From 9a1b9bf70d8f1a38816666d67a5689ad17d23c13 Mon Sep 17 00:00:00 2001
From: Filip Jonckers <filip@jonckers.org>
Date: Sat, 8 Jan 2022 00:26:17 +0100
Subject: [PATCH] fix null pointer exception on invalid DF packet

---
 gradle.properties                                   | 2 +-
 src/main/java/aero/t2s/modes/ModeSTrackHandler.java | 8 +++++++-
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/gradle.properties b/gradle.properties
index 0d03f4d..2e29164 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -1,5 +1,5 @@
 GROUP=aero.t2s
-VERSION_NAME=0.2.3-SNAPSHOT
+VERSION_NAME=0.2.4-SNAPSHOT
 
 POM_ARTIFACT_ID=mode-s
 POM_NAME=Mode-S/ADS-B (1090Mhz)
diff --git a/src/main/java/aero/t2s/modes/ModeSTrackHandler.java b/src/main/java/aero/t2s/modes/ModeSTrackHandler.java
index db19904..16b7220 100644
--- a/src/main/java/aero/t2s/modes/ModeSTrackHandler.java
+++ b/src/main/java/aero/t2s/modes/ModeSTrackHandler.java
@@ -59,6 +59,12 @@ public void handle(final String input) {
     public DownlinkFormat handleSync(final String input) {
         try {
             DownlinkFormat df = decoder.decode(toData(input));
+            if(df == null) {
+                // invalid packet (Mode A/C like *21D2; *0200; *0101;)
+                LOGGER.debug("DF Message could not be parsed: [{}]", input);
+                return null;
+            }
+
             Track track = decoder.getTrack(df.getIcao());
 
             if (track == null) {
@@ -83,7 +89,7 @@ public DownlinkFormat handleSync(final String input) {
         } catch (InvalidExtendedSquitterTypeCodeException | UnknownDownlinkFormatException e) {
             LOGGER.error(e.getMessage());
         } catch (Throwable throwable) {
-            LOGGER.error("Message could not be parsed: [" + input + "]", throwable);
+            LOGGER.error("DF Message could not be parsed: [" + input + "]", throwable);
         }
 
         return null;