Add an SSCSM controller and environment skeleton

src/client/client.cpp

@@ -51,6 +51,7 @@
 #include "translation.h"
 #include "content/mod_configuration.h"
 #include "mapnode.h"
+#include "script/sscsm_controller.h"
 
 extern gui::IGUIEnvironment* guienv;
 
@@ -131,6 +132,8 @@ Client::Client(
 
 	m_cache_save_interval = g_settings->getU16("server_map_save_interval");
 	m_mesh_grid = { g_settings->getU16("client_mesh_chunk") };
+
+	m_sscsm_controller = SSCSMController::create();
 }
 
 void Client::migrateModStorage()
@@ -498,6 +501,8 @@ void Client::step(float dtime)
 	*/
 	LocalPlayer *player = m_env.getLocalPlayer();
 
+	m_sscsm_controller->eventOnStep(this, dtime);
+
 	// Step environment (also handles player controls)
 	m_env.step(dtime);
 	m_sound->step(dtime);

src/client/client.h

@@ -55,6 +55,8 @@ struct MeshMakeData;
 struct MinimapMapblock;
 struct PlayerControl;
 struct PointedThing;
+class ClientScripting;
+class SSCSMController;
 
 namespace con {
 class IConnection;
@@ -98,8 +100,6 @@ class PacketCounter
 	std::map<u16, u32> m_packets;
 };
 
-class ClientScripting;
-
 class Client : public con::PeerHandler, public InventoryManager, public IGameDef
 {
 public:
@@ -582,6 +582,9 @@ class Client : public con::PeerHandler, public InventoryManager, public IGameDef
 	std::vector<ModSpec> m_mods;
 	StringMap m_mod_vfs;
 
+	// SSCSM
+	std::unique_ptr<SSCSMController> m_sscsm_controller;
+
 	bool m_shutdown = false;
 
 	// CSM restrictions byteflag

src/script/CMakeLists.txt

@@ -15,6 +15,8 @@ set(common_SCRIPT_SRCS
 set(client_SCRIPT_SRCS
 	${CMAKE_CURRENT_SOURCE_DIR}/scripting_mainmenu.cpp
 	${CMAKE_CURRENT_SOURCE_DIR}/scripting_client.cpp
+	${CMAKE_CURRENT_SOURCE_DIR}/sscsm_controller.cpp
+	${CMAKE_CURRENT_SOURCE_DIR}/sscsm_environment.cpp
 	${client_SCRIPT_COMMON_SRCS}
 	${client_SCRIPT_CPP_API_SRCS}
 	${client_SCRIPT_LUA_API_SRCS}

src/script/sscsm_controller.cpp

@@ -0,0 +1,65 @@
+// SPDX-FileCopyrightText: 2024 Luanti authors
+//
+// SPDX-License-Identifier: LGPL-2.1-or-later
+
+#include "sscsm_controller.h"
+#include "sscsm_environment.h"
+#include "sscsm_requests.h"
+#include "sscsm_events.h"
+#include "sscsm_stupid_channel.h"
+
+std::unique_ptr<SSCSMController> SSCSMController::create()
+{
+	auto channel = std::make_shared<StupidChannel>();
+	auto thread = std::make_unique<SSCSMEnvironment>(channel);
+	thread->start();
+
+	// Wait for thread to finish initializing.
+	auto req0 = deserializeSSCSMRequest(channel->recvB());
+	FATAL_ERROR_IF(!dynamic_cast<SSCSMRequestPollNextEvent *>(req0.get()),
+			"First request must be pollEvent.");
+
+	return std::make_unique<SSCSMController>(std::move(thread), channel);
+}
+
+SSCSMController::SSCSMController(std::unique_ptr<SSCSMEnvironment> thread,
+		std::shared_ptr<StupidChannel> channel) :
+	m_thread(std::move(thread)), m_channel(std::move(channel))
+{
+}
+
+SSCSMController::~SSCSMController()
+{
+	// send tear-down
+	m_channel->sendB(serializeSSCSMAnswer(SSCSMAnswerPollNextEvent{
+			std::make_unique<SSCSMEventTearDown>()
+		}));
+	// wait for death
+	m_thread->stop();
+	m_thread->wait();
+}
+
+SerializedSSCSMAnswer SSCSMController::handleRequest(Client *client, ISSCSMRequest *req)
+{
+	return req->exec(client);
+}
+
+void SSCSMController::runEvent(Client *client, std::unique_ptr<ISSCSMEvent> event)
+{
+	auto answer = serializeSSCSMAnswer(SSCSMAnswerPollNextEvent{std::move(event)});
+
+	while (true) {
+		auto request = deserializeSSCSMRequest(m_channel->exchangeB(std::move(answer)));
+
+		if (dynamic_cast<SSCSMRequestPollNextEvent *>(request.get()) != nullptr) {
+			break;
+		}
+
+		answer = handleRequest(client, request.get());
+	}
+}
+
+void SSCSMController::eventOnStep(Client *client, f32 dtime)
+{
+	runEvent(client, std::make_unique<SSCSMEventOnStep>(dtime));
+}

src/script/sscsm_controller.h

@@ -0,0 +1,37 @@
+// SPDX-FileCopyrightText: 2024 Luanti authors
+//
+// SPDX-License-Identifier: LGPL-2.1-or-later
+
+#pragma once
+
+#include <memory>
+#include "irrlichttypes.h"
+#include "sscsm_irequest.h"
+#include "sscsm_ievent.h"
+#include "util/basic_macros.h"
+
+class SSCSMEnvironment;
+class StupidChannel;
+
+class SSCSMController
+{
+	std::unique_ptr<SSCSMEnvironment> m_thread;
+	std::shared_ptr<StupidChannel> m_channel;
+
+	SerializedSSCSMAnswer handleRequest(Client *client, ISSCSMRequest *req);
+
+public:
+	static std::unique_ptr<SSCSMController> create();
+
+	SSCSMController(std::unique_ptr<SSCSMEnvironment> thread,
+			std::shared_ptr<StupidChannel> channel);
+
+	~SSCSMController();
+
+	DISABLE_CLASS_COPY(SSCSMController);
+
+	// Handles requests until the next event is polled
+	void runEvent(Client *client, std::unique_ptr<ISSCSMEvent> event);
+
+	void eventOnStep(Client *client, f32 dtime);
+};

src/script/sscsm_environment.cpp

@@ -0,0 +1,47 @@
+// SPDX-FileCopyrightText: 2024 Luanti authors
+//
+// SPDX-License-Identifier: LGPL-2.1-or-later
+
+#include "sscsm_environment.h"
+#include "sscsm_requests.h"
+#include "sscsm_events.h"
+#include "sscsm_stupid_channel.h"
+
+
+void *SSCSMEnvironment::run()
+{
+	while (true) {
+		auto next_event = cmdPollNextEvent();
+
+		if (dynamic_cast<SSCSMEventTearDown *>(next_event.get())) {
+			break;
+		}
+
+		next_event->exec(this);
+	}
+
+	return nullptr;
+}
+
+SerializedSSCSMAnswer SSCSMEnvironment::exchange(SerializedSSCSMRequest req)
+{
+	return m_channel->exchangeA(std::move(req));
+}
+
+std::unique_ptr<ISSCSMEvent> SSCSMEnvironment::cmdPollNextEvent()
+{
+	auto request = SSCSMRequestPollNextEvent{};
+	auto answer = deserializeSSCSMAnswer<SSCSMAnswerPollNextEvent>(
+			exchange(serializeSSCSMRequest(request))
+		);
+	return std::move(answer.next_event);
+}
+
+MapNode SSCSMEnvironment::cmdGetNode(v3s16 pos)
+{
+	auto request = SSCSMRequestGetNode{pos};
+	auto answer = deserializeSSCSMAnswer<SSCSMAnswerGetNode>(
+			exchange(serializeSSCSMRequest(request))
+		);
+	return answer.node;
+}

src/script/sscsm_environment.h

@@ -0,0 +1,32 @@
+// SPDX-FileCopyrightText: 2024 Luanti authors
+//
+// SPDX-License-Identifier: LGPL-2.1-or-later
+
+#pragma once
+
+#include <memory>
+#include "client/client.h"
+#include "threading/thread.h"
+#include "sscsm_controller.h"
+#include "sscsm_irequest.h"
+
+// The thread that runs SSCSM code.
+// Meant to be replaced by a sandboxed process.
+class SSCSMEnvironment : public Thread
+{
+	std::shared_ptr<StupidChannel> m_channel;
+
+	void *run() override;
+
+	SerializedSSCSMAnswer exchange(SerializedSSCSMRequest req);
+
+public:
+	SSCSMEnvironment(std::shared_ptr<StupidChannel> channel) :
+		Thread("SSCSMEnvironment-thread"),
+		m_channel(std::move(channel))
+	{
+	}
+
+	std::unique_ptr<ISSCSMEvent> cmdPollNextEvent();
+	MapNode cmdGetNode(v3s16 pos);
+};

src/script/sscsm_events.h

@@ -0,0 +1,34 @@
+// SPDX-FileCopyrightText: 2024 Luanti authors
+//
+// SPDX-License-Identifier: LGPL-2.1-or-later
+
+#pragma once
+
+#include "sscsm_ievent.h"
+#include "debug.h"
+#include "irrlichttypes.h"
+#include "irr_v3d.h"
+#include "sscsm_environment.h"
+#include "mapnode.h"
+
+struct SSCSMEventTearDown : public ISSCSMEvent
+{
+	void exec(SSCSMEnvironment *env) override
+	{
+		FATAL_ERROR("SSCSMEventTearDown needs to be handled by SSCSMEnvironment::run()");
+	}
+};
+
+struct SSCSMEventOnStep : public ISSCSMEvent
+{
+	f32 dtime;
+
+	SSCSMEventOnStep(f32 dtime_) : dtime(dtime_) {}
+
+	void exec(SSCSMEnvironment *env) override
+	{
+		// example
+		env->cmdGetNode(v3s16(0, 0, 0));
+	}
+};
+

src/script/sscsm_ievent.h

@@ -0,0 +1,39 @@
+// SPDX-FileCopyrightText: 2024 Luanti authors
+//
+// SPDX-License-Identifier: LGPL-2.1-or-later
+
+#pragma once
+
+#include <memory>
+#include <type_traits>
+
+class SSCSMEnvironment;
+
+// Event triggered from the main env for the SSCSM env.
+struct ISSCSMEvent
+{
+	virtual ~ISSCSMEvent() = default;
+
+	// Note: No return value (difference to ISSCSMRequest). These are not callbacks
+	// that you can run at arbitrary locations, because the untrusted code could
+	// then clobber your local variables.
+	virtual void exec(SSCSMEnvironment *cntrl) = 0;
+};
+
+// FIXME: actually serialize, and replace this with a string
+using SerializedSSCSMEvent = std::unique_ptr<ISSCSMEvent>;
+
+template <typename T>
+inline SerializedSSCSMEvent serializeSSCSMEvent(const T &event)
+{
+	static_assert(std::is_base_of_v<ISSCSMEvent, T>);
+
+	return std::make_unique<T>(event);
+}
+
+inline std::unique_ptr<ISSCSMEvent> deserializeSSCSMEvent(SerializedSSCSMEvent event_serialized)
+{
+	// The actual deserialization will have to use a type tag, and then choose
+	// the appropriate deserializer.
+	return event_serialized;
+}

src/script/sscsm_irequest.h

@@ -0,0 +1,67 @@
+// SPDX-FileCopyrightText: 2024 Luanti authors
+//
+// SPDX-License-Identifier: LGPL-2.1-or-later
+
+#pragma once
+
+#include "exceptions.h"
+#include <memory>
+#include <type_traits>
+
+class SSCSMController;
+class Client;
+
+struct ISSCSMAnswer
+{
+	virtual ~ISSCSMAnswer() = default;
+};
+
+// FIXME: actually serialize, and replace this with a string
+using SerializedSSCSMAnswer = std::unique_ptr<ISSCSMAnswer>;
+
+// Request made by the sscsm env to the main env.
+struct ISSCSMRequest
+{
+	virtual ~ISSCSMRequest() = default;
+
+	virtual SerializedSSCSMAnswer exec(Client *client) = 0;
+};
+
+// FIXME: actually serialize, and replace this with a string
+using SerializedSSCSMRequest = std::unique_ptr<ISSCSMRequest>;
+
+template <typename T>
+inline SerializedSSCSMRequest serializeSSCSMRequest(const T &request)
+{
+	static_assert(std::is_base_of_v<ISSCSMRequest, T>);
+
+	return std::make_unique<T>(request);
+}
+
+template <typename T>
+inline T deserializeSSCSMAnswer(SerializedSSCSMAnswer answer_serialized)
+{
+	static_assert(std::is_base_of_v<ISSCSMAnswer, T>);
+
+	// dynamic cast in place of actual deserialization
+	auto ptr = dynamic_cast<T *>(answer_serialized.get());
+	if (!ptr) {
+		throw SerializationError("deserializeSSCSMAnswer failed");
+	}
+	return std::move(*ptr);
+}
+
+template <typename T>
+inline SerializedSSCSMAnswer serializeSSCSMAnswer(T answer)
+{
+	static_assert(std::is_base_of_v<ISSCSMAnswer, T>);
+
+	return std::make_unique<T>(std::move(answer));
+}
+
+inline std::unique_ptr<ISSCSMRequest> deserializeSSCSMRequest(SerializedSSCSMRequest request_serialized)
+{
+	// The actual deserialization will have to use a type tag, and then choose
+	// the appropriate deserializer.
+	return request_serialized;
+}