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quic: fixup closing/draining period timing
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When entering the closing or draining periods, servers should wait
three times the current probe timeout before releasing session
state.

PR-URL: #34283
Reviewed-By: Anna Henningsen <[email protected]>
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@jasnell
jasnell committed Jul 16, 2020
1 parent ed48822 commit 4523d4a
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Showing 3 changed files with 84 additions and 85 deletions.
8 changes: 6 additions & 2 deletions src/quic/node_quic_session-inl.h
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Original file line number Diff line number Diff line change
Expand Up @@ -344,9 +344,13 @@ void QuicSession::InitApplication() {
// the peer. All existing streams are abandoned and closed.
void QuicSession::OnIdleTimeout() {
if (!is_destroyed()) {
if (state_->idle_timeout == 1) {
Debug(this, "Idle timeout");
Close(QuicSessionListener::SESSION_CLOSE_FLAG_SILENT);
return;
}
state_->idle_timeout = 1;
Debug(this, "Idle timeout");
Close(QuicSessionListener::SESSION_CLOSE_FLAG_SILENT);
UpdateClosingTimer();
}
}

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156 changes: 74 additions & 82 deletions src/quic/node_quic_session.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -1633,7 +1633,8 @@ BaseObjectPtr<QuicStream> QuicSession::CreateStream(int64_t stream_id) {

// Initiate a shutdown of the QuicSession.
void QuicSession::Close(int close_flags) {
CHECK(!is_destroyed());
if (is_destroyed())
return;
bool silent = close_flags & QuicSessionListener::SESSION_CLOSE_FLAG_SILENT;
bool stateless_reset = is_stateless_reset();

Expand Down Expand Up @@ -1735,13 +1736,16 @@ bool QuicSession::GetNewConnectionID(
}

void QuicSession::HandleError() {
if (is_destroyed() || (is_in_closing_period() && !is_server()))
if (is_destroyed())
return;

if (!SendConnectionClose()) {
set_last_error(QUIC_ERROR_SESSION, NGTCP2_ERR_INTERNAL);
Close();
}
// If the QuicSession is a server, send a CONNECTION_CLOSE. In either
// case, the closing timer will be set and the QuicSession will be
// destroyed.
if (is_server())
SendConnectionClose();
else
UpdateClosingTimer();
}

// The the retransmit libuv timer fires, it will call MaybeTimeout,
Expand All @@ -1751,20 +1755,25 @@ void QuicSession::MaybeTimeout() {
if (is_destroyed())
return;
uint64_t now = uv_hrtime();
bool transmit = false;

if (ngtcp2_conn_loss_detection_expiry(connection()) <= now) {
Debug(this, "Retransmitting due to loss detection");
CHECK_EQ(ngtcp2_conn_on_loss_detection_timer(connection(), now), 0);
IncrementStat(&QuicSessionStats::loss_retransmit_count);
transmit = true;
} else if (ngtcp2_conn_ack_delay_expiry(connection()) <= now) {
}

if (ngtcp2_conn_ack_delay_expiry(connection()) <= now) {
Debug(this, "Retransmitting due to ack delay");
ngtcp2_conn_cancel_expired_ack_delay_timer(connection(), now);
IncrementStat(&QuicSessionStats::ack_delay_retransmit_count);
transmit = true;
}
if (transmit)
SendPendingData();

int rv = ngtcp2_conn_handle_expiry(connection(), now);
if (rv != 0) {
Debug(this, "Error handling retransmit timeout: %s", ngtcp2_strerror(rv));
set_last_error(QUIC_ERROR_SESSION, rv);
HandleError();
}

SendPendingData();
}

bool QuicSession::OpenBidirectionalStream(int64_t* stream_id) {
Expand Down Expand Up @@ -1847,16 +1856,7 @@ bool QuicSession::Receive(
Debug(this, "Receiving QUIC packet");
IncrementStat(&QuicSessionStats::bytes_received, nread);

// Closing period starts once ngtcp2 has detected that the session
// is being shutdown locally. Note that this is different that the
// is_graceful_closing() function, which
// indicates a graceful shutdown that allows the session and streams
// to finish naturally. When is_in_closing_period is true, ngtcp2 is
// actively in the process of shutting down the connection and a
// CONNECTION_CLOSE has already been sent. The only thing we can do
// at this point is either ignore the packet or send another
// CONNECTION_CLOSE.
if (is_in_closing_period()) {
if (is_in_closing_period() && is_server()) {
Debug(this, "QUIC packet received while in closing period");
IncrementConnectionCloseAttempts();
// For server QuicSession instances, we serialize the connection close
Expand All @@ -1866,30 +1866,13 @@ bool QuicSession::Receive(
// every received packet, however, so we use an exponential
// backoff, increasing the ratio of packets received to connection
// close frame sent with every one we send.
if (!ShouldAttemptConnectionClose()) {
Debug(this, "Not sending connection close");
if (UNLIKELY(ShouldAttemptConnectionClose() &&
!SendConnectionClose())) {
Debug(this, "Failure trying to send another connection close");
return false;
}
Debug(this, "Sending connection close");
return SendConnectionClose();
}

// When is_in_draining_period is true, ngtcp2 has received a
// connection close and we are simply discarding received packets.
// No outbound packets may be sent. Return true here because
// the packet was correctly processed, even tho it is being
// ignored.
if (is_in_draining_period()) {
Debug(this, "QUIC packet received while in draining period");
return true;
}

// It's possible for the remote address to change from one
// packet to the next so we have to look at the addr on
// every packet.
remote_address_ = remote_addr;
QuicPath path(local_addr, remote_address_);

{
// These are within a scope to ensure that the InternalCallbackScope
// and HandleScope are both exited before continuing on with the
Expand All @@ -1901,38 +1884,28 @@ bool QuicSession::Receive(
Debug(this, "Processing received packet");
HandleScope handle_scope(env()->isolate());
InternalCallbackScope callback_scope(this);
remote_address_ = remote_addr;
QuicPath path(local_addr, remote_address_);
if (!ReceivePacket(&path, data, nread)) {
Debug(this, "Failure processing received packet (code %" PRIu64 ")",
last_error().code);
HandleError();
return false;
}
}

if (is_destroyed()) {
Debug(this, "Session was destroyed while processing the received packet");
// If the QuicSession has been destroyed but it is not
// in the closing period, a CONNECTION_CLOSE has not yet
// been sent to the peer. Let's attempt to send one.
if (!is_in_closing_period() && !is_in_draining_period()) {
set_last_error();
SendConnectionClose();
}
return true;
}

// Only send pending data if we haven't entered draining mode.
// We enter the draining period when a CONNECTION_CLOSE has been
// received from the remote peer.
if (is_in_draining_period()) {
Debug(this, "In draining period after processing packet");
// If processing the packet puts us into draining period, there's
// absolutely nothing left for us to do except silently close
// and destroy this QuicSession.
// and destroy this QuicSession, which we do by updating the
// closing timer.
GetConnectionCloseInfo();
Close(QuicSessionListener::SESSION_CLOSE_FLAG_SILENT);
UpdateClosingTimer();
return true;
}

Debug(this, "Sending pending data after processing packet");
SendPendingData();
UpdateIdleTimer();
Expand Down Expand Up @@ -1965,20 +1938,32 @@ bool QuicSession::ReceivePacket(
case NGTCP2_ERR_DRAINING:
case NGTCP2_ERR_RECV_VERSION_NEGOTIATION:
break;
case NGTCP2_ERR_RETRY:
// This should only ever happen on the server
CHECK(is_server());
socket()->SendRetry(scid_, dcid_, local_address_, remote_address_);
Close(QuicSessionListener::SESSION_CLOSE_FLAG_SILENT);
break;
case NGTCP2_ERR_DROP_CONN:
Close(QuicSessionListener::SESSION_CLOSE_FLAG_SILENT);
break;
default:
// Per ngtcp2: If NGTCP2_ERR_RETRY is returned,
// QuicSession must be a server and must perform
// address validation by sending a Retry packet
// then immediately close the connection.
if (err == NGTCP2_ERR_RETRY && is_server()) {
socket()->SendRetry(scid_, dcid_, local_address_, remote_address_);
Close(QuicSessionListener::SESSION_CLOSE_FLAG_SILENT);
break;
}
set_last_error(QUIC_ERROR_SESSION, err);
return false;
}
}

if (is_destroyed()) {
Debug(this, "Session was destroyed while processing the received packet");
// If the QuicSession has been destroyed but it is not
// in the closing period, a CONNECTION_CLOSE has not yet
// been sent to the peer. Let's attempt to send one. This
// will have the effect of setting the idle timer to the
// closing/draining period, after which the QuicSession
// will be destroyed.
return is_in_closing_period() ? true : SendConnectionClose();
}

return true;
}

Expand Down Expand Up @@ -2121,6 +2106,9 @@ bool QuicSession::SendConnectionClose() {
Debug(this, "Connection Close code: %" PRIu64 " (family: %s)",
error.code, error.family_name());

Debug(this, "Setting the connection/draining period timer");
UpdateClosingTimer();

// If initial keys have not yet been installed, use the alternative
// ImmediateConnectionClose to send a stateless connection close to
// the peer.
Expand All @@ -2135,11 +2123,12 @@ bool QuicSession::SendConnectionClose() {
return true;
}

UpdateIdleTimer();
switch (crypto_context_->side()) {
case NGTCP2_CRYPTO_SIDE_SERVER: {
if (!is_in_closing_period() && !StartClosingPeriod())
if (!is_in_closing_period() && !StartClosingPeriod()) {
Close(QuicSessionListener::SESSION_CLOSE_FLAG_SILENT);
return false;
}
CHECK_GT(conn_closebuf_->length(), 0);
return SendPacket(QuicPacket::Copy(conn_closebuf_));
}
Expand All @@ -2157,6 +2146,7 @@ bool QuicSession::SendConnectionClose() {
if (UNLIKELY(nwrite < 0)) {
Debug(this, "Error writing connection close: %d", nwrite);
set_last_error(QUIC_ERROR_SESSION, static_cast<int>(nwrite));
Close(QuicSessionListener::SESSION_CLOSE_FLAG_SILENT);
return false;
}
packet->set_length(nwrite);
Expand Down Expand Up @@ -2330,16 +2320,12 @@ bool QuicSession::StartClosingPeriod() {
if (is_in_closing_period())
return true;

StopRetransmitTimer();
UpdateIdleTimer();

QuicError error = last_error();
Debug(this, "Closing period has started. Error %d", error.code);

// Once the CONNECTION_CLOSE packet is written,
// is_in_closing_period will return true.
conn_closebuf_ = QuicPacket::Create(
"server connection close");
conn_closebuf_ = QuicPacket::Create("server connection close");
ssize_t nwrite =
SelectCloseFn(error.family)(
connection(),
Expand All @@ -2349,12 +2335,7 @@ bool QuicSession::StartClosingPeriod() {
error.code,
uv_hrtime());
if (nwrite < 0) {
if (nwrite == NGTCP2_ERR_PKT_NUM_EXHAUSTED) {
set_last_error(QUIC_ERROR_SESSION, NGTCP2_ERR_PKT_NUM_EXHAUSTED);
Close(QuicSessionListener::SESSION_CLOSE_FLAG_SILENT);
} else {
set_last_error(QUIC_ERROR_SESSION, static_cast<int>(nwrite));
}
set_last_error(QUIC_ERROR_SESSION, static_cast<int>(nwrite));
return false;
}
conn_closebuf_->set_length(nwrite);
Expand Down Expand Up @@ -2450,6 +2431,8 @@ void QuicSession::UpdateConnectionID(
// will be silently closed. It is important to update this as activity
// occurs to keep the idle timer from firing.
void QuicSession::UpdateIdleTimer() {
if (is_closing_timer_enabled())
return;
uint64_t now = uv_hrtime();
uint64_t expiry = ngtcp2_conn_get_idle_expiry(connection());
// nano to millis
Expand All @@ -2459,6 +2442,15 @@ void QuicSession::UpdateIdleTimer() {
idle_.Update(timeout, timeout);
}

void QuicSession::UpdateClosingTimer() {
set_closing_timer_enabled(true);
uint64_t timeout =
is_server() ? (ngtcp2_conn_get_pto(connection()) / 1000000ULL) * 3 : 0;
Debug(this, "Setting closing timeout to %" PRIu64, timeout);
retransmit_.Stop();
idle_.Update(timeout, 0);
idle_.Ref();
}

// Write any packets current pending for the ngtcp2 connection based on
// the current state of the QuicSession. If the QuicSession is in the
Expand Down
5 changes: 4 additions & 1 deletion src/quic/node_quic_session.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -696,7 +696,8 @@ class QuicApplication : public MemoryRetainer,
V(NGTCP2_CALLBACK, in_ngtcp2_callback) \
V(CONNECTION_CLOSE_SCOPE, in_connection_close_scope) \
V(SILENT_CLOSE, silent_closing) \
V(STATELESS_RESET, stateless_reset)
V(STATELESS_RESET, stateless_reset) \
V(CLOSING_TIMER_ENABLED, closing_timer_enabled)

// QUIC sessions are logical connections that exchange data
// back and forth between peer endpoints via UDP. Every QuicSession
Expand Down Expand Up @@ -1403,6 +1404,8 @@ class QuicSession final : public AsyncWrap,

void UpdateIdleTimer();

void UpdateClosingTimer();

inline void UpdateRetransmitTimer(uint64_t timeout);

inline void StopRetransmitTimer();
Expand Down

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