Aleth waits for 2 seconds after sending disconnect packet

CHANGELOG.md

@@ -17,6 +17,7 @@
 - Added: [#5691](https://github.com/ethereum/aleth/pull/5691) Istanbul support: EIP-2028 Transaction data gas cost reduction.
 - Added: [#5696](https://github.com/ethereum/aleth/pull/5696) Istanbul support: EIP-1344 ChainID opcode.
 - Added: [#5701](https://github.com/ethereum/aleth/issues/5701) Outputs ENR text representation in admin.nodeInfo RPC.
+- Added: [#5707](https://github.com/ethereum/aleth/pull/5707) Aleth waits for 2 seconds after sending disconnect to peer before closing socket.
 - Changed: [#5532](https://github.com/ethereum/aleth/pull/5532) The leveldb is upgraded to 1.22. This is breaking change on Windows and the old databases are not compatible.
 - Changed: [#5559](https://github.com/ethereum/aleth/pull/5559) Update peer validation error messages.
 - Changed: [#5568](https://github.com/ethereum/aleth/pull/5568) Improve rlpx handshake log messages and create new rlpx log channel.

libp2p/Host.cpp

@@ -1200,3 +1200,11 @@ void Host::forEachPeer(
             return;
 }
 
+std::unique_ptr<ba::steady_timer> Host::createTimer(std::chrono::seconds const& _expiryDelay,
+    std::function<void(const boost::system::error_code& error)>&& _f)
+{
+    std::unique_ptr<ba::steady_timer> timer{new ba::steady_timer{m_ioContext}};
+    timer->expires_after(_expiryDelay);
+    timer->async_wait(_f);
+    return timer;
+}

libp2p/Host.h

@@ -266,6 +266,11 @@ class Host: public Worker
 
     std::shared_ptr<CapabilityHostFace> capabilityHost() const { return m_capabilityHost; }
 
+    /// Execute work on the network thread after an @a _expiryDelay delay.
+    /// Returned timer should be kept alive until delay is over.
+    std::unique_ptr<ba::steady_timer> createTimer(std::chrono::seconds const& _expiryDelay,
+        std::function<void(const boost::system::error_code& error)>&& _f);
+
 protected:
     /*
      * Used by the host to run a capability's background work loop

libp2p/Session.cpp

@@ -206,6 +206,9 @@ bool Session::checkPacket(bytesConstRef _msg)
 
 void Session::send(bytes&& _msg)
 {
+    if (m_dropped)
+        return;
+
     bytesConstRef msg(&_msg);
     LOG(m_netLoggerDetail) << capabilityPacketTypeToString(_msg[0]) << " to";
     if (!checkPacket(msg))
@@ -276,16 +279,6 @@ void Session::drop(DisconnectReason _reason)
 {
     if (m_dropped)
         return;
-    bi::tcp::socket& socket = m_socket->ref();
-    if (socket.is_open())
-        try
-        {
-            boost::system::error_code ec;
-            LOG(m_netLoggerDetail) << "Closing (" << reasonOf(_reason) << ") connection with";
-            socket.shutdown(boost::asio::ip::tcp::socket::shutdown_both, ec);
-            socket.close();
-        }
-        catch (...) {}
 
     m_peer->m_lastDisconnect = _reason;
     if (_reason == BadProtocol)
@@ -298,14 +291,22 @@ void Session::drop(DisconnectReason _reason)
 
 void Session::disconnect(DisconnectReason _reason)
 {
+    if (m_dropped)
+        return;
+
     clog(VerbosityTrace, "p2pcap") << "Disconnecting (our reason: " << reasonOf(_reason) << ") from " << m_logSuffix;
 
-    if (m_socket->ref().is_open())
-    {
-        RLPStream s;
-        prep(s, DisconnectPacket, 1) << (int)_reason;
-        sealAndSend(s);
-    }
+    RLPStream s;
+    prep(s, DisconnectPacket, 1) << (int)_reason;
+    sealAndSend(s);
+
+    auto self(shared_from_this());
+    // The empty handler will keep the Session alive for the supplied amount of time, after
+    // which Host will garbage-collect the Session which will invoke the Session dtor and close the
+    // socket
+    m_disconnectTimer =
+        m_server->createTimer(std::chrono::seconds(2), [self](boost::system::error_code) {});
+
     drop(_reason);
 }
 

libp2p/Session.h

@@ -84,7 +84,7 @@ class Session: public SessionFace, public std::enable_shared_from_this<SessionFa
 
     void ping() override;
 
-    bool isConnected() const override { return m_socket->ref().is_open(); }
+    bool isConnected() const override { return !m_dropped; }
 
     NodeID id() const override;
 
@@ -177,6 +177,8 @@ class Session: public SessionFace, public std::enable_shared_from_this<SessionFa
 
     std::set<std::string> m_disabledCapabilities;
 
+    std::unique_ptr<ba::steady_timer> m_disconnectTimer;
+
     std::string m_logSuffix;
 
     Logger m_netLogger{createLogger(VerbosityDebug, "net")};