fix: keep longest manufacturer data when scan record has multiple 0xFF AD structures

android/build.gradle

@@ -91,6 +91,8 @@ dependencies {
   implementation "com.facebook.react:react-native:+"
   implementation 'io.reactivex.rxjava2:rxjava:2.2.17'
   implementation "com.polidea.rxandroidble2:rxandroidble:1.17.2"
+
+  testImplementation "junit:junit:4.13.2"
 }
 
 if (isNewArchitectureEnabled()) {

android/src/main/java/com/bleplx/adapter/AdvertisementData.java

@@ -199,6 +199,15 @@ private static void parseTxPowerLevel(AdvertisementData advData, int adLength, B
 
   private static void parseManufacturerData(AdvertisementData advData, int adLength, ByteBuffer data) {
     if (adLength < 2) return;
+    // A merged scan record can carry more than one manufacturer-specific AD
+    // structure (0xFF), e.g. one from ADV_IND and another from SCAN_RSP. The
+    // previous behaviour kept whichever structure appeared last, so a short
+    // placeholder could replace the real payload. Keep the longest structure
+    // instead, matching what iOS exposes via CoreBluetooth's merged
+    // advertisement data.
+    if (advData.manufacturerData != null && advData.manufacturerData.length >= adLength) {
+      return;
+    }
     advData.manufacturerData = new byte[adLength];
     data.get(advData.manufacturerData, 0, adLength);
   }

android/src/test/java/com/bleplx/adapter/AdvertisementDataTest.java

@@ -0,0 +1,130 @@
+package com.bleplx.adapter;
+
+import static org.junit.Assert.assertArrayEquals;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+
+import org.junit.Test;
+
+public class AdvertisementDataTest {
+
+  // --- helpers -------------------------------------------------------------
+
+  private static byte[] mfgStructure(byte... payload) {
+    byte[] structure = new byte[payload.length + 2];
+    structure[0] = (byte) (payload.length + 1); // AD length includes the type byte
+    structure[1] = (byte) 0xFF;                 // manufacturer specific data
+    System.arraycopy(payload, 0, structure, 2, payload.length);
+    return structure;
+  }
+
+  private static byte[] concat(byte[]... parts) {
+    int length = 0;
+    for (byte[] part : parts) length += part.length;
+    byte[] record = new byte[length];
+    int offset = 0;
+    for (byte[] part : parts) {
+      System.arraycopy(part, 0, record, offset, part.length);
+      offset += part.length;
+    }
+    return record;
+  }
+
+  private static final byte[] LOCAL_NAME_TEST = {0x05, 0x09, 'T', 'e', 's', 't'};
+
+  private static final byte[] LONG_PAYLOAD = {0x64, 0x4E, 0x01, 0x02};
+  private static final byte[] SHORT_PAYLOAD = {0x46, 0x46};
+
+  // --- single structure: behaviour unchanged --------------------------------
+
+  @Test
+  public void parsesSingleManufacturerDataStructure() {
+    AdvertisementData advData =
+      AdvertisementData.parseScanResponseData(mfgStructure(LONG_PAYLOAD));
+
+    assertArrayEquals(LONG_PAYLOAD, advData.getManufacturerData());
+  }
+
+  @Test
+  public void ignoresManufacturerDataShorterThanCompanyId() {
+    AdvertisementData advData =
+      AdvertisementData.parseScanResponseData(mfgStructure((byte) 0x64));
+
+    assertNull(advData.getManufacturerData());
+  }
+
+  // --- multiple structures: the longest one wins ----------------------------
+
+  @Test
+  public void keepsLongerManufacturerDataWhenShorterFollows() {
+    // e.g. real payload advertised in ADV_IND, placeholder in SCAN_RSP
+    byte[] record = concat(mfgStructure(LONG_PAYLOAD), mfgStructure(SHORT_PAYLOAD));
+
+    AdvertisementData advData = AdvertisementData.parseScanResponseData(record);
+
+    assertArrayEquals(LONG_PAYLOAD, advData.getManufacturerData());
+  }
+
+  @Test
+  public void keepsLongerManufacturerDataWhenLongerFollows() {
+    // e.g. placeholder advertised in ADV_IND, real payload in SCAN_RSP
+    byte[] record = concat(mfgStructure(SHORT_PAYLOAD), mfgStructure(LONG_PAYLOAD));
+
+    AdvertisementData advData = AdvertisementData.parseScanResponseData(record);
+
+    assertArrayEquals(LONG_PAYLOAD, advData.getManufacturerData());
+  }
+
+  @Test
+  public void keepsFirstManufacturerDataOnEqualLength() {
+    byte[] first = {0x01, 0x02, 0x03};
+    byte[] second = {0x04, 0x05, 0x06};
+    byte[] record = concat(mfgStructure(first), mfgStructure(second));
+
+    AdvertisementData advData = AdvertisementData.parseScanResponseData(record);
+
+    assertArrayEquals(first, advData.getManufacturerData());
+  }
+
+  @Test
+  public void continuesParsingSubsequentStructuresAfterKeepingExisting() {
+    // a kept-as-is (ignored) shorter structure must not desynchronize the
+    // cursor: the local name that follows it still has to parse correctly
+    byte[] record =
+      concat(mfgStructure(LONG_PAYLOAD), mfgStructure(SHORT_PAYLOAD), LOCAL_NAME_TEST);
+
+    AdvertisementData advData = AdvertisementData.parseScanResponseData(record);
+
+    assertArrayEquals(LONG_PAYLOAD, advData.getManufacturerData());
+    assertEquals("Test", advData.getLocalName());
+  }
+
+  // --- real-world capture ----------------------------------------------------
+
+  @Test
+  public void parsesRealWorldMergedScanRecord() {
+    // Merged scan record captured from a peripheral that advertises its real
+    // 25-byte identity in one packet and a 12-byte "FFFFFFFFFFFF" placeholder
+    // in the other (see PR description). Previously the placeholder won.
+    byte[] record = {
+      0x02, 0x01, 0x06, 0x1A, (byte) 0xFF, 0x64, 0x4E, 0x43,
+      0x50, 0x64, 0x53, 0x67, 0x6D, 0x52, 0x50, 0x35,
+      0x30, 0x31, 0x30, 0x31, 0x30, 0x35, 0x39, 0x30,
+      0x30, 0x31, 0x31, 0x38, 0x39, 0x01, 0x0D, (byte) 0xFF,
+      0x46, 0x46, 0x46, 0x46, 0x46, 0x46, 0x46, 0x46,
+      0x46, 0x46, 0x46, 0x46, 0x0D, 0x09, 0x41, 0x49,
+      0x20, 0x4E, 0x6F, 0x74, 0x65, 0x2D, 0x34, 0x45,
+      0x36, 0x33, 0x00, 0x00, 0x00, 0x00
+    };
+    byte[] realPayload = {
+      0x64, 0x4E, 0x43, 0x50, 0x64, 0x53, 0x67, 0x6D, 0x52, 0x50, 0x35, 0x30,
+      0x31, 0x30, 0x31, 0x30, 0x35, 0x39, 0x30, 0x30, 0x31, 0x31, 0x38, 0x39,
+      0x01
+    };
+
+    AdvertisementData advData = AdvertisementData.parseScanResponseData(record);
+
+    assertArrayEquals(realPayload, advData.getManufacturerData());
+    assertEquals("AI Note-4E63", advData.getLocalName());
+  }
+}