#####用go写的socks5服务器端代码：
1.默认只支持用户名密码的认证方式(username:abc , password:123)，监听 tcp 8083 端口；
2.CMD支持TCP、UDP，不支持BIND，需要的可自行再实现；
3.支持ipv4、domain，目前不支持 ipv6；
4.建议客户端使用 proxycap， proxycap、SocksCap64 测试过能很好支持。（玩LOL，正常游戏）建议客户端不设置服务器端做DNS解析，效率相对会慢些；
5.注意服务端 防火墙 tcp 8083 端口开放及UDP协议全开放;
6.使用时有bug或问题欢迎留言;
7.想尝试用 go 写个简单的客户端，支持 lsp 劫持，配合服务器端做代理，不清楚有什么方法或 包 实现，请路过的大牛懂的请赐教！
##### 代码部分 //socks5协议文档： http://www.ietf.org/rfc/rfc1928.txt.pdf
main.go：
```
package main
import (
"bytes"
"encoding/binary"
"errors"
"fmt"
"log"
"net"
"sync"
"time"
)
var (
tcpConnId uint64
udpConnId uint64
)
type proxy struct {
conn *net.TCPConn
}
type uServ struct {
prefix string
sigQuit chan bool
clientUdpAddr *net.UDPAddr
dstMap map[string]string
sync.RWMutex
}
func main() {
// Listen Tcp, support ipv4 only. @20171204
service := "0.0.0.0:8083"
tcpAddr, err := net.ResolveTCPAddr("tcp", service)
errCheckWithFatal("ResolveTcpAddr err:%v\n", err)
tcpListener, err := net.ListenTCP("tcp", tcpAddr)
errCheckWithFatal("ListenTCP err:%v\n", err)
for {
tcpConn, err := tcpListener.AcceptTCP()
errCheckWithPrint("Warn >>> AcceptTCP err:%v\n", err)
if err != nil {
continue
}
proxy := NewProxy(tcpConn)
go proxy.run()
}
}
func NewProxy(conn *net.TCPConn) *proxy {
return &proxy{
conn: conn,
}
}
func (p *proxy) run() {
defer p.conn.Close()
remoteAddrStr := p.conn.RemoteAddr().String()
// read
buf := make([]byte, 1024)
n, err := p.conn.Read(buf[0:])
errCheckWithPrint("Error >>> p.conn.Read err:%v\n", err)
if err != nil {
return
}
// get data bytes
b := buf[0:n]
//check Methods
if !p.isMethodsOk(b) {
log.Printf("WARN >>> from %s request methods invalid.\n", remoteAddrStr)
return
}
n, err = p.conn.Read(buf[0:])
errCheckWithPrint("Error >>> p.conn.Read err:%v\n", err)
if err != nil {
return
}
b = buf[0:n]
// check username/password
if !p.isAuthOk(b) {
log.Printf("WARN >>> from %s auth fail.\n", remoteAddrStr)
return
}
// resolve proxy CMD(tcp or udp)
/*
+----+-----+-------+------+----------+--------+
|VER | CMD | RSV | ATYP | DST.ADDR | DST.PORT |
+----+-----+-------+------+----------+--------+
| 1 | 1 |X’00’| 1 | Variable | 2 |
+----+-----+-------+------+----------+--------+
*/
n, err = p.conn.Read(buf[0:])
errCheckWithPrint("Error >>> p.conn.Read err:%v\n", err)
if err != nil {
return
}
b = buf[0:n]
if !p.isCmdSupport(b[0:2]) {
return
}
if !p.isAtypSupport(b[3:4]) {
return
}
dstAddr, dstPort := p.getAddrPort(b[3:])
if dstAddr == "" {
log.Printf("WARN >>> get NULL dstAddr,return.\n")
return
}
switch b[1] {
case 0x01: //CONNECT -> TCP
p.tcpProxy(dstAddr, dstPort)
return
case 0x02:
log.Println("WARN >>> get BIND command, not support.")
case 0x03: //UDP
p.udpProxy(dstAddr, dstPort)
return
default:
return
}
}
func (p *proxy) isMethodsOk(b []byte) bool {
// username/password only.
/*
+----+----------+----------+
|VER | NMETHODS | METHODS |
+----+----------+----------+
| 1 | 1 | 1 to 255 |
+----+----------+----------+
*/
if b[0] != 0x05 || (b[1] == 0x01 && b[2] != 0x02) {
p.conn.Write([]byte{0x05, 0xff})
return false
}
p.conn.Write([]byte{0x05, 0x02})
return true
}
func (p *proxy) isAuthOk(b []byte) bool {
//0x01 | 用户名长度（1字节）| 用户名（长度根据用户名长度域指定） | 口令长度（1字节） | 口令（长度由口令长度域指定）
// b[0] some software use 0x01,but base protocal must use 0x05,so keeps it here.
b0 := b[0]
nameLens := int(b[1])
name := string(b[2 : 2+nameLens])
passLens := int(b[2+nameLens])
pass := string(b[2+nameLens+1 : 2+nameLens+1+passLens])
//auth lens
/*
if nameLens != 32 || passLens != 48 {
p.conn.Write([]byte{b0, 0xff})
return false
}
*/
// auth count
// test auth here.
if name != "abc" || pass != "123" {
p.conn.Write([]byte{b0, 0xff})
return false
}
p.conn.Write([]byte{b0, 0x00})
return true
}
func (p *proxy) isCmdSupport(b []byte) bool {
if b[0] != 0x05 {
p.conn.Write([]byte{0x05, 0x01})
return false
}
switch b[1] {
case 0x01: //CONNECT
return true
case 0x02: //BIND
//not support here.
p.conn.Write([]byte{0x05, 0x07})
return false
case 0x03: //UDP
return true
default:
p.conn.Write([]byte{0x05, 0x07})
return false
}
}
func (p *proxy) isAtypSupport(b []byte) bool {
switch b[0] {
case 0x01: //ipv4
return true
case 0x03: //domain
return true
case 0x04: //ipv6
p.conn.Write([]byte{0x05, 0x08})
return false
default:
p.conn.Write([]byte{0x05, 0x08})
return false
}
}
func (p *proxy) getAddrPort(b []byte) (string, int) {
switch b[0] {
case 0x01: //ipv4
addr := net.IPv4(b[1], b[2], b[3], b[4]).String()
port := int(b[5])*256 + int(b[6])
return addr, port
case 0x03: //domain
domainLens := int(b[1])
domain := string(b[2 : 2+domainLens])
port := int(b[2+domainLens])*256 + int(b[2+domainLens+1])
return domain, port
default:
return "", 0
}
}
func (p *proxy) tcpProxy(dstAddr string, dstPort int) {
addr := fmt.Sprintf("%s:%d", dstAddr, dstPort)
tcpAddr, err := net.ResolveTCPAddr("tcp", addr)
errCheckWithPrint("Error >>> net.ResolveTcpAddr err:%v\n", err)
if err != nil {
p.conn.Write([]byte{0x05, 0x03})
return
}
tcpConn, err := TcpDial(nil, tcpAddr, 60*time.Second)
format := fmt.Sprintf("Error >>> net.DialTCP %s err", addr)
errCheckWithPrint(format+":%v\n", err)
if err != nil {
p.conn.Write([]byte{0x05, 0x03})
return
}
defer tcpConn.Close()
time.Sleep(10 * 1e6)
p.conn.SetNoDelay(true)
tcpConn.SetNoDelay(true)
p.conn.Write([]byte{0x05, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00})
tcpConnId++
prefix := fmt.Sprintf("> tcp: %08x", tcpConnId)
closeSig := make(chan bool, 0)
go pipe("%s >>> %d bytes send\n", prefix, p.conn, tcpConn, closeSig)
go pipe("%s <<< %d bytes recieve\n", prefix, tcpConn, p.conn, closeSig)
<-closeSig
return
}
func (p *proxy) udpProxy(clientAddr string, clientPort int) {
//log.Printf("get client bind -> %s:%d\n", clientAddr, clientPort)
// get localIp from p.conn
localExitAddr, err := net.ResolveTCPAddr("tcp", p.conn.LocalAddr().String())
errCheckWithFatal("ResolveTCPAddr err:%v\n", err)
localExitIP := localExitAddr.IP.String()
service := fmt.Sprintf("%s:%d", localExitIP, 0)
udpAddr, err := net.ResolveUDPAddr("udp", service)
errCheckWithFatal("ResolveUDPAddr err:%v\n", err)
udpListener, err := net.ListenUDP("udp", udpAddr)
errCheckWithFatal("ListenUDP err:%v\n", err)
defer udpListener.Close()
//udpListener.SetPKTINFO()
bindUdpAddr, err := net.ResolveUDPAddr("udp", udpListener.LocalAddr().String())
errCheckWithFatal("ResolveUDPAddr err:%v\n", err)
bindPort := bindUdpAddr.Port
//版本 | 代理的应答 | 保留1字节 | 地址类型 | 代理服务器地址 | 绑定的代理端口
bindMsg := []byte{0x05, 0x00, 0x00, 0x01}
buffer := bytes.NewBuffer(bindMsg)
binary.Write(buffer, binary.BigEndian, localExitAddr.IP.To4())
binary.Write(buffer, binary.BigEndian, uint16(bindPort))
//log.Printf("Local udp BIND >>> %s:%d\n", localExitIP, bindPort)
//log.Printf("Send udp BIND Msg >>> %v\n", buffer.Bytes())
p.conn.Write(buffer.Bytes())
finish := make(chan bool, 0)
go udpKeepAlive(p.conn, finish)
go udpServ(udpListener, finish)
<-finish
return
}
func errCheckWithFatal(format string, err error) {
if err != nil {
log.Fatalf("Fatal >>>"+format, err)
}
return
}
func errCheckWithPrint(format string, err error) {
if err != nil {
log.Printf(format, err)
}
return
}
func TcpDial(localAddr, remoteAddr *net.TCPAddr, timeout time.Duration) (*net.TCPConn, error) {
returned := false
ticker := time.NewTicker(timeout)
defer ticker.Stop()
type rst struct {
tcn *net.TCPConn
error
}
rst_chan := make(chan *rst, 0)
go func() {
tcpConn, err := net.DialTCP("tcp", localAddr, remoteAddr)
if err != nil {
goto Finish
} else if returned {
tcpConn.Close()
return
}
Finish:
rst_chan <- &rst{tcn: tcpConn, error: err}
}()
select {
case <-ticker.C:
returned = true
return nil, errors.New("connect timeout")
case result := <-rst_chan:
if result.error != nil {
return nil, result.error
}
return result.tcn, nil
}
}
func pipe(format, prefix string, src, dst *net.TCPConn, closeSig chan bool) {
buf := make([]byte, 0xff)
for {
n, err := src.Read(buf[0:])
if err != nil {
closeSig <- true
return
}
b := buf[0:n]
_, err = dst.Write(b)
if err != nil {
closeSig <- true
return
}
//log.Printf(format, prefix, n)
}
}
func udpKeepAlive(tcpConn *net.TCPConn, finish chan<- bool) {
tcpConn.SetKeepAlive(true)
buf := make([]byte, 1024)
for {
_, err := tcpConn.Read(buf[0:])
if err != nil {
finish <- true
return
}
}
}
func udpServ(udpConn *net.UDPConn, finish chan<- bool) {
udpConnId++
udpServ := &uServ{
prefix: fmt.Sprintf("udp >>> #%08x", udpConnId),
sigQuit: make(chan bool, 0),
dstMap: make(map[string]string),
}
go udpServ.read(udpConn)
udpServ.monitor()
finish <- true
return
}
func (uS *uServ) monitor() {
for {
select {
case <-uS.sigQuit:
return
}
}
}
func (uS *uServ) read(udpConn *net.UDPConn) {
buf := make([]byte, 2048)
buf2 := make([]byte, 2048)
for {
n, udpAddr, err := udpConn.ReadFromUDP(buf[0:])
if err != nil {
//log.Printf("%s ReadFromUDP err:%v\n", uS.prefix, err)
uS.sigQuit <- true
return
}
if uS.clientUdpAddr == nil {
uS.clientUdpAddr = udpAddr
}
b := buf[0:n]
if udpAddr.IP.String() == uS.clientUdpAddr.IP.String() { // from client
/*
+----+------+------+----------+----------+----------+
|RSV | FRAG | ATYP | DST.ADDR | DST.PORT | DATA |
+----+------+------+----------+----------+----------+
| 2 | 1 | 1 | Variable | 2 | Variable |
+----+------+------+----------+----------+----------+
*/
if b[2] != 0x00 {
log.Printf("%s WARN: FRAG do not support.\n", uS.prefix)
continue
}
switch b[3] {
case 0x01: //ipv4
dstAddr := &net.UDPAddr{
IP: net.IPv4(b[4], b[5], b[6], b[7]),
Port: int(b[8])*256 + int(b[9]),
}
uS.Lock()
if _, exist := uS.dstMap[dstAddr.String()]; !exist {
uS.dstMap[dstAddr.String()] = string(b[0:10])
}
uS.Unlock()
udpConn.WriteToUDP(b[10:], dstAddr)
//log.Printf("%s b-> %v\n", uS.prefix, b)
//log.Printf("%s data-> %v\n", uS.prefix, b[10:])
case 0x03: //domain
domainLens := int(b[4])
domain := string(b[5 : 5+domainLens])
ipAddr, err := net.ResolveIPAddr("ip", domain)
if err != nil {
log.Printf("%s Error -> domain %s dns query err:%v\n", uS.prefix, domain, err)
continue
}
dstAddr := &net.UDPAddr{
IP: ipAddr.IP,
Port: int(b[5+domainLens])*256 + int(b[6+domainLens]),
}
uS.Lock()
if _, exist := uS.dstMap[dstAddr.String()]; !exist {
uS.dstMap[dstAddr.String()] = string(b[0 : 7+domainLens])
}
uS.Unlock()
udpConn.WriteToUDP(b[7+domainLens:], dstAddr)
//log.Printf("%s b-> %v\n", uS.prefix, b)
//log.Printf("%s data-> %v\n", uS.prefix, b[7+domainLens:])
default:
log.Printf("%s WARN: ATYP %v do not support.\n", uS.prefix, b[3])
continue
}
} else { // from dst Server
uS.RLock()
if v, exist := uS.dstMap[udpAddr.String()]; exist {
uS.RUnlock()
head := []byte(v)
headLens := len(head)
copy(buf2[0:], head[0:headLens])
copy(buf2[headLens:], b[0:])
sendData := buf2[0 : headLens+n]
udpConn.WriteToUDP(sendData, uS.clientUdpAddr)
//log.Printf("%s <<< head-> %v\n", uS.prefix, head)
//log.Printf("%s <<< b-> %v\n", uS.prefix, b)
//log.Printf("%s <<< data-> %v\n", uS.prefix, sendData)
} else {
fmt.Printf("%s WARN -> %s not in dstMap.\n", uS.prefix, udpAddr.String())
uS.RUnlock()
continue
}
}
}
uS.sigQuit <- true
return
}
```
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