face: use new-style async_accept API

Change-Id: Id9de72c0922ec9ea13e5b1d9ded27dd7edf67e38
diff --git a/daemon/face/ethernet-channel.hpp b/daemon/face/ethernet-channel.hpp
index 8c11824..302b6e7 100644
--- a/daemon/face/ethernet-channel.hpp
+++ b/daemon/face/ethernet-channel.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2022,  Regents of the University of California,
+ * Copyright (c) 2014-2023,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -36,13 +36,13 @@
 namespace nfd::face {
 
 /**
- * \brief Class implementing Ethernet-based channel to create faces
+ * \brief Class implementing an Ethernet-based channel to create faces.
  */
 class EthernetChannel final : public Channel
 {
 public:
   /**
-   * \brief EthernetChannel-related error
+   * \brief EthernetChannel-related error.
    */
   class Error : public std::runtime_error
   {
@@ -51,10 +51,10 @@
   };
 
   /**
-   * \brief Create an Ethernet channel on the given \p localEndpoint (network interface)
+   * \brief Create an Ethernet channel on the given \p localEndpoint (network interface).
    *
-   * To enable creation of faces upon incoming connections,
-   * one needs to explicitly call EthernetChannel::listen method.
+   * To enable the creation of faces upon incoming connections, one needs to
+   * explicitly call listen().
    */
   EthernetChannel(shared_ptr<const ndn::net::NetworkInterface> localEndpoint,
                   time::nanoseconds idleTimeout);
@@ -72,7 +72,7 @@
   }
 
   /**
-   * \brief Create a unicast Ethernet face toward \p remoteEndpoint
+   * \brief Create a unicast Ethernet face toward \p remoteEndpoint.
    */
   void
   connect(const ethernet::Address& remoteEndpoint,
@@ -81,7 +81,7 @@
           const FaceCreationFailedCallback& onConnectFailed);
 
   /**
-   * \brief Start listening
+   * \brief Start listening.
    *
    * Enable listening on the local endpoint, waiting for incoming frames,
    * and creating a face when a frame is received from a new remote host.
diff --git a/daemon/face/tcp-channel.cpp b/daemon/face/tcp-channel.cpp
index 17f2786..38fcd05 100644
--- a/daemon/face/tcp-channel.cpp
+++ b/daemon/face/tcp-channel.cpp
@@ -40,9 +40,8 @@
 TcpChannel::TcpChannel(const tcp::Endpoint& localEndpoint, bool wantCongestionMarking,
                        DetermineFaceScopeFromAddress determineFaceScope)
   : m_localEndpoint(localEndpoint)
-  , m_acceptor(getGlobalIoService())
-  , m_socket(getGlobalIoService())
   , m_wantCongestionMarking(wantCongestionMarking)
+  , m_acceptor(getGlobalIoService())
   , m_determineFaceScope(std::move(determineFaceScope))
 {
   setUri(FaceUri(m_localEndpoint));
@@ -163,31 +162,25 @@
 TcpChannel::accept(const FaceCreatedCallback& onFaceCreated,
                    const FaceCreationFailedCallback& onAcceptFailed)
 {
-  m_acceptor.async_accept(m_socket, [=] (const auto& e) { this->handleAccept(e, onFaceCreated, onAcceptFailed); });
-}
-
-void
-TcpChannel::handleAccept(const boost::system::error_code& error,
-                         const FaceCreatedCallback& onFaceCreated,
-                         const FaceCreationFailedCallback& onAcceptFailed)
-{
-  if (error) {
-    if (error != boost::asio::error::operation_aborted) {
-      NFD_LOG_CHAN_DEBUG("Accept failed: " << error.message());
-      if (onAcceptFailed)
-        onAcceptFailed(500, "Accept failed: " + error.message());
+  m_acceptor.async_accept([=] (const boost::system::error_code& error, ip::tcp::socket socket) {
+    if (error) {
+      if (error != boost::asio::error::operation_aborted) {
+        NFD_LOG_CHAN_DEBUG("Accept failed: " << error.message());
+        if (onAcceptFailed)
+          onAcceptFailed(500, "Accept failed: " + error.message());
+      }
+      return;
     }
-    return;
-  }
 
-  NFD_LOG_CHAN_TRACE("Incoming connection from " << m_socket.remote_endpoint());
+    NFD_LOG_CHAN_TRACE("Incoming connection from " << socket.remote_endpoint());
 
-  FaceParams params;
-  params.persistency = ndn::nfd::FACE_PERSISTENCY_ON_DEMAND;
-  createFace(std::move(m_socket), params, onFaceCreated, onAcceptFailed);
+    FaceParams params;
+    params.persistency = ndn::nfd::FACE_PERSISTENCY_ON_DEMAND;
+    createFace(std::move(socket), params, onFaceCreated, onAcceptFailed);
 
-  // prepare accepting the next connection
-  accept(onFaceCreated, onAcceptFailed);
+    // prepare accepting the next connection
+    accept(onFaceCreated, onAcceptFailed);
+  });
 }
 
 void
diff --git a/daemon/face/tcp-channel.hpp b/daemon/face/tcp-channel.hpp
index 1220687..cc000ea 100644
--- a/daemon/face/tcp-channel.hpp
+++ b/daemon/face/tcp-channel.hpp
@@ -105,11 +105,6 @@
          const FaceCreationFailedCallback& onAcceptFailed);
 
   void
-  handleAccept(const boost::system::error_code& error,
-               const FaceCreatedCallback& onFaceCreated,
-               const FaceCreationFailedCallback& onAcceptFailed);
-
-  void
   handleConnect(const boost::system::error_code& error,
                 const tcp::Endpoint& remoteEndpoint,
                 const shared_ptr<boost::asio::ip::tcp::socket>& socket,
@@ -125,10 +120,9 @@
 
 private:
   const tcp::Endpoint m_localEndpoint;
+  const bool m_wantCongestionMarking;
   boost::asio::ip::tcp::acceptor m_acceptor;
-  boost::asio::ip::tcp::socket m_socket;
   std::map<tcp::Endpoint, shared_ptr<Face>> m_channelFaces;
-  bool m_wantCongestionMarking;
   DetermineFaceScopeFromAddress m_determineFaceScope;
 };
 
diff --git a/daemon/face/udp-channel.hpp b/daemon/face/udp-channel.hpp
index f4f53da..e594f64 100644
--- a/daemon/face/udp-channel.hpp
+++ b/daemon/face/udp-channel.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2022,  Regents of the University of California,
+ * Copyright (c) 2014-2023,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -34,17 +34,16 @@
 namespace nfd::face {
 
 /**
- * \brief Class implementing UDP-based channel to create faces
+ * \brief Class implementing a UDP-based channel to create faces.
  */
 class UdpChannel final : public Channel
 {
 public:
   /**
-   * \brief Create a UDP channel on the given \p localEndpoint
+   * \brief Create a UDP channel on the given \p localEndpoint.
    *
-   * To enable creation of faces upon incoming connections,
-   * one needs to explicitly call UdpChannel::listen method.
-   * The created socket is bound to \p localEndpoint.
+   * To enable the creation of faces upon incoming connections, one needs to
+   * explicitly call listen(). The created socket is bound to \p localEndpoint.
    */
   UdpChannel(const udp::Endpoint& localEndpoint,
              time::nanoseconds idleTimeout,
@@ -64,7 +63,7 @@
   }
 
   /**
-   * \brief Create a unicast UDP face toward \p remoteEndpoint
+   * \brief Create a unicast UDP face toward \p remoteEndpoint.
    */
   void
   connect(const udp::Endpoint& remoteEndpoint,
@@ -73,7 +72,7 @@
           const FaceCreationFailedCallback& onConnectFailed);
 
   /**
-   * \brief Start listening
+   * \brief Start listening.
    *
    * Enable listening on the local endpoint, waiting for incoming datagrams,
    * and creating a face when a datagram is received from a new remote host.
@@ -94,7 +93,7 @@
 
   /**
    * \brief The channel has received a packet from a remote
-   *        endpoint not associated with any UDP face yet
+   *        endpoint not associated with any UDP face yet.
    */
   void
   handleNewPeer(const boost::system::error_code& error,
@@ -113,7 +112,7 @@
   std::array<uint8_t, ndn::MAX_NDN_PACKET_SIZE> m_receiveBuffer;
   std::map<udp::Endpoint, shared_ptr<Face>> m_channelFaces;
   const time::nanoseconds m_idleFaceTimeout; ///< Timeout for automatic closure of idle on-demand faces
-  bool m_wantCongestionMarking;
+  const bool m_wantCongestionMarking;
 };
 
 } // namespace nfd::face
diff --git a/daemon/face/unix-stream-channel.cpp b/daemon/face/unix-stream-channel.cpp
index b2bb84a..906d23e 100644
--- a/daemon/face/unix-stream-channel.cpp
+++ b/daemon/face/unix-stream-channel.cpp
@@ -39,10 +39,8 @@
 UnixStreamChannel::UnixStreamChannel(const unix_stream::Endpoint& endpoint,
                                      bool wantCongestionMarking)
   : m_endpoint(endpoint)
-  , m_acceptor(getGlobalIoService())
-  , m_socket(getGlobalIoService())
-  , m_size(0)
   , m_wantCongestionMarking(wantCongestionMarking)
+  , m_acceptor(getGlobalIoService())
 {
   setUri(FaceUri(m_endpoint));
   NFD_LOG_CHAN_INFO("Creating channel");
@@ -112,39 +110,34 @@
 UnixStreamChannel::accept(const FaceCreatedCallback& onFaceCreated,
                           const FaceCreationFailedCallback& onAcceptFailed)
 {
-  m_acceptor.async_accept(m_socket, [=] (const auto& e) { this->handleAccept(e, onFaceCreated, onAcceptFailed); });
-}
-
-void
-UnixStreamChannel::handleAccept(const boost::system::error_code& error,
-                                const FaceCreatedCallback& onFaceCreated,
-                                const FaceCreationFailedCallback& onAcceptFailed)
-{
-  if (error) {
-    if (error != boost::asio::error::operation_aborted) {
-      NFD_LOG_CHAN_DEBUG("Accept failed: " << error.message());
-      if (onAcceptFailed)
-        onAcceptFailed(500, "Accept failed: " + error.message());
+  m_acceptor.async_accept([=] (const boost::system::error_code& error,
+                               boost::asio::local::stream_protocol::socket socket) {
+    if (error) {
+      if (error != boost::asio::error::operation_aborted) {
+        NFD_LOG_CHAN_DEBUG("Accept failed: " << error.message());
+        if (onAcceptFailed)
+          onAcceptFailed(500, "Accept failed: " + error.message());
+      }
+      return;
     }
-    return;
-  }
 
-  NFD_LOG_CHAN_TRACE("Incoming connection via fd " << m_socket.native_handle());
+    NFD_LOG_CHAN_TRACE("Incoming connection via fd " << socket.native_handle());
 
-  GenericLinkService::Options options;
-  options.allowCongestionMarking = m_wantCongestionMarking;
-  auto linkService = make_unique<GenericLinkService>(options);
-  auto transport = make_unique<UnixStreamTransport>(std::move(m_socket));
-  auto face = make_shared<Face>(std::move(linkService), std::move(transport));
-  face->setChannel(weak_from_this());
+    GenericLinkService::Options options;
+    options.allowCongestionMarking = m_wantCongestionMarking;
+    auto linkService = make_unique<GenericLinkService>(options);
+    auto transport = make_unique<UnixStreamTransport>(std::move(socket));
+    auto face = make_shared<Face>(std::move(linkService), std::move(transport));
+    face->setChannel(weak_from_this());
 
-  ++m_size;
-  connectFaceClosedSignal(*face, [this] { --m_size; });
+    ++m_size;
+    connectFaceClosedSignal(*face, [this] { --m_size; });
 
-  onFaceCreated(face);
+    onFaceCreated(face);
 
-  // prepare accepting the next connection
-  accept(onFaceCreated, onAcceptFailed);
+    // prepare accepting the next connection
+    accept(onFaceCreated, onAcceptFailed);
+  });
 }
 
 } // namespace nfd::face
diff --git a/daemon/face/unix-stream-channel.hpp b/daemon/face/unix-stream-channel.hpp
index 705d6f8..7c7f287 100644
--- a/daemon/face/unix-stream-channel.hpp
+++ b/daemon/face/unix-stream-channel.hpp
@@ -101,17 +101,11 @@
   accept(const FaceCreatedCallback& onFaceCreated,
          const FaceCreationFailedCallback& onAcceptFailed);
 
-  void
-  handleAccept(const boost::system::error_code& error,
-               const FaceCreatedCallback& onFaceCreated,
-               const FaceCreationFailedCallback& onAcceptFailed);
-
 private:
   const unix_stream::Endpoint m_endpoint;
+  const bool m_wantCongestionMarking;
   boost::asio::local::stream_protocol::acceptor m_acceptor;
-  boost::asio::local::stream_protocol::socket m_socket;
-  size_t m_size;
-  bool m_wantCongestionMarking;
+  size_t m_size = 0;
 };
 
 } // namespace nfd::face
diff --git a/daemon/face/websocket-channel.hpp b/daemon/face/websocket-channel.hpp
index d40bc70..a793a7c 100644
--- a/daemon/face/websocket-channel.hpp
+++ b/daemon/face/websocket-channel.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2022,  Regents of the University of California,
+ * Copyright (c) 2014-2023,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -36,17 +36,16 @@
 namespace nfd::face {
 
 /**
- * \brief Class implementing WebSocket-based channel to create faces
+ * \brief Class implementing a WebSocket-based channel to create faces.
  */
 class WebSocketChannel final : public Channel
 {
 public:
   /**
-   * \brief Create WebSocket channel for the local endpoint
+   * \brief Create a WebSocket channel for the given \p localEndpoint.
    *
-   * To enable creation of faces upon incoming connections,
-   * one needs to explicitly call WebSocketChannel::listen method.
-   * The created channel is bound to the localEndpoint.
+   * To enable the creation of faces upon incoming connections, one needs to
+   * explicitly call listen(). The created channel is bound to \p localEndpoint.
    */
   explicit
   WebSocketChannel(const websocket::Endpoint& localEndpoint);
@@ -65,7 +64,7 @@
 
   /**
    * \brief Enable listening on the local endpoint, accept connections,
-   *        and create faces when remote host makes a connection
+   *        and create faces when remote host makes a connection.
    *
    * \param onFaceCreated Callback to notify successful creation of a face
    */
@@ -73,12 +72,14 @@
   listen(const FaceCreatedCallback& onFaceCreated);
 
 NFD_PUBLIC_WITH_TESTS_ELSE_PRIVATE:
-  /** \pre listen hasn't been invoked
+  /**
+   * \pre listen() has not been invoked.
    */
   void
   setPingInterval(time::milliseconds interval);
 
-  /** \pre listen hasn't been invoked
+  /**
+   * \pre listen() has not been invoked.
    */
   void
   setPongTimeout(time::milliseconds timeout);