Merge pull request #770 from lightning-signer/holder-htlc-sigs
authorMatt Corallo <649246+TheBlueMatt@users.noreply.github.com>
Mon, 18 Jan 2021 18:49:45 +0000 (10:49 -0800)
committerGitHub <noreply@github.com>
Mon, 18 Jan 2021 18:49:45 +0000 (10:49 -0800)
Fold sign_holder_commitment_htlc_transactions into sign_holder_commitment

lightning/src/chain/channelmonitor.rs
lightning/src/chain/keysinterface.rs
lightning/src/ln/channel.rs
lightning/src/ln/onchaintx.rs
lightning/src/util/enforcing_trait_impls.rs

index b87e73d98bd77b85d8083ef633f8ced0f8380dbe..b46a2df13eea8d8c462e1df72dd6dca9fac2b45f 100644 (file)
@@ -969,7 +969,6 @@ impl<ChanSigner: ChannelKeys> ChannelMonitor<ChanSigner> {
 
                let key_derivation_params = keys.key_derivation_params();
                let holder_revocation_basepoint = keys.pubkeys().revocation_basepoint;
-               let mut onchain_tx_handler = OnchainTxHandler::new(destination_script.clone(), keys, channel_parameters.clone());
 
                let secp_ctx = Secp256k1::new();
 
@@ -991,7 +990,9 @@ impl<ChanSigner: ChannelKeys> ChannelMonitor<ChanSigner> {
                        };
                        (holder_commitment_tx, trusted_tx.commitment_number())
                };
-               onchain_tx_handler.provide_latest_holder_tx(initial_holder_commitment_tx);
+
+               let onchain_tx_handler =
+                       OnchainTxHandler::new(destination_script.clone(), keys, channel_parameters.clone(), initial_holder_commitment_tx);
 
                let mut outputs_to_watch = HashMap::new();
                outputs_to_watch.insert(funding_info.0.txid, vec![(funding_info.0.index as u32, funding_info.1.clone())]);
@@ -1725,28 +1726,26 @@ impl<ChanSigner: ChannelKeys> ChannelMonitor<ChanSigner> {
        pub fn get_latest_holder_commitment_txn<L: Deref>(&mut self, logger: &L) -> Vec<Transaction> where L::Target: Logger {
                log_trace!(logger, "Getting signed latest holder commitment transaction!");
                self.holder_tx_signed = true;
-               if let Some(commitment_tx) = self.onchain_tx_handler.get_fully_signed_holder_tx(&self.funding_redeemscript) {
-                       let txid = commitment_tx.txid();
-                       let mut res = vec![commitment_tx];
-                       for htlc in self.current_holder_commitment_tx.htlc_outputs.iter() {
-                               if let Some(vout) = htlc.0.transaction_output_index {
-                                       let preimage = if !htlc.0.offered {
-                                                       if let Some(preimage) = self.payment_preimages.get(&htlc.0.payment_hash) { Some(preimage.clone()) } else {
-                                                               // We can't build an HTLC-Success transaction without the preimage
-                                                               continue;
-                                                       }
-                                               } else { None };
-                                       if let Some(htlc_tx) = self.onchain_tx_handler.get_fully_signed_htlc_tx(
-                                                       &::bitcoin::OutPoint { txid, vout }, &preimage) {
-                                               res.push(htlc_tx);
+               let commitment_tx = self.onchain_tx_handler.get_fully_signed_holder_tx(&self.funding_redeemscript);
+               let txid = commitment_tx.txid();
+               let mut res = vec![commitment_tx];
+               for htlc in self.current_holder_commitment_tx.htlc_outputs.iter() {
+                       if let Some(vout) = htlc.0.transaction_output_index {
+                               let preimage = if !htlc.0.offered {
+                                       if let Some(preimage) = self.payment_preimages.get(&htlc.0.payment_hash) { Some(preimage.clone()) } else {
+                                               // We can't build an HTLC-Success transaction without the preimage
+                                               continue;
                                        }
+                               } else { None };
+                               if let Some(htlc_tx) = self.onchain_tx_handler.get_fully_signed_htlc_tx(
+                                       &::bitcoin::OutPoint { txid, vout }, &preimage) {
+                                       res.push(htlc_tx);
                                }
                        }
-                       // We throw away the generated waiting_first_conf data as we aren't (yet) confirmed and we don't actually know what the caller wants to do.
-                       // The data will be re-generated and tracked in check_spend_holder_transaction if we get a confirmation.
-                       return res
                }
-               Vec::new()
+               // We throw away the generated waiting_first_conf data as we aren't (yet) confirmed and we don't actually know what the caller wants to do.
+               // The data will be re-generated and tracked in check_spend_holder_transaction if we get a confirmation.
+               return res;
        }
 
        /// Unsafe test-only version of get_latest_holder_commitment_txn used by our test framework
@@ -1755,26 +1754,24 @@ impl<ChanSigner: ChannelKeys> ChannelMonitor<ChanSigner> {
        #[cfg(any(test,feature = "unsafe_revoked_tx_signing"))]
        pub fn unsafe_get_latest_holder_commitment_txn<L: Deref>(&mut self, logger: &L) -> Vec<Transaction> where L::Target: Logger {
                log_trace!(logger, "Getting signed copy of latest holder commitment transaction!");
-               if let Some(commitment_tx) = self.onchain_tx_handler.get_fully_signed_copy_holder_tx(&self.funding_redeemscript) {
-                       let txid = commitment_tx.txid();
-                       let mut res = vec![commitment_tx];
-                       for htlc in self.current_holder_commitment_tx.htlc_outputs.iter() {
-                               if let Some(vout) = htlc.0.transaction_output_index {
-                                       let preimage = if !htlc.0.offered {
-                                                       if let Some(preimage) = self.payment_preimages.get(&htlc.0.payment_hash) { Some(preimage.clone()) } else {
-                                                               // We can't build an HTLC-Success transaction without the preimage
-                                                               continue;
-                                                       }
-                                               } else { None };
-                                       if let Some(htlc_tx) = self.onchain_tx_handler.unsafe_get_fully_signed_htlc_tx(
-                                                       &::bitcoin::OutPoint { txid, vout }, &preimage) {
-                                               res.push(htlc_tx);
+               let commitment_tx = self.onchain_tx_handler.get_fully_signed_copy_holder_tx(&self.funding_redeemscript);
+               let txid = commitment_tx.txid();
+               let mut res = vec![commitment_tx];
+               for htlc in self.current_holder_commitment_tx.htlc_outputs.iter() {
+                       if let Some(vout) = htlc.0.transaction_output_index {
+                               let preimage = if !htlc.0.offered {
+                                       if let Some(preimage) = self.payment_preimages.get(&htlc.0.payment_hash) { Some(preimage.clone()) } else {
+                                               // We can't build an HTLC-Success transaction without the preimage
+                                               continue;
                                        }
+                               } else { None };
+                               if let Some(htlc_tx) = self.onchain_tx_handler.unsafe_get_fully_signed_htlc_tx(
+                                       &::bitcoin::OutPoint { txid, vout }, &preimage) {
+                                       res.push(htlc_tx);
                                }
                        }
-                       return res
                }
-               Vec::new()
+               return res
        }
 
        /// Processes transactions in a newly connected block, which may result in any of the following:
@@ -1853,15 +1850,14 @@ impl<ChanSigner: ChannelKeys> ChannelMonitor<ChanSigner> {
                }
                if should_broadcast {
                        self.pending_monitor_events.push(MonitorEvent::CommitmentTxBroadcasted(self.funding_info.0));
-                       if let Some(commitment_tx) = self.onchain_tx_handler.get_fully_signed_holder_tx(&self.funding_redeemscript) {
-                               self.holder_tx_signed = true;
-                               let (mut new_outpoints, _) = self.get_broadcasted_holder_claims(&self.current_holder_commitment_tx);
-                               let new_outputs = self.get_broadcasted_holder_watch_outputs(&self.current_holder_commitment_tx, &commitment_tx);
-                               if !new_outputs.is_empty() {
-                                       watch_outputs.push((self.current_holder_commitment_tx.txid.clone(), new_outputs));
-                               }
-                               claimable_outpoints.append(&mut new_outpoints);
-                       }
+                       let commitment_tx = self.onchain_tx_handler.get_fully_signed_holder_tx(&self.funding_redeemscript);
+                       self.holder_tx_signed = true;
+                       let (mut new_outpoints, _) = self.get_broadcasted_holder_claims(&self.current_holder_commitment_tx);
+                       let new_outputs = self.get_broadcasted_holder_watch_outputs(&self.current_holder_commitment_tx, &commitment_tx);
+                       if !new_outputs.is_empty() {
+                               watch_outputs.push((self.current_holder_commitment_tx.txid.clone(), new_outputs));
+                       }
+                       claimable_outpoints.append(&mut new_outpoints);
                }
                if let Some(events) = self.onchain_events_waiting_threshold_conf.remove(&height) {
                        for ev in events {
index 4a3a937a5c4586824ce0b875525b737ca39bdd67..80f734edbde3e0def17dcd23ceb903d564d969e2 100644 (file)
@@ -233,13 +233,21 @@ pub trait ChannelKeys : Send+Clone + Writeable {
        // TODO: Document the things someone using this interface should enforce before signing.
        fn sign_counterparty_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &CommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<(Signature, Vec<Signature>), ()>;
 
-       /// Create a signature for a holder's commitment transaction. This will only ever be called with
-       /// the same commitment_tx (or a copy thereof), though there are currently no guarantees
-       /// that it will not be called multiple times.
+       /// Create a signatures for a holder's commitment transaction and its claiming HTLC transactions.
+       /// This will only ever be called with a non-revoked commitment_tx.  This will be called with the
+       /// latest commitment_tx when we initiate a force-close.
+       /// This will be called with the previous latest, just to get claiming HTLC signatures, if we are
+       /// reacting to a ChannelMonitor replica that decided to broadcast before it had been updated to
+       /// the latest.
+       /// This may be called multiple times for the same transaction.
+       ///
        /// An external signer implementation should check that the commitment has not been revoked.
+       ///
+       /// May return Err if key derivation fails.  Callers, such as ChannelMonitor, will panic in such a case.
        //
        // TODO: Document the things someone using this interface should enforce before signing.
-       fn sign_holder_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
+       // TODO: Key derivation failure should panic rather than Err
+       fn sign_holder_commitment_and_htlcs<T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<(Signature, Vec<Signature>), ()>;
 
        /// Same as sign_holder_commitment, but exists only for tests to get access to holder commitment
        /// transactions which will be broadcasted later, after the channel has moved on to a newer
@@ -248,18 +256,6 @@ pub trait ChannelKeys : Send+Clone + Writeable {
        #[cfg(any(test,feature = "unsafe_revoked_tx_signing"))]
        fn unsafe_sign_holder_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()>;
 
-       /// Create a signature for each HTLC transaction spending a holder's commitment transaction.
-       ///
-       /// Unlike sign_holder_commitment, this may be called multiple times with *different*
-       /// commitment_tx values. While this will never be called with a revoked
-       /// commitment_tx, it is possible that it is called with the second-latest
-       /// commitment_tx (only if we haven't yet revoked it) if some watchtower/secondary
-       /// ChannelMonitor decided to broadcast before it had been updated to the latest.
-       ///
-       /// Either an Err should be returned, or a Vec with one entry for each HTLC which exists in
-       /// commitment_tx.
-       fn sign_holder_commitment_htlc_transactions<T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Vec<Signature>, ()>;
-
        /// Create a signature for the given input in a transaction spending an HTLC or commitment
        /// transaction output when our counterparty broadcasts an old state.
        ///
@@ -500,11 +496,14 @@ impl ChannelKeys for InMemoryChannelKeys {
                Ok((commitment_sig, htlc_sigs))
        }
 
-       fn sign_holder_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
+       fn sign_holder_commitment_and_htlcs<T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<(Signature, Vec<Signature>), ()> {
                let funding_pubkey = PublicKey::from_secret_key(secp_ctx, &self.funding_key);
                let funding_redeemscript = make_funding_redeemscript(&funding_pubkey, &self.counterparty_pubkeys().funding_pubkey);
                let sig = commitment_tx.trust().built_transaction().sign(&self.funding_key, &funding_redeemscript, self.channel_value_satoshis, secp_ctx);
-               Ok(sig)
+               let channel_parameters = self.get_channel_parameters();
+               let trusted_tx = commitment_tx.trust();
+               let htlc_sigs = trusted_tx.get_htlc_sigs(&self.htlc_base_key, &channel_parameters.as_holder_broadcastable(), secp_ctx)?;
+               Ok((sig, htlc_sigs))
        }
 
        #[cfg(any(test,feature = "unsafe_revoked_tx_signing"))]
@@ -514,12 +513,6 @@ impl ChannelKeys for InMemoryChannelKeys {
                Ok(commitment_tx.trust().built_transaction().sign(&self.funding_key, &channel_funding_redeemscript, self.channel_value_satoshis, secp_ctx))
        }
 
-       fn sign_holder_commitment_htlc_transactions<T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Vec<Signature>, ()> {
-               let channel_parameters = self.get_channel_parameters();
-               let trusted_tx = commitment_tx.trust();
-               trusted_tx.get_htlc_sigs(&self.htlc_base_key, &channel_parameters.as_holder_broadcastable(), secp_ctx)
-       }
-
        fn sign_justice_transaction<T: secp256k1::Signing + secp256k1::Verification>(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, htlc: &Option<HTLCOutputInCommitment>, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
                let revocation_key = match chan_utils::derive_private_revocation_key(&secp_ctx, &per_commitment_key, &self.revocation_base_key) {
                        Ok(revocation_key) => revocation_key,
index 4ba8b28bfd5780a49ec0e9260ee4f4da0b81b990..08faea160bb193a0d652a03211d4d2039942f500 100644 (file)
@@ -4742,15 +4742,13 @@ mod tests {
                                        &chan.holder_keys.pubkeys().funding_pubkey,
                                        chan.counterparty_funding_pubkey()
                                );
-                               let holder_sig = chan_keys.sign_holder_commitment(&holder_commitment_tx, &secp_ctx).unwrap();
+                               let (holder_sig, htlc_sigs) = chan_keys.sign_holder_commitment_and_htlcs(&holder_commitment_tx, &secp_ctx).unwrap();
                                assert_eq!(Signature::from_der(&hex::decode($sig_hex).unwrap()[..]).unwrap(), holder_sig, "holder_sig");
 
                                let funding_redeemscript = chan.get_funding_redeemscript();
                                let tx = holder_commitment_tx.add_holder_sig(&funding_redeemscript, holder_sig);
                                assert_eq!(serialize(&tx)[..], hex::decode($tx_hex).unwrap()[..], "tx");
 
-                               let htlc_sigs = chan_keys.sign_holder_commitment_htlc_transactions(&holder_commitment_tx, &secp_ctx).unwrap();
-
                                // ((htlc, counterparty_sig), (index, holder_sig))
                                let mut htlc_sig_iter = holder_commitment_tx.htlcs().iter().zip(&holder_commitment_tx.counterparty_htlc_sigs).zip(htlc_sigs.iter().enumerate());
 
index 1b0060dabc7c59af2eab7e6d01cfbf42085dd102..02776fdefe5044e9f450b3dce40f269d43b14a68 100644 (file)
@@ -35,6 +35,7 @@ use util::byte_utils;
 use std::collections::{HashMap, hash_map};
 use std::cmp;
 use std::ops::Deref;
+use std::mem::replace;
 
 const MAX_ALLOC_SIZE: usize = 64*1024;
 
@@ -241,7 +242,7 @@ impl Writeable for Option<Vec<Option<(usize, Signature)>>> {
 /// do RBF bumping if possible.
 pub struct OnchainTxHandler<ChanSigner: ChannelKeys> {
        destination_script: Script,
-       holder_commitment: Option<HolderCommitmentTransaction>,
+       holder_commitment: HolderCommitmentTransaction,
        // holder_htlc_sigs and prev_holder_htlc_sigs are in the order as they appear in the commitment
        // transaction outputs (hence the Option<>s inside the Vec). The first usize is the index in
        // the set of HTLCs in the HolderCommitmentTransaction.
@@ -423,13 +424,13 @@ impl<'a, K: KeysInterface> ReadableArgs<&'a K> for OnchainTxHandler<K::ChanKeySi
 }
 
 impl<ChanSigner: ChannelKeys> OnchainTxHandler<ChanSigner> {
-       pub(crate) fn new(destination_script: Script, keys: ChanSigner, channel_parameters: ChannelTransactionParameters) -> Self {
+       pub(crate) fn new(destination_script: Script, keys: ChanSigner, channel_parameters: ChannelTransactionParameters, holder_commitment: HolderCommitmentTransaction) -> Self {
 
                let key_storage = keys;
 
                OnchainTxHandler {
                        destination_script,
-                       holder_commitment: None,
+                       holder_commitment,
                        holder_htlc_sigs: None,
                        prev_holder_commitment: None,
                        prev_holder_htlc_sigs: None,
@@ -490,6 +491,8 @@ impl<ChanSigner: ChannelKeys> OnchainTxHandler<ChanSigner> {
 
        /// Lightning security model (i.e being able to redeem/timeout HTLC or penalize coutnerparty onchain) lays on the assumption of claim transactions getting confirmed before timelock expiration
        /// (CSV or CLTV following cases). In case of high-fee spikes, claim tx may stuck in the mempool, so you need to bump its feerate quickly using Replace-By-Fee or Child-Pay-For-Parent.
+       /// Panics if there are signing errors, because signing operations in reaction to on-chain events
+       /// are not expected to fail, and if they do, we may lose funds.
        fn generate_claim_tx<F: Deref, L: Deref>(&mut self, height: u32, cached_claim_datas: &ClaimTxBumpMaterial, fee_estimator: &F, logger: &L) -> Option<(Option<u32>, u32, Transaction)>
                where F::Target: FeeEstimator,
                                        L::Target: Logger,
@@ -610,17 +613,15 @@ impl<ChanSigner: ChannelKeys> OnchainTxHandler<ChanSigner> {
                                                                chan_utils::get_revokeable_redeemscript(&chan_keys.revocation_key, *on_counterparty_tx_csv, &chan_keys.broadcaster_delayed_payment_key)
                                                        };
 
-                                                       if let Ok(sig) = self.key_storage.sign_justice_transaction(&bumped_tx, i, *amount, &per_commitment_key, htlc, &self.secp_ctx) {
-                                                               bumped_tx.input[i].witness.push(sig.serialize_der().to_vec());
-                                                               bumped_tx.input[i].witness[0].push(SigHashType::All as u8);
-                                                               if htlc.is_some() {
-                                                                       bumped_tx.input[i].witness.push(chan_keys.revocation_key.clone().serialize().to_vec());
-                                                               } else {
-                                                                       bumped_tx.input[i].witness.push(vec!(1));
-                                                               }
-                                                               bumped_tx.input[i].witness.push(witness_script.clone().into_bytes());
-                                                       } else { return None; }
-                                                       //TODO: panic ?
+                                                       let sig = self.key_storage.sign_justice_transaction(&bumped_tx, i, *amount, &per_commitment_key, htlc, &self.secp_ctx).expect("sign justice tx");
+                                                       bumped_tx.input[i].witness.push(sig.serialize_der().to_vec());
+                                                       bumped_tx.input[i].witness[0].push(SigHashType::All as u8);
+                                                       if htlc.is_some() {
+                                                               bumped_tx.input[i].witness.push(chan_keys.revocation_key.clone().serialize().to_vec());
+                                                       } else {
+                                                               bumped_tx.input[i].witness.push(vec!(1));
+                                                       }
+                                                       bumped_tx.input[i].witness.push(witness_script.clone().into_bytes());
 
                                                        log_trace!(logger, "Going to broadcast Penalty Transaction {} claiming revoked {} output {} from {} with new feerate {}...", bumped_tx.txid(), if *input_descriptor == InputDescriptors::RevokedOutput { "to_holder" } else if *input_descriptor == InputDescriptors::RevokedOfferedHTLC { "offered" } else if *input_descriptor == InputDescriptors::RevokedReceivedHTLC { "received" } else { "" }, outp.vout, outp.txid, new_feerate);
                                                }
@@ -630,17 +631,16 @@ impl<ChanSigner: ChannelKeys> OnchainTxHandler<ChanSigner> {
                                                        let witness_script = chan_utils::get_htlc_redeemscript_with_explicit_keys(&htlc, &chan_keys.broadcaster_htlc_key, &chan_keys.countersignatory_htlc_key, &chan_keys.revocation_key);
 
                                                        if !preimage.is_some() { bumped_tx.lock_time = htlc.cltv_expiry }; // Right now we don't aggregate time-locked transaction, if we do we should set lock_time before to avoid breaking hash computation
-                                                       if let Ok(sig) = self.key_storage.sign_counterparty_htlc_transaction(&bumped_tx, i, &htlc.amount_msat / 1000, &per_commitment_point, htlc, &self.secp_ctx) {
-                                                               bumped_tx.input[i].witness.push(sig.serialize_der().to_vec());
-                                                               bumped_tx.input[i].witness[0].push(SigHashType::All as u8);
-                                                               if let &Some(preimage) = preimage {
-                                                                       bumped_tx.input[i].witness.push(preimage.0.to_vec());
-                                                               } else {
-                                                                       // Due to BIP146 (MINIMALIF) this must be a zero-length element to relay.
-                                                                       bumped_tx.input[i].witness.push(vec![]);
-                                                               }
-                                                               bumped_tx.input[i].witness.push(witness_script.clone().into_bytes());
+                                                       let sig = self.key_storage.sign_counterparty_htlc_transaction(&bumped_tx, i, &htlc.amount_msat / 1000, &per_commitment_point, htlc, &self.secp_ctx).expect("sign counterparty HTLC tx");
+                                                       bumped_tx.input[i].witness.push(sig.serialize_der().to_vec());
+                                                       bumped_tx.input[i].witness[0].push(SigHashType::All as u8);
+                                                       if let &Some(preimage) = preimage {
+                                                               bumped_tx.input[i].witness.push(preimage.0.to_vec());
+                                                       } else {
+                                                               // Due to BIP146 (MINIMALIF) this must be a zero-length element to relay.
+                                                               bumped_tx.input[i].witness.push(vec![]);
                                                        }
+                                                       bumped_tx.input[i].witness.push(witness_script.clone().into_bytes());
                                                        log_trace!(logger, "Going to broadcast Claim Transaction {} claiming counterparty {} htlc output {} from {} with new feerate {}...", bumped_tx.txid(), if preimage.is_some() { "offered" } else { "received" }, outp.vout, outp.txid, new_feerate);
                                                }
                                        },
@@ -664,10 +664,10 @@ impl<ChanSigner: ChannelKeys> OnchainTxHandler<ChanSigner> {
                                                return None;
                                        },
                                        &InputMaterial::Funding { ref funding_redeemscript } => {
-                                               let signed_tx = self.get_fully_signed_holder_tx(funding_redeemscript).unwrap();
+                                               let signed_tx = self.get_fully_signed_holder_tx(funding_redeemscript);
                                                // Timer set to $NEVER given we can't bump tx without anchor outputs
                                                log_trace!(logger, "Going to broadcast Holder Transaction {} claiming funding output {} from {}...", signed_tx.txid(), outp.vout, outp.txid);
-                                               return Some((None, self.holder_commitment.as_ref().unwrap().feerate_per_kw(), signed_tx));
+                                               return Some((None, self.holder_commitment.feerate_per_kw(), signed_tx));
                                        }
                                        _ => unreachable!()
                                }
@@ -905,21 +905,27 @@ impl<ChanSigner: ChannelKeys> OnchainTxHandler<ChanSigner> {
        }
 
        pub(crate) fn provide_latest_holder_tx(&mut self, tx: HolderCommitmentTransaction) {
-               self.prev_holder_commitment = self.holder_commitment.take();
-               self.holder_commitment = Some(tx);
+               self.prev_holder_commitment = Some(replace(&mut self.holder_commitment, tx));
+               self.holder_htlc_sigs = None;
        }
 
+       // Normally holder HTLCs are signed at the same time as the holder commitment tx.  However,
+       // in some configurations, the holder commitment tx has been signed and broadcast by a
+       // ChannelMonitor replica, so we handle that case here.
        fn sign_latest_holder_htlcs(&mut self) {
-               if let Some(ref holder_commitment) = self.holder_commitment {
-                       if let Ok(sigs) = self.key_storage.sign_holder_commitment_htlc_transactions(holder_commitment, &self.secp_ctx) {
-                               self.holder_htlc_sigs = Some(Self::extract_holder_sigs(holder_commitment, sigs));
-                       }
+               if self.holder_htlc_sigs.is_none() {
+                       let (_sig, sigs) = self.key_storage.sign_holder_commitment_and_htlcs(&self.holder_commitment, &self.secp_ctx).expect("sign holder commitment");
+                       self.holder_htlc_sigs = Some(Self::extract_holder_sigs(&self.holder_commitment, sigs));
                }
        }
 
+       // Normally only the latest commitment tx and HTLCs need to be signed.  However, in some
+       // configurations we may have updated our holder commitment but a replica of the ChannelMonitor
+       // broadcast the previous one before we sync with it.  We handle that case here.
        fn sign_prev_holder_htlcs(&mut self) {
-               if let Some(ref holder_commitment) = self.prev_holder_commitment {
-                       if let Ok(sigs) = self.key_storage.sign_holder_commitment_htlc_transactions(holder_commitment, &self.secp_ctx) {
+               if self.prev_holder_htlc_sigs.is_none() {
+                       if let Some(ref holder_commitment) = self.prev_holder_commitment {
+                               let (_sig, sigs) = self.key_storage.sign_holder_commitment_and_htlcs(holder_commitment, &self.secp_ctx).expect("sign previous holder commitment");
                                self.prev_holder_htlc_sigs = Some(Self::extract_holder_sigs(holder_commitment, sigs));
                        }
                }
@@ -939,50 +945,35 @@ impl<ChanSigner: ChannelKeys> OnchainTxHandler<ChanSigner> {
        // have empty holder commitment transaction if a ChannelMonitor is asked to force-close just after Channel::get_outbound_funding_created,
        // before providing a initial commitment transaction. For outbound channel, init ChannelMonitor at Channel::funding_signed, there is nothing
        // to monitor before.
-       pub(crate) fn get_fully_signed_holder_tx(&mut self, funding_redeemscript: &Script) -> Option<Transaction> {
-               if let Some(ref mut holder_commitment) = self.holder_commitment {
-                       match self.key_storage.sign_holder_commitment(&holder_commitment, &self.secp_ctx) {
-                               Ok(sig) => {
-                                       Some(holder_commitment.add_holder_sig(funding_redeemscript, sig))
-                               },
-                               Err(_) => return None,
-                       }
-               } else {
-                       None
-               }
+       pub(crate) fn get_fully_signed_holder_tx(&mut self, funding_redeemscript: &Script) -> Transaction {
+               let (sig, htlc_sigs) = self.key_storage.sign_holder_commitment_and_htlcs(&self.holder_commitment, &self.secp_ctx).expect("signing holder commitment");
+               self.holder_htlc_sigs = Some(Self::extract_holder_sigs(&self.holder_commitment, htlc_sigs));
+               self.holder_commitment.add_holder_sig(funding_redeemscript, sig)
        }
 
        #[cfg(any(test, feature="unsafe_revoked_tx_signing"))]
-       pub(crate) fn get_fully_signed_copy_holder_tx(&mut self, funding_redeemscript: &Script) -> Option<Transaction> {
-               if let Some(ref mut holder_commitment) = self.holder_commitment {
-                       match self.key_storage.sign_holder_commitment(holder_commitment, &self.secp_ctx) {
-                               Ok(sig) => {
-                                       Some(holder_commitment.add_holder_sig(funding_redeemscript, sig))
-                               },
-                               Err(_) => return None,
-                       }
-               } else {
-                       None
-               }
+       pub(crate) fn get_fully_signed_copy_holder_tx(&mut self, funding_redeemscript: &Script) -> Transaction {
+               let (sig, htlc_sigs) = self.key_storage.sign_holder_commitment_and_htlcs(&self.holder_commitment, &self.secp_ctx).expect("sign holder commitment");
+               self.holder_htlc_sigs = Some(Self::extract_holder_sigs(&self.holder_commitment, htlc_sigs));
+               self.holder_commitment.add_holder_sig(funding_redeemscript, sig)
        }
 
        pub(crate) fn get_fully_signed_htlc_tx(&mut self, outp: &::bitcoin::OutPoint, preimage: &Option<PaymentPreimage>) -> Option<Transaction> {
                let mut htlc_tx = None;
-               if self.holder_commitment.is_some() {
-                       let commitment_txid = self.holder_commitment.as_ref().unwrap().trust().txid();
-                       if commitment_txid == outp.txid {
-                               self.sign_latest_holder_htlcs();
-                               if let &Some(ref htlc_sigs) = &self.holder_htlc_sigs {
-                                       let &(ref htlc_idx, ref htlc_sig) = htlc_sigs[outp.vout as usize].as_ref().unwrap();
-                                       let holder_commitment = self.holder_commitment.as_ref().unwrap();
-                                       let trusted_tx = holder_commitment.trust();
-                                       let counterparty_htlc_sig = holder_commitment.counterparty_htlc_sigs[*htlc_idx];
-                                       htlc_tx = Some(trusted_tx
-                                               .get_signed_htlc_tx(&self.channel_transaction_parameters.as_holder_broadcastable(), *htlc_idx, &counterparty_htlc_sig, htlc_sig, preimage));
-                               }
+               let commitment_txid = self.holder_commitment.trust().txid();
+               // Check if the HTLC spends from the current holder commitment
+               if commitment_txid == outp.txid {
+                       self.sign_latest_holder_htlcs();
+                       if let &Some(ref htlc_sigs) = &self.holder_htlc_sigs {
+                               let &(ref htlc_idx, ref htlc_sig) = htlc_sigs[outp.vout as usize].as_ref().unwrap();
+                               let trusted_tx = self.holder_commitment.trust();
+                               let counterparty_htlc_sig = self.holder_commitment.counterparty_htlc_sigs[*htlc_idx];
+                               htlc_tx = Some(trusted_tx
+                                       .get_signed_htlc_tx(&self.channel_transaction_parameters.as_holder_broadcastable(), *htlc_idx, &counterparty_htlc_sig, htlc_sig, preimage));
                        }
                }
-               if self.prev_holder_commitment.is_some() {
+               // If the HTLC doesn't spend the current holder commitment, check if it spends the previous one
+               if htlc_tx.is_none() && self.prev_holder_commitment.is_some() {
                        let commitment_txid = self.prev_holder_commitment.as_ref().unwrap().trust().txid();
                        if commitment_txid == outp.txid {
                                self.sign_prev_holder_htlcs();
index 92cf178c8c5d912a61e21a6e0d24f778ece99e7c..8229f6048600f79172be41c7451580524831764e 100644 (file)
@@ -72,20 +72,7 @@ impl ChannelKeys for EnforcingChannelKeys {
                Ok(self.inner.sign_counterparty_commitment(commitment_tx, secp_ctx).unwrap())
        }
 
-       fn sign_holder_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
-               self.verify_holder_commitment_tx(commitment_tx, secp_ctx);
-
-               // TODO: enforce the ChannelKeys contract - error if this commitment was already revoked
-               // TODO: need the commitment number
-               Ok(self.inner.sign_holder_commitment(commitment_tx, secp_ctx).unwrap())
-       }
-
-       #[cfg(any(test,feature = "unsafe_revoked_tx_signing"))]
-       fn unsafe_sign_holder_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
-               Ok(self.inner.unsafe_sign_holder_commitment(commitment_tx, secp_ctx).unwrap())
-       }
-
-       fn sign_holder_commitment_htlc_transactions<T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Vec<Signature>, ()> {
+       fn sign_holder_commitment_and_htlcs<T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<(Signature, Vec<Signature>), ()> {
                let trusted_tx = self.verify_holder_commitment_tx(commitment_tx, secp_ctx);
                let commitment_txid = trusted_tx.txid();
                let holder_csv = self.inner.counterparty_selected_contest_delay();
@@ -101,7 +88,14 @@ impl ChannelKeys for EnforcingChannelKeys {
                        secp_ctx.verify(&sighash, sig, &keys.countersignatory_htlc_key).unwrap();
                }
 
-               Ok(self.inner.sign_holder_commitment_htlc_transactions(commitment_tx, secp_ctx).unwrap())
+               // TODO: enforce the ChannelKeys contract - error if this commitment was already revoked
+               // TODO: need the commitment number
+               Ok(self.inner.sign_holder_commitment_and_htlcs(commitment_tx, secp_ctx).unwrap())
+       }
+
+       #[cfg(any(test,feature = "unsafe_revoked_tx_signing"))]
+       fn unsafe_sign_holder_commitment<T: secp256k1::Signing + secp256k1::Verification>(&self, commitment_tx: &HolderCommitmentTransaction, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {
+               Ok(self.inner.unsafe_sign_holder_commitment(commitment_tx, secp_ctx).unwrap())
        }
 
        fn sign_justice_transaction<T: secp256k1::Signing + secp256k1::Verification>(&self, justice_tx: &Transaction, input: usize, amount: u64, per_commitment_key: &SecretKey, htlc: &Option<HTLCOutputInCommitment>, secp_ctx: &Secp256k1<T>) -> Result<Signature, ()> {