74 lines
2.3 KiB
C
74 lines
2.3 KiB
C
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/*--------------------------------------------------------------------------*
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*
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* Microsoft Windows
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* Copyright (C) Microsoft Corporation, 1999 - 1999
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*
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* File: base64.h
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*
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* Contents: Implements encoding / decoding table for base64 format
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*
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* History: 17-Dec-99 audriusz Created
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*
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*--------------------------------------------------------------------------*/
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/*+-------------------------------------------------------------------------*
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* class base64_table
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*
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* PURPOSE: Class maintains Base64 conversion templates. It exposes static methods
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* to both encode and decode Base64 data
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*
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* USAGE: call static methods to encode/decode one piece of data (24 bites or less)
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*
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*+-------------------------------------------------------------------------*/
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class base64_table
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{
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protected:
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static BYTE _six2pr64[64];
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static BYTE _pr2six[256];
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public:
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base64_table();
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int decode4(BYTE * src, int nChars, BYTE * dest);
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BYTE map2six(BYTE bt);
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// static functions used for zero terminated LPOLESTR format data only
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static void encode(const BYTE * &src, DWORD &cbInput, LPOLESTR &dest);
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static bool decode(LPCOLESTR &src, BYTE * &dest);
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};
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/*+-------------------------------------------------------------------------*
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*
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* METHOD: base64_table::map2six
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*
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* PURPOSE: maps symbols to 6bit value if smb is valid, 0xff else
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*
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*+-------------------------------------------------------------------------*/
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inline BYTE base64_table::map2six(BYTE bt)
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{
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return (bt > 255 ? 0xff : _pr2six[bt]);
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}
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/*+-------------------------------------------------------------------------*
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*
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* METHOD: base64_table::decode4
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*
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* PURPOSE: glues 3 bytes from stored 6bit values
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*
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* NOTE: gluing is done in place - data pointed by src is destroyed
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*
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*+-------------------------------------------------------------------------*/
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inline int base64_table::decode4(BYTE * src, int nChars, BYTE * dest)
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{
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// glue to form 3 full bytes
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src[0] <<= 2; src[0] |= (src[1] >> 4);
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src[1] <<= 4; src[1] |= (src[2] >> 2);
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src[2] <<= 6; src[2] |= (src[3] );
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// now store as many bytes as have complete set of bites;
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// int nFull = nChars*6/8; // it actually boils to 0 or nChars - 1, whichever is bigger
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for (int i=0; i< nChars-1; i++)
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*dest++ = src[i];
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return nChars ? nChars - 1 : 0;
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}
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