Introduce Legacy Version Encapsulation
This feature allows modern QUIC versions to encapsulate their first flight in Q043 packets, to support SNI-extraction middleboxes that do not support modern versions. More details in the design document at <go/quic-legacy-encaps>.
Introduce legacy version encapsulation, protected by gfe2_reloadable_flag_quic_dispatcher_legacy_version_encapsulation.
PiperOrigin-RevId: 317921151
Change-Id: I2dd8a3641caf3fd3d283613de3d117c1bdbea632
diff --git a/quic/core/quic_connection_test.cc b/quic/core/quic_connection_test.cc
index e5ab141..864a824 100644
--- a/quic/core/quic_connection_test.cc
+++ b/quic/core/quic_connection_test.cc
@@ -10371,6 +10371,49 @@
EXPECT_NE(nullptr, writer_->coalesced_packet());
}
+TEST_P(QuicConnectionTest, LegacyVersionEncapsulation) {
+ connection_.EnableLegacyVersionEncapsulation("test.example.org");
+
+ MockQuicConnectionDebugVisitor debug_visitor;
+ connection_.set_debug_visitor(&debug_visitor);
+ EXPECT_CALL(debug_visitor, OnPacketSent(_, _, _)).Times(1);
+
+ // Our TestPacketWriter normally parses the sent packet using the version
+ // from the connection, so here we need to tell it to use the encapsulation
+ // version, and reset the initial decrypter for that version.
+ writer_->framer()->SetSupportedVersions(
+ SupportedVersions(LegacyVersionForEncapsulation()));
+ writer_->framer()->framer()->SetInitialObfuscators(
+ connection_.connection_id());
+
+ {
+ QuicConnection::ScopedPacketFlusher flusher(&connection_);
+ connection_.SendCryptoDataWithString("TEST_CRYPTO_DATA", /*offset=*/0);
+ }
+
+ EXPECT_EQ(1u, writer_->packets_write_attempts());
+ // Verify that the packet is fully padded.
+ EXPECT_EQ(connection_.max_packet_length(), writer_->last_packet_size());
+
+ // Check that the connection stats show Legacy Version Encapsulation was used.
+ EXPECT_GT(connection_.GetStats().sent_legacy_version_encapsulated_packets,
+ 0u);
+
+ // Verify that the sent packet was in fact encapsulated, and check header.
+ const QuicPacketHeader& encapsulated_header = writer_->last_packet_header();
+ EXPECT_TRUE(encapsulated_header.version_flag);
+ EXPECT_EQ(encapsulated_header.version, LegacyVersionForEncapsulation());
+ EXPECT_EQ(encapsulated_header.destination_connection_id,
+ connection_.connection_id());
+
+ // Encapsulated packet should contain a stream frame for the crypto stream,
+ // optionally padding, and nothing else.
+ EXPECT_EQ(0u, writer_->crypto_frames().size());
+ EXPECT_EQ(1u, writer_->stream_frames().size());
+ EXPECT_EQ(writer_->frame_count(), writer_->framer()->padding_frames().size() +
+ writer_->stream_frames().size());
+}
+
TEST_P(QuicConnectionTest, ClientReceivedHandshakeDone) {
if (!connection_.version().HasHandshakeDone()) {
return;
