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[core] Fix extraction seq with scheduling seq in group. (#2258)
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Fixed SND Drop Request: set the message number to zero.
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@gou4shi1
gou4shi1 committed Mar 16, 2022
1 parent 3975428 commit 024e9c0
Showing 1 changed file with 61 additions and 45 deletions.
106 changes: 61 additions & 45 deletions srtcore/core.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -9532,65 +9532,81 @@ bool srt::CUDT::packUniqueData(CPacket& w_packet, time_point& w_origintime)

// A CHANGE. The sequence number is currently added to the packet
// when scheduling, not when extracting. This is a inter-migration form,
// so still override the value, but trace it.
// only override extraction sequence with scheduling sequence in group mode.
m_iSndCurrSeqNo = CSeqNo::incseq(m_iSndCurrSeqNo);

// Do this checking only for groups and only at the very first moment,
// when there's still nothing in the buffer. Otherwise there will be
// a serious data discrepancy between the agent and the peer.
// After increasing by 1, but being previously set as ISN-1, this should be == ISN,
// if this is the very first packet to send.
#if ENABLE_EXPERIMENTAL_BONDING
// Fortunately here is only the procedure that verifies if the extraction
// sequence is moved due to the difference between ISN caught during the existing
// transmission and the first sequence possible to be used at the first sending
// instruction. The group itself isn't being accessed.
if (m_parent->m_GroupOf && m_iSndCurrSeqNo != w_packet.m_iSeqNo && m_iSndCurrSeqNo == m_iISN)
{
const int packetspan = CSeqNo::seqcmp(w_packet.m_iSeqNo, m_iSndCurrSeqNo);

HLOGC(qslog.Debug, log << CONID() << "packData: Fixing EXTRACTION sequence " << m_iSndCurrSeqNo
<< " from SCHEDULING sequence " << w_packet.m_iSeqNo
<< " DIFF: " << packetspan << " STAMP:" << BufferStamp(w_packet.m_pcData, w_packet.getLength()));

// This is the very first packet to be sent; so there's nothing in
// the sending buffer yet, and therefore we are in a situation as just
// after connection. No packets in the buffer, no packets are sent,
// no ACK to be awaited. We can screw up all the variables that are
// initialized from ISN just after connection.
//
// Additionally send the drop request to the peer so that it
// won't stupidly request the packets to be retransmitted.
// Don't do it if the difference isn't positive or exceeds the threshold.
// Fortunately the group itself isn't being accessed.
if (m_parent->m_GroupOf)
{
const int packetspan = CSeqNo::seqoff(m_iSndCurrSeqNo, w_packet.m_iSeqNo);
if (packetspan > 0)
{
int32_t seqpair[2];
seqpair[0] = m_iSndCurrSeqNo;
seqpair[1] = w_packet.m_iSeqNo;
HLOGC(qslog.Debug, log << "... sending INITIAL DROP (ISN FIX): "
<< "msg=" << MSGNO_SEQ::unwrap(w_packet.m_iMsgNo) << " SEQ:"
<< seqpair[0] << " - " << seqpair[1] << "(" << packetspan << " packets)");
sendCtrl(UMSG_DROPREQ, &w_packet.m_iMsgNo, seqpair, sizeof(seqpair));
// After increasing by 1, but being previously set as ISN-1, this should be == ISN,
// if this is the very first packet to send.
if (m_iSndCurrSeqNo == m_iISN)
{
// This is the very first packet to be sent; so there's nothing in
// the sending buffer yet, and therefore we are in a situation as just
// after connection. No packets in the buffer, no packets are sent,
// no ACK to be awaited. We can screw up all the variables that are
// initialized from ISN just after connection.
LOGC(qslog.Note,
log << CONID() << "packData: Fixing EXTRACTION sequence " << m_iSndCurrSeqNo
<< " from SCHEDULING sequence " << w_packet.m_iSeqNo << " for the first packet: DIFF="
<< packetspan << " STAMP=" << BufferStamp(w_packet.m_pcData, w_packet.getLength()));
}
else
{
// There will be a serious data discrepancy between the agent and the peer.
LOGC(qslog.Error,
log << CONID() << "IPE: packData: Fixing EXTRACTION sequence " << m_iSndCurrSeqNo
<< " from SCHEDULING sequence " << w_packet.m_iSeqNo << " in the middle of transition: DIFF="
<< packetspan << " STAMP=" << BufferStamp(w_packet.m_pcData, w_packet.getLength()));
}

// Additionally send the drop request to the peer so that it
// won't stupidly request the packets to be retransmitted.
// Don't do it if the difference isn't positive or exceeds the threshold.
int32_t seqpair[2];
seqpair[0] = m_iSndCurrSeqNo;
seqpair[1] = CSeqNo::decseq(w_packet.m_iSeqNo);
const int32_t no_msgno = 0;
LOGC(qslog.Debug,
log << CONID() << "packData: Sending DROPREQ: SEQ: " << seqpair[0] << " - " << seqpair[1] << " ("
<< packetspan << " packets)");
sendCtrl(UMSG_DROPREQ, &no_msgno, seqpair, sizeof(seqpair));
// In case when this message is lost, the peer will still get the
// UMSG_DROPREQ message when the agent realizes that the requested
// packet are not present in the buffer (preadte the send buffer).

// Override extraction sequence with scheduling sequence.
m_iSndCurrSeqNo = w_packet.m_iSeqNo;
ScopedLock ackguard(m_RecvAckLock);
m_iSndLastAck = w_packet.m_iSeqNo;
m_iSndLastDataAck = w_packet.m_iSeqNo;
m_iSndLastFullAck = w_packet.m_iSeqNo;
m_iSndLastAck2 = w_packet.m_iSeqNo;
}
else if (packetspan < 0)
{
LOGC(qslog.Error,
log << CONID() << "IPE: packData: SCHEDULING sequence " << w_packet.m_iSeqNo
<< " is behind of EXTRACTION sequence " << m_iSndCurrSeqNo << ", dropping this packet: DIFF="
<< packetspan << " STAMP=" << BufferStamp(w_packet.m_pcData, w_packet.getLength()));
// XXX: Probably also change the socket state to broken?
return false;
}
}
else
#endif
{
HLOGC(qslog.Debug, log << CONID() << "packData: Applying EXTRACTION sequence " << m_iSndCurrSeqNo
<< " over SCHEDULING sequence " << w_packet.m_iSeqNo
<< " DIFF: " << CSeqNo::seqcmp(m_iSndCurrSeqNo, w_packet.m_iSeqNo)
<< " STAMP:" << BufferStamp(w_packet.m_pcData, w_packet.getLength()));

#if ENABLE_EXPERIMENTAL_BONDING
HLOGC(qslog.Debug, log << "... CONDITION: IN GROUP: " << (m_parent->m_GroupOf ? "yes":"no")
<< " extraction-seq=" << m_iSndCurrSeqNo << " scheduling-seq=" << w_packet.m_iSeqNo << " ISN=" << m_iISN);
#endif

// Do this always when not in a group,
HLOGC(qslog.Debug,
log << CONID() << "packData: Applying EXTRACTION sequence " << m_iSndCurrSeqNo
<< " over SCHEDULING sequence " << w_packet.m_iSeqNo << " for socket not in group:"
<< " DIFF=" << CSeqNo::seqcmp(m_iSndCurrSeqNo, w_packet.m_iSeqNo)
<< " STAMP=" << BufferStamp(w_packet.m_pcData, w_packet.getLength()));
// Do this always when not in a group.
w_packet.m_iSeqNo = m_iSndCurrSeqNo;
}

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