fix(net_connect): remove unused utilities and improve resource cleanup

- Remove protocol_examples_utils and addr_from_stdin files
- Add null checks in ethernet shutdown to prevent crashes
- Add proper cleanup in wifi shutdown and error paths
- Update CMakeLists to reflect removed source files

Author: abhik-roy85

components/net_connect/CMakeLists.txt

@@ -3,16 +3,14 @@ idf_build_get_property(target IDF_TARGET)
 if(${target} STREQUAL "linux")
     # Header only library for linux
 
-    idf_component_register(INCLUDE_DIRS include
-                           SRCS protocol_examples_utils.c)
+    idf_component_register(INCLUDE_DIRS include)
     return()
 endif()
 
 set(srcs "stdin_out.c"
          "addr_from_stdin.c"
          "connect.c"
-         "wifi_connect.c"
-         "protocol_examples_utils.c")
+         "wifi_connect.c")
 
 if(CONFIG_NET_CONNECT_PROVIDE_WIFI_CONSOLE_CMD)
     list(APPEND srcs "console_cmd.c")

components/net_connect/addr_from_stdin.c

@@ -128,16 +128,21 @@ static void eth_stop(void)
 /* tear down connection, release resources */
 void net_connect_ethernet_shutdown(void)
 {
-    if (s_semph_get_ip_addrs == NULL) {
-        return;
+#if CONFIG_NET_CONNECT_IPV4
+    if (s_semph_get_ip_addrs != NULL) {
+        vSemaphoreDelete(s_semph_get_ip_addrs);
+        s_semph_get_ip_addrs = NULL;
     }
-    vSemaphoreDelete(s_semph_get_ip_addrs);
-    s_semph_get_ip_addrs = NULL;
+#endif
 #if CONFIG_NET_CONNECT_IPV6
-    vSemaphoreDelete(s_semph_get_ip6_addrs);
-    s_semph_get_ip6_addrs = NULL;
+    if (s_semph_get_ip6_addrs != NULL) {
+        vSemaphoreDelete(s_semph_get_ip6_addrs);
+        s_semph_get_ip6_addrs = NULL;
+    }
 #endif
-    eth_stop();
+    if (s_eth_netif != NULL) {
+        eth_stop();
+    }
 }
 
 esp_err_t net_connect_ethernet_connect(void)