daemon: dev-output command.

Useful for controlling conversations between two nodes, by
blocking one's output.

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

daemon/json.c

@@ -114,6 +114,23 @@ bool json_tok_is_null(const char *buffer, const jsmntok_t *tok)
 	return buffer[tok->start] == 'n';
 }
 
+bool json_tok_bool(const char *buffer, const jsmntok_t *tok, bool *b)
+{
+	if (tok->type != JSMN_PRIMITIVE)
+		return false;
+	if (tok->end - tok->start == strlen("true")
+	    && memcmp(buffer + tok->start, "true", strlen("true")) == 0) {
+		*b = true;
+		return true;
+	}
+	if (tok->end - tok->start == strlen("false")
+	    && memcmp(buffer + tok->start, "false", strlen("false")) == 0) {
+		*b = false;
+		return true;
+	}
+	return false;
+}
+
 const jsmntok_t *json_next(const jsmntok_t *tok)
 {
 	const jsmntok_t *t;

daemon/json.h

@@ -32,6 +32,9 @@ bool json_tok_u64(const char *buffer, const jsmntok_t *tok,
 bool json_tok_bitcoin_amount(const char *buffer, const jsmntok_t *tok,
 			     uint64_t *satoshi);
 
+/* Extract boolean this (must be a true or false) */
+bool json_tok_bool(const char *buffer, const jsmntok_t *tok, bool *b);
+
 /* Is this the null primitive? */
 bool json_tok_is_null(const char *buffer, const jsmntok_t *tok);
 

daemon/jsonrpc.c

@@ -262,6 +262,7 @@ static const struct json_command *cmdlist[] = {
 	&crash_command,
 	&disconnect_command,
 	&signcommit_command,
+	&output_command,
 };
 
 static void json_help(struct command *cmd,

daemon/jsonrpc.h

@@ -67,4 +67,5 @@ extern const struct json_command close_command;
 extern const struct json_command newaddr_command;
 extern const struct json_command disconnect_command;
 extern const struct json_command signcommit_command;
+extern const struct json_command output_command;
 #endif /* LIGHTNING_DAEMON_JSONRPC_H */

daemon/lightning-cli.c

@@ -96,8 +96,11 @@ int main(int argc, char *argv[])
 		      method, idstr);
 
 	for (i = 2; i < argc; i++) {
-		/* Numbers are left unquoted, and quoted things left alone. */
+		/* Numbers and bools are left unquoted,
+		 * and quoted things left alone. */
 		if (strspn(argv[i], "0123456789") == strlen(argv[i])
+		    || streq(argv[i], "true")
+		    || streq(argv[i], "false")
 		    || argv[i][0] == '"')
 			tal_append_fmt(&cmd, "%s", argv[i]);
 		else

daemon/peer.c

@@ -675,9 +675,9 @@ static struct io_plan *pkt_out(struct io_conn *conn, struct peer *peer)
 	Pkt *out;
 	size_t n = tal_count(peer->outpkt);
 
-	if (peer->fake_close)
+	if (peer->fake_close || !peer->output_enabled)
 		return io_out_wait(conn, peer, pkt_out, peer);
-	
+
 	if (n == 0) {
 		/* We close the connection once we've sent everything. */
 		if (peer->cond == PEER_CLOSED)
@@ -861,6 +861,7 @@ static struct peer *new_peer(struct lightningd_state *dstate,
 	 * immediately so don't make peer a parent. */
 	peer->conn = conn;
 	peer->fake_close = false;
+	peer->output_enabled = true;
 	io_set_finish(conn, peer_disconnect, peer);
 	
 	peer->local.offer_anchor = offer_anchor;
@@ -2911,6 +2912,54 @@ static void json_signcommit(struct command *cmd,
 	command_success(cmd, response);
 }
 
+static void json_output(struct command *cmd,
+			const char *buffer, const jsmntok_t *params)
+{
+	struct peer *peer;
+	jsmntok_t *peeridtok, *enabletok;
+	bool enable;
+
+	if (!json_get_params(buffer, params,
+			     "peerid", &peeridtok,
+			     "enable", &enabletok,
+			     NULL)) {
+		command_fail(cmd, "Need peerid and enable");
+		return;
+	}
+
+	peer = find_peer(cmd->dstate, buffer, peeridtok);
+	if (!peer) {
+		command_fail(cmd, "Could not find peer with that peerid");
+		return;
+	}
+
+	if (!peer->conn) {
+		command_fail(cmd, "Peer is already disconnected");
+		return;
+	}
+
+	if (!json_tok_bool(buffer, enabletok, &enable)) {
+		command_fail(cmd, "enable must be true or false");
+		return;
+	}
+
+	log_debug(peer->log, "dev-output: output %s",
+		  enable ? "enabled" : "disabled");
+	peer->output_enabled = enable;
+
+	/* Flush any outstanding output */
+	if (peer->output_enabled)
+		io_wake(peer);
+	
+	command_success(cmd, null_response(cmd));
+}
+const struct json_command output_command = {
+	"dev-output",
+	json_output,
+	"Enable/disable any messages to peer {peerid} depending on {enable}",
+	"Returns an empty result on success"
+};
+
 const struct json_command disconnect_command = {
 	"dev-disconnect",
 	json_disconnect,

daemon/peer.h

@@ -223,7 +223,8 @@ struct peer {
 
 	/* For testing. */
 	bool fake_close;
-	
+	bool output_enabled;
+
 	/* Stuff we have in common. */
 	struct peer_visible_state local, remote;
 };