Add static_save and prevent UDP connect exhaustionslifo-fixes

This merges two pull requests from 5.0

11 files changed, 104 insertions, 34 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 95f1f28d3..b63b10f70 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -14,8 +14,8 @@ set(PROJECT_NAME_CAPITALIZED "Minetest")
 set(VERSION_MAJOR 0)
 set(VERSION_MINOR 4)
 set(VERSION_PATCH 17)
-set(VERSION_TWEAK 1)
-set(VERSION_EXTRA "" CACHE STRING "Stuff to append to version string")
+set(VERSION_TWEAK 2)
+set(VERSION_EXTRA "LinuxForks" CACHE STRING "Stuff to append to version string")
 
 # Change to false for releases
 set(DEVELOPMENT_BUILD FALSE)
diff --git a/doc/lua_api.txt b/doc/lua_api.txt
index 728fd0a1c..ca6f1585f 100644
--- a/doc/lua_api.txt
+++ b/doc/lua_api.txt
@@ -4048,6 +4048,10 @@ Definition tables
         nametag = "", -- by default empty, for players their name is shown if empty
         nametag_color = <color>, -- sets color of nametag as ColorSpec
         infotext = "", -- by default empty, text to be shown when pointed at object
+        static_save = true,
+    --  ^ If false, never save this object statically. It will simply be deleted when the block gets unloaded.
+    --  ^ The get_staticdata() callback is never called then.
+    --  ^ Defaults to 'true'
     }
 
 ### Entity definition (`register_entity`)
diff --git a/src/content_sao.h b/src/content_sao.h
index 0dad54805..9444ee758 100644
--- a/src/content_sao.h
+++ b/src/content_sao.h
@@ -102,6 +102,8 @@ public:
 			const std::string &data);
 	void step(float dtime, bool send_recommended);
 	std::string getClientInitializationData(u16 protocol_version);
+	bool isStaticAllowed() const
+	{ return m_prop.static_save; }
 	void getStaticData(std::string *result) const;
 	int punch(v3f dir,
 			const ToolCapabilities *toolcap=NULL,
diff --git a/src/network/connection.cpp b/src/network/connection.cpp
index fb3ba92ae..a504bbc08 100644
--- a/src/network/connection.cpp
+++ b/src/network/connection.cpp
@@ -2884,16 +2884,21 @@ void Connection::Disconnect()
 	putCommand(c);
 }
 
-void Connection::Receive(NetworkPacket* pkt)
+bool Connection::Receive(NetworkPacket *pkt, u32 timeout)
 {
+	/*
+		Note that this function can potentially wait infinitely if non-data
+		events keep happening before the timeout expires.
+		This is not considered to be a problem (is it?)
+	*/
 	for(;;) {
-		ConnectionEvent e = waitEvent(m_bc_receive_timeout);
+		ConnectionEvent e = waitEvent(timeout);
 		if (e.type != CONNEVENT_NONE)
 			LOG(dout_con << getDesc() << ": Receive: got event: "
 					<< e.describe() << std::endl);
 		switch(e.type) {
 		case CONNEVENT_NONE:
-			throw NoIncomingDataException("No incoming data");
+			return false;
 		case CONNEVENT_DATA_RECEIVED:
 			// Data size is lesser than command size, ignoring packet
 			if (e.data.getSize() < 2) {
@@ -2901,7 +2906,7 @@ void Connection::Receive(NetworkPacket* pkt)
 			}
 
 			pkt->putRawPacket(*e.data, e.data.getSize(), e.peer_id);
-			return;
+			return true;
 		case CONNEVENT_PEER_ADDED: {
 			UDPPeer tmp(e.peer_id, e.address, this);
 			if (m_bc_peerhandler)
@@ -2919,7 +2924,19 @@ void Connection::Receive(NetworkPacket* pkt)
 					"(port already in use?)");
 		}
 	}
-	throw NoIncomingDataException("No incoming data");
+	return false;
+}
+
+void Connection::Receive(NetworkPacket *pkt)
+{
+	bool any = Receive(pkt, m_bc_receive_timeout);
+	if (!any)
+		throw NoIncomingDataException("No incoming data");
+}
+
+bool Connection::TryReceive(NetworkPacket *pkt)
+{
+	return Receive(pkt, 0);
 }
 
 void Connection::Send(u16 peer_id, u8 channelnum,
diff --git a/src/network/connection.h b/src/network/connection.h
index 8b7ed9773..a202fa2f5 100644
--- a/src/network/connection.h
+++ b/src/network/connection.h
@@ -1016,6 +1016,7 @@ public:
 	bool Connected();
 	void Disconnect();
 	void Receive(NetworkPacket* pkt);
+	bool TryReceive(NetworkPacket* pkt);
 	void Send(u16 peer_id, u8 channelnum, NetworkPacket* pkt, bool reliable);
 	u16 GetPeerID() { return m_peer_id; }
 	Address GetPeerAddress(u16 peer_id);
@@ -1050,6 +1051,8 @@ protected:
 	UDPSocket m_udpSocket;
 	MutexedQueue<ConnectionCommand> m_command_queue;
 
+	bool Receive(NetworkPacket *pkt, u32 timeout);
+
 	void putEvent(ConnectionEvent &e);
 
 	void TriggerSend()
@@ -1074,7 +1077,7 @@ private:
 	// Backwards compatibility
 	PeerHandler *m_bc_peerhandler;
 	int m_bc_receive_timeout;
-
+  
 	bool m_shutting_down;
 
 	u16 m_next_remote_peer_id;
diff --git a/src/network/networkpacket.cpp b/src/network/networkpacket.cpp
index c4fcf9600..7c2c7d0f9 100644
--- a/src/network/networkpacket.cpp
+++ b/src/network/networkpacket.cpp
@@ -65,6 +65,15 @@ void NetworkPacket::putRawPacket(u8 *data, u32 datasize, u16 peer_id)
 	memcpy(m_data.data(), &data[2], m_datasize);
 }
 
+void NetworkPacket::clear()
+{
+	m_data.clear();
+	m_datasize = 0;
+	m_read_offset = 0;
+	m_command = 0;
+	m_peer_id = 0;
+}
+
 const char* NetworkPacket::getString(u32 from_offset)
 {
 	checkReadOffset(from_offset, 0);
diff --git a/src/network/networkpacket.h b/src/network/networkpacket.h
index 83dc33f6f..fc14d61d8 100644
--- a/src/network/networkpacket.h
+++ b/src/network/networkpacket.h
@@ -35,7 +35,7 @@ public:
 		~NetworkPacket();
 
 		void putRawPacket(u8 *data, u32 datasize, u16 peer_id);
-
+		void clear();
 		// Getters
 		u32 getSize() { return m_datasize; }
 		u16 getPeerId() { return m_peer_id; }
diff --git a/src/object_properties.cpp b/src/object_properties.cpp
index a77368151..543c0e876 100644
--- a/src/object_properties.cpp
+++ b/src/object_properties.cpp
@@ -72,6 +72,7 @@ std::string ObjectProperties::dump()
 	}
 	os<<"]";
 	os<<", spritediv="<<PP2(spritediv);
+	os << ", static_save=" << static_save;
 	os<<", initial_sprite_basepos="<<PP2(initial_sprite_basepos);
 	os<<", is_visible="<<is_visible;
 	os<<", makes_footstep_sound="<<makes_footstep_sound;
diff --git a/src/object_properties.h b/src/object_properties.h
index 908757a64..9bfe7ea7b 100644
--- a/src/object_properties.h
+++ b/src/object_properties.h
@@ -54,6 +54,7 @@ struct ObjectProperties
 	std::string infotext;
 	//! For dropped items, this contains item information.
 	std::string wield_item;
+	bool static_save = true;
 
 	ObjectProperties();
 	std::string dump();
diff --git a/src/script/common/c_content.cpp b/src/script/common/c_content.cpp
index c0e29abf0..24b84e0d0 100644
--- a/src/script/common/c_content.cpp
+++ b/src/script/common/c_content.cpp
@@ -273,7 +273,10 @@ void read_object_properties(lua_State *L, int index,
 		prop->automatic_face_movement_max_rotation_per_sec = luaL_checknumber(L, -1);
 	}
 	lua_pop(L, 1);
+
 	getstringfield(L, -1, "infotext", prop->infotext);
+	getboolfield(L, -1, "static_save", prop->static_save);
+
 	lua_getfield(L, -1, "wield_item");
 	if (!lua_isnil(L, -1))
 		prop->wield_item = read_item(L, -1, idef).getItemString();
@@ -346,6 +349,8 @@ void push_object_properties(lua_State *L, ObjectProperties *prop)
 	lua_setfield(L, -2, "automatic_face_movement_max_rotation_per_sec");
 	lua_pushlstring(L, prop->infotext.c_str(), prop->infotext.size());
 	lua_setfield(L, -2, "infotext");
+	lua_pushboolean(L, prop->static_save);
+	lua_setfield(L, -2, "static_save");
 	lua_pushlstring(L, prop->wield_item.c_str(), prop->wield_item.size());
 	lua_setfield(L, -2, "wield_item");
 }
diff --git a/src/server.cpp b/src/server.cpp
index 71a349b08..4b54c2398 100644
--- a/src/server.cpp
+++ b/src/server.cpp
@@ -90,6 +90,15 @@ void *ServerThread::run()
 	DSTACK(FUNCTION_NAME);
 	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.
+	 */
+
 	m_server->AsyncRunStep(true);
 
 	while (!stopRequested()) {
@@ -100,7 +109,6 @@ void *ServerThread::run()
 
 			m_server->Receive();
 
-		} catch (con::NoIncomingDataException &e) {
 		} catch (con::PeerNotFoundException &e) {
 			infostream<<"Server: PeerNotFoundException"<<std::endl;
 		} catch (ClientNotFoundException &e) {
@@ -1052,30 +1060,45 @@ void Server::Receive()
 	DSTACK(FUNCTION_NAME);
 	SharedBuffer<u8> data;
 	u16 peer_id;
-	try {
-		NetworkPacket pkt;
-		m_con.Receive(&pkt);
-		peer_id = pkt.getPeerId();
-		ProcessData(&pkt);
-	}
-	catch(con::InvalidIncomingDataException &e) {
-		infostream<<"Server::Receive(): "
-				"InvalidIncomingDataException: what()="
-				<<e.what()<<std::endl;
-	}
-	catch(SerializationError &e) {
-		infostream<<"Server::Receive(): "
-				"SerializationError: what()="
-				<<e.what()<<std::endl;
-	}
-	catch(ClientStateError &e) {
-		errorstream << "ProcessData: peer=" << peer_id  << e.what() << std::endl;
-		DenyAccess_Legacy(peer_id, L"Your client sent something server didn't expect."
-				L"Try reconnecting or updating your client");
-	}
-	catch(con::PeerNotFoundException &e) {
-		// Do nothing
-	}
+	bool first = true;
+	NetworkPacket pkt;
+	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();
+	    ProcessData(&pkt);
+
+	  } 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_Legacy(peer_id, L"Your client sent something server didn't expect."
+			      L"Try reconnecting or updating your client");
+	  } catch (const con::PeerNotFoundException &e) {
+	    // Do nothing
+	  } catch (const con::NoIncomingDataException &e) {
+	    return;
+	  }
+ 	}
+	
 }
 
 PlayerSAO* Server::StageTwoClientInit(u16 peer_id)
@@ -3682,6 +3705,11 @@ void dedicated_server_loop(Server &server, bool &kill)
 	static 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