lib/libalpm/base64.c

   1 /*
   2  *  RFC 1521 base64 encoding/decoding
   3  *
   4  *  Copyright (C) 2006-2010, Brainspark B.V.
   5  *
   6  *  This file is part of PolarSSL (http://www.polarssl.org)
   7  *  Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org>
   8  *
   9  *  All rights reserved.
  10  *
  11  *  This program is free software; you can redistribute it and/or modify
  12  *  it under the terms of the GNU General Public License as published by
  13  *  the Free Software Foundation; either version 2 of the License, or
  14  *  (at your option) any later version.
  15  *
  16  *  This program is distributed in the hope that it will be useful,
  17  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19  *  GNU General Public License for more details.
  20  *
  21  *  You should have received a copy of the GNU General Public License
  22  *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
  23  */
  24 /*
  25  *  Pacman Notes:
  26  *
  27  *  Taken from the PolarSSL project at www.polarssl.org under terms of the
  28  *  GPL. This is from version 0.14.2 of the library, and has been modified
  29  *  as following, which may be helpful for future updates:
  30  *  * remove "polarssl/config.h" include
  31  *  * change include from "polarssl/base64.h" to "base64.h"
  32  *  * removal of SELF_TEST code
  33  */
  34
  35 #include "base64.h"
  36
  37 static const unsigned char base64_enc_map[64] =
  38 {
  39     'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J',
  40     'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',
  41     'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd',
  42     'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
  43     'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x',
  44     'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7',
  45     '8', '9', '+', '/'
  46 };
  47
  48 static const unsigned char base64_dec_map[128] =
  49 {
  50     127, 127, 127, 127, 127, 127, 127, 127, 127, 127,
  51     127, 127, 127, 127, 127, 127, 127, 127, 127, 127,
  52     127, 127, 127, 127, 127, 127, 127, 127, 127, 127,
  53     127, 127, 127, 127, 127, 127, 127, 127, 127, 127,
  54     127, 127, 127,  62, 127, 127, 127,  63,  52,  53,
  55      54,  55,  56,  57,  58,  59,  60,  61, 127, 127,
  56     127,  64, 127, 127, 127,   0,   1,   2,   3,   4,
  57       5,   6,   7,   8,   9,  10,  11,  12,  13,  14,
  58      15,  16,  17,  18,  19,  20,  21,  22,  23,  24,
  59      25, 127, 127, 127, 127, 127, 127,  26,  27,  28,
  60      29,  30,  31,  32,  33,  34,  35,  36,  37,  38,
  61      39,  40,  41,  42,  43,  44,  45,  46,  47,  48,
  62      49,  50,  51, 127, 127, 127, 127, 127
  63 };
  64
  65 /*
  66  * Encode a buffer into base64 format
  67  */
  68 int base64_encode( unsigned char *dst, int *dlen,
  69                    const unsigned char *src, int  slen )
  70 {
  71     int i, n;
  72     int C1, C2, C3;
  73     unsigned char *p;
  74
  75     if( slen == 0 )
  76         return( 0 );
  77
  78     n = (slen << 3) / 6;
  79
  80     switch( (slen << 3) - (n * 6) )
  81     {
  82         case  2: n += 3; break;
  83         case  4: n += 2; break;
  84         default: break;
  85     }
  86
  87     if( *dlen < n + 1 )
  88     {
  89         *dlen = n + 1;
  90         return( POLARSSL_ERR_BASE64_BUFFER_TOO_SMALL );
  91     }
  92
  93     n = (slen / 3) * 3;
  94
  95     for( i = 0, p = dst; i < n; i += 3 )
  96     {
  97         C1 = *src++;
  98         C2 = *src++;
  99         C3 = *src++;
 100
 101         *p++ = base64_enc_map[(C1 >> 2) & 0x3F];
 102         *p++ = base64_enc_map[(((C1 &  3) << 4) + (C2 >> 4)) & 0x3F];
 103         *p++ = base64_enc_map[(((C2 & 15) << 2) + (C3 >> 6)) & 0x3F];
 104         *p++ = base64_enc_map[C3 & 0x3F];
 105     }
 106
 107     if( i < slen )
 108     {
 109         C1 = *src++;
 110         C2 = ((i + 1) < slen) ? *src++ : 0;
 111
 112         *p++ = base64_enc_map[(C1 >> 2) & 0x3F];
 113         *p++ = base64_enc_map[(((C1 & 3) << 4) + (C2 >> 4)) & 0x3F];
 114
 115         if( (i + 1) < slen )
 116              *p++ = base64_enc_map[((C2 & 15) << 2) & 0x3F];
 117         else *p++ = '=';
 118
 119         *p++ = '=';
 120     }
 121
 122     *dlen = p - dst;
 123     *p = 0;
 124
 125     return( 0 );
 126 }
 127
 128 /*
 129  * Decode a base64-formatted buffer
 130  */
 131 int base64_decode( unsigned char *dst, int *dlen,
 132                    const unsigned char *src, int  slen )
 133 {
 134     int i, j, n;
 135     unsigned long x;
 136     unsigned char *p;
 137
 138     for( i = j = n = 0; i < slen; i++ )
 139     {
 140         if( ( slen - i ) >= 2 &&
 141             src[i] == '\r' && src[i + 1] == '\n' )
 142             continue;
 143
 144         if( src[i] == '\n' )
 145             continue;
 146
 147         if( src[i] == '=' && ++j > 2 )
 148             return( POLARSSL_ERR_BASE64_INVALID_CHARACTER );
 149
 150         if( src[i] > 127 || base64_dec_map[src[i]] == 127 )
 151             return( POLARSSL_ERR_BASE64_INVALID_CHARACTER );
 152
 153         if( base64_dec_map[src[i]] < 64 && j != 0 )
 154             return( POLARSSL_ERR_BASE64_INVALID_CHARACTER );
 155
 156         n++;
 157     }
 158
 159     if( n == 0 )
 160         return( 0 );
 161
 162     n = ((n * 6) + 7) >> 3;
 163
 164     if( *dlen < n )
 165     {
 166         *dlen = n;
 167         return( POLARSSL_ERR_BASE64_BUFFER_TOO_SMALL );
 168     }
 169
 170    for( j = 3, n = x = 0, p = dst; i > 0; i--, src++ )
 171    {
 172         if( *src == '\r' || *src == '\n' )
 173             continue;
 174
 175         j -= ( base64_dec_map[*src] == 64 );
 176         x  = (x << 6) | ( base64_dec_map[*src] & 0x3F );
 177
 178         if( ++n == 4 )
 179         {
 180             n = 0;
 181             if( j > 0 ) *p++ = (unsigned char)( x >> 16 );
 182             if( j > 1 ) *p++ = (unsigned char)( x >>  8 );
 183             if( j > 2 ) *p++ = (unsigned char)( x       );
 184         }
 185     }
 186
 187     *dlen = p - dst;
 188
 189     return( 0 );
 190 }