1 /* $OpenBSD: base64.c,v 1.8 2015/01/16 16:48:51 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/socket.h> 47 #include <netinet/in.h> 48 #include <arpa/inet.h> 49 #include <arpa/nameser.h> 50 51 #include <ctype.h> 52 #include <resolv.h> 53 #include <stdio.h> 54 55 #include <stdlib.h> 56 #include <string.h> 57 58 static const char Base64[] = 59 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; 60 static const char Pad64 = '='; 61 62 /* (From RFC1521 and draft-ietf-dnssec-secext-03.txt) 63 The following encoding technique is taken from RFC 1521 by Borenstein 64 and Freed. It is reproduced here in a slightly edited form for 65 convenience. 66 67 A 65-character subset of US-ASCII is used, enabling 6 bits to be 68 represented per printable character. (The extra 65th character, "=", 69 is used to signify a special processing function.) 70 71 The encoding process represents 24-bit groups of input bits as output 72 strings of 4 encoded characters. Proceeding from left to right, a 73 24-bit input group is formed by concatenating 3 8-bit input groups. 74 These 24 bits are then treated as 4 concatenated 6-bit groups, each 75 of which is translated into a single digit in the base64 alphabet. 76 77 Each 6-bit group is used as an index into an array of 64 printable 78 characters. The character referenced by the index is placed in the 79 output string. 80 81 Table 1: The Base64 Alphabet 82 83 Value Encoding Value Encoding Value Encoding Value Encoding 84 0 A 17 R 34 i 51 z 85 1 B 18 S 35 j 52 0 86 2 C 19 T 36 k 53 1 87 3 D 20 U 37 l 54 2 88 4 E 21 V 38 m 55 3 89 5 F 22 W 39 n 56 4 90 6 G 23 X 40 o 57 5 91 7 H 24 Y 41 p 58 6 92 8 I 25 Z 42 q 59 7 93 9 J 26 a 43 r 60 8 94 10 K 27 b 44 s 61 9 95 11 L 28 c 45 t 62 + 96 12 M 29 d 46 u 63 / 97 13 N 30 e 47 v 98 14 O 31 f 48 w (pad) = 99 15 P 32 g 49 x 100 16 Q 33 h 50 y 101 102 Special processing is performed if fewer than 24 bits are available 103 at the end of the data being encoded. A full encoding quantum is 104 always completed at the end of a quantity. When fewer than 24 input 105 bits are available in an input group, zero bits are added (on the 106 right) to form an integral number of 6-bit groups. Padding at the 107 end of the data is performed using the '=' character. 108 109 Since all base64 input is an integral number of octets, only the 110 ------------------------------------------------- 111 following cases can arise: 112 113 (1) the final quantum of encoding input is an integral 114 multiple of 24 bits; here, the final unit of encoded 115 output will be an integral multiple of 4 characters 116 with no "=" padding, 117 (2) the final quantum of encoding input is exactly 8 bits; 118 here, the final unit of encoded output will be two 119 characters followed by two "=" padding characters, or 120 (3) the final quantum of encoding input is exactly 16 bits; 121 here, the final unit of encoded output will be three 122 characters followed by one "=" padding character. 123 */ 124 125 int 126 b64_ntop(src, srclength, target, targsize) 127 u_char const *src; 128 size_t srclength; 129 char *target; 130 size_t targsize; 131 { 132 size_t datalength = 0; 133 u_char input[3]; 134 u_char output[4]; 135 int i; 136 137 while (2 < srclength) { 138 input[0] = *src++; 139 input[1] = *src++; 140 input[2] = *src++; 141 srclength -= 3; 142 143 output[0] = input[0] >> 2; 144 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4); 145 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6); 146 output[3] = input[2] & 0x3f; 147 148 if (datalength + 4 > targsize) 149 return (-1); 150 target[datalength++] = Base64[output[0]]; 151 target[datalength++] = Base64[output[1]]; 152 target[datalength++] = Base64[output[2]]; 153 target[datalength++] = Base64[output[3]]; 154 } 155 156 /* Now we worry about padding. */ 157 if (0 != srclength) { 158 /* Get what's left. */ 159 input[0] = input[1] = input[2] = '\0'; 160 for (i = 0; i < srclength; i++) 161 input[i] = *src++; 162 163 output[0] = input[0] >> 2; 164 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4); 165 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6); 166 167 if (datalength + 4 > targsize) 168 return (-1); 169 target[datalength++] = Base64[output[0]]; 170 target[datalength++] = Base64[output[1]]; 171 if (srclength == 1) 172 target[datalength++] = Pad64; 173 else 174 target[datalength++] = Base64[output[2]]; 175 target[datalength++] = Pad64; 176 } 177 if (datalength >= targsize) 178 return (-1); 179 target[datalength] = '\0'; /* Returned value doesn't count \0. */ 180 return (datalength); 181 } 182 183 /* skips all whitespace anywhere. 184 converts characters, four at a time, starting at (or after) 185 src from base - 64 numbers into three 8 bit bytes in the target area. 186 it returns the number of data bytes stored at the target, or -1 on error. 187 */ 188 189 int 190 b64_pton(src, target, targsize) 191 char const *src; 192 u_char *target; 193 size_t targsize; 194 { 195 int tarindex, state, ch; 196 u_char nextbyte; 197 char *pos; 198 199 state = 0; 200 tarindex = 0; 201 202 while ((ch = (unsigned char)*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 >= targsize) 225 return (-1); 226 target[tarindex] |= (pos - Base64) >> 4; 227 nextbyte = ((pos - Base64) & 0x0f) << 4; 228 if (tarindex + 1 < targsize) 229 target[tarindex+1] = nextbyte; 230 else if (nextbyte) 231 return (-1); 232 } 233 tarindex++; 234 state = 2; 235 break; 236 case 2: 237 if (target) { 238 if (tarindex >= targsize) 239 return (-1); 240 target[tarindex] |= (pos - Base64) >> 2; 241 nextbyte = ((pos - Base64) & 0x03) << 6; 242 if (tarindex + 1 < targsize) 243 target[tarindex+1] = nextbyte; 244 else if (nextbyte) 245 return (-1); 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 = (unsigned char)*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 = (unsigned char)*src++) 277 if (!isspace(ch)) 278 break; 279 /* Make sure there is another trailing = sign. */ 280 if (ch != Pad64) 281 return (-1); 282 ch = (unsigned char)*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 = (unsigned char)*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 && tarindex < targsize && 302 target[tarindex] != 0) 303 return (-1); 304 } 305 } else { 306 /* 307 * We ended by seeing the end of the string. Make sure we 308 * have no partial bytes lying around. 309 */ 310 if (state != 0) 311 return (-1); 312 } 313 314 return (tarindex); 315 } 316
