1 /* 2 * base64 - libubox base64 functions 3 * 4 * Copyright (C) 2015 Felix Fietkau <nbd@openwrt.org> 5 * 6 * Permission to use, copy, modify, and/or distribute this software for any 7 * purpose with or without fee is hereby granted, provided that the above 8 * copyright notice and this permission notice appear in all copies. 9 * 10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 17 */ 18 19 /* $OpenBSD: base64.c,v 1.7 2013/12/31 02:32:56 tedu Exp $ */ 20 21 /* 22 * Copyright (c) 1996 by Internet Software Consortium. 23 * 24 * Permission to use, copy, modify, and distribute this software for any 25 * purpose with or without fee is hereby granted, provided that the above 26 * copyright notice and this permission notice appear in all copies. 27 * 28 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS 29 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES 30 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE 31 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL 32 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR 33 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS 34 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS 35 * SOFTWARE. 36 */ 37 38 /* 39 * Portions Copyright (c) 1995 by International Business Machines, Inc. 40 * 41 * International Business Machines, Inc. (hereinafter called IBM) grants 42 * permission under its copyrights to use, copy, modify, and distribute this 43 * Software with or without fee, provided that the above copyright notice and 44 * all paragraphs of this notice appear in all copies, and that the name of IBM 45 * not be used in connection with the marketing of any product incorporating 46 * the Software or modifications thereof, without specific, written prior 47 * permission. 48 * 49 * To the extent it has a right to do so, IBM grants an immunity from suit 50 * under its patents, if any, for the use, sale or manufacture of products to 51 * the extent that such products are used for performing Domain Name System 52 * dynamic updates in TCP/IP networks by means of the Software. No immunity is 53 * granted for any product per se or for any other function of any product. 54 * 55 * THE SOFTWARE IS PROVIDED "AS IS", AND IBM DISCLAIMS ALL WARRANTIES, 56 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A 57 * PARTICULAR PURPOSE. IN NO EVENT SHALL IBM BE LIABLE FOR ANY SPECIAL, 58 * DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER ARISING 59 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE, EVEN 60 * IF IBM IS APPRISED OF THE POSSIBILITY OF SUCH DAMAGES. 61 */ 62 63 #include <sys/types.h> 64 #include <ctype.h> 65 #include <stdio.h> 66 #include <stdlib.h> 67 #include <string.h> 68 69 #include "assert.h" 70 #include "utils.h" 71 72 static const char Base64[] = 73 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; 74 static const char Pad64 = '='; 75 76 /* (From RFC1521 and draft-ietf-dnssec-secext-03.txt) 77 The following encoding technique is taken from RFC 1521 by Borenstein 78 and Freed. It is reproduced here in a slightly edited form for 79 convenience. 80 81 A 65-character subset of US-ASCII is used, enabling 6 bits to be 82 represented per printable character. (The extra 65th character, "=", 83 is used to signify a special processing function.) 84 85 The encoding process represents 24-bit groups of input bits as output 86 strings of 4 encoded characters. Proceeding from left to right, a 87 24-bit input group is formed by concatenating 3 8-bit input groups. 88 These 24 bits are then treated as 4 concatenated 6-bit groups, each 89 of which is translated into a single digit in the base64 alphabet. 90 91 Each 6-bit group is used as an index into an array of 64 printable 92 characters. The character referenced by the index is placed in the 93 output string. 94 95 Table 1: The Base64 Alphabet 96 97 Value Encoding Value Encoding Value Encoding Value Encoding 98 0 A 17 R 34 i 51 z 99 1 B 18 S 35 j 52 0 100 2 C 19 T 36 k 53 1 101 3 D 20 U 37 l 54 2 102 4 E 21 V 38 m 55 3 103 5 F 22 W 39 n 56 4 104 6 G 23 X 40 o 57 5 105 7 H 24 Y 41 p 58 6 106 8 I 25 Z 42 q 59 7 107 9 J 26 a 43 r 60 8 108 10 K 27 b 44 s 61 9 109 11 L 28 c 45 t 62 + 110 12 M 29 d 46 u 63 / 111 13 N 30 e 47 v 112 14 O 31 f 48 w (pad) = 113 15 P 32 g 49 x 114 16 Q 33 h 50 y 115 116 Special processing is performed if fewer than 24 bits are available 117 at the end of the data being encoded. A full encoding quantum is 118 always completed at the end of a quantity. When fewer than 24 input 119 bits are available in an input group, zero bits are added (on the 120 right) to form an integral number of 6-bit groups. Padding at the 121 end of the data is performed using the '=' character. 122 123 Since all base64 input is an integral number of octets, only the 124 ------------------------------------------------- 125 following cases can arise: 126 127 (1) the final quantum of encoding input is an integral 128 multiple of 24 bits; here, the final unit of encoded 129 output will be an integral multiple of 4 characters 130 with no "=" padding, 131 (2) the final quantum of encoding input is exactly 8 bits; 132 here, the final unit of encoded output will be two 133 characters followed by two "=" padding characters, or 134 (3) the final quantum of encoding input is exactly 16 bits; 135 here, the final unit of encoded output will be three 136 characters followed by one "=" padding character. 137 */ 138 139 int b64_encode(const void *_src, size_t srclength, 140 void *dest, size_t targsize) 141 { 142 const unsigned char *src = _src; 143 char *target = dest; 144 size_t datalength = 0; 145 u_char input[3] = {0}; 146 u_char output[4]; 147 size_t i; 148 149 assert(dest && targsize > 0); 150 151 while (2 < srclength) { 152 input[0] = *src++; 153 input[1] = *src++; 154 input[2] = *src++; 155 srclength -= 3; 156 157 output[0] = input[0] >> 2; 158 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4); 159 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6); 160 output[3] = input[2] & 0x3f; 161 162 if (datalength + 4 > targsize) 163 return (-1); 164 target[datalength++] = Base64[output[0]]; 165 target[datalength++] = Base64[output[1]]; 166 target[datalength++] = Base64[output[2]]; 167 target[datalength++] = Base64[output[3]]; 168 } 169 170 /* Now we worry about padding. */ 171 if (0 != srclength) { 172 /* Get what's left. */ 173 input[0] = input[1] = input[2] = '\0'; 174 for (i = 0; i < srclength; i++) 175 input[i] = *src++; 176 177 output[0] = input[0] >> 2; 178 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4); 179 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6); 180 181 if (datalength + 4 > targsize) 182 return (-1); 183 target[datalength++] = Base64[output[0]]; 184 target[datalength++] = Base64[output[1]]; 185 if (srclength == 1) 186 target[datalength++] = Pad64; 187 else 188 target[datalength++] = Base64[output[2]]; 189 target[datalength++] = Pad64; 190 } 191 if (datalength >= targsize) 192 return (-1); 193 target[datalength] = '\0'; /* Returned value doesn't count \0. */ 194 return (datalength); 195 } 196 197 /* skips all whitespace anywhere. 198 converts characters, four at a time, starting at (or after) 199 src from base - 64 numbers into three 8 bit bytes in the target area. 200 it returns the number of data bytes stored at the target, or -1 on error. 201 */ 202 203 int b64_decode(const void *_src, void *dest, size_t targsize) 204 { 205 const char *src = _src; 206 unsigned char *target = dest; 207 int state, ch; 208 size_t tarindex; 209 u_char nextbyte; 210 char *pos; 211 212 state = 0; 213 tarindex = 0; 214 215 assert(dest && targsize > 0); 216 217 while ((ch = (unsigned char)*src++) != '\0') { 218 if (isspace(ch)) /* Skip whitespace anywhere. */ 219 continue; 220 221 if (ch == Pad64) 222 break; 223 224 pos = strchr(Base64, ch); 225 if (pos == 0) /* A non-base64 character. */ 226 return (-1); 227 228 switch (state) { 229 case 0: 230 if (target) { 231 if (tarindex >= targsize) 232 return (-1); 233 target[tarindex] = (pos - Base64) << 2; 234 } 235 state = 1; 236 break; 237 case 1: 238 if (target) { 239 if (tarindex >= targsize) 240 return (-1); 241 target[tarindex] |= (pos - Base64) >> 4; 242 nextbyte = ((pos - Base64) & 0x0f) << 4; 243 if (tarindex + 1 < targsize) 244 target[tarindex+1] = nextbyte; 245 else if (nextbyte) 246 return (-1); 247 } 248 tarindex++; 249 state = 2; 250 break; 251 case 2: 252 if (target) { 253 if (tarindex >= targsize) 254 return (-1); 255 target[tarindex] |= (pos - Base64) >> 2; 256 nextbyte = ((pos - Base64) & 0x03) << 6; 257 if (tarindex + 1 < targsize) 258 target[tarindex+1] = nextbyte; 259 else if (nextbyte) 260 return (-1); 261 } 262 tarindex++; 263 state = 3; 264 break; 265 case 3: 266 if (target) { 267 if (tarindex >= targsize) 268 return (-1); 269 target[tarindex] |= (pos - Base64); 270 } 271 tarindex++; 272 state = 0; 273 break; 274 } 275 } 276 277 /* 278 * We are done decoding Base-64 chars. Let's see if we ended 279 * on a byte boundary, and/or with erroneous trailing characters. 280 */ 281 282 if (ch == Pad64) { /* We got a pad char. */ 283 ch = (unsigned char)*src++; /* Skip it, get next. */ 284 switch (state) { 285 case 0: /* Invalid = in first position */ 286 case 1: /* Invalid = in second position */ 287 return (-1); 288 289 case 2: /* Valid, means one byte of info */ 290 /* Skip any number of spaces. */ 291 for (; ch != '\0'; ch = (unsigned char)*src++) 292 if (!isspace(ch)) 293 break; 294 /* Make sure there is another trailing = sign. */ 295 if (ch != Pad64) 296 return (-1); 297 ch = (unsigned char)*src++; /* Skip the = */ 298 /* Fall through to "single trailing =" case. */ 299 /* FALLTHROUGH */ 300 301 case 3: /* Valid, means two bytes of info */ 302 /* 303 * We know this char is an =. Is there anything but 304 * whitespace after it? 305 */ 306 for (; ch != '\0'; ch = (unsigned char)*src++) 307 if (!isspace(ch)) 308 return (-1); 309 310 /* 311 * Now make sure for cases 2 and 3 that the "extra" 312 * bits that slopped past the last full byte were 313 * zeros. If we don't check them, they become a 314 * subliminal channel. 315 */ 316 if (target && tarindex < targsize && 317 target[tarindex] != 0) 318 return (-1); 319 } 320 } else { 321 /* 322 * We ended by seeing the end of the string. Make sure we 323 * have no partial bytes lying around. 324 */ 325 if (state != 0) 326 return (-1); 327 } 328 329 /* Null-terminate if we have room left */ 330 if (tarindex < targsize) 331 target[tarindex] = 0; 332 333 return (tarindex); 334 } 335
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