base64.c revision bd33537fde8e1c68fcadfd6adf77b295ada9b45f
1/* $NetBSD: base64.c,v 1.8 2002/11/11 01:15:17 thorpej Exp $ */ 2 3/* 4 * Copyright (c) 1996 by Internet Software Consortium. 5 * 6 * Permission to use, copy, modify, and 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 INTERNET SOFTWARE CONSORTIUM DISCLAIMS 11 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES 12 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE 13 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL 14 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR 15 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS 16 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS 17 * SOFTWARE. 18 */ 19 20/* 21 * Portions Copyright (c) 1995 by International Business Machines, Inc. 22 * 23 * International Business Machines, Inc. (hereinafter called IBM) grants 24 * permission under its copyrights to use, copy, modify, and distribute this 25 * Software with or without fee, provided that the above copyright notice and 26 * all paragraphs of this notice appear in all copies, and that the name of IBM 27 * not be used in connection with the marketing of any product incorporating 28 * the Software or modifications thereof, without specific, written prior 29 * permission. 30 * 31 * To the extent it has a right to do so, IBM grants an immunity from suit 32 * under its patents, if any, for the use, sale or manufacture of products to 33 * the extent that such products are used for performing Domain Name System 34 * dynamic updates in TCP/IP networks by means of the Software. No immunity is 35 * granted for any product per se or for any other function of any product. 36 * 37 * THE SOFTWARE IS PROVIDED "AS IS", AND IBM DISCLAIMS ALL WARRANTIES, 38 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A 39 * PARTICULAR PURPOSE. IN NO EVENT SHALL IBM BE LIABLE FOR ANY SPECIAL, 40 * DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER ARISING 41 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE, EVEN 42 * IF IBM IS APPRISED OF THE POSSIBILITY OF SUCH DAMAGES. 43 */ 44 45#include <sys/cdefs.h> 46#if defined(LIBC_SCCS) && !defined(lint) 47__RCSID("$NetBSD: base64.c,v 1.8 2002/11/11 01:15:17 thorpej Exp $"); 48#endif /* LIBC_SCCS and not lint */ 49 50#include <sys/types.h> 51#include <sys/param.h> 52#include <sys/socket.h> 53#include <netinet/in.h> 54#include <arpa/inet.h> 55#include "arpa_nameser.h" 56 57#include <assert.h> 58#include <ctype.h> 59#ifdef ANDROID_CHANGES 60#include "resolv_private.h" 61#else 62#include <resolv.h> 63#endif 64#include <stdio.h> 65 66#include <stdlib.h> 67#include <string.h> 68 69static const char Base64[] = 70 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; 71static const char Pad64 = '='; 72 73/* (From RFC1521 and draft-ietf-dnssec-secext-03.txt) 74 The following encoding technique is taken from RFC 1521 by Borenstein 75 and Freed. It is reproduced here in a slightly edited form for 76 convenience. 77 78 A 65-character subset of US-ASCII is used, enabling 6 bits to be 79 represented per printable character. (The extra 65th character, "=", 80 is used to signify a special processing function.) 81 82 The encoding process represents 24-bit groups of input bits as output 83 strings of 4 encoded characters. Proceeding from left to right, a 84 24-bit input group is formed by concatenating 3 8-bit input groups. 85 These 24 bits are then treated as 4 concatenated 6-bit groups, each 86 of which is translated into a single digit in the base64 alphabet. 87 88 Each 6-bit group is used as an index into an array of 64 printable 89 characters. The character referenced by the index is placed in the 90 output string. 91 92 Table 1: The Base64 Alphabet 93 94 Value Encoding Value Encoding Value Encoding Value Encoding 95 0 A 17 R 34 i 51 z 96 1 B 18 S 35 j 52 0 97 2 C 19 T 36 k 53 1 98 3 D 20 U 37 l 54 2 99 4 E 21 V 38 m 55 3 100 5 F 22 W 39 n 56 4 101 6 G 23 X 40 o 57 5 102 7 H 24 Y 41 p 58 6 103 8 I 25 Z 42 q 59 7 104 9 J 26 a 43 r 60 8 105 10 K 27 b 44 s 61 9 106 11 L 28 c 45 t 62 + 107 12 M 29 d 46 u 63 / 108 13 N 30 e 47 v 109 14 O 31 f 48 w (pad) = 110 15 P 32 g 49 x 111 16 Q 33 h 50 y 112 113 Special processing is performed if fewer than 24 bits are available 114 at the end of the data being encoded. A full encoding quantum is 115 always completed at the end of a quantity. When fewer than 24 input 116 bits are available in an input group, zero bits are added (on the 117 right) to form an integral number of 6-bit groups. Padding at the 118 end of the data is performed using the '=' character. 119 120 Since all base64 input is an integral number of octets, only the 121 ------------------------------------------------- 122 following cases can arise: 123 124 (1) the final quantum of encoding input is an integral 125 multiple of 24 bits; here, the final unit of encoded 126 output will be an integral multiple of 4 characters 127 with no "=" padding, 128 (2) the final quantum of encoding input is exactly 8 bits; 129 here, the final unit of encoded output will be two 130 characters followed by two "=" padding characters, or 131 (3) the final quantum of encoding input is exactly 16 bits; 132 here, the final unit of encoded output will be three 133 characters followed by one "=" padding character. 134 */ 135 136int 137b64_ntop(src, srclength, target, targsize) 138 u_char const *src; 139 size_t srclength; 140 char *target; 141 size_t targsize; 142{ 143 size_t datalength = 0; 144 u_char input[3] = { 0, 0, 0 }; /* make compiler happy */ 145 u_char output[4]; 146 size_t i; 147 148 assert(src != NULL); 149 assert(target != NULL); 150 151 while (2 < srclength) { 152 input[0] = *src++; 153 input[1] = *src++; 154 input[2] = *src++; 155 srclength -= 3; 156 157 output[0] = (u_int32_t)input[0] >> 2; 158 output[1] = ((u_int32_t)(input[0] & 0x03) << 4) + 159 ((u_int32_t)input[1] >> 4); 160 output[2] = ((u_int32_t)(input[1] & 0x0f) << 2) + 161 ((u_int32_t)input[2] >> 6); 162 output[3] = input[2] & 0x3f; 163 assert(output[0] < 64); 164 assert(output[1] < 64); 165 assert(output[2] < 64); 166 assert(output[3] < 64); 167 168 if (datalength + 4 > targsize) 169 return (-1); 170 target[datalength++] = Base64[output[0]]; 171 target[datalength++] = Base64[output[1]]; 172 target[datalength++] = Base64[output[2]]; 173 target[datalength++] = Base64[output[3]]; 174 } 175 176 /* Now we worry about padding. */ 177 if (0 != srclength) { 178 /* Get what's left. */ 179 input[0] = input[1] = input[2] = '\0'; 180 for (i = 0; i < srclength; i++) 181 input[i] = *src++; 182 183 output[0] = (u_int32_t)input[0] >> 2; 184 output[1] = ((u_int32_t)(input[0] & 0x03) << 4) + 185 ((u_int32_t)input[1] >> 4); 186 output[2] = ((u_int32_t)(input[1] & 0x0f) << 2) + 187 ((u_int32_t)input[2] >> 6); 188 assert(output[0] < 64); 189 assert(output[1] < 64); 190 assert(output[2] < 64); 191 192 if (datalength + 4 > targsize) 193 return (-1); 194 target[datalength++] = Base64[output[0]]; 195 target[datalength++] = Base64[output[1]]; 196 if (srclength == 1) 197 target[datalength++] = Pad64; 198 else 199 target[datalength++] = Base64[output[2]]; 200 target[datalength++] = Pad64; 201 } 202 if (datalength >= targsize) 203 return (-1); 204 target[datalength] = '\0'; /* Returned value doesn't count \0. */ 205 return (datalength); 206} 207 208/* skips all whitespace anywhere. 209 converts characters, four at a time, starting at (or after) 210 src from base - 64 numbers into three 8 bit bytes in the target area. 211 it returns the number of data bytes stored at the target, or -1 on error. 212 */ 213 214int 215b64_pton(src, target, targsize) 216 char const *src; 217 u_char *target; 218 size_t targsize; 219{ 220 size_t tarindex; 221 int state, ch; 222 char *pos; 223 224 assert(src != NULL); 225 assert(target != NULL); 226 227 state = 0; 228 tarindex = 0; 229 230 while ((ch = (u_char) *src++) != '\0') { 231 if (isspace(ch)) /* Skip whitespace anywhere. */ 232 continue; 233 234 if (ch == Pad64) 235 break; 236 237 pos = strchr(Base64, ch); 238 if (pos == 0) /* A non-base64 character. */ 239 return (-1); 240 241 switch (state) { 242 case 0: 243 if (target) { 244 if (tarindex >= targsize) 245 return (-1); 246 target[tarindex] = (pos - Base64) << 2; 247 } 248 state = 1; 249 break; 250 case 1: 251 if (target) { 252 if (tarindex + 1 >= targsize) 253 return (-1); 254 target[tarindex] |= 255 (u_int32_t)(pos - Base64) >> 4; 256 target[tarindex+1] = ((pos - Base64) & 0x0f) 257 << 4 ; 258 } 259 tarindex++; 260 state = 2; 261 break; 262 case 2: 263 if (target) { 264 if (tarindex + 1 >= targsize) 265 return (-1); 266 target[tarindex] |= 267 (u_int32_t)(pos - Base64) >> 2; 268 target[tarindex+1] = ((pos - Base64) & 0x03) 269 << 6; 270 } 271 tarindex++; 272 state = 3; 273 break; 274 case 3: 275 if (target) { 276 if (tarindex >= targsize) 277 return (-1); 278 target[tarindex] |= (pos - Base64); 279 } 280 tarindex++; 281 state = 0; 282 break; 283 default: 284 abort(); 285 } 286 } 287 288 /* 289 * We are done decoding Base-64 chars. Let's see if we ended 290 * on a byte boundary, and/or with erroneous trailing characters. 291 */ 292 293 if (ch == Pad64) { /* We got a pad char. */ 294 ch = *src++; /* Skip it, get next. */ 295 switch (state) { 296 case 0: /* Invalid = in first position */ 297 case 1: /* Invalid = in second position */ 298 return (-1); 299 300 case 2: /* Valid, means one byte of info */ 301 /* Skip any number of spaces. */ 302 for (; ch != '\0'; ch = (u_char) *src++) 303 if (!isspace(ch)) 304 break; 305 /* Make sure there is another trailing = sign. */ 306 if (ch != Pad64) 307 return (-1); 308 ch = *src++; /* Skip the = */ 309 /* Fall through to "single trailing =" case. */ 310 /* FALLTHROUGH */ 311 312 case 3: /* Valid, means two bytes of info */ 313 /* 314 * We know this char is an =. Is there anything but 315 * whitespace after it? 316 */ 317 for (; ch != '\0'; ch = (u_char) *src++) 318 if (!isspace(ch)) 319 return (-1); 320 321 /* 322 * Now make sure for cases 2 and 3 that the "extra" 323 * bits that slopped past the last full byte were 324 * zeros. If we don't check them, they become a 325 * subliminal channel. 326 */ 327 if (target && target[tarindex] != 0) 328 return (-1); 329 } 330 } else { 331 /* 332 * We ended by seeing the end of the string. Make sure we 333 * have no partial bytes lying around. 334 */ 335 if (state != 0) 336 return (-1); 337 } 338 339 return (tarindex); 340} 341