base64str.cpp

email client and support pop3、smtp、imap protocol.

// base64str.cpp - written and placed in the public domain by Wei Dai
// rewritten to single decoding of strings by Thomas Kuiper
#include "stdafx.h"
#include <iostream.h>

#include "base64str.h"

static const int MAX_LINE_LENGTH = 72;

static const unsigned char vec[] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

static const unsigned char padding = '=';


Base64StrDecoder::Base64StrDecoder(char *string)
{
	inBufSize=0;
	bufpos = 0;
	Put((unsigned char*)(string),strlen(string));
	InputFinished();

}

void Base64StrDecoder::DecodeQuantum()
{

	
	if (bufpos == 250) {inBufSize=0;return;}

	unsigned char out;

	out = (unsigned char)((inBuf[0] << 2) | (inBuf[1] >> 4));

	buffer[bufpos] = out;
	bufpos++;

	
	out = (unsigned char)((inBuf[1] << 4) | (inBuf[2] >> 2));
	if (inBufSize > 2) {buffer[bufpos] = out; bufpos++;}

	out = (unsigned char)((inBuf[2] << 6) | inBuf[3]);
	if (inBufSize > 3) {buffer[bufpos] = out; bufpos++;}

	
	inBufSize=0;
}

int Base64StrDecoder::ConvToNumber(unsigned char inByte)
{
	if (inByte >= 'A' && inByte <= 'Z')
		return (inByte - 'A');

	if (inByte >= 'a' && inByte <= 'z')
		return (inByte - 'a' + 26);

	if (inByte >= '0' && inByte <= '9')
		return (inByte - '0' + 52);

	if (inByte == '+')
		return (62);

	if (inByte == '/')
		return (63);

	return (-1);
}

void Base64StrDecoder::Put(unsigned char inByte)
{
	int i=ConvToNumber(inByte);
	if (i >= 0)
		inBuf[inBufSize++]=(unsigned char) i;
	if (inBufSize==4)
		DecodeQuantum();
}

void Base64StrDecoder::Put(const unsigned char* inString, unsigned int len)
{

	while (len--)
		Base64StrDecoder::Put(*inString++);
}

void Base64StrDecoder::InputFinished()
{
	if (inBufSize)
	{
		for (int i=inBufSize;i<4;i++)
			inBuf[i]=0;

		DecodeQuantum();
	}
buffer[bufpos] = '\0';	
}