Fix segfault and assert fail

A segfault occured at quic connection close, when _quic_session was
reset, but packets where still comming.
An assert fail occured when receive_data was called on a close()'d quic
session.
Some extraneous prints removed.

flame/quicsession.cpp

@@ -91,7 +91,8 @@ void QUICSession::close()
 void QUICSession::receive_data(const char data[], size_t len, const uvw::Addr *src_addr)
 {
  size_t off = 0;
- assert(q_conn);
+ if (!q_conn)
+ return;
 
  /* split UDP datagram into multiple QUIC packets */
  while (off < len) {
@@ -226,11 +227,7 @@ void QUICSession::q_on_closed_by_remote(quicly_closed_by_remote_t *self, quicly_
  ";frame=" << PRIu64 << frame_type << ";reason=" << std::string(reason, reason_len) << std::endl;
  }
  } else if (QUICLY_ERROR_IS_QUIC_APPLICATION(err)) {
- std::cerr << "application close:code=0" << PRIx16 << QUICLY_ERROR_GET_ERROR_CODE(err) <<
- ";reason=" << std::string(reason, reason_len) << std::endl;
  } else if (err == QUICLY_ERROR_RECEIVED_STATELESS_RESET) {
- std::cerr << "stateless reset" << std::endl;
- } else if (err == QUICLY_ERROR_NO_COMPATIBLE_VERSION) {
  std::cerr << "no compatible version" << std::endl;
  } else {
  std::cerr << "unexpected close:code=" << PRIu16 << err << std::endl;

flame/quicsession.h

@@ -44,6 +44,10 @@ class QUICSession {
  quicly_cid_plaintext_t cid);
  virtual ~QUICSession();
 
+ /*
+ * Close the session and the underlying connection.
+ * Depending on the state of the session, the close will be graceful or abrut
+ */
  virtual void close();
  virtual void receive_data(const char data[], size_t len, const uvw::Addr *src_addr);
  /*

flame/trafgen.cpp

@@ -421,7 +421,8 @@ void TrafGen::start_quic()
  _metrics->trafgen_id(_udp_handle->sock().port);
 
  _udp_handle->on<uvw::UDPDataEvent>([this](const uvw::UDPDataEvent &event, uvw::UDPHandle &h) {
- _quic_session->receive_data(event.data.get(), event.length, &event.sender);
+ if (_quic_session)
+ _quic_session->receive_data(event.data.get(), event.length, &event.sender);
  });
 
  _udp_handle->recv();
@@ -478,14 +479,14 @@ void TrafGen::start()
 #ifdef QUIC_ENABLE
  else if (_traf_config->protocol == Protocol::QUIC) {
  _shutdown_timer->on<uvw::TimerEvent>([this](auto &, auto &) {
+ if (_udp_handle.get())
+ _udp_handle->stop();
  if (_quic_session.get())
  _quic_session->close();
 
  _timeout_timer->stop();
- if (_udp_handle.get()) {
- _udp_handle->stop();
+ if (_udp_handle.get())
  _udp_handle->close();
- }
  _timeout_timer->close();
  _shutdown_timer->close();
  this->handle_timeouts();