go socks5

pipe.go

package pipe

import (
    "fmt"
    "net"
)

func ConnPipe(c1 net.Conn, c2 net.Conn) {
    defer c1.Close()
    defer c2.Close()
    buf := make([]byte, 4096)
    for {
        len, err := c1.Read(buf)
        if err != nil {
            fmt.Println("pipe read", c1, ": ", err.Error())
            return
        }
        len2, err2 := c2.Write(buf[:len])
        if err2 != nil || len2 != len {
            fmt.Println("pipe write", c2, ": ", err2.Error())
            return
        }
    }
}

socks5.go

import (
	"flag"
	"fmt"
	"net"
	"os"
	"runtime"
	"socks5/utils/mock"
	"socks5/utils/pipe"
	"strconv"
)

func do_socks5(conn net.Conn) {
	buf := make([]byte, 512)
	len, err := conn.Read(buf)
	if err != nil {
		fmt.Println("conn read ", conn, ": ", err.Error())
		conn.Close()
		return
	}
	if 1+1+int(buf[1]) != len || int8(buf[0]) != '\x05' {
		fmt.Println("invalid proto debug", int(buf[0]))
		conn.Close()
		return
	}
	conn.Write([]byte("\x05\x00"))

	len, err = conn.Read(buf)
	if err != nil {
		fmt.Println("conn read ", conn, ": ", err.Error())
		conn.Close()
		return
	}
	if len <= 4 {
		fmt.Println("invalid proto")
		conn.Close()
		return
	}

	ver := int8(buf[0])
	cmd := int8(buf[1])
	atyp := int8(buf[3])

	if ver != '\x05' {
		fmt.Println("invalid proto")
		conn.Close()
		return
	}

	if cmd != 1 {
		fmt.Println("Command not supported")
		conn.Write([]byte("\x05\x07\x00\x01\x00\x00\x00\x00\x00\x00"))
		conn.Close()
		return
	}

	var dst_addr string
	var dst_port uint16
	switch atyp {
	case 1:
		if len != 10 {
			fmt.Println("invalid proto")
			conn.Close()
			return
		}
		dst_addr = net.IPv4(buf[4], buf[5], buf[6], buf[7]).String()
		dst_port = uint16(buf[8])<<8 + uint16(buf[9])
	case 3:
		addrlen := int(buf[4])
		offset := 4 + 1 + addrlen
		if offset+2 != len {
			fmt.Println("invalid proto")
			conn.Close()
			return
		}
		dst_addr = string(buf[5:offset])
		dst_port = uint16(buf[offset])<<8 + uint16(buf[offset+1])
	default:
		fmt.Println("Address type not supported", atyp)
		conn.Write([]byte("\x05\x08\x00\x01\x00\x00\x00\x00\x00\x00"))
		conn.Close()
		return
	}

	upAddr := dst_addr + ":" + strconv.Itoa(int(dst_port))
	fmt.Println(conn, upAddr)
	upConn, err := net.Dial("tcp", upAddr)
	if err != nil {
		fmt.Println("Upstream connect failed, ", upAddr)
		conn.Write([]byte("\x05\x01\x00\x01\x00\x00\x00\x00\x00\x00"))
		conn.Close()
		return
	}
	conn.Write([]byte("\x05\x00\x00\x01\x00\x00\x00\x00\x00\x00"))

	go pipe.ConnPipe(upConn, conn)
	pipe.ConnPipe(conn, upConn)
}

func main() {
	portPtr := flag.String("port", "12345", "listen port")
	wrapPtr := flag.Bool("wrap", false, "wrap toogle")
	cookie := flag.Int("cookie", 188, "cookie byte")
	flag.Parse()

	runtime.GOMAXPROCS(runtime.NumCPU())
	ssock, err := net.Listen("tcp", ":"+*portPtr)
	if err != nil {
		fmt.Println("listen", err.Error())
		os.Exit(1)
	}
	for {
		conn, err := ssock.Accept()
		if err != nil {
			fmt.Println("accept", err.Error())
			os.Exit(1)
		}
		if *wrapPtr {
			mock.SetCookie(byte(*cookie))
			go do_socks5(mock.Wrap(conn))
		} else {
			go do_socks5(conn)
		}
	}
}