emacs/lisp/net/netrc.el

;;; netrc.el --- .netrc parsing functionality  -*- lexical-binding: t -*-

;; Copyright (C) 1996-2022 Free Software Foundation, Inc.

;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
;; Keywords: news
;;
;;  Modularized by Ted Zlatanov <tzz@lifelogs.com>
;;  when it was part of Gnus.

;; 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:

;; Just the .netrc parsing functionality, abstracted so other packages
;; besides Gnus can use it.

;;; Code:

;;;
;;; .netrc and .authinfo rc parsing
;;;

(defgroup netrc nil
 "Netrc configuration."
 :group 'comm)

(defcustom netrc-file "~/.authinfo"
  "File where user credentials are stored."
  :version "24.1"
  :type 'file)

(defvar netrc-services-file "/etc/services"
  "The name of the services file.")

(defvar netrc-cache nil)

(defun netrc-parse (&optional file)
  "Parse FILE and return a list of all entries in the file."
  (interactive "fFile to Parse: ")
  (unless file
    (setq file netrc-file))
  (if (listp file)
      ;; We got already parsed contents; just return it.
      file
    (when (file-exists-p file)
      (with-temp-buffer
	(let ((tokens '("machine" "default" "login"
			"password" "account" "macdef" "force"
			"port"))
	      alist elem result pair)
          (if (and netrc-cache
		   (equal (car netrc-cache) (file-attribute-modification-time
                                             (file-attributes file))))
	      (insert (base64-decode-string (rot13-string (cdr netrc-cache))))
	    (insert-file-contents file)
	    (when (string-match "\\.gpg\\'" file)
	      ;; Store the contents of the file heavily encrypted in memory.
	      (setq netrc-cache (cons (file-attribute-modification-time
                                       (file-attributes file))
				      (rot13-string
				       (base64-encode-string
					(buffer-string)))))))
	  (goto-char (point-min))
	  ;; Go through the file, line by line.
	  (while (not (eobp))
	    (narrow-to-region (point) (point-at-eol))
	    ;; For each line, get the tokens and values.
	    (while (not (eobp))
	      (skip-chars-forward "\t ")
	      ;; Skip lines that begin with a "#".
	      (if (eq (char-after) ?#)
		  (goto-char (point-max))
		(unless (eobp)
		  (setq elem
			(if (= (following-char) ?\")
			    (read (current-buffer))
			  (buffer-substring
			   (point) (progn (skip-chars-forward "^\t ")
					  (point)))))
		  (cond
		   ((equal elem "macdef")
		    ;; We skip past the macro definition.
		    (widen)
		    (while (and (zerop (forward-line 1))
				(looking-at "$")))
		    (narrow-to-region (point) (point)))
		   ((member elem tokens)
		    ;; Tokens that don't have a following value are ignored,
		    ;; except "default".
		    (when (and pair (or (cdr pair)
					(equal (car pair) "default")))
		      (push pair alist))
		    (setq pair (list elem)))
		   (t
		    ;; Values that haven't got a preceding token are ignored.
		    (when pair
		      (setcdr pair elem)
		      (push pair alist)
		      (setq pair nil)))))))
	    (when alist
	      (push (nreverse alist) result))
	    (setq alist nil
		  pair nil)
	    (widen)
	    (forward-line 1))
	  (nreverse result))))))

(defun netrc-machine (list machine &optional port defaultport)
  "Return the netrc values from LIST for MACHINE or for the default entry.
If PORT specified, only return entries with matching port tokens.
Entries without port tokens default to DEFAULTPORT."
  (let ((rest list)
	result)
    (while list
      (when (equal (cdr (assoc "machine" (car list))) machine)
	(push (car list) result))
      (pop list))
    (unless result
      ;; No machine name matches, so we look for default entries.
      (while rest
	(when (assoc "default" (car rest))
	  (let ((elem (car rest)))
	    (setq elem (delete (assoc "default" elem) elem))
	    (push elem result)))
	(pop rest)))
    (when result
      (setq result (nreverse result))
      (if (not port)
	  (car result)
	(while (and result
		    (not (netrc-port-equal
			  (or port defaultport "nntp")
			  ;; when port is not given in the netrc file,
			  ;; it should mean "any port"
			  (or (netrc-get (car result) "port")
			      defaultport port))))
	  (pop result))
	(car result)))))

(defun netrc-machine-user-or-password (mode authinfo-file-or-list machines ports defaults)
  "Get the user name or password according to MODE from AUTHINFO-FILE-OR-LIST.
Matches a machine from MACHINES and a port from PORTS, giving
default ports DEFAULTS to `netrc-machine'.

MODE can be \"login\" or \"password\", suitable for passing to
`netrc-get'."
  (let ((authinfo-list (if (stringp authinfo-file-or-list)
			   (netrc-parse authinfo-file-or-list)
			 authinfo-file-or-list))
	(ports (or ports '(nil)))
	(defaults (or defaults '(nil)))
	info)
    (if (listp mode)
	(setq info
	      (mapcar
	       (lambda (mode-element)
		 (netrc-machine-user-or-password
		  mode-element
		  authinfo-list
		  machines
		  ports
		  defaults))
	       mode))
      (dolist (machine machines)
	(dolist (default defaults)
	  (dolist (port ports)
	    (let ((alist (netrc-machine authinfo-list machine port default)))
	      (setq info (or (netrc-get alist mode) info)))))))
    info))

(defun netrc-get (alist type)
  "Return the value of token TYPE from ALIST."
  (cdr (assoc type alist)))

(defun netrc-port-equal (port1 port2)
  (when (numberp port1)
    (setq port1 (or (netrc-find-service-name port1) port1)))
  (when (numberp port2)
    (setq port2 (or (netrc-find-service-name port2) port2)))
  (equal port1 port2))

(defun netrc-parse-services ()
  (when (file-exists-p netrc-services-file)
    (let ((services nil))
      (with-temp-buffer
	(insert-file-contents netrc-services-file)
	(while (search-forward "#" nil t)
	  (delete-region (1- (point)) (point-at-eol)))
	(goto-char (point-min))
	(while (re-search-forward
		"^ *\\([^ \n\t]+\\)[ \t]+\\([0-9]+\\)/\\([^ \t\n]+\\)" nil t)
	  (push (list (match-string 1) (string-to-number (match-string 2))
		      (intern (downcase (match-string 3))))
		services))
	(nreverse services)))))

(defun netrc-find-service-name (number &optional type)
  (let ((services (netrc-parse-services))
	service)
    (setq type (or type 'tcp))
    (while (and (setq service (pop services))
		(not (and (= number (cadr service))
			  (eq type (car (cddr service)))))))
    (car service)))

;;;###autoload
(defun netrc-credentials (machine &rest ports)
  "Return a user name/password pair.
Port specifications will be prioritized in the order they are
listed in the PORTS list."
  (let ((list (netrc-parse))
	found)
    (if (not ports)
	(setq found (netrc-machine list machine))
      (while (and ports
		  (not found))
	(setq found (netrc-machine list machine (pop ports)))))
    (when found
      (list (cdr (assoc "login" found))
	    (cdr (assoc "password" found))))))

(provide 'netrc)

;;; netrc.el ends here