In spite of the name FindLatestBefore used std::lower_bound to try
to find the earliest block with a nTime greater or equal to the
the requested value. But lower_bound uses bisection and requires
the input to be ordered with respect to the comparison operation.
Block times are not well ordered.
I don't know what lower_bound is permitted to do when the data
is not sufficiently ordered, but it's probably not good.
(I could construct an implementation which would infinite loop...)
To resolve the issue this commit introduces a maximum-so-far to the
block indexes and searches that.
For clarity the function is renamed to reflect what it actually does.
An issue that remains is that there is no grace period in importmulti:
If a address is created at time T and a send is immediately broadcast
and included by a miner with a slow clock there may not yet have been
any block with at least time T.
The normal rescan has a grace period of 7200 seconds, but importmulti
does not.
There is still a call to ActivateBestChain with cs_main if a peer
requests the block prior to it being validated, but this one is
more specifically-gated, so should be less of an issue.
AcceptToMemoryPool has several classes of return false statements.
- return state.Invalid or state.DoS directly itself
- return false and set fMissingInputs (state is valid)
- return false and state is set by failed CheckTransaction
- return false and state is set by failed CheckInputs.
This commit patches the last case where the state variable was reused for additional calls to CheckInputs to identify witness stripping as cause of validation failure. After this commit, it should be the case that if !fMissingInputs, state is always Invalid if AcceptToMemoryPool returns false.
On repeated calls to SelectCoins we try to meet the fee necessary for the last transaction, the new fee required might be smaller, so increase our change by the difference if we can.
Once we've picked coins and dummy-signed the transaction to calculate fee, if we don't have sufficient fee, then try to meet the fee by reducing change before resorting to picking new coins.
Cory Fields