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 |
41 | static const char encodemap[] = { "ABCDEFGHIJKLMNOPQRSTUVWXYZ" |
42 | "abcdefghijklmnopqrstuvwxyz" |
43 | "0123456789+/" }; |
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44 | |
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45 | static const signed char decodemap[] = { |
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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 | |
71 | void base64_encode(base64_ctx *ctx, |
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72 | const void *p, size_t sz, |
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73 | dstr *d) |
74 | { |
c601c4f1 |
75 | if (p) { |
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76 | unsigned long acc = ctx->acc; |
77 | unsigned qsz = ctx->qsz; |
c601c4f1 |
78 | const unsigned char *src = p; |
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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]); |
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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; |
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110 | DPUTC(d, encodemap[(acc >> 18) & 0x3f]); |
111 | DPUTC(d, encodemap[(acc >> 12) & 0x3f]); |
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112 | DPUTC(d, '='); |
113 | DPUTC(d, '='); |
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114 | ctx->lnlen += 4; |
115 | break; |
116 | case 2: |
117 | acc <<= 8; |
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118 | DPUTC(d, encodemap[(acc >> 18) & 0x3f]); |
119 | DPUTC(d, encodemap[(acc >> 12) & 0x3f]); |
120 | DPUTC(d, encodemap[(acc >> 6) & 0x3f]); |
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121 | DPUTC(d, '='); |
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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 |
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133 | * @const void *p@ = pointer to a source buffer |
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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 | |
143 | void base64_decode(base64_ctx *ctx, |
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144 | const void *p, size_t sz, |
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145 | dstr *d) |
146 | { |
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147 | if (p) { |
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148 | unsigned long acc = ctx->acc; |
149 | unsigned qsz = ctx->qsz; |
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150 | const char *src = p; |
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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 |
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161 | ch = decodemap[ch]; |
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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) { |
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174 | DPUTC(d, (acc >> 16) & 0xff); |
175 | DPUTC(d, (acc >> 8) & 0xff); |
176 | DPUTC(d, (acc >> 0) & 0xff); |
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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 | */ |
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208 | |
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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 | } |
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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 | |
237 | void 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 | |
250 | int main(int argc, char *argv[]) |
251 | { |
252 | unsigned char buf[BUFSIZ]; |
0bfb1431 |
253 | dstr d = DSTR_INIT; |
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254 | base64_ctx ctx; |
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255 | void (*proc)(base64_ctx *, const void *, size_t, dstr *); |
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256 | size_t sz; |
257 | |
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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 -------------------------------------------------*/ |