From 94824fbb98599360fcca511fc5b55517d0a579fb Mon Sep 17 00:00:00 2001
From: Oliver Jowett <oliver@mutability.co.uk>
Date: Fri, 23 Feb 2018 18:21:01 +0000
Subject: [PATCH] Avoid coredump on "untracked" aircraft (icao 000000) Clean up
 the first-message-squelch logic a little.

---
 mode_s.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/mode_s.c b/mode_s.c
index 9f943b4..cd6afc4 100644
--- a/mode_s.c
+++ b/mode_s.c
@@ -2106,14 +2106,13 @@ void useModesMessage(struct modesMessage *mm) {
     // forward messages when we have seen two of them.
 
     if (Modes.net) {
-        if (Modes.net_verbatim || mm->msgtype == 32) {
+        if (Modes.net_verbatim || mm->msgtype == 32 || !a) {
             // Unconditionally send
             modesQueueOutput(mm, a);
         } else if (a->messages > 1) {
-            // If this is the second message, and we
-            // squelched the first message, then re-emit the
-            // first message now.
-            if (!Modes.net_verbatim && a && a->messages == 2) {
+            // Suppress the first message. When we receive a second message,
+            // emit the first two messages.
+            if (a->messages == 2) {
                 modesQueueOutput(&a->first_message, a);
             }
             modesQueueOutput(mm, a);