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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: base64.c,v 1.3 1999/05/21 22:14:30 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 $ |
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33 | * Revision 1.3 1999/05/21 22:14:30 mdw |
34 | * Take advantage of the new dynamic string macros. |
35 | * |
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36 | * Revision 1.2 1999/05/18 21:45:27 mdw |
37 | * Allow Base64 encode and decode of arbitrary rubbish. |
38 | * |
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39 | * Revision 1.1 1999/05/17 20:35:00 mdw |
40 | * Base64 encoding and decoding support. |
41 | * |
42 | */ |
43 | |
44 | /*----- Header files ------------------------------------------------------*/ |
45 | |
46 | #include <stdio.h> |
47 | #include <stdlib.h> |
48 | #include <string.h> |
49 | |
50 | #include "base64.h" |
51 | #include "dstr.h" |
52 | |
53 | /*----- Important tables --------------------------------------------------*/ |
54 | |
55 | static const char base64_encodeMap[] = { "ABCDEFGHIJKLMNOPQRSTUVWXYZ" |
56 | "abcdefghijklmnopqrstuvwxyz" |
57 | "0123456789+/" }; |
58 | |
59 | static const signed char base64_decodeMap[] = { |
60 | -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 0x */ |
61 | -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 1x */ |
62 | -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, /* 2x */ |
63 | 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, /* 3x */ |
64 | -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, /* 4x */ |
65 | 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, /* 5x */ |
66 | -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36 ,37, 38, 39, 40, /* 6x */ |
67 | 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1 /* 7x */ |
68 | }; |
69 | |
70 | /*----- Main code ---------------------------------------------------------*/ |
71 | |
72 | /* --- @base64_encode@ --- * |
73 | * |
74 | * Arguments: @base64_ctx *ctx@ = pointer to a context block |
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75 | * @const void *p@ = pointer to a source buffer |
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76 | * @size_t sz@ = size of the source buffer |
77 | * @dstr *d@ = pointer to destination string |
78 | * |
79 | * Returns: --- |
80 | * |
81 | * Use: Encodes a binary string in base64. To flush out the final |
82 | * few characters (if necessary), pass a null source pointer. |
83 | */ |
84 | |
85 | void base64_encode(base64_ctx *ctx, |
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86 | const void *p, size_t sz, |
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87 | dstr *d) |
88 | { |
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89 | if (p) { |
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90 | unsigned long acc = ctx->acc; |
91 | unsigned qsz = ctx->qsz; |
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92 | const unsigned char *src = p; |
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93 | |
94 | while (sz) { |
95 | acc = (acc << 8) | *src++; |
96 | qsz++; |
97 | sz--; |
98 | if (qsz == 3) { |
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99 | DPUTC(d, base64_encodeMap[(acc >> 18) & 0x3f]); |
100 | DPUTC(d, base64_encodeMap[(acc >> 12) & 0x3f]); |
101 | DPUTC(d, base64_encodeMap[(acc >> 6) & 0x3f]); |
102 | DPUTC(d, base64_encodeMap[(acc >> 0) & 0x3f]); |
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103 | ctx->lnlen += 4; |
104 | if (ctx->maxline && ctx->lnlen >= ctx->maxline) { |
105 | dstr_puts(d, ctx->indent); |
106 | ctx->lnlen = 0; |
107 | } |
108 | qsz = 0; |
109 | acc = 0; |
110 | } |
111 | } |
112 | |
113 | ctx->acc = acc; |
114 | ctx->qsz = qsz; |
115 | } else { |
116 | unsigned long acc = ctx->acc; |
117 | unsigned qsz = ctx->qsz; |
118 | |
119 | switch (qsz) { |
120 | case 0: |
121 | break; |
122 | case 1: |
123 | acc <<= 16; |
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124 | DPUTC(d, base64_encodeMap[(acc >> 18) & 0x3f]); |
125 | DPUTC(d, base64_encodeMap[(acc >> 12) & 0x3f]); |
126 | DPUTC(d, '='); |
127 | DPUTC(d, '='); |
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128 | ctx->lnlen += 4; |
129 | break; |
130 | case 2: |
131 | acc <<= 8; |
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132 | DPUTC(d, base64_encodeMap[(acc >> 18) & 0x3f]); |
133 | DPUTC(d, base64_encodeMap[(acc >> 12) & 0x3f]); |
134 | DPUTC(d, base64_encodeMap[(acc >> 6) & 0x3f]); |
135 | DPUTC(d, '='); |
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136 | ctx->lnlen += 4; |
137 | break; |
138 | } |
139 | ctx->qsz = 0; |
140 | ctx->acc = 0; |
141 | } |
142 | } |
143 | |
144 | /* --- @base64_decode@ --- * |
145 | * |
146 | * Arguments: @base64_ctx *ctx@ = pointer to a context block |
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147 | * @const void *p@ = pointer to a source buffer |
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148 | * @size_t sz@ = size of the source buffer |
149 | * @dstr *d@ = pointer to destination string |
150 | * |
151 | * Returns: --- |
152 | * |
153 | * Use: Decodes a binary string in base64. To flush out the final |
154 | * few characters (if necessary), pass a null source pointer. |
155 | */ |
156 | |
157 | void base64_decode(base64_ctx *ctx, |
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158 | const void *p, size_t sz, |
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159 | dstr *d) |
160 | { |
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161 | if (p) { |
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162 | unsigned long acc = ctx->acc; |
163 | unsigned qsz = ctx->qsz; |
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164 | const char *src = p; |
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165 | int ch; |
166 | |
167 | while (sz) { |
168 | |
169 | /* --- Get the next character and convert it --- */ |
170 | |
171 | ch = *src++; |
172 | if (ch >= 128 || ch < 0) |
173 | ch = -1; |
174 | else |
175 | ch = base64_decodeMap[ch]; |
176 | sz--; |
177 | if (ch == -1) |
178 | continue; |
179 | |
180 | /* --- Bung it in the accumulator --- */ |
181 | |
182 | acc = (acc << 6) | ch; |
183 | qsz++; |
184 | |
185 | /* --- Maybe write out a completed triplet --- */ |
186 | |
187 | if (qsz == 4) { |
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188 | DPUTC(d, (acc >> 16) & 0xff); |
189 | DPUTC(d, (acc >> 8) & 0xff); |
190 | DPUTC(d, (acc >> 0) & 0xff); |
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191 | acc = 0; |
192 | qsz = 0; |
193 | } |
194 | } |
195 | |
196 | ctx->acc = acc; |
197 | ctx->qsz = qsz; |
198 | } else { |
199 | |
200 | /* --- Notes about the tail-end bits --- * |
201 | * |
202 | * Ending Base64 decoding is messy. The reference I'm using to define |
203 | * the encoding, RFC1521 section 5.2, is a little hazy on exactly what to |
204 | * do at the end. It explains that I'm meant to ignore spurious `=' |
205 | * characters, and points out that I'm not guaranteed to see anything |
206 | * interesting at the end. I'll play safe here, and ignore all `=' |
207 | * characters, relying on my client to work out when to stop feeding me |
208 | * data. I'll use the queue size to work out how many tail-end bytes |
209 | * I ought to write. |
210 | */ |
211 | |
212 | unsigned long acc = ctx->acc; |
213 | unsigned qsz = ctx->qsz; |
214 | |
215 | /* --- Now fiddle with everything else --- */ |
216 | |
217 | acc <<= 6 * (4 - qsz); |
218 | qsz *= 6; |
219 | while (qsz > 8) { |
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220 | DPUTC(d, (acc >> 16) & 0xff); |
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221 | acc <<= 8; |
222 | qsz -= 8; |
223 | } |
224 | |
225 | /* --- That seems to be good enough --- */ |
226 | |
227 | ctx->qsz = 0; |
228 | ctx->acc = 0; |
229 | } |
230 | } |
231 | |
232 | /* --- @base64_init@ --- * |
233 | * |
234 | * Arguments: @base64_ctx *ctx@ = pointer to context block to initialize |
235 | * |
236 | * Returns: --- |
237 | * |
238 | * Use: Initializes a base64 context properly. |
239 | */ |
240 | |
241 | void base64_init(base64_ctx *ctx) |
242 | { |
243 | ctx->acc = 0; |
244 | ctx->qsz = 0; |
245 | ctx->lnlen = 0; |
246 | ctx->indent = "\n"; |
247 | ctx->maxline = 72; |
248 | } |
249 | |
250 | /*----- Test driver code --------------------------------------------------*/ |
251 | |
252 | #ifdef TEST_RIG |
253 | |
254 | int main(int argc, char *argv[]) |
255 | { |
256 | unsigned char buf[BUFSIZ]; |
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257 | dstr d = DSTR_INIT; |
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258 | base64_ctx ctx; |
259 | void (*proc)(base64_ctx *, const unsigned char *, size_t, dstr *); |
260 | size_t sz; |
261 | |
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262 | base64_init(&ctx); |
263 | |
264 | if (argc > 1 && strcmp(argv[1], "-d") == 0) |
265 | proc = base64_decode; |
266 | else { |
267 | proc = base64_encode; |
268 | putchar('\t'); |
269 | ctx.indent = "\n\t"; |
270 | ctx.maxline = 64; |
271 | } |
272 | |
273 | do { |
274 | sz = fread(buf, 1, sizeof(buf), stdin); |
275 | if (sz) { |
276 | proc(&ctx, buf, sz, &d); |
277 | dstr_write(&d, stdout); |
278 | dstr_destroy(&d); |
279 | } |
280 | } while (sz == sizeof(buf)); |
281 | |
282 | proc(&ctx, 0, 0, &d); |
283 | dstr_write(&d, stdout); |
284 | |
285 | if (proc == base64_encode) |
286 | putchar('\n'); |
287 | |
288 | return (0); |
289 | } |
290 | |
291 | #endif |
292 | |
293 | /*----- That's all, folks -------------------------------------------------*/ |