1 //! Various user-configurable channel limits and settings which ChannelManager
4 use ln::channelmanager::{BREAKDOWN_TIMEOUT, MAX_LOCAL_BREAKDOWN_TIMEOUT};
6 /// Top-level config which holds ChannelHandshakeLimits and ChannelConfig.
8 /// Default::default() provides sane defaults for most configurations
9 /// (but currently with 0 relay fees!)
10 #[derive(Clone, Debug)]
11 pub struct UserConfig {
12 /// Channel config that we propose to our counterparty.
13 pub own_channel_config: ChannelHandshakeConfig,
14 /// Limits applied to our counterparty's proposed channel config settings.
15 pub peer_channel_config_limits: ChannelHandshakeLimits,
16 /// Channel config which affects behavior during channel lifetime.
17 pub channel_options: ChannelConfig,
20 impl Default for UserConfig {
21 fn default() -> Self {
23 own_channel_config: ChannelHandshakeConfig::default(),
24 peer_channel_config_limits: ChannelHandshakeLimits::default(),
25 channel_options: ChannelConfig::default(),
30 /// Configuration we set when applicable.
32 /// Default::default() provides sane defaults.
33 #[derive(Clone, Debug)]
34 pub struct ChannelHandshakeConfig {
35 /// Confirmations we will wait for before considering the channel locked in.
36 /// Applied only for inbound channels (see ChannelHandshakeLimits::max_minimum_depth for the
37 /// equivalent limit applied to outbound channels).
40 pub minimum_depth: u32,
41 /// Set to the amount of time we require our counterparty to wait to claim their money.
43 /// It's one of the main parameter of our security model. We (or one of our watchtowers) MUST
44 /// be online to check for peer having broadcast a revoked transaction to steal our funds
45 /// at least once every our_to_self_delay blocks.
47 /// Meanwhile, asking for a too high delay, we bother peer to freeze funds for nothing in
48 /// case of an honest unilateral channel close, which implicitly decrease the economic value of
51 /// Default value: BREAKDOWN_TIMEOUT (currently 144), we enforce it as a minimum at channel
52 /// opening so you can tweak config to ask for more security, not less.
53 pub our_to_self_delay: u16,
56 impl Default for ChannelHandshakeConfig {
57 fn default() -> ChannelHandshakeConfig {
58 ChannelHandshakeConfig {
60 our_to_self_delay: BREAKDOWN_TIMEOUT,
65 /// Optional channel limits which are applied during channel creation.
67 /// These limits are only applied to our counterparty's limits, not our own.
69 /// Use 0/<type>::max_value() as appropriate to skip checking.
71 /// Provides sane defaults for most configurations.
73 /// Most additional limits are disabled except those with which specify a default in individual
74 /// field documentation. Note that this may result in barely-usable channels, but since they
75 /// are applied mostly only to incoming channels that's not much of a problem.
76 #[derive(Copy, Clone, Debug)]
77 pub struct ChannelHandshakeLimits {
78 /// Minimum allowed satoshis when a channel is funded, this is supplied by the sender and so
79 /// only applies to inbound channels.
82 pub min_funding_satoshis: u64,
83 /// The remote node sets a limit on the minimum size of HTLCs we can send to them. This allows
84 /// you to limit the maximum minimum-size they can require.
86 /// Default value: u64::max_value.
87 pub max_htlc_minimum_msat: u64,
88 /// The remote node sets a limit on the maximum value of pending HTLCs to them at any given
89 /// time to limit their funds exposure to HTLCs. This allows you to set a minimum such value.
92 pub min_max_htlc_value_in_flight_msat: u64,
93 /// The remote node will require we keep a certain amount in direct payment to ourselves at all
94 /// time, ensuring that we are able to be punished if we broadcast an old state. This allows to
95 /// you limit the amount which we will have to keep to ourselves (and cannot use for HTLCs).
97 /// Default value: u64::max_value.
98 pub max_channel_reserve_satoshis: u64,
99 /// The remote node sets a limit on the maximum number of pending HTLCs to them at any given
100 /// time. This allows you to set a minimum such value.
102 /// Default value: 0.
103 pub min_max_accepted_htlcs: u16,
104 /// Outputs below a certain value will not be added to on-chain transactions. The dust value is
105 /// required to always be higher than this value so this only applies to HTLC outputs (and
106 /// potentially to-self outputs before any payments have been made).
107 /// Thus, HTLCs below this amount plus HTLC transaction fees are not enforceable on-chain.
108 /// This setting allows you to set a minimum dust limit for their commitment transactions,
109 /// reflecting the reality that tiny outputs are not considered standard transactions and will
110 /// not propagate through the Bitcoin network.
112 /// Default value: 546, the current dust limit on the Bitcoin network.
113 pub min_dust_limit_satoshis: u64,
114 /// Maximum allowed threshold above which outputs will not be generated in their commitment
116 /// HTLCs below this amount plus HTLC transaction fees are not enforceable on-chain.
118 /// Default value: u64::max_value.
119 pub max_dust_limit_satoshis: u64,
120 /// Before a channel is usable the funding transaction will need to be confirmed by at least a
121 /// certain number of blocks, specified by the node which is not the funder (as the funder can
122 /// assume they aren't going to double-spend themselves).
123 /// This config allows you to set a limit on the maximum amount of time to wait.
125 /// Default value: 144, or roughly one day and only applies to outbound channels.
126 pub max_minimum_depth: u32,
127 /// Set to force the incoming channel to match our announced channel preference in
130 /// Default value: true, to make the default that no announced channels are possible (which is
131 /// appropriate for any nodes which are not online very reliably).
132 pub force_announced_channel_preference: bool,
133 /// Set to the amount of time we're willing to wait to claim money back to us.
135 /// Not checking this value would be a security issue, as our peer would be able to set it to
136 /// max relative lock-time (a year) and we would "lose" money as it would be locked for a long time.
138 /// Default value: MAX_LOCAL_BREAKDOWN_TIMEOUT (1008), which we also enforce as a maximum value
139 /// so you can tweak config to reduce the loss of having useless locked funds (if your peer accepts)
140 pub their_to_self_delay: u16
143 impl Default for ChannelHandshakeLimits {
144 fn default() -> Self {
145 ChannelHandshakeLimits {
146 min_funding_satoshis: 0,
147 max_htlc_minimum_msat: <u64>::max_value(),
148 min_max_htlc_value_in_flight_msat: 0,
149 max_channel_reserve_satoshis: <u64>::max_value(),
150 min_max_accepted_htlcs: 0,
151 min_dust_limit_satoshis: 546,
152 max_dust_limit_satoshis: <u64>::max_value(),
153 max_minimum_depth: 144,
154 force_announced_channel_preference: true,
155 their_to_self_delay: MAX_LOCAL_BREAKDOWN_TIMEOUT,
160 /// Options which apply on a per-channel basis and may change at runtime or based on negotiation
161 /// with our counterparty.
162 #[derive(Copy, Clone, Debug)]
163 pub struct ChannelConfig {
164 /// Amount (in millionths of a satoshi) the channel will charge per transferred satoshi.
165 /// This may be allowed to change at runtime in a later update, however doing so must result in
166 /// update messages sent to notify all nodes of our updated relay fee.
168 /// Default value: 0.
169 pub fee_proportional_millionths: u32,
170 /// Set to announce the channel publicly and notify all nodes that they can route via this
173 /// This should only be set to true for nodes which expect to be online reliably.
175 /// As the node which funds a channel picks this value this will only apply for new outbound
176 /// channels unless ChannelHandshakeLimits::force_announced_channel_preferences is set.
178 /// This cannot be changed after the initial channel handshake.
180 /// Default value: false.
181 pub announced_channel: bool,
182 /// When set, we commit to an upfront shutdown_pubkey at channel open. If our counterparty
183 /// supports it, they will then enforce the mutual-close output to us matches what we provided
184 /// at intialization, preventing us from closing to an alternate pubkey.
186 /// This is set to true by default to provide a slight increase in security, though ultimately
187 /// any attacker who is able to take control of a channel can just as easily send the funds via
188 /// lightning payments, so we never require that our counterparties support this option.
190 /// This cannot be changed after a channel has been initialized.
192 /// Default value: true.
193 pub commit_upfront_shutdown_pubkey: bool
196 impl Default for ChannelConfig {
197 /// Provides sane defaults for most configurations (but with zero relay fees!).
198 fn default() -> Self {
200 fee_proportional_millionths: 0,
201 announced_channel: false,
202 commit_upfront_shutdown_pubkey: true,
207 //Add write and readable traits to channelconfig
208 impl_writeable!(ChannelConfig, 8+1+1, {
209 fee_proportional_millionths,
211 commit_upfront_shutdown_pubkey