feat(master): an edit mode flag on a private instance, down to its world server

CreatePrivateZone carries editMode as one more byte, written only when set, so
a plain private zone is sent as before. Master keeps it on the instance, starts
the world server with -editmode 1, and gives a private instance's replacement
(a reload or a live update) the same flag. Nothing sets it yet.

A capped string now skips the characters it cut, so what follows it is read
from the right place. A request to join a private instance that is still
starting is answered once its world server is ready, instead of at once with
an address nothing listens on yet.

Co-Authored-By: Claude Fable 5.2 <noreply@anthropic.com>

dMasterServer/InstanceManager.cpp

@@ -387,7 +387,7 @@ const InstancePtr& InstanceManager::FindInstanceWithPrivate(LWOMAPID mapID, LWOI
 	return g_Empty;
 }
 
-const InstancePtr& InstanceManager::CreatePrivateInstance(LWOMAPID mapID, LWOCLONEID cloneID, const std::string& password) {
+const InstancePtr& InstanceManager::CreatePrivateInstance(LWOMAPID mapID, LWOCLONEID cloneID, const std::string& password, const bool editMode) {
 	const auto& instance = FindPrivateInstance(password);
 
 	if (instance != nullptr) {
@@ -408,9 +408,10 @@ const InstancePtr& InstanceManager::CreatePrivateInstance(LWOMAPID mapID, LWOCLO
 
 	uint32_t port = GetFreePort();
 	auto newInstance = make_unique<Instance>(mExternalIP, port, mapID, ++m_LastInstanceID, cloneID, maxPlayers, maxPlayers, true, password);
+	newInstance->SetIsEditMode(editMode);
 
 	//Start the actual process:
-	StartWorldServer(mapID, port, m_LastInstanceID, maxPlayers, cloneID);
+	StartWorldServer(mapID, port, m_LastInstanceID, maxPlayers, cloneID, editMode);
 
 	m_Instances.push_back(std::move(newInstance));
 	if (m_OnInstancesChanged) m_OnInstancesChanged();

dMasterServer/InstanceManager.h

@@ -58,6 +58,10 @@ public:
 
 	bool GetIsPrivate() const { return m_IsPrivate; }
 	const std::string& GetPassword() const { return m_Password; }
+	// A GM's edit mode instance (docs/EditMode.md): private, and its world server constructs none of the zone's
+	// objects. Its replacement (a reload, a live update) is in edit mode too
+	bool GetIsEditMode() const { return m_IsEditMode; }
+	void SetIsEditMode(bool value) { m_IsEditMode = value; }
 
 	bool GetIsReady() const { return m_Ready; }
 	void SetIsReady(bool value) { m_Ready = value; }
@@ -156,6 +160,7 @@ private:
 
 	bool m_IsPrivate{};
 	std::string m_Password{};
+	bool m_IsEditMode{};
 
 	bool m_Shutdown{};
 
@@ -194,7 +199,8 @@ public:
 	const InstancePtr& FindInstance(LWOMAPID mapID, LWOINSTANCEID instanceID);
 	const InstancePtr& FindInstanceWithPrivate(LWOMAPID mapID, LWOINSTANCEID instanceID);
 
-	const InstancePtr& CreatePrivateInstance(LWOMAPID mapID, LWOCLONEID cloneID, const std::string& password);
+	// editMode: a GM's edit mode instance. An instance that has the password already is returned as it is
+	const InstancePtr& CreatePrivateInstance(LWOMAPID mapID, LWOCLONEID cloneID, const std::string& password, bool editMode = false);
 	const InstancePtr& FindPrivateInstance(const std::string& password);
 	void SetIsShuttingDown(bool value) { this->m_IsShuttingDown = value; };
 	void PruneUnreadyInstances();

dMasterServer/MasterServer.cpp

@@ -893,12 +893,12 @@ namespace {
 
 	void OnCreatePrivateZone(const CreatePrivateZone& request, const SystemAddress& sysAddr) {
 		// Passwords were cut to 50 characters when read
-		const auto& newInst = Game::im->CreatePrivateInstance(request.zoneID, request.cloneID, request.password.c_str());
+		const auto& newInst = Game::im->CreatePrivateInstance(request.zoneID, request.cloneID, request.password.c_str(), request.editMode != 0);
 		if (!newInst) {
 			LOG("No private zone was created for map %i/%i", request.zoneID, request.cloneID);
 			return;
 		}
-		LOG("Creating private zone %i/%i/%i", newInst->GetMapID(), newInst->GetCloneID(), newInst->GetInstanceID());
+		LOG("Creating private zone %i/%i/%i%s", newInst->GetMapID(), newInst->GetCloneID(), newInst->GetInstanceID(), newInst->GetIsEditMode() ? " in edit mode" : "");
 	}
 
 	void OnRequestPrivateZone(const RequestPrivateZone& request, const SystemAddress& sysAddr) {
@@ -915,6 +915,12 @@ namespace {
 			return;
 		}
 
+		// Still starting (asked for right after it was created): answered when its world server is ready
+		if (!instance->GetIsReady()) {
+			instance->GetPendingRequests().push_back({ requestID, static_cast<bool>(mythranShift), sysAddr, {} });
+			return;
+		}
+
 		const auto& zone = instance->GetZoneID();
 
 		RequestZoneTransferResponse response;

dMasterServer/MigrationCoordinator.cpp

@@ -171,11 +171,11 @@ void MigrationCoordinator::SetObserver(std::function<void(const MigrationStatus&
 
 namespace {
 	// The new instance (REPLACE): a fresh world server from the binary on disk now, so an update takes effect. A private
-	// instance's replacement gets the same password; the source is draining already, so the password finds the new one.
+	// instance's replacement gets the same password and edit mode; the source is draining already, so the password finds the new one.
 	Instance* StartTarget(Instance& source) {
 		if (source.GetIsPrivate()) {
 			source.SetIsDraining(true);
-			const auto& started = Game::im->CreatePrivateInstance(source.GetMapID(), source.GetCloneID(), source.GetPassword());
+			const auto& started = Game::im->CreatePrivateInstance(source.GetMapID(), source.GetCloneID(), source.GetPassword(), source.GetIsEditMode());
 			return started ? started.get() : nullptr;
 		}
 		const auto& started = Game::im->StartNewInstance(source.GetMapID(), source.GetCloneID());

dMasterServer/Start.cpp

@@ -192,13 +192,13 @@ uint32_t StartUgcServer() {
 	return ugc_pid;
 }
 
-uint32_t StartWorldServer(LWOMAPID mapID, uint16_t port, LWOINSTANCEID lastInstanceID, int maxPlayers, LWOCLONEID cloneID) {
+uint32_t StartWorldServer(LWOMAPID mapID, uint16_t port, LWOINSTANCEID lastInstanceID, int maxPlayers, LWOCLONEID cloneID, const bool editMode) {
 	auto world_path = BinaryPathFinder::GetBinaryDir() / "WorldServer";
 #ifdef _WIN32
 	world_path.replace_extension(".exe");
 	auto cmd = world_path.wstring() + L" -zone " + std::to_wstring(mapID) + L" -port " + std::to_wstring(port) +
 		L" -instance " + std::to_wstring(lastInstanceID) + L" -maxclients " + std::to_wstring(maxPlayers) +
-		L" -clone " + std::to_wstring(cloneID);
+		L" -clone " + std::to_wstring(cloneID) + L" -editmode " + std::to_wstring(editMode ? 1 : 0);
 
 	auto world_startup = startup;
 	auto world_info = PROCESS_INFORMATION{};
@@ -226,7 +226,8 @@ uint32_t StartWorldServer(LWOMAPID mapID, uint16_t port, LWOINSTANCEID lastInsta
 			"-port", std::to_string(port).c_str(),
 			"-instance", std::to_string(lastInstanceID).c_str(),
 			"-maxclients", std::to_string(maxPlayers).c_str(),
-			"-clone", std::to_string(cloneID).c_str(), nullptr);
+			"-clone", std::to_string(cloneID).c_str(),
+			"-editmode", editMode ? "1" : "0", nullptr);
 		// exec failed (e.g. the binary is being rebuilt): the child must not carry on as a second master
 		perror("exec");
 		_exit(127);

dMasterServer/Start.h

@@ -5,4 +5,4 @@ uint32_t StartAuthServer();
 uint32_t StartChatServer();
 uint32_t StartDashboardServer();
 uint32_t StartUgcServer();
-uint32_t StartWorldServer(LWOMAPID mapID, uint16_t port, LWOINSTANCEID lastInstanceID, int maxPlayers, LWOCLONEID cloneID);
+uint32_t StartWorldServer(LWOMAPID mapID, uint16_t port, LWOINSTANCEID lastInstanceID, int maxPlayers, LWOCLONEID cloneID, bool editMode = false);

dNet/MasterPackets.cpp

@@ -16,7 +16,12 @@ namespace {
 		uint32_t length{};
 		VALIDATE_READ(bitStream.Read(length));
 		value.resize(std::min(length, maxLength));
-		return value.empty() || bitStream.ReadBits(reinterpret_cast<unsigned char*>(value.data()), BYTES_TO_BITS(value.size()), true);
+		if (!value.empty() && !bitStream.ReadBits(reinterpret_cast<unsigned char*>(value.data()), BYTES_TO_BITS(value.size()), true)) return false;
+		const uint32_t rest = length - static_cast<uint32_t>(value.size());
+		if (rest == 0) return true;
+		if (BITS_TO_BYTES(bitStream.GetNumberOfUnreadBits()) < rest) return false;
+		bitStream.IgnoreBits(BYTES_TO_BITS(rest));
+		return true;
 	}
 }
 
@@ -147,12 +152,15 @@ namespace MasterPackets {
 		bitStream.Write(zoneID);
 		bitStream.Write(cloneID);
 		BitStreamUtils::WriteLengthPrefixed<uint32_t>(bitStream, password);
+		if (editMode != 0) bitStream.Write(editMode);
 	}
 
 	bool CreatePrivateZone::Deserialize(RakNet::BitStream& bitStream) {
 		VALIDATE_READ(bitStream.Read(zoneID));
 		VALIDATE_READ(bitStream.Read(cloneID));
 		VALIDATE_READ(ReadCappedString(bitStream, password, MAX_PASSWORD_LENGTH));
+		editMode = 0;
+		if (bitStream.GetNumberOfUnreadBits() >= 8) VALIDATE_READ(bitStream.Read(editMode));
 		return true;
 	}
 

dNet/MasterPackets.h

@@ -146,6 +146,9 @@ namespace MasterPackets {
 		uint32_t zoneID{};
 		uint32_t cloneID{};
 		std::string password; // u32 length, then 1 byte per character
+		// A GM's edit mode: the instance's world server constructs none of the zone's objects (docs/EditMode.md). Written
+		// only when set, so a plain private zone stays as it always was
+		uint8_t editMode{};
 
 		CreatePrivateZone() : LUBitStream(ServiceType::MASTER, MessageType::Master::CREATE_PRIVATE_ZONE) {}
 		void Serialize(RakNet::BitStream& bitStream) const override;

dNet/PacketFields.inc

@@ -1009,6 +1009,7 @@ json ToJson(const MasterPackets::CreatePrivateZone& m) {
 	json j = json::object();
 	j["zoneID"] = ToJson(m.zoneID);
 	j["cloneID"] = ToJson(m.cloneID);
+	j["editMode"] = ToJson(m.editMode);
 	return j;
 }
 json ToJson(const MasterPackets::RequestPrivateZone& m) {

dNet/ZoneInstanceManager.cpp

@@ -35,11 +35,12 @@ void ZoneInstanceManager::HandleRequestZoneTransferResponse(const MasterPackets:
 	}
 }
 
-void ZoneInstanceManager::CreatePrivateZone(dServer* server, uint32_t zoneID, uint32_t zoneClone, const std::string& password) {
+void ZoneInstanceManager::CreatePrivateZone(dServer* server, uint32_t zoneID, uint32_t zoneClone, const std::string& password, const bool editMode) {
 	MasterPackets::CreatePrivateZone request;
 	request.zoneID = zoneID;
 	request.cloneID = zoneClone;
 	request.password = password;
+	request.editMode = editMode ? 1 : 0;
 	MasterPackets::SendToMaster(request, server);
 }
 

dNet/ZoneInstanceManager.h

@@ -62,7 +62,8 @@ public:
 	 */
 	void HandleRequestZoneTransferResponse(const MasterPackets::RequestZoneTransferResponse& response);
 
-	void CreatePrivateZone(dServer* server, uint32_t zoneID, uint32_t zoneClone, const std::string& password);
+	// editMode: a GM's edit mode instance, whose world server constructs none of the zone's objects
+	void CreatePrivateZone(dServer* server, uint32_t zoneID, uint32_t zoneClone, const std::string& password, bool editMode = false);
 
 	void RequestPrivateZone(dServer* server, bool mythranShift, const std::string& password, TransferCallback callback);
 };

tests/dGameTests/dNetTests/MasterPacketsTests.cpp

@@ -237,6 +237,32 @@ TEST(MasterPacketsTests, PrivateZonesMatchLegacy) {
 	}
 }
 
+// The edit mode flag of a private zone: one more byte, only when set, and read after a password of any length
+TEST(MasterPacketsTests, CreatePrivateZoneEditMode) {
+	for (const auto& password : g_Strings) {
+		MasterPackets::CreatePrivateZone plain;
+		plain.zoneID = 1100;
+		plain.password = password;
+		MasterPackets::CreatePrivateZone edit = plain;
+		edit.editMode = 1;
+
+		RakNet::BitStream plainStream; LoadPayload(plainStream, plain);
+		RakNet::BitStream editStream; LoadPayload(editStream, edit);
+		EXPECT_EQ(editStream.GetNumberOfUnreadBits(), plainStream.GetNumberOfUnreadBits() + 8);
+
+		MasterPackets::CreatePrivateZone readPlain;
+		readPlain.editMode = 1;
+		ASSERT_TRUE(readPlain.Deserialize(plainStream));
+		EXPECT_EQ(readPlain.editMode, 0);
+
+		MasterPackets::CreatePrivateZone readEdit;
+		ASSERT_TRUE(readEdit.Deserialize(editStream));
+		EXPECT_EQ(readEdit.editMode, 1);
+		EXPECT_EQ(readEdit.zoneID, 1100u);
+		EXPECT_EQ(readEdit.password, password.substr(0, MasterPackets::CreatePrivateZone::MAX_PASSWORD_LENGTH));
+	}
+}
+
 TEST(MasterPacketsTests, WorldStateMatchesLegacy) {
 	for (const LWOMAPID zone : { static_cast<LWOMAPID>(0), static_cast<LWOMAPID>(1100), static_cast<LWOMAPID>(0xFFFF) }) {
 		for (const LWOINSTANCEID instance : { static_cast<LWOINSTANCEID>(0), static_cast<LWOINSTANCEID>(3), static_cast<LWOINSTANCEID>(0xFFFF) }) {