;;; GNU Guix --- Functional package management for GNU ;;; Copyright © 2010, 2011, 2013, 2014 Ludovic Courtès <ludo@gnu.org> ;;; Copyright © 2013 Nikita Karetnikov <nikita@karetnikov.org> ;;; ;;; This file is part of GNU Guix. ;;; ;;; GNU Guix 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 Guix 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 Guix. If not, see <http://www.gnu.org/licenses/>. (define-module (guix gnupg) #:use-module (ice-9 popen) #:use-module (ice-9 match) #:use-module (ice-9 regex) #:use-module (ice-9 rdelim) #:use-module (ice-9 i18n) #:use-module (srfi srfi-1) #:use-module (guix ui) #:export (%gpg-command %openpgp-key-server gnupg-verify gnupg-verify* gnupg-status-good-signature? gnupg-status-missing-key?)) ;;; Commentary: ;;; ;;; GnuPG interface. ;;; ;;; Code: (define %gpg-command ;; The GnuPG 2.x command-line program name. (make-parameter "gpg2")) (define %openpgp-key-server ;; The default key server. Note that keys.gnupg.net appears to be ;; unreliable. (make-parameter "pgp.mit.edu")) (define (gnupg-verify sig file) "Verify signature SIG for FILE. Return a status s-exp if GnuPG failed." (define (status-line->sexp line) ;; See file `doc/DETAILS' in GnuPG. (define sigid-rx (make-regexp "^\\[GNUPG:\\] SIG_ID ([A-Za-z0-9+/]+) ([[:digit:]]{4}-[[:digit:]]{2}-[[:digit:]]{2}) ([[:digit:]]+)")) (define goodsig-rx (make-regexp "^\\[GNUPG:\\] GOODSIG ([[:xdigit:]]+) (.+)$")) (define validsig-rx (make-regexp "^\\[GNUPG:\\] VALIDSIG ([[:xdigit:]]+) ([[:digit:]]{4}-[[:digit:]]{2}-[[:digit:]]{2}) ([[:digit:]]+) .*$")) (define expkeysig-rx ; good signature, but expired key (make-regexp "^\\[GNUPG:\\] EXPKEYSIG ([[:xdigit:]]+) (.*)$")) (define errsig-rx (make-regexp "^\\[GNUPG:\\] ERRSIG ([[:xdigit:]]+) ([^ ]+) ([^ ]+) ([^ ]+) ([[:digit:]]+) ([[:digit:]]+)")) (cond ((regexp-exec sigid-rx line) => (lambda (match) `(signature-id ,(match:substring match 1) ; sig id ,(match:substring match 2) ; date ,(string->number ; timestamp (match:substring match 3))))) ((regexp-exec goodsig-rx line) => (lambda (match) `(good-signature ,(match:substring match 1) ; key id ,(match:substring match 2)))) ; user name ((regexp-exec validsig-rx line) => (lambda (match) `(valid-signature ,(match:substring match 1) ; fingerprint ,(match:substring match 2) ; sig creation date ,(string->number ; timestamp (match:substring match 3))))) ((regexp-exec expkeysig-rx line) => (lambda (match) `(expired-key-signature ,(match:substring match 1) ; fingerprint ,(match:substring match 2)))) ; user name ((regexp-exec errsig-rx line) => (lambda (match) `(signature-error ,(match:substring match 1) ; key id or fingerprint ,(match:substring match 2) ; pubkey algo ,(match:substring match 3) ; hash algo ,(match:substring match 4) ; sig class ,(string->number ; timestamp (match:substring match 5)) ,(let ((rc (string->number ; return code (match:substring match 6)))) (case rc ((9) 'missing-key) ((4) 'unknown-algorithm) (else rc)))))) (else `(unparsed-line ,line)))) (define (parse-status input) (let loop ((line (read-line input)) (result '())) (if (eof-object? line) (reverse result) (loop (read-line input) (cons (status-line->sexp line) result))))) (let* ((pipe (open-pipe* OPEN_READ (%gpg-command) "--status-fd=1" "--verify" sig file)) (status (parse-status pipe))) ;; Ignore PIPE's exit status since STATUS above should contain all the ;; info we need. (close-pipe pipe) status)) (define (gnupg-status-good-signature? status) "If STATUS, as returned by `gnupg-verify', denotes a good signature, return a key-id/user pair; return #f otherwise." (any (lambda (sexp) (match sexp (((or 'good-signature 'expired-key-signature) key-id user) (cons key-id user)) (_ #f))) status)) (define (gnupg-status-missing-key? status) "If STATUS denotes a missing-key error, then return the key-id of the missing key." (any (lambda (sexp) (match sexp (('signature-error key-id _ ...) key-id) (_ #f))) status)) (define (gnupg-receive-keys key-id server) (system* (%gpg-command) "--keyserver" server "--recv-keys" key-id)) (define* (gnupg-verify* sig file #:key (key-download 'interactive) (server (%openpgp-key-server))) "Like `gnupg-verify', but try downloading the public key if it's missing. Return #t if the signature was good, #f otherwise. KEY-DOWNLOAD specifies a download policy for missing OpenPGP keys; allowed values: 'always', 'never', and 'interactive' (default)." (let ((status (gnupg-verify sig file))) (or (gnupg-status-good-signature? status) (let ((missing (gnupg-status-missing-key? status))) (define (download-and-try-again) ;; Download the missing key and try again. (begin (gnupg-receive-keys missing server) (gnupg-status-good-signature? (gnupg-verify sig file)))) (define (receive?) (let ((answer (begin (format #t (_ "~a~a~%") "Would you like to download this key " "and add it to your keyring?") (read-line)))) (string-match (locale-yes-regexp) answer))) (and missing (case key-download ((never) #f) ((always) (download-and-try-again)) (else (and (receive?) (download-and-try-again))))))))) ;;; gnupg.scm ends here