Don't cancel relay if we were the assigned next-hop

src/mesh/FloodingRouter.cpp

@@ -22,6 +22,8 @@ ErrorCode FloodingRouter::send(meshtastic_MeshPacket *p)
 bool FloodingRouter::shouldFilterReceived(const meshtastic_MeshPacket *p)
 {
     if (wasSeenRecently(p)) { // Note: this will also add a recent packet record
+        printPacket("Ignore dupe incoming msg", p);
+        rxDupe++;
         /* If the original transmitter is doing retransmissions (hopStart equals hopLimit) for a reliable transmission, e.g., when
         the ACK got lost, we will handle the packet again to make sure it gets an implicit ACK. */
         bool isRepeated = p->hop_start > 0 && p->hop_start == p->hop_limit;
@@ -42,8 +44,6 @@ bool FloodingRouter::shouldFilterReceived(const meshtastic_MeshPacket *p)
 
 void FloodingRouter::perhapsCancelDupe(const meshtastic_MeshPacket *p)
 {
-    printPacket("Ignore dupe incoming msg", p);
-    rxDupe++;
     if (config.device.role != meshtastic_Config_DeviceConfig_Role_ROUTER &&
         config.device.role != meshtastic_Config_DeviceConfig_Role_REPEATER) {
         // cancel rebroadcast of this message *if* there was already one, unless we're a router/repeater!
@@ -73,6 +73,7 @@ void FloodingRouter::perhapsRebroadcast(const meshtastic_MeshPacket *p)
                     tosend->hop_limit = 2;
                 }
 #endif
+                tosend->next_hop = NO_NEXT_HOP_PREFERENCE; // this should already be the case, but just in case
 
                 LOG_INFO("Rebroadcast received floodmsg");
                 // Note: we are careful to resend using the original senders node id

src/mesh/NextHopRouter.cpp

@@ -31,7 +31,10 @@ ErrorCode NextHopRouter::send(meshtastic_MeshPacket *p)
 bool NextHopRouter::shouldFilterReceived(const meshtastic_MeshPacket *p)
 {
     bool wasFallback = false;
-    if (wasSeenRecently(p, true, &wasFallback)) { // Note: this will also add a recent packet record
+    bool weWereNextHop = false;
+    if (wasSeenRecently(p, true, &wasFallback, &weWereNextHop)) { // Note: this will also add a recent packet record
+        printPacket("Ignore dupe incoming msg", p);
+        rxDupe++;
         stopRetransmission(p->from, p->id);
 
         // If it was a fallback to flooding, try to relay again
@@ -46,8 +49,8 @@ bool NextHopRouter::shouldFilterReceived(const meshtastic_MeshPacket *p)
             if (isRepeated) {
                 if (!findInTxQueue(p->from, p->id) && !perhapsRelay(p) && isToUs(p) && p->want_ack)
                     sendAckNak(meshtastic_Routing_Error_NONE, getFrom(p), p->id, p->channel, 0);
-            } else {
+            } else if (!weWereNextHop) {
-                perhapsCancelDupe(p); // If it's a dupe, cancel relay
+                perhapsCancelDupe(p); // If it's a dupe, cancel relay if we were not explicitly asked to relay
             }
         }
         return true;

src/mesh/PacketHistory.cpp

@@ -16,7 +16,7 @@ PacketHistory::PacketHistory()
 /**
  * Update recentBroadcasts and return true if we have already seen this packet
  */
-bool PacketHistory::wasSeenRecently(const meshtastic_MeshPacket *p, bool withUpdate, bool *wasFallback)
+bool PacketHistory::wasSeenRecently(const meshtastic_MeshPacket *p, bool withUpdate, bool *wasFallback, bool *weWereNextHop)
 {
     if (p->id == 0) {
         LOG_DEBUG("Ignore message with zero id");
@@ -43,26 +43,32 @@ bool PacketHistory::wasSeenRecently(const meshtastic_MeshPacket *p, bool withUpd
 
     if (seenRecently) {
         LOG_DEBUG("Found existing packet record for fr=0x%x,to=0x%x,id=0x%x", p->from, p->to, p->id);
+        uint8_t ourRelayID = nodeDB->getLastByteOfNodeNum(nodeDB->getNodeNum());
         if (wasFallback) {
             // If it was seen with a next-hop not set to us and now it's NO_NEXT_HOP_PREFERENCE, and the relayer relayed already
             // before, it's a fallback to flooding. If we didn't already relay and the next-hop neither, we might need to handle
             // it now.
-            uint8_t ourRelayID = nodeDB->getLastByteOfNodeNum(nodeDB->getNodeNum());
             if (found->sender != nodeDB->getNodeNum() && found->next_hop != NO_NEXT_HOP_PREFERENCE &&
                 found->next_hop != ourRelayID && p->next_hop == NO_NEXT_HOP_PREFERENCE && wasRelayer(p->relay_node, found) &&
                 !wasRelayer(ourRelayID, found) && !wasRelayer(found->next_hop, found)) {
                 *wasFallback = true;
             }
         }
+
+        // Check if we were the next hop for this packet
+        if (weWereNextHop) {
+            *weWereNextHop = found->next_hop == ourRelayID;
+        }
     }
 
     if (withUpdate) {
-        if (found != recentPackets.end()) { // delete existing to updated timestamp and next-hop/relayed_by (re-insert)
+        if (found != recentPackets.end()) { // delete existing to updated timestamp and relayed_by (re-insert)
             // Add the existing relayed_by to the new record
             for (uint8_t i = 0; i < NUM_RELAYERS - 1; i++) {
                 if (found->relayed_by[i])
                     r.relayed_by[i + 1] = found->relayed_by[i];
             }
+            r.next_hop = found->next_hop; // keep the original next_hop (such that we check whether we were originally asked)
             recentPackets.erase(found);   // as unsorted_set::iterator is const (can't update - so re-insert..)
         }
         recentPackets.insert(r);

src/mesh/PacketHistory.h

@@ -46,8 +46,10 @@ class PacketHistory
      *
      * @param withUpdate if true and not found we add an entry to recentPackets
      * @param wasFallback if not nullptr, packet will be checked for fallback to flooding and value will be set to true if so
+     * @param weWereNextHop if not nullptr, packet will be checked for us being the next hop and value will be set to true if so
      */
-    bool wasSeenRecently(const meshtastic_MeshPacket *p, bool withUpdate = true, bool *wasFallback = nullptr);
+    bool wasSeenRecently(const meshtastic_MeshPacket *p, bool withUpdate = true, bool *wasFallback = nullptr,
+                         bool *weWereNextHop = nullptr);
 
     /* Check if a certain node was a relayer of a packet in the history given an ID and sender
      * @return true if node was indeed a relayer, false if not */