;; -*- 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. ;; ;; 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/>. #!r6rs ;; RFC 4648 Base-N Encodings (library (guix base64) (export base64-encode base64-decode base64-alphabet base64url-alphabet get-delimited-base64 put-delimited-base64) (import (rnrs) (only (srfi :13 strings) string-index string-prefix? string-suffix? string-concatenate string-trim-both)) (define base64-alphabet "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/") (define base64url-alphabet "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_") (define base64-encode (case-lambda ;; Simple interface. Returns a string containing the canonical ;; base64 representation of the given bytevector. ((bv) (base64-encode bv 0 (bytevector-length bv) #f #f base64-alphabet #f)) ((bv start) (base64-encode bv start (bytevector-length bv) #f #f base64-alphabet #f)) ((bv start end) (base64-encode bv start end #f #f base64-alphabet #f)) ((bv start end line-length) (base64-encode bv start end line-length #f base64-alphabet #f)) ((bv start end line-length no-padding) (base64-encode bv start end line-length no-padding base64-alphabet #f)) ((bv start end line-length no-padding alphabet) (base64-encode bv start end line-length no-padding alphabet #f)) ;; Base64 encodes the bytes [start,end[ in the given bytevector. ;; Lines are limited to line-length characters (unless #f), ;; which must be a multiple of four. To omit the padding ;; characters (#\=) set no-padding to a true value. If port is ;; #f, returns a string. ((bv start end line-length no-padding alphabet port) (assert (or (not line-length) (zero? (mod line-length 4)))) (let-values (((p extract) (if port (values port (lambda () (values))) (open-string-output-port)))) (letrec ((put (if line-length (let ((chars 0)) (lambda (p c) (when (fx=? chars line-length) (set! chars 0) (put-char p #\linefeed)) (set! chars (fx+ chars 1)) (put-char p c))) put-char))) (let lp ((i start)) (cond ((= i end)) ((<= (+ i 3) end) (let ((x (bytevector-uint-ref bv i (endianness big) 3))) (put p (string-ref alphabet (fxbit-field x 18 24))) (put p (string-ref alphabet (fxbit-field x 12 18))) (put p (string-ref alphabet (fxbit-field x 6 12))) (put p (string-ref alphabet (fxbit-field x 0 6))) (lp (+ i 3)))) ((<= (+ i 2) end) (let ((x (fxarithmetic-shift-left (bytevector-u16-ref bv i (endianness big)) 8))) (put p (string-ref alphabet (fxbit-field x 18 24))) (put p (string-ref alphabet (fxbit-field x 12 18))) (put p (string-ref alphabet (fxbit-field x 6 12))) (unless no-padding (put p #\=)))) (else (let ((x (fxarithmetic-shift-left (bytevector-u8-ref bv i) 16))) (put p (string-ref alphabet (fxbit-field x 18 24))) (put p (string-ref alphabet (fxbit-field x 12 18))) (unless no-padding (put p #\=) (put p #\=))))))) (extract))))) ;; Decodes a base64 string. The string must contain only pure ;; unpadded base64 data. (define base64-decode (case-lambda ((str) (base64-decode str base64-alphabet #f)) ((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")) (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))))))))))) (define (get-line-comp f port) (if (port-eof? port) (eof-object) (f (get-line port)))) ;; Reads the common -----BEGIN/END type----- delimited format from ;; 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 put-delimited-base64 (case-lambda ((port type bv line-length) (display (string-append "-----BEGIN " type "-----\n") port) (base64-encode bv 0 (bytevector-length bv) line-length #f base64-alphabet port) (display (string-append "\n-----END " type "-----\n") port)) ((port type bv) (put-delimited-base64 port type bv 76)))))