Include block hash for watched transaction output

When registering a watched transaction output, any in-block descendant
transactions spending the output must be supplied. Give the block hash
when registering such outputs such that this is possible. Otherwise,
spends from other blocks may be returned inadvertently.

diff --git a/lightning/src/chain/chainmonitor.rs b/lightning/src/chain/chainmonitor.rs
index eb17b469a0365df2de4464ef313cc243441b6767..234e60b4c5967d7335711cbed1fd20da73e3c245 100644 (file)
--- a/lightning/src/chain/chainmonitor.rs
+++ b/lightning/src/chain/chainmonitor.rs
@@ -26,7 +26,7 @@
 use bitcoin::blockdata::block::{Block, BlockHeader};
 
 use chain;
-use chain::Filter;
+use chain::{Filter, WatchedOutput};
 use chain::chaininterface::{BroadcasterInterface, FeeEstimator};
 use chain::channelmonitor;
 use chain::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate, ChannelMonitorUpdateErr, MonitorEvent, Persist};
@@ -87,9 +87,14 @@ where C::Target: chain::Filter,
                        let mut txn_outputs = monitor.block_connected(header, txdata, height, &*self.broadcaster, &*self.fee_estimator, &*self.logger);
 
                        if let Some(ref chain_source) = self.chain_source {
+                               let block_hash = header.block_hash();
                                for (txid, outputs) in txn_outputs.drain(..) {
                                        for (idx, output) in outputs.iter() {
-                                               chain_source.register_output(&OutPoint { txid, index: *idx as u16 }, &output.script_pubkey);
+                                               chain_source.register_output(WatchedOutput {
+                                                       block_hash: Some(block_hash),
+                                                       outpoint: OutPoint { txid, index: *idx as u16 },
+                                                       script_pubkey: output.script_pubkey.clone(),
+                                               });
                                        }
                                }
                        }

diff --git a/lightning/src/chain/channelmonitor.rs b/lightning/src/chain/channelmonitor.rs
index 28b6da4722a7b4e3820541b30c89047d1e8e5cfe..939337d7b42d572d64c7ab5b1a6224479f6c1ce9 100644 (file)
--- a/lightning/src/chain/channelmonitor.rs
+++ b/lightning/src/chain/channelmonitor.rs
@@ -40,6 +40,7 @@ use ln::chan_utils::{CounterpartyCommitmentSecrets, HTLCOutputInCommitment, HTLC
 use ln::channelmanager::{HTLCSource, PaymentPreimage, PaymentHash};
 use ln::onchaintx::{OnchainTxHandler, InputDescriptors};
 use chain;
+use chain::WatchedOutput;
 use chain::chaininterface::{BroadcasterInterface, FeeEstimator};
 use chain::transaction::{OutPoint, TransactionData};
 use chain::keysinterface::{SpendableOutputDescriptor, StaticPaymentOutputDescriptor, DelayedPaymentOutputDescriptor, Sign, KeysInterface};
@@ -1174,7 +1175,11 @@ impl<Signer: Sign> ChannelMonitor<Signer> {
                for (txid, outputs) in lock.get_outputs_to_watch().iter() {
                        for (index, script_pubkey) in outputs.iter() {
                                assert!(*index <= u16::max_value() as u32);
-                               filter.register_output(&OutPoint { txid: *txid, index: *index as u16 }, script_pubkey);
+                               filter.register_output(WatchedOutput {
+                                       block_hash: None,
+                                       outpoint: OutPoint { txid: *txid, index: *index as u16 },
+                                       script_pubkey: script_pubkey.clone(),
+                               });
                        }
                }
        }

diff --git a/lightning/src/chain/mod.rs b/lightning/src/chain/mod.rs
index 67ae5b347f9d94b029f93333fbb68dc6e23f9518..18c7fd55d7b6643bbbc140a5208df42e39e42ea3 100644 (file)
--- a/lightning/src/chain/mod.rs
+++ b/lightning/src/chain/mod.rs
@@ -129,12 +129,38 @@ pub trait Filter: Send + Sync {
        /// a spending condition.
        fn register_tx(&self, txid: &Txid, script_pubkey: &Script);
 
-       /// Registers interest in spends of a transaction output identified by `outpoint` having
-       /// `script_pubkey` as the spending condition.
+       /// Registers interest in spends of a transaction output.
        ///
-       /// Optionally, returns any transaction dependent on the output. This is useful for Electrum
-       /// clients to facilitate registering in-block descendants.
-       fn register_output(&self, outpoint: &OutPoint, script_pubkey: &Script) -> Option<(usize, Transaction)>;
+       /// Optionally, when `output.block_hash` is set, should return any transaction spending the
+       /// output that is found in the corresponding block along with its index.
+       ///
+       /// This return value is useful for Electrum clients in order to supply in-block descendant
+       /// transactions which otherwise were not included. This is not necessary for other clients if
+       /// such descendant transactions were already included (e.g., when a BIP 157 client provides the
+       /// full block).
+       fn register_output(&self, output: WatchedOutput) -> Option<(usize, Transaction)>;
+}
+
+/// A transaction output watched by a [`ChannelMonitor`] for spends on-chain.
+///
+/// Used to convey to a [`Filter`] such an output with a given spending condition. Any transaction
+/// spending the output must be given to [`ChannelMonitor::block_connected`] either directly or via
+/// the return value of [`Filter::register_output`].
+///
+/// If `block_hash` is `Some`, this indicates the output was created in the corresponding block and
+/// may have been spent there. See [`Filter::register_output`] for details.
+///
+/// [`ChannelMonitor`]: channelmonitor::ChannelMonitor
+/// [`ChannelMonitor::block_connected`]: channelmonitor::ChannelMonitor::block_connected
+pub struct WatchedOutput {
+       /// First block where the transaction output may have been spent.
+       pub block_hash: Option<BlockHash>,
+
+       /// Outpoint identifying the transaction output.
+       pub outpoint: OutPoint,
+
+       /// Spending condition of the transaction output.
+       pub script_pubkey: Script,
 }
 
 impl<T: Listen> Listen for std::ops::Deref<Target = T> {

diff --git a/lightning/src/util/test_utils.rs b/lightning/src/util/test_utils.rs
index d2ba044e902e1ac943118aa16d137cc6da97d2c5..2eabfd5cb94ad1b84940892ba1942f91c7169820 100644 (file)
--- a/lightning/src/util/test_utils.rs
+++ b/lightning/src/util/test_utils.rs
@@ -8,6 +8,7 @@
 // licenses.
 
 use chain;
+use chain::WatchedOutput;
 use chain::chaininterface;
 use chain::chaininterface::ConfirmationTarget;
 use chain::chainmonitor;
@@ -546,8 +547,8 @@ impl chain::Filter for TestChainSource {
                self.watched_txn.lock().unwrap().insert((*txid, script_pubkey.clone()));
        }
 
-       fn register_output(&self, outpoint: &OutPoint, script_pubkey: &Script) -> Option<(usize, Transaction)> {
-               self.watched_outputs.lock().unwrap().insert((*outpoint, script_pubkey.clone()));
+       fn register_output(&self, output: WatchedOutput) -> Option<(usize, Transaction)> {
+               self.watched_outputs.lock().unwrap().insert((output.outpoint, output.script_pubkey));
                None
        }
 }