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1 | /* -*-c-*- |
2 | * |
3 | * $Id$ |
4 | * |
5 | * Base32 encoding and decoding. |
6 | * |
7 | * (c) 1997 Straylight/Edgeware |
8 | */ |
9 | |
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10 | /*----- Licensing notice --------------------------------------------------* |
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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. |
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18 | * |
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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. |
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23 | * |
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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 | /*----- Header files ------------------------------------------------------*/ |
31 | |
32 | #include <stdio.h> |
33 | #include <stdlib.h> |
34 | #include <string.h> |
35 | |
36 | #include "base32.h" |
37 | #include "dstr.h" |
38 | |
39 | /*----- Important tables --------------------------------------------------*/ |
40 | |
41 | static const char encodemap[] = { "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567" }; |
42 | |
43 | static const signed char decodemap[] = { |
44 | -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 0x */ |
45 | -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 1x */ |
46 | -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 2x */ |
47 | -1, -1, 26, 27, 28, 29, 30, 31, -1, -1, -1, -1, -1, -1, -1, -1, /* 3x */ |
48 | -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, /* 4x */ |
49 | 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, /* 5x */ |
50 | -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, /* 6x */ |
51 | 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, /* 7x */ |
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52 | }; |
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53 | |
54 | /*----- Main code ---------------------------------------------------------*/ |
55 | |
56 | /* --- @base32_encode@ --- * |
57 | * |
58 | * Arguments: @base32_ctx *ctx@ = pointer to a context block |
59 | * @const void *p@ = pointer to a source buffer |
60 | * @size_t sz@ = size of the source buffer |
61 | * @dstr *d@ = pointer to destination string |
62 | * |
63 | * Returns: --- |
64 | * |
65 | * Use: Encodes a binary string in base32. To flush out the final |
66 | * few characters (if necessary), pass a null source pointer. |
67 | */ |
68 | |
69 | void base32_encode(base32_ctx *ctx, |
70 | const void *p, size_t sz, |
71 | dstr *d) |
72 | { |
73 | if (p) { |
74 | unsigned long accl = ctx->accl, acch = ctx->acch; |
75 | unsigned qsz = ctx->qsz; |
76 | const unsigned char *src = p; |
77 | |
78 | while (sz) { |
79 | acch = (acch << 8) | ((accl >> 24) & 0xff); |
80 | accl = (accl << 8) | *src++; |
81 | qsz++; |
82 | sz--; |
83 | if (qsz == 5) { |
84 | DPUTC(d, encodemap[(acch >> 3) & 0x1f]); |
85 | DPUTC(d, encodemap[((acch << 2) & 0x1c) | ((accl >> 30) & 0x03)]); |
86 | DPUTC(d, encodemap[(accl >> 25) & 0x1f]); |
87 | DPUTC(d, encodemap[(accl >> 20) & 0x1f]); |
88 | DPUTC(d, encodemap[(accl >> 15) & 0x1f]); |
89 | DPUTC(d, encodemap[(accl >> 10) & 0x1f]); |
90 | DPUTC(d, encodemap[(accl >> 5) & 0x1f]); |
91 | DPUTC(d, encodemap[(accl >> 0) & 0x1f]); |
92 | ctx->lnlen += 8; |
93 | if (ctx->maxline && ctx->lnlen >= ctx->maxline) { |
94 | dstr_puts(d, ctx->indent); |
95 | ctx->lnlen = 0; |
96 | } |
97 | qsz = 0; |
98 | accl = acch = 0; |
99 | } |
100 | } |
101 | |
102 | ctx->acch = acch; ctx->accl = accl; |
103 | ctx->qsz = qsz; |
104 | } else { |
105 | unsigned long accl = ctx->accl, acch = ctx->acch; |
106 | unsigned qsz = ctx->qsz; |
107 | |
108 | if (qsz) { |
109 | unsigned pad = 5 - qsz; |
110 | if (pad > 3) { |
111 | acch = accl << (pad * 8 - 32); |
112 | accl = 0; |
113 | } else { |
114 | acch = (acch << (8 * pad)) | ((accl & 0xffffffff) >> (32 - 8 * pad)); |
115 | accl = accl << (8 * pad); |
116 | } |
117 | qsz = 40; |
118 | pad *= 8; |
119 | while (qsz > pad) { |
120 | DPUTC(d, encodemap[(acch >> 3) & 0x1f]); |
121 | acch = (acch << 5) | ((accl >> 27) & 0x1f); |
122 | accl = (accl << 5); |
123 | qsz -= 5; |
124 | } |
125 | while (qsz) { |
126 | DPUTC(d, '='); |
127 | qsz -= 5; |
128 | } |
129 | ctx->lnlen += 8; |
130 | } |
131 | ctx->qsz = 0; |
132 | ctx->acch = ctx->accl = 0; |
133 | } |
134 | } |
135 | |
136 | /* --- @base32_decode@ --- * |
137 | * |
138 | * Arguments: @base32_ctx *ctx@ = pointer to a context block |
139 | * @const void *p@ = pointer to a source buffer |
140 | * @size_t sz@ = size of the source buffer |
141 | * @dstr *d@ = pointer to destination string |
142 | * |
143 | * Returns: --- |
144 | * |
145 | * Use: Decodes a binary string in base32. To flush out the final |
146 | * few characters (if necessary), pass a null source pointer. |
147 | */ |
148 | |
149 | void base32_decode(base32_ctx *ctx, |
150 | const void *p, size_t sz, |
151 | dstr *d) |
152 | { |
153 | if (p) { |
154 | unsigned long accl = ctx->accl, acch = ctx->acch; |
155 | unsigned qsz = ctx->qsz; |
156 | const char *src = p; |
157 | int ch; |
158 | |
159 | while (sz) { |
160 | |
161 | /* --- Get the next character and convert it --- */ |
162 | |
163 | ch = *src++; |
164 | if (ch >= 128 || ch < 0) |
165 | ch = -1; |
166 | else |
167 | ch = decodemap[ch]; |
168 | sz--; |
169 | if (ch == -1) |
170 | continue; |
171 | |
172 | /* --- Bung it in the accumulator --- */ |
173 | |
174 | acch = (acch << 5) | ((accl >> 27) & 0x1f); |
175 | accl = (accl << 5) | ch; |
176 | qsz++; |
177 | |
178 | /* --- Maybe write out a completed triplet --- */ |
179 | |
180 | if (qsz == 8) { |
181 | DPUTC(d, (acch >> 0) & 0xff); |
182 | DPUTC(d, (accl >> 24) & 0xff); |
183 | DPUTC(d, (accl >> 16) & 0xff); |
184 | DPUTC(d, (accl >> 8) & 0xff); |
185 | DPUTC(d, (accl >> 0) & 0xff); |
186 | acch = accl = 0; |
187 | qsz = 0; |
188 | } |
189 | } |
190 | |
191 | ctx->acch = acch; ctx->accl = accl; |
192 | ctx->qsz = qsz; |
193 | } else { |
194 | |
195 | /* --- Notes about the tail-end bits --- * |
196 | * |
197 | * I'll use the queue size to work out how many tail-end bytes I ought to |
198 | * write. This isn't strictly right, but it's easier. |
199 | */ |
200 | |
201 | unsigned long acch = ctx->acch, accl = ctx->accl; |
202 | unsigned qsz = ctx->qsz; |
203 | |
204 | /* --- Now fiddle with everything else --- * |
205 | * |
206 | * There's a bodge here for invalid encodings which have a funny number |
207 | * of quintets in the final group. I'm not sure this is really worth |
208 | * having, but it might save some unexpected behaviour. (Not that you |
209 | * won't still get unexpected behaviour if the stream is completely |
210 | * empty, of course.) |
211 | */ |
212 | |
213 | if (qsz) { |
214 | unsigned pad = 8 - qsz; |
215 | if (pad > 6) { |
216 | acch = accl << (5 * pad - 32); |
217 | accl = 0; |
218 | } else { |
219 | acch = (acch << (5 * pad)) | ((accl & 0xffffffff) >> (32 - 5 * pad)); |
220 | accl = accl << (5 * pad); |
221 | } |
222 | |
223 | qsz *= 5; |
224 | while (qsz >= 8) { |
225 | DPUTC(d, acch & 0xff); |
226 | acch = accl >> 24; |
227 | accl <<= 8; |
228 | qsz -= 8; |
229 | } |
230 | } |
231 | |
232 | /* --- That seems to be good enough --- */ |
233 | |
234 | ctx->qsz = 0; |
235 | ctx->acch = ctx->accl = 0; |
236 | } |
237 | } |
238 | |
239 | /* --- @base32_init@ --- * |
240 | * |
241 | * Arguments: @base32_ctx *ctx@ = pointer to context block to initialize |
242 | * |
243 | * Returns: --- |
244 | * |
245 | * Use: Initializes a base32 context properly. |
246 | */ |
247 | |
248 | void base32_init(base32_ctx *ctx) |
249 | { |
250 | ctx->accl = ctx->acch = 0; |
251 | ctx->qsz = 0; |
252 | ctx->lnlen = 0; |
253 | ctx->indent = "\n"; |
254 | ctx->maxline = 72; |
255 | } |
256 | |
257 | /*----- Test driver code --------------------------------------------------*/ |
258 | |
259 | #ifdef TEST_RIG |
260 | |
261 | int main(int argc, char *argv[]) |
262 | { |
263 | unsigned char buf[BUFSIZ]; |
264 | dstr d = DSTR_INIT; |
265 | base32_ctx ctx; |
266 | void (*proc)(base32_ctx *, const void *, size_t, dstr *); |
267 | size_t sz; |
268 | |
269 | base32_init(&ctx); |
270 | |
271 | if (argc > 1 && strcmp(argv[1], "-d") == 0) |
272 | proc = base32_decode; |
273 | else { |
274 | proc = base32_encode; |
275 | putchar('\t'); |
276 | ctx.indent = "\n\t"; |
277 | ctx.maxline = 32; |
278 | } |
279 | |
280 | do { |
281 | sz = fread(buf, 1, sizeof(buf), stdin); |
282 | if (sz) { |
283 | proc(&ctx, buf, sz, &d); |
284 | dstr_write(&d, stdout); |
285 | dstr_destroy(&d); |
286 | } |
287 | } while (sz == sizeof(buf)); |
288 | |
289 | proc(&ctx, 0, 0, &d); |
290 | dstr_write(&d, stdout); |
291 | |
292 | if (proc == base32_encode) |
293 | putchar('\n'); |
294 | |
295 | return (0); |
296 | } |
297 | |
298 | #endif |
299 | |
300 | /*----- That's all, folks -------------------------------------------------*/ |