Deterministic packets (#11014)

src/mesh/PhoneAPI.cpp

@@ -1201,19 +1201,49 @@ void PhoneAPI::prefetchNodeInfos()
         onNowHasData(0);
 }
 
+namespace
+{
+/// Derive a stable id for a replayed satellite-DB record. Unchanged history replayed on
+/// every reconnect must not look like a new packet to the phone's history/dedup - the id
+/// only changes when the underlying data (its timestamp) actually changes.
+// `kind` only needs to distinguish the record types that can otherwise collide (e.g. device
+// vs. environment metrics both replay as TELEMETRY_APP with the same node/last_heard) - pass
+// the payload's own variant/port constant.
+uint32_t makeReplayPacketId(NodeNum num, uint32_t timestamp, uint32_t kind)
+{
+    uint32_t h = num;
+    h = h * 2654435761u + timestamp;
+    h = h * 2654435761u + kind;
+    return h ? h : 1; // some clients treat id 0 as "unset"
+}
+
+/// Populate hop_start/hop_limit from the node's real last-known hop count (if any) so a
+/// replayed packet doesn't read as "heard directly" when it wasn't.
+void setReplayHopFields(meshtastic_MeshPacket &pkt, const meshtastic_NodeInfoLite *header)
+{
+    uint8_t hopLimit = Default::getConfiguredOrDefaultHopLimit(config.lora.hop_limit);
+    uint8_t hopsAway = (header && header->has_hops_away) ? header->hops_away : 0;
+    pkt.hop_start = hopLimit;
+    pkt.hop_limit = hopsAway < hopLimit ? (uint8_t)(hopLimit - hopsAway) : 0;
+}
+} // namespace
+
 meshtastic_MeshPacket PhoneAPI::makeReplayPositionPacket(NodeNum num, const meshtastic_PositionLite &pos)
 {
     // Shape this exactly like a fresh live broadcast Position from the peer so the
     // phone runs it through its normal "live position broadcast" handler path.
     // to=ourNum would read as a DM-from-peer and never lands in node detail UI.
     meshtastic_MeshPacket pkt = meshtastic_MeshPacket_init_default;
+    const meshtastic_NodeInfoLite *header = nodeDB->getMeshNode(num);
     pkt.from = num;
     pkt.to = NODENUM_BROADCAST;
-    pkt.id = generatePacketId();
     pkt.rx_time = pos.time;
+    // Stable per-node/per-fix id: replaying the same unchanged history on every
+    // reconnect must not look like a brand new packet to the phone's history/dedup.
+    pkt.id = makeReplayPacketId(num, pkt.rx_time, meshtastic_PortNum_POSITION_APP);
     pkt.channel = 0;
-    pkt.hop_limit = Default::getConfiguredOrDefaultHopLimit(config.lora.hop_limit);
+    pkt.rx_snr = header ? header->snr : 0;
-    pkt.hop_start = pkt.hop_limit;
+    setReplayHopFields(pkt, header);
     pkt.priority = meshtastic_MeshPacket_Priority_BACKGROUND;
     // Mark as if heard over the air, not internally generated
     pkt.transport_mechanism = meshtastic_MeshPacket_TransportMechanism_TRANSPORT_LORA;
@@ -1231,13 +1261,13 @@ meshtastic_MeshPacket PhoneAPI::makeReplayTelemetryPacket(NodeNum num, const mes
     meshtastic_MeshPacket pkt = meshtastic_MeshPacket_init_default;
     pkt.from = num;
     pkt.to = NODENUM_BROADCAST;
-    pkt.id = generatePacketId();
     // No native timestamp on telemetry packets here; use last_heard.
     const meshtastic_NodeInfoLite *header = nodeDB->getMeshNode(num);
     pkt.rx_time = header ? header->last_heard : 0;
+    pkt.id = makeReplayPacketId(num, pkt.rx_time, meshtastic_Telemetry_device_metrics_tag);
     pkt.channel = 0;
-    pkt.hop_limit = Default::getConfiguredOrDefaultHopLimit(config.lora.hop_limit);
+    pkt.rx_snr = header ? header->snr : 0;
-    pkt.hop_start = pkt.hop_limit;
+    setReplayHopFields(pkt, header);
     pkt.priority = meshtastic_MeshPacket_Priority_BACKGROUND;
     // Mark as if heard over the air, not internally generated - iOS client filters
     // TRANSPORT_INTERNAL packets out of broadcast peer state updates.
@@ -1337,12 +1367,12 @@ meshtastic_MeshPacket PhoneAPI::makeReplayEnvironmentPacket(uint32_t num, const
     meshtastic_MeshPacket pkt = meshtastic_MeshPacket_init_default;
     pkt.from = num;
     pkt.to = NODENUM_BROADCAST;
-    pkt.id = generatePacketId();
     const meshtastic_NodeInfoLite *header = nodeDB->getMeshNode(num);
     pkt.rx_time = header ? header->last_heard : 0;
+    pkt.id = makeReplayPacketId(num, pkt.rx_time, meshtastic_Telemetry_environment_metrics_tag);
     pkt.channel = 0;
-    pkt.hop_limit = Default::getConfiguredOrDefaultHopLimit(config.lora.hop_limit);
+    pkt.rx_snr = header ? header->snr : 0;
-    pkt.hop_start = pkt.hop_limit;
+    setReplayHopFields(pkt, header);
     pkt.priority = meshtastic_MeshPacket_Priority_BACKGROUND;
     // Mark as if heard over the air, not internally generated - iOS client filters
     // TRANSPORT_INTERNAL packets out of broadcast peer state updates.
@@ -1400,13 +1430,13 @@ meshtastic_MeshPacket PhoneAPI::makeReplayStatusPacket(uint32_t num, const mesht
     meshtastic_MeshPacket pkt = meshtastic_MeshPacket_init_default;
     pkt.from = num;
     pkt.to = NODENUM_BROADCAST;
-    pkt.id = generatePacketId();
     // StatusMessage has no native timestamp; use last_heard.
     const meshtastic_NodeInfoLite *header = nodeDB->getMeshNode(num);
     pkt.rx_time = header ? header->last_heard : 0;
+    pkt.id = makeReplayPacketId(num, pkt.rx_time, meshtastic_PortNum_NODE_STATUS_APP);
     pkt.channel = 0;
-    pkt.hop_limit = Default::getConfiguredOrDefaultHopLimit(config.lora.hop_limit);
+    pkt.rx_snr = header ? header->snr : 0;
-    pkt.hop_start = pkt.hop_limit;
+    setReplayHopFields(pkt, header);
     pkt.priority = meshtastic_MeshPacket_Priority_BACKGROUND;
     // Mark as if heard over the air, not internally generated - client filters
     pkt.transport_mechanism = meshtastic_MeshPacket_TransportMechanism_TRANSPORT_LORA;