71 lines
2.0 KiB
C++
71 lines
2.0 KiB
C++
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// Simple Base64 code
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// (c) Copyright 2010 MCQN Ltd.
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// Released under Apache License, version 2.0
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#include "b64.h"
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/* Simple test program
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#include <stdio.h>
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void main()
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{
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char* in = "amcewen";
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char out[22];
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b64_encode(in, 15, out, 22);
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out[21] = '\0';
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printf(out);
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}
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*/
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int b64_encode(const unsigned char* aInput, int aInputLen, unsigned char* aOutput, int aOutputLen)
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{
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// Work out if we've got enough space to encode the input
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// Every 6 bits of input becomes a byte of output
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if (aOutputLen < (aInputLen*8)/6)
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{
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// FIXME Should we return an error here, or just the length
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return (aInputLen*8)/6;
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}
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// If we get here we've got enough space to do the encoding
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const char* b64_dictionary = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
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if (aInputLen == 3)
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{
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aOutput[0] = b64_dictionary[aInput[0] >> 2];
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aOutput[1] = b64_dictionary[(aInput[0] & 0x3)<<4|(aInput[1]>>4)];
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aOutput[2] = b64_dictionary[(aInput[1]&0x0F)<<2|(aInput[2]>>6)];
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aOutput[3] = b64_dictionary[aInput[2]&0x3F];
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}
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else if (aInputLen == 2)
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{
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aOutput[0] = b64_dictionary[aInput[0] >> 2];
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aOutput[1] = b64_dictionary[(aInput[0] & 0x3)<<4|(aInput[1]>>4)];
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aOutput[2] = b64_dictionary[(aInput[1]&0x0F)<<2];
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aOutput[3] = '=';
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}
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else if (aInputLen == 1)
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{
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aOutput[0] = b64_dictionary[aInput[0] >> 2];
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aOutput[1] = b64_dictionary[(aInput[0] & 0x3)<<4];
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aOutput[2] = '=';
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aOutput[3] = '=';
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}
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else
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{
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// Break the input into 3-byte chunks and process each of them
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int i;
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for (i = 0; i < aInputLen/3; i++)
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{
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b64_encode(&aInput[i*3], 3, &aOutput[i*4], 4);
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}
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if (aInputLen % 3 > 0)
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{
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// It doesn't fit neatly into a 3-byte chunk, so process what's left
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b64_encode(&aInput[i*3], aInputLen % 3, &aOutput[i*4], aOutputLen - (i*4));
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}
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}
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}
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