From: Elias Rohrer Date: Fri, 24 Jun 2022 08:53:49 +0000 (+0200) Subject: Refactor `max_mpp_path_count` to `max_path_count` X-Git-Tag: v0.0.110~23^2~1 X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=commitdiff_plain;h=790abc540d46053cacc03893e92ad57454900e94;p=rust-lightning Refactor `max_mpp_path_count` to `max_path_count` Using this field just for MPP doesn't make sense when it could intuitively also be used to indicate single-path payments. We therefore rename `max_mpp_path_count` to `max_path_count` and make sure that a value of 1 ensures MPP is not even tried. --- diff --git a/lightning/src/routing/router.rs b/lightning/src/routing/router.rs index 420a473ff..e5377dcbb 100644 --- a/lightning/src/routing/router.rs +++ b/lightning/src/routing/router.rs @@ -176,10 +176,10 @@ impl_writeable_tlv_based!(RouteParameters, { /// Maximum total CTLV difference we allow for a full payment path. pub const DEFAULT_MAX_TOTAL_CLTV_EXPIRY_DELTA: u32 = 1008; -/// Maximum number of paths we allow an MPP payment to have. +/// Maximum number of paths we allow an (MPP) payment to have. // The default limit is currently set rather arbitrary - there aren't any real fundamental path-count // limits, but for now more than 10 paths likely carries too much one-path failure. -pub const DEFAULT_MAX_MPP_PATH_COUNT: u8 = 10; +pub const DEFAULT_MAX_PATH_COUNT: u8 = 10; // The median hop CLTV expiry delta currently seen in the network. const MEDIAN_HOP_CLTV_EXPIRY_DELTA: u32 = 40; @@ -222,16 +222,16 @@ pub struct PaymentParameters { /// Defaults to [`DEFAULT_MAX_TOTAL_CLTV_EXPIRY_DELTA`]. pub max_total_cltv_expiry_delta: u32, - /// The maximum number of paths that may be used by MPP payments. - /// Defaults to [`DEFAULT_MAX_MPP_PATH_COUNT`]. - pub max_mpp_path_count: u8, + /// The maximum number of paths that may be used by (MPP) payments. + /// Defaults to [`DEFAULT_MAX_PATH_COUNT`]. + pub max_path_count: u8, } impl_writeable_tlv_based!(PaymentParameters, { (0, payee_pubkey, required), (1, max_total_cltv_expiry_delta, (default_value, DEFAULT_MAX_TOTAL_CLTV_EXPIRY_DELTA)), (2, features, option), - (3, max_mpp_path_count, (default_value, DEFAULT_MAX_MPP_PATH_COUNT)), + (3, max_path_count, (default_value, DEFAULT_MAX_PATH_COUNT)), (4, route_hints, vec_type), (6, expiry_time, option), }); @@ -245,7 +245,7 @@ impl PaymentParameters { route_hints: vec![], expiry_time: None, max_total_cltv_expiry_delta: DEFAULT_MAX_TOTAL_CLTV_EXPIRY_DELTA, - max_mpp_path_count: DEFAULT_MAX_MPP_PATH_COUNT, + max_path_count: DEFAULT_MAX_PATH_COUNT, } } @@ -282,11 +282,11 @@ impl PaymentParameters { Self { max_total_cltv_expiry_delta, ..self } } - /// Includes a limit for the maximum number of payment paths that may be used by MPP. + /// Includes a limit for the maximum number of payment paths that may be used. /// /// (C-not exported) since bindings don't support move semantics - pub fn with_max_mpp_path_count(self, max_mpp_path_count: u8) -> Self { - Self { max_mpp_path_count, ..self } + pub fn with_max_path_count(self, max_path_count: u8) -> Self { + Self { max_path_count, ..self } } } @@ -800,10 +800,16 @@ where L::Target: Logger { let network_channels = network_graph.channels(); let network_nodes = network_graph.nodes(); + if payment_params.max_path_count == 0 { + return Err(LightningError{err: "Can't find a route with no paths allowed.".to_owned(), action: ErrorAction::IgnoreError}); + } + // Allow MPP only if we have a features set from somewhere that indicates the payee supports // it. If the payee supports it they're supposed to include it in the invoice, so that should // work reliably. - let allow_mpp = if let Some(features) = &payment_params.features { + let allow_mpp = if payment_params.max_path_count == 1 { + false + } else if let Some(features) = &payment_params.features { features.supports_basic_mpp() } else if let Some(node) = network_nodes.get(&payee_node_id) { if let Some(node_info) = node.announcement_info.as_ref() { @@ -811,10 +817,6 @@ where L::Target: Logger { } else { false } } else { false }; - if allow_mpp && payment_params.max_mpp_path_count == 0 { - return Err(LightningError{err: "Can't find an MPP route with no paths allowed.".to_owned(), action: ErrorAction::IgnoreError}); - } - log_trace!(logger, "Searching for a route from payer {} to payee {} {} MPP and {} first hops {}overriding the network graph", our_node_pubkey, payment_params.payee_pubkey, if allow_mpp { "with" } else { "without" }, first_hops.map(|hops| hops.len()).unwrap_or(0), if first_hops.is_some() { "" } else { "not " }); @@ -872,10 +874,10 @@ where L::Target: Logger { // Taking too many smaller paths also increases the chance of payment failure. // Thus to avoid this effect, we require from our collected links to provide // at least a minimal contribution to the recommended value yet-to-be-fulfilled. - // This requirement is currently set to be 1/max_mpp_path_count of the payment + // This requirement is currently set to be 1/max_path_count of the payment // value to ensure we only ever return routes that do not violate this limit. let minimal_value_contribution_msat: u64 = if allow_mpp { - (final_value_msat + (payment_params.max_mpp_path_count as u64 - 1)) / payment_params.max_mpp_path_count as u64 + (final_value_msat + (payment_params.max_path_count as u64 - 1)) / payment_params.max_path_count as u64 } else { final_value_msat }; @@ -1694,7 +1696,7 @@ where L::Target: Logger { selected_paths.push(path); } // Make sure we would never create a route with more paths than we allow. - debug_assert!(selected_paths.len() <= payment_params.max_mpp_path_count.into()); + debug_assert!(selected_paths.len() <= payment_params.max_path_count.into()); if let Some(features) = &payment_params.features { for path in selected_paths.iter_mut() { @@ -4119,20 +4121,20 @@ mod tests { } { - // Attempt to route while setting max_mpp_path_count to 0 results in a failure. - let zero_payment_params = payment_params.clone().with_max_mpp_path_count(0); + // Attempt to route while setting max_path_count to 0 results in a failure. + let zero_payment_params = payment_params.clone().with_max_path_count(0); if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route( &our_id, &zero_payment_params, &network_graph.read_only(), None, 100, 42, Arc::clone(&logger), &scorer, &random_seed_bytes) { - assert_eq!(err, "Can't find an MPP route with no paths allowed."); + assert_eq!(err, "Can't find a route with no paths allowed."); } else { panic!(); } } { - // Attempt to route while setting max_mpp_path_count to 3 results in a failure. + // Attempt to route while setting max_path_count to 3 results in a failure. // This is the case because the minimal_value_contribution_msat would require each path // to account for 1/3 of the total value, which is violated by 2 out of 3 paths. - let fail_payment_params = payment_params.clone().with_max_mpp_path_count(3); + let fail_payment_params = payment_params.clone().with_max_path_count(3); if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route( &our_id, &fail_payment_params, &network_graph.read_only(), None, 250_000, 42, Arc::clone(&logger), &scorer, &random_seed_bytes) {