emacs/lisp/gnus/plstore.el

381 lines
12 KiB
EmacsLisp

;;; plstore.el --- searchable, partially encrypted, persistent plist store -*- lexical-binding: t -*-
;; Copyright (C) 2011 Free Software Foundation, Inc.
;; Author: Daiki Ueno <ueno@unixuser.org>
;; Keywords: PGP, GnuPG
;; This file is part of GNU Emacs.
;; GNU Emacs is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.
;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;; GNU General Public License for more details.
;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
;;; Commentary
;; Creating:
;;
;; (setq store (plstore-open (expand-file-name "~/.emacs.d/auth.plist")))
;; (plstore-put store "foo" '(:host "foo.example.org" :port 80) nil)
;; (plstore-save store)
;; ;; :user property is secret
;; (plstore-put store "bar" '(:host "bar.example.org") '(:user "test"))
;; (plstore-put store "baz" '(:host "baz.example.org") '(:user "test"))
;; (plstore-save store) ;<= will ask passphrase via GPG
;; (plstore-close store)
;;
;; Searching:
;;
;; (setq store (plstore-open (expand-file-name "~/.emacs.d/auth.plist")))
;; (plstore-find store '(:host ("foo.example.org")))
;; (plstore-find store '(:host ("bar.example.org"))) ;<= will ask passphrase via GPG
;; (plstore-close store)
;;
;;; Code:
(require 'epg)
(defgroup plstore nil
"Searchable, partially encrypted, persistent plist store"
:version "24.1"
:group 'files)
(defcustom plstore-select-keys 'silent
"Control whether or not to pop up the key selection dialog.
If t, always asks user to select recipients.
If nil, query user only when `plstore-encrypt-to' is not set.
If neither t nor nil, doesn't ask user. In this case, symmetric
encryption is used."
:type '(choice (const :tag "Ask always" t)
(const :tag "Ask when recipients are not set" nil)
(const :tag "Don't ask" silent))
:group 'plstore)
(defvar plstore-encrypt-to nil
"*Recipient(s) used for encrypting secret entries.
May either be a string or a list of strings.")
(put 'plstore-encrypt-to 'safe-local-variable
(lambda (val)
(or (stringp val)
(and (listp val)
(catch 'safe
(mapc (lambda (elt)
(unless (stringp elt)
(throw 'safe nil)))
val)
t)))))
(put 'plstore-encrypt-to 'permanent-local t)
(defvar plstore-cache-passphrase-for-symmetric-encryption nil)
(defvar plstore-passphrase-alist nil)
(defun plstore-passphrase-callback-function (_context _key-id plstore)
(if plstore-cache-passphrase-for-symmetric-encryption
(let* ((file (file-truename (plstore--get-buffer plstore)))
(entry (assoc file plstore-passphrase-alist))
passphrase)
(or (copy-sequence (cdr entry))
(progn
(unless entry
(setq entry (list file)
plstore-passphrase-alist
(cons entry
plstore-passphrase-alist)))
(setq passphrase
(read-passwd (format "Passphrase for PLSTORE %s: "
(plstore--get-buffer plstore))))
(setcdr entry (copy-sequence passphrase))
passphrase)))
(read-passwd (format "Passphrase for PLSTORE %s: "
(plstore--get-buffer plstore)))))
(defun plstore-progress-callback-function (_context _what _char current total
handback)
(if (= current total)
(message "%s...done" handback)
(message "%s...%d%%" handback
(if (> total 0) (floor (* (/ current (float total)) 100)) 0))))
(defun plstore--get-buffer (this)
(aref this 0))
(defun plstore--get-alist (this)
(aref this 1))
(defun plstore--get-encrypted-data (this)
(aref this 2))
(defun plstore--get-secret-alist (this)
(aref this 3))
(defun plstore--get-merged-alist (this)
(aref this 4))
(defun plstore--set-file (this file)
(aset this 0 file))
(defun plstore--set-alist (this plist)
(aset this 1 plist))
(defun plstore--set-encrypted-data (this encrypted-data)
(aset this 2 encrypted-data))
(defun plstore--set-secret-alist (this secret-alist)
(aset this 3 secret-alist))
(defun plstore--set-merged-alist (this merged-alist)
(aset this 4 merged-alist))
(defun plstore-get-file (this)
(buffer-file-name (plstore--get-buffer this)))
(defun plstore--init-from-buffer (plstore)
(goto-char (point-min))
(when (looking-at ";;; public entries")
(forward-line)
(plstore--set-alist plstore (read (point-marker)))
(forward-sexp)
(forward-char)
(when (looking-at ";;; secret entries")
(forward-line)
(plstore--set-encrypted-data plstore (read (point-marker))))
(plstore--merge-secret plstore)))
;;;###autoload
(defun plstore-open (file)
"Create a plstore instance associated with FILE."
(with-current-buffer (find-file-noselect file)
;; make the buffer invisible from user
(rename-buffer (format " plstore %s" (buffer-file-name)))
(let ((store (vector
(current-buffer)
nil ;plist (plist)
nil ;encrypted data (string)
nil ;secret plist (plist)
nil ;merged plist (plist)
)))
(plstore--init-from-buffer store)
store)))
(defun plstore-revert (plstore)
"Replace current data in PLSTORE with the file on disk."
(with-current-buffer (plstore--get-buffer plstore)
(revert-buffer t t)
(plstore--init-from-buffer plstore)))
(defun plstore-close (plstore)
"Destroy a plstore instance PLSTORE."
(kill-buffer (plstore--get-buffer plstore)))
(defun plstore--merge-secret (plstore)
(let ((alist (plstore--get-secret-alist plstore))
modified-alist
modified-plist
modified-entry
entry
plist
placeholder)
(plstore--set-merged-alist
plstore
(copy-tree (plstore--get-alist plstore)))
(setq modified-alist (plstore--get-merged-alist plstore))
(while alist
(setq entry (car alist)
alist (cdr alist)
plist (cdr entry)
modified-entry (assoc (car entry) modified-alist)
modified-plist (cdr modified-entry))
(while plist
(setq placeholder
(plist-member
modified-plist
(intern (concat ":secret-"
(substring (symbol-name (car plist)) 1)))))
(if placeholder
(setcar placeholder (car plist)))
(setq modified-plist
(plist-put modified-plist (car plist) (car (cdr plist))))
(setq plist (nthcdr 2 plist)))
(setcdr modified-entry modified-plist))))
(defun plstore--decrypt (plstore)
(if (plstore--get-encrypted-data plstore)
(let ((context (epg-make-context 'OpenPGP))
plain)
(epg-context-set-passphrase-callback
context
(cons #'plstore-passphrase-callback-function
plstore))
(epg-context-set-progress-callback
context
(cons #'plstore-progress-callback-function
(format "Decrypting %s" (plstore-get-file plstore))))
(setq plain
(epg-decrypt-string context
(plstore--get-encrypted-data plstore)))
(plstore--set-secret-alist plstore (car (read-from-string plain)))
(plstore--merge-secret plstore)
(plstore--set-encrypted-data plstore nil))))
(defun plstore--match (entry keys skip-if-secret-found)
(let ((result t) key-name key-value prop-value secret-name)
(while keys
(setq key-name (car keys)
key-value (car (cdr keys))
prop-value (plist-get (cdr entry) key-name))
(unless (member prop-value key-value)
(if skip-if-secret-found
(progn
(setq secret-name
(intern (concat ":secret-"
(substring (symbol-name key-name) 1))))
(if (plist-member (cdr entry) secret-name)
(setq result 'secret)
(setq result nil
keys nil)))
(setq result nil
keys nil)))
(setq keys (nthcdr 2 keys)))
result))
(defun plstore-find (plstore keys)
"Perform search on PLSTORE with KEYS.
KEYS is a plist."
(let (entries alist entry match decrypt plist)
;; First, go through the merged plist alist and collect entries
;; matched with keys.
(setq alist (plstore--get-merged-alist plstore))
(while alist
(setq entry (car alist)
alist (cdr alist)
match (plstore--match entry keys t))
(if (eq match 'secret)
(setq decrypt t)
(when match
(setq plist (cdr entry))
(while plist
(if (string-match "\\`:secret-" (symbol-name (car plist)))
(setq decrypt t
plist nil))
(setq plist (nthcdr 2 plist)))
(setq entries (cons entry entries)))))
;; Second, decrypt the encrypted plist and try again.
(when decrypt
(setq entries nil)
(plstore--decrypt plstore)
(setq alist (plstore--get-merged-alist plstore))
(while alist
(setq entry (car alist)
alist (cdr alist)
match (plstore--match entry keys nil))
(if match
(setq entries (cons entry entries)))))
(nreverse entries)))
(defun plstore-get (plstore name)
"Get an entry with NAME in PLSTORE."
(let ((entry (assoc name (plstore--get-merged-alist plstore)))
plist)
(setq plist (cdr entry))
(while plist
(if (string-match "\\`:secret-" (symbol-name (car plist)))
(progn
(plstore--decrypt plstore)
(setq entry (assoc name (plstore--get-merged-alist plstore))
plist nil))
(setq plist (nthcdr 2 plist))))
entry))
(defun plstore-put (plstore name keys secret-keys)
"Put an entry with NAME in PLSTORE.
KEYS is a plist containing non-secret data.
SECRET-KEYS is a plist containing secret data."
(let (entry
plist
secret-plist
symbol)
(if secret-keys
(plstore--decrypt plstore))
(while secret-keys
(setq symbol
(intern (concat ":secret-"
(substring (symbol-name (car secret-keys)) 1))))
(setq plist (plist-put plist symbol t)
secret-plist (plist-put secret-plist
(car secret-keys) (car (cdr secret-keys)))
secret-keys (nthcdr 2 secret-keys)))
(while keys
(setq symbol
(intern (concat ":secret-"
(substring (symbol-name (car keys)) 1))))
(setq plist (plist-put plist (car keys) (car (cdr keys)))
keys (nthcdr 2 keys)))
(setq entry (assoc name (plstore--get-alist plstore)))
(if entry
(setcdr entry plist)
(plstore--set-alist
plstore
(cons (cons name plist) (plstore--get-alist plstore))))
(when secret-plist
(setq entry (assoc name (plstore--get-secret-alist plstore)))
(if entry
(setcdr entry secret-plist)
(plstore--set-secret-alist
plstore
(cons (cons name secret-plist) (plstore--get-secret-alist plstore)))))
(plstore--merge-secret plstore)))
(defvar pp-escape-newlines)
(defun plstore-save (plstore)
"Save the contents of PLSTORE associated with a FILE."
(with-current-buffer (plstore--get-buffer plstore)
(erase-buffer)
(insert ";;; public entries -*- mode: emacs-lisp -*- \n"
(pp-to-string (plstore--get-alist plstore)))
(if (plstore--get-secret-alist plstore)
(let ((context (epg-make-context 'OpenPGP))
(pp-escape-newlines nil)
(recipients
(cond
((listp plstore-encrypt-to) plstore-encrypt-to)
((stringp plstore-encrypt-to) (list plstore-encrypt-to))))
cipher)
(epg-context-set-armor context t)
(epg-context-set-passphrase-callback
context
(cons #'plstore-passphrase-callback-function
plstore))
(setq cipher (epg-encrypt-string
context
(pp-to-string
(plstore--get-secret-alist plstore))
(if (or (eq plstore-select-keys t)
(and (null plstore-select-keys)
(not (local-variable-p 'plstore-encrypt-to
(current-buffer)))))
(epa-select-keys
context
"Select recipents for encryption.
If no one is selected, symmetric encryption will be performed. "
recipients)
(if plstore-encrypt-to
(epg-list-keys context recipients)))))
(goto-char (point-max))
(insert ";;; secret entries\n" (pp-to-string cipher))))
(save-buffer)))
(provide 'plstore)
;;; plstore.el ends here