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emacs/lisp/net/pinentry.el
Paul Eggert 5badc81c1c Update copyright year to 2017 
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2016-12-31 19:42:26 -08:00

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;;; pinentry.el --- GnuPG Pinentry server implementation -*- lexical-binding: t -*-
;; Copyright (C) 2015-2017 Free Software Foundation, Inc.
;; Author: Daiki Ueno <ueno@gnu.org>
;; Version: 0.1
;; Keywords: 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:
;; This package allows GnuPG passphrase to be prompted through the
;; minibuffer instead of graphical dialog.
;;
;; To use, add "allow-emacs-pinentry" to "~/.gnupg/gpg-agent.conf",
;; reload the configuration with "gpgconf --reload gpg-agent", and
;; start the server with M-x pinentry-start.
;;
;; The actual communication path between the relevant components is
;; as follows:
;;
;; gpg --> gpg-agent --> pinentry --> Emacs
;;
;; where pinentry and Emacs communicate through a Unix domain socket
;; created at:
;;
;; ${TMPDIR-/tmp}/emacs$(id -u)/pinentry
;;
;; under the same directory which server.el uses. The protocol is a
;; subset of the Pinentry Assuan protocol described in (info
;; "(pinentry) Protocol").
;;
;; NOTE: As of August 2015, this feature requires newer versions of
;; GnuPG (2.1.5+) and Pinentry (0.9.5+).
;;; Code:
(eval-when-compile (require 'cl-lib))
(defgroup pinentry nil
"The Pinentry server"
:version "25.1"
:group 'external)
(defcustom pinentry-popup-prompt-window t
"If non-nil, display multiline prompt in another window."
:type 'boolean
:group 'pinentry)
(defcustom pinentry-prompt-window-height 5
"Number of lines used to display multiline prompt."
:type 'integer
:group 'pinentry)
(defvar pinentry-debug nil)
(defvar pinentry-debug-buffer nil)
(defvar pinentry--server-process nil)
(defvar pinentry--connection-process-list nil)
(defvar pinentry--labels nil)
(put 'pinentry-read-point 'permanent-local t)
(defvar pinentry--read-point nil)
(put 'pinentry--read-point 'permanent-local t)
(defvar pinentry--prompt-buffer nil)
;; We use the same location as `server-socket-dir', when local sockets
;; are supported.
(defvar pinentry--socket-dir
(format "%s/emacs%d" (or (getenv "TMPDIR") "/tmp") (user-uid))
"The directory in which to place the server socket.
If local sockets are not supported, this is nil.")
(defconst pinentry--set-label-commands
'("SETPROMPT" "SETTITLE" "SETDESC"
"SETREPEAT" "SETREPEATERROR"
"SETOK" "SETCANCEL" "SETNOTOK"))
;; These error codes are defined in libgpg-error/src/err-codes.h.in.
(defmacro pinentry--error-code (code)
(logior (lsh 5 24) code))
(defconst pinentry--error-not-implemented
(cons (pinentry--error-code 69) "not implemented"))
(defconst pinentry--error-cancelled
(cons (pinentry--error-code 99) "cancelled"))
(defconst pinentry--error-not-confirmed
(cons (pinentry--error-code 114) "not confirmed"))
(autoload 'server-ensure-safe-dir "server")
(defvar pinentry-prompt-mode-map
(let ((keymap (make-sparse-keymap)))
(define-key keymap "q" 'quit-window)
keymap))
(define-derived-mode pinentry-prompt-mode special-mode "Pinentry"
"Major mode for `pinentry--prompt-buffer'."
(buffer-disable-undo)
(setq truncate-lines t
buffer-read-only t))
(defun pinentry--prompt (labels query-function &rest query-args)
(let ((desc (cdr (assq 'desc labels)))
(error (cdr (assq 'error labels)))
(prompt (cdr (assq 'prompt labels))))
(when (string-match "[ \n]*\\'" prompt)
(setq prompt (concat
(substring
prompt 0 (match-beginning 0)) " ")))
(when error
(setq desc (concat "Error: " (propertize error 'face 'error)
"\n" desc)))
(if (and desc pinentry-popup-prompt-window)
(save-window-excursion
(delete-other-windows)
(unless (and pinentry--prompt-buffer
(buffer-live-p pinentry--prompt-buffer))
(setq pinentry--prompt-buffer (generate-new-buffer "*Pinentry*")))
(if (get-buffer-window pinentry--prompt-buffer)
(delete-window (get-buffer-window pinentry--prompt-buffer)))
(with-current-buffer pinentry--prompt-buffer
(let ((inhibit-read-only t)
buffer-read-only)
(erase-buffer)
(insert desc))
(pinentry-prompt-mode)
(goto-char (point-min)))
(if (> (window-height)
pinentry-prompt-window-height)
(set-window-buffer (split-window nil
(- (window-height)
pinentry-prompt-window-height))
pinentry--prompt-buffer)
(pop-to-buffer pinentry--prompt-buffer)
(if (> (window-height) pinentry-prompt-window-height)
(shrink-window (- (window-height)
pinentry-prompt-window-height))))
(prog1 (apply query-function prompt query-args)
(quit-window)))
(apply query-function (concat desc "\n" prompt) query-args))))
;;;###autoload
(defun pinentry-start (&optional quiet)
"Start a Pinentry service.
Once the environment is properly set, subsequent invocations of
the gpg command will interact with Emacs for passphrase input.
If the optional QUIET argument is non-nil, messages at startup
will not be shown."
(interactive)
(unless (featurep 'make-network-process '(:family local))
(error "local sockets are not supported"))
(if (process-live-p pinentry--server-process)
(unless quiet
(message "Pinentry service is already running"))
(let* ((server-file (expand-file-name "pinentry" pinentry--socket-dir)))
(server-ensure-safe-dir pinentry--socket-dir)
;; Delete the socket files made by previous server invocations.
(ignore-errors
(let (delete-by-moving-to-trash)
(delete-file server-file)))
(cl-letf (((default-file-modes) ?\700))
(setq pinentry--server-process
(make-network-process
:name "pinentry"
:server t
:noquery t
:sentinel #'pinentry--process-sentinel
:filter #'pinentry--process-filter
:coding 'no-conversion
:family 'local
:service server-file))
(process-put pinentry--server-process :server-file server-file)))))
(defun pinentry-stop ()
"Stop a Pinentry service."
(interactive)
(when (process-live-p pinentry--server-process)
(delete-process pinentry--server-process))
(setq pinentry--server-process nil)
(dolist (process pinentry--connection-process-list)
(when (buffer-live-p (process-buffer process))
(kill-buffer (process-buffer process))))
(setq pinentry--connection-process-list nil))
(defun pinentry--labels-to-shortcuts (labels)
"Convert strings in LABEL by stripping mnemonics."
(mapcar (lambda (label)
(when label
(let (c)
(if (string-match "\\(?:\\`\\|[^_]\\)_\\([[:alnum:]]\\)" label)
(let ((key (match-string 1 label)))
(setq c (downcase (aref key 0)))
(setq label (replace-match
(propertize key 'face 'underline)
t t label)))
(setq c (if (= (length label) 0)
??
(downcase (aref label 0)))))
;; Double underscores mean a single underscore.
(when (string-match "__" label)
(setq label (replace-match "_" t t label)))
(cons c label))))
labels))
(defun pinentry--escape-string (string)
"Escape STRING in the Assuan percent escape."
(let ((length (length string))
(index 0)
(count 0))
(while (< index length)
(if (memq (aref string index) '(?\n ?\r ?%))
(setq count (1+ count)))
(setq index (1+ index)))
(setq index 0)
(let ((result (make-string (+ length (* count 2)) ?\0))
(result-index 0)
c)
(while (< index length)
(setq c (aref string index))
(if (memq c '(?\n ?\r ?%))
(let ((hex (format "%02X" c)))
(aset result result-index ?%)
(setq result-index (1+ result-index))
(aset result result-index (aref hex 0))
(setq result-index (1+ result-index))
(aset result result-index (aref hex 1))
(setq result-index (1+ result-index)))
(aset result result-index c)
(setq result-index (1+ result-index)))
(setq index (1+ index)))
result)))
(defun pinentry--unescape-string (string)
"Unescape STRING in the Assuan percent escape."
(let ((length (length string))
(index 0))
(let ((result (make-string length ?\0))
(result-index 0)
c)
(while (< index length)
(setq c (aref string index))
(if (and (eq c '?%) (< (+ index 2) length))
(progn
(aset result result-index
(string-to-number (substring string
(1+ index)
(+ index 3))
16))
(setq result-index (1+ result-index))
(setq index (+ index 2)))
(aset result result-index c)
(setq result-index (1+ result-index)))
(setq index (1+ index)))
(substring result 0 result-index))))
(defun pinentry--send-data (process escaped)
"Send a string ESCAPED to a process PROCESS.
ESCAPED will be split if it exceeds the line length limit of the
Assuan protocol."
(let ((length (length escaped))
(index 0))
(if (= length 0)
(process-send-string process "D \n")
(while (< index length)
;; 997 = ASSUAN_LINELENGTH (= 1000) - strlen ("D \n")
(let* ((sub-length (min (- length index) 997))
(sub (substring escaped index (+ index sub-length))))
(unwind-protect
(progn
(process-send-string process "D ")
(process-send-string process sub)
(process-send-string process "\n"))
(clear-string sub))
(setq index (+ index sub-length)))))))
(defun pinentry--send-error (process error)
(process-send-string process (format "ERR %d %s\n" (car error) (cdr error))))
(defun pinentry--process-filter (process input)
(unless (buffer-live-p (process-buffer process))
(let ((buffer (generate-new-buffer " *pinentry*")))
(set-process-buffer process buffer)
(with-current-buffer buffer
(if (fboundp 'set-buffer-multibyte)
(set-buffer-multibyte nil))
(make-local-variable 'pinentry--read-point)
(setq pinentry--read-point (point-min))
(make-local-variable 'pinentry--labels))))
(with-current-buffer (process-buffer process)
(when pinentry-debug
(with-current-buffer
(or pinentry-debug-buffer
(setq pinentry-debug-buffer (generate-new-buffer
" *pinentry-debug*")))
(goto-char (point-max))
(insert input)))
(save-excursion
(goto-char (point-max))
(insert input)
(goto-char pinentry--read-point)
(beginning-of-line)
(while (looking-at ".*\n") ;the input line finished
(if (looking-at "\\([A-Z_]+\\) ?\\(.*\\)")
(let ((command (match-string 1))
(string (pinentry--unescape-string (match-string 2))))
(pcase command
((and set (guard (member set pinentry--set-label-commands)))
(when (> (length string) 0)
(let* ((symbol (intern (downcase (substring set 3))))
(entry (assq symbol pinentry--labels))
(label (decode-coding-string string 'utf-8)))
(if entry
(setcdr entry label)
(push (cons symbol label) pinentry--labels))))
(ignore-errors
(process-send-string process "OK\n")))
("NOP"
(ignore-errors
(process-send-string process "OK\n")))
("GETPIN"
(let ((confirm (not (null (assq 'repeat pinentry--labels))))
passphrase escaped-passphrase encoded-passphrase)
(unwind-protect
(condition-case err
(progn
(setq passphrase
(pinentry--prompt
pinentry--labels
#'read-passwd confirm))
(setq escaped-passphrase
(pinentry--escape-string
passphrase))
(setq encoded-passphrase (encode-coding-string
escaped-passphrase
'utf-8))
(ignore-errors
(pinentry--send-data
process encoded-passphrase)
(process-send-string process "OK\n")))
(error
(message "GETPIN error %S" err)
(ignore-errors
(pinentry--send-error
process
pinentry--error-cancelled))))
(if passphrase
(clear-string passphrase))
(if escaped-passphrase
(clear-string escaped-passphrase))
(if encoded-passphrase
(clear-string encoded-passphrase))))
(setq pinentry--labels nil))
("CONFIRM"
(let ((prompt
(or (cdr (assq 'prompt pinentry--labels))
"Confirm? "))
(buttons
(delq nil
(pinentry--labels-to-shortcuts
(list (cdr (assq 'ok pinentry--labels))
(cdr (assq 'notok pinentry--labels))
(cdr (assq 'cancel pinentry--labels))))))
entry)
(if buttons
(progn
(setq prompt
(concat prompt " ("
(mapconcat #'cdr buttons
", ")
") "))
(if (setq entry (assq 'prompt pinentry--labels))
(setcdr entry prompt)
(setq pinentry--labels (cons (cons 'prompt prompt)
pinentry--labels)))
(condition-case nil
(let ((result (pinentry--prompt pinentry--labels
#'read-char)))
(if (eq result (caar buttons))
(ignore-errors
(process-send-string process "OK\n"))
(if (eq result (car (nth 1 buttons)))
(ignore-errors
(pinentry--send-error
process
pinentry--error-not-confirmed))
(ignore-errors
(pinentry--send-error
process
pinentry--error-cancelled)))))
(error
(ignore-errors
(pinentry--send-error
process
pinentry--error-cancelled)))))
(if (setq entry (assq 'prompt pinentry--labels))
(setcdr entry prompt)
(setq pinentry--labels (cons (cons 'prompt prompt)
pinentry--labels)))
(if (condition-case nil
(pinentry--prompt pinentry--labels #'y-or-n-p)
(quit))
(ignore-errors
(process-send-string process "OK\n"))
(ignore-errors
(pinentry--send-error
process
pinentry--error-not-confirmed))))
(setq pinentry--labels nil)))
(_ (ignore-errors
(pinentry--send-error
process
pinentry--error-not-implemented))))
(forward-line)
(setq pinentry--read-point (point))))))))
(defun pinentry--process-sentinel (process _status)
"The process sentinel for Emacs server connections."
;; If this is a new client process, set the query-on-exit flag to nil
;; for this process (it isn't inherited from the server process).
(when (and (eq (process-status process) 'open)
(process-query-on-exit-flag process))
(push process pinentry--connection-process-list)
(set-process-query-on-exit-flag process nil)
(ignore-errors
(process-send-string process "OK Your orders please\n")))
;; Kill the process buffer of the connection process.
(when (and (not (process-contact process :server))
(eq (process-status process) 'closed))
(when (buffer-live-p (process-buffer process))
(kill-buffer (process-buffer process)))
(setq pinentry--connection-process-list
(delq process pinentry--connection-process-list)))
;; Delete the associated connection file, if applicable.
;; Although there's no 100% guarantee that the file is owned by the
;; running Emacs instance, server-start uses server-running-p to check
;; for possible servers before doing anything, so it *should* be ours.
(and (process-contact process :server)
(eq (process-status process) 'closed)
(ignore-errors
(delete-file (process-get process :server-file)))))
(provide 'pinentry)
;;; pinentry.el ends here
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