1 /* $OpenBSD: base64.c,v 1.4 2002/01/02 23:00:10 deraadt 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 "includes.h" 46 47 #if (!defined(HAVE_B64_NTOP) && !defined(HAVE___B64_NTOP)) || (!defined(HAVE_B64_PTON) && !defined(HAVE___B64_PTON)) 48 49 #include <sys/types.h> 50 #include <sys/param.h> 51 #include <sys/socket.h> 52 #include <netinet/in.h> 53 #include <arpa/inet.h> 54 55 #include <ctype.h> 56 #include <stdio.h> 57 58 #include <stdlib.h> 59 #include <string.h> 60 61 #include "base64.h" 62 63 /* XXX abort illegal in library */ 64 #define Assert(Cond) if (!(Cond)) abort() 65 66 static const char Base64[] = 67 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; 68 static const char Pad64 = '='; 69 70 /* (From RFC1521 and draft-ietf-dnssec-secext-03.txt) 71 The following encoding technique is taken from RFC 1521 by Borenstein 72 and Freed. It is reproduced here in a slightly edited form for 73 convenience. 74 75 A 65-character subset of US-ASCII is used, enabling 6 bits to be 76 represented per printable character. (The extra 65th character, "=", 77 is used to signify a special processing function.) 78 79 The encoding process represents 24-bit groups of input bits as output 80 strings of 4 encoded characters. Proceeding from left to right, a 81 24-bit input group is formed by concatenating 3 8-bit input groups. 82 These 24 bits are then treated as 4 concatenated 6-bit groups, each 83 of which is translated into a single digit in the base64 alphabet. 84 85 Each 6-bit group is used as an index into an array of 64 printable 86 characters. The character referenced by the index is placed in the 87 output string. 88 89 Table 1: The Base64 Alphabet 90 91 Value Encoding Value Encoding Value Encoding Value Encoding 92 0 A 17 R 34 i 51 z 93 1 B 18 S 35 j 52 0 94 2 C 19 T 36 k 53 1 95 3 D 20 U 37 l 54 2 96 4 E 21 V 38 m 55 3 97 5 F 22 W 39 n 56 4 98 6 G 23 X 40 o 57 5 99 7 H 24 Y 41 p 58 6 100 8 I 25 Z 42 q 59 7 101 9 J 26 a 43 r 60 8 102 10 K 27 b 44 s 61 9 103 11 L 28 c 45 t 62 + 104 12 M 29 d 46 u 63 / 105 13 N 30 e 47 v 106 14 O 31 f 48 w (pad) = 107 15 P 32 g 49 x 108 16 Q 33 h 50 y 109 110 Special processing is performed if fewer than 24 bits are available 111 at the end of the data being encoded. A full encoding quantum is 112 always completed at the end of a quantity. When fewer than 24 input 113 bits are available in an input group, zero bits are added (on the 114 right) to form an integral number of 6-bit groups. Padding at the 115 end of the data is performed using the '=' character. 116 117 Since all base64 input is an integral number of octets, only the 118 ------------------------------------------------- 119 following cases can arise: 120 121 (1) the final quantum of encoding input is an integral 122 multiple of 24 bits; here, the final unit of encoded 123 output will be an integral multiple of 4 characters 124 with no "=" padding, 125 (2) the final quantum of encoding input is exactly 8 bits; 126 here, the final unit of encoded output will be two 127 characters followed by two "=" padding characters, or 128 (3) the final quantum of encoding input is exactly 16 bits; 129 here, the final unit of encoded output will be three 130 characters followed by one "=" padding character. 131 */ 132 133 #if !defined(HAVE_B64_NTOP) && !defined(HAVE___B64_NTOP) 134 int 135 b64_ntop(u_char const *src, size_t srclength, char *target, size_t targsize) 136 { 137 size_t datalength = 0; 138 u_char input[3]; 139 u_char output[4]; 140 int i; 141 142 while (2 < srclength) { 143 input[0] = *src++; 144 input[1] = *src++; 145 input[2] = *src++; 146 srclength -= 3; 147 148 output[0] = input[0] >> 2; 149 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4); 150 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6); 151 output[3] = input[2] & 0x3f; 152 Assert(output[0] < 64); 153 Assert(output[1] < 64); 154 Assert(output[2] < 64); 155 Assert(output[3] < 64); 156 157 if (datalength + 4 > targsize) 158 return (-1); 159 target[datalength++] = Base64[output[0]]; 160 target[datalength++] = Base64[output[1]]; 161 target[datalength++] = Base64[output[2]]; 162 target[datalength++] = Base64[output[3]]; 163 } 164 165 /* Now we worry about padding. */ 166 if (0 != srclength) { 167 /* Get what's left. */ 168 input[0] = input[1] = input[2] = '\0'; 169 for (i = 0; i < srclength; i++) 170 input[i] = *src++; 171 172 output[0] = input[0] >> 2; 173 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4); 174 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6); 175 Assert(output[0] < 64); 176 Assert(output[1] < 64); 177 Assert(output[2] < 64); 178 179 if (datalength + 4 > targsize) 180 return (-1); 181 target[datalength++] = Base64[output[0]]; 182 target[datalength++] = Base64[output[1]]; 183 if (srclength == 1) 184 target[datalength++] = Pad64; 185 else 186 target[datalength++] = Base64[output[2]]; 187 target[datalength++] = Pad64; 188 } 189 if (datalength >= targsize) 190 return (-1); 191 target[datalength] = '\0'; /* Returned value doesn't count \0. */ 192 return (datalength); 193 } 194 #endif /* !defined(HAVE_B64_NTOP) && !defined(HAVE___B64_NTOP) */ 195 196 #if !defined(HAVE_B64_PTON) && !defined(HAVE___B64_PTON) 197 198 /* skips all whitespace anywhere. 199 converts characters, four at a time, starting at (or after) 200 src from base - 64 numbers into three 8 bit bytes in the target area. 201 it returns the number of data bytes stored at the target, or -1 on error. 202 */ 203 204 int 205 b64_pton(char const *src, u_char *target, size_t targsize) 206 { 207 int tarindex, state, ch; 208 char *pos; 209 210 state = 0; 211 tarindex = 0; 212 213 while ((ch = *src++) != '\0') { 214 if (isspace(ch)) /* Skip whitespace anywhere. */ 215 continue; 216 217 if (ch == Pad64) 218 break; 219 220 pos = strchr(Base64, ch); 221 if (pos == 0) /* A non-base64 character. */ 222 return (-1); 223 224 switch (state) { 225 case 0: 226 if (target) { 227 if (tarindex >= targsize) 228 return (-1); 229 target[tarindex] = (pos - Base64) << 2; 230 } 231 state = 1; 232 break; 233 case 1: 234 if (target) { 235 if (tarindex + 1 >= targsize) 236 return (-1); 237 target[tarindex] |= (pos - Base64) >> 4; 238 target[tarindex+1] = ((pos - Base64) & 0x0f) 239 << 4 ; 240 } 241 tarindex++; 242 state = 2; 243 break; 244 case 2: 245 if (target) { 246 if (tarindex + 1 >= targsize) 247 return (-1); 248 target[tarindex] |= (pos - Base64) >> 2; 249 target[tarindex+1] = ((pos - Base64) & 0x03) 250 << 6; 251 } 252 tarindex++; 253 state = 3; 254 break; 255 case 3: 256 if (target) { 257 if (tarindex >= targsize) 258 return (-1); 259 target[tarindex] |= (pos - Base64); 260 } 261 tarindex++; 262 state = 0; 263 break; 264 } 265 } 266 267 /* 268 * We are done decoding Base-64 chars. Let's see if we ended 269 * on a byte boundary, and/or with erroneous trailing characters. 270 */ 271 272 if (ch == Pad64) { /* We got a pad char. */ 273 ch = *src++; /* Skip it, get next. */ 274 switch (state) { 275 case 0: /* Invalid = in first position */ 276 case 1: /* Invalid = in second position */ 277 return (-1); 278 279 case 2: /* Valid, means one byte of info */ 280 /* Skip any number of spaces. */ 281 for (; ch != '\0'; ch = *src++) 282 if (!isspace(ch)) 283 break; 284 /* Make sure there is another trailing = sign. */ 285 if (ch != Pad64) 286 return (-1); 287 ch = *src++; /* Skip the = */ 288 /* Fall through to "single trailing =" case. */ 289 /* FALLTHROUGH */ 290 291 case 3: /* Valid, means two bytes of info */ 292 /* 293 * We know this char is an =. Is there anything but 294 * whitespace after it? 295 */ 296 for (; ch != '\0'; ch = *src++) 297 if (!isspace(ch)) 298 return (-1); 299 300 /* 301 * Now make sure for cases 2 and 3 that the "extra" 302 * bits that slopped past the last full byte were 303 * zeros. If we don't check them, they become a 304 * subliminal channel. 305 */ 306 if (target && target[tarindex] != 0) 307 return (-1); 308 } 309 } else { 310 /* 311 * We ended by seeing the end of the string. Make sure we 312 * have no partial bytes lying around. 313 */ 314 if (state != 0) 315 return (-1); 316 } 317 318 return (tarindex); 319 } 320 321 #endif /* !defined(HAVE_B64_PTON) && !defined(HAVE___B64_PTON) */ 322 #endif 323