Non-interactive Login with TOTP tokens

[lsg551]

Feature request

Description

If 2FA is enabled for a user account, a valid TOTP token is required. ivpn login currently only supports passing such a token interactively.

I would like to pass a token along the account ID non-interactivley. This is especially useful for scripting etc.

Implementation Details

As far as I can tell with my limited knowledge, doLogin(...) in cli/commands/account.go is the code to look for.

After session creation, if the condition resp.APIStatus == types.The2FARequired is true, it just prints to STDOUT and reads the token from STDIN, then retries creating the session with the provided token.

Describe the solution you'd like

Primarliy, a new optional flag -totp <string> could be added that accepts such a token and

1. uses the token if 2FA is required,
2. or drops it silently if not.

In addition, it should be checked whether os.STDIN is a TTY (fe. via cross-platform mattn/go-isatty).

If os.STDIN is not and the user also did not pass -totp, the CLI should exit with an error and only prompt interactively if os.STDIN is a TTY and the user did not pass -totp.

Describe alternatives you've considered

none