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 // RCS-ID:      $Id$
   7 // Licence:     wxWindows licence
   8 ///////////////////////////////////////////////////////////////////////////////
   9
  10 #include "wx/wxprec.h"
  11
  12 #if wxUSE_BASE64
  13
  14 #include "wx/base64.h"
  15
  16 size_t
  17 wxBase64Encode(char *dst, size_t dstLen, const void *src_, size_t srcLen)
  18 {
  19     wxCHECK_MSG( src_, wxCONV_FAILED, _T("NULL input buffer") );
  20
  21     const unsigned char *src = static_cast<const unsigned char *>(src_);
  22
  23     static const char b64[] =
  24         "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
  25
  26
  27     size_t encLen = 0;
  28
  29     // encode blocks of 3 bytes into 4 base64 characters
  30     for ( ; srcLen >= 3; srcLen -= 3, src += 3 )
  31     {
  32         encLen += 4;
  33         if ( dst )
  34         {
  35             if ( encLen > dstLen )
  36                 return wxCONV_FAILED;
  37
  38             *dst++ = b64[src[0] >> 2];
  39             *dst++ = b64[((src[0] & 0x03) << 4) | ((src[1] & 0xf0) >> 4)];
  40             *dst++ = b64[((src[1] & 0x0f) << 2) | ((src[2] & 0xc0) >> 6)];
  41             *dst++ = b64[src[2] & 0x3f];
  42         }
  43     }
  44
  45     // finish with the remaining characters
  46     if ( srcLen )
  47     {
  48         encLen += 4;
  49         if ( dst )
  50         {
  51             if ( encLen > dstLen )
  52                 return wxCONV_FAILED;
  53
  54             // we have definitely one and maybe two bytes remaining
  55             unsigned char next = srcLen == 2 ? src[1] : 0;
  56             *dst++ = b64[src[0] >> 2];
  57             *dst++ = b64[((src[0] & 0x03) << 4) | ((next & 0xf0) >> 4)];
  58             *dst++ = srcLen == 2 ? b64[((next & 0x0f) << 2)] : '=';
  59             *dst = '=';
  60         }
  61     }
  62
  63     return encLen;
  64 }
  65
  66 size_t
  67 wxBase64Decode(void *dst_, size_t dstLen,
  68                const char *src, size_t srcLen,
  69                wxBase64DecodeMode mode,
  70                size_t *posErr)
  71 {
  72     wxCHECK_MSG( src, wxCONV_FAILED, _T("NULL input buffer") );
  73
  74     unsigned char *dst = static_cast<unsigned char *>(dst_);
  75
  76     size_t decLen = 0;
  77
  78     if ( srcLen == wxNO_LEN )
  79         srcLen = strlen(src);
  80
  81     // this table contains the values, in base 64, of all valid characters and
  82     // special values WSP or INV for white space and invalid characters
  83     // respectively as well as a special PAD value for '='
  84     enum
  85     {
  86         WSP = 200,
  87         INV,
  88         PAD
  89     };
  90
  91     static const unsigned char decode[256] =
  92     {
  93         WSP,INV,INV,INV,INV,INV,INV,INV,INV,WSP,WSP,INV,WSP,WSP,INV,INV,
  94         INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,
  95         WSP,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,076,INV,INV,INV,077,
  96         064,065,066,067,070,071,072,073,074,075,INV,INV,INV,PAD,INV,INV,
  97         INV,000,001,002,003,004,005,006,007,010,011,012,013,014,015,016,
  98         017,020,021,022,023,024,025,026,027,030,031,INV,INV,INV,INV,INV,
  99         INV,032,033,034,035,036,037,040,041,042,043,044,045,046,047,050,
 100         051,052,053,054,055,056,057,060,061,062,063,INV,INV,INV,INV,INV,
 101         INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,
 102         INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,
 103         INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,INV,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     };
 110
 111     // we decode input by groups of 4 characters but things are complicated by
 112     // the fact that there can be whitespace and other junk in it too so keep
 113     // record of where exactly we're inside the current quartet in this var
 114     int n = 0;
 115     unsigned char in[4];                    // current quartet
 116     bool end = false;                       // set when we find padding
 117     size_t padLen = 0;                      // length lost to padding
 118     const char *p;
 119     for ( p = src; srcLen; p++, srcLen-- )
 120     {
 121         const unsigned char c = decode[static_cast<unsigned char>(*p)];
 122         switch ( c )
 123         {
 124             case WSP:
 125                 if ( mode == wxBase64DecodeMode_SkipWS )
 126                     continue;
 127                 // fall through
 128
 129             case INV:
 130                 if ( mode == wxBase64DecodeMode_Relaxed )
 131                     continue;
 132
 133                 // force the loop to stop and an error to be returned
 134                 n = -1;
 135                 srcLen = 1;
 136                 break;
 137
 138             case PAD:
 139                 // set the flag telling us that we're past the end now
 140                 end = true;
 141
 142                 // there can be either a single '=' at the end of a quartet or
 143                 // "==" in positions 2 and 3
 144                 if ( n == 3 )
 145                 {
 146                     padLen = 1;
 147                     in[n++] = '\0';
 148                 }
 149                 else if ( (n == 2) && (--srcLen && *++p == '=') )
 150                 {
 151                     padLen = 2;
 152                     in[n++] = '\0';
 153                     in[n++] = '\0';
 154                 }
 155                 else // invalid padding
 156                 {
 157                     // force the loop terminate with an error
 158                     n = -1;
 159                     srcLen = 1;
 160                 }
 161                 break;
 162
 163             default:
 164                 if ( end )
 165                 {
 166                     // nothing is allowed after the end so provoke error return
 167                     n = -1;
 168                     srcLen = 1;
 169                     break;
 170                 }
 171
 172                 in[n++] = c;
 173         }
 174
 175         if ( n == 4 )
 176         {
 177             // got entire block, decode
 178             decLen += 3 - padLen;
 179             if ( dst )
 180             {
 181                 if ( decLen > dstLen )
 182                     return wxCONV_FAILED;
 183
 184                 // undo the bit shifting done during encoding
 185                 *dst++ = in[0] << 2 | in[1] >> 4;
 186                 *dst++ = in[1] << 4 | in[2] >> 2;
 187                 *dst++ = in[2] << 6 | in[3];
 188             }
 189
 190             n = 0;
 191         }
 192     }
 193
 194     if ( n )
 195     {
 196         if ( posErr )
 197         {
 198             // notice that the error was on a previous position as we did one
 199             // extra "p++" in the loop line after it
 200             *posErr = p - src - 1;
 201         }
 202
 203         return wxCONV_FAILED;
 204     }
 205
 206     return decLen;
 207 }
 208
 209 wxMemoryBuffer wxBase64Decode(const char *src,
 210                               size_t srcLen,
 211                               wxBase64DecodeMode mode,
 212                               size_t *posErr)
 213 {
 214     wxMemoryBuffer buf;
 215     wxCHECK_MSG( src, buf, _T("NULL input buffer") );
 216
 217     if ( srcLen == wxNO_LEN )
 218         srcLen = strlen(src);
 219
 220     size_t len = wxBase64DecodedSize(srcLen);
 221     len = wxBase64Decode(buf.GetWriteBuf(len), len, src, srcLen, mode, posErr);
 222     if ( len == wxCONV_FAILED )
 223         len = 0;
 224
 225     buf.SetDataLen(len);
 226
 227     return buf;
 228 }
 229
 230 #endif // wxUSE_BASE64