lib/roken/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 <config.h>
  35
  36 #include <stdlib.h>
  37 #include <string.h>
  38 #include <limits.h>
  39 #include "base64.h"
  40
  41 static const char base64_chars[] =
  42     "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
  43
  44 static int
  45 pos(char c)
  46 {
  47     const char *p;
  48     for (p = base64_chars; *p; p++)
  49         if (*p == c)
  50             return p - base64_chars;
  51     return -1;
  52 }
  53
  54 int ROKEN_LIB_FUNCTION
  55 base64_encode(const void *data, int size, char **str)
  56 {
  57     char *s, *p;
  58     int i;
  59     int c;
  60     const unsigned char *q;
  61
  62     if (size > INT_MAX/4 || size < 0) {
  63         *str = NULL;
  64         return -1;
  65     }
  66
  67     p = s = (char *) malloc(size * 4 / 3 + 4);
  68     if (p == NULL) {
  69         *str = NULL;
  70         return -1;
  71     }
  72     q = (const unsigned char *) data;
  73
  74     for (i = 0; i < size;) {
  75         c = q[i++];
  76         c *= 256;
  77         if (i < size)
  78             c += q[i];
  79         i++;
  80         c *= 256;
  81         if (i < size)
  82             c += q[i];
  83         i++;
  84         p[0] = base64_chars[(c & 0x00fc0000) >> 18];
  85         p[1] = base64_chars[(c & 0x0003f000) >> 12];
  86         p[2] = base64_chars[(c & 0x00000fc0) >> 6];
  87         p[3] = base64_chars[(c & 0x0000003f) >> 0];
  88         if (i > size)
  89             p[3] = '=';
  90         if (i > size + 1)
  91             p[2] = '=';
  92         p += 4;
  93     }
  94     *p = 0;
  95     *str = s;
  96     return strlen(s);
  97 }
  98
  99 #define DECODE_ERROR 0xffffffff
 100
 101 static unsigned int
 102 token_decode(const char *token)
 103 {
 104     int i;
 105     unsigned int val = 0;
 106     int marker = 0;
 107     if (strlen(token) < 4)
 108         return DECODE_ERROR;
 109     for (i = 0; i < 4; i++) {
 110         val *= 64;
 111         if (token[i] == '=')
 112             marker++;
 113         else if (marker > 0)
 114             return DECODE_ERROR;
 115         else
 116             val += pos(token[i]);
 117     }
 118     if (marker > 2)
 119         return DECODE_ERROR;
 120     return (marker << 24) | val;
 121 }
 122
 123 int ROKEN_LIB_FUNCTION
 124 base64_decode(const char *str, void *data)
 125 {
 126     const char *p;
 127     unsigned char *q;
 128
 129     q = data;
 130     for (p = str; *p && (*p == '=' || strchr(base64_chars, *p)); p += 4) {
 131         unsigned int val = token_decode(p);
 132         unsigned int marker = (val >> 24) & 0xff;
 133         if (val == DECODE_ERROR)
 134             return -1;
 135         *q++ = (val >> 16) & 0xff;
 136         if (marker < 2)
 137             *q++ = (val >> 8) & 0xff;
 138         if (marker < 1)
 139             *q++ = val & 0xff;
 140     }
 141     return q - (unsigned char *) data;
 142 }