Merge bitcoin-core/gui#35: Parse params directly instead of through node (partial revert #10244)

519cae8fd6e44aef3470415d7c5e12acb0acd9f4 gui: Delay interfaces::Node initialization (Russell Yanofsky)
102abff9eb6c267af64f2a3560712147d1896e13 gui: Replace interface::Node references with pointers (Russell Yanofsky)
91aced7c7e6e75c1f5896b7e3843015177f32748 gui: Remove unused interfaces::Node references (Russell Yanofsky)
e1336316250ab5cb0ed654b1e593378a6e0769ce gui: Partially revert #10244 gArgs and Params changes (Russell Yanofsky)

Pull request description:

  This PR is part of the [process separation project](https://github.com/bitcoin/bitcoin/projects/10).

  ---

  This is a partial revert of https://github.com/bitcoin/bitcoin/pull/10244. It changes gui code to go back to using gArgs and Params() functions directly instead of using interfaces::Node to handle arguments.

  These changes were originally pushed as part of https://github.com/bitcoin/bitcoin/pull/19461. Motivation is to support a new GUI process connecting to an already running node process. Details are explained in commit messages, but in addition to spawning a new bitcoin-node process, we want bitcoin-gui to connect to an existing bitcoin-node process. So for that reason it should be able to parse its own parameters, rather than rely on the node.

ACKs for top commit:
  MarcoFalke:
    re-ACK 519cae8fd6, only change is rebase and addressed nits of my previous review last week 🌄

Tree-SHA512: 9c339dd82ba78bcc7b887b84d872f35ccc7dfa3d271691e6eafe8a2048cbbe3bdde1e810ce33d0714d75d048c9de3470e9e9b6f8306a6047d1cb3548f6858dc8

18 files changed, 125 insertions, 142 deletions

diff --git a/src/interfaces/node.cpp b/src/interfaces/node.cpp
index e1c3a460e9..206262eb03 100644
--- a/src/interfaces/node.cpp
+++ b/src/interfaces/node.cpp
@@ -57,22 +57,8 @@ class NodeImpl : public Node
 {
 public:
     NodeImpl(NodeContext* context) { setContext(context); }
-    void initError(const bilingual_str& message) override { InitError(message); }
-    bool parseParameters(int argc, const char* const argv[], std::string& error) override
-    {
-        return gArgs.ParseParameters(argc, argv, error);
-    }
-    bool readConfigFiles(std::string& error) override { return gArgs.ReadConfigFiles(error, true); }
-    void forceSetArg(const std::string& arg, const std::string& value) override { gArgs.ForceSetArg(arg, value); }
-    bool softSetArg(const std::string& arg, const std::string& value) override { return gArgs.SoftSetArg(arg, value); }
-    bool softSetBoolArg(const std::string& arg, bool value) override { return gArgs.SoftSetBoolArg(arg, value); }
-    void selectParams(const std::string& network) override { SelectParams(network); }
-    bool initSettings(std::string& error) override { return gArgs.InitSettings(error); }
-    uint64_t getAssumedBlockchainSize() override { return Params().AssumedBlockchainSize(); }
-    uint64_t getAssumedChainStateSize() override { return Params().AssumedChainStateSize(); }
-    std::string getNetwork() override { return Params().NetworkIDString(); }
-    void initLogging() override { InitLogging(gArgs); }
-    void initParameterInteraction() override { InitParameterInteraction(gArgs); }
+    void initLogging() override { InitLogging(*Assert(m_context->args)); }
+    void initParameterInteraction() override { InitParameterInteraction(*Assert(m_context->args)); }
     bilingual_str getWarnings() override { return GetWarnings(true); }
     uint32_t getLogCategories() override { return LogInstance().GetCategoryMask(); }
     bool baseInitialize() override
@@ -109,7 +95,6 @@ public:
             StopMapPort();
         }
     }
-    void setupServerArgs() override { return SetupServerArgs(*m_context); }
     bool getProxy(Network net, proxyType& proxy_info) override { return GetProxy(net, proxy_info); }
     size_t getNodeCount(CConnman::NumConnections flags) override
     {
diff --git a/src/interfaces/node.h b/src/interfaces/node.h
index 753f3e6b13..0cff7ae3a1 100644
--- a/src/interfaces/node.h
+++ b/src/interfaces/node.h
@@ -55,41 +55,6 @@ class Node
 public:
     virtual ~Node() {}
 
-    //! Send init error.
-    virtual void initError(const bilingual_str& message) = 0;
-
-    //! Set command line arguments.
-    virtual bool parseParameters(int argc, const char* const argv[], std::string& error) = 0;
-
-    //! Set a command line argument
-    virtual void forceSetArg(const std::string& arg, const std::string& value) = 0;
-
-    //! Set a command line argument if it doesn't already have a value
-    virtual bool softSetArg(const std::string& arg, const std::string& value) = 0;
-
-    //! Set a command line boolean argument if it doesn't already have a value
-    virtual bool softSetBoolArg(const std::string& arg, bool value) = 0;
-
-    //! Load settings from configuration file.
-    virtual bool readConfigFiles(std::string& error) = 0;
-
-    //! Choose network parameters.
-    virtual void selectParams(const std::string& network) = 0;
-
-    //! Read and update <datadir>/settings.json file with saved settings. This
-    //! needs to be called after selectParams() because the settings file
-    //! location is network-specific.
-    virtual bool initSettings(std::string& error) = 0;
-
-    //! Get the (assumed) blockchain size.
-    virtual uint64_t getAssumedBlockchainSize() = 0;
-
-    //! Get the (assumed) chain state size.
-    virtual uint64_t getAssumedChainStateSize() = 0;
-
-    //! Get network name.
-    virtual std::string getNetwork() = 0;
-
     //! Init logging.
     virtual void initLogging() = 0;
 
@@ -117,9 +82,6 @@ public:
     //! Return whether shutdown was requested.
     virtual bool shutdownRequested() = 0;
 
-    //! Setup arguments
-    virtual void setupServerArgs() = 0;
-
     //! Map port.
     virtual void mapPort(bool use_upnp) = 0;
 
diff --git a/src/qt/bitcoin.cpp b/src/qt/bitcoin.cpp
index f53fcc41f3..e63ffdfb36 100644
--- a/src/qt/bitcoin.cpp
+++ b/src/qt/bitcoin.cpp
@@ -27,9 +27,11 @@
 #include <qt/walletmodel.h>
 #endif // ENABLE_WALLET
 
+#include <init.h>
 #include <interfaces/handler.h>
 #include <interfaces/node.h>
 #include <node/context.h>
+#include <node/ui_interface.h>
 #include <noui.h>
 #include <uint256.h>
 #include <util/system.h>
@@ -37,6 +39,7 @@
 #include <util/translation.h>
 #include <validation.h>
 
+#include <boost/signals2/connection.hpp>
 #include <memory>
 
 #include <QApplication>
@@ -193,10 +196,9 @@ void BitcoinCore::shutdown()
 static int qt_argc = 1;
 static const char* qt_argv = "bitcoin-qt";
 
-BitcoinApplication::BitcoinApplication(interfaces::Node& node):
+BitcoinApplication::BitcoinApplication():
     QApplication(qt_argc, const_cast<char **>(&qt_argv)),
     coreThread(nullptr),
-    m_node(node),
     optionsModel(nullptr),
     clientModel(nullptr),
     window(nullptr),
@@ -246,12 +248,12 @@ void BitcoinApplication::createPaymentServer()
 
 void BitcoinApplication::createOptionsModel(bool resetSettings)
 {
-    optionsModel = new OptionsModel(m_node, this, resetSettings);
+    optionsModel = new OptionsModel(this, resetSettings);
 }
 
 void BitcoinApplication::createWindow(const NetworkStyle *networkStyle)
 {
-    window = new BitcoinGUI(m_node, platformStyle, networkStyle, nullptr);
+    window = new BitcoinGUI(node(), platformStyle, networkStyle, nullptr);
 
     pollShutdownTimer = new QTimer(window);
     connect(pollShutdownTimer, &QTimer::timeout, window, &BitcoinGUI::detectShutdown);
@@ -259,17 +261,26 @@ void BitcoinApplication::createWindow(const NetworkStyle *networkStyle)
 
 void BitcoinApplication::createSplashScreen(const NetworkStyle *networkStyle)
 {
-    SplashScreen *splash = new SplashScreen(m_node, nullptr, networkStyle);
+    assert(!m_splash);
+    m_splash = new SplashScreen(nullptr, networkStyle);
     // We don't hold a direct pointer to the splash screen after creation, but the splash
     // screen will take care of deleting itself when finish() happens.
-    splash->show();
-    connect(this, &BitcoinApplication::splashFinished, splash, &SplashScreen::finish);
-    connect(this, &BitcoinApplication::requestedShutdown, splash, &QWidget::close);
+    m_splash->show();
+    connect(this, &BitcoinApplication::splashFinished, m_splash, &SplashScreen::finish);
+    connect(this, &BitcoinApplication::requestedShutdown, m_splash, &QWidget::close);
+}
+
+void BitcoinApplication::setNode(interfaces::Node& node)
+{
+    assert(!m_node);
+    m_node = &node;
+    if (optionsModel) optionsModel->setNode(*m_node);
+    if (m_splash) m_splash->setNode(*m_node);
 }
 
 bool BitcoinApplication::baseInitialize()
 {
-    return m_node.baseInitialize();
+    return node().baseInitialize();
 }
 
 void BitcoinApplication::startThread()
@@ -277,7 +288,7 @@ void BitcoinApplication::startThread()
     if(coreThread)
         return;
     coreThread = new QThread(this);
-    BitcoinCore *executor = new BitcoinCore(m_node);
+    BitcoinCore *executor = new BitcoinCore(node());
     executor->moveToThread(coreThread);
 
     /*  communication to and from thread */
@@ -298,8 +309,8 @@ void BitcoinApplication::parameterSetup()
     // print to the console unnecessarily.
     gArgs.SoftSetBoolArg("-printtoconsole", false);
 
-    m_node.initLogging();
-    m_node.initParameterInteraction();
+    InitLogging(gArgs);
+    InitParameterInteraction(gArgs);
 }
 
 void BitcoinApplication::InitializePruneSetting(bool prune)
@@ -331,7 +342,7 @@ void BitcoinApplication::requestShutdown()
     window->unsubscribeFromCoreSignals();
     // Request node shutdown, which can interrupt long operations, like
     // rescanning a wallet.
-    m_node.startShutdown();
+    node().startShutdown();
     // Unsetting the client model can cause the current thread to wait for node
     // to complete an operation, like wait for a RPC execution to complete.
     window->setClientModel(nullptr);
@@ -353,7 +364,7 @@ void BitcoinApplication::initializeResult(bool success, interfaces::BlockAndHead
     {
         // Log this only after AppInitMain finishes, as then logging setup is guaranteed complete
         qInfo() << "Platform customization:" << platformStyle->getName();
-        clientModel = new ClientModel(m_node, optionsModel);
+        clientModel = new ClientModel(node(), optionsModel);
         window->setClientModel(clientModel, &tip_info);
 #ifdef ENABLE_WALLET
         if (WalletModel::isWalletEnabled()) {
@@ -437,9 +448,9 @@ int GuiMain(int argc, char* argv[])
     std::unique_ptr<interfaces::Node> node = interfaces::MakeNode(&node_context);
 
     // Subscribe to global signals from core
-    std::unique_ptr<interfaces::Handler> handler_message_box = node->handleMessageBox(noui_ThreadSafeMessageBox);
-    std::unique_ptr<interfaces::Handler> handler_question = node->handleQuestion(noui_ThreadSafeQuestion);
-    std::unique_ptr<interfaces::Handler> handler_init_message = node->handleInitMessage(noui_InitMessage);
+    boost::signals2::scoped_connection handler_message_box = ::uiInterface.ThreadSafeMessageBox_connect(noui_ThreadSafeMessageBox);
+    boost::signals2::scoped_connection handler_question = ::uiInterface.ThreadSafeQuestion_connect(noui_ThreadSafeQuestion);
+    boost::signals2::scoped_connection handler_init_message = ::uiInterface.InitMessage_connect(noui_InitMessage);
 
     // Do not refer to data directory yet, this can be overridden by Intro::pickDataDirectory
 
@@ -453,15 +464,15 @@ int GuiMain(int argc, char* argv[])
     QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
 #endif
 
-    BitcoinApplication app(*node);
+    BitcoinApplication app;
 
     /// 2. Parse command-line options. We do this after qt in order to show an error if there are problems parsing these
     // Command-line options take precedence:
-    node->setupServerArgs();
+    SetupServerArgs(node_context);
     SetupUIArgs(gArgs);
     std::string error;
-    if (!node->parseParameters(argc, argv, error)) {
-        node->initError(strprintf(Untranslated("Error parsing command line arguments: %s\n"), error));
+    if (!gArgs.ParseParameters(argc, argv, error)) {
+        InitError(strprintf(Untranslated("Error parsing command line arguments: %s\n"), error));
         // Create a message box, because the gui has neither been created nor has subscribed to core signals
         QMessageBox::critical(nullptr, PACKAGE_NAME,
             // message can not be translated because translations have not been initialized
@@ -487,7 +498,7 @@ int GuiMain(int argc, char* argv[])
     // Show help message immediately after parsing command-line options (for "-lang") and setting locale,
     // but before showing splash screen.
     if (HelpRequested(gArgs) || gArgs.IsArgSet("-version")) {
-        HelpMessageDialog help(*node, nullptr, gArgs.IsArgSet("-version"));
+        HelpMessageDialog help(nullptr, gArgs.IsArgSet("-version"));
         help.showOrPrint();
         return EXIT_SUCCESS;
     }
@@ -497,18 +508,18 @@ int GuiMain(int argc, char* argv[])
     bool did_show_intro = false;
     bool prune = false; // Intro dialog prune check box
     // Gracefully exit if the user cancels
-    if (!Intro::showIfNeeded(*node, did_show_intro, prune)) return EXIT_SUCCESS;
+    if (!Intro::showIfNeeded(did_show_intro, prune)) return EXIT_SUCCESS;
 
     /// 6. Determine availability of data directory and parse bitcoin.conf
     /// - Do not call GetDataDir(true) before this step finishes
     if (!CheckDataDirOption()) {
-        node->initError(strprintf(Untranslated("Specified data directory \"%s\" does not exist.\n"), gArgs.GetArg("-datadir", "")));
+        InitError(strprintf(Untranslated("Specified data directory \"%s\" does not exist.\n"), gArgs.GetArg("-datadir", "")));
         QMessageBox::critical(nullptr, PACKAGE_NAME,
             QObject::tr("Error: Specified data directory \"%1\" does not exist.").arg(QString::fromStdString(gArgs.GetArg("-datadir", ""))));
         return EXIT_FAILURE;
     }
-    if (!node->readConfigFiles(error)) {
-        node->initError(strprintf(Untranslated("Error reading configuration file: %s\n"), error));
+    if (!gArgs.ReadConfigFiles(error, true)) {
+        InitError(strprintf(Untranslated("Error reading configuration file: %s\n"), error));
         QMessageBox::critical(nullptr, PACKAGE_NAME,
             QObject::tr("Error: Cannot parse configuration file: %1.").arg(QString::fromStdString(error)));
         return EXIT_FAILURE;
@@ -522,18 +533,18 @@ int GuiMain(int argc, char* argv[])
 
     // Check for -chain, -testnet or -regtest parameter (Params() calls are only valid after this clause)
     try {
-        node->selectParams(gArgs.GetChainName());
+        SelectParams(gArgs.GetChainName());
     } catch(std::exception &e) {
-        node->initError(Untranslated(strprintf("%s\n", e.what())));
+        InitError(Untranslated(strprintf("%s\n", e.what())));
         QMessageBox::critical(nullptr, PACKAGE_NAME, QObject::tr("Error: %1").arg(e.what()));
         return EXIT_FAILURE;
     }
 #ifdef ENABLE_WALLET
     // Parse URIs on command line -- this can affect Params()
-    PaymentServer::ipcParseCommandLine(*node, argc, argv);
+    PaymentServer::ipcParseCommandLine(argc, argv);
 #endif
-    if (!node->initSettings(error)) {
-        node->initError(Untranslated(error));
+    if (!gArgs.InitSettings(error)) {
+        InitError(Untranslated(error));
         QMessageBox::critical(nullptr, PACKAGE_NAME, QObject::tr("Error initializing settings: %1").arg(QString::fromStdString(error)));
         return EXIT_FAILURE;
     }
@@ -587,6 +598,8 @@ int GuiMain(int argc, char* argv[])
     if (gArgs.GetBoolArg("-splash", DEFAULT_SPLASHSCREEN) && !gArgs.GetBoolArg("-min", false))
         app.createSplashScreen(networkStyle.data());
 
+    app.setNode(*node);
+
     int rv = EXIT_SUCCESS;
     try
     {
@@ -609,10 +622,10 @@ int GuiMain(int argc, char* argv[])
         }
     } catch (const std::exception& e) {
         PrintExceptionContinue(&e, "Runaway exception");
-        app.handleRunawayException(QString::fromStdString(node->getWarnings().translated));
+        app.handleRunawayException(QString::fromStdString(app.node().getWarnings().translated));
     } catch (...) {
         PrintExceptionContinue(nullptr, "Runaway exception");
-        app.handleRunawayException(QString::fromStdString(node->getWarnings().translated));
+        app.handleRunawayException(QString::fromStdString(app.node().getWarnings().translated));
     }
     return rv;
 }
diff --git a/src/qt/bitcoin.h b/src/qt/bitcoin.h
index 20c6dfc047..69e0a5921e 100644
--- a/src/qt/bitcoin.h
+++ b/src/qt/bitcoin.h
@@ -10,6 +10,7 @@
 #endif
 
 #include <QApplication>
+#include <assert.h>
 #include <memory>
 
 #include <interfaces/node.h>
@@ -20,6 +21,7 @@ class NetworkStyle;
 class OptionsModel;
 class PaymentServer;
 class PlatformStyle;
+class SplashScreen;
 class WalletController;
 class WalletModel;
 
@@ -54,7 +56,7 @@ class BitcoinApplication: public QApplication
 {
     Q_OBJECT
 public:
-    explicit BitcoinApplication(interfaces::Node& node);
+    explicit BitcoinApplication();
     ~BitcoinApplication();
 
 #ifdef ENABLE_WALLET
@@ -88,6 +90,9 @@ public:
     /// Setup platform style
     void setupPlatformStyle();
 
+    interfaces::Node& node() const { assert(m_node); return *m_node; }
+    void setNode(interfaces::Node& node);
+
 public Q_SLOTS:
     void initializeResult(bool success, interfaces::BlockAndHeaderTipInfo tip_info);
     void shutdownResult();
@@ -102,7 +107,6 @@ Q_SIGNALS:
 
 private:
     QThread *coreThread;
-    interfaces::Node& m_node;
     OptionsModel *optionsModel;
     ClientModel *clientModel;
     BitcoinGUI *window;
@@ -114,6 +118,8 @@ private:
     int returnValue;
     const PlatformStyle *platformStyle;
     std::unique_ptr<QWidget> shutdownWindow;
+    SplashScreen* m_splash = nullptr;
+    interfaces::Node* m_node = nullptr;
 
     void startThread();
 };
diff --git a/src/qt/bitcoingui.cpp b/src/qt/bitcoingui.cpp
index 56adbf249a..8935ff19bf 100644
--- a/src/qt/bitcoingui.cpp
+++ b/src/qt/bitcoingui.cpp
@@ -95,7 +95,7 @@ BitcoinGUI::BitcoinGUI(interfaces::Node& node, const PlatformStyle *_platformSty
     updateWindowTitle();
 
     rpcConsole = new RPCConsole(node, _platformStyle, nullptr);
-    helpMessageDialog = new HelpMessageDialog(node, this, false);
+    helpMessageDialog = new HelpMessageDialog(this, false);
 #ifdef ENABLE_WALLET
     if(enableWallet)
     {
@@ -821,7 +821,7 @@ void BitcoinGUI::aboutClicked()
     if(!clientModel)
         return;
 
-    HelpMessageDialog dlg(m_node, this, true);
+    HelpMessageDialog dlg(this, true);
     dlg.exec();
 }
 
diff --git a/src/qt/intro.cpp b/src/qt/intro.cpp
index ad21dfc3ef..235722d091 100644
--- a/src/qt/intro.cpp
+++ b/src/qt/intro.cpp
@@ -6,6 +6,7 @@
 #include <config/bitcoin-config.h>
 #endif
 
+#include <chainparams.h>
 #include <fs.h>
 #include <qt/intro.h>
 #include <qt/forms/ui_intro.h>
@@ -181,7 +182,7 @@ void Intro::setDataDirectory(const QString &dataDir)
     }
 }
 
-bool Intro::showIfNeeded(interfaces::Node& node, bool& did_show_intro, bool& prune)
+bool Intro::showIfNeeded(bool& did_show_intro, bool& prune)
 {
     did_show_intro = false;
 
@@ -199,13 +200,13 @@ bool Intro::showIfNeeded(interfaces::Node& node, bool& did_show_intro, bool& pru
     {
         /* Use selectParams here to guarantee Params() can be used by node interface */
         try {
-            node.selectParams(gArgs.GetChainName());
+            SelectParams(gArgs.GetChainName());
         } catch (const std::exception&) {
             return false;
         }
 
         /* If current default data directory does not exist, let the user choose one */
-        Intro intro(0, node.getAssumedBlockchainSize(), node.getAssumedChainStateSize());
+        Intro intro(0, Params().AssumedBlockchainSize(), Params().AssumedChainStateSize());
         intro.setDataDirectory(dataDir);
         intro.setWindowIcon(QIcon(":icons/bitcoin"));
         did_show_intro = true;
@@ -242,7 +243,7 @@ bool Intro::showIfNeeded(interfaces::Node& node, bool& did_show_intro, bool& pru
      * (to be consistent with bitcoind behavior)
      */
     if(dataDir != GUIUtil::getDefaultDataDirectory()) {
-        node.softSetArg("-datadir", GUIUtil::qstringToBoostPath(dataDir).string()); // use OS locale for path setting
+        gArgs.SoftSetArg("-datadir", GUIUtil::qstringToBoostPath(dataDir).string()); // use OS locale for path setting
     }
     return true;
 }
diff --git a/src/qt/intro.h b/src/qt/intro.h
index 732393246e..51f42de7ac 100644
--- a/src/qt/intro.h
+++ b/src/qt/intro.h
@@ -47,7 +47,7 @@ public:
      * @note do NOT call global GetDataDir() before calling this function, this
      * will cause the wrong path to be cached.
      */
-    static bool showIfNeeded(interfaces::Node& node, bool& did_show_intro, bool& prune);
+    static bool showIfNeeded(bool& did_show_intro, bool& prune);
 
 Q_SIGNALS:
     void requestCheck();
diff --git a/src/qt/optionsmodel.cpp b/src/qt/optionsmodel.cpp
index 58a7591c95..7e089b4f95 100644
--- a/src/qt/optionsmodel.cpp
+++ b/src/qt/optionsmodel.cpp
@@ -27,8 +27,8 @@ const char *DEFAULT_GUI_PROXY_HOST = "127.0.0.1";
 
 static const QString GetDefaultProxyAddress();
 
-OptionsModel::OptionsModel(interfaces::Node& node, QObject *parent, bool resetSettings) :
-    QAbstractListModel(parent), m_node(node)
+OptionsModel::OptionsModel(QObject *parent, bool resetSettings) :
+    QAbstractListModel(parent)
 {
     Init(resetSettings);
 }
@@ -97,12 +97,12 @@ void OptionsModel::Init(bool resetSettings)
 
     if (!settings.contains("nDatabaseCache"))
         settings.setValue("nDatabaseCache", (qint64)nDefaultDbCache);
-    if (!m_node.softSetArg("-dbcache", settings.value("nDatabaseCache").toString().toStdString()))
+    if (!gArgs.SoftSetArg("-dbcache", settings.value("nDatabaseCache").toString().toStdString()))
         addOverriddenOption("-dbcache");
 
     if (!settings.contains("nThreadsScriptVerif"))
         settings.setValue("nThreadsScriptVerif", DEFAULT_SCRIPTCHECK_THREADS);
-    if (!m_node.softSetArg("-par", settings.value("nThreadsScriptVerif").toString().toStdString()))
+    if (!gArgs.SoftSetArg("-par", settings.value("nThreadsScriptVerif").toString().toStdString()))
         addOverriddenOption("-par");
 
     if (!settings.contains("strDataDir"))
@@ -112,19 +112,19 @@ void OptionsModel::Init(bool resetSettings)
 #ifdef ENABLE_WALLET
     if (!settings.contains("bSpendZeroConfChange"))
         settings.setValue("bSpendZeroConfChange", true);
-    if (!m_node.softSetBoolArg("-spendzeroconfchange", settings.value("bSpendZeroConfChange").toBool()))
+    if (!gArgs.SoftSetBoolArg("-spendzeroconfchange", settings.value("bSpendZeroConfChange").toBool()))
         addOverriddenOption("-spendzeroconfchange");
 #endif
 
     // Network
     if (!settings.contains("fUseUPnP"))
         settings.setValue("fUseUPnP", DEFAULT_UPNP);
-    if (!m_node.softSetBoolArg("-upnp", settings.value("fUseUPnP").toBool()))
+    if (!gArgs.SoftSetBoolArg("-upnp", settings.value("fUseUPnP").toBool()))
         addOverriddenOption("-upnp");
 
     if (!settings.contains("fListen"))
         settings.setValue("fListen", DEFAULT_LISTEN);
-    if (!m_node.softSetBoolArg("-listen", settings.value("fListen").toBool()))
+    if (!gArgs.SoftSetBoolArg("-listen", settings.value("fListen").toBool()))
         addOverriddenOption("-listen");
 
     if (!settings.contains("fUseProxy"))
@@ -132,7 +132,7 @@ void OptionsModel::Init(bool resetSettings)
     if (!settings.contains("addrProxy"))
         settings.setValue("addrProxy", GetDefaultProxyAddress());
     // Only try to set -proxy, if user has enabled fUseProxy
-    if (settings.value("fUseProxy").toBool() && !m_node.softSetArg("-proxy", settings.value("addrProxy").toString().toStdString()))
+    if ((settings.value("fUseProxy").toBool() && !gArgs.SoftSetArg("-proxy", settings.value("addrProxy").toString().toStdString())))
         addOverriddenOption("-proxy");
     else if(!settings.value("fUseProxy").toBool() && !gArgs.GetArg("-proxy", "").empty())
         addOverriddenOption("-proxy");
@@ -142,7 +142,7 @@ void OptionsModel::Init(bool resetSettings)
     if (!settings.contains("addrSeparateProxyTor"))
         settings.setValue("addrSeparateProxyTor", GetDefaultProxyAddress());
     // Only try to set -onion, if user has enabled fUseSeparateProxyTor
-    if (settings.value("fUseSeparateProxyTor").toBool() && !m_node.softSetArg("-onion", settings.value("addrSeparateProxyTor").toString().toStdString()))
+    if ((settings.value("fUseSeparateProxyTor").toBool() && !gArgs.SoftSetArg("-onion", settings.value("addrSeparateProxyTor").toString().toStdString())))
         addOverriddenOption("-onion");
     else if(!settings.value("fUseSeparateProxyTor").toBool() && !gArgs.GetArg("-onion", "").empty())
         addOverriddenOption("-onion");
@@ -150,7 +150,7 @@ void OptionsModel::Init(bool resetSettings)
     // Display
     if (!settings.contains("language"))
         settings.setValue("language", "");
-    if (!m_node.softSetArg("-lang", settings.value("language").toString().toStdString()))
+    if (!gArgs.SoftSetArg("-lang", settings.value("language").toString().toStdString()))
         addOverriddenOption("-lang");
 
     language = settings.value("language").toString();
@@ -244,10 +244,10 @@ void OptionsModel::SetPruneEnabled(bool prune, bool force)
     const int64_t prune_target_mib = PruneGBtoMiB(settings.value("nPruneSize").toInt());
     std::string prune_val = prune ? ToString(prune_target_mib) : "0";
     if (force) {
-        m_node.forceSetArg("-prune", prune_val);
+        gArgs.ForceSetArg("-prune", prune_val);
         return;
     }
-    if (!m_node.softSetArg("-prune", prune_val)) {
+    if (!gArgs.SoftSetArg("-prune", prune_val)) {
         addOverriddenOption("-prune");
     }
 }
@@ -353,7 +353,7 @@ bool OptionsModel::setData(const QModelIndex & index, const QVariant & value, in
             break;
         case MapPortUPnP: // core option - can be changed on-the-fly
             settings.setValue("fUseUPnP", value.toBool());
-            m_node.mapPort(value.toBool());
+            node().mapPort(value.toBool());
             break;
         case MinimizeOnClose:
             fMinimizeOnClose = value.toBool();
diff --git a/src/qt/optionsmodel.h b/src/qt/optionsmodel.h
index 14fdf9046e..3d9e7bbb80 100644
--- a/src/qt/optionsmodel.h
+++ b/src/qt/optionsmodel.h
@@ -11,6 +11,8 @@
 
 #include <QAbstractListModel>
 
+#include <assert.h>
+
 namespace interfaces {
 class Node;
 }
@@ -39,7 +41,7 @@ class OptionsModel : public QAbstractListModel
     Q_OBJECT
 
 public:
-    explicit OptionsModel(interfaces::Node& node, QObject *parent = nullptr, bool resetSettings = false);
+    explicit OptionsModel(QObject *parent = nullptr, bool resetSettings = false);
 
     enum OptionID {
         StartAtStartup,         // bool
@@ -92,10 +94,11 @@ public:
     void setRestartRequired(bool fRequired);
     bool isRestartRequired() const;
 
-    interfaces::Node& node() const { return m_node; }
+    interfaces::Node& node() const { assert(m_node); return *m_node; }
+    void setNode(interfaces::Node& node) { assert(!m_node); m_node = &node; }
 
 private:
-    interfaces::Node& m_node;
+    interfaces::Node* m_node = nullptr;
     /* Qt-only settings */
     bool fHideTrayIcon;
     bool fMinimizeToTray;
diff --git a/src/qt/paymentserver.cpp b/src/qt/paymentserver.cpp
index a1da85bda7..8679ced685 100644
--- a/src/qt/paymentserver.cpp
+++ b/src/qt/paymentserver.cpp
@@ -74,7 +74,7 @@ static QSet<QString> savedPaymentRequests;
 // Warning: ipcSendCommandLine() is called early in init,
 // so don't use "Q_EMIT message()", but "QMessageBox::"!
 //
-void PaymentServer::ipcParseCommandLine(interfaces::Node& node, int argc, char* argv[])
+void PaymentServer::ipcParseCommandLine(int argc, char* argv[])
 {
     for (int i = 1; i < argc; i++)
     {
@@ -97,11 +97,11 @@ void PaymentServer::ipcParseCommandLine(interfaces::Node& node, int argc, char*
                 auto tempChainParams = CreateChainParams(CBaseChainParams::MAIN);
 
                 if (IsValidDestinationString(r.address.toStdString(), *tempChainParams)) {
-                    node.selectParams(CBaseChainParams::MAIN);
+                    SelectParams(CBaseChainParams::MAIN);
                 } else {
                     tempChainParams = CreateChainParams(CBaseChainParams::TESTNET);
                     if (IsValidDestinationString(r.address.toStdString(), *tempChainParams)) {
-                        node.selectParams(CBaseChainParams::TESTNET);
+                        SelectParams(CBaseChainParams::TESTNET);
                     }
                 }
             }
diff --git a/src/qt/paymentserver.h b/src/qt/paymentserver.h
index 154f4a7ea6..eaf2bafe59 100644
--- a/src/qt/paymentserver.h
+++ b/src/qt/paymentserver.h
@@ -61,7 +61,7 @@ class PaymentServer : public QObject
 public:
     // Parse URIs on command line
     // Returns false on error
-    static void ipcParseCommandLine(interfaces::Node& node, int argc, char *argv[]);
+    static void ipcParseCommandLine(int argc, char *argv[]);
 
     // Returns true if there were URIs on the command line
     // which were successfully sent to an already-running
diff --git a/src/qt/splashscreen.cpp b/src/qt/splashscreen.cpp
index 6e6b2b8466..bd63d6e7fb 100644
--- a/src/qt/splashscreen.cpp
+++ b/src/qt/splashscreen.cpp
@@ -24,8 +24,8 @@
 #include <QScreen>
 
 
-SplashScreen::SplashScreen(interfaces::Node& node, Qt::WindowFlags f, const NetworkStyle *networkStyle) :
-    QWidget(nullptr, f), curAlignment(0), m_node(node)
+SplashScreen::SplashScreen(Qt::WindowFlags f, const NetworkStyle *networkStyle) :
+    QWidget(nullptr, f), curAlignment(0)
 {
     // set reference point, paddings
     int paddingRight            = 50;
@@ -124,7 +124,6 @@ SplashScreen::SplashScreen(interfaces::Node& node, Qt::WindowFlags f, const Netw
     setFixedSize(r.size());
     move(QGuiApplication::primaryScreen()->geometry().center() - r.center());
 
-    subscribeToCoreSignals();
     installEventFilter(this);
 
     GUIUtil::handleCloseWindowShortcut(this);
@@ -132,14 +131,28 @@ SplashScreen::SplashScreen(interfaces::Node& node, Qt::WindowFlags f, const Netw
 
 SplashScreen::~SplashScreen()
 {
-    unsubscribeFromCoreSignals();
+    if (m_node) unsubscribeFromCoreSignals();
+}
+
+void SplashScreen::setNode(interfaces::Node& node)
+{
+    assert(!m_node);
+    m_node = &node;
+    subscribeToCoreSignals();
+    if (m_shutdown) m_node->startShutdown();
+}
+
+void SplashScreen::shutdown()
+{
+    m_shutdown = true;
+    if (m_node) m_node->startShutdown();
 }
 
 bool SplashScreen::eventFilter(QObject * obj, QEvent * ev) {
     if (ev->type() == QEvent::KeyPress) {
         QKeyEvent *keyEvent = static_cast<QKeyEvent *>(ev);
         if (keyEvent->key() == Qt::Key_Q) {
-            m_node.startShutdown();
+            shutdown();
         }
     }
     return QObject::eventFilter(obj, ev);
@@ -183,10 +196,10 @@ void SplashScreen::ConnectWallet(std::unique_ptr<interfaces::Wallet> wallet)
 void SplashScreen::subscribeToCoreSignals()
 {
     // Connect signals to client
-    m_handler_init_message = m_node.handleInitMessage(std::bind(InitMessage, this, std::placeholders::_1));
-    m_handler_show_progress = m_node.handleShowProgress(std::bind(ShowProgress, this, std::placeholders::_1, std::placeholders::_2, std::placeholders::_3));
+    m_handler_init_message = m_node->handleInitMessage(std::bind(InitMessage, this, std::placeholders::_1));
+    m_handler_show_progress = m_node->handleShowProgress(std::bind(ShowProgress, this, std::placeholders::_1, std::placeholders::_2, std::placeholders::_3));
 #ifdef ENABLE_WALLET
-    m_handler_load_wallet = m_node.handleLoadWallet([this](std::unique_ptr<interfaces::Wallet> wallet) { ConnectWallet(std::move(wallet)); });
+    m_handler_load_wallet = m_node->handleLoadWallet([this](std::unique_ptr<interfaces::Wallet> wallet) { ConnectWallet(std::move(wallet)); });
 #endif
 }
 
@@ -221,6 +234,6 @@ void SplashScreen::paintEvent(QPaintEvent *event)
 
 void SplashScreen::closeEvent(QCloseEvent *event)
 {
-    m_node.startShutdown(); // allows an "emergency" shutdown during startup
+    shutdown(); // allows an "emergency" shutdown during startup
     event->ignore();
 }
diff --git a/src/qt/splashscreen.h b/src/qt/splashscreen.h
index 3158524117..2213b02c55 100644
--- a/src/qt/splashscreen.h
+++ b/src/qt/splashscreen.h
@@ -28,8 +28,9 @@ class SplashScreen : public QWidget
     Q_OBJECT
 
 public:
-    explicit SplashScreen(interfaces::Node& node, Qt::WindowFlags f, const NetworkStyle *networkStyle);
+    explicit SplashScreen(Qt::WindowFlags f, const NetworkStyle *networkStyle);
     ~SplashScreen();
+    void setNode(interfaces::Node& node);
 
 protected:
     void paintEvent(QPaintEvent *event) override;
@@ -50,6 +51,8 @@ private:
     void subscribeToCoreSignals();
     /** Disconnect core signals to splash screen */
     void unsubscribeFromCoreSignals();
+    /** Initiate shutdown */
+    void shutdown();
     /** Connect wallet signals to splash screen */
     void ConnectWallet(std::unique_ptr<interfaces::Wallet> wallet);
 
@@ -58,7 +61,8 @@ private:
     QColor curColor;
     int curAlignment;
 
-    interfaces::Node& m_node;
+    interfaces::Node* m_node = nullptr;
+    bool m_shutdown = false;
     std::unique_ptr<interfaces::Handler> m_handler_init_message;
     std::unique_ptr<interfaces::Handler> m_handler_show_progress;
     std::unique_ptr<interfaces::Handler> m_handler_load_wallet;
diff --git a/src/qt/test/addressbooktests.cpp b/src/qt/test/addressbooktests.cpp
index 035c8196bc..84f981dff3 100644
--- a/src/qt/test/addressbooktests.cpp
+++ b/src/qt/test/addressbooktests.cpp
@@ -108,7 +108,7 @@ void TestAddAddressesToSendBook(interfaces::Node& node)
 
     // Initialize relevant QT models.
     std::unique_ptr<const PlatformStyle> platformStyle(PlatformStyle::instantiate("other"));
-    OptionsModel optionsModel(node);
+    OptionsModel optionsModel;
     ClientModel clientModel(node, &optionsModel);
     AddWallet(wallet);
     WalletModel walletModel(interfaces::MakeWallet(wallet), clientModel, platformStyle.get());
diff --git a/src/qt/test/test_main.cpp b/src/qt/test/test_main.cpp
index 031913bd02..86356b43c8 100644
--- a/src/qt/test/test_main.cpp
+++ b/src/qt/test/test_main.cpp
@@ -68,11 +68,11 @@ int main(int argc, char* argv[])
 
     // Don't remove this, it's needed to access
     // QApplication:: and QCoreApplication:: in the tests
-    BitcoinApplication app(*node);
+    BitcoinApplication app;
+    app.setNode(*node);
     app.setApplicationName("Bitcoin-Qt-test");
 
-    node->setupServerArgs();            // Make gArgs available in the NodeContext
-    node->context()->args->ClearArgs(); // Clear added args again
+    app.node().context()->args = &gArgs;     // Make gArgs available in the NodeContext
     AppTests app_tests(app);
     if (QTest::qExec(&app_tests) != 0) {
         fInvalid = true;
@@ -81,7 +81,7 @@ int main(int argc, char* argv[])
     if (QTest::qExec(&test1) != 0) {
         fInvalid = true;
     }
-    RPCNestedTests test3(*node);
+    RPCNestedTests test3(app.node());
     if (QTest::qExec(&test3) != 0) {
         fInvalid = true;
     }
@@ -90,11 +90,11 @@ int main(int argc, char* argv[])
         fInvalid = true;
     }
 #ifdef ENABLE_WALLET
-    WalletTests test5(*node);
+    WalletTests test5(app.node());
     if (QTest::qExec(&test5) != 0) {
         fInvalid = true;
     }
-    AddressBookTests test6(*node);
+    AddressBookTests test6(app.node());
     if (QTest::qExec(&test6) != 0) {
         fInvalid = true;
     }
diff --git a/src/qt/test/wallettests.cpp b/src/qt/test/wallettests.cpp
index 475fd589af..adcfe0d25c 100644
--- a/src/qt/test/wallettests.cpp
+++ b/src/qt/test/wallettests.cpp
@@ -163,7 +163,7 @@ void TestGUI(interfaces::Node& node)
     std::unique_ptr<const PlatformStyle> platformStyle(PlatformStyle::instantiate("other"));
     SendCoinsDialog sendCoinsDialog(platformStyle.get());
     TransactionView transactionView(platformStyle.get());
-    OptionsModel optionsModel(node);
+    OptionsModel optionsModel;
     ClientModel clientModel(node, &optionsModel);
     AddWallet(wallet);
     WalletModel walletModel(interfaces::MakeWallet(wallet), clientModel, platformStyle.get());
diff --git a/src/qt/utilitydialog.cpp b/src/qt/utilitydialog.cpp
index 01922cf996..b7f85446f4 100644
--- a/src/qt/utilitydialog.cpp
+++ b/src/qt/utilitydialog.cpp
@@ -28,7 +28,7 @@
 #include <QVBoxLayout>
 
 /** "Help message" or "About" dialog box */
-HelpMessageDialog::HelpMessageDialog(interfaces::Node& node, QWidget *parent, bool about) :
+HelpMessageDialog::HelpMessageDialog(QWidget *parent, bool about) :
     QDialog(parent),
     ui(new Ui::HelpMessageDialog)
 {
diff --git a/src/qt/utilitydialog.h b/src/qt/utilitydialog.h
index 425b468f40..d2a5d5f67f 100644
--- a/src/qt/utilitydialog.h
+++ b/src/qt/utilitydialog.h
@@ -12,10 +12,6 @@ QT_BEGIN_NAMESPACE
 class QMainWindow;
 QT_END_NAMESPACE
 
-namespace interfaces {
-    class Node;
-}
-
 namespace Ui {
     class HelpMessageDialog;
 }
@@ -26,7 +22,7 @@ class HelpMessageDialog : public QDialog
     Q_OBJECT
 
 public:
-    explicit HelpMessageDialog(interfaces::Node& node, QWidget *parent, bool about);
+    explicit HelpMessageDialog(QWidget *parent, bool about);
     ~HelpMessageDialog();
 
     void printToConsole();