libshvbroker: Implement .app:ping

I'm getting sick of having SHV3 clients ping all the time, and it working even
though all the pings result in an error.

libshvbroker/CMakeLists.txt

@@ -2,6 +2,7 @@ qt_add_library(libshvbroker
 	src/aclmanager.cpp
 	src/aclmanagersqlite.cpp
 	src/appclioptions.cpp
+	src/appnode.cpp
 	src/brokeraclnode.cpp
 	src/brokerapp.cpp
 	src/brokerappnode.cpp

libshvbroker/src/appnode.cpp

@@ -0,0 +1,25 @@
+#include "appnode.h"
+
+#include <shv/broker/brokerapp.h>
+
+namespace shv::broker {
+AppNode::AppNode(shv::iotqt::node::ShvNode *parent)
+	: Super("", &m_metaMethods, parent)
+	, m_metaMethods {
+		shv::chainpack::methods::DIR,
+		shv::chainpack::methods::LS,
+		{shv::chainpack::Rpc::METH_PING, shv::chainpack::MetaMethod::Flag::None, "Null", "Null", shv::chainpack::AccessLevel::Browse, {}, "https://silicon-heaven.github.io/shv-doc/rpcmethods/app.html#appping"},
+	}
+{
+}
+
+shv::chainpack::RpcValue AppNode::callMethod(const StringViewList& shv_path, const std::string& method, const shv::chainpack::RpcValue& params, const chainpack::RpcValue& user_id)
+{
+	if (shv_path.empty()) {
+		if (method == shv::chainpack::Rpc::METH_PING) {
+			return chainpack::RpcValue(nullptr);
+		}
+	}
+	return Super::callMethod(shv_path, method, params, user_id);
+}
+}

libshvbroker/src/appnode.h

@@ -0,0 +1,20 @@
+#pragma once
+
+#include <shv/iotqt/node/shvnode.h>
+#include <shv/chainpack/rpcvalue.h>
+
+namespace shv::broker {
+
+class AppNode : public shv::iotqt::node::MethodsTableNode
+{
+	Q_OBJECT
+
+	using Super = shv::iotqt::node::MethodsTableNode;
+public:
+	AppNode(shv::iotqt::node::ShvNode *parent = nullptr);
+
+	shv::chainpack::RpcValue callMethod(const StringViewList &shv_path, const std::string &method, const shv::chainpack::RpcValue &params, const shv::chainpack::RpcValue &user_id) override;
+private:
+	std::vector<shv::chainpack::MetaMethod> m_metaMethods;
+};
+}

libshvbroker/src/brokerapp.cpp

@@ -1,4 +1,5 @@
 #include "aclmanagersqlite.h"
+#include "appnode.h"
 #include "brokeraclnode.h"
 #include "brokerappnode.h"
 #include "brokerrootnode.h"
@@ -295,6 +296,7 @@ BrokerApp::BrokerApp(int &argc, char **argv, AppCliOptions *cli_opts)
 	connect(m_nodesTree->root(), &shv::iotqt::node::ShvRootNode::sendRpcMessage, this, &BrokerApp::onRootNodeSendRpcMesage);
 	auto *bn = new BrokerAppNode();
 	m_nodesTree->mount(cp::Rpc::DIR_BROKER_APP, bn);
+	m_nodesTree->mount(cp::Rpc::DIR_APP, new AppNode());
 	m_nodesTree->mount(BROKER_CURRENT_CLIENT_SHV_PATH, new CurrentClientShvNode());
 	m_nodesTree->mount(std::string(cp::Rpc::DIR_BROKER) + "/clients", new ClientsNode());
 	m_nodesTree->mount(std::string(cp::Rpc::DIR_BROKER) + "/masters", new MasterBrokersNode());