Pre-release protocol
This page documents the changes from the last stable Minecraft release (currently 1.1) to the current pre-release
New packets
Entity Head Look (0x23)
Changes the direction an entity's head is facing.
| Packet ID | Field Name | Field Type | Example | Notes |
|---|---|---|---|---|
| 0x23 | Entity ID | int | ||
| Head Yaw | byte | Head yaw in steps of 2π/256 | ||
| Total Size: | 6 bytes | |||
Update Tile Entity (0x84)
Essentially a block update on a tile entity.
| Packet ID | Field Name | Field Type | Example | Notes |
|---|---|---|---|---|
| 0x84 | X | int | ||
| Y | short | |||
| Z | int | |||
| Action | byte | The type of update to perform | ||
| Custom 1 | int | Varies | ||
| Custom 2 | int | Varies | ||
| Custom 3 | int | Varies | ||
| Total Size: | 24 bytes | |||
Actions
- 1: Set mob displayed inside a mob spawner. Custom 1 contains the mob type
Changed packets
Login Request (0x01)
World height was changed to an integer. -- Please verify, I found world height to still be a byte but set to 0.
| Packet ID | Field Name | Field Type | Example | Notes |
|---|---|---|---|---|
| 0x01 | Entity ID | int | 1298
|
The Players Entity ID |
| Not used | string | (empty string) | Not used | |
| Map Seed | long | 971768181197178410
|
The server's map seed. Must be sent in respawn packets by the client. | |
| Level Type | string | DEFAULT | DEFAULT or SUPERFLAT; level-type in server.properties | |
| Server mode | int | 0
|
0 for survival, 1 for creative | |
| Dimension | byte | 0
|
-1: The Nether, 0: The Overworld, 1: The End
| |
| Difficulty | byte | 1
|
0 thru 3 for Peaceful, Easy, Normal, Hard
| |
| World height | int | 256
|
Defaults to 256
| |
| Max players | unsigned byte | 8
|
Used by the client to draw the player list | |
| Total Size: | 28 bytes + length of strings | |||
Handshake (0x02)
Client to Server
The hostname and port were added to this packet, most likely to allow virtual hosting .(sample implementation)
| Packet ID | Field Name | Field Type | Example | Notes |
|---|---|---|---|---|
| 0x02 | UsernameAndHost | string | TkTech;localhost:25565
|
The username of the player attempting to connect, and the host he is connecting to, seperated by a semicolon. |
| Total Size: | 3 bytes + length of strings | |||
Respawn (0x09)
Dimension is now an int, slightly bizarrely. I wonder if they intended to make world_height an int, in line with 0x01 login?
| Packet ID | Field Name | Field Type | Example | Notes |
|---|---|---|---|---|
| 0x09 | Dimension | int | 1
|
-1: The Nether, 0: The Overworld, 1: The End
|
| Difficulty | byte | 1
|
0 thru 3 for Peaceful, Easy, Normal, Hard. 1 is always sent c->s
| |
| Creative mode | byte | 1
|
0 for survival, 1 for creative.
| |
| World height | short | 128
|
Defaults to 128
| |
| Map Seed | long | -3815848935435401459
|
The server's map seed. | |
| Level Type | string | DEFAULT | See 0x01 login | |
| Total Size: | 19 bytes + length of string | |||
Mob Spawn (0x18)
New byte field: head yaw
This needs confirmation!
| Packet ID | Field Name | Field Type | Example | Notes |
|---|---|---|---|---|
| 0x18 | EID | int | 446
|
Entity ID |
| Type | byte | 91
|
The type of mob. See Entities#Mobs | |
| X | int | 13366
|
The Absolute Integer X Position of the object | |
| Y | int | 2176
|
The Absolute Integer Y Position of the object | |
| Z | int | 1680
|
The Absolute Integer Z Position of the object | |
| Yaw | byte | -27
|
The yaw in steps of 2π/256 | |
| Pitch | byte | 0
|
The pitch in steps of 2π/256 | |
| Head Yaw | byte | Head yaw in steps of 2π/256 | ||
| Metadata | Metadata | 127
|
Varies by mob, see Entities | |
| Total Size: | 21 bytes + Metadata (at least 1) | |||
Map Chunk (0x33)
This is currently a best guess
Here's a packet capture: https://gist.github.com/1835702
| Packet ID | Field Name | Field Type | Example | Notes |
|---|---|---|---|---|
| 0x33 | X | int | Chunk X Coordinate (x16 to get true X) Confirmed! | |
| Z | int | Chunk Z Coordinate (x16 to get true Z) Confirmed! | ||
| Complete | boolean | (unconfirmed) If true all vertical chunks not included is assumed to be air. Seems to be True when Unknown Short #1 is 2^n - 1 | ||
| Height bit map | short | 15 | Bitmask with 1 for every chunk which data follows in Compressed data. | |
| Unknown Short #2 | short | 0 | I've only seen 0
| |
| Compressed size | int | Size of compressed region data. Confirmed! | ||
| Unknown Int | int | 0 | Doesn't seem to be used by the client. Always 0. I expect this is Mod API stuff. | |
| Compressed data | unsigned byte array | …
|
The region data is compressed using ZLib Deflate function. Confirmed! | |
| Total Size: | 22 bytes + Compressed chunk size | |||
(Unconfirmed, guess) Height bit map where each bit indicates which vertical chunk it contain. Counting the number of binary 1's indicate the number of vertical chunks(16x16x16) of the uncompressed
N = number of vertical chunks.
| Size | Name | Example | Notes |
|---|---|---|---|
| 16*16*16*N | Block ID | 7(bedrock) | 1 byte per block. |
| 16*16*16*N | Add Block ID | 0 | (unconfirmed)1 byte per block. |
| 16*16*8*N | Unknown | 255 | (unconfirmed) Biome? Skylight? |
| Total Size: | 16*16*16*N*2 + 16*16*8*N bytes (uncompressed) | ||
That would make the boolean mean "Contiguous?". Possibly a memory optimisation? The bit shifting in the chunk loading code makes this idea seem likely to me - good thought! Barneygale 08:37, 15 February 2012 (MST)
- It could be an indicator that non included chunks are assumed to be empty/air, a guess --Ceiru 09:14, 15 February 2012 (MST)
- (edit conflict, lol)
- The first part of the uncompressed data is the chunk block ids (I think), which as you say are loaded based on the bitmask. Each chunk is 4096 bytes.
- Three near identical loops follow, iterating over the column of chunks. They all set the .a property of a qi - and I'm not sure what this is. I'm guessing it's a handler for chunk attributes like metadata, skylight and blocklight.
- Next there's a loop that bears a striking similarity to the first, but uses the second short as a bitmask. For each chunk, if it's mentioned in the mask, it will initialise or use the existing .e (another qi) of that chunk and copy data to it. Here's where the bool comes in. If the chunks are contiguous, and the current chunk is both loaded and has .e set, it will set .e to null.
- Then there's some chunk initialisation stuff I don't understand.
Other changes
Protocol version is now 27.
Protocol History
2012-02-15
- 12w07a
- Protocol version is now 27
- Updated packets: 0x01, 0x09, 0x33
2012-02-09
- 12w06a
- Protocol version is now 25
- New packet: 0x84
2012-01-26
- 12w04a
- Protocol version has not been changed
- Handshake Packet by client (0x02) now contains the server host and port
- Window Open Packet (0x64): WindowTitle is now longer than accepted by older clients. Contains a keyword such as "container.furnace"
2012-01-19
- 12w03a
- Protocol version is now 24
- New packet: 0x23
- MobSpawn: new field, 1 byte inserted before metadata.
