upd deps

* Add files via upload

* Update README.md

.gitignore

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

Dockerfile

@@ -5,7 +5,7 @@ RUN apk update && \
     apk add git
 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 +364,6 @@ 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.
 
 ### Donate 
 
@@ -353,3 +374,24 @@ 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。）
+
+## Contributors
+
+This project exists thanks to all the people who contribute. 
+<a href="https://github.com/xtaci/kcptun/graphs/contributors"><img src="https://opencollective.com/kcptun/contributors.svg?width=890&button=false" /></a>
+
+
+## Backers
+
+Thank you to all our backers! 🙏 [[Become a backer](https://opencollective.com/kcptun#backer)]
+
+<a href="https://opencollective.com/kcptun#backers" target="_blank"><img src="https://opencollective.com/kcptun/backers.svg?width=890"></a>
+
+
+## Sponsors
+
+Support this project by becoming a sponsor. Your logo will show up here with a link to your website. [[Become a sponsor](https://opencollective.com/kcptun#sponsor)]
+
+

build-release.sh

@@ -1,6 +1,12 @@
 #!/bin/bash
+BUILD_DIR=$(dirname "$0")/build
+mkdir -p $BUILD_DIR
+cd $BUILD_DIR
+
 sum="sha1sum"
 
+echo "If you need reproducible build, export GO111MODULE=on first"
+
 if ! hash sha1sum 2>/dev/null; then
 	if ! hash shasum 2>/dev/null; then
 		echo "I can't see 'sha1sum' or 'shasum'"
@@ -19,21 +25,34 @@ 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 +60,17 @@ 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

@@ -28,6 +28,7 @@ type Config struct {
 	Resend       int    `json:"resend"`
 	NoCongestion int    `json:"nc"`
 	SockBuf      int    `json:"sockbuf"`
+	SmuxBuf      int    `json:"smuxbuf"`
 	KeepAlive    int    `json:"keepalive"`
 	Log          string `json:"log"`
 	SnmpLog      string `json:"snmplog"`

client/main.go

@@ -2,87 +2,66 @@ 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"
 )
 
-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
-}
+// VERSION is injected by buildflags
+var VERSION = "SELFBUILD"
 
-func (c *compStream) Read(p []byte) (n int, err error) {
-	return c.r.Read(p)
-}
+// A pool for stream copying
+var xmitBuf sync.Pool
 
-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(sess *smux.Session, p1 io.ReadWriteCloser, quiet bool) {
-	if !quiet {
-		log.Println("stream opened")
-		defer log.Println("stream closed")
+func handleClient(sess *smux.Session, p1 net.Conn, quiet bool) {
+	logln := func(v ...interface{}) {
+		if !quiet {
+			log.Println(v...)
+		}
 	}
-
 	defer p1.Close()
 	p2, err := sess.OpenStream()
 	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) }()
+	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{})
-	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)
+			generic.CopyBuffer(dst, src, buf)
+			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 +78,10 @@ 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 +192,11 @@ func main() {
 			Value: 4194304, // socket buffer size in bytes
 			Usage: "per-socket buffer in bytes",
 		},
+		cli.IntFlag{
+			Name:  "smuxbuf",
+			Value: 4194304,
+			Usage: "the overall de-mux buffer in bytes",
+		},
 		cli.IntFlag{
 			Name:  "keepalive",
 			Value: 10, // nat keepalive interval in seconds
@@ -262,6 +250,7 @@ func main() {
 		config.Resend = c.Int("resend")
 		config.NoCongestion = c.Int("nc")
 		config.SockBuf = c.Int("sockbuf")
+		config.SmuxBuf = c.Int("smuxbuf")
 		config.KeepAlive = c.Int("keepalive")
 		config.Log = c.String("log")
 		config.SnmpLog = c.String("snmplog")
@@ -342,6 +331,7 @@ func main() {
 		log.Println("acknodelay:", config.AckNodelay)
 		log.Println("dscp:", config.DSCP)
 		log.Println("sockbuf:", config.SockBuf)
+		log.Println("smuxbuf:", config.SmuxBuf)
 		log.Println("keepalive:", config.KeepAlive)
 		log.Println("conn:", config.Conn)
 		log.Println("autoexpire:", config.AutoExpire)
@@ -351,7 +341,7 @@ func main() {
 		log.Println("quiet:", config.Quiet)
 
 		smuxConfig := smux.DefaultConfig()
-		smuxConfig.MaxReceiveBuffer = config.SockBuf
+		smuxConfig.MaxReceiveBuffer = config.SmuxBuf
 		smuxConfig.KeepAliveInterval = time.Duration(config.KeepAlive) * time.Second
 
 		createConn := func() (*smux.Session, error) {
@@ -381,7 +371,7 @@ func main() {
 			if config.NoComp {
 				session, err = smux.Client(kcpconn, smuxConfig)
 			} else {
-				session, err = smux.Client(newCompStream(kcpconn), smuxConfig)
+				session, err = smux.Client(generic.NewCompStream(kcpconn), smuxConfig)
 			}
 			if err != nil {
 				return nil, errors.Wrap(err, "createConn()")
@@ -415,14 +405,13 @@ func main() {
 
 		chScavenger := make(chan *smux.Session, 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
@@ -452,16 +441,16 @@ 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 +460,3 @@ 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()
-		}
-	}
-}

generic/comp.go

@@ -0,0 +1,41 @@
+package generic
+
+import (
+	"net"
+
+	"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 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/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 +1,19 @@
+module github.com/xtaci/kcptun
+
+require (
+	github.com/golang/snappy v0.0.1
+	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 v1.20.0
+	github.com/xtaci/kcp-go v5.4.2+incompatible
+	github.com/xtaci/smux v1.3.3
+	golang.org/x/crypto v0.0.0-20190605123033-f99c8df09eb5
+	golang.org/x/net v0.0.0-20190607181551-461777fb6f67 // indirect
+	golang.org/x/sys v0.0.0-20190610200419-93c9922d18ae // indirect
+	golang.org/x/text v0.3.2 // indirect
+	golang.org/x/tools v0.0.0-20190610231749-f8d1dee965f7 // indirect
+)

go.sum

@@ -0,0 +1,163 @@
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+github.com/golang/snappy v0.0.1/go.mod h1:/XxbfmMg8lxefKM7IXC3fBNl/7bRcc72aCRzEWrmP2Q=
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+github.com/klauspost/cpuid v1.2.1/go.mod h1:Pj4uuM528wm8OyEC2QMXAi2YiTZ96dNQPGgoMS4s3ek=
+github.com/klauspost/reedsolomon v1.9.1 h1:kYrT1MlR4JH6PqOpC+okdb9CDTcwEC/BqpzK4WFyXL8=
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+github.com/templexxx/cpufeat v0.0.0-20180724012125-cef66df7f161 h1:89CEmDvlq/F7SJEOqkIdNDGJXrQIhuIx9D2DBXjavSU=
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server/config.go

@@ -25,6 +25,7 @@ type Config struct {
 	Resend       int    `json:"resend"`
 	NoCongestion int    `json:"nc"`
 	SockBuf      int    `json:"sockbuf"`
+	SmuxBuf      int    `json:"smuxbuf"`
 	KeepAlive    int    `json:"keepalive"`
 	Log          string `json:"log"`
 	SnmpLog      string `json:"snmplog"`

server/main.go

@@ -2,7 +2,6 @@ package main
 
 import (
 	"crypto/sha1"
-	"encoding/csv"
 	"fmt"
 	"io"
 	"log"
@@ -11,58 +10,31 @@ 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"
 )
 
-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
-}
+// 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
-}
+// 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.MaxReceiveBuffer = config.SmuxBuf
 	smuxConfig.KeepAliveInterval = time.Duration(config.KeepAlive) * time.Second
 
 	mux, err := smux.Server(conn, smuxConfig)
@@ -72,42 +44,52 @@ func handleMux(conn io.ReadWriteCloser, config *Config) {
 	}
 	defer mux.Close()
 	for {
-		p1, err := mux.AcceptStream()
+		stream, err := mux.AcceptStream()
 		if err != nil {
 			log.Println(err)
 			return
 		}
-		p2, err := net.DialTimeout("tcp", config.Target, 5*time.Second)
-		if err != nil {
-			p1.Close()
-			log.Println(err)
-			continue
-		}
-		go handleClient(p1, p2, config.Quiet)
+
+		go func(p1 *smux.Stream) {
+			p2, err := net.Dial("tcp", 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 *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{})
-	buf1 := make([]byte, 65535)
-	go func() { io.CopyBuffer(p1, p2, buf1); 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{})
-	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)
+			generic.CopyBuffer(dst, src, buf)
+			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 +106,10 @@ 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)"
@@ -219,6 +205,11 @@ func main() {
 			Value: 4194304, // socket buffer size in bytes
 			Usage: "per-socket buffer in bytes",
 		},
+		cli.IntFlag{
+			Name:  "smuxbuf",
+			Value: 4194304,
+			Usage: "the overall de-mux buffer in bytes",
+		},
 		cli.IntFlag{
 			Name:  "keepalive",
 			Value: 10, // nat keepalive interval in seconds
@@ -273,6 +264,7 @@ func main() {
 		config.Resend = c.Int("resend")
 		config.NoCongestion = c.Int("nc")
 		config.SockBuf = c.Int("sockbuf")
+		config.SmuxBuf = c.Int("smuxbuf")
 		config.KeepAlive = c.Int("keepalive")
 		config.Log = c.String("log")
 		config.SnmpLog = c.String("snmplog")
@@ -352,6 +344,7 @@ func main() {
 		log.Println("acknodelay:", config.AckNodelay)
 		log.Println("dscp:", config.DSCP)
 		log.Println("sockbuf:", config.SockBuf)
+		log.Println("smuxbuf:", config.SmuxBuf)
 		log.Println("keepalive:", config.KeepAlive)
 		log.Println("snmplog:", config.SnmpLog)
 		log.Println("snmpperiod:", config.SnmpPeriod)
@@ -368,7 +361,7 @@ func main() {
 			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)
 		}
@@ -386,7 +379,7 @@ func main() {
 				if config.NoComp {
 					go handleMux(conn, &config)
 				} else {
-					go handleMux(newCompStream(conn), &config)
+					go handleMux(generic.NewCompStream(conn), &config)
 				}
 			} else {
 				log.Printf("%+v", err)
@@ -395,37 +388,3 @@ func main() {
 	}
 	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()
-		}
-	}
-}