datagrampart.cpp

著名的下载软件核心Shareaza

//
// DatagramPart.cpp
//
// Copyright (c) Shareaza Development Team, 2002-2004.
// This file is part of SHAREAZA (www.shareaza.com)
//
// Shareaza is free software; you can redistribute it
// and/or modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2 of
// the License, or (at your option) any later version.
//
// Shareaza is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Shareaza; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
//

#include "StdAfx.h"
#include "Shareaza.h"
#include "Settings.h"
#include "Datagrams.h"
#include "DatagramPart.h"
#include "G2Packet.h"
#include "Buffer.h"

#ifdef _DEBUG
#undef THIS_FILE
static char THIS_FILE[]=__FILE__;
#define new DEBUG_NEW
#endif


//////////////////////////////////////////////////////////////////////
// CDatagramOut construction

CDatagramOut::CDatagramOut()
{
	m_pBuffer	= NULL;
	m_pLocked	= NULL;
	m_nLocked	= 0;
}

CDatagramOut::~CDatagramOut()
{
	if ( m_pLocked ) delete [] m_pLocked;
}

//////////////////////////////////////////////////////////////////////
// CDatagramOut create

void CDatagramOut::Create(SOCKADDR_IN* pHost, CG2Packet* pPacket, WORD nSequence, CBuffer* pBuffer, BOOL bAck)
{
	ASSERT( m_pBuffer == NULL );
	
	m_pHost		= *pHost;
	m_nSequence	= nSequence;
	m_pBuffer	= pBuffer;
	
	pPacket->ToBuffer( m_pBuffer );
	
	m_bCompressed = m_pBuffer->Deflate( TRUE );
	
	m_nPacket	= Settings.Gnutella2.UdpMTU;
	m_nCount	= (BYTE)( ( m_pBuffer->m_nLength + m_nPacket - 1 ) / m_nPacket );
	m_nAcked	= m_nCount;

	SGP_HEADER pHeader;

	strncpy( pHeader.szTag, SGP_TAG_2, 3 );
	pHeader.nFlags = m_bCompressed ? SGP_DEFLATE : 0;
	if ( bAck ) pHeader.nFlags |= SGP_ACKNOWLEDGE;

	pHeader.nSequence	= m_nSequence;
	pHeader.nCount		= m_nCount;

	DWORD nOffset = 0;
	DWORD nPacket = m_nPacket + sizeof(SGP_HEADER);

	for ( BYTE nPart = 0 ; nPart < m_nCount ; nPart++, nOffset += nPacket )
	{
		pHeader.nPart = nPart + 1;
		m_pBuffer->Insert( nOffset, &pHeader, sizeof(pHeader) );
	}

	if ( m_nLocked < m_nCount )
	{
		if ( m_pLocked ) delete [] m_pLocked;
		
		m_nLocked	= m_nCount;
		m_pLocked	= new DWORD[ m_nLocked ];
	}

	ZeroMemory( m_pLocked, sizeof(DWORD) * m_nCount );

	m_tSent = GetTickCount();
}

//////////////////////////////////////////////////////////////////////
// CDatagramOut fragment packet selection

BOOL CDatagramOut::GetPacket(DWORD tNow, BYTE** ppPacket, DWORD* pnPacket, BOOL bResend)
{
	ASSERT( m_pBuffer != NULL );
	
	for ( int nPart = 0 ; nPart < m_nCount ; nPart++ )
	{
		if ( m_pLocked[ nPart ] < 0xFFFFFFFF )
		{
			if ( bResend )
			{
				if ( tNow - m_pLocked[ nPart ] >= Settings.Gnutella2.UdpOutResend ) break;
			}
			else
			{
				if ( m_pLocked[ nPart ] == 0 ) break;
			}
		}
	}
	
	if ( nPart >= m_nCount ) return FALSE;
	
	m_pLocked[ nPart ] = bResend ? tNow : 0xFFFFFFFF;
	
	DWORD nPacket = m_nPacket + sizeof(SGP_HEADER);
	
	*ppPacket = m_pBuffer->m_pBuffer + ( nPart * nPacket );
	*pnPacket = min( nPacket, m_pBuffer->m_nLength - ( nPart * nPacket ) );
	
	return TRUE;
}

//////////////////////////////////////////////////////////////////////
// CDatagramOut fragment acknowledgement

BOOL CDatagramOut::Acknowledge(BYTE nPart)
{
	if ( nPart > 0 && nPart <= m_nCount && m_nAcked > 0 )
	{
		if ( m_pLocked[ nPart - 1 ] < 0xFFFFFFFF )
		{
			m_pLocked[ nPart - 1 ] = 0xFFFFFFFF;

			if ( --m_nAcked == 0 ) return TRUE;
		}
	}
	
	return FALSE;
}