Default to not forwarding mlat messages. Add --forward-mlat option to enable it.

dump1090.c

@@ -694,6 +694,7 @@ void showHelp(void) {
 "--net-heartbeat <rate>   TCP heartbeat rate in seconds (default: 60 sec; 0 to disable)\n"
 "--net-buffer <n>         TCP buffer size 64Kb * (2^n) (default: n=0, 64Kb)\n"
 "--net-verbatim           Do not apply CRC corrections to messages we forward; send unchanged\n"
+"--forward-mlat           Allow forwarding of received mlat results to output ports\n"
 "--lat <latitude>         Reference/receiver latitude for surface posn (opt)\n"
 "--lon <longitude>        Reference/receiver longitude for surface posn (opt)\n"
 "--max-range <distance>   Absolute maximum range for position decoding (in nm, default: 300)\n"
@@ -994,6 +995,8 @@ int main(int argc, char **argv) {
             Modes.net_sndbuf_size = atoi(argv[++j]);
         } else if (!strcmp(argv[j],"--net-verbatim")) {
             Modes.net_verbatim = 1;
+        } else if (!strcmp(argv[j],"--forward-mlat")) {
+            Modes.forward_mlat = 1;
         } else if (!strcmp(argv[j],"--onlyaddr")) {
             Modes.onlyaddr = 1;
         } else if (!strcmp(argv[j],"--metric")) {

dump1090.h

@@ -309,6 +309,7 @@ struct {                             // Internal state
     int   net_fatsv_port;            // FlightAware TSV port
     int   net_sndbuf_size;           // TCP output buffer size (64Kb * 2^n)
     int   net_verbatim;              // if true, send the original message, not the CRC-corrected one
+    int   forward_mlat;              // allow forwarding of mlat messages to output ports
     int   quiet;                     // Suppress stdout
     uint32_t show_only;              // Only show messages from this ICAO
     int   interactive;               // Interactive mode

net_io.c

@@ -637,6 +637,9 @@ static void send_sbs_heartbeat(struct net_service *service)
 //=========================================================================
 //
 void modesQueueOutput(struct modesMessage *mm) {
+    if ((mm->bFlags & MODES_ACFLAGS_FROM_MLAT) && !Modes.forward_mlat)
+        return;
+
     modesSendSBSOutput(mm);
     modesSendBeastOutput(mm);
     modesSendRawOutput(mm);