splice: Gossip new scid on splice_lock

channeld/channeld.c

@@ -756,6 +756,9 @@ static void check_mutual_splice_locked(struct peer *peer)
 						&inflight->outpoint.txid);
 	wire_sync_write(MASTER_FD, take(msg));
 
+	/* We must regossip the scid since it has changed */
+	peer->gossip_scid_announced = false;
+
 	channel_announcement_negotiate(peer);
 	billboard_update(peer);
 	send_channel_update(peer, 0);

tests/test_splicing.py

@@ -1,8 +1,10 @@
 from fixtures import *  # noqa: F401,F403
-from utils import TEST_NETWORK
 import pytest
 import unittest
 import time
+from utils import (
+    wait_for, TEST_NETWORK
+)
 
 
 @pytest.mark.openchannel('v1')
@@ -39,3 +41,48 @@ def test_splice(node_factory, bitcoind):
     # Check that the splice doesn't generate a unilateral close transaction
     time.sleep(5)
     assert l1.db_query("SELECT count(*) as c FROM channeltxs;")[0]['c'] == 0
+
+
+@pytest.mark.openchannel('v1')
+@pytest.mark.openchannel('v2')
+@unittest.skipIf(TEST_NETWORK != 'regtest', 'elementsd doesnt yet support PSBT features we need')
+def test_splice_gossip(node_factory, bitcoind):
+    l1, l2, l3 = node_factory.line_graph(3, fundamount=1000000, wait_for_announce=True, opts={'experimental-splicing': None})
+
+    chan_id = l1.get_channel_id(l2)
+
+    # add extra sats to pay fee
+    funds_result = l1.rpc.fundpsbt("109000sat", "slow", 166, excess_as_change=True)
+
+    result = l1.rpc.splice_init(chan_id, 100000, funds_result['psbt'])
+    result = l1.rpc.splice_update(chan_id, result['psbt'])
+    result = l1.rpc.signpsbt(result['psbt'])
+    result = l1.rpc.splice_signed(chan_id, result['signed_psbt'])
+
+    l2.daemon.wait_for_log(r'CHANNELD_NORMAL to CHANNELD_AWAITING_SPLICE')
+    l1.daemon.wait_for_log(r'CHANNELD_NORMAL to CHANNELD_AWAITING_SPLICE')
+
+    mempool = bitcoind.rpc.getrawmempool(True)
+    assert len(list(mempool.keys())) == 1
+    assert result['txid'] in list(mempool.keys())
+
+    bitcoind.generate_block(6, wait_for_mempool=1)
+
+    l2.daemon.wait_for_log(r'CHANNELD_AWAITING_SPLICE to CHANNELD_NORMAL')
+    l1.daemon.wait_for_log(r'CHANNELD_AWAITING_SPLICE to CHANNELD_NORMAL')
+
+    # l3 should see the old channel and new channel at the same time here
+    wait_for(lambda: len(l3.rpc.listchannels()['channels']) == 6)
+
+    bitcoind.generate_block(7)
+
+    # The old channel should fall off l3's perspective
+    wait_for(lambda: len(l3.rpc.listchannels()['channels']) == 4)
+
+    # Check that the splice doesn't generate a unilateral close transaction
+    time.sleep(5)
+    assert l1.db_query("SELECT count(*) as c FROM channeltxs;")[0]['c'] == 0
+
+    # Check for channel announcement failure
+    assert not l1.daemon.is_in_log("invalid local_channel_announcement")
+    assert not l2.daemon.is_in_log("invalid local_channel_announcement")