Classic Protocol Extension/Proposals

Template

Add your proposal at the end of the page. Please use existing extensions as your guide to formatting. Please sign your proposals and comments by ending it with ~~~~.

===ExtensionName===
:Proposed by ~~~~
:Brief summary of the extension.
:'''Motivation''': Explain why this is needed or how it is useful.
:'''Client Behavior''': Detailed description of all new behavior that game clients need to implement in order to support this extension. Consider interaction with other extensions.
:'''Server Behavior''': Detailed description of all new behavior that game servers need to implement in order to support this extension. Consider interaction with other extensions.
:(Packet definitions, remarks, illustrations, and data tables go here)
:(Comments go here, please sign them)

Proposals

PlaySound

Proposed by !!!WARLOCK!!!

This extension allows server to play custom sound and musics on client.

Motivation: Servers can play custom musics or sound effects just in time or when something changes. Useful for gamemodes such as zombie survival, Servers can play zombie moaning sound while zombies are close to players. Player join and leave sounds, Kill streak sounds for games such as CTF, Radio and DJ class for players and sound effects for explosions and player deaths.

Client Behavior: Client must download and load, or load the sound directly from the URL with the ID. Client must be able to download any time after MapFinalize has sent. If the URL is empty then the Client must unload the sound with that ID. Client must unload the sound and load a new one if there's a sound with existing ID. Client must be able to play the sound right after receiving the PlaySound packet. The last playing sound can not be ignored or stopped when a new sound is going to be played. Files type must be in .WAV, otherwise they're ignored. Client must ignore downloading the existing files from Server if they're saved in drive. Client must not change the volume of all environments (Place/Destroy, Walk sounds) on SetVolume packet. Client must change a local variable for volume of next playing sound on SetVolume packet.

Server Behavior: Server must ignore sending the same url multiple times. Server can not send quick loops of sound due to network speed and client crash possibility. It's better to load all of required sounds after map load for better performance. Server must not send high sized file cause of time and speed it takes for download. Files type must be in .WAV, otherwise they're ignored. Server can change the volume before playing a sound. For a better networking, It's suggested to not send PlaySound instead of changing volume to zero.

LoadSound packet

Server to client

Packet ID	Field Name	Field Type	Example	Notes
0x?? (??)	ID	byte	143	Gives the URL an ID.
	URL	string	http://site.com/firstblood.wav	Address to a .WAV file, put this empty for unload.
	Total Size:	66 bytes

PlaySound packet

Server to client

Packet ID	Field Name	Field Type	Example	Notes
0x?? (??)	ID	byte	125	Plays the sound saved as ID.
	Total Size:	2 bytes

SetVolume packet

Server to client

Packet ID	Field Name	Field Type	Example	Notes
0x?? (??)	Percent	byte	87	Set the next playing sound(s) volume to a Percentage.
	Total Size:	2 bytes

ClientRedirection

Proposed by Sysr q (talk) 10:17, 12 May 2014 (UTC)

This extension allows servers to give clients a redirection to a separate, possibly "private" server.

Motivation: Allowing servers to redirect clients would be useful in several cases. Allowing a singular "hub" server to redirect players to various external (but related) servers depending on the gamemode they wish to play would allow tightly integrated networks. If servers are using an external "balancer" or some sort of Minecraft-aware proxy, the server could signal the proxy move its connection on the client's behalf to another server.

Client Behavior: Clients should be ready to receive a ClientRedirection packet any time after they receive a LevelFinalize packet. When clients receive a ClientRedirection packet, they should prompt the user with a message indicating the server they're being redirected too, and allow the user to continue or quit. Non-player clients (e.g., proxies) have the option of silently reconnecting on the client's behalf. Clients should then open a new connection to the newly redirected server, and begin standard negotiation protocol.

Server Behavior: Servers should only send a ClientRedirection packet after the they have sent a LevelFinalize packet. They should ensure the new server the client is being redirected to exists, and preferably is online and available.

ClientRedirection packet

Server to client

Packet ID	Field Name	Field Type	Example	Notes
0x?? (??)	Address	string	mc.example.org	Can be an IP address (IPv4/IPv6) or a hostname.
	Port	int	25565
	Name	string	Joe Blogg's Freebuild	(optional) User-friendly name to be displayed in user prompt.
Total Size:	133 bytes

ColorCodeControl

Proposed by F (talk) 22:00, 28 August 2014 (UTC)

Gives servers an option to allow players to type in color codes, and a way to render & character in chat.

Motivation: Allow players to type in color codes and to use & in chat.

Client Behavior: When this extension is mutually supported, treat character sequence && as meaning "draw an & character", without modifying current color. Do not allow & to be typed or pasted into chat unless ColorCodeControl packet has been received with AllowColorCodes set to 1.

Server Behavior: When this extension is mutually supported, server may send ColorCodeControl packet to allow client to type or paste color codes. Server should treat && as described above.

ColorCodeControl packet

Server to Client

Packet ID	Field Name	Field Type	Example	Notes
??	AllowColorCodes	byte	0	0 = disallow 1 = allow
Total Size:	2 bytes

UnicodeChat

Proposed by F (talk) 22:48, 28 August 2014 (UTC)

Expands character encoding beyond ASCII. There are three ways to go about this:

1. Expand charset to 256 characters using Win-1252.
   • Pro: Easiest to implement in clients (few changes to FontRenderer needed) and servers (no multibyte character support needed).
   • Pro: No new packets needed.
   • Pro: Easy to create custom fonts.
   • Pro: Easy for servers to maintain compatibility with legacy clients, since only 128 characters need to be remapped, most of which have decent ASCII matches.
   • Pro: Low resource use (low RAM and VRAM use, no additional CPU use, small font file).
   • Con: Still only 256 characters. Only covers Latin-derived (English and Western/Central European) languages and common symbols.
2. Expand charset to Unicode Basic Multilingual Plane (BMP) with UCS-2 fixed-length encoding.
   • Pro: Lots of characters (~65k) covering most languages and symbols.
   • Pro: Not too hard to implement (characters still fixed-width, native support in WinAPI / Java / C#).
   • Pro: Free fonts available that covers all characters.
   • Con: New renderer (possibly third-party library) needed for rendering.
   • Con: Higher resource use (higher RAM and VRAM use, more CPU use, large font file).
   • Con: Very hard to create custom fonts.
   • Con: Still does not cover all characters.
   • Con: Hard for servers to maintain compatibility with legacy clients.
   • Con: Always uses 2 bytes per character for transmission (twice as much as ASCII/CP-1252).
3. Expand charset to Unicode Basic Multilingual Plane (BMP) with UTF-8 variable-length encoding.
   • Pro: Lots of characters (~65k) covering most languages and symbols.
   • Pro: Not too hard to implement (characters can be freely converted to/from UCS-2, which is natively support in WinAPI / C#).
   • Pro: Free fonts available that covers all characters.
   • Pro: Uses 1 byte per character for transmission, most of the time.
   • Con: New renderer (possibly third-party library) needed for rendering.
   • Con: Higher resource use (higher RAM and VRAM use, more CPU use, large font file).
   • Con: Hard to create custom fonts (unless some fallback rules are implemented).
   • Con: Still does not cover all characters.
   • Con: Hard for servers to maintain compatibility with legacy clients.
4. Expand charset to full Unicode with UTF-8 variable-length encoding. Includes all the supplemental Unicode planes.
   • Pro: Widely used in other software.
   • Pro: Theoretically covers all languages and symbols.
   • Pro: Uses 1 byte per character for transmission, most of the time.
   • Con: Does not actually cover all languages and symbols due to non-existence of 100% fonts.
   • Con: Hard to find free fonts that extend beyond the BMP.
   • Con: Harder to work with strings (due to variable-width characters).
   • Con: Third-party library needed for rendering.
   • Con: Highest resource use (highest RAM and VRAM use, most CPU use, largest font files).
   • Con: Hardest to implement (no native support in WinAPI / C#).
   • Con: Hard to create custom fonts (unless some fallback rules are implemented).
   • Con: Hard for servers to maintain compatibility with legacy clients.

SelectionCuboid v2

Proposed by FabTheZen, classic1234 and Rayne

Motivation: Allows the server to not only highlight parts of a world, but also determine whether those regions are walk through or not. This could be used to disallow players to walk inside restricted areas or zones which they are not allowed to build in. It could also be used as a jail when accompanied with the '-hax' option.

Client behavior: The client must receive the SelectionCuboid extension with version 2. It must also determine whether any selections on the map walk through or not.

Server behavior: The server behaves the same way SelectionCuboid v1 does.

MakeSelection packet v2

Server to Client

Packet ID	Field Name	Field Type	Example	Notes
0x?? (??)	SelectionID	byte	0	Numeric ID of the selection. Between 0 and 127.
	Label	string	SomeZone	Text label associated with the selection
	StartX	short	1	X coordinate of the starting point
	StartY	short	2	Y coordinate of the starting point
	StartZ	short	3	Z coordinate of the starting point
	EndX	short	5	X coordinate of the ending point
	EndY	short	6	Y coordinate of the ending point
	EndZ	short	7	Z coordinate of the ending point
	Red	short	255	Between 0 and 255.
	Green	short	34	Between 0 and 255.
	Blue	short	128	Between 0 and 255.
	Opacity	short	255	0 = fully transparent 255 = fully opaque
	Walkthrough	byte	0	0 = Not walkthrough 1 = Walkthrough
Total Size:	87 bytes

Player Animation

Proposed by ByteBit

Let the player to do certain actions/animations on the client

Motivation: Other players will be able to see the block another is holding or whether one placed a block or not. It makes the game's feel more realistic, because blocks don't pop out a no where.

Client Behavior: On recieve the client should perform the actions required for the animation.

Server Behavior: The server may send the packet if needed any time after the map is send.

AnimatePlayer packet

Server to Client

Packet ID	Field Name	Field Type	Example	Notes
0xAC (172)	Animation Type	byte	1	Specifies what animation to perform (0: Hold block; 1: Set block; 2: Destroy block; 3: Player name visibility)
	Player ID	byte	1	What player to perform this animation on
	Additional byte	byte	49 (Obsidian)	Needed for specific animations (Block type for 0,1 and 2; for 3: true(1)/false(0))
Total Size:	3 bytes

PlayerHealth

Proposed by Apotter96 (talk) 02:29, 26 July 2015 (UTC)alex96

Gives players life count that is controlled by the server and reflected by the client at the top left of the game screen. The server.

Motivation: RPG and Gun games can go more extensive if they wish with lives.

Client Behavior: Display player's lives at the top left of screen when the server sends the packet. On player connect, the server needs to tell the client the max amount of lives the player can have, in between 5 and 20. May also dictate how many lives the server is allowed to send. Both need to check with the other end so they can comply together.

Server Behavior: At any time the server can send the packet telling the client the amount of lives the player has. Once a player connects, the server needs to tell the client how many lives the player is allowed to have, in between 5 and 20. Both need to check with the other end so they can comply together.

UpdateLives packet

Server to client

Packet ID	Field Name	Field Type	Example	Notes
0x?? (??)	Lives	int	15	How many lives the player has
	MaxLives	int	15	The Max amount of lives
	Total Size:	2 bytes

UpdateLives packet

Client to server

Packet ID	Field Name	Field Type	Example	Notes
0x?? (??)	MaxLives	int	15	The Max amount of lives
	Total Size:	2 bytes

(Comments go here, please sign them)

ExtPlayerList v3

Proposed by Cheesse

This extension builds upon the current version and adds the ability to change the visibility of name tags.

Motivation: Provides more flexibility in naming of players and loading of skins, autocompletion, and player tab-list display. Separates tracking of in-game entities (spawned player models) and names on the player list. ExtAddPlayerName/ExtRemovePlayerName packets take over managing the player names list (tab-list), and ExtAddEntity3/DespawnPlayer packets are used only to manage in-game entities.Provides more flexibility in naming of players and loading of skins, autocompletion, and player tab-list display. Separates tracking of in-game entities (spawned player models) and names on the player list. ExtAddPlayerName/ExtRemovePlayerName packets take over managing the player names list (tab-list), and ExtAddEntity3/DespawnPlayer packets are used only to manage in-game entities.

Client Behavior: When ExtAddPlayerName packet is received for an unused NameID, a new name must be added to the player-name list. When receiving ExtAddPlayerName packet for an already-listed NameID, client must update its ListName, GroupName, and GroupRank. Names on the player-name list should be grouped by GroupName in the player-name list. Names within a GroupName should be sorted by GroupRank (in ascending order). Names with the same GroupName and GroupRank should be sorted alphabetically by ListName. Color codes may be either drawn or stripped from ListName, GroupName, and InGameName. Player-name list must persist when client changes worlds/maps.

When an ExtAddEntity3 packet is received, it must be treated as the SpawnPlayer packet. A player model must be spawned in-game at the given location, with InGameName text drawn above it. Skin should be loaded using the given SkinName for a player name. If SkinName appears to be a player name, skin should be downloaded from the default skin server. If SkinName appears to be a full URL to a PNG image (starts with http:// or https:// and ends with .png) then skin should be downloaded from that URL. If image is correctly sized/proportioned to use as a skin for the current model, it should be used. If a blank or unrecognized value is given for SkinName, or if given image could not be downloaded or used, then the default skin should be used. The client must also set the visibility according to NameVisibility and the collision ability of the entity according to CanCollide. When client receives ExtAddEntity3 packet for an already-spawned player, a duplicate entity must not be spawned and existing entity's position must not be changed. Instead their InGameName, SkinName, NameVisibility, and CanCollide attributes must be updated. If a negative EntityID is given for ExtAddEntity3, client must update player's own spawn point, InGameName, and SkinName. If any undefined value is given in the NameVisibility or CanCollide fields, the client should ignore these fields. The client must ignore regular SpawnPlayer packets, if any are received.

When a standard DespawnPlayer packet is received for a recognized EntityID, player model must be removed from a world. When ExtRemovePlayerName packet is received for a recognized NameID, their name must be removed from player-name list. Packets with out-of-range or unrecognized NameIDs must be ignored.

In-game entities must never be affected by ExtAddPlayerName or ExtRemovePlayerName packets. Player name list must never be affected by ExtAddEntity3 or DespawnPlayer packets.

Server Behavior: Unique NameID between 0 and 255 should be assigned to every online player or every player on a map for each map. When a new player connects to the server or joins a new map, ExtAddPlayerName must be sent. GroupName and GroupRank can be used in any way, for example to group players by map/world or rank/class/faction. Server must use ExtAddEntity3 in place of standard SpawnPlayer packet. Server should re-send ExtAddPlayerName packet, using the identical NameID, when player's ListName, GroupName, or GroupRank change. Server must reliably send an ExtRemovePlayerName packet when the player disconnects. Color codes are permitted in ListName, GroupName, and InGameName.

This extension only replaces the ExtAddEntity2 packet of the ExtPlayerList extension version 2. Thus, only the ExtAddEntity3 packet is shown here.

ExtAddEntity3 packet

Server to client

Packet ID	Field Name	Field Type	Example	Notes
0x?? (??)	EntityID	byte	5	Between 0 and 127
	InGameName	string	&cNotch	Player name to be shown in-game hovering above the player.
	SkinName	string	Notch	Name of the skin that should be used by the client. Could also be a URL to a PNG image.
	SpawnX	short	1	X coordinate (32 units per block) of entity's spawn location.
	SpawnY	short	2	Y coordinate (32 units per block) of entity's spawn location.
	SpawnZ	short	3	Z coordinate (32 units per block) of entity's spawn location.
	SpawnYaw	byte	4	Orientation (left-right) at the entity's spawn location.
	SpawnPitch	byte	5	Orientation (up-down) at the entity's spawn location.
	NameVisibility	byte	6	Visibility of the InGameName of the entity. Obstacles can be blocks or other entities. 0 = (Default) Visible only by hovering the cursor over the entity within view. Ignores any obstacles in the way. 1 = Visible only by hovering the cursor over the entity within view. Invisible when obstacles block the entity. 2 = Always visible within view (name tag shrinks over distance). Ignores any obstacles in the way. 3 = Always visible within view (name tag shrinks over distance). Invisible when obstacles block the entity. 4 = Always visible anywhere (name tag does not shrink over distance). Ignores any obstacles in the way. 5 = Always visible anywhere (name tag does not shrink over distance). Invisible when obstacles block the entity. 6 = Never visible.
	CanCollide	byte	0	0 = (default) Can collide with the player. 1 = Cannot collide with the player.
	Opacity	byte	255	From 0-255, the overall opacity of the entity model.
Total Size:	140 bytes

(Comments go here, please sign them)

HackControl v2

Proposed by Cheesse

This extension allows more control over the abilities of players.

Motivation: To gain control over the movement and action abilities of players.

Client Behavior: Client must be able to receive HackControl2 packets at any time and apply the changes defined in the packet immediately. Any value may be given in any field to allow or adjust an ability. If a negative value is given in any field, the client should set that value to its default. If 0 is given in any field, the client must deactivate that ability and prevent its use by the player unless otherwise stated.

Server Behavior: Server may send HackControl2 packets to successfully connected clients at any time.

HackControl2 packet

Server to client

Packet ID	Field Name	Field Type	Example	Notes
0x?? (??)	FlySpeed	byte	0	This value is divided by 25 and multiplied by the default speed of flight to get the custom speed of flight. A value of 255 means there are no restrictions on flight. A value of 0 means flight is not allowed.
	NoClip	byte	0	0 = Prevent no-clipping 1 = Allow no-clipping
	WalkSpeed	byte	64	This value is divided by 25 and multiplied by the default walking speed to get the custom walking speed. A value of 255 means there are no restrictions on walking speed. A value of 0 means the player is not allowed to walk.
	RunSpeed	byte	16	This sets the speedhacking capabilities of the player. This value is divided by 25, then added to 1, then multiplied by the default walking speed to get the custom running speed. A value of 255 means there are no restrictions on running speed. A value of 0 means the player is not allowed to run.
	AllowRespawn	byte	1	0 = Prevent respawning 1 = Allow respawning
	PointOfView	byte	0	0 = First-person view 1 = Third-person behind view 2 = Third-person front view Setting this field to a defined value will prevent the player from changing their point of view. Setting it to an undefined value will allow the player to switch points of view.
	JumpHeight	byte	40	Maximum height in player units of the player's normal jump. A value of 0 means the player is not allowed to jump. A value of 255 means there are no restrictions on jump height.
	SuperJumpHeight	byte	100	Maximum height in player units of any other jump abilities the player has, like using speed to get a higher jump. A SuperJumpHeight value of 0 means the player is not allowed to superjump. A value of 255 means there are no restrictions on jump height.
Total Size:	9 bytes

(Comments go here, please sign them)

MessageTypes v2

Proposed by Cheesse

This extension adds new ways of presenting information to the player.

Motivation: To allow the server to send messages in different places and for limited times.

Client Behavior: Client must interpret the PlayerID field of the standard Message packet as the Message Type field. Certain values in this field correspond to different locations for messages on the screen. Any undefined values in this field should be ignored and presented as regular chat messages. Without mutual server-client support for this extension, this field should be ignored.

Server Behavior: Server may use the PlayerID field of the Message packet to have that message placed at a certain location on the player's screen.

MessageType Value	Meaning	Message Placement
0	Chat	In the chatbox.
1	Status1	At the top right of the screen.
2	Status2	At the top right of the screen below Status1.
3	Status3	At the top right of the screen below Status2.
11	BottomRight1	At the bottom right of the screen.
12	BottomRight2	At the bottom right of the screen above BottomRight1.
13	BottomRight3	At the bottom right of the screen above BottomRight2.
45	LeftHotbar	On top of the hotbar aligned to the left.
54	RightHotbar	On top of the hotbar aligned to the right.
100	BigAnnouncement	In large font slightly above the center of the screen.
200	SmallAnnouncement	Near the center of the screen below BigAnnouncement.

This extension does not define any new packets.

(Comments go here, please sign them)

ExtMapInfo

Proposed by Cheesse

This extension allows the server to send the client some of the map's metadata and other information

Motivation: To allow clients to save metadata with the maps they choose to save. This extension can also be modified to add more features to maps.

Client Behavior: Client must be able to receive FinalMapInfo packets at any time after a LevelInitialize packet has been received and before a FinalMapInfo packet has been received. Client should store the values in these fields in memory to be used later. The metadata defined in these fields come from those defined in the ClassicWorld file definitions. Client should ignore any LevelFinalize packets recieved.

Server Behavior: Server must send FinalMapInfo packets with the correct values after it has finished sending the client the raw block data after sending a LevelInitialize packet. The server should not send this packet at any other time. The server should never send any LevelFinalize packets to the client.

FinalMapInfo packet

Server to client

Packet ID	Field Name	Field Type	Example	Notes
0x?? (??)	"FormatVersion	byte	1	The FormatVersion is currently set to 1.
	"MapName"	string	main	The name of the map.
	"UUID"	byte array [16]	abcdefghijklmnop	The UUID of the map.
	"XSize"	short	128	The length of the map in the X dimension.
	"YSize"	short	128	The length of the map in the Y dimension.
	"ZSize"	short	128	The length of the map in the Z dimension.
	"CreatedBy"	string	Cheesse	The name of the author of the map. This should be an existing Classicube username.
	"MapGenSoftware"	string	Mapbuilder	The name of the software used to generate the map.
	"MapGenName"	string	Flat	The name of the generator function used to generate the map.
	"TimeCreated"	long	1234567890	The UTC Unix timestamp of the time the map was generated.
	"TimeLastModified"	long	1234567890	The UTC Unix timestamp of the time the map was last modified.
Total Size:	298 bytes

(Comments go here, please sign them)

BlockDefinitionsExt2

Proposed by Goodly.

This extension allows servers to define more properties for the custom blocks provided by BlockDefinitions.

Motivation: To allow for better custom blocks to be created.

Client Behavior: This extension depends on BlockDefinitions extension and BlockDefinitionsExt extension, and must only be enabled if BOTH extensions are mutually supported. Client should be able receive any number of DefineBlockExt2 packets during the level loading process (after receiving LevelInitialize and until receiving LevelFinalize packets). However, dependent on client, this can be sent after level loading (Some clients might just find it more extensible than others).

Client must be able to accept and render blocks as specified in DefineBlockExt2 packets. Clients must accept any valid definitions with BlockID between 1 and 254, inclusive. If a new definition is accepted for an already-defined BlockID, the old definition should be replaced.

DefineBlockExt2 Packet

Server to Client

Field Name	Field Type	Example	Notes
RandomOffset	byte	1	Whether or not the block is randomly offset. 0 = Not offset (No change). 1 = Randomly offset on the X and Z axis from -3/16 to 3/16. 2 = Randomly offset on the Y axis from -3/16 to 3/16. 3 = Randomly offset on the Y axis from -3/16 to 0. 4 = Randomly offset on the X, Y and Z axis from -3/16 to 3/16 5 = Randomly offset on the X and Z axis from -3/16 to 3/16 and randomly offset on the Y axis from -3/16 to 0. Note: This only effects blocks which have the "Shape" as 0 (sprite)
FatSprite	byte	1	Whether or not the sprite is stretched closer to the edge of the block, similar to premium. 0 = Not fat (No change). 1 = The corners of the sprite are stretched from 0.8 to 15.2. (Instead of the original values of 2.50 to 13.5.) Note: This only effects blocks which have the "Shape" as 0 (sprite)
Selectable	byte	0	Whether or not the block/liquid becomes highlighted when pointed at it (Like how liquids are not breakable or selectable by default). 0 = Not select-able. 1 = Selectable. (No change)
Replaceable	byte	1	Whether or not the client is able to reach through and place blocks inside of the the block/liquid. 0 = No change from original behavior 1 = The block can be reached through when placing blocks and can be overwritten if a block is placed inside of it. (Similar to liquid)
Red	byte	255	Red component that the block is multiplied by.
Green	byte	109	Green component that the block is multiplied by.
Blue	byte	255	Blue component that the block is multiplied by.
Total Size:	8 bytes

SoundControl

Proposed by Cheesse

This extension allows the client to play music and sounds defined by the server.

Motivation: To create a more stimulating experience by adding custom sounds and music to the game.

Client Behavior: The client must be able to receive any packets defined by this extension at any time. It must not play any music unless ordered by the server. It must dispose of any unloaded custom audio or store it in an unusable format. Loops must be played on a loop. Defined BlockSounds must be available for use by custom block types, and any local placement or deletion of a block or any local footsteps on that block that uses custom BlockSounds should have the custom sound played simultaneously. Sounds being played by the PlayEntityLoopSource and PlayEntitySFX must have their sources move with the entity. The client should play SFX ordered by the server immediately after receiving any PlaySFX, PlayLevelSFX, or PlayEntitySFX packet. If the client receives an undefined value for any packet, that packet should be ignored. When a custom audio file is defined within a default slot, the client should return the default audio to that slot when it becomes undefined.

Server Behavior: The server may send any packets defined by this extension at any time, however, it is recommended that the server defines all sounds during the level loading phase. All audio defined only for a specific level must be unloaded by the server upon client leaving the level. Defined custom BlockSounds must be available for use by custom blocks. The PlayEntityLoopSource and PlayEntitySFX packets allow servers to attach the source of a sound to an entity. This makes it easier for servers to play "moving" sounds without having to send too much data. All audio files linked by the server must be in .ogg format. All loops MUST have a length longer than 10 seconds. The server is responsible for not infringing upon copyright and licensing.

DefineMusic packet

Server to client

Packet ID	Field Name	Field Type	Example	Notes
0x?? (??)	SongID	byte	0	Valid IDs are from 0-255. IDs for default music are as follows: 0=calm1, 1=calm2, 2=calm3, 3=hal1, 4=hal2, 5=hal3, 6=hal4. Default music may be redefined by the server.
	SongSource	string	http://www.abc.com/song.ogg	The location of the music file online. The link must lead to a .ogg file. If this field contains only "X" (case-sensitive), the music of the SongID within the SongCategory must be unloaded. If this field contains only "A" (case-sensitive), all music defined within the SongCategory must be unloaded. Otherwise, the client should do nothing.
	Total Size:	66 bytes

DefineBlockSound packet

Server to client

Packet ID	Field Name	Field Type	Example	Notes
0x?? (??)	BlockSoundID	byte	8	This is a bitfield where the 14 most significant bits represent the "block type" (such as wood, metal, grass) and the 2 least significant bits represent IDs for each individual sound (think of the different sounds for stone blocks).
	BlockSoundSource	string	http://www.abc.com/water.ogg	The location of the loop file online. The link must lead to a .ogg file. If this field contains only "X" (case-sensitive), the audio for that specific BlockSoundID must be unloaded. If this field contains only "A" (case-sensitive), all sounds with the same "block type" must be unloaded. Otherwise, the client should do nothing.
Total Size:	66 bytes

DefineLoop packet

Server to client

Packet ID	Field Name	Field Type	Example	Notes
0x?? (??)	LoopID	byte	3	Valid IDs are from 0-255.
	LoopSource	string	http://www.abc.com/cavenoise.ogg	The location of the loop file online. The link must lead to a .ogg file. If this field contains only "X" (case-sensitive), the audio for the LoopID must be unloaded. Otherwise, the client should do nothing.
Total Size:	66 bytes

DefineSFX packet

Server to client

Packet ID	Field Name	Field Type	Example	Notes
0x?? (??)	SFXID	byte	0	Valid IDs are from 0-255.
	SFXSource	string	http://www.abc.com/killstreak.ogg	The location of the music file online. The link must lead to a .ogg file. If this field contains only "X", the sound of the SFXID must be unloaded. Otherwise, the client should do nothing.
Total Size:	66 bytes

PlayMusic packet

Server to client

Packet ID	Field Name	Field Type	Example	Notes
0x?? (??)	SongID	byte	0	SongID must be defined.
	Volume	byte	100	From 0-200, the volume at which to play the music.
	Fade	byte	0	This is a bitfield from 0-7 with 7 being the most significant bit. Bits 0-3 are for the period taken for the song to fade in. Valid values for this are from 0-15 (in seconds). Bits 4-7 are for are for the fade out, and the values for this are from 0-15 (in seconds).
	Loop	byte	0	From 0-254, the position from the start, in tenths of a second, at which the music should return after the end is reached. If this field is 255, then the song does not loop.
Total Size:	5 bytes

PlayLevelLoopSource packet

Server to client

Packet ID	Field Name	Field Type	Example	Notes
0x?? (??)	LoopID	byte	0	LoopID must be previously defined. If a different loop was playing at a position defined by PositionX, -Y, and -Z, then the client must replace that loop with this one.
	Volume	byte	100	From 0-200, the volume at which to play the sound effect. If the volume is set to 0, the client must not play any loops at that position, especially if one was playing there before.
	PositionX	short	20	The X-coordinate of the position of the source of the loop on the level (in player coordinates).
	PositionY	short	20	The Y-coordinate of the position of the source of the loop on the level (in player coordinates).
	PositionZ	short	20	The Z-coordinate of the position of the source of the loop on the level (in player coordinates).
Total Size:	9 bytes

PlayEntityLoopSource packet

Server to client

Packet ID	Field Name	Field Type	Example	Notes
0x?? (??)	LoopID	byte	0	LoopID must be previously defined. If a different loop was playing from an entity with ID EntityID, the client must replace that loop with this one.
	Volume	byte	100	From 0-200, the volume at which to play the sound effect. If the volume is set to 0, the client must not play any loops from that entity, especially if one was playing there before.
	EntityID	byte	1	The ID of the entity from which the loop should be played.
Total Size:	4 bytes

PlaySFX packet

Server to client

Packet ID	Field Name	Field Type	Example	Notes
0x?? (??)	SFXID	byte	0	SFXID must be defined.
	Volume	byte	100	From 0-200, the volume at which to play the sound effect.
Total Size:	3 bytes

PlayLevelSFX packet

Server to client

Packet ID	Field Name	Field Type	Example	Notes
0x?? (??)	SFXID	byte	0	SFXID must be defined.
	Volume	byte	100	From 0-200, the volume at which to play the sound effect.
	PositionX	short	100	The X-coordinate of the position of the source of the loop on the level (in player coordinates).
	PositionY	short	100	The Y-coordinate of the position of the source of the loop on the level (in player coordinates).
	PositionZ	short	100	The Z-coordinate of the position of the source of the loop on the level (in player coordinates).
Total Size:	9 bytes

PlayEntitySFX packet

Server to client

Packet ID	Field Name	Field Type	Example	Notes
0x?? (??)	SFXID	byte	0	SFXID must be defined.
	Volume	byte	100	From 0-200, the volume at which to play the sound effect.
	EntityID	byte	3	The ID of the entity from which the sound effect should be played.
Total Size:	4 bytes

(Comments go here, please sign them)

WebSocketsSupport

Proposed by Maxouf0x (talk) 06:18, 3 August 2017 (UTC)

Add websocket support to the minecraft classic protocol.

Motivation: Make web clients without having to use webtcp.

Client Behavior: Clients that use web socket must send a normal HTTP GET request to http://<server IP>:<server port>/connect, When the client recive the redirect, it must open a websocket connection to the recived URL, and continue with the normal protocol, wrapped in a websocket.

Server Behavior: Server supporting websockets must check if the client has sent an HTTP GET request before sending the Server Identification package. If the client has sent an HTTP GET request to /connect, the web socket integration is disabled, but implemented, the server must respond with a 503 error code. If the websocket integration is enabled, the server must respond with a 302 code, redirecting to http://<server IP>:<server Port/Other port>/game. When the server recives a websocket connection to http://<server IP>:<server Port/Other port>/game, it must continue with the normal protocol, wrapped in a websocket.

The port used to request /connect is the same as the game port, so that this doesn't break the current heartbeat system.

This extension does not define any new packets.

(Comments go here, please sign them)

what? WebSockets are already supported.

TheAwesome98 (talk) 17:23, 6 November 2021 (UTC)

ExtDirection

Proposed by Cheesse

Increases the precision of direction data sent in all player position/orientation packets.

Motivation: Improve the precision of player rotation for servers that require high precision.

Client Behavior: The client must write unsigned shorts instead of bytes for the Yaw and Pitch fields of the PositionAndOrientation packet and any other packet that contains entity direction data.

Server Behavior: The server must write unsigned shorts instead of bytes for the Yaw and Pitch fields of the SpawnPlayer, PositionAndOrientation, PositionAndOrientationUpdate, and OrientationUpdate packets and any other packet that contains entity direction data.

This extension does not define any new packets.

ClientRedirection r2

Proposed by Galaxtone (talk) 05:32, 21 January 2019 (UTC)

The extensions allows servers to redirect clients to other servers.

Motivation: Allowing servers to redirect clients to other trusted sub-servers or a completly different server, Useful for hub servers leading to smaller sub-servers and even for sudden creation of private servers to connect to, and for the proxies themselves implement extension support.

Client Behavior: After extension negotiation, the client must send a Redirection packet (Specifies the redirecting server, blank if directly connected) to the server, afterwards the client must be able to receive a Redirection packet at any time, upon receiving the packet (Ignoring if blank), the client may deny the redirection by doing nothing, otherwise the client must disconnect from the server and reconnect to the specified server.

Server Behavior: After extension negotiation, the server must wait for a Redirection packet from compatible clients before sending level data, afterwards the server may then send the Redirection packet at any time.

Redirection packet

Bidirectional

Packet ID	Field Name	Field Type	Example	Notes
0x?? (??)	Server Hash	String	226fb815f216daf4d0ef653bc32c6b89	32 base-36 characters.
Total Size:	65 bytes

Note: This is the second revision of this extension proposal, not the second version of the extension.

DefineQuad

Proposed by Cybertoon

This extension allows you to define extra quads for a block.

Motivation: This would allow blocks that have more than one quad. So-called "block model".

Client Behavior: The client would render the extra quads given by this packet for a block, with the textures defined by this packet. Requires support for BlockDefinitionsExt. If the block is discarded with RemoveBlockDefinition, all Quads defined by this packet must also be discarded. If the client supports multiple collisions, if this packet defines collisions, use those instead. If client doesn't, or if none are defined, use the bounds defined in BlockDefinition. If "render" is set to false, this quad will only be used for bounds. If both are false, do nothing. If client doesn't support multiple collisions in a block, do nothing if render is set to false.

Server Behavior: If client supports extension, send the client the quads, starting with the second quad, then the next, so forth and so forth. This packet must be sent after the block has already been defined.

DefineQuad packet

Packet ID	Field Name	Field Type	Example	Notes
0x?? (??)	BlockID	byte	0	The ID of the block this Quad belongs to. Between 1 and 255.
	QuadID	byte	0	Refers to a terrain.png tile. Between 0 and 255 (unsigned). The ID of the extra quad being defined. Changing Quad 0 will change the quad defined in the BlockDefinition, and the bounds defined there will be the bounding box unless multiple bounding boxes are supported by client.
	TopTextureId	byte	0	Refers to a terrain.png tile. Between 0 and 255 (unsigned). Can be same as other texture IDs. This is the texture ID for the Y = 1 face.
	LeftTextureId	byte	0	Refers to a terrain.png tile. Between 0 and 255 (unsigned). Can be same as other texture IDs. This is the texture ID for the X = 0 face.
	RightTextureId	byte	0	Refers to a terrain.png tile. Between 0 and 255 (unsigned). Can be same as other texture IDs. This is the texture ID for the X = 1 face.
	FrontTextureId	byte	0	Refers to a terrain.png tile. Between 0 and 255 (unsigned). Can be same as other texture IDs. This is the texture ID for the Z = 0 face.
	BackTextureId	byte	0	Refers to a terrain.png tile. Between 0 and 255 (unsigned). Can be same as other texture IDs. This is the texture ID for the Z = 1 face.
	BottomTextureId	byte	0	Refers to a terrain.png tile. Between 0 and 255 (unsigned). Can be same as other texture IDs. This is the texture ID for the Y = 0 face.
	MinX	byte	0	Minimum X coordinate in pixels. Min allowed is 0, max allowed is 15.
	MinY	byte	0	Minimum Y coordinate in pixels. Min allowed is 0, max allowed is 15.
	MinZ	byte	0	Minimum Z coordinate in pixels. Min allowed is 0, max allowed is 15.
	MaxX	byte	16	Maximum X coordinate in pixels. Min allowed is 1, max allowed is 16.
	MaxY	byte	16	Maximum Y coordinate in pixels. Min allowed is 1, max allowed is 16.
	MaxZ	byte	16	Maximum Z coordinate in pixels. Min allowed is 1, max allowed is 16.
	ColR	byte	255	Red color to filter with.
	ColG	byte	255	Green color to filter with.
	ColB	byte	255	Blue color to filter with.
	Collide	bool	true	Whether this quad can collide with this quad. If set to false, this quad will be ignored by colision. If multiple collisions are not supported by the client, use bounds defined in the BlockDefinition.
	Render	bool	true	Whether this quad will render. If set to false, this quad will not render, and will only be used for collision.
	Total Size:	18 bytes

(Comments go here, please sign them)

TexturePackExt

Proposed by Galaxtone (talk) 00:59, 27 February 2020 (UTC)

This extension adds hierarchical texture packs where multiple may be loaded per map and override each other in a distinct order.

Motivation: Creating texture packs that modify a few assets without having to copy the server's global texture pack assets which would be bulky, impractical and non-portable between servers.

Client behavior: This extension must be mutually supported along with EnvMapAspect. The client must combine all texture packs, resolving file conflicts between multiple texture packs by using the file from the texture pack with the highest order. The client must treat SetMapEnvUrl packets as texture packs with an order of -1. The client must be able to receive SetMapEnvUrlExt packets at any time appropriate to receive SetMapEnvUrl packets. The EnvMapEnvUrl packet must be used to clear all texture packs as the EnvMapEnvUrlExt packet will set or clear the texture pack at the specified order.

Server behavior: Server may send SetMapEnvUrlExt packets at any time appropriate to send SetMapEnvUrl packets. To reset all texture packs to the client's default, server has to use the SetMapEnvUrl packet instead.

SetMapEnvUrlExt packet

Server to Client

Packet ID	Field Name	Field Type	Example	Notes
0x?? (??)	Following field from SetMapEnvUrl packet: TexturePackURL
	TexturePackOrder	byte	6	The order of the texture pack.
Total Size:	66 bytes

(Comments go here, please sign them)

BlockDefinitions v2

Proposed by Jshtab (talk) 19:10, 11 January 2022 (UTC)

Functionally equal to supporting BlockDefinitionsExt v2. Superceeds BlockDefinitionsExt v2 and BlockDefinitions v1.

Motivation: Prevent dependency hell, promote consistency.

Client Behavior: Functionally equal to supporting BlockDefinitionsExt v2.

Server Behavior: Functionally equal to supporting BlockDefinitionsExt v2. If a client supports BlockDefinitions v1 and BlockDefinitionsExt v2, they support BlockDefinitions v2

(Comments go here, please sign them)

ScreenElements

Proposed by DT

This extension allows the server to define and undefine 2d elements on the client's screen.

Motivation: It would allow for advanced UI elements and sprites to be drawn to the screen, such as a textured health bar above the hotbar, or a timer at the top of the screen.

Client Behavior: Clients should be able to define and undefine image and text elements. Client should use sprites.png in the texture pack zip for textured sprites. Client must be able to receive and send all packets. Screen elements should not persist between maps.

Server Behavior: Servers should be able to send and receive packets to define and undefine image and text elements.

DefineImgElem

Server to Client

Packet ID	Field Name	Field Type	Example	Notes
0x?? (??)
	ElemID	byte	0	Element ID
	AnchorX	byte	1	The screen anchor along the X axis 0 = Left 1 = Center 2 = Right
	AnchorY	byte	1	The screen anchor along the Y axis 0 = Top 1 = Center 2 = Bottom
	OffsetX	short	24	The X offset from AnchorX
	OffsetY	short	-712	The Y offset from AnchorY
	Source	UVCoords	(0,5, 10,15)	UV Coords of sprites.png to display
Total Size:	16 bytes

DefineTextElem

Server to Client

Packet ID	Field Name	Field Type	Example	Notes
0x?? (??)
	ElemID	byte	0	Element ID
	AnchorX	byte	1	The screen anchor along the X axis 0 = Left 1 = Center 2 = Right
	AnchorY	byte	1	The screen anchor along the Y axis 0 = Top 1 = Center 2 = Bottom
	OffsetX	short	24	The X offset from AnchorX
	OffsetY	short	-712	The Y offset from AnchorY
	Text	string	""	Text to display
	Scale	byte	0	Scale of text being displayed (0 for small, 1 for big)
Total Size:	72 bytes

UndefineElem

Server to Client

Packet ID	Field Name	Field Type	Example	Notes
0x?? (??)
	ElemID	byte	0	Element ID to undefine
Total Size:	2 bytes

(Comments go here, please sign them)

ExtendedBlocks v2

Proposed by Infernity (talk) 17:19, 15 June 2022 (UTC)

Allows using more than 768 blocks.

Motivation: Allows for ever-more-detailed maps by sending up to 65,536 blocks.

Client Behavior: Clients must adjust how they read the map as described in the Affect on map sending section. Clients must also adjust how they read and write several fields of the packets described in the Affect on other packets section. When a client detects that the secondary map blocks array is used, it must switch from accessing blocks via map.blocks[index] to map1.blocks[index] | (map2.blocks[index] << 8) instead.

Server Behavior: Servers must adjust how they write the map as described in the Affect on map sending section. Servers must also adjust how they read and write several fields of the packets described in the Affect on other packets section. Ideally, servers should avoid sending a secondary map blocks array when possible to minimise client memory usage.

Affect on map sending

Essentially, instead of LevelDataChunk packets just being used to send the compressed form of the map blocks array, it is repurposed to send both the compressed form of the 'main' map blocks array and optionally a secondary map blocks array. To accomplish this, the Percent Complete field in the LevelDataChunk packet is repurposed. A value of 0 indicates that this LevelDataChunk packet contains part of the compressed data for the 'main' map blocks array, while a value of 1 indicates this LevelDataChunk packet contains part of the compressed data for the optional secondary map blocks array.

The client and server should treat the LevelDataChunk packets used for the 'main' map blocks array as completely separate from the secondary map blocks array, i.e. the 'main' map blocks array should be compressed and decompressed completely independently of the optional secondary map blocks array.

Note: Even if the server only sends a 'main' map blocks array, the client must still be prepared to allocate a secondary map blocks array at any time after map load. For example:

• Client A goes to map XYZ
• Server sends client A just a main blocks array for map XYZ
• A minute later, client B places a block with ID 510 on map XYZ
• Server then broadcasts this block change to all clients on map XYZ

Since a secondary map blocks array was not sent during map load by the server, Client A must now allocate a secondary map blocks array.

Affect on other packets

Several fields in some packets are expanded in size. These are:

Packet	Field Name	New Type	Direction
Set Block (0x05)	Block type	short	Client -> Server
Set Block (0x06)	Block Type	short	Server -> Client
Position and Orientation (0x08)	Player ID	short	Client -> Server
HoldThis (0x14)	BlockToHold	short	Server -> Client
SetBlockPermission (0x1C)	BlockType	short	Server -> Client
DefineBlock (0x23)	BlockID	short	Server -> Client
UndefineBlock (0x24)	BlockID	short	Server -> Client
DefineBlockExt (0x25)	BlockID	short	Server -> Client
BulkBlockUpdate (0x28)	Blocks	byte[512]	Server -> Client
SetInventoryOrder (0x2C)	Order	short	Server -> Client
SetInventoryOrder (0x2C)	Block ID	short	Server -> Client
SetHotbar (0x2D)	BlockID	short	Server -> Client

Affect on BulkBlockUpdate

Although the affect on most packets is straightforward, the changes to BulkBlockUpdate requires a more thorough explanation:

• The first 256 bytes store the lower 8 bits of the ID for each of the 256 blocks.
• The remaining 256 bytes store the higher 8 bits of the ID for each of the 256 blocks.

(Comments go here, please sign them)

Most of this is copy/pasted from ExtendedBlocks v1, though BulkBlockUpdate has been updated to support the new blocks. This probably also needs the ability for more than 512 textures, but that's a seperate packet. Also maybe a packet to say how many blocks server/client supports? Also also, feel free to edit this; just sign on the top too. Infernity (talk) 17:19, 15 June 2022 (UTC)

ExtServerMessages

Proposed by Rainb0wSkeppy (talk) 22:43, 20 June 2023 (UTC)

Allows the server to remove, insert and replace messages, set the background and foreground color of the messages, and send messages longer then 64 characters

Motivation: To allow the server to send messages longer then 64 characters, highlight parts of chat by changing the background color and to edit and delete messages after they have been sent (eg. a moderator removing messages that break the rules)

Client Behavior: The client must read 2 characters after the &, the first one is the foreground and the second one is the background, When the server sends a message, the client inserts in the correct place, When the Position field is 0xff the client should not send a message until the Position field isn't 0xff, then concatenate the messages, When the server sends a DeleteMessage packet, it deletes the specified message

Server Behavior: The server may send messages with the Position field and send DeleteMessage packets

ExtServerMessage packet

Server to client

Packet ID	Field Name	Field Type	Example	Notes
0x?? (??)	Position	byte	0	The position of the message. 0 is after the last message, 1 is between the last and the 2nd last message, 2 is between the 2nd last and the 3nd last message, etc. Position of 255 means the message should not be shown and should be concatenated with the next ExtServerMessage packet.
	Message	string	&70Rainb0wSkeppy: &f0hi	The message to be sent
	Total Size:	66 bytes

DeleteMessage packet

Server to client

Packet ID	Field Name	Field Type	Example	Notes
0x?? (??)	Position	byte	0	The position of the message. 0 is the last message, 1 is the 2nd last message, 2 is the 3nd last message, etc.
	Total Size:	2 bytes

(Comments go here, please sign them)