neutrino icon indicating copy to clipboard operation
neutrino copied to clipboard

Published 20 hours ago • verified publisher icon lightninglabs

Regtest: "block target difficulty is higher than max"

Open amanzag opened this issue 2 years ago • 3 comments

Whenever I try to use neutrino in regtest mode, I run into this error:

I/GoLog   (29209): 2022-08-02 14:49:05.236 [DBG] BTCN: Difficulty retarget at block height 4032
I/GoLog   (29209): 2022-08-02 14:49:05.236 [DBG] BTCN: Old target 207fffff (7fffff0000000000000000000000000000000000000000000000000000000000)
I/GoLog   (29209): 2022-08-02 14:49:05.236 [DBG] BTCN: New target 201fffff (1fffff0000000000000000000000000000000000000000000000000000000000)
I/GoLog   (29209): 2022-08-02 14:49:05.236 [DBG] BTCN: Actual timespan 33h35m0s, adjusted timespan 84h0m0s, target timespan 336h0m0s
I/GoLog   (29209): 2022-08-02 14:49:05.236 [WRN] BTCN: Header doesn't pass sanity check: block target difficulty of 7fffff0000000000000000000000000000000000000000000000000000000000 is higher than max of 1fffff0000000000000000000000000000000000000000000000000000000000 -- disconnecting peer

There must be some flaw in the difficulty calculation logic here: https://github.com/lightninglabs/neutrino/blob/master/blockmanager.go#L2795-L2834

Related issue (but I think it belongs here): https://github.com/btcsuite/btcd/issues/1819

amanzag avatar Aug 02 '22 16:08 amanzag

Are you able to reproduce the same thing w/ simnet? IIRC, I think btcd will do difficulty retargets for regtest, while bitcoind never does. This is what historically led to the creation of simnet (which does the retargets).

Roasbeef avatar Aug 02 '22 20:08 Roasbeef

I think you're right. I can't reproduce with simnet and that's probably because I'm running neutrino against a bitcoind which, as you say, doesn't do retargets, as can be seen here: https://github.com/bitcoin/bitcoin/blob/master/src/chainparams.cpp#L407

Shouldn't btcd/neutrino disable retargets for regtest as well?

amanzag avatar Aug 02 '22 21:08 amanzag

I created a pull request https://github.com/lightninglabs/neutrino/pull/256 that fixes the issue. It's probably not the right way of fixing it, but if you point me in the right direction I can change it.

amanzag avatar Aug 03 '22 16:08 amanzag

bitcoind was refactored a bit, the fPowNoRetargeting field can now be found here: https://github.com/bitcoin/bitcoin/blob/e695d8536e534f1e59de4a62a0d87a93e7a73456/src/kernel/chainparams.cpp#L415

guggero avatar Apr 11 '23 08:04 guggero