Move future block check into validateHeader #204
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I'm still bothered by the fact that this isn't technically a consensus rule. It can't be a consensus rule, because the network does not reach consensus on the current time! The network only reaches consensus on "history" -- the list of parent blocks. (This is also why SufficientlyHeavierThan is not a consensus rule: it depends on information other than the history.)
Splitting the checks out like this does make the consensus package slightly harder to use correctly. But I think I'm okay with that. consensus is a low-level package whose only "real" consumer is coreutils/chain, so it can have some sharp edges. In theory, someone else could write their own implementation of chain.Manager with a different ErrFutureBlock threshold, and it would still be 100% compliant with Sia consensus.
| func validateHeader(s State, parentID types.BlockID, timestamp time.Time, nonce uint64, id types.BlockID) error { | ||
| if parentID != s.Index.ID { | ||
| return errors.New("wrong parent ID") | ||
| } else if timestamp.After(s.MaxFutureTimestamp(time.Now())) { |
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this makes the function impure -- calling it at different times gives you different results. The current time should be passed in as an argument instead.
This seems accurate, but with a big caveat. |
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