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