//! Various user-configurable channel limits and settings which ChannelManager
//! applies for you.
+use ln::channel::MAX_FUNDING_SATOSHIS_NO_WUMBO;
use ln::channelmanager::{BREAKDOWN_TIMEOUT, MAX_LOCAL_BREAKDOWN_TIMEOUT};
/// Configuration we set when applicable.
/// 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.
+ ///
+ /// This can be set to a value between 1-100, where the value corresponds to the percent of the
+ /// channel value in whole percentages.
+ ///
+ /// Note that:
+ /// * 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`.
+ ///
+ /// * This caps the total value for inbound HTLCs in-flight only, and there's currently
+ /// no way to configure the cap for the total value of outbound HTLCs in-flight.
+ ///
+ /// * The requirements for your node being online to ensure the safety of HTLC-encumbered funds
+ /// are different from the non-HTLC-encumbered funds. This makes this an important knob to
+ /// restrict exposure to loss due to being offline for too long.
+ /// 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.
+ 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
+ /// our real on-chain channel UTXO in each invoice and requiring that our counterparty only
+ /// relay HTLCs to us using the channel's SCID alias.
+ ///
+ /// If this option is set, channels may be created that will not be readable by LDK versions
+ /// prior to 0.0.106, causing [`ChannelManager`]'s read method to return a
+ /// [`DecodeError:InvalidValue`].
+ ///
+ /// Note that setting this to true does *not* prevent us from opening channels with
+ /// counterparties that do not support the `scid_alias` option; we will simply fall back to a
+ /// private channel without that option.
+ ///
+ /// Ignored if the channel is negotiated to be announced, see
+ /// [`ChannelConfig::announced_channel`] and
+ /// [`ChannelHandshakeLimits::force_announced_channel_preference`] for more.
+ ///
+ /// 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
+ pub negotiate_scid_privacy: bool,
}
impl Default for ChannelHandshakeConfig {
minimum_depth: 6,
our_to_self_delay: BREAKDOWN_TIMEOUT,
our_htlc_minimum_msat: 1,
+ max_inbound_htlc_value_in_flight_percent_of_channel: 10,
+ negotiate_scid_privacy: false,
}
}
}
/// are applied mostly only to incoming channels that's not much of a problem.
#[derive(Copy, Clone, Debug)]
pub struct ChannelHandshakeLimits {
- /// Minimum allowed satoshis when a channel is funded, this is supplied by the sender and so
+ /// Minimum allowed satoshis when a channel is funded. This is supplied by the sender and so
/// only applies to inbound channels.
///
/// 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.
+ 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: 0.
pub min_max_accepted_htlcs: u16,
- /// Outputs below a certain value will not be added to on-chain transactions. The dust value is
- /// required to always be higher than this value so this only applies to HTLC outputs (and
- /// potentially to-self outputs before any payments have been made).
- /// Thus, HTLCs below this amount plus HTLC transaction fees are not enforceable on-chain.
- /// This setting allows you to set a minimum dust limit for their commitment transactions,
- /// reflecting the reality that tiny outputs are not considered standard transactions and will
- /// not propagate through the Bitcoin network.
- ///
- /// Default value: 546, the current dust limit on the Bitcoin network.
- pub min_dust_limit_satoshis: u64,
- /// Maximum allowed threshold above which outputs will not be generated in their commitment
- /// transactions.
- /// HTLCs below this amount plus HTLC transaction fees are not enforceable on-chain.
- ///
- /// Default value: u64::max_value.
- pub max_dust_limit_satoshis: u64,
/// 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).
///
/// Default value: 144, or roughly one day and only applies to outbound channels.
pub max_minimum_depth: u32,
- /// Set to force the incoming channel to match our announced channel preference in
- /// ChannelConfig.
+ /// Set to force an incoming channel to match our announced channel preference in
+ /// [`ChannelConfig::announced_channel`].
+ ///
+ /// For a node which is not online reliably, this should be set to true and
+ /// [`ChannelConfig::announced_channel`] set to false, ensuring that no announced (aka public)
+ /// channels will ever be opened.
///
- /// Default value: true, to make the default that no announced channels are possible (which is
- /// appropriate for any nodes which are not online very reliably).
+ /// 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.
///
fn default() -> Self {
ChannelHandshakeLimits {
min_funding_satoshis: 0,
+ max_funding_satoshis: MAX_FUNDING_SATOSHIS_NO_WUMBO,
max_htlc_minimum_msat: <u64>::max_value(),
min_max_htlc_value_in_flight_msat: 0,
max_channel_reserve_satoshis: <u64>::max_value(),
min_max_accepted_htlcs: 0,
- min_dust_limit_satoshis: 546,
- max_dust_limit_satoshis: <u64>::max_value(),
max_minimum_depth: 144,
force_announced_channel_preference: true,
their_to_self_delay: MAX_LOCAL_BREAKDOWN_TIMEOUT,
/// with our counterparty.
#[derive(Copy, Clone, Debug)]
pub struct ChannelConfig {
- /// Amount (in millionths of a satoshi) the channel will charge per transferred satoshi.
+ /// Amount (in millionths of a satoshi) charged per satoshi for payments forwarded outbound
+ /// over the channel.
/// 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.
- pub fee_proportional_millionths: u32,
+ 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`].
+ /// 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.
+ ///
+ /// The default value of a single satoshi roughly matches the market rate on many routing nodes
+ /// as of July 2021. Adjusting it upwards or downwards may change whether nodes route through
+ /// this node.
+ ///
+ /// Default value: 1000.
+ ///
+ /// [`forwarding_fee_proportional_millionths`]: ChannelConfig::forwarding_fee_proportional_millionths
+ pub forwarding_fee_base_msat: u32,
/// The difference in the CLTV value between incoming HTLCs and an outbound HTLC forwarded over
/// the channel this config applies to.
///
/// This should only be set to true for nodes which expect to be online reliably.
///
/// As the node which funds a channel picks this value this will only apply for new outbound
- /// channels unless ChannelHandshakeLimits::force_announced_channel_preferences is set.
+ /// channels unless [`ChannelHandshakeLimits::force_announced_channel_preference`] is set.
///
/// This cannot be changed after the initial channel handshake.
///
/// This cannot be changed after a channel has been initialized.
///
/// Default value: true.
- pub commit_upfront_shutdown_pubkey: bool
+ pub commit_upfront_shutdown_pubkey: bool,
+ /// Limit our total exposure to in-flight HTLCs which are burned to fees as they are too
+ /// small to claim on-chain.
+ ///
+ /// 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
+ /// channel is force-closed.
+ ///
+ /// 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,
+ /// The additional fee we're willing to pay to avoid waiting for the counterparty's
+ /// `to_self_delay` to reclaim funds.
+ ///
+ /// When we close a channel cooperatively with our counterparty, we negotiate a fee for the
+ /// closing transaction which both sides find acceptable, ultimately paid by the channel
+ /// 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
+ /// 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
+ /// 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.
+ /// Thus, this value is ignored when we are not the funder.
+ ///
+ /// Default value: 1000 satoshis.
+ ///
+ /// [`Normal`]: crate::chain::chaininterface::ConfirmationTarget::Normal
+ /// [`Background`]: crate::chain::chaininterface::ConfirmationTarget::Background
+ pub force_close_avoidance_max_fee_satoshis: u64,
}
impl Default for ChannelConfig {
/// Provides sane defaults for most configurations (but with zero relay fees!).
fn default() -> Self {
ChannelConfig {
- fee_proportional_millionths: 0,
+ forwarding_fee_proportional_millionths: 0,
+ forwarding_fee_base_msat: 1000,
cltv_expiry_delta: 6 * 12, // 6 blocks/hour * 12 hours
announced_channel: false,
commit_upfront_shutdown_pubkey: true,
+ max_dust_htlc_exposure_msat: 5_000_000,
+ force_close_avoidance_max_fee_satoshis: 1000,
}
}
}
-//Add write and readable traits to channelconfig
-impl_writeable!(ChannelConfig, 8+2+1+1, {
- fee_proportional_millionths,
- cltv_expiry_delta,
- announced_channel,
- commit_upfront_shutdown_pubkey
+impl_writeable_tlv_based!(ChannelConfig, {
+ (0, forwarding_fee_proportional_millionths, required),
+ (1, max_dust_htlc_exposure_msat, (default_value, 5_000_000)),
+ (2, cltv_expiry_delta, required),
+ (3, force_close_avoidance_max_fee_satoshis, (default_value, 1000)),
+ (4, announced_channel, required),
+ (6, commit_upfront_shutdown_pubkey, required),
+ (8, forwarding_fee_base_msat, required),
});
/// Top-level config which holds ChannelHandshakeLimits and ChannelConfig.
pub peer_channel_config_limits: ChannelHandshakeLimits,
/// Channel config which affects behavior during channel lifetime.
pub channel_options: ChannelConfig,
+ /// 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 [`ChannelConfig::announced_channel`] and
+ /// [`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
+ /// way to disable forwarding on public channels retroactively. Thus, in order to change a node
+ /// from a publicly-announced forwarding node to a private non-forwarding node you must close
+ /// 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.
+ 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.
+ pub accept_inbound_channels: bool,
+ /// 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
+ /// 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.
+ ///
+ /// [`Event::OpenChannelRequest`]: crate::util::events::Event::OpenChannelRequest
+ /// [`msgs::OpenChannel`]: crate::ln::msgs::OpenChannel
+ /// [`msgs::AcceptChannel`]: crate::ln::msgs::AcceptChannel
+ pub manually_accept_inbound_channels: bool,
}
impl Default for UserConfig {
own_channel_config: ChannelHandshakeConfig::default(),
peer_channel_config_limits: ChannelHandshakeLimits::default(),
channel_options: ChannelConfig::default(),
+ accept_forwards_to_priv_channels: false,
+ accept_inbound_channels: true,
+ manually_accept_inbound_channels: false,
}
}
}
projects / rust-lightning / blobdiff