diff options
| -rw-r--r-- | base64.scm | 291 |
1 files changed, 173 insertions, 118 deletions
@@ -1,25 +1,23 @@ ;; -*- mode: scheme; coding: utf-8 -*- -;; -;; This module was renamed from (weinholt text base64 (1 0 20100612)) to -;; (guix base64) by Nikita Karetnikov <nikita@karetnikov.org> on -;; February 12, 2014. -;; -;; Some optimizations made by Ludovic Courtès <ludo@gnu.org>, 2015. -;; -;; Copyright © 2009, 2010 Göran Weinholt <goran@weinholt.se> -;; -;; This program 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. -;; -;; This program 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 this program. If not, see <http://www.gnu.org/licenses/>. +;; Copyright © 2009, 2010, 2012, 2013 Göran Weinholt <goran@weinholt.se> + +;; Permission is hereby granted, free of charge, to any person obtaining a +;; copy of this software and associated documentation files (the "Software"), +;; to deal in the Software without restriction, including without limitation +;; the rights to use, copy, modify, merge, publish, distribute, sublicense, +;; and/or sell copies of the Software, and to permit persons to whom the +;; Software is furnished to do so, subject to the following conditions: + +;; The above copyright notice and this permission notice shall be included in +;; all copies or substantial portions of the Software. + +;; THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +;; IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +;; FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL +;; THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +;; LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING +;; FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER +;; DEALINGS IN THE SOFTWARE. #!r6rs ;; RFC 4648 Base-N Encodings @@ -35,23 +33,7 @@ (only (srfi :13 strings) string-index string-prefix? string-suffix? - string-concatenate string-trim-both) - (only (guile) ash logior)) - - - (define-syntax define-alias - (syntax-rules () - ((_ new old) - (define-syntax new (identifier-syntax old))))) - - ;; Force the use of Guile's own primitives to avoid the overhead of its 'fx' - ;; procedures. - (define-alias fxbit-field bitwise-bit-field) - (define-alias fxarithmetic-shift ash) - (define-alias fxarithmetic-shift-left ash) - (define-alias fxand logand) - (define-alias fxior logior) - (define-alias fxxor logxor) + string-concatenate string-trim-both)) (define base64-alphabet "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/") @@ -119,8 +101,29 @@ (put p #\=))))))) (extract))))) - ;; Decodes a base64 string. The string must contain only pure - ;; unpadded base64 data. + ;; Create a lookup table for the alphabet and remember the latest table. + (define get-decode-table + (let ((ascii-table #f) + (extra-table '()) ;in the unlikely case of unicode chars + (table-alphabet #f)) + (lambda (alphabet) + (unless (eq? alphabet table-alphabet) + ;; Rebuild the table. + (do ((ascii (make-vector 128 #f)) + (extra '()) + (i 0 (+ i 1))) + ((= i (string-length alphabet)) + (set! ascii-table ascii) + (set! extra-table extra)) + (let ((c (char->integer (string-ref alphabet i)))) + (if (fx<=? c 127) + (vector-set! ascii c i) + (set! extra (cons (cons c i) extra))))) + (set! table-alphabet alphabet)) + (values ascii-table extra-table)))) + + ;; Decodes a correctly padded base64 string, optionally ignoring + ;; non-alphabet characters. (define base64-decode (case-lambda ((str) @@ -128,47 +131,95 @@ ((str alphabet) (base64-decode str alphabet #f)) ((str alphabet port) - (unless (zero? (mod (string-length str) 4)) - (error 'base64-decode - "input string must be a multiple of four characters")) + (base64-decode str alphabet port #t)) + ((str alphabet port strict?) + (define (pad? c) (eqv? c (char->integer #\=))) (let-values (((p extract) (if port (values port (lambda () (values))) - (open-bytevector-output-port)))) - (do ((i 0 (+ i 4))) - ((= i (string-length str)) - (extract)) - (let ((c1 (string-ref str i)) - (c2 (string-ref str (+ i 1))) - (c3 (string-ref str (+ i 2))) - (c4 (string-ref str (+ i 3)))) - ;; TODO: be more clever than string-index - (let ((i1 (string-index alphabet c1)) - (i2 (string-index alphabet c2)) - (i3 (string-index alphabet c3)) - (i4 (string-index alphabet c4))) - (cond ((and i1 i2 i3 i4) - (let ((x (fxior (fxarithmetic-shift-left i1 18) - (fxarithmetic-shift-left i2 12) - (fxarithmetic-shift-left i3 6) - i4))) - (put-u8 p (fxbit-field x 16 24)) - (put-u8 p (fxbit-field x 8 16)) - (put-u8 p (fxbit-field x 0 8)))) - ((and i1 i2 i3 (char=? c4 #\=) - (= i (- (string-length str) 4))) - (let ((x (fxior (fxarithmetic-shift-left i1 18) - (fxarithmetic-shift-left i2 12) - (fxarithmetic-shift-left i3 6)))) - (put-u8 p (fxbit-field x 16 24)) - (put-u8 p (fxbit-field x 8 16)))) - ((and i1 i2 (char=? c3 #\=) (char=? c4 #\=) - (= i (- (string-length str) 4))) - (let ((x (fxior (fxarithmetic-shift-left i1 18) - (fxarithmetic-shift-left i2 12)))) - (put-u8 p (fxbit-field x 16 24)))) - (else - (error 'base64-decode "invalid input" - (list c1 c2 c3 c4))))))))))) + (open-bytevector-output-port))) + ((ascii extra) (get-decode-table alphabet))) + (define-syntax lookup + (syntax-rules () + ((_ c) (or (and (fx<=? c 127) (vector-ref ascii c)) + (cond ((assv c extra) => cdr) + (else #f)))))) + (let* ((len (if strict? + (string-length str) + (let lp ((i (fx- (string-length str) 1))) + ;; Skip trailing invalid chars. + (cond ((fxzero? i) 0) + ((let ((c (char->integer (string-ref str i)))) + (or (lookup c) (pad? c))) + (fx+ i 1)) + (else (lp (fx- i 1)))))))) + (let lp ((i 0)) + (cond + ((fx=? i len) + (extract)) + ((fx<=? i (fx- len 4)) + (let lp* ((c1 (char->integer (string-ref str i))) + (c2 (char->integer (string-ref str (fx+ i 1)))) + (c3 (char->integer (string-ref str (fx+ i 2)))) + (c4 (char->integer (string-ref str (fx+ i 3)))) + (i i)) + (let ((i1 (lookup c1)) (i2 (lookup c2)) + (i3 (lookup c3)) (i4 (lookup c4))) + (cond + ((and i1 i2 i3 i4) + ;; All characters present and accounted for. + ;; The most common case. + (let ((x (fxior (fxarithmetic-shift-left i1 18) + (fxarithmetic-shift-left i2 12) + (fxarithmetic-shift-left i3 6) + i4))) + (put-u8 p (fxbit-field x 16 24)) + (put-u8 p (fxbit-field x 8 16)) + (put-u8 p (fxbit-field x 0 8)) + (lp (fx+ i 4)))) + ((and i1 i2 i3 (pad? c4) (= i (- len 4))) + ;; One padding character at the end of the input. + (let ((x (fxior (fxarithmetic-shift-left i1 18) + (fxarithmetic-shift-left i2 12) + (fxarithmetic-shift-left i3 6)))) + (put-u8 p (fxbit-field x 16 24)) + (put-u8 p (fxbit-field x 8 16)) + (lp (fx+ i 4)))) + ((and i1 i2 (pad? c3) (pad? c4) (= i (- len 4))) + ;; Two padding characters. + (let ((x (fxior (fxarithmetic-shift-left i1 18) + (fxarithmetic-shift-left i2 12)))) + (put-u8 p (fxbit-field x 16 24)) + (lp (fx+ i 4)))) + ((not strict?) + ;; Non-alphabet characters. + (let lp ((i i) (c* '()) (n 4)) + (cond ((fxzero? n) + ;; Found four valid characters. + (lp* (cadddr c*) (caddr c*) (cadr c*) (car c*) + (fx- i 4))) + ((fx=? i len) + (error 'base64-decode + "Invalid input in non-strict mode." + i c*)) + (else + ;; Gather alphabetic (or valid + ;; padding) characters. + (let ((c (char->integer (string-ref str i)))) + (cond ((or (lookup c) + (and (pad? c) + (fx<=? n 2) + (fx=? i (fx- len n)))) + (lp (fx+ i 1) (cons c c*) (fx- n 1))) + (else + (lp (fx+ i 1) c* n)))))))) + (else + (error 'base64-decode + "Invalid input in strict mode." + c1 c2 c3 c4)))))) + (else + (error 'base64-decode + "The input is too short, it may be missing padding." + i))))))))) (define (get-line-comp f port) (if (port-eof? port) @@ -179,45 +230,49 @@ ;; the given port. Returns two values: a string with the type and a ;; bytevector containing the base64 decoded data. The second value ;; is the eof object if there is an eof before the BEGIN delimiter. - (define (get-delimited-base64 port) - (define (get-first-data-line port) - ;; Some MIME data has header fields in the same format as mail - ;; or http. These are ignored. - (let ((line (get-line-comp string-trim-both port))) - (cond ((eof-object? line) line) - ((string-index line #\:) - (let lp () ;read until empty line - (let ((line (get-line-comp string-trim-both port))) - (if (string=? line "") - (get-line-comp string-trim-both port) - (lp))))) - (else line)))) - (let ((line (get-line-comp string-trim-both port))) - (cond ((eof-object? line) - (values "" (eof-object))) - ((string=? line "") - (get-delimited-base64 port)) - ((and (string-prefix? "-----BEGIN " line) - (string-suffix? "-----" line)) - (let* ((type (substring line 11 (- (string-length line) 5))) - (endline (string-append "-----END " type "-----"))) - (let-values (((outp extract) (open-bytevector-output-port))) - (let lp ((line (get-first-data-line port))) - (cond ((eof-object? line) - (error 'get-delimited-base64 - "unexpected end of file")) - ((string-prefix? "-" line) - (unless (string=? line endline) - (error 'get-delimited-base64 - "bad end delimiter" type line)) - (values type (extract))) - (else - (unless (and (= (string-length line) 5) - (string-prefix? "=" line)) ;Skip Radix-64 checksum - (base64-decode line base64-alphabet outp)) - (lp (get-line-comp string-trim-both port)))))))) - (else ;skip garbage (like in openssl x509 -in foo -text output). - (get-delimited-base64 port))))) + (define get-delimited-base64 + (case-lambda + ((port) + (get-delimited-base64 port #t)) + ((port strict) + (define (get-first-data-line port) + ;; Some MIME data has header fields in the same format as mail + ;; or http. These are ignored. + (let ((line (get-line-comp string-trim-both port))) + (cond ((eof-object? line) line) + ((string-index line #\:) + (let lp () ;read until empty line + (let ((line (get-line-comp string-trim-both port))) + (if (string=? line "") + (get-line-comp string-trim-both port) + (lp))))) + (else line)))) + (let ((line (get-line-comp string-trim-both port))) + (cond ((eof-object? line) + (values "" (eof-object))) + ((string=? line "") + (get-delimited-base64 port)) + ((and (string-prefix? "-----BEGIN " line) + (string-suffix? "-----" line)) + (let* ((type (substring line 11 (- (string-length line) 5))) + (endline (string-append "-----END " type "-----"))) + (let-values (((outp extract) (open-bytevector-output-port))) + (let lp ((line (get-first-data-line port))) + (cond ((eof-object? line) + (error 'get-delimited-base64 + "unexpected end of file")) + ((string-prefix? "-" line) + (unless (string=? line endline) + (error 'get-delimited-base64 + "bad end delimiter" type line)) + (values type (extract))) + (else + (unless (and (= (string-length line) 5) + (string-prefix? "=" line)) ;Skip Radix-64 checksum + (base64-decode line base64-alphabet outp)) + (lp (get-line-comp string-trim-both port)))))))) + (else ;skip garbage (like in openssl x509 -in foo -text output). + (get-delimited-base64 port))))))) (define put-delimited-base64 (case-lambda |