splice: enable and test mutli-channel splice script

Turns on mutli channel splices in splice script and adds a test for it.

Changelog-Changed: Splice script now supports splicing over multiple channels

Author: ddustin

plugins/spender/splice.c

@@ -1261,7 +1261,6 @@ validate_splice_cmd(struct splice_cmd *splice_cmd)
 {
 	struct splice_script_result *action;
 	int paying_fee_count = 0;
-	int channels = 0;
 	for (size_t i = 0; i < tal_count(splice_cmd->actions); i++) {
 		action = splice_cmd->actions[i];
 		/* Taking fee from onchain wallet requires recursive looping
@@ -1297,14 +1296,6 @@ validate_splice_cmd(struct splice_cmd *splice_cmd)
 					    JSONRPC2_INVALID_PARAMS,
 					    "Dynamic bitcoin address amounts"
 					    " not supported for now");
-		if (action->channel_id) {
-			if (channels)
-				return command_fail(splice_cmd->cmd,
-						    JSONRPC2_INVALID_PARAMS,
-						    "Multi-channel splice not"
-						    "supported for now");
-			channels++;
-		}
 		if (action->bitcoin_address)
 			return command_fail(splice_cmd->cmd,
 					    JSONRPC2_INVALID_PARAMS,

tests/test_splice.py

@@ -195,3 +195,35 @@ def test_script_splice_in(node_factory, bitcoind, chainparams):
     l1.wait_for_channel_onchain(l2.info['id'])
     account_info = only_one([acct for acct in l1.rpc.bkpr_listbalances()['accounts'] if acct['account'] == account_id])
     assert not account_info['account_closed']
+
+
+@pytest.mark.openchannel('v1')
+@pytest.mark.openchannel('v2')
+@unittest.skipIf(TEST_NETWORK != 'regtest', 'elementsd doesnt yet support PSBT features we need')
+def test_script_two_chan_splice_in(node_factory, bitcoind):
+    l1, l2, l3 = node_factory.line_graph(3, fundamount=1000000, wait_for_announce=True, opts={'experimental-splicing': None})
+
+    chan_id1 = l2.get_channel_id(l1)
+    chan_id2 = l2.get_channel_id(l3)
+
+    # l2 will splice funds into the channels with l1 and l3 at the same time
+    result = l2.rpc.splice(f"wallet -> 200999; 100000 -> {chan_id1}; 100000 -> {chan_id2}; * -> wallet", force_feerate=True, debug_log=True)
+
+    l3.daemon.wait_for_log(r'CHANNELD_NORMAL to CHANNELD_AWAITING_SPLICE')
+    l2.daemon.wait_for_log(r'CHANNELD_NORMAL to CHANNELD_AWAITING_SPLICE')
+    l1.daemon.wait_for_log(r'CHANNELD_NORMAL to CHANNELD_AWAITING_SPLICE')
+
+    wait_for(lambda: len(list(bitcoind.rpc.getrawmempool(True).keys())) == 1)
+    assert result['txid'] in list(bitcoind.rpc.getrawmempool(True).keys())
+
+    bitcoind.generate_block(6, wait_for_mempool=1)
+
+    l3.daemon.wait_for_log(r'CHANNELD_AWAITING_SPLICE to CHANNELD_NORMAL')
+    l2.daemon.wait_for_log(r'CHANNELD_AWAITING_SPLICE to CHANNELD_NORMAL')
+    l1.daemon.wait_for_log(r'CHANNELD_AWAITING_SPLICE to CHANNELD_NORMAL')
+
+    inv = l2.rpc.invoice(10**2, '1', 'no_1')
+    l1.rpc.pay(inv['bolt11'])
+
+    inv = l3.rpc.invoice(10**2, '2', 'no_2')
+    l2.rpc.pay(inv['bolt11'])