Add an accessor to ChainMonitor to fet the claimable balances

The common user desire is to get the set of claimable balances for
all non-closed channels. In order to do so, they really want to
just ask their `ChainMonitor` for the set of balances, which they
can do here by passing the `ChannelManager::list_channels` output
to `ChainMonitor::get_claimable_balances`.

Author: TheBlueMatt

lightning/src/chain/chainmonitor.rs

@@ -30,12 +30,13 @@ use chain;
 use chain::{Filter, WatchedOutput};
 use chain::chaininterface::{BroadcasterInterface, FeeEstimator};
 use chain::channelmonitor;
-use chain::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate, ChannelMonitorUpdateErr, MonitorEvent, Persist, TransactionOutputs};
+use chain::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate, ChannelMonitorUpdateErr, ClaimableBalance, MonitorEvent, Persist, TransactionOutputs};
 use chain::transaction::{OutPoint, TransactionData};
 use chain::keysinterface::Sign;
 use util::logger::Logger;
 use util::events;
 use util::events::EventHandler;
+use ln::channelmanager::ChannelDetails;
 
 use prelude::*;
 use sync::RwLock;
@@ -140,6 +141,29 @@ where C::Target: chain::Filter,
 		}
 	}
 
+	/// Gets the balances in the contained [`ChannelMonitor`]s which are claimable on-chain or
+	/// claims which are awaiting confirmation.
+	///
+	/// Includes the balances from each [`ChannelMonitor`] *except* those included in
+	/// `ignored_channels`, allowing you to filter for only channels which are not still open (and
+	/// who's balance should likely be pulled from the [`ChannelDetails`].
+	///
+	/// See [`ChannelMonitor::get_claimable_balances`] for more details on the exact criteria for
+	/// inclusion in the return value.
+	pub fn get_claimable_balances(&self, ignored_channels: &[ChannelDetails]) -> Vec<ClaimableBalance> {
+		let mut ret = Vec::new();
+		let monitors = self.monitors.read().unwrap();
+		'monitor_iter: for (funding_outpoint, monitor) in monitors.iter() {
+			for chan in ignored_channels {
+				if chan.funding_txo.as_ref() == Some(funding_outpoint) {
+					continue 'monitor_iter;
+				}
+			}
+			ret.append(&mut monitor.get_claimable_balances());
+		}
+		ret
+	}
+
 	#[cfg(any(test, feature = "fuzztarget", feature = "_test_utils"))]
 	pub fn get_and_clear_pending_events(&self) -> Vec<events::Event> {
 		use util::events::EventsProvider;