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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 <unordered_map>
#include <vector>
#include "base/macros.h"
#include "net/quic/core/crypto/quic_compressed_certs_cache.h"
#include "net/quic/core/crypto/quic_random.h"
#include "net/quic/core/quic_blocked_writer_interface.h"
#include "net/quic/core/quic_buffered_packet_store.h"
#include "net/quic/core/quic_connection.h"
#include "net/quic/core/quic_crypto_server_stream.h"
#include "net/quic/core/quic_packets.h"
#include "net/quic/core/quic_session.h"
#include "net/quic/core/quic_version_manager.h"
#include "net/quic/platform/api/quic_containers.h"
#include "net/quic/platform/api/quic_socket_address.h"
#include "net/tools/quic/quic_process_packet_interface.h"
#include "net/tools/quic/quic_time_wait_list_manager.h"
#include "net/tools/quic/stateless_rejector.h"
namespace net {
namespace test {
class QuicDispatcherPeer;
} // namespace test
class QuicConfig;
class QuicCryptoServerConfig;
class QuicDispatcher : public QuicTimeWaitListManager::Visitor,
public ProcessPacketInterface,
public QuicBlockedWriterInterface,
public QuicFramerVisitorInterface,
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);
~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& server_address,
const QuicSocketAddress& client_address,
const QuicReceivedPacket& packet) override;
// Called when the socket becomes writable to allow queued writes to happen.
void OnCanWrite() override;
// 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 connection_id,
QuicErrorCode error,
const std::string& error_details) override;
// QuicSession::Visitor interface implementation (via inheritance of
// QuicTimeWaitListManager::Visitor):
// Queues the blocked writer for later resumption.
void OnWriteBlocked(QuicBlockedWriterInterface* blocked_writer) override;
// QuicTimeWaitListManager::Visitor interface implementation
// Called whenever the time wait list manager adds a new connection to the
// time-wait list.
void OnConnectionAddedToTimeWaitList(QuicConnectionId connection_id) override;
using SessionMap =
std::unordered_map<QuicConnectionId, std::unique_ptr<QuicSession>>;
const SessionMap& session_map() const { return session_map_; }
// Deletes all sessions on the closed session list and clears the list.
virtual void DeleteSessions();
// 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 QuicPacketNumber kMaxReasonableInitialPacketNumber = 100;
static_assert(kMaxReasonableInitialPacketNumber >=
kInitialCongestionWindow + 10,
"kMaxReasonableInitialPacketNumber is unreasonably small "
"relative to kInitialCongestionWindow.");
// QuicFramerVisitorInterface implementation. Not expected to be called
// outside of this class.
void OnPacket() override;
// Called when the public header has been parsed.
bool OnUnauthenticatedPublicHeader(
const QuicPacketPublicHeader& header) override;
// Called when the private header has been parsed of a data packet that is
// destined for the time wait manager.
bool OnUnauthenticatedHeader(const QuicPacketHeader& header) override;
void OnError(QuicFramer* framer) override;
bool OnProtocolVersionMismatch(QuicVersion received_version) override;
// The following methods should never get called because
// OnUnauthenticatedPublicHeader() or OnUnauthenticatedHeader() (whichever
// was called last), will return false and prevent a subsequent invocation
// of these methods. Thus, the payload of the packet is never processed in
// the dispatcher.
void OnPublicResetPacket(const QuicPublicResetPacket& packet) override;
void OnVersionNegotiationPacket(
const QuicVersionNegotiationPacket& packet) override;
void OnDecryptedPacket(EncryptionLevel level) override;
bool OnPacketHeader(const QuicPacketHeader& header) override;
bool OnStreamFrame(const QuicStreamFrame& frame) override;
bool OnAckFrame(const QuicAckFrame& frame) override;
bool OnStopWaitingFrame(const QuicStopWaitingFrame& frame) override;
bool OnPaddingFrame(const QuicPaddingFrame& frame) override;
bool OnPingFrame(const QuicPingFrame& frame) override;
bool OnRstStreamFrame(const QuicRstStreamFrame& frame) override;
bool OnConnectionCloseFrame(const QuicConnectionCloseFrame& frame) override;
bool OnGoAwayFrame(const QuicGoAwayFrame& frame) override;
bool OnWindowUpdateFrame(const QuicWindowUpdateFrame& frame) override;
bool OnBlockedFrame(const QuicBlockedFrame& frame) override;
bool OnPathCloseFrame(const QuicPathCloseFrame& frame) override;
void OnPacketComplete() override;
// QuicBufferedPacketStore::VisitorInterface implementation.
void OnExpiredPackets(QuicConnectionId 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 connection_id,
const QuicSocketAddress& client_address) = 0;
// Called when a connection is rejected statelessly.
virtual void OnConnectionRejectedStatelessly();
// Called when a connection is closed statelessly.
virtual void OnConnectionClosedStatelessly(QuicErrorCode error);
// Returns true if cheap stateless rejection should be attempted.
virtual bool ShouldAttemptCheapStatelessRejection();
// 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, in that if one validity check indicates a lower-valued fate and
// another validity check indicates a higher-valued fate, the higher-valued
// fate should be obeyed.
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.
// Buffer the packet.
// Drop the packet (ignore and give no response).
// This method is called by OnUnauthenticatedHeader 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.
virtual QuicPacketFate ValidityChecks(const QuicPacketHeader& header);
// 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();
// Called when |connection_id| doesn't have an open connection yet, to buffer
// |current_packet_| until it can be delivered to the connection.
void BufferEarlyPacket(QuicConnectionId connection_id);
// Called when |current_packet_| is a CHLO packet. Creates a new connection
// and delivers any buffered packets for that connection id.
void ProcessChlo();
QuicTimeWaitListManager* time_wait_list_manager() {
return time_wait_list_manager_.get();
const QuicVersionVector& GetSupportedVersions();
QuicConnectionId current_connection_id() { return current_connection_id_; }
const QuicSocketAddress& current_server_address() {
return current_server_address_;
const QuicSocketAddress& current_client_address() {
return current_client_address_;
const QuicReceivedPacket& current_packet() { return *current_packet_; }
const QuicConfig& config() const { return config_; }
const QuicCryptoServerConfig* crypto_config() const { return crypto_config_; }
QuicCompressedCertsCache* compressed_certs_cache() {
return &compressed_certs_cache_;
QuicFramer* framer() { return &framer_; }
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(); }
// Creates per-connection packet writers out of the QuicDispatcher's shared
// QuicPacketWriter. The per-connection writers' IsWriteBlocked() state must
// always be the same as the shared writer's IsWriteBlocked(), or else the
// QuicDispatcher::OnCanWrite logic will not work. (This will hopefully be
// cleaned up for bug 16950226.)
virtual QuicPacketWriter* CreatePerConnectionWriter();
// Returns true if a session should be created for a connection with an
// unknown version identified by |version_tag|.
virtual bool ShouldCreateSessionForUnknownVersion(QuicTag version_tag);
void SetLastError(QuicErrorCode error);
// Called when the public header has been parsed and the session has been
// looked up, and the session was not found in the active list of sessions.
// Returns false if processing should stop after this call.
virtual bool OnUnauthenticatedUnknownPublicHeader(
const QuicPacketPublicHeader& header);
// 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(
QuicConnectionId connection_id);
bool HasBufferedPackets(QuicConnectionId connection_id);
// Called when BufferEarlyPacket() fail to buffer the packet.
virtual void OnBufferPacketFailure(
QuicBufferedPacketStore::EnqueuePacketResult result,
QuicConnectionId connection_id);
friend class test::QuicDispatcherPeer;
friend class StatelessRejectorProcessDoneCallback;
typedef std::unordered_set<QuicConnectionId> QuicConnectionIdSet;
// Removes the session from the session map and write blocked list, and adds
// the ConnectionId to the time-wait list. If |session_closed_statelessly| is
// true, any future packets for the ConnectionId will be black-holed.
void CleanUpSession(SessionMap::iterator it,
QuicConnection* connection,
bool session_closed_statelessly);
bool HandlePacketForTimeWait(const QuicPacketPublicHeader& header);
// Attempts to reject the connection statelessly, if stateless rejects are
// possible and if the current packet contains a CHLO message. Determines a
// fate which describes what subsequent processing should be performed on the
// packets, like ValidityChecks, and invokes ProcessUnauthenticatedHeaderFate.
void MaybeRejectStatelessly(QuicConnectionId connection_id,
const QuicPacketHeader& header);
// Deliver |packets| to |session| for further processing.
void DeliverPacketsToSession(
const std::list<QuicBufferedPacketStore::BufferedPacket>& packets,
QuicSession* session);
// Perform the appropriate actions on the current packet based on |fate| -
// either process, buffer, or drop it.
void ProcessUnauthenticatedHeaderFate(QuicPacketFate fate,
QuicConnectionId connection_id,
QuicPacketNumber packet_number);
// Invoked when StatelessRejector::Process completes.
void OnStatelessRejectorProcessDone(
std::unique_ptr<StatelessRejector> rejector,
const QuicSocketAddress& current_client_address,
const QuicSocketAddress& current_server_address,
std::unique_ptr<QuicReceivedPacket> current_packet,
QuicPacketNumber packet_number,
QuicVersion first_version);
// Examine the state of the rejector and decide what to do with the current
// packet.
void ProcessStatelessRejectorState(
std::unique_ptr<StatelessRejector> rejector,
QuicPacketNumber packet_number,
QuicVersion first_version);
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_;
// 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_;
// Set of connection IDs for which asynchronous CHLO processing is in
// progress, making it necessary to buffer any other packets which arrive on
// that connection until CHLO processing is complete.
QuicConnectionIdSet temporarily_buffered_connections_;
// Information about the packet currently being handled.
QuicSocketAddress current_client_address_;
QuicSocketAddress current_server_address_;
const QuicReceivedPacket* current_packet_;
QuicConnectionId current_connection_id_;
// Used to get the supported versions based on flag. Does not own.
QuicVersionManager* version_manager_;
QuicFramer framer_;
// The last error set by SetLastError(), which is called by
// framer_visitor_->OnError().
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_;
} // namespace net