@@ -0,0 +1,145 @@
package main
import (
"encoding/binary"
"errors"
"fmt"
"io"
"net"
)
func main () {
server , err := net .Listen ("tcp" , ":1080" )
if err != nil {
fmt .Printf ("Listen failed: %v\n " , err )
return
}
for {
client , err := server .Accept ()
if err != nil {
fmt .Printf ("Accept failed: %v" , err )
continue
}
go process (client )
}
}
func process (client net.Conn ) {
if err := Socks5Auth (client ); err != nil {
fmt .Println ("auth error:" , err )
client .Close ()
return
}
target , err := Socks5Connect (client )
if err != nil {
fmt .Println ("connect error:" , err )
client .Close ()
return
}
Socks5Forward (client , target )
}
func Socks5Auth (client net.Conn ) (err error ) {
buf := make ([]byte , 256 )
// 读取 VER 和 NMETHODS
n , err := io .ReadFull (client , buf [:2 ])
if n != 2 {
return errors .New ("reading header: " + err .Error ())
}
ver , nMethods := int (buf [0 ]), int (buf [1 ])
if ver != 5 {
return errors .New ("invalid version" )
}
// 读取 METHODS 列表
n , err = io .ReadFull (client , buf [:nMethods ])
if n != nMethods {
return errors .New ("reading methods: " + err .Error ())
}
//无需认证
n , err = client .Write ([]byte {0x05 , 0x00 })
if n != 2 || err != nil {
return errors .New ("write rsp: " + err .Error ())
}
return nil
}
func Socks5Connect (client net.Conn ) (net.Conn , error ) {
buf := make ([]byte , 256 )
n , err := io .ReadFull (client , buf [:4 ])
if n != 4 {
return nil , errors .New ("read header: " + err .Error ())
}
ver , cmd , _ , atyp := buf [0 ], buf [1 ], buf [2 ], buf [3 ]
if ver != 5 || cmd != 1 {
return nil , errors .New ("invalid ver/cmd" )
}
addr := ""
switch atyp {
case 1 :
n , err = io .ReadFull (client , buf [:4 ])
if n != 4 {
return nil , errors .New ("invalid IPv4: " + err .Error ())
}
addr = fmt .Sprintf ("%d.%d.%d.%d" , buf [0 ], buf [1 ], buf [2 ], buf [3 ])
case 3 :
n , err = io .ReadFull (client , buf [:1 ])
if n != 1 {
return nil , errors .New ("invalid hostname: " + err .Error ())
}
addrLen := int (buf [0 ])
n , err = io .ReadFull (client , buf [:addrLen ])
if n != addrLen {
return nil , errors .New ("invalid hostname: " + err .Error ())
}
addr = string (buf [:addrLen ])
case 4 :
return nil , errors .New ("IPv6: no supported yet" )
default :
return nil , errors .New ("invalid atyp" )
}
n , err = io .ReadFull (client , buf [:2 ])
if n != 2 {
return nil , errors .New ("read port: " + err .Error ())
}
port := binary .BigEndian .Uint16 (buf [:2 ])
destAddrPort := fmt .Sprintf ("%s:%d" , addr , port )
dest , err := net .Dial ("tcp" , destAddrPort )
if err != nil {
return nil , errors .New ("dial dst: " + err .Error ())
}
n , err = client .Write ([]byte {0x05 , 0x00 , 0x00 , 0x01 , 0 , 0 , 0 , 0 , 0 , 0 })
if err != nil {
dest .Close ()
return nil , errors .New ("write rsp: " + err .Error ())
}
return dest , nil
}
func Socks5Forward (client , target net.Conn ) {
forward := func (src , dest net.Conn ) {
defer src .Close ()
defer dest .Close ()
io .Copy (src , dest )
}
go forward (client , target )
go forward (target , client )
}
felix021 revised this gist