external/bsd/tmux/dist/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
  43 #include <sys/types.h>
  44 #include <sys/param.h>
  45 #include <sys/socket.h>
  46
  47 #include <netinet/in.h>
  48 #include <arpa/inet.h>
  49
  50 #include <ctype.h>
  51 #include <stdio.h>
  52 #include <stdlib.h>
  53 #include <string.h>
  54
  55 #define Assert(Cond) if (!(Cond)) abort()
  56
  57 static const char Base64[] =
  58         "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
  59 static const char Pad64 = '=';
  60
  61 /* (From RFC1521 and draft-ietf-dnssec-secext-03.txt)
  62    The following encoding technique is taken from RFC 1521 by Borenstein
  63    and Freed.  It is reproduced here in a slightly edited form for
  64    convenience.
  65
  66    A 65-character subset of US-ASCII is used, enabling 6 bits to be
  67    represented per printable character. (The extra 65th character, "=",
  68    is used to signify a special processing function.)
  69
  70    The encoding process represents 24-bit groups of input bits as output
  71    strings of 4 encoded characters. Proceeding from left to right, a
  72    24-bit input group is formed by concatenating 3 8-bit input groups.
  73    These 24 bits are then treated as 4 concatenated 6-bit groups, each
  74    of which is translated into a single digit in the base64 alphabet.
  75
  76    Each 6-bit group is used as an index into an array of 64 printable
  77    characters. The character referenced by the index is placed in the
  78    output string.
  79
  80                          Table 1: The Base64 Alphabet
  81
  82       Value Encoding  Value Encoding  Value Encoding  Value Encoding
  83           0 A            17 R            34 i            51 z
  84           1 B            18 S            35 j            52 0
  85           2 C            19 T            36 k            53 1
  86           3 D            20 U            37 l            54 2
  87           4 E            21 V            38 m            55 3
  88           5 F            22 W            39 n            56 4
  89           6 G            23 X            40 o            57 5
  90           7 H            24 Y            41 p            58 6
  91           8 I            25 Z            42 q            59 7
  92           9 J            26 a            43 r            60 8
  93          10 K            27 b            44 s            61 9
  94          11 L            28 c            45 t            62 +
  95          12 M            29 d            46 u            63 /
  96          13 N            30 e            47 v
  97          14 O            31 f            48 w         (pad) =
  98          15 P            32 g            49 x
  99          16 Q            33 h            50 y
 100
 101    Special processing is performed if fewer than 24 bits are available
 102    at the end of the data being encoded.  A full encoding quantum is
 103    always completed at the end of a quantity.  When fewer than 24 input
 104    bits are available in an input group, zero bits are added (on the
 105    right) to form an integral number of 6-bit groups.  Padding at the
 106    end of the data is performed using the '=' character.
 107
 108    Since all base64 input is an integral number of octets, only the
 109          -------------------------------------------------
 110    following cases can arise:
 111
 112        (1) the final quantum of encoding input is an integral
 113            multiple of 24 bits; here, the final unit of encoded
 114            output will be an integral multiple of 4 characters
 115            with no "=" padding,
 116        (2) the final quantum of encoding input is exactly 8 bits;
 117            here, the final unit of encoded output will be two
 118            characters followed by two "=" padding characters, or
 119        (3) the final quantum of encoding input is exactly 16 bits;
 120            here, the final unit of encoded output will be three
 121            characters followed by one "=" padding character.
 122    */
 123
 124 int
 125 b64_ntop(uint8_t const *src, size_t srclength, char *target, size_t targsize) {
 126         size_t datalength = 0;
 127         uint8_t input[3];
 128         uint8_t output[4];
 129         size_t i;
 130
 131         while (2 < srclength) {
 132                 input[0] = *src++;
 133                 input[1] = *src++;
 134                 input[2] = *src++;
 135                 srclength -= 3;
 136
 137                 output[0] = input[0] >> 2;
 138                 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
 139                 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
 140                 output[3] = input[2] & 0x3f;
 141                 Assert(output[0] < 64);
 142                 Assert(output[1] < 64);
 143                 Assert(output[2] < 64);
 144                 Assert(output[3] < 64);
 145
 146                 if (datalength + 4 > targsize)
 147                         return (-1);
 148                 target[datalength++] = Base64[output[0]];
 149                 target[datalength++] = Base64[output[1]];
 150                 target[datalength++] = Base64[output[2]];
 151                 target[datalength++] = Base64[output[3]];
 152         }
 153
 154         /* Now we worry about padding. */
 155         if (0 != srclength) {
 156                 /* Get what's left. */
 157                 input[0] = input[1] = input[2] = '\0';
 158                 for (i = 0; i < srclength; i++)
 159                         input[i] = *src++;
 160
 161                 output[0] = input[0] >> 2;
 162                 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
 163                 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
 164                 Assert(output[0] < 64);
 165                 Assert(output[1] < 64);
 166                 Assert(output[2] < 64);
 167
 168                 if (datalength + 4 > targsize)
 169                         return (-1);
 170                 target[datalength++] = Base64[output[0]];
 171                 target[datalength++] = Base64[output[1]];
 172                 if (srclength == 1)
 173                         target[datalength++] = Pad64;
 174                 else
 175                         target[datalength++] = Base64[output[2]];
 176                 target[datalength++] = Pad64;
 177         }
 178         if (datalength >= targsize)
 179                 return (-1);
 180         target[datalength] = '\0';      /* Returned value doesn't count \0. */
 181         return (datalength);
 182 }