close: param to force-close a leased channel

By default, we won't close a channel that we leased to a peer.
You can override this with the `force_lease_closed` flag.

Changelog-Added: JSON-RPC: close now has parameter to force close a leased channel (option_will_fund)

channeld/channeld.c

@@ -1997,6 +1997,9 @@ static void handle_peer_shutdown(struct peer *peer, const u8 *shutdown)
 		peer_failed_warn(peer->pps, &peer->channel_id,
 				 "Bad shutdown %s", tal_hex(peer, shutdown));
 
+	/* FIXME: We shouldn't let them initiate a shutdown while the
+	 * channel is active (if we leased funds) */
+
 	/* BOLT #2:
 	 *
 	 * - if both nodes advertised the `option_upfront_shutdown_script`

contrib/pyln-client/pyln/client/lightning.py

@@ -515,17 +515,23 @@ class LightningRpc(UnixDomainSocketRpc):
         payload.update({k: v for k, v in kwargs.items()})
         return self.call("check", payload)
 
-    def close(self, peer_id, unilateraltimeout=None, destination=None, fee_negotiation_step=None):
+    def close(self, peer_id, unilateraltimeout=None, destination=None, fee_negotiation_step=None, force_lease_closed=False):
         """
         Close the channel with peer {id}, forcing a unilateral
         close after {unilateraltimeout} seconds if non-zero, and
         the to-local output will be sent to {destination}.
+
+        If channel funds have been leased to the peer and the
+        lease has not yet expired, you can force a close with
+        {force_lease_closed}. Note that your funds will still be
+        locked until the lease expires.
         """
         payload = {
             "id": peer_id,
             "unilateraltimeout": unilateraltimeout,
             "destination": destination,
-            "fee_negotiation_step": fee_negotiation_step
+            "fee_negotiation_step": fee_negotiation_step,
+            "force_lease_closed": force_lease_closed,
         }
         return self.call("close", payload)
 

doc/lightning-close.7

@@ -3,7 +3,7 @@
 lightning-close - Command for closing channels with direct peers
 .SH SYNOPSIS
 
-\fBclose\fR \fIid\fR [\fIunilateraltimeout\fR] [\fIdestination\fR] [\fIfee_negotiation_step\fR] [\fIwrong_funding\\\fR]
+\fBclose\fR \fIid\fR [\fIunilateraltimeout\fR] [\fIdestination\fR] [\fIfee_negotiation_step\fR] [\fIwrong_funding\fR] [\fIforce_lease_closed\fR]
 
 .SH DESCRIPTION
 
@@ -67,6 +67,11 @@ allowed if this peer opened the channel and the channel is unused: it
 can rescue openings which have been manually miscreated\.
 
 
+\fIforce_lease_closed\fR if the channel has funds leased to the peer
+(option_will_fund), we prevent initiation of a mutual close
+unless this flag is passed in\. Defaults to false\.
+
+
 The peer needs to be live and connected in order to negotiate a mutual
 close\. The default of unilaterally closing after 48 hours is usually a
 reasonable indication that you can no longer contact the peer\.
@@ -123,4 +128,4 @@ ZmnSCPxj \fI<ZmnSCPxj@protonmail.com\fR> is mainly responsible\.
 
 Main web site: \fIhttps://github.com/ElementsProject/lightning\fR
 
-\" SHA256STAMP:03f1e6937a88aad4bdcd29d010da9ced148e3498ea19b388e8cbfde25276482d
+\" SHA256STAMP:c36a8ba48c3d2826344e23f880c21e0183942df8523da94394e5786dec874083

doc/lightning-close.7.md

@@ -4,7 +4,7 @@ lightning-close -- Command for closing channels with direct peers
 SYNOPSIS
 --------
 
-**close** *id* \[*unilateraltimeout*\] \[*destination*\] \[*fee_negotiation_step*\] \[*wrong_funding\*]
+**close** *id* \[*unilateraltimeout*\] \[*destination*\] \[*fee_negotiation_step*\] \[*wrong_funding*\] \[*force_lease_closed*\]
 
 DESCRIPTION
 -----------
@@ -56,6 +56,11 @@ shutdown transaction will spend this output instead.  This is only
 allowed if this peer opened the channel and the channel is unused: it
 can rescue openings which have been manually miscreated.
 
+*force_lease_closed* if the channel has funds leased to the peer
+(option_will_fund), we prevent initiation of a mutual close
+unless this flag is passed in. Defaults to false.
+
+
 The peer needs to be live and connected in order to negotiate a mutual
 close. The default of unilaterally closing after 48 hours is usually a
 reasonable indication that you can no longer contact the peer.

lightningd/peer_control.c

@@ -1671,7 +1671,7 @@ static struct command_result *json_close(struct command *cmd,
 	struct channel *channel COMPILER_WANTS_INIT("gcc 7.3.0 fails, 8.3 OK");
 	unsigned int *timeout;
 	const u8 *close_to_script = NULL;
-	bool close_script_set, wrong_funding_changed;
+	bool close_script_set, wrong_funding_changed, *force_lease_close;
 	const char *fee_negotiation_step_str;
 	struct bitcoin_outpoint *wrong_funding;
 	char* end;
@@ -1685,6 +1685,8 @@ static struct command_result *json_close(struct command *cmd,
 		   p_opt("fee_negotiation_step", param_string,
 			 &fee_negotiation_step_str),
 		   p_opt("wrong_funding", param_outpoint, &wrong_funding),
+		   p_opt_def("force_lease_closed", param_bool,
+			     &force_lease_close, false),
 		   NULL))
 		return command_param_failed();
 
@@ -1714,6 +1716,15 @@ static struct command_result *json_close(struct command *cmd,
 				    "Peer has no active channel");
 	}
 
+	if (!*force_lease_close && channel->opener != LOCAL
+	    && get_block_height(cmd->ld->topology) < channel->lease_expiry)
+		return command_fail(cmd, LIGHTNINGD,
+				    "Peer leased this channel from us, we"
+				    " shouldn't close until lease has expired"
+				    " (lease expires block %u,"
+				    " current block %u)",
+				    channel->lease_expiry,
+				    get_block_height(cmd->ld->topology));
 
 	/* If we've set a local shutdown script for this peer, and it's not the
 	 * default upfront script, try to close to a different channel.