jsonrpc: Make an explicit jsonrpc struct

This wraps the listener, a separate log and the registered
commands. This is mainly needed once we dynamically add
sjson_command`s to the JSON-RPC.

lightningd/jsonrpc.c

@@ -77,6 +77,18 @@ struct json_connection {
 	struct json_stream **js_arr;
 };
 
+/**
+ * `jsonrpc` encapsulates the entire state of the JSON-RPC interface,
+ * including a list of methods that the interface supports (can be
+ * appended dynamically, e.g., for plugins, and logs. It also serves
+ * as a convenient `tal`-parent for all JSON-RPC related allocations.
+ */
+struct jsonrpc {
+	struct io_listener *rpc_listener;
+	struct json_command **commands;
+	struct log *log;
+};
+
 /* The command itself usually owns the stream, because jcon may get closed.
  * The command transfers ownership once it's done though. */
 static struct json_stream *jcon_new_json_stream(const tal_t *ctx,
@@ -292,10 +304,9 @@ static void json_add_help_command(struct command *cmd,
 static void json_help(struct command *cmd,
 		      const char *buffer, const jsmntok_t *params)
 {
-	unsigned int i;
 	struct json_stream *response;
-	struct json_command **cmdlist = get_cmdlist();
 	const jsmntok_t *cmdtok;
+	struct json_command **commands = cmd->ld->jsonrpc->commands;
 
 	if (!param(cmd, buffer, params,
 		   p_opt("command", json_tok_tok, &cmdtok),
@@ -303,10 +314,10 @@ static void json_help(struct command *cmd,
 		return;
 
 	if (cmdtok) {
-		for (i = 0; i < num_cmdlist; i++) {
-			if (json_tok_streq(buffer, cmdtok, cmdlist[i]->name)) {
+		for (size_t i = 0; i < tal_count(commands); i++) {
+			if (json_tok_streq(buffer, cmdtok, commands[i]->name)) {
 				response = json_stream_success(cmd);
-				json_add_help_command(cmd, response, cmdlist[i]);
+				json_add_help_command(cmd, response, commands[i]);
 				goto done;
 			}
 		}
@@ -320,8 +331,8 @@ static void json_help(struct command *cmd,
 	response = json_stream_success(cmd);
 	json_object_start(response, NULL);
 	json_array_start(response, "help");
-	for (i = 0; i < num_cmdlist; i++) {
-		json_add_help_command(cmd, response, cmdlist[i]);
+	for (size_t i=0; i<tal_count(commands); i++) {
+		json_add_help_command(cmd, response, commands[i]);
 	}
 	json_array_end(response);
 	json_object_end(response);
@@ -330,17 +341,17 @@ done:
 	command_success(cmd, response);
 }
 
-static const struct json_command *find_cmd(const char *buffer,
+static const struct json_command *find_cmd(const struct jsonrpc *rpc,
+					   const char *buffer,
 					   const jsmntok_t *tok)
 {
-	unsigned int i;
-	struct json_command **cmdlist = get_cmdlist();
+	struct json_command **commands = rpc->commands;
 
-	/* cmdlist[i]->name can be NULL in test code. */
-	for (i = 0; i < num_cmdlist; i++)
-		if (cmdlist[i]->name
-		    && json_tok_streq(buffer, tok, cmdlist[i]->name))
-			return cmdlist[i];
+	/* commands[i]->name can be NULL in test code. */
+	for (size_t i=0; i<tal_count(commands); i++)
+          if (commands[i]->name &&
+              json_tok_streq(buffer, tok, commands[i]->name))
+            return commands[i];
 	return NULL;
 }
 
@@ -516,9 +527,9 @@ static void parse_request(struct json_connection *jcon, const jsmntok_t tok[])
 		return;
 	}
 
-	/* This is a convenient tal parent for duration of command
-	 * (which may outlive the conn!). */
-	c = tal(jcon->ld->rpc_listener, struct command);
+	/* Allocate the command off of the `jsonrpc` object and not
+	 * the connection since the command may outlive `conn`. */
+	c = tal(jcon->ld->jsonrpc, struct command);
 	c->jcon = jcon;
 	c->ld = jcon->ld;
 	c->pending = false;
@@ -543,8 +554,8 @@ static void parse_request(struct json_connection *jcon, const jsmntok_t tok[])
 		return;
 	}
 
-	c->json_cmd = find_cmd(jcon->buffer, method);
-	if (!c->json_cmd) {
+        c->json_cmd = find_cmd(jcon->ld->jsonrpc, jcon->buffer, method);
+        if (!c->json_cmd) {
 		command_fail(c, JSONRPC2_METHOD_NOT_FOUND,
 			     "Unknown command '%.*s'",
 			     method->end - method->start,
@@ -713,10 +724,41 @@ static struct io_plan *incoming_jcon_connected(struct io_conn *conn,
 	return jcon_connected(notleak(conn), ld);
 }
 
-void setup_jsonrpc(struct lightningd *ld, const char *rpc_filename)
+bool jsonrpc_command_add(struct jsonrpc *rpc, struct json_command *command)
+{
+	size_t count = tal_count(rpc->commands);
+
+	/* Check that we don't clobber a method */
+	for (size_t i = 0; i < count; i++)
+		if (rpc->commands[i] != NULL &&
+		    streq(rpc->commands[i]->name, command->name))
+			return false;
+
+	*tal_arr_expand(&rpc->commands) = command;
+	return true;
+}
+
+static struct jsonrpc *jsonrpc_new(const tal_t *ctx, struct lightningd *ld, int fd)
+{
+	struct jsonrpc *jsonrpc = tal(ctx, struct jsonrpc);
+	struct json_command **commands = get_cmdlist();
+
+	jsonrpc->commands = tal_arr(jsonrpc, struct json_command *, 0);
+	jsonrpc->log = new_log(jsonrpc, ld->log_book, "jsonrpc");
+	for (size_t i=0; i<num_cmdlist; i++) {
+		jsonrpc_command_add(jsonrpc, commands[i]);
+	}
+	jsonrpc->rpc_listener = io_new_listener(
+		ld->rpc_filename, fd, incoming_jcon_connected, ld);
+	log_debug(jsonrpc->log, "Listening on '%s'", ld->rpc_filename);
+	return jsonrpc;
+}
+
+struct jsonrpc *setup_jsonrpc(struct lightningd *ld)
 {
 	struct sockaddr_un addr;
 	int fd, old_umask;
+	const char *rpc_filename = ld->rpc_filename;
 
 	if (streq(rpc_filename, "/dev/tty")) {
 		fd = open(rpc_filename, O_RDWR);
@@ -724,7 +766,7 @@ void setup_jsonrpc(struct lightningd *ld, const char *rpc_filename)
 			err(1, "Opening %s", rpc_filename);
 		/* Technically this is a leak, but there's only one */
 		notleak(io_new_conn(ld, fd, jcon_connected, ld));
-		return;
+		return jsonrpc_new(ld, ld, fd);
 	}
 
 	fd = socket(AF_UNIX, SOCK_STREAM, 0);
@@ -750,8 +792,7 @@ void setup_jsonrpc(struct lightningd *ld, const char *rpc_filename)
 	if (listen(fd, 1) != 0)
 		err(1, "Listening on '%s'", rpc_filename);
 
-	log_debug(ld->log, "Listening on '%s'", rpc_filename);
-	ld->rpc_listener = io_new_listener(ld->rpc_filename, fd, incoming_jcon_connected, ld);
+	return jsonrpc_new(ld, ld, fd);
 }
 
 /**

lightningd/jsonrpc.h

@@ -93,7 +93,15 @@ void PRINTF_FMT(3, 4) command_fail(struct command *cmd, int code,
 void command_still_pending(struct command *cmd);
 
 /* For initialization */
-void setup_jsonrpc(struct lightningd *ld, const char *rpc_filename);
+struct jsonrpc *setup_jsonrpc(struct lightningd *ld);
+
+/**
+ * Add a new command/method to the JSON-RPC interface.
+ *
+ * Returns true if the command was added correctly, false if adding
+ * this would clobber a command name.
+ */
+bool jsonrpc_command_add(struct jsonrpc *rpc, struct json_command *command);
 
 AUTODATA_TYPE(json_command, struct json_command);
 #endif /* LIGHTNING_LIGHTNINGD_JSONRPC_H */

lightningd/lightningd.c

@@ -695,7 +695,7 @@ int main(int argc, char *argv[])
 
 	/*~ Create RPC socket: now lightning-cli can send us JSON RPC commands
 	 *  over a UNIX domain socket specified by `ld->rpc_filename`. */
-	setup_jsonrpc(ld, ld->rpc_filename);
+	ld->jsonrpc = setup_jsonrpc(ld);
 
 	/*~ We defer --daemon until we've completed most initialization: that
 	 *  way we'll exit with an error rather than silently exiting 0, then
@@ -778,7 +778,7 @@ int main(int argc, char *argv[])
 	 * it might actually be touching the DB in some destructors, e.g.,
 	 * unreserving UTXOs (see #1737) */
 	db_begin_transaction(ld->wallet->db);
-	tal_free(ld->rpc_listener);
+	tal_free(ld->jsonrpc);
 	db_commit_transaction(ld->wallet->db);
 
 	remove(ld->pidfile);

lightningd/lightningd.h

@@ -84,10 +84,11 @@ struct lightningd {
 	/* Location of the RPC socket. */
 	char *rpc_filename;
 
-	/* The listener for the RPC socket. Can be shut down separately from the
-	 * rest of the daemon to allow a clean shutdown, which frees all pending
-	 * cmds in a DB transaction. */
-	struct io_listener *rpc_listener;
+	/* The root of the jsonrpc interface. Can be shut down
+	 * separately from the rest of the daemon to allow a clean
+	 * shutdown, which frees all pending cmds in a DB
+	 * transaction. */
+	struct jsonrpc *jsonrpc;
 
 	/* Configuration file name */
 	char *config_filename;

lightningd/test/run-find_my_abspath.c

@@ -138,7 +138,7 @@ void register_opts(struct lightningd *ld UNNEEDED)
 void setup_color_and_alias(struct lightningd *ld UNNEEDED)
 { fprintf(stderr, "setup_color_and_alias called!\n"); abort(); }
 /* Generated stub for setup_jsonrpc */
-void setup_jsonrpc(struct lightningd *ld UNNEEDED, const char *rpc_filename UNNEEDED)
+struct jsonrpc *setup_jsonrpc(struct lightningd *ld UNNEEDED)
 { fprintf(stderr, "setup_jsonrpc called!\n"); abort(); }
 /* Generated stub for setup_topology */
 void setup_topology(struct chain_topology *topology UNNEEDED, struct timers *timers UNNEEDED,