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 "got_compat.h"
  46
  47 #include <sys/types.h>
  48 #include <sys/socket.h>
  49 #include <netinet/in.h>
  50 #include <arpa/inet.h>
  51 #include <arpa/nameser.h>
  52
  53 #include <ctype.h>
  54 #include <resolv.h>
  55 #include <stdio.h>
  56
  57 #include <stdlib.h>
  58 #include <string.h>
  59
  60 static const char Base64[] =
  61         "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
  62 static const char Pad64 = '=';
  63
  64 /* (From RFC1521 and draft-ietf-dnssec-secext-03.txt)
  65    The following encoding technique is taken from RFC 1521 by Borenstein
  66    and Freed.  It is reproduced here in a slightly edited form for
  67    convenience.
  68
  69    A 65-character subset of US-ASCII is used, enabling 6 bits to be
  70    represented per printable character. (The extra 65th character, "=",
  71    is used to signify a special processing function.)
  72
  73    The encoding process represents 24-bit groups of input bits as output
  74    strings of 4 encoded characters. Proceeding from left to right, a
  75    24-bit input group is formed by concatenating 3 8-bit input groups.
  76    These 24 bits are then treated as 4 concatenated 6-bit groups, each
  77    of which is translated into a single digit in the base64 alphabet.
  78
  79    Each 6-bit group is used as an index into an array of 64 printable
  80    characters. The character referenced by the index is placed in the
  81    output string.
  82
  83                          Table 1: The Base64 Alphabet
  84
  85       Value Encoding  Value Encoding  Value Encoding  Value Encoding
  86           0 A            17 R            34 i            51 z
  87           1 B            18 S            35 j            52 0
  88           2 C            19 T            36 k            53 1
  89           3 D            20 U            37 l            54 2
  90           4 E            21 V            38 m            55 3
  91           5 F            22 W            39 n            56 4
  92           6 G            23 X            40 o            57 5
  93           7 H            24 Y            41 p            58 6
  94           8 I            25 Z            42 q            59 7
  95           9 J            26 a            43 r            60 8
  96          10 K            27 b            44 s            61 9
  97          11 L            28 c            45 t            62 +
  98          12 M            29 d            46 u            63 /
  99          13 N            30 e            47 v
 100          14 O            31 f            48 w         (pad) =
 101          15 P            32 g            49 x
 102          16 Q            33 h            50 y
 103
 104    Special processing is performed if fewer than 24 bits are available
 105    at the end of the data being encoded.  A full encoding quantum is
 106    always completed at the end of a quantity.  When fewer than 24 input
 107    bits are available in an input group, zero bits are added (on the
 108    right) to form an integral number of 6-bit groups.  Padding at the
 109    end of the data is performed using the '=' character.
 110
 111    Since all base64 input is an integral number of octets, only the
 112          -------------------------------------------------
 113    following cases can arise:
 114
 115        (1) the final quantum of encoding input is an integral
 116            multiple of 24 bits; here, the final unit of encoded
 117            output will be an integral multiple of 4 characters
 118            with no "=" padding,
 119        (2) the final quantum of encoding input is exactly 8 bits;
 120            here, the final unit of encoded output will be two
 121            characters followed by two "=" padding characters, or
 122        (3) the final quantum of encoding input is exactly 16 bits;
 123            here, the final unit of encoded output will be three
 124            characters followed by one "=" padding character.
 125    */
 126
 127 int
 128 b64_ntop(src, srclength, target, targsize)
 129         u_char const *src;
 130         size_t srclength;
 131         char *target;
 132         size_t targsize;
 133 {
 134         size_t datalength = 0;
 135         u_char input[3];
 136         u_char output[4];
 137         int i;
 138
 139         while (2 < srclength) {
 140                 input[0] = *src++;
 141                 input[1] = *src++;
 142                 input[2] = *src++;
 143                 srclength -= 3;
 144
 145                 output[0] = input[0] >> 2;
 146                 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
 147                 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
 148                 output[3] = input[2] & 0x3f;
 149
 150                 if (datalength + 4 > targsize)
 151                         return (-1);
 152                 target[datalength++] = Base64[output[0]];
 153                 target[datalength++] = Base64[output[1]];
 154                 target[datalength++] = Base64[output[2]];
 155                 target[datalength++] = Base64[output[3]];
 156         }
 157
 158         /* Now we worry about padding. */
 159         if (0 != srclength) {
 160                 /* Get what's left. */
 161                 input[0] = input[1] = input[2] = '\0';
 162                 for (i = 0; i < srclength; i++)
 163                         input[i] = *src++;
 164
 165                 output[0] = input[0] >> 2;
 166                 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
 167                 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
 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(src, target, targsize)
 193         char const *src;
 194         u_char *target;
 195         size_t targsize;
 196 {
 197         int tarindex, state, ch;
 198         u_char nextbyte;
 199         char *pos;
 200
 201         state = 0;
 202         tarindex = 0;
 203
 204         while ((ch = (unsigned char)*src++) != '\0') {
 205                 if (isspace(ch))        /* Skip whitespace anywhere. */
 206                         continue;
 207
 208                 if (ch == Pad64)
 209                         break;
 210
 211                 pos = strchr(Base64, ch);
 212                 if (pos == 0)           /* A non-base64 character. */
 213                         return (-1);
 214
 215                 switch (state) {
 216                 case 0:
 217                         if (target) {
 218                                 if (tarindex >= targsize)
 219                                         return (-1);
 220                                 target[tarindex] = (pos - Base64) << 2;
 221                         }
 222                         state = 1;
 223                         break;
 224                 case 1:
 225                         if (target) {
 226                                 if (tarindex >= targsize)
 227                                         return (-1);
 228                                 target[tarindex]   |=  (pos - Base64) >> 4;
 229                                 nextbyte = ((pos - Base64) & 0x0f) << 4;
 230                                 if (tarindex + 1 < targsize)
 231                                         target[tarindex+1] = nextbyte;
 232                                 else if (nextbyte)
 233                                         return (-1);
 234                         }
 235                         tarindex++;
 236                         state = 2;
 237                         break;
 238                 case 2:
 239                         if (target) {
 240                                 if (tarindex >= targsize)
 241                                         return (-1);
 242                                 target[tarindex]   |=  (pos - Base64) >> 2;
 243                                 nextbyte = ((pos - Base64) & 0x03) << 6;
 244                                 if (tarindex + 1 < targsize)
 245                                         target[tarindex+1] = nextbyte;
 246                                 else if (nextbyte)
 247                                         return (-1);
 248                         }
 249                         tarindex++;
 250                         state = 3;
 251                         break;
 252                 case 3:
 253                         if (target) {
 254                                 if (tarindex >= targsize)
 255                                         return (-1);
 256                                 target[tarindex] |= (pos - Base64);
 257                         }
 258                         tarindex++;
 259                         state = 0;
 260                         break;
 261                 }
 262         }
 263
 264         /*
 265          * We are done decoding Base-64 chars.  Let's see if we ended
 266          * on a byte boundary, and/or with erroneous trailing characters.
 267          */
 268
 269         if (ch == Pad64) {                      /* We got a pad char. */
 270                 ch = (unsigned char)*src++;     /* Skip it, get next. */
 271                 switch (state) {
 272                 case 0:         /* Invalid = in first position */
 273                 case 1:         /* Invalid = in second position */
 274                         return (-1);
 275
 276                 case 2:         /* Valid, means one byte of info */
 277                         /* Skip any number of spaces. */
 278                         for (; ch != '\0'; ch = (unsigned char)*src++)
 279                                 if (!isspace(ch))
 280                                         break;
 281                         /* Make sure there is another trailing = sign. */
 282                         if (ch != Pad64)
 283                                 return (-1);
 284                         ch = (unsigned char)*src++;             /* Skip the = */
 285                         /* Fall through to "single trailing =" case. */
 286                         /* FALLTHROUGH */
 287
 288                 case 3:         /* Valid, means two bytes of info */
 289                         /*
 290                          * We know this char is an =.  Is there anything but
 291                          * whitespace after it?
 292                          */
 293                         for (; ch != '\0'; ch = (unsigned char)*src++)
 294                                 if (!isspace(ch))
 295                                         return (-1);
 296
 297                         /*
 298                          * Now make sure for cases 2 and 3 that the "extra"
 299                          * bits that slopped past the last full byte were
 300                          * zeros.  If we don't check them, they become a
 301                          * subliminal channel.
 302                          */
 303                         if (target && tarindex < targsize &&
 304                             target[tarindex] != 0)
 305                                 return (-1);
 306                 }
 307         } else {
 308                 /*
 309                  * We ended by seeing the end of the string.  Make sure we
 310                  * have no partial bytes lying around.
 311                  */
 312                 if (state != 0)
 313                         return (-1);
 314         }
 315
 316         return (tarindex);
 317 }