Bedrock Server

A Minecraft Bedrock server implementation in Elixir. This is experimental and is not a fully featured minecraft server (yet). Use at your own risk.

Installation

If available in Hex, the package can be installed by adding bedrock_server to your list of dependencies in mix.exs:

def deps do
  [
    {:bedrock_server, "~> 0.1.0"}
  ]
end

---

Todo

• ipv6

Notes

Start an iex session with:

iex -S mix

Elixir <<>> types: https://hexdocs.pm/elixir/1.12/Kernel.SpecialForms.html#%3C%3C%3E%3E/1

RakNet

Reliability

Frame Set Packet

Packet ID	Field Name			Field Type	Notes
0x80..0x8d	Sequence number			uint24le
	Frames	Flags		byte	Top 3 bits are reliability type, fourth bit is 1 when the frame is fragmented and part of a compound.
		Length IN BITS		unsigned short	Length of the body in bits.
		Reliable frame index		uint24le	only if reliable
		Sequenced frame index		uint24le	only if sequenced
		Order	Ordered frame index	uint24le	only if ordered
			Order channel	byte
		Fragment	Compound size	int	only if fragmented
			Compound ID	short
			Index	int
		Body	ceil(length/8) bytes

Handshake

1. C -> S: Open Connection Request 1
2. S -> C: Open Connection Reply 1
3. C -> S: Open Connection Request 2
4. S -> C: Open Connection Reply 2

Once the handshake is established, messages will be contained in a Frame Set Packet.

1. C -> S: Connection Request
2. S -> C: Connection Request Accepted
3. C -> S: New Incoming Connection

All following packets will be Game Packets.

Types

Name	Size	Desc
addr	7
int8	1	Signed 8-bit integer
int16	2	Signed 16-bit integer
int24	3	Signed 24-bit integer
int64	4	Signed 64-bit integer
MAGIC	16	0x00ffff00fefefefefdfdfdfd12345678 This is hardcoded in the RakNet source

Packets

Unconnected Ping 0x01

Clients start by sending this packet to the server on port 19132 repeatedly for server discovery. Once the client has established a connection, it will send connected pings instead.

This packet should be replied to with an unconnected pong.

Field	Type	Notes
Ping ID	i64	Time since start in milliseconds
MAGIC	MAGIC

Unconnected Ping 0x02

Same as 0x01, except for that it should only be replied to if there are any open connections to the server.

Unconnected Pong 0x1c

Field	Type	Notes
Time	i64
Server GUID	i64
MAGIC	MAGIC
Server ID	string	This is used for the MOTD

Server ID string format
The server id is seperated by semicolons and uses the following fields in order. Again, joined by a semicolon.

Field	Desc
Edition	MCPE (Bedrock), MCEE (Education Edition)
MOTD Line 1	Server MOTD
Protocol	The protocol version number
Version	The minecraft version number
Player Count	The number of connected players
Player Limit	The maximum number of players the server supports
Server ID	todo
MOTD Line 2	Server MOTD
Gamemode	The game mode string representation (seems unused)
Gamemode ID	The game mode number representation (seems unused)
IPv4 Port
IPv6 Port

Connected Ping 0x00

This packet should be replied to with a connected pong.

Field	Type	Notes
Time	i64	The ping time

Connected Pong 0x03

Field	Type	Notes
Ping Time	i64
Ping Time	i64

Open Connection Request 1 0x05

The client will send this packet with decreasing MTU until the server responds. This is done to discover the MTU size for the connection.

This packet should be replied to with Open Connection Reply 1 with the MTU size of the amount of padding you received in bytes plus 46. (improve) (28 udp overhead, 1 packet id, 16 magic, 1 protocol version)

Field	Type	Notes
MAGIC	MAGIC
Protocol Version	i8	Currently 11
MTU	Zero padding	Padding used to detect the maximum MTU size

Open Connection Reply 1 0x06

Field	Type	Notes
MAGIC	MAGIC
Server GUID	i64
Use Security	boolean	This must be false
MTU	i16	See Open Connection Request 1

Open Connection Request 2 0x07

This packet should be replied to with Open Connection Reply 2.

Field	Type	Notes
MAGIC	MAGIC
Server Address	address
MTU	i16	See Open Connection Request 1

Open Connection Reply 2 0x08

Field	Type	Notes
MAGIC	MAGIC
Server GUID	i64
MTU	i16	See Open Connection Request 1
Use Encryption	boolean	Not sure what this does

Connection Request 0x09

This packet should be replied to with Connection Request Accepted.

Field	Type
GUID	i64
Time	i64

Connection Request Accepted 0x10

Field	Type	Notes
Client address	ip
System index	int8	Unknown what this does.
Internal IDs	ip*10	Unknown what these do. Empty ipts for all of them works.
Request time	int64
Time	int64

New Incoming Connection 0x13

Field	Type	Notes
Server address	ip
Internal address	int8	Unknown what this does.

Disconnect 0x15

This packet is empty.