src/common/base64.cpp

   1 ///////////////////////////////////////////////////////////////////////////////
   2 // Name:        src/common/base64.cpp
   3 // Purpose:     implementation of BASE64 encoding/decoding functions
   4 // Author:      Charles Reimers, Vadim Zeitlin
   5 // Created:     2007-06-18
   6 // Licence:     wxWindows licence
   7 ///////////////////////////////////////////////////////////////////////////////
   8
   9 #include "wx/wxprec.h"
  10
  11 #ifdef __BORLANDC__
  12     #pragma hdrstop
  13 #endif
  14
  15 #if wxUSE_BASE64
  16
  17 #include "wx/base64.h"
  18
  19 size_t
  20 wxBase64Encode(char *dst, size_t dstLen, const void *src_, size_t srcLen)
  21 {
  22     wxCHECK_MSG( src_, wxCONV_FAILED, wxT("NULL input buffer") );
  23
  24     const unsigned char *src = static_cast<const unsigned char *>(src_);
  25
  26     static const char b64[] =
  27         "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
  28
  29
  30     size_t encLen = 0;
  31
  32     // encode blocks of 3 bytes into 4 base64 characters
  33     for ( ; srcLen >= 3; srcLen -= 3, src += 3 )
  34     {
  35         encLen += 4;
  36         if ( dst )
  37         {
  38             if ( encLen > dstLen )
  39                 return wxCONV_FAILED;
  40
  41             *dst++ = b64[src[0] >> 2];
  42             *dst++ = b64[((src[0] & 0x03) << 4) | ((src[1] & 0xf0) >> 4)];
  43             *dst++ = b64[((src[1] & 0x0f) << 2) | ((src[2] & 0xc0) >> 6)];
  44             *dst++ = b64[src[2] & 0x3f];
  45         }
  46     }
  47
  48     // finish with the remaining characters
  49     if ( srcLen )
  50     {
  51         encLen += 4;
  52         if ( dst )
  53         {
  54             if ( encLen > dstLen )
  55                 return wxCONV_FAILED;
  56
  57             // we have definitely one and maybe two bytes remaining
  58             unsigned char next = srcLen == 2 ? src[1] : 0;
  59             *dst++ = b64[src[0] >> 2];
  60             *dst++ = b64[((src[0] & 0x03) << 4) | ((next & 0xf0) >> 4)];
  61             *dst++ = srcLen == 2 ? b64[((next & 0x0f) << 2)] : '=';
  62             *dst = '=';
  63         }
  64     }
  65
  66     return encLen;
  67 }
  68
  69 size_t
  70 wxBase64Decode(void *dst_, size_t dstLen,
  71                const char *src, size_t srcLen,
  72                wxBase64DecodeMode mode,
  73                size_t *posErr)
  74 {
  75     wxCHECK_MSG( src, wxCONV_FAILED, wxT("NULL input buffer") );
  76
  77     unsigned char *dst = static_cast<unsigned char *>(dst_);
  78
  79     size_t decLen = 0;
  80
  81     if ( srcLen == wxNO_LEN )
  82         srcLen = strlen(src);
  83
  84     // this table contains the values, in base 64, of all valid characters and
  85     // special values WSP or INV for white space and invalid characters
  86     // respectively as well as a special PAD value for '='
  87     enum
  88     {
  89         WSP = 200,
  90         INV,
  91         PAD
  92     };
  93
  94     static const unsigned char decode[256] =
  95     {
  96         WSP,INV,INV,INV,INV,INV,INV,INV,INV,WSP,WSP,INV,WSP,WSP,INV,INV,
  97         INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,
  98         WSP,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,076,INV,INV,INV,077,
  99         064,065,066,067,070,071,072,073,074,075,INV,INV,INV,PAD,INV,INV,
 100         INV,000,001,002,003,004,005,006,007,010,011,012,013,014,015,016,
 101         017,020,021,022,023,024,025,026,027,030,031,INV,INV,INV,INV,INV,
 102         INV,032,033,034,035,036,037,040,041,042,043,044,045,046,047,050,
 103         051,052,053,054,055,056,057,060,061,062,063,INV,INV,INV,INV,INV,
 104         INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,
 105         INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,
 106         INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,
 107         INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,
 108         INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,
 109         INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,
 110         INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,
 111         INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,
 112     };
 113
 114     // we decode input by groups of 4 characters but things are complicated by
 115     // the fact that there can be whitespace and other junk in it too so keep
 116     // record of where exactly we're inside the current quartet in this var
 117     int n = 0;
 118     unsigned char in[4];                    // current quartet
 119     bool end = false;                       // set when we find padding
 120     size_t padLen = 0;                      // length lost to padding
 121     const char *p;
 122     for ( p = src; srcLen; p++, srcLen-- )
 123     {
 124         const unsigned char c = decode[static_cast<unsigned char>(*p)];
 125         switch ( c )
 126         {
 127             case WSP:
 128                 if ( mode == wxBase64DecodeMode_SkipWS )
 129                     continue;
 130                 // fall through
 131
 132             case INV:
 133                 if ( mode == wxBase64DecodeMode_Relaxed )
 134                     continue;
 135
 136                 // force the loop to stop and an error to be returned
 137                 n = -1;
 138                 srcLen = 1;
 139                 break;
 140
 141             case PAD:
 142                 // set the flag telling us that we're past the end now
 143                 end = true;
 144
 145                 // there can be either a single '=' at the end of a quartet or
 146                 // "==" in positions 2 and 3
 147                 if ( n == 3 )
 148                 {
 149                     padLen = 1;
 150                     in[n++] = '\0';
 151                 }
 152                 else if ( (n == 2) && (--srcLen && *++p == '=') )
 153                 {
 154                     padLen = 2;
 155                     in[n++] = '\0';
 156                     in[n++] = '\0';
 157                 }
 158                 else // invalid padding
 159                 {
 160                     // force the loop terminate with an error
 161                     n = -1;
 162                     srcLen = 1;
 163                 }
 164                 break;
 165
 166             default:
 167                 if ( end )
 168                 {
 169                     // nothing is allowed after the end so provoke error return
 170                     n = -1;
 171                     srcLen = 1;
 172                     break;
 173                 }
 174
 175                 in[n++] = c;
 176         }
 177
 178         if ( n == 4 )
 179         {
 180             // got entire block, decode
 181             decLen += 3 - padLen;
 182             if ( dst )
 183             {
 184                 if ( decLen > dstLen )
 185                     return wxCONV_FAILED;
 186
 187                 // undo the bit shifting done during encoding
 188                 *dst++ = in[0] << 2 | in[1] >> 4;
 189
 190                 // be careful to not overwrite the output buffer with NUL pad
 191                 // bytes
 192                 if ( padLen != 2 )
 193                 {
 194                     *dst++ = in[1] << 4 | in[2] >> 2;
 195                     if ( !padLen )
 196                         *dst++ = in[2] << 6 | in[3];
 197                 }
 198             }
 199
 200             n = 0;
 201         }
 202     }
 203
 204     if ( n )
 205     {
 206         if ( posErr )
 207         {
 208             // notice that the error was on a previous position as we did one
 209             // extra "p++" in the loop line after it
 210             *posErr = p - src - 1;
 211         }
 212
 213         return wxCONV_FAILED;
 214     }
 215
 216     return decLen;
 217 }
 218
 219 wxMemoryBuffer wxBase64Decode(const char *src,
 220                               size_t srcLen,
 221                               wxBase64DecodeMode mode,
 222                               size_t *posErr)
 223 {
 224     wxMemoryBuffer buf;
 225     wxCHECK_MSG( src, buf, wxT("NULL input buffer") );
 226
 227     if ( srcLen == wxNO_LEN )
 228         srcLen = strlen(src);
 229
 230     size_t len = wxBase64DecodedSize(srcLen);
 231     len = wxBase64Decode(buf.GetWriteBuf(len), len, src, srcLen, mode, posErr);
 232     if ( len == wxCONV_FAILED )
 233         len = 0;
 234
 235     buf.SetDataLen(len);
 236
 237     return buf;
 238 }
 239
 240 #endif // wxUSE_BASE64