En/Decode MIME-Content with MimeSniffer

// DefaultCoder.cpp: implementation of the CDefaultCoder class.
//
//////////////////////////////////////////////////////////////////////

#include "stdafx.h"
#include "DefaultCoder.h"

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

CDefaultCoder::CDefaultCoder()
{

}

CDefaultCoder::~CDefaultCoder()
{

}

void CDefaultCoder::Decode(LPSTREAM pSource, LPSTREAM pDest)
{
	char	buf[4096];
	DWORD	dwRead;
	DWORD	dwPos = 0;
	
	memset(buf, 0, sizeof(buf));

	do
	{
		pSource->Read(buf+dwPos, 1, &dwRead);

		if (dwRead != 1 || buf[dwPos] == 10 || dwPos > (sizeof(buf)-2))
		{
			if (strlen(buf) > 0)
			{
				if (strcmp(buf, "..\r\n") == 0 )
				{
					strcpy(buf, ".\r\n");
				}
				pDest->Write(buf, strlen(buf), NULL);
			}
			memset(buf, 0, sizeof(buf));
			dwPos = 0;
		
			if (dwRead != 1)
				break;
		}
		else
			dwPos++;
	}
	while(true);
}

void CDefaultCoder::Encode(LPSTREAM pSource, LPSTREAM pDest)
{
	BYTE		c;
	DWORD		dwRead;
	char		buf[128];
	DWORD		nBreak = 75;
	int			nState = 0;
	BYTE		nLast;
	DWORD		dwWritten = 0;
	DWORD		dwWrittenWithoutLineFeed = 0;

	memset(buf, 0, sizeof(buf));

	do
	{
		pSource->Read(&c, 1, &dwRead);

		if (dwRead != 1)
		{
			if (strlen(buf) > 0)
			{
				pDest->Write(buf, strlen(buf), NULL);
				dwWritten += strlen(buf);
				nLast = buf[strlen(buf)-1];
			}
			break;
		}
		if (strlen(buf) > 40)
		{
			if (strstr(buf, "\n") != 0)
				dwWrittenWithoutLineFeed = 0;
			else
				dwWrittenWithoutLineFeed += 20;

			if (dwWrittenWithoutLineFeed > nBreak)
			{
				pDest->Write("=\r\n", 3, NULL);	
				dwWrittenWithoutLineFeed = 0;
			}

			pDest->Write(buf, 20, NULL);
			dwWritten += 20;

			memmove(buf, buf+20, sizeof(buf)-20);
		}
	   
		buf[strlen(buf)] = c;

		restate:

		switch(nState)
		{
			case 0:
			{
				if      (c == '\r')
				{
					nState = 1;
					continue;
				}
			}
			break;

			case 1:
			{
				if (c == '\n')
				{
					nState = 2;
					continue;
				}
				else
				{
					nState = 0;
					goto restate;
				}
			}
			break;

			case 2:
			{
				if (c == '.')
				{
					nState = 3;
					continue;
				}
				else
				{
					nState = 0;
					goto restate;
				}
			}
			break;

			case 3:
			{
				if (c == '\r')
				{
					nState = 4;
					continue;
				}
				else
				{
					nState = 0;
					goto restate;
				}
			}
			break;

			case 4:
			{
				if (c == '\n')
				{
					sprintf(buf+strlen(buf)-3, "..\r\n");
				}
				else
				{
					nState = 0;
					goto restate;
				}
			}
			break;

			default:
			{
				ATLASSERT(FALSE);
			}
			break;
		}
		if (strlen(buf) > 0)
		{
			if (strstr(buf, "\n") != 0)
				dwWrittenWithoutLineFeed = 0;
			else
				dwWrittenWithoutLineFeed += strlen(buf);

			if (dwWrittenWithoutLineFeed > nBreak)
			{
				pDest->Write("\r\n", 2, NULL);	
				dwWrittenWithoutLineFeed = 0;
			}

			pDest->Write(buf, strlen(buf), NULL);
			dwWritten += strlen(buf);
			nLast = buf[strlen(buf)-1];
		}
		memset(buf, 0, sizeof(buf));
		nState = 0;
	}
	while(true);

	if (dwWritten > 0 && nLast != 10)
		pDest->Write("\r\n", 2, NULL);
}