Refactor position precision handling to honor explicit channel settings and prevent location leaks (#10513)

src/mesh/PositionPrecision.cpp

@@ -4,17 +4,19 @@
 
 #include <Arduino.h>
 
-uint32_t getPositionPrecisionForChannel(uint8_t channelIndex)
+uint32_t getPositionPrecisionForChannel(const meshtastic_Channel &channel)
 {
-    const meshtastic_Channel &channel = channels.getByIndex(channelIndex);
-
     if (channel.settings.has_module_settings) {
         return channel.settings.module_settings.position_precision;
-    } else if (channel.role == meshtastic_Channel_Role_PRIMARY) {
-        return 32;
-    } else {
-        return 0;
     }
+    // No module settings: fail closed. A PRIMARY channel used to default to 32
+    // here, leaking an exact position on a sharing-disabled channel. See #10509.
+    return 0;
+}
+
+uint32_t getPositionPrecisionForChannel(uint8_t channelIndex)
+{
+    return getPositionPrecisionForChannel(channels.getByIndex(channelIndex));
 }
 
 static int32_t truncateCoordinate(int32_t coordinate, uint32_t precision)

src/mesh/PositionPrecision.h

@@ -1,8 +1,10 @@
 #pragma once
 
+#include "meshtastic/channel.pb.h"
 #include "meshtastic/mesh.pb.h"
 #include <stdint.h>
 
+uint32_t getPositionPrecisionForChannel(const meshtastic_Channel &channel);
 uint32_t getPositionPrecisionForChannel(uint8_t channelIndex);
 void applyPositionPrecision(meshtastic_Position &position, uint32_t precision);
 bool applyPositionPrecision(meshtastic_MeshPacket &packet, uint32_t precision);