base64.c

   1 /* From Kerberos, krb4-1.0.3 */
   2 /*
   3  * Copyright (c) 1995 - 1999 Kungliga Tekniska Hšgskolan
   4  * (Royal Institute of Technology, Stockholm, Sweden).
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  *
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  *
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  *    notice, this list of conditions and the following disclaimer in the
  16  *    documentation and/or other materials provided with the distribution.
  17  *
  18  * 3. Neither the name of the Institute nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  */
  34
  35 #ifdef HAVE_CONFIG_H
  36 #include <config.h>
  37 RCSID("$Id: base64.c,v 1.4 1999/12/02 16:58:45 joda Exp $");
  38 #endif
  39 #include <stdlib.h>
  40 #include <string.h>
  41 #include "base64.h"
  42
  43 static char base64[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
  44
  45 static int pos(char c)
  46 {
  47   char *p;
  48   for(p = base64; *p; p++)
  49     if(*p == c)
  50       return p - base64;
  51   return -1;
  52 }
  53
  54 int 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[(c&0x00fc0000) >> 18];
  77     p[1]=base64[(c&0x0003f000) >> 12];
  78     p[2]=base64[(c&0x00000fc0) >> 6];
  79     p[3]=base64[(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 int base64_decode(const char *str, void *data)
  92 {
  93   const char *p;
  94   unsigned char *q;
  95   int c;
  96   int x;
  97   int done = 0;
  98   q=(unsigned char*)data;
  99   for(p=str; *p && !done; p+=4){
 100     x = pos(p[0]);
 101     if(x >= 0)
 102       c = x;
 103     else{
 104       done = 3;
 105       break;
 106     }
 107     c*=64;
 108
 109     x = pos(p[1]);
 110     if(x >= 0)
 111       c += x;
 112     else
 113       return -1;
 114     c*=64;
 115
 116     if(p[2] == '=')
 117       done++;
 118     else{
 119       x = pos(p[2]);
 120       if(x >= 0)
 121         c += x;
 122       else
 123         return -1;
 124     }
 125     c*=64;
 126
 127     if(p[3] == '=')
 128       done++;
 129     else{
 130       if(done)
 131         return -1;
 132       x = pos(p[3]);
 133       if(x >= 0)
 134         c += x;
 135       else
 136         return -1;
 137     }
 138     if(done < 3)
 139       *q++=(c&0x00ff0000)>>16;
 140
 141     if(done < 2)
 142       *q++=(c&0x0000ff00)>>8;
 143     if(done < 1)
 144       *q++=(c&0x000000ff)>>0;
 145   }
 146   return q - (unsigned char*)data;
 147 }