read returning zero not an error for serial clients

net_io.c

@@ -318,6 +318,7 @@ static struct client *createSocketClient(struct net_service *service, int fd) {
     if ((c->fd == Modes.beast_fd) && (Modes.sdr_type == SDR_MODESBEAST || Modes.sdr_type == SDR_GNS)) {
         /* Message from a local connected Modes-S beast or GNS5894 are passed off the internet */
         c->remote = 0;
+        c->serial = 1;
     }
 
     //fprintf(stderr, "c->receiverId: %016"PRIx64"\n", c->receiverId);
@@ -4459,7 +4460,7 @@ static int readClient(struct client *c, int64_t now) {
             return 0;
         }
         // Other errors
-        if (!c->remote) {
+        if (c->serial) {
             fprintf(stderr, "Serial client read error: %s\n", strerror(err));
         }
         if (Modes.debug_net) {
@@ -4473,6 +4474,11 @@ static int readClient(struct client *c, int64_t now) {
 
     // End of file
     if (nread == 0) {
+        if (c->serial) {
+            // for serial this just means we're doing non-blocking reads and there are no bytes available
+            return 0;
+        }
+
         if (c->con) {
             if (Modes.synthetic_now) {
                 Modes.synthetic_now = 0;
@@ -5399,7 +5405,7 @@ void modesNetPeriodicWork(void) {
 
     int64_t wait_ms;
     if (Modes.sdr_type == SDR_MODESBEAST || Modes.sdr_type == SDR_GNS) {
-        wait_ms = 20;
+        wait_ms = 100;
     } else if (Modes.sdr_type != SDR_NONE) {
         // NO WAIT WHEN USING AN SDR !! IMPORTANT !!
         wait_ms = 0;

net_io.h

@@ -100,6 +100,7 @@ struct client
     int fd; // File descriptor
     int8_t bufferToProcess;
     int8_t remote;
+    int8_t serial;
     int8_t bContinue;
     int8_t discard;
     int8_t processing;