better hop selection fault tolerance

include/llarp/pathbuilder.h

@@ -33,7 +33,7 @@ struct llarp_pathbuild_job;
 typedef void (*llarp_pathbuilder_hook)(struct llarp_pathbuild_job*);
 // select hop function (user, nodedb, prevhop, result, hopnnumber) called in
 // logic thread
-typedef void (*llarp_pathbuilder_select_hop_func)(void*, struct llarp_nodedb*,
+typedef bool (*llarp_pathbuilder_select_hop_func)(void*, struct llarp_nodedb*,
                                                   struct llarp_rc*,
                                                   struct llarp_rc*, size_t);
 

include/llarp/pathset.hpp

@@ -98,12 +98,12 @@ namespace llarp
       SelectHop(llarp_nodedb* db, llarp_rc* prev, llarp_rc* cur,
                 size_t hop) = 0;
 
-      static void
+      static bool
       SelectHopCallback(void* user, llarp_nodedb* db, llarp_rc* prev,
                         llarp_rc* cur, size_t hopno)
       {
         PathSet* self = static_cast< PathSet* >(user);
-        self->SelectHop(db, prev, cur, hopno);
+        return self->SelectHop(db, prev, cur, hopno);
       }
 
      private:

llarp/pathbuilder.cpp

@@ -156,7 +156,12 @@ namespace llarp
     {
       llarp_rc* rc = &job->hops.hops[idx].router;
       llarp_rc_clear(rc);
-      job->selectHop(job->user, job->router->nodedb, prev, rc, idx);
+      if(!job->selectHop(job->user, job->router->nodedb, prev, rc, idx))
+      {
+        /// TODO: handle this failure properly
+        llarp::LogWarn("Failed to select hop ", idx);
+        return;
+      }
       prev = rc;
       ++idx;
     }