Add a new QUIC connection option, 5RTO, which closes the QUIC connection after 5 consecutive RTOs. …

net/quic/quic_connection.cc

Index: net/quic/quic_connection.cc
diff --git a/net/quic/quic_connection.cc b/net/quic/quic_connection.cc
index 3e807a35281453173730faff0259dea8612d4b5d..afd5e50e4e401d832fcc311d610e09f3305b5e8b 100644
--- a/net/quic/quic_connection.cc
+++ b/net/quic/quic_connection.cc
@@ -235,6 +235,7 @@ QuicConnection::QuicConnection(QuicConnectionId connection_id,
       pending_version_negotiation_packet_(false),
       save_crypto_packets_as_termination_packets_(false),
       silent_close_enabled_(false),
+      close_connection_after_five_rtos_(false),
       received_packet_manager_(&stats_),
       ack_queued_(false),
       num_retransmittable_packets_received_since_last_ack_sent_(0),
@@ -370,6 +371,10 @@ void QuicConnection::SetFromConfig(const QuicConfig& config) {
       config.HasClientSentConnectionOption(kAKD2, perspective_)) {
     ack_mode_ = ACK_DECIMATION_WITH_REORDERING;
   }
+  if (FLAGS_quic_enable_rto_timeout &&
+      config.HasClientSentConnectionOption(k5RTO, perspective_)) {
+    close_connection_after_five_rtos_ = true;
+  }
 }
 
 void QuicConnection::OnSendConnectionState(
@@ -1782,6 +1787,14 @@ void QuicConnection::OnRetransmissionTimeout() {
     return;
   }
 
+  if (close_connection_after_five_rtos_ &&
+      sent_packet_manager_.consecutive_rto_count() >= 4) {
+    // Close on the 5th consecutive RTO, so after 4 previous RTOs have occurred.
+    SendConnectionCloseWithDetails(QUIC_TOO_MANY_RTOS,
+                                   "5 consecutive retransmission timeouts");
+    return;
+  }
+
   sent_packet_manager_.OnRetransmissionTimeout();
   WriteIfNotBlocked();