base64.c revision 1.7
1 /* $NetBSD: base64.c,v 1.7 2000/07/07 08:03:38 itohy 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 2000/07/07 08:03:38 itohy 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); 152 153 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 int tarindex, state, ch; 223 char *pos; 224 225 _DIAGASSERT(src != NULL); 226 _DIAGASSERT(target != NULL); 227 228 state = 0; 229 tarindex = 0; 230 231 while ((ch = (u_char) *src++) != '\0') { 232 if (isspace(ch)) /* Skip whitespace anywhere. */ 233 continue; 234 235 if (ch == Pad64) 236 break; 237 238 pos = strchr(Base64, ch); 239 if (pos == 0) /* A non-base64 character. */ 240 return (-1); 241 242 switch (state) { 243 case 0: 244 if (target) { 245 if (tarindex >= targsize) 246 return (-1); 247 target[tarindex] = (pos - Base64) << 2; 248 } 249 state = 1; 250 break; 251 case 1: 252 if (target) { 253 if (tarindex + 1 >= targsize) 254 return (-1); 255 target[tarindex] |= 256 (u_int32_t)(pos - Base64) >> 4; 257 target[tarindex+1] = ((pos - Base64) & 0x0f) 258 << 4 ; 259 } 260 tarindex++; 261 state = 2; 262 break; 263 case 2: 264 if (target) { 265 if (tarindex + 1 >= targsize) 266 return (-1); 267 target[tarindex] |= 268 (u_int32_t)(pos - Base64) >> 2; 269 target[tarindex+1] = ((pos - Base64) & 0x03) 270 << 6; 271 } 272 tarindex++; 273 state = 3; 274 break; 275 case 3: 276 if (target) { 277 if (tarindex >= targsize) 278 return (-1); 279 target[tarindex] |= (pos - Base64); 280 } 281 tarindex++; 282 state = 0; 283 break; 284 default: 285 abort(); 286 } 287 } 288 289 /* 290 * We are done decoding Base-64 chars. Let's see if we ended 291 * on a byte boundary, and/or with erroneous trailing characters. 292 */ 293 294 if (ch == Pad64) { /* We got a pad char. */ 295 ch = *src++; /* Skip it, get next. */ 296 switch (state) { 297 case 0: /* Invalid = in first position */ 298 case 1: /* Invalid = in second position */ 299 return (-1); 300 301 case 2: /* Valid, means one byte of info */ 302 /* Skip any number of spaces. */ 303 for (; ch != '\0'; ch = (u_char) *src++) 304 if (!isspace(ch)) 305 break; 306 /* Make sure there is another trailing = sign. */ 307 if (ch != Pad64) 308 return (-1); 309 ch = *src++; /* Skip the = */ 310 /* Fall through to "single trailing =" case. */ 311 /* FALLTHROUGH */ 312 313 case 3: /* Valid, means two bytes of info */ 314 /* 315 * We know this char is an =. Is there anything but 316 * whitespace after it? 317 */ 318 for (; ch != '\0'; ch = (u_char) *src++) 319 if (!isspace(ch)) 320 return (-1); 321 322 /* 323 * Now make sure for cases 2 and 3 that the "extra" 324 * bits that slopped past the last full byte were 325 * zeros. If we don't check them, they become a 326 * subliminal channel. 327 */ 328 if (target && target[tarindex] != 0) 329 return (-1); 330 } 331 } else { 332 /* 333 * We ended by seeing the end of the string. Make sure we 334 * have no partial bytes lying around. 335 */ 336 if (state != 0) 337 return (-1); 338 } 339 340 return (tarindex); 341 } 342
Indexes created Tue Sep 23 07:09:52 GMT 2025