1 /* $NetBSD: base64.c,v 1.5 2021/08/27 17:53:13 christos Exp $ */
2
3 /*-
4 * Copyright (c) 2018 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Christos Zoulas.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32 #include <sys/cdefs.h>
33 __RCSID("$NetBSD: base64.c,v 1.5 2021/08/27 17:53:13 christos Exp $");
34
35 #include <ctype.h>
36 #include <errno.h>
37 #include <err.h>
38 #include <stdbool.h>
39 #include <stdio.h>
40 #include <stdint.h>
41 #include <stdlib.h>
42 #include <string.h>
43 #include <unistd.h>
44
45 static const char B64[] =
46 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
47
48 static size_t
getinput(FILE * fin,uint8_t in[3])49 getinput(FILE *fin, uint8_t in[3])
50 {
51 size_t res;
52 int c;
53
54 for (res = 0; res < 3 && (c = getc(fin)) != EOF; res++)
55 in[res] = (uint8_t)c;
56 for (size_t i = res; i < 3; i++)
57 in[i] = 0;
58
59 return res;
60 }
61
62 static int
putoutput(FILE * fout,uint8_t out[4],size_t len,size_t wrap,size_t * pos)63 putoutput(FILE *fout, uint8_t out[4], size_t len, size_t wrap, size_t *pos)
64 {
65 size_t i;
66
67 for (i = 0; i < len + 1; i++) {
68 if (out[i] >= 64) {
69 return EINVAL;
70 }
71 if (fputc(B64[out[i]], fout) == -1)
72 return errno;
73 if (++(*pos) == wrap) {
74 if (fputc('\n', fout) == -1)
75 return errno;
76 *pos = 0;
77 }
78 }
79 for (; i < 4; i++) {
80 if (fputc('=', fout) == -1)
81 return errno;
82 if (++(*pos) == wrap) {
83 if (fputc('\n', fout) == -1)
84 return errno;
85 *pos = 0;
86 }
87 }
88
89 return 0;
90 }
91
92 static void
encode(uint8_t out[4],uint8_t in[3])93 encode(uint8_t out[4], uint8_t in[3])
94 {
95 out[0] = in[0] >> 2;
96 out[1] = (uint8_t)(((in[0] & 0x03) << 4) | (in[1] >> 4));
97 out[2] = (uint8_t)(((in[1] & 0x0f) << 2) | (in[2] >> 6));
98 out[3] = in[2] & 0x3f;
99 }
100
101 static int
b64_encode(FILE * fout,FILE * fin,size_t wrap)102 b64_encode(FILE *fout, FILE *fin, size_t wrap)
103 {
104 uint8_t in[3];
105 uint8_t out[4];
106 size_t ilen;
107 size_t pos = 0;
108 int e;
109
110 while ((ilen = getinput(fin, in)) > 2) {
111 encode(out, in);
112 if ((e = putoutput(fout, out, ilen, wrap, &pos)) != 0)
113 return e;
114 }
115
116 if (ilen != 0) {
117 encode(out, in);
118 if ((e = putoutput(fout, out, ilen, wrap, &pos)) != 0)
119 return e;
120 }
121
122 if (pos && wrap) {
123 if (fputc('\n', fout) == -1)
124 return errno;
125 }
126 return 0;
127 }
128
129
130 static int
b64_decode(FILE * fout,FILE * fin,bool ignore)131 b64_decode(FILE *fout, FILE *fin, bool ignore)
132 {
133 int state, c;
134 uint8_t b, out;
135 const char *pos;
136
137 state = 0;
138 out = 0;
139
140 while ((c = getc(fin)) != -1) {
141 if (ignore && isspace(c))
142 continue;
143
144 if (c == '=')
145 break;
146
147 pos = strchr(B64, c);
148 if (pos == NULL)
149 return EFTYPE;
150
151 b = (uint8_t)(pos - B64);
152
153 switch (state) {
154 case 0:
155 out = (uint8_t)(b << 2);
156 break;
157 case 1:
158 out |= b >> 4;
159 if (fputc(out, fout) == -1)
160 return errno;
161 out = (uint8_t)((b & 0xf) << 4);
162 break;
163 case 2:
164 out |= b >> 2;
165 if (fputc(out, fout) == -1)
166 return errno;
167 out = (uint8_t)((b & 0x3) << 6);
168 break;
169 case 3:
170 out |= b;
171 if (fputc(out, fout) == -1)
172 return errno;
173 out = 0;
174 break;
175 default:
176 abort();
177 }
178 state = (state + 1) & 3;
179 }
180
181 if (c == '=') {
182 switch (state) {
183 case 0:
184 case 1:
185 return EFTYPE;
186 case 2:
187 while ((c = getc(fin)) != -1) {
188 if (ignore && isspace(c))
189 continue;
190 break;
191 }
192 if (c != '=')
193 return EFTYPE;
194 /*FALLTHROUGH*/
195 case 3:
196 while ((c = getc(fin)) != -1) {
197 if (ignore && isspace(c))
198 continue;
199 break;
200 }
201 if (c != -1)
202 return EFTYPE;
203 return 0;
204 default:
205 abort();
206 }
207 }
208
209 if (c != -1 || state != 0)
210 return EFTYPE;
211
212 return 0;
213 }
214
215 static __dead void
usage(void)216 usage(void)
217 {
218 fprintf(stderr, "Usage: %s [-di] [-w <wrap>] [<file>]...\n",
219 getprogname());
220 exit(EXIT_FAILURE);
221 }
222
223 static void
doit(FILE * fout,FILE * fin,bool decode,bool ignore,size_t wrap)224 doit(FILE *fout, FILE *fin, bool decode, bool ignore, size_t wrap)
225 {
226 int e;
227
228 if (decode)
229 e = b64_decode(fout, fin, ignore);
230 else
231 e = b64_encode(fout, fin, wrap);
232
233 if (e == 0)
234 return;
235 errc(EXIT_FAILURE, e, "%scoding failed", decode ? "De": "En");
236 }
237
238 int
main(int argc,char * argv[])239 main(int argc, char *argv[])
240 {
241 bool decode = false;
242 size_t wrap = 76;
243 bool ignore = true;
244 int c;
245
246 while ((c = getopt(argc, argv, "b:Ddiw:")) != -1) {
247 switch (c) {
248 case 'D':
249 decode = ignore = true;
250 break;
251 case 'd':
252 decode = true;
253 break;
254 case 'i':
255 ignore = true;
256 break;
257 case 'b':
258 case 'w':
259 wrap = (size_t)atoi(optarg);
260 break;
261 default:
262 usage();
263 }
264 }
265
266 if (optind == argc) {
267 doit(stdout, stdin, decode, ignore, wrap);
268 return EXIT_SUCCESS;
269 }
270
271 for (c = optind; c < argc; c++) {
272 FILE *fp = strcmp(argv[c], "-") == 0 ?
273 stdin : fopen(argv[c], "r");
274 if (fp == NULL)
275 err(EXIT_FAILURE, "Can't open `%s'", argv[c]);
276 doit(stdout, fp, decode, ignore, wrap);
277 if (fp != stdin)
278 fclose(fp);
279 fclose(fp);
280 }
281
282 return EXIT_SUCCESS;
283 }
284