Flag for system timestamp in Beast output

Allow the user to specify that the system timestamp should be used in
the Beast output timestamp bytes instead of the device-specific
timestamp.

Author: xander-hirsch

dump1090.c

@@ -403,6 +403,7 @@ static void showHelp(void)
 "--net-buffer <n>         TCP buffer size 64Kb * (2^n) (default: n=0, 64Kb)\n"
 "--net-verbatim           Make output connections default to verbatim mode\n"
 "                           (forward all messages without correction)\n"
+"--beast-sys-time         Encode the system timestamp in Beast output\n"
 "--forward-mlat           Allow forwarding of received mlat results\n"
 "\n"
 // ------ 80 char limit ----------------------------------------------------------|
@@ -693,6 +694,8 @@ 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],"--beast-sys-time")) {
+            Modes.beast_sys_timestamp = 1;
         } else if (!strcmp(argv[j],"--forward-mlat")) {
             Modes.forward_mlat = 1;
         } else if (!strcmp(argv[j],"--onlyaddr")) {

dump1090.h

@@ -365,6 +365,7 @@ struct _Modes {                             // Internal state
     char *net_bind_address;          // Bind address
     int   net_sndbuf_size;           // TCP output buffer size (64Kb * 2^n)
     int   net_verbatim;              // if true, Beast output connections default to verbatim mode
+    int   beast_sys_timestamp;       // if true, use the system timestamp for Beast output
     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

net_io.c

@@ -399,13 +399,16 @@ static void completeWrite(struct net_writer *writer, void *endptr) {
 //
 // Write raw output in Beast Binary format with Timestamp to TCP clients
 //
+
+#define BEAST_TIMESTAMP Modes.beast_sys_timestamp ? mm->sysTimestampMsg : mm->timestampMsg
+
 static void modesSendBeastVerbatimOutput(struct modesMessage *mm, struct aircraft __attribute__((unused)) *a) {
     // Don't forward mlat messages, unless --forward-mlat is set
     if (mm->source == SOURCE_MLAT && !Modes.forward_mlat)
         return;
 
     // Do verbatim output for all messages
-    writeBeastMessage(&Modes.beast_verbatim_out, mm->timestampMsg, mm->signalLevel, mm->verbatim, mm->msgbits / 8);
+    writeBeastMessage(&Modes.beast_verbatim_out, BEAST_TIMESTAMP, mm->signalLevel, mm->verbatim, mm->msgbits / 8);
 }
 
 static void modesSendBeastCookedOutput(struct modesMessage *mm, struct aircraft *a) {
@@ -422,9 +425,11 @@ static void modesSendBeastCookedOutput(struct modesMessage *mm, struct aircraft
     if ((a && !a->reliable) && !mm->reliable)
         return;
 
-    writeBeastMessage(&Modes.beast_cooked_out, mm->timestampMsg, mm->signalLevel, mm->msg, mm->msgbits / 8);
+    writeBeastMessage(&Modes.beast_cooked_out, BEAST_TIMESTAMP, mm->signalLevel, mm->msg, mm->msgbits / 8);
 }
 
+#undef BEAST_TIMESTAMP
+
 static void writeBeastMessage(struct net_writer *writer, uint64_t timestamp, double signalLevel, unsigned char *msg, int msgLen) {
     char ch;
     int  j;