base64.c revision 1.9
1 /* $NetBSD: base64.c,v 1.9 2007/01/27 22:26:44 christos Exp $ */ 2 3 /* 4 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC") 5 * Copyright (c) 1996-1999 by Internet Software Consortium. 6 * 7 * Permission to use, copy, modify, and distribute this software for any 8 * purpose with or without fee is hereby granted, provided that the above 9 * copyright notice and this permission notice appear in all copies. 10 * 11 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES 12 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 13 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR 14 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 15 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 16 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT 17 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS 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 #if 0 48 static const char rcsid[] = "Id: base64.c,v 1.3.18.1 2005/04/27 05:01:05 sra Exp"; 49 #else 50 __RCSID("$NetBSD: base64.c,v 1.9 2007/01/27 22:26:44 christos Exp $"); 51 #endif 52 #endif /* LIBC_SCCS and not lint */ 53 54 #include "port_before.h" 55 56 #include <sys/types.h> 57 #include <sys/param.h> 58 #include <sys/socket.h> 59 60 #include <netinet/in.h> 61 #include <arpa/inet.h> 62 #include <arpa/nameser.h> 63 64 #include <assert.h> 65 #include <ctype.h> 66 #include <resolv.h> 67 #include <stdio.h> 68 #include <stdlib.h> 69 #include <string.h> 70 71 #include "port_after.h" 72 73 #define Assert(Cond) if (!(Cond)) abort() 74 75 static const char Base64[] = 76 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; 77 static const char Pad64 = '='; 78 79 /* (From RFC1521 and draft-ietf-dnssec-secext-03.txt) 80 The following encoding technique is taken from RFC1521 by Borenstein 81 and Freed. It is reproduced here in a slightly edited form for 82 convenience. 83 84 A 65-character subset of US-ASCII is used, enabling 6 bits to be 85 represented per printable character. (The extra 65th character, "=", 86 is used to signify a special processing function.) 87 88 The encoding process represents 24-bit groups of input bits as output 89 strings of 4 encoded characters. Proceeding from left to right, a 90 24-bit input group is formed by concatenating 3 8-bit input groups. 91 These 24 bits are then treated as 4 concatenated 6-bit groups, each 92 of which is translated into a single digit in the base64 alphabet. 93 94 Each 6-bit group is used as an index into an array of 64 printable 95 characters. The character referenced by the index is placed in the 96 output string. 97 98 Table 1: The Base64 Alphabet 99 100 Value Encoding Value Encoding Value Encoding Value Encoding 101 0 A 17 R 34 i 51 z 102 1 B 18 S 35 j 52 0 103 2 C 19 T 36 k 53 1 104 3 D 20 U 37 l 54 2 105 4 E 21 V 38 m 55 3 106 5 F 22 W 39 n 56 4 107 6 G 23 X 40 o 57 5 108 7 H 24 Y 41 p 58 6 109 8 I 25 Z 42 q 59 7 110 9 J 26 a 43 r 60 8 111 10 K 27 b 44 s 61 9 112 11 L 28 c 45 t 62 + 113 12 M 29 d 46 u 63 / 114 13 N 30 e 47 v 115 14 O 31 f 48 w (pad) = 116 15 P 32 g 49 x 117 16 Q 33 h 50 y 118 119 Special processing is performed if fewer than 24 bits are available 120 at the end of the data being encoded. A full encoding quantum is 121 always completed at the end of a quantity. When fewer than 24 input 122 bits are available in an input group, zero bits are added (on the 123 right) to form an integral number of 6-bit groups. Padding at the 124 end of the data is performed using the '=' character. 125 126 Since all base64 input is an integral number of octets, only the 127 ------------------------------------------------- 128 following cases can arise: 129 130 (1) the final quantum of encoding input is an integral 131 multiple of 24 bits; here, the final unit of encoded 132 output will be an integral multiple of 4 characters 133 with no "=" padding, 134 (2) the final quantum of encoding input is exactly 8 bits; 135 here, the final unit of encoded output will be two 136 characters followed by two "=" padding characters, or 137 (3) the final quantum of encoding input is exactly 16 bits; 138 here, the final unit of encoded output will be three 139 characters followed by one "=" padding character. 140 */ 141 142 int 143 b64_ntop(u_char const *src, size_t srclength, char *target, size_t targsize) { 144 size_t datalength = 0; 145 u_char input[3]; 146 u_char output[4]; 147 size_t i; 148 149 _DIAGASSERT(src != NULL); 150 _DIAGASSERT(target != NULL); 151 152 while (2U < srclength) { 153 input[0] = *src++; 154 input[1] = *src++; 155 input[2] = *src++; 156 srclength -= 3; 157 158 output[0] = (u_int32_t)input[0] >> 2; 159 output[1] = ((u_int32_t)(input[0] & 0x03) << 4) + 160 ((u_int32_t)input[1] >> 4); 161 output[2] = ((u_int32_t)(input[1] & 0x0f) << 2) + 162 ((u_int32_t)input[2] >> 6); 163 output[3] = input[2] & 0x3f; 164 Assert(output[0] < 64); 165 Assert(output[1] < 64); 166 Assert(output[2] < 64); 167 Assert(output[3] < 64); 168 169 if (datalength + 4 > targsize) 170 return (-1); 171 target[datalength++] = Base64[output[0]]; 172 target[datalength++] = Base64[output[1]]; 173 target[datalength++] = Base64[output[2]]; 174 target[datalength++] = Base64[output[3]]; 175 } 176 177 /* Now we worry about padding. */ 178 if (0U != srclength) { 179 /* Get what's left. */ 180 input[0] = input[1] = input[2] = '\0'; 181 for (i = 0; i < srclength; i++) 182 input[i] = *src++; 183 184 output[0] = (u_int32_t)input[0] >> 2; 185 output[1] = ((u_int32_t)(input[0] & 0x03) << 4) + 186 ((u_int32_t)input[1] >> 4); 187 output[2] = ((u_int32_t)(input[1] & 0x0f) << 2) + 188 ((u_int32_t)input[2] >> 6); 189 Assert(output[0] < 64); 190 Assert(output[1] < 64); 191 Assert(output[2] < 64); 192 193 if (datalength + 4 > targsize) 194 return (-1); 195 target[datalength++] = Base64[output[0]]; 196 target[datalength++] = Base64[output[1]]; 197 if (srclength == 1U) 198 target[datalength++] = Pad64; 199 else 200 target[datalength++] = Base64[output[2]]; 201 target[datalength++] = Pad64; 202 } 203 if (datalength >= targsize) 204 return (-1); 205 target[datalength] = '\0'; /*%< Returned value doesn't count \\0. */ 206 return (datalength); 207 } 208 209 /* skips all whitespace anywhere. 210 converts characters, four at a time, starting at (or after) 211 src from base - 64 numbers into three 8 bit bytes in the target area. 212 it returns the number of data bytes stored at the target, or -1 on error. 213 */ 214 215 int 216 b64_pton(src, target, targsize) 217 char const *src; 218 u_char *target; 219 size_t targsize; 220 { 221 size_t tarindex; 222 int 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 ((size_t)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 ((size_t)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 ((size_t)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 ((size_t)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 } 342 343 /*! \file */ 344
Indexes created Tue Sep 23 02:09:52 GMT 2025