Allow receiving less than the onion claims to pay

[rust-lightning] / lightning / src / ln / channelmanager.rs

diff --git a/lightning/src/ln/channelmanager.rs b/lightning/src/ln/channelmanager.rs
index 808c7ffcd3ac2196e5961f406f13d5f347fee0c5..5ebaa531ce2a37333cb9fe53ff1ac5673cdbc151 100644 (file)
--- a/lightning/src/ln/channelmanager.rs
+++ b/lightning/src/ln/channelmanager.rs
@@ -2526,9 +2526,10 @@ where
                }
        }
 
-       fn construct_recv_pending_htlc_info(&self, hop_data: msgs::OnionHopData, shared_secret: [u8; 32],
-               payment_hash: PaymentHash, amt_msat: u64, cltv_expiry: u32, phantom_shared_secret: Option<[u8; 32]>) -> Result<PendingHTLCInfo, ReceiveError>
-       {
+       fn construct_recv_pending_htlc_info(
+               &self, hop_data: msgs::OnionHopData, shared_secret: [u8; 32], payment_hash: PaymentHash,
+               amt_msat: u64, cltv_expiry: u32, phantom_shared_secret: Option<[u8; 32]>, allow_underpay: bool
+       ) -> Result<PendingHTLCInfo, ReceiveError> {
                // final_incorrect_cltv_expiry
                if hop_data.outgoing_cltv_value > cltv_expiry {
                        return Err(ReceiveError {
@@ -2554,7 +2555,7 @@ where
                                msg: "The final CLTV expiry is too soon to handle",
                        });
                }
-               if hop_data.amt_to_forward > amt_msat {
+               if !allow_underpay && hop_data.amt_to_forward > amt_msat {
                        return Err(ReceiveError {
                                err_code: 19,
                                err_data: amt_msat.to_be_bytes().to_vec(),
@@ -2841,7 +2842,7 @@ where
 
        fn construct_pending_htlc_status<'a>(
                &self, msg: &msgs::UpdateAddHTLC, shared_secret: [u8; 32], decoded_hop: onion_utils::Hop,
-               next_packet_pubkey_opt: Option<Result<PublicKey, secp256k1::Error>>
+               allow_underpay: bool, next_packet_pubkey_opt: Option<Result<PublicKey, secp256k1::Error>>
        ) -> PendingHTLCStatus {
                macro_rules! return_err {
                        ($msg: expr, $err_code: expr, $data: expr) => {
@@ -2859,7 +2860,9 @@ where
                match decoded_hop {
                        onion_utils::Hop::Receive(next_hop_data) => {
                                // OUR PAYMENT!
-                               match self.construct_recv_pending_htlc_info(next_hop_data, shared_secret, msg.payment_hash, msg.amount_msat, msg.cltv_expiry, None) {
+                               match self.construct_recv_pending_htlc_info(next_hop_data, shared_secret, msg.payment_hash,
+                                       msg.amount_msat, msg.cltv_expiry, None, allow_underpay)
+                               {
                                        Ok(info) => {
                                                // Note that we could obviously respond immediately with an update_fulfill_htlc
                                                // message, however that would leak that we are the recipient of this payment, so
@@ -3675,7 +3678,10 @@ where
                                                                                                };
                                                                                                match next_hop {
                                                                                                        onion_utils::Hop::Receive(hop_data) => {
-                                                                                                               match self.construct_recv_pending_htlc_info(hop_data, incoming_shared_secret, payment_hash, outgoing_amt_msat, outgoing_cltv_value, Some(phantom_shared_secret)) {
+                                                                                                               match self.construct_recv_pending_htlc_info(hop_data,
+                                                                                                                       incoming_shared_secret, payment_hash, outgoing_amt_msat,
+                                                                                                                       outgoing_cltv_value, Some(phantom_shared_secret), false)
+                                                                                                               {
                                                                                                                        Ok(info) => phantom_receives.push((prev_short_channel_id, prev_funding_outpoint, prev_user_channel_id, vec![(info, prev_htlc_id)])),
                                                                                                                        Err(ReceiveError { err_code, err_data, msg }) => failed_payment!(msg, err_code, err_data, Some(phantom_shared_secret))
                                                                                                                }
@@ -3923,11 +3929,14 @@ where
                                                                                        htlcs.push(claimable_htlc);
                                                                                        let amount_msat = htlcs.iter().map(|htlc| htlc.value).sum();
                                                                                        htlcs.iter_mut().for_each(|htlc| htlc.total_value_received = Some(amount_msat));
+                                                                                       let counterparty_skimmed_fee_msat = htlcs.iter()
+                                                                                               .map(|htlc| htlc.counterparty_skimmed_fee_msat.unwrap_or(0)).sum();
                                                                                        new_events.push_back((events::Event::PaymentClaimable {
                                                                                                receiver_node_id: Some(receiver_node_id),
                                                                                                payment_hash,
                                                                                                purpose: $purpose,
                                                                                                amount_msat,
+                                                                                               counterparty_skimmed_fee_msat,
                                                                                                via_channel_id: Some(prev_channel_id),
                                                                                                via_user_channel_id: Some(prev_user_channel_id),
                                                                                                claim_deadline: Some(earliest_expiry - HTLC_FAIL_BACK_BUFFER),
@@ -5421,7 +5430,8 @@ where
 
                                let pending_forward_info = match decoded_hop_res {
                                        Ok((next_hop, shared_secret, next_packet_pk_opt)) =>
-                                               self.construct_pending_htlc_status(msg, shared_secret, next_hop, next_packet_pk_opt),
+                                               self.construct_pending_htlc_status(msg, shared_secret, next_hop,
+                                                       chan.get().context.config().accept_underpaying_htlcs, next_packet_pk_opt),
                                        Err(e) => PendingHTLCStatus::Fail(e)
                                };
                                let create_pending_htlc_status = |chan: &Channel<<SP::Target as SignerProvider>::Signer>, pending_forward_info: PendingHTLCStatus, error_code: u16| {