Update Zephyr examples

examples/zephyr/mqtt-aws-client/src/main.c

@@ -50,14 +50,14 @@ static void fn(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
   }
 }
 
-// We have no valid system time(), and we need it for TLS. Implement it
-time_t time(time_t *tp) {
-  time_t t = s_boot_timestamp + k_uptime_get() / 1000;
+// example system time()-like function
+time_t ourtime(time_t *tp) {
+  time_t t = s_boot_timestamp + mg_millis() / 1000;
   if (tp != NULL) *tp = t;
   return t;
 }
 
-// SNTP callback. Modifies s_boot_timestamp, to make time() correct
+// SNTP callback. Modifies s_boot_timestamp, to make ourtime() correct
 static void sfn(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
   if (ev == MG_EV_SNTP_TIME) {
     int64_t t = *(int64_t *) ev_data;
@@ -85,7 +85,23 @@ static void timer_fn(void *arg) {
   if (s_boot_timestamp < 9999) mg_sntp_request(s_sntp_conn);
 }
 
+// Zephyr: Define a semaphore and network management callback to be able to wait
+// until our IP address is ready. The main function will start and block on this
+// semaphore until this event handler releases it when the network is ready
+K_SEM_DEFINE(run, 0, 1);
+
+static void zeh(struct net_mgmt_event_callback *cb, uint32_t mgmt_event,
+                struct net_if *iface) {
+  if (mgmt_event == NET_EVENT_L4_CONNECTED) k_sem_give(&run);
+}
+
 int main(int argc, char *argv[]) {
+  // Zephyr: Register the network management callback and block on the semaphore
+  struct net_mgmt_event_callback ncb;
+  net_mgmt_init_event_callback(&ncb, zeh, NET_EVENT_L4_CONNECTED);
+  net_mgmt_add_event_callback(&ncb);
+  k_sem_take(&run, K_FOREVER);
+
   mg_log_set(MG_LL_DEBUG);
 
   mg_mgr_init(&mgr);