Pre-release protocol

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Revision as of 10:23, 29 April 2012 by Pdelvo (talk | contribs)
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This page documents the changes from the last stable Minecraft release (currently 1.2.5) to the current pre-release (or weekly release).

New packets

Tab-complete (0xCB)

Two-way

Sent C->S when the user presses [tab] while writing text. The payload contains all text behind the cursor.

The server responds with an auto-completion of the last word sent to it. In the case of regular chat, this is a player username. Command names and parameters are also supported.

In the event of more than one possible completion, the server responds with the options packed into the single string field, separated by a null character. Note that as strings are UTF-16, this is two bytes wide.

Packet ID Field Name Field Type Example Notes
0xCB Text string
Total Size: 3 bytes + length of string

Locale and View Distance (0xCC)

Client to server

Sent when the player connects, or when settings are changed.

Packet ID Field Name Field Type Example Notes
0xCC Locale string en_GB
View distance int 0 0-3 for 'far', 'normal', 'short', 'tiny'.
Chat info byte Bits: 0: chat enabled, 2: colors enabled
Total Size: 7 bytes + length of string

Encryption Key Response (0xFC)

Two-Way

Sent after receiving 0xFD. After the client send a Encryption Key Response packet to the server the server responds with one too(with a empty Shared key). The shared key is a client-generated, 16 bytes long key for RC4 encryption. The key is encrypted with RSA with the public key from the Encryption Key Request packet.

Packet ID Field Name Field Type Example Notes
0xFC Shared key length short
Shared key byte array
Total Size: 3 bytes + length of key

Encryption Key Request (0xFD)

Server to client

Sent after handshakes.

Public key encryption: RSA.

Packet ID Field Name Field Type Example Notes
0xFD Server id string
Public key length short
Public key byte array
Total Size: 5 bytes + length of string + length of key

Changed packets

Login Request (0x01)

Two-Way

Just a guess: stripped unused string field.

Client to Server

Packet ID Field Name Field Type Example Notes
0x01 Protocol Version int 20 1.2.5's protocol version is 29 - since version 31 always 0
Username string TkTech The name of the user attempting to login, max length of 16 - since version 31 empty string
Not used int 0
Not used int 0
Not used byte 0
Not used unsigned byte 0
Not used unsigned byte 0
Total Size: 20 bytes + length of strings

Server to Client

Packet ID Field Name Field Type Example Notes
0x01 Entity ID int 1298 The Players Entity ID
Level Type string default default or SUPERFLAT; level-type in server.properties
Server mode int 0 0 for survival, 1 for creative
Dimension int 0 -1: The Nether, 0: The Overworld, 1: The End
Difficulty byte 1 0 thru 3 for Peaceful, Easy, Normal, Hard
Not used unsigned byte 0 Only 0 observed from vanilla server, was previously world height
Max players unsigned byte 8 Used by the client to draw the player list
Total Size: 20 bytes + length of strings

Hanshake (0x02)

Client to server only - before encryption, not sure what happens thereafter, may still be a server reply --Ceiru 23:12, 27 April 2012 (MST)

Packet ID Field Name Field Type Example Notes
0x02 Protocol Version byte 31
Username and Host string TkTech The username of the player attempting to connect, and the host he is connecting to, seperated by a semicolon.
Total Size: 4 bytes + length of string

Protocol History

2012-04-26

  • 12w17a
  • Protocol version is now 31
  • After exchanging handshakes, RC4 based encryption is initiated. The server sends 0xFD, which is replied by the client using 0xFC.
  • Changed packet: 0x01 Login Request
  • Changed packet: 0x02 Handshake
  • Changed packet: 0xCC Locale and View Distance
  • New packet: 0xFC Encryption Key Response
  • New packet: 0xFD Encryption Key Request
  • New Item: Book & Quills (0x182) is enchantable

2012-04-19

  • 12w16a
  • Protocol version is now 30
  • New packet: 0xCB Tab-complete
  • New packet: 0xCC Locale and View Distance