DatagramPart.cpp

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//
// DatagramPart.cpp
//
// Copyright (c) Shareaza Development Team, 2002-2005.
// 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 );

    int nPart = 0;
        for ( ; 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;
}

---