Add an operations section to ChannelManager docs
[rust-lightning] / lightning / src / ln / blinded_payment_tests.rs
index 9b580d1fa7599df71a70cf3d8819d4402545d5c8..198ded1cb4421aa8afbee8848f22c4381f2b7b3d 100644 (file)
@@ -10,7 +10,7 @@
 use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey};
 use crate::blinded_path::BlindedPath;
 use crate::blinded_path::payment::{ForwardNode, ForwardTlvs, PaymentConstraints, PaymentRelay, ReceiveTlvs};
-use crate::events::{HTLCDestination, MessageSendEvent, MessageSendEventsProvider};
+use crate::events::{Event, HTLCDestination, MessageSendEvent, MessageSendEventsProvider, PaymentFailureReason};
 use crate::ln::PaymentSecret;
 use crate::ln::channelmanager;
 use crate::ln::channelmanager::{PaymentId, RecipientOnionFields};
@@ -20,18 +20,22 @@ 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::ln::outbound_payment::{Retry, IDEMPOTENCY_TIMEOUT_TICKS};
+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;
 
-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 {
+fn blinded_payment_path(
+       payment_secret: PaymentSecret, intro_node_min_htlc: u64, intro_node_max_htlc: u64,
+       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) {
+       let mut intro_node_min_htlc_opt = Some(intro_node_min_htlc);
+       let mut intro_node_max_htlc_opt = Some(intro_node_max_htlc);
+       for (idx, (node_id, chan_upd)) in node_ids.iter().zip(channel_upds).enumerate() {
                intermediate_nodes.push(ForwardNode {
                        node_id: *node_id,
                        tlvs: ForwardTlvs {
@@ -43,28 +47,43 @@ pub fn get_blinded_route_parameters(
                                },
                                payment_constraints: PaymentConstraints {
                                        max_cltv_expiry: u32::max_value(),
-                                       htlc_minimum_msat: chan_upd.htlc_minimum_msat,
+                                       htlc_minimum_msat: intro_node_min_htlc_opt.take()
+                                               .unwrap_or_else(|| channel_upds[idx - 1].htlc_minimum_msat),
                                },
                                features: BlindedHopFeatures::empty(),
                        },
-                       htlc_maximum_msat: chan_upd.htlc_maximum_msat,
+                       htlc_maximum_msat: intro_node_max_htlc_opt.take()
+                               .unwrap_or_else(|| channel_upds[idx - 1].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,
+                       htlc_minimum_msat:
+                               intro_node_min_htlc_opt.unwrap_or_else(|| channel_upds.last().unwrap().htlc_minimum_msat),
                },
        };
        let mut secp_ctx = Secp256k1::new();
-       let blinded_path = BlindedPath::new_for_payment(
+       BlindedPath::new_for_payment(
                &intermediate_nodes[..], *node_ids.last().unwrap(), payee_tlvs,
-               channel_upds.last().unwrap().htlc_maximum_msat, keys_manager, &secp_ctx
-       ).unwrap();
+               intro_node_max_htlc_opt.unwrap_or_else(|| channel_upds.last().unwrap().htlc_maximum_msat),
+               TEST_FINAL_CLTV as u16, keys_manager, &secp_ctx
+       ).unwrap()
+}
 
+pub fn get_blinded_route_parameters(
+       amt_msat: u64, payment_secret: PaymentSecret, intro_node_min_htlc: u64, intro_node_max_htlc: u64,
+       node_ids: Vec<PublicKey>, channel_upds: &[&msgs::UnsignedChannelUpdate],
+       keys_manager: &test_utils::TestKeysInterface
+) -> RouteParameters {
        RouteParameters::from_payment_params_and_value(
-               PaymentParameters::blinded(vec![blinded_path]), amt_msat
+               PaymentParameters::blinded(vec![
+                       blinded_payment_path(
+                               payment_secret, intro_node_min_htlc, intro_node_max_htlc, node_ids, channel_upds,
+                               keys_manager
+                       )
+               ]), amt_msat
        )
 }
 
@@ -92,7 +111,8 @@ fn do_one_hop_blinded_path(success: bool) {
        };
        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
+               nodes[1].node.get_our_node_id(), payee_tlvs, TEST_FINAL_CLTV as u16,
+               &chanmon_cfgs[1].keys_manager, &secp_ctx
        ).unwrap();
 
        let route_params = RouteParameters::from_payment_params_and_value(
@@ -133,7 +153,8 @@ fn mpp_to_one_hop_blinded_path() {
                },
        };
        let blinded_path = BlindedPath::one_hop_for_payment(
-               nodes[3].node.get_our_node_id(), payee_tlvs, &chanmon_cfgs[3].keys_manager, &secp_ctx
+               nodes[3].node.get_our_node_id(), payee_tlvs, TEST_FINAL_CLTV as u16,
+               &chanmon_cfgs[3].keys_manager, &secp_ctx
        ).unwrap();
 
        let bolt12_features =
@@ -159,6 +180,70 @@ fn mpp_to_one_hop_blinded_path() {
        claim_payment_along_route(&nodes[0], expected_route, false, payment_preimage);
 }
 
+#[test]
+fn mpp_to_three_hop_blinded_paths() {
+       let chanmon_cfgs = create_chanmon_cfgs(6);
+       let node_cfgs = create_node_cfgs(6, &chanmon_cfgs);
+       let node_chanmgrs = create_node_chanmgrs(6, &node_cfgs, &[None, None, None, None, None, None]);
+       let nodes = create_network(6, &node_cfgs, &node_chanmgrs);
+
+       // Create this network topology so node 0 MPP's over 2 3-hop blinded paths:
+       //     n1 -- n3
+       //    /        \
+       // n0           n5
+       //    \        /
+       //     n2 -- n4
+       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;
+       let chan_upd_2_4 = create_announced_chan_between_nodes(&nodes, 2, 4).0.contents;
+       let chan_upd_3_5 = create_announced_chan_between_nodes(&nodes, 3, 5).0.contents;
+       let chan_upd_4_5 = create_announced_chan_between_nodes(&nodes, 4, 5).0.contents;
+
+       let amt_msat = 15_000_000;
+       let (payment_preimage, payment_hash, payment_secret) = get_payment_preimage_hash(&nodes[5], Some(amt_msat), None);
+       let route_params = {
+               let path_1_params = get_blinded_route_parameters(
+                       amt_msat, payment_secret, 1, 1_0000_0000, vec![
+                               nodes[1].node.get_our_node_id(), nodes[3].node.get_our_node_id(),
+                               nodes[5].node.get_our_node_id()
+                       ], &[&chan_upd_1_3, &chan_upd_3_5], &chanmon_cfgs[5].keys_manager
+               );
+               let path_2_params = get_blinded_route_parameters(
+                       amt_msat, payment_secret, 1, 1_0000_0000, vec![
+                               nodes[2].node.get_our_node_id(), nodes[4].node.get_our_node_id(),
+                               nodes[5].node.get_our_node_id()
+                       ], &[&chan_upd_2_4, &chan_upd_4_5], &chanmon_cfgs[5].keys_manager
+               );
+               let pay_params = PaymentParameters::blinded(
+                       vec![
+                               path_1_params.payment_params.payee.blinded_route_hints()[0].clone(),
+                               path_2_params.payment_params.payee.blinded_route_hints()[0].clone()
+                       ]
+               )
+                       .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, Retry::Attempts(0)).unwrap();
+       check_added_monitors(&nodes[0], 2);
+
+       let expected_route: &[&[&Node]] = &[&[&nodes[1], &nodes[3], &nodes[5]], &[&nodes[2], &nodes[4], &nodes[5]]];
+       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.
@@ -171,63 +256,108 @@ enum ForwardCheckFail {
 
 #[test]
 fn forward_checks_failure() {
-       do_forward_checks_failure(ForwardCheckFail::InboundOnionCheck);
-       do_forward_checks_failure(ForwardCheckFail::ForwardPayloadEncodedAsReceive);
-       do_forward_checks_failure(ForwardCheckFail::OutboundChannelCheck);
+       do_forward_checks_failure(ForwardCheckFail::InboundOnionCheck, true);
+       do_forward_checks_failure(ForwardCheckFail::InboundOnionCheck, false);
+       do_forward_checks_failure(ForwardCheckFail::ForwardPayloadEncodedAsReceive, true);
+       do_forward_checks_failure(ForwardCheckFail::ForwardPayloadEncodedAsReceive, false);
+       do_forward_checks_failure(ForwardCheckFail::OutboundChannelCheck, true);
+       do_forward_checks_failure(ForwardCheckFail::OutboundChannelCheck, false);
 }
 
-fn do_forward_checks_failure(check: ForwardCheckFail) {
+fn do_forward_checks_failure(check: ForwardCheckFail, intro_fails: bool) {
        // 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);
+       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 mut nodes = create_network(4, &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 chan_upd_2_3 = create_announced_chan_between_nodes_with_value(&nodes, 2, 3, 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 (_, payment_hash, payment_secret) = get_payment_preimage_hash(&nodes[3], Some(amt_msat), None);
+       let route_params = get_blinded_route_parameters(amt_msat, payment_secret, 1, 1_0000_0000,
+               nodes.iter().skip(1).map(|n| n.node.get_our_node_id()).collect(),
+               &[&chan_upd_1_2, &chan_upd_2_3], &chanmon_cfgs[3].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);
+       macro_rules! cause_error {
+               ($src_node_idx: expr, $target_node_idx: expr, $update_add: expr) => {
+                       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();
+                                       if $target_node_idx + 1 < nodes.len() {
+                                               onion_payloads.pop();
+                                       }
+                                       $update_add.onion_routing_packet = onion_utils::construct_onion_packet(onion_payloads, onion_keys, [0; 32], &payment_hash).unwrap();
+                               },
+                               ForwardCheckFail::OutboundChannelCheck => {
+                                       // The intro node will see that the next-hop peer is disconnected and fail the HTLC backwards.
+                                       nodes[$src_node_idx].node.peer_disconnected(&nodes[$target_node_idx].node.get_our_node_id());
+                               }
+                       }
+               }
+       }
 
-       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());
-               },
+       let mut updates_0_1 = get_htlc_update_msgs!(nodes[0], nodes[1].node.get_our_node_id());
+       let update_add = &mut updates_0_1.update_add_htlcs[0];
+
+       if intro_fails {
+               cause_error!(1, 2, update_add);
        }
-       nodes[1].node.handle_update_add_htlc(&nodes[0].node.get_our_node_id(), &payment_event.msgs[0]);
+
+       nodes[1].node.handle_update_add_htlc(&nodes[0].node.get_our_node_id(), &update_add);
        check_added_monitors!(nodes[1], 0);
-       do_commitment_signed_dance(&nodes[1], &nodes[0], &payment_event.commitment_msg, true, true);
+       do_commitment_signed_dance(&nodes[1], &nodes[0], &updates_0_1.commitment_signed, true, true);
+
+       if intro_fails {
+               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]));
+               return
+       }
+
+       expect_pending_htlcs_forwardable!(nodes[1]);
+       check_added_monitors!(nodes[1], 1);
+
+       let mut updates_1_2 = get_htlc_update_msgs!(nodes[1], nodes[2].node.get_our_node_id());
+       let mut update_add = &mut updates_1_2.update_add_htlcs[0];
+
+       cause_error!(2, 3, update_add);
+
+       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], &updates_1_2.commitment_signed, true, true);
+
+       let mut updates = get_htlc_update_msgs!(nodes[2], nodes[1].node.get_our_node_id());
+       let update_malformed = &mut updates.update_fail_malformed_htlcs[0];
+       assert_eq!(update_malformed.failure_code, INVALID_ONION_BLINDING);
+       assert_eq!(update_malformed.sha256_of_onion, [0; 32]);
+
+       // Ensure the intro node will properly blind the error if its downstream node failed to do so.
+       update_malformed.sha256_of_onion = [1; 32];
+       update_malformed.failure_code = INVALID_ONION_BLINDING ^ 1;
+       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]);
@@ -249,7 +379,7 @@ fn failed_backwards_to_intro_node() {
 
        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,
+       let route_params = get_blinded_route_parameters(amt_msat, payment_secret, 1, 1_0000_0000,
                nodes.iter().skip(1).map(|n| n.node.get_our_node_id()).collect(), &[&chan_upd_1_2],
                &chanmon_cfgs[2].keys_manager);
 
@@ -305,26 +435,32 @@ enum ProcessPendingHTLCsCheck {
 
 #[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);
+       do_forward_fail_in_process_pending_htlc_fwds(ProcessPendingHTLCsCheck::FwdPeerDisconnected, true);
+       do_forward_fail_in_process_pending_htlc_fwds(ProcessPendingHTLCsCheck::FwdPeerDisconnected, false);
+       do_forward_fail_in_process_pending_htlc_fwds(ProcessPendingHTLCsCheck::FwdChannelClosed, true);
+       do_forward_fail_in_process_pending_htlc_fwds(ProcessPendingHTLCsCheck::FwdChannelClosed, false);
 }
-fn do_forward_fail_in_process_pending_htlc_fwds(check: ProcessPendingHTLCsCheck) {
+fn do_forward_fail_in_process_pending_htlc_fwds(check: ProcessPendingHTLCsCheck, intro_fails: bool) {
        // 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);
+       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 mut nodes = create_network(4, &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_upd_1_2, chan_id_1_2) = {
                let chan = create_announced_chan_between_nodes_with_value(&nodes, 1, 2, 1_000_000, 0);
                (chan.0.contents, chan.2)
        };
+       let (chan_upd_2_3, chan_id_2_3) = {
+               let chan = create_announced_chan_between_nodes_with_value(&nodes, 2, 3, 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],
+       let route_params = get_blinded_route_parameters(amt_msat, payment_secret, 1, 1_0000_0000,
+               nodes.iter().skip(1).map(|n| n.node.get_our_node_id()).collect(), &[&chan_upd_1_2, &chan_upd_2_3],
                &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();
@@ -339,43 +475,80 @@ fn do_forward_fail_in_process_pending_htlc_fwds(check: ProcessPendingHTLCsCheck)
        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),
+       macro_rules! cause_error {
+               ($prev_node: expr, $curr_node: expr, $next_node: expr, $failed_chan_id: expr, $failed_scid: expr) => {
+                       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.
+                                       $curr_node.node.peer_disconnected(&$next_node.node.get_our_node_id());
+                                       expect_pending_htlcs_forwardable!($curr_node);
+                                       expect_pending_htlcs_forwardable_and_htlc_handling_failed_ignore!($curr_node,
+                                               vec![HTLCDestination::NextHopChannel { node_id: Some($next_node.node.get_our_node_id()), channel_id: $failed_chan_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.
+                                       $curr_node.node.force_close_broadcasting_latest_txn(&$failed_chan_id, &$next_node.node.get_our_node_id()).unwrap();
+                                       let events = $curr_node.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),
+                                       }
+
+                                       $curr_node.node.process_pending_htlc_forwards();
+                                       expect_pending_htlcs_forwardable_and_htlc_handling_failed_ignore!($curr_node,
+                                               vec![HTLCDestination::UnknownNextHop { requested_forward_scid: $failed_scid }]);
+                                       check_closed_broadcast(&$curr_node, 1, true);
+                                       check_added_monitors!($curr_node, 1);
+                                       $curr_node.node.process_pending_htlc_forwards();
+                               },
                        }
+               }
+       }
 
-                       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();
-               },
+       if intro_fails {
+               cause_error!(nodes[0], nodes[1], nodes[2], chan_id_1_2, chan_upd_1_2.short_channel_id);
+               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]));
+               return
        }
 
+       expect_pending_htlcs_forwardable!(nodes[1]);
+       check_added_monitors!(nodes[1], 1);
+
+       let mut updates_1_2 = get_htlc_update_msgs!(nodes[1], nodes[2].node.get_our_node_id());
+       let mut update_add = &mut updates_1_2.update_add_htlcs[0];
+       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], &updates_1_2.commitment_signed, true, true);
+
+       cause_error!(nodes[1], nodes[2], nodes[3], chan_id_2_3, chan_upd_2_3.short_channel_id);
+       check_added_monitors!(nodes[2], 1);
+
+       let mut updates = get_htlc_update_msgs!(nodes[2], nodes[1].node.get_our_node_id());
+       let update_malformed = &mut updates.update_fail_malformed_htlcs[0];
+       assert_eq!(update_malformed.failure_code, INVALID_ONION_BLINDING);
+       assert_eq!(update_malformed.sha256_of_onion, [0; 32]);
+
+       // Ensure the intro node will properly blind the error if its downstream node failed to do so.
+       update_malformed.sha256_of_onion = [1; 32];
+       update_malformed.failure_code = INVALID_ONION_BLINDING ^ 1;
+       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]);
-       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]));
 }
@@ -403,7 +576,7 @@ fn do_blinded_intercept_payment(intercept_node_fails: bool) {
        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,
+       let route_params = get_blinded_route_parameters(amt_msat, payment_secret, 1, 1_0000_0000,
                nodes.iter().skip(1).map(|n| n.node.get_our_node_id()).collect(), &[&intercept_chan_upd],
                &chanmon_cfgs[2].keys_manager);
 
@@ -480,7 +653,7 @@ fn two_hop_blinded_path_success() {
 
        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,
+       let route_params = get_blinded_route_parameters(amt_msat, payment_secret, 1, 1_0000_0000,
                nodes.iter().skip(1).map(|n| n.node.get_our_node_id()).collect(), &[&chan_upd_1_2],
                &chanmon_cfgs[2].keys_manager);
 
@@ -490,6 +663,88 @@ fn two_hop_blinded_path_success() {
        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;
+
+       // Get all our nodes onto the same height so payments don't fail for CLTV violations.
+       connect_blocks(&nodes[0], nodes[4].best_block_info().1 - nodes[0].best_block_info().1);
+       connect_blocks(&nodes[1], nodes[4].best_block_info().1 - nodes[1].best_block_info().1);
+       connect_blocks(&nodes[2], nodes[4].best_block_info().1 - nodes[2].best_block_info().1);
+       assert_eq!(nodes[4].best_block_info().1, nodes[3].best_block_info().1);
+
+       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, 1, 1_0000_0000,
+               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);
+}
+
+#[test]
+fn three_hop_blinded_path_fail() {
+       // Test that an intermediate blinded forwarding node gets failed back to with
+       // malformed and also fails back themselves with malformed.
+       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 mut nodes = create_network(4, &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 chan_upd_2_3 = create_announced_chan_between_nodes_with_value(&nodes, 2, 3, 1_000_000, 0).0.contents;
+
+       let amt_msat = 5000;
+       let (_, payment_hash, payment_secret) = get_payment_preimage_hash(&nodes[3], Some(amt_msat), None);
+       let route_params = get_blinded_route_parameters(amt_msat, payment_secret, 1, 1_0000_0000,
+               nodes.iter().skip(1).map(|n| n.node.get_our_node_id()).collect(),
+               &[&chan_upd_1_2, &chan_upd_2_3], &chanmon_cfgs[3].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]]], amt_msat, payment_hash, payment_secret);
+
+       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_3_2 = get_htlc_update_msgs!(nodes[3], nodes[2].node.get_our_node_id());
+       assert_eq!(updates_3_2.update_fail_malformed_htlcs.len(), 1);
+       let update_malformed = &updates_3_2.update_fail_malformed_htlcs[0];
+       assert_eq!(update_malformed.sha256_of_onion, [0; 32]);
+       assert_eq!(update_malformed.failure_code, INVALID_ONION_BLINDING);
+       nodes[2].node.handle_update_fail_malformed_htlc(&nodes[3].node.get_our_node_id(), update_malformed);
+       do_commitment_signed_dance(&nodes[2], &nodes[3], &updates_3_2.commitment_signed, true, false);
+
+       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 = 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]));
+}
+
 #[derive(PartialEq)]
 enum ReceiveCheckFail {
        // The recipient fails the payment upon `PaymentClaimable`.
@@ -537,19 +792,20 @@ fn do_multi_hop_receiver_fail(check: ReceiveCheckFail) {
        };
 
        let amt_msat = 5000;
-       let final_cltv_delta = if check == ReceiveCheckFail::ProcessPendingHTLCsCheck {
+       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), final_cltv_delta);
-       let mut route_params = get_blinded_route_parameters(amt_msat, payment_secret,
+       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, 1, 1_0000_0000,
                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].blinded_tail.as_mut().map(|bt| bt.excess_final_cltv_expiry_delta = TEST_FINAL_CLTV - 2);
+               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
@@ -558,7 +814,7 @@ fn do_multi_hop_receiver_fail(check: ReceiveCheckFail) {
                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,
+                       let high_htlc_min_params = get_blinded_route_parameters(amt_msat, payment_secret, 1, 1_0000_0000,
                                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 {
@@ -657,6 +913,7 @@ fn do_multi_hop_receiver_fail(check: ReceiveCheckFail) {
                        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 + TEST_FINAL_CLTV);
                        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);
@@ -700,3 +957,310 @@ fn do_multi_hop_receiver_fail(check: ReceiveCheckFail) {
        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, 1, 1_0000_0000,
+                                       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, 1, 1_0000_0000,
+                                       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!()
+       }
+}
+
+#[test]
+fn min_htlc() {
+       // The min htlc of a blinded path is the max (htlc_min - following_fees) along the path. Make sure
+       // the payment succeeds when we calculate the min htlc this way.
+       let chanmon_cfgs = create_chanmon_cfgs(4);
+       let node_cfgs = create_node_cfgs(4, &chanmon_cfgs);
+       let mut node_1_cfg = test_default_channel_config();
+       node_1_cfg.channel_handshake_config.our_htlc_minimum_msat = 2000;
+       node_1_cfg.channel_config.forwarding_fee_base_msat = 1000;
+       node_1_cfg.channel_config.forwarding_fee_proportional_millionths = 100_000;
+       let mut node_2_cfg = test_default_channel_config();
+       node_2_cfg.channel_handshake_config.our_htlc_minimum_msat = 5000;
+       node_2_cfg.channel_config.forwarding_fee_base_msat = 200;
+       node_2_cfg.channel_config.forwarding_fee_proportional_millionths = 150_000;
+       let mut node_3_cfg = test_default_channel_config();
+       node_3_cfg.channel_handshake_config.our_htlc_minimum_msat = 2000;
+       let node_chanmgrs = create_node_chanmgrs(4, &node_cfgs, &[None, Some(node_1_cfg), Some(node_2_cfg), Some(node_3_cfg)]);
+       let nodes = create_network(4, &node_cfgs, &node_chanmgrs);
+       create_announced_chan_between_nodes_with_value(&nodes, 0, 1, 1_000_000, 0);
+       let chan_1_2 = create_announced_chan_between_nodes_with_value(&nodes, 1, 2, 1_000_000, 0);
+       let chan_2_3 = create_announced_chan_between_nodes_with_value(&nodes, 2, 3, 1_000_000, 0);
+
+       let min_htlc_msat = {
+               // The min htlc for this setup is nodes[2]'s htlc_minimum_msat minus the
+               // following fees.
+               let post_base_fee = chan_2_3.1.contents.htlc_minimum_msat - chan_2_3.0.contents.fee_base_msat as u64;
+               let prop_fee = chan_2_3.0.contents.fee_proportional_millionths as u64;
+               (post_base_fee * 1_000_000 + 1_000_000 + prop_fee - 1) / (prop_fee + 1_000_000)
+       };
+       let (payment_preimage, payment_hash, payment_secret) = get_payment_preimage_hash(&nodes[3], Some(min_htlc_msat), None);
+       let mut route_params = get_blinded_route_parameters(
+               min_htlc_msat, payment_secret, chan_1_2.1.contents.htlc_minimum_msat,
+               chan_1_2.1.contents.htlc_maximum_msat, vec![nodes[1].node.get_our_node_id(),
+               nodes[2].node.get_our_node_id(), nodes[3].node.get_our_node_id()],
+               &[&chan_1_2.0.contents, &chan_2_3.0.contents], &chanmon_cfgs[3].keys_manager);
+       assert_eq!(min_htlc_msat,
+               route_params.payment_params.payee.blinded_route_hints()[0].0.htlc_minimum_msat);
+
+       nodes[0].node.send_payment(payment_hash, RecipientOnionFields::spontaneous_empty(), PaymentId(payment_hash.0), route_params.clone(), Retry::Attempts(0)).unwrap();
+       check_added_monitors(&nodes[0], 1);
+       pass_along_route(&nodes[0], &[&[&nodes[1], &nodes[2], &nodes[3]]], min_htlc_msat, payment_hash, payment_secret);
+       claim_payment(&nodes[0], &[&nodes[1], &nodes[2], &nodes[3]], payment_preimage);
+
+       // Paying 1 less than the min fails.
+       for _ in 0..IDEMPOTENCY_TIMEOUT_TICKS + 1 {
+               nodes[0].node.timer_tick_occurred();
+       }
+       if let Payee::Blinded { ref mut route_hints, .. } = route_params.payment_params.payee {
+               route_hints[0].0.htlc_minimum_msat -= 1;
+       } else { panic!() }
+       route_params.final_value_msat -= 1;
+       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, 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 conditionally_round_fwd_amt() {
+       // Previously, the (rng-found) feerates below caught a bug where an intermediate node would
+       // calculate an amt_to_forward that underpaid them by 1 msat, caused by rounding up the outbound
+       // amount on top of an already rounded-up total routing fee. Ensure that we'll conditionally round
+       // down intermediate nodes' outbound amounts based on whether rounding up will result in
+       // undercharging for relay.
+       let chanmon_cfgs = create_chanmon_cfgs(5);
+       let node_cfgs = create_node_cfgs(5, &chanmon_cfgs);
+
+       let mut node_1_cfg = test_default_channel_config();
+       node_1_cfg.channel_config.forwarding_fee_base_msat = 247371;
+       node_1_cfg.channel_config.forwarding_fee_proportional_millionths = 86552;
+
+       let mut node_2_cfg = test_default_channel_config();
+       node_2_cfg.channel_config.forwarding_fee_base_msat = 198921;
+       node_2_cfg.channel_config.forwarding_fee_proportional_millionths = 681759;
+
+       let mut node_3_cfg = test_default_channel_config();
+       node_3_cfg.channel_config.forwarding_fee_base_msat = 132845;
+       node_3_cfg.channel_config.forwarding_fee_proportional_millionths = 552561;
+
+       let node_chanmgrs = create_node_chanmgrs(5, &node_cfgs, &[None, Some(node_1_cfg), Some(node_2_cfg), Some(node_3_cfg), None]);
+       let nodes = create_network(5, &node_cfgs, &node_chanmgrs);
+       create_announced_chan_between_nodes_with_value(&nodes, 0, 1, 1_000_000, 0);
+       let chan_1_2 = create_announced_chan_between_nodes_with_value(&nodes, 1, 2, 1_000_000, 0);
+       let chan_2_3 = create_announced_chan_between_nodes_with_value(&nodes, 2, 3, 1_000_000, 0);
+       let chan_3_4 = create_announced_chan_between_nodes_with_value(&nodes, 3, 4, 1_000_000, 0);
+
+       let amt_msat = 100_000;
+       let (payment_preimage, payment_hash, payment_secret) = get_payment_preimage_hash(&nodes[4], Some(amt_msat), None);
+       let mut route_params = get_blinded_route_parameters(amt_msat, payment_secret,
+               chan_1_2.1.contents.htlc_minimum_msat, chan_1_2.1.contents.htlc_maximum_msat,
+               vec![nodes[1].node.get_our_node_id(), nodes[2].node.get_our_node_id(),
+               nodes[3].node.get_our_node_id(), nodes[4].node.get_our_node_id()],
+               &[&chan_1_2.0.contents, &chan_2_3.0.contents, &chan_3_4.0.contents],
+               &chanmon_cfgs[4].keys_manager);
+       route_params.max_total_routing_fee_msat = None;
+
+       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);
+       nodes[4].node.claim_funds(payment_preimage);
+       let expected_path = &[&nodes[1], &nodes[2], &nodes[3], &nodes[4]];
+       let expected_route = &[&expected_path[..]];
+       let mut args = ClaimAlongRouteArgs::new(&nodes[0], &expected_route[..], payment_preimage)
+               .allow_1_msat_fee_overpay();
+       let expected_fee = pass_claimed_payment_along_route(args);
+       expect_payment_sent(&nodes[0], payment_preimage, Some(Some(expected_fee)), true, true);
+}
+
+#[test]
+fn blinded_keysend() {
+       let mut mpp_keysend_config = test_default_channel_config();
+       mpp_keysend_config.accept_mpp_keysend = true;
+       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, Some(mpp_keysend_config)]);
+       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 (keysend_preimage, _, payment_secret) = get_payment_preimage_hash(&nodes[2], None, None);
+       let route_params = get_blinded_route_parameters(amt_msat, payment_secret, 1,
+               1_0000_0000,
+               nodes.iter().skip(1).map(|n| n.node.get_our_node_id()).collect(),
+               &[&chan_upd_1_2], &chanmon_cfgs[2].keys_manager);
+
+       let payment_hash = nodes[0].node.send_spontaneous_payment_with_retry(Some(keysend_preimage), RecipientOnionFields::spontaneous_empty(), PaymentId(keysend_preimage.0), route_params, Retry::Attempts(0)).unwrap();
+       check_added_monitors(&nodes[0], 1);
+
+       let expected_route: &[&[&Node]] = &[&[&nodes[1], &nodes[2]]];
+       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);
+       pass_along_path(&nodes[0], expected_route[0], amt_msat, payment_hash, Some(payment_secret), ev.clone(), true, Some(keysend_preimage));
+       claim_payment_along_route(&nodes[0], expected_route, false, keysend_preimage);
+}
+
+#[test]
+fn blinded_mpp_keysend() {
+       let mut mpp_keysend_config = test_default_channel_config();
+       mpp_keysend_config.accept_mpp_keysend = true;
+       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, Some(mpp_keysend_config)]);
+       let nodes = create_network(4, &node_cfgs, &node_chanmgrs);
+
+       create_announced_chan_between_nodes(&nodes, 0, 1);
+       create_announced_chan_between_nodes(&nodes, 0, 2);
+       let chan_1_3 = create_announced_chan_between_nodes(&nodes, 1, 3);
+       let chan_2_3 = create_announced_chan_between_nodes(&nodes, 2, 3);
+
+       let amt_msat = 15_000_000;
+       let (keysend_preimage, _, payment_secret) = get_payment_preimage_hash(&nodes[3], None, None);
+       let route_params = {
+               let pay_params = PaymentParameters::blinded(
+                       vec![
+                               blinded_payment_path(payment_secret, 1, 1_0000_0000,
+                                       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, 1, 1_0000_0000,
+                                       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)
+       };
+
+       let payment_hash = nodes[0].node.send_spontaneous_payment_with_retry(Some(keysend_preimage), RecipientOnionFields::spontaneous_empty(), PaymentId(keysend_preimage.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, Some(keysend_preimage));
+
+       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, Some(keysend_preimage));
+       claim_payment_along_route(&nodes[0], expected_route, false, keysend_preimage);
+}