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tcp: Emulate SACK for SACKless connections in TcpSocketBase

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This commit is contained in:
Natale Patriciello
2017-02-03 14:02:11 +01:00
parent d85c1e3c89
commit a968aeabb8
1 changed files with 20 additions and 0 deletions
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20
src/internet/model/tcp-socket-base.cc
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@@ -1305,6 +1305,26 @@ TcpSocketBase::DoForwardUp (Ptr<Packet> packet, const Address &fromAddress,
EstimateRtt (tcpHeader);
UpdateWindowSize (tcpHeader);
if (!m_sackEnabled
&& m_tcb->m_congState != TcpSocketState::CA_LOSS
&& !m_persistEvent.IsRunning ())
{
// Emulate SACK for (old) dupack definition.
// Don't generate block for the persistent window probe
// Don't include the ACK number in any SACK block
if (tcpHeader.GetAckNumber () == m_txBuffer->HeadSequence ()
&& tcpHeader.GetAckNumber () < m_tcb->m_nextTxSequence)
{
// Dupack following old ns-3 behavior. Craft a special SACK option.
uint8_t available = tcpHeader.GetMaxOptionLength () - tcpHeader.GetOptionLength ();
Ptr<const TcpOptionSack> sackBlock = m_txBuffer->CraftSackOption (tcpHeader.GetAckNumber (), available);
if (sackBlock != 0)
{
tcpHeader.AppendOption (sackBlock);
}
}
}
}