gfe-relnote: Do not pad server initial connection close packet. Protected by blocked gfe2_reloadable_flag_quic_enable_version_t*.

PiperOrigin-RevId: 294975306
Change-Id: Iee6759502df58292cc69f634c6273bd3b5b542b7

quic/core/quic_connection_test.cc

diff --git a/quic/core/quic_connection_test.cc b/quic/core/quic_connection_test.cc
index 67e2ab0..a7eac86 100644
--- a/quic/core/quic_connection_test.cc
+++ b/quic/core/quic_connection_test.cc
@@ -8173,6 +8173,26 @@
   ASSERT_TRUE(writer_->coalesced_packet() == nullptr);
 }
 
+TEST_P(QuicConnectionTest, DoNotPadServerInitialConnectionClose) {
+  if (!connection_.SupportsMultiplePacketNumberSpaces()) {
+    return;
+  }
+  set_perspective(Perspective::IS_SERVER);
+
+  EXPECT_CALL(visitor_, OnConnectionClosed(_, _));
+  const QuicErrorCode kQuicErrorCode = QUIC_INTERNAL_ERROR;
+  connection_.CloseConnection(
+      kQuicErrorCode, "Some random error message",
+      ConnectionCloseBehavior::SEND_CONNECTION_CLOSE_PACKET);
+
+  EXPECT_EQ(2u, QuicConnectionPeer::GetNumEncryptionLevels(&connection_));
+
+  TestConnectionCloseQuicErrorCode(kQuicErrorCode);
+  EXPECT_EQ(1u, writer_->connection_close_frames().size());
+  EXPECT_TRUE(writer_->padding_frames().empty());
+  EXPECT_EQ(ENCRYPTION_INITIAL, writer_->framer()->last_decrypted_level());
+}
+
 // Regression test for b/63620844.
 TEST_P(QuicConnectionTest, FailedToWriteHandshakePacket) {
   SimulateNextPacketTooLarge();

quic/core/quic_packet_creator.cc

diff --git a/quic/core/quic_packet_creator.cc b/quic/core/quic_packet_creator.cc
index 30df1a3..aa749c6 100644
--- a/quic/core/quic_packet_creator.cc
+++ b/quic/core/quic_packet_creator.cc
@@ -941,10 +941,17 @@
       << "Attempt to serialize empty coalesced packet";
   size_t packet_length = 0;
   if (coalesced.initial_packet() != nullptr) {
+    // Padding coalesced packet containing initial packet to full.
+    size_t padding_size = coalesced.max_packet_length() - coalesced.length();
+    if (framer_->perspective() == Perspective::IS_SERVER &&
+        QuicUtils::ContainsFrameType(
+            coalesced.initial_packet()->retransmittable_frames,
+            CONNECTION_CLOSE_FRAME)) {
+      // Do not pad server initial connection close packet.
+      padding_size = 0;
+    }
     size_t initial_length = ReserializeInitialPacketInCoalescedPacket(
-        *coalesced.initial_packet(),
-        /*padding_size=*/coalesced.max_packet_length() - coalesced.length(),
-        buffer, buffer_len);
+        *coalesced.initial_packet(), padding_size, buffer, buffer_len);
     if (initial_length == 0) {
       QUIC_BUG << "Failed to reserialize ENCRYPTION_INITIAL packet in "
                   "coalesced packet";