Fix a case when the initial rtt could be 0 when the client tries to

use 0 in QuicConfig.  Also ensures the initail_rtt is always at least
15ms.

Merge internal change: 79686080
BUG=431658
TBR=rch@chromium.org

Review URL: https://codereview.chromium.org/714143005

Cr-Commit-Position: refs/heads/master@{#303732}
(cherry picked from commit fc97ab64f59827a7438bc04ba57175edbdc45c34)

Review URL: https://codereview.chromium.org/724283002

Cr-Commit-Position: refs/branch-heads/2214@{#37}
Cr-Branched-From: 03655fd3f6d72165dc3c9bd2c89807305316fe6c-refs/heads/master@{#303346}

4 files changed, 18 insertions, 9 deletions

diff --git a/net/quic/quic_protocol.h b/net/quic/quic_protocol.h
index afd5ed4..ad920d0 100644
--- a/net/quic/quic_protocol.h
+++ b/net/quic/quic_protocol.h
@@ -76,6 +76,9 @@ const QuicByteCount kDefaultSocketReceiveBuffer = 256 * 1024;
 // Smaller values are ignored.
 const QuicByteCount kMinSocketReceiveBuffer = 16 * 1024;
 
+// Don't allow a client to suggest an RTT shorter than 10ms.
+const uint32 kMinInitialRoundTripTimeUs = 10 * kNumMicrosPerMilli;
+
 // Don't allow a client to suggest an RTT longer than 15 seconds.
 const uint32 kMaxInitialRoundTripTimeUs = 15 * kNumMicrosPerSecond;
 
diff --git a/net/quic/quic_sent_packet_manager.cc b/net/quic/quic_sent_packet_manager.cc
index bdf8690..9e2d04f 100644
--- a/net/quic/quic_sent_packet_manager.cc
+++ b/net/quic/quic_sent_packet_manager.cc
@@ -97,12 +97,16 @@ QuicSentPacketManager::~QuicSentPacketManager() {
 void QuicSentPacketManager::SetFromConfig(const QuicConfig& config) {
   if (config.HasReceivedInitialRoundTripTimeUs() &&
       config.ReceivedInitialRoundTripTimeUs() > 0) {
-    rtt_stats_.set_initial_rtt_us(min(kMaxInitialRoundTripTimeUs,
-                                      config.ReceivedInitialRoundTripTimeUs()));
-  } else if (config.HasInitialRoundTripTimeUsToSend()) {
     rtt_stats_.set_initial_rtt_us(
-        min(kMaxInitialRoundTripTimeUs,
-            config.GetInitialRoundTripTimeUsToSend()));
+        max(kMinInitialRoundTripTimeUs,
+            min(kMaxInitialRoundTripTimeUs,
+                config.ReceivedInitialRoundTripTimeUs())));
+  } else if (config.HasInitialRoundTripTimeUsToSend() &&
+             config.GetInitialRoundTripTimeUsToSend() > 0) {
+    rtt_stats_.set_initial_rtt_us(
+        max(kMinInitialRoundTripTimeUs,
+            min(kMaxInitialRoundTripTimeUs,
+                config.GetInitialRoundTripTimeUsToSend())));
   }
   // TODO(ianswett): BBR is currently a server only feature.
   if (FLAGS_quic_allow_bbr &&
diff --git a/net/quic/quic_time.h b/net/quic/quic_time.h
index 5fbe30c..53e5ebe 100644
--- a/net/quic/quic_time.h
+++ b/net/quic/quic_time.h
@@ -18,6 +18,8 @@
 namespace net {
 
 static const uint64 kNumMicrosPerSecond = base::Time::kMicrosecondsPerSecond;
+static const uint64 kNumMicrosPerMilli =
+    base::Time::kMicrosecondsPerMillisecond;
 
 // A QuicTime is a purely relative time. QuicTime values from different clocks
 // cannot be compared to each other. If you need an absolute time, see
diff --git a/net/tools/quic/end_to_end_test.cc b/net/tools/quic/end_to_end_test.cc
index 55e2d88..1fb3e79 100644
--- a/net/tools/quic/end_to_end_test.cc
+++ b/net/tools/quic/end_to_end_test.cc
@@ -924,7 +924,7 @@ TEST_P(EndToEndTest, LimitCongestionWindowAndRTT) {
   // Client tries to request twice the server's max initial window, and the
   // server limits it to the max.
   client_config_.SetInitialCongestionWindowToSend(2 * kMaxInitialWindow);
-  client_config_.SetInitialRoundTripTimeUsToSend(1000);
+  client_config_.SetInitialRoundTripTimeUsToSend(20000);
 
   ASSERT_TRUE(Initialize());
   client_->client()->WaitForCryptoHandshakeConfirmed();
@@ -949,9 +949,9 @@ TEST_P(EndToEndTest, LimitCongestionWindowAndRTT) {
   EXPECT_EQ(GetParam().use_pacing, server_sent_packet_manager.using_pacing());
   EXPECT_EQ(GetParam().use_pacing, client_sent_packet_manager.using_pacing());
 
-  // The client *should* set the intitial RTT.
-  EXPECT_EQ(1000u, client_sent_packet_manager.GetRttStats()->initial_rtt_us());
-  EXPECT_EQ(1000u, server_sent_packet_manager.GetRttStats()->initial_rtt_us());
+  // The client *should* set the intitial RTT, but it's increased to 10ms.
+  EXPECT_EQ(20000u, client_sent_packet_manager.GetRttStats()->initial_rtt_us());
+  EXPECT_EQ(20000u, server_sent_packet_manager.GetRttStats()->initial_rtt_us());
 
   // Now use the negotiated limits with packet loss.
   SetPacketLossPercentage(30);