contrib/ldns/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 <ldns/config.h>
  43
  44 #include <sys/types.h>
  45 #include <sys/param.h>
  46 #ifdef HAVE_SYS_SOCKET_H
  47 #include <sys/socket.h>
  48 #endif
  49
  50 #ifdef HAVE_NETINET_IN_H
  51 #include <netinet/in.h>
  52 #endif
  53 #ifdef HAVE_ARPA_INET_H
  54 #include <arpa/inet.h>
  55 #endif
  56
  57 #include <ctype.h>
  58 #include <stdio.h>
  59 #include <stdlib.h>
  60 #include <string.h>
  61
  62 #define Assert(Cond) if (!(Cond)) abort()
  63
  64 static const char Base64[] =
  65         "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
  66 static const char Pad64 = '=';
  67
  68 /* (From RFC1521 and draft-ietf-dnssec-secext-03.txt)
  69    The following encoding technique is taken from RFC 1521 by Borenstein
  70    and Freed.  It is reproduced here in a slightly edited form for
  71    convenience.
  72
  73    A 65-character subset of US-ASCII is used, enabling 6 bits to be
  74    represented per printable character. (The extra 65th character, "=",
  75    is used to signify a special processing function.)
  76
  77    The encoding process represents 24-bit groups of input bits as output
  78    strings of 4 encoded characters. Proceeding from left to right, a
  79    24-bit input group is formed by concatenating 3 8-bit input groups.
  80    These 24 bits are then treated as 4 concatenated 6-bit groups, each
  81    of which is translated into a single digit in the base64 alphabet.
  82
  83    Each 6-bit group is used as an index into an array of 64 printable
  84    characters. The character referenced by the index is placed in the
  85    output string.
  86
  87                          Table 1: The Base64 Alphabet
  88
  89       Value Encoding  Value Encoding  Value Encoding  Value Encoding
  90           0 A            17 R            34 i            51 z
  91           1 B            18 S            35 j            52 0
  92           2 C            19 T            36 k            53 1
  93           3 D            20 U            37 l            54 2
  94           4 E            21 V            38 m            55 3
  95           5 F            22 W            39 n            56 4
  96           6 G            23 X            40 o            57 5
  97           7 H            24 Y            41 p            58 6
  98           8 I            25 Z            42 q            59 7
  99           9 J            26 a            43 r            60 8
 100          10 K            27 b            44 s            61 9
 101          11 L            28 c            45 t            62 +
 102          12 M            29 d            46 u            63 /
 103          13 N            30 e            47 v
 104          14 O            31 f            48 w         (pad) =
 105          15 P            32 g            49 x
 106          16 Q            33 h            50 y
 107
 108    Special processing is performed if fewer than 24 bits are available
 109    at the end of the data being encoded.  A full encoding quantum is
 110    always completed at the end of a quantity.  When fewer than 24 input
 111    bits are available in an input group, zero bits are added (on the
 112    right) to form an integral number of 6-bit groups.  Padding at the
 113    end of the data is performed using the '=' character.
 114
 115    Since all base64 input is an integral number of octets, only the
 116          -------------------------------------------------
 117    following cases can arise:
 118
 119        (1) the final quantum of encoding input is an integral
 120            multiple of 24 bits; here, the final unit of encoded
 121            output will be an integral multiple of 4 characters
 122            with no "=" padding,
 123        (2) the final quantum of encoding input is exactly 8 bits;
 124            here, the final unit of encoded output will be two
 125            characters followed by two "=" padding characters, or
 126        (3) the final quantum of encoding input is exactly 16 bits;
 127            here, the final unit of encoded output will be three
 128            characters followed by one "=" padding character.
 129    */
 130
 131 int
 132 ldns_b64_ntop(uint8_t const *src, size_t srclength, char *target, size_t targsize) {
 133         size_t datalength = 0;
 134         uint8_t input[3];
 135         uint8_t output[4];
 136         size_t i;
 137
 138         if (srclength == 0) {
 139                 if (targsize > 0) {
 140                         target[0] = '\0';
 141                         return 0;
 142                 } else {
 143                         return -1;
 144                 }
 145         }
 146
 147         while (2 < srclength) {
 148                 input[0] = *src++;
 149                 input[1] = *src++;
 150                 input[2] = *src++;
 151                 srclength -= 3;
 152
 153                 output[0] = input[0] >> 2;
 154                 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
 155                 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
 156                 output[3] = input[2] & 0x3f;
 157                 Assert(output[0] < 64);
 158                 Assert(output[1] < 64);
 159                 Assert(output[2] < 64);
 160                 Assert(output[3] < 64);
 161
 162                 if (datalength + 4 > targsize) {
 163                         return (-1);
 164                 }
 165                 target[datalength++] = Base64[output[0]];
 166                 target[datalength++] = Base64[output[1]];
 167                 target[datalength++] = Base64[output[2]];
 168                 target[datalength++] = Base64[output[3]];
 169         }
 170
 171         /* Now we worry about padding. */
 172         if (0 != srclength) {
 173                 /* Get what's left. */
 174                 input[0] = input[1] = input[2] = (uint8_t) '\0';
 175                 for (i = 0; i < srclength; i++)
 176                         input[i] = *src++;
 177
 178                 output[0] = input[0] >> 2;
 179                 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
 180                 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
 181                 Assert(output[0] < 64);
 182                 Assert(output[1] < 64);
 183                 Assert(output[2] < 64);
 184
 185                 if (datalength + 4 > targsize) {
 186                         return (-2);
 187                 }
 188                 target[datalength++] = Base64[output[0]];
 189                 target[datalength++] = Base64[output[1]];
 190                 if (srclength == 1) {
 191                         target[datalength++] = Pad64;
 192                 } else {
 193                         target[datalength++] = Base64[output[2]];
 194                 }
 195                 target[datalength++] = Pad64;
 196         }
 197         if (datalength >= targsize) {
 198                 return (-3);
 199         }
 200         target[datalength] = '\0';      /* Returned value doesn't count \0. */
 201         return (int) (datalength);
 202 }