dual-funding: update fee_step to be a feerate

Using a 'feestep' is more restrictive than you'd want, instead we
enforce that the next feerate must be at least 1/64th more than the
last, but put no upper limit on it

Includes update to lnprototest changes

Contributed-By: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
Changelog-EXPERIMENTAL: Protocol: Replaces init_rbf's `fee_step` for RBF of v2 opens with `funding_feerate_perkw`, breaking change

tests/test_opening.py

@@ -201,7 +201,7 @@ def test_v2_open_sigs_restart_while_dead(node_factory, bitcoind):
 
 @unittest.skipIf(TEST_NETWORK != 'regtest', 'elementsd doesnt yet support PSBT features we need')
 @pytest.mark.openchannel('v2')
-def test_v2_rbf(node_factory, bitcoind, chainparams):
+def test_v2_rbf_single(node_factory, bitcoind, chainparams):
     l1, l2 = node_factory.get_nodes(2, opts={'wumbo': None})
 
     l1.rpc.connect(l2.info['id'], 'localhost', l2.port)
@@ -227,8 +227,7 @@ def test_v2_rbf(node_factory, bitcoind, chainparams):
     info_1 = only_one(only_one(l1.rpc.listpeers(l2.info['id'])['peers'])['channels'])
     assert info_1['initial_feerate'] == info_1['last_feerate']
     rate = int(info_1['last_feerate'][:-5])
-    assert int(info_1['next_feerate'][:-5]) == rate + rate // 4
-    assert info_1['next_fee_step'] == 1
+    assert int(info_1['next_feerate'][:-5]) == rate * 65 // 64
 
     # Initiate an RBF
     startweight = 42 + 172  # base weight, funding output
@@ -249,11 +248,36 @@ def test_v2_rbf(node_factory, bitcoind, chainparams):
     assert info_1['next_feerate'] == info_2['last_feerate']
 
     rate = int(info_2['last_feerate'][:-5])
-    assert int(info_2['next_feerate'][:-5]) == rate + rate // 4
-    assert info_2['next_fee_step'] == 2
+    assert int(info_2['next_feerate'][:-5]) == rate * 65 // 64
 
     # Sign our inputs, and continue
     signed_psbt = l1.rpc.signpsbt(update['psbt'])['signed_psbt']
+
+    # Fails because we didn't put enough feerate in.
+    with pytest.raises(RpcError, match=r'insufficient fee'):
+        l1.rpc.openchannel_signed(chan_id, signed_psbt)
+
+    # Do it again, with a higher feerate
+    info_2 = only_one(only_one(l1.rpc.listpeers(l2.info['id'])['peers'])['channels'])
+    assert info_1['initial_feerate'] == info_2['initial_feerate']
+    assert info_1['next_feerate'] == info_2['last_feerate']
+    rate = int(info_2['last_feerate'][:-5])
+    assert int(info_2['next_feerate'][:-5]) == rate * 65 // 64
+
+    # We 4x the feerate to beat the min-relay fee
+    next_rate = '{}perkw'.format(rate * 65 // 64 * 4)
+    # Gotta unreserve the psbt and re-reserve with higher feerate
+    l1.rpc.unreserveinputs(initpsbt['psbt'])
+    initpsbt = l1.rpc.utxopsbt(chan_amount, next_rate, startweight,
+                               prev_utxos, reservedok=True,
+                               min_witness_weight=110,
+                               excess_as_change=True)
+    # Do the bump+sign
+    bump = l1.rpc.openchannel_bump(chan_id, chan_amount, initpsbt['psbt'],
+                                   funding_feerate=next_rate)
+    update = l1.rpc.openchannel_update(chan_id, bump['psbt'])
+    assert update['commitments_secured']
+    signed_psbt = l1.rpc.signpsbt(update['psbt'])['signed_psbt']
     l1.rpc.openchannel_signed(chan_id, signed_psbt)
 
     bitcoind.generate_block(1)
@@ -265,7 +289,6 @@ def test_v2_rbf(node_factory, bitcoind, chainparams):
     assert 'initial_feerate' not in info_1
     assert 'last_feerate' not in info_1
     assert 'next_feerate' not in info_1
-    assert 'next_fee_step' not in info_1
 
     # Shut l2 down, force close the channel.
     l2.stop()
@@ -304,7 +327,9 @@ def test_v2_rbf_multi(node_factory, bitcoind, chainparams):
     with pytest.raises(RpcError):
         l1.rpc.openchannel_abort(chan_id)
 
-    next_feerate = find_next_feerate(l1, l2)
+    rate = int(find_next_feerate(l1, l2)[:-5])
+    # We 4x the feerate to beat the min-relay fee
+    next_feerate = '{}perkw'.format(rate * 4)
 
     # Initiate an RBF
     startweight = 42 + 172  # base weight, funding output
@@ -314,15 +339,19 @@ def test_v2_rbf_multi(node_factory, bitcoind, chainparams):
                                excess_as_change=True)
 
     # Do the bump
-    bump = l1.rpc.openchannel_bump(chan_id, chan_amount, initpsbt['psbt'])
+    bump = l1.rpc.openchannel_bump(chan_id, chan_amount,
+                                   initpsbt['psbt'],
+                                   funding_feerate=next_feerate)
 
     # Abort this open attempt! We will re-try
     aborted = l1.rpc.openchannel_abort(chan_id)
     assert not aborted['channel_canceled']
 
-    # Do the bump, again
+    # Do the bump, again, same feerate
     l1.rpc.connect(l2.info['id'], 'localhost', l2.port)
-    bump = l1.rpc.openchannel_bump(chan_id, chan_amount, initpsbt['psbt'])
+    bump = l1.rpc.openchannel_bump(chan_id, chan_amount,
+                                   initpsbt['psbt'],
+                                   funding_feerate=next_feerate)
 
     update = l1.rpc.openchannel_update(chan_id, bump['psbt'])
     assert update['commitments_secured']
@@ -331,9 +360,11 @@ def test_v2_rbf_multi(node_factory, bitcoind, chainparams):
     signed_psbt = l1.rpc.signpsbt(update['psbt'])['signed_psbt']
     l1.rpc.openchannel_signed(chan_id, signed_psbt)
 
-    next_feerate = find_next_feerate(l1, l2)
+    # We 2x the feerate to beat the min-relay fee
+    rate = int(find_next_feerate(l1, l2)[:-5])
+    next_feerate = '{}perkw'.format(rate * 2)
 
-    # Initiate an RBF, double the channel amount this time
+    # Initiate another RBF, double the channel amount this time
     startweight = 42 + 172  # base weight, funding output
     initpsbt = l1.rpc.utxopsbt(chan_amount * 2, next_feerate, startweight,
                                prev_utxos, reservedok=True,
@@ -341,7 +372,9 @@ def test_v2_rbf_multi(node_factory, bitcoind, chainparams):
                                excess_as_change=True)
 
     # Do the bump
-    bump = l1.rpc.openchannel_bump(chan_id, chan_amount * 2, initpsbt['psbt'])
+    bump = l1.rpc.openchannel_bump(chan_id, chan_amount * 2,
+                                   initpsbt['psbt'],
+                                   funding_feerate=next_feerate)
 
     update = l1.rpc.openchannel_update(chan_id, bump['psbt'])
     assert update['commitments_secured']
@@ -724,14 +757,18 @@ def test_rbf_fails_to_broadcast(node_factory, bitcoind, chainparams):
 
     def run_retry():
         startweight = 42 + 173
-        next_feerate = find_next_feerate(l1, l2)
+        rate = int(find_next_feerate(l1, l2)[:-5])
+        # We 2x the feerate to beat the min-relay fee
+        next_feerate = '{}perkw'.format(rate * 2)
         initpsbt = l1.rpc.utxopsbt(chan_amount, next_feerate, startweight,
                                    prev_utxos, reservedok=True,
                                    min_witness_weight=110,
                                    excess_as_change=True)
 
         l1.rpc.connect(l2.info['id'], 'localhost', l2.port)
-        bump = l1.rpc.openchannel_bump(chan_id, chan_amount, initpsbt['psbt'])
+        bump = l1.rpc.openchannel_bump(chan_id, chan_amount,
+                                       initpsbt['psbt'],
+                                       funding_feerate=next_feerate)
         # We should be able to call this with while an open is progress
         # but not yet committed
         l1.rpc.dev_sign_last_tx(l2.info['id'])
@@ -741,37 +778,19 @@ def test_rbf_fails_to_broadcast(node_factory, bitcoind, chainparams):
         return l1.rpc.signpsbt(update['psbt'])['signed_psbt']
 
     signed_psbt = run_retry()
-    with pytest.raises(RpcError, match=r'insufficient fee, rejecting replacement'):
-        l1.rpc.openchannel_signed(chan_id, signed_psbt)
+    l1.rpc.openchannel_signed(chan_id, signed_psbt)
     inflights = only_one(only_one(l1.rpc.listpeers()['peers'])['channels'])['inflight']
-    assert inflights[-1]['funding_txid'] not in bitcoind.rpc.getrawmempool()
+    assert inflights[-1]['funding_txid'] in bitcoind.rpc.getrawmempool()
 
-    # If we restart and listpeers, it will crash
+    # Restart and listpeers, used to crash
     l1.restart()
-
     l1.rpc.listpeers()
 
-    # We've restarted. Let's RBF until we successfully get a
-    # new funding transaction for this channel
-    # do it again
-    signed_psbt = run_retry()
-    with pytest.raises(RpcError, match=r'insufficient fee, rejecting replacement'):
-        l1.rpc.openchannel_signed(chan_id, signed_psbt)
-    inflights = only_one(only_one(l1.rpc.listpeers()['peers'])['channels'])['inflight']
-    assert inflights[-1]['funding_txid'] not in bitcoind.rpc.getrawmempool()
-
-    # and again
-    signed_psbt = run_retry()
-    with pytest.raises(RpcError, match=r'insufficient fee, rejecting replacement'):
-        l1.rpc.openchannel_signed(chan_id, signed_psbt)
-    inflights = only_one(only_one(l1.rpc.listpeers()['peers'])['channels'])['inflight']
-    assert inflights[-1]['funding_txid'] not in bitcoind.rpc.getrawmempool()
-
-    # now we should be ok
+    # We've restarted. Let's RBF
     signed_psbt = run_retry()
     l1.rpc.openchannel_signed(chan_id, signed_psbt)
     inflights = only_one(only_one(l1.rpc.listpeers()['peers'])['channels'])['inflight']
-    assert len(inflights) == 5
+    assert len(inflights) == 3
     assert inflights[-1]['funding_txid'] in bitcoind.rpc.getrawmempool()
 
     l1.restart()
@@ -896,7 +915,9 @@ def test_rbf_non_last_mined(node_factory, bitcoind, chainparams):
 
     def run_retry():
         startweight = 42 + 173
-        next_feerate = find_next_feerate(l1, l2)
+        rate = int(find_next_feerate(l1, l2)[:-5])
+        # We 2x the feerate to beat the min-relay fee
+        next_feerate = '{}perkw'.format(rate * 2)
         initpsbt = l1.rpc.utxopsbt(chan_amount, next_feerate, startweight,
                                    prev_utxos, reservedok=True,
                                    min_witness_weight=110,