Remove OnionMessageProvider

OnionMessageProvider is a super-trait of OnionMessageHandler, but they
don't need to be used separately. Additionally, the former is misplaced
in the events module. Remove OnionMessageProvider and add it's only
method, next_onion_message_for_peer, into OnionMessageHandler.

Author: jkczyz

lightning/src/events/mod.rs

@@ -1846,12 +1846,6 @@ pub trait MessageSendEventsProvider {
 	fn get_and_clear_pending_msg_events(&self) -> Vec<MessageSendEvent>;
 }
 
-/// A trait indicating an object may generate onion messages to send
-pub trait OnionMessageProvider {
-	/// Gets the next pending onion message for the peer with the given node id.
-	fn next_onion_message_for_peer(&self, peer_node_id: PublicKey) -> Option<msgs::OnionMessage>;
-}
-
 /// A trait indicating an object may generate events.
 ///
 /// Events are processed by passing an [`EventHandler`] to [`process_pending_events`].

lightning/src/ln/msgs.rs

@@ -49,7 +49,7 @@ use core::str::FromStr;
 use crate::io::{self, Cursor, Read};
 use crate::io_extras::read_to_end;
 
-use crate::events::{MessageSendEventsProvider, OnionMessageProvider};
+use crate::events::MessageSendEventsProvider;
 use crate::util::chacha20poly1305rfc::ChaChaPolyReadAdapter;
 use crate::util::logger;
 use crate::util::ser::{LengthReadable, LengthReadableArgs, Readable, ReadableArgs, Writeable, Writer, WithoutLength, FixedLengthReader, HighZeroBytesDroppedBigSize, Hostname, TransactionU16LenLimited, BigSize};
@@ -1497,17 +1497,22 @@ pub trait RoutingMessageHandler : MessageSendEventsProvider {
 	fn provided_init_features(&self, their_node_id: &PublicKey) -> InitFeatures;
 }
 
-/// A trait to describe an object that can receive onion messages.
-pub trait OnionMessageHandler : OnionMessageProvider {
+/// A handler for received [`OnionMessage`]s and for providing generated ones to send.
+pub trait OnionMessageHandler {
 	/// Handle an incoming `onion_message` message from the given peer.
 	fn handle_onion_message(&self, peer_node_id: &PublicKey, msg: &OnionMessage);
+
+	/// Returns the next pending onion message for the peer with the given node id.
+	fn next_onion_message_for_peer(&self, peer_node_id: PublicKey) -> Option<OnionMessage>;
+
 	/// Called when a connection is established with a peer. Can be used to track which peers
 	/// advertise onion message support and are online.
 	///
 	/// May return an `Err(())` if the features the peer supports are not sufficient to communicate
 	/// with us. Implementors should be somewhat conservative about doing so, however, as other
 	/// message handlers may still wish to communicate with this peer.
 	fn peer_connected(&self, their_node_id: &PublicKey, init: &Init, inbound: bool) -> Result<(), ()>;
+
 	/// Indicates a connection to the peer failed/an existing connection was lost. Allows handlers to
 	/// drop and refuse to forward onion messages to this peer.
 	fn peer_disconnected(&self, their_node_id: &PublicKey);

lightning/src/ln/peer_handler.rs

@@ -19,7 +19,7 @@ use bitcoin::blockdata::constants::ChainHash;
 use bitcoin::secp256k1::{self, Secp256k1, SecretKey, PublicKey};
 
 use crate::sign::{KeysManager, NodeSigner, Recipient};
-use crate::events::{MessageSendEvent, MessageSendEventsProvider, OnionMessageProvider};
+use crate::events::{MessageSendEvent, MessageSendEventsProvider};
 use crate::ln::ChannelId;
 use crate::ln::features::{InitFeatures, NodeFeatures};
 use crate::ln::msgs;
@@ -107,11 +107,9 @@ impl RoutingMessageHandler for IgnoringMessageHandler {
 	}
 	fn processing_queue_high(&self) -> bool { false }
 }
-impl OnionMessageProvider for IgnoringMessageHandler {
-	fn next_onion_message_for_peer(&self, _peer_node_id: PublicKey) -> Option<msgs::OnionMessage> { None }
-}
 impl OnionMessageHandler for IgnoringMessageHandler {
 	fn handle_onion_message(&self, _their_node_id: &PublicKey, _msg: &msgs::OnionMessage) {}
+	fn next_onion_message_for_peer(&self, _peer_node_id: PublicKey) -> Option<msgs::OnionMessage> { None }
 	fn peer_connected(&self, _their_node_id: &PublicKey, _init: &msgs::Init, _inbound: bool) -> Result<(), ()> { Ok(()) }
 	fn peer_disconnected(&self, _their_node_id: &PublicKey) {}
 	fn provided_node_features(&self) -> NodeFeatures { NodeFeatures::empty() }

lightning/src/onion_message/functional_tests.rs

@@ -10,7 +10,6 @@
 //! Onion message testing and test utilities live here.
 
 use crate::blinded_path::BlindedPath;
-use crate::events::OnionMessageProvider;
 use crate::ln::features::InitFeatures;
 use crate::ln::msgs::{self, DecodeError, OnionMessageHandler};
 use crate::sign::{NodeSigner, Recipient};

lightning/src/onion_message/messenger.rs

@@ -19,7 +19,6 @@ use crate::blinded_path::BlindedPath;
 use crate::blinded_path::message::{advance_path_by_one, ForwardTlvs, ReceiveTlvs};
 use crate::blinded_path::utils;
 use crate::sign::{EntropySource, KeysManager, NodeSigner, Recipient};
-use crate::events::OnionMessageProvider;
 use crate::ln::features::{InitFeatures, NodeFeatures};
 use crate::ln::msgs::{self, OnionMessageHandler};
 use crate::ln::onion_utils;
@@ -645,18 +644,7 @@ where
 		features.set_onion_messages_optional();
 		features
 	}
-}
 
-impl<ES: Deref, NS: Deref, L: Deref, MR: Deref, OMH: Deref, CMH: Deref> OnionMessageProvider
-for OnionMessenger<ES, NS, L, MR, OMH, CMH>
-where
-	ES::Target: EntropySource,
-	NS::Target: NodeSigner,
-	L::Target: Logger,
-	MR::Target: MessageRouter,
-	OMH::Target: OffersMessageHandler,
-	CMH::Target: CustomOnionMessageHandler,
-{
 	fn next_onion_message_for_peer(&self, peer_node_id: PublicKey) -> Option<msgs::OnionMessage> {
 		let mut pending_msgs = self.pending_messages.lock().unwrap();
 		if let Some(msgs) = pending_msgs.get_mut(&peer_node_id) {