examples: common connect to also support no connection flow if no inteface chosen

This is useful for testing if there's no need for external network and connection

examples/common_components/protocol_examples_common/Kconfig.projbuild

@@ -177,6 +177,7 @@ menu "Example Connection Configuration"
     config EXAMPLE_CONNECT_IPV6
         bool "Obtain IPv6 address"
         default y
+        depends on EXAMPLE_CONNECT_WIFI || EXAMPLE_CONNECT_ETHERNET
         help
             By default, examples will wait until IPv4 and IPv6 local link addresses are obtained.
             Disable this option if the network does not support IPv6.

examples/common_components/protocol_examples_common/connect.c

@@ -43,9 +43,10 @@
 #define NR_OF_IP_ADDRESSES_TO_WAIT_FOR (s_active_interfaces)
 #endif
 
+#define EXAMPLE_DO_CONNECT CONFIG_EXAMPLE_CONNECT_WIFI || CONFIG_EXAMPLE_CONNECT_ETHERNET
+
 static int s_active_interfaces = 0;
 static xSemaphoreHandle s_semph_get_ip_addrs;
-static esp_ip4_addr_t s_ip_addr;
 static esp_netif_t *s_example_esp_netif = NULL;
 
 #ifdef CONFIG_EXAMPLE_CONNECT_IPV6
@@ -102,7 +103,11 @@ static void start(void)
     s_example_esp_netif = NULL;
 #endif
 
+#if EXAMPLE_DO_CONNECT
+    /* create semaphore if at least one interface is active */
     s_semph_get_ip_addrs = xSemaphoreCreateCounting(NR_OF_IP_ADDRESSES_TO_WAIT_FOR, 0);
+#endif
+
 }
 
 /* tear down connection, release resources */
@@ -119,6 +124,9 @@ static void stop(void)
 #endif
 }
 
+#if EXAMPLE_DO_CONNECT
+static esp_ip4_addr_t s_ip_addr;
+
 static void on_got_ip(void *arg, esp_event_base_t event_base,
                       int32_t event_id, void *event_data)
 {
@@ -131,6 +139,7 @@ static void on_got_ip(void *arg, esp_event_base_t event_base,
     memcpy(&s_ip_addr, &event->ip_info.ip, sizeof(s_ip_addr));
     xSemaphoreGive(s_semph_get_ip_addrs);
 }
+#endif
 
 #ifdef CONFIG_EXAMPLE_CONNECT_IPV6
 
@@ -155,9 +164,11 @@ static void on_got_ipv6(void *arg, esp_event_base_t event_base,
 
 esp_err_t example_connect(void)
 {
+#if EXAMPLE_DO_CONNECT
     if (s_semph_get_ip_addrs != NULL) {
         return ESP_ERR_INVALID_STATE;
     }
+#endif
     start();
     ESP_ERROR_CHECK(esp_register_shutdown_handler(&stop));
     ESP_LOGI(TAG, "Waiting for IP(s)");

examples/common_components/protocol_examples_common/include/protocol_examples_common.h

@@ -24,6 +24,11 @@ extern "C" {
 #define EXAMPLE_INTERFACE get_example_netif()
 #endif
 
+#if !defined (CONFIG_EXAMPLE_CONNECT_ETHERNET) && !defined (CONFIG_EXAMPLE_CONNECT_WIFI)
+// This is useful for some tests which do not need a network connection
+#define EXAMPLE_INTERFACE NULL
+#endif
+
 /**
  * @brief Configure Wi-Fi or Ethernet, connect, wait for IP
  *