add function to query if RLC bearer exists (the implementation)

lib/include/srslte/upper/rlc.h

@@ -90,6 +90,7 @@ public:
   void del_bearer(uint32_t lcid);
   void del_bearer_mrb(uint32_t lcid);
   void change_lcid(uint32_t old_lcid, uint32_t new_lcid);
+  bool has_bearer(uint32_t lcid);
 
 private:
   void reset_metrics(); 

lib/src/upper/rlc.cc

@@ -571,6 +571,15 @@ exit:
 }
 
 
+bool rlc::has_bearer(uint32_t lcid)
+{
+  pthread_rwlock_rdlock(&rwlock);
+  bool ret = valid_lcid(lcid);
+  pthread_rwlock_unlock(&rwlock);
+  return ret;
+}
+
+
 /*******************************************************************************
   Helpers (Lock must be hold when calling those)
 *******************************************************************************/