base64.cpp

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// Base64.cpp: implementation of the Base64 class.
//
//////////////////////////////////////////////////////////////////////

#include "stdafx.h"
#include "Base64.h"

//////////////////////////////////////////////////////////////////////
// Construction/Destruction
//////////////////////////////////////////////////////////////////////




Base64::Base64()
{
	reslenth = 0;
	memset(this->m_resultbuffer,0,sizeof(m_resultbuffer));
}

Base64::~Base64()
{

}

//编码函数   
bool Base64::EnCode(char *source,int len)
{
	if(source == NULL)
		return false;
	
	char base64_alphabet[] = {'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P', 
	'Q','R','S','T','U','V','W','X','Y','Z','a','b','c','d','e','f', 
	'g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v', 
	'w','x','y','z','0','1','2','3','4','5','6','7','8','9','+','/','='}; 
	
	reslenth  = 0;
	int tmp[4];

	int index = 0;

	for(;index < len;index += 3)
	{
		if(index+2 < len)
		{
			tmp[0] = (source[index]&0xfc) >> 2;
			tmp[1] = ((source[index]&0x03)<<4) + ((source[index+1]&0xf0)>>4);
			tmp[2] = ((source[index+1]&0x0f)<<2) + ((source[index+2]&0xc0)>>6);
			tmp[3] = source[index+2]&0x3f;

		}
		else if(index + 1 < len)
		{
			tmp[0] = (source[index]&0xfc) >> 2;
			tmp[1] = ((source[index]&0x03)<<4) + ((source[index+1]&0xf0)>>4);
			tmp[2] = ((source[index+1]&0x0f)<<2);
			tmp[3] = 64;
		}
		else 
		{
			tmp[0] = (source[index]&0xfc) >> 2;
			tmp[1] = ((source[index]&0x03)<<4);
			tmp[2] = 64;
			tmp[3] = 64;
		}
		for(int i = 0;i < 4;++i)
		{
			if(reslenth + i >= MAX_BASE64_BUFFER)
				return false;
			m_resultbuffer[reslenth + i] = base64_alphabet[tmp[i]];
		}
		reslenth += 4;
	}
	m_resultbuffer[reslenth] = 0;
	return true;
}

int Base64::GetResLengh()
{
	return reslenth;
}


bool Base64::GetRes(char *result, int lenth)
{
	int actlen = reslenth < lenth?reslenth:lenth;
	memcpy(result,m_resultbuffer,sizeof(char)*actlen);
	result[actlen] = 0;
	return true;
}


bool Base64::DeCode(char *source)
{
	if(source == NULL)
		return false;

	char base64_alphabet[] = {'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P', 
	'Q','R','S','T','U','V','W','X','Y','Z','a','b','c','d','e','f', 
	'g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v', 
	'w','x','y','z','0','1','2','3','4','5','6','7','8','9','+','/','='}; 
	
	int index,i,table[256];
	int lenth = strlen(source);
	char tmp[4];

	memset(table,0,sizeof(table));
	for(i = 0;i <= 64;++i)
		table[base64_alphabet[i]] = i;
	reslenth = 0;

	for(index = 0;index < lenth;index+=4)
	{
		if(source[index+2] == '=')
		{
			tmp[0] = ((table[source[index]]&0x3f)<<2)+((table[source[index+1]]&0x30)>>4);
			tmp[1] = 0;
			tmp[2] = 0;
		}
		else if(source[index+3] == '=')
		{
			tmp[0] = ((table[source[index]]&0x3f)<<2)+((table[source[index+1]]&0x30)>>4);
			tmp[1] = ((table[source[index+1]]&0x0f)<<4) + ((table[source[index+2]]&0x3c)>>2);
			tmp[2] = 0;
		}
		else
		{
			tmp[0] = ((table[source[index]]&0x3f)<<2)+((table[source[index+1]]&0x30)>>4);
			tmp[1] = ((table[source[index+1]]&0x0f)<<4) + ((table[source[index+2]]&0x3c)>>2);
			tmp[2] = ((table[source[index+2]]&0x03)<<6) + ((table[source[index+3]]&0x3f));
		}
		for(i = 0;i<3&&tmp[i]!=0;++i)
		{
			if(reslenth >= MAX_BASE64_BUFFER)
				return false;
			m_resultbuffer[reslenth++] = tmp[i];
		}
	}
	return true;
}