gosocks5/server/selector.go

package server

import (
	"net"
	"net/url"

	"github.com/ginuerzh/gosocks5"
)

type serverSelector struct {
	methods []uint8
	Users   []*url.Userinfo
}

func (selector *serverSelector) Methods() []uint8 {
	return selector.methods
}

func (selector *serverSelector) AddMethod(methods ...uint8) {
	selector.methods = append(selector.methods, methods...)
}

func (selector *serverSelector) Select(methods ...uint8) (method uint8) {
	method = gosocks5.MethodNoAuth

	// when user/pass is set, auth is mandatory
	if len(selector.Users) > 0 {
		method = gosocks5.MethodUserPass
	}

	return
}

func (selector *serverSelector) OnSelected(method uint8, conn net.Conn) (net.Conn, error) {
	switch method {
	case gosocks5.MethodUserPass:
		req, err := gosocks5.ReadUserPassRequest(conn)
		if err != nil {
			return nil, err
		}

		valid := false
		for _, user := range selector.Users {
			username := user.Username()
			password, _ := user.Password()
			if (req.Username == username && req.Password == password) ||
				(req.Username == username && password == "") ||
				(username == "" && req.Password == password) {
				valid = true
				break
			}
		}
		if len(selector.Users) > 0 && !valid {
			resp := gosocks5.NewUserPassResponse(gosocks5.UserPassVer, gosocks5.Failure)
			if err := resp.Write(conn); err != nil {
				return nil, err
			}
			return nil, gosocks5.ErrAuthFailure
		}

		resp := gosocks5.NewUserPassResponse(gosocks5.UserPassVer, gosocks5.Succeeded)
		if err := resp.Write(conn); err != nil {
			return nil, err
		}
	case gosocks5.MethodNoAcceptable:
		return nil, gosocks5.ErrBadMethod
	}

	return conn, nil
}