121 lines
2.2 KiB
C++
121 lines
2.2 KiB
C++
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#include "Base64.h"
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#include "stdio.h"
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#include "string.h"
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int DecodeBase64(char * pInput, char * pOutput) {
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int i = 0;
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int iCnt = 0;
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int iSrcLen = (int)strlen(pInput);
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char * p = pOutput;
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for (i=0; i<iSrcLen; i++)
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{
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if (pInput[i] > 127) continue;
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if (pInput[i] == '=') return p-pOutput+1;
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char a = BVal(pInput[i]);
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if (a == 255) continue;
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switch (iCnt)
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{
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case 0:
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{
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*p = a << 2;
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iCnt++;
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}
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break;
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case 1:
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{
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*p++ |= a >> 4;
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*p = a << 4;
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iCnt++;
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}
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break;
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case 2:
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{
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*p++ |= a >> 2;
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*p = a << 6;
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iCnt++;
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}
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break;
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case 3:
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{
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*p++ |= a;
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iCnt = 0;
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}
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break;
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}
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}
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*p = 0x00;
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return p-pOutput;
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}
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int EncodeBase64(char * pInput,int iInputLen,char * pOutput)
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{
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int i = 0;
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int loop = 0;
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int remain = 0;
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int iDstLen = 0;
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int iSrcLen = iInputLen;
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loop = iSrcLen/3;
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remain = iSrcLen%3;
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// also can encode native char one by one as decode method
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// but because all of char in native string is to be encoded so encode 3-chars one time is easier.
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for (i=0; i<loop; i++)
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{
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char a1 = (pInput[i*3] >> 2);
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char a2 = ( ((pInput[i*3] & 0x03) << 4) | (pInput[i*3+1] >> 4) );
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char a3 = ( ((pInput[i*3+1] & 0x0F) << 2) | ((pInput[i*3+2] & 0xC0) >> 6) );
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char a4 = (pInput[i*3+2] & 0x3F);
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pOutput[i*4] = AVal(a1);
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pOutput[i*4+1] = AVal(a2);
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pOutput[i*4+2] = AVal(a3);
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pOutput[i*4+3] = AVal(a4);
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}
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iDstLen = i*4;
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if (remain == 1)
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{
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// should pad two equal sign
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i = iSrcLen-1;
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char a1 = (pInput[i] >> 2);
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char a2 = ((pInput[i] & 0x03) << 4);
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pOutput[iDstLen++] = AVal(a1);
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pOutput[iDstLen++] = AVal(a2);
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pOutput[iDstLen++] = '=';
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pOutput[iDstLen++] = '=';
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pOutput[iDstLen] = 0x00;
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}
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else if (remain == 2)
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{
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// should pad one equal sign
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i = iSrcLen-2;
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char a1 = (pInput[i] >> 2);
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char a2 = ( ((pInput[i] & 0x03) << 4) | (pInput[i+1] >> 4));
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char a3 = ( (pInput[i+1] & 0x0F) << 2);
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pOutput[iDstLen++] = AVal(a1);
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pOutput[iDstLen++] = AVal(a2);
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pOutput[iDstLen++] = AVal(a3);
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pOutput[iDstLen++] = '=';
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pOutput[iDstLen] = 0x00;
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}
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else
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{
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// just division by 3
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pOutput[iDstLen] = 0x00;
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}
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return iDstLen;
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}
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