fsm: Enforce FSM and FSM instance names are valid osmocom identifiers

Let's enforce that the names of FSMs and their instances are valid
osmocom identifiers.  This is important as the FSMs are automatically
exported via those names on the CTRL inteface, and we have to make sure
CTRL syntax actually permits them.

Change-Id: I9ef59432f43a3cdb94e4cbb0c44ac3f9b2aac0f2
diff --git a/src/fsm.c b/src/fsm.c
index d62fd79..3f8de9c 100644
--- a/src/fsm.c
+++ b/src/fsm.c
@@ -146,6 +146,10 @@
  */
 int osmo_fsm_register(struct osmo_fsm *fsm)
 {
+	if (!osmo_identifier_valid(fsm->name)) {
+		LOGP(DLGLOBAL, LOGL_ERROR, "Attempting to register FSM with illegal identifier '%s'\n", fsm->name);
+		return -EINVAL;
+	}
 	if (osmo_fsm_find_by_name(fsm->name))
 		return -EEXIST;
 	llist_add_tail(&fsm->list, &osmo_g_fsms);
@@ -206,8 +210,15 @@
 	fi->priv = priv;
 	fi->log_level = log_level;
 	osmo_timer_setup(&fi->timer, fsm_tmr_cb, fi);
-	if (id)
+	if (id) {
+		if (!osmo_identifier_valid(id)) {
+			LOGP(DLGLOBAL, LOGL_ERROR, "Attempting to allocate FSM instance of type '%s'"
+			     " with illegal identifier '%s'\n", fsm->name, id);
+			talloc_free(fi);
+			return NULL;
+		}
 		fi->id = talloc_strdup(fi, id);
+	}
 
 	if (!fsm_log_addr) {
 		if (id)