From 8da4ea2aaff5b75845a63066e809719553a0442a Mon Sep 17 00:00:00 2001
From: Matej Glejtek <matejglejtek@gmail.com>
Date: Sun, 3 Sep 2023 20:42:55 +0200
Subject: [PATCH] feat: shorted BLE advertisements to max 31 bytes

---
 .../flutter_opendroneid/scanner/BluetoothScanner.kt         | 6 ++++--
 .../cz/dronetag/flutter_opendroneid/scanner/ODIDScanner.kt  | 4 ++++
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/android/src/main/kotlin/cz/dronetag/flutter_opendroneid/scanner/BluetoothScanner.kt b/android/src/main/kotlin/cz/dronetag/flutter_opendroneid/scanner/BluetoothScanner.kt
index af3622e..6ee3b00 100644
--- a/android/src/main/kotlin/cz/dronetag/flutter_opendroneid/scanner/BluetoothScanner.kt
+++ b/android/src/main/kotlin/cz/dronetag/flutter_opendroneid/scanner/BluetoothScanner.kt
@@ -46,9 +46,11 @@ class BluetoothScanner(
                 if (result.getPrimaryPhy() == BluetoothDevice.PHY_LE_CODED)
                     source = Pigeon.MessageSource.BLUETOOTH_LONG_RANGE;
             }
-
+            // if using BLE, max size of data is MAX_BLE_ADV_SIZE
+            // if using BT5, data can be longer up to 256 bytes
+            val isBLE = maxAdvDataLen() <= MAX_BLE_ADV_SIZE
             receiveData(
-                offsetData(bytes, BT_OFFSET),
+                if(isBLE) getDataFromIndex(bytes, BT_OFFSET, MAX_BLE_ADV_SIZE) else offsetData(bytes, BT_OFFSET),
                 result.device.address,
                 source,
                 result.rssi.toLong(),
diff --git a/android/src/main/kotlin/cz/dronetag/flutter_opendroneid/scanner/ODIDScanner.kt b/android/src/main/kotlin/cz/dronetag/flutter_opendroneid/scanner/ODIDScanner.kt
index 5ce4401..8f776b6 100644
--- a/android/src/main/kotlin/cz/dronetag/flutter_opendroneid/scanner/ODIDScanner.kt
+++ b/android/src/main/kotlin/cz/dronetag/flutter_opendroneid/scanner/ODIDScanner.kt
@@ -15,6 +15,7 @@ abstract class ODIDScanner(
     companion object {
         const val MAX_MESSAGE_SIZE = 25
         const val BT_OFFSET = 6
+        const val MAX_BLE_ADV_SIZE = 31
         const val WIFI_BEACON_OFFSET = 5
         const val WIFI_NAN_OFFSET = 1
     }
@@ -62,4 +63,7 @@ abstract class ODIDScanner(
 
     /// returns ByteArray without first offset elements
     inline fun offsetData(data: ByteArray, offset: Int) : ByteArray = data.copyOfRange(offset, data.size)
+
+    /// returns ByteArray with bytes from start to end
+    inline fun getDataFromIndex(data: ByteArray, start: Int, end: Int) : ByteArray = data.copyOfRange(start, end)
 }
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