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

dump1090.c

@@ -428,6 +428,7 @@ void showHelp(void) {
 "--net-ro-rate <rate>     TCP raw output memory flush rate (default: 0)\n"
 "--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"
+"--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"
 "--fix                    Enable single-bits error correction using CRC\n"
@@ -736,6 +737,8 @@ int main(int argc, char **argv) {
             Modes.net_output_sbs_port = atoi(argv[++j]);
         } else if (!strcmp(argv[j],"--net-buffer") && more) {
             Modes.net_sndbuf_size = atoi(argv[++j]);
+        } 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

@@ -320,6 +320,7 @@ struct {                             // Internal state
     int   net_fatsv_port;            // FlightAware TSV port
     int   no_rtlsdr_ok;              // keep going if no RTLSDR dev found
     int   net_sndbuf_size;           // TCP output buffer size (64Kb * 2^n)
+    int   forward_mlat;              // enable forwarding of mlat to output ports
     int   quiet;                     // Suppress stdout
     int   interactive;               // Interactive mode
     int   interactive_rows;          // Interactive mode: max number of rows

interactive.c

@@ -371,9 +371,7 @@ struct aircraft *interactiveReceiveData(struct modesMessage *mm, struct client *
         //If we sucessfully decoded, back copy the results to mm so that we can print them in list output
         if (location_ok) {
             mm->bFlags |= MODES_ACFLAGS_LATLON_VALID;
-            if (mm->timestampMsg == 0xFF004D4C4154) // Magic mlat timestamp
+            if (!(mm->bFlags & MODES_ACFLAGS_MLAT))
-                mm->bFlags |= MODES_ACFLAGS_MLAT;
-            else
                 a->bFlags &= ~MODES_ACFLAGS_MLAT;
             mm->fLat    = a->lat;
             mm->fLon    = a->lon;

mode_s.c

@@ -838,6 +838,9 @@ void decodeModesMessage(struct modesMessage *mm, unsigned char *msg) {
     memcpy(mm->msg, msg, MODES_LONG_MSG_BYTES);
     msg = mm->msg;
 
+    if (mm->remote && mm->timestampMsg == 0xFF004D4C4154) // Magic mlat timestamp
+        mm->bFlags |= MODES_ACFLAGS_MLAT;
+
     // Get the message type ASAP as other operations depend on this
     mm->msgtype         = msg[0] >> 3; // Downlink Format
     mm->msgbits         = modesMessageLenByType(mm->msgtype);

net_io.c

@@ -473,6 +473,9 @@ void modesSendSBSOutput(struct modesMessage *mm) {
 //=========================================================================
 //
 void modesQueueOutput(struct modesMessage *mm) {
+    if ((mm->bFlags & MODES_ACFLAGS_MLAT) && !Modes.forward_mlat)
+        return;
+
     if (Modes.stat_sbs_connections)   {modesSendSBSOutput(mm);}
     if (Modes.stat_beast_connections) {modesSendBeastOutput(mm);}
     if (Modes.stat_raw_connections)   {modesSendRawOutput(mm);}