Packet System

Moongate v2 uses concrete packet classes implementing IGameNetworkPacket.

Packet Contract

public interface IGameNetworkPacket
{
    byte OpCode { get; }
    int Length { get; } // -1 for variable-length
    bool TryParse(ReadOnlySpan<byte> data);
    void Write(ref SpanWriter writer);
}

Registration Model

Packets are decorated with:

[PacketHandler(0x02, PacketSizing.Fixed, Length = 7, Description = "Move Request")]

Key types:

• PacketHandlerAttribute
  • OpCode, Sizing, Length, Description
• PacketSizing
  • Fixed, Variable
• PacketRegistry
  • metadata + packet factory per opcode
• PacketTable.Register(PacketRegistry)
  • generated registration entrypoint

Runtime Use

NetworkService uses PacketRegistry to:

1. resolve descriptor (TryGetDescriptor)
2. create packet instance (TryCreatePacket)
3. call TryParse(rawPacket)
4. publish IncomingGamePacket to message bus

PacketDispatchService then routes by opcode to registered IPacketListener instances.

Current gameplay examples:

• PlayerStatusHandler listens to PacketDefinition.GetPlayerStatusPacket
  • BasicStatus requests enqueue PlayerStatusPacket (0x11)
  • RequestSkills requests enqueue SkillListPacket (0x3A)
• ItemHandler listens to book packets
  • BookHeaderNewPacket (0xD4) saves writable book title / author
  • BookPagesPacket (0x66) serves page requests and writable page saves
• DyeWindowHandler listens to DyeWindowPacket (0x95)
  • the classic dye-tub target flow opens 0x95 to the client
  • the client response on 0x95 applies hue to the pending item target
• BulletinBoardHandler listens to BulletinBoardMessagesPacket (0x71)
  • double click on a bulletin board opens the classic board window
  • client sub 3/4/5/6 requests load messages, post replies, and remove owned leaf messages

Pragmatic POL Coverage Matrix

This matrix tracks the packet subset that is already present in Moongate or still relevant for the current 7.x client target.

Status values:

• handler: parsed and wired to gameplay with RegisterPacketHandler(...)
• outgoing: server-to-client packet emitted by runtime code
• parse-only: packet class is registered in PacketRegistry, but no gameplay listener handles it yet
• missing: relevant in POL/client docs, but not implemented in Moongate

Opcode	Op Description	Direction	Moongate Packet Class	Status	Runtime Wiring	Notes
0xEF	Login Seed	C -> S	LoginSeedPacket	handler	LoginHandler	Login bootstrap
0x80	Account Login	C -> S	AccountLoginPacket	handler	LoginHandler	Account auth
0xA0	Server Select	C -> S	ServerSelectPacket	handler	LoginHandler	Shard select
0x91	Game Login	C -> S	GameLoginPacket	handler	LoginHandler	Game-server auth
0x5D	Login Character	C -> S	LoginCharacterPacket	handler	LoginHandler	Character enter world
0xBD	Client Version	C -> S	ClientVersionPacket	handler	LoginHandler	Stores negotiated client version
0xF8	Character Creation	C -> S	CharacterCreationPacket	handler	CharacterHandler	Modern creation flow
0x72	Request War Mode / War Mode	both	RequestWarModePacket, WarModePacket	handler + outgoing	CharacterHandler	Inbound toggle request and outbound war-mode state reply share opcode 0x72; outgoing packet is intentionally not registry-decorated to avoid direction-agnostic opcode collision
0x02	Move Request	C -> S	MoveRequestPacket	handler	MovementHandler	Core movement
0x73	Ping Message	C -> S	PingMessagePacket	handler	PingPongHandler	Keepalive
0xC8	Client View Range	C -> S	ClientViewRangePacket	handler	ClientViewRangeHandler	View range update
0x34	Get Player Status	C -> S	GetPlayerStatusPacket	handler	PlayerStatusHandler	BasicStatus -> 0x11, RequestSkills -> 0x3A
0xAD	Unicode Speech	C -> S	UnicodeSpeechPacket	handler	SpeechHandler	In-game commands and speech
0xB5	Open Chat Window	C -> S	OpenChatWindowPacket	handler	ChatHandler	Opens classic conference chat and creates runtime chat user
0xB3	Chat Text	C -> S	ChatTextPacket	handler	ChatHandler	Conference chat actions (message, join, pm, ignore, ops, voice, kick, whois, emote)
0x6C	Target Cursor Commands	C -> S	TargetCursorCommandsPacket	handler	PlayerTargetService	Target callbacks
0xBF	General Information	C -> S	GeneralInformationPacket	handler	GeneralInformationHandler	Includes context menu / stat lock subcommands
0xD6	Mega Cliloc	C -> S	MegaClilocPacket	handler	ToolTipHandler	Tooltip requests
0xB1	Gump Menu Selection	C -> S	GumpMenuSelectionPacket	handler	GumpHandler	Gump button replies
0x06	Double Click	C -> S	DoubleClickPacket	handler	ItemHandler	Item use / open flows
0x09	Single Click	C -> S	SingleClickPacket	handler	ItemHandler	Labels / tooltip-side behavior
0x07	Pick Up Item	C -> S	PickUpItemPacket	handler	ItemHandler	Drag start
0x08	Drop Item	C -> S	DropItemPacket	handler	ItemHandler	Container / world drop
0x13	Drop -> Wear Item	C -> S	DropWearItemPacket	handler	ItemHandler	Equip flow
0x66	Books (Pages)	C -> S	BookPagesPacket	handler	ItemHandler	Page request and writable page save
0x71	Bulletin Board Messages	both	BulletinBoardMessagesPacket, BulletinBoardDisplayPacket, BulletinBoardSummaryPacket, BulletinBoardMessagePacket	handler + outgoing	BulletinBoardHandler, BulletinBoardModule / BulletinBoardService	Classic bulletin board open/read/post/remove flow
0x95	Dye Window	both	DyeWindowPacket, DisplayDyeWindowPacket	handler + outgoing	DyeWindowHandler, DyeModule / DyeColorService	Classic dye tub hue picker flow; outgoing packet intentionally not registry-decorated to avoid opcode collision
0xD4	Book Header (New)	C -> S	BookHeaderNewPacket	handler	ItemHandler	Writable title / author save
0xD9	Spy On Client	C -> S	SpyOnClientPacket	handler	PlayerHandler	Minimal session-side handling
0x03	Talk Request	C -> S	TalkRequestPacket	parse-only	none	Legacy speech path not wired
0x12	Request Skill / Use	C -> S	RequestSkillUsePacket	parse-only	none	Skill-use flow still missing
0x83	Delete Character	C -> S	DeleteCharacterPacket	parse-only	none	No delete flow wired
0xA8	Server List	S -> C	ServerListPacket	outgoing	LoginHandler	Shard list
0x8C	Server Redirect	S -> C	ServerRedirectPacket	outgoing	LoginHandler	Redirect to game server
0x1B	Login Confirm	S -> C	LoginConfirmPacket	outgoing	login flow	Character accepted
0xA9	Characters / Starting Locations	S -> C	CharactersStartingLocationsPacket	outgoing	login flow	Character list + starts
0xB9	Support Features	S -> C	SupportFeaturesPacket	outgoing	login flow	Enables client features
0x55	Login Complete	S -> C	LoginCompletePacket	outgoing	login flow	Enter world complete
0x22	Move Confirm	S -> C	MoveConfirmPacket	outgoing	movement flow	Movement ack
0x21	Move Deny	S -> C	MoveDenyPacket	outgoing	movement flow	Movement reject
0x78	Mobile Incoming	S -> C	MobileIncomingPacket	outgoing	world/entity sync	Nearby mobiles
0x20	Draw Player	S -> C	DrawPlayerPacket	outgoing	login/move flow	Draw controlled mobile
0x2E	Worn Item	S -> C	WornItemPacket	outgoing	equipment sync	Equipped visuals
0x24	Draw Container	S -> C	DrawContainerPacket	outgoing	container flow	Open container
0x3C	Add Multiple Items To Container	S -> C	AddMultipleItemsToContainerPacket	outgoing	container flow	Batched contents
0x88	Paperdoll	S -> C	PaperdollPacket	outgoing	character UI	Paperdoll open
0x11	Status Bar Info	S -> C	PlayerStatusPacket	outgoing	PlayerStatusHandler	Modern 7.x status payload
0xB2	Chat Command	S -> C	ChatCommandPacket	outgoing	ChatSystemService	Classic conference chat responses and UI updates
0x3A	Send Skills	S -> C	SkillListPacket	outgoing	PlayerStatusHandler	Full skill list with lock state
0x23	Dragging Of Item	S -> C	DraggingOfItemPacket	outgoing	item drag flow	Drag visual
0xAE	Unicode Speech Message	S -> C	UnicodeSpeechMessagePacket	outgoing	speech/system messages	Server speech
0xB0	Generic Gump	S -> C	GenericGumpPacket	outgoing	gump flow	Standard gump
0xDD	Compressed Gump	S -> C	CompressedGumpPacket	outgoing	gump flow	Compressed gump
0xF3	Object Information	S -> C	ObjectInformationPacket	outgoing	item/world sync	Item/object updates
0x76	Server Change	S -> C	ServerChangePacket	outgoing	map transition flow	Map/server boundary change
0x65	Weather	S -> C	SetWeatherPacket	outgoing	world presentation	Client 7.x still supports it
0x54	Play Sound Effect	S -> C	PlaySoundEffectPacket	outgoing	world presentation	Audio cue
0x70	Graphical Effect	S -> C	GraphicalEffectPacket	outgoing	world presentation	Classic effect
0xC0	Hued Effect	S -> C	HuedEffectPacket	outgoing	world presentation	Colored effect
0xC7	Particle Effect	S -> C	ParticleEffectPacket	outgoing	world presentation	Particle effect
0x7C	Relay	both	none	missing	none	Relevant in POL docs, not implemented in Moongate
0x16	Status Bar Info (old)	S -> C	none	missing	none	POL legacy status packet; Moongate uses modern 0x11 only
0x39	Group Remove / old chat	C -> S	none	missing	none	Not targeted for current client/runtime

Serialization

Outbound packets are serialized with SpanWriter in OutboundPacketSender.

• fixed packets typically pre-size buffer with Length
• variable packets can use dynamic writer growth
• packet logging can output hex dump when LogPacketData is enabled

Current notable outgoing packet classes:

• PlayerStatusPacket
  • modern 7.x status layout
  • reads effective mobile state from UOMobileEntity
• SkillListPacket
  • outgoing 0x3A
  • serializes the persisted mobile skill table in skill-id order
  • includes lock state, but not per-skill caps
• BookHeaderNewPacket
  • opens the classic book UI
  • toggles client writable mode per item

Source Generation

Moongate.Generators provides generated packet artifacts used by runtime:

• packet table registration code
• packet opcode constants (PacketDefinition partial)

This avoids manual opcode duplication and keeps registration centralized.

Listener Registration Generation

Server listener wiring is also source-generated.

Listener classes declare handled opcodes:

[RegisterPacketHandler(PacketDefinition.MoveRequestPacket)]
public class MovementHandler : BasePacketListener
{
    // ...
}

Moongate.Generators produces bootstrap code that calls RegisterPacketHandler<TListener>(container, opCode) for all discovered attributes.

This keeps:

• listener mapping explicit and compile-time validated.
• bootstrap code shorter and easier to maintain.
• runtime startup free from reflection-based handler scanning.

Game Event Listener Registration Generation

In addition to packet handler registration, Moongate also generates game-event listener subscriptions.

Listener classes decorated with [RegisterGameEventListener] are scanned at compile time. For each implemented IGameEventListener<TEvent>, generated bootstrap code subscribes the listener on IGameEventBusService.

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