esp-netif: Support non-lwip mode, add test

It is required to define a mandatory dependency on lwip, so we
introduced esp_netif_stack component and made it require lwip, instead
of directly depending on lwip.
This enables building w-out lwip and support other TCP/IP stacks.

.gitlab/CODEOWNERS

@@ -92,6 +92,7 @@
 /components/esp_lcd/                  @esp-idf-codeowners/peripherals
 /components/esp_local_ctrl/           @esp-idf-codeowners/app-utilities
 /components/esp_netif/                @esp-idf-codeowners/network
+/components/esp_netif_stack/          @esp-idf-codeowners/network
 /components/esp_partition/            @esp-idf-codeowners/storage
 /components/esp_phy/                  @esp-idf-codeowners/bluetooth @esp-idf-codeowners/wifi @esp-idf-codeowners/ieee802154
 /components/esp_pm/                   @esp-idf-codeowners/power-management @esp-idf-codeowners/bluetooth @esp-idf-codeowners/wifi

components/esp_netif/CMakeLists.txt

@@ -6,48 +6,52 @@ if(${target} STREQUAL "linux")
     return()
 endif()
 
-set(srcs
-    "esp_netif_handlers.c"
-    "esp_netif_objects.c"
-    "esp_netif_defaults.c"
+set(srcs_lwip
         "lwip/esp_netif_lwip.c"
         "lwip/esp_netif_lwip_defaults.c"
         "lwip/netif/wlanif.c"
         "lwip/netif/ethernetif.c"
         "lwip/netif/esp_pbuf_ref.c")
 
+
+set(srcs
+    "esp_netif_handlers.c"
+    "esp_netif_objects.c"
+    "esp_netif_defaults.c")
+
 set(include_dirs "include")
-set(priv_include_dirs "lwip" "private_include")
+set(priv_include_dirs "private_include")
 
 if(CONFIG_PPP_SUPPORT)
-list(APPEND srcs
-    "lwip/esp_netif_lwip_ppp.c")
+    list(APPEND srcs_lwip lwip/esp_netif_lwip_ppp.c)
 endif()
 
-if(CONFIG_LWIP_NETIF_LOOPBACK)
-list(APPEND srcs
-    "loopback/esp_netif_loopback.c")
-endif()
 
 if(CONFIG_ESP_NETIF_L2_TAP)
-list(APPEND srcs
-    "vfs_l2tap/esp_vfs_l2tap.c")
+    list(APPEND srcs vfs_l2tap/esp_vfs_l2tap.c)
 endif()
 
 if(CONFIG_ESP_NETIF_BRIDGE_EN)
-list(APPEND srcs
-    "lwip/esp_netif_br_glue.c")
+    list(APPEND srcs_lwip lwip/esp_netif_br_glue.c)
+endif()
+
+if(CONFIG_ESP_NETIF_LOOPBACK)
+    list(APPEND srcs loopback/esp_netif_loopback.c)
+elseif(CONFIG_ESP_NETIF_TCPIP_LWIP)
+    list(APPEND srcs ${srcs_lwip})
+    list(APPEND priv_include_dirs lwip)
 endif()
 
 idf_component_register(SRCS "${srcs}"
                     INCLUDE_DIRS "${include_dirs}"
                     PRIV_INCLUDE_DIRS "${priv_include_dirs}"
                     REQUIRES esp_event
-                    PRIV_REQUIRES lwip
+                    PRIV_REQUIRES esp_netif_stack
                     LDFRAGMENTS linker.lf)
 
 if(CONFIG_ESP_NETIF_L2_TAP OR CONFIG_ESP_NETIF_BRIDGE_EN)
     idf_component_optional_requires(PRIVATE esp_eth vfs)
 endif()
 
+
 target_compile_options(${COMPONENT_LIB} PRIVATE "-Wno-format")

components/esp_netif/esp_netif_defaults.c

@@ -5,7 +5,6 @@
  */
 
 #include "esp_netif.h"
-#include "lwip/esp_netif_net_stack.h"
 
 //
 // Purpose of this module is to provide
@@ -31,4 +30,6 @@ const esp_netif_inherent_config_t _g_esp_netif_inherent_ap_config = ESP_NETIF_IN
 
 const esp_netif_inherent_config_t _g_esp_netif_inherent_eth_config = ESP_NETIF_INHERENT_DEFAULT_ETH();
 
+#ifdef CONFIG_PPP_SUPPORT
 const esp_netif_inherent_config_t _g_esp_netif_inherent_ppp_config = ESP_NETIF_INHERENT_DEFAULT_PPP();
+#endif

components/esp_netif/include/esp_netif_defaults.h

@@ -17,8 +17,8 @@ extern "C" {
 // Macros to assemble master configs with partial configs from netif, stack and driver
 //
 
-#ifdef CONFIG_LWIP_ESP_GRATUITOUS_ARP
 // If GARP enabled in menuconfig (default), make it also a default config for common netifs
+#ifdef CONFIG_LWIP_ESP_GRATUITOUS_ARP
 #define ESP_NETIF_DEFAULT_ARP_FLAGS (ESP_NETIF_FLAG_GARP)
 #else
 #define ESP_NETIF_DEFAULT_ARP_FLAGS (0)
@@ -65,6 +65,7 @@ extern "C" {
         .bridge_info = NULL \
     }
 
+#ifdef CONFIG_PPP_SUPPORT
 #define ESP_NETIF_INHERENT_DEFAULT_PPP() \
     {   \
         .flags = ESP_NETIF_FLAG_IS_PPP, \
@@ -77,6 +78,7 @@ extern "C" {
         .route_prio = 20,  \
         .bridge_info = NULL \
     }
+#endif /* CONFIG_PPP_SUPPORT */
 
 
 
@@ -126,6 +128,7 @@ extern "C" {
         .stack = ESP_NETIF_NETSTACK_DEFAULT_WIFI_STA, \
     }
 
+#ifdef CONFIG_PPP_SUPPORT
 /**
 * @brief  Default configuration reference of PPP client
 */
@@ -135,6 +138,7 @@ extern "C" {
         .driver = NULL,                               \
         .stack = ESP_NETIF_NETSTACK_DEFAULT_PPP,      \
     }
+#endif /* CONFIG_PPP_SUPPORT */
 
 /**
  * @brief  Default base config (esp-netif inherent) of WIFI STA
@@ -153,10 +157,12 @@ extern "C" {
  */
 #define ESP_NETIF_BASE_DEFAULT_ETH             &_g_esp_netif_inherent_eth_config
 
+#ifdef CONFIG_PPP_SUPPORT
 /**
  * @brief  Default base config (esp-netif inherent) of ppp interface
  */
 #define ESP_NETIF_BASE_DEFAULT_PPP             &_g_esp_netif_inherent_ppp_config
+#endif
 
 
 #define ESP_NETIF_NETSTACK_DEFAULT_ETH          _g_esp_netif_netstack_default_eth
@@ -165,7 +171,9 @@ extern "C" {
 #ifdef CONFIG_ESP_WIFI_SOFTAP_SUPPORT
 #define ESP_NETIF_NETSTACK_DEFAULT_WIFI_AP      _g_esp_netif_netstack_default_wifi_ap
 #endif
+#ifdef CONFIG_PPP_SUPPORT
 #define ESP_NETIF_NETSTACK_DEFAULT_PPP          _g_esp_netif_netstack_default_ppp
+#endif
 
 //
 // Include default network stacks configs
@@ -179,8 +187,9 @@ extern const esp_netif_netstack_config_t *_g_esp_netif_netstack_default_wifi_sta
 #ifdef CONFIG_ESP_WIFI_SOFTAP_SUPPORT
 extern const esp_netif_netstack_config_t *_g_esp_netif_netstack_default_wifi_ap;
 #endif
+#ifdef CONFIG_PPP_SUPPORT
 extern const esp_netif_netstack_config_t *_g_esp_netif_netstack_default_ppp;
-
+#endif
 //
 // Include default common configs inherent to esp-netif
 //  - These inherent configs are defined in esp_netif_defaults.c and describe
@@ -191,8 +200,9 @@ extern const esp_netif_inherent_config_t _g_esp_netif_inherent_sta_config;
 extern const esp_netif_inherent_config_t _g_esp_netif_inherent_ap_config;
 #endif
 extern const esp_netif_inherent_config_t _g_esp_netif_inherent_eth_config;
+#ifdef CONFIG_PPP_SUPPORT
 extern const esp_netif_inherent_config_t _g_esp_netif_inherent_ppp_config;
-
+#endif
 #ifdef CONFIG_ESP_WIFI_SOFTAP_SUPPORT
 extern const esp_netif_ip_info_t _g_esp_netif_soft_ap_ip;
 #endif

components/esp_netif_stack/CMakeLists.txt

@@ -0,0 +1 @@
+idf_component_register(REQUIRES lwip)

components/esp_netif_stack/README.md

@@ -0,0 +1,20 @@
+# ESP-NETIF stack component
+
+This component is a direct dependency of ESP-NETIF and it defines a required dependency on lwIP.
+
+## Purpose
+
+Purpose of this component is to pull specific TCP/IP stack (lwIP) into the list of dependencies when using component ESP-NETIF.
+By means of `esp_netif_stack` component, we can define these two
+dependency scenarios:
+
+1) Defines a required dependency on lwIP via this component (default)
+2) In case a non-lwip build is required.
+
+## Configure ESP-NETIF for building without lwIP
+
+In order to use ESP-NETIF without lwIP (e.g. when using custom TCP/IP stack), follow these steps
+
+* unselect `CONFIG_ESP_NETIF_TCPIP_LWIP` in `esp_netif` component configuration
+* add a component `esp_netif_stack` to your private component paths
+* register an empty component `idf_component_register()` in the component's CMakeLists.txt

docs/en/api-reference/network/esp_netif.rst

@@ -8,6 +8,8 @@ The purpose of ESP-NETIF library is twofold:
 
 ESP-IDF currently implements ESP-NETIF for the lwIP TCP/IP stack only. However, the adapter itself is TCP/IP implementation agnostic and different implementations are possible.
 
+It is also possible to use a custom TCP/IP stack with ESP-IDF, provided it implements BSD API. For more information on building ESP-IDF without lwIP, please refer to :idf_file:`components/esp_netif_stack/README.md`.
+
 Some ESP-NETIF API functions are intended to be called by application code, for example to get/set interface IP addresses, configure DHCP. Other functions are intended for internal ESP-IDF use by the network driver layer.
 
 In many cases, applications do not need to call ESP-NETIF APIs directly as they are called from the default network event handlers.

examples/protocols/sntp/main/sntp_example_main.c

@@ -9,6 +9,7 @@
 #include <string.h>
 #include <time.h>
 #include <sys/time.h>
+#include <netdb.h>
 #include "freertos/FreeRTOS.h"
 #include "freertos/task.h"
 #include "freertos/event_groups.h"

tools/test_apps/protocols/esp_netif/build_config/main/netif_init_c99.c

@@ -46,10 +46,12 @@ static void test_wifi_init_custom(void)
         s_init_wifi_netif(&esp_netif_config);
     }
 
+#ifdef CONFIG_PPP_SUPPORT
     {
         esp_netif_inherent_config_t esp_netif_config = ESP_NETIF_INHERENT_DEFAULT_PPP();
         s_init_wifi_netif(&esp_netif_config);
     }
+#endif
 }
 
 static void test_common_init_field(void)

tools/test_apps/protocols/esp_netif/build_config/main/netif_init_cpp.cpp

@@ -45,10 +45,12 @@ static void test_wifi_init_custom(void)
         s_init_wifi_netif(esp_netif_config);
     }
 
+#ifdef CONFIG_PPP_SUPPORT
     {
         esp_netif_inherent_config_t esp_netif_config = ESP_NETIF_INHERENT_DEFAULT_PPP();
         s_init_wifi_netif(esp_netif_config);
     }
+#endif
 }
 
 static void test_common_init_field(void)

tools/test_apps/protocols/esp_netif/build_config/sdkconfig.defaults

@@ -0,0 +1 @@
+CONFIG_LWIP_PPP_SUPPORT=y

tools/test_apps/protocols/netif_components/CMakeLists.txt

@@ -6,30 +6,48 @@ cmake_minimum_required(VERSION 3.16)
 
 set(driver_components esp_eth esp_wifi openthread)
 
+# General rules for all these tests
+#   * No optional dependencies
+#   * Forbidden dependencies are only driver components
+set(forbidden_deps ${driver_components})
+set(optional_deps)
 # Check manually if the ESP_NETIF is configured in sdkconfig
+# Note that we cannot use Kconfig values at this stage, and therefore we have to parse
+# the sdkconfig manually for the relevant "config" (CONFIG_TESTAPP_COMPONENT_...),
+# in case the sdkconfig doesn't exist (clean build), we choose the default.
 message(STATUS "Checking if sdkconfig contains CONFIG_TESTAPP_COMPONENT related config:")
 set(config_file "${CMAKE_CURRENT_SOURCE_DIR}/sdkconfig")
 if(EXISTS ${config_file})
-    # If the config file exists, check for the non-default settings - LWIP
+    # If the config file exists, check for the non-default settings - LWIP or ESP-NETIF-without-LWIP
     # otherwise (file missing or defalut settings) go with ESP_NETIF
     file(READ ${config_file} config_file_content)
-    string(FIND "${config_file_content}" "CONFIG_TESTAPP_COMPONENT_LWIP=y" match)
-    if(NOT ${match} EQUAL -1)
-        set(CONFIG_IS_LWIP 1)
+    string(FIND "${config_file_content}" "CONFIG_TESTAPP_COMPONENT_LWIP=y" match_lwip)
+    string(FIND "${config_file_content}" "CONFIG_TESTAPP_COMPONENT_ESP_NETIF_WITHOUT_LWIP=y" match_netif_no_lwip)
+    if(NOT ${match_lwip} EQUAL -1)
+        set(CHECK_DEPS_FOR_LWIP 1)
+    elseif(NOT ${match_netif_no_lwip} EQUAL -1)
+        set(CHECK_DEPS_FOR_ESP_NETIF_WITHOUT_LWIP 1)
     endif()
 endif()
 
-if(CONFIG_IS_LWIP)
-    message(STATUS "CONFIG_TESTAPP_COMPONENT_ESP_LWIP")
+if(CHECK_DEPS_FOR)
+    message(STATUS "CONFIG_TESTAPP_COMPONENT_LWIP")
     set(component_under_test lwip)
     set(expected_build_components lwip)
+elseif(CHECK_DEPS_FOR_ESP_NETIF_WITHOUT_LWIP)
+    message(STATUS "CONFIG_TESTAPP_COMPONENT_ESP_NETIF_WITHOUT_LWIP")
+    set(component_under_test esp_netif)
+    set(expected_build_components esp_netif)
+    list(APPEND optional_deps mbedtls)
+    list(APPEND forbidden_deps lwip)    # lwip mustn't be pulled in, in "esp-netif without lwip" setup
+    list(APPEND EXTRA_COMPONENT_DIRS "esp_netif_stack")
 else()
     message(STATUS "CONFIG_TESTAPP_COMPONENT_ESP_NETIF")
     set(component_under_test esp_netif)
     set(expected_build_components esp_netif lwip)
 endif()
 
-set(COMPONENTS ${component_under_test} main)
+set(COMPONENTS ${component_under_test} main ${optional_deps})
 
 include($ENV{IDF_PATH}/tools/cmake/project.cmake)
 
@@ -45,8 +63,8 @@ foreach(comp ${build_components})
     message(STATUS "${comp}")
 endforeach()
 
-# Check for all driver components, these shall not be included
-foreach(comp ${driver_components})
+# Check for all the components, these shall not be included
+foreach(comp ${forbidden_deps})
     if(${comp} IN_LIST build_components)
         message(FATAL_ERROR "Component ${comp} shall not be included when building only ${component_under_test}")
     else()

tools/test_apps/protocols/netif_components/README.md

@@ -5,6 +5,8 @@
 
 This test application checks the list of components included into the build when:
 * `esp_netif` component is added to the build.
+    - with default network stack, i.e. `lwip`
+    - without lwip using empty `esp-netif-stack` component
 * `lwip`  component is added to the build.
 
 The test checks that driver components are not included in the build
@@ -17,12 +19,12 @@ The test checks that driver components are not included in the build
 
 # Troubleshooting
 
-If you get a build error in this example, please check there's no dependency from the tested component (either `esp_netif` or `lwip`) to any defined driver component.
+If you get a build error in this example, please check there's no dependency from the tested component (either `esp_netif` or `lwip`) to any defined component listed in `${forbidden_deps}`, that must not be included.
 
 Please open the project `CMakeLists.txt` to view the expected dependencies and driver's components that must not be included in the list:
-* CMake variable `driver_components` contains list of driver's components
-* CMake variable `expected_build_components` contains list expected dependecies
+* CMake variable `forbidden_deps` contains list of components that must not be included.
+* CMake variable `expected_build_components` contains list expected dependencies
 
-Note that this project creates `component_deps.dot`, a simpified dependecy graph that could be used to display and troubleshoot component dependencies.
+Note that this project creates `component_deps.dot`, a simplified dependency graph that could be used to display and troubleshoot component dependencies.
 
 Note that this test is executed for one target only in CI (ESP32), but shall work correctly for all IDF supported targets.

tools/test_apps/protocols/netif_components/esp_netif_stack/CMakeLists.txt

@@ -0,0 +1 @@
+idf_component_register()

tools/test_apps/protocols/netif_components/main/Kconfig.projbuild

@@ -11,6 +11,10 @@ menu "TestApp Configuration"
         config TESTAPP_COMPONENT_LWIP
             bool "lwip"
 
+        config TESTAPP_COMPONENT_ESP_NETIF_WITHOUT_LWIP
+            bool "esp_netif without lwip"
+            depends on ESP_NETIF_LOOPBACK
+
     endchoice
 
 endmenu

tools/test_apps/protocols/netif_components/sdkconfig.ci.esp_netif_nolwip

@@ -0,0 +1,2 @@
+CONFIG_TESTAPP_COMPONENT_ESP_NETIF_WITHOUT_LWIP=y
+CONFIG_ESP_NETIF_LOOPBACK=y