Include MPP payment amount in RecipientOnionFields

In some uses of LDK we need the ability to send HTLCs for only a
portion of some larger MPP payment. This allows payers to make
single payments which spend funds from multiple wallets, which may
be important for ecash wallets holding funds in multiple mints or
graduated wallets which hold funds across a trusted wallet and a
self-custodial wallet.

In order to allow for this, we need to separate the concept of the
payment amount from the onion MPP amount. Here we start this
process by adding a `total_mpp_amount_msat` field to
`RecipientOnionFields` (which is the appropriate place for a field
describing something in the recipient onion).

We currently always assert that it is equal to the existing fields,
but will relax this in the coming commit(s).

We also start including a payment preimage on probe attempts,
which appears to have been the intent of the code, but which did
not work correctly.

The bulk of the test updates were done by Claude.

Author: TheBlueMatt

fuzz/src/chanmon_consistency.rs

@@ -585,7 +585,7 @@ fn send_payment(
 		}],
 		route_params: Some(route_params.clone()),
 	};
-	let onion = RecipientOnionFields::secret_only(payment_secret);
+	let onion = RecipientOnionFields::secret_only(payment_secret, amt);
 	let res = source.send_payment_with_route(route, payment_hash, onion, payment_id);
 	match res {
 		Err(err) => {
@@ -642,7 +642,7 @@ fn send_hop_payment(
 		}],
 		route_params: Some(route_params.clone()),
 	};
-	let onion = RecipientOnionFields::secret_only(payment_secret);
+	let onion = RecipientOnionFields::secret_only(payment_secret, amt);
 	let res = source.send_payment_with_route(route, payment_hash, onion, payment_id);
 	match res {
 		Err(err) => {
@@ -698,7 +698,7 @@ fn send_mpp_payment(
 		amt,
 	);
 	let route = Route { paths, route_params: Some(route_params) };
-	let onion = RecipientOnionFields::secret_only(payment_secret);
+	let onion = RecipientOnionFields::secret_only(payment_secret, amt);
 	let res = source.send_payment_with_route(route, payment_hash, onion, payment_id);
 	match res {
 		Err(_) => false,
@@ -769,7 +769,7 @@ fn send_mpp_hop_payment(
 		amt,
 	);
 	let route = Route { paths, route_params: Some(route_params) };
-	let onion = RecipientOnionFields::secret_only(payment_secret);
+	let onion = RecipientOnionFields::secret_only(payment_secret, amt);
 	let res = source.send_payment_with_route(route, payment_hash, onion, payment_id);
 	match res {
 		Err(_) => false,

fuzz/src/full_stack.rs

@@ -739,7 +739,7 @@ pub fn do_test(mut data: &[u8], logger: &Arc<dyn Logger>) {
 				payments_sent += 1;
 				let _ = channelmanager.send_payment(
 					payment_hash,
-					RecipientOnionFields::spontaneous_empty(),
+					RecipientOnionFields::spontaneous_empty(final_value_msat),
 					PaymentId(payment_hash.0),
 					params,
 					Retry::Attempts(2),
@@ -761,7 +761,7 @@ pub fn do_test(mut data: &[u8], logger: &Arc<dyn Logger>) {
 				payments_sent += 1;
 				let _ = channelmanager.send_payment(
 					payment_hash,
-					RecipientOnionFields::secret_only(payment_secret),
+					RecipientOnionFields::secret_only(payment_secret, final_value_msat),
 					PaymentId(payment_hash.0),
 					params,
 					Retry::Attempts(2),

lightning/src/chain/channelmonitor.rs

@@ -6850,7 +6850,7 @@ mod tests {
 		// the update through to the ChannelMonitor which will refuse it (as the channel is closed).
 		let (route, payment_hash, _, payment_secret) = get_route_and_payment_hash!(nodes[1], nodes[0], 100_000);
 		nodes[1].node.send_payment_with_route(route, payment_hash,
-			RecipientOnionFields::secret_only(payment_secret), PaymentId(payment_hash.0)
+			RecipientOnionFields::secret_only(payment_secret, 100_000), PaymentId(payment_hash.0)
 		).unwrap();
 		check_added_monitors(&nodes[1], 1);
 

lightning/src/events/mod.rs

@@ -41,8 +41,8 @@ use crate::types::payment::{PaymentHash, PaymentPreimage, PaymentSecret};
 use crate::types::string::UntrustedString;
 use crate::util::errors::APIError;
 use crate::util::ser::{
-	BigSize, FixedLengthReader, MaybeReadable, Readable, RequiredWrapper, UpgradableRequired,
-	WithoutLength, Writeable, Writer,
+	BigSize, FixedLengthReader, MaybeReadable, Readable, ReadableArgs, RequiredWrapper,
+	UpgradableRequired, WithoutLength, Writeable, Writer,
 };
 
 use crate::io;
@@ -2378,7 +2378,7 @@ impl MaybeReadable for Event {
 						(6, _user_payment_id, option),
 						(7, claim_deadline, option),
 						(8, payment_preimage, option),
-						(9, onion_fields, option),
+						(9, onion_fields, (option: ReadableArgs, amount_msat)),
 						(10, counterparty_skimmed_fee_msat_opt, option),
 						(11, payment_context, option),
 						(13, payment_id, option),
@@ -2710,7 +2710,8 @@ impl MaybeReadable for Event {
 						(4, amount_msat, required),
 						(5, htlcs, optional_vec),
 						(7, sender_intended_total_msat, option),
-						(9, onion_fields, option),
+						(9, onion_fields, (option: ReadableArgs,
+							sender_intended_total_msat.unwrap_or(amount_msat))),
 						(11, payment_id, option),
 					});
 					Ok(Some(Event::PaymentClaimed {

lightning/src/ln/accountable_tests.rs

@@ -31,7 +31,7 @@ fn test_accountable_forwarding_with_override(
 		PaymentParameters::from_node_id(nodes[2].node.get_our_node_id(), TEST_FINAL_CLTV),
 		100_000,
 	);
-	let onion_fields = RecipientOnionFields::secret_only(payment_secret);
+	let onion_fields = RecipientOnionFields::secret_only(payment_secret, 100_000);
 	let payment_id = PaymentId(payment_hash.0);
 	nodes[0]
 		.node

lightning/src/ln/async_payments_tests.rs

@@ -615,7 +615,7 @@ fn invalid_keysend_payment_secret() {
 		.node
 		.send_spontaneous_payment(
 			Some(keysend_preimage),
-			RecipientOnionFields::spontaneous_empty(),
+			RecipientOnionFields::spontaneous_empty(amt_msat),
 			PaymentId(keysend_preimage.0),
 			route_params,
 			Retry::Attempts(0),

lightning/src/ln/async_signer_tests.rs

@@ -297,7 +297,7 @@ fn do_test_async_commitment_signature_for_commitment_signed_revoke_and_ack(
 
 	let (route, our_payment_hash, _our_payment_preimage, our_payment_secret) =
 		get_route_and_payment_hash!(src, dst, 8000000);
-	let recipient_fields = RecipientOnionFields::secret_only(our_payment_secret);
+	let recipient_fields = RecipientOnionFields::secret_only(our_payment_secret, 8000000);
 	let payment_id = PaymentId(our_payment_hash.0);
 	src.node
 		.send_payment_with_route(route, our_payment_hash, recipient_fields, payment_id)
@@ -521,7 +521,7 @@ fn do_test_async_raa_peer_disconnect(
 
 	let (route, our_payment_hash, _our_payment_preimage, our_payment_secret) =
 		get_route_and_payment_hash!(src, dst, 8000000);
-	let recipient_fields = RecipientOnionFields::secret_only(our_payment_secret);
+	let recipient_fields = RecipientOnionFields::secret_only(our_payment_secret, 8000000);
 	let payment_id = PaymentId(our_payment_hash.0);
 	src.node
 		.send_payment_with_route(route, our_payment_hash, recipient_fields, payment_id)
@@ -670,7 +670,7 @@ fn do_test_async_commitment_signature_peer_disconnect(
 
 	let (route, our_payment_hash, _our_payment_preimage, our_payment_secret) =
 		get_route_and_payment_hash!(src, dst, 8000000);
-	let recipient_fields = RecipientOnionFields::secret_only(our_payment_secret);
+	let recipient_fields = RecipientOnionFields::secret_only(our_payment_secret, 8000000);
 	let payment_id = PaymentId(our_payment_hash.0);
 	src.node
 		.send_payment_with_route(route, our_payment_hash, recipient_fields, payment_id)
@@ -805,7 +805,7 @@ fn do_test_async_commitment_signature_ordering(monitor_update_failure: bool) {
 	// to the peer.
 	let (route, payment_hash_2, payment_preimage_2, payment_secret_2) =
 		get_route_and_payment_hash!(nodes[0], nodes[1], 1000000);
-	let recipient_fields = RecipientOnionFields::secret_only(payment_secret_2);
+	let recipient_fields = RecipientOnionFields::secret_only(payment_secret_2, 1000000);
 	let payment_id = PaymentId(payment_hash_2.0);
 	nodes[0]
 		.node
@@ -1344,14 +1344,14 @@ fn test_no_disconnect_while_async_revoke_and_ack_expecting_remote_commitment_sig
 	// We'll send a payment from both nodes to each other.
 	let (route1, payment_hash1, _, payment_secret1) =
 		get_route_and_payment_hash!(&nodes[0], &nodes[1], payment_amount);
-	let onion1 = RecipientOnionFields::secret_only(payment_secret1);
+	let onion1 = RecipientOnionFields::secret_only(payment_secret1, payment_amount);
 	let payment_id1 = PaymentId(payment_hash1.0);
 	nodes[0].node.send_payment_with_route(route1, payment_hash1, onion1, payment_id1).unwrap();
 	check_added_monitors(&nodes[0], 1);
 
 	let (route2, payment_hash2, _, payment_secret2) =
 		get_route_and_payment_hash!(&nodes[1], &nodes[0], payment_amount);
-	let onion2 = RecipientOnionFields::secret_only(payment_secret2);
+	let onion2 = RecipientOnionFields::secret_only(payment_secret2, payment_amount);
 	let payment_id2 = PaymentId(payment_hash2.0);
 	nodes[1].node.send_payment_with_route(route2, payment_hash2, onion2, payment_id2).unwrap();
 	check_added_monitors(&nodes[1], 1);