Pre-release protocol

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Revision as of 18:40, 17 January 2024 by WinX64 (talk | contribs) (24w03a)
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This page documents the changes from the last stable Minecraft release (currently 1.20.4, protocol 765) to the current pre-release (currently 24w03a, protocol Snapshot 171). 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
Handshake serverbound
0x00 Handshake Current Pre
Login clientbound
0x05 Cookie Request (Login) Pre
Login serverbound
0x04 Cookie Response (Login) Pre
Configuration clientbound
0x00 Cookie Request (Configuration) Pre
Configuration serverbound
0x01 Cookie Response (Configuration) Pre
Play clientbound
0x16 Cookie Request (Play) Pre
0x6A Store Cookie Pre
0x72 Transfer Pre
0x74 Update Attributes Current Pre
0x75 Entity Effect Current Pre
Play serverbound
0x10 Cookie Response (Play) Pre

New/modified data types

No changes so far.

Entity Metadata

Type (VarInt Enum) Value (Varies) Notes
0 Byte
1 VarInt
2 VarLong
3 Float
4 String
5 Chat
6 OptChat (Boolean + Chat) Chat is present if the Boolean is set to true
7 Slot
8 Boolean
9 Rotation 3 Floats: rotation on x, rotation on y, rotation on z
10 Position
11 OptPosition (Boolean + Position) Position is present if the Boolean is set to true
12 Direction (VarInt) (Down = 0, Up = 1, North = 2, South = 3, West = 4, East = 5)
13 OptUUID (Boolean + UUID) UUID is present if the Boolean is set to true
14 BlockID (VarInt)
15 OptBlockID (VarInt) 0 for absent (implies air); otherwise, a block state ID as per the block state registry
16 NBT
17 Particle
18 Villager Data 3 VarInts: villager type, villager profession, level
19 OptVarInt 0 for absent; 1 + actual value otherwise. Used for entity IDs.
20 Pose A VarInt enum: 0: STANDING, 1: FALL_FLYING, 2: SLEEPING, 3: SWIMMING, 4: SPIN_ATTACK, 5: SNEAKING, 6: LONG_JUMPING, 7: DYING, 8: CROAKING, 9: USING_TONGUE, 10: SITTING, 11: ROARING, 12: SNIFFING, 13: EMERGING, 14: DIGGING
21 Cat Variant A VarInt that points towards the CAT_VARIANT registry.
22 Frog Variant A VarInt that points towards the FROG_VARIANT registry.
23 OptGlobalPos (Boolean + GlobalPos) GlobalPos consists of a dimension identifier and Position.
24 Painting Variant A VarInt that points towards the PAINTING_VARIANT registry.
25 Sniffer State A VarInt enum: IDLING = 0, FEELING_HAPPY = 1, SCENTING = 2, SNIFFING = 3, SEARCHING = 4, DIGGING = 5, RISING = 6
26 Armadillo State A VarInt enum: IDLE = 0, ROLLING = 1, SCARED = 2
26 27 Vector3 3 Floats: x, y, z
27 28 Quaternion 4 Floats: x, y, z, w

Armadillo

Extends Animal.

Index Type Meaning Default
17 Armadillo State Armadillo State IDLE

Block Actions

No changes so far.

Inventories

No changes so far.

Plugin Channels

No changes so far.

Handshake

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 765 in Minecraft 1.20.4).
Server Address String (255) 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 simple redirect, e.g. if _minecraft._tcp.example.com points to mc.example.org, users connecting to example.com will provide 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, 3 for Transfer.

Status

Clientbound

No changes so far.

Serverbound

No changes so far.

Login

Clientbound

Cookie Request (Login)

Requests a cookie that was previously stored.

Packet ID State Bound To Field Name Field Type Notes
0x05 Login Client Key Identifier The identifier of the cookie.

Serverbound

Cookie Response (Login)

Response to a Cookie Request (Login) from the server. The Notchian server only accepts responses of up to 5 kiB in size.

Packet ID State Bound To Field Name Field Type Notes
0x04 Login Server Key Identifier The identifier of the cookie.
Has Payload Boolean The payload is only present if the cookie exists on the client.
Payload Optional ByteArray(5120) The data of the cookie, if any.

Configuration

Clientbound

Cookie Request (Configuration)

Requests a cookie that was previously stored.

Packet ID State Bound To Field Name Field Type Notes
0x00 Configuration Client Key Identifier The identifier of the cookie.

Serverbound

Cookie Response (Configuration)

Response to a Cookie Request (Configuration) from the server. The Notchian server only accepts responses of up to 5 kiB in size.

Packet ID State Bound To Field Name Field Type Notes
0x01 Configuration Server Key Identifier The identifier of the cookie.
Has Payload Boolean The payload is only present if the cookie exists on the client.
Payload Optional ByteArray(5120) The data of the cookie, if any.

Play

Clientbound

Cookie Request (Play)

Requests a cookie that was previously stored.

Packet ID State Bound To Field Name Field Type Notes
0x16 Play Client Key Identifier The identifier of the cookie.

Store Cookie

Stores some arbitrary data on the client, which persists between server transfers. The Notchian client only accepts cookies of up to 5 kiB in size.

Packet ID State Bound To Field Name Field Type Notes
0x6A Play Client Key Identifier The identifier of the cookie.
Payload ByteArray(5120) The data of the cookie.

Transfer

Notifies the client that it should transfer to the given server. Cookies previously stored are preserved between server transfers.

Packet ID State Bound To Field Name Field Type Notes
0x72 Play Client Host String The hostname of IP of the server.
Port VarInt The port of the server.

Update Attributes

Sets attributes on the given entity.

Packet ID State Bound To Field Name Field Type Notes
0x71 Play Client Entity ID VarInt
Number Of Properties VarInt Number of elements in the following array.
Property Key Id Array Identifier VarInt Enum See below.
Value Double See below.
Number Of Modifiers VarInt Number of elements in the following array.
Modifiers Array of Modifier Data See Attribute#Modifiers. Modifier Data defined below.

Known Key values (see also Attribute#Modifiers):

Id Key Default Min Max Label
0 generic.armor 0.0 0.0 30.0 Armor.
1 generic.armor_toughness 0.0 0.0 20.0 Armor Toughness.
2 generic.attack_damage 2.0 0.0 2048.0 Attack Damage.
3 generic.attack_knockback 0.0 0.0 5.0 Attack Knockback.
4 generic.attack_speed 4.0 0.0 1024.0 Attack Speed.
5 generic.block_interaction_range 4.5 0.0 64.0 Block Interaction Range.
6 generic.entity_interaction_range 3.0 0.0 64.0 Entity Interaction Range.
7 generic.flying_speed 0.4 0.0 1024.0 Flying Speed.
8 generic.follow_range 32.0 0.0 2048.0 Follow Range.
9 horse.jump_strength 0.7 0.0 2.0 Jump Strength.
10 generic.knockback_resistance 0.0 0.0 1.0 Knockback Resistance.
11 generic.luck 0.0 -1024.0 1024.0 Luck.
12 generic.max_absorption 0.0 0.0 2048.0 Max Absorption.
13 generic.max_health 20.0 1.0 1024.0 Max Health.
14 generic.movement_speed 0.7 0.0 1024.0 Movement Speed.
15 generic.scale 1.0 0.0625 16.0 Scale.
16 zombie.spawn_reinforcements 0.0 0.0 1.0 Spawn Reinforcements Chance.
17 generic.step_height 0.6 0.0 10.0 Step Height.

Modifier Data structure:

Field Name Field Type Notes
UUID UUID
Amount Double May be positive or negative.
Operation Byte See below.

The operation controls how the base value of the modifier is changed.

  • 0: Add/subtract amount
  • 1: Add/subtract amount percent of the current value
  • 2: Multiply by amount percent

All of the 0's are applied first, and then the 1's, and then the 2's.

Entity Effect

Packet ID State Bound To Field Name Field Type Notes
0x72 Play Client Entity ID VarInt
Effect ID VarInt See this table.
Amplifier Byte Notchian client displays effect level as Amplifier + 1.
Duration VarInt Duration in ticks. (-1 for infinite)
Flags Byte Bit field, see below.
Has Factor Data Boolean Used in DARKNESS effect
Factor Codec NBT Tag See below
Huh.png The following information needs to be added to this page:
What exact effect does the blend bit flag have on the client? What happens if it is used on effects besides DARKNESS?

Within flags:

  • 0x01: Is ambient - was the effect spawned from a beacon? All beacon-generated effects are ambient. Ambient effects use a different icon in the HUD (blue border rather than gray). If all effects on an entity are ambient, the "Is potion effect ambient" living metadata field should be set to true. Usually should not be enabled.
  • 0x02: Show particles - should all particles from this effect be hidden? Effects with particles hidden are not included in the calculation of the effect color, and are not rendered on the HUD (but are still rendered within the inventory). Usually should be enabled.
  • 0x04: Show icon - should the icon be displayed on the client? Usually should be enabled.
  • 0x08: Blend - should the effect's hard-coded blending be applied? Currently only used in the DARKNESS effect to apply extra void fog and adjust the gamma value for lighting.

Factor Data

Name Type Notes
padding_duration TAG_INT
factor_start TAG_FLOAT
factor_target TAG_FLOAT
factor_current TAG_FLOAT
effect_changed_timestamp TAG_INT
factor_previous_frame TAG_FLOAT
had_effect_last_tick TAG_BOOLEAN

Serverbound

Cookie Response (Play)

Response to a Cookie Request (Play) from the server. The Notchian server only accepts responses of up to 5 kiB in size.

Packet ID State Bound To Field Name Field Type Notes
0x6A Play Server Key Identifier The identifier of the cookie.
Has Payload Boolean The payload is only present if the cookie exists on the client.
Payload Optional ByteArray(5120) The data of the cookie, if any.