FeatherMC/src/protocol/protocol.hjson

{
    types:
    {
        varint: {
            // native type
            type: int32_t

            // this is the max size. varint is 3 to 5
            size: 5
            
            // R/W: ReadVarInt, WriteVarInt
            method: VarInt
            
            // Alias types use ReadVarInt<T>
            generic: true
        }

        ProtocolState: {
            alias: varint
        }

        string: {
            type: std::string
            clientbound: {type: 'const std::string&'}

            method: String
            // requires count: e.g. string[256] 
            // generated C type will not be an array
            size: count
        }

        uuid: {
            type: MinecraftUUID
            size: 16
        }

        position: {
            type: BlockPos
            size: 8
            method: Position
        }

        direction: {
            type: Direction
            size: 1
            alias: varint
        }

        uint64: {type: 'uint64_t', size: 8}
        int64: {type: 'int64_t', size: 8}

        uint32: {type: 'uint32_t', size: 4}
        int32: {type: 'int32_t', size: 4}

        uint16: {type: 'uint16_t', size: 2}
        int16: {type: 'int16_t', size: 2}

        uint8: {type: 'uint8_t', size: 1}
        int8: {type: 'int8_t', size: 1}

        byte: {type: 'uint8_t', size: 1}

        // if no native type is specified,
        // it's assumed to be the type's name
        bool: {size: 1}

        float: {size: 4}
        double: {size: 8}
    }

    states :
    {
        Handholding : -1
        Play        : 0
        Status      : 1
        Login       : 2
    }

    messages :
    {
        handholding :
        {
            serverbound :
            {
                Handshake :
                {
                    id    : 0
                    vars  : 
                    {
                        protocolVersion : varint
                        serverIP        : string[255]
                        port            : uint16
                        intention       : ProtocolState
                    }
                }
            }
        }

        status :
        {
            clientbound :
            {
                Response :
                {
                    id    : 0
                    vars  : 
                    {
                        jsonResponse : string[32767]
                    }
                }

                Pong :
                {
                    id    : 1
                    vars  : 
                    {
                        timestamp : uint64
                    }
                }
            }

            serverbound :
            {
                Request :
                {
                    id    : 0
                    vars  : 
                    {
                    }
                }

                Ping :
                {
                    id    : 1
                    vars  : 
                    {
                        timestamp : uint64
                    }
                }
            }
        }

        login :
        {
            clientbound :
            {
                Disconnect :
                {
                    id    : 0
                    vars  : 
                    {
                        reason : string[32767]
                    }
                }

                Success :
                {
                    id    : 2
                    vars  : 
                    {
                        uuid     : string[32]
                        username : string[16]
                    }
                }
            }

            serverbound :
            {         
                Start :
                {
                    id    : 0
                    vars  : 
                    {
                        username : string[16]
                    }
                }
            }
        }

        play :
        {
            serverbound:
            {
                ChatMessage:
                {
                    id   : 0x03
                    vars :
                    {
                        message : string[256]
                    }
                }

                KeepAlive:
                {
                    id   : 0x0F
                    vars : 
                    {
                        id : int64
                    }
                }

                PlayerAction: {
                    id: 0x1A
                    enums: {
                        Action: {
                            .type: varint

                            StartBreakBlock: 0
                            AbortBreakBlock: 1
                            FinishedBreakBlock: 2
                            DropItemStack: 3
                            DropItem: 4
                            ReleaseUseItem: 5 # shoot array, finished eating, etc
                            SwapItemHands: 6
                        }
                    }
                    vars: {
                        action: Action
                        pos: position
                        direction: direction
                    }
                }
            }

            clientbound :
            {
                ChatMessage:
                {
                    id   : 0x0F
                    vars :
                    {
                        jsonData : string[32767]
                        position : uint8
                    }
                }

                JoinGame :
                {
                    id    : 38
                    vars  : 
                    {
                        entityId            : int32
                        gamemode            : uint8
                        dimension           : int32
                        seedHash            : uint64
                        maxPlayers          : uint8
                        levelType           : string[16]
                        viewDistance        : varint
                        reducedDebugInfo    : bool
                        enableRespawnScreen : bool
                    }
                }
                
                KeepAlive:
                {
                    id: 0x21
                    vars: {
                        id: int64
                    }
                }
				
				ChunkData:
				{
					id: 0x22
					vars: {
						chunkX: int32
						chunkZ: int32
						fullChunk: bool
						// bitmask for each 16x16x16 chunk section
						// LSB: section at y=0, bits for up to y=15
						chunkSections: varint
						//heightmaps: nbt
						
						// only if fullChunk == true
						biomes(fullChunk?): int32[1024]
						
						dataSize: varint
						data: byte[dataSize]
						
						//numBlockEntities: varint
						//blockEntities: nbt[numBlockEntities]
						
					}
				}
				
				PlayerInfo: {
					id: 0x34
					enums: {
						Action: {
                            .type: varint

							AddPlayer: 0
							UpdateGamemode: 1
							UpdateLatency: 2
							UpdateDisplayName: 3
							RemovePlayer: 4
						}
                        # this could be a global enum
                        Gamemode: {
                            .type: varint

                            Survival: 0,
                            Creative: 1,
                            Adventure: 2,
                            Spectator: 3
                        }
					}
                    vars: {
                        action: Action
                        numPlayers: varint
                        players(#numPlayers): {
                            uuid: uuid
                            .switch(action): {
                                AddPlayer: {
                                    name: string[16]
                                    numProps: varint
                                    properties(#numProps): {
                                        name: string[32767]
                                        value: string[32767]
                                        isSigned: bool
                                        signature(isSigned?): string[32767]
                                    }
                                    gamemode: Gamemode
                                    ping: varint
                                    //hasDisplayName: bool
                                    //displayName(hasDisplayName?): chat
                                }

                                UpdateGamemode: {
                                    gamemode: Gamemode
                                }

                                UpdateLatency: {
                                    # in ms
                                    ping: varint
                                }

                                UpdateDisplayName: {
                                    //hasDisplayName: bool
                                    //displayName(hasDisplayName?): chat
                                }

                                RemovePlayer: {}
                            }
                        }
                    }
				}

                PlayerPositionAndLook:
                {
                    id: 0x36
                    enums: {
                        RelativeFlags: {
                            .type: byte
                            
                            X: 1,
                            Y: 2,
                            Z: 4,
                            Y_ROT: 8,
                            X_ROT: 16,
                        }
                    }
                    vars: {
                        x: double
                        y: double
                        z: double
                        // xRot is yaw, yRot is pitch
                        xRot: float
                        yRot: float
                        flags: RelativeFlags
                        id: varint
                    }
                }

                SpawnPosition:
                {
                    id: 0x4E
                    vars: {
                        location: position
                    }
                }
            }
        }
    }
}