compat/base64.c

   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 }