Introduce CurrencyConversion in Flow and ChannelManager

Following the introduction of the `CurrencyConversion` trait, this
commit integrates it into the `Flow` and `ChannelManager` as a
required parameter.

This change enables users to supply their own fiat-to-msat conversion
logic when constructing the Flow or ChannelManager, making synchronised
currency handling fully customizable at the application level.

Author: shaavan

fuzz/src/chanmon_consistency.rs

@@ -58,6 +58,9 @@ use lightning::ln::msgs::{
 use lightning::ln::script::ShutdownScript;
 use lightning::ln::types::ChannelId;
 use lightning::offers::invoice::UnsignedBolt12Invoice;
+use lightning::offers::invoice_request::CurrencyConversion;
+use lightning::offers::offer::CurrencyCode;
+use lightning::offers::parse::Bolt12SemanticError;
 use lightning::onion_message::messenger::{Destination, MessageRouter, OnionMessagePath};
 use lightning::routing::router::{
 	InFlightHtlcs, Path, PaymentParameters, Route, RouteHop, RouteParameters, Router,
@@ -150,6 +153,14 @@ impl MessageRouter for FuzzRouter {
 	}
 }
 
+struct FuzzCurrencyConversion {}
+
+impl CurrencyConversion for FuzzCurrencyConversion {
+	fn fiat_to_msats(&self, _iso4217_code: CurrencyCode) -> Result<u64, Bolt12SemanticError> {
+		unreachable!()
+	}
+}
+
 pub struct TestBroadcaster {}
 impl BroadcasterInterface for TestBroadcaster {
 	fn broadcast_transactions(&self, _txs: &[&Transaction]) {}
@@ -464,6 +475,7 @@ type ChanMan<'a> = ChannelManager<
 	Arc<FuzzEstimator>,
 	&'a FuzzRouter,
 	&'a FuzzRouter,
+	&'a FuzzCurrencyConversion,
 	Arc<dyn Logger>,
 >;
 
@@ -637,6 +649,7 @@ pub fn do_test<Out: Output>(data: &[u8], underlying_out: Out, anchors: bool) {
 	let out = SearchingOutput::new(underlying_out);
 	let broadcast = Arc::new(TestBroadcaster {});
 	let router = FuzzRouter {};
+	let currency_conversion = FuzzCurrencyConversion {};
 
 	macro_rules! make_node {
 		($node_id: expr, $fee_estimator: expr) => {{
@@ -679,6 +692,7 @@ pub fn do_test<Out: Output>(data: &[u8], underlying_out: Out, anchors: bool) {
 					broadcast.clone(),
 					&router,
 					&router,
+					&currency_conversion,
 					Arc::clone(&logger),
 					keys_manager.clone(),
 					keys_manager.clone(),
@@ -770,6 +784,7 @@ pub fn do_test<Out: Output>(data: &[u8], underlying_out: Out, anchors: bool) {
 			tx_broadcaster: broadcast.clone(),
 			router: &router,
 			message_router: &router,
+			currency_conversion: &currency_conversion,
 			logger,
 			default_config: config,
 			channel_monitors: monitor_refs,

fuzz/src/full_stack.rs

@@ -50,6 +50,9 @@ use lightning::ln::peer_handler::{
 use lightning::ln::script::ShutdownScript;
 use lightning::ln::types::ChannelId;
 use lightning::offers::invoice::UnsignedBolt12Invoice;
+use lightning::offers::invoice_request::CurrencyConversion;
+use lightning::offers::offer::CurrencyCode;
+use lightning::offers::parse::Bolt12SemanticError;
 use lightning::onion_message::messenger::{Destination, MessageRouter, OnionMessagePath};
 use lightning::routing::gossip::{NetworkGraph, P2PGossipSync};
 use lightning::routing::router::{
@@ -181,6 +184,14 @@ impl MessageRouter for FuzzRouter {
 	}
 }
 
+struct FuzzCurrencyConversion {}
+
+impl CurrencyConversion for FuzzCurrencyConversion {
+	fn fiat_to_msats(&self, _iso4217_code: CurrencyCode) -> Result<u64, Bolt12SemanticError> {
+		unreachable!()
+	}
+}
+
 struct TestBroadcaster {
 	txn_broadcasted: Mutex<Vec<Transaction>>,
 }
@@ -236,6 +247,7 @@ type ChannelMan<'a> = ChannelManager<
 	Arc<FuzzEstimator>,
 	&'a FuzzRouter,
 	&'a FuzzRouter,
+	&'a FuzzCurrencyConversion,
 	Arc<dyn Logger>,
 >;
 type PeerMan<'a> = PeerManager<
@@ -543,6 +555,7 @@ pub fn do_test(mut data: &[u8], logger: &Arc<dyn Logger>) {
 	});
 	let fee_est = Arc::new(FuzzEstimator { input: input.clone() });
 	let router = FuzzRouter {};
+	let currency_conversion = FuzzCurrencyConversion {};
 
 	macro_rules! get_slice {
 		($len: expr) => {
@@ -606,6 +619,7 @@ pub fn do_test(mut data: &[u8], logger: &Arc<dyn Logger>) {
 		broadcast.clone(),
 		&router,
 		&router,
+		&currency_conversion,
 		Arc::clone(&logger),
 		keys_manager.clone(),
 		keys_manager.clone(),

fuzz/src/lsps_message.rs

@@ -10,6 +10,7 @@ use lightning::chain::{chainmonitor, BestBlock};
 use lightning::ln::channelmanager::{ChainParameters, ChannelManager};
 use lightning::ln::peer_handler::CustomMessageHandler;
 use lightning::ln::wire::CustomMessageReader;
+use lightning::offers::invoice_request::DefaultCurrencyConversion;
 use lightning::onion_message::messenger::DefaultMessageRouter;
 use lightning::routing::gossip::NetworkGraph;
 use lightning::routing::router::DefaultRouter;
@@ -49,6 +50,7 @@ pub fn do_test(data: &[u8]) {
 	));
 	let msg_router =
 		Arc::new(DefaultMessageRouter::new(Arc::clone(&network_graph), Arc::clone(&keys_manager)));
+	let currency_conversion = Arc::new(DefaultCurrencyConversion {});
 	let chain_source = Arc::new(TestChainSource::new(Network::Bitcoin));
 	let kv_store = Arc::new(TestStore::new(false));
 	let chain_monitor = Arc::new(chainmonitor::ChainMonitor::new(
@@ -68,6 +70,7 @@ pub fn do_test(data: &[u8]) {
 		Arc::clone(&tx_broadcaster),
 		Arc::clone(&router),
 		Arc::clone(&msg_router),
+		Arc::clone(&currency_conversion),
 		Arc::clone(&logger),
 		Arc::clone(&keys_manager),
 		Arc::clone(&keys_manager),

lightning-background-processor/src/lib.rs

@@ -1672,6 +1672,7 @@ mod tests {
 		IgnoringMessageHandler, MessageHandler, PeerManager, SocketDescriptor,
 	};
 	use lightning::ln::types::ChannelId;
+	use lightning::offers::invoice_request::DefaultCurrencyConversion;
 	use lightning::onion_message::messenger::{DefaultMessageRouter, OnionMessenger};
 	use lightning::routing::gossip::{NetworkGraph, P2PGossipSync};
 	use lightning::routing::router::{CandidateRouteHop, DefaultRouter, Path, RouteHop};
@@ -1745,6 +1746,7 @@ mod tests {
 				Arc<KeysManager>,
 			>,
 		>,
+		Arc<DefaultCurrencyConversion>,
 		Arc<test_utils::TestLogger>,
 	>;
 
@@ -2167,6 +2169,7 @@ mod tests {
 				Arc::clone(&network_graph),
 				Arc::clone(&keys_manager),
 			));
+			let currency_conversion = Arc::new(DefaultCurrencyConversion {});
 			let chain_source = Arc::new(test_utils::TestChainSource::new(Network::Bitcoin));
 			let kv_store =
 				Arc::new(Persister::new(format!("{}_persister_{}", &persist_dir, i).into()));
@@ -2189,6 +2192,7 @@ mod tests {
 				Arc::clone(&tx_broadcaster),
 				Arc::clone(&router),
 				Arc::clone(&msg_router),
+				currency_conversion,
 				Arc::clone(&logger),
 				Arc::clone(&keys_manager),
 				Arc::clone(&keys_manager),

lightning-block-sync/src/init.rs

@@ -50,6 +50,7 @@ where
 /// use lightning::chain::chaininterface::BroadcasterInterface;
 /// use lightning::chain::chaininterface::FeeEstimator;
 /// use lightning::ln::channelmanager::{ChannelManager, ChannelManagerReadArgs};
+/// use lightning::offers::invoice_request::CurrencyConversion;
 /// use lightning::onion_message::messenger::MessageRouter;
 /// use lightning::routing::router::Router;
 /// use lightning::sign;
@@ -71,6 +72,7 @@ where
 /// 	F: FeeEstimator,
 /// 	R: Router,
 /// 	MR: MessageRouter,
+/// 	CC: CurrencyConversion,
 /// 	L: Logger,
 /// 	C: chain::Filter,
 /// 	P: chainmonitor::Persist<SP::EcdsaSigner>,
@@ -85,6 +87,7 @@ where
 /// 	fee_estimator: &F,
 /// 	router: &R,
 /// 	message_router: &MR,
+/// 	currency_conversion: &CC,
 /// 	logger: &L,
 /// 	persister: &P,
 /// ) {
@@ -105,11 +108,12 @@ where
 /// 			tx_broadcaster,
 /// 			router,
 /// 			message_router,
+/// 			currency_conversion,
 /// 			logger,
 /// 			config,
 /// 			vec![&mut monitor],
 /// 		);
-/// 		<(BlockHash, ChannelManager<&ChainMonitor<SP::EcdsaSigner, &C, &T, &F, &L, &P, &ES>, &T, &ES, &NS, &SP, &F, &R, &MR, &L>)>::read(
+/// 		<(BlockHash, ChannelManager<&ChainMonitor<SP::EcdsaSigner, &C, &T, &F, &L, &P, &ES>, &T, &ES, &NS, &SP, &F, &R, &MR, &CC, &L>)>::read(
 /// 			&mut Cursor::new(&serialized_manager), read_args).unwrap()
 /// 	};
 ///