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
  34 #include <stdlib.h>
  35 #include <string.h>
  36
  37 #include "dma.h"
  38
  39 static char base64_chars[] =
  40     "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
  41
  42 static int
  43 pos(char c)
  44 {
  45         char *p;
  46         for (p = base64_chars; *p; p++)
  47                 if (*p == c)
  48                         return p - base64_chars;
  49         return -1;
  50 }
  51
  52
  53 int
  54 base64_encode(const void *data, int size, char **str)
  55 {
  56     char *s, *p;
  57     int i;
  58     int c;
  59     const unsigned char *q;
  60
  61     p = s = (char *) malloc(size * 4 / 3 + 4);
  62     if (p == NULL)
  63         return -1;
  64     q = (const unsigned char *) data;
  65     i = 0;
  66     for (i = 0; i < size;) {
  67         c = q[i++];
  68         c *= 256;
  69         if (i < size)
  70             c += q[i];
  71         i++;
  72         c *= 256;
  73         if (i < size)
  74             c += q[i];
  75         i++;
  76         p[0] = base64_chars[(c & 0x00fc0000) >> 18];
  77         p[1] = base64_chars[(c & 0x0003f000) >> 12];
  78         p[2] = base64_chars[(c & 0x00000fc0) >> 6];
  79         p[3] = base64_chars[(c & 0x0000003f) >> 0];
  80         if (i > size)
  81             p[3] = '=';
  82         if (i > size + 1)
  83             p[2] = '=';
  84         p += 4;
  85     }
  86     *p = 0;
  87     *str = s;
  88     return strlen(s);
  89 }
  90
  91 #define DECODE_ERROR 0xffffffff
  92
  93 static unsigned int
  94 token_decode(const char *token)
  95 {
  96         int i;
  97         unsigned int val = 0;
  98         int marker = 0;
  99         if (strlen(token) < 4)
 100                 return DECODE_ERROR;
 101         for (i = 0; i < 4; i++) {
 102                 val *= 64;
 103                 if (token[i] == '=')
 104                         marker++;
 105                 else if (marker > 0)
 106                         return DECODE_ERROR;
 107                 else
 108                         val += pos(token[i]);
 109         }
 110         if (marker > 2)
 111                 return DECODE_ERROR;
 112         return (marker << 24) | val;
 113 }
 114
 115 int
 116 base64_decode(const char *str, void *data)
 117 {
 118         const char *p;
 119         unsigned char *q;
 120
 121         q = data;
 122         for (p = str; *p && (*p == '=' || strchr(base64_chars, *p)); p += 4) {
 123                 unsigned int val = token_decode(p);
 124                 unsigned int marker = (val >> 24) & 0xff;
 125                 if (val == DECODE_ERROR)
 126                         return -1;
 127                 *q++ = (val >> 16) & 0xff;
 128                 if (marker < 2)
 129                         *q++ = (val >> 8) & 0xff;
 130                 if (marker < 1)
 131                         *q++ = val & 0xff;
 132         }
 133         return q - (unsigned char *) data;
 134 }
 135