Implement SNTP client

PUBLISHED_FROM=ac54bcbc81a9ee688e8b90e261172be76a9fbacd

examples/sntp_client/Makefile

@@ -0,0 +1,3 @@
+PROG = sntp_client
+MODULE_CFLAGS = -DMG_ENABLE_SNTP
+include ../examples.mk

examples/sntp_client/sntp_client.c

@@ -0,0 +1,51 @@
+/*
+ * Copyright (c) 2016 Cesanta Software Limited
+ * All rights reserved
+ */
+
+#include "mongoose.h"
+
+static int s_exit_flag = 0;
+static const char *s_default_server = "pool.ntp.org";
+
+static void ev_handler(struct mg_connection *c, int ev, void *ev_data) {
+  struct mg_sntp_message *sm = (struct mg_sntp_message *) ev_data;
+  time_t t;
+  (void) c;
+
+  switch (ev) {
+    case MG_SNTP_REPLY:
+      t = time(NULL);
+      fprintf(stdout, "Local time: %s", ctime(&t));
+      t = (time_t) sm->time;
+      fprintf(stdout, "Time from %s: %s", s_default_server, ctime(&t));
+      s_exit_flag = 1;
+      break;
+    case MG_SNTP_FAILED:
+      fprintf(stderr, "Failed to get time\n");
+      s_exit_flag = 1;
+      break;
+  }
+}
+
+int main() {
+  struct mg_mgr mgr;
+  struct mg_connection *c;
+
+  mg_mgr_init(&mgr, NULL);
+
+  c = mg_sntp_get_time(&mgr, ev_handler, s_default_server);
+
+  if (c == NULL) {
+    fprintf(stderr, "Failed to connect to %s\n", s_default_server);
+    return -1;
+  }
+
+  while (s_exit_flag == 0) {
+    mg_mgr_poll(&mgr, 1000);
+  }
+
+  mg_mgr_free(&mgr);
+
+  return 0;
+}