commando: add stress test, fix memleak report.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

plugins/commando.c

@@ -452,8 +452,11 @@ static void handle_incmd(struct node_id *peer,
 
 	incmd = find_commando(incoming_commands, peer, NULL);
 	/* Don't let them buffer multiple commands: discard old. */
-	if (incmd && incmd->id != idnum)
+	if (incmd && incmd->id != idnum) {
+		plugin_log(plugin, LOG_DBG, "New cmd from %s, replacing old",
+			   node_id_to_hexstr(tmpctx, peer));
 		incmd = tal_free(incmd);
+	}
 
 	if (!incmd) {
 		incmd = tal(plugin, struct commando);
@@ -705,6 +708,7 @@ static struct command_result *json_commando(struct command *cmd,
 	tal_free(peer);
 	tal_free(method);
 	tal_free(cparams);
+	tal_free(rune);
 
 	return send_more_cmd(cmd, NULL, NULL, outgoing);
 }

tests/test_plugin.py

@@ -2804,3 +2804,36 @@ def test_commando_rune(node_factory):
                              'rune': rune['rune'],
                              'method': cmd,
                              'params': params})
+
+
+@pytest.mark.slow_test
+def test_commando_stress(node_factory, executor):
+    """Stress test to slam commando with many large queries"""
+    nodes = node_factory.get_nodes(5)
+
+    rune = nodes[0].rpc.commando_rune()['rune']
+    for n in nodes[1:]:
+        n.connect(nodes[0])
+
+    futs = []
+    for i in range(1000):
+        node = random.choice(nodes[1:])
+        futs.append(executor.submit(node.rpc.call, method='commando',
+                                    payload={'peer_id': nodes[0].info['id'],
+                                             'rune': rune,
+                                             'method': 'invoice',
+                                             'params': {'amount_msat': 'any',
+                                                        'label': 'label{}'.format(i),
+                                                        'description': 'A' * 200000,
+                                                        'deschashonly': True}}))
+    discards = 0
+    for f in futs:
+        try:
+            f.result(TIMEOUT)
+        except RpcError as e:
+            assert(e.error['code'] == 0x4c50)
+            assert(e.error['message'] == "Invalid JSON")
+            discards += 1
+
+    # Should have exactly one discard msg from each discard
+    nodes[0].daemon.wait_for_logs([r"New cmd from .*, replacing old"] * discards)