age/cmd/age/encrypted_keys.go
Filippo Valsorda fa5b575ceb cmd/age: use CONIN$/CONOUT$ on Windows for password prompts
Fixes #128
Closes #274

Co-authored-by: codesoap <codesoap@mailbox.org>
2021-06-02 11:04:02 +02:00

85 lines
2.5 KiB
Go

// Copyright 2019 Google LLC
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file or at
// https://developers.google.com/open-source/licenses/bsd
package main
import (
"errors"
"fmt"
"os"
"runtime"
"filippo.io/age"
"golang.org/x/term"
)
type LazyScryptIdentity struct {
Passphrase func() (string, error)
}
var _ age.Identity = &LazyScryptIdentity{}
func (i *LazyScryptIdentity) Unwrap(stanzas []*age.Stanza) (fileKey []byte, err error) {
if len(stanzas) != 1 || stanzas[0].Type != "scrypt" {
return nil, age.ErrIncorrectIdentity
}
pass, err := i.Passphrase()
if err != nil {
return nil, fmt.Errorf("could not read passphrase: %v", err)
}
ii, err := age.NewScryptIdentity(pass)
if err != nil {
return nil, err
}
fileKey, err = ii.Unwrap(stanzas)
if errors.Is(err, age.ErrIncorrectIdentity) {
// ScryptIdentity returns ErrIncorrectIdentity for an incorrect
// passphrase, which would lead Decrypt to returning "no identity
// matched any recipient". That makes sense in the API, where there
// might be multiple configured ScryptIdentity. Since in cmd/age there
// can be only one, return a better error message.
return nil, fmt.Errorf("incorrect passphrase")
}
return fileKey, err
}
// readPassphrase reads a passphrase from the terminal. It does not read from a
// non-terminal stdin, so it does not check stdinInUse.
func readPassphrase(prompt string) ([]byte, error) {
var in, out *os.File
if runtime.GOOS == "windows" {
var err error
in, err = os.OpenFile("CONIN$", os.O_RDWR, 0)
if err != nil {
return nil, err
}
defer in.Close()
out, err = os.OpenFile("CONOUT$", os.O_WRONLY, 0)
if err != nil {
return nil, err
}
defer out.Close()
} else if _, err := os.Stat("/dev/tty"); err == nil {
tty, err := os.OpenFile("/dev/tty", os.O_RDWR, 0)
if err != nil {
return nil, err
}
defer tty.Close()
in, out = tty, tty
} else {
if !term.IsTerminal(int(os.Stdin.Fd())) {
return nil, fmt.Errorf("standard input is not a terminal, and /dev/tty is not available: %v", err)
}
in, out = os.Stdin, os.Stderr
}
fmt.Fprintf(out, "%s ", prompt)
// Use CRLF to work around an apparent bug in WSL2's handling of CONOUT$.
// Only when running a Windows binary from WSL2, the cursor would not go
// back to the start of the line with a simple LF. Honestly, it's impressive
// CONIN$ and CONOUT$ even work at all inside WSL2.
defer fmt.Fprintf(out, "\r\n")
return term.ReadPassword(int(in.Fd()))
}