Merge pull request #2961 from jkczyz/2024-03-compact-blinded-paths
[rust-lightning] / lightning / src / blinded_path / mod.rs
index 1415836c01fee6cacaa8d2808f28d6d9ecfba37a..07fa7b770249cae94e1ea18269b63805dc933f93 100644 (file)
@@ -17,6 +17,7 @@ use bitcoin::secp256k1::{self, PublicKey, Secp256k1, SecretKey};
 
 use crate::ln::msgs::DecodeError;
 use crate::offers::invoice::BlindedPayInfo;
+use crate::routing::gossip::{NodeId, ReadOnlyNetworkGraph};
 use crate::sign::EntropySource;
 use crate::util::ser::{Readable, Writeable, Writer};
 
@@ -28,11 +29,11 @@ use crate::prelude::*;
 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
 pub struct BlindedPath {
        /// To send to a blinded path, the sender first finds a route to the unblinded
-       /// `introduction_node_id`, which can unblind its [`encrypted_payload`] to find out the onion
+       /// `introduction_node`, which can unblind its [`encrypted_payload`] to find out the onion
        /// message or payment's next hop and forward it along.
        ///
        /// [`encrypted_payload`]: BlindedHop::encrypted_payload
-       pub introduction_node_id: PublicKey,
+       pub introduction_node: IntroductionNode,
        /// Used by the introduction node to decrypt its [`encrypted_payload`] to forward the onion
        /// message or payment.
        ///
@@ -42,6 +43,52 @@ pub struct BlindedPath {
        pub blinded_hops: Vec<BlindedHop>,
 }
 
+/// The unblinded node in a [`BlindedPath`].
+#[derive(Clone, Debug, Hash, PartialEq, Eq)]
+pub enum IntroductionNode {
+       /// The node id of the introduction node.
+       NodeId(PublicKey),
+       /// The short channel id of the channel leading to the introduction node. The [`Direction`]
+       /// identifies which side of the channel is the introduction node.
+       DirectedShortChannelId(Direction, u64),
+}
+
+/// The side of a channel that is the [`IntroductionNode`] in a [`BlindedPath`]. [BOLT 7] defines
+/// which nodes is which in the [`ChannelAnnouncement`] message.
+///
+/// [BOLT 7]: https://github.com/lightning/bolts/blob/master/07-routing-gossip.md#the-channel_announcement-message
+/// [`ChannelAnnouncement`]: crate::ln::msgs::ChannelAnnouncement
+#[derive(Clone, Copy, Debug, Hash, PartialEq, Eq)]
+pub enum Direction {
+       /// The lesser node id when compared lexicographically in ascending order.
+       NodeOne,
+       /// The greater node id when compared lexicographically in ascending order.
+       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.
@@ -74,25 +121,26 @@ impl BlindedPath {
                if node_pks.is_empty() { return Err(()) }
                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_id = node_pks[0];
+               let introduction_node = IntroductionNode::NodeId(node_pks[0]);
 
                Ok(BlindedPath {
-                       introduction_node_id,
+                       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(|_| ())?,
                })
        }
 
        /// Create a one-hop blinded path for a payment.
-       pub fn one_hop_for_payment<ES: EntropySource, T: secp256k1::Signing + secp256k1::Verification>(
-               payee_node_id: PublicKey, payee_tlvs: payment::ReceiveTlvs, entropy_source: &ES,
-               secp_ctx: &Secp256k1<T>
+       pub fn one_hop_for_payment<ES: EntropySource + ?Sized, T: secp256k1::Signing + secp256k1::Verification>(
+               payee_node_id: PublicKey, payee_tlvs: payment::ReceiveTlvs, min_final_cltv_expiry_delta: u16,
+               entropy_source: &ES, secp_ctx: &Secp256k1<T>
        ) -> Result<(BlindedPayInfo, Self), ()> {
                // This value is not considered in pathfinding for 1-hop blinded paths, because it's intended to
                // be in relation to a specific channel.
                let htlc_maximum_msat = u64::max_value();
                Self::new_for_payment(
-                       &[], payee_node_id, payee_tlvs, htlc_maximum_msat, entropy_source, secp_ctx
+                       &[], payee_node_id, payee_tlvs, htlc_maximum_msat, min_final_cltv_expiry_delta,
+                       entropy_source, secp_ctx
                )
        }
 
@@ -105,28 +153,64 @@ impl BlindedPath {
        ///
        /// [`ForwardTlvs`]: crate::blinded_path::payment::ForwardTlvs
        //  TODO: make all payloads the same size with padding + add dummy hops
-       pub(crate) fn new_for_payment<ES: EntropySource, T: secp256k1::Signing + secp256k1::Verification>(
+       pub fn new_for_payment<ES: EntropySource + ?Sized, T: secp256k1::Signing + secp256k1::Verification>(
                intermediate_nodes: &[payment::ForwardNode], payee_node_id: PublicKey,
-               payee_tlvs: payment::ReceiveTlvs, htlc_maximum_msat: u64, entropy_source: &ES,
-               secp_ctx: &Secp256k1<T>
+               payee_tlvs: payment::ReceiveTlvs, htlc_maximum_msat: u64, min_final_cltv_expiry_delta: u16,
+               entropy_source: &ES, secp_ctx: &Secp256k1<T>
        ) -> Result<(BlindedPayInfo, Self), ()> {
+               let introduction_node = IntroductionNode::NodeId(
+                       intermediate_nodes.first().map_or(payee_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 blinded_payinfo = payment::compute_payinfo(intermediate_nodes, &payee_tlvs, htlc_maximum_msat)?;
+               let blinded_payinfo = payment::compute_payinfo(
+                       intermediate_nodes, &payee_tlvs, htlc_maximum_msat, min_final_cltv_expiry_delta
+               )?;
                Ok((blinded_payinfo, BlindedPath {
-                       introduction_node_id: intermediate_nodes.first().map_or(payee_node_id, |n| n.node_id),
+                       introduction_node,
                        blinding_point: PublicKey::from_secret_key(secp_ctx, &blinding_secret),
                        blinded_hops: payment::blinded_hops(
                                secp_ctx, intermediate_nodes, payee_node_id, payee_tlvs, &blinding_secret
                        ).map_err(|_| ())?,
                }))
        }
+
+       /// Returns the introduction [`NodeId`] of the blinded path, if it is publicly reachable (i.e.,
+       /// it is found in the network graph).
+       pub fn public_introduction_node_id<'a>(
+               &self, network_graph: &'a ReadOnlyNetworkGraph
+       ) -> Option<&'a NodeId> {
+               match &self.introduction_node {
+                       IntroductionNode::NodeId(pubkey) => {
+                               let node_id = NodeId::from_pubkey(pubkey);
+                               network_graph.nodes().get_key_value(&node_id).map(|(key, _)| key)
+                       },
+                       IntroductionNode::DirectedShortChannelId(direction, scid) => {
+                               network_graph
+                                       .channel(*scid)
+                                       .map(|c| match direction {
+                                               Direction::NodeOne => &c.node_one,
+                                               Direction::NodeTwo => &c.node_two,
+                                       })
+                       },
+               }
+       }
 }
 
 impl Writeable for BlindedPath {
        fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
-               self.introduction_node_id.write(w)?;
+               match &self.introduction_node {
+                       IntroductionNode::NodeId(pubkey) => pubkey.write(w)?,
+                       IntroductionNode::DirectedShortChannelId(direction, scid) => {
+                               match direction {
+                                       Direction::NodeOne => 0u8.write(w)?,
+                                       Direction::NodeTwo => 1u8.write(w)?,
+                               }
+                               scid.write(w)?;
+                       },
+               }
+
                self.blinding_point.write(w)?;
                (self.blinded_hops.len() as u8).write(w)?;
                for hop in &self.blinded_hops {
@@ -138,7 +222,17 @@ impl Writeable for BlindedPath {
 
 impl Readable for BlindedPath {
        fn read<R: io::Read>(r: &mut R) -> Result<Self, DecodeError> {
-               let introduction_node_id = Readable::read(r)?;
+               let mut first_byte: u8 = Readable::read(r)?;
+               let introduction_node = match first_byte {
+                       0 => IntroductionNode::DirectedShortChannelId(Direction::NodeOne, Readable::read(r)?),
+                       1 => IntroductionNode::DirectedShortChannelId(Direction::NodeTwo, Readable::read(r)?),
+                       2|3 => {
+                               use io::Read;
+                               let mut pubkey_read = core::slice::from_mut(&mut first_byte).chain(r.by_ref());
+                               IntroductionNode::NodeId(Readable::read(&mut pubkey_read)?)
+                       },
+                       _ => return Err(DecodeError::InvalidValue),
+               };
                let blinding_point = Readable::read(r)?;
                let num_hops: u8 = Readable::read(r)?;
                if num_hops == 0 { return Err(DecodeError::InvalidValue) }
@@ -147,7 +241,7 @@ impl Readable for BlindedPath {
                        blinded_hops.push(Readable::read(r)?);
                }
                Ok(BlindedPath {
-                       introduction_node_id,
+                       introduction_node,
                        blinding_point,
                        blinded_hops,
                })
@@ -159,3 +253,25 @@ impl_writeable!(BlindedHop, {
        encrypted_payload
 });
 
+impl Direction {
+       /// Returns the [`NodeId`] from the inputs corresponding to the direction.
+       pub fn select_node_id<'a>(&self, node_a: &'a NodeId, node_b: &'a NodeId) -> &'a NodeId {
+               match self {
+                       Direction::NodeOne => core::cmp::min(node_a, node_b),
+                       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,
+               }
+       }
+}