upgrade to kcp-go@5.4.10

commit f3022926ae0c0d176088c299f40df47b472b7a52
Author: xtaci <daniel820313@gmail.com>
Date:   Wed Jul 3 13:18:04 2019 +0000

    enable tcp option

commit e8be0df1d071a2cab0c2c3bc573af0fd836d852e
Author: xtaci <daniel820313@gmail.com>
Date:   Wed Jul 3 13:01:22 2019 +0000

    fix compile for i386

commit 03d15811558f6aedc9d58b4eeef17b563186ac4b
Author: xtaci <daniel820313@gmail.com>
Date:   Wed Jul 3 12:35:02 2019 +0000

    upd build-release.sh and simplify platformd-depedent dial/listen

commit b8240d92ea453b397a5662c19c5ffebf3356af78
Author: xtaci <daniel820313@gmail.com>
Date:   Wed Jul 3 09:49:01 2019 +0000

    simplify listening

commit e2e87b6f8dcabbd91d521f02baa00443c0ad1df3
Author: xtaci <daniel820313@gmail.com>
Date:   Wed Jul 3 09:41:43 2019 +0000

    simplify dialing

.gitignore

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

.travis.yml

@@ -1,18 +1,18 @@
 language: go
 go:
-    - 1.9.x
-    - 1.10.x
     - 1.11.x
+    - 1.12.x
+    - 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

@@ -1,11 +1,12 @@
 FROM golang:alpine as builder
 MAINTAINER xtaci <daniel820313@gmail.com>
+ENV GO111MODULE=on
 RUN apk update && \
     apk upgrade && \
-    apk add git
+    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:3.6
+FROM alpine:3.9
 COPY --from=builder /go/bin /bin
 EXPOSE 29900/udp
 EXPOSE 12948

README.md

@@ -23,8 +23,6 @@
 
 > *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.*
 
-> *KCP discussion QQ group: 364933586, KCP integration, tuning, network transmission and related technical discussions.*
-
 ### QuickStart
 
 Increase the number of open files on your server, as:
@@ -34,25 +32,24 @@ Increase the number of open files on your server, as:
 Suggested `sysctl.conf` parameters for better handling of UDP packets:
 
 ```
-net.core.rmem_max=26214400
+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
+net.core.netdev_max_backlog=2048 // proportional to -rcvwnd
 ```
 
 You can also increase the per-socket buffer by adding parameter(default 4MB):
 ```
 -sockbuf 16777217
 ```
-increasing this would work for most of the old model CPUs.
-
+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 fast2
-KCP Server: ./server_linux_amd64 -t "TARGET_IP:8388" -l ":4000" -mode fast2
+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:
 
@@ -72,7 +69,15 @@ All precompiled releases are genereated from `build-release.sh` script.
 
 ### Performance
 
-<img src="fast.png" alt="fast.com" height="256px" />       
+<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
 
@@ -95,7 +100,15 @@ All precompiled releases are genereated from `build-release.sh` script.
 
 > *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.
+
+#### 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
 
@@ -106,15 +119,15 @@ All precompiled releases are genereated from `build-release.sh` script.
 #### Usage
 
 ```
-$ ./client_darwin_amd64 -h
+xtaci@gw:~$ ./client_linux_amd64 -h
 NAME:
    kcptun - client(with SMUX)
 
 USAGE:
-   client_darwin_amd64 [global options] command [command options] [arguments...]
+   client_linux_amd64 [global options] command [command options] [arguments...]
 
 VERSION:
-   20180922
+   20190409
 
 COMMANDS:
      help, h  Shows a list of commands or help for one command
@@ -135,8 +148,9 @@ GLOBAL OPTIONS:
    --parityshard value, --ps value  set reed-solomon erasure coding - parityshard (default: 3)
    --dscp value                     set DSCP(6bit) (default: 0)
    --nocomp                         disable compression
-   --sockbuf value                  (default: 4194304)
-   --keepalive value                (default: 10)
+   --sockbuf value                  per-socket buffer in bytes (default: 4194304)
+   --smuxbuf value                  the overall de-mux buffer in bytes (default: 4194304)
+   --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
@@ -144,16 +158,16 @@ GLOBAL OPTIONS:
    -c value                         config from json file, which will override the command from shell
    --help, -h                       show help
    --version, -v                    print the version
-
-$ ./server_darwin_amd64 -h
+   
+xtaci@gw:~$ ./server_linux_amd64 -h
 NAME:
    kcptun - server(with SMUX)
 
 USAGE:
-   server_darwin_amd64 [global options] command [command options] [arguments...]
+   server_linux_amd64 [global options] command [command options] [arguments...]
 
 VERSION:
-   20180922
+   20190409
 
 COMMANDS:
      help, h  Shows a list of commands or help for one command
@@ -171,8 +185,9 @@ GLOBAL OPTIONS:
    --parityshard value, --ps value  set reed-solomon erasure coding - parityshard (default: 3)
    --dscp value                     set DSCP(6bit) (default: 0)
    --nocomp                         disable compression
-   --sockbuf value                  (default: 4194304)
-   --keepalive value                (default: 10)
+   --sockbuf value                  per-socket buffer in bytes (default: 4194304)
+   --smuxbuf value                  the overall de-mux buffer in bytes (default: 4194304)
+   --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
@@ -252,11 +267,17 @@ 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 Usage Control
+#### 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:
@@ -277,29 +298,30 @@ Compression is enabled by default, you can disable it by setting ```-nocomp``` o
 #### SNMP
 
 ```go
-// Snmp defines network statistics indicator
 type Snmp struct {
-    BytesSent        uint64 // raw bytes sent
-    BytesReceived    uint64
-    MaxConn          uint64
-    ActiveOpens      uint64
-    PassiveOpens     uint64
-    CurrEstab        uint64 // count of connections for now
-    InErrs           uint64 // udp read errors
+    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 from kcp
-    InSegs           uint64
-    OutSegs          uint64
-    InBytes          uint64 // udp bytes received
-    OutBytes         uint64 // udp bytes sent
-    RetransSegs      uint64
-    FastRetransSegs  uint64
-    EarlyRetransSegs uint64
+    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
-    FECSegs          uint64 // FEC segments received
+    FECParityShards  uint64 // FEC segments received
     FECShortShards   uint64 // number of data shards that's not enough for recovery
 }
 ```
@@ -342,7 +364,7 @@ The parameters below **MUST** be **IDENTICAL** on **BOTH** side:
 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://play.google.com/store/apps/details?id=com.k17game.k3 -- Battle Zone - Earth 2048, an online strategy game using kcp.
+1. https://zhuanlan.zhihu.com/p/53849089 -- kcptun开发小记
 
 ### Donate 
 
@@ -353,3 +375,5 @@ via Ethereum(ETH): Address: 0x2e4b43ab3d0983da282592571eef61ae5e60f726 , Or scan
 via WeChat
 
 <img src="wechat_donate.jpg" alt="kcptun" height="120px" /> 
+
+（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

@@ -1,6 +1,17 @@
 #!/bin/bash
+
+BUILD_DIR=$(dirname "$0")/build
+mkdir -p $BUILD_DIR
+cd $BUILD_DIR
+
 sum="sha1sum"
 
+if [ "$GO111MODULE" != "on" ]; then
+	echo "GO111MODULE is off"
+else
+	echo "GO111MODULE is on"
+fi 
+
 if ! hash sha1sum 2>/dev/null; then
 	if ! hash shasum 2>/dev/null; then
 		echo "I can't see 'sha1sum' or 'shasum'"
@@ -19,21 +30,34 @@ VERSION=`date -u +%Y%m%d`
 LDFLAGS="-X main.VERSION=$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 CGO_ENABLED=0 GOOS=$os GOARCH=$arch go build -ldflags "$LDFLAGS" -gcflags "$GCFLAGS" -o client_${os}_${arch}${suffix} github.com/xtaci/kcptun/client
-		env CGO_ENABLED=0 GOOS=$os GOARCH=$arch go build -ldflags "$LDFLAGS" -gcflags "$GCFLAGS" -o server_${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}
-		$sum kcptun-${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
@@ -41,10 +65,17 @@ ARMS=(5 6 7)
 for v in ${ARMS[@]}; do
 	env CGO_ENABLED=0 GOOS=linux GOARCH=arm GOARM=$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*
-$sum kcptun-linux-arm-$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

client/config.go

@@ -28,11 +28,15 @@ type Config struct {
 	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 {

client/dial.go

@@ -0,0 +1,18 @@
+package main
+
+import (
+	"github.com/pkg/errors"
+	kcp "github.com/xtaci/kcp-go"
+	"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

@@ -2,87 +2,87 @@ package main
 
 import (
 	"crypto/sha1"
-	"encoding/csv"
 	"fmt"
 	"io"
 	"log"
 	"math/rand"
 	"net"
 	"os"
+	"sync"
 	"time"
 
 	"golang.org/x/crypto/pbkdf2"
 
-	"github.com/golang/snappy"
 	"github.com/pkg/errors"
 	"github.com/urfave/cli"
 	kcp "github.com/xtaci/kcp-go"
+	"github.com/xtaci/kcptun/generic"
 	"github.com/xtaci/smux"
-
-	"path/filepath"
+	smuxv2 "github.com/xtaci/smux/v2"
 )
 
-var (
-	// VERSION is injected by buildflags
-	VERSION = "SELFBUILD"
-	// SALT is use for pbkdf2 key expansion
-	SALT = "kcp-go"
-)
+// SALT is use for pbkdf2 key expansion
+const SALT = "kcp-go"
 
-type compStream struct {
-	conn net.Conn
-	w    *snappy.Writer
-	r    *snappy.Reader
-}
+// maximum supported smux version
+const maxSmuxVer = 2
 
-func (c *compStream) Read(p []byte) (n int, err error) {
-	return c.r.Read(p)
-}
+// VERSION is injected by buildflags
+var VERSION = "SELFBUILD"
 
-func (c *compStream) Write(p []byte) (n int, err error) {
-	n, err = c.w.Write(p)
-	err = c.w.Flush()
-	return n, err
-}
+// A pool for stream copying
+var xmitBuf sync.Pool
 
-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(sess *smux.Session, p1 io.ReadWriteCloser, quiet bool) {
-	if !quiet {
-		log.Println("stream opened")
-		defer log.Println("stream closed")
+func handleClient(mux generic.Mux, p1 net.Conn, quiet bool) {
+	logln := func(v ...interface{}) {
+		if !quiet {
+			log.Println(v...)
+		}
 	}
-
 	defer p1.Close()
-	p2, err := sess.OpenStream()
+	p2, err := mux.Open()
 	if err != nil {
+		logln(err)
 		return
 	}
+
 	defer p2.Close()
 
-	// start tunnel
-	p1die := make(chan struct{})
-	buf1 := make([]byte, 65535)
-	go func() { io.CopyBuffer(p1, p2, buf1); close(p1die) }()
+	if s2, ok := p2.(generic.Stream); ok {
+		logln("stream opened", "in:", p1.RemoteAddr(), "out:", fmt.Sprint(s2.RemoteAddr(), "(", s2.ID(), ")"))
+		defer logln("stream closed", "in:", p1.RemoteAddr(), "out:", fmt.Sprint(s2.RemoteAddr(), "(", s2.ID(), ")"))
+	}
 
-	p2die := make(chan struct{})
-	buf2 := make([]byte, 65535)
-	go func() { io.CopyBuffer(p2, p1, buf2); close(p2die) }()
+	// start tunnel & wait for tunnel termination
+	streamCopy := func(dst io.Writer, src io.ReadCloser) chan struct{} {
+		die := make(chan struct{})
+		go func() {
+			buf := xmitBuf.Get().([]byte)
+			if _, err := generic.CopyBuffer(dst, src, buf); err != nil {
+				if s2, ok := p2.(generic.Stream); ok {
+					// verbose error handling
+					cause := err
+					if e, ok := err.(interface{ Cause() error }); ok {
+						cause = e.Cause()
+					}
+
+					switch cause {
+					case smux.ErrInvalidProtocol:
+						log.Println("smux version:1", err, "in:", p1.RemoteAddr(), "out:", fmt.Sprint(s2.RemoteAddr(), "(", s2.ID(), ")"))
+					case smuxv2.ErrInvalidProtocol:
+						log.Println("smux version:2", err, "in:", p1.RemoteAddr(), "out:", fmt.Sprint(s2.RemoteAddr(), "(", s2.ID(), ")"))
+					}
+				}
+			}
+			xmitBuf.Put(buf)
+			close(die)
+		}()
+		return die
+	}
 
-	// wait for tunnel termination
 	select {
-	case <-p1die:
-	case <-p2die:
+	case <-streamCopy(p1, p2):
+	case <-streamCopy(p2, p1):
 	}
 }
 
@@ -99,6 +99,10 @@ func main() {
 		// add more log flags for debugging
 		log.SetFlags(log.LstdFlags | log.Lshortfile)
 	}
+	xmitBuf.New = func() interface{} {
+		return make([]byte, 32768)
+	}
+
 	myApp := cli.NewApp()
 	myApp.Name = "kcptun"
 	myApp.Usage = "client(with SMUX)"
@@ -209,6 +213,21 @@ func main() {
 			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
@@ -233,6 +252,10 @@ func main() {
 			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
@@ -262,11 +285,15 @@ func main() {
 		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"))
@@ -298,8 +325,37 @@ func main() {
 		listener, err := net.ListenTCP("tcp", addr)
 		checkError(err)
 
+		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)
+
+		// 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 config.Crypt {
 		case "sm4":
@@ -331,33 +387,10 @@ func main() {
 			block, _ = kcp.NewAESBlockCrypt(pass)
 		}
 
-		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("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)
-
-		smuxConfig := smux.DefaultConfig()
-		smuxConfig.MaxReceiveBuffer = config.SockBuf
-		smuxConfig.KeepAliveInterval = time.Duration(config.KeepAlive) * time.Second
-
-		createConn := func() (*smux.Session, error) {
-			kcpconn, err := kcp.DialWithOptions(config.RemoteAddr, block, config.DataShard, config.ParityShard)
+		createConn := func() (generic.Mux, error) {
+			kcpconn, err := dial(&config, block)
 			if err != nil {
-				return nil, errors.Wrap(err, "createConn()")
+				return nil, errors.Wrap(err, "dial()")
 			}
 			kcpconn.SetStreamMode(true)
 			kcpconn.SetWriteDelay(false)
@@ -375,23 +408,48 @@ func main() {
 			if err := kcpconn.SetWriteBuffer(config.SockBuf); err != nil {
 				log.Println("SetWriteBuffer:", err)
 			}
+			log.Println("smux version:", config.SmuxVer, "on connection:", kcpconn.LocalAddr(), "->", kcpconn.RemoteAddr())
+			switch config.SmuxVer {
+			case 1:
+				smuxConfig := smux.DefaultConfig()
+				smuxConfig.MaxReceiveBuffer = config.SmuxBuf
+				smuxConfig.KeepAliveInterval = time.Duration(config.KeepAlive) * time.Second
 
-			// stream multiplex
-			var session *smux.Session
-			if config.NoComp {
-				session, err = smux.Client(kcpconn, smuxConfig)
-			} else {
-				session, err = smux.Client(newCompStream(kcpconn), smuxConfig)
+				// stream multiplex
+				var session *smux.Session
+				if config.NoComp {
+					session, err = smux.Client(kcpconn, smuxConfig)
+				} else {
+					session, err = smux.Client(generic.NewCompStream(kcpconn), smuxConfig)
+				}
+				if err != nil {
+					return nil, errors.Wrap(err, "createConn()")
+				}
+				return session, nil
+			case 2:
+				smuxConfig := smuxv2.DefaultConfig()
+				smuxConfig.MaxReceiveBuffer = config.SmuxBuf
+				smuxConfig.MaxStreamBuffer = config.StreamBuf
+				smuxConfig.KeepAliveInterval = time.Duration(config.KeepAlive) * time.Second
+
+				// stream multiplex
+				var session *smuxv2.Session
+				if config.NoComp {
+					session, err = smuxv2.Client(kcpconn, smuxConfig)
+				} else {
+					session, err = smuxv2.Client(generic.NewCompStream(kcpconn), smuxConfig)
+				}
+				if err != nil {
+					return nil, errors.Wrap(err, "createConn()")
+				}
+				return session, nil
+			default:
+				panic("incorrect smux version")
 			}
-			if err != nil {
-				return nil, errors.Wrap(err, "createConn()")
-			}
-			log.Println("connection:", kcpconn.LocalAddr(), "->", kcpconn.RemoteAddr())
-			return session, nil
 		}
 
 		// wait until a connection is ready
-		waitConn := func() *smux.Session {
+		waitConn := func() generic.Mux {
 			for {
 				if session, err := createConn(); err == nil {
 					return session
@@ -404,7 +462,7 @@ func main() {
 
 		numconn := uint16(config.Conn)
 		muxes := make([]struct {
-			session *smux.Session
+			session generic.Mux
 			ttl     time.Time
 		}, numconn)
 
@@ -413,16 +471,15 @@ func main() {
 			muxes[k].ttl = time.Now().Add(time.Duration(config.AutoExpire) * time.Second)
 		}
 
-		chScavenger := make(chan *smux.Session, 128)
+		chScavenger := make(chan generic.Mux, 128)
 		go scavenger(chScavenger, config.ScavengeTTL)
-		go snmpLogger(config.SnmpLog, config.SnmpPeriod)
+		go generic.SnmpLogger(config.SnmpLog, config.SnmpPeriod)
 		rr := uint16(0)
 		for {
 			p1, err := listener.AcceptTCP()
 			if err != nil {
-				log.Fatalln(err)
+				log.Fatalf("%+v", err)
 			}
-			checkError(err)
 			idx := rr % numconn
 
 			// do auto expiration && reconnection
@@ -440,11 +497,11 @@ func main() {
 }
 
 type scavengeSession struct {
-	session *smux.Session
+	session generic.Mux
 	ts      time.Time
 }
 
-func scavenger(ch chan *smux.Session, ttl int) {
+func scavenger(ch chan generic.Mux, ttl int) {
 	ticker := time.NewTicker(time.Second)
 	defer ticker.Stop()
 	var sessionList []scavengeSession
@@ -452,16 +509,16 @@ func scavenger(ch chan *smux.Session, ttl int) {
 		select {
 		case sess := <-ch:
 			sessionList = append(sessionList, scavengeSession{sess, time.Now()})
-			log.Println("session marked as expired")
+			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")
+					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")
+					log.Println("session reached scavenge ttl", s.session.RemoteAddr())
 					s.session.Close()
 				} else {
 					newList = append(newList, sessionList[k])
@@ -471,37 +528,3 @@ func scavenger(ch chan *smux.Session, ttl int) {
 		}
 	}
 }
-
-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()
-		}
-	}
-}

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 +1,36 @@
+package generic
+
+import "io"
+
+// io.CopyBuffer has extra tests for interface like io.ReaderFrom and io.WriterTo
+// which is not efficient in memory management from tests
+func CopyBuffer(dst io.Writer, src io.Reader, buf []byte) (written int64, err error) {
+	if buf != nil && len(buf) == 0 {
+		panic("empty buffer in copyBuffer")
+	}
+
+	for {
+		nr, er := src.Read(buf)
+		if nr > 0 {
+			nw, ew := dst.Write(buf[0:nr])
+			if nw > 0 {
+				written += int64(nw)
+			}
+			if ew != nil {
+				err = ew
+				break
+			}
+			if nr != nw {
+				err = io.ErrShortWrite
+				break
+			}
+		}
+		if er != nil {
+			if er != io.EOF {
+				err = er
+			}
+			break
+		}
+	}
+	return written, err
+}

generic/mux.go

@@ -0,0 +1,21 @@
+package generic
+
+import (
+	"io"
+	"net"
+)
+
+type Mux interface {
+	Open() (io.ReadWriteCloser, error)
+	Accept() (io.ReadWriteCloser, error)
+	IsClosed() bool
+	NumStreams() int
+	RemoteAddr() net.Addr
+	Close() error
+}
+
+type Stream interface {
+	io.ReadWriteCloser
+	ID() uint32
+	RemoteAddr() net.Addr
+}

generic/snmp.go

@@ -0,0 +1,46 @@
+package generic
+
+import (
+	"encoding/csv"
+	"fmt"
+	"log"
+	"os"
+	"path/filepath"
+	"time"
+
+	"github.com/xtaci/kcp-go"
+)
+
+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 +1,24 @@
+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 v1.2.1 // indirect
+	github.com/klauspost/reedsolomon v1.9.2 // indirect
+	github.com/pkg/errors v0.8.1
+	github.com/templexxx/cpufeat v0.0.0-20180724012125-cef66df7f161 // indirect
+	github.com/templexxx/xor v0.0.0-20181023030647-4e92f724b73b // indirect
+	github.com/tjfoc/gmsm v1.0.1 // indirect
+	github.com/urfave/cli v1.21.0
+	github.com/xtaci/kcp-go v5.4.10+incompatible
+	github.com/xtaci/lossyconn v0.0.0-20190602105132-8df528c0c9ae // indirect
+	github.com/xtaci/smux v1.4.4
+	github.com/xtaci/smux/v2 v2.0.11
+	github.com/xtaci/tcpraw v1.2.25
+	golang.org/x/crypto v0.0.0-20190909091759-094676da4a83
+	golang.org/x/net v0.0.0-20190909003024-a7b16738d86b // indirect
+	golang.org/x/sys v0.0.0-20190910064555-bbd175535a8b // indirect
+)
+
+go 1.13

go.sum

@@ -0,0 +1,53 @@
+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 v1.2.1 h1:vJi+O/nMdFt0vqm8NZBI6wzALWdA2X+egi0ogNyrC/w=
+github.com/klauspost/cpuid v1.2.1/go.mod h1:Pj4uuM528wm8OyEC2QMXAi2YiTZ96dNQPGgoMS4s3ek=
+github.com/klauspost/reedsolomon v1.9.2 h1:E9CMS2Pqbv+C7tsrYad4YC9MfhnMVWhMRsTi7U0UB18=
+github.com/klauspost/reedsolomon v1.9.2/go.mod h1:CwCi+NUr9pqSVktrkN+Ondf06rkhYZ/pcNv7fu+8Un4=
+github.com/pkg/errors v0.8.1 h1:iURUrRGxPUNPdy5/HRSm+Yj6okJ6UtLINN0Q9M4+h3I=
+github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
+github.com/templexxx/cpufeat v0.0.0-20180724012125-cef66df7f161 h1:89CEmDvlq/F7SJEOqkIdNDGJXrQIhuIx9D2DBXjavSU=
+github.com/templexxx/cpufeat v0.0.0-20180724012125-cef66df7f161/go.mod h1:wM7WEvslTq+iOEAMDLSzhVuOt5BRZ05WirO+b09GHQU=
+github.com/templexxx/xor v0.0.0-20181023030647-4e92f724b73b h1:mnG1fcsIB1d/3vbkBak2MM0u+vhGhlQwpeimUi7QncM=
+github.com/templexxx/xor v0.0.0-20181023030647-4e92f724b73b/go.mod h1:5XA7W9S6mni3h5uvOC75dA3m9CCCaS83lltmc0ukdi4=
+github.com/tjfoc/gmsm v1.0.1 h1:R11HlqhXkDospckjZEihx9SW/2VW0RgdwrykyWMFOQU=
+github.com/tjfoc/gmsm v1.0.1/go.mod h1:XxO4hdhhrzAd+G4CjDqaOkd0hUzmtPR/d3EiBBMn/wc=
+github.com/urfave/cli v1.21.0 h1:wYSSj06510qPIzGSua9ZqsncMmWE3Zr55KBERygyrxE=
+github.com/urfave/cli v1.21.0/go.mod h1:lxDj6qX9Q6lWQxIrbrT0nwecwUtRnhVZAJjJZrVUZZQ=
+github.com/xtaci/kcp-go v5.4.7+incompatible h1:0WXorSb87WBIVjXWv618klAeCh8H32NcDpWq+g04x2E=
+github.com/xtaci/kcp-go v5.4.7+incompatible/go.mod h1:bN6vIwHQbfHaHtFpEssmWsN45a+AZwO7eyRCmEIbtvE=
+github.com/xtaci/kcp-go v5.4.8+incompatible h1:4GnTyiiC1S7ZFBMKvsF0gMJ3MoN1BoiFRCQ7IuAeUB0=
+github.com/xtaci/kcp-go v5.4.8+incompatible/go.mod h1:bN6vIwHQbfHaHtFpEssmWsN45a+AZwO7eyRCmEIbtvE=
+github.com/xtaci/kcp-go v5.4.9+incompatible h1:wrMgJXB/UFch+ERT0Qr4wO9CSqPAXWblbnH9uGK7TM4=
+github.com/xtaci/kcp-go v5.4.9+incompatible/go.mod h1:bN6vIwHQbfHaHtFpEssmWsN45a+AZwO7eyRCmEIbtvE=
+github.com/xtaci/kcp-go v5.4.10+incompatible h1:FgH1ji3efEmRFaHEeyim1RYN4Q/c8BT8VqXMklBmh84=
+github.com/xtaci/kcp-go v5.4.10+incompatible/go.mod h1:bN6vIwHQbfHaHtFpEssmWsN45a+AZwO7eyRCmEIbtvE=
+github.com/xtaci/lossyconn v0.0.0-20190602105132-8df528c0c9ae h1:J0GxkO96kL4WF+AIT3M4mfUVinOCPgf2uUWYFUzN0sM=
+github.com/xtaci/lossyconn v0.0.0-20190602105132-8df528c0c9ae/go.mod h1:gXtu8J62kEgmN++bm9BVICuT/e8yiLI2KFobd/TRFsE=
+github.com/xtaci/smux v1.4.4 h1:FukIfahko+KHhS9Gxppkp6756opZymvPOLNmpny1is4=
+github.com/xtaci/smux v1.4.4/go.mod h1:LuA3S0xssf4fmGRJ7ow3EehgmDUzib4EcobaFNKvlMA=
+github.com/xtaci/smux/v2 v2.0.10 h1:EKYuZH06sfoId5REZXyHmKTSgIeU5Ko27JICc0YI6ys=
+github.com/xtaci/smux/v2 v2.0.10/go.mod h1:Iqy5a3Gax2p7WCKHOHkSNo/COthNFXd3/vqrcKNtzqI=
+github.com/xtaci/smux/v2 v2.0.11 h1:thVWmgGRciZ8iaATwpY2B/51aHzmMI6wrF7DfcJSckU=
+github.com/xtaci/smux/v2 v2.0.11/go.mod h1:Iqy5a3Gax2p7WCKHOHkSNo/COthNFXd3/vqrcKNtzqI=
+github.com/xtaci/tcpraw v1.2.25 h1:VDlqo0op17JeXBM6e2G9ocCNLOJcw9mZbobMbJjo0vk=
+github.com/xtaci/tcpraw v1.2.25/go.mod h1:dKyZ2V75s0cZ7cbgJYdxPvms7af0joIeOyx1GgJQbLk=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/crypto v0.0.0-20190909091759-094676da4a83 h1:mgAKeshyNqWKdENOnQsg+8dRTwZFIwFaO3HNl52sweA=
+golang.org/x/crypto v0.0.0-20190909091759-094676da4a83/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
+golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
+golang.org/x/net v0.0.0-20190909003024-a7b16738d86b h1:XfVGCX+0T4WOStkaOsJRllbsiImhB2jgVBGc9L0lPGc=
+golang.org/x/net v0.0.0-20190909003024-a7b16738d86b/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 v0.0.0-20190910064555-bbd175535a8b h1:3S2h5FadpNr0zUUCVZjlKIEYF+KaX/OBplTGo89CYHI=
+golang.org/x/sys v0.0.0-20190910064555-bbd175535a8b/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

@@ -25,12 +25,16 @@ type Config struct {
 	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 {

server/main.go

@@ -2,7 +2,6 @@ package main
 
 import (
 	"crypto/sha1"
-	"encoding/csv"
 	"fmt"
 	"io"
 	"log"
@@ -11,103 +10,143 @@ import (
 	"net/http"
 	_ "net/http/pprof"
 	"os"
+	"sync"
 	"time"
 
 	"golang.org/x/crypto/pbkdf2"
 
-	"path/filepath"
-
-	"github.com/golang/snappy"
 	"github.com/urfave/cli"
 	kcp "github.com/xtaci/kcp-go"
+	"github.com/xtaci/kcptun/generic"
 	"github.com/xtaci/smux"
+	smuxv2 "github.com/xtaci/smux/v2"
+	"github.com/xtaci/tcpraw"
 )
 
-var (
-	// VERSION is injected by buildflags
-	VERSION = "SELFBUILD"
-	// SALT is use for pbkdf2 key expansion
-	SALT = "kcp-go"
-)
+// SALT is use for pbkdf2 key expansion
+const SALT = "kcp-go"
 
-type compStream struct {
-	conn net.Conn
-	w    *snappy.Writer
-	r    *snappy.Reader
-}
+// maximum supported smux version
+const maxSmuxVer = 2
 
-func (c *compStream) Read(p []byte) (n int, err error) {
-	return c.r.Read(p)
-}
+// VERSION is injected by buildflags
+var VERSION = "SELFBUILD"
 
-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
-}
+// A pool for stream copying
+var xmitBuf sync.Pool
 
 // handle multiplex-ed connection
-func handleMux(conn io.ReadWriteCloser, config *Config) {
-	// stream multiplex
-	smuxConfig := smux.DefaultConfig()
-	smuxConfig.MaxReceiveBuffer = config.SockBuf
-	smuxConfig.KeepAliveInterval = time.Duration(config.KeepAlive) * time.Second
-
-	mux, err := smux.Server(conn, smuxConfig)
-	if err != nil {
-		log.Println(err)
-		return
+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
 	}
-	defer mux.Close()
-	for {
-		p1, err := mux.AcceptStream()
+	log.Println("smux version:", config.SmuxVer, "on connection:", conn.LocalAddr(), "->", conn.RemoteAddr())
+
+	// stream multiplex
+	var muxer generic.Mux
+	switch config.SmuxVer {
+	case 1:
+		smuxConfig := smux.DefaultConfig()
+		smuxConfig.MaxReceiveBuffer = config.SmuxBuf
+		smuxConfig.KeepAliveInterval = time.Duration(config.KeepAlive) * time.Second
+
+		mux, err := smux.Server(conn, smuxConfig)
 		if err != nil {
 			log.Println(err)
 			return
 		}
-		p2, err := net.DialTimeout("tcp", config.Target, 5*time.Second)
+		defer mux.Close()
+		muxer = mux
+	case 2:
+		smuxConfig := smuxv2.DefaultConfig()
+		smuxConfig.MaxReceiveBuffer = config.SmuxBuf
+		smuxConfig.MaxStreamBuffer = config.StreamBuf
+		smuxConfig.KeepAliveInterval = time.Duration(config.KeepAlive) * time.Second
+
+		mux, err := smuxv2.Server(conn, smuxConfig)
 		if err != nil {
-			p1.Close()
 			log.Println(err)
-			continue
+			return
 		}
-		go handleClient(p1, p2, config.Quiet)
+		defer mux.Close()
+		muxer = mux
+	default:
+		panic("incorrect smux version")
+	}
+
+	for {
+		stream, err := muxer.Accept()
+		if err != nil {
+			log.Println(err)
+			return
+		}
+
+		go func(p1 io.ReadWriteCloser) {
+			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, quiet bool) {
-	if !quiet {
-		log.Println("stream opened")
-		defer log.Println("stream closed")
+func handleClient(p1 io.ReadWriteCloser, 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{})
-	buf1 := make([]byte, 65535)
-	go func() { io.CopyBuffer(p1, p2, buf1); close(p1die) }()
+	if s1, ok := p1.(generic.Stream); ok {
+		logln("stream opened", "in:", fmt.Sprint(s1.RemoteAddr(), "(", s1.ID(), ")"), "out:", p2.RemoteAddr())
+		defer logln("stream closed", "in:", fmt.Sprint(s1.RemoteAddr(), "(", s1.ID(), ")"), "out:", p2.RemoteAddr())
+	}
 
-	p2die := make(chan struct{})
-	buf2 := make([]byte, 65535)
-	go func() { io.CopyBuffer(p2, p1, buf2); close(p2die) }()
+	// start tunnel & wait for tunnel termination
+	streamCopy := func(dst io.Writer, src io.ReadCloser) chan struct{} {
+		die := make(chan struct{})
+		go func() {
+			buf := xmitBuf.Get().([]byte)
+			if _, err := generic.CopyBuffer(dst, src, buf); err != nil {
+				if s1, ok := p1.(generic.Stream); ok {
+					// verbose error handling
+					cause := err
+					if e, ok := err.(interface{ Cause() error }); ok {
+						cause = e.Cause()
+					}
+
+					switch cause {
+					case smux.ErrInvalidProtocol:
+						log.Println("smux version:1", err, "in:", fmt.Sprint(s1.RemoteAddr(), "(", s1.ID(), ")"), "out:", p2.RemoteAddr())
+					case smuxv2.ErrInvalidProtocol:
+						log.Println("smux version:2", err, "in:", fmt.Sprint(s1.RemoteAddr(), "(", s1.ID(), ")"), "out:", p2.RemoteAddr())
+					}
+				}
+			}
+			xmitBuf.Put(buf)
+			close(die)
+		}()
+		return die
+	}
 
-	// wait for tunnel termination
 	select {
-	case <-p1die:
-	case <-p2die:
+	case <-streamCopy(p1, p2):
+	case <-streamCopy(p2, p1):
 	}
 }
 
@@ -124,6 +163,10 @@ func main() {
 		// add more log flags for debugging
 		log.SetFlags(log.LstdFlags | log.Lshortfile)
 	}
+	xmitBuf.New = func() interface{} {
+		return make([]byte, 32768)
+	}
+
 	myApp := cli.NewApp()
 	myApp.Name = "kcptun"
 	myApp.Usage = "server(with SMUX)"
@@ -137,7 +180,7 @@ 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",
@@ -219,6 +262,21 @@ func main() {
 			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
@@ -247,6 +305,10 @@ func main() {
 			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
@@ -273,12 +335,16 @@ func main() {
 		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
@@ -306,8 +372,35 @@ func main() {
 		}
 
 		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 config.Crypt {
 		case "sm4":
@@ -339,93 +432,64 @@ func main() {
 			block, _ = kcp.NewAESBlockCrypt(pass)
 		}
 
-		lis, err := kcp.ListenWithOptions(config.Listen, block, config.DataShard, config.ParityShard)
-		checkError(err)
-		log.Println("listening on:", lis.Addr())
-		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("keepalive:", config.KeepAlive)
-		log.Println("snmplog:", config.SnmpLog)
-		log.Println("snmpperiod:", config.SnmpPeriod)
-		log.Println("pprof:", config.Pprof)
-		log.Println("quiet:", config.Quiet)
-
-		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)
-		}
-
-		go snmpLogger(config.SnmpLog, config.SnmpPeriod)
+		go generic.SnmpLogger(config.SnmpLog, config.SnmpPeriod)
 		if config.Pprof {
 			go http.ListenAndServe(":6060", nil)
 		}
 
-		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)
+		// 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)
+			}
 
-				if config.NoComp {
-					go handleMux(conn, &config)
+			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), &config)
+					log.Printf("%+v", err)
 				}
-			} else {
-				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)
 }
-
-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()
-		}
-	}
-}