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url: Allow `;' to separate key/value pairs in URL-encoded strings.
[mLib] / base64.c
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ceba1986 1/* -*-c-*-
2 *
8656dc50 3 * $Id: base64.c,v 1.7 2004/04/08 01:36:11 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
ceba1986 30/*----- Header files ------------------------------------------------------*/
31
32#include <stdio.h>
33#include <stdlib.h>
34#include <string.h>
35
36#include "base64.h"
37#include "dstr.h"
38
39/*----- Important tables --------------------------------------------------*/
40
fde30071 41static const char encodemap[] = { "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
42 "abcdefghijklmnopqrstuvwxyz"
43 "0123456789+/" };
ceba1986 44
fde30071 45static const signed char decodemap[] = {
ceba1986 46 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 0x */
47 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 1x */
48 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, /* 2x */
49 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, /* 3x */
50 -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, /* 4x */
51 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, /* 5x */
52 -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36 ,37, 38, 39, 40, /* 6x */
53 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1 /* 7x */
54};
55
56/*----- Main code ---------------------------------------------------------*/
57
58/* --- @base64_encode@ --- *
59 *
60 * Arguments: @base64_ctx *ctx@ = pointer to a context block
c601c4f1 61 * @const void *p@ = pointer to a source buffer
ceba1986 62 * @size_t sz@ = size of the source buffer
63 * @dstr *d@ = pointer to destination string
64 *
65 * Returns: ---
66 *
67 * Use: Encodes a binary string in base64. To flush out the final
68 * few characters (if necessary), pass a null source pointer.
69 */
70
71void base64_encode(base64_ctx *ctx,
c601c4f1 72 const void *p, size_t sz,
ceba1986 73 dstr *d)
74{
c601c4f1 75 if (p) {
ceba1986 76 unsigned long acc = ctx->acc;
77 unsigned qsz = ctx->qsz;
c601c4f1 78 const unsigned char *src = p;
ceba1986 79
80 while (sz) {
81 acc = (acc << 8) | *src++;
82 qsz++;
83 sz--;
84 if (qsz == 3) {
fde30071 85 DPUTC(d, encodemap[(acc >> 18) & 0x3f]);
86 DPUTC(d, encodemap[(acc >> 12) & 0x3f]);
87 DPUTC(d, encodemap[(acc >> 6) & 0x3f]);
88 DPUTC(d, encodemap[(acc >> 0) & 0x3f]);
ceba1986 89 ctx->lnlen += 4;
90 if (ctx->maxline && ctx->lnlen >= ctx->maxline) {
91 dstr_puts(d, ctx->indent);
92 ctx->lnlen = 0;
93 }
94 qsz = 0;
95 acc = 0;
96 }
97 }
98
99 ctx->acc = acc;
100 ctx->qsz = qsz;
101 } else {
102 unsigned long acc = ctx->acc;
103 unsigned qsz = ctx->qsz;
104
105 switch (qsz) {
106 case 0:
107 break;
108 case 1:
109 acc <<= 16;
fde30071 110 DPUTC(d, encodemap[(acc >> 18) & 0x3f]);
111 DPUTC(d, encodemap[(acc >> 12) & 0x3f]);
c601c4f1 112 DPUTC(d, '=');
113 DPUTC(d, '=');
ceba1986 114 ctx->lnlen += 4;
115 break;
116 case 2:
117 acc <<= 8;
fde30071 118 DPUTC(d, encodemap[(acc >> 18) & 0x3f]);
119 DPUTC(d, encodemap[(acc >> 12) & 0x3f]);
120 DPUTC(d, encodemap[(acc >> 6) & 0x3f]);
c601c4f1 121 DPUTC(d, '=');
ceba1986 122 ctx->lnlen += 4;
123 break;
124 }
125 ctx->qsz = 0;
126 ctx->acc = 0;
127 }
128}
129
130/* --- @base64_decode@ --- *
131 *
132 * Arguments: @base64_ctx *ctx@ = pointer to a context block
c601c4f1 133 * @const void *p@ = pointer to a source buffer
ceba1986 134 * @size_t sz@ = size of the source buffer
135 * @dstr *d@ = pointer to destination string
136 *
137 * Returns: ---
138 *
139 * Use: Decodes a binary string in base64. To flush out the final
140 * few characters (if necessary), pass a null source pointer.
141 */
142
143void base64_decode(base64_ctx *ctx,
c601c4f1 144 const void *p, size_t sz,
ceba1986 145 dstr *d)
146{
c601c4f1 147 if (p) {
ceba1986 148 unsigned long acc = ctx->acc;
149 unsigned qsz = ctx->qsz;
c601c4f1 150 const char *src = p;
ceba1986 151 int ch;
152
153 while (sz) {
154
155 /* --- Get the next character and convert it --- */
156
157 ch = *src++;
158 if (ch >= 128 || ch < 0)
159 ch = -1;
160 else
fde30071 161 ch = decodemap[ch];
ceba1986 162 sz--;
163 if (ch == -1)
164 continue;
165
166 /* --- Bung it in the accumulator --- */
167
168 acc = (acc << 6) | ch;
169 qsz++;
170
171 /* --- Maybe write out a completed triplet --- */
172
173 if (qsz == 4) {
c601c4f1 174 DPUTC(d, (acc >> 16) & 0xff);
175 DPUTC(d, (acc >> 8) & 0xff);
176 DPUTC(d, (acc >> 0) & 0xff);
ceba1986 177 acc = 0;
178 qsz = 0;
179 }
180 }
181
182 ctx->acc = acc;
183 ctx->qsz = qsz;
184 } else {
185
186 /* --- Notes about the tail-end bits --- *
187 *
188 * Ending Base64 decoding is messy. The reference I'm using to define
189 * the encoding, RFC1521 section 5.2, is a little hazy on exactly what to
190 * do at the end. It explains that I'm meant to ignore spurious `='
191 * characters, and points out that I'm not guaranteed to see anything
192 * interesting at the end. I'll play safe here, and ignore all `='
193 * characters, relying on my client to work out when to stop feeding me
194 * data. I'll use the queue size to work out how many tail-end bytes
195 * I ought to write.
196 */
197
198 unsigned long acc = ctx->acc;
199 unsigned qsz = ctx->qsz;
200
a226592f 201 /* --- Now fiddle with everything else --- *
202 *
203 * There's a bodge here for invalid encodings which have only one hextet
204 * in the final group. I'm not sure this is really worth having, but it
205 * might save some unexpected behaviour. (Not that you won't still get
206 * unexpected behaviour if the stream is completely empty, of course.)
207 */
ceba1986 208
a226592f 209 if (qsz) {
210 acc <<= 6 * (4 - qsz);
211 qsz *= 6;
212 if (qsz < 8)
213 qsz = 8;
214 while (qsz >= 8) {
215 DPUTC(d, (acc >> 16) & 0xff);
216 acc <<= 8;
217 qsz -= 8;
218 }
ceba1986 219 }
220
221 /* --- That seems to be good enough --- */
222
223 ctx->qsz = 0;
224 ctx->acc = 0;
225 }
226}
227
228/* --- @base64_init@ --- *
229 *
230 * Arguments: @base64_ctx *ctx@ = pointer to context block to initialize
231 *
232 * Returns: ---
233 *
234 * Use: Initializes a base64 context properly.
235 */
236
237void base64_init(base64_ctx *ctx)
238{
239 ctx->acc = 0;
240 ctx->qsz = 0;
241 ctx->lnlen = 0;
242 ctx->indent = "\n";
243 ctx->maxline = 72;
244}
245
246/*----- Test driver code --------------------------------------------------*/
247
248#ifdef TEST_RIG
249
250int main(int argc, char *argv[])
251{
252 unsigned char buf[BUFSIZ];
0bfb1431 253 dstr d = DSTR_INIT;
ceba1986 254 base64_ctx ctx;
d5679ed0 255 void (*proc)(base64_ctx *, const void *, size_t, dstr *);
ceba1986 256 size_t sz;
257
ceba1986 258 base64_init(&ctx);
259
260 if (argc > 1 && strcmp(argv[1], "-d") == 0)
261 proc = base64_decode;
262 else {
263 proc = base64_encode;
264 putchar('\t');
265 ctx.indent = "\n\t";
266 ctx.maxline = 64;
267 }
268
269 do {
270 sz = fread(buf, 1, sizeof(buf), stdin);
271 if (sz) {
272 proc(&ctx, buf, sz, &d);
273 dstr_write(&d, stdout);
274 dstr_destroy(&d);
275 }
276 } while (sz == sizeof(buf));
277
278 proc(&ctx, 0, 0, &d);
279 dstr_write(&d, stdout);
280
281 if (proc == base64_encode)
282 putchar('\n');
283
284 return (0);
285}
286
287#endif
288
289/*----- That's all, folks -------------------------------------------------*/