getpasswd functionality in Go?

Question

Situation:

I want to get a password entry from the stdin console - without echoing what the user types. Is there something com

Answer 1

The following is one of best ways to get it done. First get terminal package by go get golang.org/x/crypto/ssh

package main

import (
    "bufio"
    "fmt"
    "os"
    "strings"
    "syscall"

    "golang.org/x/crypto/ssh/terminal"
)

func main() {
    username, password, _ := credentials()
    fmt.Printf("Username: %s, Password: %s\n", username, password)
}

func credentials() (string, string, error) {
    reader := bufio.NewReader(os.Stdin)

    fmt.Print("Enter Username: ")
    username, err := reader.ReadString('\n')
    if err != nil {
        return "", "", err
    }

    fmt.Print("Enter Password: ")
    bytePassword, err := terminal.ReadPassword(int(syscall.Stdin))
    if err != nil {
        return "", "", err
    }

    password := string(bytePassword)
    return strings.TrimSpace(username), strings.TrimSpace(password), nil
}

http://play.golang.org/p/l-9IP1mrhA

Answer 2

You could also use PasswordPrompt function of https://github.com/peterh/liner package.

Answer 3

Here is a version specific to Linux:

func terminalEcho(show bool) {
    // Enable or disable echoing terminal input. This is useful specifically for
    // when users enter passwords.
    // calling terminalEcho(true) turns on echoing (normal mode)
    // calling terminalEcho(false) hides terminal input.
    var termios = &syscall.Termios{}
    var fd = os.Stdout.Fd()

    if _, _, err := syscall.Syscall(syscall.SYS_IOCTL, fd,
        syscall.TCGETS, uintptr(unsafe.Pointer(termios))); err != 0 {
        return
    }

    if show {
        termios.Lflag |= syscall.ECHO
    } else {
        termios.Lflag &^= syscall.ECHO
    }

    if _, _, err := syscall.Syscall(syscall.SYS_IOCTL, fd,
        uintptr(syscall.TCSETS),
        uintptr(unsafe.Pointer(termios))); err != 0 {
        return
    }
}

So to use it:

fmt.Print("password: ")

terminalEcho(false)
var pw string
fmt.Scanln(&pw)
terminalEcho(true)
fmt.Println("")

It's the TCGETS syscall that is linux specific. There are different syscall values for OSX and Windows.

Answer 4

Required launching stty via Go ForkExec() function:

package main

import (
    os      "os"
    bufio   "bufio"
    fmt     "fmt"
    str     "strings"
)

func main() {
    fmt.Println();
    if passwd, err := Getpasswd("Enter password: "); err == nil {
        fmt.Printf("\n\nPassword: '%s'\n",passwd)
    }
}

func Getpasswd(prompt string) (passwd string, err os.Error) {
    fmt.Print(prompt);
    const stty_arg0  = "/bin/stty";
    stty_argv_e_off := []string{"stty","-echo"};
    stty_argv_e_on  := []string{"stty","echo"};
    const exec_cwdir = "";
    fd := []*os.File{os.Stdin,os.Stdout,os.Stderr};
    pid, err := os.ForkExec(stty_arg0,stty_argv_e_off,nil,exec_cwdir,fd);
    if err != nil {
        return passwd, os.NewError(fmt.Sprintf("Failed turning off console echo for password entry:\n\t%s",err))
    }
    rd := bufio.NewReader(os.Stdin);
    os.Wait(pid,0);
    line, err := rd.ReadString('\n');
    if err == nil {
        passwd = str.TrimSpace(line)
    } else {
        err = os.NewError(fmt.Sprintf("Failed during password entry: %s",err))
    }
    pid, e := os.ForkExec(stty_arg0,stty_argv_e_on,nil,exec_cwdir,fd);
    if e == nil {
        os.Wait(pid,0)
    } else if err == nil {
        err = os.NewError(fmt.Sprintf("Failed turning on console echo post password entry:\n\t%s",e))
    }
    return passwd, err
}

Answer 5

Just saw a mail in #go-nuts maillist. There is someone who wrote quite a simple go package to be used. You can find it here: https://github.com/howeyc/gopass

It something like that:

package main

import "fmt"
import "github.com/howeyc/gopass"

func main() {
    fmt.Printf("Password: ")
    pass := gopass.GetPasswd()
    // Do something with pass
}

Answer 6

Here is a solution that I developed using Go1.6.2 that you might find useful.

It only uses the following standard packages: bufio, fmt, os, strings and syscall. More specifically, it uses syscall.ForkExec() and syscall.Wait4() to invoke stty to disable/enable terminal echo.

I have tested it on Linux and BSD (Mac). It will not work on windows.

// getPassword - Prompt for password. Use stty to disable echoing.
import ( "bufio"; "fmt"; "os"; "strings"; "syscall" )
func getPassword(prompt string) string {
    fmt.Print(prompt)

    // Common settings and variables for both stty calls.
    attrs := syscall.ProcAttr{
        Dir:   "",
        Env:   []string{},
        Files: []uintptr{os.Stdin.Fd(), os.Stdout.Fd(), os.Stderr.Fd()},
        Sys:   nil}
    var ws syscall.WaitStatus

    // Disable echoing.
    pid, err := syscall.ForkExec(
        "/bin/stty",
        []string{"stty", "-echo"},
        &attrs)
    if err != nil {
        panic(err)
    }

    // Wait for the stty process to complete.
    _, err = syscall.Wait4(pid, &ws, 0, nil)
    if err != nil {
        panic(err)
    }

    // Echo is disabled, now grab the data.
    reader := bufio.NewReader(os.Stdin)
    text, err := reader.ReadString('\n')
    if err != nil {
        panic(err)
    }

    // Re-enable echo.
    pid, err = syscall.ForkExec(
        "/bin/stty",
        []string{"stty", "echo"},
        &attrs)
    if err != nil {
        panic(err)
    }

    // Wait for the stty process to complete.
    _, err = syscall.Wait4(pid, &ws, 0, nil)
    if err != nil {
        panic(err)
    }

    return strings.TrimSpace(text)
}