Support fully direct request/responses (#9455)

Co-authored-by: Ben Meadors <benmmeadors@gmail.com>

src/mesh/ReliableRouter.cpp

@@ -17,12 +17,6 @@
 ErrorCode ReliableRouter::send(meshtastic_MeshPacket *p)
 {
     if (p->want_ack) {
-        // If someone asks for acks on broadcast, we need the hop limit to be at least one, so that first node that receives our
-        // message will rebroadcast.  But asking for hop_limit 0 in that context means the client app has no preference on hop
-        // counts and we want this message to get through the whole mesh, so use the default.
-        if (p->hop_limit == 0) {
-            p->hop_limit = Default::getConfiguredOrDefaultHopLimit(config.lora.hop_limit);
-        }
         DEBUG_HEAP_BEFORE;
         auto copy = packetPool.allocCopy(*p);
         DEBUG_HEAP_AFTER("ReliableRouter::send", copy);

src/mesh/Router.cpp

@@ -266,6 +266,13 @@ ErrorCode Router::sendLocal(meshtastic_MeshPacket *p, RxSource src)
             }
         }
 
+        // If someone asks for acks on broadcast, we need the hop limit to be at least one, so that first node that receives our
+        // message will rebroadcast.  But asking for hop_limit 0 in that context means the client app has no preference on hop
+        // counts and we want this message to get through the whole mesh, so use the default.
+        if (src == RX_SRC_USER && p->want_ack && p->hop_limit == 0) {
+            p->hop_limit = Default::getConfiguredOrDefaultHopLimit(config.lora.hop_limit);
+        }
+
         return send(p);
     }
 }

src/modules/RoutingModule.cpp

@@ -67,6 +67,8 @@ uint8_t RoutingModule::getHopLimitForResponse(const meshtastic_MeshPacket &mp)
 #if !(EVENTMODE)             // This falls through to the default.
             return hopsUsed; // If the request used more hops than the limit, use the same amount of hops
 #endif
+        } else if (mp.hop_start == 0) {
+            return 0; // The requesting node wanted 0 hops, so the response also uses a direct/local path.
         } else if ((uint8_t)(hopsUsed + 2) < config.lora.hop_limit) {
             return hopsUsed + 2; // Use only the amount of hops needed with some margin as the way back may be different
         }