base64.c revision 1.2
1 /* $NetBSD: base64.c,v 1.2 1997/04/13 10:30:31 mrg 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 #if defined(LIBC_SCCS) && !defined(lint) 46 static char rcsid[] = "$NetBSD: base64.c,v 1.2 1997/04/13 10:30:31 mrg Exp $"; 47 #endif /* LIBC_SCCS and not lint */ 48 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 <ctype.h> 58 #include <resolv.h> 59 #include <stdio.h> 60 61 #if defined(BSD) && (BSD >= 199103) && defined(AF_INET6) 62 # include <stdlib.h> 63 # include <string.h> 64 #else 65 # include "../conf/portability.h" 66 #endif 67 68 #define Assert(Cond) if (!(Cond)) abort() 69 70 static const char Base64[] = 71 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; 72 static const char Pad64 = '='; 73 74 /* (From RFC1521 and draft-ietf-dnssec-secext-03.txt) 75 The following encoding technique is taken from RFC 1521 by Borenstein 76 and Freed. It is reproduced here in a slightly edited form for 77 convenience. 78 79 A 65-character subset of US-ASCII is used, enabling 6 bits to be 80 represented per printable character. (The extra 65th character, "=", 81 is used to signify a special processing function.) 82 83 The encoding process represents 24-bit groups of input bits as output 84 strings of 4 encoded characters. Proceeding from left to right, a 85 24-bit input group is formed by concatenating 3 8-bit input groups. 86 These 24 bits are then treated as 4 concatenated 6-bit groups, each 87 of which is translated into a single digit in the base64 alphabet. 88 89 Each 6-bit group is used as an index into an array of 64 printable 90 characters. The character referenced by the index is placed in the 91 output string. 92 93 Table 1: The Base64 Alphabet 94 95 Value Encoding Value Encoding Value Encoding Value Encoding 96 0 A 17 R 34 i 51 z 97 1 B 18 S 35 j 52 0 98 2 C 19 T 36 k 53 1 99 3 D 20 U 37 l 54 2 100 4 E 21 V 38 m 55 3 101 5 F 22 W 39 n 56 4 102 6 G 23 X 40 o 57 5 103 7 H 24 Y 41 p 58 6 104 8 I 25 Z 42 q 59 7 105 9 J 26 a 43 r 60 8 106 10 K 27 b 44 s 61 9 107 11 L 28 c 45 t 62 + 108 12 M 29 d 46 u 63 / 109 13 N 30 e 47 v 110 14 O 31 f 48 w (pad) = 111 15 P 32 g 49 x 112 16 Q 33 h 50 y 113 114 Special processing is performed if fewer than 24 bits are available 115 at the end of the data being encoded. A full encoding quantum is 116 always completed at the end of a quantity. When fewer than 24 input 117 bits are available in an input group, zero bits are added (on the 118 right) to form an integral number of 6-bit groups. Padding at the 119 end of the data is performed using the '=' character. 120 121 Since all base64 input is an integral number of octets, only the 122 ------------------------------------------------- 123 following cases can arise: 124 125 (1) the final quantum of encoding input is an integral 126 multiple of 24 bits; here, the final unit of encoded 127 output will be an integral multiple of 4 characters 128 with no "=" padding, 129 (2) the final quantum of encoding input is exactly 8 bits; 130 here, the final unit of encoded output will be two 131 characters followed by two "=" padding characters, or 132 (3) the final quantum of encoding input is exactly 16 bits; 133 here, the final unit of encoded output will be three 134 characters followed by one "=" padding character. 135 */ 136 137 int 138 b64_ntop(src, srclength, target, targsize) 139 u_char const *src; 140 size_t srclength; 141 char *target; 142 size_t targsize; 143 { 144 size_t datalength = 0; 145 u_char input[3]; 146 u_char output[4]; 147 int i; 148 149 while (2 < srclength) { 150 input[0] = *src++; 151 input[1] = *src++; 152 input[2] = *src++; 153 srclength -= 3; 154 155 output[0] = input[0] >> 2; 156 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4); 157 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6); 158 output[3] = input[2] & 0x3f; 159 Assert(output[0] < 64); 160 Assert(output[1] < 64); 161 Assert(output[2] < 64); 162 Assert(output[3] < 64); 163 164 if (datalength + 4 > targsize) 165 return (-1); 166 target[datalength++] = Base64[output[0]]; 167 target[datalength++] = Base64[output[1]]; 168 target[datalength++] = Base64[output[2]]; 169 target[datalength++] = Base64[output[3]]; 170 } 171 172 /* Now we worry about padding. */ 173 if (0 != srclength) { 174 /* Get what's left. */ 175 input[0] = input[1] = input[2] = '\0'; 176 for (i = 0; i < srclength; i++) 177 input[i] = *src++; 178 179 output[0] = input[0] >> 2; 180 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4); 181 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6); 182 Assert(output[0] < 64); 183 Assert(output[1] < 64); 184 Assert(output[2] < 64); 185 186 if (datalength + 4 > targsize) 187 return (-1); 188 target[datalength++] = Base64[output[0]]; 189 target[datalength++] = Base64[output[1]]; 190 if (srclength == 1) 191 target[datalength++] = Pad64; 192 else 193 target[datalength++] = Base64[output[2]]; 194 target[datalength++] = Pad64; 195 } 196 if (datalength >= targsize) 197 return (-1); 198 target[datalength] = '\0'; /* Returned value doesn't count \0. */ 199 return (datalength); 200 } 201 202 /* skips all whitespace anywhere. 203 converts characters, four at a time, starting at (or after) 204 src from base - 64 numbers into three 8 bit bytes in the target area. 205 it returns the number of data bytes stored at the target, or -1 on error. 206 */ 207 208 int 209 b64_pton(src, target, targsize) 210 char const *src; 211 u_char *target; 212 size_t targsize; 213 { 214 int tarindex, state, ch; 215 char *pos; 216 217 state = 0; 218 tarindex = 0; 219 220 while ((ch = *src++) != '\0') { 221 if (isspace(ch)) /* Skip whitespace anywhere. */ 222 continue; 223 224 if (ch == Pad64) 225 break; 226 227 pos = strchr(Base64, ch); 228 if (pos == 0) /* A non-base64 character. */ 229 return (-1); 230 231 switch (state) { 232 case 0: 233 if (target) { 234 if (tarindex >= targsize) 235 return (-1); 236 target[tarindex] = (pos - Base64) << 2; 237 } 238 state = 1; 239 break; 240 case 1: 241 if (target) { 242 if (tarindex + 1 >= targsize) 243 return (-1); 244 target[tarindex] |= (pos - Base64) >> 4; 245 target[tarindex+1] = ((pos - Base64) & 0x0f) 246 << 4 ; 247 } 248 tarindex++; 249 state = 2; 250 break; 251 case 2: 252 if (target) { 253 if (tarindex + 1 >= targsize) 254 return (-1); 255 target[tarindex] |= (pos - Base64) >> 2; 256 target[tarindex+1] = ((pos - Base64) & 0x03) 257 << 6; 258 } 259 tarindex++; 260 state = 3; 261 break; 262 case 3: 263 if (target) { 264 if (tarindex >= targsize) 265 return (-1); 266 target[tarindex] |= (pos - Base64); 267 } 268 tarindex++; 269 state = 0; 270 break; 271 default: 272 abort(); 273 } 274 } 275 276 /* 277 * We are done decoding Base-64 chars. Let's see if we ended 278 * on a byte boundary, and/or with erroneous trailing characters. 279 */ 280 281 if (ch == Pad64) { /* We got a pad char. */ 282 ch = *src++; /* Skip it, get next. */ 283 switch (state) { 284 case 0: /* Invalid = in first position */ 285 case 1: /* Invalid = in second position */ 286 return (-1); 287 288 case 2: /* Valid, means one byte of info */ 289 /* Skip any number of spaces. */ 290 for (NULL; ch != '\0'; ch = *src++) 291 if (!isspace(ch)) 292 break; 293 /* Make sure there is another trailing = sign. */ 294 if (ch != Pad64) 295 return (-1); 296 ch = *src++; /* Skip the = */ 297 /* Fall through to "single trailing =" case. */ 298 /* FALLTHROUGH */ 299 300 case 3: /* Valid, means two bytes of info */ 301 /* 302 * We know this char is an =. Is there anything but 303 * whitespace after it? 304 */ 305 for (NULL; ch != '\0'; ch = *src++) 306 if (!isspace(ch)) 307 return (-1); 308 309 /* 310 * Now make sure for cases 2 and 3 that the "extra" 311 * bits that slopped past the last full byte were 312 * zeros. If we don't check them, they become a 313 * subliminal channel. 314 */ 315 if (target && target[tarindex] != 0) 316 return (-1); 317 } 318 } else { 319 /* 320 * We ended by seeing the end of the string. Make sure we 321 * have no partial bytes lying around. 322 */ 323 if (state != 0) 324 return (-1); 325 } 326 327 return (tarindex); 328 } 329
Indexes created Fri Sep 26 08:10:20 GMT 2025