Event mode: Enforce reliable hop limit and disallow default public MQTT (#4343)

* Event mode: Enforce reliable hop limit

* Event mode: Short circuit wantsLink on MQTT for default broker address

* Just enforce at channels level since everything uses this

* For events never forward packets with excessive hop_limit

* In EVENT_MODE, don't respond with hop_limit set more then the configured max.

* Correct hop_start when correcting hop_limit in event mode.

* Make EVENT_MODE work from userPrefs.h

* Event mode: Disallow Router or Repeater roles

---------

Co-authored-by: Jonathan Bennett <jbennett@incomsystems.biz>

src/mesh/Channels.cpp

@@ -1,6 +1,7 @@
 #include "Channels.h"
 #include "../userPrefs.h"
 #include "CryptoEngine.h"
+#include "Default.h"
 #include "DisplayFormatters.h"
 #include "NodeDB.h"
 #include "RadioInterface.h"
@@ -276,6 +277,12 @@ void Channels::setChannel(const meshtastic_Channel &c)
 
 bool Channels::anyMqttEnabled()
 {
+#if EVENT_MODE
+    // Don't publish messages on the public MQTT broker if we are in event mode
+    if (strcmp(moduleConfig.mqtt.address, default_mqtt_address) == 0) {
+        return false;
+    }
+#endif
     for (int i = 0; i < getNumChannels(); i++)
         if (channelFile.channels[i].role != meshtastic_Channel_Role_DISABLED && channelFile.channels[i].has_settings &&
             (channelFile.channels[i].settings.downlink_enabled || channelFile.channels[i].settings.uplink_enabled))

src/mesh/Default.cpp

@@ -1,4 +1,5 @@
 #include "Default.h"
+#include "../userPrefs.h"
 
 uint32_t Default::getConfiguredOrDefaultMs(uint32_t configuredInterval, uint32_t defaultInterval)
 {
@@ -41,3 +42,12 @@ uint32_t Default::getConfiguredOrDefaultMsScaled(uint32_t configured, uint32_t d
 
     return getConfiguredOrDefaultMs(configured, defaultValue) * congestionScalingCoefficient(numOnlineNodes);
 }
+
+uint8_t Default::getConfiguredOrDefaultHopLimit(uint8_t configured)
+{
+#if EVENT_MODE
+    return (configured > HOP_RELIABLE) ? HOP_RELIABLE : config.lora.hop_limit;
+#else
+    return (configured >= HOP_MAX) ? HOP_MAX : config.lora.hop_limit;
+#endif
+}

src/mesh/Default.h

@@ -30,6 +30,7 @@ class Default
     static uint32_t getConfiguredOrDefaultMs(uint32_t configuredInterval, uint32_t defaultInterval);
     static uint32_t getConfiguredOrDefault(uint32_t configured, uint32_t defaultValue);
     static uint32_t getConfiguredOrDefaultMsScaled(uint32_t configured, uint32_t defaultValue, uint32_t numOnlineNodes);
+    static uint8_t getConfiguredOrDefaultHopLimit(uint8_t configured);
 
   private:
     static float congestionScalingCoefficient(int numOnlineNodes)

src/mesh/FloodingRouter.cpp

@@ -1,4 +1,5 @@
 #include "FloodingRouter.h"
+#include "../userPrefs.h"
 #include "configuration.h"
 #include "mesh-pb-constants.h"
 
@@ -46,6 +47,13 @@ void FloodingRouter::sniffReceived(const meshtastic_MeshPacket *p, const meshtas
                 meshtastic_MeshPacket *tosend = packetPool.allocCopy(*p); // keep a copy because we will be sending it
 
                 tosend->hop_limit--; // bump down the hop count
+#if EVENT_MODE
+                if (tosend->hop_limit > 2) {
+                    // if we are "correcting" the hop_limit, "correct" the hop_start by the same amount to preserve hops away.
+                    tosend->hop_start -= (tosend->hop_limit - 2);
+                    tosend->hop_limit = 2;
+                }
+#endif
 
                 LOG_INFO("Rebroadcasting received floodmsg to neighbors\n");
                 // Note: we are careful to resend using the original senders node id

src/mesh/ReliableRouter.cpp

@@ -1,4 +1,5 @@
 #include "ReliableRouter.h"
+#include "Default.h"
 #include "MeshModule.h"
 #include "MeshTypes.h"
 #include "configuration.h"
@@ -17,7 +18,7 @@ ErrorCode ReliableRouter::send(meshtastic_MeshPacket *p)
         // message will rebroadcast.  But asking for hop_limit 0 in that context means the client app has no preference on hop
         // counts and we want this message to get through the whole mesh, so use the default.
         if (p->hop_limit == 0) {
-            p->hop_limit = (config.lora.hop_limit >= HOP_MAX) ? HOP_MAX : config.lora.hop_limit;
+            p->hop_limit = Default::getConfiguredOrDefaultHopLimit(config.lora.hop_limit);
         }
 
         auto copy = packetPool.allocCopy(*p);

src/mesh/Router.cpp

@@ -11,6 +11,7 @@
 #if !MESHTASTIC_EXCLUDE_MQTT
 #include "mqtt/MQTT.h"
 #endif
+#include "Default.h"
 #if ARCH_PORTDUINO
 #include "platform/portduino/PortduinoGlue.h"
 #endif
@@ -125,7 +126,7 @@ meshtastic_MeshPacket *Router::allocForSending()
     p->which_payload_variant = meshtastic_MeshPacket_decoded_tag; // Assume payload is decoded at start.
     p->from = nodeDB->getNodeNum();
     p->to = NODENUM_BROADCAST;
-    p->hop_limit = (config.lora.hop_limit >= HOP_MAX) ? HOP_MAX : config.lora.hop_limit;
+    p->hop_limit = Default::getConfiguredOrDefaultHopLimit(config.lora.hop_limit);
     p->id = generatePacketId();
     p->rx_time =
         getValidTime(RTCQualityFromNet); // Just in case we process the packet locally - make sure it has a valid timestamp

src/modules/AdminModule.cpp

@@ -400,6 +400,13 @@ void AdminModule::handleSetConfig(const meshtastic_Config &c)
                 requiresReboot = true;
             }
         }
+#if EVENT_MODE
+        // If we're in event mode, nobody is a Router or Repeater
+        if (config.device.role == meshtastic_Config_DeviceConfig_Role_ROUTER ||
+            config.device.role == meshtastic_Config_DeviceConfig_Role_REPEATER) {
+            config.device.role = meshtastic_Config_DeviceConfig_Role_CLIENT;
+        }
+#endif
         break;
     case meshtastic_Config_position_tag:
         LOG_INFO("Setting config: Position\n");

src/modules/RoutingModule.cpp

@@ -1,4 +1,5 @@
 #include "RoutingModule.h"
+#include "Default.h"
 #include "MeshService.h"
 #include "NodeDB.h"
 #include "Router.h"
@@ -50,12 +51,15 @@ uint8_t RoutingModule::getHopLimitForResponse(uint8_t hopStart, uint8_t hopLimit
         // Hops used by the request. If somebody in between running modified firmware modified it, ignore it
         uint8_t hopsUsed = hopStart < hopLimit ? config.lora.hop_limit : hopStart - hopLimit;
         if (hopsUsed > config.lora.hop_limit) {
+// In event mode, we never want to send packets with more than our default 3 hops.
+#if !(EVENTMODE)             // This falls through to the default.
             return hopsUsed; // If the request used more hops than the limit, use the same amount of hops
+#endif
         } else if ((uint8_t)(hopsUsed + 2) < config.lora.hop_limit) {
             return hopsUsed + 2; // Use only the amount of hops needed with some margin as the way back may be different
         }
     }
-    return config.lora.hop_limit; // Use the default hop limit
+    return Default::getConfiguredOrDefaultHopLimit(config.lora.hop_limit); // Use the default hop limit
 }
 
 RoutingModule::RoutingModule() : ProtobufModule("routing", meshtastic_PortNum_ROUTING_APP, &meshtastic_Routing_msg)

userPrefs.h

@@ -1,7 +1,10 @@
 #ifndef _USERPREFS_
 #define _USERPREFS_
+
 // Uncomment and modify to set device defaults
 
+// #define EVENT_MODE 1
+
 // #define CONFIG_LORA_REGION_USERPREFS meshtastic_Config_LoRaConfig_RegionCode_US
 // #define LORACONFIG_MODEM_PRESET_USERPREFS meshtastic_Config_LoRaConfig_ModemPreset_SHORT_FAST
 // #define LORACONFIG_CHANNEL_NUM_USERPREFS 31