base64.c revision 106121
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) 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 66static const char Base64[] = 67 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; 68static 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 133int 134b64_ntop(u_char const *src, size_t srclength, char *target, 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 200int 201b64_pton(char const *src, u_char *target, size_t targsize) 202{ 203 int tarindex, state, ch; 204 char *pos; 205 206 state = 0; 207 tarindex = 0; 208 209 while ((ch = *src++) != '\0') { 210 if (isspace(ch)) /* Skip whitespace anywhere. */ 211 continue; 212 213 if (ch == Pad64) 214 break; 215 216 pos = strchr(Base64, ch); 217 if (pos == 0) /* A non-base64 character. */ 218 return (-1); 219 220 switch (state) { 221 case 0: 222 if (target) { 223 if (tarindex >= targsize) 224 return (-1); 225 target[tarindex] = (pos - Base64) << 2; 226 } 227 state = 1; 228 break; 229 case 1: 230 if (target) { 231 if (tarindex + 1 >= targsize) 232 return (-1); 233 target[tarindex] |= (pos - Base64) >> 4; 234 target[tarindex+1] = ((pos - Base64) & 0x0f) 235 << 4 ; 236 } 237 tarindex++; 238 state = 2; 239 break; 240 case 2: 241 if (target) { 242 if (tarindex + 1 >= targsize) 243 return (-1); 244 target[tarindex] |= (pos - Base64) >> 2; 245 target[tarindex+1] = ((pos - Base64) & 0x03) 246 << 6; 247 } 248 tarindex++; 249 state = 3; 250 break; 251 case 3: 252 if (target) { 253 if (tarindex >= targsize) 254 return (-1); 255 target[tarindex] |= (pos - Base64); 256 } 257 tarindex++; 258 state = 0; 259 break; 260 } 261 } 262 263 /* 264 * We are done decoding Base-64 chars. Let's see if we ended 265 * on a byte boundary, and/or with erroneous trailing characters. 266 */ 267 268 if (ch == Pad64) { /* We got a pad char. */ 269 ch = *src++; /* Skip it, get next. */ 270 switch (state) { 271 case 0: /* Invalid = in first position */ 272 case 1: /* Invalid = in second position */ 273 return (-1); 274 275 case 2: /* Valid, means one byte of info */ 276 /* Skip any number of spaces. */ 277 for (; ch != '\0'; ch = *src++) 278 if (!isspace(ch)) 279 break; 280 /* Make sure there is another trailing = sign. */ 281 if (ch != Pad64) 282 return (-1); 283 ch = *src++; /* Skip the = */ 284 /* Fall through to "single trailing =" case. */ 285 /* FALLTHROUGH */ 286 287 case 3: /* Valid, means two bytes of info */ 288 /* 289 * We know this char is an =. Is there anything but 290 * whitespace after it? 291 */ 292 for (; ch != '\0'; ch = *src++) 293 if (!isspace(ch)) 294 return (-1); 295 296 /* 297 * Now make sure for cases 2 and 3 that the "extra" 298 * bits that slopped past the last full byte were 299 * zeros. If we don't check them, they become a 300 * subliminal channel. 301 */ 302 if (target && 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} 316 317#endif /* !defined(HAVE_B64_NTOP) && !defined(HAVE___B64_NTOP) */ 318