X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=lightning%2Fsrc%2Fblinded_path%2Fmod.rs;h=2d3d085bddf35d51a5276c5c9c048506527ac45b;hb=0a6886ee38cfd906f984d7b8f444cb8621fce4fd;hp=7f4cfe2e3008eb25e46ed8a8dc10a21bf13a6a7b;hpb=e1d00063e2ed6b476e727c67b01e1ad871eb1e43;p=rust-lightning

diff --git a/lightning/src/blinded_path/mod.rs b/lightning/src/blinded_path/mod.rs
index 7f4cfe2e..2d3d085b 100644
--- a/lightning/src/blinded_path/mod.rs
+++ b/lightning/src/blinded_path/mod.rs
@@ -10,7 +10,7 @@
 //! Creating blinded paths and related utilities live here.
 
 pub mod payment;
-pub(crate) mod message;
+pub mod message;
 pub(crate) mod utils;
 
 use bitcoin::secp256k1::{self, PublicKey, Secp256k1, SecretKey};
@@ -21,6 +21,7 @@ use crate::offers::invoice::BlindedPayInfo;
 use crate::routing::gossip::{NodeId, ReadOnlyNetworkGraph};
 use crate::sign::EntropySource;
 use crate::util::ser::{Readable, Writeable, Writer};
+use crate::util::scid_utils;
 
 use crate::io;
 use crate::prelude::*;
@@ -124,7 +125,7 @@ impl BlindedPath {
 	pub fn one_hop_for_message<ES: Deref, T: secp256k1::Signing + secp256k1::Verification>(
 		recipient_node_id: PublicKey, entropy_source: ES, secp_ctx: &Secp256k1<T>
 	) -> Result<Self, ()> where ES::Target: EntropySource {
-		Self::new_for_message(&[recipient_node_id], entropy_source, secp_ctx)
+		Self::new_for_message(&[], recipient_node_id, entropy_source, secp_ctx)
 	}
 
 	/// Create a blinded path for an onion message, to be forwarded along `node_pks`. The last node
@@ -133,17 +134,21 @@ impl BlindedPath {
 	/// Errors if no hops are provided or if `node_pk`(s) are invalid.
 	//  TODO: make all payloads the same size with padding + add dummy hops
 	pub fn new_for_message<ES: Deref, T: secp256k1::Signing + secp256k1::Verification>(
-		node_pks: &[PublicKey], entropy_source: ES, secp_ctx: &Secp256k1<T>
+		intermediate_nodes: &[message::ForwardNode], recipient_node_id: PublicKey,
+		entropy_source: ES, secp_ctx: &Secp256k1<T>
 	) -> Result<Self, ()> where ES::Target: EntropySource {
-		if node_pks.is_empty() { return Err(()) }
+		let introduction_node = IntroductionNode::NodeId(
+			intermediate_nodes.first().map_or(recipient_node_id, |n| n.node_id)
+		);
 		let blinding_secret_bytes = entropy_source.get_secure_random_bytes();
 		let blinding_secret = SecretKey::from_slice(&blinding_secret_bytes[..]).expect("RNG is busted");
-		let introduction_node = IntroductionNode::NodeId(node_pks[0]);
 
 		Ok(BlindedPath {
 			introduction_node,
 			blinding_point: PublicKey::from_secret_key(secp_ctx, &blinding_secret),
-			blinded_hops: message::blinded_hops(secp_ctx, node_pks, &blinding_secret).map_err(|_| ())?,
+			blinded_hops: message::blinded_hops(
+				secp_ctx, intermediate_nodes, recipient_node_id, &blinding_secret,
+			).map_err(|_| ())?,
 		})
 	}
 
@@ -213,6 +218,35 @@ impl BlindedPath {
 			},
 		}
 	}
+
+	/// Attempts to a use a compact representation for the [`IntroductionNode`] by using a directed
+	/// short channel id from a channel in `network_graph` leading to the introduction node.
+	///
+	/// While this may result in a smaller encoding, there is a trade off in that the path may
+	/// become invalid if the channel is closed or hasn't been propagated via gossip. Therefore,
+	/// calling this may not be suitable for long-lived blinded paths.
+	pub fn use_compact_introduction_node(&mut self, network_graph: &ReadOnlyNetworkGraph) {
+		if let IntroductionNode::NodeId(pubkey) = &self.introduction_node {
+			let node_id = NodeId::from_pubkey(pubkey);
+			if let Some(node_info) = network_graph.node(&node_id) {
+				if let Some((scid, channel_info)) = node_info
+					.channels
+					.iter()
+					.filter_map(|scid| network_graph.channel(*scid).map(|info| (*scid, info)))
+					.min_by_key(|(scid, _)| scid_utils::block_from_scid(*scid))
+				{
+					let direction = if node_id == channel_info.node_one {
+						Direction::NodeOne
+					} else {
+						debug_assert_eq!(node_id, channel_info.node_two);
+						Direction::NodeTwo
+					};
+					self.introduction_node =
+						IntroductionNode::DirectedShortChannelId(direction, scid);
+				}
+			}
+		}
+	}
 }
 
 impl Writeable for BlindedPath {