1 /* $OpenBSD: base64.c,v 1.3 1997/11/08 20:46:55 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 "config.h" 46 47 #if !defined(HAVE_B64_NTOP) && !defined(HAVE___B64_NTOP) 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 #define Assert(Cond) if (!(Cond)) abort() 64 65 static const char Base64[] = 66 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; 67 static const char Pad64 = '='; 68 69 /* (From RFC1521 and draft-ietf-dnssec-secext-03.txt) 70 The following encoding technique is taken from RFC 1521 by Borenstein 71 and Freed. It is reproduced here in a slightly edited form for 72 convenience. 73 74 A 65-character subset of US-ASCII is used, enabling 6 bits to be 75 represented per printable character. (The extra 65th character, "=", 76 is used to signify a special processing function.) 77 78 The encoding process represents 24-bit groups of input bits as output 79 strings of 4 encoded characters. Proceeding from left to right, a 80 24-bit input group is formed by concatenating 3 8-bit input groups. 81 These 24 bits are then treated as 4 concatenated 6-bit groups, each 82 of which is translated into a single digit in the base64 alphabet. 83 84 Each 6-bit group is used as an index into an array of 64 printable 85 characters. The character referenced by the index is placed in the 86 output string. 87 88 Table 1: The Base64 Alphabet 89 90 Value Encoding Value Encoding Value Encoding Value Encoding 91 0 A 17 R 34 i 51 z 92 1 B 18 S 35 j 52 0 93 2 C 19 T 36 k 53 1 94 3 D 20 U 37 l 54 2 95 4 E 21 V 38 m 55 3 96 5 F 22 W 39 n 56 4 97 6 G 23 X 40 o 57 5 98 7 H 24 Y 41 p 58 6 99 8 I 25 Z 42 q 59 7 100 9 J 26 a 43 r 60 8 101 10 K 27 b 44 s 61 9 102 11 L 28 c 45 t 62 + 103 12 M 29 d 46 u 63 / 104 13 N 30 e 47 v 105 14 O 31 f 48 w (pad) = 106 15 P 32 g 49 x 107 16 Q 33 h 50 y 108 109 Special processing is performed if fewer than 24 bits are available 110 at the end of the data being encoded. A full encoding quantum is 111 always completed at the end of a quantity. When fewer than 24 input 112 bits are available in an input group, zero bits are added (on the 113 right) to form an integral number of 6-bit groups. Padding at the 114 end of the data is performed using the '=' character. 115 116 Since all base64 input is an integral number of octets, only the 117 ------------------------------------------------- 118 following cases can arise: 119 120 (1) the final quantum of encoding input is an integral 121 multiple of 24 bits; here, the final unit of encoded 122 output will be an integral multiple of 4 characters 123 with no "=" padding, 124 (2) the final quantum of encoding input is exactly 8 bits; 125 here, the final unit of encoded output will be two 126 characters followed by two "=" padding characters, or 127 (3) the final quantum of encoding input is exactly 16 bits; 128 here, the final unit of encoded output will be three 129 characters followed by one "=" padding character. 130 */ 131 132 int 133 b64_ntop(u_char const *src, size_t srclength, char *target, size_t targsize) 134 { 135 size_t datalength = 0; 136 u_char input[3]; 137 u_char output[4]; 138 int i; 139 140 while (2 < srclength) { 141 input[0] = *src++; 142 input[1] = *src++; 143 input[2] = *src++; 144 srclength -= 3; 145 146 output[0] = input[0] >> 2; 147 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4); 148 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6); 149 output[3] = input[2] & 0x3f; 150 Assert(output[0] < 64); 151 Assert(output[1] < 64); 152 Assert(output[2] < 64); 153 Assert(output[3] < 64); 154 155 if (datalength + 4 > targsize) 156 return (-1); 157 target[datalength++] = Base64[output[0]]; 158 target[datalength++] = Base64[output[1]]; 159 target[datalength++] = Base64[output[2]]; 160 target[datalength++] = Base64[output[3]]; 161 } 162 163 /* Now we worry about padding. */ 164 if (0 != srclength) { 165 /* Get what's left. */ 166 input[0] = input[1] = input[2] = '\0'; 167 for (i = 0; i < srclength; i++) 168 input[i] = *src++; 169 170 output[0] = input[0] >> 2; 171 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4); 172 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6); 173 Assert(output[0] < 64); 174 Assert(output[1] < 64); 175 Assert(output[2] < 64); 176 177 if (datalength + 4 > targsize) 178 return (-1); 179 target[datalength++] = Base64[output[0]]; 180 target[datalength++] = Base64[output[1]]; 181 if (srclength == 1) 182 target[datalength++] = Pad64; 183 else 184 target[datalength++] = Base64[output[2]]; 185 target[datalength++] = Pad64; 186 } 187 if (datalength >= targsize) 188 return (-1); 189 target[datalength] = '\0'; /* Returned value doesn't count \0. */ 190 return (datalength); 191 } 192 193 /* skips all whitespace anywhere. 194 converts characters, four at a time, starting at (or after) 195 src from base - 64 numbers into three 8 bit bytes in the target area. 196 it returns the number of data bytes stored at the target, or -1 on error. 197 */ 198 199 int 200 b64_pton(char const *src, u_char *target, size_t targsize) 201 { 202 int tarindex, state, ch; 203 char *pos; 204 205 state = 0; 206 tarindex = 0; 207 208 while ((ch = *src++) != '\0') { 209 if (isspace(ch)) /* Skip whitespace anywhere. */ 210 continue; 211 212 if (ch == Pad64) 213 break; 214 215 pos = strchr(Base64, ch); 216 if (pos == 0) /* A non-base64 character. */ 217 return (-1); 218 219 switch (state) { 220 case 0: 221 if (target) { 222 if (tarindex >= targsize) 223 return (-1); 224 target[tarindex] = (pos - Base64) << 2; 225 } 226 state = 1; 227 break; 228 case 1: 229 if (target) { 230 if (tarindex + 1 >= targsize) 231 return (-1); 232 target[tarindex] |= (pos - Base64) >> 4; 233 target[tarindex+1] = ((pos - Base64) & 0x0f) 234 << 4 ; 235 } 236 tarindex++; 237 state = 2; 238 break; 239 case 2: 240 if (target) { 241 if (tarindex + 1 >= targsize) 242 return (-1); 243 target[tarindex] |= (pos - Base64) >> 2; 244 target[tarindex+1] = ((pos - Base64) & 0x03) 245 << 6; 246 } 247 tarindex++; 248 state = 3; 249 break; 250 case 3: 251 if (target) { 252 if (tarindex >= targsize) 253 return (-1); 254 target[tarindex] |= (pos - Base64); 255 } 256 tarindex++; 257 state = 0; 258 break; 259 } 260 } 261 262 /* 263 * We are done decoding Base-64 chars. Let's see if we ended 264 * on a byte boundary, and/or with erroneous trailing characters. 265 */ 266 267 if (ch == Pad64) { /* We got a pad char. */ 268 ch = *src++; /* Skip it, get next. */ 269 switch (state) { 270 case 0: /* Invalid = in first position */ 271 case 1: /* Invalid = in second position */ 272 return (-1); 273 274 case 2: /* Valid, means one byte of info */ 275 /* Skip any number of spaces. */ 276 for (; ch != '\0'; ch = *src++) 277 if (!isspace(ch)) 278 break; 279 /* Make sure there is another trailing = sign. */ 280 if (ch != Pad64) 281 return (-1); 282 ch = *src++; /* Skip the = */ 283 /* Fall through to "single trailing =" case. */ 284 /* FALLTHROUGH */ 285 286 case 3: /* Valid, means two bytes of info */ 287 /* 288 * We know this char is an =. Is there anything but 289 * whitespace after it? 290 */ 291 for (; ch != '\0'; ch = *src++) 292 if (!isspace(ch)) 293 return (-1); 294 295 /* 296 * Now make sure for cases 2 and 3 that the "extra" 297 * bits that slopped past the last full byte were 298 * zeros. If we don't check them, they become a 299 * subliminal channel. 300 */ 301 if (target && target[tarindex] != 0) 302 return (-1); 303 } 304 } else { 305 /* 306 * We ended by seeing the end of the string. Make sure we 307 * have no partial bytes lying around. 308 */ 309 if (state != 0) 310 return (-1); 311 } 312 313 return (tarindex); 314 } 315 316 #endif /* !defined(HAVE_B64_NTOP) && !defined(HAVE___B64_NTOP) */ 317