lightningd/log: debug-log-pr

doc/developers-guide/plugin-development/event-notifications.md

@@ -519,3 +519,16 @@ In the shutdown case, plugins should not interact with lightnind except via (id-
     }
 }
 ```
+
+### `channel_closed`
+
+A notification for topic `channel_closed` is sent when a channel has been successfully closed with a peer. It includes the peer id and the closing transaction ID.
+
+```json
+{
+  "channel_closed": {
+    "id": "0313ceef8b96120a48dbb8106e55b9aaa52787c376872ecc720bc4385c53df79d3",
+    "closing_txid": "0799d85107cb28cadbe4f9e12c3049b8175cda12dc399a870bf4b00d534d35f3"
+  }
+}
+```

lightningd/closing_control.c

@@ -31,6 +31,7 @@
 #include <lightningd/jsonrpc.h>
 #include <lightningd/lightningd.h>
 #include <lightningd/log.h>
+#include <lightningd/notification.h>
 #include <lightningd/opening_common.h>
 #include <lightningd/options.h>
 #include <lightningd/peer_control.h>
@@ -330,6 +331,13 @@ static void peer_closing_complete(struct channel *channel, const u8 *msg)
 			  REASON_UNKNOWN,
 			  "Closing complete");
 
+	struct bitcoin_txid closing_txid;
+	bitcoin_txid(channel->last_tx, &closing_txid);
+
+	/* Tell plugin about the channel close. */
+	notify_channel_closed(channel->peer->ld, &channel->peer->id,
+			      &closing_txid);
+
 	/* Channel gets dropped to chain cooperatively. */
 	drop_to_chain(channel->peer->ld, channel, true, NULL);
 }

lightningd/notification.c

@@ -292,6 +292,26 @@ void notify_channel_opened(struct lightningd *ld,
 	notify_send(ld, n);
 }
 
+static void channel_closed_notification_serialize(struct json_stream *stream,
+						  struct lightningd *ld,
+						  const struct node_id *node_id,
+						  const struct bitcoin_txid *closing_txid)
+{
+	json_add_node_id(stream, "id", node_id);
+	json_add_txid(stream, "closing_txid", closing_txid);
+}
+
+REGISTER_NOTIFICATION(channel_closed)
+
+void notify_channel_closed(struct lightningd *ld,
+			   const struct node_id *node_id,
+			   const struct bitcoin_txid *closing_txid)
+{
+	struct jsonrpc_notification *n = notify_start("channel_closed");
+	channel_closed_notification_serialize(n->stream, ld, node_id, closing_txid);
+	notify_send(ld, n);
+}
+
 static void channel_state_changed_notification_serialize(struct json_stream *stream,
 							 const struct node_id *peer_id,
 							 const struct channel_id *cid,

lightningd/notification.h

@@ -50,6 +50,10 @@ void notify_channel_opened(struct lightningd *ld,
 			   const struct bitcoin_txid *funding_txid,
 			   bool channel_ready);
 
+void notify_channel_closed(struct lightningd *ld,
+			   const struct node_id *node_id,
+			   const struct bitcoin_txid *closing_txid);
+
 void notify_channel_state_changed(struct lightningd *ld,
 				  const struct node_id *peer_id,
 				  const struct channel_id *cid,

tests/plugins/misc_notifications.py

@@ -22,6 +22,14 @@ def channel_opened(plugin, channel_opened, **kwargs):
                        channel_opened["funding_txid"]))
 
 
+@plugin.subscribe("channel_closed")
+def channel_closed(plugin, channel_closed, **kwargs):
+    plugin.log(
+        "A channel was closed to us by {}, with a closing"
+        " transaction ID: {}".format(channel_closed["id"],
+                                     channel_closed["closing_txid"]))
+
+
 @plugin.subscribe("channel_state_changed")
 def channel_state_changed(plugin, channel_state_changed, **kwargs):
     plugin.log("channel_state_changed {}".format(channel_state_changed))

tests/test_plugin.py

@@ -1335,6 +1335,27 @@ def test_channel_opened_notification(node_factory):
                            .format(l1.info["id"], amount))
 
 
+def test_channel_closed_notification(node_factory):
+    """
+    Test the 'channel_closed' notification sent at channel closing success.
+    """
+    plugin_path = os.path.join(os.getcwd(), "tests/plugins/misc_notifications.py")
+    opts = [{"plugin": plugin_path}, {"plugin": plugin_path}]
+    amount = 10**6
+    l1, l2 = node_factory.line_graph(2, fundchannel=True, fundamount=amount,
+                                     opts=opts)
+
+    closing_txid = only_one(l2.rpc.close(l1.info['id'])['txids'])
+
+    l1.daemon.wait_for_log(r"A channel was closed to us by {}, with a closing"
+                           " transaction ID: {}".format(l2.rpc.getinfo()["id"],
+                                                        closing_txid,))
+
+    l2.daemon.wait_for_log(r"A channel was closed to us by {}, with a closing"
+                           " transaction ID: {}".format(l1.rpc.getinfo()["id"],
+                                                        closing_txid,))
+
+
 def test_forward_event_notification(node_factory, bitcoind, executor):
     """ test 'forward_event' notifications
     """