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| package main | |
| import ( | |
| "context" | |
| "fmt" | |
| "log" | |
| "net" | |
| "os" | |
| "strconv" | |
| "syscall" | |
| "github.com/spf13/pflag" | |
| "tailscale.com/net/socks5" | |
| ) | |
| var SEG_SIZE int | |
| func dial(ctx context.Context, network, addr string) (net.Conn, error) { | |
| // create a low level connection and set the TCP Max segment size | |
| fd, err := syscall.Socket(syscall.AF_INET, syscall.SOCK_STREAM, syscall.IPPROTO_TCP) | |
| if err != nil { | |
| return nil, err | |
| } | |
| err = syscall.SetsockoptInt(fd, syscall.IPPROTO_TCP, syscall.TCP_MAXSEG, SEG_SIZE) | |
| if err != nil { | |
| return nil, err | |
| } | |
| // get the new seg size and print | |
| // r, err := syscall.GetsockoptInt(fd, syscall.IPPROTO_TCP, syscall.TCP_MAXSEG) | |
| // if err != nil { | |
| // log.Println(err) | |
| // } else { | |
| // fmt.Println(r) | |
| // } | |
| // addr is in ip:port format, need to convert it back and extract port | |
| var ipBytes net.IP | |
| serverAddr, serverPortStr, err := net.SplitHostPort(addr) | |
| if err != nil { | |
| return nil, err | |
| } | |
| serverPort, _ := strconv.Atoi(serverPortStr) | |
| if ip := net.ParseIP(serverAddr); ip != nil { | |
| if ip.To4() != nil { | |
| ipBytes = ip.To4() | |
| } else { | |
| return nil, fmt.Errorf("ipv6 is not yet supported") | |
| } | |
| } else { | |
| return nil, fmt.Errorf("fqdn is not yet supported") | |
| } | |
| // connect to remote host | |
| sockAddr := syscall.SockaddrInet4{ | |
| Port: serverPort, | |
| Addr: [4]byte{ipBytes[0], ipBytes[1], ipBytes[2], ipBytes[3]}, | |
| } | |
| err = syscall.Connect(fd, &sockAddr) | |
| defer syscall.Close(fd) | |
| if err != nil { | |
| return nil, err | |
| } | |
| // convert the fd back to a connection | |
| f := os.NewFile(uintptr(fd), "") | |
| return net.FileConn(f) | |
| } | |
| func main() { | |
| listen := pflag.StringP("listen", "l", "127.0.0.1:1080", "Address to listen on") | |
| segmentSize := pflag.IntP("size", "s", 250, "Segment size") | |
| pflag.Parse() | |
| SEG_SIZE = *segmentSize | |
| l, err := net.Listen("tcp", *listen) | |
| if err != nil { | |
| log.Fatal(err) | |
| } | |
| mySocks := socks5.Server{ | |
| Dialer: dial, | |
| } | |
| log.Println("Started SOCKS on 1080") | |
| log.Fatal(mySocks.Serve(l)) | |
| } |
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