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FRPCDoSDetection

RPC DoS detection

API > API/Runtime > API/Runtime/Engine

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

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 Unreal Specifiers
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 Unreal Specifiers

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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