X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=lightning%2Fsrc%2Futil%2Fconfig.rs;h=4e124c27fd95d4f70b83e184ed291f0e56b3e9ef;hb=691e10f01eb904804a6a33d8cec8fc6568b0a884;hp=ba00158c635f5ef7fb85663b9bc8702b03695e28;hpb=f65660945d7f3577e09e9860b82b52f9b33a5814;p=rust-lightning diff --git a/lightning/src/util/config.rs b/lightning/src/util/config.rs index ba00158c..4e124c27 100644 --- a/lightning/src/util/config.rs +++ b/lightning/src/util/config.rs @@ -13,21 +13,24 @@ use crate::ln::channel::MAX_FUNDING_SATOSHIS_NO_WUMBO; use crate::ln::channelmanager::{BREAKDOWN_TIMEOUT, MAX_LOCAL_BREAKDOWN_TIMEOUT}; +#[cfg(fuzzing)] +use crate::util::ser::Readable; + /// Configuration we set when applicable. /// -/// Default::default() provides sane defaults. +/// `Default::default()` provides sane defaults. #[derive(Copy, Clone, Debug)] pub struct ChannelHandshakeConfig { /// Confirmations we will wait for before considering the channel locked in. - /// Applied only for inbound channels (see ChannelHandshakeLimits::max_minimum_depth for the + /// Applied only for inbound channels (see [`ChannelHandshakeLimits::max_minimum_depth`] for the /// equivalent limit applied to outbound channels). /// - /// A lower-bound of 1 is applied, requiring all channels to have a confirmed commitment + /// A lower-bound of `1` is applied, requiring all channels to have a confirmed commitment /// transaction before operation. If you wish to accept channels with zero confirmations, see /// [`UserConfig::manually_accept_inbound_channels`] and /// [`ChannelManager::accept_inbound_channel_from_trusted_peer_0conf`]. /// - /// Default value: 6. + /// Default value: `6` /// /// [`ChannelManager::accept_inbound_channel`]: crate::ln::channelmanager::ChannelManager::accept_inbound_channel /// [`ChannelManager::accept_inbound_channel_from_trusted_peer_0conf`]: crate::ln::channelmanager::ChannelManager::accept_inbound_channel_from_trusted_peer_0conf @@ -45,16 +48,16 @@ pub struct ChannelHandshakeConfig { /// case of an honest unilateral channel close, which implicitly decrease the economic value of /// our channel. /// - /// Default value: [`BREAKDOWN_TIMEOUT`], we enforce it as a minimum at channel opening so you - /// can tweak config to ask for more security, not less. + /// Default value: [`BREAKDOWN_TIMEOUT`] (We enforce it as a minimum at channel opening so you + /// can tweak config to ask for more security, not less.) pub our_to_self_delay: u16, /// Set to the smallest value HTLC we will accept to process. /// /// This value is sent to our counterparty on channel-open and we close the channel any time /// our counterparty misbehaves by sending us an HTLC with a value smaller than this. /// - /// Default value: 1. If the value is less than 1, it is ignored and set to 1, as is required - /// by the protocol. + /// Default value: `1` (If the value is less than `1`, it is ignored and set to `1`, as is + /// required by the protocol. pub our_htlc_minimum_msat: u64, /// Sets the percentage of the channel value we will cap the total value of outstanding inbound /// HTLCs to. @@ -63,7 +66,7 @@ pub struct ChannelHandshakeConfig { /// channel value in whole percentages. /// /// Note that: - /// * If configured to another value than the default value 10, any new channels created with + /// * If configured to another value than the default value `10`, any new channels created with /// the non default value will cause versions of LDK prior to 0.0.104 to refuse to read the /// `ChannelManager`. /// @@ -76,9 +79,11 @@ pub struct ChannelHandshakeConfig { /// See [`ChannelHandshakeConfig::our_to_self_delay`] and [`ChannelConfig::cltv_expiry_delta`] /// for more information. /// - /// Default value: 10. - /// Minimum value: 1, any values less than 1 will be treated as 1 instead. - /// Maximum value: 100, any values larger than 100 will be treated as 100 instead. + /// Default value: `10` + /// + /// Minimum value: `1` (Any values less will be treated as `1` instead.) + /// + /// Maximum value: `100` (Any values larger will be treated as `100` instead.) pub max_inbound_htlc_value_in_flight_percent_of_channel: u8, /// If set, we attempt to negotiate the `scid_privacy` (referred to as `scid_alias` in the /// BOLTs) option for outbound private channels. This provides better privacy by not including @@ -97,7 +102,7 @@ pub struct ChannelHandshakeConfig { /// [`ChannelHandshakeConfig::announced_channel`] and /// [`ChannelHandshakeLimits::force_announced_channel_preference`] for more. /// - /// Default value: false. This value is likely to change to true in the future. + /// Default value: `false` (This value is likely to change to `true` in the future.) /// /// [`ChannelManager`]: crate::ln::channelmanager::ChannelManager /// [`DecodeError::InvalidValue`]: crate::ln::msgs::DecodeError::InvalidValue @@ -110,7 +115,7 @@ pub struct ChannelHandshakeConfig { /// As the node which funds a channel picks this value this will only apply for new outbound /// channels unless [`ChannelHandshakeLimits::force_announced_channel_preference`] is set. /// - /// Default value: false. + /// Default value: `false` pub announced_channel: bool, /// When set, we commit to an upfront shutdown_pubkey at channel open. If our counterparty /// supports it, they will then enforce the mutual-close output to us matches what we provided @@ -122,9 +127,9 @@ pub struct ChannelHandshakeConfig { /// /// The upfront key committed is provided from [`SignerProvider::get_shutdown_scriptpubkey`]. /// - /// Default value: true. + /// Default value: `true` /// - /// [`SignerProvider::get_shutdown_scriptpubkey`]: crate::chain::keysinterface::SignerProvider::get_shutdown_scriptpubkey + /// [`SignerProvider::get_shutdown_scriptpubkey`]: crate::sign::SignerProvider::get_shutdown_scriptpubkey pub commit_upfront_shutdown_pubkey: bool, /// The Proportion of the channel value to configure as counterparty's channel reserve, /// i.e., `their_channel_reserve_satoshis` for both outbound and inbound channels. @@ -143,17 +148,28 @@ pub struct ChannelHandshakeConfig { /// Note: Versions of LDK earlier than v0.0.104 will fail to read channels with any channel reserve /// other than the default value. /// - /// Default value: 1% of channel value, i.e., configured as 10,000 millionths. - /// Minimum value: If the calculated proportional value is less than 1000 sats, it will be treated - /// as 1000 sats instead, which is a safe implementation-specific lower bound. - /// Maximum value: 1,000,000, any values larger than 1 Million will be treated as 1 Million (or 100%) - /// instead, although channel negotiations will fail in that case. + /// Default value: `10_000` millionths (i.e., 1% of channel value) + /// + /// Minimum value: If the calculated proportional value is less than `1000` sats, it will be + /// treated as `1000` sats instead, which is a safe implementation-specific lower + /// bound. + /// + /// Maximum value: `1_000_000` (i.e., 100% of channel value. Any values larger than one million + /// will be treated as one million instead, although channel negotiations will + /// fail in that case.) pub their_channel_reserve_proportional_millionths: u32, - #[cfg(anchors)] - /// If set, we attempt to negotiate the `anchors_zero_fee_htlc_tx`option for outbound channels. + /// If set, we attempt to negotiate the `anchors_zero_fee_htlc_tx`option for all future + /// channels. This feature requires having a reserve of onchain funds readily available to bump + /// transactions in the event of a channel force close to avoid the possibility of losing funds. + /// + /// Note that if you wish accept inbound channels with anchor outputs, you must enable + /// [`UserConfig::manually_accept_inbound_channels`] and manually accept them with + /// [`ChannelManager::accept_inbound_channel`]. This is done to give you the chance to check + /// whether your reserve of onchain funds is enough to cover the fees for all existing and new + /// channels featuring anchor outputs in the event of a force close. /// /// If this option is set, channels may be created that will not be readable by LDK versions - /// prior to 0.0.114, causing [`ChannelManager`]'s read method to return a + /// prior to 0.0.116, causing [`ChannelManager`]'s read method to return a /// [`DecodeError::InvalidValue`]. /// /// Note that setting this to true does *not* prevent us from opening channels with @@ -164,9 +180,10 @@ pub struct ChannelHandshakeConfig { /// vulnerability after its deployment. For more context, see the [`SIGHASH_SINGLE + update_fee /// Considered Harmful`] mailing list post. /// - /// Default value: false. This value is likely to change to true in the future. + /// Default value: `false` (This value is likely to change to `true` in the future.) /// /// [`ChannelManager`]: crate::ln::channelmanager::ChannelManager + /// [`ChannelManager::accept_inbound_channel`]: crate::ln::channelmanager::ChannelManager::accept_inbound_channel /// [`DecodeError::InvalidValue`]: crate::ln::msgs::DecodeError::InvalidValue /// [`SIGHASH_SINGLE + update_fee Considered Harmful`]: https://lists.linuxfoundation.org/pipermail/lightning-dev/2020-September/002796.html pub negotiate_anchors_zero_fee_htlc_tx: bool, @@ -179,9 +196,10 @@ pub struct ChannelHandshakeConfig { /// Note: Versions of LDK earlier than v0.0.115 will fail to read channels with a configuration /// other than the default value. /// - /// Default value: 50 - /// Maximum value: 483, any values larger will be treated as 483. - /// This is the BOLT #2 spec limit on `max_accepted_htlcs`. + /// Default value: `50` + /// + /// Maximum value: `483` (Any values larger will be treated as `483`. This is the BOLT #2 spec + /// limit on `max_accepted_htlcs`.) pub our_max_accepted_htlcs: u16, } @@ -196,18 +214,38 @@ impl Default for ChannelHandshakeConfig { announced_channel: false, commit_upfront_shutdown_pubkey: true, their_channel_reserve_proportional_millionths: 10_000, - #[cfg(anchors)] negotiate_anchors_zero_fee_htlc_tx: false, our_max_accepted_htlcs: 50, } } } +// When fuzzing, we want to allow the fuzzer to pick any configuration parameters. Thus, we +// implement Readable here in a naive way (which is a bit easier for the fuzzer to handle). We +// don't really want to ever expose this to users (if we did we'd want to use TLVs). +#[cfg(fuzzing)] +impl Readable for ChannelHandshakeConfig { + fn read(reader: &mut R) -> Result { + Ok(Self { + minimum_depth: Readable::read(reader)?, + our_to_self_delay: Readable::read(reader)?, + our_htlc_minimum_msat: Readable::read(reader)?, + max_inbound_htlc_value_in_flight_percent_of_channel: Readable::read(reader)?, + negotiate_scid_privacy: Readable::read(reader)?, + announced_channel: Readable::read(reader)?, + commit_upfront_shutdown_pubkey: Readable::read(reader)?, + their_channel_reserve_proportional_millionths: Readable::read(reader)?, + negotiate_anchors_zero_fee_htlc_tx: Readable::read(reader)?, + our_max_accepted_htlcs: Readable::read(reader)?, + }) + } +} + /// Optional channel limits which are applied during channel creation. /// /// These limits are only applied to our counterparty's limits, not our own. /// -/// Use 0/`::max_value()` as appropriate to skip checking. +/// Use `0` or `::max_value()` as appropriate to skip checking. /// /// Provides sane defaults for most configurations. /// @@ -219,40 +257,40 @@ pub struct ChannelHandshakeLimits { /// Minimum allowed satoshis when a channel is funded. This is supplied by the sender and so /// only applies to inbound channels. /// - /// Default value: 0. + /// Default value: `0` pub min_funding_satoshis: u64, /// Maximum allowed satoshis when a channel is funded. This is supplied by the sender and so /// only applies to inbound channels. /// - /// Default value: 2^24 - 1. + /// Default value: `2^24 - 1` pub max_funding_satoshis: u64, /// The remote node sets a limit on the minimum size of HTLCs we can send to them. This allows /// you to limit the maximum minimum-size they can require. /// - /// Default value: u64::max_value. + /// Default value: `u64::max_value` pub max_htlc_minimum_msat: u64, /// The remote node sets a limit on the maximum value of pending HTLCs to them at any given /// time to limit their funds exposure to HTLCs. This allows you to set a minimum such value. /// - /// Default value: 0. + /// Default value: `0` pub min_max_htlc_value_in_flight_msat: u64, /// The remote node will require we keep a certain amount in direct payment to ourselves at all /// time, ensuring that we are able to be punished if we broadcast an old state. This allows to /// you limit the amount which we will have to keep to ourselves (and cannot use for HTLCs). /// - /// Default value: u64::max_value. + /// Default value: `u64::max_value`. pub max_channel_reserve_satoshis: u64, /// The remote node sets a limit on the maximum number of pending HTLCs to them at any given /// time. This allows you to set a minimum such value. /// - /// Default value: 0. + /// Default value: `0` pub min_max_accepted_htlcs: u16, /// Before a channel is usable the funding transaction will need to be confirmed by at least a /// certain number of blocks, specified by the node which is not the funder (as the funder can /// assume they aren't going to double-spend themselves). /// This config allows you to set a limit on the maximum amount of time to wait. /// - /// Default value: 144, or roughly one day and only applies to outbound channels. + /// Default value: `144`, or roughly one day and only applies to outbound channels pub max_minimum_depth: u32, /// Whether we implicitly trust funding transactions generated by us for our own outbound /// channels to not be double-spent. @@ -265,12 +303,12 @@ pub struct ChannelHandshakeLimits { /// You may wish to un-set this if you allow the user to (or do in an automated fashion) /// double-spend the funding transaction to RBF with an alternative channel open. /// - /// This only applies if our counterparty set their confirmations-required value to 0, and we - /// always trust our own funding transaction at 1 confirmation irrespective of this value. + /// This only applies if our counterparty set their confirmations-required value to `0`, and we + /// always trust our own funding transaction at `1` confirmation irrespective of this value. /// Thus, this effectively acts as a `min_minimum_depth`, with the only possible values being - /// `true` (0) and `false` (1). + /// `true` (`0`) and `false` (`1`). /// - /// Default value: true + /// Default value: `true` pub trust_own_funding_0conf: bool, /// Set to force an incoming channel to match our announced channel preference in /// [`ChannelHandshakeConfig::announced_channel`]. @@ -279,14 +317,14 @@ pub struct ChannelHandshakeLimits { /// [`ChannelHandshakeConfig::announced_channel`] set to false, ensuring that no announced (aka public) /// channels will ever be opened. /// - /// Default value: true. + /// Default value: `true` pub force_announced_channel_preference: bool, /// Set to the amount of time we're willing to wait to claim money back to us. /// /// Not checking this value would be a security issue, as our peer would be able to set it to /// max relative lock-time (a year) and we would "lose" money as it would be locked for a long time. /// - /// Default value: 2016, which we also enforce as a maximum value so you can tweak config to + /// Default value: `2016`, which we also enforce as a maximum value so you can tweak config to /// reduce the loss of having useless locked funds (if your peer accepts) pub their_to_self_delay: u16 } @@ -308,6 +346,75 @@ impl Default for ChannelHandshakeLimits { } } +// When fuzzing, we want to allow the fuzzer to pick any configuration parameters. Thus, we +// implement Readable here in a naive way (which is a bit easier for the fuzzer to handle). We +// don't really want to ever expose this to users (if we did we'd want to use TLVs). +#[cfg(fuzzing)] +impl Readable for ChannelHandshakeLimits { + fn read(reader: &mut R) -> Result { + Ok(Self { + min_funding_satoshis: Readable::read(reader)?, + max_funding_satoshis: Readable::read(reader)?, + max_htlc_minimum_msat: Readable::read(reader)?, + min_max_htlc_value_in_flight_msat: Readable::read(reader)?, + max_channel_reserve_satoshis: Readable::read(reader)?, + min_max_accepted_htlcs: Readable::read(reader)?, + trust_own_funding_0conf: Readable::read(reader)?, + max_minimum_depth: Readable::read(reader)?, + force_announced_channel_preference: Readable::read(reader)?, + their_to_self_delay: Readable::read(reader)?, + }) + } +} + +/// Options for how to set the max dust exposure allowed on a channel. See +/// [`ChannelConfig::max_dust_htlc_exposure`] for details. +#[derive(Copy, Clone, Debug, PartialEq, Eq)] +pub enum MaxDustHTLCExposure { + /// This sets a fixed limit on the total dust exposure in millisatoshis. Setting this too low + /// may prevent the sending or receipt of low-value HTLCs on high-traffic nodes, however this + /// limit is very important to prevent stealing of large amounts of dust HTLCs by miners + /// through [fee griefing + /// attacks](https://lists.linuxfoundation.org/pipermail/lightning-dev/2020-May/002714.html). + /// + /// Note that if the feerate increases significantly, without a manual increase + /// to this maximum the channel may be unable to send/receive HTLCs between the maximum dust + /// exposure and the new minimum value for HTLCs to be economically viable to claim. + FixedLimitMsat(u64), + /// This sets a multiplier on the [`ConfirmationTarget::OnChainSweep`] feerate (in sats/KW) to + /// determine the maximum allowed dust exposure. If this variant is used then the maximum dust + /// exposure in millisatoshis is calculated as: + /// `feerate_per_kw * value`. For example, with our default value + /// `FeeRateMultiplier(10_000)`: + /// + /// - For the minimum fee rate of 1 sat/vByte (250 sat/KW, although the minimum + /// defaults to 253 sats/KW for rounding, see [`FeeEstimator`]), the max dust exposure would + /// be 253 * 10_000 = 2,530,000 msats. + /// - For a fee rate of 30 sat/vByte (7500 sat/KW), the max dust exposure would be + /// 7500 * 50_000 = 75,000,000 msats (0.00075 BTC). + /// + /// Note, if you're using a third-party fee estimator, this may leave you more exposed to a + /// fee griefing attack, where your fee estimator may purposely overestimate the fee rate, + /// causing you to accept more dust HTLCs than you would otherwise. + /// + /// This variant is primarily meant to serve pre-anchor channels, as HTLC fees being included + /// on HTLC outputs means your channel may be subject to more dust exposure in the event of + /// increases in fee rate. + /// + /// # Backwards Compatibility + /// This variant only became available in LDK 0.0.116, so if you downgrade to a prior version + /// by default this will be set to a [`Self::FixedLimitMsat`] of 5,000,000 msat. + /// + /// [`FeeEstimator`]: crate::chain::chaininterface::FeeEstimator + /// [`ConfirmationTarget::OnChainSweep`]: crate::chain::chaininterface::ConfirmationTarget::OnChainSweep + FeeRateMultiplier(u64), +} + +impl_writeable_tlv_based_enum!(MaxDustHTLCExposure, ; + (1, FixedLimitMsat), + (3, FeeRateMultiplier), +); + /// Options which apply on a per-channel basis and may change at runtime or based on negotiation /// with our counterparty. #[derive(Copy, Clone, Debug, PartialEq, Eq)] @@ -317,7 +424,7 @@ pub struct ChannelConfig { /// This may be allowed to change at runtime in a later update, however doing so must result in /// update messages sent to notify all nodes of our updated relay fee. /// - /// Default value: 0. + /// Default value: `0` pub forwarding_fee_proportional_millionths: u32, /// Amount (in milli-satoshi) charged for payments forwarded outbound over the channel, in /// excess of [`forwarding_fee_proportional_millionths`]. @@ -328,7 +435,7 @@ pub struct ChannelConfig { /// as of July 2021. Adjusting it upwards or downwards may change whether nodes route through /// this node. /// - /// Default value: 1000. + /// Default value: `1000` /// /// [`forwarding_fee_proportional_millionths`]: ChannelConfig::forwarding_fee_proportional_millionths pub forwarding_fee_base_msat: u32, @@ -346,34 +453,73 @@ pub struct ChannelConfig { /// enough time to broadcast and confirm a transaction, possibly with time in between to RBF /// the spending transaction). /// - /// Default value: 72 (12 hours at an average of 6 blocks/hour). - /// Minimum value: [`MIN_CLTV_EXPIRY_DELTA`], any values less than this will be treated as - /// [`MIN_CLTV_EXPIRY_DELTA`] instead. + /// Default value: `72` (12 hours at an average of 6 blocks/hour) + /// + /// Minimum value: [`MIN_CLTV_EXPIRY_DELTA`] (Any values less than this will be treated as + /// [`MIN_CLTV_EXPIRY_DELTA`] instead.) /// /// [`MIN_CLTV_EXPIRY_DELTA`]: crate::ln::channelmanager::MIN_CLTV_EXPIRY_DELTA pub cltv_expiry_delta: u16, - /// Limit our total exposure to in-flight HTLCs which are burned to fees as they are too - /// small to claim on-chain. + /// Limit our total exposure to potential loss to on-chain fees on close, including in-flight + /// HTLCs which are burned to fees as they are too small to claim on-chain and fees on + /// commitment transaction(s) broadcasted by our counterparty in excess of our own fee estimate. + /// + /// # HTLC-based Dust Exposure /// /// When an HTLC present in one of our channels is below a "dust" threshold, the HTLC will /// not be claimable on-chain, instead being turned into additional miner fees if either /// party force-closes the channel. Because the threshold is per-HTLC, our total exposure - /// to such payments may be sustantial if there are many dust HTLCs present when the + /// to such payments may be substantial if there are many dust HTLCs present when the /// channel is force-closed. /// /// The dust threshold for each HTLC is based on the `dust_limit_satoshis` for each party in a /// channel negotiated throughout the channel open process, along with the fees required to have /// a broadcastable HTLC spending transaction. When a channel supports anchor outputs /// (specifically the zero fee HTLC transaction variant), this threshold no longer takes into - /// account the HTLC transaction fee as it is zero. - /// - /// This limit is applied for sent, forwarded, and received HTLCs and limits the total - /// exposure across all three types per-channel. Setting this too low may prevent the - /// sending or receipt of low-value HTLCs on high-traffic nodes, and this limit is very - /// important to prevent stealing of dust HTLCs by miners. - /// - /// Default value: 5_000_000 msat. - pub max_dust_htlc_exposure_msat: u64, + /// account the HTLC transaction fee as it is zero. Because of this, you may want to set this + /// value to a fixed limit for channels using anchor outputs, while the fee rate multiplier + /// variant is primarily intended for use with pre-anchor channels. + /// + /// The selected limit is applied for sent, forwarded, and received HTLCs and limits the total + /// exposure across all three types per-channel. + /// + /// # Transaction Fee Dust Exposure + /// + /// Further, counterparties broadcasting a commitment transaction in a force-close may result + /// in other balance being burned to fees, and thus all fees on commitment and HTLC + /// transactions in excess of our local fee estimates are included in the dust calculation. + /// + /// Because of this, another way to look at this limit is to divide it by 43,000 (or 218,750 + /// for non-anchor channels) and see it as the maximum feerate disagreement (in sats/vB) per + /// non-dust HTLC we're allowed to have with our peers before risking a force-closure for + /// inbound channels. + // This works because, for anchor channels the on-chain cost is 172 weight (172+703 for + // non-anchors with an HTLC-Success transaction), i.e. + // dust_exposure_limit_msat / 1000 = 172 * feerate_in_sat_per_vb / 4 * HTLC count + // dust_exposure_limit_msat = 43,000 * feerate_in_sat_per_vb * HTLC count + // dust_exposure_limit_msat / HTLC count / 43,000 = feerate_in_sat_per_vb + /// + /// Thus, for the default value of 10_000 * a current feerate estimate of 10 sat/vB (or 2,500 + /// sat/KW), we risk force-closure if we disagree with our peer by: + /// * `10_000 * 2_500 / 43_000 / (483*2)` = 0.6 sat/vB for anchor channels with 483 HTLCs in + /// both directions (the maximum), + /// * `10_000 * 2_500 / 43_000 / (50*2)` = 5.8 sat/vB for anchor channels with 50 HTLCs in both + /// directions (the LDK default max from [`ChannelHandshakeConfig::our_max_accepted_htlcs`]) + /// * `10_000 * 2_500 / 218_750 / (483*2)` = 0.1 sat/vB for non-anchor channels with 483 HTLCs + /// in both directions (the maximum), + /// * `10_000 * 2_500 / 218_750 / (50*2)` = 1.1 sat/vB for non-anchor channels with 50 HTLCs + /// in both (the LDK default maximum from [`ChannelHandshakeConfig::our_max_accepted_htlcs`]) + /// + /// Note that when using [`MaxDustHTLCExposure::FeeRateMultiplier`] this maximum disagreement + /// will scale linearly with increases (or decreases) in the our feerate estimates. Further, + /// for anchor channels we expect our counterparty to use a relatively low feerate estimate + /// while we use [`ConfirmationTarget::OnChainSweep`] (which should be relatively high) and + /// feerate disagreement force-closures should only occur when theirs is higher than ours. + /// + /// Default value: [`MaxDustHTLCExposure::FeeRateMultiplier`] with a multiplier of `10_000` + /// + /// [`ConfirmationTarget::OnChainSweep`]: crate::chain::chaininterface::ConfirmationTarget::OnChainSweep + pub max_dust_htlc_exposure: MaxDustHTLCExposure, /// The additional fee we're willing to pay to avoid waiting for the counterparty's /// `to_self_delay` to reclaim funds. /// @@ -382,21 +528,75 @@ pub struct ChannelConfig { /// funder/initiator. /// /// When we are the funder, because we have to pay the channel closing fee, we bound the - /// acceptable fee by our [`Background`] and [`Normal`] fees, with the upper bound increased by + /// acceptable fee by our [`ChannelCloseMinimum`] and [`NonAnchorChannelFee`] fees, with the upper bound increased by /// this value. Because the on-chain fee we'd pay to force-close the channel is kept near our - /// [`Normal`] feerate during normal operation, this value represents the additional fee we're + /// [`NonAnchorChannelFee`] feerate during normal operation, this value represents the additional fee we're /// willing to pay in order to avoid waiting for our counterparty's to_self_delay to reclaim our /// funds. /// /// When we are not the funder, we require the closing transaction fee pay at least our - /// [`Background`] fee estimate, but allow our counterparty to pay as much fee as they like. + /// [`ChannelCloseMinimum`] fee estimate, but allow our counterparty to pay as much fee as they like. /// Thus, this value is ignored when we are not the funder. /// - /// Default value: 1000 satoshis. + /// Default value: `1000` /// - /// [`Normal`]: crate::chain::chaininterface::ConfirmationTarget::Normal - /// [`Background`]: crate::chain::chaininterface::ConfirmationTarget::Background + /// [`NonAnchorChannelFee`]: crate::chain::chaininterface::ConfirmationTarget::NonAnchorChannelFee + /// [`ChannelCloseMinimum`]: crate::chain::chaininterface::ConfirmationTarget::ChannelCloseMinimum pub force_close_avoidance_max_fee_satoshis: u64, + /// If set, allows this channel's counterparty to skim an additional fee off this node's inbound + /// HTLCs. Useful for liquidity providers to offload on-chain channel costs to end users. + /// + /// Usage: + /// - The payee will set this option and set its invoice route hints to use [intercept scids] + /// generated by this channel's counterparty. + /// - The counterparty will get an [`HTLCIntercepted`] event upon payment forward, and call + /// [`forward_intercepted_htlc`] with less than the amount provided in + /// [`HTLCIntercepted::expected_outbound_amount_msat`]. The difference between the expected and + /// actual forward amounts is their fee. See + /// + /// for how this feature may be used in the LSP use case. + /// + /// # Note + /// It's important for payee wallet software to verify that [`PaymentClaimable::amount_msat`] is + /// as-expected if this feature is activated, otherwise they may lose money! + /// [`PaymentClaimable::counterparty_skimmed_fee_msat`] provides the fee taken by the + /// counterparty. + /// + /// # Note + /// Switching this config flag on may break compatibility with versions of LDK prior to 0.0.116. + /// Unsetting this flag between restarts may lead to payment receive failures. + /// + /// Default value: `false` + /// + /// [intercept scids]: crate::ln::channelmanager::ChannelManager::get_intercept_scid + /// [`forward_intercepted_htlc`]: crate::ln::channelmanager::ChannelManager::forward_intercepted_htlc + /// [`HTLCIntercepted`]: crate::events::Event::HTLCIntercepted + /// [`HTLCIntercepted::expected_outbound_amount_msat`]: crate::events::Event::HTLCIntercepted::expected_outbound_amount_msat + /// [`PaymentClaimable::amount_msat`]: crate::events::Event::PaymentClaimable::amount_msat + /// [`PaymentClaimable::counterparty_skimmed_fee_msat`]: crate::events::Event::PaymentClaimable::counterparty_skimmed_fee_msat + // TODO: link to bLIP when it's merged + pub accept_underpaying_htlcs: bool, +} + +impl ChannelConfig { + /// Applies the given [`ChannelConfigUpdate`] as a partial update to the [`ChannelConfig`]. + pub fn apply(&mut self, update: &ChannelConfigUpdate) { + if let Some(forwarding_fee_proportional_millionths) = update.forwarding_fee_proportional_millionths { + self.forwarding_fee_proportional_millionths = forwarding_fee_proportional_millionths; + } + if let Some(forwarding_fee_base_msat) = update.forwarding_fee_base_msat { + self.forwarding_fee_base_msat = forwarding_fee_base_msat; + } + if let Some(cltv_expiry_delta) = update.cltv_expiry_delta { + self.cltv_expiry_delta = cltv_expiry_delta; + } + if let Some(max_dust_htlc_exposure_msat) = update.max_dust_htlc_exposure_msat { + self.max_dust_htlc_exposure = max_dust_htlc_exposure_msat; + } + if let Some(force_close_avoidance_max_fee_satoshis) = update.force_close_avoidance_max_fee_satoshis { + self.force_close_avoidance_max_fee_satoshis = force_close_avoidance_max_fee_satoshis; + } + } } impl Default for ChannelConfig { @@ -406,22 +606,101 @@ impl Default for ChannelConfig { forwarding_fee_proportional_millionths: 0, forwarding_fee_base_msat: 1000, cltv_expiry_delta: 6 * 12, // 6 blocks/hour * 12 hours - max_dust_htlc_exposure_msat: 5_000_000, + max_dust_htlc_exposure: MaxDustHTLCExposure::FeeRateMultiplier(10000), force_close_avoidance_max_fee_satoshis: 1000, + accept_underpaying_htlcs: false, } } } -impl_writeable_tlv_based!(ChannelConfig, { - (0, forwarding_fee_proportional_millionths, required), - (2, forwarding_fee_base_msat, required), - (4, cltv_expiry_delta, required), - (6, max_dust_htlc_exposure_msat, required), - // ChannelConfig serialized this field with a required type of 8 prior to the introduction of - // LegacyChannelConfig. To make sure that serialization is not compatible with this one, we use - // the next required type of 10, which if seen by the old serialization will always fail. - (10, force_close_avoidance_max_fee_satoshis, required), -}); +impl crate::util::ser::Writeable for ChannelConfig { + fn write(&self, writer: &mut W) -> Result<(), crate::io::Error> { + let max_dust_htlc_exposure_msat_fixed_limit = match self.max_dust_htlc_exposure { + MaxDustHTLCExposure::FixedLimitMsat(limit) => limit, + MaxDustHTLCExposure::FeeRateMultiplier(_) => 5_000_000, + }; + write_tlv_fields!(writer, { + (0, self.forwarding_fee_proportional_millionths, required), + (1, self.accept_underpaying_htlcs, (default_value, false)), + (2, self.forwarding_fee_base_msat, required), + (3, self.max_dust_htlc_exposure, required), + (4, self.cltv_expiry_delta, required), + (6, max_dust_htlc_exposure_msat_fixed_limit, required), + // ChannelConfig serialized this field with a required type of 8 prior to the introduction of + // LegacyChannelConfig. To make sure that serialization is not compatible with this one, we use + // the next required type of 10, which if seen by the old serialization will always fail. + (10, self.force_close_avoidance_max_fee_satoshis, required), + }); + Ok(()) + } +} + +impl crate::util::ser::Readable for ChannelConfig { + fn read(reader: &mut R) -> Result { + let mut forwarding_fee_proportional_millionths = 0; + let mut accept_underpaying_htlcs = false; + let mut forwarding_fee_base_msat = 1000; + let mut cltv_expiry_delta = 6 * 12; + let mut max_dust_htlc_exposure_msat = None; + let mut max_dust_htlc_exposure_enum = None; + let mut force_close_avoidance_max_fee_satoshis = 1000; + read_tlv_fields!(reader, { + (0, forwarding_fee_proportional_millionths, required), + (1, accept_underpaying_htlcs, (default_value, false)), + (2, forwarding_fee_base_msat, required), + (3, max_dust_htlc_exposure_enum, option), + (4, cltv_expiry_delta, required), + // Has always been written, but became optionally read in 0.0.116 + (6, max_dust_htlc_exposure_msat, option), + (10, force_close_avoidance_max_fee_satoshis, required), + }); + let max_dust_htlc_fixed_limit = max_dust_htlc_exposure_msat.unwrap_or(5_000_000); + let max_dust_htlc_exposure_msat = max_dust_htlc_exposure_enum + .unwrap_or(MaxDustHTLCExposure::FixedLimitMsat(max_dust_htlc_fixed_limit)); + Ok(Self { + forwarding_fee_proportional_millionths, + accept_underpaying_htlcs, + forwarding_fee_base_msat, + cltv_expiry_delta, + max_dust_htlc_exposure: max_dust_htlc_exposure_msat, + force_close_avoidance_max_fee_satoshis, + }) + } +} + +/// A parallel struct to [`ChannelConfig`] to define partial updates. +#[allow(missing_docs)] +pub struct ChannelConfigUpdate { + pub forwarding_fee_proportional_millionths: Option, + pub forwarding_fee_base_msat: Option, + pub cltv_expiry_delta: Option, + pub max_dust_htlc_exposure_msat: Option, + pub force_close_avoidance_max_fee_satoshis: Option, +} + +impl Default for ChannelConfigUpdate { + fn default() -> ChannelConfigUpdate { + ChannelConfigUpdate { + forwarding_fee_proportional_millionths: None, + forwarding_fee_base_msat: None, + cltv_expiry_delta: None, + max_dust_htlc_exposure_msat: None, + force_close_avoidance_max_fee_satoshis: None, + } + } +} + +impl From for ChannelConfigUpdate { + fn from(config: ChannelConfig) -> ChannelConfigUpdate { + ChannelConfigUpdate { + forwarding_fee_proportional_millionths: Some(config.forwarding_fee_proportional_millionths), + forwarding_fee_base_msat: Some(config.forwarding_fee_base_msat), + cltv_expiry_delta: Some(config.cltv_expiry_delta), + max_dust_htlc_exposure_msat: Some(config.max_dust_htlc_exposure), + force_close_avoidance_max_fee_satoshis: Some(config.force_close_avoidance_max_fee_satoshis), + } + } +} /// Legacy version of [`ChannelConfig`] that stored the static /// [`ChannelHandshakeConfig::announced_channel`] and @@ -450,12 +729,17 @@ impl Default for LegacyChannelConfig { impl crate::util::ser::Writeable for LegacyChannelConfig { fn write(&self, writer: &mut W) -> Result<(), crate::io::Error> { + let max_dust_htlc_exposure_msat_fixed_limit = match self.options.max_dust_htlc_exposure { + MaxDustHTLCExposure::FixedLimitMsat(limit) => limit, + MaxDustHTLCExposure::FeeRateMultiplier(_) => 5_000_000, + }; write_tlv_fields!(writer, { (0, self.options.forwarding_fee_proportional_millionths, required), - (1, self.options.max_dust_htlc_exposure_msat, (default_value, 5_000_000)), + (1, max_dust_htlc_exposure_msat_fixed_limit, required), (2, self.options.cltv_expiry_delta, required), (3, self.options.force_close_avoidance_max_fee_satoshis, (default_value, 1000)), (4, self.announced_channel, required), + (5, self.options.max_dust_htlc_exposure, required), (6, self.commit_upfront_shutdown_pubkey, required), (8, self.options.forwarding_fee_base_msat, required), }); @@ -466,28 +750,36 @@ impl crate::util::ser::Writeable for LegacyChannelConfig { impl crate::util::ser::Readable for LegacyChannelConfig { fn read(reader: &mut R) -> Result { let mut forwarding_fee_proportional_millionths = 0; - let mut max_dust_htlc_exposure_msat = 5_000_000; + let mut max_dust_htlc_exposure_msat_fixed_limit = None; let mut cltv_expiry_delta = 0; let mut force_close_avoidance_max_fee_satoshis = 1000; let mut announced_channel = false; let mut commit_upfront_shutdown_pubkey = false; let mut forwarding_fee_base_msat = 0; + let mut max_dust_htlc_exposure_enum = None; read_tlv_fields!(reader, { (0, forwarding_fee_proportional_millionths, required), - (1, max_dust_htlc_exposure_msat, (default_value, 5_000_000u64)), + // Has always been written, but became optionally read in 0.0.116 + (1, max_dust_htlc_exposure_msat_fixed_limit, option), (2, cltv_expiry_delta, required), (3, force_close_avoidance_max_fee_satoshis, (default_value, 1000u64)), (4, announced_channel, required), + (5, max_dust_htlc_exposure_enum, option), (6, commit_upfront_shutdown_pubkey, required), (8, forwarding_fee_base_msat, required), }); + let max_dust_htlc_exposure_msat_fixed_limit = + max_dust_htlc_exposure_msat_fixed_limit.unwrap_or(5_000_000); + let max_dust_htlc_exposure_msat = max_dust_htlc_exposure_enum + .unwrap_or(MaxDustHTLCExposure::FixedLimitMsat(max_dust_htlc_exposure_msat_fixed_limit)); Ok(Self { options: ChannelConfig { forwarding_fee_proportional_millionths, - max_dust_htlc_exposure_msat, + max_dust_htlc_exposure: max_dust_htlc_exposure_msat, cltv_expiry_delta, force_close_avoidance_max_fee_satoshis, forwarding_fee_base_msat, + accept_underpaying_htlcs: false, }, announced_channel, commit_upfront_shutdown_pubkey, @@ -497,8 +789,8 @@ impl crate::util::ser::Readable for LegacyChannelConfig { /// Top-level config which holds ChannelHandshakeLimits and ChannelConfig. /// -/// Default::default() provides sane defaults for most configurations -/// (but currently with 0 relay fees!) +/// `Default::default()` provides sane defaults for most configurations +/// (but currently with zero relay fees!) #[derive(Copy, Clone, Debug)] pub struct UserConfig { /// Channel handshake config that we propose to our counterparty. @@ -507,13 +799,13 @@ pub struct UserConfig { pub channel_handshake_limits: ChannelHandshakeLimits, /// Channel config which affects behavior during channel lifetime. pub channel_config: ChannelConfig, - /// If this is set to false, we will reject any HTLCs which were to be forwarded over private + /// If this is set to `false`, we will reject any HTLCs which were to be forwarded over private /// channels. This prevents us from taking on HTLC-forwarding risk when we intend to run as a /// node which is not online reliably. /// /// For nodes which are not online reliably, you should set all channels to *not* be announced /// (using [`ChannelHandshakeConfig::announced_channel`] and - /// [`ChannelHandshakeLimits::force_announced_channel_preference`]) and set this to false to + /// [`ChannelHandshakeLimits::force_announced_channel_preference`]) and set this to `false` to /// ensure you are not exposed to any forwarding risk. /// /// Note that because you cannot change a channel's announced state after creation, there is no @@ -522,36 +814,62 @@ pub struct UserConfig { /// all your channels and open new ones. For privacy, you should also change your node_id /// (swapping all private and public key material for new ones) at that time. /// - /// Default value: false. + /// Default value: `false` pub accept_forwards_to_priv_channels: bool, - /// If this is set to false, we do not accept inbound requests to open a new channel. - /// Default value: true. + /// If this is set to `false`, we do not accept inbound requests to open a new channel. + /// + /// Default value: `true` pub accept_inbound_channels: bool, - /// If this is set to true, the user needs to manually accept inbound requests to open a new + /// If this is set to `true`, the user needs to manually accept inbound requests to open a new /// channel. /// - /// When set to true, [`Event::OpenChannelRequest`] will be triggered once a request to open a + /// When set to `true`, [`Event::OpenChannelRequest`] will be triggered once a request to open a /// new inbound channel is received through a [`msgs::OpenChannel`] message. In that case, a /// [`msgs::AcceptChannel`] message will not be sent back to the counterparty node unless the /// user explicitly chooses to accept the request. /// - /// Default value: false. + /// Default value: `false` /// /// [`Event::OpenChannelRequest`]: crate::events::Event::OpenChannelRequest /// [`msgs::OpenChannel`]: crate::ln::msgs::OpenChannel /// [`msgs::AcceptChannel`]: crate::ln::msgs::AcceptChannel pub manually_accept_inbound_channels: bool, - /// If this is set to true, LDK will intercept HTLCs that are attempting to be forwarded over + /// If this is set to `true`, LDK will intercept HTLCs that are attempting to be forwarded over /// fake short channel ids generated via [`ChannelManager::get_intercept_scid`]. Upon HTLC /// intercept, LDK will generate an [`Event::HTLCIntercepted`] which MUST be handled by the user. /// - /// Setting this to true may break backwards compatibility with LDK versions < 0.0.113. + /// Setting this to `true` may break backwards compatibility with LDK versions < 0.0.113. /// - /// Default value: false. + /// Default value: `false` /// /// [`ChannelManager::get_intercept_scid`]: crate::ln::channelmanager::ChannelManager::get_intercept_scid /// [`Event::HTLCIntercepted`]: crate::events::Event::HTLCIntercepted pub accept_intercept_htlcs: bool, + /// If this is set to `false`, when receiving a keysend payment we'll fail it if it has multiple + /// parts. If this is set to `true`, we'll accept the payment. + /// + /// Setting this to `true` will break backwards compatibility upon downgrading to an LDK + /// version prior to 0.0.116 while receiving an MPP keysend. If we have already received an MPP + /// keysend, downgrading will cause us to fail to deserialize [`ChannelManager`]. + /// + /// Default value: `false` + /// + /// [`ChannelManager`]: crate::ln::channelmanager::ChannelManager + pub accept_mpp_keysend: bool, + /// If this is set to `true`, the user needs to manually pay [`Bolt12Invoice`]s when received. + /// + /// When set to `true`, [`Event::InvoiceReceived`] will be generated for each received + /// [`Bolt12Invoice`] instead of being automatically paid after verification. Use + /// [`ChannelManager::send_payment_for_bolt12_invoice`] to pay the invoice or + /// [`ChannelManager::abandon_payment`] to abandon the associated payment. + /// + /// Default value: `false` + /// + /// [`Bolt12Invoice`]: crate::offers::invoice::Bolt12Invoice + /// [`Event::InvoiceReceived`]: crate::events::Event::InvoiceReceived + /// [`ChannelManager::send_payment_for_bolt12_invoice`]: crate::ln::channelmanager::ChannelManager::send_payment_for_bolt12_invoice + /// [`ChannelManager::abandon_payment`]: crate::ln::channelmanager::ChannelManager::abandon_payment + pub manually_handle_bolt12_invoices: bool, } impl Default for UserConfig { @@ -564,6 +882,28 @@ impl Default for UserConfig { accept_inbound_channels: true, manually_accept_inbound_channels: false, accept_intercept_htlcs: false, + accept_mpp_keysend: false, + manually_handle_bolt12_invoices: false, } } } + +// When fuzzing, we want to allow the fuzzer to pick any configuration parameters. Thus, we +// implement Readable here in a naive way (which is a bit easier for the fuzzer to handle). We +// don't really want to ever expose this to users (if we did we'd want to use TLVs). +#[cfg(fuzzing)] +impl Readable for UserConfig { + fn read(reader: &mut R) -> Result { + Ok(Self { + channel_handshake_config: Readable::read(reader)?, + channel_handshake_limits: Readable::read(reader)?, + channel_config: Readable::read(reader)?, + accept_forwards_to_priv_channels: Readable::read(reader)?, + accept_inbound_channels: Readable::read(reader)?, + manually_accept_inbound_channels: Readable::read(reader)?, + accept_intercept_htlcs: Readable::read(reader)?, + accept_mpp_keysend: Readable::read(reader)?, + manually_handle_bolt12_invoices: Readable::read(reader)?, + }) + } +}