external/bsd/libbind/dist/isc/base64.c

   1 /*      $NetBSD$        */
   2
   3 /*
   4  * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
   5  * Copyright (c) 1996-1999 by Internet Software Consortium.
   6  *
   7  * Permission to use, copy, modify, and distribute this software for any
   8  * purpose with or without fee is hereby granted, provided that the above
   9  * copyright notice and this permission notice appear in all copies.
  10  *
  11  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
  12  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  13  * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
  14  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  15  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  16  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
  17  * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS 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 #if !defined(LINT) && !defined(CODECENTER)
  46 static const char rcsid[] = "Id: base64.c,v 1.4 2005/04/27 04:56:34 sra Exp";
  47 #endif /* not lint */
  48
  49 #include "port_before.h"
  50
  51 #include <sys/types.h>
  52 #include <sys/param.h>
  53 #include <sys/socket.h>
  54
  55 #include <netinet/in.h>
  56 #include <arpa/inet.h>
  57 #include <arpa/nameser.h>
  58
  59 #include <ctype.h>
  60 #include <resolv.h>
  61 #include <stdio.h>
  62 #include <stdlib.h>
  63 #include <string.h>
  64
  65 #include "port_after.h"
  66
  67 #define Assert(Cond) if (!(Cond)) abort()
  68
  69 static const char Base64[] =
  70         "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
  71 static const char Pad64 = '=';
  72
  73 /* (From RFC1521 and draft-ietf-dnssec-secext-03.txt)
  74    The following encoding technique is taken from RFC1521 by Borenstein
  75    and Freed.  It is reproduced here in a slightly edited form for
  76    convenience.
  77
  78    A 65-character subset of US-ASCII is used, enabling 6 bits to be
  79    represented per printable character. (The extra 65th character, "=",
  80    is used to signify a special processing function.)
  81
  82    The encoding process represents 24-bit groups of input bits as output
  83    strings of 4 encoded characters. Proceeding from left to right, a
  84    24-bit input group is formed by concatenating 3 8-bit input groups.
  85    These 24 bits are then treated as 4 concatenated 6-bit groups, each
  86    of which is translated into a single digit in the base64 alphabet.
  87
  88    Each 6-bit group is used as an index into an array of 64 printable
  89    characters. The character referenced by the index is placed in the
  90    output string.
  91
  92                          Table 1: The Base64 Alphabet
  93
  94       Value Encoding  Value Encoding  Value Encoding  Value Encoding
  95           0 A            17 R            34 i            51 z
  96           1 B            18 S            35 j            52 0
  97           2 C            19 T            36 k            53 1
  98           3 D            20 U            37 l            54 2
  99           4 E            21 V            38 m            55 3
 100           5 F            22 W            39 n            56 4
 101           6 G            23 X            40 o            57 5
 102           7 H            24 Y            41 p            58 6
 103           8 I            25 Z            42 q            59 7
 104           9 J            26 a            43 r            60 8
 105          10 K            27 b            44 s            61 9
 106          11 L            28 c            45 t            62 +
 107          12 M            29 d            46 u            63 /
 108          13 N            30 e            47 v
 109          14 O            31 f            48 w         (pad) =
 110          15 P            32 g            49 x
 111          16 Q            33 h            50 y
 112
 113    Special processing is performed if fewer than 24 bits are available
 114    at the end of the data being encoded.  A full encoding quantum is
 115    always completed at the end of a quantity.  When fewer than 24 input
 116    bits are available in an input group, zero bits are added (on the
 117    right) to form an integral number of 6-bit groups.  Padding at the
 118    end of the data is performed using the '=' character.
 119
 120    Since all base64 input is an integral number of octets, only the
 121          -------------------------------------------------
 122    following cases can arise:
 123
 124        (1) the final quantum of encoding input is an integral
 125            multiple of 24 bits; here, the final unit of encoded
 126            output will be an integral multiple of 4 characters
 127            with no "=" padding,
 128        (2) the final quantum of encoding input is exactly 8 bits;
 129            here, the final unit of encoded output will be two
 130            characters followed by two "=" padding characters, or
 131        (3) the final quantum of encoding input is exactly 16 bits;
 132            here, the final unit of encoded output will be three
 133            characters followed by one "=" padding character.
 134    */
 135
 136 int
 137 b64_ntop(u_char const *src, size_t srclength, char *target, size_t targsize) {
 138         size_t datalength = 0;
 139         u_char input[3];
 140         u_char output[4];
 141         size_t i;
 142
 143         while (2U < srclength) {
 144                 input[0] = *src++;
 145                 input[1] = *src++;
 146                 input[2] = *src++;
 147                 srclength -= 3;
 148
 149                 output[0] = input[0] >> 2;
 150                 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
 151                 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
 152                 output[3] = input[2] & 0x3f;
 153                 Assert(output[0] < 64);
 154                 Assert(output[1] < 64);
 155                 Assert(output[2] < 64);
 156                 Assert(output[3] < 64);
 157
 158                 if (datalength + 4 > targsize)
 159                         return (-1);
 160                 target[datalength++] = Base64[output[0]];
 161                 target[datalength++] = Base64[output[1]];
 162                 target[datalength++] = Base64[output[2]];
 163                 target[datalength++] = Base64[output[3]];
 164         }
 165
 166         /* Now we worry about padding. */
 167         if (0U != srclength) {
 168                 /* Get what's left. */
 169                 input[0] = input[1] = input[2] = '\0';
 170                 for (i = 0; i < srclength; i++)
 171                         input[i] = *src++;
 172
 173                 output[0] = input[0] >> 2;
 174                 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
 175                 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
 176                 Assert(output[0] < 64);
 177                 Assert(output[1] < 64);
 178                 Assert(output[2] < 64);
 179
 180                 if (datalength + 4 > targsize)
 181                         return (-1);
 182                 target[datalength++] = Base64[output[0]];
 183                 target[datalength++] = Base64[output[1]];
 184                 if (srclength == 1U)
 185                         target[datalength++] = Pad64;
 186                 else
 187                         target[datalength++] = Base64[output[2]];
 188                 target[datalength++] = Pad64;
 189         }
 190         if (datalength >= targsize)
 191                 return (-1);
 192         target[datalength] = '\0';      /*%< Returned value doesn't count \\0. */
 193         return (datalength);
 194 }
 195
 196 /* skips all whitespace anywhere.
 197    converts characters, four at a time, starting at (or after)
 198    src from base - 64 numbers into three 8 bit bytes in the target area.
 199    it returns the number of data bytes stored at the target, or -1 on error.
 200  */
 201
 202 int
 203 b64_pton(src, target, targsize)
 204         char const *src;
 205         u_char *target;
 206         size_t targsize;
 207 {
 208         int tarindex, state, ch;
 209         char *pos;
 210
 211         state = 0;
 212         tarindex = 0;
 213
 214         while ((ch = *src++) != '\0') {
 215                 if (isspace(ch))        /*%< Skip whitespace anywhere. */
 216                         continue;
 217
 218                 if (ch == Pad64)
 219                         break;
 220
 221                 pos = strchr(Base64, ch);
 222                 if (pos == 0)           /*%< A non-base64 character. */
 223                         return (-1);
 224
 225                 switch (state) {
 226                 case 0:
 227                         if (target) {
 228                                 if ((size_t)tarindex >= targsize)
 229                                         return (-1);
 230                                 target[tarindex] = (pos - Base64) << 2;
 231                         }
 232                         state = 1;
 233                         break;
 234                 case 1:
 235                         if (target) {
 236                                 if ((size_t)tarindex + 1 >= targsize)
 237                                         return (-1);
 238                                 target[tarindex]   |=  (pos - Base64) >> 4;
 239                                 target[tarindex+1]  = ((pos - Base64) & 0x0f)
 240                                                         << 4 ;
 241                         }
 242                         tarindex++;
 243                         state = 2;
 244                         break;
 245                 case 2:
 246                         if (target) {
 247                                 if ((size_t)tarindex + 1 >= targsize)
 248                                         return (-1);
 249                                 target[tarindex]   |=  (pos - Base64) >> 2;
 250                                 target[tarindex+1]  = ((pos - Base64) & 0x03)
 251                                                         << 6;
 252                         }
 253                         tarindex++;
 254                         state = 3;
 255                         break;
 256                 case 3:
 257                         if (target) {
 258                                 if ((size_t)tarindex >= targsize)
 259                                         return (-1);
 260                                 target[tarindex] |= (pos - Base64);
 261                         }
 262                         tarindex++;
 263                         state = 0;
 264                         break;
 265                 default:
 266                         abort();
 267                 }
 268         }
 269
 270         /*
 271          * We are done decoding Base-64 chars.  Let's see if we ended
 272          * on a byte boundary, and/or with erroneous trailing characters.
 273          */
 274
 275         if (ch == Pad64) {              /*%< We got a pad char. */
 276                 ch = *src++;            /*%< Skip it, get next. */
 277                 switch (state) {
 278                 case 0:         /*%< Invalid = in first position */
 279                 case 1:         /*%< Invalid = in second position */
 280                         return (-1);
 281
 282                 case 2:         /*%< Valid, means one byte of info */
 283                         /* Skip any number of spaces. */
 284                         for ((void)NULL; ch != '\0'; ch = *src++)
 285                                 if (!isspace(ch))
 286                                         break;
 287                         /* Make sure there is another trailing = sign. */
 288                         if (ch != Pad64)
 289                                 return (-1);
 290                         ch = *src++;            /*%< Skip the = */
 291                         /* Fall through to "single trailing =" case. */
 292                         /* FALLTHROUGH */
 293
 294                 case 3:         /*%< Valid, means two bytes of info */
 295                         /*
 296                          * We know this char is an =.  Is there anything but
 297                          * whitespace after it?
 298                          */
 299                         for ((void)NULL; ch != '\0'; ch = *src++)
 300                                 if (!isspace(ch))
 301                                         return (-1);
 302
 303                         /*
 304                          * Now make sure for cases 2 and 3 that the "extra"
 305                          * bits that slopped past the last full byte were
 306                          * zeros.  If we don't check them, they become a
 307                          * subliminal channel.
 308                          */
 309                         if (target && target[tarindex] != 0)
 310                                 return (-1);
 311                 }
 312         } else {
 313                 /*
 314                  * We ended by seeing the end of the string.  Make sure we
 315                  * have no partial bytes lying around.
 316                  */
 317                 if (state != 0)
 318                         return (-1);
 319         }
 320
 321         return (tarindex);
 322 }
 323
 324 /*! \file */