base64.c revision 1.7.2.1
1 /* $NetBSD: base64.c,v 1.7.2.1 2002/11/11 22:22:22 nathanw 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 1.7.2.1 2002/11/11 22:22:22 nathanw 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 #include <resolv.h> 60 #include <stdio.h> 61 62 #if defined(BSD) && (BSD >= 199103) && defined(AF_INET6) 63 # include <stdlib.h> 64 # include <string.h> 65 #else 66 # include "../conf/portability.h" 67 #endif 68 69 #define Assert(Cond) if (!(Cond)) abort() 70 71 static const char Base64[] = 72 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; 73 static const char Pad64 = '='; 74 75 /* (From RFC1521 and draft-ietf-dnssec-secext-03.txt) 76 The following encoding technique is taken from RFC 1521 by Borenstein 77 and Freed. It is reproduced here in a slightly edited form for 78 convenience. 79 80 A 65-character subset of US-ASCII is used, enabling 6 bits to be 81 represented per printable character. (The extra 65th character, "=", 82 is used to signify a special processing function.) 83 84 The encoding process represents 24-bit groups of input bits as output 85 strings of 4 encoded characters. Proceeding from left to right, a 86 24-bit input group is formed by concatenating 3 8-bit input groups. 87 These 24 bits are then treated as 4 concatenated 6-bit groups, each 88 of which is translated into a single digit in the base64 alphabet. 89 90 Each 6-bit group is used as an index into an array of 64 printable 91 characters. The character referenced by the index is placed in the 92 output string. 93 94 Table 1: The Base64 Alphabet 95 96 Value Encoding Value Encoding Value Encoding Value Encoding 97 0 A 17 R 34 i 51 z 98 1 B 18 S 35 j 52 0 99 2 C 19 T 36 k 53 1 100 3 D 20 U 37 l 54 2 101 4 E 21 V 38 m 55 3 102 5 F 22 W 39 n 56 4 103 6 G 23 X 40 o 57 5 104 7 H 24 Y 41 p 58 6 105 8 I 25 Z 42 q 59 7 106 9 J 26 a 43 r 60 8 107 10 K 27 b 44 s 61 9 108 11 L 28 c 45 t 62 + 109 12 M 29 d 46 u 63 / 110 13 N 30 e 47 v 111 14 O 31 f 48 w (pad) = 112 15 P 32 g 49 x 113 16 Q 33 h 50 y 114 115 Special processing is performed if fewer than 24 bits are available 116 at the end of the data being encoded. A full encoding quantum is 117 always completed at the end of a quantity. When fewer than 24 input 118 bits are available in an input group, zero bits are added (on the 119 right) to form an integral number of 6-bit groups. Padding at the 120 end of the data is performed using the '=' character. 121 122 Since all base64 input is an integral number of octets, only the 123 ------------------------------------------------- 124 following cases can arise: 125 126 (1) the final quantum of encoding input is an integral 127 multiple of 24 bits; here, the final unit of encoded 128 output will be an integral multiple of 4 characters 129 with no "=" padding, 130 (2) the final quantum of encoding input is exactly 8 bits; 131 here, the final unit of encoded output will be two 132 characters followed by two "=" padding characters, or 133 (3) the final quantum of encoding input is exactly 16 bits; 134 here, the final unit of encoded output will be three 135 characters followed by one "=" padding character. 136 */ 137 138 int 139 b64_ntop(src, srclength, target, targsize) 140 u_char const *src; 141 size_t srclength; 142 char *target; 143 size_t targsize; 144 { 145 size_t datalength = 0; 146 u_char input[3]; 147 u_char output[4]; 148 size_t i; 149 150 _DIAGASSERT(src != NULL); 151 _DIAGASSERT(target != NULL); 152 153 while (2 < srclength) { 154 input[0] = *src++; 155 input[1] = *src++; 156 input[2] = *src++; 157 srclength -= 3; 158 159 output[0] = (u_int32_t)input[0] >> 2; 160 output[1] = ((u_int32_t)(input[0] & 0x03) << 4) + 161 ((u_int32_t)input[1] >> 4); 162 output[2] = ((u_int32_t)(input[1] & 0x0f) << 2) + 163 ((u_int32_t)input[2] >> 6); 164 output[3] = input[2] & 0x3f; 165 Assert(output[0] < 64); 166 Assert(output[1] < 64); 167 Assert(output[2] < 64); 168 Assert(output[3] < 64); 169 170 if (datalength + 4 > targsize) 171 return (-1); 172 target[datalength++] = Base64[output[0]]; 173 target[datalength++] = Base64[output[1]]; 174 target[datalength++] = Base64[output[2]]; 175 target[datalength++] = Base64[output[3]]; 176 } 177 178 /* Now we worry about padding. */ 179 if (0 != srclength) { 180 /* Get what's left. */ 181 input[0] = input[1] = input[2] = '\0'; 182 for (i = 0; i < srclength; i++) 183 input[i] = *src++; 184 185 output[0] = (u_int32_t)input[0] >> 2; 186 output[1] = ((u_int32_t)(input[0] & 0x03) << 4) + 187 ((u_int32_t)input[1] >> 4); 188 output[2] = ((u_int32_t)(input[1] & 0x0f) << 2) + 189 ((u_int32_t)input[2] >> 6); 190 Assert(output[0] < 64); 191 Assert(output[1] < 64); 192 Assert(output[2] < 64); 193 194 if (datalength + 4 > targsize) 195 return (-1); 196 target[datalength++] = Base64[output[0]]; 197 target[datalength++] = Base64[output[1]]; 198 if (srclength == 1) 199 target[datalength++] = Pad64; 200 else 201 target[datalength++] = Base64[output[2]]; 202 target[datalength++] = Pad64; 203 } 204 if (datalength >= targsize) 205 return (-1); 206 target[datalength] = '\0'; /* Returned value doesn't count \0. */ 207 return (datalength); 208 } 209 210 /* skips all whitespace anywhere. 211 converts characters, four at a time, starting at (or after) 212 src from base - 64 numbers into three 8 bit bytes in the target area. 213 it returns the number of data bytes stored at the target, or -1 on error. 214 */ 215 216 int 217 b64_pton(src, target, targsize) 218 char const *src; 219 u_char *target; 220 size_t targsize; 221 { 222 size_t tarindex; 223 int state, ch; 224 char *pos; 225 226 _DIAGASSERT(src != NULL); 227 _DIAGASSERT(target != NULL); 228 229 state = 0; 230 tarindex = 0; 231 232 while ((ch = (u_char) *src++) != '\0') { 233 if (isspace(ch)) /* Skip whitespace anywhere. */ 234 continue; 235 236 if (ch == Pad64) 237 break; 238 239 pos = strchr(Base64, ch); 240 if (pos == 0) /* A non-base64 character. */ 241 return (-1); 242 243 switch (state) { 244 case 0: 245 if (target) { 246 if (tarindex >= targsize) 247 return (-1); 248 target[tarindex] = (pos - Base64) << 2; 249 } 250 state = 1; 251 break; 252 case 1: 253 if (target) { 254 if (tarindex + 1 >= targsize) 255 return (-1); 256 target[tarindex] |= 257 (u_int32_t)(pos - Base64) >> 4; 258 target[tarindex+1] = ((pos - Base64) & 0x0f) 259 << 4 ; 260 } 261 tarindex++; 262 state = 2; 263 break; 264 case 2: 265 if (target) { 266 if (tarindex + 1 >= targsize) 267 return (-1); 268 target[tarindex] |= 269 (u_int32_t)(pos - Base64) >> 2; 270 target[tarindex+1] = ((pos - Base64) & 0x03) 271 << 6; 272 } 273 tarindex++; 274 state = 3; 275 break; 276 case 3: 277 if (target) { 278 if (tarindex >= targsize) 279 return (-1); 280 target[tarindex] |= (pos - Base64); 281 } 282 tarindex++; 283 state = 0; 284 break; 285 default: 286 abort(); 287 } 288 } 289 290 /* 291 * We are done decoding Base-64 chars. Let's see if we ended 292 * on a byte boundary, and/or with erroneous trailing characters. 293 */ 294 295 if (ch == Pad64) { /* We got a pad char. */ 296 ch = *src++; /* Skip it, get next. */ 297 switch (state) { 298 case 0: /* Invalid = in first position */ 299 case 1: /* Invalid = in second position */ 300 return (-1); 301 302 case 2: /* Valid, means one byte of info */ 303 /* Skip any number of spaces. */ 304 for (; ch != '\0'; ch = (u_char) *src++) 305 if (!isspace(ch)) 306 break; 307 /* Make sure there is another trailing = sign. */ 308 if (ch != Pad64) 309 return (-1); 310 ch = *src++; /* Skip the = */ 311 /* Fall through to "single trailing =" case. */ 312 /* FALLTHROUGH */ 313 314 case 3: /* Valid, means two bytes of info */ 315 /* 316 * We know this char is an =. Is there anything but 317 * whitespace after it? 318 */ 319 for (; ch != '\0'; ch = (u_char) *src++) 320 if (!isspace(ch)) 321 return (-1); 322 323 /* 324 * Now make sure for cases 2 and 3 that the "extra" 325 * bits that slopped past the last full byte were 326 * zeros. If we don't check them, they become a 327 * subliminal channel. 328 */ 329 if (target && target[tarindex] != 0) 330 return (-1); 331 } 332 } else { 333 /* 334 * We ended by seeing the end of the string. Make sure we 335 * have no partial bytes lying around. 336 */ 337 if (state != 0) 338 return (-1); 339 } 340 341 return (tarindex); 342 } 343
Indexes created Fri Sep 26 20:09:58 GMT 2025