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 #include "base64.h" 69 70 static const char Base64[] = 71 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; 72 static const char Pad64 = '='; 73 74 /* (From RFC1521 and draft-ietf-dnssec-secext-03.txt) 75 The following encoding technique is taken from RFC 1521 by Borenstein 76 and Freed. It is reproduced here in a slightly edited form for 77 convenience. 78 79 A 65-character subset of US-ASCII is used, enabling 6 bits to be 80 represented per printable character. (The extra 65th character, "=", 81 is used to signify a special processing function.) 82 83 The encoding process represents 24-bit groups of input bits as output 84 strings of 4 encoded characters. Proceeding from left to right, a 85 24-bit input group is formed by concatenating 3 8-bit input groups. 86 These 24 bits are then treated as 4 concatenated 6-bit groups, each 87 of which is translated into a single digit in the base64 alphabet. 88 89 Each 6-bit group is used as an index into an array of 64 printable 90 characters. The character referenced by the index is placed in the 91 output string. 92 93 Table 1: The Base64 Alphabet 94 95 Value Encoding Value Encoding Value Encoding Value Encoding 96 0 A 17 R 34 i 51 z 97 1 B 18 S 35 j 52 0 98 2 C 19 T 36 k 53 1 99 3 D 20 U 37 l 54 2 100 4 E 21 V 38 m 55 3 101 5 F 22 W 39 n 56 4 102 6 G 23 X 40 o 57 5 103 7 H 24 Y 41 p 58 6 104 8 I 25 Z 42 q 59 7 105 9 J 26 a 43 r 60 8 106 10 K 27 b 44 s 61 9 107 11 L 28 c 45 t 62 + 108 12 M 29 d 46 u 63 / 109 13 N 30 e 47 v 110 14 O 31 f 48 w (pad) = 111 15 P 32 g 49 x 112 16 Q 33 h 50 y 113 114 Special processing is performed if fewer than 24 bits are available 115 at the end of the data being encoded. A full encoding quantum is 116 always completed at the end of a quantity. When fewer than 24 input 117 bits are available in an input group, zero bits are added (on the 118 right) to form an integral number of 6-bit groups. Padding at the 119 end of the data is performed using the '=' character. 120 121 Since all base64 input is an integral number of octets, only the 122 ------------------------------------------------- 123 following cases can arise: 124 125 (1) the final quantum of encoding input is an integral 126 multiple of 24 bits; here, the final unit of encoded 127 output will be an integral multiple of 4 characters 128 with no "=" padding, 129 (2) the final quantum of encoding input is exactly 8 bits; 130 here, the final unit of encoded output will be two 131 characters followed by two "=" padding characters, or 132 (3) the final quantum of encoding input is exactly 16 bits; 133 here, the final unit of encoded output will be three 134 characters followed by one "=" padding character. 135 */ 136 137 int b64_encode(const void *_src, size_t srclength, 138 void *dest, size_t targsize) 139 { 140 const unsigned char *src = _src; 141 char *target = dest; 142 size_t datalength = 0; 143 u_char input[3]; 144 u_char output[4]; 145 int i; 146 147 while (2 < srclength) { 148 input[0] = *src++; 149 input[1] = *src++; 150 input[2] = *src++; 151 srclength -= 3; 152 153 output[0] = input[0] >> 2; 154 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4); 155 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6); 156 output[3] = input[2] & 0x3f; 157 158 if (datalength + 4 > targsize) 159 return (-1); 160 target[datalength++] = Base64[output[0]]; 161 target[datalength++] = Base64[output[1]]; 162 target[datalength++] = Base64[output[2]]; 163 target[datalength++] = Base64[output[3]]; 164 } 165 166 /* Now we worry about padding. */ 167 if (0 != srclength) { 168 /* Get what's left. */ 169 input[0] = input[1] = input[2] = '\0'; 170 for (i = 0; i < srclength; i++) 171 input[i] = *src++; 172 173 output[0] = input[0] >> 2; 174 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4); 175 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6); 176 177 if (datalength + 4 > targsize) 178 return (-1); 179 target[datalength++] = Base64[output[0]]; 180 target[datalength++] = Base64[output[1]]; 181 if (srclength == 1) 182 target[datalength++] = Pad64; 183 else 184 target[datalength++] = Base64[output[2]]; 185 target[datalength++] = Pad64; 186 } 187 if (datalength >= targsize) 188 return (-1); 189 target[datalength] = '\0'; /* Returned value doesn't count \0. */ 190 return (datalength); 191 } 192 193 /* skips all whitespace anywhere. 194 converts characters, four at a time, starting at (or after) 195 src from base - 64 numbers into three 8 bit bytes in the target area. 196 it returns the number of data bytes stored at the target, or -1 on error. 197 */ 198 199 int b64_decode(const void *_src, void *dest, size_t targsize) 200 { 201 const char *src = _src; 202 unsigned char *target = dest; 203 int tarindex, state, ch; 204 u_char nextbyte; 205 char *pos; 206 207 state = 0; 208 tarindex = 0; 209 210 while ((ch = (unsigned char)*src++) != '\0') { 211 if (isspace(ch)) /* Skip whitespace anywhere. */ 212 continue; 213 214 if (ch == Pad64) 215 break; 216 217 pos = strchr(Base64, ch); 218 if (pos == 0) /* A non-base64 character. */ 219 return (-1); 220 221 switch (state) { 222 case 0: 223 if (target) { 224 if (tarindex >= targsize) 225 return (-1); 226 target[tarindex] = (pos - Base64) << 2; 227 } 228 state = 1; 229 break; 230 case 1: 231 if (target) { 232 if (tarindex >= targsize) 233 return (-1); 234 target[tarindex] |= (pos - Base64) >> 4; 235 nextbyte = ((pos - Base64) & 0x0f) << 4; 236 if (tarindex + 1 < targsize) 237 target[tarindex+1] = nextbyte; 238 else if (nextbyte) 239 return (-1); 240 } 241 tarindex++; 242 state = 2; 243 break; 244 case 2: 245 if (target) { 246 if (tarindex >= targsize) 247 return (-1); 248 target[tarindex] |= (pos - Base64) >> 2; 249 nextbyte = ((pos - Base64) & 0x03) << 6; 250 if (tarindex + 1 < targsize) 251 target[tarindex+1] = nextbyte; 252 else if (nextbyte) 253 return (-1); 254 } 255 tarindex++; 256 state = 3; 257 break; 258 case 3: 259 if (target) { 260 if (tarindex >= targsize) 261 return (-1); 262 target[tarindex] |= (pos - Base64); 263 } 264 tarindex++; 265 state = 0; 266 break; 267 } 268 } 269 270 /* 271 * We are done decoding Base-64 chars. Let's see if we ended 272 * on a byte boundary, and/or with erroneous trailing characters. 273 */ 274 275 if (ch == Pad64) { /* We got a pad char. */ 276 ch = (unsigned char)*src++; /* Skip it, get next. */ 277 switch (state) { 278 case 0: /* Invalid = in first position */ 279 case 1: /* Invalid = in second position */ 280 return (-1); 281 282 case 2: /* Valid, means one byte of info */ 283 /* Skip any number of spaces. */ 284 for (; ch != '\0'; ch = (unsigned char)*src++) 285 if (!isspace(ch)) 286 break; 287 /* Make sure there is another trailing = sign. */ 288 if (ch != Pad64) 289 return (-1); 290 ch = (unsigned char)*src++; /* Skip the = */ 291 /* Fall through to "single trailing =" case. */ 292 /* FALLTHROUGH */ 293 294 case 3: /* Valid, means two bytes of info */ 295 /* 296 * We know this char is an =. Is there anything but 297 * whitespace after it? 298 */ 299 for (; ch != '\0'; ch = (unsigned char)*src++) 300 if (!isspace(ch)) 301 return (-1); 302 303 /* 304 * Now make sure for cases 2 and 3 that the "extra" 305 * bits that slopped past the last full byte were 306 * zeros. If we don't check them, they become a 307 * subliminal channel. 308 */ 309 if (target && tarindex < targsize && 310 target[tarindex] != 0) 311 return (-1); 312 } 313 } else { 314 /* 315 * We ended by seeing the end of the string. Make sure we 316 * have no partial bytes lying around. 317 */ 318 if (state != 0) 319 return (-1); 320 } 321 322 /* Null-terminate if we have room left */ 323 if (tarindex < targsize) 324 target[tarindex] = 0; 325 326 return (tarindex); 327 } 328
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