Package io.github.mahmoudimus.quic.token

Class BloomTokenLog

java.lang.Object

io.github.mahmoudimus.quic.token.BloomTokenLog

All Implemented Interfaces:

TokenLog

public final class BloomTokenLog
extends Object
implements TokenLog

A TokenLog of bounded memory. Each period keeps a hash set of the tokens used, which turns into a bloom filter once it outgrows its share of the memory budget, so memory grows linearly and then stops. Time is divided into periods of one token lifetime, and two filters cover the two periods in which unexpired tokens can expire; older filters are dropped, so the false positive rate does not climb forever.

Tokens are identified by the first 8 bytes of their nonce, which the server chose at random and authenticated, so no secure hash is needed.

Threads. Not thread-safe and takes no locks. An endpoint shares one log among its connections, so the endpoint layer must serialize calls to it.

Field Summary

Fields

Modifier and Type	Field	Description
static final long	DEFAULT_EXPECTED_HITS	The default expected token uses per lifetime.
static final int	DEFAULT_MAX_BYTES	The default memory budget, 10 MiB.

Fields inherited from interface io.github.mahmoudimus.quic.token.TokenLog

NONE

Constructor Summary

Constructors

Constructor	Description
BloomTokenLog()	A log with the default budget and expected use.
BloomTokenLog(int maxBytes, int kNum)	A log with a memory budget and a number of hash functions.

Method Summary

Modifier and Type	Method	Description
boolean	checkAndInsert(byte[] nonce, Instant issued, Duration lifetime)	Records that a token was used.
static BloomTokenLog	withExpectedItems(int maxBytes, long expectedHits)	A log with a memory budget, tuned for an expected number of uses per lifetime.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

DEFAULT_MAX_BYTES

public static final int DEFAULT_MAX_BYTES

The default memory budget, 10 MiB.

See Also:

• Constant Field Values

DEFAULT_EXPECTED_HITS

public static final long DEFAULT_EXPECTED_HITS

The default expected token uses per lifetime.

See Also:

• Constant Field Values

Constructor Details

BloomTokenLog

public BloomTokenLog()

A log with the default budget and expected use.

BloomTokenLog

public BloomTokenLog(int maxBytes,
 int kNum)

A log with a memory budget and a number of hash functions.

Parameters:

maxBytes - the approximate memory budget, split between the two filters

kNum - the number of bloom filter hash functions

Method Details

withExpectedItems

public static BloomTokenLog withExpectedItems(int maxBytes,
 long expectedHits)

A log with a memory budget, tuned for an expected number of uses per lifetime.

Parameters:

maxBytes - the approximate memory budget

expectedHits - the expected token uses per lifetime

Returns:

the log

checkAndInsert

public boolean checkAndInsert(byte[] nonce,
 Instant issued,
 Duration lifetime)

Description copied from interface: TokenLog

Records that a token was used.

Specified by:

checkAndInsert in interface TokenLog

Parameters:

nonce - the token's unique nonce

issued - when the token was issued

lifetime - how long such tokens are valid

Returns:

true if the token is accepted, false if it may have been used before