RateLimiter Class Reference

Thread-safe per-key attempt limiter used to throttle abusive requests. More...

#include <ratelimiter.h>

Collaboration diagram for RateLimiter:

Classes
struct	AttemptHistory

Public Member Functions
bool	recordAttempt (const QString &key, int maxAttempts, int windowSeconds)
	Record an attempt for key and report whether the key is now blocked.
bool	recordAttemptAt (const QString &key, int maxAttempts, int windowSeconds, qint64 now)
	Record an attempt as seen at epoch second now.
bool	isBlocked (const QString &key, int maxAttempts, int windowSeconds) const
	True if key already has at least maxAttempts attempts within windowSeconds.
bool	isBlockedAt (const QString &key, int maxAttempts, int windowSeconds, qint64 now) const
	Whether key is blocked as measured at epoch second now.
void	clearAttempts (const QString &key)
	Drop all recorded attempts for the key, e.g. after a successful login.
int	retryAfterSeconds (const QString &key, int maxAttempts, int windowSeconds) const
	Get the retry-after window in seconds for key.
int	retryAfterSecondsAt (const QString &key, int maxAttempts, int windowSeconds, qint64 now) const
	Get the retry-after window in seconds for key as measured at now.

Private Member Functions
void	pruneLocked (qint64 now)
	Drops keys whose last attempts have fully aged out of their window.

Private Attributes
QMutex	mutex
QMap< QString, AttemptHistory >	attempts
qint64	lastPruneSecs = 0

Static Private Attributes
static constexpr int	PruneIntervalSeconds = 60

Detailed Description

Thread-safe per-key attempt limiter used to throttle abusive requests.

Member Function Documentation

clearAttempts()

void RateLimiter::clearAttempts

(

const QString &

key

)

Drop all recorded attempts for the key, e.g. after a successful login.

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isBlocked()

bool RateLimiter::isBlocked	(	const QString &	key,
		int	maxAttempts,
		int	windowSeconds ) const

True if key already has at least maxAttempts attempts within windowSeconds.

Reads only; records nothing. Returns false when maxAttempts <= 0 or windowSeconds <= 0. Delegates to isBlockedAt().

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isBlockedAt()

bool RateLimiter::isBlockedAt	(	const QString &	key,
		int	maxAttempts,
		int	windowSeconds,
		qint64	now ) const

Whether key is blocked as measured at epoch second now.

Exposed for deterministic tests; production callers should use isBlocked().

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pruneLocked()

void RateLimiter::pruneLocked ( qint64 now )

private

Drops keys whose last attempts have fully aged out of their window.

Runs at most every PruneIntervalSeconds to stop the map from growing without bound when attackers rotate source addresses.

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recordAttempt()

bool RateLimiter::recordAttempt	(	const QString &	key,
		int	maxAttempts,
		int	windowSeconds )

Record an attempt for key and report whether the key is now blocked.

A key that is already at its limit is not extended: the attempt is rejected without appending, so the lockout lifts once the recorded attempts age out of the window. Returns false immediately when maxAttempts <= 0 or windowSeconds <= 0 (rate limiting disabled), recording nothing.

Delegates to recordAttemptAt() with the current wall-clock time.

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recordAttemptAt()

bool RateLimiter::recordAttemptAt	(	const QString &	key,
		int	maxAttempts,
		int	windowSeconds,
		qint64	now )

Record an attempt as seen at epoch second now.

Exposed for deterministic tests; production callers should use recordAttempt().

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retryAfterSeconds()

int RateLimiter::retryAfterSeconds	(	const QString &	key,
		int	maxAttempts,
		int	windowSeconds ) const

Get the retry-after window in seconds for key.

Returns the number of seconds from now until the oldest attempt exits windowSeconds and the key is no longer blocked. If the key is not blocked, returns 0. Returns 0 if maxAttempts <= 0 or windowSeconds <= 0.

Delegates to retryAfterSecondsAt().

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retryAfterSecondsAt()

int RateLimiter::retryAfterSecondsAt	(	const QString &	key,
		int	maxAttempts,
		int	windowSeconds,
		qint64	now ) const

Get the retry-after window in seconds for key as measured at now.

Exposed for deterministic tests.

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Member Data Documentation

attempts

QMap<QString, AttemptHistory> RateLimiter::attempts

private

lastPruneSecs

qint64 RateLimiter::lastPruneSecs = 0

private

mutex

QMutex RateLimiter::mutex

mutableprivate

PruneIntervalSeconds

int RateLimiter::PruneIntervalSeconds = 60

staticconstexprprivate

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The documentation for this class was generated from the following files:

• servatrice/src/ratelimiter.h
• servatrice/src/ratelimiter.cpp