X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=lightning%2Fsrc%2Fblinded_path%2Fmod.rs;h=3dc6b121b006b80f95f05bfb59f23a5ff0764b98;hb=806b7f0e312c59c87fd628fb71e7c4a77a39645a;hp=daa9f033d94e4f0b5544c8cc71bb6e7523ca8acb;hpb=7002180261d495f15c12f9a341af1e7dbcac2990;p=rust-lightning

diff --git a/lightning/src/blinded_path/mod.rs b/lightning/src/blinded_path/mod.rs
index daa9f033..3dc6b121 100644
--- a/lightning/src/blinded_path/mod.rs
+++ b/lightning/src/blinded_path/mod.rs
@@ -24,6 +24,17 @@ use crate::util::ser::{Readable, Writeable, Writer};
 use crate::io;
 use crate::prelude::*;
 
+/// The next hop to forward an onion message along its path.
+///
+/// Note that payment blinded paths always specify their next hop using an explicit node id.
+#[derive(Clone, Debug, Hash, PartialEq, Eq)]
+pub enum NextMessageHop {
+	/// The node id of the next hop.
+	NodeId(PublicKey),
+	/// The short channel id leading to the next hop.
+	ShortChannelId(u64),
+}
+
 /// Onion messages and payments can be sent and received to blinded paths, which serve to hide the
 /// identity of the recipient.
 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
@@ -58,7 +69,7 @@ pub enum IntroductionNode {
 ///
 /// [BOLT 7]: https://github.com/lightning/bolts/blob/master/07-routing-gossip.md#the-channel_announcement-message
 /// [`ChannelAnnouncement`]: crate::ln::msgs::ChannelAnnouncement
-#[derive(Clone, Debug, Hash, PartialEq, Eq)]
+#[derive(Clone, Copy, Debug, Hash, PartialEq, Eq)]
 pub enum Direction {
 	/// The lesser node id when compared lexicographically in ascending order.
 	NodeOne,
@@ -66,6 +77,29 @@ pub enum Direction {
 	NodeTwo,
 }
 
+/// An interface for looking up the node id of a channel counterparty for the purpose of forwarding
+/// an [`OnionMessage`].
+///
+/// [`OnionMessage`]: crate::ln::msgs::OnionMessage
+pub trait NodeIdLookUp {
+	/// Returns the node id of the forwarding node's channel counterparty with `short_channel_id`.
+	///
+	/// Here, the forwarding node is referring to the node of the [`OnionMessenger`] parameterized
+	/// by the [`NodeIdLookUp`] and the counterparty to one of that node's peers.
+	///
+	/// [`OnionMessenger`]: crate::onion_message::messenger::OnionMessenger
+	fn next_node_id(&self, short_channel_id: u64) -> Option<PublicKey>;
+}
+
+/// A [`NodeIdLookUp`] that always returns `None`.
+pub struct EmptyNodeIdLookUp {}
+
+impl NodeIdLookUp for EmptyNodeIdLookUp {
+	fn next_node_id(&self, _short_channel_id: u64) -> Option<PublicKey> {
+		None
+	}
+}
+
 /// An encrypted payload and node id corresponding to a hop in a payment or onion message path, to
 /// be encoded in the sender's onion packet. These hops cannot be identified by outside observers
 /// and thus can be used to hide the identity of the recipient.
@@ -238,4 +272,17 @@ impl Direction {
 			Direction::NodeTwo => core::cmp::max(node_a, node_b),
 		}
 	}
+
+	/// Returns the [`PublicKey`] from the inputs corresponding to the direction.
+	pub fn select_pubkey<'a>(&self, node_a: &'a PublicKey, node_b: &'a PublicKey) -> &'a PublicKey {
+		let (node_one, node_two) = if NodeId::from_pubkey(node_a) < NodeId::from_pubkey(node_b) {
+			(node_a, node_b)
+		} else {
+			(node_b, node_a)
+		};
+		match self {
+			Direction::NodeOne => node_one,
+			Direction::NodeTwo => node_two,
+		}
+	}
 }