kcp2k-go

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A Golang implementation of Mirror kcp (kcp2k)
Ready to use, can communicate directly with Mirror kcp

Introduction

The kcp2k included with the Mirror game framework customizes a communication protocol based on the underlying kcp protocol
Main feature comparison:

	Transmission Features	Handshake and Close
KCP2K	Supports reliable and unreliable transmission	Supported
KCP	Supports reliable transmission only	Not Supported

Examples

simple example

kcp2k Encoding

Adds a kcp2kHeader on top of the original transmission packet to support distinguishing between reliable and unreliable transmissions

1 byte	4 bytes
channel	cookie

channel:

• 1 Reliable Transmission
• 2 Unreliable Transmission

The cookie is a "credential" after the connection is established, and its official purpose is:

generate a random cookie for this connection to avoid UDP spoofing

Reliable Transmission Encoding

Mirror kcp supports handshake and close, with the first byte of the transmitted data being the control bit

type Kcp2kOpcode byte

const (
    Hello      Kcp2kOpcode = 1
    Ping       Kcp2kOpcode = 2
    Data       Kcp2kOpcode = 3
    Disconnect Kcp2kOpcode = 4
)

The final raw encoding sent via udp is:

1 byte	4 bytes	24 bytes	1 byte	N bytes
0x01	cookie	kcp protocol	Kcp2kOpcode	data

Unreliable Transmission Encoding

Unreliable transmission encoding is simpler, as follows:

1 byte	4 bytes	N bytes
0x02	cookie	data

Additional Information

kcp-go need exposing the interface to read a whole kcp data packet from the UDPSession
So, I forked and modified it: https://github.com/0990/kcp-go