RakNetty

RakNetty

RakNetty is a clean and modern implementation (port) of Oculus's RakNet in java.

Why RakNetty?

RakNet is a networking library used by many project, including the renowned Minecraft: Bedrock Edition and Unity Engine. RakNet uses UDP as its networking protocol, which is connectionless by default and packets are not guaranteed to reach the destination, in comparison with TCP. RakNet implements a number of algorithms to ensure that packets can be delivered in an ordered and reliable way. RakNetty ports the protocol and algorithms to java.

RakNetty is built based on Netty, a high-performance asynchronous event-driven framework. In comparison with the original c++ version using Blocking IO, RakNetty has the advantages of Non-blocking IO to further improve the overall performance, which is achieved by dispatching the packets to be handled by multiple threads. In comparison, the original version of RakNet also handles the packets for all connections in a single thread.

Current status

Currently, RakNetty is functional and supports most RakNet features, but only trivially tested. The codes are also organised in a Netty-like structure with Java style conversion rather than a byte-to-byte copy of the original c++ version.

Usage

Maven repository

<repositories>
    <repository>
        <id>nukkit-releases</id>
        <url>https://nukkit.org/nexus/repository/maven-releases/</url>
    </repository>
</repositories>

Dependency

<dependency>
    <groupId>org.nukkit</groupId>
    <artifactId>raknetty</artifactId>
    <version>1.0</version>
</dependency>

Create a client

See Example Client

Create a server

See Example Server

Channel Options

RakNet defines a number of constants in its original code, which allows the developers to override them by redefining. Minecraft: Bedrock Edition uses a different version of RakNet and changes some constants. For purpose of general use, RakNetty supports the override of constants in a different way, by making advantage of Netty's Channel Options.

Server options

Option	Description	Default RakNet	Bedrock
RAKNET_GUID	Guid of the server	Random	Random
RAKNET_NUMBER_OF_INTERNAL_IDS	Size of address list in connection request	10	20
RAKNET_PROTOCOL_VERSION	Version of RakNet protocol	6	10
RAKNET_MAX_CONNECTIONS	Number of maximum connections	User-specific	User-specific
RAKNET_MAX_MTU_SIZE	Maximum allowable MTU size	1492	1400
RAKNET_OFFLINE_RESPONSE	Offline response when pinging	String	Server MOTD

Usage:

ServerBootstrap boot; // your own server bootstrap

boot.option(RakServerChannelOption.RAKNET_GUID, 123456L)
    .option(RakServerChannelOption.RAKNET_NUMBER_OF_INTERNAL_IDS, 20)
    .option(RakServerChannelOption.RAKNET_PROTOCOL_VERSION, 10)
    .option(RakServerChannelOption.RAKNET_MAX_CONNECTIONS, 15)
    .option(RakServerChannelOption.RAKNET_MAX_MTU_SIZE, 1400)
    .option(RakServerChannelOption.RAKNET_OFFLINE_RESPONSE, new ExampleBedrockPingResponse());

Client options

Option	Description	Default RakNet	Bedrock
RAKNET_GUID	Guid of the server	Random	Random
RAKNET_NUMBER_OF_INTERNAL_IDS	Size of address list in connection request	10	20
RAKNET_PROTOCOL_VERSION	Version of RakNet protocol	6	10
RAKNET_CONNECT_MTU_SIZES	Sizes for trial to detect the MTU size	1492, 1200, 576	1492, 1200, 576
RAKNET_CONNECT_ATTEMPTS	Attempts to be made before the connection request failed	6	12
RAKNET_CONNECT_INTERVAL	Interval between each connection request	1000	500
RAKNET_CONNECT_TIMEOUT	Timeout of connection request	0	0
RAKNET_UNRELIABLE_TIMEOUT	Timeout of unreliable packets to be discarded	0	0
RAKNET_TIMEOUT	Timeout of connection	10000	10000

Usage:

Bootstrap boot; // your own bootstrap

boot.option(RakChannelOption.RAKNET_GUID, 654321L)
    .option(RakChannelOption.RAKNET_NUMBER_OF_INTERNAL_IDS, 20)
    .option(RakChannelOption.RAKNET_PROTOCOL_VERSION, 10)
    .option(RakChannelOption.RAKNET_CONNECT_INTERVAL, 500)
    .option(RakChannelOption.RAKNET_CONNECT_ATTEMPTS, 12);