debug (5f9cdf29) · Commits · jan.koester / libnetplus

debian/changelog

+14 −0

Original line number	Diff line number	Diff line
		libnetplus (20260504+5) unstable; urgency=medium

		* QUIC: fix critical data-loss bug in loss-detection retransmit — if
		sendPacket() failed (EAGAIN / send-buffer full after a burst), the
		stream data was erased from _sent_packets but never re-inserted,
		causing permanent loss of ~47 in-flight packets. Fix: on send
		failure, re-queue under the original PN so the next loss-detection
		cycle retries the retransmit.
		* QUIC: fix same data-loss bug in PTO retransmit path — only erase
		the original entry and increment _pto_count after sendPacket()
		succeeds; re-queue on failure.
		* QUIC: improve [QUIC-DIAG] retransmit logging — report retransmit_ok
		/ retransmit_fail counts and PTO re-queue events

		libnetplus (20260504+4) unstable; urgency=medium

		* QUIC: add client-side [QUIC-DIAG] logging for ACK processing (first

src/quic.cpp

+28 −17

Original line number	Diff line number	Diff line
		@@ -3661,8 +3661,8 @@ void quic::checkLossAndRetransmit() {
		if (age >= pto_thresh) {
		// Retransmit the oldest unacked packet as a probe
		auto sp = oldest; // copy — will be erased below
		uint64_t old_pn = _sent_packets.begin()->first;
		_sent_packets.erase(_sent_packets.begin());
		++_pto_count;

		if (sp.data_length > 0 \|\| sp.fin) {
		uint8_t frame_type = 0x08 \| 0x02;
		@@ -3689,14 +3689,16 @@ void quic::checkLossAndRetransmit() {
		recordSentPacket(new_pn, sp.stream_id, sp.stream_offset,
		sp.stream_data.data(), sp.stream_data.size(),
		sp.fin, packet.size());
		++_pto_count;
		} else {
		// Send failed (EAGAIN) — re-queue under original PN
		// so the data is not permanently lost
		_sent_packets[old_pn] = std::move(sp);
		std::cerr << "[QUIC-DIAG] PTO send failed, re-queued pn="
		<< old_pn << "\n";
		}
		QUIC_DBG("PTO probe: new_pn=%lu age=%.3fs pto=%.3fs",
		(unsigned long)new_pn, age, pto_thresh);
		std::cerr << "[QUIC-DIAG] PTO probe: age=" << age
		<< "s pto=" << pto_thresh
		<< "s sent_packets=" << _sent_packets.size()
		<< " largest_acked=" << _largest_acked_pn
		<< "\n";
		}
		}
		}
		@@ -3744,12 +3746,7 @@ void quic::checkLossAndRetransmit() {
		}

		// Retransmit lost stream data with new packet numbers
		if (!lost.empty()) {
		std::cerr << "[QUIC-DIAG] loss detected: " << lost.size()
		<< " packets, largest_acked=" << _largest_acked_pn
		<< " sent_packets_remaining=" << _sent_packets.size()
		<< "\n";
		}
		size_t retransmit_ok = 0, retransmit_fail = 0;
		for (auto& sp : lost) {
		if (sp.data_length == 0 && !sp.fin) continue;

		@@ -3784,9 +3781,6 @@ void quic::checkLossAndRetransmit() {

		ssize_t sent = sendPacket(packet.data(), packet.size());
		if (sent < 0) {
		// Single non-blocking retry — do not sleep with quic_mtx held.
		// If the socket is still busy the packet will be retransmitted
		// on the next loss-detection cycle.
		sent = sendPacket(packet.data(), packet.size());
		}

		@@ -3794,12 +3788,29 @@ void quic::checkLossAndRetransmit() {
		// Track retransmitted packet under new PN
		recordSentPacket(new_pn, sp.stream_id, sp.stream_offset,
		sp.stream_data.data(), sp.stream_data.size(), sp.fin, packet.size());
		++retransmit_ok;
		} else {
		// Send failed (EAGAIN / send-buffer full) — re-insert under
		// the original PN so the packet is retried on the next
		// loss-detection cycle instead of being permanently lost.
		size_t saved_size = sp.sent_size;
		_sent_packets[sp.pn] = std::move(sp);
		_bytes_in_flight += saved_size;
		++retransmit_fail;
		}

		QUIC_DBG("RETRANSMIT: old_pn=%lu new_pn=%lu sid=%lu off=%lu len=%zu fin=%d",
		QUIC_DBG("RETRANSMIT: old_pn=%lu new_pn=%lu sid=%lu off=%lu len=%zu fin=%d sent=%zd",
		(unsigned long)sp.pn, (unsigned long)new_pn,
		(unsigned long)sp.stream_id, (unsigned long)sp.stream_offset,
		sp.data_length, (int)sp.fin);
		sp.data_length, (int)sp.fin, sent);
		}
		if (!lost.empty()) {
		std::cerr << "[QUIC-DIAG] loss detected: " << lost.size()
		<< " packets, largest_acked=" << _largest_acked_pn
		<< " retransmit_ok=" << retransmit_ok
		<< " retransmit_fail=" << retransmit_fail
		<< " sent_packets=" << _sent_packets.size()
		<< "\n";
		}
		}