mail/fdm/src/compat/b64_ntop.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 //#include <config.h>
  43
  44 #include <sys/types.h>
  45 #include <sys/param.h>
  46 #include <sys/socket.h>
  47
  48 #include <netinet/in.h>
  49 #include <arpa/inet.h>
  50
  51 #include <ctype.h>
  52 #include <stdio.h>
  53 #include <stdlib.h>
  54 #include <string.h>
  55
  56 #include "fdm.h"
  57
  58 #define Assert(Cond) if (!(Cond)) abort()
  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    following cases can arise:
 113
 114        (1) the final quantum of encoding input is an integral
 115            multiple of 24 bits; here, the final unit of encoded
 116            output will be an integral multiple of 4 characters
 117            with no "=" padding,
 118        (2) the final quantum of encoding input is exactly 8 bits;
 119            here, the final unit of encoded output will be two
 120            characters followed by two "=" padding characters, or
 121        (3) the final quantum of encoding input is exactly 16 bits;
 122            here, the final unit of encoded output will be three
 123            characters followed by one "=" padding character.
 124    */
 125
 126 int
 127 local_b64_ntop(uint8_t const *src, size_t srclength, char *target, size_t targsize) {
 128         size_t datalength = 0;
 129         uint8_t input[3];
 130         uint8_t output[4];
 131         size_t i;
 132
 133         while (2 < srclength) {
 134                 input[0] = *src++;
 135                 input[1] = *src++;
 136                 input[2] = *src++;
 137                 srclength -= 3;
 138
 139                 output[0] = input[0] >> 2;
 140                 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
 141                 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
 142                 output[3] = input[2] & 0x3f;
 143                 Assert(output[0] < 64);
 144                 Assert(output[1] < 64);
 145                 Assert(output[2] < 64);
 146                 Assert(output[3] < 64);
 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                 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 }