//
// Copyright (c) Microsoft Corporation.  All rights reserved.
//
//
// This source code is licensed under Microsoft Shared Source License
// Version 1.0 for Windows CE.
// For a copy of the license visit http://go.microsoft.com/fwlink/?LinkId=3223.
//
//+---------------------------------------------------------------------------------
//
//
// File:
//      xmlbase64.cpp
//
// Contents:
//
//      base64 encode/decode implementation
//
//----------------------------------------------------------------------------------

#include "headers.h"

#ifdef UNDER_CE
#include "WinCEUtils.h"
#endif


// The following table translates an ascii subset to 6 bit values as follows
// (see rfc 1521):
//
//  input    hex (decimal)
//  'A' --> 0x00 (0)
//  'B' --> 0x01 (1)
//  ...
//  'Z' --> 0x19 (25)
//  'a' --> 0x1a (26)
//  'b' --> 0x1b (27)
//  ...
//  'z' --> 0x33 (51)
//  '0' --> 0x34 (52)
//  ...
//  '9' --> 0x3d (61)
//  '+' --> 0x3e (62)
//  '/' --> 0x3f (63)
//
// Encoded lines must be no longer than 76 characters.
// The final "quantum" is handled as follows:  The translation output shall
// always consist of 4 characters.  'x', below, means a translated character,
// and '=' means an equal sign.  0, 1 or 2 equal signs padding out a four byte
// translation quantum means decoding the four bytes would result in 3, 2 or 1
// unencoded bytes, respectively.
//
//  unencoded size    encoded data
//  --------------    ------------
//     1 byte       "xx=="
//     2 bytes      "xxx="
//     3 bytes      "xxxx"

#define CB_BASE64LINEMAX    64  // others use 64 -- could be up to 76

// Any other (invalid) input character value translates to 0x40 (64)

const BYTE abDecode[256] =
{
    /* 00: */ 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
    /* 10: */ 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
    /* 20: */ 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 62, 64, 64, 64, 63,
    /* 30: */ 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 64, 64, 64, 64, 64, 64,
    /* 40: */ 64,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14,
    /* 50: */ 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 64, 64, 64, 64, 64,
    /* 60: */ 64, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
    /* 70: */ 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 64, 64, 64, 64, 64,
    /* 80: */ 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
    /* 90: */ 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
    /* a0: */ 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
    /* b0: */ 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
    /* c0: */ 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
    /* d0: */ 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
    /* e0: */ 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
    /* f0: */ 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
};


const UCHAR abEncode[] =
    /*  0 thru 25: */ "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    /* 26 thru 51: */ "abcdefghijklmnopqrstuvwxyz"
    /* 52 thru 61: */ "0123456789"
    /* 62 and 63: */  "+/";


DWORD
Base64DecodeA(const char * pchIn, DWORD cchIn, BYTE * pbOut, DWORD * pcbOut)
{
    DWORD err = ERROR_SUCCESS;
    DWORD cchInDecode, cbOutDecode;
    CHAR const *pchInEnd;
    CHAR const *pchInT;
    BYTE *pbOutT;

    // Count the translatable characters, skipping whitespace & CR-LF chars.
    cchInDecode = 0;
    pchInEnd = &pchIn[cchIn];
    for (pchInT = pchIn; pchInT < pchInEnd; pchInT++)
    {
        if (sizeof(abDecode) < (unsigned) *pchInT || abDecode[*pchInT] > 63)
        {
            // skip all whitespace
            if (	*pchInT == ' ' 
                ||	*pchInT == '\t' 
                ||	*pchInT == '\r' 
                ||	*pchInT == '\n'
                )
            {
                continue;
            }

            if (0 != cchInDecode)
            {
                if ((cchInDecode % 4) == 0)
                {
                    break;          // ends on quantum boundary
                }

                // The length calculation may stop in the middle of the last
                // translation quantum, because the equal sign padding
                // characters are treated as invalid input.  If the last
                // translation quantum is not 4 bytes long, it must be 2 or 3
                // bytes long.

                if (*pchInT == '=' && (cchInDecode % 4) != 1)
                {
                    break;              // normal termination
                }
            }
            err = ERROR_INVALID_DATA;
            goto error;
        }
        cchInDecode++;
    }

    ASSERT(pchInT <= pchInEnd);
    pchInEnd = pchInT;      // don't process any trailing stuff again

    // We know how many translatable characters are in the input buffer, so now
    // set the output buffer size to three bytes for every four (or fraction of
    // four) input bytes.

    cbOutDecode = ((cchInDecode + 3) / 4) * 3;

    pbOutT = pbOut;

    if (NULL == pbOut)
    {
        pbOutT += cbOutDecode;
    }
    else
    {
        // Decode one quantum at a time: 4 bytes ==> 3 bytes

        ASSERT(cbOutDecode <= *pcbOut);
        pchInT = pchIn;
        while (cchInDecode > 0)
        {
            DWORD i;
            BYTE ab4[4];

            memset(ab4, 0, sizeof(ab4));
            for (i = 0; i < min(sizeof(ab4)/sizeof(ab4[0]), cchInDecode); i++)
            {
                while (
                    sizeof(abDecode) > (unsigned) *pchInT &&
                    63 < abDecode[*pchInT])
                {
                    pchInT++;
                }
                ASSERT(pchInT < pchInEnd);
                ab4[i] = (BYTE) *pchInT++;
            }

            // Translate 4 input characters into 6 bits each, and deposit the
            // resulting 24 bits into 3 output bytes by shifting as appropriate.

            // out[0] = in[0]:in[1] 6:2
            // out[1] = in[1]:in[2] 4:4
            // out[2] = in[2]:in[3] 2:6

            *pbOutT++ =
                (BYTE) ((abDecode[ab4[0]] << 2) | (abDecode[ab4[1]] >> 4));

            if (i > 2)
            {
                *pbOutT++ =
                    (BYTE) ((abDecode[ab4[1]] << 4) | (abDecode[ab4[2]] >> 2));
            }
            if (i > 3)
            {
                *pbOutT++ = (BYTE) ((abDecode[ab4[2]] << 6) | abDecode[ab4[3]]);
            }
            cchInDecode -= i;
        }
        ASSERT((DWORD) (pbOutT - pbOut) <= cbOutDecode);
    }
    *pcbOut = (DWORD)(pbOutT - pbOut);
error:
    return(err);
}

// Base64EncodeA 
//
// RETURNS  0 (i.e. ERROR_SUCCESS) on success
//


DWORD
Base64EncodeA(
              IN BYTE const *pbIn,
              IN DWORD cbIn,
              OUT CHAR *pchOut,
              OUT DWORD *pcchOut)
{
    CHAR *pchOutT;
    DWORD cchOutEncode;

    // Allocate enough memory for full final translation quantum.
    cchOutEncode = ((cbIn + 2) / 3) * 4;

    // and enough for CR-LF pairs for every CB_BASE64LINEMAX character line.
    cchOutEncode +=
        2 * ((cchOutEncode + CB_BASE64LINEMAX - 1) / CB_BASE64LINEMAX);

    pchOutT = pchOut;
    if (NULL == pchOut)
    {
        pchOutT += cchOutEncode;
    }
    else
    {
        DWORD cCol;

        ASSERT(cchOutEncode <= *pcchOut);
        cCol = 0;
        while ((long) cbIn > 0) // signed comparison -- cbIn can wrap
        {
            BYTE ab3[3];

            if (cCol == CB_BASE64LINEMAX/4)
            {
                cCol = 0;
                *pchOutT++ = '\r';
                *pchOutT++ = '\n';
            }
            cCol++;
            memset(ab3, 0, sizeof(ab3));

            ab3[0] = *pbIn++;
            if (cbIn > 1)
            {
                ab3[1] = *pbIn++;
                if (cbIn > 2)
                {
                    ab3[2] = *pbIn++;
                }
            }

            *pchOutT++ = abEncode[ab3[0] >> 2];
            *pchOutT++ = abEncode[((ab3[0] << 4) | (ab3[1] >> 4)) & 0x3f];
            *pchOutT++ = (cbIn > 1)?
                abEncode[((ab3[1] << 2) | (ab3[2] >> 6)) & 0x3f] : '=';
            *pchOutT++ = (cbIn > 2)? abEncode[ab3[2] & 0x3f] : '=';

            cbIn -= 3;
        }
        *pchOutT++ = '\r';
        *pchOutT++ = '\n';
        ASSERT((DWORD) (pchOutT - pchOut) <= cchOutEncode);
    }
    *pcchOut = (DWORD)(pchOutT - pchOut);
    return(ERROR_SUCCESS);
}

// Base64EncodeW 
//
// RETURNS  0 (i.e. ERROR_SUCCESS) on success
//

DWORD Base64EncodeW(
                    BYTE const *pbIn,
                    DWORD cbIn,
                    WCHAR *wszOut,
                    DWORD *pcchOut)

{

    DWORD   cchOut;
    char   *pch = NULL;
    DWORD   cch;
    DWORD   err;

    ASSERT(pcchOut != NULL);

    // only want to know how much to allocate
    // we know all base64 char map 1-1 with unicode
    if( wszOut == NULL )
    {
        // get the number of characters
        *pcchOut = 0;
        err = Base64EncodeA(
            pbIn,
            cbIn,
            NULL,
            pcchOut);
    }

    // otherwise we have an output buffer
    else
    {

        // char count is the same be it ascii or unicode,
        cchOut = *pcchOut;
        cch = 0;
        err = ERROR_OUTOFMEMORY;
        if( (pch = new char[cchOut]) != NULL  &&            
            (err = Base64EncodeA(
            pbIn,
            cbIn,
            pch,
            &cchOut)) == ERROR_SUCCESS      )
        {

            // should not fail!
            cch = MultiByteToWideChar(0, 
                0, 
                pch, 
                cchOut, 
                wszOut, 
                *pcchOut);

            // check to make sure we did not fail                            
            ASSERT(*pcchOut == 0 || cch != 0);                            
        }
    }

    delete [] pch; 

    return(err);
}

// Base64DecodeW 
//
// RETURNS  0 (i.e. ERROR_SUCCESS) on success
//

DWORD Base64DecodeW(
                    const WCHAR * wszIn,
                    DWORD cch,
                    BYTE *pbOut,
                    DWORD *pcbOut)
{

    char *pch = 0;
    DWORD err = ERROR_SUCCESS;
    
    if( (pch = new char[cch]) == NULL ) 
    {
        err = ERROR_OUTOFMEMORY;
    }
    else if( WideCharToMultiByte(0, 0, wszIn, cch, pch, cch, 
        NULL, NULL) == 0 ) 
    {
        err = ERROR_NO_DATA;
    }
    else if( pbOut == NULL ) 
    {
        *pcbOut = 0;
        err = Base64DecodeA(pch, cch, NULL, pcbOut);
    }
    else 
    {
        err = Base64DecodeA(pch, cch, pbOut, pcbOut);
    }


    delete [] pch;
    return(err);
}
