main.go

package main

import (
	"context"
	"fmt"
	"github.com/DavidGamba/go-getoptions"
	"github.com/things-go/go-socks5"
	"golang.org/x/net/proxy"
	"io/ioutil"
	"log"
	"net"
	"os"
	"regexp"
	"strings"
)
var upStreamProxy string

func main() {
	var listenPort int
	var listenAddress string
	var blackListFileAddress string
	opt := getoptions.New()
	opt.Bool("help", false, opt.Alias("h", "?"))
	opt.IntVarOptional(&listenPort, "port", 51081,opt.Alias("p"),opt.Description("Listening Port"))
	opt.StringVarOptional(&listenAddress, "address", "127.0.0.1",opt.Alias("a"),opt.Description("Listening Address"))
	opt.StringVarOptional(&blackListFileAddress, "blacklist", "black_list",opt.Alias("b"),opt.Description("Blacklist File path"))
	opt.StringVarOptional(&upStreamProxy, "upstream", "",opt.Alias("u"),opt.Description("UpStream Socks5 Address (ex: 127.0.0.1:1080)"))
	_, err := opt.Parse(os.Args[1:])
	if opt.Called("help") {
		fmt.Fprintf(os.Stderr, opt.Help())
		os.Exit(1)
	}
	if err != nil {
		fmt.Fprintf(os.Stderr, "ERROR: %s\n\n", err)
		fmt.Fprintf(os.Stderr, opt.Help(getoptions.HelpSynopsis))
		os.Exit(1)
	}
	contentBytes, err := ioutil.ReadFile(blackListFileAddress)
	if err != nil {
		panic(err)
	}
	contentString := strings.ReplaceAll(string(contentBytes),"\r","")
	blackList := strings.Split(contentString ,"\n")
	var hostRegexes = make([]*regexp.Regexp,len(blackList))

	for i , host := range blackList {
		hostRegexes[i] , _ = regexp.Compile(host)
	}
	resolver := new(CustomResolver)
	resolver.blockList = hostRegexes
	var server *socks5.Server
	if upStreamProxy != "" {
		server = socks5.NewServer(
			socks5.WithLogger(socks5.NewLogger(log.New(os.Stdout, "socks5: ", log.LstdFlags))),
			socks5.WithResolver(resolver),
			socks5.WithDial(dialOut),
		)
	}else{
		server = socks5.NewServer(
			socks5.WithLogger(socks5.NewLogger(log.New(os.Stdout, "socks5: ", log.LstdFlags))),
			socks5.WithResolver(resolver),
		)
	}
	if err := server.ListenAndServe("tcp", fmt.Sprintf("%s:%d",listenAddress,listenPort)); err != nil {
		panic(err)
	}
}
func dialOut(ctx context.Context, network, addr string) (net.Conn, error) {
	conChan := make(chan net.Conn)
	errChan := make(chan error)
	go func() {
		dialer , err :=	proxy.SOCKS5(network,upStreamProxy,nil,proxy.Direct)
		if err != nil {
			errChan <- err
		}
		conn,err := dialer.Dial(network,addr)
		if err != nil {
			errChan <- err
		}
		conChan <- conn
	}()
	select {
	case err := <- errChan :
		return nil, err
	case conChan := <- conChan:
		return conChan,nil
	case <- ctx.Done():
		return nil,ctx.Err()
	}
}