Initial version of NextHopRouter

src/modules/NeighborInfoModule.cpp

@@ -156,6 +156,17 @@ size_t NeighborInfoModule::cleanUpNeighbors()
     // Update the neighbor list
     for (uint i = 0; i < indices_to_remove.size(); i++) {
         int index = indices_to_remove[i];
+
+        if (config.lora.next_hop_routing) {
+            // 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 == neighbors[index].node_id) {
+                    node->next_hop = 0;
+                }
+            }
+        }
+
         LOG_DEBUG("Removing neighbor with node ID 0x%x\n", neighbors[index].node_id);
         for (int j = index; j < num_neighbors - 1; j++) {
             neighbors[j] = neighbors[j + 1];
@@ -205,6 +216,8 @@ bool NeighborInfoModule::handleReceivedProtobuf(const meshtastic_MeshPacket &mp,
     if (enabled) {
         printNeighborInfo("RECEIVED", np);
         updateNeighbors(mp, np);
+        if (config.lora.next_hop_routing)
+            updateNextHops(np);
     }
     // Allow others to handle this packet
     return false;
@@ -229,6 +242,54 @@ void NeighborInfoModule::updateLastSentById(meshtastic_MeshPacket *p)
         pb_encode_to_bytes(p->decoded.payload.bytes, sizeof(p->decoded.payload.bytes), &meshtastic_NeighborInfo_msg, updated);
 }
 
+/* Update the next hop for nodes in the database.
+ * Based on our own neighbors, and the neighbors of our neighbors.
+ */
+void NeighborInfoModule::updateNextHops(meshtastic_NeighborInfo *np)
+{
+    LOG_DEBUG("Updating next hops based on received NeighborInfo packet\n");
+    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 = 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
+
+            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 = currentNode->num;
+        }
+    } else if (currentNode) { // Sender is not a neighbor
+        // Find common neighbors and use the most recent as next hop to this node
+        meshtastic_NodeInfoLite *currentNextHop = nodeDB.getMeshNode(currentNode->next_hop);
+        uint32_t maxLastHeard = currentNextHop ? currentNextHop->last_heard : 0;
+        for (uint8_t i = 0; i < np->neighbors_count; i++) {
+            meshtastic_NodeInfoLite *neighborOfCurrentNode = nodeDB.getMeshNode(np->neighbors[i].node_id);
+            if (neighborOfCurrentNode && isANeighbor(neighborOfCurrentNode->num)) {
+                // This neighbor was heard more recently than the current next hop
+                if (neighborOfCurrentNode->last_heard > maxLastHeard) {
+                    currentNode->next_hop = 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);
+                }
+            }
+        }
+    }
+}
+
+bool NeighborInfoModule::isANeighbor(NodeNum node_id)
+{
+    for (int i = 0; i < *numNeighbors; i++) {
+        if (neighbors[i].node_id == node_id) {
+            return true;
+        }
+    }
+    return false;
+}
+
 void NeighborInfoModule::resetNeighbors()
 {
     *numNeighbors = 0;
@@ -308,4 +369,4 @@ bool NeighborInfoModule::saveProtoForModule()
     okay &= nodeDB.saveProto(neighborInfoConfigFile, meshtastic_NeighborInfo_size, &meshtastic_NeighborInfo_msg, &neighborState);
 
     return okay;
-}
+}

src/modules/NeighborInfoModule.h

@@ -20,8 +20,9 @@ class NeighborInfoModule : public ProtobufModule<meshtastic_NeighborInfo>, priva
 
     bool saveProtoForModule();
 
-    // Let FloodingRouter call updateLastSentById upon rebroadcasting a NeighborInfo packet
+    // Let FloodingRouter/NexthopRouter call updateLastSentById upon rebroadcasting a NeighborInfo packet
     friend class FloodingRouter;
+    friend class NextHopRouter;
 
   protected:
     // Note: this holds our local info.
@@ -70,6 +71,12 @@ class NeighborInfoModule : public ProtobufModule<meshtastic_NeighborInfo>, priva
     /* update a NeighborInfo packet with our NodeNum as last_sent_by_id */
     void updateLastSentById(meshtastic_MeshPacket *p);
 
+    /* update the next hop for nodes in the database */
+    void updateNextHops(meshtastic_NeighborInfo *np);
+
+    /* check if the given node number is a neighbor of us */
+    bool isANeighbor(NodeNum node_id);
+
     void loadProtoForModule();
 
     /* Does our periodic broadcast */

src/modules/TraceRouteModule.h

@@ -9,8 +9,9 @@ class TraceRouteModule : public ProtobufModule<meshtastic_RouteDiscovery>
   public:
     TraceRouteModule();
 
-    // Let FloodingRouter call updateRoute upon rebroadcasting a TraceRoute request
+    // Let FloodingRouter/NextHopRouter call updateRoute upon rebroadcasting a TraceRoute request
     friend class FloodingRouter;
+    friend class NextHopRouter;
 
   protected:
     bool handleReceivedProtobuf(const meshtastic_MeshPacket &mp, meshtastic_RouteDiscovery *r) override;