@@ -1561,6 +1561,133 @@ fn do_test_intercepted_payment(test: InterceptTest) {
15611561 }
15621562}
15631563
1564+ #[ test]
1565+ fn accept_underpaying_htlcs_config ( ) {
1566+ do_accept_underpaying_htlcs_config ( 1 ) ;
1567+ do_accept_underpaying_htlcs_config ( 2 ) ;
1568+ do_accept_underpaying_htlcs_config ( 3 ) ;
1569+ }
1570+
1571+ fn do_accept_underpaying_htlcs_config ( num_mpp_parts : usize ) {
1572+ let chanmon_cfgs = create_chanmon_cfgs ( 3 ) ;
1573+ let node_cfgs = create_node_cfgs ( 3 , & chanmon_cfgs) ;
1574+ let mut intercept_forwards_config = test_default_channel_config ( ) ;
1575+ intercept_forwards_config. accept_intercept_htlcs = true ;
1576+ let mut underpay_config = test_default_channel_config ( ) ;
1577+ underpay_config. channel_config . accept_underpaying_htlcs = true ;
1578+ let node_chanmgrs = create_node_chanmgrs ( 3 , & node_cfgs, & [ None , Some ( intercept_forwards_config) , Some ( underpay_config) ] ) ;
1579+ let nodes = create_network ( 3 , & node_cfgs, & node_chanmgrs) ;
1580+
1581+ let mut chan_ids = Vec :: new ( ) ;
1582+ for _ in 0 ..num_mpp_parts {
1583+ let _ = create_announced_chan_between_nodes_with_value ( & nodes, 0 , 1 , 10_000 , 0 ) ;
1584+ let channel_id = create_unannounced_chan_between_nodes_with_value ( & nodes, 1 , 2 , 2_000_000 , 0 ) . 0 . channel_id ;
1585+ chan_ids. push ( channel_id) ;
1586+ }
1587+
1588+ // Send the initial payment.
1589+ let amt_msat = 900_000 ;
1590+ let skimmed_fee_msat = 20 ;
1591+ let mut route_hints = Vec :: new ( ) ;
1592+ for _ in 0 ..num_mpp_parts {
1593+ route_hints. push ( RouteHint ( vec ! [ RouteHintHop {
1594+ src_node_id: nodes[ 1 ] . node. get_our_node_id( ) ,
1595+ short_channel_id: nodes[ 1 ] . node. get_intercept_scid( ) ,
1596+ fees: RoutingFees {
1597+ base_msat: 1000 ,
1598+ proportional_millionths: 0 ,
1599+ } ,
1600+ cltv_expiry_delta: MIN_CLTV_EXPIRY_DELTA ,
1601+ htlc_minimum_msat: None ,
1602+ htlc_maximum_msat: Some ( amt_msat / num_mpp_parts as u64 + 5 ) ,
1603+ } ] ) ) ;
1604+ }
1605+ let payment_params = PaymentParameters :: from_node_id ( nodes[ 2 ] . node . get_our_node_id ( ) , TEST_FINAL_CLTV )
1606+ . with_route_hints ( route_hints) . unwrap ( )
1607+ . with_bolt11_features ( nodes[ 2 ] . node . invoice_features ( ) ) . unwrap ( ) ;
1608+ let route_params = RouteParameters {
1609+ payment_params,
1610+ final_value_msat : amt_msat,
1611+ } ;
1612+ let ( payment_hash, payment_secret) = nodes[ 2 ] . node . create_inbound_payment ( Some ( amt_msat) , 60 * 60 , None ) . unwrap ( ) ;
1613+ nodes[ 0 ] . node . send_payment ( payment_hash, RecipientOnionFields :: secret_only ( payment_secret) ,
1614+ PaymentId ( payment_hash. 0 ) , route_params, Retry :: Attempts ( 0 ) ) . unwrap ( ) ;
1615+ check_added_monitors ! ( nodes[ 0 ] , num_mpp_parts) ; // one monitor per path
1616+ let mut events: Vec < SendEvent > = nodes[ 0 ] . node . get_and_clear_pending_msg_events ( ) . into_iter ( ) . map ( |e| SendEvent :: from_event ( e) ) . collect ( ) ;
1617+ assert_eq ! ( events. len( ) , num_mpp_parts) ;
1618+
1619+ // Forward the intercepted payments.
1620+ for ( idx, ev) in events. into_iter ( ) . enumerate ( ) {
1621+ nodes[ 1 ] . node . handle_update_add_htlc ( & nodes[ 0 ] . node . get_our_node_id ( ) , & ev. msgs [ 0 ] ) ;
1622+ do_commitment_signed_dance ( & nodes[ 1 ] , & nodes[ 0 ] , & ev. commitment_msg , false , true ) ;
1623+
1624+ let events = nodes[ 1 ] . node . get_and_clear_pending_events ( ) ;
1625+ assert_eq ! ( events. len( ) , 1 ) ;
1626+ let ( intercept_id, expected_outbound_amt_msat) = match events[ 0 ] {
1627+ crate :: events:: Event :: HTLCIntercepted {
1628+ intercept_id, expected_outbound_amount_msat, payment_hash : pmt_hash, ..
1629+ } => {
1630+ assert_eq ! ( pmt_hash, payment_hash) ;
1631+ ( intercept_id, expected_outbound_amount_msat)
1632+ } ,
1633+ _ => panic ! ( )
1634+ } ;
1635+ nodes[ 1 ] . node . forward_intercepted_htlc ( intercept_id, & chan_ids[ idx] ,
1636+ nodes[ 2 ] . node . get_our_node_id ( ) , expected_outbound_amt_msat - skimmed_fee_msat) . unwrap ( ) ;
1637+ expect_pending_htlcs_forwardable ! ( nodes[ 1 ] ) ;
1638+ let payment_event = {
1639+ {
1640+ let mut added_monitors = nodes[ 1 ] . chain_monitor . added_monitors . lock ( ) . unwrap ( ) ;
1641+ assert_eq ! ( added_monitors. len( ) , 1 ) ;
1642+ added_monitors. clear ( ) ;
1643+ }
1644+ let mut events = nodes[ 1 ] . node . get_and_clear_pending_msg_events ( ) ;
1645+ assert_eq ! ( events. len( ) , 1 ) ;
1646+ SendEvent :: from_event ( events. remove ( 0 ) )
1647+ } ;
1648+ nodes[ 2 ] . node . handle_update_add_htlc ( & nodes[ 1 ] . node . get_our_node_id ( ) , & payment_event. msgs [ 0 ] ) ;
1649+ do_commitment_signed_dance ( & nodes[ 2 ] , & nodes[ 1 ] , & payment_event. commitment_msg , false , true ) ;
1650+ if idx == num_mpp_parts - 1 {
1651+ expect_pending_htlcs_forwardable ! ( nodes[ 2 ] ) ;
1652+ }
1653+ }
1654+
1655+ // Claim the payment and check that the skimmed fee is as expected.
1656+ let payment_preimage = nodes[ 2 ] . node . get_payment_preimage ( payment_hash, payment_secret) . unwrap ( ) ;
1657+ let events = nodes[ 2 ] . node . get_and_clear_pending_events ( ) ;
1658+ assert_eq ! ( events. len( ) , 1 ) ;
1659+ match events[ 0 ] {
1660+ crate :: events:: Event :: PaymentClaimable {
1661+ ref payment_hash, ref purpose, amount_msat, counterparty_skimmed_fee_msat, receiver_node_id, ..
1662+ } => {
1663+ assert_eq ! ( payment_hash, payment_hash) ;
1664+ assert_eq ! ( amt_msat - skimmed_fee_msat * num_mpp_parts as u64 , amount_msat) ;
1665+ assert_eq ! ( skimmed_fee_msat * num_mpp_parts as u64 , counterparty_skimmed_fee_msat) ;
1666+ assert_eq ! ( nodes[ 2 ] . node. get_our_node_id( ) , receiver_node_id. unwrap( ) ) ;
1667+ match purpose {
1668+ crate :: events:: PaymentPurpose :: InvoicePayment { payment_preimage : ev_payment_preimage,
1669+ payment_secret : ev_payment_secret, .. } =>
1670+ {
1671+ assert_eq ! ( payment_preimage, ev_payment_preimage. unwrap( ) ) ;
1672+ assert_eq ! ( payment_secret, * ev_payment_secret) ;
1673+ } ,
1674+ _ => panic ! ( ) ,
1675+ }
1676+ } ,
1677+ _ => panic ! ( "Unexpected event" ) ,
1678+ }
1679+ let mut expected_paths_vecs = Vec :: new ( ) ;
1680+ let mut expected_paths = Vec :: new ( ) ;
1681+ for _ in 0 ..num_mpp_parts { expected_paths_vecs. push ( vec ! ( & nodes[ 1 ] , & nodes[ 2 ] ) ) ; }
1682+ for i in 0 ..num_mpp_parts { expected_paths. push ( & expected_paths_vecs[ i] [ ..] ) ; }
1683+ let total_fee_msat = do_claim_payment_along_route_with_extra_penultimate_hop_fees (
1684+ & nodes[ 0 ] , & expected_paths[ ..] , & vec ! [ skimmed_fee_msat as u32 ; num_mpp_parts] [ ..] , false ,
1685+ payment_preimage) ;
1686+ // The sender doesn't know that the penultimate hop took an extra fee.
1687+ expect_payment_sent ( & nodes[ 0 ] , payment_preimage,
1688+ Some ( Some ( total_fee_msat - skimmed_fee_msat * num_mpp_parts as u64 ) ) , true ) ;
1689+ }
1690+
15641691#[ derive( PartialEq ) ]
15651692enum AutoRetry {
15661693 Success ,
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