gfe-relnote: Drop QUIC INITIAL packets which are less than 1200 bytes. Protected by --gfe2_reloadable_flag_quic_drop_small_initial_packets

PiperOrigin-RevId: 286621288
Change-Id: I46543378213f091886662d4963b84a5b74ac3e9f

quic/core/quic_dispatcher.cc

diff --git a/quic/core/quic_dispatcher.cc b/quic/core/quic_dispatcher.cc
index 9c71d41..c628993 100644
--- a/quic/core/quic_dispatcher.cc
+++ b/quic/core/quic_dispatcher.cc
@@ -149,6 +149,9 @@
                                   const QuicSocketAddress& peer_address,
                                   QuicErrorCode error_code,
                                   const std::string& error_details) {
+    // TODO(rch): Remove this method when quic_drop_small_initial_packets is
+    // deprecated.
+    DCHECK(!GetQuicReloadableFlag(quic_drop_small_initial_packets));
     SerializeConnectionClosePacket(error_code, error_details);
 
     for (const auto& packet : *collector_.packets()) {
@@ -457,6 +460,13 @@
         packet_info.form == IETF_QUIC_LONG_HEADER_PACKET &&
         packet_info.long_packet_type == INITIAL &&
         packet_info.packet.length() < kMinClientInitialPacketLength) {
+      if (GetQuicReloadableFlag(quic_drop_small_initial_packets)) {
+        QUIC_DVLOG(1) << "Dropping initial packet which is too short, length: "
+                      << packet_info.packet.length();
+        QUIC_CODE_COUNT(quic_drop_small_initial_packets);
+        QUIC_RELOADABLE_FLAG_COUNT(quic_drop_small_initial_packets);
+        return true;
+      }
       StatelessConnectionTerminator terminator(
           packet_info.destination_connection_id, packet_info.version,
           helper_.get(), time_wait_list_manager_.get());

quic/core/quic_dispatcher_test.cc

diff --git a/quic/core/quic_dispatcher_test.cc b/quic/core/quic_dispatcher_test.cc
index 4f797c2..6d83adf 100644
--- a/quic/core/quic_dispatcher_test.cc
+++ b/quic/core/quic_dispatcher_test.cc
@@ -1270,7 +1270,14 @@
   QuicSocketAddress client_address(QuicIpAddress::Loopback4(), 1);
 
   EXPECT_CALL(*dispatcher_, CreateQuicSession(_, _, _, _)).Times(0);
-  EXPECT_CALL(*time_wait_list_manager_, SendPacket(_, _, _)).Times(1);
+  if (GetQuicReloadableFlag(quic_drop_small_initial_packets)) {
+    EXPECT_CALL(*time_wait_list_manager_, SendPacket(_, _, _)).Times(0);
+  } else {
+    EXPECT_CALL(*time_wait_list_manager_, SendPacket(_, _, _)).Times(1);
+  }
+  EXPECT_CALL(*time_wait_list_manager_,
+              AddConnectionIdToTimeWait(_, _, _, _, _))
+      .Times(0);
   ProcessPacket(client_address, TestConnectionId(1), true,
                 CurrentSupportedVersions()[0], SerializeCHLO(), false,
                 CONNECTION_ID_PRESENT, PACKET_4BYTE_PACKET_NUMBER, 1);