ceba1986 |
1 | /* -*-c-*- |
2 | * |
3 | * $Id: base64.c,v 1.1 1999/05/17 20:35:00 mdw Exp $ |
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 $ |
33 | * Revision 1.1 1999/05/17 20:35:00 mdw |
34 | * Base64 encoding and decoding support. |
35 | * |
36 | */ |
37 | |
38 | /*----- Header files ------------------------------------------------------*/ |
39 | |
40 | #include <stdio.h> |
41 | #include <stdlib.h> |
42 | #include <string.h> |
43 | |
44 | #include "base64.h" |
45 | #include "dstr.h" |
46 | |
47 | /*----- Important tables --------------------------------------------------*/ |
48 | |
49 | static const char base64_encodeMap[] = { "ABCDEFGHIJKLMNOPQRSTUVWXYZ" |
50 | "abcdefghijklmnopqrstuvwxyz" |
51 | "0123456789+/" }; |
52 | |
53 | static const signed char base64_decodeMap[] = { |
54 | -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 0x */ |
55 | -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /* 1x */ |
56 | -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, /* 2x */ |
57 | 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, /* 3x */ |
58 | -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, /* 4x */ |
59 | 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, /* 5x */ |
60 | -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36 ,37, 38, 39, 40, /* 6x */ |
61 | 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1 /* 7x */ |
62 | }; |
63 | |
64 | /*----- Main code ---------------------------------------------------------*/ |
65 | |
66 | /* --- @base64_encode@ --- * |
67 | * |
68 | * Arguments: @base64_ctx *ctx@ = pointer to a context block |
69 | * @const unsigned char *src@ = pointer to a source buffer |
70 | * @size_t sz@ = size of the source buffer |
71 | * @dstr *d@ = pointer to destination string |
72 | * |
73 | * Returns: --- |
74 | * |
75 | * Use: Encodes a binary string in base64. To flush out the final |
76 | * few characters (if necessary), pass a null source pointer. |
77 | */ |
78 | |
79 | void base64_encode(base64_ctx *ctx, |
80 | const unsigned char *src, size_t sz, |
81 | dstr *d) |
82 | { |
83 | if (src) { |
84 | unsigned long acc = ctx->acc; |
85 | unsigned qsz = ctx->qsz; |
86 | |
87 | while (sz) { |
88 | acc = (acc << 8) | *src++; |
89 | qsz++; |
90 | sz--; |
91 | if (qsz == 3) { |
92 | dstr_putc(d, base64_encodeMap[(acc >> 18) & 0x3f]); |
93 | dstr_putc(d, base64_encodeMap[(acc >> 12) & 0x3f]); |
94 | dstr_putc(d, base64_encodeMap[(acc >> 6) & 0x3f]); |
95 | dstr_putc(d, base64_encodeMap[(acc >> 0) & 0x3f]); |
96 | ctx->lnlen += 4; |
97 | if (ctx->maxline && ctx->lnlen >= ctx->maxline) { |
98 | dstr_puts(d, ctx->indent); |
99 | ctx->lnlen = 0; |
100 | } |
101 | qsz = 0; |
102 | acc = 0; |
103 | } |
104 | } |
105 | |
106 | ctx->acc = acc; |
107 | ctx->qsz = qsz; |
108 | } else { |
109 | unsigned long acc = ctx->acc; |
110 | unsigned qsz = ctx->qsz; |
111 | |
112 | switch (qsz) { |
113 | case 0: |
114 | break; |
115 | case 1: |
116 | acc <<= 16; |
117 | dstr_putc(d, base64_encodeMap[(acc >> 18) & 0x3f]); |
118 | dstr_putc(d, base64_encodeMap[(acc >> 12) & 0x3f]); |
119 | dstr_putc(d, '='); |
120 | dstr_putc(d, '='); |
121 | ctx->lnlen += 4; |
122 | break; |
123 | case 2: |
124 | acc <<= 8; |
125 | dstr_putc(d, base64_encodeMap[(acc >> 18) & 0x3f]); |
126 | dstr_putc(d, base64_encodeMap[(acc >> 12) & 0x3f]); |
127 | dstr_putc(d, base64_encodeMap[(acc >> 6) & 0x3f]); |
128 | dstr_putc(d, '='); |
129 | ctx->lnlen += 4; |
130 | break; |
131 | } |
132 | ctx->qsz = 0; |
133 | ctx->acc = 0; |
134 | } |
135 | } |
136 | |
137 | /* --- @base64_decode@ --- * |
138 | * |
139 | * Arguments: @base64_ctx *ctx@ = pointer to a context block |
140 | * @const unsigned char *src@ = pointer to a source buffer |
141 | * @size_t sz@ = size of the source buffer |
142 | * @dstr *d@ = pointer to destination string |
143 | * |
144 | * Returns: --- |
145 | * |
146 | * Use: Decodes a binary string in base64. To flush out the final |
147 | * few characters (if necessary), pass a null source pointer. |
148 | */ |
149 | |
150 | void base64_decode(base64_ctx *ctx, |
151 | const unsigned char *src, size_t sz, |
152 | dstr *d) |
153 | { |
154 | if (src) { |
155 | unsigned long acc = ctx->acc; |
156 | unsigned qsz = ctx->qsz; |
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 = base64_decodeMap[ch]; |
168 | sz--; |
169 | if (ch == -1) |
170 | continue; |
171 | |
172 | /* --- Bung it in the accumulator --- */ |
173 | |
174 | acc = (acc << 6) | ch; |
175 | qsz++; |
176 | |
177 | /* --- Maybe write out a completed triplet --- */ |
178 | |
179 | if (qsz == 4) { |
180 | dstr_putc(d, (acc >> 16) & 0xff); |
181 | dstr_putc(d, (acc >> 8) & 0xff); |
182 | dstr_putc(d, (acc >> 0) & 0xff); |
183 | acc = 0; |
184 | qsz = 0; |
185 | } |
186 | } |
187 | |
188 | ctx->acc = acc; |
189 | ctx->qsz = qsz; |
190 | } else { |
191 | |
192 | /* --- Notes about the tail-end bits --- * |
193 | * |
194 | * Ending Base64 decoding is messy. The reference I'm using to define |
195 | * the encoding, RFC1521 section 5.2, is a little hazy on exactly what to |
196 | * do at the end. It explains that I'm meant to ignore spurious `=' |
197 | * characters, and points out that I'm not guaranteed to see anything |
198 | * interesting at the end. I'll play safe here, and ignore all `=' |
199 | * characters, relying on my client to work out when to stop feeding me |
200 | * data. I'll use the queue size to work out how many tail-end bytes |
201 | * I ought to write. |
202 | */ |
203 | |
204 | unsigned long acc = ctx->acc; |
205 | unsigned qsz = ctx->qsz; |
206 | |
207 | /* --- Now fiddle with everything else --- */ |
208 | |
209 | acc <<= 6 * (4 - qsz); |
210 | qsz *= 6; |
211 | while (qsz > 8) { |
212 | dstr_putc(d, (acc >> 16) & 0xff); |
213 | acc <<= 8; |
214 | qsz -= 8; |
215 | } |
216 | |
217 | /* --- That seems to be good enough --- */ |
218 | |
219 | ctx->qsz = 0; |
220 | ctx->acc = 0; |
221 | } |
222 | } |
223 | |
224 | /* --- @base64_init@ --- * |
225 | * |
226 | * Arguments: @base64_ctx *ctx@ = pointer to context block to initialize |
227 | * |
228 | * Returns: --- |
229 | * |
230 | * Use: Initializes a base64 context properly. |
231 | */ |
232 | |
233 | void base64_init(base64_ctx *ctx) |
234 | { |
235 | ctx->acc = 0; |
236 | ctx->qsz = 0; |
237 | ctx->lnlen = 0; |
238 | ctx->indent = "\n"; |
239 | ctx->maxline = 72; |
240 | } |
241 | |
242 | /*----- Test driver code --------------------------------------------------*/ |
243 | |
244 | #ifdef TEST_RIG |
245 | |
246 | int main(int argc, char *argv[]) |
247 | { |
248 | unsigned char buf[BUFSIZ]; |
249 | dstr d; |
250 | base64_ctx ctx; |
251 | void (*proc)(base64_ctx *, const unsigned char *, size_t, dstr *); |
252 | size_t sz; |
253 | |
254 | dstr_create(&d); |
255 | base64_init(&ctx); |
256 | |
257 | if (argc > 1 && strcmp(argv[1], "-d") == 0) |
258 | proc = base64_decode; |
259 | else { |
260 | proc = base64_encode; |
261 | putchar('\t'); |
262 | ctx.indent = "\n\t"; |
263 | ctx.maxline = 64; |
264 | } |
265 | |
266 | do { |
267 | sz = fread(buf, 1, sizeof(buf), stdin); |
268 | if (sz) { |
269 | proc(&ctx, buf, sz, &d); |
270 | dstr_write(&d, stdout); |
271 | dstr_destroy(&d); |
272 | } |
273 | } while (sz == sizeof(buf)); |
274 | |
275 | proc(&ctx, 0, 0, &d); |
276 | dstr_write(&d, stdout); |
277 | |
278 | if (proc == base64_encode) |
279 | putchar('\n'); |
280 | |
281 | return (0); |
282 | } |
283 | |
284 | #endif |
285 | |
286 | /*----- That's all, folks -------------------------------------------------*/ |