@@ -1736,6 +1736,133 @@ fn do_test_intercepted_payment(test: InterceptTest) {
17361736 }
17371737}
17381738
1739+ #[ test]
1740+ fn accept_underpaying_htlcs_config ( ) {
1741+ do_accept_underpaying_htlcs_config ( 1 ) ;
1742+ do_accept_underpaying_htlcs_config ( 2 ) ;
1743+ do_accept_underpaying_htlcs_config ( 3 ) ;
1744+ }
1745+
1746+ fn do_accept_underpaying_htlcs_config ( num_mpp_parts : usize ) {
1747+ let chanmon_cfgs = create_chanmon_cfgs ( 3 ) ;
1748+ let node_cfgs = create_node_cfgs ( 3 , & chanmon_cfgs) ;
1749+ let mut intercept_forwards_config = test_default_channel_config ( ) ;
1750+ intercept_forwards_config. accept_intercept_htlcs = true ;
1751+ let mut underpay_config = test_default_channel_config ( ) ;
1752+ underpay_config. channel_config . accept_underpaying_htlcs = true ;
1753+ let node_chanmgrs = create_node_chanmgrs ( 3 , & node_cfgs, & [ None , Some ( intercept_forwards_config) , Some ( underpay_config) ] ) ;
1754+ let nodes = create_network ( 3 , & node_cfgs, & node_chanmgrs) ;
1755+
1756+ let mut chan_ids = Vec :: new ( ) ;
1757+ for _ in 0 ..num_mpp_parts {
1758+ let _ = create_announced_chan_between_nodes_with_value ( & nodes, 0 , 1 , 10_000 , 0 ) ;
1759+ let channel_id = create_unannounced_chan_between_nodes_with_value ( & nodes, 1 , 2 , 2_000_000 , 0 ) . 0 . channel_id ;
1760+ chan_ids. push ( channel_id) ;
1761+ }
1762+
1763+ // Send the initial payment.
1764+ let amt_msat = 900_000 ;
1765+ let skimmed_fee_msat = 20 ;
1766+ let mut route_hints = Vec :: new ( ) ;
1767+ for _ in 0 ..num_mpp_parts {
1768+ route_hints. push ( RouteHint ( vec ! [ RouteHintHop {
1769+ src_node_id: nodes[ 1 ] . node. get_our_node_id( ) ,
1770+ short_channel_id: nodes[ 1 ] . node. get_intercept_scid( ) ,
1771+ fees: RoutingFees {
1772+ base_msat: 1000 ,
1773+ proportional_millionths: 0 ,
1774+ } ,
1775+ cltv_expiry_delta: MIN_CLTV_EXPIRY_DELTA ,
1776+ htlc_minimum_msat: None ,
1777+ htlc_maximum_msat: Some ( amt_msat / num_mpp_parts as u64 + 5 ) ,
1778+ } ] ) ) ;
1779+ }
1780+ let payment_params = PaymentParameters :: from_node_id ( nodes[ 2 ] . node . get_our_node_id ( ) , TEST_FINAL_CLTV )
1781+ . with_route_hints ( route_hints) . unwrap ( )
1782+ . with_bolt11_features ( nodes[ 2 ] . node . invoice_features ( ) ) . unwrap ( ) ;
1783+ let route_params = RouteParameters {
1784+ payment_params,
1785+ final_value_msat : amt_msat,
1786+ } ;
1787+ let ( payment_hash, payment_secret) = nodes[ 2 ] . node . create_inbound_payment ( Some ( amt_msat) , 60 * 60 , None ) . unwrap ( ) ;
1788+ nodes[ 0 ] . node . send_payment ( payment_hash, RecipientOnionFields :: secret_only ( payment_secret) ,
1789+ PaymentId ( payment_hash. 0 ) , route_params, Retry :: Attempts ( 0 ) ) . unwrap ( ) ;
1790+ check_added_monitors ! ( nodes[ 0 ] , num_mpp_parts) ; // one monitor per path
1791+ let mut events: Vec < SendEvent > = nodes[ 0 ] . node . get_and_clear_pending_msg_events ( ) . into_iter ( ) . map ( |e| SendEvent :: from_event ( e) ) . collect ( ) ;
1792+ assert_eq ! ( events. len( ) , num_mpp_parts) ;
1793+
1794+ // Forward the intercepted payments.
1795+ for ( idx, ev) in events. into_iter ( ) . enumerate ( ) {
1796+ nodes[ 1 ] . node . handle_update_add_htlc ( & nodes[ 0 ] . node . get_our_node_id ( ) , & ev. msgs [ 0 ] ) ;
1797+ do_commitment_signed_dance ( & nodes[ 1 ] , & nodes[ 0 ] , & ev. commitment_msg , false , true ) ;
1798+
1799+ let events = nodes[ 1 ] . node . get_and_clear_pending_events ( ) ;
1800+ assert_eq ! ( events. len( ) , 1 ) ;
1801+ let ( intercept_id, expected_outbound_amt_msat) = match events[ 0 ] {
1802+ crate :: events:: Event :: HTLCIntercepted {
1803+ intercept_id, expected_outbound_amount_msat, payment_hash : pmt_hash, ..
1804+ } => {
1805+ assert_eq ! ( pmt_hash, payment_hash) ;
1806+ ( intercept_id, expected_outbound_amount_msat)
1807+ } ,
1808+ _ => panic ! ( )
1809+ } ;
1810+ nodes[ 1 ] . node . forward_intercepted_htlc ( intercept_id, & chan_ids[ idx] ,
1811+ nodes[ 2 ] . node . get_our_node_id ( ) , expected_outbound_amt_msat - skimmed_fee_msat) . unwrap ( ) ;
1812+ expect_pending_htlcs_forwardable ! ( nodes[ 1 ] ) ;
1813+ let payment_event = {
1814+ {
1815+ let mut added_monitors = nodes[ 1 ] . chain_monitor . added_monitors . lock ( ) . unwrap ( ) ;
1816+ assert_eq ! ( added_monitors. len( ) , 1 ) ;
1817+ added_monitors. clear ( ) ;
1818+ }
1819+ let mut events = nodes[ 1 ] . node . get_and_clear_pending_msg_events ( ) ;
1820+ assert_eq ! ( events. len( ) , 1 ) ;
1821+ SendEvent :: from_event ( events. remove ( 0 ) )
1822+ } ;
1823+ nodes[ 2 ] . node . handle_update_add_htlc ( & nodes[ 1 ] . node . get_our_node_id ( ) , & payment_event. msgs [ 0 ] ) ;
1824+ do_commitment_signed_dance ( & nodes[ 2 ] , & nodes[ 1 ] , & payment_event. commitment_msg , false , true ) ;
1825+ if idx == num_mpp_parts - 1 {
1826+ expect_pending_htlcs_forwardable ! ( nodes[ 2 ] ) ;
1827+ }
1828+ }
1829+
1830+ // Claim the payment and check that the skimmed fee is as expected.
1831+ let payment_preimage = nodes[ 2 ] . node . get_payment_preimage ( payment_hash, payment_secret) . unwrap ( ) ;
1832+ let events = nodes[ 2 ] . node . get_and_clear_pending_events ( ) ;
1833+ assert_eq ! ( events. len( ) , 1 ) ;
1834+ match events[ 0 ] {
1835+ crate :: events:: Event :: PaymentClaimable {
1836+ ref payment_hash, ref purpose, amount_msat, counterparty_skimmed_fee_msat, receiver_node_id, ..
1837+ } => {
1838+ assert_eq ! ( payment_hash, payment_hash) ;
1839+ assert_eq ! ( amt_msat - skimmed_fee_msat * num_mpp_parts as u64 , amount_msat) ;
1840+ assert_eq ! ( skimmed_fee_msat * num_mpp_parts as u64 , counterparty_skimmed_fee_msat) ;
1841+ assert_eq ! ( nodes[ 2 ] . node. get_our_node_id( ) , receiver_node_id. unwrap( ) ) ;
1842+ match purpose {
1843+ crate :: events:: PaymentPurpose :: InvoicePayment { payment_preimage : ev_payment_preimage,
1844+ payment_secret : ev_payment_secret, .. } =>
1845+ {
1846+ assert_eq ! ( payment_preimage, ev_payment_preimage. unwrap( ) ) ;
1847+ assert_eq ! ( payment_secret, * ev_payment_secret) ;
1848+ } ,
1849+ _ => panic ! ( ) ,
1850+ }
1851+ } ,
1852+ _ => panic ! ( "Unexpected event" ) ,
1853+ }
1854+ let mut expected_paths_vecs = Vec :: new ( ) ;
1855+ let mut expected_paths = Vec :: new ( ) ;
1856+ for _ in 0 ..num_mpp_parts { expected_paths_vecs. push ( vec ! ( & nodes[ 1 ] , & nodes[ 2 ] ) ) ; }
1857+ for i in 0 ..num_mpp_parts { expected_paths. push ( & expected_paths_vecs[ i] [ ..] ) ; }
1858+ let total_fee_msat = do_claim_payment_along_route_with_extra_penultimate_hop_fees (
1859+ & nodes[ 0 ] , & expected_paths[ ..] , & vec ! [ skimmed_fee_msat as u32 ; num_mpp_parts] [ ..] , false ,
1860+ payment_preimage) ;
1861+ // The sender doesn't know that the penultimate hop took an extra fee.
1862+ expect_payment_sent ( & nodes[ 0 ] , payment_preimage,
1863+ Some ( Some ( total_fee_msat - skimmed_fee_msat * num_mpp_parts as u64 ) ) , true ) ;
1864+ }
1865+
17391866#[ derive( PartialEq ) ]
17401867enum AutoRetry {
17411868 Success ,
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