--- /dev/null
+;;; pinentry.el --- GnuPG Pinentry server implementation -*- lexical-binding: t -*-
+
+;; Copyright (C) 2015 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, 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 June 2015, this feature requires newer versions of
+;; GnuPG (2.1.5+) and Pinentry (not yet released, possibly 0.9.5+).
+;; For details, see the discussion on gnupg-devel mailing list:
+;; <https://lists.gnupg.org/pipermail/gnupg-devel/2015-May/029875.html>.
+
+;;; Code:
+
+(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)
+
+;; 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")
+
+;;;###autoload
+(defun pinentry-start ()
+ "Start a Pinentry service.
+
+Once the environment is properly set, subsequent invocations of
+the gpg command will interact with Emacs for passphrase input."
+ (interactive)
+ (unless (featurep 'make-network-process '(:family local))
+ (error "local sockets are not supported"))
+ (if (process-live-p pinentry--server-process)
+ (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)))
+ (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)
+ (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 ((prompt
+ (or (cdr (assq 'desc pinentry--labels))
+ (cdr (assq 'prompt pinentry--labels))
+ ""))
+ (confirm (not (null (assq 'repeat pinentry--labels))))
+ entry)
+ (if (setq entry (assq 'error pinentry--labels))
+ (setq prompt (concat "Error: "
+ (propertize
+ (copy-sequence (cdr entry))
+ 'face 'error)
+ "\n"
+ prompt)))
+ (if (setq entry (assq 'title pinentry--labels))
+ (setq prompt (format "[%s] %s"
+ (cdr entry) prompt)))
+ (if (string-match ":?[ \n]*\\'" prompt)
+ (setq prompt (concat
+ (substring
+ prompt 0 (match-beginning 0)) ": ")))
+ (let (passphrase escaped-passphrase encoded-passphrase)
+ (unwind-protect
+ (condition-case nil
+ (progn
+ (setq passphrase
+ (read-passwd prompt 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
+ (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 'desc pinentry--labels))
+ ""))
+ (buttons
+ (pinentry--labels-to-shortcuts
+ (list (cdr (assq 'ok pinentry--labels))
+ (cdr (assq 'notok pinentry--labels))
+ (cdr (assq 'cancel pinentry--labels)))))
+ entry)
+ (if (setq entry (assq 'error pinentry--labels))
+ (setq prompt (concat "Error: "
+ (propertize
+ (copy-sequence (cdr entry))
+ 'face 'error)
+ "\n"
+ prompt)))
+ (if (setq entry (assq 'title pinentry--labels))
+ (setq prompt (format "[%s] %s"
+ (cdr entry) prompt)))
+ (if (remq nil buttons)
+ (progn
+ (setq prompt
+ (concat prompt " ("
+ (mapconcat #'cdr (remq nil buttons)
+ ", ")
+ ") "))
+ (condition-case nil
+ (let ((result (read-char prompt)))
+ (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 (string-match "[ \n]*\\'" prompt)
+ (setq prompt (concat
+ (substring
+ prompt 0 (match-beginning 0)) " ")))
+ (if (condition-case nil
+ (y-or-n-p prompt)
+ (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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