Add OnchainTxHandler::get_fully_signed_htlc

In case of channel force-closure, access to local commitment
transactions and its dependent HTLCs is needed. Instead of using
broadcast_by_local_state which registers outpoint to claim and
outputs to watch which are going to be discarded in this case,
we simply ask OnchainTxHandler to build and sign HTLC transactions
through new API.

diff --git a/lightning/src/ln/channelmonitor.rs b/lightning/src/ln/channelmonitor.rs
index 0f6cc826e5df294cda33c4550d6336584fbceea9..f4f03abc3e20835258302766882d09e6b539f4eb 100644 (file)
--- a/lightning/src/ln/channelmonitor.rs
+++ b/lightning/src/ln/channelmonitor.rs
@@ -1819,10 +1819,17 @@ impl<ChanSigner: ChannelKeys> ChannelMonitor<ChanSigner> {
        pub fn get_latest_local_commitment_txn(&mut self) -> Vec<Transaction> {
                log_trace!(self, "Getting signed latest local commitment transaction!");
                if let Some(commitment_tx) = self.onchain_tx_handler.get_fully_signed_local_tx(self.channel_value_satoshis.unwrap()) {
+                       let txid = commitment_tx.txid();
                        let mut res = vec![commitment_tx];
                        if let &Some(ref local_tx) = &self.current_local_signed_commitment_tx {
-                               let mut htlc_txn = self.broadcast_by_local_state(res.get(0).unwrap(), local_tx).0;
-                               res.append(&mut htlc_txn);
+                               for htlc in local_tx.htlc_outputs.iter() {
+                                       if let Some(htlc_index) = htlc.0.transaction_output_index {
+                                               let preimage = if let Some(preimage) = self.payment_preimages.get(&htlc.0.payment_hash) { Some(*preimage) } else { None };
+                                               if let Some(htlc_tx) = self.onchain_tx_handler.get_fully_signed_htlc_tx(txid, htlc_index, 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_local_transaction if we get a confirmation.
                        }
@@ -1838,10 +1845,17 @@ impl<ChanSigner: ChannelKeys> ChannelMonitor<ChanSigner> {
        pub fn unsafe_get_latest_local_commitment_txn(&mut self) -> Vec<Transaction> {
                log_trace!(self, "Getting signed copy of latest local commitment transaction!");
                if let Some(commitment_tx) = self.onchain_tx_handler.get_fully_signed_copy_local_tx(self.channel_value_satoshis.unwrap()) {
+                       let txid = commitment_tx.txid();
                        let mut res = vec![commitment_tx];
                        if let &Some(ref local_tx) = &self.current_local_signed_commitment_tx {
-                               let mut htlc_txn = self.broadcast_by_local_state(res.get(0).unwrap(), local_tx).0;
-                               res.append(&mut htlc_txn);
+                               for htlc in local_tx.htlc_outputs.iter() {
+                                       if let Some(htlc_index) = htlc.0.transaction_output_index {
+                                               let preimage = if let Some(preimage) = self.payment_preimages.get(&htlc.0.payment_hash) { Some(*preimage) } else { None };
+                                               if let Some(htlc_tx) = self.onchain_tx_handler.get_fully_signed_htlc_tx(txid, htlc_index, preimage) {
+                                                       res.push(htlc_tx);
+                                               }
+                                       }
+                               }
                        }
                        return res
                }

diff --git a/lightning/src/ln/onchaintx.rs b/lightning/src/ln/onchaintx.rs
index fce935549024ae697e5e611bb730382ce8f5f83f..8cb9bfb397ac4f14a2450f7ebc5709d43e58ab69 100644 (file)
--- a/lightning/src/ln/onchaintx.rs
+++ b/lightning/src/ln/onchaintx.rs
@@ -15,7 +15,7 @@ use secp256k1;
 
 use ln::msgs::DecodeError;
 use ln::channelmonitor::{ANTI_REORG_DELAY, CLTV_SHARED_CLAIM_BUFFER, InputMaterial, ClaimRequest};
-use ln::channelmanager::HTLCSource;
+use ln::channelmanager::{HTLCSource, PaymentPreimage};
 use ln::chan_utils;
 use ln::chan_utils::{HTLCType, LocalCommitmentTransaction, TxCreationKeys, HTLCOutputInCommitment};
 use chain::chaininterface::{FeeEstimator, BroadcasterInterface, ConfirmationTarget, MIN_RELAY_FEE_SAT_PER_1000_WEIGHT};
@@ -893,4 +893,23 @@ impl<ChanSigner: ChannelKeys> OnchainTxHandler<ChanSigner> {
                }
                None
        }
+
+       pub(super) fn get_fully_signed_htlc_tx(&mut self, txid: Sha256dHash, htlc_index: u32, preimage: Option<PaymentPreimage>) -> Option<Transaction> {
+               //TODO: store preimage in OnchainTxHandler
+               if let Some(ref local_commitment) = self.local_commitment {
+                       if local_commitment.txid() == txid {
+                               if let Some(ref htlc_cache) = self.current_htlc_cache {
+                                       if let Some(htlc) = htlc_cache.per_htlc.get(&htlc_index) {
+                                               if !htlc.0.offered && preimage.is_none() { return None; }; // If we don't have preimage for HTLC-Success, don't try to generate
+                                               let htlc_secret = if !htlc.0.offered { preimage } else { None }; // If we have a preimage for a HTLC-Timeout, don't use it that's likely a duplicate HTLC hash
+                                               let mut htlc_tx = chan_utils::build_htlc_transaction(&txid, htlc_cache.feerate_per_kw, self.local_csv, &htlc.0, &htlc_cache.local_keys.a_delayed_payment_key, &htlc_cache.local_keys.revocation_key);
+                                               self.key_storage.sign_htlc_transaction(&mut htlc_tx, htlc.1.as_ref().unwrap(), &htlc_secret, &htlc.0, &htlc_cache.local_keys.a_htlc_key, &htlc_cache.local_keys.b_htlc_key, &htlc_cache.local_keys.revocation_key, &htlc_cache.local_keys.per_commitment_point, &self.secp_ctx);
+                                               return Some(htlc_tx);
+
+                                       }
+                               }
+                       }
+               }
+               None
+       }
 }