C++ PacketBuffer::getBufferSize方法代码示例

/**
    Reads data and returns a pointer to a new PacketBuffer object. You are responsible for
    deleting the returned packet when you are finished with it.

    You are gerented to receive a full PacketBuffer object.

    When data is read in, some verification is done to ensure that the packet header is
    valid. There is no way to validate the buffer portion of the packet. A test is done
    on the header to see if the cookie (just a constant value passed all the time) and
    to see the the command looks like it might be valid. There is no way to tell other then
    if the command is zero (PacketBuffer::pcInvalid). Note that a common problem with getting
    PacketBuffer::pcInvalid as a command is not setting the command in a packet before sending
    it.

    If a packet is sent with a size greater then 3000 bytes, the read operation will
    reset the internal buffer, and throw an exception. This is done to prevent bogus packets
    overflowing the buffer.

    \throw SocketInstanceException  If there is a read error, or a connection was closed.
    \throw BufferedSocketException          If a bad packet was read.
**/
PacketBuffer* BufferedSocket::recvPacket()
{
    PacketBuffer* pPacket = readFullPacket();

    if(pPacket->cookie()!=PacketBuffer::pkCookie || pPacket->getCmd()==PacketBuffer::pcInvalid)
    {
#ifdef DEBUG
        logs::dump(pPacket,PacketBuffer::getHeaderSize());
        logs::dump(pPacket->m_Buffer,pPacket->getBufferSize());
#endif
        resetBuffer();
        CStr msg;
        msg.format("bad packet received %s",
                   pPacket->getCmd() ? "(invalid command)":"(invalid cookie)");
        throwBufferedSocketException(msg);
    }

    return pPacket;
}

//
//We do two checks  to see that we have enough data to make
//a full packet. One check is to see that we have enough data
//the make a header. The second is to see if there is enough
//to make a packet with a header plus it's data.
//We return NULL if there wasn't
//enough data to make a full packet. If there is enough data
//we return _one_ complete packet, and make sure the buffer
//is ready to extract more packets, and recieve additional
//data.
//
//A full packet is the size of the packet header (all packets
//_must_ have full header, plus the size of any data. There
//doesn't always have to be any data with the packet.
//
PacketBuffer* BufferedSocket::parsForPacket()
{
    PacketBuffer* pPacket = NULL;
    char* phead = m_pbuffer;
    char* ptail = phead+m_nBytesInBuf;
    unsigned32 nSize;

    if(m_nBytesInBuf<PacketBuffer::getHeaderSize())
        return NULL;

    nSize = ntohl(*(unsigned32*)phead)+PacketBuffer::getHeaderSize();
    if((unsigned32)(ptail-phead) < nSize)
        return NULL;

    //copy in the header, then copy in packet data, less the header data
    pPacket = new PacketBuffer(0,nSize-PacketBuffer::getHeaderSize());    //new packet
    memcpy(pPacket->getHeader(),phead,PacketBuffer::getHeaderSize());
    pPacket->makeHostReady(true);       //convert header from network byte order
    if(nSize>PacketBuffer::getHeaderSize()) //if we have data after the header
        memcpy(pPacket->getBuffer(),phead+PacketBuffer::getHeaderSize(),pPacket->getBufferSize());

    phead += nSize;
    m_nBytesInBuf -= nSize;

    if(phead>=ptail)
    {
        //there is no more data in the buffer
        m_ptr = m_pbuffer;
        m_nBytesInBuf = 0;
    }
    else
    {
        //we need to move the unparsed data to the beginning of the buffer
        memmove(m_pbuffer,phead,m_nBytesInBuf);
        m_ptr = m_pbuffer+m_nBytesInBuf;
    }

    return pPacket;
}