build system: remove lwip from common requirements

lwip was added to common requirements list to provide "sys/socket.h"
header to all components without additional requirements specified.

However, lwip pulls in a lot of dependencies on other components.
This commit removes lwip from common requirements to reduce the number
of components in G1-only apps.

To compensate for this removal, the following changes are made:
- newlib (which is a common requirement) has a public dependency on
  lwip if lwip is present in the build. This ensures that sys/socket.h
  is available as long as lwip component is included into the build.
- lwip is now a public requirement of esp-tls since esp_tls.h includes
  sys/socket.h header.
- lwip is now a public requirement o esp_http_client because
  sys/socket.h is included from esp_http_client.h
- lwip is now a private requirement of esp_wifi for "smartconfig_ack"
- lwip is now a private requirement of mqtt for socket functions
- lwip is now a public requirement of tcp_transport because
  esp_transport_tcp.h includes sys/socket.h header.
- mbedtls checks if lwip component is present in the build. If yes,
  net_sockets.c is added to the build, along with the dependency on
  lwip. Previously lwip was a public requirement of mbedtls
  unconditionally.

system/g1_components test app is updated to reflect the changes

Default public dependencies of a component before and after this
change, except common requirements:

- esp_timer (public dependency of freertos)
- bootloader_support (public dependency of esp_hw_support)
- vfs (public dependency of lwip)
- esp_wifi (public dependency of lwip)
- esp_event (public dependency of esp_wifi)
- esp_netif (public dependency of esp_event)
- esp_eth (public dependency of esp_netif)
- esp_phy (public dependency of esp_wifi)

After:

- esp_timer (public dependency of freertos)
- bootloader_support (public dependency of esp_hw_support)

Altogether, the following components have been always added as
public requirements to all other components, and are not added now
([breaking-change]):

- lwip
- vfs
- esp_wifi
- esp_event
- esp_netif
- esp_eth
- esp_phy

Application components now need to explicitly declare dependencies on
these components.

components/esp-tls/CMakeLists.txt

@@ -12,8 +12,10 @@ endif()
 idf_component_register(SRCS "${srcs}"
                     INCLUDE_DIRS . esp-tls-crypto
                     PRIV_INCLUDE_DIRS "private_include"
-                    REQUIRES mbedtls
+                    # lwip and mbedtls are public requirements becasue esp_tls.h
-                    PRIV_REQUIRES lwip http_parser)
+                    # includes sys/socket.h and mbedtls header files.
+                    REQUIRES mbedtls lwip
+                    PRIV_REQUIRES http_parser)
 
 if(CONFIG_ESP_TLS_USING_WOLFSSL)
     idf_component_get_property(wolfssl esp-wolfssl COMPONENT_LIB)

components/esp_http_client/CMakeLists.txt

@@ -4,5 +4,6 @@ idf_component_register(SRCS "esp_http_client.c"
                             "lib/http_utils.c"
                     INCLUDE_DIRS "include"
                     PRIV_INCLUDE_DIRS "lib/include"
-                    REQUIRES http_parser
+                    # lwip is a public requirement because esp_http_client.h includes sys/socket.h
+                    REQUIRES http_parser lwip
                     PRIV_REQUIRES tcp_transport)

components/esp_wifi/CMakeLists.txt

@@ -31,7 +31,7 @@ idf_component_register(SRCS "${srcs}"
                     INCLUDE_DIRS "include"
                     REQUIRES esp_event esp_phy
                     PRIV_REQUIRES driver esptool_py esp_netif esp_pm esp_timer nvs_flash
-                                  wpa_supplicant hal ${extra_priv_requires}
+                                  wpa_supplicant hal lwip ${extra_priv_requires}
                     LDFRAGMENTS "${ldfragments}")
 
 if(CONFIG_ESP32_WIFI_ENABLED)

components/mbedtls/CMakeLists.txt

@@ -17,10 +17,17 @@ endif()
 
 idf_component_register(SRCS "${mbedtls_srcs}"
     INCLUDE_DIRS "${mbedtls_include_dirs}"
-    REQUIRES lwip
     PRIV_REQUIRES "${priv_requires}"
     )
 
+# Determine the type of mbedtls component library
+if(mbedtls_srcs STREQUAL "")
+    # For no sources in component library we must use "INTERFACE"
+    set(linkage_type INTERFACE)
+else()
+    set(linkage_type PUBLIC)
+endif()
+
 
 if(CONFIG_MBEDTLS_CERTIFICATE_BUNDLE)
     set(bundle_name "x509_crt_bundle")
@@ -103,8 +110,7 @@ endif()
 
 set(mbedtls_targets mbedtls mbedcrypto mbedx509)
 
-set(mbedtls_target_sources "${COMPONENT_DIR}/port/mbedtls_debug.c"
+set(mbedtls_target_sources "${COMPONENT_DIR}/port/mbedtls_debug.c")
-                           "${COMPONENT_DIR}/port/net_sockets.c")
 
 if(CONFIG_MBEDTLS_DYNAMIC_BUFFER)
 set(mbedtls_target_sources ${mbedtls_target_sources}
@@ -114,6 +120,15 @@ set(mbedtls_target_sources ${mbedtls_target_sources}
                            "${COMPONENT_DIR}/port/dynamic/esp_ssl_tls.c")
 endif()
 
+# net_sockets.c should only be compiled if BSD socket functions are available.
+# Do this by checking if lwip component is included into the build.
+idf_build_get_property(build_components BUILD_COMPONENTS)
+if(lwip IN_LIST build_components)
+    list(APPEND mbedtls_target_sources "${COMPONENT_DIR}/port/net_sockets.c")
+    idf_component_get_property(lwip_lib lwip COMPONENT_LIB)
+    target_link_libraries(${COMPONENT_LIB} ${linkage_type} ${lwip_lib})
+endif()
+
 # Add port files to mbedtls targets
 target_sources(mbedtls PRIVATE ${mbedtls_target_sources})
 
@@ -240,14 +255,6 @@ set_property(TARGET mbedcrypto APPEND PROPERTY LINK_INTERFACE_LIBRARIES mbedtls)
 set_property(TARGET mbedcrypto APPEND PROPERTY LINK_LIBRARIES idf::driver idf::${target})
 set_property(TARGET mbedcrypto APPEND PROPERTY INTERFACE_LINK_LIBRARIES idf::driver idf::${target})
 
-# Link mbedtls libraries to component library
-if(mbedtls_srcs STREQUAL "")
-    # For no sources in component library we must use "INTERFACE"
-    set(linkage_type INTERFACE)
-else()
-    set(linkage_type PUBLIC)
-endif()
-
 target_link_libraries(${COMPONENT_LIB} ${linkage_type} ${mbedtls_targets})
 
 if(CONFIG_ESP_TLS_USE_DS_PERIPHERAL)

components/mqtt/CMakeLists.txt

@@ -4,6 +4,7 @@ idf_component_register(SRCS "esp-mqtt/mqtt_client.c"
                             "esp-mqtt/lib/platform_esp32_idf.c"
                     INCLUDE_DIRS esp-mqtt/include
                     PRIV_INCLUDE_DIRS "esp-mqtt/lib/include"
+                    PRIV_REQUIRES lwip
                     )
 
 if(TEST_BUILD)

components/newlib/CMakeLists.txt

@@ -53,3 +53,7 @@ if(CONFIG_NEWLIB_NANO_FORMAT)
 endif()
 
 add_subdirectory(port)
+
+# if lwip is included in the build, add it as a public requirement so that
+# #include <sys/socket.h> works without any special provisions.
+idf_component_optional_requires(PUBLIC lwip)

components/tcp_transport/CMakeLists.txt

@@ -11,4 +11,4 @@ endif()
 idf_component_register(SRCS "${srcs}"
                     INCLUDE_DIRS "include"
                     PRIV_INCLUDE_DIRS "private_include"
-                    REQUIRES esp-tls)
+                    REQUIRES esp-tls lwip)

tools/cmake/build.cmake

@@ -162,9 +162,8 @@ function(__build_init idf_path)
     else()
         # Set components required by all other components in the build
         #
-        # - lwip is here so that #include <sys/socket.h> works without any special provisions
         # - esp_hw_support is here for backward compatibility
-        set(requires_common cxx newlib freertos esp_hw_support heap log lwip soc hal esp_rom esp_common esp_system)
+        set(requires_common cxx newlib freertos esp_hw_support heap log soc hal esp_rom esp_common esp_system)
         idf_build_set_property(__COMPONENT_REQUIRES_COMMON "${requires_common}")
     endif()
 

tools/test_apps/system/g1_components/CMakeLists.txt

@@ -41,15 +41,6 @@ set(extra_components_which_shouldnt_be_included
     #   Figure out if these components can exist without a dependency on efuse.
     #   If not, see if esp_hw_support can provide minimal efuse component replacement in G1 build.
     efuse
-    # esp_eth is a dependency of esp_netif, esp_event, lwip
-    #   Once they are removed from G1, esp_eth will be removed as well.
-    esp_eth
-    # esp_event is a dependency of esp_wifi, esp_eth. Both should be removed from G1.
-    esp_event
-    # esp_netif is a dependency of lwip and esp_event, should disappear once lwip is removed.
-    esp_netif
-    # esp_phy is a dependency of esp_wifi.
-    esp_phy
     # esp_pm is pulled in by freertos, can be made a weak dependency
     #   conditional on related Kconfig option. It is also used by esp_wifi, driver, mbedtls,
     #   all of which should be removed from G1-only build.
@@ -59,30 +50,17 @@ set(extra_components_which_shouldnt_be_included
     # esp_timer is a dependency of freertos, esp_event, esp_wifi, driver.
     #   For freertos, it can be made a weak dependency conditional on FREERTOS_RUN_TIME_STATS_USING_ESP_TIMER
     esp_timer
-    # esp_wifi is a dependency of lwip.
-    #   [refactor-todo]: investigate making esp_wifi a conditional dependency.
-    esp_wifi
     # esptool_py is a dependency of bootloader, esp_wifi, app_update, partition_table, all of which
     #   should be removed from G1-only build.
     esptool_py
-    # lwip is a common component due to "sys/socket.h" header.
-    #   [refactor-todo] consider adding a system-level sys/socket.h in newlib instead
-    lwip
     # mbedtls is a dependency of bootloader_support (plus other easier-to-remove ones)
     #   it is hard to make it conditional, need to remove bootloader_support.
     mbedtls
-    # nvs_flash is required by:
-    #   esp_wifi, esp_phy — both should be removed
-    nvs_flash
     # partition_table is pulled in by app_update, esptool_py, bootloader; all to be removed
     partition_table
     # pthread is required by esp_system (for initialization only, can be made a weak dependency)
     #   and cxx. See also [refactor-todo] about cxx, can it work without pthread?
     pthread
-    # vfs is a dependency of lwip. It can be made conditional, while lwip is still a common component.
-    vfs
-    # wpa_supplicant is a dependency of esp_wifi, which is to be removed from G1-only build
-    wpa_supplicant
 )
 
 set(expected_components