Add rescan logic to ChainMonitor::block_connected

Electrum clients will only provide transaction data for outputs that
have been explicitly registered. Hence, upon registering new outputs,
recursively register any outputs to watch contained within dependent
transactions from the same block.

Author: jkczyz

lightning/src/chain/chainmonitor.rs

@@ -100,7 +100,14 @@ where C::Target: chain::Filter,
 			if let Some(ref chain_source) = self.chain_source {
 				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);
+						// Register any new outputs with the chain source for filtering and recurse
+						// if it indicates that there are dependent transactions within the block
+						// that had not been previously included in txdata.
+						let outpoint = OutPoint { txid, index: *idx as u16 };
+						if let Some(txdata) = chain_source.register_output(&outpoint, &output.script_pubkey) {
+							let txdata: Vec<_> = txdata.iter().map(|(index, tx)| (*index, tx)).collect();
+							self.block_connected(header, &txdata, height);
+						}
 					}
 				}
 			}