+// This file is Copyright its original authors, visible in version control
+// history.
+//
+// This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
+// or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
+// You may not use this file except in accordance with one or both of these
+// licenses.
+
//! Various user-configurable channel limits and settings which ChannelManager
//! applies for you.
use ln::channelmanager::{BREAKDOWN_TIMEOUT, MAX_LOCAL_BREAKDOWN_TIMEOUT};
-/// Top-level config which holds ChannelHandshakeLimits and ChannelConfig.
-///
-/// Default::default() provides sane defaults for most configurations
-/// (but currently with 0 relay fees!)
-#[derive(Clone, Debug)]
-pub struct UserConfig {
- /// Channel config that we propose to our counterparty.
- pub own_channel_config: ChannelHandshakeConfig,
- /// Limits applied to our counterparty's proposed channel config settings.
- pub peer_channel_config_limits: ChannelHandshakeLimits,
- /// Channel config which affects behavior during channel lifetime.
- pub channel_options: ChannelConfig,
-}
-
-impl Default for UserConfig {
- fn default() -> Self {
- UserConfig {
- own_channel_config: ChannelHandshakeConfig::default(),
- peer_channel_config_limits: ChannelHandshakeLimits::default(),
- channel_options: ChannelConfig::default(),
- }
- }
-}
-
/// Configuration we set when applicable.
///
/// Default::default() provides sane defaults.
-#[derive(Clone, Debug)]
+#[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
///
/// Default value: 6.
pub minimum_depth: u32,
- /// Set to the amount of time we require our counterparty to wait to claim their money.
+ /// Set to the number of blocks we require our counterparty to wait to claim their money (ie
+ /// the number of blocks we have to punish our counterparty if they broadcast a revoked
+ /// transaction).
///
- /// It's one of the main parameter of our security model. We (or one of our watchtowers) MUST
- /// be online to check for peer having broadcast a revoked transaction to steal our funds
- /// at least once every our_to_self_delay blocks.
+ /// This is one of the main parameters of our security model. We (or one of our watchtowers) MUST
+ /// be online to check for revoked transactions on-chain at least once every our_to_self_delay
+ /// blocks (minus some margin to allow us enough time to broadcast and confirm a transaction,
+ /// possibly with time in between to RBF the spending transaction).
///
/// Meanwhile, asking for a too high delay, we bother peer to freeze funds for nothing in
/// case of an honest unilateral channel close, which implicitly decrease the economic value of
/// our channel.
///
- /// Default value: BREAKDOWN_TIMEOUT (currently 144), 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.
///
///
/// 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.
///
/// 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: MAX_LOCAL_BREAKDOWN_TIMEOUT (1008), 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)
+ /// 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
}
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 is analogous to [`ChannelHandshakeConfig::our_to_self_delay`] but applies to in-flight
+ /// HTLC balance when a channel appears on-chain whereas
+ /// [`ChannelHandshakeConfig::our_to_self_delay`] applies to the remaining
+ /// (non-HTLC-encumbered) balance.
+ ///
+ /// Thus, for HTLC-encumbered balances to be enforced on-chain when a channel is force-closed,
+ /// we (or one of our watchtowers) MUST be online to check for broadcast of the current
+ /// commitment transaction at least once per this many blocks (minus some margin to allow us
+ /// 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.
+ ///
+ /// [`MIN_CLTV_EXPIRY_DELTA`]: crate::ln::channelmanager::MIN_CLTV_EXPIRY_DELTA
+ pub cltv_expiry_delta: u16,
/// Set to announce the channel publicly and notify all nodes that they can route via this
/// channel.
///
/// 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+1+1, {
- fee_proportional_millionths,
- 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.
+///
+/// Default::default() provides sane defaults for most configurations
+/// (but currently with 0 relay fees!)
+#[derive(Copy, Clone, Debug)]
+pub struct UserConfig {
+ /// Channel config that we propose to our counterparty.
+ pub own_channel_config: ChannelHandshakeConfig,
+ /// Limits applied to our counterparty's proposed channel config settings.
+ 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,
+}
+
+impl Default for UserConfig {
+ fn default() -> Self {
+ UserConfig {
+ own_channel_config: ChannelHandshakeConfig::default(),
+ peer_channel_config_limits: ChannelHandshakeLimits::default(),
+ channel_options: ChannelConfig::default(),
+ accept_forwards_to_priv_channels: false,
+ }
+ }
+}
projects / rust-lightning / blobdiff