dlls/secur32/base64_codec.c

   1 /*
   2  * base64 encoder/decoder
   3  *
   4  * Copyright 2005 by Kai Blin
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, write to the Free Software
  18  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  19  */
  20
  21 #include "windef.h"
  22 #include "winerror.h"
  23 #include "sspi.h"
  24 #include "wine/debug.h"
  25
  26 WINE_DEFAULT_DEBUG_CHANNEL(secur32);
  27
  28 static const char b64[] =
  29 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
  30
  31 SECURITY_STATUS encodeBase64(PBYTE in_buf, int in_len, char* out_buf,
  32         int max_len, int *out_len)
  33 {
  34     int div, i;
  35     PBYTE d = in_buf;
  36     int bytes = (in_len*8 + 5)/6, pad_bytes = (bytes % 4) ? 4 - (bytes % 4) : 0;
  37
  38     TRACE("bytes is %d, pad bytes is %d\n", bytes, pad_bytes);
  39     *out_len = bytes + pad_bytes;
  40
  41     if(bytes + pad_bytes + 1 > max_len)
  42         return SEC_E_BUFFER_TOO_SMALL;
  43
  44     /* Three bytes of input give 4 chars of output */
  45     div = in_len / 3;
  46
  47     i = 0;
  48     while(div > 0)
  49     {
  50         /* first char is the first 6 bits of the first byte*/
  51         out_buf[i + 0] = b64[ ( d[0] >> 2) & 0x3f ];
  52         /* second char is the last 2 bits of the first byte and the first 4
  53          * bits of the second byte */
  54         out_buf[i + 1] = b64[ ((d[0] << 4) & 0x30) | (d[1] >> 4 & 0x0f)];
  55         /* third char is the last 4 bits of the second byte and the first 2
  56          * bits of the third byte */
  57         out_buf[i + 2] = b64[ ((d[1] << 2) & 0x3c) | (d[2] >> 6 & 0x03)];
  58         /* fourth char is the remaining 6 bits of the third byte */
  59         out_buf[i + 3] = b64[   d[2]       & 0x3f];
  60         i += 4;
  61         d += 3;
  62         div--;
  63     }
  64
  65     switch(pad_bytes)
  66     {
  67         case 1:
  68             /* first char is the first 6 bits of the first byte*/
  69             out_buf[i + 0] = b64[ ( d[0] >> 2) & 0x3f ];
  70             /* second char is the last 2 bits of the first byte and the first 4
  71              * bits of the second byte */
  72             out_buf[i + 1] = b64[ ((d[0] << 4) & 0x30) | (d[1] >> 4 & 0x0f)];
  73             /* third char is the last 4 bits of the second byte padded with
  74              * two zeroes */
  75             out_buf[i + 2] = b64[ ((d[1] >> 4) & 0x3c) ];
  76             /* fourth char is a = to indicate one byte of padding */
  77             out_buf[i + 3] = '=';
  78             out_buf[i + 4] = 0;
  79             break;
  80         case 2:
  81             /* first char is the first 6 bits of the first byte*/
  82             out_buf[i + 0] = b64[ ( d[0] >> 2) & 0x3f ];
  83             /* second char is the last 2 bits of the first byte padded with
  84              * four zeroes*/
  85             out_buf[i + 1] = b64[ ((d[0] << 4) & 0x30)];
  86             /* third char is = to indicate padding */
  87             out_buf[i + 2] = '=';
  88             /* fourth char is = to indicate padding */
  89             out_buf[i + 3] = '=';
  90             out_buf[i + 4] = 0;
  91             break;
  92         default:
  93             out_buf[i] = 0;
  94     }
  95
  96     return SEC_E_OK;
  97 }
  98
  99 static inline BYTE decode(char c)
 100 {
 101     if( c >= 'A' && c <= 'Z')
 102         return c - 'A';
 103     if( c >= 'a' && c <= 'z')
 104         return c - 'a' + 26;
 105     if( c >= '0' && c <= '9')
 106         return c - '0' + 52;
 107     if( c == '+')
 108         return 62;
 109     if( c == '/')
 110         return 63;
 111     else
 112         return 64;
 113 }
 114
 115 SECURITY_STATUS decodeBase64(char *in_buf, int in_len, PBYTE out_buf,
 116         int max_len, int *out_len)
 117 {
 118     int len = in_len, i;
 119     char *d = in_buf;
 120     int  ip0, ip1, ip2, ip3;
 121
 122     TRACE("in_len: %d\n", in_len);
 123
 124     if((in_len % 4) != 0)
 125         return SEC_E_INVALID_TOKEN;
 126
 127     if(in_len > max_len)
 128         return SEC_E_BUFFER_TOO_SMALL;
 129
 130     i = 0;
 131     while(len > 4)
 132     {
 133         if((ip0 = decode(d[0])) > 63)
 134             return SEC_E_INVALID_TOKEN;
 135         if((ip1 = decode(d[1])) > 63)
 136             return SEC_E_INVALID_TOKEN;
 137         if((ip2 = decode(d[2])) > 63)
 138             return SEC_E_INVALID_TOKEN;
 139         if((ip3 = decode(d[3])) > 63)
 140             return SEC_E_INVALID_TOKEN;
 141
 142         out_buf[i + 0] = (ip0 << 2) | (ip1 >> 4);
 143         out_buf[i + 1] = (ip1 << 4) | (ip2 >> 2);
 144         out_buf[i + 2] = (ip2 << 6) |  ip3;
 145         len -= 4;
 146         i += 3;
 147         d += 4;
 148     }
 149
 150     if(d[2] == '=')
 151     {
 152         if((ip0 = decode(d[0])) > 63)
 153             return SEC_E_INVALID_TOKEN;
 154         if((ip1 = decode(d[1])) > 63)
 155             return SEC_E_INVALID_TOKEN;
 156
 157         out_buf[i] = (ip0 << 2) | (ip1 >> 4);
 158         i++;
 159     }
 160     else if(d[3] == '=')
 161     {
 162         if((ip0 = decode(d[0])) > 63)
 163             return SEC_E_INVALID_TOKEN;
 164         if((ip1 = decode(d[1])) > 63)
 165             return SEC_E_INVALID_TOKEN;
 166         if((ip2 = decode(d[2])) > 63)
 167             return SEC_E_INVALID_TOKEN;
 168
 169         out_buf[i + 0] = (ip0 << 2) | (ip1 >> 4);
 170         out_buf[i + 1] = (ip1 << 4) | (ip2 >> 2);
 171         i += 2;
 172     }
 173     else
 174     {
 175         if((ip0 = decode(d[0])) > 63)
 176             return SEC_E_INVALID_TOKEN;
 177         if((ip1 = decode(d[1])) > 63)
 178             return SEC_E_INVALID_TOKEN;
 179         if((ip2 = decode(d[2])) > 63)
 180             return SEC_E_INVALID_TOKEN;
 181         if((ip3 = decode(d[3])) > 63)
 182             return SEC_E_INVALID_TOKEN;
 183
 184
 185         out_buf[i + 0] = (ip0 << 2) | (ip1 >> 4);
 186         out_buf[i + 1] = (ip1 << 4) | (ip2 >> 2);
 187         out_buf[i + 2] = (ip2 << 6) |  ip3;
 188         i += 3;
 189     }
 190     *out_len = i;
 191     return SEC_E_OK;
 192 }