Aleth waits for 2 seconds after sending disconnect to peer before clo…

…sing socket

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.h

@@ -266,6 +266,11 @@ class Host: public Worker
 
     std::shared_ptr<CapabilityHostFace> capabilityHost() const { return m_capabilityHost; }
 
+    std::shared_ptr<ba::steady_timer> createTimer()
+    {
+        return std::make_shared<ba::steady_timer>(m_ioContext);
+    }
+
 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)
@@ -300,13 +293,32 @@ void Session::disconnect(DisconnectReason _reason)
 {
     clog(VerbosityTrace, "p2pcap") << "Disconnecting (our reason: " << reasonOf(_reason) << ") from " << m_logSuffix;
 
-    if (m_socket->ref().is_open())
+    if (!m_dropped)
     {
         RLPStream s;
         prep(s, DisconnectPacket, 1) << (int)_reason;
         sealAndSend(s);
+        auto disconnectTimer = m_server->createTimer();
+        auto self(shared_from_this());
+        disconnectTimer->expires_after(std::chrono::seconds(2));
+        disconnectTimer->async_wait([self, this, _reason](boost::system::error_code) {
+            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 (...)
+            {
+            }
+        });
     }
-    drop(_reason);
+    else
+        drop(_reason);
 }
 
 void Session::start()

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;