From: Mattias Engdegård Date: Tue, 27 Oct 2020 10:52:38 +0000 (+0100) Subject: Don't rely on bignums in ntlm.el X-Git-Tag: emacs-28.0.90~5395 X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=f971a612a92eea4c8aab6b002d7998bb0b6f5ca1;p=emacs.git Don't rely on bignums in ntlm.el Since ntlm.el is distributed as a separate package in GNU ELPA and should be able to run on older Emacs versions without bignums, we cannot make use of them here. See discussion at https://lists.gnu.org/archive/html/emacs-devel/2020-10/msg01665.html. Instead, we add a small poor man's bignum implementation. * lisp/net/ntlm.el (ntlm--bignat-of-int, ntlm--bignat-add) (ntlm--bignat-shift-left, ntlm--bignat-mul-byte, ntlm--bignat-mul) (ntlm--bignat-of-string, ntlm--bignat-of-digits) (ntlm--bignat-to-int64): New. (ntlm--time-to-timestamp): Use the ntlm--bignat- functions instead of Lisp integers. * test/lisp/net/ntlm-tests.el: New file. --- diff --git a/lisp/net/ntlm.el b/lisp/net/ntlm.el index 9401430799c..6d1cf2da71f 100644 --- a/lisp/net/ntlm.el +++ b/lisp/net/ntlm.el @@ -132,23 +132,89 @@ is not given." domain ;buffer field )))) +;; Poor man's bignums: natural numbers represented as lists of bytes +;; in little-endian order. +;; When this code no longer needs to run on Emacs 26 or older, all this +;; silliness should be simplified to use ordinary Lisp integers. + +(eval-and-compile ; for compile-time simplification + (defun ntlm--bignat-of-int (x) + "Convert the natural number X into a bignat." + (declare (pure t)) + (and (not (zerop x)) + (cons (logand x #xff) (ntlm--bignat-of-int (ash x -8))))) + + (defun ntlm--bignat-add (a b &optional carry) + "Add the bignats A and B and the natural number CARRY." + (declare (pure t)) + (and (or a b (and carry (not (zerop carry)))) + (let ((s (+ (if a (car a) 0) + (if b (car b) 0) + (or carry 0)))) + (cons (logand s #xff) + (ntlm--bignat-add (cdr a) (cdr b) (ash s -8)))))) + + (defun ntlm--bignat-shift-left (x n) + "Multiply the bignat X by 2^{8N}." + (declare (pure t)) + (if (zerop n) x (ntlm--bignat-shift-left (cons 0 x) (1- n)))) + + (defun ntlm--bignat-mul-byte (a b) + "Multiply the bignat A with the byte B." + (declare (pure t)) + (let ((p (mapcar (lambda (x) (* x b)) a))) + (ntlm--bignat-add + (mapcar (lambda (x) (logand x #xff)) p) + (cons 0 (mapcar (lambda (x) (ash x -8)) p))))) + + (defun ntlm--bignat-mul (a b) + "Multiply the bignats A and B." + (declare (pure t)) + (and a b (ntlm--bignat-add (ntlm--bignat-mul-byte a (car b)) + (cons 0 (ntlm--bignat-mul a (cdr b)))))) + + (defun ntlm--bignat-of-string (s) + "Convert the string S (in decimal) to a bignat." + (declare (pure t)) + (ntlm--bignat-of-digits (reverse (string-to-list s)))) + + (defun ntlm--bignat-of-digits (digits) + "Convert the little-endian list DIGITS of decimal digits to a bignat." + (declare (pure t)) + (and digits + (ntlm--bignat-add + nil + (ntlm--bignat-mul-byte (ntlm--bignat-of-digits (cdr digits)) 10) + (- (car digits) ?0)))) + + (defun ntlm--bignat-to-int64 (x) + "Convert the bignat X to a 64-bit little-endian number as a string." + (declare (pure t)) + (apply #'unibyte-string (mapcar (lambda (n) (or (nth n x) 0)) + (number-sequence 0 7)))) + ) + (defun ntlm--time-to-timestamp (time) "Convert TIME to an NTLMv2 timestamp. Return a unibyte string representing the number of tenths of a microsecond since January 1, 1601 as a 64-bit little-endian signed integer. TIME must be on the form (HIGH LOW USEC PSEC)." - (let* ((s (+ (ash (nth 0 time) 16) (nth 1 time))) - (us (nth 2 time)) - (ps (nth 3 time)) + (let* ((s-hi (ntlm--bignat-of-int (nth 0 time))) + (s-lo (ntlm--bignat-of-int (nth 1 time))) + (s (ntlm--bignat-add (ntlm--bignat-shift-left s-hi 2) s-lo)) + (us*10 (ntlm--bignat-of-int (* (nth 2 time) 10))) + (ps/1e5 (ntlm--bignat-of-int (/ (nth 3 time) 100000))) + ;; tenths of microseconds between 1601-01-01 and 1970-01-01 + (to-unix-epoch (ntlm--bignat-of-string "116444736000000000")) (tenths-of-us-since-jan-1-1601 - (+ (* s 10000000) (* us 10) (/ ps 100000) - ;; tenths of microseconds between 1601-01-01 and 1970-01-01 - 116444736000000000))) - (apply #'unibyte-string - (mapcar (lambda (i) - (logand (ash tenths-of-us-since-jan-1-1601 (* i -8)) - #xff)) - (number-sequence 0 7))))) + (ntlm--bignat-add + (ntlm--bignat-add + (ntlm--bignat-add + (ntlm--bignat-mul s (ntlm--bignat-of-int 10000000)) + us*10) + ps/1e5) + to-unix-epoch))) + (ntlm--bignat-to-int64 tenths-of-us-since-jan-1-1601))) (defun ntlm-compute-timestamp () "Current time as an NTLMv2 timestamp, as a unibyte string." diff --git a/test/lisp/net/ntlm-tests.el b/test/lisp/net/ntlm-tests.el new file mode 100644 index 00000000000..e515ebe2635 --- /dev/null +++ b/test/lisp/net/ntlm-tests.el @@ -0,0 +1,52 @@ +;;; ntlm-tests.el --- tests for ntlm.el -*- lexical-binding: t -*- + +;; Copyright (C) 2020 Free Software Foundation, Inc. + +;; 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 . + +(require 'ert) +(require 'ntlm) + +;; This is the Lisp bignum implementation of `ntlm--time-to-timestamp', +;; for reference. +(defun ntlm-tests--time-to-timestamp (time) + "Convert TIME to an NTLMv2 timestamp. +Return a unibyte string representing the number of tenths of a +microsecond since January 1, 1601 as a 64-bit little-endian +signed integer. TIME must be on the form (HIGH LOW USEC PSEC)." + (let* ((s (+ (ash (nth 0 time) 16) (nth 1 time))) + (us (nth 2 time)) + (ps (nth 3 time)) + (tenths-of-us-since-jan-1-1601 + (+ (* s 10000000) (* us 10) (/ ps 100000) + ;; tenths of microseconds between 1601-01-01 and 1970-01-01 + 116444736000000000))) + (apply #'unibyte-string + (mapcar (lambda (i) + (logand (ash tenths-of-us-since-jan-1-1601 (* i -8)) + #xff)) + (number-sequence 0 7))))) + +(ert-deftest ntlm-time-to-timestamp () + ;; Verify poor man's bignums in implementation that can run on Emacs < 27.1. + (let ((time '(24471 63910 412962 0))) + (should (equal (ntlm--time-to-timestamp time) + (ntlm-tests--time-to-timestamp time)))) + (let ((time '(397431 65535 999999 999999))) + (should (equal (ntlm--time-to-timestamp time) + (ntlm-tests--time-to-timestamp time))))) + +(provide 'ntlm-tests)