Safe Haskell	Safe-Inferred
Language	Haskell2010

Ouroboros.Consensus.MiniProtocol.ChainSync.Client.HistoricityCheck

Contents

Interface
Real implementation

Synopsis

data HistoricalChainSyncMessage
- = HistoricalMsgRollBackward
- | HistoricalMsgAwaitReply
data HistoricityCheck m blk = HistoricityCheck {
- judgeMessageHistoricity ∷ HistoricalChainSyncMessage → HeaderStateWithTime blk → m (Either HistoricityException ())
}
newtype HistoricityCutoff = HistoricityCutoff {
- getHistoricityCutoff ∷ NominalDiffTime
}
data HistoricityException = ∀ blk.HasHeader blk ⇒ HistoricityException {
- historicalMessage ∷ HistoricalChainSyncMessage
- historicalPoint ∷ !(Point blk)
- slotTime ∷ !RelativeTime
- arrivalTime ∷ !RelativeTime
- historicityCutoff ∷ !HistoricityCutoff
}
mkCheck ∷ ∀ m blk. (Monad m, HasHeader blk, HasAnnTip blk) ⇒ SystemTime m → m GsmState → HistoricityCutoff → HistoricityCheck m blk
noCheck ∷ Applicative m ⇒ HistoricityCheck m blk

Interface

data HistoricalChainSyncMessage Source #

ChainSync historicity checks are performed for MsgRollBackwards and MsgAwaitReplys, see HistoricityCheck.

Constructors

HistoricalMsgRollBackward
HistoricalMsgAwaitReply

Instances

Instances details

Show HistoricalChainSyncMessage Source #
Instance details Defined in Ouroboros.Consensus.MiniProtocol.ChainSync.Client.HistoricityCheck Methods showsPrec ∷ Int → HistoricalChainSyncMessage → ShowS # show ∷ HistoricalChainSyncMessage → String # showList ∷ [HistoricalChainSyncMessage] → ShowS #
Eq HistoricalChainSyncMessage Source #
Instance details Defined in Ouroboros.Consensus.MiniProtocol.ChainSync.Client.HistoricityCheck Methods (==) ∷ HistoricalChainSyncMessage → HistoricalChainSyncMessage → Bool # (/=) ∷ HistoricalChainSyncMessage → HistoricalChainSyncMessage → Bool #

data HistoricityCheck m blk Source #

Interface for the ChainSync client for deciding whether MsgRollBackwards and MsgAwaitReplys are historical.

Constructors

HistoricityCheck

Fields

judgeMessageHistoricity ∷ HistoricalChainSyncMessage → HeaderStateWithTime blk → m (Either HistoricityException ())
Determine whether the received message is historical. Depending on the first argument, the second argument is:
- HistoricalMsgRollBackward: The oldest state that was rolled back. (Note that rollbacks of depth zero are hence never historical.).
- HistoricalMsgAwaitReply: The state corresponding to the tip of the candidate fragment when MsgAwaitReply was sent.

newtype HistoricityCutoff Source #

Constructors

HistoricityCutoff
Fields getHistoricityCutoff ∷ NominalDiffTime

Instances

Instances details

Show HistoricityCutoff Source #
Instance details Defined in Ouroboros.Consensus.MiniProtocol.ChainSync.Client.HistoricityCheck Methods showsPrec ∷ Int → HistoricityCutoff → ShowS # show ∷ HistoricityCutoff → String # showList ∷ [HistoricityCutoff] → ShowS #
Eq HistoricityCutoff Source #
Instance details Defined in Ouroboros.Consensus.MiniProtocol.ChainSync.Client.HistoricityCheck Methods (==) ∷ HistoricityCutoff → HistoricityCutoff → Bool # (/=) ∷ HistoricityCutoff → HistoricityCutoff → Bool #
Ord HistoricityCutoff Source #
Instance details Defined in Ouroboros.Consensus.MiniProtocol.ChainSync.Client.HistoricityCheck Methods compare ∷ HistoricityCutoff → HistoricityCutoff → Ordering # (<) ∷ HistoricityCutoff → HistoricityCutoff → Bool # (<=) ∷ HistoricityCutoff → HistoricityCutoff → Bool # (>) ∷ HistoricityCutoff → HistoricityCutoff → Bool # (>=) ∷ HistoricityCutoff → HistoricityCutoff → Bool # max ∷ HistoricityCutoff → HistoricityCutoff → HistoricityCutoff # min ∷ HistoricityCutoff → HistoricityCutoff → HistoricityCutoff #

data HistoricityException Source #

Constructors

∀ blk.HasHeader blk ⇒ HistoricityException

We received a MsgRollBackward or a MsgAwaitReply while their candidate chain was too old for it to plausibly have been sent by an honest caught-up peer.

INVARIANT: historicityCutoff < arrivalTime diffRelTime slotTime

Fields

historicalMessage ∷ HistoricalChainSyncMessage
historicalPoint ∷ !(Point blk)
Depending on historicalMessage:
- HistoricalMsgRollBackward: The oldest header that was rewound.
- HistoricalMsgAwaitReply: The tip of the candidate fragment.
slotTime ∷ !RelativeTime
The time corresponding to the slot of historicalPoint.
arrivalTime ∷ !RelativeTime
When the offending historicalMessage was received.
historicityCutoff ∷ !HistoricityCutoff

Instances

Instances details

Exception HistoricityException Source #
Instance details Defined in Ouroboros.Consensus.MiniProtocol.ChainSync.Client.HistoricityCheck Methods toException ∷ HistoricityException → SomeException # fromException ∷ SomeException → Maybe HistoricityException # displayException ∷ HistoricityException → String #
Show HistoricityException Source #
Instance details Defined in Ouroboros.Consensus.MiniProtocol.ChainSync.Client.HistoricityCheck Methods showsPrec ∷ Int → HistoricityException → ShowS # show ∷ HistoricityException → String # showList ∷ [HistoricityException] → ShowS #
Eq HistoricityException Source #	The maximum age of a `MsgRollBackward` or `MsgAwaitReply` at arrival time, constraining the age of the oldest rewound header or the tip of the candidate fragment, respectively. This should be set to at least the maximum duration (across all eras) of a stability window (the number of slots in which at least `k` blocks are guaranteed to arise). For example, on Cardano mainnet today, the Praos Chain Growth property implies that `3k/f` (=129600) slots (=36 hours) will contain at least `k` (=2160) blocks. (Byron has a smaller stability window, namely `2k` (=24 hours as the Byron slot length is 20s). Thus a peer rolling back a header that is older than 36 hours or signals that it doesn't have more headers is either violating the maximum rollback or else isn't a caught-up node. Either way, a syncing node should not be connected to that peer.
Instance details Defined in Ouroboros.Consensus.MiniProtocol.ChainSync.Client.HistoricityCheck Methods (==) ∷ HistoricityException → HistoricityException → Bool # (/=) ∷ HistoricityException → HistoricityException → Bool #

Real implementation

mkCheck Source #

Arguments

∷ ∀ m blk. (Monad m, HasHeader blk, HasAnnTip blk)
⇒ SystemTime m
→ m GsmState	Get the current `GsmState`. This is used to disable the historicity check when we are caught up. The rationale is extra resilience against disconnects between honest nodes in disaster scenarios with very low chain density.
→ HistoricityCutoff
→ HistoricityCheck m blk

Deny all rollbacks that rewind blocks older than HistoricityCutoff upon arrival.

noCheck ∷ Applicative m ⇒ HistoricityCheck m blk Source #

Do not perform any historicity checks. This is useful when we only sync from trusted peers (Praos mode) or when the impact of historical messages is already mitigated by other means (for example indirectly by the Limit on Patience in the case of Genesis without ChainSync Jumping).