chiark / gitweb /
New @conn_init@ interface.
[mLib] / base64.c
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ceba1986 1/* -*-c-*-
2 *
a226592f 3 * $Id: base64.c,v 1.4 1999/10/15 21:08:46 mdw Exp $
ceba1986 4 *
5 * Base64 encoding and decoding.
6 *
7 * (c) 1997 Straylight/Edgeware
8 */
9
10/*----- Licensing notice --------------------------------------------------*
11 *
12 * This file is part of the mLib utilities library.
13 *
14 * mLib is free software; you can redistribute it and/or modify
15 * it under the terms of the GNU Library General Public License as
16 * published by the Free Software Foundation; either version 2 of the
17 * License, or (at your option) any later version.
18 *
19 * mLib is distributed in the hope that it will be useful,
20 * but WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
22 * GNU Library General Public License for more details.
23 *
24 * You should have received a copy of the GNU Library General Public
25 * License along with mLib; if not, write to the Free
26 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
27 * MA 02111-1307, USA.
28 */
29
30/*----- Revision history --------------------------------------------------*
31 *
32 * $Log: base64.c,v $
a226592f 33 * Revision 1.4 1999/10/15 21:08:46 mdw
34 * Change support for erroneous Base64 streams with length 1 mod 4.
35 *
0bfb1431 36 * Revision 1.3 1999/05/21 22:14:30 mdw
37 * Take advantage of the new dynamic string macros.
38 *
c601c4f1 39 * Revision 1.2 1999/05/18 21:45:27 mdw
40 * Allow Base64 encode and decode of arbitrary rubbish.
41 *
ceba1986 42 * Revision 1.1 1999/05/17 20:35:00 mdw
43 * Base64 encoding and decoding support.
44 *
45 */
46
47/*----- Header files ------------------------------------------------------*/
48
49#include <stdio.h>
50#include <stdlib.h>
51#include <string.h>
52
53#include "base64.h"
54#include "dstr.h"
55
56/*----- Important tables --------------------------------------------------*/
57
58static const char base64_encodeMap[] = { "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
59 "abcdefghijklmnopqrstuvwxyz"
60 "0123456789+/" };
61
62static const signed char base64_decodeMap[] = {
63 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 0x */
64 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 1x */
65 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, /* 2x */
66 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, /* 3x */
67 -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, /* 4x */
68 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, /* 5x */
69 -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36 ,37, 38, 39, 40, /* 6x */
70 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1 /* 7x */
71};
72
73/*----- Main code ---------------------------------------------------------*/
74
75/* --- @base64_encode@ --- *
76 *
77 * Arguments: @base64_ctx *ctx@ = pointer to a context block
c601c4f1 78 * @const void *p@ = pointer to a source buffer
ceba1986 79 * @size_t sz@ = size of the source buffer
80 * @dstr *d@ = pointer to destination string
81 *
82 * Returns: ---
83 *
84 * Use: Encodes a binary string in base64. To flush out the final
85 * few characters (if necessary), pass a null source pointer.
86 */
87
88void base64_encode(base64_ctx *ctx,
c601c4f1 89 const void *p, size_t sz,
ceba1986 90 dstr *d)
91{
c601c4f1 92 if (p) {
ceba1986 93 unsigned long acc = ctx->acc;
94 unsigned qsz = ctx->qsz;
c601c4f1 95 const unsigned char *src = p;
ceba1986 96
97 while (sz) {
98 acc = (acc << 8) | *src++;
99 qsz++;
100 sz--;
101 if (qsz == 3) {
c601c4f1 102 DPUTC(d, base64_encodeMap[(acc >> 18) & 0x3f]);
103 DPUTC(d, base64_encodeMap[(acc >> 12) & 0x3f]);
104 DPUTC(d, base64_encodeMap[(acc >> 6) & 0x3f]);
105 DPUTC(d, base64_encodeMap[(acc >> 0) & 0x3f]);
ceba1986 106 ctx->lnlen += 4;
107 if (ctx->maxline && ctx->lnlen >= ctx->maxline) {
108 dstr_puts(d, ctx->indent);
109 ctx->lnlen = 0;
110 }
111 qsz = 0;
112 acc = 0;
113 }
114 }
115
116 ctx->acc = acc;
117 ctx->qsz = qsz;
118 } else {
119 unsigned long acc = ctx->acc;
120 unsigned qsz = ctx->qsz;
121
122 switch (qsz) {
123 case 0:
124 break;
125 case 1:
126 acc <<= 16;
c601c4f1 127 DPUTC(d, base64_encodeMap[(acc >> 18) & 0x3f]);
128 DPUTC(d, base64_encodeMap[(acc >> 12) & 0x3f]);
129 DPUTC(d, '=');
130 DPUTC(d, '=');
ceba1986 131 ctx->lnlen += 4;
132 break;
133 case 2:
134 acc <<= 8;
c601c4f1 135 DPUTC(d, base64_encodeMap[(acc >> 18) & 0x3f]);
136 DPUTC(d, base64_encodeMap[(acc >> 12) & 0x3f]);
137 DPUTC(d, base64_encodeMap[(acc >> 6) & 0x3f]);
138 DPUTC(d, '=');
ceba1986 139 ctx->lnlen += 4;
140 break;
141 }
142 ctx->qsz = 0;
143 ctx->acc = 0;
144 }
145}
146
147/* --- @base64_decode@ --- *
148 *
149 * Arguments: @base64_ctx *ctx@ = pointer to a context block
c601c4f1 150 * @const void *p@ = pointer to a source buffer
ceba1986 151 * @size_t sz@ = size of the source buffer
152 * @dstr *d@ = pointer to destination string
153 *
154 * Returns: ---
155 *
156 * Use: Decodes a binary string in base64. To flush out the final
157 * few characters (if necessary), pass a null source pointer.
158 */
159
160void base64_decode(base64_ctx *ctx,
c601c4f1 161 const void *p, size_t sz,
ceba1986 162 dstr *d)
163{
c601c4f1 164 if (p) {
ceba1986 165 unsigned long acc = ctx->acc;
166 unsigned qsz = ctx->qsz;
c601c4f1 167 const char *src = p;
ceba1986 168 int ch;
169
170 while (sz) {
171
172 /* --- Get the next character and convert it --- */
173
174 ch = *src++;
175 if (ch >= 128 || ch < 0)
176 ch = -1;
177 else
178 ch = base64_decodeMap[ch];
179 sz--;
180 if (ch == -1)
181 continue;
182
183 /* --- Bung it in the accumulator --- */
184
185 acc = (acc << 6) | ch;
186 qsz++;
187
188 /* --- Maybe write out a completed triplet --- */
189
190 if (qsz == 4) {
c601c4f1 191 DPUTC(d, (acc >> 16) & 0xff);
192 DPUTC(d, (acc >> 8) & 0xff);
193 DPUTC(d, (acc >> 0) & 0xff);
ceba1986 194 acc = 0;
195 qsz = 0;
196 }
197 }
198
199 ctx->acc = acc;
200 ctx->qsz = qsz;
201 } else {
202
203 /* --- Notes about the tail-end bits --- *
204 *
205 * Ending Base64 decoding is messy. The reference I'm using to define
206 * the encoding, RFC1521 section 5.2, is a little hazy on exactly what to
207 * do at the end. It explains that I'm meant to ignore spurious `='
208 * characters, and points out that I'm not guaranteed to see anything
209 * interesting at the end. I'll play safe here, and ignore all `='
210 * characters, relying on my client to work out when to stop feeding me
211 * data. I'll use the queue size to work out how many tail-end bytes
212 * I ought to write.
213 */
214
215 unsigned long acc = ctx->acc;
216 unsigned qsz = ctx->qsz;
217
a226592f 218 /* --- Now fiddle with everything else --- *
219 *
220 * There's a bodge here for invalid encodings which have only one hextet
221 * in the final group. I'm not sure this is really worth having, but it
222 * might save some unexpected behaviour. (Not that you won't still get
223 * unexpected behaviour if the stream is completely empty, of course.)
224 */
ceba1986 225
a226592f 226 if (qsz) {
227 acc <<= 6 * (4 - qsz);
228 qsz *= 6;
229 if (qsz < 8)
230 qsz = 8;
231 while (qsz >= 8) {
232 DPUTC(d, (acc >> 16) & 0xff);
233 acc <<= 8;
234 qsz -= 8;
235 }
ceba1986 236 }
237
238 /* --- That seems to be good enough --- */
239
240 ctx->qsz = 0;
241 ctx->acc = 0;
242 }
243}
244
245/* --- @base64_init@ --- *
246 *
247 * Arguments: @base64_ctx *ctx@ = pointer to context block to initialize
248 *
249 * Returns: ---
250 *
251 * Use: Initializes a base64 context properly.
252 */
253
254void base64_init(base64_ctx *ctx)
255{
256 ctx->acc = 0;
257 ctx->qsz = 0;
258 ctx->lnlen = 0;
259 ctx->indent = "\n";
260 ctx->maxline = 72;
261}
262
263/*----- Test driver code --------------------------------------------------*/
264
265#ifdef TEST_RIG
266
267int main(int argc, char *argv[])
268{
269 unsigned char buf[BUFSIZ];
0bfb1431 270 dstr d = DSTR_INIT;
ceba1986 271 base64_ctx ctx;
272 void (*proc)(base64_ctx *, const unsigned char *, size_t, dstr *);
273 size_t sz;
274
ceba1986 275 base64_init(&ctx);
276
277 if (argc > 1 && strcmp(argv[1], "-d") == 0)
278 proc = base64_decode;
279 else {
280 proc = base64_encode;
281 putchar('\t');
282 ctx.indent = "\n\t";
283 ctx.maxline = 64;
284 }
285
286 do {
287 sz = fread(buf, 1, sizeof(buf), stdin);
288 if (sz) {
289 proc(&ctx, buf, sz, &d);
290 dstr_write(&d, stdout);
291 dstr_destroy(&d);
292 }
293 } while (sz == sizeof(buf));
294
295 proc(&ctx, 0, 0, &d);
296 dstr_write(&d, stdout);
297
298 if (proc == base64_encode)
299 putchar('\n');
300
301 return (0);
302}
303
304#endif
305
306/*----- That's all, folks -------------------------------------------------*/