X-Git-Url: https://jxself.org/git/?p=8sync.git;a=blobdiff_plain;f=8sync%2Fcontrib%2Fbase64.scm;fp=8sync%2Fcontrib%2Fbase64.scm;h=0eb489e1666fbc2e56959a7dd94344c12e8f242a;hp=0000000000000000000000000000000000000000;hb=c7a6683e7ba2377909f37bc6dc11d49f43369191;hpb=d23b593a5810b38d2517a44c09d49b2835c59e16 diff --git a/8sync/contrib/base64.scm b/8sync/contrib/base64.scm new file mode 100644 index 0000000..0eb489e --- /dev/null +++ b/8sync/contrib/base64.scm @@ -0,0 +1,285 @@ +;; -*- mode: scheme; coding: utf-8 -*- +;; Copyright © 2009, 2010, 2012, 2013 Göran Weinholt + +;; 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 + +(library (8sync contrib 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))))) + + ;; 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) + (base64-decode str base64-alphabet #f)) + ((str alphabet) + (base64-decode str alphabet #f)) + ((str alphabet port) + (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))) + ((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) + (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 + (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 + ((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)))))