daemon: add dev-routefail command.

We're about to change the code so that if it can't route, it will fail
the HTLC.  The current low-level tests will hate this, so have a dev switch
to turn that off.

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

daemon/jsonrpc.c

@@ -265,6 +265,7 @@ static const struct json_command *cmdlist[] = {
 	&signcommit_command,
 	&output_command,
 	&add_route_command,
+	&routefail_command,
 };
 
 static void json_help(struct command *cmd,

daemon/jsonrpc.h

@@ -71,4 +71,5 @@ extern const struct json_command signcommit_command;
 extern const struct json_command output_command;
 extern const struct json_command accept_payment_command;
 extern const struct json_command add_route_command;
+extern const struct json_command routefail_command;
 #endif /* LIGHTNING_DAEMON_JSONRPC_H */

daemon/lightningd.c

@@ -204,6 +204,7 @@ static struct lightningd_state *lightningd_state(void)
 	list_head_init(&dstate->bitcoin_req);
 	list_head_init(&dstate->wallet);
 	list_head_init(&dstate->payments);
+	dstate->dev_never_routefail = false;
 	dstate->bitcoin_req_running = false;
 	dstate->nodes = empty_node_map(dstate);
 	return dstate;

daemon/lightningd.h

@@ -96,5 +96,8 @@ struct lightningd_state {
 
 	/* All known nodes. */
 	struct node_map *nodes;
+
+	/* For testing: don't fail if we can't route. */
+	bool dev_never_routefail;
 };
 #endif /* LIGHTNING_DAEMON_LIGHTNING_H */

daemon/routing.c

@@ -299,3 +299,35 @@ const struct json_command add_route_command = {
 	"Returns an empty result on success"
 };
 
+static void json_routefail(struct command *cmd,
+			   const char *buffer, const jsmntok_t *params)
+{
+	jsmntok_t *enabletok;
+	bool enable;
+
+	if (!json_get_params(buffer, params,
+			     "enable", &enabletok,
+			     NULL)) {
+		command_fail(cmd, "Need enable");
+		return;
+	}
+
+	if (!json_tok_bool(buffer, enabletok, &enable)) {
+		command_fail(cmd, "enable must be true or false");
+		return;
+	}
+
+	log_debug(cmd->dstate->base_log, "dev-routefail: routefail %s",
+		  enable ? "enabled" : "disabled");
+	cmd->dstate->dev_never_routefail = !enable;
+
+	command_success(cmd, null_response(cmd));
+}
+const struct json_command routefail_command = {
+	"dev-routefail",
+	json_routefail,
+	"FAIL htlcs that we can't route if {enable}",
+	"Returns an empty result on success"
+};
+
+