usr/src/lib/libc/port/gen/base64.c

   1 /*
   2  * Copyright (c) 1996, 1998 by Internet Software Consortium.
   3  *
   4  * Permission to use, copy, modify, and distribute this software for any
   5  * purpose with or without fee is hereby granted, provided that the above
   6  * copyright notice and this permission notice appear in all copies.
   7  *
   8  * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
   9  * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
  10  * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
  11  * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
  12  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
  13  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
  14  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
  15  * SOFTWARE.
  16  */
  17
  18 /*
  19  * Portions Copyright (c) 1995 by International Business Machines, Inc.
  20  *
  21  * International Business Machines, Inc. (hereinafter called IBM) grants
  22  * permission under its copyrights to use, copy, modify, and distribute this
  23  * Software with or without fee, provided that the above copyright notice and
  24  * all paragraphs of this notice appear in all copies, and that the name of IBM
  25  * not be used in connection with the marketing of any product incorporating
  26  * the Software or modifications thereof, without specific, written prior
  27  * permission.
  28  *
  29  * To the extent it has a right to do so, IBM grants an immunity from suit
  30  * under its patents, if any, for the use, sale or manufacture of products to
  31  * the extent that such products are used for performing Domain Name System
  32  * dynamic updates in TCP/IP networks by means of the Software.  No immunity is
  33  * granted for any product per se or for any other function of any product.
  34  *
  35  * THE SOFTWARE IS PROVIDED "AS IS", AND IBM DISCLAIMS ALL WARRANTIES,
  36  * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
  37  * PARTICULAR PURPOSE.  IN NO EVENT SHALL IBM BE LIABLE FOR ANY SPECIAL,
  38  * DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER ARISING
  39  * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE, EVEN
  40  * IF IBM IS APPRISED OF THE POSSIBILITY OF SUCH DAMAGES.
  41  */
  42
  43 #include <sys/param.h>
  44 #include <sys/socket.h>
  45
  46 #include <netinet/in.h>
  47 #include <arpa/inet.h>
  48 #include <arpa/nameser.h>
  49
  50 #include <ctype.h>
  51 #include <resolv.h>
  52 #include <stdio.h>
  53 #include <stdlib.h>
  54 #include <string.h>
  55
  56 #define Assert(Cond) if (!(Cond)) abort()
  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(u_char const *src, size_t srclength, char *target, size_t targsize) {
 127         size_t datalength = 0;
 128         u_char input[3];
 129         u_char output[4];
 130         size_t i;
 131
 132         while (2 < srclength) {
 133                 input[0] = *src++;
 134                 input[1] = *src++;
 135                 input[2] = *src++;
 136                 srclength -= 3;
 137
 138                 output[0] = input[0] >> 2;
 139                 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
 140                 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
 141                 output[3] = input[2] & 0x3f;
 142                 Assert(output[0] < 64);
 143                 Assert(output[1] < 64);
 144                 Assert(output[2] < 64);
 145                 Assert(output[3] < 64);
 146
 147                 if (datalength + 4 > targsize)
 148                         return (-1);
 149                 target[datalength++] = Base64[output[0]];
 150                 target[datalength++] = Base64[output[1]];
 151                 target[datalength++] = Base64[output[2]];
 152                 target[datalength++] = Base64[output[3]];
 153         }
 154
 155         /* Now we worry about padding. */
 156         if (0 != srclength) {
 157                 /* Get what's left. */
 158                 input[0] = input[1] = input[2] = '\0';
 159                 for (i = 0; i < srclength; i++)
 160                         input[i] = *src++;
 161
 162                 output[0] = input[0] >> 2;
 163                 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
 164                 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
 165                 Assert(output[0] < 64);
 166                 Assert(output[1] < 64);
 167                 Assert(output[2] < 64);
 168
 169                 if (datalength + 4 > targsize)
 170                         return (-1);
 171                 target[datalength++] = Base64[output[0]];
 172                 target[datalength++] = Base64[output[1]];
 173                 if (srclength == 1)
 174                         target[datalength++] = Pad64;
 175                 else
 176                         target[datalength++] = Base64[output[2]];
 177                 target[datalength++] = Pad64;
 178         }
 179         if (datalength >= targsize)
 180                 return (-1);
 181         target[datalength] = '\0';      /* Returned value doesn't count \0. */
 182         return (datalength);
 183 }
 184
 185 /* skips all whitespace anywhere.
 186    converts characters, four at a time, starting at (or after)
 187    src from base - 64 numbers into three 8 bit bytes in the target area.
 188    it returns the number of data bytes stored at the target, or -1 on error.
 189  */
 190
 191 int
 192 b64_pton(const char *src, u_char *target, size_t targsize)
 193 {
 194         int tarindex, state, ch;
 195         u_char nextbyte;
 196         char *pos;
 197
 198         state = 0;
 199         tarindex = 0;
 200
 201         while ((ch = *src++) != '\0') {
 202                 if (isspace((unsigned char)ch))        /* Skip whitespace anywhere. */
 203                         continue;
 204
 205                 if (ch == Pad64)
 206                         break;
 207
 208                 pos = strchr(Base64, ch);
 209                 if (pos == NULL)                /* A non-base64 character. */
 210                         return (-1);
 211
 212                 switch (state) {
 213                 case 0:
 214                         if (target) {
 215                                 if ((size_t)tarindex >= targsize)
 216                                         return (-1);
 217                                 target[tarindex] = (pos - Base64) << 2;
 218                         }
 219                         state = 1;
 220                         break;
 221                 case 1:
 222                         if (target) {
 223                                 if ((size_t)tarindex >= targsize)
 224                                         return (-1);
 225                                 target[tarindex]   |=  (pos - Base64) >> 4;
 226                                 nextbyte = ((pos - Base64) & 0x0f) << 4;
 227                                 if ((size_t)tarindex + 1 < targsize)
 228                                         target[tarindex + 1] = nextbyte;
 229                                 else if (nextbyte)
 230                                         return (-1);
 231                         }
 232                         tarindex++;
 233                         state = 2;
 234                         break;
 235                 case 2:
 236                         if (target) {
 237                                 if ((size_t)tarindex >= targsize)
 238                                         return (-1);
 239                                 target[tarindex]   |=  (pos - Base64) >> 2;
 240                                 nextbyte = ((pos - Base64) & 0x03) << 6;
 241                                 if ((size_t)tarindex + 1 < targsize)
 242                                         target[tarindex + 1] = nextbyte;
 243                                 else if (nextbyte)
 244                                         return (-1);
 245                         }
 246                         tarindex++;
 247                         state = 3;
 248                         break;
 249                 case 3:
 250                         if (target) {
 251                                 if ((size_t)tarindex >= targsize)
 252                                         return (-1);
 253                                 target[tarindex] |= (pos - Base64);
 254                         }
 255                         tarindex++;
 256                         state = 0;
 257                         break;
 258                 default:
 259                         abort();
 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 ((void)NULL; ch != '\0'; ch = *src++)
 278                                 if (!isspace((unsigned char)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 ((void)NULL; ch != '\0'; ch = *src++)
 293                                 if (!isspace((unsigned char)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 && (size_t)tarindex < targsize &&
 303                             target[tarindex] != 0)
 304                                 return (-1);
 305                 }
 306         } else {
 307                 /*
 308                  * We ended by seeing the end of the string.  Make sure we
 309                  * have no partial bytes lying around.
 310                  */
 311                 if (state != 0)
 312                         return (-1);
 313         }
 314
 315         return (tarindex);
 316 }