Plugin: support extra args to "start".

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Changelog-Added: Plugins: `start` command can now take plugin-specific parameters.

contrib/pyln-client/pyln/client/lightning.py

@@ -1024,14 +1024,15 @@ def ping(self, peer_id, length=128, pongbytes=128):
         }
         return self.call("ping", payload)
 
-    def plugin_start(self, plugin):
+    def plugin_start(self, plugin, **kwargs):
         """
         Adds a plugin to lightningd.
         """
         payload = {
             "subcommand": "start",
-            "plugin": plugin
+            "plugin": plugin,
         }
+        payload.update({k: v for k, v in kwargs.items()})
         return self.call("plugin", payload)
 
     def plugin_startdir(self, directory):

doc/lightning-plugin.7.md

@@ -15,9 +15,10 @@ restart lightningd. It takes 1 to 3 parameters: a command
 optionally one or two parameters which describes the plugin on which the
 action has to be taken.
 
-The *start* command takes a path as the first parameter and will load the
-plugin available from this path. It will wait for the plugin to complete
-the handshake with `lightningd` for 20 seconds at the most.
+The *start* command takes a path as the first parameter and will load
+the plugin available from this path.  Any additional parameters are
+passed to the plugin. It will wait for the plugin to complete the
+handshake with `lightningd` for 20 seconds at the most.
 
 The *stop* command takes a plugin name as parameter. It will kill and
 unload the specified plugin.

lightningd/options.c

@@ -348,7 +348,7 @@ static char *opt_add_plugin(const char *arg, struct lightningd *ld)
 		log_info(ld->log, "%s: disabled via disable-plugin", arg);
 		return NULL;
 	}
-	plugin_register(ld->plugins, arg, NULL, false);
+	plugin_register(ld->plugins, arg, NULL, false, NULL, NULL);
 	return NULL;
 }
 
@@ -375,7 +375,7 @@ static char *opt_important_plugin(const char *arg, struct lightningd *ld)
 		log_info(ld->log, "%s: disabled via disable-plugin", arg);
 		return NULL;
 	}
-	plugin_register(ld->plugins, arg, NULL, true);
+	plugin_register(ld->plugins, arg, NULL, true, NULL, NULL);
 	return NULL;
 }
 

lightningd/plugin.c

@@ -1,5 +1,6 @@
 #include <ccan/array_size/array_size.h>
 #include <ccan/list/list.h>
+#include <ccan/mem/mem.h>
 #include <ccan/opt/opt.h>
 #include <ccan/tal/str/str.h>
 #include <ccan/utf8/utf8.h>
@@ -174,7 +175,9 @@ static void destroy_plugin(struct plugin *p)
 }
 
 struct plugin *plugin_register(struct plugins *plugins, const char* path TAKES,
-			       struct command *start_cmd, bool important)
+			       struct command *start_cmd, bool important,
+			       const char *parambuf STEALS,
+			       const jsmntok_t *params STEALS)
 {
 	struct plugin *p, *p_temp;
 
@@ -212,6 +215,8 @@ struct plugin *plugin_register(struct plugins *plugins, const char* path TAKES,
 	list_head_init(&p->pending_rpccalls);
 
 	p->important = important;
+	p->parambuf = tal_steal(p, parambuf);
+	p->params = tal_steal(p, params);
 	return p;
 }
 
@@ -1154,6 +1159,48 @@ static const char *plugin_hooks_add(struct plugin *plugin, const char *buffer,
 	return NULL;
 }
 
+static struct plugin_opt *plugin_opt_find(struct plugin *plugin,
+					  const char *name, size_t namelen)
+{
+	struct plugin_opt *opt;
+
+	list_for_each(&plugin->plugin_opts, opt, list) {
+		/* Trim the `--` that we added before */
+		if (memeqstr(name, namelen, opt->name + 2))
+			return opt;
+	}
+	return NULL;
+}
+
+/* start command might have included plugin-specific parameters */
+static const char *plugin_add_params(struct plugin *plugin)
+{
+	size_t i;
+	const jsmntok_t *t;
+
+	if (!plugin->params)
+		return NULL;
+
+	json_for_each_obj(i, t, plugin->params) {
+		struct plugin_opt *popt;
+		char *err;
+
+		popt = plugin_opt_find(plugin,
+				       plugin->parambuf + t->start,
+				       t->end - t->start);
+		if (!popt) {
+			return tal_fmt(plugin, "unknown parameter %.*s",
+				       json_tok_full_len(t),
+				       json_tok_full(plugin->parambuf, t));
+		}
+		err = plugin_opt_set(json_strdup(tmpctx, plugin->parambuf,
+						 t + 1), popt);
+		if (err)
+			return err;
+	}
+	return NULL;
+}
+
 static void plugin_manifest_timeout(struct plugin *plugin)
 {
 	bool startup = plugin->plugins->startup;
@@ -1243,6 +1290,8 @@ static const char *plugin_parse_getmanifest_response(const char *buffer,
 		err = plugin_subscriptions_add(plugin, buffer, resulttok);
 	if (!err)
 		err = plugin_hooks_add(plugin, buffer, resulttok);
+	if (!err)
+		err = plugin_add_params(plugin);
 
 	plugin->plugin_state = NEEDS_INIT;
 	return err;
@@ -1360,7 +1409,8 @@ char *add_plugin_dir(struct plugins *plugins, const char *dir, bool error_ok)
 			log_info(plugins->log, "%s: disabled via disable-plugin",
 				 fullpath);
 		} else {
-			p = plugin_register(plugins, fullpath, NULL, false);
+			p = plugin_register(plugins, fullpath, NULL, false,
+					    NULL, NULL);
 			if (!p && !error_ok)
 				return tal_fmt(NULL, "Failed to register %s: %s",
 				               fullpath, strerror(errno));
@@ -1807,7 +1857,8 @@ void plugins_set_builtin_plugins_dir(struct plugins *plugins,
 				take(path_join(NULL, dir,
 					       list_of_builtin_plugins[i])),
 				NULL,
-				/* important = */ true);
+				/* important = */ true,
+				NULL, NULL);
 }
 
 struct plugin_destroyed {

lightningd/plugin.h

@@ -88,6 +88,10 @@ struct plugin {
 	/* If set, the plugin is so important that if it terminates early,
 	 * C-lightning should terminate as well.  */
 	bool important;
+
+	/* Parameters for dynamically-started plugins. */
+	const char *parambuf;
+	const jsmntok_t *params;
 };
 
 /**
@@ -200,14 +204,19 @@ void plugins_free(struct plugins *plugins);
  * @param path: The path of the executable for this plugin
  * @param start_cmd: The optional JSON command which caused this.
  * @param important: The plugin is important.
+ * @param parambuf: NULL, or the JSON buffer for extra parameters.
+ * @param params: NULL, or the tokens for extra parameters.
  *
  * If @start_cmd, then plugin_cmd_killed or plugin_cmd_succeeded will be called
  * on it eventually.
  */
 struct plugin *plugin_register(struct plugins *plugins,
 			       const char* path TAKES,
 			       struct command *start_cmd,
-			       bool important);
+			       bool important,
+			       const char *parambuf STEALS,
+			       const jsmntok_t *params STEALS);
+
 
 /**
  * Returns true if the provided name matches a plugin command

lightningd/plugin_control.c

@@ -56,9 +56,10 @@ struct command_result *plugin_cmd_all_complete(struct plugins *plugins,
  * will give a result 60 seconds later at the most (once init completes).
  */
 static struct command_result *
-plugin_dynamic_start(struct command *cmd, const char *plugin_path)
+plugin_dynamic_start(struct command *cmd, const char *plugin_path,
+		     const char *buffer, const jsmntok_t *params)
 {
-	struct plugin *p = plugin_register(cmd->ld->plugins, plugin_path, cmd, false);
+	struct plugin *p = plugin_register(cmd->ld->plugins, plugin_path, cmd, false, buffer, params);
 	const char *err;
 
 	if (!p)
@@ -173,15 +174,35 @@ static struct command_result *json_plugin_control(struct command *cmd,
 		return plugin_dynamic_stop(cmd, plugin_name);
 	} else if (streq(subcmd, "start")) {
 		const char *plugin_path;
+		jsmntok_t *mod_params;
 
 		if (!param(cmd, buffer, params,
 			   p_req("subcommand", param_ignore, cmd),
 			   p_req("plugin", param_string, &plugin_path),
+			   p_opt_any(),
 			   NULL))
 			return command_param_failed();
 
+		/* Manually parse any remaining options (only for objects,
+		 * since plugin options must be explicitly named!). */
+		if (params->type == JSMN_ARRAY) {
+			if (params->size != 2)
+				return command_fail(cmd, JSONRPC2_INVALID_PARAMS,
+						    "Extra parameters must be in object");
+			mod_params = NULL;
+		} else {
+			mod_params = json_tok_copy(cmd, params);
+
+			json_tok_remove(&mod_params, mod_params,
+					json_get_member(buffer, mod_params,
+							"subcommand") - 1, 1);
+			json_tok_remove(&mod_params, mod_params,
+					json_get_member(buffer, mod_params,
+							"plugin") - 1, 1);
+		}
 		if (access(plugin_path, X_OK) == 0)
-			return plugin_dynamic_start(cmd, plugin_path);
+			return plugin_dynamic_start(cmd, plugin_path,
+						    buffer, mod_params);
 		else
 			return command_fail(cmd, JSONRPC2_INVALID_PARAMS,
 						   "%s is not executable: %s",

tests/test_plugin.py

@@ -2182,3 +2182,18 @@ def test_htlc_accepted_hook_failonion(node_factory):
     inv = l2.rpc.invoice(42, 'failonion000', '')['bolt11']
     with pytest.raises(RpcError):
         l1.rpc.pay(inv)
+
+
+def test_dynamic_args(node_factory):
+    plugin_path = os.path.join(os.getcwd(), 'contrib/plugins/helloworld.py')
+
+    l1 = node_factory.get_node()
+    l1.rpc.plugin_start(plugin_path, greeting='Test arg parsing')
+
+    assert l1.rpc.call("hello") == "Test arg parsing world"
+    plugin = only_one([p for p in l1.rpc.listconfigs()['plugins'] if p['path'] == plugin_path])
+    assert plugin['options']['greeting'] == 'Test arg parsing'
+
+    l1.rpc.plugin_stop(plugin_path)
+
+    assert [p for p in l1.rpc.listconfigs()['plugins'] if p['path'] == plugin_path] == []