798430d127 wallet: Sanity check fee paid cannot be negative (Andrew Chow)
c1a84f108e wallet: Move fee underpayment check to after fee setting (Andrew Chow)
e5daf976d5 wallet: Rename nFeeRet in CreateTransactionInternal to current_fee (Andrew Chow)
Pull request description:
Currently the fee underpayment check occurs right after we calculate what the transaction's fee should be. However the fee paid by the transaction at that time does not always match. Notably, when doing SFFO, the fee paid at that time will almost always be less than the fee required, which then required having a bypass of the underpayment check that results in SFFO payments going through when they should not.
This PR moves the underpayment check to after fees have been finalized so that we always check whether the fee is being underpaid. This removes the exception for SFFO and unifies this behavior for both SFFO and non-SFFO txs.
ACKs for top commit:
S3RK:
Code review ACK 798430d127
furszy:
Code review ACK 798430d
glozow:
utACK 798430d127, code looks correct to me
Tree-SHA512: 720e8a3dbdc9937b12ee7881eb2ad58332c9584520da87ef3080e6f9d6220ce8d3bd8b9317b4877e56a229113437340852976db8f64df0d5cc50723fa04b02f0
8f3021155e