Privatae
67 lines
2.8 KiB
Go
67 lines
2.8 KiB
Go
package main
|
|
|
|
// pair_terminal.go: the one question `pair` asks a person, on a local machine
|
|
// that already serves a Host: whether to add another.
|
|
//
|
|
// A local bastion used to serve one Host, full stop, because on a single-user
|
|
// machine a second Host appearing meant someone else had got a token onto the
|
|
// box. A person who uses two Hosts (a Cloud machine beside the platform one)
|
|
// could not pair the second at all. Now the second is added when the person at
|
|
// this machine says so, and only then: the answer is read from the controlling
|
|
// terminal, never from standard input, so a token piped in by a script or an
|
|
// installer (which feeds the pairing code through standard input) cannot add a
|
|
// Host by itself. With no terminal there is nobody to ask, and the pair is
|
|
// refused.
|
|
|
|
import (
|
|
"bufio"
|
|
"errors"
|
|
"fmt"
|
|
"io"
|
|
"strconv"
|
|
"strings"
|
|
)
|
|
|
|
// errNoTerminal: this process has no controlling terminal to ask on.
|
|
var errNoTerminal = errors.New("no terminal")
|
|
|
|
// openTerminal opens the controlling terminal for one question: a reader for
|
|
// the answer, a writer for the question, and a close. A variable so a test can
|
|
// stand in a person; nothing else assigns it.
|
|
var openTerminal = openControllingTerminal
|
|
|
|
// terminalSafeName is a Host name as the question shows it. newHost is the
|
|
// handle the token carries, which nothing has checked yet: whoever made the
|
|
// token chose it, and a control character or an escape sequence in it could
|
|
// rewrite the question on the person's screen. A plain host name is shown as
|
|
// it is; anything else is quoted, every such byte escaped.
|
|
func terminalSafeName(name string) string {
|
|
if validHostName(name) {
|
|
return name
|
|
}
|
|
return strconv.QuoteToASCII(name)
|
|
}
|
|
|
|
// confirmAddHost asks whether to add newHost beside serving, the Host this
|
|
// local machine already serves. True only for a typed y or yes.
|
|
func confirmAddHost(serving, newHost string) (bool, error) {
|
|
in, out, closeTerm, err := openTerminal()
|
|
if err != nil {
|
|
return false, fmt.Errorf("this computer already serves your Host %s, and adding another needs a yes typed "+
|
|
"at this computer, but this run has no terminal to ask in. Run the same command in a terminal "+
|
|
"window on this computer; nothing was paired", serving)
|
|
}
|
|
defer closeTerm()
|
|
fmt.Fprintf(out, "This computer already serves your Host %s. Add %s as well? It gets a pairing of its own,\n"+
|
|
"and `privatae-bastion ui` shows what each Host may do here. [y/N] ", terminalSafeName(serving), terminalSafeName(newHost))
|
|
line, err := bufio.NewReader(io.LimitReader(in, 256)).ReadString('\n')
|
|
if err != nil && !errors.Is(err, io.EOF) {
|
|
return false, fmt.Errorf("could not read the answer (%v); nothing was paired", err)
|
|
}
|
|
switch strings.ToLower(strings.TrimSpace(line)) {
|
|
case "y", "yes":
|
|
return true, nil
|
|
}
|
|
return false, nil
|
|
}
|