Allow disabling network proxies

Both manually and automatically. There's now a setting in the network
preferences to toggle between the system-defined proxy and disabling it
altogether. When the system-defined proxy is enabled, Drawpile will
check if it's valid at all and automatically disable it if not, e.g.
because it's a proxy that can't actually tunnel connections.

Relates to #1360.

ChangeLog

@@ -1,6 +1,7 @@
 Unreleased Version 2.2.2-pre
  * Fix: Solve rendering glitches with selection outlines that happen on some systems. Thanks xxxx for reporting.
  * Feature: Allow scaling animation exports. Thanks Hopfel for animating across a giant canvas.
+ * Fix: Allow disabling the application proxy in the network preferences and automatically detect bad proxy configurations that can't actually make connections. Thanks FishEggsThe for reporting.
 
 2024-08-09 Version 2.2.2-beta.3
  * Fix: Use more accurate timers for performance profiles if the platform supports it.

src/desktop/dialogs/settingsdialog/network.cpp

@@ -9,6 +9,7 @@
 #include "desktop/widgets/kis_slider_spin_box.h"
 #include "libclient/utils/avatarlistmodel.h"
 #include "libclient/utils/avatarlistmodeldelegate.h"
+#include "libshared/net/proxy.h"
 #include <QCheckBox>
 #include <QFormLayout>
 #include <QHBoxLayout>
@@ -138,6 +139,14 @@ void Network::initNetwork(
 	form->addRow(
 		tr("Network timeout:"), utils::encapsulate(tr("%1 seconds"), timeout));
 
+#ifndef __EMSCRIPTEN__
+	auto *proxy = utils::addRadioGroup(
+		form, tr("Network proxy:"), true,
+		{{tr("System"), int(net::ProxyMode::Default)},
+		 {tr("Disabled"), int(net::ProxyMode::Disabled)}});
+	settings.bindNetworkProxyMode(proxy);
+#endif
+
 	auto *messageQueueDrainRate = new KisSliderSpinBox;
 	messageQueueDrainRate->setRange(
 		0, net::MessageQueue::MAX_SMOOTH_DRAIN_RATE);

src/desktop/mainwindow.cpp

@@ -2272,6 +2272,7 @@ void MainWindow::hostSession(
 		return;
 	}
 
+	// clang-format on
 	// Start server if hosting locally
 	const desktop::settings::Settings &settings = dpApp().settings();
 	if(!useremote) {
@@ -2283,7 +2284,8 @@ void MainWindow::hostSession(
 		QString errorMessage;
 		bool serverStarted = server->start(
 			settings.serverPort(), settings.serverTimeout(),
-			settings.serverPrivateUserList(), &errorMessage);
+			settings.networkProxyMode(), settings.serverPrivateUserList(),
+			&errorMessage);
 		if(!serverStarted) {
 			QMessageBox::warning(this, tr("Host Session"), errorMessage);
 			delete server;
@@ -2303,6 +2305,7 @@ void MainWindow::hostSession(
 		return;
 #endif
 	}
+	// clang-format off
 
 	// Connect to server
 	net::LoginHandler *login = new net::LoginHandler(
@@ -2326,7 +2329,8 @@ void MainWindow::hostSession(
 		shouldShowDialogMaximized());
 
 	m_doc->client()->connectToServer(
-		settings.serverTimeout(), login, !useremote);
+		settings.serverTimeout(), settings.networkProxyMode(), login,
+		!useremote);
 }
 
 void MainWindow::invite()
@@ -2551,7 +2555,9 @@ void MainWindow::joinSession(const QUrl& url, const QString &autoRecordFile)
 
 	dlg->show();
 	m_doc->setRecordOnConnect(autoRecordFile);
-	m_doc->client()->connectToServer(dpApp().settings().serverTimeout(), login, false);
+	const desktop::settings::Settings &settings = dpApp().settings();
+	m_doc->client()->connectToServer(
+		settings.serverTimeout(), settings.networkProxyMode(), login, false);
 }
 
 /**

src/libclient/net/client.cpp

@@ -26,12 +26,12 @@ Client::Client(CommandHandler *commandHandler, QObject *parent)
 }
 
 void Client::connectToServer(
-	int timeoutSecs, LoginHandler *loginhandler, bool builtin)
+	int timeoutSecs, int proxyMode, LoginHandler *loginhandler, bool builtin)
 {
 	Q_ASSERT(!isConnected());
 	m_builtin = builtin;
 
-	m_server = Server::make(loginhandler->url(), timeoutSecs, this);
+	m_server = Server::make(loginhandler->url(), timeoutSecs, proxyMode, this);
 	m_server->setSmoothDrainRate(m_smoothDrainRate);
 
 #ifdef Q_OS_ANDROID

src/libclient/net/client.h

@@ -51,8 +51,9 @@ class Client final : public QObject {
 	 * @brief Connect to a remote server
 	 * @param loginhandler the login handler to use
 	 */
-	void
-	connectToServer(int timeoutSecs, LoginHandler *loginhandler, bool builtin);
+	void connectToServer(
+		int timeoutSecs, int proxyMode, LoginHandler *loginhandler,
+		bool builtin);
 
 	/**
 	 * @brief Disconnect from the remote server

src/libclient/net/server.cpp

@@ -15,20 +15,21 @@
 
 namespace net {
 
-Server *Server::make(const QUrl &url, int timeoutSecs, Client *client)
+Server *Server::make(
+	const QUrl &url, int timeoutSecs, int proxyMode, Client *client)
 {
 #if defined(HAVE_WEBSOCKETS) && defined(HAVE_TCPSOCKETS)
 	if(url.scheme().startsWith(QStringLiteral("ws"), Qt::CaseInsensitive)) {
-		return new WebSocketServer(timeoutSecs, client);
+		return new WebSocketServer(timeoutSecs, proxyMode, client);
 	} else {
-		return new TcpServer(timeoutSecs, client);
+		return new TcpServer(timeoutSecs, proxyMode, client);
 	}
 #elif defined(HAVE_TCPSOCKETS)
 	Q_UNUSED(url);
-	return new TcpServer(timeoutSecs, client);
+	return new TcpServer(timeoutSecs, proxyMode, client);
 #elif defined(HAVE_WEBSOCKETS)
 	Q_UNUSED(url);
-	return new WebSocketServer(timeoutSecs, client);
+	return new WebSocketServer(timeoutSecs, proxyMode, client);
 #else
 #	error "No socket implementation compiled in."
 #endif

src/libclient/net/server.h

@@ -31,7 +31,8 @@ class Server : public QObject {
 		TRUSTED_HOST // A host we have explicitly marked as trusted
 	};
 
-	static Server *make(const QUrl &url, int timeoutSecs, Client *client);
+	static Server *
+	make(const QUrl &url, int timeoutSecs, int proxyMode, Client *client);
 
 	static QString addSchemeToUserSuppliedAddress(const QString &remoteAddress);
 	static QUrl fixUpAddress(const QUrl &originalUrl, bool join);

src/libclient/net/tcpserver.cpp

@@ -2,18 +2,23 @@
 #include "libclient/net/tcpserver.h"
 #include "cmake-config/config.h"
 #include "libclient/net/login.h"
+#include "libshared/net/proxy.h"
 #include "libshared/net/tcpmessagequeue.h"
 #include "libshared/util/qtcompat.h"
 #include <QDebug>
+#include <QNetworkProxy>
 #include <QSslConfiguration>
 #include <QSslSocket>
 
 namespace net {
 
-TcpServer::TcpServer(int timeoutSecs, Client *client)
+TcpServer::TcpServer(int timeoutSecs, int proxyMode, Client *client)
 	: Server(client)
 {
 	m_socket = new QSslSocket(this);
+	if(shouldDisableProxy(proxyMode, m_socket->proxy(), false, false)) {
+		m_socket->setProxy(QNetworkProxy::NoProxy);
+	}
 	m_socket->setSocketOption(QAbstractSocket::LowDelayOption, true);
 
 	QSslConfiguration sslconf = m_socket->sslConfiguration();

src/libclient/net/tcpserver.h

@@ -12,7 +12,7 @@ namespace net {
 class TcpServer final : public Server {
 	Q_OBJECT
 public:
-	explicit TcpServer(int timeoutSecs, Client *client);
+	explicit TcpServer(int timeoutSecs, int proxyMode, Client *client);
 
 	bool isWebSocket() const override;
 

src/libclient/net/websocketserver.cpp

@@ -2,6 +2,10 @@
 #include "libclient/net/websocketserver.h"
 #include "libshared/net/websocketmessagequeue.h"
 #include <QWebSocket>
+#ifndef __EMSCRIPTEN__
+#	include "libshared/net/proxy.h"
+#	include <QNetworkProxy>
+#endif
 
 namespace {
 #ifdef HAVE_WEBSOCKETS
@@ -16,10 +20,17 @@ const auto WebSocketError =
 
 namespace net {
 
-WebSocketServer::WebSocketServer(int timeoutSecs, Client *client)
+WebSocketServer::WebSocketServer(int timeoutSecs, int proxyMode, Client *client)
 	: Server(client)
 {
 	m_socket = new QWebSocket(QString(), QWebSocketProtocol::Version13, this);
+#ifdef __EMSCRIPTEN__
+	Q_UNUSED(proxyMode);
+#else
+	if(shouldDisableProxy(proxyMode, m_socket->proxy(), true, false)) {
+		m_socket->setProxy(QNetworkProxy::NoProxy);
+	}
+#endif
 
 	m_msgqueue = new WebSocketMessageQueue(m_socket, true, this);
 	m_msgqueue->setIdleTimeout(timeoutSecs * 1000);

src/libclient/net/websocketserver.h

@@ -12,7 +12,8 @@ class WebSocketMessageQueue;
 class WebSocketServer final : public Server {
 	Q_OBJECT
 public:
-	explicit WebSocketServer(int timeoutSecs, Client *client);
+	explicit WebSocketServer(
+		int timeoutSecs, int proxyMode, Client *client);
 
 	bool isWebSocket() const override;
 

src/libclient/server/builtinserver.cpp

@@ -6,7 +6,9 @@
 #include "libserver/client.h"
 #include "libserver/inmemoryconfig.h"
 #include "libserver/loginhandler.h"
+#include "libshared/net/proxy.h"
 #include <QJsonArray>
+#include <QNetworkProxy>
 #include <QTcpServer>
 
 namespace server {
@@ -60,12 +62,15 @@ std::tuple<Session *, QString> BuiltinServer::createSession(
 }
 
 bool BuiltinServer::start(
-	quint16 preferredPort, int clientTimeout, bool privateUserList,
-	QString *outErrorMessage)
+	quint16 preferredPort, int clientTimeout, int proxyMode,
+	bool privateUserList, QString *outErrorMessage)
 {
 	Q_ASSERT(!m_server);
 
 	m_server = new QTcpServer{this};
+	if(net::shouldDisableProxy(proxyMode, m_server->proxy(), false, true)) {
+		m_server->setProxy(QNetworkProxy::NoProxy);
+	}
 	connect(
 		m_server, &QTcpServer::newConnection, this, &BuiltinServer::newClient);
 

src/libclient/server/builtinserver.h

@@ -50,8 +50,8 @@ class BuiltinServer final : public QObject, public Sessions {
 		const QString &founder) override;
 
 	bool start(
-		quint16 preferredPort, int clientTimeout, bool privateUserList,
-		QString *outErrorMessage = nullptr);
+		quint16 preferredPort, int clientTimeout, int proxyMode,
+		bool privateUserList, QString *outErrorMessage = nullptr);
 
 public slots:
 	void stop();

src/libclient/settings_table.h

@@ -17,6 +17,7 @@ SETTING(checkerColor2               , CheckerColor2               , "settings/ch
 SETTING(interpolateInputs           , InterpolateInputs           , "settings/input/interpolate"            , true)
 SETTING(messageQueueDrainRate       , MessageQueueDrainRate       , "settings/messagequeuedrainrate"        , net::MessageQueue::DEFAULT_SMOOTH_DRAIN_RATE)
 SETTING(mouseSmoothing              , MouseSmoothing              , "settings/input/mousesmoothing"         , false)
+SETTING(networkProxyMode            , NetworkProxyMode            , "settings/networkproxymode"             , 0)
 SETTING(parentalControlsAutoTag     , ParentalControlsAutoTag     , "pc/autotag"                            , true)
 SETTING(parentalControlsForceCensor , ParentalControlsForceCensor , "pc/noUncensoring"                      , false)
 SETTING(parentalControlsLevel       , ParentalControlsLevel       , "pc/level"                              , parentalcontrols::Level::Unrestricted)

src/libshared/CMakeLists.txt

@@ -13,6 +13,8 @@ target_sources(dpshared PRIVATE
 	net/messagequeue.h
 	net/protover.cpp
 	net/protover.h
+	net/proxy.cpp
+	net/proxy.h
 	net/servercmd.cpp
 	net/servercmd.h
 	util/database.cpp

src/libshared/net/proxy.h

@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+#ifndef LIBSHARED_NET_PROXY_H
+#define LIBSHARED_NET_PROXY_H
+
+class QNetworkProxy;
+
+namespace net {
+
+enum class ProxyMode {
+	Default = 0,
+	Disabled = 1,
+};
+
+bool shouldDisableProxy(
+	int proxyMode, const QNetworkProxy &proxy, bool allowHttp, bool listen);
+
+}
+
+#endif