3 * Base32 encoding and decoding.
5 * (c) 1997 Straylight/Edgeware
8 /*----- Licensing notice --------------------------------------------------*
10 * This file is part of the mLib utilities library.
12 * mLib is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU Library General Public License as
14 * published by the Free Software Foundation; either version 2 of the
15 * License, or (at your option) any later version.
17 * mLib is distributed in the hope that it will be useful,
18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 * GNU Library General Public License for more details.
22 * You should have received a copy of the GNU Library General Public
23 * License along with mLib; if not, write to the Free
24 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
28 /*----- Header files ------------------------------------------------------*/
37 /*----- Important tables --------------------------------------------------*/
39 static const char encodemap
[] = { "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567" };
41 static const signed char decodemap
[] = {
42 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 0x */
43 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 1x */
44 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 2x */
45 -1, -1, 26, 27, 28, 29, 30, 31, -1, -1, -1, -1, -1, -1, -1, -1, /* 3x */
46 -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, /* 4x */
47 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, /* 5x */
48 -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, /* 6x */
49 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, /* 7x */
52 /*----- Main code ---------------------------------------------------------*/
54 /* --- @base32_encode@ --- *
56 * Arguments: @base32_ctx *ctx@ = pointer to a context block
57 * @const void *p@ = pointer to a source buffer
58 * @size_t sz@ = size of the source buffer
59 * @dstr *d@ = pointer to destination string
63 * Use: Encodes a binary string in base32. To flush out the final
64 * few characters (if necessary), pass a null source pointer.
67 void base32_encode(base32_ctx
*ctx
,
68 const void *p
, size_t sz
,
72 unsigned long accl
= ctx
->accl
, acch
= ctx
->acch
;
73 unsigned qsz
= ctx
->qsz
;
74 const unsigned char *src
= p
;
77 acch
= (acch
<< 8) | ((accl
>> 24) & 0xff);
78 accl
= (accl
<< 8) | *src
++;
82 DPUTC(d
, encodemap
[(acch
>> 3) & 0x1f]);
83 DPUTC(d
, encodemap
[((acch
<< 2) & 0x1c) | ((accl
>> 30) & 0x03)]);
84 DPUTC(d
, encodemap
[(accl
>> 25) & 0x1f]);
85 DPUTC(d
, encodemap
[(accl
>> 20) & 0x1f]);
86 DPUTC(d
, encodemap
[(accl
>> 15) & 0x1f]);
87 DPUTC(d
, encodemap
[(accl
>> 10) & 0x1f]);
88 DPUTC(d
, encodemap
[(accl
>> 5) & 0x1f]);
89 DPUTC(d
, encodemap
[(accl
>> 0) & 0x1f]);
91 if (ctx
->maxline
&& ctx
->lnlen
>= ctx
->maxline
) {
92 dstr_puts(d
, ctx
->indent
);
100 ctx
->acch
= acch
; ctx
->accl
= accl
;
103 unsigned long accl
= ctx
->accl
, acch
= ctx
->acch
;
104 unsigned qsz
= ctx
->qsz
;
107 unsigned pad
= 5 - qsz
;
109 acch
= accl
<< (pad
* 8 - 32);
112 acch
= (acch
<< (8 * pad
)) | ((accl
& 0xffffffff) >> (32 - 8 * pad
));
113 accl
= accl
<< (8 * pad
);
118 DPUTC(d
, encodemap
[(acch
>> 3) & 0x1f]);
119 acch
= (acch
<< 5) | ((accl
>> 27) & 0x1f);
130 ctx
->acch
= ctx
->accl
= 0;
134 /* --- @base32_decode@ --- *
136 * Arguments: @base32_ctx *ctx@ = pointer to a context block
137 * @const void *p@ = pointer to a source buffer
138 * @size_t sz@ = size of the source buffer
139 * @dstr *d@ = pointer to destination string
143 * Use: Decodes a binary string in base32. To flush out the final
144 * few characters (if necessary), pass a null source pointer.
147 void base32_decode(base32_ctx
*ctx
,
148 const void *p
, size_t sz
,
152 unsigned long accl
= ctx
->accl
, acch
= ctx
->acch
;
153 unsigned qsz
= ctx
->qsz
;
159 /* --- Get the next character and convert it --- */
162 if (ch
>= 128 || ch
< 0)
170 /* --- Bung it in the accumulator --- */
172 acch
= (acch
<< 5) | ((accl
>> 27) & 0x1f);
173 accl
= (accl
<< 5) | ch
;
176 /* --- Maybe write out a completed triplet --- */
179 DPUTC(d
, (acch
>> 0) & 0xff);
180 DPUTC(d
, (accl
>> 24) & 0xff);
181 DPUTC(d
, (accl
>> 16) & 0xff);
182 DPUTC(d
, (accl
>> 8) & 0xff);
183 DPUTC(d
, (accl
>> 0) & 0xff);
189 ctx
->acch
= acch
; ctx
->accl
= accl
;
193 /* --- Notes about the tail-end bits --- *
195 * I'll use the queue size to work out how many tail-end bytes I ought to
196 * write. This isn't strictly right, but it's easier.
199 unsigned long acch
= ctx
->acch
, accl
= ctx
->accl
;
200 unsigned qsz
= ctx
->qsz
;
202 /* --- Now fiddle with everything else --- *
204 * There's a bodge here for invalid encodings which have a funny number
205 * of quintets in the final group. I'm not sure this is really worth
206 * having, but it might save some unexpected behaviour. (Not that you
207 * won't still get unexpected behaviour if the stream is completely
212 unsigned pad
= 8 - qsz
;
214 acch
= accl
<< (5 * pad
- 32);
217 acch
= (acch
<< (5 * pad
)) | ((accl
& 0xffffffff) >> (32 - 5 * pad
));
218 accl
= accl
<< (5 * pad
);
223 DPUTC(d
, acch
& 0xff);
230 /* --- That seems to be good enough --- */
233 ctx
->acch
= ctx
->accl
= 0;
237 /* --- @base32_init@ --- *
239 * Arguments: @base32_ctx *ctx@ = pointer to context block to initialize
243 * Use: Initializes a base32 context properly.
246 void base32_init(base32_ctx
*ctx
)
248 ctx
->accl
= ctx
->acch
= 0;
255 /*----- Test driver code --------------------------------------------------*/
259 int main(int argc
, char *argv
[])
261 unsigned char buf
[BUFSIZ
];
264 void (*proc
)(base32_ctx
*, const void *, size_t, dstr
*);
269 if (argc
> 1 && strcmp(argv
[1], "-d") == 0)
270 proc
= base32_decode
;
272 proc
= base32_encode
;
279 sz
= fread(buf
, 1, sizeof(buf
), stdin
);
281 proc(&ctx
, buf
, sz
, &d
);
282 dstr_write(&d
, stdout
);
285 } while (sz
== sizeof(buf
));
287 proc(&ctx
, 0, 0, &d
);
288 dstr_write(&d
, stdout
);
290 if (proc
== base32_encode
)
298 /*----- That's all, folks -------------------------------------------------*/