Add a debug_assert the newly-documented (but existing) requirement

If we add an entry to `claimable_payments` we have to ensure we
actually accept the HTLC we're considering, otherwise we'll end up
with an empty `claimable_payments` entry.

diff --git a/lightning/src/ln/channelmanager.rs b/lightning/src/ln/channelmanager.rs
index d51209d7e0ec5c88d7bbac48e52b9f81cdab5640..845a922ee562f3a52a4b80c99ea635e784998074 100644 (file)
--- a/lightning/src/ln/channelmanager.rs
+++ b/lightning/src/ln/channelmanager.rs
@@ -3315,8 +3315,11 @@ where
                                                                        onion_payload,
                                                                };
 
+                                                               let mut committed_to_claimable = false;
+
                                                                macro_rules! fail_htlc {
                                                                        ($htlc: expr, $payment_hash: expr) => {
+                                                                               debug_assert!(!committed_to_claimable);
                                                                                let mut htlc_msat_height_data = $htlc.value.to_be_bytes().to_vec();
                                                                                htlc_msat_height_data.extend_from_slice(
                                                                                        &self.best_block.read().unwrap().height().to_be_bytes(),
@@ -3357,8 +3360,11 @@ where
                                                                                let ref mut claimable_payment = claimable_payments.claimable_payments
                                                                                        .entry(payment_hash)
                                                                                        // Note that if we insert here we MUST NOT fail_htlc!()
-                                                                                       .or_insert_with(|| ClaimablePayment {
-                                                                                               purpose: purpose(), htlcs: Vec::new()
+                                                                                       .or_insert_with(|| {
+                                                                                               committed_to_claimable = true;
+                                                                                               ClaimablePayment {
+                                                                                                       purpose: purpose(), htlcs: Vec::new()
+                                                                                               }
                                                                                        });
                                                                                let ref mut htlcs = &mut claimable_payment.htlcs;
                                                                                if htlcs.len() == 1 {
@@ -3394,6 +3400,9 @@ where
                                                                                                log_bytes!(payment_hash.0));
                                                                                        fail_htlc!(claimable_htlc, payment_hash);
                                                                                } else if total_value >= $payment_data.total_msat {
+                                                                                       #[allow(unused_assignments)] {
+                                                                                               committed_to_claimable = true;
+                                                                                       }
                                                                                        let prev_channel_id = prev_funding_outpoint.to_channel_id();
                                                                                        htlcs.push(claimable_htlc);
                                                                                        let amount_msat = htlcs.iter().map(|htlc| htlc.value).sum();
@@ -3413,6 +3422,9 @@ where
                                                                                        // payment value yet, wait until we receive more
                                                                                        // MPP parts.
                                                                                        htlcs.push(claimable_htlc);
+                                                                                       #[allow(unused_assignments)] {
+                                                                                               committed_to_claimable = true;
+                                                                                       }
                                                                                }
                                                                                payment_claimable_generated
                                                                        }}