base64.c revision 1.4
1 /* $NetBSD: base64.c,v 1.4 1998/11/13 15:46:52 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 1.4 1998/11/13 15:46:52 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] = (u_int32_t)input[0] >> 2; 157 output[1] = ((u_int32_t)(input[0] & 0x03) << 4) + 158 ((u_int32_t)input[1] >> 4); 159 output[2] = ((u_int32_t)(input[1] & 0x0f) << 2) + 160 ((u_int32_t)input[2] >> 6); 161 output[3] = input[2] & 0x3f; 162 Assert(output[0] < 64); 163 Assert(output[1] < 64); 164 Assert(output[2] < 64); 165 Assert(output[3] < 64); 166 167 if (datalength + 4 > targsize) 168 return (-1); 169 target[datalength++] = Base64[output[0]]; 170 target[datalength++] = Base64[output[1]]; 171 target[datalength++] = Base64[output[2]]; 172 target[datalength++] = Base64[output[3]]; 173 } 174 175 /* Now we worry about padding. */ 176 if (0 != srclength) { 177 /* Get what's left. */ 178 input[0] = input[1] = input[2] = '\0'; 179 for (i = 0; i < srclength; i++) 180 input[i] = *src++; 181 182 output[0] = (u_int32_t)input[0] >> 2; 183 output[1] = ((u_int32_t)(input[0] & 0x03) << 4) + 184 ((u_int32_t)input[1] >> 4); 185 output[2] = ((u_int32_t)(input[1] & 0x0f) << 2) + 186 ((u_int32_t)input[2] >> 6); 187 Assert(output[0] < 64); 188 Assert(output[1] < 64); 189 Assert(output[2] < 64); 190 191 if (datalength + 4 > targsize) 192 return (-1); 193 target[datalength++] = Base64[output[0]]; 194 target[datalength++] = Base64[output[1]]; 195 if (srclength == 1) 196 target[datalength++] = Pad64; 197 else 198 target[datalength++] = Base64[output[2]]; 199 target[datalength++] = Pad64; 200 } 201 if (datalength >= targsize) 202 return (-1); 203 target[datalength] = '\0'; /* Returned value doesn't count \0. */ 204 return (datalength); 205 } 206 207 /* skips all whitespace anywhere. 208 converts characters, four at a time, starting at (or after) 209 src from base - 64 numbers into three 8 bit bytes in the target area. 210 it returns the number of data bytes stored at the target, or -1 on error. 211 */ 212 213 int 214 b64_pton(src, target, targsize) 215 char const *src; 216 u_char *target; 217 size_t targsize; 218 { 219 int tarindex, state, ch; 220 char *pos; 221 222 state = 0; 223 tarindex = 0; 224 225 while ((ch = *src++) != '\0') { 226 if (isspace(ch)) /* Skip whitespace anywhere. */ 227 continue; 228 229 if (ch == Pad64) 230 break; 231 232 pos = strchr(Base64, ch); 233 if (pos == 0) /* A non-base64 character. */ 234 return (-1); 235 236 switch (state) { 237 case 0: 238 if (target) { 239 if (tarindex >= targsize) 240 return (-1); 241 target[tarindex] = (pos - Base64) << 2; 242 } 243 state = 1; 244 break; 245 case 1: 246 if (target) { 247 if (tarindex + 1 >= targsize) 248 return (-1); 249 target[tarindex] |= 250 (u_int32_t)(pos - Base64) >> 4; 251 target[tarindex+1] = ((pos - Base64) & 0x0f) 252 << 4 ; 253 } 254 tarindex++; 255 state = 2; 256 break; 257 case 2: 258 if (target) { 259 if (tarindex + 1 >= targsize) 260 return (-1); 261 target[tarindex] |= 262 (u_int32_t)(pos - Base64) >> 2; 263 target[tarindex+1] = ((pos - Base64) & 0x03) 264 << 6; 265 } 266 tarindex++; 267 state = 3; 268 break; 269 case 3: 270 if (target) { 271 if (tarindex >= targsize) 272 return (-1); 273 target[tarindex] |= (pos - Base64); 274 } 275 tarindex++; 276 state = 0; 277 break; 278 default: 279 abort(); 280 } 281 } 282 283 /* 284 * We are done decoding Base-64 chars. Let's see if we ended 285 * on a byte boundary, and/or with erroneous trailing characters. 286 */ 287 288 if (ch == Pad64) { /* We got a pad char. */ 289 ch = *src++; /* Skip it, get next. */ 290 switch (state) { 291 case 0: /* Invalid = in first position */ 292 case 1: /* Invalid = in second position */ 293 return (-1); 294 295 case 2: /* Valid, means one byte of info */ 296 /* Skip any number of spaces. */ 297 for (; ch != '\0'; ch = *src++) 298 if (!isspace(ch)) 299 break; 300 /* Make sure there is another trailing = sign. */ 301 if (ch != Pad64) 302 return (-1); 303 ch = *src++; /* Skip the = */ 304 /* Fall through to "single trailing =" case. */ 305 /* FALLTHROUGH */ 306 307 case 3: /* Valid, means two bytes of info */ 308 /* 309 * We know this char is an =. Is there anything but 310 * whitespace after it? 311 */ 312 for (; ch != '\0'; ch = *src++) 313 if (!isspace(ch)) 314 return (-1); 315 316 /* 317 * Now make sure for cases 2 and 3 that the "extra" 318 * bits that slopped past the last full byte were 319 * zeros. If we don't check them, they become a 320 * subliminal channel. 321 */ 322 if (target && target[tarindex] != 0) 323 return (-1); 324 } 325 } else { 326 /* 327 * We ended by seeing the end of the string. Make sure we 328 * have no partial bytes lying around. 329 */ 330 if (state != 0) 331 return (-1); 332 } 333 334 return (tarindex); 335 } 336
Indexes created Wed Sep 24 05:09:52 GMT 2025