Bastien TEINTURIER [ARCHIVE] on Nostr: 📅 Original date posted:2020-10-14 📝 Original message: I totally agree with the ...
📅 Original date posted:2020-10-14
📝 Original message:
I totally agree with the simplicity argument, I wanted to raise this
because it's (IMO) an issue
today because of the way we deal with on-chain fees, but it's less
impactful once update_fee is
scoped to some min_relay_fee.
Let's put this aside for now then and we can revisit later if needed.
Thanks for the feedback everyone!
Bastien
Le lun. 12 oct. 2020 à 20:49, Olaoluwa Osuntokun <laolu32 at gmail.com> a
écrit :
> > It seems to me that the "funder pays all the commit tx fees" rule exists
> > solely for simplicity (which was totally reasonable).
>
> At this stage, I've learned that simplicity (when doing anything that
> involves multi-party on-chain fee negotiating/verification/enforcement can
> really go a long way). Just think about all the edge cases w.r.t
> _allocating
> enough funds to pay for fees_ we've discovered over the past few years in
> the state machine. I fear adding a more elaborate fee splitting mechanism
> would only blow up the number of obscure edge cases that may lead to a
> channel temporarily or permanently being "borked".
>
> If we're going to add a "fairer" way of splitting fees, we'll really need
> to
> dig down pre-deployment to ensure that we've explored any resulting edge
> cases within our solution space, as we'll only be _adding_ complexity to
> fee
> splitting.
>
> IMO, anchor commitments in their "final form" (fixed fee rate on commitment
> transaction, only "emergency" use of update_fee) significantly simplifies
> things as it shifts from "funding pay fees", to "broadcaster/confirmer pays
> fees". However, as you note this doesn't fully distribute the worst-case
> cost of needing to go to chain with a "fully loaded" commitment
> transaction.
> Even with HTLCs, they could only be signed at 1 sat/byte from the funder's
> perspective, once again putting the burden on the broadcaster/confirmer to
> make up the difference.
>
> -- Laolu
>
>
> On Mon, Oct 5, 2020 at 6:13 AM Bastien TEINTURIER via Lightning-dev <
> lightning-dev at lists.linuxfoundation.org> wrote:
>
>> Good morning list,
>>
>> It seems to me that the "funder pays all the commit tx fees" rule exists
>> solely for simplicity
>> (which was totally reasonable). I haven't been able to find much
>> discussion about this decision
>> on the mailing list nor in the spec commits.
>>
>> At first glance, it's true that at the beginning of the channel lifetime,
>> the funder should be
>> responsible for the fee (it's his decision to open a channel after all).
>> But as time goes by and
>> both peers earn value from this channel, this rule becomes questionable.
>> We've discovered since
>> then that there is some risk associated with having pending HTLCs
>> (flood-and-loot type of attacks,
>> pinning, channel jamming, etc).
>>
>> I think that *in some cases*, fundees should be paying a portion of the
>> commit-tx on-chain fees,
>> otherwise we may end up with a web-of-trust network where channels would
>> only exist between peers
>> that trust each other, which is quite limiting (I'm hoping we can do
>> better).
>>
>> Routing nodes may be at risk when they *receive* HTLCs. All the attacks
>> that steal funds come from
>> the fact that a routing node has paid downstream but cannot claim the
>> upstream HTLCs (correct me
>> if that's incorrect). Thus I'd like nodes to pay for the on-chain fees of
>> the HTLCs they offer
>> while they're pending in the commit-tx, regardless of whether they're
>> funder or fundee.
>>
>> The simplest way to do this would be to deduce the HTLC cost (172 *
>> feerate) from the offerer's
>> main output (instead of the funder's main output, while keeping the base
>> commit tx weight paid
>> by the funder).
>>
>> A more extreme proposal would be to tie the *total* commit-tx fee to the
>> channel usage:
>>
>> * if there are no pending HTLCs, the funder pays all the fee
>> * if there are pending HTLCs, each node pays a proportion of the fee
>> proportional to the number of
>> HTLCs they offered. If Alice offered 1 HTLC and Bob offered 3 HTLCs, Bob
>> pays 75% of the
>> commit-tx fee and Alice pays 25%. When the HTLCs settle, the fee is
>> redistributed.
>>
>> This model uses the on-chain fee as collateral for usage of the channel.
>> If Alice wants to forward
>> HTLCs through this channel (because she has something to gain - routing
>> fees), she should be taking
>> on some of the associated risk, not Bob. Bob will be taking the same risk
>> downstream if he chooses
>> to forward.
>>
>> I believe it also forces the fundee to care about on-chain feerates,
>> which is a healthy incentive.
>> It may create a feedback loop between on-chain feerates and routing fees,
>> which I believe is also
>> a good long-term thing (but it's hard to predict as there may be negative
>> side-effects as well).
>>
>> What do you all think? Is this a terrible idea? Is it okay-ish, but not
>> worth the additional
>> complexity? Is it an amazing idea worth a lightning nobel? Please don't
>> take any of my claims
>> for granted and challenge them, there may be negative side-effects I'm
>> completely missing, this is
>> a fragile game of incentives...
>>
>> Side-note: don't forget to take into account that the fees for HTLC
>> transactions (second-level txs)
>> are always paid by the party that broadcasts them (which makes sense). I
>> still think this is not
>> enough and can even be abused by fundees in some setups.
>>
>> Thanks,
>> Bastien
>> _______________________________________________
>> Lightning-dev mailing list
>> Lightning-dev at lists.linuxfoundation.org
>> https://lists.linuxfoundation.org/mailman/listinfo/lightning-dev
>>
>
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📝 Original message:
I totally agree with the simplicity argument, I wanted to raise this
because it's (IMO) an issue
today because of the way we deal with on-chain fees, but it's less
impactful once update_fee is
scoped to some min_relay_fee.
Let's put this aside for now then and we can revisit later if needed.
Thanks for the feedback everyone!
Bastien
Le lun. 12 oct. 2020 à 20:49, Olaoluwa Osuntokun <laolu32 at gmail.com> a
écrit :
> > It seems to me that the "funder pays all the commit tx fees" rule exists
> > solely for simplicity (which was totally reasonable).
>
> At this stage, I've learned that simplicity (when doing anything that
> involves multi-party on-chain fee negotiating/verification/enforcement can
> really go a long way). Just think about all the edge cases w.r.t
> _allocating
> enough funds to pay for fees_ we've discovered over the past few years in
> the state machine. I fear adding a more elaborate fee splitting mechanism
> would only blow up the number of obscure edge cases that may lead to a
> channel temporarily or permanently being "borked".
>
> If we're going to add a "fairer" way of splitting fees, we'll really need
> to
> dig down pre-deployment to ensure that we've explored any resulting edge
> cases within our solution space, as we'll only be _adding_ complexity to
> fee
> splitting.
>
> IMO, anchor commitments in their "final form" (fixed fee rate on commitment
> transaction, only "emergency" use of update_fee) significantly simplifies
> things as it shifts from "funding pay fees", to "broadcaster/confirmer pays
> fees". However, as you note this doesn't fully distribute the worst-case
> cost of needing to go to chain with a "fully loaded" commitment
> transaction.
> Even with HTLCs, they could only be signed at 1 sat/byte from the funder's
> perspective, once again putting the burden on the broadcaster/confirmer to
> make up the difference.
>
> -- Laolu
>
>
> On Mon, Oct 5, 2020 at 6:13 AM Bastien TEINTURIER via Lightning-dev <
> lightning-dev at lists.linuxfoundation.org> wrote:
>
>> Good morning list,
>>
>> It seems to me that the "funder pays all the commit tx fees" rule exists
>> solely for simplicity
>> (which was totally reasonable). I haven't been able to find much
>> discussion about this decision
>> on the mailing list nor in the spec commits.
>>
>> At first glance, it's true that at the beginning of the channel lifetime,
>> the funder should be
>> responsible for the fee (it's his decision to open a channel after all).
>> But as time goes by and
>> both peers earn value from this channel, this rule becomes questionable.
>> We've discovered since
>> then that there is some risk associated with having pending HTLCs
>> (flood-and-loot type of attacks,
>> pinning, channel jamming, etc).
>>
>> I think that *in some cases*, fundees should be paying a portion of the
>> commit-tx on-chain fees,
>> otherwise we may end up with a web-of-trust network where channels would
>> only exist between peers
>> that trust each other, which is quite limiting (I'm hoping we can do
>> better).
>>
>> Routing nodes may be at risk when they *receive* HTLCs. All the attacks
>> that steal funds come from
>> the fact that a routing node has paid downstream but cannot claim the
>> upstream HTLCs (correct me
>> if that's incorrect). Thus I'd like nodes to pay for the on-chain fees of
>> the HTLCs they offer
>> while they're pending in the commit-tx, regardless of whether they're
>> funder or fundee.
>>
>> The simplest way to do this would be to deduce the HTLC cost (172 *
>> feerate) from the offerer's
>> main output (instead of the funder's main output, while keeping the base
>> commit tx weight paid
>> by the funder).
>>
>> A more extreme proposal would be to tie the *total* commit-tx fee to the
>> channel usage:
>>
>> * if there are no pending HTLCs, the funder pays all the fee
>> * if there are pending HTLCs, each node pays a proportion of the fee
>> proportional to the number of
>> HTLCs they offered. If Alice offered 1 HTLC and Bob offered 3 HTLCs, Bob
>> pays 75% of the
>> commit-tx fee and Alice pays 25%. When the HTLCs settle, the fee is
>> redistributed.
>>
>> This model uses the on-chain fee as collateral for usage of the channel.
>> If Alice wants to forward
>> HTLCs through this channel (because she has something to gain - routing
>> fees), she should be taking
>> on some of the associated risk, not Bob. Bob will be taking the same risk
>> downstream if he chooses
>> to forward.
>>
>> I believe it also forces the fundee to care about on-chain feerates,
>> which is a healthy incentive.
>> It may create a feedback loop between on-chain feerates and routing fees,
>> which I believe is also
>> a good long-term thing (but it's hard to predict as there may be negative
>> side-effects as well).
>>
>> What do you all think? Is this a terrible idea? Is it okay-ish, but not
>> worth the additional
>> complexity? Is it an amazing idea worth a lightning nobel? Please don't
>> take any of my claims
>> for granted and challenge them, there may be negative side-effects I'm
>> completely missing, this is
>> a fragile game of incentives...
>>
>> Side-note: don't forget to take into account that the fees for HTLC
>> transactions (second-level txs)
>> are always paid by the party that broadcasts them (which makes sense). I
>> still think this is not
>> enough and can even be abused by fundees in some setups.
>>
>> Thanks,
>> Bastien
>> _______________________________________________
>> Lightning-dev mailing list
>> Lightning-dev at lists.linuxfoundation.org
>> https://lists.linuxfoundation.org/mailman/listinfo/lightning-dev
>>
>
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