boolean CTCPConnection::SendSegment (unsigned nFlags, u32 nSequenceNumber, u32 nAcknowledgmentNumber,
const void *pData, unsigned nDataLength)
{
unsigned nDataOffset = 5;
assert (nDataOffset * 4 == sizeof (TTCPHeader));
if (nFlags & TCP_FLAG_SYN)
{
nDataOffset++;
}
unsigned nHeaderLength = nDataOffset * 4;
unsigned nPacketLength = nHeaderLength + nDataLength; // may wrap
assert (nPacketLength >= nHeaderLength);
assert (nHeaderLength <= FRAME_BUFFER_SIZE);
assert (m_pTxBuffer != 0);
TTCPHeader *pHeader = (TTCPHeader *) m_pTxBuffer;
pHeader->nSourcePort = le2be16 (m_nOwnPort);
pHeader->nDestPort = le2be16 (m_nForeignPort);
pHeader->nSequenceNumber = le2be32 (nSequenceNumber);
pHeader->nAcknowledgmentNumber = nFlags & TCP_FLAG_ACK ? le2be32 (nAcknowledgmentNumber) : 0;
pHeader->nDataOffsetFlags = (nDataOffset << TCP_DATA_OFFSET_SHIFT) | nFlags;
pHeader->nWindow = le2be16 (m_nRCV_WND);
pHeader->nUrgentPointer = le2be16 (m_nSND_UP);
if (nFlags & TCP_FLAG_SYN)
{
TTCPOption *pOption = (TTCPOption *) pHeader->Options;
pOption->nKind = TCP_OPTION_MSS;
pOption->nLength = 4;
pOption->Data[0] = TCP_CONFIG_MSS >> 8;
pOption->Data[1] = TCP_CONFIG_MSS & 0xFF;
}
boolean CTCPRejector::SendSegment (unsigned nFlags, u32 nSequenceNumber, u32 nAcknowledgmentNumber)
{
assert (!(nFlags & TCP_FLAG_SYN));
unsigned nDataOffset = 5;
assert (nDataOffset * 4 == sizeof (TTCPHeader));
unsigned nHeaderLength = nDataOffset * 4;
unsigned nPacketLength = nHeaderLength;
assert (nHeaderLength <= FRAME_BUFFER_SIZE);
assert (m_pTxBuffer != 0);
TTCPHeader *pHeader = (TTCPHeader *) m_pTxBuffer;
pHeader->nSourcePort = le2be16 (m_nOwnPort);
pHeader->nDestPort = le2be16 (m_nForeignPort);
pHeader->nSequenceNumber = le2be32 (nSequenceNumber);
pHeader->nAcknowledgmentNumber = nFlags & TCP_FLAG_ACK ? le2be32 (nAcknowledgmentNumber) : 0;
pHeader->nDataOffsetFlags = (nDataOffset << TCP_DATA_OFFSET_SHIFT) | nFlags;
pHeader->nWindow = 0;
pHeader->nUrgentPointer = 0;
pHeader->nChecksum = 0; // must be 0 for calculation
pHeader->nChecksum = m_Checksum.Calculate (m_pTxBuffer, nPacketLength);
#ifdef TCP_DEBUG
CLogger::Get ()->Write (FromTCP, LogDebug,
"tx %c%c%c%c%c%c, seq %u, ack %u, win %u, len %u",
nFlags & TCP_FLAG_URGENT ? 'U' : '-',
nFlags & TCP_FLAG_ACK ? 'A' : '-',
nFlags & TCP_FLAG_PUSH ? 'P' : '-',
nFlags & TCP_FLAG_RESET ? 'R' : '-',
nFlags & TCP_FLAG_SYN ? 'S' : '-',
nFlags & TCP_FLAG_FIN ? 'F' : '-',
nSequenceNumber,
nFlags & TCP_FLAG_ACK ? nAcknowledgmentNumber : 0,
0,
0);
#endif
assert (m_pNetworkLayer != 0);
return m_pNetworkLayer->Send (m_ForeignIP, m_pTxBuffer, nPacketLength, IPPROTO_TCP);
}