closingd: add notifications for feerate ranges.

This allows cmdline users to have more idea what's going on.

Inspired-by: #4777
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Changelog-Added: `close` now notifies about the feeranges each side uses.

closingd/closingd.c

@@ -32,6 +32,20 @@
 #define REQ_FD STDIN_FILENO
 #define HSM_FD 6
 
+static void notify(enum log_level level, const char *fmt, ...)
+{
+	va_list ap;
+
+	va_start(ap, fmt);
+	wire_sync_write(REQ_FD,
+			take(towire_closingd_notification(NULL,
+							  level,
+							  tal_vfmt(tmpctx, fmt,
+								   ap))));
+
+	va_end(ap);
+}
+
 static struct bitcoin_tx *close_tx(const tal_t *ctx,
 				   const struct chainparams *chainparams,
 				   struct per_peer_state *pps,
@@ -192,6 +206,10 @@ static void send_offer(struct per_peer_state *pps,
 		close_tlvs->fee_range
 			= cast_const(struct tlv_closing_signed_tlvs_fee_range *,
 				     tlv_fees);
+		notify(LOG_INFORM, "Sending closing fee offer %s, with range %s-%s",
+		       type_to_string(tmpctx, struct amount_sat, &fee_to_offer),
+		       type_to_string(tmpctx, struct amount_sat, &tlv_fees->min_fee_satoshis),
+		       type_to_string(tmpctx, struct amount_sat, &tlv_fees->max_fee_satoshis));
 	} else
 		close_tlvs = NULL;
 
@@ -345,10 +363,17 @@ receive_offer(struct per_peer_state *pps,
 		     type_to_string(tmpctx, struct amount_sat, &received_fee));
 
 	if (tlv_fees) {
-		if (close_tlvs)
+		if (close_tlvs) {
 			*tlv_fees = tal_steal(tlv_fees, close_tlvs->fee_range);
-		else
+			notify(LOG_INFORM, "Received closing fee offer %s, with range %s-%s",
+			       type_to_string(tmpctx, struct amount_sat, &received_fee),
+			       type_to_string(tmpctx, struct amount_sat, &(*tlv_fees)->min_fee_satoshis),
+			       type_to_string(tmpctx, struct amount_sat, &(*tlv_fees)->max_fee_satoshis));
+		} else {
 			*tlv_fees = NULL;
+			notify(LOG_INFORM, "Received closing fee offer %s, without range",
+			       type_to_string(tmpctx, struct amount_sat, &received_fee));
+		}
 	}
 
 	/* Master sorts out what is best offer, we just tell it any above min */
@@ -1078,4 +1103,5 @@ int main(int argc, char *argv[])
 	daemon_shutdown();
 
 	return 0;
+
 }

closingd/closingd_wire.csv

@@ -3,6 +3,7 @@
 #include <common/cryptomsg.h>
 #include <common/htlc_wire.h>
 #include <common/per_peer_state.h>
+#include <common/status_wire.h>
 # Begin!  (passes peer fd, gossipd-client fd)
 msgtype,closingd_init,2001
 msgdata,closingd_init,chainparams,chainparams,
@@ -31,6 +32,11 @@ msgdata,closingd_init,use_quickclose,bool,
 msgdata,closingd_init,dev_fast_gossip,bool,
 msgdata,closingd_init,shutdown_wrong_funding,?bitcoin_outpoint,
 
+# Message for any commands waiting.
+msgtype,closingd_notification,2003
+msgdata,closingd_notification,level,enum log_level,
+msgdata,closingd_notification,message,wirestring,
+
 # We received an offer, save signature.
 msgtype,closingd_received_signature,2002
 msgdata,closingd_received_signature,signature,bitcoin_signature,

lightningd/closing_control.c

@@ -283,6 +283,25 @@ static void peer_closing_complete(struct channel *channel, const u8 *msg)
 			  "Closing complete");
 }
 
+static void peer_closing_notify(struct channel *channel, const u8 *msg)
+{
+	char *message;
+	struct close_command *i;
+	enum log_level level;
+
+	if (!fromwire_closingd_notification(msg, msg, &level, &message)) {
+		channel_internal_error(channel, "Bad closing_notify %s",
+				       tal_hex(msg, msg));
+		return;
+	}
+
+	list_for_each(&channel->peer->ld->close_commands, i, list) {
+		if (i->channel != channel)
+			continue;
+		json_notify_fmt(i->cmd, level, "%s", message);
+	}
+}
+
 static unsigned closing_msg(struct subd *sd, const u8 *msg, const int *fds UNUSED)
 {
 	enum closingd_wire t = fromwire_peektype(msg);
@@ -296,6 +315,10 @@ static unsigned closing_msg(struct subd *sd, const u8 *msg, const int *fds UNUSE
 		peer_closing_complete(sd->channel, msg);
 		break;
 
+	case WIRE_CLOSINGD_NOTIFICATION:
+		peer_closing_notify(sd->channel, msg);
+		break;
+
 	/* We send these, not receive them */
 	case WIRE_CLOSINGD_INIT:
 	case WIRE_CLOSINGD_RECEIVED_SIGNATURE_REPLY:

tests/test_closing.py

@@ -3318,8 +3318,13 @@ def test_close_feerate_range(node_factory, bitcoind, chainparams):
     """Test the quick-close fee range negotiation"""
     l1, l2 = node_factory.line_graph(2)
 
+    notifications = []
+    def save_notifications(message, progress, request, **kwargs):
+        notifications.append(message)
+
     # Lowball the range here.
-    l1.rpc.close(l2.info['id'], feerange=['253perkw', 'normal'])
+    with l1.rpc.notify(save_notifications):
+        l1.rpc.close(l2.info['id'], feerange=['253perkw', 'normal'])
 
     if not chainparams['elements']:
         l1_range = [138, 4110]
@@ -3335,6 +3340,16 @@ def test_close_feerate_range(node_factory, bitcoind, chainparams):
     overlap = [max(l1_range[0], l2_range[0]), min(l1_range[1], l2_range[1])]
     l1.daemon.wait_for_log('performing quickclose in range {}sat-{}sat'.format(overlap[0], overlap[1]))
 
+    log = l1.daemon.is_in_log('Their actual closing tx fee is .*sat')
+    rate = re.match('.*Their actual closing tx fee is ([0-9]*sat).*', log).group(1)
+
+    assert notifications == ['Sending closing fee offer {}, with range {}sat-{}sat'.format(rate,
+                                                                                           l1_range[0],
+                                                                                           l1_range[1]),
+                             'Received closing fee offer {}, with range {}sat-{}sat'.format(rate,
+                                                                                            l2_range[0],
+                                                                                            l2_range[1])]
+
 
 def test_close_twice(node_factory, executor):
     # First feerate is too low, second fixes it.