Make sure to ACK ACKs/replies if next-hop routing is used (#8052)

* Make sure to ACK ACKs/replies if next-hop routing is used
To stop their retransmissions; hop limit of 0 is enough

* Update src/mesh/ReliableRouter.cpp

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

---------

Co-authored-by: Ben Meadors <benmmeadors@gmail.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

src/mesh/ReliableRouter.cpp

@@ -97,27 +97,34 @@ bool ReliableRouter::shouldFilterReceived(const meshtastic_MeshPacket *p)
 void ReliableRouter::sniffReceived(const meshtastic_MeshPacket *p, const meshtastic_Routing *c)
 {
     if (isToUs(p)) { // ignore ack/nak/want_ack packets that are not address to us (we only handle 0 hop reliability)
-        if (p->want_ack) {
+        if (!MeshModule::currentReply) {
-            if (MeshModule::currentReply) {
+            if (p->want_ack) {
-                LOG_DEBUG("Another module replied to this message, no need for 2nd ack");
+                if (p->which_payload_variant == meshtastic_MeshPacket_decoded_tag) {
-            } else if (p->which_payload_variant == meshtastic_MeshPacket_decoded_tag) {
+                    /* A response may be set to want_ack for retransmissions, but we don't need to ACK a response if it received
-                // A response may be set to want_ack for retransmissions, but we don't need to ACK a response if it received an
+                      an implicit ACK already. If we received it directly or via NextHopRouter, only ACK with a hop limit of 0 to
-                // implicit ACK already. If we received it directly, only ACK with a hop limit of 0
+                      make sure the other side stops retransmitting. */
-                if (!p->decoded.request_id)
+                    if (!p->decoded.request_id && !p->decoded.reply_id) {
-                    sendAckNak(meshtastic_Routing_Error_NONE, getFrom(p), p->id, p->channel,
+                        sendAckNak(meshtastic_Routing_Error_NONE, getFrom(p), p->id, p->channel,
+                                   routingModule->getHopLimitForResponse(p->hop_start, p->hop_limit));
+                    } else if ((p->hop_start > 0 && p->hop_start == p->hop_limit) || p->next_hop != NO_NEXT_HOP_PREFERENCE) {
+                        sendAckNak(meshtastic_Routing_Error_NONE, getFrom(p), p->id, p->channel, 0);
+                    }
+                } else if (p->which_payload_variant == meshtastic_MeshPacket_encrypted_tag && p->channel == 0 &&
+                           (nodeDB->getMeshNode(p->from) == nullptr || nodeDB->getMeshNode(p->from)->user.public_key.size == 0)) {
+                    LOG_INFO("PKI packet from unknown node, send PKI_UNKNOWN_PUBKEY");
+                    sendAckNak(meshtastic_Routing_Error_PKI_UNKNOWN_PUBKEY, getFrom(p), p->id, channels.getPrimaryIndex(),
                                routingModule->getHopLimitForResponse(p->hop_start, p->hop_limit));
-                else if (p->hop_start > 0 && p->hop_start == p->hop_limit)
+                } else {
-                    sendAckNak(meshtastic_Routing_Error_NONE, getFrom(p), p->id, p->channel, 0);
+                    // Send a 'NO_CHANNEL' error on the primary channel if want_ack packet destined for us cannot be decoded
-            } else if (p->which_payload_variant == meshtastic_MeshPacket_encrypted_tag && p->channel == 0 &&
+                    sendAckNak(meshtastic_Routing_Error_NO_CHANNEL, getFrom(p), p->id, channels.getPrimaryIndex(),
-                       (nodeDB->getMeshNode(p->from) == nullptr || nodeDB->getMeshNode(p->from)->user.public_key.size == 0)) {
+                               routingModule->getHopLimitForResponse(p->hop_start, p->hop_limit));
-                LOG_INFO("PKI packet from unknown node, send PKI_UNKNOWN_PUBKEY");
+                }
-                sendAckNak(meshtastic_Routing_Error_PKI_UNKNOWN_PUBKEY, getFrom(p), p->id, channels.getPrimaryIndex(),
+            } else if (p->next_hop == nodeDB->getLastByteOfNodeNum(getNodeNum()) && p->hop_limit > 0) {
-                           routingModule->getHopLimitForResponse(p->hop_start, p->hop_limit));
+                // No wantAck, but we need to ACK with hop limit of 0 if we were the next hop to stop their retransmissions
-            } else {
+                sendAckNak(meshtastic_Routing_Error_NONE, getFrom(p), p->id, p->channel, 0);
-                // Send a 'NO_CHANNEL' error on the primary channel if want_ack packet destined for us cannot be decoded
-                sendAckNak(meshtastic_Routing_Error_NO_CHANNEL, getFrom(p), p->id, channels.getPrimaryIndex(),
-                           routingModule->getHopLimitForResponse(p->hop_start, p->hop_limit));
             }
+        } else {
+            LOG_DEBUG("Another module replied to this message, no need for 2nd ack");
         }
         if (p->which_payload_variant == meshtastic_MeshPacket_decoded_tag && c &&
             c->error_reason == meshtastic_Routing_Error_PKI_UNKNOWN_PUBKEY) {