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From: Matt Corallo <lf-lists@mattcorallo.com>
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Date: Mon, 22 Feb 2021 01:44:55 -0500
Message-Id: <4FF38E1A-677B-478C-B32F-4640DF867810@mattcorallo.com>
References: <20210222051624.6eklzfec2bf4lqdk@erisian.com.au>
In-Reply-To: <20210222051624.6eklzfec2bf4lqdk@erisian.com.au>
To: Anthony Towns <aj@erisian.com.au>
Cc: Michael Folkson <michaelfolkson@gmail.com>,
 Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] Yesterday's Taproot activation meeting on
	lockinontimeout (LOT)
Precedence: list

Hmm, indeed, I may have missed that you can skip the headers issues by not p=
ersisting them, though there are other follow-on effects that are concerning=
 and I think still make my point valid.

A node feeding you invalid headers (used to be) cause for a ban - is that in=
formation still persisted? More importantly, nodes on both sides of the fork=
 need to find each other. There=E2=80=99s not a great way to do that without=
 forking the address database, DNS seeds and defining a new protocol magic.

Matt

> On Feb 22, 2021, at 00:16, Anthony Towns <aj@erisian.com.au> wrote:
>=20
> =EF=BB=BFOn Fri, Feb 19, 2021 at 12:48:00PM -0500, Matt Corallo via bitcoi=
n-dev wrote:
>> It was pointed out to me that this discussion is largely moot as the
>> software complexity for Bitcoin Core to ship an option like this is likel=
y
>> not practical/what people would wish to see.
>> Bitcoin Core does not have infrastructure to handle switching consensus
>> rules with the same datadir - after running with uasf=3Dtrue for some tim=
e,
>> valid blocks will be marked as invalid,=20
>=20
> I don't think this is true? With the current proposed bip8 code,
> lockinontimeout=3Dtrue will cause headers to be marked as invalid, and
> won't process the block further. If a node running lockinontimeout=3Dtrue
> accepts the header, then it will apply the same consensus rules as a
> lockinontimeout=3Dfalse node.
>=20
> I don't think an invalid header will be added to the block index at all,
> so a node restart should always cleanly allow it to be reconsidered.
>=20
> The test case in
>=20
> https://github.com/bitcoin/bitcoin/pull/19573/commits/bd8517135fc839c3332f=
ea4d9c8373b94c8c9de8
>=20
> tests that a node that had rejected a chain due to lockinontimeout=3Dtrue
> will reorg to that chain after being restarted as a byproduct of the way
> it tests different cases (the nodes set a new startheight, but retain
> their lockinontimeout settings).
>=20
>=20
> (I think with the current bip8 code, if you switch from
> lockinontimeout=3Dfalse to lockinontimeout=3Dtrue and the tip of the curre=
nt
> most work chain is after the timeoutheight and did not lockin, then you
> will continue following that chain until a taproot-invalid transaction
> is inclued, rather than immediately reorging to a shorter chain that
> complies with the lockinontimeout=3Dtrue rules)
>=20
> Cheers,
> aj
>=20