X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=lightning%2Fsrc%2Futil%2Fconfig.rs;h=0f625098f79f9030ae25ddc1979cc6b5fcba30ae;hb=e49f738630559ce2eaa97689f1b4d37546fc7020;hp=c76747cbbf8e1de83ab1ac381ae09c8c266de5d3;hpb=9e03d2bc7a5d45c56722b40348b143403167142c;p=rust-lightning diff --git a/lightning/src/util/config.rs b/lightning/src/util/config.rs index c76747cb..0f625098 100644 --- a/lightning/src/util/config.rs +++ b/lightning/src/util/config.rs @@ -1,36 +1,22 @@ +// This file is Copyright its original authors, visible in version control +// history. +// +// This file is licensed under the Apache License, Version 2.0 or the MIT license +// , 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::channel::MAX_FUNDING_SATOSHIS_NO_WUMBO; 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 @@ -38,18 +24,21 @@ pub struct ChannelHandshakeConfig { /// /// 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. /// @@ -59,6 +48,28 @@ pub struct ChannelHandshakeConfig { /// 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, + /// 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 { @@ -67,6 +78,7 @@ impl Default for ChannelHandshakeConfig { minimum_depth: 6, our_to_self_delay: BREAKDOWN_TIMEOUT, our_htlc_minimum_msat: 1, + negotiate_scid_privacy: false, } } } @@ -84,11 +96,16 @@ impl Default for ChannelHandshakeConfig { /// 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. /// @@ -110,22 +127,6 @@ pub struct ChannelHandshakeLimits { /// /// 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). @@ -133,19 +134,22 @@ pub struct ChannelHandshakeLimits { /// /// 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 } @@ -153,12 +157,11 @@ impl Default for ChannelHandshakeLimits { fn default() -> Self { ChannelHandshakeLimits { min_funding_satoshis: 0, + max_funding_satoshis: MAX_FUNDING_SATOSHIS_NO_WUMBO, max_htlc_minimum_msat: ::max_value(), min_max_htlc_value_in_flight_msat: 0, max_channel_reserve_satoshis: ::max_value(), min_max_accepted_htlcs: 0, - min_dust_limit_satoshis: 546, - max_dust_limit_satoshis: ::max_value(), max_minimum_depth: 144, force_announced_channel_preference: true, their_to_self_delay: MAX_LOCAL_BREAKDOWN_TIMEOUT, @@ -170,19 +173,53 @@ impl Default for ChannelHandshakeLimits { /// 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. /// @@ -199,23 +236,130 @@ pub struct ChannelConfig { /// 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, + /// 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 { + 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, + accept_inbound_channels: true, + manually_accept_inbound_channels: false, + } + } +}