1 /* $NetBSD: base64.c,v 1.14 2012/06/25 22:32:44 abs 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 1.4 2005/04/27 04:56:34 sra Exp"; 49 #else 50 __RCSID("$NetBSD: base64.c,v 1.14 2012/06/25 22:32:44 abs 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 _DIAGASSERT(__type_fit(int, datalength)); 207 return (int)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(char const *src, u_char *target, size_t targsize) 218 { 219 size_t tarindex; 220 int state, ch; 221 char *pos; 222 223 _DIAGASSERT(src != NULL); 224 _DIAGASSERT(target != NULL); 225 226 state = 0; 227 tarindex = 0; 228 229 while ((ch = (u_char) *src++) != '\0') { 230 if (isspace(ch)) /*%< Skip whitespace anywhere. */ 231 continue; 232 233 if (ch == Pad64) 234 break; 235 236 pos = strchr(Base64, ch); 237 if (pos == 0) /*%< A non-base64 character. */ 238 return (-1); 239 240 switch (state) { 241 case 0: 242 if (target) { 243 if ((size_t)tarindex >= targsize) 244 return (-1); 245 target[tarindex] = 246 (unsigned char)(pos - Base64) << 2; 247 } 248 state = 1; 249 break; 250 case 1: 251 if (target) { 252 if ((size_t)tarindex + 1 >= targsize) 253 return (-1); 254 target[tarindex] |= 255 (u_int32_t)(pos - Base64) >> 4; 256 target[tarindex+1] = 257 (unsigned char) 258 (((pos - Base64) & 0x0f) << 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] = 270 (unsigned char) 271 (((pos - Base64) & 0x03) << 6); 272 } 273 tarindex++; 274 state = 3; 275 break; 276 case 3: 277 if (target) { 278 if ((size_t)tarindex >= targsize) 279 return (-1); 280 target[tarindex] |= 281 (unsigned char)(pos - Base64); 282 } 283 tarindex++; 284 state = 0; 285 break; 286 default: 287 abort(); 288 } 289 } 290 291 /* 292 * We are done decoding Base-64 chars. Let's see if we ended 293 * on a byte boundary, and/or with erroneous trailing characters. 294 */ 295 296 if (ch == Pad64) { /*%< We got a pad char. */ 297 ch = *src++; /*%< Skip it, get next. */ 298 switch (state) { 299 case 0: /*%< Invalid = in first position */ 300 case 1: /*%< Invalid = in second position */ 301 return (-1); 302 303 case 2: /*%< Valid, means one byte of info */ 304 /* Skip any number of spaces. */ 305 for (; ch != '\0'; ch = (u_char) *src++) 306 if (!isspace(ch)) 307 break; 308 /* Make sure there is another trailing = sign. */ 309 if (ch != Pad64) 310 return (-1); 311 ch = *src++; /*%< Skip the = */ 312 /* Fall through to "single trailing =" case. */ 313 /* FALLTHROUGH */ 314 315 case 3: /*%< Valid, means two bytes of info */ 316 /* 317 * We know this char is an =. Is there anything but 318 * whitespace after it? 319 */ 320 for (; ch != '\0'; ch = (u_char) *src++) 321 if (!isspace(ch)) 322 return (-1); 323 324 /* 325 * Now make sure for cases 2 and 3 that the "extra" 326 * bits that slopped past the last full byte were 327 * zeros. If we don't check them, they become a 328 * subliminal channel. 329 */ 330 if (target && target[tarindex] != 0) 331 return (-1); 332 } 333 } else { 334 /* 335 * We ended by seeing the end of the string. Make sure we 336 * have no partial bytes lying around. 337 */ 338 if (state != 0) 339 return (-1); 340 } 341 342 _DIAGASSERT(__type_fit(int, tarindex)); 343 return (int)tarindex; 344 } 345 346 /*! \file */ 347