QModbusTcpServer: do not store client sockets in a separate list

The 'connections' list was used only for tracking who is connected.
We can just call
 QObject::findChildren<QTcpSocket *>
on the QTcpServer instance for that.

This also fixes the issue with removing data from the container while
iterating over it.

The old code was also removing the data from the container while
iterating over it, because calling socket->disconnectFromHost() from
a ranged-for loop results in sending a QTcpSocket::disconnected()
signal and immediately calling the connected lambda.
This patch fixes the issue.

Change-Id: I24d8c197545162af232d438d0941faba6ffc94d0
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
(cherry picked from commit a18c97f1a897e4653a47a45976d78bea5a2243be)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

2 files changed, 3 insertions, 6 deletions

diff --git a/src/serialbus/qmodbustcpserver.cpp b/src/serialbus/qmodbustcpserver.cpp
index 715c55c..ad7e2e5 100644
--- a/src/serialbus/qmodbustcpserver.cpp
+++ b/src/serialbus/qmodbustcpserver.cpp
@@ -98,7 +98,9 @@ void QModbusTcpServer::close()
     if (d->m_tcpServer->isListening())
         d->m_tcpServer->close();
 
-    for (auto socket : std::as_const(d->connections))
+    const auto childSockets =
+            d->m_tcpServer->findChildren<QTcpSocket *>(Qt::FindDirectChildrenOnly);
+    for (auto socket : childSockets)
         socket->disconnectFromHost();
 
     setState(QModbusDevice::UnconnectedState);
diff --git a/src/serialbus/qmodbustcpserver_p.h b/src/serialbus/qmodbustcpserver_p.h
index 0f1cbfe..f7c392f 100644
--- a/src/serialbus/qmodbustcpserver_p.h
+++ b/src/serialbus/qmodbustcpserver_p.h
@@ -99,8 +99,6 @@ public:
                 return;
             }
 
-            connections.append(socket);
-
             auto buffer = new QByteArray();
 
             QObject::connect(socket, &QObject::destroyed, socket, [buffer]() {
@@ -108,8 +106,6 @@ public:
                 delete buffer;
             });
             QObject::connect(socket, &QTcpSocket::disconnected, q, [socket, this]() {
-                connections.removeAll(socket);
-
                 Q_Q(QModbusTcpServer);
                 emit q->modbusClientDisconnected(socket);
                 socket->deleteLater();
@@ -193,7 +189,6 @@ public:
     }
 
     QTcpServer *m_tcpServer { nullptr };
-    QList<QTcpSocket *> connections;
 
     std::unique_ptr<QModbusTcpConnectionObserver> m_observer;