base64.c revision 1.5
1 /* $NetBSD: base64.c,v 1.5 1999/09/16 11:45:11 lukem 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 1.5 1999/09/16 11:45:11 lukem 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 int i; 149 150 _DIAGASSERT(src != NULL); 151 _DIAGASSERT(target != NULL); 152 #ifdef _DIAGNOSTIC 153 if (src == NULL || target == NULL) 154 return (-1); 155 #endif 156 157 while (2 < srclength) { 158 input[0] = *src++; 159 input[1] = *src++; 160 input[2] = *src++; 161 srclength -= 3; 162 163 output[0] = (u_int32_t)input[0] >> 2; 164 output[1] = ((u_int32_t)(input[0] & 0x03) << 4) + 165 ((u_int32_t)input[1] >> 4); 166 output[2] = ((u_int32_t)(input[1] & 0x0f) << 2) + 167 ((u_int32_t)input[2] >> 6); 168 output[3] = input[2] & 0x3f; 169 Assert(output[0] < 64); 170 Assert(output[1] < 64); 171 Assert(output[2] < 64); 172 Assert(output[3] < 64); 173 174 if (datalength + 4 > targsize) 175 return (-1); 176 target[datalength++] = Base64[output[0]]; 177 target[datalength++] = Base64[output[1]]; 178 target[datalength++] = Base64[output[2]]; 179 target[datalength++] = Base64[output[3]]; 180 } 181 182 /* Now we worry about padding. */ 183 if (0 != srclength) { 184 /* Get what's left. */ 185 input[0] = input[1] = input[2] = '\0'; 186 for (i = 0; i < srclength; i++) 187 input[i] = *src++; 188 189 output[0] = (u_int32_t)input[0] >> 2; 190 output[1] = ((u_int32_t)(input[0] & 0x03) << 4) + 191 ((u_int32_t)input[1] >> 4); 192 output[2] = ((u_int32_t)(input[1] & 0x0f) << 2) + 193 ((u_int32_t)input[2] >> 6); 194 Assert(output[0] < 64); 195 Assert(output[1] < 64); 196 Assert(output[2] < 64); 197 198 if (datalength + 4 > targsize) 199 return (-1); 200 target[datalength++] = Base64[output[0]]; 201 target[datalength++] = Base64[output[1]]; 202 if (srclength == 1) 203 target[datalength++] = Pad64; 204 else 205 target[datalength++] = Base64[output[2]]; 206 target[datalength++] = Pad64; 207 } 208 if (datalength >= targsize) 209 return (-1); 210 target[datalength] = '\0'; /* Returned value doesn't count \0. */ 211 return (datalength); 212 } 213 214 /* skips all whitespace anywhere. 215 converts characters, four at a time, starting at (or after) 216 src from base - 64 numbers into three 8 bit bytes in the target area. 217 it returns the number of data bytes stored at the target, or -1 on error. 218 */ 219 220 int 221 b64_pton(src, target, targsize) 222 char const *src; 223 u_char *target; 224 size_t targsize; 225 { 226 int tarindex, state, ch; 227 char *pos; 228 229 _DIAGASSERT(src != NULL); 230 _DIAGASSERT(target != NULL); 231 #ifdef _DIAGNOSTIC 232 if (src == NULL || target == NULL) 233 return (-1); 234 #endif 235 236 state = 0; 237 tarindex = 0; 238 239 while ((ch = *src++) != '\0') { 240 if (isspace(ch)) /* Skip whitespace anywhere. */ 241 continue; 242 243 if (ch == Pad64) 244 break; 245 246 pos = strchr(Base64, ch); 247 if (pos == 0) /* A non-base64 character. */ 248 return (-1); 249 250 switch (state) { 251 case 0: 252 if (target) { 253 if (tarindex >= targsize) 254 return (-1); 255 target[tarindex] = (pos - Base64) << 2; 256 } 257 state = 1; 258 break; 259 case 1: 260 if (target) { 261 if (tarindex + 1 >= targsize) 262 return (-1); 263 target[tarindex] |= 264 (u_int32_t)(pos - Base64) >> 4; 265 target[tarindex+1] = ((pos - Base64) & 0x0f) 266 << 4 ; 267 } 268 tarindex++; 269 state = 2; 270 break; 271 case 2: 272 if (target) { 273 if (tarindex + 1 >= targsize) 274 return (-1); 275 target[tarindex] |= 276 (u_int32_t)(pos - Base64) >> 2; 277 target[tarindex+1] = ((pos - Base64) & 0x03) 278 << 6; 279 } 280 tarindex++; 281 state = 3; 282 break; 283 case 3: 284 if (target) { 285 if (tarindex >= targsize) 286 return (-1); 287 target[tarindex] |= (pos - Base64); 288 } 289 tarindex++; 290 state = 0; 291 break; 292 default: 293 abort(); 294 } 295 } 296 297 /* 298 * We are done decoding Base-64 chars. Let's see if we ended 299 * on a byte boundary, and/or with erroneous trailing characters. 300 */ 301 302 if (ch == Pad64) { /* We got a pad char. */ 303 ch = *src++; /* Skip it, get next. */ 304 switch (state) { 305 case 0: /* Invalid = in first position */ 306 case 1: /* Invalid = in second position */ 307 return (-1); 308 309 case 2: /* Valid, means one byte of info */ 310 /* Skip any number of spaces. */ 311 for (; ch != '\0'; ch = *src++) 312 if (!isspace(ch)) 313 break; 314 /* Make sure there is another trailing = sign. */ 315 if (ch != Pad64) 316 return (-1); 317 ch = *src++; /* Skip the = */ 318 /* Fall through to "single trailing =" case. */ 319 /* FALLTHROUGH */ 320 321 case 3: /* Valid, means two bytes of info */ 322 /* 323 * We know this char is an =. Is there anything but 324 * whitespace after it? 325 */ 326 for (; ch != '\0'; ch = *src++) 327 if (!isspace(ch)) 328 return (-1); 329 330 /* 331 * Now make sure for cases 2 and 3 that the "extra" 332 * bits that slopped past the last full byte were 333 * zeros. If we don't check them, they become a 334 * subliminal channel. 335 */ 336 if (target && target[tarindex] != 0) 337 return (-1); 338 } 339 } else { 340 /* 341 * We ended by seeing the end of the string. Make sure we 342 * have no partial bytes lying around. 343 */ 344 if (state != 0) 345 return (-1); 346 } 347 348 return (tarindex); 349 } 350
Indexes created Fri Sep 26 20:09:58 GMT 2025