1 /* $OpenBSD: base64.c,v 1.5 2006/10/21 09:55:03 otto 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 static const char Base64[] = 60 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; 61 static const char Pad64 = '='; 62 63 /* (From RFC1521 and draft-ietf-dnssec-secext-03.txt) 64 The following encoding technique is taken from RFC 1521 by Borenstein 65 and Freed. It is reproduced here in a slightly edited form for 66 convenience. 67 68 A 65-character subset of US-ASCII is used, enabling 6 bits to be 69 represented per printable character. (The extra 65th character, "=", 70 is used to signify a special processing function.) 71 72 The encoding process represents 24-bit groups of input bits as output 73 strings of 4 encoded characters. Proceeding from left to right, a 74 24-bit input group is formed by concatenating 3 8-bit input groups. 75 These 24 bits are then treated as 4 concatenated 6-bit groups, each 76 of which is translated into a single digit in the base64 alphabet. 77 78 Each 6-bit group is used as an index into an array of 64 printable 79 characters. The character referenced by the index is placed in the 80 output string. 81 82 Table 1: The Base64 Alphabet 83 84 Value Encoding Value Encoding Value Encoding Value Encoding 85 0 A 17 R 34 i 51 z 86 1 B 18 S 35 j 52 0 87 2 C 19 T 36 k 53 1 88 3 D 20 U 37 l 54 2 89 4 E 21 V 38 m 55 3 90 5 F 22 W 39 n 56 4 91 6 G 23 X 40 o 57 5 92 7 H 24 Y 41 p 58 6 93 8 I 25 Z 42 q 59 7 94 9 J 26 a 43 r 60 8 95 10 K 27 b 44 s 61 9 96 11 L 28 c 45 t 62 + 97 12 M 29 d 46 u 63 / 98 13 N 30 e 47 v 99 14 O 31 f 48 w (pad) = 100 15 P 32 g 49 x 101 16 Q 33 h 50 y 102 103 Special processing is performed if fewer than 24 bits are available 104 at the end of the data being encoded. A full encoding quantum is 105 always completed at the end of a quantity. When fewer than 24 input 106 bits are available in an input group, zero bits are added (on the 107 right) to form an integral number of 6-bit groups. Padding at the 108 end of the data is performed using the '=' character. 109 110 Since all base64 input is an integral number of octets, only the 111 ------------------------------------------------- 112 following cases can arise: 113 114 (1) the final quantum of encoding input is an integral 115 multiple of 24 bits; here, the final unit of encoded 116 output will be an integral multiple of 4 characters 117 with no "=" padding, 118 (2) the final quantum of encoding input is exactly 8 bits; 119 here, the final unit of encoded output will be two 120 characters followed by two "=" padding characters, or 121 (3) the final quantum of encoding input is exactly 16 bits; 122 here, the final unit of encoded output will be three 123 characters followed by one "=" padding character. 124 */ 125 126 int 127 b64_ntop(src, srclength, target, targsize) 128 u_char const *src; 129 size_t srclength; 130 char *target; 131 size_t targsize; 132 { 133 size_t datalength = 0; 134 u_char input[3]; 135 u_char output[4]; 136 int i; 137 138 while (2 < srclength) { 139 input[0] = *src++; 140 input[1] = *src++; 141 input[2] = *src++; 142 srclength -= 3; 143 144 output[0] = input[0] >> 2; 145 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4); 146 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6); 147 output[3] = input[2] & 0x3f; 148 149 if (datalength + 4 > targsize) 150 return (-1); 151 target[datalength++] = Base64[output[0]]; 152 target[datalength++] = Base64[output[1]]; 153 target[datalength++] = Base64[output[2]]; 154 target[datalength++] = Base64[output[3]]; 155 } 156 157 /* Now we worry about padding. */ 158 if (0 != srclength) { 159 /* Get what's left. */ 160 input[0] = input[1] = input[2] = '\0'; 161 for (i = 0; i < srclength; i++) 162 input[i] = *src++; 163 164 output[0] = input[0] >> 2; 165 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4); 166 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6); 167 168 if (datalength + 4 > targsize) 169 return (-1); 170 target[datalength++] = Base64[output[0]]; 171 target[datalength++] = Base64[output[1]]; 172 if (srclength == 1) 173 target[datalength++] = Pad64; 174 else 175 target[datalength++] = Base64[output[2]]; 176 target[datalength++] = Pad64; 177 } 178 if (datalength >= targsize) 179 return (-1); 180 target[datalength] = '\0'; /* Returned value doesn't count \0. */ 181 return (datalength); 182 } 183 184 /* skips all whitespace anywhere. 185 converts characters, four at a time, starting at (or after) 186 src from base - 64 numbers into three 8 bit bytes in the target area. 187 it returns the number of data bytes stored at the target, or -1 on error. 188 */ 189 190 int 191 b64_pton(src, target, targsize) 192 char const *src; 193 u_char *target; 194 size_t targsize; 195 { 196 int tarindex, state, ch; 197 char *pos; 198 199 state = 0; 200 tarindex = 0; 201 202 while ((ch = *src++) != '\0') { 203 if (isspace(ch)) /* Skip whitespace anywhere. */ 204 continue; 205 206 if (ch == Pad64) 207 break; 208 209 pos = strchr(Base64, ch); 210 if (pos == 0) /* A non-base64 character. */ 211 return (-1); 212 213 switch (state) { 214 case 0: 215 if (target) { 216 if (tarindex >= targsize) 217 return (-1); 218 target[tarindex] = (pos - Base64) << 2; 219 } 220 state = 1; 221 break; 222 case 1: 223 if (target) { 224 if (tarindex + 1 >= targsize) 225 return (-1); 226 target[tarindex] |= (pos - Base64) >> 4; 227 target[tarindex+1] = ((pos - Base64) & 0x0f) 228 << 4 ; 229 } 230 tarindex++; 231 state = 2; 232 break; 233 case 2: 234 if (target) { 235 if (tarindex + 1 >= targsize) 236 return (-1); 237 target[tarindex] |= (pos - Base64) >> 2; 238 target[tarindex+1] = ((pos - Base64) & 0x03) 239 << 6; 240 } 241 tarindex++; 242 state = 3; 243 break; 244 case 3: 245 if (target) { 246 if (tarindex >= targsize) 247 return (-1); 248 target[tarindex] |= (pos - Base64); 249 } 250 tarindex++; 251 state = 0; 252 break; 253 } 254 } 255 256 /* 257 * We are done decoding Base-64 chars. Let's see if we ended 258 * on a byte boundary, and/or with erroneous trailing characters. 259 */ 260 261 if (ch == Pad64) { /* We got a pad char. */ 262 ch = *src++; /* Skip it, get next. */ 263 switch (state) { 264 case 0: /* Invalid = in first position */ 265 case 1: /* Invalid = in second position */ 266 return (-1); 267 268 case 2: /* Valid, means one byte of info */ 269 /* Skip any number of spaces. */ 270 for (; ch != '\0'; ch = *src++) 271 if (!isspace(ch)) 272 break; 273 /* Make sure there is another trailing = sign. */ 274 if (ch != Pad64) 275 return (-1); 276 ch = *src++; /* Skip the = */ 277 /* Fall through to "single trailing =" case. */ 278 /* FALLTHROUGH */ 279 280 case 3: /* Valid, means two bytes of info */ 281 /* 282 * We know this char is an =. Is there anything but 283 * whitespace after it? 284 */ 285 for (; ch != '\0'; ch = *src++) 286 if (!isspace(ch)) 287 return (-1); 288 289 /* 290 * Now make sure for cases 2 and 3 that the "extra" 291 * bits that slopped past the last full byte were 292 * zeros. If we don't check them, they become a 293 * subliminal channel. 294 */ 295 if (target && target[tarindex] != 0) 296 return (-1); 297 } 298 } else { 299 /* 300 * We ended by seeing the end of the string. Make sure we 301 * have no partial bytes lying around. 302 */ 303 if (state != 0) 304 return (-1); 305 } 306 307 return (tarindex); 308 } 309