base64.c

   1 /*
   2  * Copyright (c) 1995-2001 Kungliga Tekniska Högskolan
   3  * (Royal Institute of Technology, Stockholm, Sweden).
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  *
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  *
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  *
  17  * 3. Neither the name of the Institute nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  *
  33  * $DragonFly: src/libexec/dma/base64.c,v 1.2 2008/09/02 15:11:49 matthias Exp $
  34  */
  35
  36 #include <stdlib.h>
  37 #include <string.h>
  38
  39 int base64_encode(const void *data, int size, char **str);
  40
  41 static char base64_chars[] =
  42     "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
  43
  44 static int
  45 pos(char c)
  46 {
  47         char *p;
  48         for (p = base64_chars; *p; p++)
  49                 if (*p == c)
  50                         return p - base64_chars;
  51         return -1;
  52 }
  53
  54
  55 int
  56 base64_encode(const void *data, int size, char **str)
  57 {
  58     char *s, *p;
  59     int i;
  60     int c;
  61     const unsigned char *q;
  62
  63     p = s = (char *) malloc(size * 4 / 3 + 4);
  64     if (p == NULL)
  65         return -1;
  66     q = (const unsigned char *) data;
  67     i = 0;
  68     for (i = 0; i < size;) {
  69         c = q[i++];
  70         c *= 256;
  71         if (i < size)
  72             c += q[i];
  73         i++;
  74         c *= 256;
  75         if (i < size)
  76             c += q[i];
  77         i++;
  78         p[0] = base64_chars[(c & 0x00fc0000) >> 18];
  79         p[1] = base64_chars[(c & 0x0003f000) >> 12];
  80         p[2] = base64_chars[(c & 0x00000fc0) >> 6];
  81         p[3] = base64_chars[(c & 0x0000003f) >> 0];
  82         if (i > size)
  83             p[3] = '=';
  84         if (i > size + 1)
  85             p[2] = '=';
  86         p += 4;
  87     }
  88     *p = 0;
  89     *str = s;
  90     return strlen(s);
  91 }
  92
  93 #define DECODE_ERROR 0xffffffff
  94
  95 static unsigned int
  96 token_decode(const char *token)
  97 {
  98         int i;
  99         unsigned int val = 0;
 100         int marker = 0;
 101         if (strlen(token) < 4)
 102                 return DECODE_ERROR;
 103         for (i = 0; i < 4; i++) {
 104                 val *= 64;
 105                 if (token[i] == '=')
 106                         marker++;
 107                 else if (marker > 0)
 108                         return DECODE_ERROR;
 109                 else
 110                         val += pos(token[i]);
 111         }
 112         if (marker > 2)
 113                 return DECODE_ERROR;
 114         return (marker << 24) | val;
 115 }
 116
 117 int
 118 base64_decode(const char *str, void *data)
 119 {
 120         const char *p;
 121         unsigned char *q;
 122
 123         q = data;
 124         for (p = str; *p && (*p == '=' || strchr(base64_chars, *p)); p += 4) {
 125                 unsigned int val = token_decode(p);
 126                 unsigned int marker = (val >> 24) & 0xff;
 127                 if (val == DECODE_ERROR)
 128                         return -1;
 129                 *q++ = (val >> 16) & 0xff;
 130                 if (marker < 2)
 131                         *q++ = (val >> 8) & 0xff;
 132                 if (marker < 1)
 133                         *q++ = val & 0xff;
 134         }
 135         return q - (unsigned char *) data;
 136 }
 137