lightning 0.0.121

// This file is Copyright its original authors, visible in version control
// history.
//
// This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
// or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
// You may not use this file except in accordance with one or both of these
// licenses.

use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey};
use crate::blinded_path::BlindedPath;
use crate::blinded_path::payment::{ForwardNode, ForwardTlvs, PaymentConstraints, PaymentRelay, ReceiveTlvs};
use crate::events::{Event, HTLCDestination, MessageSendEvent, MessageSendEventsProvider, PaymentFailureReason};
use crate::ln::PaymentSecret;
use crate::ln::channelmanager;
use crate::ln::channelmanager::{PaymentId, RecipientOnionFields};
use crate::ln::features::BlindedHopFeatures;
use crate::ln::functional_test_utils::*;
use crate::ln::msgs;
use crate::ln::msgs::ChannelMessageHandler;
use crate::ln::onion_utils;
use crate::ln::onion_utils::INVALID_ONION_BLINDING;
use crate::ln::outbound_payment::Retry;
use crate::offers::invoice::BlindedPayInfo;
use crate::prelude::*;
use crate::routing::router::{Payee, PaymentParameters, RouteParameters};
use crate::util::config::UserConfig;
use crate::util::test_utils;

fn blinded_payment_path(
	payment_secret: PaymentSecret, node_ids: Vec<PublicKey>,
	channel_upds: &[&msgs::UnsignedChannelUpdate], keys_manager: &test_utils::TestKeysInterface
) -> (BlindedPayInfo, BlindedPath) {
	let mut intermediate_nodes = Vec::new();
	for (node_id, chan_upd) in node_ids.iter().zip(channel_upds) {
		intermediate_nodes.push(ForwardNode {
			node_id: *node_id,
			tlvs: ForwardTlvs {
				short_channel_id: chan_upd.short_channel_id,
				payment_relay: PaymentRelay {
					cltv_expiry_delta: chan_upd.cltv_expiry_delta,
					fee_proportional_millionths: chan_upd.fee_proportional_millionths,
					fee_base_msat: chan_upd.fee_base_msat,
				},
				payment_constraints: PaymentConstraints {
					max_cltv_expiry: u32::max_value(),
					htlc_minimum_msat: chan_upd.htlc_minimum_msat,
				},
				features: BlindedHopFeatures::empty(),
			},
			htlc_maximum_msat: chan_upd.htlc_maximum_msat,
		});
	}
	let payee_tlvs = ReceiveTlvs {
		payment_secret,
		payment_constraints: PaymentConstraints {
			max_cltv_expiry: u32::max_value(),
			htlc_minimum_msat: channel_upds.last().unwrap().htlc_minimum_msat,
		},
	};
	let mut secp_ctx = Secp256k1::new();
	BlindedPath::new_for_payment(
		&intermediate_nodes[..], *node_ids.last().unwrap(), payee_tlvs,
		channel_upds.last().unwrap().htlc_maximum_msat, keys_manager, &secp_ctx
	).unwrap()
}

pub fn get_blinded_route_parameters(
	amt_msat: u64, payment_secret: PaymentSecret, node_ids: Vec<PublicKey>,
	channel_upds: &[&msgs::UnsignedChannelUpdate], keys_manager: &test_utils::TestKeysInterface
) -> RouteParameters {
	RouteParameters::from_payment_params_and_value(
		PaymentParameters::blinded(vec![
			blinded_payment_path(payment_secret, node_ids, channel_upds, keys_manager)
		]), amt_msat
	)
}

#[test]
fn one_hop_blinded_path() {
	do_one_hop_blinded_path(true);
	do_one_hop_blinded_path(false);
}

fn do_one_hop_blinded_path(success: bool) {
	let chanmon_cfgs = create_chanmon_cfgs(2);
	let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
	let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
	let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
	let chan_upd = create_announced_chan_between_nodes_with_value(&nodes, 0, 1, 1_000_000, 0).0.contents;

	let amt_msat = 5000;
	let (payment_preimage, payment_hash, payment_secret) = get_payment_preimage_hash(&nodes[1], Some(amt_msat), None);
	let payee_tlvs = ReceiveTlvs {
		payment_secret,
		payment_constraints: PaymentConstraints {
			max_cltv_expiry: u32::max_value(),
			htlc_minimum_msat: chan_upd.htlc_minimum_msat,
		},
	};
	let mut secp_ctx = Secp256k1::new();
	let blinded_path = BlindedPath::one_hop_for_payment(
		nodes[1].node.get_our_node_id(), payee_tlvs, &chanmon_cfgs[1].keys_manager, &secp_ctx
	).unwrap();

	let route_params = RouteParameters::from_payment_params_and_value(
		PaymentParameters::blinded(vec![blinded_path]),
		amt_msat,
	);
	nodes[0].node.send_payment(payment_hash, RecipientOnionFields::spontaneous_empty(),
	PaymentId(payment_hash.0), route_params, Retry::Attempts(0)).unwrap();
	check_added_monitors(&nodes[0], 1);
	pass_along_route(&nodes[0], &[&[&nodes[1]]], amt_msat, payment_hash, payment_secret);
	if success {
		claim_payment(&nodes[0], &[&nodes[1]], payment_preimage);
	} else {
		fail_payment(&nodes[0], &[&nodes[1]], payment_hash);
	}
}

#[test]
fn mpp_to_one_hop_blinded_path() {
	let chanmon_cfgs = create_chanmon_cfgs(4);
	let node_cfgs = create_node_cfgs(4, &chanmon_cfgs);
	let node_chanmgrs = create_node_chanmgrs(4, &node_cfgs, &[None, None, None, None]);
	let nodes = create_network(4, &node_cfgs, &node_chanmgrs);
	let mut secp_ctx = Secp256k1::new();

	create_announced_chan_between_nodes(&nodes, 0, 1);
	create_announced_chan_between_nodes(&nodes, 0, 2);
	let chan_upd_1_3 = create_announced_chan_between_nodes(&nodes, 1, 3).0.contents;
	create_announced_chan_between_nodes(&nodes, 2, 3).0.contents;

	let amt_msat = 15_000_000;
	let (payment_preimage, payment_hash, payment_secret) = get_payment_preimage_hash(&nodes[3], Some(amt_msat), None);
	let payee_tlvs = ReceiveTlvs {
		payment_secret,
		payment_constraints: PaymentConstraints {
			max_cltv_expiry: u32::max_value(),
			htlc_minimum_msat: chan_upd_1_3.htlc_minimum_msat,
		},
	};
	let blinded_path = BlindedPath::one_hop_for_payment(
		nodes[3].node.get_our_node_id(), payee_tlvs, &chanmon_cfgs[3].keys_manager, &secp_ctx
	).unwrap();

	let bolt12_features =
		channelmanager::provided_bolt12_invoice_features(&UserConfig::default());
	let route_params = RouteParameters::from_payment_params_and_value(
		PaymentParameters::blinded(vec![blinded_path]).with_bolt12_features(bolt12_features).unwrap(),
		amt_msat,
	);
	nodes[0].node.send_payment(payment_hash, RecipientOnionFields::spontaneous_empty(), PaymentId(payment_hash.0), route_params, Retry::Attempts(0)).unwrap();
	check_added_monitors(&nodes[0], 2);

	let expected_route: &[&[&Node]] = &[&[&nodes[1], &nodes[3]], &[&nodes[2], &nodes[3]]];
	let mut events = nodes[0].node.get_and_clear_pending_msg_events();
	assert_eq!(events.len(), 2);

	let ev = remove_first_msg_event_to_node(&nodes[1].node.get_our_node_id(), &mut events);
	pass_along_path(&nodes[0], expected_route[0], amt_msat, payment_hash.clone(),
		Some(payment_secret), ev.clone(), false, None);

	let ev = remove_first_msg_event_to_node(&nodes[2].node.get_our_node_id(), &mut events);
	pass_along_path(&nodes[0], expected_route[1], amt_msat, payment_hash.clone(),
		Some(payment_secret), ev.clone(), true, None);
	claim_payment_along_route(&nodes[0], expected_route, false, payment_preimage);
}

enum ForwardCheckFail {
	// Fail a check on the inbound onion payload. In this case, we underflow when calculating the
	// outgoing cltv_expiry.
	InboundOnionCheck,
	// The forwarding node's payload is encoded as a receive, i.e. the next hop HMAC is [0; 32].
	ForwardPayloadEncodedAsReceive,
	// Fail a check on the outbound channel. In this case, our next-hop peer is offline.
	OutboundChannelCheck,
}

#[test]
fn forward_checks_failure() {
	do_forward_checks_failure(ForwardCheckFail::InboundOnionCheck);
	do_forward_checks_failure(ForwardCheckFail::ForwardPayloadEncodedAsReceive);
	do_forward_checks_failure(ForwardCheckFail::OutboundChannelCheck);
}

fn do_forward_checks_failure(check: ForwardCheckFail) {
	// Ensure we'll fail backwards properly if a forwarding check fails on initial update_add
	// receipt.
	let chanmon_cfgs = create_chanmon_cfgs(3);
	let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
	let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, None, None]);
	let mut nodes = create_network(3, &node_cfgs, &node_chanmgrs);
	// We need the session priv to construct a bogus onion packet later.
	*nodes[0].keys_manager.override_random_bytes.lock().unwrap() = Some([3; 32]);
	create_announced_chan_between_nodes_with_value(&nodes, 0, 1, 1_000_000, 0);
	let chan_upd_1_2 = create_announced_chan_between_nodes_with_value(&nodes, 1, 2, 1_000_000, 0).0.contents;

	let amt_msat = 5000;
	let (_, payment_hash, payment_secret) = get_payment_preimage_hash(&nodes[2], Some(amt_msat), None);
	let route_params = get_blinded_route_parameters(amt_msat, payment_secret,
		nodes.iter().skip(1).map(|n| n.node.get_our_node_id()).collect(), &[&chan_upd_1_2],
		&chanmon_cfgs[2].keys_manager);

	let route = get_route(&nodes[0], &route_params).unwrap();
	node_cfgs[0].router.expect_find_route(route_params.clone(), Ok(route.clone()));
	nodes[0].node.send_payment(payment_hash, RecipientOnionFields::spontaneous_empty(), PaymentId(payment_hash.0), route_params, Retry::Attempts(0)).unwrap();
	check_added_monitors(&nodes[0], 1);

	let mut events = nodes[0].node.get_and_clear_pending_msg_events();
	assert_eq!(events.len(), 1);
	let ev = remove_first_msg_event_to_node(&nodes[1].node.get_our_node_id(), &mut events);
	let mut payment_event = SendEvent::from_event(ev);

	let mut update_add = &mut payment_event.msgs[0];
	match check {
		ForwardCheckFail::InboundOnionCheck => {
			update_add.cltv_expiry = 10; // causes outbound CLTV expiry to underflow
		},
		ForwardCheckFail::ForwardPayloadEncodedAsReceive => {
			let session_priv = SecretKey::from_slice(&[3; 32]).unwrap();
			let onion_keys = onion_utils::construct_onion_keys(&Secp256k1::new(), &route.paths[0], &session_priv).unwrap();
			let cur_height = nodes[0].best_block_info().1;
			let (mut onion_payloads, ..) = onion_utils::build_onion_payloads(
				&route.paths[0], amt_msat, RecipientOnionFields::spontaneous_empty(), cur_height, &None).unwrap();
			// Remove the receive payload so the blinded forward payload is encoded as a final payload
			// (i.e. next_hop_hmac == [0; 32])
			onion_payloads.pop();
			update_add.onion_routing_packet = onion_utils::construct_onion_packet(onion_payloads, onion_keys, [0; 32], &payment_hash).unwrap();
		},
		ForwardCheckFail::OutboundChannelCheck => {
			// The intro node will see that the next-hop peer is disconnected and fail the HTLC backwards.
			nodes[1].node.peer_disconnected(&nodes[2].node.get_our_node_id());
		},
	}
	nodes[1].node.handle_update_add_htlc(&nodes[0].node.get_our_node_id(), &payment_event.msgs[0]);
	check_added_monitors!(nodes[1], 0);
	do_commitment_signed_dance(&nodes[1], &nodes[0], &payment_event.commitment_msg, true, true);

	let mut updates = get_htlc_update_msgs!(nodes[1], nodes[0].node.get_our_node_id());
	nodes[0].node.handle_update_fail_htlc(&nodes[1].node.get_our_node_id(), &updates.update_fail_htlcs[0]);
	do_commitment_signed_dance(&nodes[0], &nodes[1], &updates.commitment_signed, false, false);
	expect_payment_failed_conditions(&nodes[0], payment_hash, false,
		PaymentFailedConditions::new().expected_htlc_error_data(INVALID_ONION_BLINDING, &[0; 32]));
}

#[test]
fn failed_backwards_to_intro_node() {
	// Ensure the intro node will error backwards properly even if the downstream node did not blind
	// their error.
	let chanmon_cfgs = create_chanmon_cfgs(3);
	let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
	let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, None, None]);
	let mut nodes = create_network(3, &node_cfgs, &node_chanmgrs);
	create_announced_chan_between_nodes_with_value(&nodes, 0, 1, 1_000_000, 0);
	let chan_upd_1_2 = create_announced_chan_between_nodes_with_value(&nodes, 1, 2, 1_000_000, 0).0.contents;

	let amt_msat = 5000;
	let (_, payment_hash, payment_secret) = get_payment_preimage_hash(&nodes[2], Some(amt_msat), None);
	let route_params = get_blinded_route_parameters(amt_msat, payment_secret,
		nodes.iter().skip(1).map(|n| n.node.get_our_node_id()).collect(), &[&chan_upd_1_2],
		&chanmon_cfgs[2].keys_manager);

	nodes[0].node.send_payment(payment_hash, RecipientOnionFields::spontaneous_empty(), PaymentId(payment_hash.0), route_params, Retry::Attempts(0)).unwrap();
	check_added_monitors(&nodes[0], 1);

	let mut events = nodes[0].node.get_and_clear_pending_msg_events();
	assert_eq!(events.len(), 1);
	let ev = remove_first_msg_event_to_node(&nodes[1].node.get_our_node_id(), &mut events);
	let mut payment_event = SendEvent::from_event(ev);

	nodes[1].node.handle_update_add_htlc(&nodes[0].node.get_our_node_id(), &payment_event.msgs[0]);
	check_added_monitors!(nodes[1], 0);
	do_commitment_signed_dance(&nodes[1], &nodes[0], &payment_event.commitment_msg, false, false);
	expect_pending_htlcs_forwardable!(nodes[1]);
	check_added_monitors!(&nodes[1], 1);

	let mut events = nodes[1].node.get_and_clear_pending_msg_events();
	assert_eq!(events.len(), 1);
	let ev = remove_first_msg_event_to_node(&nodes[2].node.get_our_node_id(), &mut events);
	let mut payment_event = SendEvent::from_event(ev);

	// Ensure the final node fails to handle the HTLC.
	payment_event.msgs[0].onion_routing_packet.hop_data[0] ^= 1;
	nodes[2].node.handle_update_add_htlc(&nodes[1].node.get_our_node_id(), &payment_event.msgs[0]);
	check_added_monitors!(nodes[2], 0);
	do_commitment_signed_dance(&nodes[2], &nodes[1], &payment_event.commitment_msg, true, true);
	nodes[2].node.process_pending_htlc_forwards();

	let mut updates = get_htlc_update_msgs!(nodes[2], nodes[1].node.get_our_node_id());
	let mut update_malformed = &mut updates.update_fail_malformed_htlcs[0];
	// Check that the final node encodes its failure correctly.
	assert_eq!(update_malformed.failure_code, INVALID_ONION_BLINDING);
	assert_eq!(update_malformed.sha256_of_onion, [0; 32]);

	// Modify such the final hop does not correctly blind their error so we can ensure the intro node
	// converts it to the correct error.
	update_malformed.sha256_of_onion = [1; 32];
	nodes[1].node.handle_update_fail_malformed_htlc(&nodes[2].node.get_our_node_id(), update_malformed);
	do_commitment_signed_dance(&nodes[1], &nodes[2], &updates.commitment_signed, true, false);

	let mut updates = get_htlc_update_msgs!(nodes[1], nodes[0].node.get_our_node_id());
	nodes[0].node.handle_update_fail_htlc(&nodes[1].node.get_our_node_id(), &updates.update_fail_htlcs[0]);
	do_commitment_signed_dance(&nodes[0], &nodes[1], &updates.commitment_signed, false, false);
	expect_payment_failed_conditions(&nodes[0], payment_hash, false,
		PaymentFailedConditions::new().expected_htlc_error_data(INVALID_ONION_BLINDING, &[0; 32]));
}

enum ProcessPendingHTLCsCheck {
	FwdPeerDisconnected,
	FwdChannelClosed,
}

#[test]
fn forward_fail_in_process_pending_htlc_fwds() {
	do_forward_fail_in_process_pending_htlc_fwds(ProcessPendingHTLCsCheck::FwdPeerDisconnected);
	do_forward_fail_in_process_pending_htlc_fwds(ProcessPendingHTLCsCheck::FwdChannelClosed);
}
fn do_forward_fail_in_process_pending_htlc_fwds(check: ProcessPendingHTLCsCheck) {
	// Ensure the intro node will error backwards properly if the HTLC fails in
	// process_pending_htlc_forwards.
	let chanmon_cfgs = create_chanmon_cfgs(3);
	let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
	let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, None, None]);
	let mut nodes = create_network(3, &node_cfgs, &node_chanmgrs);
	create_announced_chan_between_nodes_with_value(&nodes, 0, 1, 1_000_000, 0);
	let (chan_upd_1_2, channel_id) = {
		let chan = create_announced_chan_between_nodes_with_value(&nodes, 1, 2, 1_000_000, 0);
		(chan.0.contents, chan.2)
	};

	let amt_msat = 5000;
	let (_, payment_hash, payment_secret) = get_payment_preimage_hash(&nodes[2], Some(amt_msat), None);
	let route_params = get_blinded_route_parameters(amt_msat, payment_secret,
		nodes.iter().skip(1).map(|n| n.node.get_our_node_id()).collect(), &[&chan_upd_1_2],
		&chanmon_cfgs[2].keys_manager);

	nodes[0].node.send_payment(payment_hash, RecipientOnionFields::spontaneous_empty(), PaymentId(payment_hash.0), route_params, Retry::Attempts(0)).unwrap();
	check_added_monitors(&nodes[0], 1);

	let mut events = nodes[0].node.get_and_clear_pending_msg_events();
	assert_eq!(events.len(), 1);
	let ev = remove_first_msg_event_to_node(&nodes[1].node.get_our_node_id(), &mut events);
	let mut payment_event = SendEvent::from_event(ev);

	nodes[1].node.handle_update_add_htlc(&nodes[0].node.get_our_node_id(), &payment_event.msgs[0]);
	check_added_monitors!(nodes[1], 0);
	do_commitment_signed_dance(&nodes[1], &nodes[0], &payment_event.commitment_msg, false, false);

	match check {
		ProcessPendingHTLCsCheck::FwdPeerDisconnected => {
			// Disconnect the next-hop peer so when we go to forward in process_pending_htlc_forwards, the
			// intro node will error backwards.
			nodes[1].node.peer_disconnected(&nodes[2].node.get_our_node_id());
			expect_pending_htlcs_forwardable!(nodes[1]);
			expect_pending_htlcs_forwardable_and_htlc_handling_failed_ignore!(nodes[1],
				vec![HTLCDestination::NextHopChannel { node_id: Some(nodes[2].node.get_our_node_id()), channel_id }]);
		},
		ProcessPendingHTLCsCheck::FwdChannelClosed => {
			// Force close the next-hop channel so when we go to forward in process_pending_htlc_forwards,
			// the intro node will error backwards.
			nodes[1].node.force_close_broadcasting_latest_txn(&channel_id, &nodes[2].node.get_our_node_id()).unwrap();
			let events = nodes[1].node.get_and_clear_pending_events();
			match events[0] {
				crate::events::Event::PendingHTLCsForwardable { .. } => {},
				_ => panic!("Unexpected event {:?}", events),
			};
			match events[1] {
				crate::events::Event::ChannelClosed { .. } => {},
				_ => panic!("Unexpected event {:?}", events),
			}

			nodes[1].node.process_pending_htlc_forwards();
			expect_pending_htlcs_forwardable_and_htlc_handling_failed_ignore!(nodes[1],
				vec![HTLCDestination::UnknownNextHop { requested_forward_scid: chan_upd_1_2.short_channel_id }]);
			check_closed_broadcast(&nodes[1], 1, true);
			check_added_monitors!(nodes[1], 1);
			nodes[1].node.process_pending_htlc_forwards();
		},
	}

	let mut updates = get_htlc_update_msgs!(nodes[1], nodes[0].node.get_our_node_id());
	nodes[0].node.handle_update_fail_htlc(&nodes[1].node.get_our_node_id(), &updates.update_fail_htlcs[0]);
	check_added_monitors!(nodes[1], 1);
	do_commitment_signed_dance(&nodes[0], &nodes[1], &updates.commitment_signed, false, false);

	expect_payment_failed_conditions(&nodes[0], payment_hash, false,
		PaymentFailedConditions::new().expected_htlc_error_data(INVALID_ONION_BLINDING, &[0; 32]));
}

#[test]
fn blinded_intercept_payment() {
	do_blinded_intercept_payment(true);
	do_blinded_intercept_payment(false);
}
fn do_blinded_intercept_payment(intercept_node_fails: bool) {
	let chanmon_cfgs = create_chanmon_cfgs(3);
	let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
	let mut intercept_forwards_config = test_default_channel_config();
	intercept_forwards_config.accept_intercept_htlcs = true;
	let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, Some(intercept_forwards_config), None]);
	let nodes = create_network(3, &node_cfgs, &node_chanmgrs);
	create_announced_chan_between_nodes_with_value(&nodes, 0, 1, 1_000_000, 0);
	let (channel_id, chan_upd) = {
		let chan = create_announced_chan_between_nodes_with_value(&nodes, 1, 2, 1_000_000, 0);
		(chan.2, chan.0.contents)
	};

	let amt_msat = 5000;
	let (payment_preimage, payment_hash, payment_secret) = get_payment_preimage_hash(&nodes[2], Some(amt_msat), None);
	let intercept_scid = nodes[1].node.get_intercept_scid();
	let mut intercept_chan_upd = chan_upd;
	intercept_chan_upd.short_channel_id = intercept_scid;
	let route_params = get_blinded_route_parameters(amt_msat, payment_secret,
		nodes.iter().skip(1).map(|n| n.node.get_our_node_id()).collect(), &[&intercept_chan_upd],
		&chanmon_cfgs[2].keys_manager);

	nodes[0].node.send_payment(payment_hash, RecipientOnionFields::spontaneous_empty(),
	PaymentId(payment_hash.0), route_params, Retry::Attempts(0)).unwrap();
	check_added_monitors(&nodes[0], 1);
	let payment_event = {
		let mut events = nodes[0].node.get_and_clear_pending_msg_events();
		assert_eq!(events.len(), 1);
		SendEvent::from_event(events.remove(0))
	};
	nodes[1].node.handle_update_add_htlc(&nodes[0].node.get_our_node_id(), &payment_event.msgs[0]);
	commitment_signed_dance!(nodes[1], nodes[0], &payment_event.commitment_msg, false, true);

	let events = nodes[1].node.get_and_clear_pending_events();
	assert_eq!(events.len(), 1);
	let (intercept_id, expected_outbound_amount_msat) = match events[0] {
		crate::events::Event::HTLCIntercepted {
			intercept_id, payment_hash: pmt_hash,
			requested_next_hop_scid: short_channel_id, expected_outbound_amount_msat, ..
		} => {
			assert_eq!(pmt_hash, payment_hash);
			assert_eq!(short_channel_id, intercept_scid);
			(intercept_id, expected_outbound_amount_msat)
		},
		_ => panic!()
	};

	if intercept_node_fails {
		nodes[1].node.fail_intercepted_htlc(intercept_id).unwrap();
		expect_pending_htlcs_forwardable_and_htlc_handling_failed_ignore!(nodes[1], vec![HTLCDestination::UnknownNextHop { requested_forward_scid: intercept_scid }]);
		nodes[1].node.process_pending_htlc_forwards();
		let update_fail = get_htlc_update_msgs!(nodes[1], nodes[0].node.get_our_node_id());
		check_added_monitors!(&nodes[1], 1);
		assert!(update_fail.update_fail_htlcs.len() == 1);
		let fail_msg = update_fail.update_fail_htlcs[0].clone();
		nodes[0].node.handle_update_fail_htlc(&nodes[1].node.get_our_node_id(), &fail_msg);
		commitment_signed_dance!(nodes[0], nodes[1], update_fail.commitment_signed, false);
		expect_payment_failed_conditions(&nodes[0], payment_hash, false,
			PaymentFailedConditions::new().expected_htlc_error_data(INVALID_ONION_BLINDING, &[0; 32]));
		return
	}

	nodes[1].node.forward_intercepted_htlc(intercept_id, &channel_id, nodes[2].node.get_our_node_id(), expected_outbound_amount_msat).unwrap();
	expect_pending_htlcs_forwardable!(nodes[1]);

	let payment_event = {
		{
			let mut added_monitors = nodes[1].chain_monitor.added_monitors.lock().unwrap();
			assert_eq!(added_monitors.len(), 1);
			added_monitors.clear();
		}
		let mut events = nodes[1].node.get_and_clear_pending_msg_events();
		assert_eq!(events.len(), 1);
		SendEvent::from_event(events.remove(0))
	};
	nodes[2].node.handle_update_add_htlc(&nodes[1].node.get_our_node_id(), &payment_event.msgs[0]);
	commitment_signed_dance!(nodes[2], nodes[1], &payment_event.commitment_msg, false, true);
	expect_pending_htlcs_forwardable!(nodes[2]);

	expect_payment_claimable!(&nodes[2], payment_hash, payment_secret, amt_msat, None, nodes[2].node.get_our_node_id());
	do_claim_payment_along_route(&nodes[0], &vec!(&vec!(&nodes[1], &nodes[2])[..]), false, payment_preimage);
	expect_payment_sent(&nodes[0], payment_preimage, Some(Some(1000)), true, true);
}

#[test]
fn two_hop_blinded_path_success() {
	let chanmon_cfgs = create_chanmon_cfgs(3);
	let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
	let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, None, None]);
	let mut nodes = create_network(3, &node_cfgs, &node_chanmgrs);
	create_announced_chan_between_nodes_with_value(&nodes, 0, 1, 1_000_000, 0);
	let chan_upd_1_2 = create_announced_chan_between_nodes_with_value(&nodes, 1, 2, 1_000_000, 0).0.contents;

	let amt_msat = 5000;
	let (payment_preimage, payment_hash, payment_secret) = get_payment_preimage_hash(&nodes[2], Some(amt_msat), None);
	let route_params = get_blinded_route_parameters(amt_msat, payment_secret,
		nodes.iter().skip(1).map(|n| n.node.get_our_node_id()).collect(), &[&chan_upd_1_2],
		&chanmon_cfgs[2].keys_manager);

	nodes[0].node.send_payment(payment_hash, RecipientOnionFields::spontaneous_empty(), PaymentId(payment_hash.0), route_params, Retry::Attempts(0)).unwrap();
	check_added_monitors(&nodes[0], 1);
	pass_along_route(&nodes[0], &[&[&nodes[1], &nodes[2]]], amt_msat, payment_hash, payment_secret);
	claim_payment(&nodes[0], &[&nodes[1], &nodes[2]], payment_preimage);
}

#[test]
fn three_hop_blinded_path_success() {
	let chanmon_cfgs = create_chanmon_cfgs(5);
	let node_cfgs = create_node_cfgs(5, &chanmon_cfgs);
	let node_chanmgrs = create_node_chanmgrs(5, &node_cfgs, &[None, None, None, None, None]);
	let mut nodes = create_network(5, &node_cfgs, &node_chanmgrs);
	create_announced_chan_between_nodes_with_value(&nodes, 0, 1, 1_000_000, 0);
	create_announced_chan_between_nodes_with_value(&nodes, 1, 2, 1_000_000, 0);
	let chan_upd_2_3 = create_announced_chan_between_nodes_with_value(&nodes, 2, 3, 1_000_000, 0).0.contents;
	let chan_upd_3_4 = create_announced_chan_between_nodes_with_value(&nodes, 3, 4, 1_000_000, 0).0.contents;

	let amt_msat = 5000;
	let (payment_preimage, payment_hash, payment_secret) = get_payment_preimage_hash(&nodes[4], Some(amt_msat), None);
	let route_params = get_blinded_route_parameters(amt_msat, payment_secret,
		nodes.iter().skip(2).map(|n| n.node.get_our_node_id()).collect(),
		&[&chan_upd_2_3, &chan_upd_3_4], &chanmon_cfgs[4].keys_manager);

	nodes[0].node.send_payment(payment_hash, RecipientOnionFields::spontaneous_empty(), PaymentId(payment_hash.0), route_params, Retry::Attempts(0)).unwrap();
	check_added_monitors(&nodes[0], 1);
	pass_along_route(&nodes[0], &[&[&nodes[1], &nodes[2], &nodes[3], &nodes[4]]], amt_msat, payment_hash, payment_secret);
	claim_payment(&nodes[0], &[&nodes[1], &nodes[2], &nodes[3], &nodes[4]], payment_preimage);
}

#[derive(PartialEq)]
enum ReceiveCheckFail {
	// The recipient fails the payment upon `PaymentClaimable`.
	RecipientFail,
	// Failure to decode the recipient's onion payload.
	OnionDecodeFail,
	// The incoming HTLC did not satisfy our requirements; in this case it underpaid us according to
	// the expected receive amount in the onion.
	ReceiveRequirements,
	// The incoming HTLC errors when added to the Channel, in this case due to the HTLC being
	// delivered out-of-order with a shutdown message.
	ChannelCheck,
	// The HTLC is successfully added to the inbound channel but fails receive checks in
	// process_pending_htlc_forwards.
	ProcessPendingHTLCsCheck,
	// The HTLC violates the `PaymentConstraints` contained within the receiver's encrypted payload.
	PaymentConstraints,
}

#[test]
fn multi_hop_receiver_fail() {
	do_multi_hop_receiver_fail(ReceiveCheckFail::RecipientFail);
	do_multi_hop_receiver_fail(ReceiveCheckFail::OnionDecodeFail);
	do_multi_hop_receiver_fail(ReceiveCheckFail::ReceiveRequirements);
	do_multi_hop_receiver_fail(ReceiveCheckFail::ChannelCheck);
	do_multi_hop_receiver_fail(ReceiveCheckFail::ProcessPendingHTLCsCheck);
	do_multi_hop_receiver_fail(ReceiveCheckFail::PaymentConstraints);
}

fn do_multi_hop_receiver_fail(check: ReceiveCheckFail) {
	// Test that the receiver to a multihop blinded path fails back correctly.
	let chanmon_cfgs = create_chanmon_cfgs(3);
	let node_cfgs = create_node_cfgs(3, &chanmon_cfgs);
	let node_chanmgrs = create_node_chanmgrs(3, &node_cfgs, &[None, None, None]);
	let mut nodes = create_network(3, &node_cfgs, &node_chanmgrs);
	// We need the session priv to construct an invalid onion packet later.
	let session_priv = [3; 32];
	*nodes[0].keys_manager.override_random_bytes.lock().unwrap() = Some(session_priv);
	create_announced_chan_between_nodes_with_value(&nodes, 0, 1, 1_000_000, 0);
	let (chan_upd_1_2, chan_id_1_2) = {
		let (chan_upd, _, channel_id, ..) = create_announced_chan_between_nodes_with_value(
			&nodes, 1, 2, 1_000_000, 0
		);
		(chan_upd.contents, channel_id)
	};

	let amt_msat = 5000;
	let excess_final_cltv_delta_opt = if check == ReceiveCheckFail::ProcessPendingHTLCsCheck {
		// Set the final CLTV expiry too low to trigger the failure in process_pending_htlc_forwards.
		Some(TEST_FINAL_CLTV as u16 - 2)
	} else { None };
	let (_, payment_hash, payment_secret) = get_payment_preimage_hash(&nodes[2], Some(amt_msat), excess_final_cltv_delta_opt);
	let mut route_params = get_blinded_route_parameters(amt_msat, payment_secret,
		nodes.iter().skip(1).map(|n| n.node.get_our_node_id()).collect(), &[&chan_upd_1_2],
		&chanmon_cfgs[2].keys_manager);

	let route = if check == ReceiveCheckFail::ProcessPendingHTLCsCheck {
		let mut route = get_route(&nodes[0], &route_params).unwrap();
		// Set the final CLTV expiry too low to trigger the failure in process_pending_htlc_forwards.
		route.paths[0].hops.last_mut().map(|h| h.cltv_expiry_delta += excess_final_cltv_delta_opt.unwrap() as u32);
		route.paths[0].blinded_tail.as_mut().map(|bt| bt.excess_final_cltv_expiry_delta = excess_final_cltv_delta_opt.unwrap() as u32);
		route
	} else if check == ReceiveCheckFail::PaymentConstraints {
		// Create a blinded path where the receiver's encrypted payload has an htlc_minimum_msat that is
		// violated by `amt_msat`, and stick it in the route_params without changing the corresponding
		// BlindedPayInfo (to ensure pathfinding still succeeds).
		let high_htlc_min_bp = {
			let mut high_htlc_minimum_upd = chan_upd_1_2.clone();
			high_htlc_minimum_upd.htlc_minimum_msat = amt_msat + 1000;
			let high_htlc_min_params = get_blinded_route_parameters(amt_msat, payment_secret,
				nodes.iter().skip(1).map(|n| n.node.get_our_node_id()).collect(), &[&high_htlc_minimum_upd],
				&chanmon_cfgs[2].keys_manager);
			if let Payee::Blinded { route_hints, .. } = high_htlc_min_params.payment_params.payee {
				route_hints[0].1.clone()
			} else { panic!() }
		};
		if let Payee::Blinded { ref mut route_hints, .. } = route_params.payment_params.payee {
			route_hints[0].1 = high_htlc_min_bp;
		} else { panic!() }
		find_route(&nodes[0], &route_params).unwrap()
	} else {
		find_route(&nodes[0], &route_params).unwrap()
	};
	node_cfgs[0].router.expect_find_route(route_params.clone(), Ok(route.clone()));
	nodes[0].node.send_payment(payment_hash, RecipientOnionFields::spontaneous_empty(), PaymentId(payment_hash.0), route_params, Retry::Attempts(0)).unwrap();
	check_added_monitors(&nodes[0], 1);

	let mut payment_event_0_1 = {
		let mut events = nodes[0].node.get_and_clear_pending_msg_events();
		assert_eq!(events.len(), 1);
		let ev = remove_first_msg_event_to_node(&nodes[1].node.get_our_node_id(), &mut events);
		SendEvent::from_event(ev)
	};
	nodes[1].node.handle_update_add_htlc(&nodes[0].node.get_our_node_id(), &payment_event_0_1.msgs[0]);
	check_added_monitors!(nodes[1], 0);
	do_commitment_signed_dance(&nodes[1], &nodes[0], &payment_event_0_1.commitment_msg, false, false);
	expect_pending_htlcs_forwardable!(nodes[1]);
	check_added_monitors!(&nodes[1], 1);

	let mut payment_event_1_2 = {
		let mut events = nodes[1].node.get_and_clear_pending_msg_events();
		assert_eq!(events.len(), 1);
		let ev = remove_first_msg_event_to_node(&nodes[2].node.get_our_node_id(), &mut events);
		SendEvent::from_event(ev)
	};

	match check {
		ReceiveCheckFail::RecipientFail => {
			nodes[2].node.handle_update_add_htlc(&nodes[1].node.get_our_node_id(), &payment_event_1_2.msgs[0]);
			check_added_monitors!(nodes[2], 0);
			do_commitment_signed_dance(&nodes[2], &nodes[1], &payment_event_1_2.commitment_msg, true, true);
			expect_pending_htlcs_forwardable!(nodes[2]);
			check_payment_claimable(
				&nodes[2].node.get_and_clear_pending_events()[0], payment_hash, payment_secret, amt_msat,
				None, nodes[2].node.get_our_node_id()
			);
			nodes[2].node.fail_htlc_backwards(&payment_hash);
			expect_pending_htlcs_forwardable_conditions(
				nodes[2].node.get_and_clear_pending_events(), &[HTLCDestination::FailedPayment { payment_hash }]
			);
			nodes[2].node.process_pending_htlc_forwards();
			check_added_monitors!(nodes[2], 1);
		},
		ReceiveCheckFail::OnionDecodeFail => {
			let session_priv = SecretKey::from_slice(&session_priv).unwrap();
			let mut onion_keys = onion_utils::construct_onion_keys(&Secp256k1::new(), &route.paths[0], &session_priv).unwrap();
			let cur_height = nodes[0].best_block_info().1;
			let (mut onion_payloads, ..) = onion_utils::build_onion_payloads(
				&route.paths[0], amt_msat, RecipientOnionFields::spontaneous_empty(), cur_height, &None).unwrap();

			let update_add = &mut payment_event_1_2.msgs[0];
			onion_payloads.last_mut().map(|p| {
				if let msgs::OutboundOnionPayload::BlindedReceive { ref mut intro_node_blinding_point, .. } = p {
					// The receiver should error if both the update_add blinding_point and the
					// intro_node_blinding_point are set.
					assert!(intro_node_blinding_point.is_none() && update_add.blinding_point.is_some());
					*intro_node_blinding_point = Some(PublicKey::from_slice(&[2; 33]).unwrap());
				} else { panic!() }
			});
			update_add.onion_routing_packet = onion_utils::construct_onion_packet(
				vec![onion_payloads.pop().unwrap()], vec![onion_keys.pop().unwrap()], [0; 32],
				&payment_hash
			).unwrap();
			nodes[2].node.handle_update_add_htlc(&nodes[1].node.get_our_node_id(), update_add);
			check_added_monitors!(nodes[2], 0);
			do_commitment_signed_dance(&nodes[2], &nodes[1], &payment_event_1_2.commitment_msg, true, true);
		},
		ReceiveCheckFail::ReceiveRequirements => {
			let update_add = &mut payment_event_1_2.msgs[0];
			update_add.amount_msat -= 1;
			nodes[2].node.handle_update_add_htlc(&nodes[1].node.get_our_node_id(), update_add);
			check_added_monitors!(nodes[2], 0);
			do_commitment_signed_dance(&nodes[2], &nodes[1], &payment_event_1_2.commitment_msg, true, true);
		},
		ReceiveCheckFail::ChannelCheck => {
			nodes[2].node.close_channel(&chan_id_1_2, &nodes[1].node.get_our_node_id()).unwrap();
			let node_2_shutdown = get_event_msg!(nodes[2], MessageSendEvent::SendShutdown, nodes[1].node.get_our_node_id());
			nodes[1].node.handle_shutdown(&nodes[2].node.get_our_node_id(), &node_2_shutdown);
			let node_1_shutdown = get_event_msg!(nodes[1], MessageSendEvent::SendShutdown, nodes[2].node.get_our_node_id());

			nodes[2].node.handle_update_add_htlc(&nodes[1].node.get_our_node_id(), &payment_event_1_2.msgs[0]);
			nodes[2].node.handle_commitment_signed(&nodes[1].node.get_our_node_id(), &payment_event_1_2.commitment_msg);
			check_added_monitors!(nodes[2], 1);

			nodes[2].node.handle_shutdown(&nodes[1].node.get_our_node_id(), &node_1_shutdown);
			commitment_signed_dance!(nodes[2], nodes[1], (), false, true, false, false);
		},
		ReceiveCheckFail::ProcessPendingHTLCsCheck => {
			assert_eq!(payment_event_1_2.msgs[0].cltv_expiry, nodes[0].best_block_info().1 + 1 + excess_final_cltv_delta_opt.unwrap() as u32);
			nodes[2].node.handle_update_add_htlc(&nodes[1].node.get_our_node_id(), &payment_event_1_2.msgs[0]);
			check_added_monitors!(nodes[2], 0);
			do_commitment_signed_dance(&nodes[2], &nodes[1], &payment_event_1_2.commitment_msg, true, true);
			expect_pending_htlcs_forwardable!(nodes[2]);
			expect_pending_htlcs_forwardable_and_htlc_handling_failed_ignore!(nodes[2],
				vec![HTLCDestination::FailedPayment { payment_hash }]);
			check_added_monitors!(nodes[2], 1);
		},
		ReceiveCheckFail::PaymentConstraints => {
			nodes[2].node.handle_update_add_htlc(&nodes[1].node.get_our_node_id(), &payment_event_1_2.msgs[0]);
			check_added_monitors!(nodes[2], 0);
			do_commitment_signed_dance(&nodes[2], &nodes[1], &payment_event_1_2.commitment_msg, true, true);
		}
	}

	let updates_2_1 = get_htlc_update_msgs!(nodes[2], nodes[1].node.get_our_node_id());
	assert_eq!(updates_2_1.update_fail_malformed_htlcs.len(), 1);
	let update_malformed = &updates_2_1.update_fail_malformed_htlcs[0];
	assert_eq!(update_malformed.sha256_of_onion, [0; 32]);
	assert_eq!(update_malformed.failure_code, INVALID_ONION_BLINDING);
	nodes[1].node.handle_update_fail_malformed_htlc(&nodes[2].node.get_our_node_id(), update_malformed);
	do_commitment_signed_dance(&nodes[1], &nodes[2], &updates_2_1.commitment_signed, true, false);

	let updates_1_0 = if check == ReceiveCheckFail::ChannelCheck {
		let events = nodes[1].node.get_and_clear_pending_msg_events();
		assert_eq!(events.len(), 2);
		events.into_iter().find_map(|ev| {
			match ev {
				MessageSendEvent:: UpdateHTLCs { node_id, updates } => {
					assert_eq!(node_id, nodes[0].node.get_our_node_id());
					return Some(updates)
				},
				MessageSendEvent::SendClosingSigned { .. } => None,
				_ => panic!()
			}
		}).unwrap()
	} else { get_htlc_update_msgs!(nodes[1], nodes[0].node.get_our_node_id()) };
	assert_eq!(updates_1_0.update_fail_htlcs.len(), 1);
	nodes[0].node.handle_update_fail_htlc(&nodes[1].node.get_our_node_id(), &updates_1_0.update_fail_htlcs[0]);
	do_commitment_signed_dance(&nodes[0], &nodes[1], &updates_1_0.commitment_signed, false, false);
	expect_payment_failed_conditions(&nodes[0], payment_hash, false,
		PaymentFailedConditions::new().expected_htlc_error_data(INVALID_ONION_BLINDING, &[0; 32]));
}

#[test]
fn blinded_path_retries() {
	let chanmon_cfgs = create_chanmon_cfgs(4);
	// Make one blinded path's fees slightly higher so they are tried in a deterministic order.
	let mut higher_fee_chan_cfg = test_default_channel_config();
	higher_fee_chan_cfg.channel_config.forwarding_fee_base_msat += 1;
	let node_cfgs = create_node_cfgs(4, &chanmon_cfgs);
	let node_chanmgrs = create_node_chanmgrs(4, &node_cfgs, &[None, None, Some(higher_fee_chan_cfg), None]);
	let mut nodes = create_network(4, &node_cfgs, &node_chanmgrs);

	// Create this network topology so nodes[0] has a blinded route hint to retry over.
	//      n1
	//    /    \
	// n0       n3
	//    \    /
	//      n2
	create_announced_chan_between_nodes_with_value(&nodes, 0, 1, 1_000_000, 0);
	create_announced_chan_between_nodes_with_value(&nodes, 0, 2, 1_000_000, 0);
	let chan_1_3 = create_announced_chan_between_nodes_with_value(&nodes, 1, 3, 1_000_000, 0);
	let chan_2_3 = create_announced_chan_between_nodes_with_value(&nodes, 2, 3, 1_000_000, 0);

	let amt_msat = 5000;
	let (_, payment_hash, payment_secret) = get_payment_preimage_hash(&nodes[3], Some(amt_msat), None);
	let route_params = {
		let pay_params = PaymentParameters::blinded(
			vec![
				blinded_payment_path(payment_secret,
					vec![nodes[1].node.get_our_node_id(), nodes[3].node.get_our_node_id()], &[&chan_1_3.0.contents],
					&chanmon_cfgs[3].keys_manager
				),
				blinded_payment_path(payment_secret,
					vec![nodes[2].node.get_our_node_id(), nodes[3].node.get_our_node_id()], &[&chan_2_3.0.contents],
					&chanmon_cfgs[3].keys_manager
				),
			]
		)
			.with_bolt12_features(channelmanager::provided_bolt12_invoice_features(&UserConfig::default()))
			.unwrap();
		RouteParameters::from_payment_params_and_value(pay_params, amt_msat)
	};

	nodes[0].node.send_payment(payment_hash, RecipientOnionFields::spontaneous_empty(), PaymentId(payment_hash.0), route_params.clone(), Retry::Attempts(2)).unwrap();
	check_added_monitors(&nodes[0], 1);
	pass_along_route(&nodes[0], &[&[&nodes[1], &nodes[3]]], amt_msat, payment_hash, payment_secret);

	macro_rules! fail_payment_back {
		($intro_node: expr) => {
			nodes[3].node.fail_htlc_backwards(&payment_hash);
			expect_pending_htlcs_forwardable_conditions(
				nodes[3].node.get_and_clear_pending_events(), &[HTLCDestination::FailedPayment { payment_hash }]
			);
			nodes[3].node.process_pending_htlc_forwards();
			check_added_monitors!(nodes[3], 1);

			let updates = get_htlc_update_msgs!(nodes[3], $intro_node.node.get_our_node_id());
			assert_eq!(updates.update_fail_malformed_htlcs.len(), 1);
			let update_malformed = &updates.update_fail_malformed_htlcs[0];
			assert_eq!(update_malformed.sha256_of_onion, [0; 32]);
			assert_eq!(update_malformed.failure_code, INVALID_ONION_BLINDING);
			$intro_node.node.handle_update_fail_malformed_htlc(&nodes[3].node.get_our_node_id(), update_malformed);
			do_commitment_signed_dance(&$intro_node, &nodes[3], &updates.commitment_signed, true, false);

			let updates =  get_htlc_update_msgs!($intro_node, nodes[0].node.get_our_node_id());
			assert_eq!(updates.update_fail_htlcs.len(), 1);
			nodes[0].node.handle_update_fail_htlc(&$intro_node.node.get_our_node_id(), &updates.update_fail_htlcs[0]);
			do_commitment_signed_dance(&nodes[0], &$intro_node, &updates.commitment_signed, false, false);

			let mut events = nodes[0].node.get_and_clear_pending_events();
			assert_eq!(events.len(), 2);
			match events[0] {
				Event::PaymentPathFailed { payment_hash: ev_payment_hash, payment_failed_permanently, ..  } => {
					assert_eq!(payment_hash, ev_payment_hash);
					assert_eq!(payment_failed_permanently, false);
				},
				_ => panic!("Unexpected event"),
			}
			match events[1] {
				Event::PendingHTLCsForwardable { .. } => {},
				_ => panic!("Unexpected event"),
			}
			nodes[0].node.process_pending_htlc_forwards();
		}
	}

	fail_payment_back!(nodes[1]);

	// Pass the retry along.
	check_added_monitors!(nodes[0], 1);
	let mut msg_events = nodes[0].node.get_and_clear_pending_msg_events();
	assert_eq!(msg_events.len(), 1);
	pass_along_path(&nodes[0], &[&nodes[2], &nodes[3]], amt_msat, payment_hash, Some(payment_secret), msg_events.pop().unwrap(), true, None);

	fail_payment_back!(nodes[2]);
	let evs = nodes[0].node.get_and_clear_pending_events();
	assert_eq!(evs.len(), 1);
	match evs[0] {
		Event::PaymentFailed { payment_hash: ev_payment_hash, reason, .. } => {
			assert_eq!(ev_payment_hash, payment_hash);
			// We have 1 retry attempt remaining, but we're out of blinded paths to try.
			assert_eq!(reason, Some(PaymentFailureReason::RouteNotFound));
		},
		_ => panic!()
	}
}