Set last byte to 0xFF if it ended at 0x00

As per an idea of @S5NC

src/mesh/NextHopRouter.cpp

@@ -19,7 +19,7 @@ ErrorCode NextHopRouter::send(meshtastic_MeshPacket *p)
 bool NextHopRouter::shouldFilterReceived(const meshtastic_MeshPacket *p)
 {
     if (wasSeenRecently(p)) { // Note: this will also add a recent packet record
-        if (p->next_hop == (uint8_t)(getNodeNum() & 0xFF)) {
+        if (p->next_hop == nodeDB.getLastByteOfNodeNum(getNodeNum())) {
             LOG_DEBUG("Ignoring incoming msg, because we've already seen it.\n");
         } else {
             LOG_DEBUG("Ignoring incoming msg, because we've already seen it and cancel any outgoing packets.\n");
@@ -51,7 +51,7 @@ void NextHopRouter::sniffReceived(const meshtastic_MeshPacket *p, const meshtast
 
     if (config.device.role != meshtastic_Config_DeviceConfig_Role_CLIENT_MUTE) {
         if ((p->to != getNodeNum()) && (getFrom(p) != getNodeNum())) {
-            if (p->next_hop == (uint8_t)(getNodeNum() & 0xFF)) {
+            if (p->next_hop == nodeDB.getLastByteOfNodeNum(getNodeNum())) {
                 meshtastic_MeshPacket *tosend = packetPool.allocCopy(*p); // keep a copy because we will be sending it
                 LOG_INFO("Relaying received next-hop message coming from %x\n", p->relay_node);
 

src/mesh/NodeDB.cpp

@@ -824,10 +824,10 @@ void NodeDB::updateFrom(const meshtastic_MeshPacket &mp)
 
         // If this packet didn't travel any hops, then it was sent directly to us, so we know what to use as next hop to this node
         if (mp.original_hop_limit == mp.hop_limit) {
-            info->next_hop = (uint8_t)(mp.from & 0xFF);
+            info->next_hop = getLastByteOfNodeNum(mp.from);
         } else if (mp.relay_node && (mp.original_hop_limit - mp.hop_limit == 1)) {
             // This packet traveled one hop, so we can use the relay_node as next_hop
-            info->next_hop = (uint8_t)(mp.relay_node & 0xFF);
+            info->next_hop = getLastByteOfNodeNum(mp.relay_node);
         }
     }
 }

src/mesh/NodeDB.h

@@ -91,6 +91,9 @@ class NodeDB
     /// @return our node number
     NodeNum getNodeNum() { return myNodeInfo.my_node_num; }
 
+    // @return last byte of a NodeNum, 0xFF if it ended at 0x00
+    uint8_t getLastByteOfNodeNum(NodeNum num) { return (uint8_t)((num & 0xFF) ? (num & 0xFF) : 0xFF); }
+
     /// if returns false, that means our node should send a DenyNodeNum response.  If true, we think the number is okay for use
     // bool handleWantNodeNum(NodeNum n);
 

src/mesh/Router.cpp

@@ -241,10 +241,10 @@ ErrorCode Router::send(meshtastic_MeshPacket *p)
     p->from = getFrom(p);
 
     // If we are the original transmitter, set the original hop limit
-    if (p->from == nodeDB.getNodeNum())
+    if (p->from == getNodeNum())
         p->original_hop_limit = config.lora.hop_limit ? config.lora.hop_limit : HOP_RELIABLE;
 
-    p->relay_node = (uint8_t)(getNodeNum() & 0xFF); // set the current relayer to us
+    p->relay_node = nodeDB.getLastByteOfNodeNum(getNodeNum()); // set the relayer to us
 
     // If the packet hasn't yet been encrypted, do so now (it might already be encrypted if we are just forwarding it)
 

src/modules/NeighborInfoModule.cpp

@@ -161,7 +161,7 @@ size_t NeighborInfoModule::cleanUpNeighbors()
             // Clear all next hops of nodes that had this neighbor as next hop
             for (unsigned int j = 0; j < nodeDB.getNumMeshNodes(); j++) {
                 meshtastic_NodeInfoLite *node = nodeDB.getMeshNodeByIndex(j);
-                if (node->next_hop == (uint8_t)(neighbors[index].node_id & 0xFF)) {
+                if (node->next_hop == nodeDB.getLastByteOfNodeNum(neighbors[index].node_id)) {
                     node->next_hop = 0;
                 }
             }
@@ -251,7 +251,7 @@ void NeighborInfoModule::updateNextHops(meshtastic_NeighborInfo *np)
     meshtastic_NodeInfoLite *currentNode = nodeDB.getMeshNode(np->node_id);
     // Check if the sender of this neighborInfo packet is a neighbor of ourselves
     if (currentNode && isANeighbor(np->node_id)) {
-        currentNode->next_hop = (uint8_t)(np->node_id & 0xFF); // Set the next hop to the sender of this packet
+        currentNode->next_hop = nodeDB.getLastByteOfNodeNum(np->node_id); // Set the next hop to the sender of this packet
         for (uint8_t i = 0; i < np->neighbors_count; i++) {
             if (isANeighbor(np->neighbors[i].node_id))
                 continue; // This node is a neighbor of ourselves
@@ -259,7 +259,7 @@ void NeighborInfoModule::updateNextHops(meshtastic_NeighborInfo *np)
             meshtastic_NodeInfoLite *neighborOfCurrentNode = nodeDB.getMeshNode(np->neighbors[i].node_id);
             // Update next hop of this node to the sender of this packet, because it is the most recent neighbor
             if (neighborOfCurrentNode)
-                neighborOfCurrentNode->next_hop = (uint8_t)(currentNode->num & 0xFF);
+                neighborOfCurrentNode->next_hop = nodeDB.getLastByteOfNodeNum(currentNode->num);
         }
     } else if (currentNode) { // Sender is not a neighbor
         // Find common neighbors and use the most recent as next hop to this node
@@ -270,7 +270,7 @@ void NeighborInfoModule::updateNextHops(meshtastic_NeighborInfo *np)
             if (neighborOfCurrentNode && isANeighbor(neighborOfCurrentNode->num)) {
                 // This neighbor was heard more recently than the current next hop
                 if (neighborOfCurrentNode->last_heard > maxLastHeard) {
-                    currentNode->next_hop = (uint8_t)(neighborOfCurrentNode->num & 0xFF);
+                    currentNode->next_hop = nodeDB.getLastByteOfNodeNum(neighborOfCurrentNode->num);
                     maxLastHeard = neighborOfCurrentNode->last_heard;
                     LOG_DEBUG("More recent node found, so update next_hop of %x to %x\n", currentNode->num,
                               neighborOfCurrentNode->num);