Assert that our weight prediction can't result in unspendable txn

diff --git a/src/ln/channelmonitor.rs b/src/ln/channelmonitor.rs
index c279c2c4071dddddd06612f3962b330857c0f858..1888117e849585fb20e7cf307b51171de0a3e246 100644 (file)
--- a/src/ln/channelmonitor.rs
+++ b/src/ln/channelmonitor.rs
@@ -1209,9 +1209,11 @@ impl ChannelMonitor {
                                                                        value: htlc.amount_msat / 1000, //TODO: - fee
                                                                }),
                                                        };
-                                                       single_htlc_tx.output[0].value -= fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::HighPriority) * (single_htlc_tx.get_weight() + Self::get_witnesses_weight(&vec![if htlc.offered { InputDescriptors::RevokedOfferedHTLC } else { InputDescriptors::RevokedReceivedHTLC }])) / 1000;
+                                                       let predicted_weight = single_htlc_tx.get_weight() + Self::get_witnesses_weight(&vec![if htlc.offered { InputDescriptors::RevokedOfferedHTLC } else { InputDescriptors::RevokedReceivedHTLC }]);
+                                                       single_htlc_tx.output[0].value -= fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::HighPriority) * predicted_weight / 1000;
                                                        let sighash_parts = bip143::SighashComponents::new(&single_htlc_tx);
                                                        sign_input!(sighash_parts, single_htlc_tx.input[0], Some(idx), htlc.amount_msat / 1000);
+                                                       assert!(predicted_weight >= single_htlc_tx.get_weight());
                                                        txn_to_broadcast.push(single_htlc_tx);
                                                }
                                        }
@@ -1261,7 +1263,8 @@ impl ChannelMonitor {
                                input: inputs,
                                output: outputs,
                        };
-                       spend_tx.output[0].value -= fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::HighPriority) * (spend_tx.get_weight() + Self::get_witnesses_weight(&input_descriptors)) / 1000;
+                       let predicted_weight = spend_tx.get_weight() + Self::get_witnesses_weight(&input_descriptors);
+                       spend_tx.output[0].value -= fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::HighPriority) * predicted_weight / 1000;
 
                        let mut values_drain = values.drain(..);
                        let sighash_parts = bip143::SighashComponents::new(&spend_tx);
@@ -1270,6 +1273,7 @@ impl ChannelMonitor {
                                let value = values_drain.next().unwrap();
                                sign_input!(sighash_parts, input, htlc_idx, value);
                        }
+                       assert!(predicted_weight >= spend_tx.get_weight());
 
                        spendable_outputs.push(SpendableOutputDescriptor::StaticOutput {
                                outpoint: BitcoinOutPoint { txid: spend_tx.txid(), vout: 0 },
@@ -1428,9 +1432,11 @@ impl ChannelMonitor {
                                                                                        value: htlc.amount_msat / 1000,
                                                                                }),
                                                                        };
-                                                                       single_htlc_tx.output[0].value -= fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::HighPriority) * (single_htlc_tx.get_weight() + Self::get_witnesses_weight(&vec![if htlc.offered { InputDescriptors::OfferedHTLC } else { InputDescriptors::ReceivedHTLC }])) / 1000;
+                                                                       let predicted_weight = single_htlc_tx.get_weight() + Self::get_witnesses_weight(&vec![if htlc.offered { InputDescriptors::OfferedHTLC } else { InputDescriptors::ReceivedHTLC }]);
+                                                                       single_htlc_tx.output[0].value -= fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::HighPriority) * predicted_weight / 1000;
                                                                        let sighash_parts = bip143::SighashComponents::new(&single_htlc_tx);
                                                                        sign_input!(sighash_parts, single_htlc_tx.input[0], htlc.amount_msat / 1000, payment_preimage.0.to_vec());
+                                                                       assert!(predicted_weight >= single_htlc_tx.get_weight());
                                                                        spendable_outputs.push(SpendableOutputDescriptor::StaticOutput {
                                                                                outpoint: BitcoinOutPoint { txid: single_htlc_tx.txid(), vout: 0 },
                                                                                output: single_htlc_tx.output[0].clone(),
@@ -1478,7 +1484,8 @@ impl ChannelMonitor {
                                                input: inputs,
                                                output: outputs,
                                        };
-                                       spend_tx.output[0].value -= fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::HighPriority) * (spend_tx.get_weight() + Self::get_witnesses_weight(&input_descriptors)) / 1000;
+                                       let predicted_weight = spend_tx.get_weight() + Self::get_witnesses_weight(&input_descriptors);
+                                       spend_tx.output[0].value -= fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::HighPriority) * predicted_weight / 1000;
 
                                        let mut values_drain = values.drain(..);
                                        let sighash_parts = bip143::SighashComponents::new(&spend_tx);
@@ -1488,6 +1495,7 @@ impl ChannelMonitor {
                                                sign_input!(sighash_parts, input, value.0, (value.1).0.to_vec());
                                        }
 
+                                       assert!(predicted_weight >= spend_tx.get_weight());
                                        spendable_outputs.push(SpendableOutputDescriptor::StaticOutput {
                                                outpoint: BitcoinOutPoint { txid: spend_tx.txid(), vout: 0 },
                                                output: spend_tx.output[0].clone(),
@@ -1562,7 +1570,8 @@ impl ChannelMonitor {
                                input: inputs,
                                output: outputs,
                        };
-                       spend_tx.output[0].value -= fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::HighPriority) * (spend_tx.get_weight() + Self::get_witnesses_weight(&vec![InputDescriptors::RevokedOutput])) / 1000;
+                       let predicted_weight = spend_tx.get_weight() + Self::get_witnesses_weight(&vec![InputDescriptors::RevokedOutput]);
+                       spend_tx.output[0].value -= fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::HighPriority) * predicted_weight / 1000;
 
                        let sighash_parts = bip143::SighashComponents::new(&spend_tx);
 
@@ -1581,6 +1590,7 @@ impl ChannelMonitor {
                        spend_tx.input[0].witness.push(vec!(1));
                        spend_tx.input[0].witness.push(redeemscript.into_bytes());
 
+                       assert!(predicted_weight >= spend_tx.get_weight());
                        let outpoint = BitcoinOutPoint { txid: spend_tx.txid(), vout: 0 };
                        let output = spend_tx.output[0].clone();
                        (Some(spend_tx), Some(SpendableOutputDescriptor::StaticOutput { outpoint, output }))