Add create_blinded_paths to MessageRouter

The MessageRouter trait is used to find an OnionMessagePath to a
Destination (e.g., to a BlindedPath). Expand the interface with a
create_blinded_paths method for creating such paths to a recipient.
Provide a default implementation creating two-hop blinded paths where
the recipient's peers serve as introduction nodes.

diff --git a/fuzz/src/onion_message.rs b/fuzz/src/onion_message.rs
index 1051083d36be759d633b108a8078575d95d2287a..d2d60cfcf640593e2e38d264eac6eeb0c2abafad 100644 (file)
--- a/fuzz/src/onion_message.rs
+++ b/fuzz/src/onion_message.rs
@@ -1,17 +1,18 @@
 // Imports that need to be added manually
 use bitcoin::bech32::u5;
 use bitcoin::blockdata::script::ScriptBuf;
-use bitcoin::secp256k1::{PublicKey, Scalar, Secp256k1, SecretKey};
+use bitcoin::secp256k1::{PublicKey, Scalar, Secp256k1, SecretKey, self};
 use bitcoin::secp256k1::ecdh::SharedSecret;
 use bitcoin::secp256k1::ecdsa::RecoverableSignature;
 use bitcoin::secp256k1::schnorr;
 
-use lightning::sign::{Recipient, KeyMaterial, EntropySource, NodeSigner, SignerProvider};
+use lightning::blinded_path::BlindedPath;
 use lightning::ln::features::InitFeatures;
 use lightning::ln::msgs::{self, DecodeError, OnionMessageHandler};
 use lightning::ln::script::ShutdownScript;
 use lightning::offers::invoice::UnsignedBolt12Invoice;
 use lightning::offers::invoice_request::UnsignedInvoiceRequest;
+use lightning::sign::{Recipient, KeyMaterial, EntropySource, NodeSigner, SignerProvider};
 use lightning::util::test_channel_signer::TestChannelSigner;
 use lightning::util::logger::Logger;
 use lightning::util::ser::{Readable, Writeable, Writer};
@@ -82,6 +83,15 @@ impl MessageRouter for TestMessageRouter {
                        first_node_addresses: None,
                })
        }
+
+       fn create_blinded_paths<
+               ES: EntropySource + ?Sized, T: secp256k1::Signing + secp256k1::Verification
+       >(
+               &self, _recipient: PublicKey, _peers: Vec<PublicKey>, _entropy_source: &ES,
+               _secp_ctx: &Secp256k1<T>
+       ) -> Result<Vec<BlindedPath>, ()> {
+               unreachable!()
+       }
 }
 
 struct TestOffersMessageHandler {}

diff --git a/lightning/src/onion_message/functional_tests.rs b/lightning/src/onion_message/functional_tests.rs
index 9323be5fff2d36b2d586a9ed60948d71993daa64..b0031a6c3f4e05cd41823ceb9fa785ab3fb91722 100644 (file)
--- a/lightning/src/onion_message/functional_tests.rs
+++ b/lightning/src/onion_message/functional_tests.rs
@@ -13,14 +13,14 @@ use crate::blinded_path::BlindedPath;
 use crate::events::{Event, EventsProvider};
 use crate::ln::features::InitFeatures;
 use crate::ln::msgs::{self, DecodeError, OnionMessageHandler, SocketAddress};
-use crate::sign::{NodeSigner, Recipient};
+use crate::sign::{EntropySource, NodeSigner, Recipient};
 use crate::util::ser::{FixedLengthReader, LengthReadable, Writeable, Writer};
 use crate::util::test_utils;
 use super::{CustomOnionMessageHandler, Destination, MessageRouter, OffersMessage, OffersMessageHandler, OnionMessageContents, OnionMessagePath, OnionMessenger, PendingOnionMessage, SendError};
 
 use bitcoin::network::constants::Network;
 use bitcoin::hashes::hex::FromHex;
-use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey};
+use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey, self};
 
 use crate::io;
 use crate::io_extras::read_to_end;
@@ -55,6 +55,15 @@ impl MessageRouter for TestMessageRouter {
                                Some(vec![SocketAddress::TcpIpV4 { addr: [127, 0, 0, 1], port: 1000 }]),
                })
        }
+
+       fn create_blinded_paths<
+               ES: EntropySource + ?Sized, T: secp256k1::Signing + secp256k1::Verification
+       >(
+               &self, _recipient: PublicKey, _peers: Vec<PublicKey>, _entropy_source: &ES,
+               _secp_ctx: &Secp256k1<T>
+       ) -> Result<Vec<BlindedPath>, ()> {
+               unreachable!()
+       }
 }
 
 struct TestOffersMessageHandler {}

diff --git a/lightning/src/onion_message/messenger.rs b/lightning/src/onion_message/messenger.rs
index 8a44eb2a5beebf3128582bdbce23cc8edfbda381..c0db6096b995744c8dac86a90031eb8982ece9a6 100644 (file)
--- a/lightning/src/onion_message/messenger.rs
+++ b/lightning/src/onion_message/messenger.rs
@@ -64,9 +64,9 @@ pub(super) const MAX_TIMER_TICKS: usize = 2;
 /// # extern crate bitcoin;
 /// # use bitcoin::hashes::_export::_core::time::Duration;
 /// # use bitcoin::hashes::hex::FromHex;
-/// # use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey};
+/// # use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey, self};
 /// # use lightning::blinded_path::BlindedPath;
-/// # use lightning::sign::KeysManager;
+/// # use lightning::sign::{EntropySource, KeysManager};
 /// # use lightning::ln::peer_handler::IgnoringMessageHandler;
 /// # use lightning::onion_message::{OnionMessageContents, Destination, MessageRouter, OnionMessagePath, OnionMessenger};
 /// # use lightning::util::logger::{Logger, Record};
@@ -90,6 +90,11 @@ pub(super) const MAX_TIMER_TICKS: usize = 2;
 /// #             first_node_addresses: None,
 /// #         })
 /// #     }
+/// #     fn create_blinded_paths<ES: EntropySource + ?Sized, T: secp256k1::Signing + secp256k1::Verification>(
+/// #         &self, _recipient: PublicKey, _peers: Vec<PublicKey>, _entropy_source: &ES, _secp_ctx: &Secp256k1<T>
+/// #     ) -> Result<Vec<BlindedPath>, ()> {
+/// #         unreachable!()
+/// #     }
 /// # }
 /// # let seed = [42u8; 32];
 /// # let time = Duration::from_secs(123456);
@@ -270,6 +275,15 @@ pub trait MessageRouter {
        fn find_path(
                &self, sender: PublicKey, peers: Vec<PublicKey>, destination: Destination
        ) -> Result<OnionMessagePath, ()>;
+
+       /// Creates [`BlindedPath`]s to the `recipient` node. The nodes in `peers` are assumed to be
+       /// direct peers with the `recipient`.
+       fn create_blinded_paths<
+               ES: EntropySource + ?Sized, T: secp256k1::Signing + secp256k1::Verification
+       >(
+               &self, recipient: PublicKey, peers: Vec<PublicKey>, entropy_source: &ES,
+               secp_ctx: &Secp256k1<T>
+       ) -> Result<Vec<BlindedPath>, ()>;
 }
 
 /// A [`MessageRouter`] that can only route to a directly connected [`Destination`].
@@ -321,6 +335,43 @@ where
                        }
                }
        }
+
+       fn create_blinded_paths<
+               ES: EntropySource + ?Sized, T: secp256k1::Signing + secp256k1::Verification
+       >(
+               &self, recipient: PublicKey, peers: Vec<PublicKey>, entropy_source: &ES,
+               secp_ctx: &Secp256k1<T>
+       ) -> Result<Vec<BlindedPath>, ()> {
+               // Limit the number of blinded paths that are computed.
+               const MAX_PATHS: usize = 3;
+
+               // Ensure peers have at least three channels so that it is more difficult to infer the
+               // recipient's node_id.
+               const MIN_PEER_CHANNELS: usize = 3;
+
+               let network_graph = self.network_graph.deref().read_only();
+               let paths = peers.into_iter()
+                       // Limit to peers with announced channels
+                       .filter(|pubkey|
+                               network_graph
+                                       .node(&NodeId::from_pubkey(&pubkey))
+                                       .map(|info| &info.channels[..])
+                                       .map(|channels| channels.len() >= MIN_PEER_CHANNELS)
+                                       .unwrap_or(false)
+                       )
+                       .map(|pubkey| vec![pubkey, recipient])
+                       .map(|node_pks| BlindedPath::new_for_message(&node_pks, entropy_source, secp_ctx))
+                       .take(MAX_PATHS)
+                       .collect::<Result<Vec<_>, _>>();
+
+               match paths {
+                       Ok(paths) if !paths.is_empty() => Ok(paths),
+                       _ => {
+                               BlindedPath::one_hop_for_message(recipient, entropy_source, secp_ctx)
+                                       .map(|path| vec![path])
+                       },
+               }
+       }
 }
 
 /// A path for sending an [`OnionMessage`].