base64.c revision 1.3
1 /* $NetBSD: base64.c,v 1.3 1997/07/13 19:57:30 christos 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 1.3 1997/07/13 19:57:30 christos Exp $"); 48 #endif /* LIBC_SCCS and not lint */ 49 50 51 #include <sys/types.h> 52 #include <sys/param.h> 53 #include <sys/socket.h> 54 #include <netinet/in.h> 55 #include <arpa/inet.h> 56 #include <arpa/nameser.h> 57 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 while (2 < srclength) { 151 input[0] = *src++; 152 input[1] = *src++; 153 input[2] = *src++; 154 srclength -= 3; 155 156 output[0] = input[0] >> 2; 157 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4); 158 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6); 159 output[3] = input[2] & 0x3f; 160 Assert(output[0] < 64); 161 Assert(output[1] < 64); 162 Assert(output[2] < 64); 163 Assert(output[3] < 64); 164 165 if (datalength + 4 > targsize) 166 return (-1); 167 target[datalength++] = Base64[output[0]]; 168 target[datalength++] = Base64[output[1]]; 169 target[datalength++] = Base64[output[2]]; 170 target[datalength++] = Base64[output[3]]; 171 } 172 173 /* Now we worry about padding. */ 174 if (0 != srclength) { 175 /* Get what's left. */ 176 input[0] = input[1] = input[2] = '\0'; 177 for (i = 0; i < srclength; i++) 178 input[i] = *src++; 179 180 output[0] = input[0] >> 2; 181 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4); 182 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6); 183 Assert(output[0] < 64); 184 Assert(output[1] < 64); 185 Assert(output[2] < 64); 186 187 if (datalength + 4 > targsize) 188 return (-1); 189 target[datalength++] = Base64[output[0]]; 190 target[datalength++] = Base64[output[1]]; 191 if (srclength == 1) 192 target[datalength++] = Pad64; 193 else 194 target[datalength++] = Base64[output[2]]; 195 target[datalength++] = Pad64; 196 } 197 if (datalength >= targsize) 198 return (-1); 199 target[datalength] = '\0'; /* Returned value doesn't count \0. */ 200 return (datalength); 201 } 202 203 /* skips all whitespace anywhere. 204 converts characters, four at a time, starting at (or after) 205 src from base - 64 numbers into three 8 bit bytes in the target area. 206 it returns the number of data bytes stored at the target, or -1 on error. 207 */ 208 209 int 210 b64_pton(src, target, targsize) 211 char const *src; 212 u_char *target; 213 size_t targsize; 214 { 215 int tarindex, state, ch; 216 char *pos; 217 218 state = 0; 219 tarindex = 0; 220 221 while ((ch = *src++) != '\0') { 222 if (isspace(ch)) /* Skip whitespace anywhere. */ 223 continue; 224 225 if (ch == Pad64) 226 break; 227 228 pos = strchr(Base64, ch); 229 if (pos == 0) /* A non-base64 character. */ 230 return (-1); 231 232 switch (state) { 233 case 0: 234 if (target) { 235 if (tarindex >= targsize) 236 return (-1); 237 target[tarindex] = (pos - Base64) << 2; 238 } 239 state = 1; 240 break; 241 case 1: 242 if (target) { 243 if (tarindex + 1 >= targsize) 244 return (-1); 245 target[tarindex] |= (pos - Base64) >> 4; 246 target[tarindex+1] = ((pos - Base64) & 0x0f) 247 << 4 ; 248 } 249 tarindex++; 250 state = 2; 251 break; 252 case 2: 253 if (target) { 254 if (tarindex + 1 >= targsize) 255 return (-1); 256 target[tarindex] |= (pos - Base64) >> 2; 257 target[tarindex+1] = ((pos - Base64) & 0x03) 258 << 6; 259 } 260 tarindex++; 261 state = 3; 262 break; 263 case 3: 264 if (target) { 265 if (tarindex >= targsize) 266 return (-1); 267 target[tarindex] |= (pos - Base64); 268 } 269 tarindex++; 270 state = 0; 271 break; 272 default: 273 abort(); 274 } 275 } 276 277 /* 278 * We are done decoding Base-64 chars. Let's see if we ended 279 * on a byte boundary, and/or with erroneous trailing characters. 280 */ 281 282 if (ch == Pad64) { /* We got a pad char. */ 283 ch = *src++; /* Skip it, get next. */ 284 switch (state) { 285 case 0: /* Invalid = in first position */ 286 case 1: /* Invalid = in second position */ 287 return (-1); 288 289 case 2: /* Valid, means one byte of info */ 290 /* Skip any number of spaces. */ 291 for (; ch != '\0'; ch = *src++) 292 if (!isspace(ch)) 293 break; 294 /* Make sure there is another trailing = sign. */ 295 if (ch != Pad64) 296 return (-1); 297 ch = *src++; /* Skip the = */ 298 /* Fall through to "single trailing =" case. */ 299 /* FALLTHROUGH */ 300 301 case 3: /* Valid, means two bytes of info */ 302 /* 303 * We know this char is an =. Is there anything but 304 * whitespace after it? 305 */ 306 for (; ch != '\0'; ch = *src++) 307 if (!isspace(ch)) 308 return (-1); 309 310 /* 311 * Now make sure for cases 2 and 3 that the "extra" 312 * bits that slopped past the last full byte were 313 * zeros. If we don't check them, they become a 314 * subliminal channel. 315 */ 316 if (target && target[tarindex] != 0) 317 return (-1); 318 } 319 } else { 320 /* 321 * We ended by seeing the end of the string. Make sure we 322 * have no partial bytes lying around. 323 */ 324 if (state != 0) 325 return (-1); 326 } 327 328 return (tarindex); 329 } 330
Indexes created Fri Sep 26 08:10:20 GMT 2025