Merge branch 'bugfix/sntp_example_docs' into 'master'

sntp example - updated ntp over dhcp code/comments (GitHub PR)

Closes IDFGH-6147

See merge request espressif/esp-idf!15897

examples/protocols/sntp/README.md

@@ -20,6 +20,16 @@ Open the project configuration menu (`idf.py menuconfig`):
 When this example boots first time after ESP32 is reset, it connects to WiFi and obtains time using SNTP.
 See `initialize_sntp` function for details.
 
+## Obtaining time using LwIP SNTP-over-DHCP module
+
+NTP server addresses could be automatically aquired via DHCP server option 42. This could be usefull on closed environments where public NTPs are not accessible
+or to prefer local servers and reduce traffic to the outer world.
+See following menuconfig options:
+ * `Component config-->LWIP-->SNTP-->Maximum number of NTP servers`
+ * `Component config-->LWIP-->SNTP-->Request NTP servers from DHCP`
+ * `Component config-->LWIP-->SNTP-->Maximum number of NTP servers aquired via DHCP`
+ * `Component config-->LWIP-->Enable LWIP Debug-->Enable SNTP debug messages`
+
 ## Timekeeping
 
 Once time is synchronized, ESP32 will perform timekeeping using built-in timers.

examples/protocols/sntp/example_test.py

@@ -15,7 +15,7 @@ def test_examples_sntp(env, extra_data):
 
     dut.expect_all('Time is not set yet. Connecting to WiFi and getting time over NTP.',
                    'Initializing SNTP',
-                   'Waiting for system time to be set... (1/10)',
+                   re.compile(r'Waiting for system time to be set... \(\d+/\d+\)'),
                    'Notification of a time synchronization event',
                    timeout=60)
 

examples/protocols/sntp/main/Kconfig.projbuild

@@ -1,5 +1,11 @@
 menu "Example Configuration"
 
+    config SNTP_TIME_SERVER
+        string "SNTP server name"
+        default "pool.ntp.org"
+        help
+            Hostname of the main SNTP server.
+
     choice SNTP_TIME_SYNC_METHOD
         prompt "Time synchronization method"
         default SNTP_TIME_SYNC_METHOD_IMMED

examples/protocols/sntp/main/sntp_example_main.c

@@ -23,6 +23,10 @@
 
 static const char *TAG = "example";
 
+#ifndef INET6_ADDRSTRLEN
+#define INET6_ADDRSTRLEN 48
+#endif
+
 /* Variable holding number of times ESP32 restarted since first boot.
  * It is placed into RTC memory using RTC_DATA_ATTR and
  * maintains its value when ESP32 wakes from deep sleep.
@@ -124,10 +128,15 @@ static void obtain_time(void)
 
     /**
      * NTP server address could be aquired via DHCP,
-     * see LWIP_DHCP_GET_NTP_SRV menuconfig option
+     * see following menuconfig options:
+     * 'LWIP_DHCP_GET_NTP_SRV' - enable STNP over DHCP
+     * 'LWIP_SNTP_DEBUG' - enable debugging messages
+     *
+     * NOTE: This call should be made BEFORE esp aquires IP address from DHCP,
+     * otherwise NTP option would be rejected by default.
      */
 #ifdef LWIP_DHCP_GET_NTP_SRV
-    sntp_servermode_dhcp(1);
+    sntp_servermode_dhcp(1);      // accept NTP offers from DHCP server, if any
 #endif
 
     /* This helper function configures Wi-Fi or Ethernet, as selected in menuconfig.
@@ -142,7 +151,7 @@ static void obtain_time(void)
     time_t now = 0;
     struct tm timeinfo = { 0 };
     int retry = 0;
-    const int retry_count = 10;
+    const int retry_count = 15;
     while (sntp_get_sync_status() == SNTP_SYNC_STATUS_RESET && ++retry < retry_count) {
         ESP_LOGI(TAG, "Waiting for system time to be set... (%d/%d)", retry, retry_count);
         vTaskDelay(2000 / portTICK_PERIOD_MS);
@@ -157,10 +166,44 @@ static void initialize_sntp(void)
 {
     ESP_LOGI(TAG, "Initializing SNTP");
     sntp_setoperatingmode(SNTP_OPMODE_POLL);
-    sntp_setservername(0, "pool.ntp.org");
+
+/*
+ * If 'NTP over DHCP' is enabled, we set dynamic pool address
+ * as a 'secondary' server. It will act as a fallback server in case that address
+ * provided via NTP over DHCP is not accessible
+ */
+#if LWIP_DHCP_GET_NTP_SRV && SNTP_MAX_SERVERS > 1
+    sntp_setservername(1, "pool.ntp.org");
+
+#if LWIP_IPV6 && SNTP_MAX_SERVERS > 2          // statically assigned IPv6 address is also possible
+    ip_addr_t ip6;
+    if (ipaddr_aton("2a01:3f7::1", &ip6)) {    // ipv6 ntp source "ntp.netnod.se"
+        sntp_setserver(2, &ip6);
+    }
+#endif  /* LWIP_IPV6 */
+
+#else   /* LWIP_DHCP_GET_NTP_SRV && (SNTP_MAX_SERVERS > 1) */
+    // otherwise, use DNS address from a pool
+    sntp_setservername(0, CONFIG_SNTP_TIME_SERVER);
+#endif
+
     sntp_set_time_sync_notification_cb(time_sync_notification_cb);
 #ifdef CONFIG_SNTP_TIME_SYNC_METHOD_SMOOTH
     sntp_set_sync_mode(SNTP_SYNC_MODE_SMOOTH);
 #endif
     sntp_init();
+
+    ESP_LOGI(TAG, "List of configured NTP servers:");
+
+    for (uint8_t i = 0; i < SNTP_MAX_SERVERS; ++i){
+        if (sntp_getservername(i)){
+            ESP_LOGI(TAG, "server %d: %s", i, sntp_getservername(i));
+        } else {
+            // we have either IPv4 or IPv6 address, let's print it
+            char buff[INET6_ADDRSTRLEN];
+            ip_addr_t const *ip = sntp_getserver(i);
+            if (ipaddr_ntoa_r(ip, buff, INET6_ADDRSTRLEN) != NULL)
+                ESP_LOGI(TAG, "server %d: %s", i, buff);
+        }
+    }
 }