a bugfix in kcp-go, upgrade to kcp-go/v5@v5.5.9

commit 58d2c9d3468aa1c04f8cb60f0680186b6330804c
Author: xtaci <daniel820313@gmail.com>
Date:   Thu Dec 26 17:40:36 2019 +0800

    combine smux v1 & v2

.github/ISSUE_TEMPLATE

@@ -0,0 +1,29 @@
+问问题前先搜索ISSUE，并搞清楚下面的问题:
+
+1. 检查 ```-key xxx``` 至少三遍, ***保证***两边一致。
+2. 保证```-nocomp, -datashard, -parityshard,  -key, -crypt, -smuxver```两边一致。
+3. 是否在服务器端，正确设定了转发的目标服务器地址 ***--target***。
+4. 是否在客户端，正确的连接到了 client的监听端口。
+5. 如果第3条不确定，尝试在服务器上telnet target port试试。
+6. 防火墙是否关闭了UDP通信，或者设置了UDP的最大发包速率？
+7. 两端的版本是否一致？
+8. 是不是最新版本？
+9. 两端分别是什么操作系统？
+10. 两端的输出日志是什么？
+
+Before firing issue, make sure you figured out the following common questions.
+
+PLEASE DO SEARCH FIRST.
+
+1. Check your ```-key xxx``` for at least 3 times, ***MAKE SURE*** both sides share the same secret.
+2. ```-nocomp, -datashard, -parityshard,  -key, -crypt, -smuxver``` ***must be the same*** on both side.
+3. Did you correctly set the ***-target*** on the server side?
+4. Did you correctly connected to the listening port on client side?
+5. ***MAKE SURE*** ```telnet target port``` on your server successful(don't ask me why couldn't).
+6. Does your ***firewall allows UDP*** communications? (including your ISP Cable-Modem)
+7. Are you using the **same version** for both client & server
+8. Are you using the **latest release**?
+9. Which **OS** do you use?
+10. Which end for this issue related to, **client or server**?
+
+

.gitignore

@@ -24,3 +24,5 @@ _testmain.go
 *.prof
 client/client
 server/server
+build/*
+.DS_Store

.travis.yml

@@ -1,16 +1,16 @@
 language: go
 go:
-    - 1.6
+    - 1.13.x
 before_install:
     - go get github.com/mattn/goveralls
     - go get golang.org/x/tools/cmd/cover
 install:
-    - go get github.com/xtaci/kcptun/client
-    - go get github.com/xtaci/kcptun/server
+    - env GO111MODULE=on go get github.com/xtaci/kcptun/client
+    - env GO111MODULE=on go get github.com/xtaci/kcptun/server
 before_script:
 script:
     - cd $HOME/gopath/src/github.com/xtaci/kcptun/client
-    - $HOME/gopath/bin/goveralls -service=travis-ci
+    - env GO111MODULE=on $HOME/gopath/bin/goveralls -service=travis-ci
     - cd $HOME/gopath/src/github.com/xtaci/kcptun/server
-    - $HOME/gopath/bin/goveralls -service=travis-ci
+    - env GO111MODULE=on $HOME/gopath/bin/goveralls -service=travis-ci
     - exit 0

Dockerfile

@@ -1,6 +1,12 @@
-FROM golang:latest
+FROM golang:alpine as builder
 MAINTAINER xtaci <daniel820313@gmail.com>
-RUN go get github.com/xtaci/kcptun/client
-RUN go get github.com/xtaci/kcptun/server
+ENV GO111MODULE=on
+RUN apk update && \
+    apk upgrade && \
+    apk add git gcc libc-dev linux-headers
+RUN go get -ldflags "-X main.VERSION=$(date -u +%Y%m%d) -s -w" github.com/xtaci/kcptun/client && go get -ldflags "-X main.VERSION=$(date -u +%Y%m%d) -s -w" github.com/xtaci/kcptun/server
+
+FROM alpine:3.9
+COPY --from=builder /go/bin /bin
 EXPOSE 29900/udp
 EXPOSE 12948

README.md

@@ -1,83 +1,305 @@
-# <img src="logo.png" alt="kcptun" height="60px" /> 
-[![GoDoc][1]][2] [![Release][13]][14] [![Powered][17]][18] [![Build Status][3]][4] [![Go Report Card][5]][6] [![Downloads][15]][16] 
-[1]: https://godoc.org/github.com/xtaci/kcptun?status.svg
-[2]: https://godoc.org/github.com/xtaci/kcptun
+# <img src="logo.png" alt="kcptun" height="54px" /> 
+
+[![Release][13]][14] [![Powered][17]][18] [![MIT licensed][11]][12] [![Build Status][3]][4] [![Go Report Card][5]][6] [![Downloads][15]][16] [![Docker][1]][2] 
+
+[1]: https://img.shields.io/docker/pulls/xtaci/kcptun
+[2]: https://hub.docker.com/r/xtaci/kcptun
 [3]: https://travis-ci.org/xtaci/kcptun.svg?branch=master
 [4]: https://travis-ci.org/xtaci/kcptun
 [5]: https://goreportcard.com/badge/github.com/xtaci/kcptun
 [6]: https://goreportcard.com/report/github.com/xtaci/kcptun
-[7]: https://img.shields.io/badge/license-MIT-blue.svg
-[8]: https://raw.githubusercontent.com/xtaci/kcptun/master/LICENSE.md
-[9]: https://img.shields.io/github/stars/xtaci/kcptun.svg
-[10]: https://github.com/xtaci/kcptun/stargazers
-[11]: https://img.shields.io/github/forks/xtaci/kcptun.svg
-[12]: https://github.com/xtaci/kcptun/network
-[13]: https://img.shields.io/github/release/xtaci/kcptun.svg
+[11]: https://img.shields.io/github/license/xtaci/kcptun
+[12]: LICENSE.md
+[13]: https://img.shields.io/github/v/release/xtaci/kcptun?color=orange
 [14]: https://github.com/xtaci/kcptun/releases/latest
-[15]: https://img.shields.io/github/downloads/xtaci/kcptun/total.svg?maxAge=2592000
+[15]: https://img.shields.io/github/downloads/xtaci/kcptun/total.svg?maxAge=1800&color=orange
 [16]: https://github.com/xtaci/kcptun/releases
 [17]: https://img.shields.io/badge/KCP-Powered-blue.svg
 [18]: https://github.com/skywind3000/kcp
-[19]: https://img.shields.io/docker/pulls/xtaci/kcptun.svg?maxAge=2592000
-[20]: https://hub.docker.com/r/xtaci/kcptun/
 
-TCP流转换为KCP+UDP流，:zap:***[官方下载地址](https://github.com/xtaci/kcptun/releases/latest)***:zap:工作示意图：  
+<img src="kcptun.png" alt="kcptun" height="300px"/>
 
-![kcptun](kcptun.png)
+> *Disclaimer: kcptun maintains a single website — [github.com/xtaci/kcptun](https://github.com/xtaci/kcptun). Any websites other than [github.com/xtaci/kcptun](https://github.com/xtaci/kcptun) are not endorsed by xtaci.*
 
-***kcptun是[kcp-go](https://github.com/xtaci/kcp-go)的一个测试应用，可以用于任意tcp网络程序的传输承载(尤其用于游戏数据传输测试)，用于优化丢包环境下的网络流畅度。***   
+### Requirements
+
+| Target | Minimum | Recommended |
+| --- | --- | --- |
+| System | aix darwin dragonfly freebsd linux netbsd openbsd solaris windows | linux |
+| Memory | >20MB | >32MB |
+| CPU | ANY | amd64 with AES-NI & AVX2 |
+
+
+### QuickStart
+
+Increase the number of open files on your server, as:
+
+`ulimit -n 65535`, or write it in `~/.bashrc`.
+
+Suggested `sysctl.conf` parameters for better handling of UDP packets:
 
-### *快速设定* :lollipop:
 ```
-服务器: ./server_linux_amd64 -t "127.0.0.1:1080" -l ":554" -mode fast2  // 转发到本地1080端口
-客户端: ./client_darwin_amd64 -r "服务器IP地址:554" -l ":1080" -mode fast2    // 监听本地1080端口
+net.core.rmem_max=26214400 // BDP - bandwidth delay product
+net.core.rmem_default=26214400
+net.core.wmem_max=26214400
+net.core.wmem_default=26214400
+net.core.netdev_max_backlog=2048 // proportional to -rcvwnd
 ```
 
-### *使用の方法* :lollipop:
-![client](client.png)
-![server](server.png)
-
-### *适用范围限定* :lollipop:   
-1. 实时网络游戏的数据传输        
-2. 跨运营商的流量传输               
-3. 其他高丢包通信链路的TCP承载      
-
-### *推荐参数* :lollipop: 
+You can also increase the per-socket buffer by adding parameter(default 4MB):
 ```
-适用大部分ADSL接入（非对称上下行）的参数（实验环境电信100M ADSL）
-SERVER:   -mtu 1400 -sndwnd 2048 -rcvwnd 2048 -mode fast2
-CLIENT:   -mtu 1400 -sndwnd 256 -rcvwnd 2048 -mode fast2 -dscp 46
+-sockbuf 16777217
+```
+for **slow processors**, increasing this buffer is **CRITICAL** to receive packets properly.
+
+Download a corresponding one from precompiled [Releases](https://github.com/xtaci/kcptun/releases).
+
+```
+KCP Client: ./client_darwin_amd64 -r "KCP_SERVER_IP:4000" -l ":8388" -mode fast3 -nocomp -autoexpire 900 -sockbuf 16777217 -dscp 46
+KCP Server: ./server_linux_amd64 -t "TARGET_IP:8388" -l ":4000" -mode fast3 -nocomp -sockbuf 16777217 -dscp 46
+```
+The above commands will establish port forwarding channel for 8388/tcp as:
+
+> Application -> **KCP Client(8388/tcp) -> KCP Server(4000/udp)** -> Target Server(8388/tcp) 
+
+which tunnels the original connection:
+
+> Application -> Target Server(8388/tcp) 
+
+### Build from source
+
+```
+$ git clone https://github.com/xtaci/kcptun.git
+$ cd kcptun
+$ ./build-release.sh
+$ cd build
 ```
 
-*简易调优方法*：
-> 第一步：同时在两端逐步增大client rcvwnd和server sndwnd;        
-> 第二步：尝试下载，观察如果带宽利用率接近物理带宽则停止，否则跳转到第一步。       
+All precompiled releases are genereated from `build-release.sh` script.
 
-*巭孬嫑乱动*        
+### Performance
 
-### *DSCP* :lollipop: 
-DSCP差分服务代码点（Differentiated Services Code Point），IETF于1998年12月发布了Diff-Serv（Differentiated Service）的QoS分类标准。它在每个数据包IP头部的服务类别TOS标识字节中，利用已使用的6比特和未使用的2比特，通过编码值来区分优先级。     
-常用DSCP值可以参考[Wikipedia DSCP](https://en.wikipedia.org/wiki/Differentiated_services#Commonly_used_DSCP_values)，至于有没有用，完全取决于数据包经过的设备。
+<img src="fast.png" alt="fast.com" height="256px" />  
+
+![bandwidth](bw.png)
+
+![flame](flame.png)
+
+> Practical bandwidth graph with parameters:  -mode fast3 -ds 10 -ps 3
+
+
+
+### Basic Tuning Guide
+
+#### Improving Thoughput
+
+> **Q: I have a high speed network link, how to reach the maximum bandwidth?**        
+
+> **A:** Increase `-rcvwnd` on KCP Client and `-sndwnd` on KCP Server **simultaneously & gradually**, the mininum one decides the maximum transfer rate of the link, as `wnd * mtu / rtt`; Then try downloading something and to see if it meets your requirements. 
+(mtu is adjustable by `-mtu`)
+
+#### Improving Latency
+
+> **Q: I'm using kcptun for game, I don't want any lag happening.**    
+
+> **A:** Lag means packet loss for most of the time, lags can be improved by changing `-mode`.
+
+> eg: `-mode fast3`    
+
+> Aggresiveness/Responsiveness on retransmission for embeded modes are:
+
+> *fast3 > fast2 > fast > normal > default*
+
+#### HOLB
+
+Since streams are multiplexed into a single physical channel, head of line blocking may appear under certain circumstances, by
+increasing `-smuxbuf` to a larger value (default 4MB) may mitigate this problem, obviously this will costs more memory.
+
+For versions >= v20190924, you can switch to smux version 2, smux v2 has options to limit per-stream memory usage, now set `-smuxver 2` to enable smux v2, and adjust `-streambuf` to limit per-stream memory usage, eg: `-streambuf 2097152` can limit per-stream memory usage to 2MB. By limiting stream buffer on the receiver side, a back-pressure will be conducted to the sender and limits reading, and finally prevent source from sending too much data to occupy every bits of buffer along the link. (Setting -smuxver **MUST** be **IDENTICAL** on both side, default is 1. )
+
+#### Slow Devices
+
+kcptun made use of **ReedSolomon-Codes** to recover lost packets, which requires massive amount of computation, a low-end ARM device cannot satisfy kcptun well. To unleash the full potential of kcptun, a multi-core x86 homeserver CPU like AMD Opteron is recommended.
+If you insist on running under some ARM routers, you'd better turn off `FEC` and use `salsa20` as the encryption method.
+
+### Expert Tuning Guide
+
+#### Overview
+
+<p align="left"><img src="layeredparams.png" alt="params" height="450px"/></p>
+
+#### Usage
 
-### *内置模式* :lollipop: 
-响应速度:     
-*fast3 >* ***[fast2]*** *> fast > normal > default*        
-有效载荷比:     
-*default > normal > fast >* ***[fast2]*** *> fast3*       
-中间mode参数比较均衡，总之就是越快越浪费带宽，推荐模式 ***fast2***         
-更高级的 ***手动档*** 需要理解KCP协议，并通过 ***隐藏参数*** 调整，例如:
 ```
- -mode manual -nodelay 1 -resend 2 -nc 1 -interval 20
+➜  ~ ./client_linux_amd64 -h
+NAME:
+   kcptun - client(with SMUX)
+
+USAGE:
+   client_linux_amd64 [global options] command [command options] [arguments...]
+
+VERSION:
+   20190924
+
+COMMANDS:
+   help, h  Shows a list of commands or help for one command
+
+GLOBAL OPTIONS:
+   --localaddr value, -l value      local listen address (default: ":12948")
+   --remoteaddr value, -r value     kcp server address (default: "vps:29900")
+   --key value                      pre-shared secret between client and server (default: "it's a secrect") [$KCPTUN_KEY]
+   --crypt value                    aes, aes-128, aes-192, salsa20, blowfish, twofish, cast5, 3des, tea, xtea, xor, sm4, none (default: "aes")
+   --mode value                     profiles: fast3, fast2, fast, normal, manual (default: "fast")
+   --conn value                     set num of UDP connections to server (default: 1)
+   --autoexpire value               set auto expiration time(in seconds) for a single UDP connection, 0 to disable (default: 0)
+   --scavengettl value              set how long an expired connection can live(in sec), -1 to disable (default: 600)
+   --mtu value                      set maximum transmission unit for UDP packets (default: 1350)
+   --sndwnd value                   set send window size(num of packets) (default: 128)
+   --rcvwnd value                   set receive window size(num of packets) (default: 512)
+   --datashard value, --ds value    set reed-solomon erasure coding - datashard (default: 10)
+   --parityshard value, --ps value  set reed-solomon erasure coding - parityshard (default: 3)
+   --dscp value                     set DSCP(6bit) (default: 0)
+   --nocomp                         disable compression
+   --sockbuf value                  per-socket buffer in bytes (default: 4194304)
+   --smuxver value                  specify smux version, available 1,2 (default: 1)
+   --smuxbuf value                  the overall de-mux buffer in bytes (default: 4194304)
+   --streambuf value                per stream receive buffer in bytes, smux v2+ (default: 2097152)
+   --keepalive value                seconds between heartbeats (default: 10)
+   --snmplog value                  collect snmp to file, aware of timeformat in golang, like: ./snmp-20060102.log
+   --snmpperiod value               snmp collect period, in seconds (default: 60)
+   --log value                      specify a log file to output, default goes to stderr
+   --quiet                          to suppress the 'stream open/close' messages
+   --tcp                            to emulate a TCP connection(linux)
+   -c value                         config from json file, which will override the command from shell
+   --help, -h                       show help
+   --version, -v                    print the version
+   
+➜  ~ ./server_linux_amd64 -h
+NAME:
+   kcptun - server(with SMUX)
+
+USAGE:
+   server_linux_amd64 [global options] command [command options] [arguments...]
+
+VERSION:
+   20190924
+
+COMMANDS:
+   help, h  Shows a list of commands or help for one command
+
+GLOBAL OPTIONS:
+   --listen value, -l value         kcp server listen address (default: ":29900")
+   --target value, -t value         target server address, or path/to/unix_socket (default: "127.0.0.1:12948")
+   --key value                      pre-shared secret between client and server (default: "it's a secrect") [$KCPTUN_KEY]
+   --crypt value                    aes, aes-128, aes-192, salsa20, blowfish, twofish, cast5, 3des, tea, xtea, xor, sm4, none (default: "aes")
+   --mode value                     profiles: fast3, fast2, fast, normal, manual (default: "fast")
+   --mtu value                      set maximum transmission unit for UDP packets (default: 1350)
+   --sndwnd value                   set send window size(num of packets) (default: 1024)
+   --rcvwnd value                   set receive window size(num of packets) (default: 1024)
+   --datashard value, --ds value    set reed-solomon erasure coding - datashard (default: 10)
+   --parityshard value, --ps value  set reed-solomon erasure coding - parityshard (default: 3)
+   --dscp value                     set DSCP(6bit) (default: 0)
+   --nocomp                         disable compression
+   --sockbuf value                  per-socket buffer in bytes (default: 4194304)
+   --smuxver value                  specify smux version, available 1,2 (default: 1)
+   --smuxbuf value                  the overall de-mux buffer in bytes (default: 4194304)
+   --streambuf value                per stream receive buffer in bytes, smux v2+ (default: 2097152)
+   --keepalive value                seconds between heartbeats (default: 10)
+   --snmplog value                  collect snmp to file, aware of timeformat in golang, like: ./snmp-20060102.log
+   --snmpperiod value               snmp collect period, in seconds (default: 60)
+   --pprof                          start profiling server on :6060
+   --log value                      specify a log file to output, default goes to stderr
+   --quiet                          to suppress the 'stream open/close' messages
+   --tcp                            to emulate a TCP connection(linux)
+   -c value                         config from json file, which will override the command from shell
+   --help, -h                       show help
+   --version, -v                    print the version
 ```
 
-### *前向纠错* :lollipop: 
-前向纠错采用Reed Solomon纠删码, 它的基本原理如下： 给定n个数据块d1, d2,…, dn，n和一个正整数m， RS根据n个数据块生成m个校验块， c1, c2,…, cm。 对于任意的n和m， 从n个原始数据块和m 个校验块中任取n块就能解码出原始数据， 即RS最多容忍m个数据块或者校验块同时丢失。
+#### Forward Error Correction
 
-![reed-solomon](rs.png)
+In coding theory, the [Reed–Solomon code](https://en.wikipedia.org/wiki/Reed%E2%80%93Solomon_error_correction) belongs to the class of non-binary cyclic error-correcting codes. The Reed–Solomon code is based on univariate polynomials over finite fields.
 
-通过```-datashard 10 -parityshard 3``` 可以调整Reed Solomon参数。
+It is able to detect and correct multiple symbol errors. By adding t check symbols to the data, a Reed–Solomon code can detect any combination of up to t erroneous symbols, or correct up to ⌊t/2⌋ symbols. As an erasure code, it can correct up to t known erasures, or it can detect and correct combinations of errors and erasures. Furthermore, Reed–Solomon codes are suitable as multiple-burst bit-error correcting codes, since a sequence of b + 1 consecutive bit errors can affect at most two symbols of size b. The choice of t is up to the designer of the code, and may be selected within wide limits.
+
+![FED](FEC.png)
+
+Setting parameters of RS-Code with ```-datashard m -parityshard n``` on **BOTH** KCP Client & KCP Server **MUST** be **IDENTICAL**.
+
+#### DSCP
+
+Differentiated services or DiffServ is a computer networking architecture that specifies a simple, scalable and coarse-grained mechanism for classifying and managing network traffic and providing quality of service (QoS) on modern IP networks. DiffServ can, for example, be used to provide low-latency to critical network traffic such as voice or streaming media while providing simple best-effort service to non-critical services such as web traffic or file transfers.
+
+DiffServ uses a 6-bit differentiated services code point (DSCP) in the 8-bit differentiated services field (DS field) in the IP header for packet classification purposes. The DS field and ECN field replace the outdated IPv4 TOS field.
+
+setting each side with ```-dscp value```, Here are some [Commonly used DSCP values](https://en.wikipedia.org/wiki/Differentiated_services#Commonly_used_DSCP_values).
+
+#### Cryptanalysis
+
+kcptun is shipped with builtin packet encryption powered by various block encryption algorithms and works in [Cipher Feedback Mode](https://en.wikipedia.org/wiki/Block_cipher_mode_of_operation#Cipher_Feedback_(CFB)), for each packet to be sent, the encryption process will start from encrypting a [nonce](https://en.wikipedia.org/wiki/Cryptographic_nonce) from the [system entropy](https://en.wikipedia.org/wiki//dev/random), so encryption to same plaintexts never leads to a same ciphertexts thereafter.
+
+The contents of the packets are completely anonymous with encryption, including the headers(FEC,KCP), checksums and contents. Note that, no matter which encryption method you choose on you upper layer, if you disable encryption by specifying `-crypt none` to kcptun, the transmit will be insecure somehow, since the header is ***PLAINTEXT*** to everyone it would be susceptible to header tampering, such as jamming the *sliding window size*, *round-trip time*, *FEC property* and *checksums*. ```aes-128``` is suggested for minimal encryption since modern CPUs are shipped with [AES-NI](https://en.wikipedia.org/wiki/AES_instruction_set) instructions and performs even better than `salsa20`(check the table below).
+
+Other possible attacks to kcptun includes: a) [traffic analysis](https://en.wikipedia.org/wiki/Traffic_analysis), dataflow on specific websites may have pattern while interchanging data, but this type of eavesdropping has been mitigated by adapting [smux](https://github.com/xtaci/smux) to mix data streams so as to introduce noises, perfect solution to this has not appeared yet, theroretically by shuffling/mixing messages on larger scale network may mitigate this problem.  b) [replay attack](https://en.wikipedia.org/wiki/Replay_attack), since the asymmetrical encryption has not been introduced into kcptun for some reason, capturing the packets and replay them on a different machine is possible, (notice: hijacking the session and decrypting the contents is still *impossible*), so upper layers should contain a asymmetrical encryption system to guarantee the authenticity of each message(to process message exactly once), such as HTTPS/OpenSSL/LibreSSL, only by signing the requests with private keys can eliminate this type of attack. 
+
+Important: 
+1. `-crypt` and `-key` must be the same on both KCP Client & KCP Server.
+2. `-crypt xor` is also insecure and vulnerable to [known-plaintext attack](https://en.wikipedia.org/wiki/Known-plaintext_attack), do not use this unless you know what you are doing. (*cryptanalysis note: any type of [counter mode](https://en.wikipedia.org/wiki/Block_cipher_mode_of_operation#Counter_(CTR)) is insecure in packet encryption due to the shorten of counter period and leads to iv/nonce collision*)
+
+Benchmarks for crypto algorithms supported by kcptun:
+
+```
+BenchmarkSM4-4                 	   50000	     32087 ns/op	  93.49 MB/s	       0 B/op	       0 allocs/op
+BenchmarkAES128-4              	  500000	      3274 ns/op	 916.15 MB/s	       0 B/op	       0 allocs/op
+BenchmarkAES192-4              	  500000	      3587 ns/op	 836.34 MB/s	       0 B/op	       0 allocs/op
+BenchmarkAES256-4              	  300000	      3828 ns/op	 783.60 MB/s	       0 B/op	       0 allocs/op
+BenchmarkTEA-4                 	  100000	     15359 ns/op	 195.32 MB/s	       0 B/op	       0 allocs/op
+BenchmarkXOR-4                 	20000000	        90.2 ns/op	33249.02 MB/s	       0 B/op	       0 allocs/op
+BenchmarkBlowfish-4            	   50000	     26885 ns/op	 111.58 MB/s	       0 B/op	       0 allocs/op
+BenchmarkNone-4                	30000000	        45.8 ns/op	65557.11 MB/s	       0 B/op	       0 allocs/op
+BenchmarkCast5-4               	   50000	     34370 ns/op	  87.29 MB/s	       0 B/op	       0 allocs/op
+Benchmark3DES-4                	   10000	    117893 ns/op	  25.45 MB/s	       0 B/op	       0 allocs/op
+BenchmarkTwofish-4             	   50000	     33477 ns/op	  89.61 MB/s	       0 B/op	       0 allocs/op
+BenchmarkXTEA-4                	   30000	     45825 ns/op	  65.47 MB/s	       0 B/op	       0 allocs/op
+BenchmarkSalsa20-4             	  500000	      3282 ns/op	 913.90 MB/s	       0 B/op	       0 allocs/op
+```
+
+Benchmark result from openssl
+
+```
+$ openssl speed -evp aes-128-cfb
+Doing aes-128-cfb for 3s on 16 size blocks: 157794127 aes-128-cfb's in 2.98s
+Doing aes-128-cfb for 3s on 64 size blocks: 39614018 aes-128-cfb's in 2.98s
+Doing aes-128-cfb for 3s on 256 size blocks: 9971090 aes-128-cfb's in 2.99s
+Doing aes-128-cfb for 3s on 1024 size blocks: 2510877 aes-128-cfb's in 2.99s
+Doing aes-128-cfb for 3s on 8192 size blocks: 310865 aes-128-cfb's in 2.98s
+OpenSSL 1.0.2p  14 Aug 2018
+built on: reproducible build, date unspecified
+options:bn(64,64) rc4(ptr,int) des(idx,cisc,16,int) aes(partial) idea(int) blowfish(idx)
+compiler: clang -I. -I.. -I../include  -fPIC -fno-common -DOPENSSL_PIC -DOPENSSL_THREADS -D_REENTRANT -DDSO_DLFCN -DHAVE_DLFCN_H -arch x86_64 -O3 -DL_ENDIAN -Wall -DOPENSSL_IA32_SSE2 -DOPENSSL_BN_ASM_MONT -DOPENSSL_BN_ASM_MONT5 -DOPENSSL_BN_ASM_GF2m -DSHA1_ASM -DSHA256_ASM -DSHA512_ASM -DMD5_ASM -DAES_ASM -DVPAES_ASM -DBSAES_ASM -DWHIRLPOOL_ASM -DGHASH_ASM -DECP_NISTZ256_ASM
+The 'numbers' are in 1000s of bytes per second processed.
+type             16 bytes     64 bytes    256 bytes   1024 bytes   8192 bytes
+aes-128-cfb     847216.79k   850770.86k   853712.05k   859912.39k   854565.80k
+```
+
+The encrytion performance in kcptun is as fast as in openssl library(if not faster).
+
+
+#### Memory Control
+
+Routers, mobile devices are susceptible to memory consumption; by setting GOGC environment(eg: GOGC=20) will make the garbage collector to recycle faster.
+Reference: https://blog.golang.org/go15gc
+
+Primary memory allocation are done from a global buffer pool *xmit.Buf*, in kcp-go, when we need to allocate some bytes, we can get from that pool, and a *fixed-capacity* 1500 bytes(mtuLimit) will be returned, the *rx queue*, *tx queue* and *fec queue* all receive bytes from there, and they will return the bytes to the pool after using to prevent *unnecessary zer0ing* of bytes. 
+The pool mechanism maintained a *high watermark* for slice objects, these *in-flight* objects from the pool will survive from the perodical garbage collection, meanwhile the pool kept the ability to return the memory to runtime if in idle, `-sndwnd`,`-rcvwnd`,`-ds`, `-ps`, these parameters affect this *high watermark*, the larger the value, the bigger the memory consumption will be.
+
+`-smuxbuf` also affects the maximum memory consumption, this parameter maintains a subtle balance between *concurrency* and *resource*, you can increase this value(default 4MB) to boost concurrency if you have many clients to serve and you get a powerful server at the same time, and also you can decrease this value to serve only 1 or 2 clients and hope this program can run under some embeded SoC system with limited memory and only you can access. (Notice that the `-smuxbuf` value is not proprotional to concurrency, you need to test.)
+
+
+#### Compression
+
+kcptun has builtin snappy algorithms for compressing streams:
 
-### *Snappy数据流压缩* :lollipop: 
 > Snappy is a compression/decompression library. It does not aim for maximum
 > compression, or compatibility with any other compression library; instead,
 > it aims for very high speeds and reasonable compression. For instance,
@@ -85,52 +307,83 @@ DSCP差分服务代码点（Differentiated Services Code Point），IETF于1998
 > for most inputs, but the resulting compressed files are anywhere from 20% to
 > 100% bigger.
 
-Reference: http://google.github.io/snappy/
+> Reference: http://google.github.io/snappy/
+
+Compression may save bandwidth for **PLAINTEXT** data, it's quite useful for specific scenarios as cross-datacenter replications, by compressing the redologs in dbms or kafka-like message queues and then transfer the data streams across the continent can be much faster.
+
+Compression is enabled by default, you can disable it by setting ```-nocomp``` on **BOTH** KCP Client & KCP Server **MUST** be **IDENTICAL**.
+
+#### SNMP
 
-### *SNMP* :lollipop:
 ```go
-// Snmp defines network statistics indicator
 type Snmp struct {
-	BytesSent        uint64 // payload bytes sent
-	BytesReceived    uint64
-	MaxConn          uint64
-	ActiveOpens      uint64
-	PassiveOpens     uint64
-	CurrEstab        uint64
-	InErrs           uint64
-	InCsumErrors     uint64 // checksum errors
-	InSegs           uint64
-	OutSegs          uint64
-	OutBytes         uint64 // udp bytes sent
-	RetransSegs      uint64
-	FastRetransSegs  uint64
-	EarlyRetransSegs uint64
-	LostSegs         uint64
-	RepeatSegs       uint64
-	FECRecovered     uint64
-	FECErrs          uint64
-	FECSegs          uint64 // fec segments received
+    BytesSent        uint64 // bytes sent from upper level
+    BytesReceived    uint64 // bytes received to upper level
+    MaxConn          uint64 // max number of connections ever reached
+    ActiveOpens      uint64 // accumulated active open connections
+    PassiveOpens     uint64 // accumulated passive open connections
+    CurrEstab        uint64 // current number of established connections
+    InErrs           uint64 // UDP read errors reported from net.PacketConn
+    InCsumErrors     uint64 // checksum errors from CRC32
+    KCPInErrors      uint64 // packet iput errors reported from KCP
+    InPkts           uint64 // incoming packets count
+    OutPkts          uint64 // outgoing packets count
+    InSegs           uint64 // incoming KCP segments
+    OutSegs          uint64 // outgoing KCP segments
+    InBytes          uint64 // UDP bytes received
+    OutBytes         uint64 // UDP bytes sent
+    RetransSegs      uint64 // accmulated retransmited segments
+    FastRetransSegs  uint64 // accmulated fast retransmitted segments
+    EarlyRetransSegs uint64 // accmulated early retransmitted segments
+    LostSegs         uint64 // number of segs infered as lost
+    RepeatSegs       uint64 // number of segs duplicated
+    FECRecovered     uint64 // correct packets recovered from FEC
+    FECErrs          uint64 // incorrect packets recovered from FEC
+    FECParityShards  uint64 // FEC segments received
+    FECShortShards   uint64 // number of data shards that's not enough for recovery
 }
 ```
 
-使用```kill -SIGUSR1 pid``` 可以在控制台打印出SNMP信息，通常用于精细调整***当前链路的有效载荷比***。        
-观察```RetransSegs,FastRetransSegs,LostSegs,OutSegs```这几者的数值比例，用于参考调整```-mode manual,fec```的参数。        
+Sending a `SIGUSR1` signal to KCP Client or KCP Server will dump SNMP information to console, just like `/proc/net/snmp`. You can use this information to do fine-grained tuning.
 
-### *性能对比* :lollipop:
-```
-root@vultr:~# iperf -s
-------------------------------------------------------------
-Server listening on TCP port 5001
-TCP window size: 4.00 MByte (default)
-------------------------------------------------------------
-[  4] local 172.7.7.1 port 5001 connected with 172.7.7.2 port 55453
-[ ID] Interval       Transfer     Bandwidth
-[  4]  0.0-18.0 sec  5.50 MBytes  2.56 Mbits/sec     <-- connection via kcptun
-[  5] local 45.32.xxx.xxx port 5001 connected with 218.88.xxx.xxx port 17220
-[  5]  0.0-17.9 sec  2.12 MBytes   997 Kbits/sec     <-- direct connnection via tcp
-```
+### Manual Control
 
-### *免责申明* :warning:
-用户以各种方式使用本软件（包括但不限于修改使用、直接使用、通过第三方使用）的过程中，不得以任何方式利用本软件直接或间接从事违反中国法律、以及社会公德的行为。软件的使用者需对自身行为负责，因使用软件引发的一切纠纷，由使用者承担全部法律及连带责任。作者不承担任何法律及连带责任。       
+https://github.com/skywind3000/kcp/blob/master/README.en.md#protocol-configuration
 
-对免责声明的解释、修改及更新权均属于作者本人所有。
+`-mode manual -nodelay 1 -interval 20 -resend 2 -nc 1`
+
+Low-level KCP configuration can be altered by using manual mode like above, make sure you really **UNDERSTAND** what these means before doing **ANY** manual settings.
+
+
+### Identical Parmeters
+
+The parameters below **MUST** be **IDENTICAL** on **BOTH** side:
+
+1. -key
+1. -crypt
+1. -nocomp
+1. -datashard
+1. -parityshard
+1. -smuxver
+
+### References
+
+1. https://github.com/skywind3000/kcp -- KCP - A Fast and Reliable ARQ Protocol.
+1. https://github.com/xtaci/kcp-go/ -- A Production-Grade Reliable-UDP Library for golang
+1. https://github.com/klauspost/reedsolomon -- Reed-Solomon Erasure Coding in Go.
+1. https://en.wikipedia.org/wiki/Differentiated_services -- DSCP.
+1. http://google.github.io/snappy/ -- A fast compressor/decompressor.
+1. https://www.backblaze.com/blog/reed-solomon/ -- Reed-Solomon Explained.
+1. http://www.qualcomm.cn/products/raptorq -- RaptorQ Forward Error Correction Scheme for Object Delivery.
+1. https://en.wikipedia.org/wiki/PBKDF2 -- Key stretching.
+1. http://blog.appcanary.com/2016/encrypt-or-compress.html -- Should you encrypt or compress first?
+1. https://github.com/hashicorp/yamux -- Connection multiplexing library.
+1. https://tools.ietf.org/html/rfc6937 -- Proportional Rate Reduction for TCP.
+1. https://tools.ietf.org/html/rfc5827 -- Early Retransmit for TCP and Stream Control Transmission Protocol (SCTP).
+1. http://http2.github.io/ -- What is HTTP/2?
+1. http://www.lartc.org/ -- Linux Advanced Routing & Traffic Control
+1. https://en.wikipedia.org/wiki/Noisy-channel_coding_theorem -- Noisy channel coding theorem
+1. https://zhuanlan.zhihu.com/p/53849089 -- kcptun开发小记
+
+
+（注意：我没有任何社交网站的账号，请小心骗子。）

build-release-cgo.sh

@@ -0,0 +1,139 @@
+#!/bin/bash
+
+BUILD_DIR=$(dirname "$0")/build
+mkdir -p $BUILD_DIR
+cd $BUILD_DIR
+
+sum="sha1sum"
+
+if [ "$GO111MODULE" != "on" ]; then
+	echo "GO111MODULE is off"
+else
+	echo "GO111MODULE is on"
+fi 
+
+echo "Prerequisites for cross-compiling were written in build-release.sh"
+
+# required library for cross-compiling
+# sudo apt-get install -y automake autogen build-essential ca-certificates   gcc-5-arm-linux-gnueabi g++-5-arm-linux-gnueabi libc6-dev-armel-cross   gcc-5-arm-linux-gnueabihf g++-5-arm-linux-gnueabihf libc6-dev-armhf-cross gcc-5-aarch64-linux-gnu g++-5-aarch64-linux-gnu libc6-dev-arm64-cross  gcc-5-mips-linux-gnu g++-5-mips-linux-gnu libc6-dev-mips-cross gcc-5-mipsel-linux-gnu g++-5-mipsel-linux-gnu libc6-dev-mipsel-cross  gcc-5-mips64-linux-gnuabi64 g++-5-mips64-linux-gnuabi64 libc6-dev-mips64-cross  gcc-5-mips64el-linux-gnuabi64 g++-5-mips64el-linux-gnuabi64 libc6-dev-mips64el-cross  gcc-5-multilib g++-5-multilib gcc-mingw-w64 g++-mingw-w64 clang llvm-dev   libtool libxml2-dev uuid-dev libssl-dev swig openjdk-8-jdk pkg-config patch  make xz-utils cpio wget zip unzip p7zip git mercurial bzr texinfo help2man --no-install-recommends
+
+# if error message:
+#     /usr/include/linux/errno.h:1:23: fatal error: asm/errno.h: No such file or directory
+# try:
+#    ln -s /usr/include/asm-generic /usr/include/asm
+
+if ! hash sha1sum 2>/dev/null; then
+	if ! hash shasum 2>/dev/null; then
+		echo "I can't see 'sha1sum' or 'shasum'"
+		echo "Please install one of them!"
+		exit
+	fi
+	sum="shasum"
+fi
+
+UPX=false
+if hash upx 2>/dev/null; then
+	UPX=true
+fi
+
+VERSION=`date -u +%Y%m%d`
+LDFLAGS="-X main.VERSION=$VERSION -s -w"
+LDFLAGS_LINUX='-X main.VERSION='$VERSION' -s -w -linkmode "external" -extldflags "-static"'
+LDFLAGS_LINUX32='-X main.VERSION='$VERSION' -s -w -linkmode "external" -extldflags "-static -m32 -L/usr/lib32"'
+echo "-ldflag for linux/amd64:" $LDFLAGS_LINUX
+echo "-ldflag for linux/386:" $LDFLAGS_LINUX32
+echo "-ldflag for other:" $LDFLAGS
+
+echo "=== Building ==="
+
+# 386
+OSES=(linux windows)
+for os in ${OSES[@]}; do
+	suffix=""
+	if [ "$os" == "windows" ]
+	then
+		suffix=".exe"
+	fi
+
+	if [ "$os" == "linux" ];then
+		CC=gcc-5 CGO_ENABLED=1 GOOS=$os GOARCH=386 CGO_CFLAGS="-m32 -L/usr/lib32" CGO_CXXFLAGS="-m32 -L/usr/lib32" go build -ldflags "$LDFLAGS_LINUX32" -o client_${os}_386${suffix} github.com/xtaci/kcptun/client
+		CC=gcc-5 CGO_ENABLED=1 GOOS=$os GOARCH=386 CGO_CFLAGS="-m32 -L/usr/lib32" CGO_CXXFLAGS="-m32 -L/usr/lib32" go build -ldflags "$LDFLAGS_LINUX32" -o server_${os}_386${suffix} github.com/xtaci/kcptun/server
+	else 
+		CGO_ENABLED=0 GOOS=$os GOARCH=386 go build -ldflags "$LDFLAGS" -o client_${os}_386${suffix} github.com/xtaci/kcptun/client
+		CGO_ENABLED=0 GOOS=$os GOARCH=386 go build -ldflags "$LDFLAGS" -o server_${os}_386${suffix} github.com/xtaci/kcptun/server
+	fi
+
+	if $UPX; then upx -9 client_${os}_386${suffix} server_${os}_386${suffix};fi
+	tar -zcf kcptun-${os}-386-$VERSION.tar.gz client_${os}_386${suffix} server_${os}_386${suffix}
+	$sum kcptun-${os}-386-$VERSION.tar.gz
+done
+
+# AMD64 
+OSES=(linux darwin windows freebsd)
+for os in ${OSES[@]}; do
+	suffix=""
+	if [ "$os" == "windows" ]
+	then
+		suffix=".exe"
+	fi
+
+	if [ "$os" == "linux" ];then
+		CC=gcc-5 CGO_ENABLED=1 GOOS=$os GOARCH=amd64 go build -ldflags "$LDFLAGS_LINUX" -o client_${os}_amd64${suffix} github.com/xtaci/kcptun/client
+		CC=gcc-5 CGO_ENABLED=1 GOOS=$os GOARCH=amd64 go build -ldflags "$LDFLAGS_LINUX" -o server_${os}_amd64${suffix} github.com/xtaci/kcptun/server
+	else 
+		CGO_ENABLED=0 GOOS=$os GOARCH=amd64 go build -ldflags "$LDFLAGS" -o client_${os}_amd64${suffix} github.com/xtaci/kcptun/client
+		CGO_ENABLED=0 GOOS=$os GOARCH=amd64 go build -ldflags "$LDFLAGS" -o server_${os}_amd64${suffix} github.com/xtaci/kcptun/server
+	fi
+
+	if $UPX; then upx -9 client_${os}_amd64${suffix} server_${os}_amd64${suffix};fi
+	tar -zcf kcptun-${os}-amd64-$VERSION.tar.gz client_${os}_amd64${suffix} server_${os}_amd64${suffix}
+	$sum kcptun-${os}-amd64-$VERSION.tar.gz
+done
+
+# ARM-5
+#CC=arm-linux-gnueabi-gcc-5 GOOS=linux GOARCH=arm GOARM=5 CGO_ENABLED=1 CGO_CFLAGS="-march=armv5" CGO_CXXFLAGS="-march=armv5" go install std
+CC=arm-linux-gnueabi-gcc-5 CXX=arm-linux-gnueabi-g++-5 GOOS=linux GOARCH=arm GOARM=5 CGO_ENABLED=1 CGO_CFLAGS="-march=armv5" CGO_CXXFLAGS="-march=armv5" go build -ldflags "$LDFLAGS_LINUX"  -o client_linux_arm5  github.com/xtaci/kcptun/client
+CC=arm-linux-gnueabi-gcc-5 CXX=arm-linux-gnueabi-g++-5 GOOS=linux GOARCH=arm GOARM=5 CGO_ENABLED=1 CGO_CFLAGS="-march=armv5" CGO_CXXFLAGS="-march=armv5" go build -ldflags "$LDFLAGS_LINUX"  -o server_linux_arm5  github.com/xtaci/kcptun/server
+if $UPX; then upx -9 client_linux_arm5 server_linux_arm5;fi
+tar -zcf kcptun-linux-arm5-$VERSION.tar.gz client_linux_arm5 server_linux_arm5
+$sum kcptun-linux-arm5-$VERSION.tar.gz
+
+# ARM-6
+#CC=arm-linux-gnueabi-gcc-5 GOOS=linux GOARCH=arm GOARM=6 CGO_ENABLED=1 CGO_CFLAGS="-march=armv6" CGO_CXXFLAGS="-march=armv6" go install std
+CC=arm-linux-gnueabi-gcc-5 CXX=arm-linux-gnueabi-g++-5 GOOS=linux GOARCH=arm GOARM=6 CGO_ENABLED=1 CGO_CFLAGS="-march=armv6" CGO_CXXFLAGS="-march=armv6" go build -ldflags "$LDFLAGS_LINUX"  -o client_linux_arm6 github.com/xtaci/kcptun/client
+CC=arm-linux-gnueabi-gcc-5 CXX=arm-linux-gnueabi-g++-5 GOOS=linux GOARCH=arm GOARM=6 CGO_ENABLED=1 CGO_CFLAGS="-march=armv6" CGO_CXXFLAGS="-march=armv6" go build -ldflags "$LDFLAGS_LINUX"  -o server_linux_arm6 github.com/xtaci/kcptun/server
+if $UPX; then upx -9 client_linux_arm6 server_linux_arm6;fi
+tar -zcf kcptun-linux-arm6-$VERSION.tar.gz client_linux_arm6 server_linux_arm6
+$sum kcptun-linux-arm6-$VERSION.tar.gz
+
+# ARM-7
+ARMS=(7)
+#CC=arm-linux-gnueabihf-gcc-5 GOOS=linux GOARCH=arm GOARM=7 CGO_ENABLED=1 CGO_CFLAGS="-march=armv7-a" CGO_CXXFLAGS="-march=armv7-a" go install std
+CC=arm-linux-gnueabihf-gcc-5 CXX=arm-linux-gnueabihf-g++-5 GOOS=linux GOARCH=arm GOARM=7 CGO_ENABLED=1 CGO_CFLAGS="-march=armv7-a -fPIC" CGO_CXXFLAGS="-march=armv7-a -fPIC" go build -ldflags "$LDFLAGS_LINUX"  -o client_linux_arm7  github.com/xtaci/kcptun/client
+CC=arm-linux-gnueabihf-gcc-5 CXX=arm-linux-gnueabihf-g++-5 GOOS=linux GOARCH=arm GOARM=7 CGO_ENABLED=1 CGO_CFLAGS="-march=armv7-a -fPIC" CGO_CXXFLAGS="-march=armv7-a -fPIC" go build -ldflags "$LDFLAGS_LINUX"  -o server_linux_arm7  github.com/xtaci/kcptun/server
+if $UPX; then upx -9 client_linux_arm7 server_linux_arm7;fi
+tar -zcf kcptun-linux-arm7-$VERSION.tar.gz client_linux_arm7 server_linux_arm7
+$sum kcptun-linux-arm7-$VERSION.tar.gz
+
+# ARM64
+CC=aarch64-linux-gnu-gcc-5 CXX=aarch64-linux-gnu-g++-5 GOOS=linux GOARCH=arm64 CGO_ENABLED=1 go build -ldflags "$LDFLAGS_LINUX"  -o client_linux_arm64  github.com/xtaci/kcptun/client
+CC=aarch64-linux-gnu-gcc-5 CXX=aarch64-linux-gnu-g++-5 GOOS=linux GOARCH=arm64 CGO_ENABLED=1 go build -ldflags "$LDFLAGS_LINUX"  -o server_linux_arm64  github.com/xtaci/kcptun/server
+if $UPX; then upx -9 client_linux_arm64 server_linux_arm64*;fi
+tar -zcf kcptun-linux-arm64-$VERSION.tar.gz client_linux_arm64 server_linux_arm64
+$sum kcptun-linux-arm64-$VERSION.tar.gz
+
+#MIPS32LE
+CC=mipsel-linux-gnu-gcc-5 CXX=mipsel-linux-gnu-g++-5 GOOS=linux GOARCH=mipsle CGO_ENABLED=1 GOMIPS=softfloat go build -ldflags "$LDFLAGS_LINUX"  -o client_linux_mipsle github.com/xtaci/kcptun/client
+CC=mipsel-linux-gnu-gcc-5 CXX=mipsel-linux-gnu-g++-5 GOOS=linux GOARCH=mipsle CGO_ENABLED=1 GOMIPS=softfloat go build -ldflags "$LDFLAGS_LINUX"  -o server_linux_mipsle github.com/xtaci/kcptun/server
+
+#MIPS32
+CC=mips-linux-gnu-gcc-5 CXX=mips-linux-gnu-g++-5 GOOS=linux GOARCH=mips CGO_ENABLED=1 GOMIPS=softfloat go build -ldflags "$LDFLAGS_LINUX"  -o client_linux_mips github.com/xtaci/kcptun/client
+CC=mips-linux-gnu-gcc-5 CXX=mips-linux-gnu-g++-5 GOOS=linux GOARCH=mips CGO_ENABLED=1 GOMIPS=softfloat go build -ldflags "$LDFLAGS_LINUX"  -o server_linux_mips github.com/xtaci/kcptun/server
+
+if $UPX; then upx -9 client_linux_mips* server_linux_mips*;fi
+tar -zcf kcptun-linux-mipsle-$VERSION.tar.gz client_linux_mipsle server_linux_mipsle
+tar -zcf kcptun-linux-mips-$VERSION.tar.gz client_linux_mips server_linux_mips
+$sum kcptun-linux-mipsle-$VERSION.tar.gz
+$sum kcptun-linux-mips-$VERSION.tar.gz
+
+echo "=== Building Completed ==="

build-release.sh

@@ -1,8 +1,21 @@
 #!/bin/bash
-MD5='md5sum'
-unamestr=`uname`
-if [[ "$unamestr" == 'Darwin' ]]; then
-	MD5='md5'
+
+BUILD_DIR=$(dirname "$0")/build
+mkdir -p $BUILD_DIR
+cd $BUILD_DIR
+
+sum="sha1sum"
+
+export GO111MODULE=on
+echo "Setting GO111MODULE to" $GO111MODULE
+
+if ! hash sha1sum 2>/dev/null; then
+	if ! hash shasum 2>/dev/null; then
+		echo "I can't see 'sha1sum' or 'shasum'"
+		echo "Please install one of them!"
+		exit
+	fi
+	sum="shasum"
 fi
 
 UPX=false
@@ -12,30 +25,63 @@ fi
 
 VERSION=`date -u +%Y%m%d`
 LDFLAGS="-X main.VERSION=$VERSION -s -w"
+GCFLAGS=""
 
+# AMD64 
 OSES=(linux darwin windows freebsd)
-ARCHS=(amd64 386)
 for os in ${OSES[@]}; do
-	for arch in ${ARCHS[@]}; do
-		suffix=""
-		if [ "$os" == "windows" ]
-		then
-			suffix=".exe"
-		fi
-		env GOOS=$os GOARCH=$arch go build -ldflags "$LDFLAGS" -o client_${os}_${arch}${suffix} github.com/xtaci/kcptun/client
-		env GOOS=$os GOARCH=$arch go build -ldflags "$LDFLAGS" -o server_${os}_${arch}${suffix} github.com/xtaci/kcptun/server
-		if $UPX; then upx -9 client_${os}_${arch}${suffix} server_${os}_${arch}${suffix};fi
-		tar -zcf kcptun-${os}-${arch}-$VERSION.tar.gz client_${os}_${arch}${suffix} server_${os}_${arch}${suffix}
-		$MD5 kcptun-${os}-${arch}-$VERSION.tar.gz
-	done
+	suffix=""
+	if [ "$os" == "windows" ]
+	then
+		suffix=".exe"
+	fi
+	env CGO_ENABLED=0 GOOS=$os GOARCH=amd64 go build -ldflags "$LDFLAGS" -gcflags "$GCFLAGS" -o client_${os}_amd64${suffix} github.com/xtaci/kcptun/client
+	env CGO_ENABLED=0 GOOS=$os GOARCH=amd64 go build -ldflags "$LDFLAGS" -gcflags "$GCFLAGS" -o server_${os}_amd64${suffix} github.com/xtaci/kcptun/server
+	if $UPX; then upx -9 client_${os}_amd64${suffix} server_${os}_amd64${suffix};fi
+	tar -zcf kcptun-${os}-amd64-$VERSION.tar.gz client_${os}_amd64${suffix} server_${os}_amd64${suffix}
+	$sum kcptun-${os}-amd64-$VERSION.tar.gz
+done
+
+# 386
+OSES=(linux windows)
+for os in ${OSES[@]}; do
+	suffix=""
+	if [ "$os" == "windows" ]
+	then
+		suffix=".exe"
+	fi
+	env CGO_ENABLED=0 GOOS=$os GOARCH=386 go build -ldflags "$LDFLAGS" -gcflags "$GCFLAGS" -o client_${os}_386${suffix} github.com/xtaci/kcptun/client
+	env CGO_ENABLED=0 GOOS=$os GOARCH=386 go build -ldflags "$LDFLAGS" -gcflags "$GCFLAGS" -o server_${os}_386${suffix} github.com/xtaci/kcptun/server
+	if $UPX; then upx -9 client_${os}_386${suffix} server_${os}_386${suffix};fi
+	tar -zcf kcptun-${os}-386-$VERSION.tar.gz client_${os}_386${suffix} server_${os}_386${suffix}
+	$sum kcptun-${os}-386-$VERSION.tar.gz
 done
 
 # ARM
 ARMS=(5 6 7)
 for v in ${ARMS[@]}; do
-	env GOOS=linux GOARCH=arm GOARM=$v go build -ldflags "$LDFLAGS" -o client_linux_arm$v  github.com/xtaci/kcptun/client
-	env GOOS=linux GOARCH=arm GOARM=$v go build -ldflags "$LDFLAGS" -o server_linux_arm$v  github.com/xtaci/kcptun/server
+	env CGO_ENABLED=0 GOOS=linux GOARCH=arm GOARM=$v go build -ldflags "$LDFLAGS" -gcflags "$GCFLAGS" -o client_linux_arm$v  github.com/xtaci/kcptun/client
+	env CGO_ENABLED=0 GOOS=linux GOARCH=arm GOARM=$v go build -ldflags "$LDFLAGS" -gcflags "$GCFLAGS" -o server_linux_arm$v  github.com/xtaci/kcptun/server
+if $UPX; then upx -9 client_linux_arm$v server_linux_arm$v;fi
+tar -zcf kcptun-linux-arm$v-$VERSION.tar.gz client_linux_arm$v server_linux_arm$v
+$sum kcptun-linux-arm$v-$VERSION.tar.gz
 done
-if $UPX; then upx -9 client_linux_arm* server_linux_arm*;fi
-tar -zcf kcptun-linux-arm-$VERSION.tar.gz client_linux_arm* server_linux_arm*
-$MD5 kcptun-linux-arm-$VERSION.tar.gz
+
+# ARM64
+env CGO_ENABLED=0 GOOS=linux GOARCH=arm64 go build -ldflags "$LDFLAGS" -gcflags "$GCFLAGS" -o client_linux_arm64  github.com/xtaci/kcptun/client
+env CGO_ENABLED=0 GOOS=linux GOARCH=arm64 go build -ldflags "$LDFLAGS" -gcflags "$GCFLAGS" -o server_linux_arm64  github.com/xtaci/kcptun/server
+if $UPX; then upx -9 client_linux_arm64 server_linux_arm64*;fi
+tar -zcf kcptun-linux-arm64-$VERSION.tar.gz client_linux_arm64 server_linux_arm64
+$sum kcptun-linux-arm64-$VERSION.tar.gz
+
+#MIPS32LE
+env CGO_ENABLED=0 GOOS=linux GOARCH=mipsle GOMIPS=softfloat go build -ldflags "$LDFLAGS" -gcflags "$GCFLAGS" -o client_linux_mipsle github.com/xtaci/kcptun/client
+env CGO_ENABLED=0 GOOS=linux GOARCH=mipsle GOMIPS=softfloat go build -ldflags "$LDFLAGS" -gcflags "$GCFLAGS" -o server_linux_mipsle github.com/xtaci/kcptun/server
+env CGO_ENABLED=0 GOOS=linux GOARCH=mips GOMIPS=softfloat go build -ldflags "$LDFLAGS" -gcflags "$GCFLAGS" -o client_linux_mips github.com/xtaci/kcptun/client
+env CGO_ENABLED=0 GOOS=linux GOARCH=mips GOMIPS=softfloat go build -ldflags "$LDFLAGS" -gcflags "$GCFLAGS" -o server_linux_mips github.com/xtaci/kcptun/server
+
+if $UPX; then upx -9 client_linux_mips* server_linux_mips*;fi
+tar -zcf kcptun-linux-mipsle-$VERSION.tar.gz client_linux_mipsle server_linux_mipsle
+tar -zcf kcptun-linux-mips-$VERSION.tar.gz client_linux_mips server_linux_mips
+$sum kcptun-linux-mipsle-$VERSION.tar.gz
+$sum kcptun-linux-mips-$VERSION.tar.gz

client/config.go

@@ -0,0 +1,50 @@
+package main
+
+import (
+	"encoding/json"
+	"os"
+)
+
+// Config for client
+type Config struct {
+	LocalAddr    string `json:"localaddr"`
+	RemoteAddr   string `json:"remoteaddr"`
+	Key          string `json:"key"`
+	Crypt        string `json:"crypt"`
+	Mode         string `json:"mode"`
+	Conn         int    `json:"conn"`
+	AutoExpire   int    `json:"autoexpire"`
+	ScavengeTTL  int    `json:"scavengettl"`
+	MTU          int    `json:"mtu"`
+	SndWnd       int    `json:"sndwnd"`
+	RcvWnd       int    `json:"rcvwnd"`
+	DataShard    int    `json:"datashard"`
+	ParityShard  int    `json:"parityshard"`
+	DSCP         int    `json:"dscp"`
+	NoComp       bool   `json:"nocomp"`
+	AckNodelay   bool   `json:"acknodelay"`
+	NoDelay      int    `json:"nodelay"`
+	Interval     int    `json:"interval"`
+	Resend       int    `json:"resend"`
+	NoCongestion int    `json:"nc"`
+	SockBuf      int    `json:"sockbuf"`
+	SmuxVer      int    `json:"smuxver"`
+	SmuxBuf      int    `json:"smuxbuf"`
+	StreamBuf    int    `json:"streambuf"`
+	KeepAlive    int    `json:"keepalive"`
+	Log          string `json:"log"`
+	SnmpLog      string `json:"snmplog"`
+	SnmpPeriod   int    `json:"snmpperiod"`
+	Quiet        bool   `json:"quiet"`
+	TCP          bool   `json:"tcp"`
+}
+
+func parseJSONConfig(config *Config, path string) error {
+	file, err := os.Open(path) // For read access.
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+
+	return json.NewDecoder(file).Decode(config)
+}

client/dial.go

@@ -0,0 +1,18 @@
+package main
+
+import (
+	"github.com/pkg/errors"
+	kcp "github.com/xtaci/kcp-go/v5"
+	"github.com/xtaci/tcpraw"
+)
+
+func dial(config *Config, block kcp.BlockCrypt) (*kcp.UDPSession, error) {
+	if config.TCP {
+		conn, err := tcpraw.Dial("tcp", config.RemoteAddr)
+		if err != nil {
+			return nil, errors.Wrap(err, "tcpraw.Dial()")
+		}
+		return kcp.NewConn(config.RemoteAddr, block, config.DataShard, config.ParityShard, conn)
+	}
+	return kcp.DialWithOptions(config.RemoteAddr, block, config.DataShard, config.ParityShard)
+}

client/main.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"crypto/sha1"
+	"fmt"
 	"io"
 	"log"
 	"math/rand"
@@ -11,85 +12,77 @@ import (
 
 	"golang.org/x/crypto/pbkdf2"
 
-	"github.com/golang/snappy"
-	"github.com/hashicorp/yamux"
+	"github.com/pkg/errors"
 	"github.com/urfave/cli"
-	"github.com/xtaci/kcp-go"
+	kcp "github.com/xtaci/kcp-go/v5"
+	"github.com/xtaci/kcptun/generic"
+	"github.com/xtaci/smux"
 )
 
-var (
-	// VERSION is injected by buildflags
-	VERSION = "SELFBUILD"
+const (
 	// SALT is use for pbkdf2 key expansion
 	SALT = "kcp-go"
+	// maximum supported smux version
+	maxSmuxVer = 2
+	// stream copy buffer size
+	bufSize = 4096
 )
 
-type compStream struct {
-	conn net.Conn
-	w    *snappy.Writer
-	r    *snappy.Reader
-}
+// VERSION is injected by buildflags
+var VERSION = "SELFBUILD"
 
-func (c *compStream) Read(p []byte) (n int, err error) {
-	return c.r.Read(p)
-}
-
-func (c *compStream) Write(p []byte) (n int, err error) {
-	n, err = c.w.Write(p)
-	err = c.w.Flush()
-	return n, err
-}
-
-func (c *compStream) Close() error {
-	return c.conn.Close()
-}
-
-func newCompStream(conn net.Conn) *compStream {
-	c := new(compStream)
-	c.conn = conn
-	c.w = snappy.NewBufferedWriter(conn)
-	c.r = snappy.NewReader(conn)
-	return c
-}
-
-func handleClient(p1, p2 io.ReadWriteCloser) {
-	log.Println("stream opened")
-	defer log.Println("stream closed")
+// handleClient aggregates connection p1 on mux with 'writeLock'
+func handleClient(session *smux.Session, p1 net.Conn, quiet bool) {
+	logln := func(v ...interface{}) {
+		if !quiet {
+			log.Println(v...)
+		}
+	}
 	defer p1.Close()
+	p2, err := session.OpenStream()
+	if err != nil {
+		logln(err)
+		return
+	}
+
 	defer p2.Close()
 
-	// start tunnel
-	p1die := make(chan struct{})
-	go func() {
-		io.Copy(p1, p2)
-		close(p1die)
-	}()
+	logln("stream opened", "in:", p1.RemoteAddr(), "out:", fmt.Sprint(p2.RemoteAddr(), "(", p2.ID(), ")"))
+	defer logln("stream closed", "in:", p1.RemoteAddr(), "out:", fmt.Sprint(p2.RemoteAddr(), "(", p2.ID(), ")"))
 
-	p2die := make(chan struct{})
-	go func() {
-		io.Copy(p2, p1)
-		close(p2die)
-	}()
-
-	// wait for tunnel termination
-	select {
-	case <-p1die:
-	case <-p2die:
+	// start tunnel & wait for tunnel termination
+	streamCopy := func(dst io.Writer, src io.ReadCloser) {
+		if _, err := generic.Copy(dst, src); err != nil {
+			// report protocol error
+			if err == smux.ErrInvalidProtocol {
+				log.Println("smux", err, "in:", p1.RemoteAddr(), "out:", fmt.Sprint(p2.RemoteAddr(), "(", p2.ID(), ")"))
+			}
+		}
+		p1.Close()
+		p2.Close()
 	}
+
+	go streamCopy(p1, p2)
+	streamCopy(p2, p1)
 }
 
 func checkError(err error) {
 	if err != nil {
-		log.Println(err)
+		log.Printf("%+v\n", err)
 		os.Exit(-1)
 	}
 }
 
 func main() {
 	rand.Seed(int64(time.Now().Nanosecond()))
+	if VERSION == "SELFBUILD" {
+		// add more log flags for debugging
+		log.SetFlags(log.LstdFlags | log.Lshortfile)
+	}
+
 	myApp := cli.NewApp()
 	myApp.Name = "kcptun"
-	myApp.Usage = "kcptun client"
+	myApp.Usage = "client(with SMUX)"
 	myApp.Version = VERSION
 	myApp.Flags = []cli.Flag{
 		cli.StringFlag{
@@ -105,28 +98,38 @@ func main() {
 		cli.StringFlag{
 			Name:   "key",
 			Value:  "it's a secrect",
-			Usage:  "key for communcation, must be the same as kcptun server",
+			Usage:  "pre-shared secret between client and server",
 			EnvVar: "KCPTUN_KEY",
 		},
 		cli.StringFlag{
 			Name:  "crypt",
 			Value: "aes",
-			Usage: "methods for encryption: aes, tea, xor, none",
+			Usage: "aes, aes-128, aes-192, salsa20, blowfish, twofish, cast5, 3des, tea, xtea, xor, sm4, none",
 		},
 		cli.StringFlag{
 			Name:  "mode",
 			Value: "fast",
-			Usage: "mode for communication: fast3, fast2, fast, normal",
+			Usage: "profiles: fast3, fast2, fast, normal, manual",
 		},
 		cli.IntFlag{
 			Name:  "conn",
 			Value: 1,
-			Usage: "establish N physical connections as specified by 'conn' to server",
+			Usage: "set num of UDP connections to server",
+		},
+		cli.IntFlag{
+			Name:  "autoexpire",
+			Value: 0,
+			Usage: "set auto expiration time(in seconds) for a single UDP connection, 0 to disable",
+		},
+		cli.IntFlag{
+			Name:  "scavengettl",
+			Value: 600,
+			Usage: "set how long an expired connection can live(in sec), -1 to disable",
 		},
 		cli.IntFlag{
 			Name:  "mtu",
 			Value: 1350,
-			Usage: "set MTU of UDP packets, suggest 'tracepath' to discover path mtu",
+			Usage: "set maximum transmission unit for UDP packets",
 		},
 		cli.IntFlag{
 			Name:  "sndwnd",
@@ -135,32 +138,33 @@ func main() {
 		},
 		cli.IntFlag{
 			Name:  "rcvwnd",
-			Value: 1024,
+			Value: 512,
 			Usage: "set receive window size(num of packets)",
 		},
-		cli.BoolFlag{
-			Name:  "nocomp",
-			Usage: "disable compression",
-		},
 		cli.IntFlag{
-			Name:  "datashard",
+			Name:  "datashard,ds",
 			Value: 10,
 			Usage: "set reed-solomon erasure coding - datashard",
 		},
 		cli.IntFlag{
-			Name:  "parityshard",
+			Name:  "parityshard,ps",
 			Value: 3,
 			Usage: "set reed-solomon erasure coding - parityshard",
 		},
-		cli.BoolFlag{
-			Name:  "acknodelay",
-			Usage: "flush ack immediately when a packet is received",
-		},
 		cli.IntFlag{
 			Name:  "dscp",
 			Value: 0,
 			Usage: "set DSCP(6bit)",
 		},
+		cli.BoolFlag{
+			Name:  "nocomp",
+			Usage: "disable compression",
+		},
+		cli.BoolFlag{
+			Name:   "acknodelay",
+			Usage:  "flush ack immediately when a packet is received",
+			Hidden: true,
+		},
 		cli.IntFlag{
 			Name:   "nodelay",
 			Value:  0,
@@ -168,7 +172,7 @@ func main() {
 		},
 		cli.IntFlag{
 			Name:   "interval",
-			Value:  40,
+			Value:  50,
 			Hidden: true,
 		},
 		cli.IntFlag{
@@ -181,102 +185,307 @@ func main() {
 			Value:  0,
 			Hidden: true,
 		},
+		cli.IntFlag{
+			Name:  "sockbuf",
+			Value: 4194304, // socket buffer size in bytes
+			Usage: "per-socket buffer in bytes",
+		},
+		cli.IntFlag{
+			Name:  "smuxver",
+			Value: 1,
+			Usage: "specify smux version, available 1,2",
+		},
+		cli.IntFlag{
+			Name:  "smuxbuf",
+			Value: 4194304,
+			Usage: "the overall de-mux buffer in bytes",
+		},
+		cli.IntFlag{
+			Name:  "streambuf",
+			Value: 2097152,
+			Usage: "per stream receive buffer in bytes, smux v2+",
+		},
+		cli.IntFlag{
+			Name:  "keepalive",
+			Value: 10, // nat keepalive interval in seconds
+			Usage: "seconds between heartbeats",
+		},
+		cli.StringFlag{
+			Name:  "snmplog",
+			Value: "",
+			Usage: "collect snmp to file, aware of timeformat in golang, like: ./snmp-20060102.log",
+		},
+		cli.IntFlag{
+			Name:  "snmpperiod",
+			Value: 60,
+			Usage: "snmp collect period, in seconds",
+		},
+		cli.StringFlag{
+			Name:  "log",
+			Value: "",
+			Usage: "specify a log file to output, default goes to stderr",
+		},
+		cli.BoolFlag{
+			Name:  "quiet",
+			Usage: "to suppress the 'stream open/close' messages",
+		},
+		cli.BoolFlag{
+			Name:  "tcp",
+			Usage: "to emulate a TCP connection(linux)",
+		},
+		cli.StringFlag{
+			Name:  "c",
+			Value: "", // when the value is not empty, the config path must exists
+			Usage: "config from json file, which will override the command from shell",
+		},
 	}
-	myApp.Action = func(c *cli.Context) {
+	myApp.Action = func(c *cli.Context) error {
+		config := Config{}
+		config.LocalAddr = c.String("localaddr")
+		config.RemoteAddr = c.String("remoteaddr")
+		config.Key = c.String("key")
+		config.Crypt = c.String("crypt")
+		config.Mode = c.String("mode")
+		config.Conn = c.Int("conn")
+		config.AutoExpire = c.Int("autoexpire")
+		config.ScavengeTTL = c.Int("scavengettl")
+		config.MTU = c.Int("mtu")
+		config.SndWnd = c.Int("sndwnd")
+		config.RcvWnd = c.Int("rcvwnd")
+		config.DataShard = c.Int("datashard")
+		config.ParityShard = c.Int("parityshard")
+		config.DSCP = c.Int("dscp")
+		config.NoComp = c.Bool("nocomp")
+		config.AckNodelay = c.Bool("acknodelay")
+		config.NoDelay = c.Int("nodelay")
+		config.Interval = c.Int("interval")
+		config.Resend = c.Int("resend")
+		config.NoCongestion = c.Int("nc")
+		config.SockBuf = c.Int("sockbuf")
+		config.SmuxBuf = c.Int("smuxbuf")
+		config.StreamBuf = c.Int("streambuf")
+		config.SmuxVer = c.Int("smuxver")
+		config.KeepAlive = c.Int("keepalive")
+		config.Log = c.String("log")
+		config.SnmpLog = c.String("snmplog")
+		config.SnmpPeriod = c.Int("snmpperiod")
+		config.Quiet = c.Bool("quiet")
+		config.TCP = c.Bool("tcp")
+
+		if c.String("c") != "" {
+			err := parseJSONConfig(&config, c.String("c"))
+			checkError(err)
+		}
+
+		// log redirect
+		if config.Log != "" {
+			f, err := os.OpenFile(config.Log, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
+			checkError(err)
+			defer f.Close()
+			log.SetOutput(f)
+		}
+
+		switch config.Mode {
+		case "normal":
+			config.NoDelay, config.Interval, config.Resend, config.NoCongestion = 0, 40, 2, 1
+		case "fast":
+			config.NoDelay, config.Interval, config.Resend, config.NoCongestion = 0, 30, 2, 1
+		case "fast2":
+			config.NoDelay, config.Interval, config.Resend, config.NoCongestion = 1, 20, 2, 1
+		case "fast3":
+			config.NoDelay, config.Interval, config.Resend, config.NoCongestion = 1, 10, 2, 1
+		}
+
 		log.Println("version:", VERSION)
-		addr, err := net.ResolveTCPAddr("tcp", c.String("localaddr"))
+		addr, err := net.ResolveTCPAddr("tcp", config.LocalAddr)
 		checkError(err)
 		listener, err := net.ListenTCP("tcp", addr)
 		checkError(err)
-		pass := pbkdf2.Key([]byte(c.String("key")), []byte(SALT), 4096, 32, sha1.New)
 
-		// kcp server
-		nodelay, interval, resend, nc := c.Int("nodelay"), c.Int("interval"), c.Int("resend"), c.Int("nc")
+		log.Println("smux version:", config.SmuxVer)
+		log.Println("listening on:", listener.Addr())
+		log.Println("encryption:", config.Crypt)
+		log.Println("nodelay parameters:", config.NoDelay, config.Interval, config.Resend, config.NoCongestion)
+		log.Println("remote address:", config.RemoteAddr)
+		log.Println("sndwnd:", config.SndWnd, "rcvwnd:", config.RcvWnd)
+		log.Println("compression:", !config.NoComp)
+		log.Println("mtu:", config.MTU)
+		log.Println("datashard:", config.DataShard, "parityshard:", config.ParityShard)
+		log.Println("acknodelay:", config.AckNodelay)
+		log.Println("dscp:", config.DSCP)
+		log.Println("sockbuf:", config.SockBuf)
+		log.Println("smuxbuf:", config.SmuxBuf)
+		log.Println("streambuf:", config.StreamBuf)
+		log.Println("keepalive:", config.KeepAlive)
+		log.Println("conn:", config.Conn)
+		log.Println("autoexpire:", config.AutoExpire)
+		log.Println("scavengettl:", config.ScavengeTTL)
+		log.Println("snmplog:", config.SnmpLog)
+		log.Println("snmpperiod:", config.SnmpPeriod)
+		log.Println("quiet:", config.Quiet)
+		log.Println("tcp:", config.TCP)
 
-		switch c.String("mode") {
-		case "normal":
-			nodelay, interval, resend, nc = 0, 30, 2, 1
-		case "fast":
-			nodelay, interval, resend, nc = 0, 20, 2, 1
-		case "fast2":
-			nodelay, interval, resend, nc = 1, 20, 2, 1
-		case "fast3":
-			nodelay, interval, resend, nc = 1, 10, 2, 1
+		// parameters check
+		if config.SmuxVer > maxSmuxVer {
+			log.Fatal("unsupported smux version:", config.SmuxVer)
 		}
 
-		log.Println("listening on:", listener.Addr())
-		log.Println("encryption:", c.String("crypt"))
-		log.Println("nodelay parameters:", nodelay, interval, resend, nc)
-		log.Println("remote address:", c.String("remoteaddr"))
-		log.Println("sndwnd:", c.Int("sndwnd"), "rcvwnd:", c.Int("rcvwnd"))
-		log.Println("compression:", !c.Bool("nocomp"))
-		log.Println("mtu:", c.Int("mtu"))
-		log.Println("datashard:", c.Int("datashard"), "parityshard:", c.Int("parityshard"))
-		log.Println("acknodelay:", c.Bool("acknodelay"))
-		log.Println("dscp:", c.Int("dscp"))
-		log.Println("conn:", c.Int("conn"))
+		log.Println("initiating key derivation")
+		pass := pbkdf2.Key([]byte(config.Key), []byte(SALT), 4096, 32, sha1.New)
+		log.Println("key derivation done")
+		var block kcp.BlockCrypt
+		switch config.Crypt {
+		case "sm4":
+			block, _ = kcp.NewSM4BlockCrypt(pass[:16])
+		case "tea":
+			block, _ = kcp.NewTEABlockCrypt(pass[:16])
+		case "xor":
+			block, _ = kcp.NewSimpleXORBlockCrypt(pass)
+		case "none":
+			block, _ = kcp.NewNoneBlockCrypt(pass)
+		case "aes-128":
+			block, _ = kcp.NewAESBlockCrypt(pass[:16])
+		case "aes-192":
+			block, _ = kcp.NewAESBlockCrypt(pass[:24])
+		case "blowfish":
+			block, _ = kcp.NewBlowfishBlockCrypt(pass)
+		case "twofish":
+			block, _ = kcp.NewTwofishBlockCrypt(pass)
+		case "cast5":
+			block, _ = kcp.NewCast5BlockCrypt(pass[:16])
+		case "3des":
+			block, _ = kcp.NewTripleDESBlockCrypt(pass[:24])
+		case "xtea":
+			block, _ = kcp.NewXTEABlockCrypt(pass[:16])
+		case "salsa20":
+			block, _ = kcp.NewSalsa20BlockCrypt(pass)
+		default:
+			config.Crypt = "aes"
+			block, _ = kcp.NewAESBlockCrypt(pass)
+		}
 
-		createConn := func() *yamux.Session {
-			var block kcp.BlockCrypt
-			switch c.String("crypt") {
-			case "tea":
-				block, _ = kcp.NewTEABlockCrypt(pass[:16])
-			case "xor":
-				block, _ = kcp.NewSimpleXORBlockCrypt(pass)
-			case "none":
-				block, _ = kcp.NewNoneBlockCrypt(pass)
-			default:
-				block, _ = kcp.NewAESBlockCrypt(pass)
+		createConn := func() (*smux.Session, error) {
+			kcpconn, err := dial(&config, block)
+			if err != nil {
+				return nil, errors.Wrap(err, "dial()")
+			}
+			kcpconn.SetStreamMode(true)
+			kcpconn.SetWriteDelay(false)
+			kcpconn.SetNoDelay(config.NoDelay, config.Interval, config.Resend, config.NoCongestion)
+			kcpconn.SetWindowSize(config.SndWnd, config.RcvWnd)
+			kcpconn.SetMtu(config.MTU)
+			kcpconn.SetACKNoDelay(config.AckNodelay)
+
+			if err := kcpconn.SetDSCP(config.DSCP); err != nil {
+				log.Println("SetDSCP:", err)
+			}
+			if err := kcpconn.SetReadBuffer(config.SockBuf); err != nil {
+				log.Println("SetReadBuffer:", err)
+			}
+			if err := kcpconn.SetWriteBuffer(config.SockBuf); err != nil {
+				log.Println("SetWriteBuffer:", err)
+			}
+			log.Println("smux version:", config.SmuxVer, "on connection:", kcpconn.LocalAddr(), "->", kcpconn.RemoteAddr())
+			smuxConfig := smux.DefaultConfig()
+			smuxConfig.Version = config.SmuxVer
+			smuxConfig.MaxReceiveBuffer = config.SmuxBuf
+			smuxConfig.MaxStreamBuffer = config.StreamBuf
+			smuxConfig.KeepAliveInterval = time.Duration(config.KeepAlive) * time.Second
+
+			if err := smux.VerifyConfig(smuxConfig); err != nil {
+				log.Fatalf("%+v", err)
 			}
-			kcpconn, err := kcp.DialWithOptions(c.String("remoteaddr"), block, c.Int("datashard"), c.Int("parityshard"))
-			checkError(err)
-			kcpconn.SetNoDelay(nodelay, interval, resend, nc)
-			kcpconn.SetWindowSize(c.Int("sndwnd"), c.Int("rcvwnd"))
-			kcpconn.SetMtu(c.Int("mtu"))
-			kcpconn.SetACKNoDelay(c.Bool("acknodelay"))
-			kcpconn.SetDSCP(c.Int("dscp"))
 
 			// stream multiplex
-			config := &yamux.Config{
-				AcceptBacklog:          256,
-				EnableKeepAlive:        true,
-				KeepAliveInterval:      30 * time.Second,
-				ConnectionWriteTimeout: 30 * time.Second,
-				MaxStreamWindowSize:    16777216,
-				LogOutput:              os.Stderr,
-			}
-			var session *yamux.Session
-			if c.Bool("nocomp") {
-				session, err = yamux.Client(kcpconn, config)
+			var session *smux.Session
+			if config.NoComp {
+				session, err = smux.Client(kcpconn, smuxConfig)
 			} else {
-				session, err = yamux.Client(newCompStream(kcpconn), config)
+				session, err = smux.Client(generic.NewCompStream(kcpconn), smuxConfig)
 			}
-			checkError(err)
-			return session
+			if err != nil {
+				return nil, errors.Wrap(err, "createConn()")
+			}
+			return session, nil
 		}
 
-		numconn := uint16(c.Int("conn"))
-		var muxes []*yamux.Session
-		for i := uint16(0); i < numconn; i++ {
-			muxes = append(muxes, createConn())
+		// wait until a connection is ready
+		waitConn := func() *smux.Session {
+			for {
+				if session, err := createConn(); err == nil {
+					return session
+				} else {
+					log.Println("re-connecting:", err)
+					time.Sleep(time.Second)
+				}
+			}
 		}
 
+		numconn := uint16(config.Conn)
+		muxes := make([]struct {
+			session *smux.Session
+			ttl     time.Time
+		}, numconn)
+
+		for k := range muxes {
+			muxes[k].session = waitConn()
+			muxes[k].ttl = time.Now().Add(time.Duration(config.AutoExpire) * time.Second)
+		}
+
+		chScavenger := make(chan *smux.Session, 128)
+		go scavenger(chScavenger, config.ScavengeTTL)
+		go generic.SnmpLogger(config.SnmpLog, config.SnmpPeriod)
 		rr := uint16(0)
 		for {
 			p1, err := listener.AcceptTCP()
-			checkError(err)
-			mux := muxes[rr%numconn]
-			p2, err := mux.Open()
-			if err != nil { // yamux failure
-				log.Println(err)
-				p1.Close()
-				mux.Close()
-				muxes[rr%numconn] = createConn()
-				continue
+			if err != nil {
+				log.Fatalf("%+v", err)
 			}
-			go handleClient(p1, p2)
+			idx := rr % numconn
+
+			// do auto expiration && reconnection
+			if muxes[idx].session.IsClosed() || (config.AutoExpire > 0 && time.Now().After(muxes[idx].ttl)) {
+				chScavenger <- muxes[idx].session
+				muxes[idx].session = waitConn()
+				muxes[idx].ttl = time.Now().Add(time.Duration(config.AutoExpire) * time.Second)
+			}
+
+			go handleClient(muxes[idx].session, p1, config.Quiet)
 			rr++
 		}
 	}
 	myApp.Run(os.Args)
 }
+
+type scavengeSession struct {
+	session *smux.Session
+	ts      time.Time
+}
+
+func scavenger(ch chan *smux.Session, ttl int) {
+	ticker := time.NewTicker(time.Second)
+	defer ticker.Stop()
+	var sessionList []scavengeSession
+	for {
+		select {
+		case sess := <-ch:
+			sessionList = append(sessionList, scavengeSession{sess, time.Now()})
+			log.Println("session marked as expired", sess.RemoteAddr())
+		case <-ticker.C:
+			var newList []scavengeSession
+			for k := range sessionList {
+				s := sessionList[k]
+				if s.session.NumStreams() == 0 || s.session.IsClosed() {
+					log.Println("session normally closed", s.session.RemoteAddr())
+					s.session.Close()
+				} else if ttl >= 0 && time.Since(s.ts) >= time.Duration(ttl)*time.Second {
+					log.Println("session reached scavenge ttl", s.session.RemoteAddr())
+					s.session.Close()
+				} else {
+					newList = append(newList, sessionList[k])
+				}
+			}
+			sessionList = newList
+		}
+	}
+}

client/signal.go

@@ -8,7 +8,7 @@ import (
 	"os/signal"
 	"syscall"
 
-	"github.com/xtaci/kcp-go"
+	kcp "github.com/xtaci/kcp-go/v5"
 )
 
 func init() {
@@ -18,6 +18,7 @@ func init() {
 func sigHandler() {
 	ch := make(chan os.Signal, 1)
 	signal.Notify(ch, syscall.SIGUSR1)
+	signal.Ignore(syscall.SIGPIPE)
 
 	for {
 		switch <-ch {

examples/kcptun.service

@@ -0,0 +1,16 @@
+Description=kcptun
+
+Wants=network.target
+After=syslog.target network-online.target
+
+[Service]
+Type=simple
+Environment=GOGC=20
+ExecStart=/home/user/client_linux_amd64 -c /home/user/local.json
+Restart=on-failure
+RestartSec=10
+KillMode=process
+LimitNOFILE=65536
+
+[Install]
+WantedBy=multi-user.target

examples/local.json

@@ -0,0 +1,27 @@
+{
+	"localaddr": ":2000",
+	"remoteaddr": "11.22.33.44:2000",
+	"key": "PASSWORD",
+	"crypt": "aes-128",
+	"mode": "fast3",
+	"mtu": 1400,
+	"sndwnd": 128,
+	"rcvwnd": 1024,
+	"datashard": 10,
+	"parityshard": 3,
+	"dscp": 46,
+	"nocomp": true,
+	"acknodelay": false,
+	"nodelay": 1,
+	"interval": 40,
+	"resend": 2,
+	"nc": 1,
+	"sockbuf": 16777217,
+	"smuxver": 1,
+	"smuxbuf": 16777217,
+	"streambuf": 2097152,
+	"keepalive": 10,
+	"autoexpire": 1800,
+	"quiet": false,
+	"tcp": false
+}

examples/server.json

@@ -0,0 +1,27 @@
+{
+        "listen": ":2000",
+        "target": "127.0.0.1:9999",
+        "key": "PASSWORD",
+        "crypt": "aes-128",
+        "mode": "fast3",
+        "mtu": 1400,
+        "sndwnd": 2048,
+        "rcvwnd": 2048,
+        "datashard": 10,
+        "parityshard": 3,
+        "dscp": 46,
+        "nocomp": true,
+        "acknodelay": false,
+        "nodelay": 1,
+        "interval": 40,
+        "resend": 2,
+        "nc": 1,
+        "sockbuf": 16777217,
+        "smuxver": 1,
+        "smuxbuf": 16777217,
+        "streambuf": 2097152,
+        "keepalive": 10,
+        "pprof":false,
+        "quiet":false,
+        "tcp":false
+}

generic/comp.go

@@ -0,0 +1,62 @@
+package generic
+
+import (
+	"net"
+	"time"
+
+	"github.com/golang/snappy"
+	"github.com/pkg/errors"
+)
+
+type CompStream struct {
+	conn net.Conn
+	w    *snappy.Writer
+	r    *snappy.Reader
+}
+
+func (c *CompStream) Read(p []byte) (n int, err error) {
+	return c.r.Read(p)
+}
+
+func (c *CompStream) Write(p []byte) (n int, err error) {
+	if _, err := c.w.Write(p); err != nil {
+		return 0, errors.WithStack(err)
+	}
+
+	if err := c.w.Flush(); err != nil {
+		return 0, errors.WithStack(err)
+	}
+	return len(p), err
+}
+
+func (c *CompStream) Close() error {
+	return c.conn.Close()
+}
+
+func (c *CompStream) LocalAddr() net.Addr {
+	return c.conn.LocalAddr()
+}
+
+func (c *CompStream) RemoteAddr() net.Addr {
+	return c.conn.RemoteAddr()
+}
+
+func (c *CompStream) SetDeadline(t time.Time) error {
+	return c.conn.SetDeadline(t)
+}
+
+func (c *CompStream) SetReadDeadline(t time.Time) error {
+	return c.conn.SetReadDeadline(t)
+}
+
+func (c *CompStream) SetWriteDeadline(t time.Time) error {
+	return c.conn.SetWriteDeadline(t)
+}
+
+func NewCompStream(conn net.Conn) *CompStream {
+	c := new(CompStream)
+	c.conn = conn
+	c.w = snappy.NewBufferedWriter(conn)
+	c.r = snappy.NewReader(conn)
+	return c
+}

generic/copy.go

@@ -0,0 +1,24 @@
+package generic
+
+import (
+	"io"
+)
+
+const bufSize = 4096
+
+// Memory optimized io.Copy function specified for this library
+func Copy(dst io.Writer, src io.Reader) (written int64, err error) {
+	// If the reader has a WriteTo method, use it to do the copy.
+	// Avoids an allocation and a copy.
+	if wt, ok := src.(io.WriterTo); ok {
+		return wt.WriteTo(dst)
+	}
+	// Similarly, if the writer has a ReadFrom method, use it to do the copy.
+	if rt, ok := dst.(io.ReaderFrom); ok {
+		return rt.ReadFrom(src)
+	}
+
+	// fallback to standard io.CopyBuffer
+	buf := make([]byte, bufSize)
+	return io.CopyBuffer(dst, src, buf)
+}

generic/snmp.go

@@ -0,0 +1,46 @@
+package generic
+
+import (
+	"encoding/csv"
+	"fmt"
+	"log"
+	"os"
+	"path/filepath"
+	"time"
+
+	kcp "github.com/xtaci/kcp-go/v5"
+)
+
+func SnmpLogger(path string, interval int) {
+	if path == "" || interval == 0 {
+		return
+	}
+	ticker := time.NewTicker(time.Duration(interval) * time.Second)
+	defer ticker.Stop()
+	for {
+		select {
+		case <-ticker.C:
+			// split path into dirname and filename
+			logdir, logfile := filepath.Split(path)
+			// only format logfile
+			f, err := os.OpenFile(logdir+time.Now().Format(logfile), os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
+			if err != nil {
+				log.Println(err)
+				return
+			}
+			w := csv.NewWriter(f)
+			// write header in empty file
+			if stat, err := f.Stat(); err == nil && stat.Size() == 0 {
+				if err := w.Write(append([]string{"Unix"}, kcp.DefaultSnmp.Header()...)); err != nil {
+					log.Println(err)
+				}
+			}
+			if err := w.Write(append([]string{fmt.Sprint(time.Now().Unix())}, kcp.DefaultSnmp.ToSlice()...)); err != nil {
+				log.Println(err)
+			}
+			// kcp.DefaultSnmp.Reset()
+			w.Flush()
+			f.Close()
+		}
+	}
+}

go.mod

@@ -0,0 +1,19 @@
+module github.com/xtaci/kcptun
+
+require (
+	github.com/coreos/go-iptables v0.4.2 // indirect
+	github.com/golang/snappy v0.0.1
+	github.com/google/gopacket v1.1.17 // indirect
+	github.com/klauspost/cpuid v1.2.3 // indirect
+	github.com/pkg/errors v0.9.1
+	github.com/tjfoc/gmsm v1.3.0 // indirect
+	github.com/urfave/cli v1.21.0
+	github.com/xtaci/kcp-go/v5 v5.5.9
+	github.com/xtaci/smux v1.5.12
+	github.com/xtaci/tcpraw v1.2.25
+	golang.org/x/crypto v0.0.0-20200302210943-78000ba7a073
+	golang.org/x/net v0.0.0-20200301022130-244492dfa37a // indirect
+	golang.org/x/sys v0.0.0-20200302150141-5c8b2ff67527 // indirect
+)
+
+go 1.13

go.sum

@@ -0,0 +1,62 @@
+github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
+github.com/coreos/go-iptables v0.4.2 h1:KH0EwId05JwWIfb96gWvkiT2cbuOu8ygqUaB+yPAwIg=
+github.com/coreos/go-iptables v0.4.2/go.mod h1:/mVI274lEDI2ns62jHCDnCyBF9Iwsmekav8Dbxlm1MU=
+github.com/golang/snappy v0.0.1 h1:Qgr9rKW7uDUkrbSmQeiDsGa8SjGyCOGtuasMWwvp2P4=
+github.com/golang/snappy v0.0.1/go.mod h1:/XxbfmMg8lxefKM7IXC3fBNl/7bRcc72aCRzEWrmP2Q=
+github.com/google/gopacket v1.1.17 h1:rMrlX2ZY2UbvT+sdz3+6J+pp2z+msCq9MxTU6ymxbBY=
+github.com/google/gopacket v1.1.17/go.mod h1:UdDNZ1OO62aGYVnPhxT1U6aI7ukYtA/kB8vaU0diBUM=
+github.com/klauspost/cpuid v1.2.2 h1:1xAgYebNnsb9LKCdLOvFWtAxGU/33mjJtyOVbmUa0Us=
+github.com/klauspost/cpuid v1.2.2/go.mod h1:Pj4uuM528wm8OyEC2QMXAi2YiTZ96dNQPGgoMS4s3ek=
+github.com/klauspost/cpuid v1.2.3 h1:CCtW0xUnWGVINKvE/WWOYKdsPV6mawAtvQuSl8guwQs=
+github.com/klauspost/cpuid v1.2.3/go.mod h1:Pj4uuM528wm8OyEC2QMXAi2YiTZ96dNQPGgoMS4s3ek=
+github.com/klauspost/reedsolomon v1.9.3 h1:N/VzgeMfHmLc+KHMD1UL/tNkfXAt8FnUqlgXGIduwAY=
+github.com/klauspost/reedsolomon v1.9.3/go.mod h1:CwCi+NUr9pqSVktrkN+Ondf06rkhYZ/pcNv7fu+8Un4=
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+github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
+github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
+github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
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+github.com/templexxx/xorsimd v0.4.1 h1:iUZcywbOYDRAZUasAs2eSCUW8eobuZDy0I9FJiORkVg=
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+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
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+golang.org/x/crypto v0.0.0-20191206172530-e9b2fee46413/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
+golang.org/x/crypto v0.0.0-20191219195013-becbf705a915/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
+golang.org/x/crypto v0.0.0-20200302210943-78000ba7a073 h1:xMPOj6Pz6UipU1wXLkrtqpHbR0AVFnyPEQq/wRWz9lM=
+golang.org/x/crypto v0.0.0-20200302210943-78000ba7a073/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
+golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
+golang.org/x/net v0.0.0-20191209160850-c0dbc17a3553 h1:efeOvDhwQ29Dj3SdAV/MJf8oukgn+8D8WgaCaRMchF8=
+golang.org/x/net v0.0.0-20191209160850-c0dbc17a3553/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/net v0.0.0-20200301022130-244492dfa37a h1:GuSPYbZzB5/dcLNCwLQLsg3obCJtX9IJhpXkvY7kzk0=
+golang.org/x/net v0.0.0-20200301022130-244492dfa37a/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190405154228-4b34438f7a67/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20191228213918-04cbcbbfeed8 h1:JA8d3MPx/IToSyXZG/RhwYEtfrKO1Fxrqe8KrkiLXKM=
+golang.org/x/sys v0.0.0-20191228213918-04cbcbbfeed8/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20200302150141-5c8b2ff67527 h1:uYVVQ9WP/Ds2ROhcaGPeIdVq0RIXVLwsHlnvJ+cT1So=
+golang.org/x/sys v0.0.0-20200302150141-5c8b2ff67527/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=

server/config.go

@@ -0,0 +1,48 @@
+package main
+
+import (
+	"encoding/json"
+	"os"
+)
+
+// Config for server
+type Config struct {
+	Listen       string `json:"listen"`
+	Target       string `json:"target"`
+	Key          string `json:"key"`
+	Crypt        string `json:"crypt"`
+	Mode         string `json:"mode"`
+	MTU          int    `json:"mtu"`
+	SndWnd       int    `json:"sndwnd"`
+	RcvWnd       int    `json:"rcvwnd"`
+	DataShard    int    `json:"datashard"`
+	ParityShard  int    `json:"parityshard"`
+	DSCP         int    `json:"dscp"`
+	NoComp       bool   `json:"nocomp"`
+	AckNodelay   bool   `json:"acknodelay"`
+	NoDelay      int    `json:"nodelay"`
+	Interval     int    `json:"interval"`
+	Resend       int    `json:"resend"`
+	NoCongestion int    `json:"nc"`
+	SockBuf      int    `json:"sockbuf"`
+	SmuxBuf      int    `json:"smuxbuf"`
+	StreamBuf    int    `json:"streambuf"`
+	SmuxVer      int    `json:"smuxver"`
+	KeepAlive    int    `json:"keepalive"`
+	Log          string `json:"log"`
+	SnmpLog      string `json:"snmplog"`
+	SnmpPeriod   int    `json:"snmpperiod"`
+	Pprof        bool   `json:"pprof"`
+	Quiet        bool   `json:"quiet"`
+	TCP          bool   `json:"tcp"`
+}
+
+func parseJSONConfig(config *Config, path string) error {
+	file, err := os.Open(path) // For read access.
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+
+	return json.NewDecoder(file).Decode(config)
+}

server/main.go

@@ -2,122 +2,132 @@ package main
 
 import (
 	"crypto/sha1"
+	"fmt"
 	"io"
 	"log"
 	"math/rand"
 	"net"
+	"net/http"
+	_ "net/http/pprof"
 	"os"
+	"sync"
 	"time"
 
 	"golang.org/x/crypto/pbkdf2"
 
-	"github.com/golang/snappy"
-	"github.com/hashicorp/yamux"
 	"github.com/urfave/cli"
-	"github.com/xtaci/kcp-go"
+	kcp "github.com/xtaci/kcp-go/v5"
+	"github.com/xtaci/kcptun/generic"
+	"github.com/xtaci/smux"
+	"github.com/xtaci/tcpraw"
 )
 
-var (
-	// VERSION is injected by buildflags
-	VERSION = "SELFBUILD"
+const (
 	// SALT is use for pbkdf2 key expansion
 	SALT = "kcp-go"
+	// maximum supported smux version
+	maxSmuxVer = 2
+	// stream copy buffer size
+	bufSize = 4096
 )
 
-type compStream struct {
-	conn net.Conn
-	w    *snappy.Writer
-	r    *snappy.Reader
-}
-
-func (c *compStream) Read(p []byte) (n int, err error) {
-	return c.r.Read(p)
-}
-
-func (c *compStream) Write(p []byte) (n int, err error) {
-	n, err = c.w.Write(p)
-	err = c.w.Flush()
-	return n, err
-}
-
-func (c *compStream) Close() error {
-	return c.conn.Close()
-}
-
-func newCompStream(conn net.Conn) *compStream {
-	c := new(compStream)
-	c.conn = conn
-	c.w = snappy.NewBufferedWriter(conn)
-	c.r = snappy.NewReader(conn)
-	return c
-}
+// VERSION is injected by buildflags
+var VERSION = "SELFBUILD"
 
 // handle multiplex-ed connection
-func handleMux(conn io.ReadWriteCloser, target string) {
-	// stream multiplex
-	var mux *yamux.Session
-	config := &yamux.Config{
-		AcceptBacklog:          256,
-		EnableKeepAlive:        true,
-		KeepAliveInterval:      30 * time.Second,
-		ConnectionWriteTimeout: 30 * time.Second,
-		MaxStreamWindowSize:    16777216,
-		LogOutput:              os.Stderr,
+func handleMux(conn net.Conn, config *Config) {
+	// check if target is unix domain socket
+	var isUnix bool
+	if _, _, err := net.SplitHostPort(config.Target); err != nil {
+		isUnix = true
 	}
-	m, err := yamux.Server(conn, config)
+	log.Println("smux version:", config.SmuxVer, "on connection:", conn.LocalAddr(), "->", conn.RemoteAddr())
+
+	// stream multiplex
+	smuxConfig := smux.DefaultConfig()
+	smuxConfig.Version = config.SmuxVer
+	smuxConfig.MaxReceiveBuffer = config.SmuxBuf
+	smuxConfig.MaxStreamBuffer = config.StreamBuf
+	smuxConfig.KeepAliveInterval = time.Duration(config.KeepAlive) * time.Second
+
+	mux, err := smux.Server(conn, smuxConfig)
 	if err != nil {
 		log.Println(err)
 		return
 	}
-	mux = m
 	defer mux.Close()
 
 	for {
-		p1, err := mux.Accept()
+		stream, err := mux.AcceptStream()
 		if err != nil {
 			log.Println(err)
 			return
 		}
-		p2, err := net.DialTimeout("tcp", target, 5*time.Second)
-		if err != nil {
-			log.Println(err)
-			return
-		}
-		go handleClient(p1, p2)
+
+		go func(p1 *smux.Stream) {
+			var p2 net.Conn
+			var err error
+			if !isUnix {
+				p2, err = net.Dial("tcp", config.Target)
+			} else {
+				p2, err = net.Dial("unix", config.Target)
+			}
+
+			if err != nil {
+				log.Println(err)
+				p1.Close()
+				return
+			}
+			handleClient(p1, p2, config.Quiet)
+		}(stream)
 	}
 }
 
-func handleClient(p1, p2 io.ReadWriteCloser) {
-	log.Println("stream opened")
-	defer log.Println("stream closed")
+func handleClient(p1 *smux.Stream, p2 net.Conn, quiet bool) {
+	logln := func(v ...interface{}) {
+		if !quiet {
+			log.Println(v...)
+		}
+	}
+
 	defer p1.Close()
 	defer p2.Close()
 
-	// start tunnel
-	p1die := make(chan struct{})
-	go func() {
-		io.Copy(p1, p2)
-		close(p1die)
-	}()
+	logln("stream opened", "in:", fmt.Sprint(p1.RemoteAddr(), "(", p1.ID(), ")"), "out:", p2.RemoteAddr())
+	defer logln("stream closed", "in:", fmt.Sprint(p1.RemoteAddr(), "(", p1.ID(), ")"), "out:", p2.RemoteAddr())
 
-	p2die := make(chan struct{})
-	go func() {
-		io.Copy(p2, p1)
-		close(p2die)
-	}()
+	// start tunnel & wait for tunnel termination
+	streamCopy := func(dst io.Writer, src io.ReadCloser) {
+		if _, err := generic.Copy(dst, src); err != nil {
+			if err == smux.ErrInvalidProtocol {
+				log.Println("smux", err, "in:", fmt.Sprint(p1.RemoteAddr(), "(", p1.ID(), ")"), "out:", p2.RemoteAddr())
+			}
+		}
+		p1.Close()
+		p2.Close()
+	}
 
-	// wait for tunnel termination
-	select {
-	case <-p1die:
-	case <-p2die:
+	go streamCopy(p2, p1)
+	streamCopy(p1, p2)
+}
+
+func checkError(err error) {
+	if err != nil {
+		log.Printf("%+v\n", err)
+		os.Exit(-1)
 	}
 }
 
 func main() {
 	rand.Seed(int64(time.Now().Nanosecond()))
+	if VERSION == "SELFBUILD" {
+		// add more log flags for debugging
+		log.SetFlags(log.LstdFlags | log.Lshortfile)
+	}
+
 	myApp := cli.NewApp()
 	myApp.Name = "kcptun"
-	myApp.Usage = "kcptun server"
+	myApp.Usage = "server(with SMUX)"
 	myApp.Version = VERSION
 	myApp.Flags = []cli.Flag{
 		cli.StringFlag{
@@ -128,28 +138,28 @@ func main() {
 		cli.StringFlag{
 			Name:  "target, t",
 			Value: "127.0.0.1:12948",
-			Usage: "target server address",
+			Usage: "target server address, or path/to/unix_socket",
 		},
 		cli.StringFlag{
 			Name:   "key",
 			Value:  "it's a secrect",
-			Usage:  "key for communcation, must be the same as kcptun client",
+			Usage:  "pre-shared secret between client and server",
 			EnvVar: "KCPTUN_KEY",
 		},
 		cli.StringFlag{
 			Name:  "crypt",
 			Value: "aes",
-			Usage: "methods for encryption: aes, tea, xor, none",
+			Usage: "aes, aes-128, aes-192, salsa20, blowfish, twofish, cast5, 3des, tea, xtea, xor, sm4, none",
 		},
 		cli.StringFlag{
 			Name:  "mode",
 			Value: "fast",
-			Usage: "mode for communication: fast3, fast2, fast, normal",
+			Usage: "profiles: fast3, fast2, fast, normal, manual",
 		},
 		cli.IntFlag{
 			Name:  "mtu",
 			Value: 1350,
-			Usage: "set MTU of UDP packets, suggest 'tracepath' to discover path mtu",
+			Usage: "set maximum transmission unit for UDP packets",
 		},
 		cli.IntFlag{
 			Name:  "sndwnd",
@@ -161,29 +171,30 @@ func main() {
 			Value: 1024,
 			Usage: "set receive window size(num of packets)",
 		},
-		cli.BoolFlag{
-			Name:  "nocomp",
-			Usage: "disable compression",
-		},
 		cli.IntFlag{
-			Name:  "datashard",
+			Name:  "datashard,ds",
 			Value: 10,
 			Usage: "set reed-solomon erasure coding - datashard",
 		},
 		cli.IntFlag{
-			Name:  "parityshard",
+			Name:  "parityshard,ps",
 			Value: 3,
 			Usage: "set reed-solomon erasure coding - parityshard",
 		},
-		cli.BoolFlag{
-			Name:  "acknodelay",
-			Usage: "flush ack immediately when a packet is received",
-		},
 		cli.IntFlag{
 			Name:  "dscp",
 			Value: 0,
 			Usage: "set DSCP(6bit)",
 		},
+		cli.BoolFlag{
+			Name:  "nocomp",
+			Usage: "disable compression",
+		},
+		cli.BoolFlag{
+			Name:   "acknodelay",
+			Usage:  "flush ack immediately when a packet is received",
+			Hidden: true,
+		},
 		cli.IntFlag{
 			Name:   "nodelay",
 			Value:  0,
@@ -191,7 +202,7 @@ func main() {
 		},
 		cli.IntFlag{
 			Name:   "interval",
-			Value:  40,
+			Value:  50,
 			Hidden: true,
 		},
 		cli.IntFlag{
@@ -204,65 +215,239 @@ func main() {
 			Value:  0,
 			Hidden: true,
 		},
+		cli.IntFlag{
+			Name:  "sockbuf",
+			Value: 4194304, // socket buffer size in bytes
+			Usage: "per-socket buffer in bytes",
+		},
+		cli.IntFlag{
+			Name:  "smuxver",
+			Value: 1,
+			Usage: "specify smux version, available 1,2",
+		},
+		cli.IntFlag{
+			Name:  "smuxbuf",
+			Value: 4194304,
+			Usage: "the overall de-mux buffer in bytes",
+		},
+		cli.IntFlag{
+			Name:  "streambuf",
+			Value: 2097152,
+			Usage: "per stream receive buffer in bytes, smux v2+",
+		},
+		cli.IntFlag{
+			Name:  "keepalive",
+			Value: 10, // nat keepalive interval in seconds
+			Usage: "seconds between heartbeats",
+		},
+		cli.StringFlag{
+			Name:  "snmplog",
+			Value: "",
+			Usage: "collect snmp to file, aware of timeformat in golang, like: ./snmp-20060102.log",
+		},
+		cli.IntFlag{
+			Name:  "snmpperiod",
+			Value: 60,
+			Usage: "snmp collect period, in seconds",
+		},
+		cli.BoolFlag{
+			Name:  "pprof",
+			Usage: "start profiling server on :6060",
+		},
+		cli.StringFlag{
+			Name:  "log",
+			Value: "",
+			Usage: "specify a log file to output, default goes to stderr",
+		},
+		cli.BoolFlag{
+			Name:  "quiet",
+			Usage: "to suppress the 'stream open/close' messages",
+		},
+		cli.BoolFlag{
+			Name:  "tcp",
+			Usage: "to emulate a TCP connection(linux)",
+		},
+		cli.StringFlag{
+			Name:  "c",
+			Value: "", // when the value is not empty, the config path must exists
+			Usage: "config from json file, which will override the command from shell",
+		},
 	}
-	myApp.Action = func(c *cli.Context) {
-		log.Println("version:", VERSION)
-		nodelay, interval, resend, nc := c.Int("nodelay"), c.Int("interval"), c.Int("resend"), c.Int("nc")
-		switch c.String("mode") {
-		case "normal":
-			nodelay, interval, resend, nc = 0, 30, 2, 1
-		case "fast":
-			nodelay, interval, resend, nc = 0, 20, 2, 1
-		case "fast2":
-			nodelay, interval, resend, nc = 1, 20, 2, 1
-		case "fast3":
-			nodelay, interval, resend, nc = 1, 10, 2, 1
+	myApp.Action = func(c *cli.Context) error {
+		config := Config{}
+		config.Listen = c.String("listen")
+		config.Target = c.String("target")
+		config.Key = c.String("key")
+		config.Crypt = c.String("crypt")
+		config.Mode = c.String("mode")
+		config.MTU = c.Int("mtu")
+		config.SndWnd = c.Int("sndwnd")
+		config.RcvWnd = c.Int("rcvwnd")
+		config.DataShard = c.Int("datashard")
+		config.ParityShard = c.Int("parityshard")
+		config.DSCP = c.Int("dscp")
+		config.NoComp = c.Bool("nocomp")
+		config.AckNodelay = c.Bool("acknodelay")
+		config.NoDelay = c.Int("nodelay")
+		config.Interval = c.Int("interval")
+		config.Resend = c.Int("resend")
+		config.NoCongestion = c.Int("nc")
+		config.SockBuf = c.Int("sockbuf")
+		config.SmuxBuf = c.Int("smuxbuf")
+		config.StreamBuf = c.Int("streambuf")
+		config.SmuxVer = c.Int("smuxver")
+		config.KeepAlive = c.Int("keepalive")
+		config.Log = c.String("log")
+		config.SnmpLog = c.String("snmplog")
+		config.SnmpPeriod = c.Int("snmpperiod")
+		config.Pprof = c.Bool("pprof")
+		config.Quiet = c.Bool("quiet")
+		config.TCP = c.Bool("tcp")
+
+		if c.String("c") != "" {
+			//Now only support json config file
+			err := parseJSONConfig(&config, c.String("c"))
+			checkError(err)
 		}
 
-		pass := pbkdf2.Key([]byte(c.String("key")), []byte(SALT), 4096, 32, sha1.New)
+		// log redirect
+		if config.Log != "" {
+			f, err := os.OpenFile(config.Log, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
+			checkError(err)
+			defer f.Close()
+			log.SetOutput(f)
+		}
+
+		switch config.Mode {
+		case "normal":
+			config.NoDelay, config.Interval, config.Resend, config.NoCongestion = 0, 40, 2, 1
+		case "fast":
+			config.NoDelay, config.Interval, config.Resend, config.NoCongestion = 0, 30, 2, 1
+		case "fast2":
+			config.NoDelay, config.Interval, config.Resend, config.NoCongestion = 1, 20, 2, 1
+		case "fast3":
+			config.NoDelay, config.Interval, config.Resend, config.NoCongestion = 1, 10, 2, 1
+		}
+
+		log.Println("version:", VERSION)
+		log.Println("smux version:", config.SmuxVer)
+		log.Println("listening on:", config.Listen)
+		log.Println("target:", config.Target)
+		log.Println("encryption:", config.Crypt)
+		log.Println("nodelay parameters:", config.NoDelay, config.Interval, config.Resend, config.NoCongestion)
+		log.Println("sndwnd:", config.SndWnd, "rcvwnd:", config.RcvWnd)
+		log.Println("compression:", !config.NoComp)
+		log.Println("mtu:", config.MTU)
+		log.Println("datashard:", config.DataShard, "parityshard:", config.ParityShard)
+		log.Println("acknodelay:", config.AckNodelay)
+		log.Println("dscp:", config.DSCP)
+		log.Println("sockbuf:", config.SockBuf)
+		log.Println("smuxbuf:", config.SmuxBuf)
+		log.Println("streambuf:", config.StreamBuf)
+		log.Println("keepalive:", config.KeepAlive)
+		log.Println("snmplog:", config.SnmpLog)
+		log.Println("snmpperiod:", config.SnmpPeriod)
+		log.Println("pprof:", config.Pprof)
+		log.Println("quiet:", config.Quiet)
+		log.Println("tcp:", config.TCP)
+
+		// parameters check
+		if config.SmuxVer > maxSmuxVer {
+			log.Fatal("unsupported smux version:", config.SmuxVer)
+		}
+
+		log.Println("initiating key derivation")
+		pass := pbkdf2.Key([]byte(config.Key), []byte(SALT), 4096, 32, sha1.New)
+		log.Println("key derivation done")
 		var block kcp.BlockCrypt
-		switch c.String("crypt") {
+		switch config.Crypt {
+		case "sm4":
+			block, _ = kcp.NewSM4BlockCrypt(pass[:16])
 		case "tea":
 			block, _ = kcp.NewTEABlockCrypt(pass[:16])
 		case "xor":
 			block, _ = kcp.NewSimpleXORBlockCrypt(pass)
 		case "none":
 			block, _ = kcp.NewNoneBlockCrypt(pass)
+		case "aes-128":
+			block, _ = kcp.NewAESBlockCrypt(pass[:16])
+		case "aes-192":
+			block, _ = kcp.NewAESBlockCrypt(pass[:24])
+		case "blowfish":
+			block, _ = kcp.NewBlowfishBlockCrypt(pass)
+		case "twofish":
+			block, _ = kcp.NewTwofishBlockCrypt(pass)
+		case "cast5":
+			block, _ = kcp.NewCast5BlockCrypt(pass[:16])
+		case "3des":
+			block, _ = kcp.NewTripleDESBlockCrypt(pass[:24])
+		case "xtea":
+			block, _ = kcp.NewXTEABlockCrypt(pass[:16])
+		case "salsa20":
+			block, _ = kcp.NewSalsa20BlockCrypt(pass)
 		default:
+			config.Crypt = "aes"
 			block, _ = kcp.NewAESBlockCrypt(pass)
 		}
 
-		lis, err := kcp.ListenWithOptions(c.String("listen"), block, c.Int("datashard"), c.Int("parityshard"))
-		if err != nil {
-			log.Fatal(err)
+		go generic.SnmpLogger(config.SnmpLog, config.SnmpPeriod)
+		if config.Pprof {
+			go http.ListenAndServe(":6060", nil)
 		}
-		log.Println("listening on ", lis.Addr())
-		log.Println("encryption:", c.String("crypt"))
-		log.Println("nodelay parameters:", nodelay, interval, resend, nc)
-		log.Println("sndwnd:", c.Int("sndwnd"), "rcvwnd:", c.Int("rcvwnd"))
-		log.Println("compression:", !c.Bool("nocomp"))
-		log.Println("mtu:", c.Int("mtu"))
-		log.Println("datashard:", c.Int("datashard"), "parityshard:", c.Int("parityshard"))
-		log.Println("acknodelay:", c.Bool("acknodelay"))
-		log.Println("dscp:", c.Int("dscp"))
-		for {
-			if conn, err := lis.Accept(); err == nil {
-				log.Println("remote address:", conn.RemoteAddr())
-				conn.SetNoDelay(nodelay, interval, resend, nc)
-				conn.SetMtu(c.Int("mtu"))
-				conn.SetWindowSize(c.Int("sndwnd"), c.Int("rcvwnd"))
-				conn.SetACKNoDelay(c.Bool("acknodelay"))
-				conn.SetDSCP(c.Int("dscp"))
 
-				if c.Bool("nocomp") {
-					go handleMux(conn, c.String("target"))
+		// main loop
+		var wg sync.WaitGroup
+		loop := func(lis *kcp.Listener) {
+			defer wg.Done()
+			if err := lis.SetDSCP(config.DSCP); err != nil {
+				log.Println("SetDSCP:", err)
+			}
+			if err := lis.SetReadBuffer(config.SockBuf); err != nil {
+				log.Println("SetReadBuffer:", err)
+			}
+			if err := lis.SetWriteBuffer(config.SockBuf); err != nil {
+				log.Println("SetWriteBuffer:", err)
+			}
+
+			for {
+				if conn, err := lis.AcceptKCP(); err == nil {
+					log.Println("remote address:", conn.RemoteAddr())
+					conn.SetStreamMode(true)
+					conn.SetWriteDelay(false)
+					conn.SetNoDelay(config.NoDelay, config.Interval, config.Resend, config.NoCongestion)
+					conn.SetMtu(config.MTU)
+					conn.SetWindowSize(config.SndWnd, config.RcvWnd)
+					conn.SetACKNoDelay(config.AckNodelay)
+
+					if config.NoComp {
+						go handleMux(conn, &config)
+					} else {
+						go handleMux(generic.NewCompStream(conn), &config)
+					}
 				} else {
-					go handleMux(newCompStream(conn), c.String("target"))
+					log.Printf("%+v", err)
 				}
+			}
+		}
+
+		if config.TCP { // tcp dual stack
+			if conn, err := tcpraw.Listen("tcp", config.Listen); err == nil {
+				lis, err := kcp.ServeConn(block, config.DataShard, config.ParityShard, conn)
+				checkError(err)
+				wg.Add(1)
+				go loop(lis)
 			} else {
 				log.Println(err)
 			}
 		}
+
+		// udp stack
+		lis, err := kcp.ListenWithOptions(config.Listen, block, config.DataShard, config.ParityShard)
+		checkError(err)
+		wg.Add(1)
+		go loop(lis)
+		wg.Wait()
+		return nil
 	}
 	myApp.Run(os.Args)
 }

server/signal.go

@@ -8,7 +8,7 @@ import (
 	"os/signal"
 	"syscall"
 
-	"github.com/xtaci/kcp-go"
+	kcp "github.com/xtaci/kcp-go/v5"
 )
 
 func init() {
@@ -18,6 +18,7 @@ func init() {
 func sigHandler() {
 	ch := make(chan os.Signal, 1)
 	signal.Notify(ch, syscall.SIGUSR1)
+	signal.Ignore(syscall.SIGPIPE)
 
 	for {
 		switch <-ch {