;;; auth-source-pass.el --- Integrate auth-source with password-store -*- lexical-binding: t -*-
;; Copyright (C) 2015, 2017 Free Software Foundation, Inc.
;; Author: Damien Cassou <damien@cassou.me>,
;; Nicolas Petton <nicolas@petton.fr>
;; Version: 2.0.0
;; Package-Requires: ((emacs "24.4")
;; Created: 07 Jun 2015
;; Keywords: pass password-store auth-source username password login
;; 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 <https://www.gnu.org/licenses/>.
;;; Commentary:
;; Integrates password-store (http://passwordstore.org/) within
;; auth-source.
;;; Code:
(require 'seq)
(eval-when-compile (require 'subr-x))
(eval-when-compile
(require 'cl-lib))
(require 'auth-source)
(require 'url-parse)
(cl-defun auth-source-pass-search (&rest spec
&key backend type host user port
&allow-other-keys)
"Given a property list SPEC, return search matches from the :backend.
See `auth-source-search' for details on SPEC."
(cl-assert (or (null type) (eq type (oref backend type)))
t "Invalid password-store search: %s %s")
(when (listp host)
;; Take the first non-nil item of the list of hosts
(setq host (seq-find #'identity host)))
(list (auth-source-pass--build-result host port user)))
(defun auth-source-pass--build-result (host port user)
"Build auth-source-pass entry matching HOST, PORT and USER."
(let ((entry (auth-source-pass--find-match host user)))
(when entry
(let ((retval (list
:host host
:port (or (auth-source-pass-get "port" entry) port)
:user (or (auth-source-pass-get "user" entry) user)
:secret (lambda () (auth-source-pass-get 'secret entry)))))
(auth-source-pass--do-debug "return %s as final result (plus hidden password)"
(seq-subseq retval 0 -2)) ;; remove password
retval))))
;;;###autoload
(defun auth-source-pass-enable ()
"Enable auth-source-password-store."
;; To add password-store to the list of sources, evaluate the following:
(add-to-list 'auth-sources 'password-store)
;; clear the cache (required after each change to #'auth-source-pass-search)
(auth-source-forget-all-cached))
(defvar auth-source-pass-backend
(auth-source-backend
(format "Password store")
:source "." ;; not used
:type 'password-store
:search-function #'auth-source-pass-search)
"Auth-source backend for password-store.")
(defun auth-source-pass-backend-parse (entry)
"Create a password-store auth-source backend from ENTRY."
(when (eq entry 'password-store)
(auth-source-backend-parse-parameters entry auth-source-pass-backend)))
(add-hook 'auth-source-backend-parser-functions #'auth-source-pass-backend-parse)
(defun auth-source-pass-get (key entry)
"Return the value associated to KEY in the password-store entry ENTRY.
ENTRY is the name of a password-store entry.
The key used to retrieve the password is the symbol `secret'.
The convention used as the format for a password-store file is
the following (see http://www.passwordstore.org/#organization):
secret
key1: value1
key2: value2"
(let ((data (auth-source-pass-parse-entry entry)))
(or (cdr (assoc key data))
(and (string= key "user")
(cdr (assoc "username" data))))))
(defun auth-source-pass--read-entry (entry)
"Return a string with the file content of ENTRY."
(with-temp-buffer
(insert-file-contents (expand-file-name
(format "%s.gpg" entry)
"~/.password-store"))
(buffer-substring-no-properties (point-min) (point-max))))
(defun auth-source-pass-parse-entry (entry)
"Return an alist of the data associated with ENTRY.
ENTRY is the name of a password-store entry."
(let ((file-contents (ignore-errors (auth-source-pass--read-entry entry))))
(and file-contents
(cons `(secret . ,(auth-source-pass--parse-secret file-contents))
(auth-source-pass--parse-data file-contents)))))
(defun auth-source-pass--parse-secret (contents)
"Parse the password-store data in the string CONTENTS and return its secret.
The secret is the first line of CONTENTS."
(car (split-string contents "\\\n" t)))
(defun auth-source-pass--parse-data (contents)
"Parse the password-store data in the string CONTENTS and return an alist.
CONTENTS is the contents of a password-store formatted file."
(let ((lines (split-string contents "\\\n" t "\\\s")))
(seq-remove #'null
(mapcar (lambda (line)
(let ((pair (mapcar (lambda (s) (string-trim s))
(split-string line ":"))))
(when (> (length pair) 1)
(cons (car pair)
(mapconcat #'identity (cdr pair) ":")))))
(cdr lines)))))
(defun auth-source-pass--user-match-p (entry user)
"Return true iff ENTRY match USER."
(or (null user)
(string= user (auth-source-pass-get "user" entry))))
(defun auth-source-pass--hostname (host)
"Extract hostname from HOST."
(let ((url (url-generic-parse-url host)))
(or (url-host url) host)))
(defun auth-source-pass--hostname-with-user (host)
"Extract hostname and user from HOST."
(let* ((url (url-generic-parse-url host))
(user (url-user url))
(hostname (url-host url)))
(cond
((and user hostname) (format "%s@%s" user hostname))
(hostname hostname)
(t host))))
(defun auth-source-pass--do-debug (&rest msg)
"Call `auth-source-do-debug` with MSG and a prefix."
(apply #'auth-source-do-debug
(cons (concat "auth-source-password-store: " (car msg))
(cdr msg))))
(defun auth-source-pass--select-one-entry (entries user)
"Select one entry from ENTRIES by searching for a field matching USER."
(let ((number (length entries))
(entry-with-user
(and user
(seq-find (lambda (entry)
(string-equal (auth-source-pass-get "user" entry) user))
entries))))
(auth-source-pass--do-debug "found %s matches: %s" number
(mapconcat #'identity entries ", "))
(if entry-with-user
(progn
(auth-source-pass--do-debug "return %s as it contains matching user field"
entry-with-user)
entry-with-user)
(auth-source-pass--do-debug "return %s as it is the first one" (car entries))
(car entries))))
(defun auth-source-pass--entry-valid-p (entry)
"Return t iff ENTRY can be opened.
Also displays a warning if not. This function is slow, don't call it too
often."
(if (auth-source-pass-parse-entry entry)
t
(auth-source-pass--do-debug "entry '%s' is not valid" entry)
nil))
;; TODO: add tests for that when `assess-with-filesystem' is included
;; in Emacs
(defun auth-source-pass-entries ()
"Return a list of all password store entries."
(let ((store-dir (expand-file-name "~/.password-store/")))
(mapcar
(lambda (file) (file-name-sans-extension (file-relative-name file store-dir)))
(directory-files-recursively store-dir "\.gpg$"))))
(defun auth-source-pass--find-all-by-entry-name (entryname user)
"Search the store for all entries either matching ENTRYNAME/USER or ENTRYNAME.
Only return valid entries as of `auth-source-pass--entry-valid-p'."
(seq-filter (lambda (entry)
(and
(or
(let ((components-host-user
(member entryname (split-string entry "/"))))
(and (= (length components-host-user) 2)
(string-equal user (cadr components-host-user))))
(string-equal entryname (file-name-nondirectory entry)))
(auth-source-pass--entry-valid-p entry)))
(auth-source-pass-entries)))
(defun auth-source-pass--find-one-by-entry-name (entryname user)
"Search the store for an entry matching ENTRYNAME.
If USER is non nil, give precedence to entries containing a user field
matching USER."
(auth-source-pass--do-debug "searching for '%s' in entry names (user: %s)"
entryname
user)
(let ((matching-entries (auth-source-pass--find-all-by-entry-name entryname user)))
(pcase (length matching-entries)
(0 (auth-source-pass--do-debug "no match found")
nil)
(1 (auth-source-pass--do-debug "found 1 match: %s" (car matching-entries))
(car matching-entries))
(_ (auth-source-pass--select-one-entry matching-entries user)))))
(defun auth-source-pass--find-match (host user)
"Return a password-store entry name matching HOST and USER.
If many matches are found, return the first one. If no match is
found, return nil."
(or
(if (url-user (url-generic-parse-url host))
;; if HOST contains a user (e.g., "user@host.com"), <HOST>
(auth-source-pass--find-one-by-entry-name (auth-source-pass--hostname-with-user host) user)
;; otherwise, if USER is provided, search for <USER>@<HOST>
(when (stringp user)
(auth-source-pass--find-one-by-entry-name (concat user "@" (auth-source-pass--hostname host)) user)))
;; if that didn't work, search for HOST without it's user component if any
(auth-source-pass--find-one-by-entry-name (auth-source-pass--hostname host) user)
;; if that didn't work, remove subdomain: foo.bar.com -> bar.com
(let ((components (split-string host "\\.")))
(when (= (length components) 3)
;; start from scratch
(auth-source-pass--find-match (mapconcat 'identity (cdr components) ".") user)))))
(provide 'auth-source-pass)
;;; auth-source-pass.el ends here