    if (error == boost::asio::error::operation_aborted) // when the socket is closed by someone
       return;
 
     socket->close();
 
-    NFD_LOG_DEBUG("Connect to remote endpoint failed: "
-                  << error.category().message(error.value()));
-
-    onConnectFailed("Connect to remote endpoint failed: " +
-                    error.category().message(error.value()));
+    NFD_LOG_DEBUG("[" << m_localEndpoint << "] Connect failed: " << error.message());
+    if (onConnectFailed)
+      onConnectFailed(error.message());
     return;
   }
 
-  NFD_LOG_DEBUG("[" << m_localEndpoint << "] "
-                ">> Connection to " << socket->remote_endpoint());
+  NFD_LOG_DEBUG("[" << m_localEndpoint << "] Connected to " << socket->remote_endpoint());
 
   createFace(socket, onFaceCreated, false);
 }
 
 void
-TcpChannel::handleFailedConnect(const shared_ptr<ip::tcp::socket>& socket,
-                                const ConnectFailedCallback& onConnectFailed)
+TcpChannel::handleConnectTimeout(const shared_ptr<ip::tcp::socket>& socket,
+                                 const ConnectFailedCallback& onConnectFailed)
 {
   NFD_LOG_DEBUG("Connect to remote endpoint timed out");
-  onConnectFailed("Connect to remote endpoint timed out");
-  socket->close(); // abort the connection
+
+  // abort the connection attempt
+  boost::system::error_code error;
+  socket->close(error);
+
+  if (onConnectFailed)
+    onConnectFailed("Connect to remote endpoint timed out");
 }
 
 } // namespace nfd
diff --git a/daemon/face/tcp-channel.hpp b/daemon/face/tcp-channel.hpp
index 25c5fb0..ba59dbe 100644
--- a/daemon/face/tcp-channel.hpp
+++ b/daemon/face/tcp-channel.hpp
@@ -27,7 +27,6 @@
 #define NFD_DAEMON_FACE_TCP_CHANNEL_HPP
 
 #include "channel.hpp"
-#include "tcp-face.hpp"
 #include "core/scheduler.hpp"
 
 namespace nfd {
@@ -55,9 +54,6 @@
   explicit
   TcpChannel(const tcp::Endpoint& localEndpoint);
 
-  virtual
-  ~TcpChannel();
-
   /**
    * \brief Enable listening on the local endpoint, accept connections,
    *        and create faces when remote host makes a connection
@@ -97,39 +93,37 @@
              bool isOnDemand);
 
   void
-  afterFaceFailed(tcp::Endpoint &endpoint);
+  accept(const FaceCreatedCallback& onFaceCreated,
+         const ConnectFailedCallback& onConnectFailed);
 
   void
-  handleSuccessfulAccept(const boost::system::error_code& error,
-                         const shared_ptr<boost::asio::ip::tcp::socket>& socket,
-                         const FaceCreatedCallback& onFaceCreated,
-                         const ConnectFailedCallback& onConnectFailed);
+  handleAccept(const boost::system::error_code& error,
+               const shared_ptr<boost::asio::ip::tcp::socket>& socket,
+               const FaceCreatedCallback& onFaceCreated,
+               const ConnectFailedCallback& onConnectFailed);
 
   void
-  handleSuccessfulConnect(const boost::system::error_code& error,
-                          const shared_ptr<boost::asio::ip::tcp::socket>& socket,
-                          const scheduler::EventId& connectTimeoutEvent,
-                          const FaceCreatedCallback& onFaceCreated,
-                          const ConnectFailedCallback& onConnectFailed);
+  handleConnect(const boost::system::error_code& error,
+                const shared_ptr<boost::asio::ip::tcp::socket>& socket,
+                const scheduler::EventId& connectTimeoutEvent,
+                const FaceCreatedCallback& onFaceCreated,
+                const ConnectFailedCallback& onConnectFailed);
 
   void
-  handleFailedConnect(const shared_ptr<boost::asio::ip::tcp::socket>& socket,
-                      const ConnectFailedCallback& onConnectFailed);
+  handleConnectTimeout(const shared_ptr<boost::asio::ip::tcp::socket>& socket,
+                       const ConnectFailedCallback& onConnectFailed);
 
 private:
+  std::map<tcp::Endpoint, shared_ptr<Face>> m_channelFaces;
+
+  boost::asio::ip::tcp::acceptor m_acceptor;
   tcp::Endpoint m_localEndpoint;
-
-  typedef std::map< tcp::Endpoint, shared_ptr<Face> > ChannelFaceMap;
-  ChannelFaceMap m_channelFaces;
-
-  bool m_isListening;
-  shared_ptr<boost::asio::ip::tcp::acceptor> m_acceptor;
 };
 
 inline bool
 TcpChannel::isListening() const
 {
-  return m_isListening;
+  return m_acceptor.is_open();
 }
 
 } // namespace nfd
diff --git a/daemon/face/udp-channel.cpp b/daemon/face/udp-channel.cpp
index fd79d9d..bd860cc 100644
--- a/daemon/face/udp-channel.cpp
+++ b/daemon/face/udp-channel.cpp
@@ -24,6 +24,7 @@
  */
 
 #include "udp-channel.hpp"
+#include "udp-face.hpp"
 #include "core/global-io.hpp"
 
 namespace nfd {
@@ -38,64 +39,55 @@
   , m_isListening(false)
   , m_idleFaceTimeout(timeout)
 {
-  /// \todo the reuse_address works as we want in Linux, but in other system could be different.
-  ///       We need to check this
-  ///       (SO_REUSEADDR doesn't behave uniformly in different OS)
+  setUri(FaceUri(m_localEndpoint));
 
   m_socket = make_shared<ip::udp::socket>(ref(getGlobalIoService()));
   m_socket->open(m_localEndpoint.protocol());
-  m_socket->set_option(boost::asio::ip::udp::socket::reuse_address(true));
+  m_socket->set_option(ip::udp::socket::reuse_address(true));
   if (m_localEndpoint.address().is_v6())
-    {
-      m_socket->set_option(ip::v6_only(true));
-    }
+    m_socket->set_option(ip::v6_only(true));
 
   try {
     m_socket->bind(m_localEndpoint);
   }
-  catch (boost::system::system_error& e) {
-    //The bind failed, so the socket is useless now
+  catch (const boost::system::system_error& e) {
+    // bind failed, so the socket is useless now
     m_socket->close();
-    throw Error("Failed to properly configure the socket. "
-                "UdpChannel creation aborted, check the address (" + std::string(e.what()) + ")");
+    throw Error("bind failed: " + std::string(e.what()));
   }
-
-  this->setUri(FaceUri(localEndpoint));
 }
 
 void
 UdpChannel::listen(const FaceCreatedCallback& onFaceCreated,
-                   const ConnectFailedCallback& onListenFailed)
+                   const ConnectFailedCallback& onReceiveFailed)
 {
-  if (m_isListening) {
-    throw Error("Listen already called on this channel");
+  if (isListening()) {
+    NFD_LOG_WARN("[" << m_localEndpoint << "] Already listening");
+    return;
   }
   m_isListening = true;
 
-  onFaceCreatedNewPeerCallback = onFaceCreated;
-  onConnectFailedNewPeerCallback = onListenFailed;
-
   m_socket->async_receive_from(boost::asio::buffer(m_inputBuffer, ndn::MAX_NDN_PACKET_SIZE),
                                m_newRemoteEndpoint,
-                               bind(&UdpChannel::newPeer, this,
+                               bind(&UdpChannel::handleNewPeer, this,
                                     boost::asio::placeholders::error,
-                                    boost::asio::placeholders::bytes_transferred));
+                                    boost::asio::placeholders::bytes_transferred,
+                                    onFaceCreated, onReceiveFailed));
 }
 
-
 void
 UdpChannel::connect(const udp::Endpoint& remoteEndpoint,
                     const FaceCreatedCallback& onFaceCreated,
                     const ConnectFailedCallback& onConnectFailed)
 {
-  ChannelFaceMap::iterator i = m_channelFaces.find(remoteEndpoint);
-  if (i != m_channelFaces.end()) {
-    i->second->setOnDemand(false);
-    onFaceCreated(i->second);
+  auto it = m_channelFaces.find(remoteEndpoint);
+  if (it != m_channelFaces.end()) {
+    it->second->setOnDemand(false);
+    onFaceCreated(it->second);
     return;
   }
 
-  //creating a new socket for the face that will be created soon
+  // creating a new socket for the face that will be created soon
   shared_ptr<ip::udp::socket> clientSocket =
     make_shared<ip::udp::socket>(ref(getGlobalIoService()));
 
@@ -109,11 +101,12 @@
     //async_connect, make sure that if in the meantime we receive a UDP pkt from
     //that endpoint nothing bad happen (it's difficult, but it could happen)
   }
-  catch (boost::system::system_error& e) {
+  catch (const boost::system::system_error& e) {
     clientSocket->close();
     onConnectFailed("Failed to configure socket (" + std::string(e.what()) + ")");
     return;
   }
+
   createFace(clientSocket, onFaceCreated, false);
 }
 
@@ -123,7 +116,6 @@
   return m_channelFaces.size();
 }
 
-
 shared_ptr<UdpFace>
 UdpChannel::createFace(const shared_ptr<ip::udp::socket>& socket,
                        const FaceCreatedCallback& onFaceCreated,
@@ -133,19 +125,22 @@
 
   shared_ptr<UdpFace> face;
 
-  ChannelFaceMap::iterator faceMapPos = m_channelFaces.find(remoteEndpoint);
-  if (faceMapPos == m_channelFaces.end())
+  auto it = m_channelFaces.find(remoteEndpoint);
+  if (it == m_channelFaces.end())
     {
       face = make_shared<UdpFace>(socket, isOnDemand, m_idleFaceTimeout);
 
-      face->onFail.connectSingleShot(bind(&UdpChannel::afterFaceFailed, this, remoteEndpoint));
+      face->onFail.connectSingleShot([this, remoteEndpoint] (const std::string&) {
+        NFD_LOG_TRACE("Erasing " << remoteEndpoint << " from channel face map");
+        m_channelFaces.erase(remoteEndpoint);
+      });
 
       m_channelFaces[remoteEndpoint] = face;
     }
   else
     {
       // we've already created a a face for this endpoint, just reuse it
-      face = faceMapPos->second;
+      face = it->second;
 
       boost::system::error_code error;
       socket->shutdown(ip::udp::socket::shutdown_both, error);
@@ -160,23 +155,27 @@
 }
 
 void
-UdpChannel::newPeer(const boost::system::error_code& error,
-                    size_t nBytesReceived)
+UdpChannel::handleNewPeer(const boost::system::error_code& error,
+                          size_t nBytesReceived,
+                          const FaceCreatedCallback& onFaceCreated,
+                          const ConnectFailedCallback& onReceiveFailed)
 {
   if (error) {
-    if (error == boost::asio::error::operation_aborted)
+    if (error == boost::asio::error::operation_aborted) // when the socket is closed by someone
       return;
 
-    NFD_LOG_ERROR("newPeer: " << error.message());
+    NFD_LOG_DEBUG("[" << m_localEndpoint << "] Receive failed: " << error.message());
+    if (onReceiveFailed)
+      onReceiveFailed(error.message());
     return;
   }
 
-  NFD_LOG_DEBUG("newPeer from " << m_newRemoteEndpoint);
+  NFD_LOG_DEBUG("[" << m_localEndpoint << "] New peer " << m_newRemoteEndpoint);
 
   shared_ptr<UdpFace> face;
 
-  ChannelFaceMap::iterator i = m_channelFaces.find(m_newRemoteEndpoint);
-  if (i != m_channelFaces.end()) {
+  auto it = m_channelFaces.find(m_newRemoteEndpoint);
+  if (it != m_channelFaces.end()) {
     //The face already exists.
     //Usually this shouldn't happen, because the channel creates a Udpface
     //as soon as it receives a pkt from a new endpoint and then the
@@ -187,10 +186,8 @@
     //ready. In this case, the channel has to pass the pkt to the face
 
     NFD_LOG_DEBUG("The creation of the face for the remote endpoint "
-                  << m_newRemoteEndpoint
-                  << " is in progress");
-
-    face = i->second;
+                  << m_newRemoteEndpoint << " is already in progress");
+    face = it->second;
   }
   else {
     shared_ptr<ip::udp::socket> clientSocket =
@@ -198,6 +195,7 @@
     clientSocket->open(m_localEndpoint.protocol());
     clientSocket->set_option(ip::udp::socket::reuse_address(true));
     clientSocket->bind(m_localEndpoint);
+
     boost::system::error_code ec;
     clientSocket->connect(m_newRemoteEndpoint, ec);
     if (ec) {
@@ -206,9 +204,7 @@
       return;
     }
 
-    face = createFace(clientSocket,
-                      onFaceCreatedNewPeerCallback,
-                      true);
+    face = createFace(clientSocket, onFaceCreated, true);
   }
 
   // dispatch the datagram to the face for processing
@@ -216,17 +212,10 @@
 
   m_socket->async_receive_from(boost::asio::buffer(m_inputBuffer, ndn::MAX_NDN_PACKET_SIZE),
                                m_newRemoteEndpoint,
-                               bind(&UdpChannel::newPeer, this,
+                               bind(&UdpChannel::handleNewPeer, this,
                                     boost::asio::placeholders::error,
-                                    boost::asio::placeholders::bytes_transferred));
-}
-
-
-void
-UdpChannel::afterFaceFailed(udp::Endpoint &endpoint)
-{
-  NFD_LOG_DEBUG("afterFaceFailed: " << endpoint);
-  m_channelFaces.erase(endpoint);
+                                    boost::asio::placeholders::bytes_transferred,
+                                    onFaceCreated, onReceiveFailed));
 }
 
 } // namespace nfd
diff --git a/daemon/face/udp-channel.hpp b/daemon/face/udp-channel.hpp
index b51d50d..1451713 100644
--- a/daemon/face/udp-channel.hpp
+++ b/daemon/face/udp-channel.hpp
@@ -27,8 +27,6 @@
 #define NFD_DAEMON_FACE_UDP_CHANNEL_HPP
 
 #include "channel.hpp"
-#include "core/global-io.hpp"
-#include "udp-face.hpp"
 
 namespace nfd {
 
@@ -36,10 +34,10 @@
 typedef boost::asio::ip::udp::endpoint Endpoint;
 } // namespace udp
 
+class UdpFace;
+
 /**
  * \brief Class implementing UDP-based channel to create faces
- *
- *
  */
 class UdpChannel : public Channel
 {
@@ -79,7 +77,7 @@
    */
   void
   listen(const FaceCreatedCallback& onFaceCreated,
-         const ConnectFailedCallback& onAcceptFailed);
+         const ConnectFailedCallback& onReceiveFailed);
 
   /**
    * \brief Create a face by establishing connection to remote endpoint
@@ -97,22 +95,28 @@
   size_t
   size() const;
 
+  bool
+  isListening() const;
+
 private:
   shared_ptr<UdpFace>
   createFace(const shared_ptr<boost::asio::ip::udp::socket>& socket,
              const FaceCreatedCallback& onFaceCreated,
              bool isOnDemand);
-  void
-  afterFaceFailed(udp::Endpoint& endpoint);
 
   /**
-   * \brief The UdpChannel has received a new pkt from a remote endpoint not yet
-   *        associated with any UdpFace
+   * \brief The channel has received a new packet from a remote
+   *        endpoint that is not associated with any UdpFace yet
    */
   void
-  newPeer(const boost::system::error_code& error, size_t nBytesReceived);
+  handleNewPeer(const boost::system::error_code& error,
+                size_t nBytesReceived,
+                const FaceCreatedCallback& onFaceCreated,
+                const ConnectFailedCallback& onReceiveFailed);
 
 private:
+  std::map<udp::Endpoint, shared_ptr<UdpFace>> m_channelFaces;
+
   udp::Endpoint m_localEndpoint;
 
   /**
@@ -121,25 +125,12 @@
   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[ndn::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
    */
@@ -152,6 +143,12 @@
   time::seconds m_idleFaceTimeout;
 };
 
+inline bool
+UdpChannel::isListening() const
+{
+  return m_isListening;
+}
+
 } // namespace nfd
 
 #endif // NFD_DAEMON_FACE_UDP_CHANNEL_HPP
diff --git a/daemon/face/unix-stream-channel.cpp b/daemon/face/unix-stream-channel.cpp
index d64f333..52df192 100644
--- a/daemon/face/unix-stream-channel.cpp
+++ b/daemon/face/unix-stream-channel.cpp
@@ -1,11 +1,12 @@
 /* -*- 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
+ * Copyright (c) 2014-2015,  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.
@@ -20,9 +21,10 @@
  *
  * 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/>.
- **/
+ */
 
 #include "unix-stream-channel.hpp"
+#include "unix-stream-face.hpp"
 #include "core/global-io.hpp"
 
 #include <boost/filesystem.hpp>
@@ -35,23 +37,22 @@
 using namespace boost::asio::local;
 
 UnixStreamChannel::UnixStreamChannel(const unix_stream::Endpoint& endpoint)
-  : m_endpoint(endpoint)
-  , m_isListening(false)
+  : m_acceptor(getGlobalIoService())
+  , m_endpoint(endpoint)
 {
-  setUri(FaceUri(endpoint));
+  setUri(FaceUri(m_endpoint));
 }
 
 UnixStreamChannel::~UnixStreamChannel()
 {
-  if (m_isListening)
-    {
-      // use the non-throwing variants during destruction
-      // and ignore any errors
-      boost::system::error_code error;
-      m_acceptor->close(error);
-      NFD_LOG_TRACE("[" << m_endpoint << "] Removing socket file");
-      boost::filesystem::remove(m_endpoint.path(), error);
-    }
+  if (isListening()) {
+    // use the non-throwing variants during destruction
+    // and ignore any errors
+    boost::system::error_code error;
+    m_acceptor.close(error);
+    NFD_LOG_DEBUG("[" << m_endpoint << "] Removing socket file");
+    boost::filesystem::remove(m_endpoint.path(), error);
+  }
 }
 
 void
@@ -59,7 +60,7 @@
                           const ConnectFailedCallback& onAcceptFailed,
                           int backlog/* = acceptor::max_connections*/)
 {
-  if (m_isListening) {
+  if (isListening()) {
     NFD_LOG_WARN("[" << m_endpoint << "] Already listening");
     return;
   }
@@ -69,78 +70,73 @@
   fs::path socketPath(m_endpoint.path());
   fs::file_type type = fs::symlink_status(socketPath).type();
 
-  if (type == fs::socket_file)
-    {
-      boost::system::error_code error;
-      stream_protocol::socket socket(getGlobalIoService());
-      socket.connect(m_endpoint, error);
-      NFD_LOG_TRACE("[" << m_endpoint << "] connect() on existing socket file returned: "
-                    + error.message());
-      if (!error)
-        {
-          // someone answered, leave the socket alone
-          throw Error("Socket file at " + m_endpoint.path()
-                      + " belongs to another NFD process");
-        }
-      else if (error == boost::system::errc::connection_refused ||
-               error == boost::system::errc::timed_out)
-        {
-          // no one is listening on the remote side,
-          // we can safely remove the socket file
-          NFD_LOG_INFO("[" << m_endpoint << "] Removing stale socket file");
-          fs::remove(socketPath);
-        }
+  if (type == fs::socket_file) {
+    boost::system::error_code error;
+    stream_protocol::socket socket(getGlobalIoService());
+    socket.connect(m_endpoint, error);
+    NFD_LOG_TRACE("[" << m_endpoint << "] connect() on existing socket file returned: "
+                  + error.message());
+    if (!error) {
+      // someone answered, leave the socket alone
+      throw Error("Socket file at " + m_endpoint.path()
+                  + " belongs to another NFD process");
     }
-  else if (type != fs::file_not_found)
-    {
-      throw Error(m_endpoint.path() + " already exists and is not a socket file");
+    else if (error == boost::asio::error::connection_refused ||
+             error == boost::asio::error::timed_out) {
+      // no one is listening on the remote side,
+      // we can safely remove the stale socket
+      NFD_LOG_DEBUG("[" << m_endpoint << "] Removing stale socket file");
+      fs::remove(socketPath);
     }
+  }
+  else if (type != fs::file_not_found) {
+    throw Error(m_endpoint.path() + " already exists and is not a socket file");
+  }
 
-  m_acceptor = make_shared<stream_protocol::acceptor>(ref(getGlobalIoService()));
-  m_acceptor->open();
-  m_acceptor->bind(m_endpoint);
-  m_acceptor->listen(backlog);
-  m_isListening = true;
+  m_acceptor.open();
+  m_acceptor.bind(m_endpoint);
+  m_acceptor.listen(backlog);
 
-  if (::chmod(m_endpoint.path().c_str(), 0666) < 0)
-    {
-      throw Error("Failed to chmod() socket file at " + m_endpoint.path());
-    }
+  if (::chmod(m_endpoint.path().c_str(), 0666) < 0) {
+    throw Error("chmod(" + m_endpoint.path() + ") failed: " + std::strerror(errno));
+  }
 
-  shared_ptr<stream_protocol::socket> clientSocket =
-    make_shared<stream_protocol::socket>(ref(getGlobalIoService()));
-
-  m_acceptor->async_accept(*clientSocket,
-                           bind(&UnixStreamChannel::handleSuccessfulAccept, this,
-                                boost::asio::placeholders::error, clientSocket,
-                                onFaceCreated, onAcceptFailed));
+  // start accepting connections
+  accept(onFaceCreated, onAcceptFailed);
 }
 
 void
-UnixStreamChannel::handleSuccessfulAccept(const boost::system::error_code& error,
-                                          const shared_ptr<stream_protocol::socket>& socket,
-                                          const FaceCreatedCallback& onFaceCreated,
-                                          const ConnectFailedCallback& onAcceptFailed)
+UnixStreamChannel::accept(const FaceCreatedCallback &onFaceCreated,
+                          const ConnectFailedCallback &onAcceptFailed)
+{
+  auto socket = make_shared<stream_protocol::socket>(ref(getGlobalIoService()));
+
+  m_acceptor.async_accept(*socket,
+                          bind(&UnixStreamChannel::handleAccept, this,
+                               boost::asio::placeholders::error,
+                               socket, onFaceCreated, onAcceptFailed));
+}
+
+void
+UnixStreamChannel::handleAccept(const boost::system::error_code& error,
+                                const shared_ptr<stream_protocol::socket>& socket,
+                                const FaceCreatedCallback& onFaceCreated,
+                                const ConnectFailedCallback& onAcceptFailed)
 {
   if (error) {
-    if (error == boost::system::errc::operation_canceled) // when socket is closed by someone
+    if (error == boost::asio::error::operation_aborted) // when the socket is closed by someone
       return;
 
-    NFD_LOG_DEBUG("[" << m_endpoint << "] Connection failed: " << error.message());
-    onAcceptFailed("Connection failed: " + error.message());
+    NFD_LOG_DEBUG("[" << m_endpoint << "] Accept failed: " << error.message());
+    if (onAcceptFailed)
+      onAcceptFailed(error.message());
     return;
   }
 
-  NFD_LOG_DEBUG("[" << m_endpoint << "] << Incoming connection");
-
-  shared_ptr<stream_protocol::socket> clientSocket =
-    make_shared<stream_protocol::socket>(ref(getGlobalIoService()));
+  NFD_LOG_DEBUG("[" << m_endpoint << "] Incoming connection");
 
   // prepare accepting the next connection
-  m_acceptor->async_accept(*clientSocket,
-                           bind(&UnixStreamChannel::handleSuccessfulAccept, this,
-                                boost::asio::placeholders::error, clientSocket,
-                                onFaceCreated, onAcceptFailed));
+  accept(onFaceCreated, onAcceptFailed);
 
   shared_ptr<UnixStreamFace> face = make_shared<UnixStreamFace>(socket);
   onFaceCreated(face);
diff --git a/daemon/face/unix-stream-channel.hpp b/daemon/face/unix-stream-channel.hpp
index c923c39..c90dcb0 100644
--- a/daemon/face/unix-stream-channel.hpp
+++ b/daemon/face/unix-stream-channel.hpp
@@ -26,7 +26,6 @@
 #define NFD_DAEMON_FACE_UNIX_STREAM_CHANNEL_HPP
 
 #include "channel.hpp"
-#include "unix-stream-face.hpp"
 
 namespace nfd {
 
@@ -60,8 +59,7 @@
   explicit
   UnixStreamChannel(const unix_stream::Endpoint& endpoint);
 
-  virtual
-  ~UnixStreamChannel();
+  ~UnixStreamChannel() DECL_OVERRIDE;
 
   /**
    * \brief Enable listening on the local endpoint, accept connections,
@@ -77,19 +75,31 @@
          const ConnectFailedCallback& onAcceptFailed,
          int backlog = boost::asio::local::stream_protocol::acceptor::max_connections);
 
-private:
-  void
-  handleSuccessfulAccept(const boost::system::error_code& error,
-                         const shared_ptr<boost::asio::local::stream_protocol::socket>& socket,
-                         const FaceCreatedCallback& onFaceCreated,
-                         const ConnectFailedCallback& onConnectFailed);
+  bool
+  isListening() const;
 
 private:
+  void
+  accept(const FaceCreatedCallback& onFaceCreated,
+         const ConnectFailedCallback& onAcceptFailed);
+
+  void
+  handleAccept(const boost::system::error_code& error,
+               const shared_ptr<boost::asio::local::stream_protocol::socket>& socket,
+               const FaceCreatedCallback& onFaceCreated,
+               const ConnectFailedCallback& onAcceptFailed);
+
+private:
+  boost::asio::local::stream_protocol::acceptor m_acceptor;
   unix_stream::Endpoint m_endpoint;
-  shared_ptr<boost::asio::local::stream_protocol::acceptor> m_acceptor;
-  bool m_isListening;
 };
 
+inline bool
+UnixStreamChannel::isListening() const
+{
+  return m_acceptor.is_open();
+}
+
 } // namespace nfd
 
 #endif // NFD_DAEMON_FACE_UNIX_STREAM_CHANNEL_HPP
diff --git a/daemon/face/websocket-channel.cpp b/daemon/face/websocket-channel.cpp
index 016dcac..855dd99 100644
--- a/daemon/face/websocket-channel.cpp
+++ b/daemon/face/websocket-channel.cpp
@@ -24,6 +24,8 @@
  */
 
 #include "websocket-channel.hpp"
+#include "core/global-io.hpp"
+#include "core/scheduler.hpp"
 
 #include <boost/date_time/posix_time/posix_time.hpp>
 
@@ -31,13 +33,13 @@
 
 NFD_LOG_INIT("WebSocketChannel");
 
-using namespace boost::asio;
-
 WebSocketChannel::WebSocketChannel(const websocket::Endpoint& localEndpoint)
   : m_localEndpoint(localEndpoint)
   , m_isListening(false)
   , m_pingInterval(10000)
 {
+  setUri(FaceUri(m_localEndpoint, "ws"));
+
   // Setup WebSocket server
   m_server.clear_access_channels(websocketpp::log::alevel::all);
   m_server.clear_error_channels(websocketpp::log::alevel::all);
@@ -46,19 +48,19 @@
   m_server.set_open_handler(bind(&WebSocketChannel::handleOpen, this, _1));
   m_server.set_close_handler(bind(&WebSocketChannel::handleClose, this, _1));
   m_server.init_asio(&getGlobalIoService());
+
+  // Detect disconnections using ping-pong messages
+  m_server.set_pong_handler(bind(&WebSocketChannel::handlePong, this, _1, _2));
+  m_server.set_pong_timeout_handler(bind(&WebSocketChannel::handlePongTimeout, this, _1, _2));
+
   // Always set SO_REUSEADDR flag
   m_server.set_reuse_addr(true);
-
-  // Detect disconnection using PONG message
-  m_server.set_pong_handler(bind(&WebSocketChannel::handlePong, this, _1, _2));
-  m_server.set_pong_timeout_handler(bind(&WebSocketChannel::handlePongTimeout,
-                                         this, _1, _2));
-
-  this->setUri(FaceUri(localEndpoint, "ws"));
 }
 
-WebSocketChannel::~WebSocketChannel()
+void
+WebSocketChannel::setPingInterval(time::milliseconds interval)
 {
+  m_pingInterval = interval;
 }
 
 void
@@ -70,56 +72,53 @@
 void
 WebSocketChannel::handlePongTimeout(websocketpp::connection_hdl hdl, std::string msg)
 {
-  ChannelFaceMap::iterator it = m_channelFaces.find(hdl);
-  if (it != m_channelFaces.end())
-    {
-      it->second->close();
-      NFD_LOG_DEBUG("handlePongTimeout: remove " << it->second->getRemoteUri());
-      m_channelFaces.erase(it);
-    }
+  auto it = m_channelFaces.find(hdl);
+  if (it != m_channelFaces.end()) {
+    NFD_LOG_TRACE(__func__ << ": " << it->second->getRemoteUri());
+    it->second->close();
+    m_channelFaces.erase(it);
+  }
 }
 
 void
 WebSocketChannel::handlePong(websocketpp::connection_hdl hdl, std::string msg)
 {
-  ChannelFaceMap::iterator it = m_channelFaces.find(hdl);
-  if (it != m_channelFaces.end())
-    {
-      NFD_LOG_TRACE("handlePong: from " << it->second->getRemoteUri());
-    }
+  auto it = m_channelFaces.find(hdl);
+  if (it != m_channelFaces.end()) {
+    NFD_LOG_TRACE("Pong from " << it->second->getRemoteUri());
+  }
 }
 
 void
 WebSocketChannel::handleMessage(websocketpp::connection_hdl hdl,
                                 websocket::Server::message_ptr msg)
 {
-  ChannelFaceMap::iterator it = m_channelFaces.find(hdl);
-  if (it != m_channelFaces.end())
-    {
-      it->second->handleReceive(msg->get_payload());
-    }
+  auto it = m_channelFaces.find(hdl);
+  if (it != m_channelFaces.end()) {
+    it->second->handleReceive(msg->get_payload());
+  }
 }
 
 void
 WebSocketChannel::handleOpen(websocketpp::connection_hdl hdl)
 {
   std::string remote;
-  try
-    {
-      remote = "wsclient://" + m_server.get_con_from_hdl(hdl)->get_remote_endpoint();
-    }
-  catch (websocketpp::lib::error_code&)
-    {
-      NFD_LOG_DEBUG("handleOpen: cannot get remote uri");
-      websocketpp::lib::error_code ecode;
-      m_server.close(hdl, websocketpp::close::status::normal, "closed by channel", ecode);
-    }
-  shared_ptr<WebSocketFace> face = ndn::make_shared<WebSocketFace>(FaceUri(remote), this->getUri(),
-                                                                   hdl, ref(m_server));
+  try {
+    remote = "wsclient://" + m_server.get_con_from_hdl(hdl)->get_remote_endpoint();
+  }
+  catch (const websocketpp::lib::error_code& e) {
+    NFD_LOG_WARN("Cannot get remote URI");
+    websocketpp::lib::error_code error;
+    m_server.close(hdl, websocketpp::close::status::normal, "closed by channel", error);
+    return;
+  }
+
+  auto face = make_shared<WebSocketFace>(FaceUri(remote), this->getUri(),
+                                         hdl, ref(m_server));
   m_onFaceCreatedCallback(face);
   m_channelFaces[hdl] = face;
 
-  // Schedule PING message
+  // Schedule ping message
   scheduler::EventId pingEvent = scheduler::schedule(m_pingInterval,
                                                      bind(&WebSocketChannel::sendPing, this, hdl));
   face->setPingEventId(pingEvent);
@@ -128,62 +127,49 @@
 void
 WebSocketChannel::sendPing(websocketpp::connection_hdl hdl)
 {
-  ChannelFaceMap::iterator it = m_channelFaces.find(hdl);
-  if (it != m_channelFaces.end())
-    {
-      try
-        {
-          m_server.ping(hdl, "NFD-WebSocket");
-        }
-      catch (websocketpp::lib::error_code&)
-        {
-          it->second->close();
-          NFD_LOG_DEBUG("sendPing: failed to ping " << it->second->getRemoteUri());
-          m_channelFaces.erase(it);
-        }
+  auto it = m_channelFaces.find(hdl);
+  if (it != m_channelFaces.end()) {
+    NFD_LOG_TRACE("Sending ping to " << it->second->getRemoteUri());
 
-      NFD_LOG_TRACE("sendPing: to " << it->second->getRemoteUri());
-
-      // Schedule next PING message
-      scheduler::EventId pingEvent = scheduler::schedule(m_pingInterval,
-                                         bind(&WebSocketChannel::sendPing, this, hdl));
-      it->second->setPingEventId(pingEvent);
+    try {
+      m_server.ping(hdl, "NFD-WebSocket");
     }
+    catch (const websocketpp::lib::error_code& e) {
+      NFD_LOG_WARN("Failed to ping " << it->second->getRemoteUri());
+      it->second->close();
+      m_channelFaces.erase(it);
+      return;
+    }
+
+    // Schedule next ping message
+    scheduler::EventId pingEvent = scheduler::schedule(m_pingInterval,
+                                                       bind(&WebSocketChannel::sendPing, this, hdl));
+    it->second->setPingEventId(pingEvent);
+  }
 }
 
 void
 WebSocketChannel::handleClose(websocketpp::connection_hdl hdl)
 {
-  ChannelFaceMap::iterator it = m_channelFaces.find(hdl);
-  if (it != m_channelFaces.end())
-    {
-      it->second->close();
-      NFD_LOG_DEBUG("handleClose: remove " << it->second->getRemoteUri());
-      m_channelFaces.erase(it);
-    }
+  auto it = m_channelFaces.find(hdl);
+  if (it != m_channelFaces.end()) {
+    NFD_LOG_TRACE(__func__ << ": " << it->second->getRemoteUri());
+    it->second->close();
+    m_channelFaces.erase(it);
+  }
 }
 
-
 void
 WebSocketChannel::listen(const FaceCreatedCallback& onFaceCreated)
 {
-  if (m_isListening)
-    {
-      throw Error("Listen already called on this channel");
-    }
+  if (isListening()) {
+    NFD_LOG_WARN("[" << m_localEndpoint << "] Already listening");
+    return;
+  }
   m_isListening = true;
 
   m_onFaceCreatedCallback = onFaceCreated;
-
-  try
-    {
-      m_server.listen(m_localEndpoint);
-    }
-  catch (websocketpp::lib::error_code ec)
-    {
-      throw Error("Failed to listen on local endpoint");
-    }
-
+  m_server.listen(m_localEndpoint);
   m_server.start_accept();
 }
 
diff --git a/daemon/face/websocket-channel.hpp b/daemon/face/websocket-channel.hpp
index f7c6ae2..f560ab3 100644
--- a/daemon/face/websocket-channel.hpp
+++ b/daemon/face/websocket-channel.hpp
@@ -27,34 +27,17 @@
 #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,
@@ -66,9 +49,6 @@
   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
@@ -88,11 +68,9 @@
   bool
   isListening() const;
 
+PUBLIC_WITH_TESTS_ELSE_PRIVATE:
   void
-  setPingInterval(time::milliseconds interval)
-  {
-    m_pingInterval = interval;
-  }
+  setPingInterval(time::milliseconds interval);
 
   void
   setPongTimeout(time::milliseconds timeout);
@@ -118,20 +96,16 @@
 
 private:
   websocket::Endpoint m_localEndpoint;
-
   websocket::Server m_server;
 
+  std::map<websocketpp::connection_hdl, shared_ptr<WebSocketFace>,
+           std::owner_less<websocketpp::connection_hdl>> m_channelFaces;
+
   /**
-   * Callbacks for face creation.
-   * New communications are detected using async_receive_from.
-   * Its handler has a fixed signature. No space for the face callback
+   * Callback for face creation
    */
   FaceCreatedCallback m_onFaceCreatedCallback;
 
-  typedef std::map< websocketpp::connection_hdl, shared_ptr<WebSocketFace>,
-                    std::owner_less<websocketpp::connection_hdl> > ChannelFaceMap;
-  ChannelFaceMap m_channelFaces;
-
   /**
    * \brief If true, it means the function listen has already been called
    */