minetest/src/server.cpp

/*
Minetest
Copyright (C) 2010-2013 celeron55, Perttu Ahola <celeron55@gmail.com>

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/

#include "server.h"
#include <iostream>
#include <queue>
#include <algorithm>
#include "network/connection.h"
#include "network/networkprotocol.h"
#include "network/serveropcodes.h"
#include "ban.h"
#include "environment.h"
#include "map.h"
#include "threading/mutex_auto_lock.h"
#include "constants.h"
#include "voxel.h"
#include "config.h"
#include "version.h"
#include "filesys.h"
#include "mapblock.h"
#include "server/serveractiveobject.h"
#include "settings.h"
#include "profiler.h"
#include "log.h"
#include "scripting_server.h"
#include "nodedef.h"
#include "itemdef.h"
#include "craftdef.h"
#include "emerge.h"
#include "mapgen/mapgen.h"
#include "mapgen/mg_biome.h"
#include "content_mapnode.h"
#include "content_nodemeta.h"
#include "content/mods.h"
#include "modchannels.h"
#include "serverlist.h"
#include "util/string.h"
#include "rollback.h"
#include "util/serialize.h"
#include "util/thread.h"
#include "defaultsettings.h"
#include "server/mods.h"
#include "util/base64.h"
#include "util/sha1.h"
#include "util/hex.h"
#include "database/database.h"
#include "chatmessage.h"
#include "chat_interface.h"
#include "remoteplayer.h"
#include "server/player_sao.h"
#include "server/serverinventorymgr.h"
#include "translation.h"
#include "database/database-sqlite3.h"
#include "database/database-files.h"
#include "database/database-dummy.h"
#include "gameparams.h"

class ClientNotFoundException : public BaseException
{
public:
	ClientNotFoundException(const char *s):
		BaseException(s)
	{}
};

class ServerThread : public Thread
{
public:

	ServerThread(Server *server):
		Thread("Server"),
		m_server(server)
	{}

	void *run();

private:
	Server *m_server;
};

void *ServerThread::run()
{
	BEGIN_DEBUG_EXCEPTION_HANDLER

	/*
	 * The real business of the server happens on the ServerThread.
	 * How this works:
	 * AsyncRunStep() runs an actual server step as soon as enough time has
	 * passed (dedicated_server_loop keeps track of that).
	 * Receive() blocks at least(!) 30ms waiting for a packet (so this loop
	 * doesn't busy wait) and will process any remaining packets.
	 */

	try {
		m_server->AsyncRunStep(true);
	} catch (con::ConnectionBindFailed &e) {
		m_server->setAsyncFatalError(e.what());
	} catch (LuaError &e) {
		m_server->setAsyncFatalError(e);
	}

	while (!stopRequested()) {
		try {
			m_server->AsyncRunStep();

			m_server->Receive();

		} catch (con::PeerNotFoundException &e) {
			infostream<<"Server: PeerNotFoundException"<<std::endl;
		} catch (ClientNotFoundException &e) {
		} catch (con::ConnectionBindFailed &e) {
			m_server->setAsyncFatalError(e.what());
		} catch (LuaError &e) {
			m_server->setAsyncFatalError(e);
		}
	}

	END_DEBUG_EXCEPTION_HANDLER

	return nullptr;
}

v3f ServerPlayingSound::getPos(ServerEnvironment *env, bool *pos_exists) const
{
	if (pos_exists)
		*pos_exists = false;

	switch (type ){
	case SoundLocation::Local:
		return v3f(0,0,0);
	case SoundLocation::Position:
		if (pos_exists)
			*pos_exists = true;
		return pos;
	case SoundLocation::Object:
		{
			if (object == 0)
				return v3f(0,0,0);
			ServerActiveObject *sao = env->getActiveObject(object);
			if (!sao)
				return v3f(0,0,0);
			if (pos_exists)
				*pos_exists = true;
			return sao->getBasePosition();
		}
	}
	return v3f(0,0,0);
}

void Server::ShutdownState::reset()
{
	m_timer = 0.0f;
	message.clear();
	should_reconnect = false;
	is_requested = false;
}

void Server::ShutdownState::trigger(float delay, const std::string &msg, bool reconnect)
{
	m_timer = delay;
	message = msg;
	should_reconnect = reconnect;
}

void Server::ShutdownState::tick(float dtime, Server *server)
{
	if (m_timer <= 0.0f)
		return;

	// Timed shutdown
	static const float shutdown_msg_times[] =
	{
		1, 2, 3, 4, 5, 10, 20, 40, 60, 120, 180, 300, 600, 1200, 1800, 3600
	};

	// Automated messages
	if (m_timer < shutdown_msg_times[ARRLEN(shutdown_msg_times) - 1]) {
		for (float t : shutdown_msg_times) {
			// If shutdown timer matches an automessage, shot it
			if (m_timer > t && m_timer - dtime < t) {
				std::wstring periodicMsg = getShutdownTimerMessage();

				infostream << wide_to_utf8(periodicMsg).c_str() << std::endl;
				server->SendChatMessage(PEER_ID_INEXISTENT, periodicMsg);
				break;
			}
		}
	}

	m_timer -= dtime;
	if (m_timer < 0.0f) {
		m_timer = 0.0f;
		is_requested = true;
	}
}

std::wstring Server::ShutdownState::getShutdownTimerMessage() const
{
	std::wstringstream ws;
	ws << L"*** Server shutting down in "
		<< duration_to_string(myround(m_timer)).c_str() << ".";
	return ws.str();
}

/*
	Server
*/

Server::Server(
		const std::string &path_world,
		const SubgameSpec &gamespec,
		bool simple_singleplayer_mode,
		Address bind_addr,
		bool dedicated,
		ChatInterface *iface,
		std::string *on_shutdown_errmsg
	):
	m_bind_addr(bind_addr),
	m_path_world(path_world),
	m_gamespec(gamespec),
	m_simple_singleplayer_mode(simple_singleplayer_mode),
	m_dedicated(dedicated),
	m_async_fatal_error(""),
	m_con(std::make_shared<con::Connection>(PROTOCOL_ID,
			512,
			CONNECTION_TIMEOUT,
			m_bind_addr.isIPv6(),
			this)),
	m_itemdef(createItemDefManager()),
	m_nodedef(createNodeDefManager()),
	m_craftdef(createCraftDefManager()),
	m_thread(new ServerThread(this)),
	m_clients(m_con),
	m_admin_chat(iface),
	m_on_shutdown_errmsg(on_shutdown_errmsg),
	m_modchannel_mgr(new ModChannelMgr())
{
	if (m_path_world.empty())
		throw ServerError("Supplied empty world path");

	if (!gamespec.isValid())
		throw ServerError("Supplied invalid gamespec");

#if USE_PROMETHEUS
	m_metrics_backend = std::unique_ptr<MetricsBackend>(createPrometheusMetricsBackend());
#else
	m_metrics_backend = std::make_unique<MetricsBackend>();
#endif

	m_uptime_counter = m_metrics_backend->addCounter("minetest_core_server_uptime", "Server uptime (in seconds)");
	m_player_gauge = m_metrics_backend->addGauge("minetest_core_player_number", "Number of connected players");

	m_timeofday_gauge = m_metrics_backend->addGauge(
			"minetest_core_timeofday",
			"Time of day value");

	m_lag_gauge = m_metrics_backend->addGauge(
			"minetest_core_latency",
			"Latency value (in seconds)");


	const std::string aom_types[] = {"reliable", "unreliable"};
	for (u32 i = 0; i < ARRLEN(aom_types); i++) {
		std::string help_str("Number of active object messages generated (");
		help_str.append(aom_types[i]).append(")");
		m_aom_buffer_counter[i] = m_metrics_backend->addCounter(
				"minetest_core_aom_generated_count", help_str,
				{{"type", aom_types[i]}});
	}

	m_packet_recv_counter = m_metrics_backend->addCounter(
			"minetest_core_server_packet_recv",
			"Processable packets received");

	m_packet_recv_processed_counter = m_metrics_backend->addCounter(
			"minetest_core_server_packet_recv_processed",
			"Valid received packets processed");

	m_map_edit_event_counter = m_metrics_backend->addCounter(
			"minetest_core_map_edit_events",
			"Number of map edit events");

	m_lag_gauge->set(g_settings->getFloat("dedicated_server_step"));
}

Server::~Server()
{

	// Send shutdown message
	SendChatMessage(PEER_ID_INEXISTENT, ChatMessage(CHATMESSAGE_TYPE_ANNOUNCE,
			L"*** Server shutting down"));

	if (m_env) {
		MutexAutoLock envlock(m_env_mutex);

		infostream << "Server: Saving players" << std::endl;
		m_env->saveLoadedPlayers();

		infostream << "Server: Kicking players" << std::endl;
		std::string kick_msg;
		bool reconnect = false;
		if (isShutdownRequested()) {
			reconnect = m_shutdown_state.should_reconnect;
			kick_msg = m_shutdown_state.message;
		}
		if (kick_msg.empty()) {
			kick_msg = g_settings->get("kick_msg_shutdown");
		}
		m_env->saveLoadedPlayers(true);
		m_env->kickAllPlayers(SERVER_ACCESSDENIED_SHUTDOWN,
			kick_msg, reconnect);
	}

	actionstream << "Server: Shutting down" << std::endl;

	// Do this before stopping the server in case mapgen callbacks need to access
	// server-controlled resources (like ModStorages). Also do them before
	// shutdown callbacks since they may modify state that is finalized in a
	// callback.
	if (m_emerge)
		m_emerge->stopThreads();

	if (m_env) {
		MutexAutoLock envlock(m_env_mutex);

		// Execute script shutdown hooks
		infostream << "Executing shutdown hooks" << std::endl;
		try {
			m_script->on_shutdown();
		} catch (ModError &e) {
			errorstream << "ModError: " << e.what() << std::endl;
			if (m_on_shutdown_errmsg) {
				if (m_on_shutdown_errmsg->empty()) {
					*m_on_shutdown_errmsg = std::string("ModError: ") + e.what();
				} else {
					*m_on_shutdown_errmsg += std::string("\nModError: ") + e.what();
				}
			}
		}

		infostream << "Server: Saving environment metadata" << std::endl;
		m_env->saveMeta();
	}

	// Stop threads
	if (m_thread) {
		stop();
		delete m_thread;
	}

	// Write any changes before deletion.
	if (m_mod_storage_database)
		m_mod_storage_database->endSave();

	// Delete things in the reverse order of creation
	delete m_emerge;
	delete m_env;
	delete m_rollback;
	delete m_mod_storage_database;
	delete m_banmanager;
	delete m_itemdef;
	delete m_nodedef;
	delete m_craftdef;

	// Deinitialize scripting
	infostream << "Server: Deinitializing scripting" << std::endl;
	delete m_script;
	delete m_startup_server_map; // if available
	delete m_game_settings;

	while (!m_unsent_map_edit_queue.empty()) {
		delete m_unsent_map_edit_queue.front();
		m_unsent_map_edit_queue.pop();
	}
}

void Server::init()
{
	infostream << "Server created for gameid \"" << m_gamespec.id << "\"";
	if (m_simple_singleplayer_mode)
		infostream << " in simple singleplayer mode" << std::endl;
	else
		infostream << std::endl;
	infostream << "- world:  " << m_path_world << std::endl;
	infostream << "- game:   " << m_gamespec.path << std::endl;

	m_game_settings = Settings::createLayer(SL_GAME);

	// Create world if it doesn't exist
	try {
		loadGameConfAndInitWorld(m_path_world,
				fs::GetFilenameFromPath(m_path_world.c_str()),
				m_gamespec, false);
	} catch (const BaseException &e) {
		throw ServerError(std::string("Failed to initialize world: ") + e.what());
	}

	// Create emerge manager
	m_emerge = new EmergeManager(this, m_metrics_backend.get());

	// Create ban manager
	std::string ban_path = m_path_world + DIR_DELIM "ipban.txt";
	m_banmanager = new BanManager(ban_path);

	// Create mod storage database and begin a save for later
	m_mod_storage_database = openModStorageDatabase(m_path_world);
	m_mod_storage_database->beginSave();

	m_modmgr = std::make_unique<ServerModManager>(m_path_world);
	std::vector<ModSpec> unsatisfied_mods = m_modmgr->getUnsatisfiedMods();
	// complain about mods with unsatisfied dependencies
	if (!m_modmgr->isConsistent()) {
		m_modmgr->printUnsatisfiedModsError();
	}

	//lock environment
	MutexAutoLock envlock(m_env_mutex);

	// Create the Map (loads map_meta.txt, overriding configured mapgen params)
	ServerMap *servermap = new ServerMap(m_path_world, this, m_emerge, m_metrics_backend.get());
	m_startup_server_map = servermap;

	// Initialize scripting
	infostream << "Server: Initializing Lua" << std::endl;

	m_script = new ServerScripting(this);

	// Must be created before mod loading because we have some inventory creation
	m_inventory_mgr = std::make_unique<ServerInventoryManager>();

	m_script->loadMod(getBuiltinLuaPath() + DIR_DELIM "init.lua", BUILTIN_MOD_NAME);

	m_gamespec.checkAndLog();
	m_modmgr->loadMods(m_script);

	// Read Textures and calculate sha1 sums
	fillMediaCache();

	// Apply item aliases in the node definition manager
	m_nodedef->updateAliases(m_itemdef);

	// Apply texture overrides from texturepack/override.txt
	std::vector<std::string> paths;
	fs::GetRecursiveDirs(paths, g_settings->get("texture_path"));
	fs::GetRecursiveDirs(paths, m_gamespec.path + DIR_DELIM + "textures");
	for (const std::string &path : paths) {
		TextureOverrideSource override_source(path + DIR_DELIM + "override.txt");
		m_nodedef->applyTextureOverrides(override_source.getNodeTileOverrides());
		m_itemdef->applyTextureOverrides(override_source.getItemTextureOverrides());
	}

	m_nodedef->setNodeRegistrationStatus(true);

	// Perform pending node name resolutions
	m_nodedef->runNodeResolveCallbacks();

	// unmap node names in cross-references
	m_nodedef->resolveCrossrefs();

	// init the recipe hashes to speed up crafting
	m_craftdef->initHashes(this);

	// Initialize Environment
	m_startup_server_map = nullptr; // Ownership moved to ServerEnvironment
	m_env = new ServerEnvironment(servermap, m_script, this,
		m_path_world, m_metrics_backend.get());

	m_inventory_mgr->setEnv(m_env);
	m_clients.setEnv(m_env);

	if (!servermap->settings_mgr.makeMapgenParams())
		FATAL_ERROR("Couldn't create any mapgen type");

	// Initialize mapgens
	m_emerge->initMapgens(servermap->getMapgenParams());

	if (g_settings->getBool("enable_rollback_recording")) {
		// Create rollback manager
		m_rollback = new RollbackManager(m_path_world, this);
	}

	// Give environment reference to scripting api
	m_script->initializeEnvironment(m_env);

	// Do this after regular script init is done
	m_script->initAsync();

	// Register us to receive map edit events
	servermap->addEventReceiver(this);

	m_env->loadMeta();

	// Those settings can be overwritten in world.mt, they are
	// intended to be cached after environment loading.
	m_liquid_transform_every = g_settings->getFloat("liquid_update");
	m_max_chatmessage_length = g_settings->getU16("chat_message_max_size");
	m_csm_restriction_flags = g_settings->getU64("csm_restriction_flags");
	m_csm_restriction_noderange = g_settings->getU32("csm_restriction_noderange");
}

void Server::start()
{
	init();

	infostream << "Starting server on " << m_bind_addr.serializeString()
			<< "..." << std::endl;

	// Stop thread if already running
	m_thread->stop();

	// Initialize connection
	m_con->SetTimeoutMs(30);
	m_con->Serve(m_bind_addr);

	// Start thread
	m_thread->start();

	// ASCII art for the win!
	std::cerr
		<< "         __.               __.                 __.  " << std::endl
		<< "  _____ |__| ____   _____ /  |_  _____  _____ /  |_ " << std::endl
		<< " /     \\|  |/    \\ /  __ \\    _\\/  __ \\/   __>    _\\" << std::endl
		<< "|  Y Y  \\  |   |  \\   ___/|  | |   ___/\\___  \\|  |  " << std::endl
		<< "|__|_|  /  |___|  /\\______>  |  \\______>_____/|  |  " << std::endl
		<< "      \\/ \\/     \\/         \\/                  \\/   " << std::endl;
	actionstream << "World at [" << m_path_world << "]" << std::endl;
	actionstream << "Server for gameid=\"" << m_gamespec.id
			<< "\" listening on ";
	m_bind_addr.print(actionstream);
	actionstream << "." << std::endl;
}

void Server::stop()
{
	infostream<<"Server: Stopping and waiting threads"<<std::endl;

	// Stop threads (set run=false first so both start stopping)
	m_thread->stop();
	m_thread->wait();

	infostream<<"Server: Threads stopped"<<std::endl;
}

void Server::step(float dtime)
{
	// Limit a bit
	if (dtime > 2.0)
		dtime = 2.0;
	{
		MutexAutoLock lock(m_step_dtime_mutex);
		m_step_dtime += dtime;
	}
	// Throw if fatal error occurred in thread
	std::string async_err = m_async_fatal_error.get();
	if (!async_err.empty()) {
		if (!m_simple_singleplayer_mode) {
			m_env->kickAllPlayers(SERVER_ACCESSDENIED_CRASH,
				g_settings->get("kick_msg_crash"),
				g_settings->getBool("ask_reconnect_on_crash"));
		}
		throw ServerError("AsyncErr: " + async_err);
	}
}

void Server::AsyncRunStep(bool initial_step)
{

	float dtime;
	{
		MutexAutoLock lock1(m_step_dtime_mutex);
		dtime = m_step_dtime;
	}

	{
		// Send blocks to clients
		SendBlocks(dtime);
	}

	if((dtime < 0.001) && !initial_step)
		return;

	ScopeProfiler sp(g_profiler, "Server::AsyncRunStep()", SPT_AVG);

	{
		MutexAutoLock lock1(m_step_dtime_mutex);
		m_step_dtime -= dtime;
	}

	/*
		Update uptime
	*/
	m_uptime_counter->increment(dtime);

	handlePeerChanges();

	/*
		Update time of day and overall game time
	*/
	m_env->setTimeOfDaySpeed(g_settings->getFloat("time_speed"));

	/*
		Send to clients at constant intervals
	*/

	m_time_of_day_send_timer -= dtime;
	if (m_time_of_day_send_timer < 0.0) {
		m_time_of_day_send_timer = g_settings->getFloat("time_send_interval");
		u16 time = m_env->getTimeOfDay();
		float time_speed = g_settings->getFloat("time_speed");
		SendTimeOfDay(PEER_ID_INEXISTENT, time, time_speed);

		m_timeofday_gauge->set(time);
	}

	{
		MutexAutoLock lock(m_env_mutex);
		// Figure out and report maximum lag to environment
		float max_lag = m_env->getMaxLagEstimate();
		max_lag *= 0.9998; // Decrease slowly (about half per 5 minutes)
		if(dtime > max_lag){
			if(dtime > 0.1 && dtime > max_lag * 2.0)
				infostream<<"Server: Maximum lag peaked to "<<dtime
						<<" s"<<std::endl;
			max_lag = dtime;
		}
		m_env->reportMaxLagEstimate(max_lag);

		// Step environment
		m_env->step(dtime);
	}

	static const float map_timer_and_unload_dtime = 2.92;
	if(m_map_timer_and_unload_interval.step(dtime, map_timer_and_unload_dtime))
	{
		MutexAutoLock lock(m_env_mutex);
		// Run Map's timers and unload unused data
		ScopeProfiler sp(g_profiler, "Server: map timer and unload");
		m_env->getMap().timerUpdate(map_timer_and_unload_dtime,
			std::max(g_settings->getFloat("server_unload_unused_data_timeout"), 0.0f),
			-1);
	}

	/*
		Listen to the admin chat, if available
	*/
	if (m_admin_chat) {
		if (!m_admin_chat->command_queue.empty()) {
			MutexAutoLock lock(m_env_mutex);
			while (!m_admin_chat->command_queue.empty()) {
				ChatEvent *evt = m_admin_chat->command_queue.pop_frontNoEx();
				handleChatInterfaceEvent(evt);
				delete evt;
			}
		}
		m_admin_chat->outgoing_queue.push_back(
			new ChatEventTimeInfo(m_env->getGameTime(), m_env->getTimeOfDay()));
	}

	/*
		Do background stuff
	*/

	/* Transform liquids */
	m_liquid_transform_timer += dtime;
	if(m_liquid_transform_timer >= m_liquid_transform_every)
	{
		m_liquid_transform_timer -= m_liquid_transform_every;

		MutexAutoLock lock(m_env_mutex);

		ScopeProfiler sp(g_profiler, "Server: liquid transform");

		std::map<v3s16, MapBlock*> modified_blocks;
		m_env->getServerMap().transformLiquids(modified_blocks, m_env);

		/*
			Set the modified blocks unsent for all the clients
		*/
		if (!modified_blocks.empty()) {
			SetBlocksNotSent(modified_blocks);
		}
	}
	m_clients.step(dtime);

	// increase/decrease lag gauge gradually
	if (m_lag_gauge->get() > dtime) {
		m_lag_gauge->decrement(dtime/100);
	} else {
		m_lag_gauge->increment(dtime/100);
	}

	{
		float &counter = m_step_pending_dyn_media_timer;
		counter += dtime;
		if (counter >= 5.0f) {
			stepPendingDynMediaCallbacks(counter);
			counter = 0;
		}
	}


#if USE_CURL
	// send masterserver announce
	{
		float &counter = m_masterserver_timer;
		if (!isSingleplayer() && (!counter || counter >= 300.0) &&
				g_settings->getBool("server_announce")) {
			ServerList::sendAnnounce(counter ? ServerList::AA_UPDATE :
						ServerList::AA_START,
					m_bind_addr.getPort(),
					m_clients.getPlayerNames(),
					m_uptime_counter->get(),
					m_env->getGameTime(),
					m_lag_gauge->get(),
					m_gamespec.id,
					Mapgen::getMapgenName(m_emerge->mgparams->mgtype),
					m_modmgr->getMods(),
					m_dedicated);
			counter = 0.01;
		}
		counter += dtime;
	}
#endif

	/*
		Check added and deleted active objects
	*/
	{
		//infostream<<"Server: Checking added and deleted active objects"<<std::endl;
		MutexAutoLock envlock(m_env_mutex);

		{
			ClientInterface::AutoLock clientlock(m_clients);
			const RemoteClientMap &clients = m_clients.getClientList();
			ScopeProfiler sp(g_profiler, "Server: update objects within range");

			m_player_gauge->set(clients.size());
			for (const auto &client_it : clients) {
				RemoteClient *client = client_it.second;

				if (client->getState() < CS_DefinitionsSent)
					continue;

				// This can happen if the client times out somehow
				if (!m_env->getPlayer(client->peer_id))
					continue;

				PlayerSAO *playersao = getPlayerSAO(client->peer_id);
				if (!playersao)
					continue;

				SendActiveObjectRemoveAdd(client, playersao);
			}
		}

		// Write changes to the mod storage
		m_mod_storage_save_timer -= dtime;
		if (m_mod_storage_save_timer <= 0.0f) {
			m_mod_storage_save_timer = g_settings->getFloat("server_map_save_interval");
			m_mod_storage_database->endSave();
			m_mod_storage_database->beginSave();
		}
	}

	/*
		Send object messages
	*/
	{
		MutexAutoLock envlock(m_env_mutex);
		ScopeProfiler sp(g_profiler, "Server: send SAO messages");

		// Key = object id
		// Value = data sent by object
		std::unordered_map<u16, std::vector<ActiveObjectMessage>*> buffered_messages;

		// Get active object messages from environment
		ActiveObjectMessage aom(0);
		u32 count_reliable = 0, count_unreliable = 0;
		for(;;) {
			if (!m_env->getActiveObjectMessage(&aom))
				break;
			if (aom.reliable)
				count_reliable++;
			else
				count_unreliable++;

			std::vector<ActiveObjectMessage>* message_list = nullptr;
			auto n = buffered_messages.find(aom.id);
			if (n == buffered_messages.end()) {
				message_list = new std::vector<ActiveObjectMessage>;
				buffered_messages[aom.id] = message_list;
			} else {
				message_list = n->second;
			}
			message_list->push_back(std::move(aom));
		}

		m_aom_buffer_counter[0]->increment(count_reliable);
		m_aom_buffer_counter[1]->increment(count_unreliable);

		{
			ClientInterface::AutoLock clientlock(m_clients);
			const RemoteClientMap &clients = m_clients.getClientList();
			// Route data to every client
			std::string reliable_data, unreliable_data;
			for (const auto &client_it : clients) {
				reliable_data.clear();
				unreliable_data.clear();
				RemoteClient *client = client_it.second;
				PlayerSAO *player = getPlayerSAO(client->peer_id);
				// Go through all objects in message buffer
				for (const auto &buffered_message : buffered_messages) {
					// If object does not exist or is not known by client, skip it
					u16 id = buffered_message.first;
					ServerActiveObject *sao = m_env->getActiveObject(id);
					if (!sao || client->m_known_objects.find(id) == client->m_known_objects.end())
						continue;

					// Get message list of object
					std::vector<ActiveObjectMessage>* list = buffered_message.second;
					// Go through every message
					for (const ActiveObjectMessage &aom : *list) {
						// Send position updates to players who do not see the attachment
						if (aom.datastring[0] == AO_CMD_UPDATE_POSITION) {
							if (sao->getId() == player->getId())
								continue;

							// Do not send position updates for attached players
							// as long the parent is known to the client
							ServerActiveObject *parent = sao->getParent();
							if (parent && client->m_known_objects.find(parent->getId()) !=
									client->m_known_objects.end())
								continue;
						}

						// Add full new data to appropriate buffer
						std::string &buffer = aom.reliable ? reliable_data : unreliable_data;
						char idbuf[2];
						writeU16((u8*) idbuf, aom.id);
						// u16 id
						// std::string data
						buffer.append(idbuf, sizeof(idbuf));
						buffer.append(serializeString16(aom.datastring));
					}
				}
				/*
					reliable_data and unreliable_data are now ready.
					Send them.
				*/
				if (!reliable_data.empty()) {
					SendActiveObjectMessages(client->peer_id, reliable_data);
				}

				if (!unreliable_data.empty()) {
					SendActiveObjectMessages(client->peer_id, unreliable_data, false);
				}
			}
		}

		// Clear buffered_messages
		for (auto &buffered_message : buffered_messages) {
			delete buffered_message.second;
		}
	}

	/*
		Send queued-for-sending map edit events.
	*/
	{
		// We will be accessing the environment
		MutexAutoLock lock(m_env_mutex);

		// Single change sending is disabled if queue size is big
		bool disable_single_change_sending = false;
		if(m_unsent_map_edit_queue.size() >= 4)
			disable_single_change_sending = true;

		const auto event_count = m_unsent_map_edit_queue.size();
		m_map_edit_event_counter->increment(event_count);

		// We'll log the amount of each
		Profiler prof;

		std::unordered_set<v3s16> node_meta_updates;

		while (!m_unsent_map_edit_queue.empty()) {
			MapEditEvent* event = m_unsent_map_edit_queue.front();
			m_unsent_map_edit_queue.pop();

			// Players far away from the change are stored here.
			// Instead of sending the changes, MapBlocks are set not sent
			// for them.
			std::unordered_set<u16> far_players;

			switch (event->type) {
			case MEET_ADDNODE:
			case MEET_SWAPNODE:
				prof.add("MEET_ADDNODE", 1);
				sendAddNode(event->p, event->n, &far_players,
						disable_single_change_sending ? 5 : 30,
						event->type == MEET_ADDNODE);
				break;
			case MEET_REMOVENODE:
				prof.add("MEET_REMOVENODE", 1);
				sendRemoveNode(event->p, &far_players,
						disable_single_change_sending ? 5 : 30);
				break;
			case MEET_BLOCK_NODE_METADATA_CHANGED: {
				prof.add("MEET_BLOCK_NODE_METADATA_CHANGED", 1);
				if (!event->is_private_change) {
					node_meta_updates.emplace(event->p);
				}

				if (MapBlock *block = m_env->getMap().getBlockNoCreateNoEx(
						getNodeBlockPos(event->p))) {
					block->raiseModified(MOD_STATE_WRITE_NEEDED,
						MOD_REASON_REPORT_META_CHANGE);
				}
				break;
			}
			case MEET_OTHER:
				prof.add("MEET_OTHER", 1);
				for (const v3s16 &modified_block : event->modified_blocks) {
					m_clients.markBlockposAsNotSent(modified_block);
				}
				break;
			default:
				prof.add("unknown", 1);
				warningstream << "Server: Unknown MapEditEvent "
						<< ((u32)event->type) << std::endl;
				break;
			}

			/*
				Set blocks not sent to far players
			*/
			if (!far_players.empty()) {
				// Convert list format to that wanted by SetBlocksNotSent
				std::map<v3s16, MapBlock*> modified_blocks2;
				for (const v3s16 &modified_block : event->modified_blocks) {
					modified_blocks2[modified_block] =
							m_env->getMap().getBlockNoCreateNoEx(modified_block);
				}

				// Set blocks not sent
				for (const u16 far_player : far_players) {
					if (RemoteClient *client = getClient(far_player))
						client->SetBlocksNotSent(modified_blocks2);
				}
			}

			delete event;
		}

		if (event_count >= 5) {
			infostream << "Server: MapEditEvents:" << std::endl;
			prof.print(infostream);
		} else if (event_count != 0) {
			verbosestream << "Server: MapEditEvents:" << std::endl;
			prof.print(verbosestream);
		}

		// Send all metadata updates
		if (!node_meta_updates.empty())
			sendMetadataChanged(node_meta_updates);
	}

	/*
		Trigger emerge thread
		Doing this every 2s is left over from old code, unclear if this is still needed.
	*/
	{
		float &counter = m_emergethread_trigger_timer;
		counter -= dtime;
		if (counter <= 0.0f) {
			counter = 2.0f;

			m_emerge->startThreads();
		}
	}

	// Save map, players and auth stuff
	{
		float &counter = m_savemap_timer;
		counter += dtime;
		static thread_local const float save_interval =
			g_settings->getFloat("server_map_save_interval");
		if (counter >= save_interval) {
			counter = 0.0;
			MutexAutoLock lock(m_env_mutex);

			ScopeProfiler sp(g_profiler, "Server: map saving (sum)");

			// Save ban file
			if (m_banmanager->isModified()) {
				m_banmanager->save();
			}

			// Save changed parts of map
			m_env->getMap().save(MOD_STATE_WRITE_NEEDED);

			// Save players
			m_env->saveLoadedPlayers();

			// Save environment metadata
			m_env->saveMeta();
		}
	}

	m_shutdown_state.tick(dtime, this);
}

void Server::Receive()
{
	NetworkPacket pkt;
	session_t peer_id;
	bool first = true;
	for (;;) {
		pkt.clear();
		peer_id = 0;
		try {
			/*
				In the first iteration *wait* for a packet, afterwards process
				all packets that are immediately available (no waiting).
			*/
			if (first) {
				m_con->Receive(&pkt);
				first = false;
			} else {
				if (!m_con->TryReceive(&pkt))
					return;
			}

			peer_id = pkt.getPeerId();
			m_packet_recv_counter->increment();
			ProcessData(&pkt);
			m_packet_recv_processed_counter->increment();
		} catch (const con::InvalidIncomingDataException &e) {
			infostream << "Server::Receive(): InvalidIncomingDataException: what()="
					<< e.what() << std::endl;
		} catch (const SerializationError &e) {
			infostream << "Server::Receive(): SerializationError: what()="
					<< e.what() << std::endl;
		} catch (const ClientStateError &e) {
			errorstream << "ProcessData: peer=" << peer_id << " what()="
					 << e.what() << std::endl;
			DenyAccess(peer_id, SERVER_ACCESSDENIED_UNEXPECTED_DATA);
		} catch (const con::PeerNotFoundException &e) {
			// Do nothing
		} catch (const con::NoIncomingDataException &e) {
			return;
		}
	}
}

PlayerSAO* Server::StageTwoClientInit(session_t peer_id)
{
	std::string playername;
	PlayerSAO *playersao = NULL;
	{
		ClientInterface::AutoLock clientlock(m_clients);
		RemoteClient* client = m_clients.lockedGetClientNoEx(peer_id, CS_InitDone);
		if (client) {
			playername = client->getName();
			playersao = emergePlayer(playername.c_str(), peer_id, client->net_proto_version);
		}
	}

	RemotePlayer *player = m_env->getPlayer(playername.c_str());

	// If failed, cancel
	if (!playersao || !player) {
		if (player && player->getPeerId() != PEER_ID_INEXISTENT) {
			actionstream << "Server: Failed to emerge player \"" << playername
					<< "\" (player allocated to an another client)" << std::endl;
			DenyAccess(peer_id, SERVER_ACCESSDENIED_ALREADY_CONNECTED);
		} else {
			errorstream << "Server: " << playername << ": Failed to emerge player"
					<< std::endl;
			DenyAccess(peer_id, SERVER_ACCESSDENIED_SERVER_FAIL);
		}
		return nullptr;
	}

	/*
		Send complete position information
	*/
	SendMovePlayer(peer_id);

	// Send privileges
	SendPlayerPrivileges(peer_id);

	// Send inventory formspec
	SendPlayerInventoryFormspec(peer_id);

	// Send inventory
	SendInventory(playersao, false);

	// Send HP
	SendPlayerHP(playersao, false);

	// Send death screen
	if (playersao->isDead())
		SendDeathscreen(peer_id, false, v3f(0,0,0));

	// Send Breath
	SendPlayerBreath(playersao);

	/*
		Update player list and print action
	*/
	{
		NetworkPacket notice_pkt(TOCLIENT_UPDATE_PLAYER_LIST, 0, PEER_ID_INEXISTENT);
		notice_pkt << (u8) PLAYER_LIST_ADD << (u16) 1 << std::string(player->getName());
		m_clients.sendToAll(&notice_pkt);
	}
	{
		std::string ip_str = getPeerAddress(player->getPeerId()).serializeString();
		const auto &names = m_clients.getPlayerNames();

		actionstream << player->getName() << " [" << ip_str << "] joins game. List of players: ";
		for (const std::string &name : names)
			actionstream << name << " ";
		actionstream << player->getName() << std::endl;
	}
	return playersao;
}

inline void Server::handleCommand(NetworkPacket *pkt)
{
	const ToServerCommandHandler &opHandle = toServerCommandTable[pkt->getCommand()];
	(this->*opHandle.handler)(pkt);
}

void Server::ProcessData(NetworkPacket *pkt)
{
	// Environment is locked first.
	MutexAutoLock envlock(m_env_mutex);

	ScopeProfiler sp(g_profiler, "Server: Process network packet (sum)");
	u32 peer_id = pkt->getPeerId();

	try {
		Address address = getPeerAddress(peer_id);
		std::string addr_s = address.serializeString();

		// FIXME: Isn't it a bit excessive to check this for every packet?
		if (m_banmanager->isIpBanned(addr_s)) {
			std::string ban_name = m_banmanager->getBanName(addr_s);
			infostream << "Server: A banned client tried to connect from "
					<< addr_s << "; banned name was " << ban_name << std::endl;
			DenyAccess(peer_id, SERVER_ACCESSDENIED_CUSTOM_STRING,
				"Your IP is banned. Banned name was " + ban_name);
			return;
		}
	} catch (con::PeerNotFoundException &e) {
		/*
		 * no peer for this packet found
		 * most common reason is peer timeout, e.g. peer didn't
		 * respond for some time, your server was overloaded or
		 * things like that.
		 */
		infostream << "Server::ProcessData(): Canceling: peer "
				<< peer_id << " not found" << std::endl;
		return;
	}

	try {
		ToServerCommand command = (ToServerCommand) pkt->getCommand();

		// Command must be handled into ToServerCommandHandler
		if (command >= TOSERVER_NUM_MSG_TYPES) {
			infostream << "Server: Ignoring unknown command "
					 << command << std::endl;
			return;
		}

		if (toServerCommandTable[command].state == TOSERVER_STATE_NOT_CONNECTED) {
			handleCommand(pkt);
			return;
		}

		u8 peer_ser_ver = getClient(peer_id, CS_InitDone)->serialization_version;

		if(peer_ser_ver == SER_FMT_VER_INVALID) {
			errorstream << "Server::ProcessData(): Cancelling: Peer"
					" serialization format invalid or not initialized."
					" Skipping incoming command=" << command << std::endl;
			return;
		}

		/* Handle commands related to client startup */
		if (toServerCommandTable[command].state == TOSERVER_STATE_STARTUP) {
			handleCommand(pkt);
			return;
		}

		if (m_clients.getClientState(peer_id) < CS_Active) {
			if (command == TOSERVER_PLAYERPOS) return;

			errorstream << "Got packet command: " << command << " for peer id "
					<< peer_id << " but client isn't active yet. Dropping packet "
					<< std::endl;
			return;
		}

		handleCommand(pkt);
	} catch (SendFailedException &e) {
		errorstream << "Server::ProcessData(): SendFailedException: "
				<< "what=" << e.what()
				<< std::endl;
	} catch (PacketError &e) {
		actionstream << "Server::ProcessData(): PacketError: "
				<< "what=" << e.what()
				<< std::endl;
	}
}

void Server::setTimeOfDay(u32 time)
{
	m_env->setTimeOfDay(time);
	m_time_of_day_send_timer = 0;
}

void Server::onMapEditEvent(const MapEditEvent &event)
{
	if (m_ignore_map_edit_events_area.contains(event.getArea()))
		return;

	m_unsent_map_edit_queue.push(new MapEditEvent(event));
}

void Server::SetBlocksNotSent(std::map<v3s16, MapBlock *>& block)
{
	std::vector<session_t> clients = m_clients.getClientIDs();
	ClientInterface::AutoLock clientlock(m_clients);
	// Set the modified blocks unsent for all the clients
	for (const session_t client_id : clients) {
			if (RemoteClient *client = m_clients.lockedGetClientNoEx(client_id))
				client->SetBlocksNotSent(block);
	}
}

void Server::peerAdded(con::Peer *peer)
{
	verbosestream<<"Server::peerAdded(): peer->id="
			<<peer->id<<std::endl;

	m_peer_change_queue.push(con::PeerChange(con::PEER_ADDED, peer->id, false));
}

void Server::deletingPeer(con::Peer *peer, bool timeout)
{
	verbosestream<<"Server::deletingPeer(): peer->id="
			<<peer->id<<", timeout="<<timeout<<std::endl;

	m_clients.event(peer->id, CSE_Disconnect);
	m_peer_change_queue.push(con::PeerChange(con::PEER_REMOVED, peer->id, timeout));
}

bool Server::getClientConInfo(session_t peer_id, con::rtt_stat_type type, float* retval)
{
	*retval = m_con->getPeerStat(peer_id,type);
	return *retval != -1;
}

bool Server::getClientInfo(session_t peer_id, ClientInfo &ret)
{
	ClientInterface::AutoLock clientlock(m_clients);
	RemoteClient* client = m_clients.lockedGetClientNoEx(peer_id, CS_Invalid);

	if (!client)
		return false;

	ret.state = client->getState();
	ret.addr = client->getAddress();
	ret.uptime = client->uptime();
	ret.ser_vers = client->serialization_version;
	ret.prot_vers = client->net_proto_version;

	ret.major = client->getMajor();
	ret.minor = client->getMinor();
	ret.patch = client->getPatch();
	ret.vers_string = client->getFullVer();

	ret.lang_code = client->getLangCode();

	return true;
}

void Server::handlePeerChanges()
{
	while(!m_peer_change_queue.empty())
	{
		con::PeerChange c = m_peer_change_queue.front();
		m_peer_change_queue.pop();

		verbosestream<<"Server: Handling peer change: "
				<<"id="<<c.peer_id<<", timeout="<<c.timeout
				<<std::endl;

		switch(c.type)
		{
		case con::PEER_ADDED:
			m_clients.CreateClient(c.peer_id);
			break;

		case con::PEER_REMOVED:
			DeleteClient(c.peer_id, c.timeout?CDR_TIMEOUT:CDR_LEAVE);
			break;

		default:
			FATAL_ERROR("Invalid peer change event received!");
			break;
		}
	}
}

void Server::printToConsoleOnly(const std::string &text)
{
	if (m_admin_chat) {
		m_admin_chat->outgoing_queue.push_back(
			new ChatEventChat("", utf8_to_wide(text)));
	} else {
		std::cout << text << std::endl;
	}
}

void Server::Send(NetworkPacket *pkt)
{
	Send(pkt->getPeerId(), pkt);
}

void Server::Send(session_t peer_id, NetworkPacket *pkt)
{
	m_clients.send(peer_id,
		clientCommandFactoryTable[pkt->getCommand()].channel,
		pkt,
		clientCommandFactoryTable[pkt->getCommand()].reliable);
}

void Server::SendMovement(session_t peer_id)
{
	std::ostringstream os(std::ios_base::binary);

	NetworkPacket pkt(TOCLIENT_MOVEMENT, 12 * sizeof(float), peer_id);

	pkt << g_settings->getFloat("movement_acceleration_default");
	pkt << g_settings->getFloat("movement_acceleration_air");
	pkt << g_settings->getFloat("movement_acceleration_fast");
	pkt << g_settings->getFloat("movement_speed_walk");
	pkt << g_settings->getFloat("movement_speed_crouch");
	pkt << g_settings->getFloat("movement_speed_fast");
	pkt << g_settings->getFloat("movement_speed_climb");
	pkt << g_settings->getFloat("movement_speed_jump");
	pkt << g_settings->getFloat("movement_liquid_fluidity");
	pkt << g_settings->getFloat("movement_liquid_fluidity_smooth");
	pkt << g_settings->getFloat("movement_liquid_sink");
	pkt << g_settings->getFloat("movement_gravity");

	Send(&pkt);
}

void Server::HandlePlayerHPChange(PlayerSAO *playersao, const PlayerHPChangeReason &reason)
{
	m_script->player_event(playersao, "health_changed");
	SendPlayerHP(playersao, reason.type != PlayerHPChangeReason::SET_HP_MAX);

	// Send to other clients
	playersao->sendPunchCommand();

	if (playersao->isDead())
		HandlePlayerDeath(playersao, reason);
}

void Server::SendPlayerHP(PlayerSAO *playersao, bool effect)
{
	SendHP(playersao->getPeerID(), playersao->getHP(), effect);
}

void Server::SendHP(session_t peer_id, u16 hp, bool effect)
{
	NetworkPacket pkt(TOCLIENT_HP, 3, peer_id);
	pkt << hp << effect;
	Send(&pkt);
}

void Server::SendBreath(session_t peer_id, u16 breath)
{
	NetworkPacket pkt(TOCLIENT_BREATH, 2, peer_id);
	pkt << (u16) breath;
	Send(&pkt);
}

void Server::SendAccessDenied(session_t peer_id, AccessDeniedCode reason,
		const std::string &custom_reason, bool reconnect)
{
	assert(reason < SERVER_ACCESSDENIED_MAX);

	NetworkPacket pkt(TOCLIENT_ACCESS_DENIED, 1, peer_id);
	pkt << (u8)reason;
	if (reason == SERVER_ACCESSDENIED_CUSTOM_STRING)
		pkt << custom_reason;
	else if (reason == SERVER_ACCESSDENIED_SHUTDOWN ||
			reason == SERVER_ACCESSDENIED_CRASH)
		pkt << custom_reason << (u8)reconnect;
	Send(&pkt);
}

void Server::SendDeathscreen(session_t peer_id, bool set_camera_point_target,
		v3f camera_point_target)
{
	NetworkPacket pkt(TOCLIENT_DEATHSCREEN, 1 + sizeof(v3f), peer_id);
	pkt << set_camera_point_target << camera_point_target;
	Send(&pkt);
}

void Server::SendItemDef(session_t peer_id,
		IItemDefManager *itemdef, u16 protocol_version)
{
	NetworkPacket pkt(TOCLIENT_ITEMDEF, 0, peer_id);

	/*
		u16 command
		u32 length of the next item
		zlib-compressed serialized ItemDefManager
	*/
	std::ostringstream tmp_os(std::ios::binary);
	itemdef->serialize(tmp_os, protocol_version);
	std::ostringstream tmp_os2(std::ios::binary);
	compressZlib(tmp_os.str(), tmp_os2);
	pkt.putLongString(tmp_os2.str());

	// Make data buffer
	verbosestream << "Server: Sending item definitions to id(" << peer_id
			<< "): size=" << pkt.getSize() << std::endl;

	Send(&pkt);
}

void Server::SendNodeDef(session_t peer_id,
	const NodeDefManager *nodedef, u16 protocol_version)
{
	NetworkPacket pkt(TOCLIENT_NODEDEF, 0, peer_id);

	/*
		u16 command
		u32 length of the next item
		zlib-compressed serialized NodeDefManager
	*/
	std::ostringstream tmp_os(std::ios::binary);
	nodedef->serialize(tmp_os, protocol_version);
	std::ostringstream tmp_os2(std::ios::binary);
	compressZlib(tmp_os.str(), tmp_os2);

	pkt.putLongString(tmp_os2.str());

	// Make data buffer
	verbosestream << "Server: Sending node definitions to id(" << peer_id
			<< "): size=" << pkt.getSize() << std::endl;

	Send(&pkt);
}

/*
	Non-static send methods
*/

void Server::SendInventory(PlayerSAO *sao, bool incremental)
{
	RemotePlayer *player = sao->getPlayer();

	// Do not send new format to old clients
	incremental &= player->protocol_version >= 38;

	UpdateCrafting(player);

	/*
		Serialize it
	*/

	NetworkPacket pkt(TOCLIENT_INVENTORY, 0, sao->getPeerID());

	std::ostringstream os(std::ios::binary);
	sao->getInventory()->serialize(os, incremental);
	sao->getInventory()->setModified(false);
	player->setModified(true);

	const std::string &s = os.str();
	pkt.putRawString(s.c_str(), s.size());
	Send(&pkt);
}

void Server::SendChatMessage(session_t peer_id, const ChatMessage &message)
{
	NetworkPacket pkt(TOCLIENT_CHAT_MESSAGE, 0, peer_id);
	u8 version = 1;
	u8 type = message.type;
	pkt << version << type << message.sender << message.message
		<< static_cast<u64>(message.timestamp);

	if (peer_id != PEER_ID_INEXISTENT) {
		RemotePlayer *player = m_env->getPlayer(peer_id);
		if (!player)
			return;

		Send(&pkt);
	} else {
		m_clients.sendToAll(&pkt);
	}
}

void Server::SendShowFormspecMessage(session_t peer_id, const std::string &formspec,
	const std::string &formname)
{
	NetworkPacket pkt(TOCLIENT_SHOW_FORMSPEC, 0, peer_id);
	if (formspec.empty()){
		//the client should close the formspec
		//but make sure there wasn't another one open in meantime
		const auto it = m_formspec_state_data.find(peer_id);
		if (it != m_formspec_state_data.end() && it->second == formname) {
			m_formspec_state_data.erase(peer_id);
		}
		pkt.putLongString("");
	} else {
		m_formspec_state_data[peer_id] = formname;
		pkt.putLongString(formspec);
	}
	pkt << formname;

	Send(&pkt);
}

// Spawns a particle on peer with peer_id
void Server::SendSpawnParticle(session_t peer_id, u16 protocol_version,
	const ParticleParameters &p)
{
	static thread_local const float radius =
			g_settings->getS16("max_block_send_distance") * MAP_BLOCKSIZE * BS;

	if (peer_id == PEER_ID_INEXISTENT) {
		std::vector<session_t> clients = m_clients.getClientIDs();
		const v3f pos = p.pos * BS;
		const float radius_sq = radius * radius;

		for (const session_t client_id : clients) {
			RemotePlayer *player = m_env->getPlayer(client_id);
			if (!player)
				continue;

			PlayerSAO *sao = player->getPlayerSAO();
			if (!sao)
				continue;

			// Do not send to distant clients
			if (sao->getBasePosition().getDistanceFromSQ(pos) > radius_sq)
				continue;

			SendSpawnParticle(client_id, player->protocol_version, p);
		}
		return;
	}
	assert(protocol_version != 0);

	NetworkPacket pkt(TOCLIENT_SPAWN_PARTICLE, 0, peer_id);

	{
		// NetworkPacket and iostreams are incompatible...
		std::ostringstream oss(std::ios_base::binary);
		p.serialize(oss, protocol_version);
		pkt.putRawString(oss.str());
	}

	Send(&pkt);
}

// Adds a ParticleSpawner on peer with peer_id
void Server::SendAddParticleSpawner(session_t peer_id, u16 protocol_version,
	const ParticleSpawnerParameters &p, u16 attached_id, u32 id)
{
	static thread_local const float radius =
			g_settings->getS16("max_block_send_distance") * MAP_BLOCKSIZE * BS;

	if (peer_id == PEER_ID_INEXISTENT) {
		std::vector<session_t> clients = m_clients.getClientIDs();
		const v3f pos = (p.minpos + p.maxpos) / 2.0f * BS;
		const float radius_sq = radius * radius;
		/* Don't send short-lived spawners to distant players.
		 * This could be replaced with proper tracking at some point. */
		const bool distance_check = !attached_id && p.time <= 1.0f;

		for (const session_t client_id : clients) {
			RemotePlayer *player = m_env->getPlayer(client_id);
			if (!player)
				continue;

			if (distance_check) {
				PlayerSAO *sao = player->getPlayerSAO();
				if (!sao)
					continue;
				if (sao->getBasePosition().getDistanceFromSQ(pos) > radius_sq)
					continue;
			}

			SendAddParticleSpawner(client_id, player->protocol_version,
				p, attached_id, id);
		}
		return;
	}
	assert(protocol_version != 0);

	NetworkPacket pkt(TOCLIENT_ADD_PARTICLESPAWNER, 100, peer_id);

	pkt << p.amount << p.time << p.minpos << p.maxpos << p.minvel
		<< p.maxvel << p.minacc << p.maxacc << p.minexptime << p.maxexptime
		<< p.minsize << p.maxsize << p.collisiondetection;

	pkt.putLongString(p.texture);

	pkt << id << p.vertical << p.collision_removal << attached_id;
	{
		std::ostringstream os(std::ios_base::binary);
		p.animation.serialize(os, protocol_version);
		pkt.putRawString(os.str());
	}
	pkt << p.glow << p.object_collision;
	pkt << p.node.param0 << p.node.param2 << p.node_tile;

	Send(&pkt);
}

void Server::SendDeleteParticleSpawner(session_t peer_id, u32 id)
{
	NetworkPacket pkt(TOCLIENT_DELETE_PARTICLESPAWNER, 4, peer_id);

	pkt << id;

	if (peer_id != PEER_ID_INEXISTENT)
		Send(&pkt);
	else
		m_clients.sendToAll(&pkt);

}

void Server::SendHUDAdd(session_t peer_id, u32 id, HudElement *form)
{
	NetworkPacket pkt(TOCLIENT_HUDADD, 0 , peer_id);

	pkt << id << (u8) form->type << form->pos << form->name << form->scale
			<< form->text << form->number << form->item << form->dir
			<< form->align << form->offset << form->world_pos << form->size
			<< form->z_index << form->text2 << form->style;

	Send(&pkt);
}

void Server::SendHUDRemove(session_t peer_id, u32 id)
{
	NetworkPacket pkt(TOCLIENT_HUDRM, 4, peer_id);
	pkt << id;
	Send(&pkt);
}

void Server::SendHUDChange(session_t peer_id, u32 id, HudElementStat stat, void *value)
{
	NetworkPacket pkt(TOCLIENT_HUDCHANGE, 0, peer_id);
	pkt << id << (u8) stat;

	switch (stat) {
		case HUD_STAT_POS:
		case HUD_STAT_SCALE:
		case HUD_STAT_ALIGN:
		case HUD_STAT_OFFSET:
			pkt << *(v2f *) value;
			break;
		case HUD_STAT_NAME:
		case HUD_STAT_TEXT:
		case HUD_STAT_TEXT2:
			pkt << *(std::string *) value;
			break;
		case HUD_STAT_WORLD_POS:
			pkt << *(v3f *) value;
			break;
		case HUD_STAT_SIZE:
			pkt << *(v2s32 *) value;
			break;
		default: // all other types
			pkt << *(u32 *) value;
			break;
	}

	Send(&pkt);
}

void Server::SendHUDSetFlags(session_t peer_id, u32 flags, u32 mask)
{
	NetworkPacket pkt(TOCLIENT_HUD_SET_FLAGS, 4 + 4, peer_id);

	flags &= ~(HUD_FLAG_HEALTHBAR_VISIBLE | HUD_FLAG_BREATHBAR_VISIBLE);

	pkt << flags << mask;

	Send(&pkt);
}

void Server::SendHUDSetParam(session_t peer_id, u16 param, const std::string &value)
{
	NetworkPacket pkt(TOCLIENT_HUD_SET_PARAM, 0, peer_id);
	pkt << param << value;
	Send(&pkt);
}

void Server::SendSetSky(session_t peer_id, const SkyboxParams &params)
{
	NetworkPacket pkt(TOCLIENT_SET_SKY, 0, peer_id);

	// Handle prior clients here
	if (m_clients.getProtocolVersion(peer_id) < 39) {
		pkt << params.bgcolor << params.type << (u16) params.textures.size();

		for (const std::string& texture : params.textures)
			pkt << texture;

		pkt << params.clouds;
	} else { // Handle current clients and future clients
		pkt << params.bgcolor << params.type
		<< params.clouds << params.fog_sun_tint
		<< params.fog_moon_tint << params.fog_tint_type;

		if (params.type == "skybox") {
			pkt << (u16) params.textures.size();
			for (const std::string &texture : params.textures)
				pkt << texture;
		} else if (params.type == "regular") {
			pkt << params.sky_color.day_sky << params.sky_color.day_horizon
				<< params.sky_color.dawn_sky << params.sky_color.dawn_horizon
				<< params.sky_color.night_sky << params.sky_color.night_horizon
				<< params.sky_color.indoors;
		}
	}

	Send(&pkt);
}

void Server::SendSetSun(session_t peer_id, const SunParams &params)
{
	NetworkPacket pkt(TOCLIENT_SET_SUN, 0, peer_id);
	pkt << params.visible << params.texture
		<< params.tonemap << params.sunrise
		<< params.sunrise_visible << params.scale;

	Send(&pkt);
}
void Server::SendSetMoon(session_t peer_id, const MoonParams &params)
{
	NetworkPacket pkt(TOCLIENT_SET_MOON, 0, peer_id);

	pkt << params.visible << params.texture
		<< params.tonemap << params.scale;

	Send(&pkt);
}
void Server::SendSetStars(session_t peer_id, const StarParams &params)
{
	NetworkPacket pkt(TOCLIENT_SET_STARS, 0, peer_id);

	pkt << params.visible << params.count
		<< params.starcolor << params.scale
		<< params.day_opacity;

	Send(&pkt);
}

void Server::SendCloudParams(session_t peer_id, const CloudParams &params)
{
	NetworkPacket pkt(TOCLIENT_CLOUD_PARAMS, 0, peer_id);
	pkt << params.density << params.color_bright << params.color_ambient
			<< params.height << params.thickness << params.speed;
	Send(&pkt);
}

void Server::SendOverrideDayNightRatio(session_t peer_id, bool do_override,
		float ratio)
{
	NetworkPacket pkt(TOCLIENT_OVERRIDE_DAY_NIGHT_RATIO,
			1 + 2, peer_id);

	pkt << do_override << (u16) (ratio * 65535);

	Send(&pkt);
}

void Server::SendSetLighting(session_t peer_id, const Lighting &lighting)
{
	NetworkPacket pkt(TOCLIENT_SET_LIGHTING,
			4, peer_id);
	
	pkt << lighting.shadow_intensity;

	Send(&pkt);
}

void Server::SendTimeOfDay(session_t peer_id, u16 time, f32 time_speed)
{
	NetworkPacket pkt(TOCLIENT_TIME_OF_DAY, 0, peer_id);
	pkt << time << time_speed;

	if (peer_id == PEER_ID_INEXISTENT) {
		m_clients.sendToAll(&pkt);
	}
	else {
		Send(&pkt);
	}
}

void Server::SendPlayerBreath(PlayerSAO *sao)
{
	assert(sao);

	m_script->player_event(sao, "breath_changed");
	SendBreath(sao->getPeerID(), sao->getBreath());
}

void Server::SendMovePlayer(session_t peer_id)
{
	RemotePlayer *player = m_env->getPlayer(peer_id);
	assert(player);
	PlayerSAO *sao = player->getPlayerSAO();
	assert(sao);

	// Send attachment updates instantly to the client prior updating position
	sao->sendOutdatedData();

	NetworkPacket pkt(TOCLIENT_MOVE_PLAYER, sizeof(v3f) + sizeof(f32) * 2, peer_id);
	pkt << sao->getBasePosition() << sao->getLookPitch() << sao->getRotation().Y;

	{
		v3f pos = sao->getBasePosition();
		verbosestream << "Server: Sending TOCLIENT_MOVE_PLAYER"
				<< " pos=(" << pos.X << "," << pos.Y << "," << pos.Z << ")"
				<< " pitch=" << sao->getLookPitch()
				<< " yaw=" << sao->getRotation().Y
				<< std::endl;
	}

	Send(&pkt);
}

void Server::SendPlayerFov(session_t peer_id)
{
	NetworkPacket pkt(TOCLIENT_FOV, 4 + 1 + 4, peer_id);

	PlayerFovSpec fov_spec = m_env->getPlayer(peer_id)->getFov();
	pkt << fov_spec.fov << fov_spec.is_multiplier << fov_spec.transition_time;

	Send(&pkt);
}

void Server::SendLocalPlayerAnimations(session_t peer_id, v2s32 animation_frames[4],
		f32 animation_speed)
{
	NetworkPacket pkt(TOCLIENT_LOCAL_PLAYER_ANIMATIONS, 0,
		peer_id);

	pkt << animation_frames[0] << animation_frames[1] << animation_frames[2]
			<< animation_frames[3] << animation_speed;

	Send(&pkt);
}

void Server::SendEyeOffset(session_t peer_id, v3f first, v3f third)
{
	NetworkPacket pkt(TOCLIENT_EYE_OFFSET, 0, peer_id);
	pkt << first << third;
	Send(&pkt);
}

void Server::SendPlayerPrivileges(session_t peer_id)
{
	RemotePlayer *player = m_env->getPlayer(peer_id);
	assert(player);
	if(player->getPeerId() == PEER_ID_INEXISTENT)
		return;

	std::set<std::string> privs;
	m_script->getAuth(player->getName(), NULL, &privs);

	NetworkPacket pkt(TOCLIENT_PRIVILEGES, 0, peer_id);
	pkt << (u16) privs.size();

	for (const std::string &priv : privs) {
		pkt << priv;
	}

	Send(&pkt);
}

void Server::SendPlayerInventoryFormspec(session_t peer_id)
{
	RemotePlayer *player = m_env->getPlayer(peer_id);
	assert(player);
	if (player->getPeerId() == PEER_ID_INEXISTENT)
		return;

	NetworkPacket pkt(TOCLIENT_INVENTORY_FORMSPEC, 0, peer_id);
	pkt.putLongString(player->inventory_formspec);

	Send(&pkt);
}

void Server::SendPlayerFormspecPrepend(session_t peer_id)
{
	RemotePlayer *player = m_env->getPlayer(peer_id);
	assert(player);
	if (player->getPeerId() == PEER_ID_INEXISTENT)
		return;

	NetworkPacket pkt(TOCLIENT_FORMSPEC_PREPEND, 0, peer_id);
	pkt << player->formspec_prepend;
	Send(&pkt);
}

void Server::SendActiveObjectRemoveAdd(RemoteClient *client, PlayerSAO *playersao)
{
	// Radius inside which objects are active
	static thread_local const s16 radius =
		g_settings->getS16("active_object_send_range_blocks") * MAP_BLOCKSIZE;

	// Radius inside which players are active
	static thread_local const bool is_transfer_limited =
		g_settings->exists("unlimited_player_transfer_distance") &&
		!g_settings->getBool("unlimited_player_transfer_distance");

	static thread_local const s16 player_transfer_dist =
		g_settings->getS16("player_transfer_distance") * MAP_BLOCKSIZE;

	s16 player_radius = player_transfer_dist == 0 && is_transfer_limited ?
		radius : player_transfer_dist;

	s16 my_radius = MYMIN(radius, playersao->getWantedRange() * MAP_BLOCKSIZE);
	if (my_radius <= 0)
		my_radius = radius;

	std::queue<u16> removed_objects, added_objects;
	m_env->getRemovedActiveObjects(playersao, my_radius, player_radius,
		client->m_known_objects, removed_objects);
	m_env->getAddedActiveObjects(playersao, my_radius, player_radius,
		client->m_known_objects, added_objects);

	int removed_count = removed_objects.size();
	int added_count   = added_objects.size();

	if (removed_objects.empty() && added_objects.empty())
		return;

	char buf[4];
	std::string data;

	// Handle removed objects
	writeU16((u8*)buf, removed_objects.size());
	data.append(buf, 2);
	while (!removed_objects.empty()) {
		// Get object
		u16 id = removed_objects.front();
		ServerActiveObject* obj = m_env->getActiveObject(id);

		// Add to data buffer for sending
		writeU16((u8*)buf, id);
		data.append(buf, 2);

		// Remove from known objects
		client->m_known_objects.erase(id);

		if (obj && obj->m_known_by_count > 0)
			obj->m_known_by_count--;

		removed_objects.pop();
	}

	// Handle added objects
	writeU16((u8*)buf, added_objects.size());
	data.append(buf, 2);
	while (!added_objects.empty()) {
		// Get object
		u16 id = added_objects.front();
		ServerActiveObject *obj = m_env->getActiveObject(id);
		added_objects.pop();

		if (!obj) {
			warningstream << FUNCTION_NAME << ": NULL object id="
				<< (int)id << std::endl;
			continue;
		}

		// Get object type
		u8 type = obj->getSendType();

		// Add to data buffer for sending
		writeU16((u8*)buf, id);
		data.append(buf, 2);
		writeU8((u8*)buf, type);
		data.append(buf, 1);

		data.append(serializeString32(
			obj->getClientInitializationData(client->net_proto_version)));

		// Add to known objects
		client->m_known_objects.insert(id);

		obj->m_known_by_count++;
	}

	NetworkPacket pkt(TOCLIENT_ACTIVE_OBJECT_REMOVE_ADD, data.size(), client->peer_id);
	pkt.putRawString(data.c_str(), data.size());
	Send(&pkt);

	verbosestream << "Server::SendActiveObjectRemoveAdd: "
		<< removed_count << " removed, " << added_count << " added, "
		<< "packet size is " << pkt.getSize() << std::endl;
}

void Server::SendActiveObjectMessages(session_t peer_id, const std::string &datas,
		bool reliable)
{
	NetworkPacket pkt(TOCLIENT_ACTIVE_OBJECT_MESSAGES,
			datas.size(), peer_id);

	pkt.putRawString(datas.c_str(), datas.size());

	m_clients.send(pkt.getPeerId(),
			reliable ? clientCommandFactoryTable[pkt.getCommand()].channel : 1,
			&pkt, reliable);
}

void Server::SendCSMRestrictionFlags(session_t peer_id)
{
	NetworkPacket pkt(TOCLIENT_CSM_RESTRICTION_FLAGS,
		sizeof(m_csm_restriction_flags) + sizeof(m_csm_restriction_noderange), peer_id);
	pkt << m_csm_restriction_flags << m_csm_restriction_noderange;
	Send(&pkt);
}

void Server::SendPlayerSpeed(session_t peer_id, const v3f &added_vel)
{
	NetworkPacket pkt(TOCLIENT_PLAYER_SPEED, 0, peer_id);
	pkt << added_vel;
	Send(&pkt);
}

inline s32 Server::nextSoundId()
{
	s32 ret = m_next_sound_id;
	if (m_next_sound_id == INT32_MAX)
		m_next_sound_id = 0; // signed overflow is undefined
	else
		m_next_sound_id++;
	return ret;
}

s32 Server::playSound(ServerPlayingSound &params, bool ephemeral)
{
	// Find out initial position of sound
	bool pos_exists = false;
	const v3f pos = params.getPos(m_env, &pos_exists);
	// If position is not found while it should be, cancel sound
	if(pos_exists != (params.type != SoundLocation::Local))
		return -1;

	// Filter destination clients
	std::vector<session_t> dst_clients;
	if (!params.to_player.empty()) {
		RemotePlayer *player = m_env->getPlayer(params.to_player.c_str());
		if(!player){
			infostream<<"Server::playSound: Player \""<<params.to_player
					<<"\" not found"<<std::endl;
			return -1;
		}
		if (player->getPeerId() == PEER_ID_INEXISTENT) {
			infostream<<"Server::playSound: Player \""<<params.to_player
					<<"\" not connected"<<std::endl;
			return -1;
		}
		dst_clients.push_back(player->getPeerId());
	} else {
		std::vector<session_t> clients = m_clients.getClientIDs();

		for (const session_t client_id : clients) {
			RemotePlayer *player = m_env->getPlayer(client_id);
			if (!player)
				continue;
			if (!params.exclude_player.empty() &&
					params.exclude_player == player->getName())
				continue;

			PlayerSAO *sao = player->getPlayerSAO();
			if (!sao)
				continue;

			if (pos_exists) {
				if(sao->getBasePosition().getDistanceFrom(pos) >
						params.max_hear_distance)
					continue;
			}
			dst_clients.push_back(client_id);
		}
	}

	if(dst_clients.empty())
		return -1;

	// old clients will still use this, so pick a reserved ID (-1)
	const s32 id = ephemeral ? -1 : nextSoundId();

	float gain = params.gain * params.spec.gain;
	NetworkPacket pkt(TOCLIENT_PLAY_SOUND, 0);
	pkt << id << params.spec.name << gain
			<< (u8) params.type << pos << params.object
			<< params.spec.loop << params.spec.fade << params.spec.pitch
			<< ephemeral;

	bool as_reliable = !ephemeral;

	for (const session_t peer_id : dst_clients) {
		if (!ephemeral)
			params.clients.insert(peer_id);
		m_clients.send(peer_id, 0, &pkt, as_reliable);
	}

	if (!ephemeral)
		m_playing_sounds[id] = std::move(params);
	return id;
}
void Server::stopSound(s32 handle)
{
	auto it = m_playing_sounds.find(handle);
	if (it == m_playing_sounds.end())
		return;

	ServerPlayingSound &psound = it->second;

	NetworkPacket pkt(TOCLIENT_STOP_SOUND, 4);
	pkt << handle;

	for (session_t peer_id : psound.clients) {
		// Send as reliable
		m_clients.send(peer_id, 0, &pkt, true);
	}

	// Remove sound reference
	m_playing_sounds.erase(it);
}

void Server::fadeSound(s32 handle, float step, float gain)
{
	auto it = m_playing_sounds.find(handle);
	if (it == m_playing_sounds.end())
		return;

	ServerPlayingSound &psound = it->second;
	psound.gain = gain; // destination gain

	NetworkPacket pkt(TOCLIENT_FADE_SOUND, 4);
	pkt << handle << step << gain;

	for (session_t peer_id : psound.clients) {
		// Send as reliable
		m_clients.send(peer_id, 0, &pkt, true);
	}

	// Remove sound reference
	if (gain <= 0 || psound.clients.empty())
		m_playing_sounds.erase(it);
}

void Server::sendRemoveNode(v3s16 p, std::unordered_set<u16> *far_players,
		float far_d_nodes)
{
	float maxd = far_d_nodes * BS;
	v3f p_f = intToFloat(p, BS);
	v3s16 block_pos = getNodeBlockPos(p);

	NetworkPacket pkt(TOCLIENT_REMOVENODE, 6);
	pkt << p;

	std::vector<session_t> clients = m_clients.getClientIDs();
	ClientInterface::AutoLock clientlock(m_clients);

	for (session_t client_id : clients) {
		RemoteClient *client = m_clients.lockedGetClientNoEx(client_id);
		if (!client)
			continue;

		RemotePlayer *player = m_env->getPlayer(client_id);
		PlayerSAO *sao = player ? player->getPlayerSAO() : nullptr;

		// If player is far away, only set modified blocks not sent
		if (!client->isBlockSent(block_pos) || (sao &&
				sao->getBasePosition().getDistanceFrom(p_f) > maxd)) {
			if (far_players)
				far_players->emplace(client_id);
			else
				client->SetBlockNotSent(block_pos);
			continue;
		}

		// Send as reliable
		m_clients.send(client_id, 0, &pkt, true);
	}
}

void Server::sendAddNode(v3s16 p, MapNode n, std::unordered_set<u16> *far_players,
		float far_d_nodes, bool remove_metadata)
{
	float maxd = far_d_nodes * BS;
	v3f p_f = intToFloat(p, BS);
	v3s16 block_pos = getNodeBlockPos(p);

	NetworkPacket pkt(TOCLIENT_ADDNODE, 6 + 2 + 1 + 1 + 1);
	pkt << p << n.param0 << n.param1 << n.param2
			<< (u8) (remove_metadata ? 0 : 1);

	std::vector<session_t> clients = m_clients.getClientIDs();
	ClientInterface::AutoLock clientlock(m_clients);

	for (session_t client_id : clients) {
		RemoteClient *client = m_clients.lockedGetClientNoEx(client_id);
		if (!client)
			continue;

		RemotePlayer *player = m_env->getPlayer(client_id);
		PlayerSAO *sao = player ? player->getPlayerSAO() : nullptr;

		// If player is far away, only set modified blocks not sent
		if (!client->isBlockSent(block_pos) || (sao &&
				sao->getBasePosition().getDistanceFrom(p_f) > maxd)) {
			if (far_players)
				far_players->emplace(client_id);
			else
				client->SetBlockNotSent(block_pos);
			continue;
		}

		// Send as reliable
		m_clients.send(client_id, 0, &pkt, true);
	}
}

void Server::sendMetadataChanged(const std::unordered_set<v3s16> &positions, float far_d_nodes)
{
	NodeMetadataList meta_updates_list(false);
	std::ostringstream os(std::ios::binary);

	std::vector<session_t> clients = m_clients.getClientIDs();
	ClientInterface::AutoLock clientlock(m_clients);

	for (session_t i : clients) {
		RemoteClient *client = m_clients.lockedGetClientNoEx(i);
		if (!client)
			continue;

		ServerActiveObject *player = getPlayerSAO(i);
		v3s16 player_pos;
		if (player)
			player_pos = floatToInt(player->getBasePosition(), BS);

		for (const v3s16 pos : positions) {
			NodeMetadata *meta = m_env->getMap().getNodeMetadata(pos);

			if (!meta)
				continue;

			v3s16 block_pos = getNodeBlockPos(pos);
			if (!client->isBlockSent(block_pos) ||
					player_pos.getDistanceFrom(pos) > far_d_nodes) {
				client->SetBlockNotSent(block_pos);
				continue;
			}

			// Add the change to send list
			meta_updates_list.set(pos, meta);
		}
		if (meta_updates_list.size() == 0)
			continue;

		// Send the meta changes
		os.str("");
		meta_updates_list.serialize(os, client->serialization_version, false, true, true);
		std::string raw = os.str();
		os.str("");
		compressZlib(raw, os);

		NetworkPacket pkt(TOCLIENT_NODEMETA_CHANGED, 0, i);
		pkt.putLongString(os.str());
		Send(&pkt);

		meta_updates_list.clear();
	}
}

void Server::SendBlockNoLock(session_t peer_id, MapBlock *block, u8 ver,
		u16 net_proto_version, SerializedBlockCache *cache)
{
	thread_local const int net_compression_level = rangelim(g_settings->getS16("map_compression_level_net"), -1, 9);
	std::string s, *sptr = nullptr;

	if (cache) {
		auto it = cache->find({block->getPos(), ver});
		if (it != cache->end())
			sptr = &it->second;
	}

	// Serialize the block in the right format
	if (!sptr) {
		std::ostringstream os(std::ios_base::binary);
		block->serialize(os, ver, false, net_compression_level);
		block->serializeNetworkSpecific(os);
		s = os.str();
		sptr = &s;
	}

	NetworkPacket pkt(TOCLIENT_BLOCKDATA, 2 + 2 + 2 + sptr->size(), peer_id);
	pkt << block->getPos();
	pkt.putRawString(*sptr);
	Send(&pkt);

	// Store away in cache
	if (cache && sptr == &s)
		(*cache)[{block->getPos(), ver}] = std::move(s);
}

void Server::SendBlocks(float dtime)
{
	MutexAutoLock envlock(m_env_mutex);
	//TODO check if one big lock could be faster then multiple small ones

	std::vector<PrioritySortedBlockTransfer> queue;

	u32 total_sending = 0, unique_clients = 0;

	{
		ScopeProfiler sp2(g_profiler, "Server::SendBlocks(): Collect list");

		std::vector<session_t> clients = m_clients.getClientIDs();

		ClientInterface::AutoLock clientlock(m_clients);
		for (const session_t client_id : clients) {
			RemoteClient *client = m_clients.lockedGetClientNoEx(client_id, CS_Active);

			if (!client)
				continue;

			total_sending += client->getSendingCount();
			const auto old_count = queue.size();
			client->GetNextBlocks(m_env,m_emerge, dtime, queue);
			unique_clients += queue.size() > old_count ? 1 : 0;
		}
	}

	// Sort.
	// Lowest priority number comes first.
	// Lowest is most important.
	std::sort(queue.begin(), queue.end());

	ClientInterface::AutoLock clientlock(m_clients);

	// Maximal total count calculation
	// The per-client block sends is halved with the maximal online users
	u32 max_blocks_to_send = (m_env->getPlayerCount() + g_settings->getU32("max_users")) *
		g_settings->getU32("max_simultaneous_block_sends_per_client") / 4 + 1;

	ScopeProfiler sp(g_profiler, "Server::SendBlocks(): Send to clients");
	Map &map = m_env->getMap();

	SerializedBlockCache cache, *cache_ptr = nullptr;
	if (unique_clients > 1) {
		// caching is pointless with a single client
		cache_ptr = &cache;
	}

	for (const PrioritySortedBlockTransfer &block_to_send : queue) {
		if (total_sending >= max_blocks_to_send)
			break;

		MapBlock *block = map.getBlockNoCreateNoEx(block_to_send.pos);
		if (!block)
			continue;

		RemoteClient *client = m_clients.lockedGetClientNoEx(block_to_send.peer_id,
				CS_Active);
		if (!client)
			continue;

		SendBlockNoLock(block_to_send.peer_id, block, client->serialization_version,
				client->net_proto_version, cache_ptr);

		client->SentBlock(block_to_send.pos);
		total_sending++;
	}
}

bool Server::SendBlock(session_t peer_id, const v3s16 &blockpos)
{
	MapBlock *block = m_env->getMap().getBlockNoCreateNoEx(blockpos);
	if (!block)
		return false;

	ClientInterface::AutoLock clientlock(m_clients);
	RemoteClient *client = m_clients.lockedGetClientNoEx(peer_id, CS_Active);
	if (!client || client->isBlockSent(blockpos))
		return false;
	SendBlockNoLock(peer_id, block, client->serialization_version,
			client->net_proto_version);

	return true;
}

bool Server::addMediaFile(const std::string &filename,
	const std::string &filepath, std::string *filedata_to,
	std::string *digest_to)
{
	// If name contains illegal characters, ignore the file
	if (!string_allowed(filename, TEXTURENAME_ALLOWED_CHARS)) {
		infostream << "Server: ignoring illegal file name: \""
				<< filename << "\"" << std::endl;
		return false;
	}
	// If name is not in a supported format, ignore it
	const char *supported_ext[] = {
		".png", ".jpg", ".bmp", ".tga",
		".ogg",
		".x", ".b3d", ".obj",
		// Custom translation file format
		".tr",
		NULL
	};
	if (removeStringEnd(filename, supported_ext).empty()) {
		infostream << "Server: ignoring unsupported file extension: \""
				<< filename << "\"" << std::endl;
		return false;
	}
	// Ok, attempt to load the file and add to cache

	// Read data
	std::string filedata;
	if (!fs::ReadFile(filepath, filedata)) {
		errorstream << "Server::addMediaFile(): Failed to open \""
					<< filename << "\" for reading" << std::endl;
		return false;
	}

	if (filedata.empty()) {
		errorstream << "Server::addMediaFile(): Empty file \""
				<< filepath << "\"" << std::endl;
		return false;
	}

	SHA1 sha1;
	sha1.addBytes(filedata.c_str(), filedata.length());

	unsigned char *digest = sha1.getDigest();
	std::string sha1_base64 = base64_encode(digest, 20);
	std::string sha1_hex = hex_encode((char*) digest, 20);
	if (digest_to)
		*digest_to = std::string((char*) digest, 20);
	free(digest);

	// Put in list
	m_media[filename] = MediaInfo(filepath, sha1_base64);
	verbosestream << "Server: " << sha1_hex << " is " << filename
			<< std::endl;

	if (filedata_to)
		*filedata_to = std::move(filedata);
	return true;
}

void Server::fillMediaCache()
{
	infostream << "Server: Calculating media file checksums" << std::endl;

	// Collect all media file paths
	std::vector<std::string> paths;

	// ordered in descending priority
	paths.push_back(getBuiltinLuaPath() + DIR_DELIM + "locale");
	fs::GetRecursiveDirs(paths, porting::path_user + DIR_DELIM + "textures" + DIR_DELIM + "server");
	fs::GetRecursiveDirs(paths, m_gamespec.path + DIR_DELIM + "textures");
	m_modmgr->getModsMediaPaths(paths);

	// Collect media file information from paths into cache
	for (const std::string &mediapath : paths) {
		std::vector<fs::DirListNode> dirlist = fs::GetDirListing(mediapath);
		for (const fs::DirListNode &dln : dirlist) {
			if (dln.dir) // Ignore dirs (already in paths)
				continue;

			const std::string &filename = dln.name;
			if (m_media.find(filename) != m_media.end()) // Do not override
				continue;

			std::string filepath = mediapath;
			filepath.append(DIR_DELIM).append(filename);
			addMediaFile(filename, filepath);
		}
	}

	infostream << "Server: " << m_media.size() << " media files collected" << std::endl;
}

void Server::sendMediaAnnouncement(session_t peer_id, const std::string &lang_code)
{
	// Make packet
	NetworkPacket pkt(TOCLIENT_ANNOUNCE_MEDIA, 0, peer_id);

	u16 media_sent = 0;
	std::string lang_suffix;
	lang_suffix.append(".").append(lang_code).append(".tr");
	for (const auto &i : m_media) {
		if (i.second.no_announce)
			continue;
		if (str_ends_with(i.first, ".tr") && !str_ends_with(i.first, lang_suffix))
			continue;
		media_sent++;
	}

	pkt << media_sent;

	for (const auto &i : m_media) {
		if (i.second.no_announce)
			continue;
		if (str_ends_with(i.first, ".tr") && !str_ends_with(i.first, lang_suffix))
			continue;
		pkt << i.first << i.second.sha1_digest;
	}

	pkt << g_settings->get("remote_media");
	Send(&pkt);

	verbosestream << "Server: Announcing files to id(" << peer_id
		<< "): count=" << media_sent << " size=" << pkt.getSize() << std::endl;
}

struct SendableMedia
{
	std::string name;
	std::string path;
	std::string data;

	SendableMedia(const std::string &name, const std::string &path,
			std::string &&data):
		name(name), path(path), data(std::move(data))
	{}
};

void Server::sendRequestedMedia(session_t peer_id,
		const std::vector<std::string> &tosend)
{
	verbosestream<<"Server::sendRequestedMedia(): "
			<<"Sending files to client"<<std::endl;

	/* Read files */

	// Put 5kB in one bunch (this is not accurate)
	u32 bytes_per_bunch = 5000;

	std::vector< std::vector<SendableMedia> > file_bunches;
	file_bunches.emplace_back();

	u32 file_size_bunch_total = 0;

	for (const std::string &name : tosend) {
		if (m_media.find(name) == m_media.end()) {
			errorstream<<"Server::sendRequestedMedia(): Client asked for "
					<<"unknown file \""<<(name)<<"\""<<std::endl;
			continue;
		}

		const auto &m = m_media[name];

		// Read data
		std::string data;
		if (!fs::ReadFile(m.path, data)) {
			errorstream << "Server::sendRequestedMedia(): Failed to read \""
					<< name << "\"" << std::endl;
			continue;
		}
		file_size_bunch_total += data.size();

		// Put in list
		file_bunches.back().emplace_back(name, m.path, std::move(data));

		// Start next bunch if got enough data
		if(file_size_bunch_total >= bytes_per_bunch) {
			file_bunches.emplace_back();
			file_size_bunch_total = 0;
		}

	}

	/* Create and send packets */

	u16 num_bunches = file_bunches.size();
	for (u16 i = 0; i < num_bunches; i++) {
		/*
			u16 command
			u16 total number of texture bunches
			u16 index of this bunch
			u32 number of files in this bunch
			for each file {
				u16 length of name
				string name
				u32 length of data
				data
			}
		*/

		NetworkPacket pkt(TOCLIENT_MEDIA, 4 + 0, peer_id);
		pkt << num_bunches << i << (u32) file_bunches[i].size();

		for (const SendableMedia &j : file_bunches[i]) {
			pkt << j.name;
			pkt.putLongString(j.data);
		}

		verbosestream << "Server::sendRequestedMedia(): bunch "
				<< i << "/" << num_bunches
				<< " files=" << file_bunches[i].size()
				<< " size="  << pkt.getSize() << std::endl;
		Send(&pkt);
	}
}

void Server::stepPendingDynMediaCallbacks(float dtime)
{
	MutexAutoLock lock(m_env_mutex);

	for (auto it = m_pending_dyn_media.begin(); it != m_pending_dyn_media.end();) {
		it->second.expiry_timer -= dtime;
		bool del = it->second.waiting_players.empty() || it->second.expiry_timer < 0;

		if (!del) {
			it++;
			continue;
		}

		const auto &name = it->second.filename;
		if (!name.empty()) {
			assert(m_media.count(name));
			// if no_announce isn't set we're definitely deleting the wrong file!
			sanity_check(m_media[name].no_announce);

			fs::DeleteSingleFileOrEmptyDirectory(m_media[name].path);
			m_media.erase(name);
		}
		getScriptIface()->freeDynamicMediaCallback(it->first);
		it = m_pending_dyn_media.erase(it);
	}
}

void Server::SendMinimapModes(session_t peer_id,
		std::vector<MinimapMode> &modes, size_t wanted_mode)
{
	RemotePlayer *player = m_env->getPlayer(peer_id);
	assert(player);
	if (player->getPeerId() == PEER_ID_INEXISTENT)
		return;

	NetworkPacket pkt(TOCLIENT_MINIMAP_MODES, 0, peer_id);
	pkt << (u16)modes.size() << (u16)wanted_mode;

	for (auto &mode : modes)
		pkt << (u16)mode.type << mode.label << mode.size << mode.texture << mode.scale;

	Send(&pkt);
}

void Server::sendDetachedInventory(Inventory *inventory, const std::string &name, session_t peer_id)
{
	NetworkPacket pkt(TOCLIENT_DETACHED_INVENTORY, 0, peer_id);
	pkt << name;

	if (!inventory) {
		pkt << false; // Remove inventory
	} else {
		pkt << true; // Update inventory

		// Serialization & NetworkPacket isn't a love story
		std::ostringstream os(std::ios_base::binary);
		inventory->serialize(os);
		inventory->setModified(false);

		const std::string &os_str = os.str();
		pkt << static_cast<u16>(os_str.size()); // HACK: to keep compatibility with 5.0.0 clients
		pkt.putRawString(os_str);
	}

	if (peer_id == PEER_ID_INEXISTENT)
		m_clients.sendToAll(&pkt);
	else
		Send(&pkt);
}

void Server::sendDetachedInventories(session_t peer_id, bool incremental)
{
	// Lookup player name, to filter detached inventories just after
	std::string peer_name;
	if (peer_id != PEER_ID_INEXISTENT) {
		peer_name = getClient(peer_id, CS_Created)->getName();
	}

	auto send_cb = [this, peer_id](const std::string &name, Inventory *inv) {
		sendDetachedInventory(inv, name, peer_id);
	};

	m_inventory_mgr->sendDetachedInventories(peer_name, incremental, send_cb);
}

/*
	Something random
*/

void Server::HandlePlayerDeath(PlayerSAO *playersao, const PlayerHPChangeReason &reason)
{
	infostream << "Server::DiePlayer(): Player "
			<< playersao->getPlayer()->getName()
			<< " dies" << std::endl;

	playersao->clearParentAttachment();

	// Trigger scripted stuff
	m_script->on_dieplayer(playersao, reason);

	SendDeathscreen(playersao->getPeerID(), false, v3f(0,0,0));
}

void Server::RespawnPlayer(session_t peer_id)
{
	PlayerSAO *playersao = getPlayerSAO(peer_id);
	assert(playersao);

	infostream << "Server::RespawnPlayer(): Player "
			<< playersao->getPlayer()->getName()
			<< " respawns" << std::endl;

	const auto *prop = playersao->accessObjectProperties();
	playersao->setHP(prop->hp_max,
			PlayerHPChangeReason(PlayerHPChangeReason::RESPAWN));
	playersao->setBreath(prop->breath_max);

	bool repositioned = m_script->on_respawnplayer(playersao);
	if (!repositioned) {
		// setPos will send the new position to client
		playersao->setPos(findSpawnPos());
	}
}


void Server::DenySudoAccess(session_t peer_id)
{
	NetworkPacket pkt(TOCLIENT_DENY_SUDO_MODE, 0, peer_id);
	Send(&pkt);
}


void Server::DenyAccess(session_t peer_id, AccessDeniedCode reason,
		const std::string &custom_reason, bool reconnect)
{
	SendAccessDenied(peer_id, reason, custom_reason, reconnect);
	m_clients.event(peer_id, CSE_SetDenied);
	DisconnectPeer(peer_id);
}

void Server::DisconnectPeer(session_t peer_id)
{
	m_modchannel_mgr->leaveAllChannels(peer_id);
	m_con->DisconnectPeer(peer_id);
}

void Server::acceptAuth(session_t peer_id, bool forSudoMode)
{
	if (!forSudoMode) {
		RemoteClient* client = getClient(peer_id, CS_Invalid);

		NetworkPacket resp_pkt(TOCLIENT_AUTH_ACCEPT, 1 + 6 + 8 + 4, peer_id);

		// Right now, the auth mechs don't change between login and sudo mode.
		u32 sudo_auth_mechs = client->allowed_auth_mechs;
		client->allowed_sudo_mechs = sudo_auth_mechs;

		resp_pkt << v3f(0,0,0) << (u64) m_env->getServerMap().getSeed()
				<< g_settings->getFloat("dedicated_server_step")
				<< sudo_auth_mechs;

		Send(&resp_pkt);
		m_clients.event(peer_id, CSE_AuthAccept);
	} else {
		NetworkPacket resp_pkt(TOCLIENT_ACCEPT_SUDO_MODE, 1 + 6 + 8 + 4, peer_id);

		// We only support SRP right now
		u32 sudo_auth_mechs = AUTH_MECHANISM_FIRST_SRP;

		resp_pkt << sudo_auth_mechs;
		Send(&resp_pkt);
		m_clients.event(peer_id, CSE_SudoSuccess);
	}
}

void Server::DeleteClient(session_t peer_id, ClientDeletionReason reason)
{
	std::wstring message;
	{
		/*
			Clear references to playing sounds
		*/
		for (std::unordered_map<s32, ServerPlayingSound>::iterator
				 i = m_playing_sounds.begin(); i != m_playing_sounds.end();) {
			ServerPlayingSound &psound = i->second;
			psound.clients.erase(peer_id);
			if (psound.clients.empty())
				m_playing_sounds.erase(i++);
			else
				++i;
		}

		// clear formspec info so the next client can't abuse the current state
		m_formspec_state_data.erase(peer_id);

		RemotePlayer *player = m_env->getPlayer(peer_id);

		/* Run scripts and remove from environment */
		if (player) {
			PlayerSAO *playersao = player->getPlayerSAO();
			assert(playersao);

			playersao->clearChildAttachments();
			playersao->clearParentAttachment();

			// inform connected clients
			const std::string &player_name = player->getName();
			NetworkPacket notice(TOCLIENT_UPDATE_PLAYER_LIST, 0, PEER_ID_INEXISTENT);
			// (u16) 1 + std::string represents a vector serialization representation
			notice << (u8) PLAYER_LIST_REMOVE  << (u16) 1 << player_name;
			m_clients.sendToAll(&notice);
			// run scripts
			m_script->on_leaveplayer(playersao, reason == CDR_TIMEOUT);

			playersao->disconnected();
		}

		/*
			Print out action
		*/
		{
			if (player && reason != CDR_DENY) {
				std::ostringstream os(std::ios_base::binary);
				std::vector<session_t> clients = m_clients.getClientIDs();

				for (const session_t client_id : clients) {
					// Get player
					RemotePlayer *player = m_env->getPlayer(client_id);
					if (!player)
						continue;

					// Get name of player
					os << player->getName() << " ";
				}

				std::string name = player->getName();
				actionstream << name << " "
						<< (reason == CDR_TIMEOUT ? "times out." : "leaves game.")
						<< " List of players: " << os.str() << std::endl;
				if (m_admin_chat)
					m_admin_chat->outgoing_queue.push_back(
						new ChatEventNick(CET_NICK_REMOVE, name));
			}
		}
		{
			MutexAutoLock env_lock(m_env_mutex);
			m_clients.DeleteClient(peer_id);
		}
	}

	// Send leave chat message to all remaining clients
	if (!message.empty()) {
		SendChatMessage(PEER_ID_INEXISTENT,
				ChatMessage(CHATMESSAGE_TYPE_ANNOUNCE, message));
	}
}

void Server::UpdateCrafting(RemotePlayer *player)
{
	InventoryList *clist = player->inventory.getList("craft");
	if (!clist || clist->getSize() == 0)
		return;

	if (!clist->checkModified())
		return;

	// Get a preview for crafting
	ItemStack preview;
	InventoryLocation loc;
	loc.setPlayer(player->getName());
	std::vector<ItemStack> output_replacements;
	getCraftingResult(&player->inventory, preview, output_replacements, false, this);
	m_env->getScriptIface()->item_CraftPredict(preview, player->getPlayerSAO(),
			clist, loc);

	InventoryList *plist = player->inventory.getList("craftpreview");
	if (plist && plist->getSize() >= 1) {
		// Put the new preview in
		plist->changeItem(0, preview);
	}
}

void Server::handleChatInterfaceEvent(ChatEvent *evt)
{
	if (evt->type == CET_NICK_ADD) {
		// The terminal informed us of its nick choice
		m_admin_nick = ((ChatEventNick *)evt)->nick;
		if (!m_script->getAuth(m_admin_nick, NULL, NULL)) {
			errorstream << "You haven't set up an account." << std::endl
				<< "Please log in using the client as '"
				<< m_admin_nick << "' with a secure password." << std::endl
				<< "Until then, you can't execute admin tasks via the console," << std::endl
				<< "and everybody can claim the user account instead of you," << std::endl
				<< "giving them full control over this server." << std::endl;
		}
	} else {
		assert(evt->type == CET_CHAT);
		handleAdminChat((ChatEventChat *)evt);
	}
}

std::wstring Server::handleChat(const std::string &name,
	std::wstring wmessage, bool check_shout_priv, RemotePlayer *player)
{
	// If something goes wrong, this player is to blame
	RollbackScopeActor rollback_scope(m_rollback,
			std::string("player:") + name);

	if (g_settings->getBool("strip_color_codes"))
		wmessage = unescape_enriched(wmessage);

	if (player) {
		switch (player->canSendChatMessage()) {
		case RPLAYER_CHATRESULT_FLOODING: {
			std::wstringstream ws;
			ws << L"You cannot send more messages. You are limited to "
					<< g_settings->getFloat("chat_message_limit_per_10sec")
					<< L" messages per 10 seconds.";
			return ws.str();
		}
		case RPLAYER_CHATRESULT_KICK:
			DenyAccess(player->getPeerId(), SERVER_ACCESSDENIED_CUSTOM_STRING,
				"You have been kicked due to message flooding.");
			return L"";
		case RPLAYER_CHATRESULT_OK:
			break;
		default:
			FATAL_ERROR("Unhandled chat filtering result found.");
		}
	}

	if (m_max_chatmessage_length > 0
			&& wmessage.length() > m_max_chatmessage_length) {
		return L"Your message exceed the maximum chat message limit set on the server. "
				L"It was refused. Send a shorter message";
	}

	auto message = trim(wide_to_utf8(wmessage));
	if (message.empty())
		return L"";

	if (message.find_first_of("\n\r") != std::wstring::npos) {
		return L"Newlines are not permitted in chat messages";
	}

	// Run script hook, exit if script ate the chat message
	if (m_script->on_chat_message(name, message))
		return L"";

	// Line to send
	std::wstring line;
	// Whether to send line to the player that sent the message, or to all players
	bool broadcast_line = true;

	if (check_shout_priv && !checkPriv(name, "shout")) {
		line += L"-!- You don't have permission to shout.";
		broadcast_line = false;
	} else {
		/*
			Workaround for fixing chat on Android. Lua doesn't handle
			the Cyrillic alphabet and some characters on older Android devices
		*/
#ifdef __ANDROID__
		line += L"<" + utf8_to_wide(name) + L"> " + wmessage;
#else
		line += utf8_to_wide(m_script->formatChatMessage(name,
				wide_to_utf8(wmessage)));
#endif
	}

	/*
		Tell calling method to send the message to sender
	*/
	if (!broadcast_line)
		return line;

	/*
		Send the message to others
	*/
	actionstream << "CHAT: " << wide_to_utf8(unescape_enriched(line)) << std::endl;

	ChatMessage chatmsg(line);

	std::vector<session_t> clients = m_clients.getClientIDs();
	for (u16 cid : clients)
		SendChatMessage(cid, chatmsg);

	return L"";
}

void Server::handleAdminChat(const ChatEventChat *evt)
{
	std::string name = evt->nick;
	std::wstring wmessage = evt->evt_msg;

	std::wstring answer = handleChat(name, wmessage);

	// If asked to send answer to sender
	if (!answer.empty()) {
		m_admin_chat->outgoing_queue.push_back(new ChatEventChat("", answer));
	}
}

RemoteClient *Server::getClient(session_t peer_id, ClientState state_min)
{
	RemoteClient *client = getClientNoEx(peer_id,state_min);
	if(!client)
		throw ClientNotFoundException("Client not found");

	return client;
}
RemoteClient *Server::getClientNoEx(session_t peer_id, ClientState state_min)
{
	return m_clients.getClientNoEx(peer_id, state_min);
}

std::string Server::getPlayerName(session_t peer_id)
{
	RemotePlayer *player = m_env->getPlayer(peer_id);
	if (!player)
		return "[id="+itos(peer_id)+"]";
	return player->getName();
}

PlayerSAO *Server::getPlayerSAO(session_t peer_id)
{
	RemotePlayer *player = m_env->getPlayer(peer_id);
	if (!player)
		return NULL;
	return player->getPlayerSAO();
}

std::string Server::getStatusString()
{
	std::ostringstream os(std::ios_base::binary);
	os << "# Server: ";
	// Version
	os << "version: " << g_version_string;
	// Game
	os << " | game: " << (m_gamespec.title.empty() ? m_gamespec.id : m_gamespec.title);
	// Uptime
	os << " | uptime: " << duration_to_string((int) m_uptime_counter->get());
	// Max lag estimate
	os << " | max lag: " << std::setprecision(3);
	os << (m_env ? m_env->getMaxLagEstimate() : 0) << "s";

	// Information about clients
	bool first = true;
	os << " | clients: ";
	if (m_env) {
		std::vector<session_t> clients = m_clients.getClientIDs();
		for (session_t client_id : clients) {
			RemotePlayer *player = m_env->getPlayer(client_id);

			// Get name of player
			const char *name = player ? player->getName() : "<unknown>";

			// Add name to information string
			if (!first)
				os << ", ";
			else
				first = false;
			os << name;
		}
	}

	if (m_env && !((ServerMap*)(&m_env->getMap()))->isSavingEnabled())
		os << std::endl << "# Server: " << " WARNING: Map saving is disabled.";

	if (!g_settings->get("motd").empty())
		os << std::endl << "# Server: " << g_settings->get("motd");

	return os.str();
}

std::set<std::string> Server::getPlayerEffectivePrivs(const std::string &name)
{
	std::set<std::string> privs;
	m_script->getAuth(name, NULL, &privs);
	return privs;
}

bool Server::checkPriv(const std::string &name, const std::string &priv)
{
	std::set<std::string> privs = getPlayerEffectivePrivs(name);
	return (privs.count(priv) != 0);
}

void Server::reportPrivsModified(const std::string &name)
{
	if (name.empty()) {
		std::vector<session_t> clients = m_clients.getClientIDs();
		for (const session_t client_id : clients) {
			RemotePlayer *player = m_env->getPlayer(client_id);
			reportPrivsModified(player->getName());
		}
	} else {
		RemotePlayer *player = m_env->getPlayer(name.c_str());
		if (!player)
			return;
		SendPlayerPrivileges(player->getPeerId());
		PlayerSAO *sao = player->getPlayerSAO();
		if(!sao)
			return;
		sao->updatePrivileges(
				getPlayerEffectivePrivs(name),
				isSingleplayer());
	}
}

void Server::reportInventoryFormspecModified(const std::string &name)
{
	RemotePlayer *player = m_env->getPlayer(name.c_str());
	if (!player)
		return;
	SendPlayerInventoryFormspec(player->getPeerId());
}

void Server::reportFormspecPrependModified(const std::string &name)
{
	RemotePlayer *player = m_env->getPlayer(name.c_str());
	if (!player)
		return;
	SendPlayerFormspecPrepend(player->getPeerId());
}

void Server::setIpBanned(const std::string &ip, const std::string &name)
{
	m_banmanager->add(ip, name);
}

void Server::unsetIpBanned(const std::string &ip_or_name)
{
	m_banmanager->remove(ip_or_name);
}

std::string Server::getBanDescription(const std::string &ip_or_name)
{
	return m_banmanager->getBanDescription(ip_or_name);
}

void Server::notifyPlayer(const char *name, const std::wstring &msg)
{
	// m_env will be NULL if the server is initializing
	if (!m_env)
		return;

	if (m_admin_nick == name && !m_admin_nick.empty()) {
		m_admin_chat->outgoing_queue.push_back(new ChatEventChat("", msg));
	}

	RemotePlayer *player = m_env->getPlayer(name);
	if (!player) {
		return;
	}

	if (player->getPeerId() == PEER_ID_INEXISTENT)
		return;

	SendChatMessage(player->getPeerId(), ChatMessage(msg));
}

bool Server::showFormspec(const char *playername, const std::string &formspec,
	const std::string &formname)
{
	// m_env will be NULL if the server is initializing
	if (!m_env)
		return false;

	RemotePlayer *player = m_env->getPlayer(playername);
	if (!player)
		return false;

	SendShowFormspecMessage(player->getPeerId(), formspec, formname);
	return true;
}

u32 Server::hudAdd(RemotePlayer *player, HudElement *form)
{
	if (!player)
		return -1;

	u32 id = player->addHud(form);

	SendHUDAdd(player->getPeerId(), id, form);

	return id;
}

bool Server::hudRemove(RemotePlayer *player, u32 id) {
	if (!player)
		return false;

	HudElement* todel = player->removeHud(id);

	if (!todel)
		return false;

	delete todel;

	SendHUDRemove(player->getPeerId(), id);
	return true;
}

bool Server::hudChange(RemotePlayer *player, u32 id, HudElementStat stat, void *data)
{
	if (!player)
		return false;

	SendHUDChange(player->getPeerId(), id, stat, data);
	return true;
}

bool Server::hudSetFlags(RemotePlayer *player, u32 flags, u32 mask)
{
	if (!player)
		return false;

	u32 new_hud_flags = (player->hud_flags & ~mask) | flags;
	if (new_hud_flags == player->hud_flags) // no change
		return true;
	
	SendHUDSetFlags(player->getPeerId(), flags, mask);
	player->hud_flags = new_hud_flags;

	PlayerSAO* playersao = player->getPlayerSAO();

	if (!playersao)
		return false;

	m_script->player_event(playersao, "hud_changed");
	return true;
}

bool Server::hudSetHotbarItemcount(RemotePlayer *player, s32 hotbar_itemcount)
{
	if (!player)
		return false;

	if (hotbar_itemcount <= 0 || hotbar_itemcount > HUD_HOTBAR_ITEMCOUNT_MAX)
		return false;

	player->setHotbarItemcount(hotbar_itemcount);
	std::ostringstream os(std::ios::binary);
	writeS32(os, hotbar_itemcount);
	SendHUDSetParam(player->getPeerId(), HUD_PARAM_HOTBAR_ITEMCOUNT, os.str());
	return true;
}

void Server::hudSetHotbarImage(RemotePlayer *player, const std::string &name)
{
	if (!player)
		return;

	player->setHotbarImage(name);
	SendHUDSetParam(player->getPeerId(), HUD_PARAM_HOTBAR_IMAGE, name);
}

void Server::hudSetHotbarSelectedImage(RemotePlayer *player, const std::string &name)
{
	if (!player)
		return;

	player->setHotbarSelectedImage(name);
	SendHUDSetParam(player->getPeerId(), HUD_PARAM_HOTBAR_SELECTED_IMAGE, name);
}

Address Server::getPeerAddress(session_t peer_id)
{
	// Note that this is only set after Init was received in Server::handleCommand_Init
	return getClient(peer_id, CS_Invalid)->getAddress();
}

void Server::setLocalPlayerAnimations(RemotePlayer *player,
		v2s32 animation_frames[4], f32 frame_speed)
{
	sanity_check(player);
	player->setLocalAnimations(animation_frames, frame_speed);
	SendLocalPlayerAnimations(player->getPeerId(), animation_frames, frame_speed);
}

void Server::setPlayerEyeOffset(RemotePlayer *player, const v3f &first, const v3f &third)
{
	sanity_check(player);
	player->eye_offset_first = first;
	player->eye_offset_third = third;
	SendEyeOffset(player->getPeerId(), first, third);
}

void Server::setSky(RemotePlayer *player, const SkyboxParams &params)
{
	sanity_check(player);
	player->setSky(params);
	SendSetSky(player->getPeerId(), params);
}

void Server::setSun(RemotePlayer *player, const SunParams &params)
{
	sanity_check(player);
	player->setSun(params);
	SendSetSun(player->getPeerId(), params);
}

void Server::setMoon(RemotePlayer *player, const MoonParams &params)
{
	sanity_check(player);
	player->setMoon(params);
	SendSetMoon(player->getPeerId(), params);
}

void Server::setStars(RemotePlayer *player, const StarParams &params)
{
	sanity_check(player);
	player->setStars(params);
	SendSetStars(player->getPeerId(), params);
}

void Server::setClouds(RemotePlayer *player, const CloudParams &params)
{
	sanity_check(player);
	player->setCloudParams(params);
	SendCloudParams(player->getPeerId(), params);
}

void Server::overrideDayNightRatio(RemotePlayer *player, bool do_override,
	float ratio)
{
	sanity_check(player);
	player->overrideDayNightRatio(do_override, ratio);
	SendOverrideDayNightRatio(player->getPeerId(), do_override, ratio);
}

void Server::setLighting(RemotePlayer *player, const Lighting &lighting)
{
	sanity_check(player);
	player->setLighting(lighting);
	SendSetLighting(player->getPeerId(), lighting);
}

void Server::notifyPlayers(const std::wstring &msg)
{
	SendChatMessage(PEER_ID_INEXISTENT, ChatMessage(msg));
}

void Server::spawnParticle(const std::string &playername,
	const ParticleParameters &p)
{
	// m_env will be NULL if the server is initializing
	if (!m_env)
		return;

	session_t peer_id = PEER_ID_INEXISTENT;
	u16 proto_ver = 0;
	if (!playername.empty()) {
		RemotePlayer *player = m_env->getPlayer(playername.c_str());
		if (!player)
			return;
		peer_id = player->getPeerId();
		proto_ver = player->protocol_version;
	}

	SendSpawnParticle(peer_id, proto_ver, p);
}

u32 Server::addParticleSpawner(const ParticleSpawnerParameters &p,
	ServerActiveObject *attached, const std::string &playername)
{
	// m_env will be NULL if the server is initializing
	if (!m_env)
		return -1;

	session_t peer_id = PEER_ID_INEXISTENT;
	u16 proto_ver = 0;
	if (!playername.empty()) {
		RemotePlayer *player = m_env->getPlayer(playername.c_str());
		if (!player)
			return -1;
		peer_id = player->getPeerId();
		proto_ver = player->protocol_version;
	}

	u16 attached_id = attached ? attached->getId() : 0;

	u32 id;
	if (attached_id == 0)
		id = m_env->addParticleSpawner(p.time);
	else
		id = m_env->addParticleSpawner(p.time, attached_id);

	SendAddParticleSpawner(peer_id, proto_ver, p, attached_id, id);
	return id;
}

void Server::deleteParticleSpawner(const std::string &playername, u32 id)
{
	// m_env will be NULL if the server is initializing
	if (!m_env)
		throw ServerError("Can't delete particle spawners during initialisation!");

	session_t peer_id = PEER_ID_INEXISTENT;
	if (!playername.empty()) {
		RemotePlayer *player = m_env->getPlayer(playername.c_str());
		if (!player)
			return;
		peer_id = player->getPeerId();
	}

	m_env->deleteParticleSpawner(id);
	SendDeleteParticleSpawner(peer_id, id);
}

bool Server::dynamicAddMedia(std::string filepath,
	const u32 token, const std::string &to_player, bool ephemeral)
{
	std::string filename = fs::GetFilenameFromPath(filepath.c_str());
	auto it = m_media.find(filename);
	if (it != m_media.end()) {
		// Allow the same path to be "added" again in certain conditions
		if (ephemeral || it->second.path != filepath) {
			errorstream << "Server::dynamicAddMedia(): file \"" << filename
				<< "\" already exists in media cache" << std::endl;
			return false;
		}
	}

	// Load the file and add it to our media cache
	std::string filedata, raw_hash;
	bool ok = addMediaFile(filename, filepath, &filedata, &raw_hash);
	if (!ok)
		return false;

	if (ephemeral) {
		// Create a copy of the file and swap out the path, this removes the
		// requirement that mods keep the file accessible at the original path.
		filepath = fs::CreateTempFile();
		bool ok = ([&] () -> bool {
			if (filepath.empty())
				return false;
			std::ofstream os(filepath.c_str(), std::ios::binary);
			if (!os.good())
				return false;
			os << filedata;
			os.close();
			return !os.fail();
		})();
		if (!ok) {
			errorstream << "Server: failed to create a copy of media file "
				<< "\"" << filename << "\"" << std::endl;
			m_media.erase(filename);
			return false;
		}
		verbosestream << "Server: \"" << filename << "\" temporarily copied to "
			<< filepath << std::endl;

		m_media[filename].path = filepath;
		m_media[filename].no_announce = true;
		// stepPendingDynMediaCallbacks will clean this up later.
	} else if (!to_player.empty()) {
		m_media[filename].no_announce = true;
	}

	// Push file to existing clients
	NetworkPacket pkt(TOCLIENT_MEDIA_PUSH, 0);
	pkt << raw_hash << filename << (bool)ephemeral;

	NetworkPacket legacy_pkt = pkt;

	// Newer clients get asked to fetch the file (asynchronous)
	pkt << token;
	// Older clients have an awful hack that just throws the data at them
	legacy_pkt.putLongString(filedata);

	std::unordered_set<session_t> delivered, waiting;
	{
		ClientInterface::AutoLock clientlock(m_clients);
		for (auto &pair : m_clients.getClientList()) {
			if (pair.second->getState() == CS_DefinitionsSent && !ephemeral) {
				/*
					If a client is in the DefinitionsSent state it is too late to
					transfer the file via sendMediaAnnouncement() but at the same
					time the client cannot accept a media push yet.
					Short of artificially delaying the joining process there is no
					way for the server to resolve this so we (currently) opt not to.
				*/
				warningstream << "The media \"" << filename << "\" (dynamic) could "
					"not be delivered to " << pair.second->getName()
					<< " due to a race condition." << std::endl;
				continue;
			}
			if (pair.second->getState() < CS_Active)
				continue;

			const auto proto_ver = pair.second->net_proto_version;
			if (proto_ver < 39)
				continue;

			const session_t peer_id = pair.second->peer_id;
			if (!to_player.empty() && getPlayerName(peer_id) != to_player)
				continue;

			if (proto_ver < 40) {
				delivered.emplace(peer_id);
				/*
					The network layer only guarantees ordered delivery inside a channel.
					Since the very next packet could be one that uses the media, we have
					to push the media over ALL channels to ensure it is processed before
					it is used. In practice this means channels 1 and 0.
				*/
				m_clients.send(peer_id, 1, &legacy_pkt, true);
				m_clients.send(peer_id, 0, &legacy_pkt, true);
			} else {
				waiting.emplace(peer_id);
				Send(peer_id, &pkt);
			}
		}
	}

	// Run callback for players that already had the file delivered (legacy-only)
	for (session_t peer_id : delivered) {
		if (auto player = m_env->getPlayer(peer_id))
			getScriptIface()->on_dynamic_media_added(token, player->getName());
	}

	// Save all others in our pending state
	auto &state = m_pending_dyn_media[token];
	state.waiting_players = std::move(waiting);
	// regardless of success throw away the callback after a while
	state.expiry_timer = 60.0f;
	if (ephemeral)
		state.filename = filename;

	return true;
}

// actions: time-reversed list
// Return value: success/failure
bool Server::rollbackRevertActions(const std::list<RollbackAction> &actions,
		std::list<std::string> *log)
{
	infostream<<"Server::rollbackRevertActions(len="<<actions.size()<<")"<<std::endl;
	ServerMap *map = (ServerMap*)(&m_env->getMap());

	// Fail if no actions to handle
	if (actions.empty()) {
		assert(log);
		log->push_back("Nothing to do.");
		return false;
	}

	int num_tried = 0;
	int num_failed = 0;

	for (const RollbackAction &action : actions) {
		num_tried++;
		bool success = action.applyRevert(map, m_inventory_mgr.get(), this);
		if(!success){
			num_failed++;
			std::ostringstream os;
			os<<"Revert of step ("<<num_tried<<") "<<action.toString()<<" failed";
			infostream<<"Map::rollbackRevertActions(): "<<os.str()<<std::endl;
			if (log)
				log->push_back(os.str());
		}else{
			std::ostringstream os;
			os<<"Successfully reverted step ("<<num_tried<<") "<<action.toString();
			infostream<<"Map::rollbackRevertActions(): "<<os.str()<<std::endl;
			if (log)
				log->push_back(os.str());
		}
	}

	infostream<<"Map::rollbackRevertActions(): "<<num_failed<<"/"<<num_tried
			<<" failed"<<std::endl;

	// Call it done if less than half failed
	return num_failed <= num_tried/2;
}

// IGameDef interface
// Under envlock
IItemDefManager *Server::getItemDefManager()
{
	return m_itemdef;
}

const NodeDefManager *Server::getNodeDefManager()
{
	return m_nodedef;
}

ICraftDefManager *Server::getCraftDefManager()
{
	return m_craftdef;
}

u16 Server::allocateUnknownNodeId(const std::string &name)
{
	return m_nodedef->allocateDummy(name);
}

IWritableItemDefManager *Server::getWritableItemDefManager()
{
	return m_itemdef;
}

NodeDefManager *Server::getWritableNodeDefManager()
{
	return m_nodedef;
}

IWritableCraftDefManager *Server::getWritableCraftDefManager()
{
	return m_craftdef;
}

const std::vector<ModSpec> & Server::getMods() const
{
	return m_modmgr->getMods();
}

const ModSpec *Server::getModSpec(const std::string &modname) const
{
	return m_modmgr->getModSpec(modname);
}

std::string Server::getBuiltinLuaPath()
{
	return porting::path_share + DIR_DELIM + "builtin";
}

v3f Server::findSpawnPos()
{
	ServerMap &map = m_env->getServerMap();
	v3f nodeposf;
	if (g_settings->getV3FNoEx("static_spawnpoint", nodeposf))
		return nodeposf * BS;

	bool is_good = false;
	// Limit spawn range to mapgen edges (determined by 'mapgen_limit')
	s32 range_max = map.getMapgenParams()->getSpawnRangeMax();

	// Try to find a good place a few times
	for (s32 i = 0; i < 4000 && !is_good; i++) {
		s32 range = MYMIN(1 + i, range_max);
		// We're going to try to throw the player to this position
		v2s16 nodepos2d = v2s16(
			-range + (myrand() % (range * 2)),
			-range + (myrand() % (range * 2)));
		// Get spawn level at point
		s16 spawn_level = m_emerge->getSpawnLevelAtPoint(nodepos2d);
		// Continue if MAX_MAP_GENERATION_LIMIT was returned by the mapgen to
		// signify an unsuitable spawn position, or if outside limits.
		if (spawn_level >= MAX_MAP_GENERATION_LIMIT ||
				spawn_level <= -MAX_MAP_GENERATION_LIMIT)
			continue;

		v3s16 nodepos(nodepos2d.X, spawn_level, nodepos2d.Y);
		// Consecutive empty nodes
		s32 air_count = 0;

		// Search upwards from 'spawn level' for 2 consecutive empty nodes, to
		// avoid obstructions in already-generated mapblocks.
		// In ungenerated mapblocks consisting of 'ignore' nodes, there will be
		// no obstructions, but mapgen decorations are generated after spawn so
		// the player may end up inside one.
		for (s32 i = 0; i < 8; i++) {
			v3s16 blockpos = getNodeBlockPos(nodepos);
			map.emergeBlock(blockpos, true);
			content_t c = map.getNode(nodepos).getContent();

			// In generated mapblocks allow spawn in all 'airlike' drawtype nodes.
			// In ungenerated mapblocks allow spawn in 'ignore' nodes.
			if (m_nodedef->get(c).drawtype == NDT_AIRLIKE || c == CONTENT_IGNORE) {
				air_count++;
				if (air_count >= 2) {
					// Spawn in lower empty node
					nodepos.Y--;
					nodeposf = intToFloat(nodepos, BS);
					// Don't spawn the player outside map boundaries
					if (objectpos_over_limit(nodeposf))
						// Exit this loop, positions above are probably over limit
						break;

					// Good position found, cause an exit from main loop
					is_good = true;
					break;
				}
			} else {
				air_count = 0;
			}
			nodepos.Y++;
		}
	}

	if (is_good)
		return nodeposf;

	// No suitable spawn point found, return fallback 0,0,0
	return v3f(0.0f, 0.0f, 0.0f);
}

void Server::requestShutdown(const std::string &msg, bool reconnect, float delay)
{
	if (delay == 0.0f) {
	// No delay, shutdown immediately
		m_shutdown_state.is_requested = true;
		// only print to the infostream, a chat message saying
		// "Server Shutting Down" is sent when the server destructs.
		infostream << "*** Immediate Server shutdown requested." << std::endl;
	} else if (delay < 0.0f && m_shutdown_state.isTimerRunning()) {
		// Negative delay, cancel shutdown if requested
		m_shutdown_state.reset();
		std::wstringstream ws;

		ws << L"*** Server shutdown canceled.";

		infostream << wide_to_utf8(ws.str()).c_str() << std::endl;
		SendChatMessage(PEER_ID_INEXISTENT, ws.str());
		// m_shutdown_* are already handled, skip.
		return;
	} else if (delay > 0.0f) {
	// Positive delay, tell the clients when the server will shut down
		std::wstringstream ws;

		ws << L"*** Server shutting down in "
				<< duration_to_string(myround(delay)).c_str()
				<< ".";

		infostream << wide_to_utf8(ws.str()).c_str() << std::endl;
		SendChatMessage(PEER_ID_INEXISTENT, ws.str());
	}

	m_shutdown_state.trigger(delay, msg, reconnect);
}

PlayerSAO* Server::emergePlayer(const char *name, session_t peer_id, u16 proto_version)
{
	/*
		Try to get an existing player
	*/
	RemotePlayer *player = m_env->getPlayer(name);

	// If player is already connected, cancel
	if (player && player->getPeerId() != PEER_ID_INEXISTENT) {
		infostream<<"emergePlayer(): Player already connected"<<std::endl;
		return NULL;
	}

	/*
		If player with the wanted peer_id already exists, cancel.
	*/
	if (m_env->getPlayer(peer_id)) {
		infostream<<"emergePlayer(): Player with wrong name but same"
				" peer_id already exists"<<std::endl;
		return NULL;
	}

	if (!player) {
		player = new RemotePlayer(name, idef());
	}

	bool newplayer = false;

	// Load player
	PlayerSAO *playersao = m_env->loadPlayer(player, &newplayer, peer_id, isSingleplayer());

	// Complete init with server parts
	playersao->finalize(player, getPlayerEffectivePrivs(player->getName()));
	player->protocol_version = proto_version;

	/* Run scripts */
	if (newplayer) {
		m_script->on_newplayer(playersao);
	}

	return playersao;
}

bool Server::registerModStorage(ModMetadata *storage)
{
	if (m_mod_storages.find(storage->getModName()) != m_mod_storages.end()) {
		errorstream << "Unable to register same mod storage twice. Storage name: "
				<< storage->getModName() << std::endl;
		return false;
	}

	m_mod_storages[storage->getModName()] = storage;
	return true;
}

void Server::unregisterModStorage(const std::string &name)
{
	std::unordered_map<std::string, ModMetadata *>::const_iterator it = m_mod_storages.find(name);
	if (it != m_mod_storages.end())
		m_mod_storages.erase(name);
}

void dedicated_server_loop(Server &server, bool &kill)
{
	verbosestream<<"dedicated_server_loop()"<<std::endl;

	IntervalLimiter m_profiler_interval;

	static thread_local const float steplen =
			g_settings->getFloat("dedicated_server_step");
	static thread_local const float profiler_print_interval =
			g_settings->getFloat("profiler_print_interval");

	/*
	 * The dedicated server loop only does time-keeping (in Server::step) and
	 * provides a way to main.cpp to kill the server externally (bool &kill).
	 */

	for(;;) {
		// This is kind of a hack but can be done like this
		// because server.step() is very light
		sleep_ms((int)(steplen*1000.0));
		server.step(steplen);

		if (server.isShutdownRequested() || kill)
			break;

		/*
			Profiler
		*/
		if (profiler_print_interval != 0) {
			if(m_profiler_interval.step(steplen, profiler_print_interval))
			{
				infostream<<"Profiler:"<<std::endl;
				g_profiler->print(infostream);
				g_profiler->clear();
			}
		}
	}

	infostream << "Dedicated server quitting" << std::endl;
#if USE_CURL
	if (g_settings->getBool("server_announce"))
		ServerList::sendAnnounce(ServerList::AA_DELETE,
			server.m_bind_addr.getPort());
#endif
}

/*
 * Mod channels
 */


bool Server::joinModChannel(const std::string &channel)
{
	return m_modchannel_mgr->joinChannel(channel, PEER_ID_SERVER) &&
			m_modchannel_mgr->setChannelState(channel, MODCHANNEL_STATE_READ_WRITE);
}

bool Server::leaveModChannel(const std::string &channel)
{
	return m_modchannel_mgr->leaveChannel(channel, PEER_ID_SERVER);
}

bool Server::sendModChannelMessage(const std::string &channel, const std::string &message)
{
	if (!m_modchannel_mgr->canWriteOnChannel(channel))
		return false;

	broadcastModChannelMessage(channel, message, PEER_ID_SERVER);
	return true;
}

ModChannel* Server::getModChannel(const std::string &channel)
{
	return m_modchannel_mgr->getModChannel(channel);
}

void Server::broadcastModChannelMessage(const std::string &channel,
		const std::string &message, session_t from_peer)
{
	const std::vector<u16> &peers = m_modchannel_mgr->getChannelPeers(channel);
	if (peers.empty())
		return;

	if (message.size() > STRING_MAX_LEN) {
		warningstream << "ModChannel message too long, dropping before sending "
				<< " (" << message.size() << " > " << STRING_MAX_LEN << ", channel: "
				<< channel << ")" << std::endl;
		return;
	}

	std::string sender;
	if (from_peer != PEER_ID_SERVER) {
		sender = getPlayerName(from_peer);
	}

	NetworkPacket resp_pkt(TOCLIENT_MODCHANNEL_MSG,
			2 + channel.size() + 2 + sender.size() + 2 + message.size());
	resp_pkt << channel << sender << message;
	for (session_t peer_id : peers) {
		// Ignore sender
		if (peer_id == from_peer)
			continue;

		Send(peer_id, &resp_pkt);
	}

	if (from_peer != PEER_ID_SERVER) {
		m_script->on_modchannel_message(channel, sender, message);
	}
}

Translations *Server::getTranslationLanguage(const std::string &lang_code)
{
	if (lang_code.empty())
		return nullptr;

	auto it = server_translations.find(lang_code);
	if (it != server_translations.end())
		return &it->second; // Already loaded

	// [] will create an entry
	auto *translations = &server_translations[lang_code];

	std::string suffix = "." + lang_code + ".tr";
	for (const auto &i : m_media) {
		if (str_ends_with(i.first, suffix)) {
			std::string data;
			if (fs::ReadFile(i.second.path, data)) {
				translations->loadTranslation(data);
			}
		}
	}

	return translations;
}

ModMetadataDatabase *Server::openModStorageDatabase(const std::string &world_path)
{
	std::string world_mt_path = world_path + DIR_DELIM + "world.mt";
	Settings world_mt;
	if (!world_mt.readConfigFile(world_mt_path.c_str()))
		throw BaseException("Cannot read world.mt!");

	std::string backend = world_mt.exists("mod_storage_backend") ?
		world_mt.get("mod_storage_backend") : "files";
	if (backend == "files")
		warningstream << "/!\\ You are using the old mod storage files backend. "
			<< "This backend is deprecated and may be removed in a future release /!\\"
			<< std::endl << "Switching to SQLite3 is advised, "
			<< "please read http://wiki.minetest.net/Database_backends." << std::endl;

	return openModStorageDatabase(backend, world_path, world_mt);
}

ModMetadataDatabase *Server::openModStorageDatabase(const std::string &backend,
		const std::string &world_path, const Settings &world_mt)
{
	if (backend == "sqlite3")
		return new ModMetadataDatabaseSQLite3(world_path);

	if (backend == "files")
		return new ModMetadataDatabaseFiles(world_path);

	if (backend == "dummy")
		return new Database_Dummy();

	throw BaseException("Mod storage database backend " + backend + " not supported");
}

bool Server::migrateModStorageDatabase(const GameParams &game_params, const Settings &cmd_args)
{
	std::string migrate_to = cmd_args.get("migrate-mod-storage");
	Settings world_mt;
	std::string world_mt_path = game_params.world_path + DIR_DELIM + "world.mt";
	if (!world_mt.readConfigFile(world_mt_path.c_str())) {
		errorstream << "Cannot read world.mt!" << std::endl;
		return false;
	}

	std::string backend = world_mt.exists("mod_storage_backend") ?
		world_mt.get("mod_storage_backend") : "files";
	if (backend == migrate_to) {
		errorstream << "Cannot migrate: new backend is same"
			<< " as the old one" << std::endl;
		return false;
	}

	ModMetadataDatabase *srcdb = nullptr;
	ModMetadataDatabase *dstdb = nullptr;

	bool succeeded = false;

	try {
		srcdb = Server::openModStorageDatabase(backend, game_params.world_path, world_mt);
		dstdb = Server::openModStorageDatabase(migrate_to, game_params.world_path, world_mt);

		dstdb->beginSave();

		std::vector<std::string> mod_list;
		srcdb->listMods(&mod_list);
		for (const std::string &modname : mod_list) {
			StringMap meta;
			srcdb->getModEntries(modname, &meta);
			for (const auto &pair : meta) {
				dstdb->setModEntry(modname, pair.first, pair.second);
			}
		}

		dstdb->endSave();

		succeeded = true;

		actionstream << "Successfully migrated the metadata of "
			<< mod_list.size() << " mods" << std::endl;
		world_mt.set("mod_storage_backend", migrate_to);
		if (!world_mt.updateConfigFile(world_mt_path.c_str()))
			errorstream << "Failed to update world.mt!" << std::endl;
		else
			actionstream << "world.mt updated" << std::endl;

	} catch (BaseException &e) {
		errorstream << "An error occurred during migration: " << e.what() << std::endl;
	}

	delete srcdb;
	delete dstdb;

	if (succeeded && backend == "files") {
		// Back up files
		const std::string storage_path = game_params.world_path + DIR_DELIM + "mod_storage";
		const std::string backup_path = game_params.world_path + DIR_DELIM + "mod_storage.bak";
		if (!fs::Rename(storage_path, backup_path))
			warningstream << "After migration, " << storage_path
				<< " could not be renamed to " << backup_path << std::endl;
	}

	return succeeded;
}