lightningd: don't ignore fee limits on mutual close.

LDK will pick the *upper* limit (see: lightningdevkit/rust-lightning#3014)!

It should not do this, but since you can set a manual range for mutual close, it's probably better to disable this option for close, as it's even more dangerous than documented.

Changelog-Changed: config/JSON: --ignore-fee-limits / setchannel ignorefeelimits no longer applies to mutual close.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Fixes: ElementsProject#7242

lightningd/closing_control.c

@@ -434,9 +434,6 @@ void peer_start_closingd(struct channel *channel, struct peer_fd *peer_fd)
 	if (channel->closing_feerate_range) {
 		min_feerate = channel->closing_feerate_range[0];
 		max_feerate = channel->closing_feerate_range[1];
-	} else if (channel->ignore_fee_limits || ld->config.ignore_fee_limits) {
-		min_feerate = 253;
-		max_feerate = 0xFFFFFFFF;
 	}
 
 	/* BOLT #3:

tests/test_closing.py

@@ -4044,7 +4044,6 @@ def test_closing_no_anysegwit_retry(node_factory, bitcoind):
     l1.rpc.close(l2.info['id'], destination=oldaddr)
 
 
-@pytest.mark.xfail(strict=True)
 def test_closing_ignore_fee_limits(node_factory, bitcoind, executor):
     """Don't use ignore-fee-limits on mutual close: LDK takes us to the cleaners if we do!"""
     l1, l2 = node_factory.line_graph(2, opts=[{'may_reconnect': True,

tests/test_connection.py

@@ -2491,12 +2491,13 @@ def test_fee_limits(node_factory, bitcoind):
     wait_for(lambda: only_one(l2.rpc.listpeerchannels()['channels'])['feerate']['perkw'] == fee)
     assert only_one(l2.rpc.listpeerchannels()['channels'])['peer_connected'] is True
 
-    l1.rpc.close(l2.info['id'])
+    # This will fail to mutual close, since l2 won't ignore insane *close* fees!
+    assert l1.rpc.close(l2.info['id'], unilateraltimeout=5)['type'] == 'unilateral'
 
     # Make sure the resolution of this one doesn't interfere with the next!
     # Note: may succeed, may fail with insufficient fee, depending on how
     # bitcoind feels!
-    l2.daemon.wait_for_log('sendrawtx exit')
+    l1.daemon.wait_for_log('sendrawtx exit')
     bitcoind.generate_block(1)
     sync_blockheight(bitcoind, [l1, l2])
 
@@ -2530,7 +2531,6 @@ def test_fee_limits(node_factory, bitcoind):
     # 15sat/byte fee
     l1.daemon.wait_for_log('peer_out WIRE_REVOKE_AND_ACK')
 
-    # This should wait for close to complete
     l1.rpc.close(chan)