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129 lines
4.1 KiB
EmacsLisp
129 lines
4.1 KiB
EmacsLisp
;;; password-cache.el --- Read passwords, possibly using a password cache. -*- lexical-binding: t -*-
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;; Copyright (C) 1999-2000, 2003-2022 Free Software Foundation, Inc.
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;; Author: Simon Josefsson <simon@josefsson.org>
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;; Created: 2003-12-21
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;; Keywords: extensions
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;; This file is part of GNU Emacs.
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;; GNU Emacs is free software: you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation, either version 3 of the License, or
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;; (at your option) any later version.
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;; GNU Emacs is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;; GNU General Public License for more details.
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;; You should have received a copy of the GNU General Public License
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;; along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>.
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;;; Commentary:
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;; Greatly influenced by pgg.el written by Daiki Ueno, with timer
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;; fixes for XEmacs by Katsumi Yamaoka. In fact, this is mostly just
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;; a rip-off.
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;;
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;; (password-read "Password? " "test")
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;; ;; Minibuffer prompt for password.
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;; => "foo"
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;;
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;; (password-cache-add "test" (read-passwd "Password? "))
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;; ;; Minibuffer prompt from read-passwd, which returns "foo".
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;; => nil
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;; (password-read "Password? " "test")
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;; ;; No minibuffer prompt
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;; => "foo"
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;;
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;; (password-read "Password? " "test")
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;; ;; No minibuffer prompt
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;; => "foo"
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;;
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;; ;; Wait `password-cache-expiry' seconds.
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;;
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;; (password-read "Password? " "test")
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;; ;; Minibuffer prompt for password is back.
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;; => "foo"
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;;; Code:
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;; Options are autoloaded since they are used by eg mml-sec.el.
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;;;###autoload
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(defcustom password-cache t
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"Whether to cache passwords."
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:group 'password
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:type 'boolean)
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;;;###autoload
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(defcustom password-cache-expiry 16
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"How many seconds passwords are cached, or nil to disable expiring.
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Whether passwords are cached at all is controlled by `password-cache'."
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:group 'password
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:type '(choice (const :tag "Never" nil)
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(integer :tag "Seconds")))
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(defvar password-data (make-hash-table :test #'equal))
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(defun password-read-from-cache (key)
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"Obtain passphrase for KEY from time-limited passphrase cache.
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Custom variables `password-cache' and `password-cache-expiry'
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regulate cache behavior."
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(and password-cache
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key
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(gethash key password-data)))
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;;;###autoload
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(defun password-in-cache-p (key)
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"Check if KEY is in the cache."
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(and password-cache
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key
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(not (eq (gethash key password-data 'password-cache-no-data)
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'password-cache-no-data))))
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(defun password-read (prompt &optional key)
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"Read password, for use with KEY, from user, or from cache if wanted.
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KEY indicate the purpose of the password, so the cache can
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separate passwords. The cache is not used if KEY is nil.
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KEY is typically a string but can be anything (compared via `equal').
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The variable `password-cache' control whether the cache is used."
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(or (password-read-from-cache key)
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(read-passwd prompt)))
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(defun password-cache-remove (key)
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"Remove password indexed by KEY from password cache.
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This is typically run by a timer setup from `password-cache-add',
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but can be invoked at any time to forcefully remove passwords
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from the cache. This may be useful when it has been detected
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that a password is invalid, so that `password-read' query the
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user again."
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(let ((password (gethash key password-data)))
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(when (stringp password)
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(clear-string password))
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(remhash key password-data)))
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(defun password-cache-add (key password)
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"Add password to cache.
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The password is removed by a timer after `password-cache-expiry' seconds."
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(when (and password-cache-expiry
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(eq (gethash key password-data 'password-cache-no-data)
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'password-cache-no-data))
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(run-at-time password-cache-expiry nil
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#'password-cache-remove
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key))
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(puthash key password password-data)
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nil)
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(defun password-reset ()
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"Clear the password cache."
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(interactive)
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(clrhash password-data))
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(provide 'password-cache)
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;;; password-cache.el ends here
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