1 /* $NetBSD: base64.c,v 1.8 2023/08/23 19:16:14 rillig 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 1.8 2023/08/23 19:16:14 rillig 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 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 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 if (fputc(B64[out[i]], fout) == EOF) 71 return errno; 72 if (++(*pos) == wrap) { 73 if (fputc('\n', fout) == EOF) 74 return errno; 75 *pos = 0; 76 } 77 } 78 for (; i < 4; i++) { 79 if (fputc('=', fout) == EOF) 80 return errno; 81 if (++(*pos) == wrap) { 82 if (fputc('\n', fout) == EOF) 83 return errno; 84 *pos = 0; 85 } 86 } 87 88 return 0; 89 } 90 91 static void 92 encode(uint8_t out[4], uint8_t in[3]) 93 { 94 out[0] = in[0] >> 2; 95 out[1] = (uint8_t)(((in[0] & 0x03) << 4) | (in[1] >> 4)); 96 out[2] = (uint8_t)(((in[1] & 0x0f) << 2) | (in[2] >> 6)); 97 out[3] = in[2] & 0x3f; 98 } 99 100 static int 101 b64_encode(FILE *fout, FILE *fin, size_t wrap) 102 { 103 uint8_t in[3]; 104 uint8_t out[4]; 105 size_t ilen; 106 size_t pos = 0; 107 int e; 108 109 while ((ilen = getinput(fin, in)) > 2) { 110 encode(out, in); 111 if ((e = putoutput(fout, out, ilen, wrap, &pos)) != 0) 112 return e; 113 } 114 115 if (ilen != 0) { 116 encode(out, in); 117 if ((e = putoutput(fout, out, ilen, wrap, &pos)) != 0) 118 return e; 119 } 120 121 if (pos != 0 && wrap != 0) { 122 if (fputc('\n', fout) == EOF) 123 return errno; 124 } 125 return 0; 126 } 127 128 static int 129 b64_decode(FILE *fout, FILE *fin, bool ignore) 130 { 131 int state, c; 132 uint8_t b, out; 133 const char *pos; 134 135 state = 0; 136 out = 0; 137 138 while ((c = getc(fin)) != EOF) { 139 if (ignore && isspace(c)) 140 continue; 141 142 if (c == '=') 143 break; 144 145 pos = strchr(B64, c); 146 if (pos == NULL) 147 return EFTYPE; 148 149 b = (uint8_t)(pos - B64); 150 151 switch (state) { 152 case 0: 153 out = (uint8_t)(b << 2); 154 break; 155 case 1: 156 out |= b >> 4; 157 if (fputc(out, fout) == EOF) 158 return errno; 159 out = (uint8_t)((b & 0xf) << 4); 160 break; 161 case 2: 162 out |= b >> 2; 163 if (fputc(out, fout) == EOF) 164 return errno; 165 out = (uint8_t)((b & 0x3) << 6); 166 break; 167 case 3: 168 out |= b; 169 if (fputc(out, fout) == EOF) 170 return errno; 171 out = 0; 172 break; 173 default: 174 abort(); 175 } 176 state = (state + 1) & 3; 177 } 178 179 if (c == '=') { 180 switch (state) { 181 case 0: 182 case 1: 183 return EFTYPE; 184 case 2: 185 while ((c = getc(fin)) != EOF) { 186 if (ignore && isspace(c)) 187 continue; 188 break; 189 } 190 if (c != '=') 191 return EFTYPE; 192 /*FALLTHROUGH*/ 193 case 3: 194 while ((c = getc(fin)) != EOF) { 195 if (ignore && isspace(c)) 196 continue; 197 break; 198 } 199 if (c != EOF) 200 return EFTYPE; 201 return 0; 202 default: 203 abort(); 204 } 205 } 206 207 if (c != EOF || state != 0) 208 return EFTYPE; 209 210 return 0; 211 } 212 213 static __dead void 214 usage(void) 215 { 216 fprintf(stderr, "Usage: %s [-di] [-w <wrap>] [<file>]...\n", 217 getprogname()); 218 exit(EXIT_FAILURE); 219 } 220 221 static void 222 doit(FILE *fout, FILE *fin, bool decode, bool ignore, size_t wrap) 223 { 224 int e; 225 226 if (decode) 227 e = b64_decode(fout, fin, ignore); 228 else 229 e = b64_encode(fout, fin, wrap); 230 231 if (e == 0) 232 return; 233 errc(EXIT_FAILURE, e, "%scoding failed", decode ? "De": "En"); 234 } 235 236 int 237 main(int argc, char *argv[]) 238 { 239 bool decode = false; 240 size_t wrap = 76; 241 bool ignore = true; 242 int c; 243 244 while ((c = getopt(argc, argv, "b:Ddiw:")) != -1) { 245 switch (c) { 246 case 'D': 247 decode = ignore = true; 248 break; 249 case 'd': 250 decode = true; 251 break; 252 case 'i': 253 ignore = true; 254 break; 255 case 'b': 256 case 'w': 257 wrap = (size_t)atoi(optarg); 258 break; 259 default: 260 usage(); 261 } 262 } 263 264 if (optind == argc) { 265 doit(stdout, stdin, decode, ignore, wrap); 266 return EXIT_SUCCESS; 267 } 268 269 for (c = optind; c < argc; c++) { 270 FILE *fp = strcmp(argv[c], "-") == 0 ? 271 stdin : fopen(argv[c], "r"); 272 if (fp == NULL) 273 err(EXIT_FAILURE, "Can't open `%s'", argv[c]); 274 doit(stdout, fp, decode, ignore, wrap); 275 if (fp != stdin) 276 fclose(fp); 277 } 278 279 return EXIT_SUCCESS; 280 } 281