Pre-release protocol

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Revision as of 11:36, 21 March 2020 by Proximyst (talk | contribs) (Add information on how to decode & encode UUID)
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This page documents the changes from the last stable Minecraft release (currently 1.15.2, protocol 578) to the current pre-release (currently 20w12a, protocol 707). Note that this page contains bleeding-edge information that may not be completely or correctly documented.

One who wishes to commandeer the merging of this into Protocol when an update is made must be sure to respect any changes that may have occurred to the respective packets there.

Contents

Data types

No changes so far.

Packets

ID Packet name Documentation
Handshaking serverbound
0x00 Handshake Current Pre
Play clientbound
0x4E 0x43 Spawn Position Current (unchanged)
0x43 0x44 Display Scoreboard Current (unchanged)
0x44 0x45 Entity Metadata Current (unchanged)
0x45 0x46 Attach Entity Current (unchanged)
0x46 0x47 Entity Velocity Current (unchanged)
0x47 0x48 Entity Equipment Current (unchanged)
0x48 0x49 Set Experience Current (unchanged)
0x49 0x4A Update Health Current (unchanged)
0x4A 0x4B Scoreboard Objective Current (unchanged)
0x4B 0x4C Set Passengers Current (unchanged)
0x4C 0x4D Teams Current (unchanged)
0x4D 0x4E Update Score Current (unchanged)
Login clientbound
0x02 Login Success Current Pre

New/modified data types

No changes so far.

Entity Metadata

Abstract Arrow

Extends Entity.

Abstract base class for Tipped Arrow (which is used for regular arrows as well as tipped ones) and Spectral Arrow.

Index Type Meaning Default
7 Byte Bit mask Meaning 0
0x01 Is critical
0x02 Is noclip (used by loyalty tridents when returning)
8 OptUUID Unused Empty
9 8 Byte Peircing level 0

Tipped Arrow

Extends Abstract Arrow.

Used for both tipped and regular arrows. If not tipped, then color is set to -1 and no tipped arrow particles are used.

Index Type Meaning Default
10 9 VarInt Color (-1 for no particles) -1

Spectral Arrow

Extends Abstract Arrow.

No additional metadata.

Trident

Extends Abstract Arrow.

Index Type Meaning Default
10 9 VarInt Loyalty level (enchantment) 0
11 10 Boolean Has enchantment glint False

Hoglin

Extends Animal.

No additional metadata.

Piglin

Extends Monster.

Index Type Meaning Default
15 Boolean Is baby false
16 Boolean Is immune to zombification false
17 Boolean Is charging crossbow false

Zombie Pigman Zombified Piglin

Extends Zombie.

No additional metadata.

Block Actions

No changes so far.

Inventories

No changes so far.

Plugin Channels

No changes so far.

Play

Clientbound

No changes so far.

Serverbound

No changes so far.

Handshaking

Clientbound

There are no clientbound packets in the Handshaking state, since the protocol immediately switches to a different state after the client sends the first packet.

Serverbound

Handshake

This causes the server to switch into the target state.

Packet ID State Bound To Field Name Field Type Notes
0x00 Handshaking Server Protocol Version VarInt See protocol version numbers (currently 578 707)
Server Address String Hostname or IP, e.g. localhost or 127.0.0.1, that was used to connect. The Notchian server does not use this information. Note that SRV records are a complete redirect, e.g. if _minecraft._tcp.example.com points to mc.example.org, users connecting to example.com will provide mc.example.org as server address in addition to connecting to it.
Server Port Unsigned Short Default is 25565. The Notchian server does not use this information.
Next State VarInt Enum 1 for status, 2 for login

Status

Clientbound

No changes so far.

Serverbound

No changes so far.

Login

Clientbound

Login Success

Packet ID State Bound To Field Name Field Type Notes
0x02 Login Client UUID String (36) Int array (4) Unlike in other packets, this field contains the UUID as a string with hyphens a fixed length int array.

The UUID is encoded and decoded as follows, where the int array for decoding is read in the order the bytes are received:

 public static UUID decodeUuid(int[] is) {
   return new UUID((long)is[0] << 32 | (long)is[1] & 4294967295L, (long)is[2] << 32 | (long)is[3] & 4294967295L);
 }
 public static int[] encodeUuid(long mostSignificantBits, long leastSignificantBits) {
   return new int[]{
       (int)(mostSignificantBits >> 32),
       (int)mostSignificantBits,
       (int)(leastSignificantBits >> 32),
       (int)leastSignificantBits
   };
 }

Username String (16)

This packet switches the connection state to play.

Serverbound

No changes so far.