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 <stdio.h>
  42 #include "base64.h"
  43
  44 static char base64[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
  45
  46 static int pos(char c)
  47 {
  48   char *p;
  49   for(p = base64; *p; p++)
  50     if(*p == c)
  51       return p - base64;
  52   return -1;
  53 }
  54
  55 int 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   p = s = (char*)malloc(size*4/3+4);
  63   if (p == NULL)
  64       return -1;
  65   q = (const unsigned char*)data;
  66   i=0;
  67   for(i = 0; i < size;){
  68     c=q[i++];
  69     c*=256;
  70     if(i < size)
  71       c+=q[i];
  72     i++;
  73     c*=256;
  74     if(i < size)
  75       c+=q[i];
  76     i++;
  77     p[0]=base64[(c&0x00fc0000) >> 18];
  78     p[1]=base64[(c&0x0003f000) >> 12];
  79     p[2]=base64[(c&0x00000fc0) >> 6];
  80     p[3]=base64[(c&0x0000003f) >> 0];
  81     if(i > size)
  82       p[3]='=';
  83     if(i > size+1)
  84       p[2]='=';
  85     p+=4;
  86   }
  87   *p=0;
  88   *str = s;
  89   return strlen(s);
  90 }
  91
  92 int base64_decode(const char *str, void *data)
  93 {
  94   const char *p;
  95   unsigned char *q;
  96   int c;
  97   int x;
  98   int done = 0;
  99   q=(unsigned char*)data;
 100   for(p=str; *p && !done; p+=4){
 101     x = pos(p[0]);
 102     if(x >= 0)
 103       c = x;
 104     else{
 105       done = 3;
 106       break;
 107     }
 108     c*=64;
 109
 110     x = pos(p[1]);
 111     if(x >= 0)
 112       c += x;
 113     else{
 114       fprintf(stderr, "base64_decode: bad character '%c' (%.2x)\n",
 115               p[1], p[1]);
 116       return -1;
 117     }
 118     c*=64;
 119
 120     if(p[2] == '=')
 121       done++;
 122     else{
 123       x = pos(p[2]);
 124       if(x >= 0)
 125         c += x;
 126       else{
 127         fprintf(stderr, "base64_decode: bad character '%c' (%.2x)\n",
 128               p[2], p[2]);
 129         return -1;
 130       }
 131     }
 132     c*=64;
 133
 134     if(p[3] == '=')
 135       done++;
 136     else{
 137       if(done){
 138         fprintf(stderr, "base64_decode: done, '%c' (%.2x)\n",
 139             p[3], p[3]);
 140         return -1;
 141       }
 142       x = pos(p[3]);
 143       if(x >= 0)
 144         c += x;
 145       else
 146         return -1;
 147     }
 148     if(done < 3)
 149       *q++=(c&0x00ff0000)>>16;
 150
 151     if(done < 2)
 152       *q++=(c&0x0000ff00)>>8;
 153     if(done < 1)
 154       *q++=(c&0x000000ff)>>0;
 155   }
 156   return q - (unsigned char*)data;
 157 }