FRPCDoSDetection | Unreal Engine 5.6 Documentation

RPC DoS detection

Implements DoS detection for NetConnection RPC's, using an escalating series of detection states depending on the severity of the DoS, to prevent false positives and minimize any performance impact.

RPC's are profiled based on count and execution time, with careful implementation of tracking to balance lookup speed, memory usage, timing, and analytics tracking.


Name	FRPCDoSDetection
Type	class
Header File	/Engine/Source/Runtime/Engine/Public/Net/RPCDoSDetection.h
Include Path	#include "Net/RPCDoSDetection.h"

Syntax

class FRPCDoSDetection : protected FRPCDoSState

Inheritance Hierarchy

FRPCDoSState → FRPCDoSDetection

Classes

Name	Remarks
FPacketScope	Variables and functions that should only be accessible while receiving an individual packet
FSequentialRPCScope	Variables and functions that should only be accessible while receiving the same RPC individually/sequentially
FTickScope	Variables and functions that should only be accessible during TickDispatch
TScopeBase	Base class for setting code scope activity

Structs

Name	Remarks
FLightweightRPCTracking	Lightweight RPC tracking state

Constants

Name	Type	Remarks	Include Path
DefaultActiveRPCTrackingSize	int32	Default size for ActiveRPCTracking, to minimize realloc	Net/RPCDoSDetection.h
TimeQuotaCheckInterval	double	Interval for time quota checks, in seconds	Net/RPCDoSDetection.h

Variables

Protected

Name	Type	Remarks	Include Path
ActiveRPCTracking	TArray< FActiveRPCTrackingInfo >	Stores a reference to active/valid RPCTracking entries, for faster cleanup - as the above map stores values sparsely.	Net/RPCDoSDetection.h
ActiveState	int8	The currently active RPC DoS severity state settings	Net/RPCDoSDetection.h
AddressFunc	FGetRPCDoSAddress	Callback used for getting the address of the NetConnection the RPC DoS Detection is associated with	Net/RPCDoSDetection.h
AnalyticsMinTimePerSecThreshold	double	The minimum RPC time per second threshold, for doing analytics updates/checks	Net/RPCDoSDetection.h
AnalyticsVars	FRPCDoSAnalyticsVars	The locally cached/updated analytics variables, for the RPC DoS Detection - aggregated upon connection Close	Net/RPCDoSDetection.h
bHitchSuspendDetection	bool	Whether or not RPC DoS Detection has been suspended, due to a hitch impairing the accuracy of measurements	Net/RPCDoSDetection.h
bRPCDoSAnalytics	bool	Whether or not analytics for RPC DoS detection is enabled	Net/RPCDoSDetection.h
bRPCDoSDetection	bool	Whether or not RPC DoS detection is presently enabled	Net/RPCDoSDetection.h
bRPCTrackingEnabled	bool	Whether or not RPC Tracking has been enabled by RPC DoS escalation or other checks	Net/RPCDoSDetection.h
CachedAddress	FString	Player IP cached from AddressFunc	Net/RPCDoSDetection.h
CachedPlayerUID	FString	Player UID cached from PlayerUIDFunc	Net/RPCDoSDetection.h
CounterPerPeriodHistory	FRPCDoSCounters	Counter history which is precalculated/cached from CounterPerSecHistory, for tracking per-period time (up to a maximum of 16s)	Net/RPCDoSDetection.h
CounterPerSecHistory	TArray< FRPCDoSCounters >	Stores enough per second quota history, to allow all DetectionSeverity states to recalculate if their CooloffTime is reached	Net/RPCDoSDetection.h
DetectionSeverity	TArray< FRPCDoSStateConfig >	The different RPC DoS detection states, of escalating severity, depending on the amount of RPC spam	Net/RPCDoSDetection.h
ForcedRPCTracking	FName	If the related CVar is set, the name of the RPC which should forcibly enable tracking.	Net/RPCDoSDetection.h
ForcedRPCTrackingChance	double	Specifies the chance (between 0.0 and 1.0) that tracking will be enabled, when encountering the ForcedRPCTracking RPC	Net/RPCDoSDetection.h
ForcedRPCTrackingEndTime	double	Specifies the time at which forced RPC tracking should end, if tracking isn't enabled by the active state	Net/RPCDoSDetection.h
ForcedRPCTrackingLength	double	Specifies the length of time forced RPC tracking should be enabled (disabled the next tick, if 0.0)	Net/RPCDoSDetection.h
HitchSuspendDetectionStartTime	double	Timestamp for when RPC DoS Detection was suspended, due to a hitch	Net/RPCDoSDetection.h
HitchSuspendDetectionTimeMS	int32	The amount of time to suspend RPC DoS Detection, once a hitch is encountered, to prevent false positives from built-up packets	Net/RPCDoSDetection.h
HitchTimeQuotaMS	int32	The amount of time since the previous frame, for detecting hitches, to prevent false positives from built-up packets	Net/RPCDoSDetection.h
KickPlayerFunc	FRPCDoSKickPlayer	Callback used for kicking the player after a bad enough RPC DoS	Net/RPCDoSDetection.h
LastAnalyticsThresholdRecalc	double	The last time the 'AnalyticsMinTimePerSecThreshold' was recalculated	Net/RPCDoSDetection.h
LastCounterPerSecHistoryIdx	int32	The last written index of CounterPerSecHistory	Net/RPCDoSDetection.h
LastMetEscalationConditions	double	The last time the previous severity states escalation conditions were met (to prevent bouncing up/down between states)	Net/RPCDoSDetection.h
LastPerSecQuotaBegin	double	Timestamp for the last time per-second quota counting began	Net/RPCDoSDetection.h
LastPreTickDispatchTime	double	Cached PreTickDispatch timestamp, to reuse for minimizing timestamp retrieval	Net/RPCDoSDetection.h
LastRPCTrackingClean	double	The last time RPCTracking was cleaned out	Net/RPCDoSDetection.h
MaxRPCTrackingPeriod	int8	The runtime maximum number of seconds of RPC tracking that is used	Net/RPCDoSDetection.h
NextTimeQuotaCheck	double	Timestamp for when time quota's should next be checked	Net/RPCDoSDetection.h
PacketScopePrivate	FPacketScope	Scoped variables/functions accessible while receiving an individual packet	Net/RPCDoSDetection.h
PlayerUIDFunc	FGetRPCDoSPlayerUID	Callback used for getting the unique id of the NetConnection the RPC DoS Detection is associated with	Net/RPCDoSDetection.h
ReceivedPacketEndTime	double	Cached free/external timestamp, for when the last received packet finished processing	Net/RPCDoSDetection.h
RPCBlockAllowList	TArray< FName >	List of RPC's which should never be blocked	Net/RPCDoSDetection.h
RPCDoSAnalyticsData	TNetAnalyticsDataPtr< FRPCDoSAnalyticsData >	The net analytics data holder for the RPC DoS analytics, which is where analytics variables are aggregated upon Close	Net/RPCDoSDetection.h
RPCIntervalCounter	uint32	Unbounded RPC counter, for performing RPC checks at every 'x' intervals	Net/RPCDoSDetection.h
RPCTracking	TMap< void *, TSharedPtr< FRPCTrackingInfo > >	Maps UFunction pointers to live function tracking structs (NOTE: Treats the UFunction's as potentially invalid/GC'd, hence void*)	Net/RPCDoSDetection.h
SecondCounter	FRPCDoSCounters	Per-second RPC counting (approximate - may cover more than one second, in the case of expensive/long-running RPCs)	Net/RPCDoSDetection.h
SecondsIncrementer	uint8	Wrapping count of seconds passed, for RPC tracking	Net/RPCDoSDetection.h
SequentialRPCScopePrivate	FSequentialRPCScope	Scoped variables/functions accessible while receiving the same RPC individually/sequentially	Net/RPCDoSDetection.h
TickScopePrivate	FTickScope	Scoped variables/functions accessible during TickDispatch	Net/RPCDoSDetection.h
WorstActiveState	int8	The worst RPC DoS severity state that has been active	Net/RPCDoSDetection.h
WorstAnalyticsState	int8	The worst RPC DoS severity state that has been active and passed confirmation thresholds - used for limiting analytics events	Net/RPCDoSDetection.h

Functions

Public

Name	Remarks	Include Path
void Init ( FName NetDriverName, TSharedPtr< FNetAnalyticsAggregator >& AnalyticsAggregator, FGetWorld&& InWorldFunc, FGetRPCDoSAddress&& InAddressFunc, FGetRPCDoSPlayerUID&& InPlayerUIDFunc, FRPCDoSKickPlayer&& InKickPlayerFunc )	Initialize RPC DoS Detection, inputting callbacks for retrieving external information necessary for analytics.	Net/RPCDoSDetection.h
void InitConfig ( FName NetDriverName )	Initializes configuration settings for RPC DoS Detection - with support for hot reloading	Net/RPCDoSDetection.h
bool IsRPCDoSDetectionEnabled()	Whether or not RPC DoS Detection is enabled	Net/RPCDoSDetection.h
void LightweightReceivedRPC ( UFunction* Function, FName FunctionName )	If RPC monitoring is disabled, does extremely lightweight tracking of RPC calls, for monitoring tracking triggers, and to allow a chance for deducing full RPC tracking information if monitoring is enabled while receiving (so that e.g. if an RPC DoS attack enables monitoring, information on the RPC responsible can be recovered).	Net/RPCDoSDetection.h
void NotifyClose()	Triggered upon NetConnection Close (for committing analytics)	Net/RPCDoSDetection.h
ERPCNotifyResult NotifyReceivedRPC ( FNetBitReader& Reader, TSet< FNetworkGUID >& UnmappedGuids, UObject* Object, UFunction* Function, FName FunctionName )	If RPC monitoring is enabled, provides a notification for every RPC that is received, with the ability to block it.	Net/RPCDoSDetection.h
void PostReceivedPacket ( double TimeSeconds )	Called after the current NetConnection receives a packet.	Net/RPCDoSDetection.h
void PostReceivedRPC()	Called after the current NetConnection receives an RPC.	Net/RPCDoSDetection.h
void PostReceivedRPCPacket ( double TimeSeconds )	Called after the current NetConnection receives a packet, when RPC DoS Detection is active and the packet contains an RPC.	Net/RPCDoSDetection.h
void PostSequentialRPC ( EPostSequentialRPCType SequenceType, double TimeSeconds, FRPCDoSCounters* RPCCounter, FRPCTrackingInfo* RPCTrackingInfo )	Called after the same RPC was received once or multiple times sequentially, for optimal timing	Net/RPCDoSDetection.h
void PostTickDispatch()	Called after the packet-loop TickDispatch	Net/RPCDoSDetection.h
void PreReceivedPacket ( double TimeSeconds )	Called prior to the current NetConnection receiving a packet.	Net/RPCDoSDetection.h
void PreTickDispatch ( double TimeSeconds )	Called prior to the packet-loop TickDispatch	Net/RPCDoSDetection.h
void SetAddressFunc ( FGetRPCDoSAddress&& InAddressFunc )	Overrides the current AddressFunc	Net/RPCDoSDetection.h
void SetKickPlayerFunc ( FRPCDoSKickPlayer&& InKickPlayerFunc )	Overrides the current KickPlayerFunc	Net/RPCDoSDetection.h
void SetPlayerUIDFunc ( FGetRPCDoSPlayerUID&& InPlayerUIDFunc )	Overrides the current PlayerUIDFunc	Net/RPCDoSDetection.h
bool ShouldMonitorReceivedRPC()	Whether or not monitoring of received RPC's (i.e. calling of NotifyReceivedRPC) should be performed	Net/RPCDoSDetection.h
void UpdateSeverity ( ERPCDoSSeverityUpdate Update, ERPCDoSEscalateReason Reason )	Updates the current RPC DoS detection severity state	Net/RPCDoSDetection.h

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