commit 6c7313ca12e854982a6a12b72e1a5714db9c83a4
author fayang <fayang@google.com> Thu Apr 23 12:10:35 2020 -0700
committer Copybara-Service <copybara-worker@google.com> Thu Apr 23 12:13:41 2020 -0700
tree b69d6f68c7d64c596ede05da8f022ca196e37ebc
parent bde76c39d428cfc284f9813e831260554836e139

gfe-relnote: In QUIC, add exponential backoff for PTO timeout when there is not RTT measurement. Protected by gfe2_reloadable_flag_quic_enable_version_draft_25_v3 and gfe2_reloadable_flag_quic_enable_version_draft_27.

Also change PTO timeout from 2 * initial_rtt to 3 * initial_rtt.

PiperOrigin-RevId: 308102591
Change-Id: If44e9e7f6107b7a95650e5f4744ea847d2b998d2

quic/core/quic_sent_packet_manager.cc

diff --git a/quic/core/quic_sent_packet_manager.cc b/quic/core/quic_sent_packet_manager.cc
index c727d93..f0ee1a7 100644
--- a/quic/core/quic_sent_packet_manager.cc
+++ b/quic/core/quic_sent_packet_manager.cc
@@ -1169,10 +1169,11 @@
 const QuicTime::Delta QuicSentPacketManager::GetProbeTimeoutDelay() const {
   DCHECK(pto_enabled_);
   if (rtt_stats_.smoothed_rtt().IsZero()) {
-    if (rtt_stats_.initial_rtt().IsZero()) {
-      return QuicTime::Delta::FromSeconds(1);
-    }
-    return 2 * rtt_stats_.initial_rtt();
+    // Respect kMinHandshakeTimeoutMs to avoid a potential amplification attack.
+    QUIC_BUG_IF(rtt_stats_.initial_rtt().IsZero());
+    return std::max(3 * rtt_stats_.initial_rtt(),
+                    QuicTime::Delta::FromMilliseconds(kMinHandshakeTimeoutMs)) *
+           (1 << consecutive_pto_count_);
   }
   const QuicTime::Delta rtt_var = use_standard_deviation_for_pto_
                                       ? rtt_stats_.GetStandardOrMeanDeviation()