[![GoDoc][1]][2] [![Powered][9]][10] [![MIT licensed][11]][12] [![Build Status][3]][4] [![Go Report Card][5]][6] [![Coverage Statusd][7]][8] [1]: https://godoc.org/github.com/xtaci/kcp-go?status.svg [2]: https://godoc.org/github.com/xtaci/kcp-go [3]: https://travis-ci.org/xtaci/kcp-go.svg?branch=master [4]: https://travis-ci.org/xtaci/kcp-go [5]: https://goreportcard.com/badge/github.com/xtaci/kcp-go [6]: https://goreportcard.com/report/github.com/xtaci/kcp-go [7]: https://codecov.io/gh/xtaci/kcp-go/branch/master/graph/badge.svg [8]: https://codecov.io/gh/xtaci/kcp-go [9]: https://img.shields.io/badge/KCP-Powered-blue.svg [10]: https://github.com/skywind3000/kcp [11]: https://img.shields.io/badge/license-MIT-blue.svg [12]: LICENSE [](https://en.wikipedia.org/wiki/Claude_Shannon) ## Introduction kcp-go is a full-featured ***Reliable-UDP*** library for golang. It provides ***reliable, ordered, and error-checked*** delivery of a stream of octets between applications running on hosts communicating over an IP network. ## Features 1. Optimized for ***Online Games, Audio/Video Streaming***. 1. Compatible with [skywind3000's](https://github.com/skywind3000) C version with optimizations. 1. ***Cache friendly*** and ***Memory optimized*** design in golang. 1. Compatible with [net.Conn](https://golang.org/pkg/net/#Conn) and [net.Listener](https://golang.org/pkg/net/#Listener). 1. [FEC(Forward Error Correction)](https://en.wikipedia.org/wiki/Forward_error_correction) Support with [Reed-Solomon Codes](https://en.wikipedia.org/wiki/Reed%E2%80%93Solomon_error_correction) 1. Packet level encryption support with [AES](https://en.wikipedia.org/wiki/Advanced_Encryption_Standard), [TEA](https://en.wikipedia.org/wiki/Tiny_Encryption_Algorithm), [3DES](https://en.wikipedia.org/wiki/Triple_DES), [Blowfish](https://en.wikipedia.org/wiki/Blowfish_(cipher)), [Cast5](https://en.wikipedia.org/wiki/CAST-128), [Salsa20]( https://en.wikipedia.org/wiki/Salsa20), etc. in [CFB](https://en.wikipedia.org/wiki/Block_cipher_mode_of_operation#Cipher_Feedback_.28CFB.29) mode. ## Conventions Control messages like SYN/FIN/RST in TCP ***are not defined*** in KCP, you need some ***keepalive mechanims*** in the application-level. a real world example is to use some ***multiplexing*** protocol over session, such as [smux](https://github.com/xtaci/smux), see [kcptun](https://github.com/xtaci/kcptun) for example. ## Documentation For complete documentation, see the associated [Godoc](https://godoc.org/github.com/xtaci/kcp-go). ## Specification ## Usage Client: [full demo](https://github.com/xtaci/kcptun/blob/master/client/main.go#L231) ```go kcpconn, err := kcp.DialWithOptions("192.168.0.1:10000", nil, 10, 3) ``` Server: [full demo](https://github.com/xtaci/kcptun/blob/master/server/main.go#L235) ```go lis, err := kcp.ListenWithOptions(":10000", nil, 10, 3) ``` ## Performance ``` 型号名称： MacBook Pro 型号标识符： MacBookPro12,1 处理器名称： Intel Core i5 处理器速度： 2.7 GHz 处理器数目： 1 核总数： 2 L2 缓存（每个核）： 256 KB L3 缓存： 3 MB 内存： 8 GB ``` ``` $ go test -run Speed new client 127.0.0.1:61165 total recv: 16777216 time for 16MB rtt with encryption 570.41176ms &{BytesSent:33554432 BytesReceived:33554432 MaxConn:2 ActiveOpens:1 PassiveOpens:1 CurrEstab:1 InErrs:0 InCsumErrors:0 InSegs:42577 OutSegs:42641 OutBytes:48111336 RetransSegs:92 FastRetransSegs:92 LostSegs:0 RepeatSegs:0 FECRecovered:1 FECErrs:0 FECSegs:8514} PASS ok github.com/xtaci/kcp-go 0.600s ``` ## Who is using this? 1. https://github.com/xtaci/kcptun 2. https://github.com/getlantern/lantern 3. https://github.com/smallnest/rpcx ## Links 1. https://github.com/xtaci/libkcp -- FEC enhanced KCP session library for iOS/Android in C++ 2. https://github.com/skywind3000/kcp -- A Fast and Reliable ARQ Protocol 3. https://github.com/klauspost/reedsolomon -- Reed-Solomon Erasure Coding in Go