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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// A server side dispatcher which dispatches a given client's data to their
// stream.
#include <memory>
#include <string>
#include <vector>
#include "net/third_party/quiche/src/quic/core/crypto/quic_compressed_certs_cache.h"
#include "net/third_party/quiche/src/quic/core/crypto/quic_random.h"
#include "net/third_party/quiche/src/quic/core/quic_blocked_writer_interface.h"
#include "net/third_party/quiche/src/quic/core/quic_buffered_packet_store.h"
#include "net/third_party/quiche/src/quic/core/quic_connection.h"
#include "net/third_party/quiche/src/quic/core/quic_crypto_server_stream.h"
#include "net/third_party/quiche/src/quic/core/quic_packets.h"
#include "net/third_party/quiche/src/quic/core/quic_process_packet_interface.h"
#include "net/third_party/quiche/src/quic/core/quic_session.h"
#include "net/third_party/quiche/src/quic/core/quic_time_wait_list_manager.h"
#include "net/third_party/quiche/src/quic/core/quic_version_manager.h"
#include "net/third_party/quiche/src/quic/platform/api/quic_containers.h"
#include "net/third_party/quiche/src/quic/platform/api/quic_socket_address.h"
namespace quic {
namespace test {
class QuicDispatcherPeer;
} // namespace test
class QuicConfig;
class QuicCryptoServerConfig;
class QuicDispatcher : public QuicTimeWaitListManager::Visitor,
public ProcessPacketInterface,
public QuicBufferedPacketStore::VisitorInterface {
// Ideally we'd have a linked_hash_set: the boolean is unused.
typedef QuicLinkedHashMap<QuicBlockedWriterInterface*, bool> WriteBlockedList;
QuicDispatcher(const QuicConfig* config,
const QuicCryptoServerConfig* crypto_config,
QuicVersionManager* version_manager,
std::unique_ptr<QuicConnectionHelperInterface> helper,
std::unique_ptr<QuicCryptoServerStream::Helper> session_helper,
std::unique_ptr<QuicAlarmFactory> alarm_factory,
uint8_t expected_server_connection_id_length);
QuicDispatcher(const QuicDispatcher&) = delete;
QuicDispatcher& operator=(const QuicDispatcher&) = delete;
~QuicDispatcher() override;
// Takes ownership of |writer|.
void InitializeWithWriter(QuicPacketWriter* writer);
// Process the incoming packet by creating a new session, passing it to
// an existing session, or passing it to the time wait list.
void ProcessPacket(const QuicSocketAddress& self_address,
const QuicSocketAddress& peer_address,
const QuicReceivedPacket& packet) override;
// Called when the socket becomes writable to allow queued writes to happen.
virtual void OnCanWrite();
// Returns true if there's anything in the blocked writer list.
virtual bool HasPendingWrites() const;
// Sends ConnectionClose frames to all connected clients.
void Shutdown();
// QuicSession::Visitor interface implementation (via inheritance of
// QuicTimeWaitListManager::Visitor):
// Ensure that the closed connection is cleaned up asynchronously.
void OnConnectionClosed(QuicConnectionId server_connection_id,
QuicErrorCode error,
const std::string& error_details,
ConnectionCloseSource source) override;
// QuicSession::Visitor interface implementation (via inheritance of
// QuicTimeWaitListManager::Visitor):
// Queues the blocked writer for later resumption.
void OnWriteBlocked(QuicBlockedWriterInterface* blocked_writer) override;
// QuicSession::Visitor interface implementation (via inheritance of
// QuicTimeWaitListManager::Visitor):
// Collects reset error code received on streams.
void OnRstStreamReceived(const QuicRstStreamFrame& frame) override;
// QuicSession::Visitor interface implementation (via inheritance of
// QuicTimeWaitListManager::Visitor):
// Collects reset error code received on streams.
void OnStopSendingReceived(const QuicStopSendingFrame& frame) override;
// QuicTimeWaitListManager::Visitor interface implementation
// Called whenever the time wait list manager adds a new connection to the
// time-wait list.
void OnConnectionAddedToTimeWaitList(
QuicConnectionId server_connection_id) override;
using SessionMap = QuicUnorderedMap<QuicConnectionId,
const SessionMap& session_map() const { return session_map_; }
// Deletes all sessions on the closed session list and clears the list.
virtual void DeleteSessions();
using ConnectionIdMap = QuicUnorderedMap<QuicConnectionId,
const ConnectionIdMap& connection_id_map() const {
return connection_id_map_;
// The largest packet number we expect to receive with a connection
// ID for a connection that is not established yet. The current design will
// send a handshake and then up to 50 or so data packets, and then it may
// resend the handshake packet up to 10 times. (Retransmitted packets are
// sent with unique packet numbers.)
static const uint64_t kMaxReasonableInitialPacketNumber = 100;
static_assert(kMaxReasonableInitialPacketNumber >=
kInitialCongestionWindow + 10,
"kMaxReasonableInitialPacketNumber is unreasonably small "
"relative to kInitialCongestionWindow.");
// QuicBufferedPacketStore::VisitorInterface implementation.
void OnExpiredPackets(QuicConnectionId server_connection_id,
early_arrived_packets) override;
// Create connections for previously buffered CHLOs as many as allowed.
virtual void ProcessBufferedChlos(size_t max_connections_to_create);
// Return true if there is CHLO buffered.
virtual bool HasChlosBuffered() const;
virtual QuicSession* CreateQuicSession(QuicConnectionId server_connection_id,
const QuicSocketAddress& peer_address,
QuicStringPiece alpn,
const ParsedQuicVersion& version) = 0;
// Tries to validate and dispatch packet based on available information.
// Returns true if packet is dropped or successfully dispatched (e.g.,
// processed by existing session, processed by time wait list, etc.),
// otherwise, returns false and the packet needs further processing.
virtual bool MaybeDispatchPacket(const ReceivedPacketInfo& packet_info);
// Values to be returned by ValidityChecks() to indicate what should be done
// with a packet. Fates with greater values are considered to be higher
// priority. ValidityChecks should return fate based on the priority order
// (i.e., returns higher priority fate first)
enum QuicPacketFate {
// Process the packet normally, which is usually to establish a connection.
// Put the connection ID into time-wait state and send a public reset.
// Drop the packet.
// This method is called by ProcessHeader on packets not associated with a
// known connection ID. It applies validity checks and returns a
// QuicPacketFate to tell what should be done with the packet.
// TODO(fayang): Merge ValidityChecks into MaybeDispatchPacket.
virtual QuicPacketFate ValidityChecks(const ReceivedPacketInfo& packet_info);
// Create and return the time wait list manager for this dispatcher, which
// will be owned by the dispatcher as time_wait_list_manager_
virtual QuicTimeWaitListManager* CreateQuicTimeWaitListManager();
// Buffers packet until it can be delivered to a connection.
void BufferEarlyPacket(const ReceivedPacketInfo& packet_info);
// Called when |packet_info| is a CHLO packet. Creates a new connection and
// delivers any buffered packets for that connection id.
void ProcessChlo(const std::string& alpn, ReceivedPacketInfo* packet_info);
// Return true if dispatcher wants to destroy session outside of
// OnConnectionClosed() call stack.
virtual bool ShouldDestroySessionAsynchronously();
QuicTimeWaitListManager* time_wait_list_manager() {
return time_wait_list_manager_.get();
const QuicTransportVersionVector& GetSupportedTransportVersions();
const ParsedQuicVersionVector& GetSupportedVersions();
const QuicConfig& config() const { return *config_; }
const QuicCryptoServerConfig* crypto_config() const { return crypto_config_; }
QuicCompressedCertsCache* compressed_certs_cache() {
return &compressed_certs_cache_;
QuicConnectionHelperInterface* helper() { return helper_.get(); }
QuicCryptoServerStream::Helper* session_helper() {
return session_helper_.get();
QuicAlarmFactory* alarm_factory() { return alarm_factory_.get(); }
QuicPacketWriter* writer() { return writer_.get(); }
// Returns true if a session should be created for a connection with an
// unknown version identified by |version_label|.
virtual bool ShouldCreateSessionForUnknownVersion(
QuicVersionLabel version_label);
void SetLastError(QuicErrorCode error);
// Called by MaybeDispatchPacket when current packet cannot be dispatched.
// Used by subclasses to conduct specific logic to dispatch packet. Returns
// true if packet is successfully dispatched.
virtual bool OnFailedToDispatchPacket(const ReceivedPacketInfo& packet_info);
// Called when a new connection starts to be handled by this dispatcher.
// Either this connection is created or its packets is buffered while waiting
// for CHLO. Returns true if a new connection should be created or its packets
// should be buffered, false otherwise.
virtual bool ShouldCreateOrBufferPacketForConnection(
const ReceivedPacketInfo& packet_info);
bool HasBufferedPackets(QuicConnectionId server_connection_id);
// Called when BufferEarlyPacket() fail to buffer the packet.
virtual void OnBufferPacketFailure(
QuicBufferedPacketStore::EnqueuePacketResult result,
QuicConnectionId server_connection_id);
// Removes the session from the session map and write blocked list, and adds
// the ConnectionId to the time-wait list.
virtual void CleanUpSession(SessionMap::iterator it,
QuicConnection* connection,
ConnectionCloseSource source);
void StopAcceptingNewConnections();
// Called to terminate a connection statelessly. Depending on |format|, either
// 1) send connection close with |error_code| and |error_details| and add
// connection to time wait list or 2) directly add connection to time wait
// list with |action|.
void StatelesslyTerminateConnection(
QuicConnectionId server_connection_id,
PacketHeaderFormat format,
bool version_flag,
bool use_length_prefix,
ParsedQuicVersion version,
QuicErrorCode error_code,
const std::string& error_details,
QuicTimeWaitListManager::TimeWaitAction action);
// Save/Restore per packet context.
virtual std::unique_ptr<QuicPerPacketContext> GetPerPacketContext() const;
virtual void RestorePerPacketContext(
std::unique_ptr<QuicPerPacketContext> /*context*/) {}
// If true, our framer will change its expected connection ID length
// to the received destination connection ID length of all IETF long headers.
void SetShouldUpdateExpectedServerConnectionIdLength(
bool should_update_expected_server_connection_id_length) {
should_update_expected_server_connection_id_length_ =
// If true, the dispatcher will allow incoming initial packets that have
// destination connection IDs shorter than 64 bits.
void SetAllowShortInitialServerConnectionIds(
bool allow_short_initial_server_connection_ids) {
allow_short_initial_server_connection_ids_ =
friend class test::QuicDispatcherPeer;
typedef QuicUnorderedSet<QuicConnectionId, QuicConnectionIdHash>
// TODO(fayang): Consider to rename this function to
// ProcessValidatedPacketWithUnknownConnectionId.
void ProcessHeader(ReceivedPacketInfo* packet_info);
// Deliver |packets| to |session| for further processing.
void DeliverPacketsToSession(
const std::list<QuicBufferedPacketStore::BufferedPacket>& packets,
QuicSession* session);
// If the connection ID length is different from what the dispatcher expects,
// replace the connection ID with a random one of the right length,
// and save it to make sure the mapping is persistent.
QuicConnectionId MaybeReplaceServerConnectionId(
QuicConnectionId server_connection_id,
ParsedQuicVersion version);
// Returns true if |version| is a supported protocol version.
bool IsSupportedVersion(const ParsedQuicVersion version);
// Sends public/stateless reset packets with no version and unknown
// connection ID according to the packet's size.
void MaybeResetPacketsWithNoVersion(const ReceivedPacketInfo& packet_info);
void set_new_sessions_allowed_per_event_loop(
int16_t new_sessions_allowed_per_event_loop) {
new_sessions_allowed_per_event_loop_ = new_sessions_allowed_per_event_loop;
const QuicConfig* config_;
const QuicCryptoServerConfig* crypto_config_;
// The cache for most recently compressed certs.
QuicCompressedCertsCache compressed_certs_cache_;
// The list of connections waiting to write.
WriteBlockedList write_blocked_list_;
SessionMap session_map_;
// Map of connection IDs with bad lengths to their replacements.
ConnectionIdMap connection_id_map_;
// Entity that manages connection_ids in time wait state.
std::unique_ptr<QuicTimeWaitListManager> time_wait_list_manager_;
// The list of closed but not-yet-deleted sessions.
std::vector<std::unique_ptr<QuicSession>> closed_session_list_;
// The helper used for all connections.
std::unique_ptr<QuicConnectionHelperInterface> helper_;
// The helper used for all sessions.
std::unique_ptr<QuicCryptoServerStream::Helper> session_helper_;
// Creates alarms.
std::unique_ptr<QuicAlarmFactory> alarm_factory_;
// An alarm which deletes closed sessions.
std::unique_ptr<QuicAlarm> delete_sessions_alarm_;
// The writer to write to the socket with.
std::unique_ptr<QuicPacketWriter> writer_;
// Packets which are buffered until a connection can be created to handle
// them.
QuicBufferedPacketStore buffered_packets_;
// Used to get the supported versions based on flag. Does not own.
QuicVersionManager* version_manager_;
// The last error set by SetLastError().
// TODO(fayang): consider removing last_error_.
QuicErrorCode last_error_;
// A backward counter of how many new sessions can be create within current
// event loop. When reaches 0, it means can't create sessions for now.
int16_t new_sessions_allowed_per_event_loop_;
// True if this dispatcher is not draining.
bool accept_new_connections_;
// If false, the dispatcher follows the IETF spec and rejects packets with
// invalid destination connection IDs lengths below 64 bits.
// If true they are allowed.
bool allow_short_initial_server_connection_ids_;
// IETF short headers contain a destination connection ID but do not
// encode its length. This variable contains the length we expect to read.
// This is also used to signal an error when a long header packet with
// different destination connection ID length is received when
// should_update_expected_server_connection_id_length_ is false and packet's
// version does not allow variable length connection ID.
uint8_t expected_server_connection_id_length_;
// If true, change expected_server_connection_id_length_ to be the received
// destination connection ID length of all IETF long headers.
bool should_update_expected_server_connection_id_length_;
} // namespace quic