fix(common): Improve linux port

examples/mqtt/CMakeLists.txt

@@ -1,19 +1,21 @@
-# The following four lines of boilerplate have to be in your project's CMakeLists
-# in this exact order for cmake to work correctly
+# This project serves as a demo to enable using esp-mqtt on ESP platform targets as well as on linux
 cmake_minimum_required(VERSION 3.16)
 
-# (Not part of the boilerplate)
-# This example uses an extra component for common functions such as Wi-Fi and Ethernet connection.
+# For ESP32 platform target
 set(EXTRA_COMPONENT_DIRS $ENV{IDF_PATH}/examples/common_components/protocol_examples_common)
 
 if(${IDF_TARGET} STREQUAL "linux")
+# For linux-target we have two options:
+# - With lwIP (must be defined on command line, e.g. idf.py -DWITH_LWIP=1)
+#     access networking from linux `tap` interface (TAP networking mode)
+# - Without lwIP (must be defined on command line, e.g. idf.py -DWITH_LWIP=0)
+#     no designated interface, accesses user network via linux/socket sys calls
     if(WITH_LWIP STREQUAL 1)
         set(EXTRA_COMPONENT_DIRS $ENV{IDF_PATH}/examples/common_components/protocol_examples_tapif_io
                                  "../../common_components/linux_compat/esp_timer")
         set(COMPONENTS main esp_netif lwip protocol_examples_tapif_io startup esp_hw_support esp_system nvs_flash mqtt esp_timer)
     else()
         list(APPEND EXTRA_COMPONENT_DIRS
-                "../../common_components/linux_compat/freertos"
                 "../../common_components/linux_compat/esp_timer"
                 "$ENV{IDF_PATH}/examples/protocols/linux_stubs/esp_stubs")
         set(COMPONENTS main nvs_flash esp-tls esp_stubs mqtt protocol_examples_common esp_timer)
@@ -21,4 +23,4 @@ if(${IDF_TARGET} STREQUAL "linux")
 endif()
 
 include($ENV{IDF_PATH}/tools/cmake/project.cmake)
-project(mqtt_tcp)
+project(esp_mqtt_demo)

examples/mqtt/README.md

@@ -0,0 +1,41 @@
+# MQTT demo application that runs on linux
+
+## Overview
+
+This is a simple example demonstrating connecting to an MQTT broker, subscribing and publishing some data.
+This example uses IDF build system and could be configured to be build and executed:
+* for any ESP32 family chip
+* for linux target
+
+## How to use example
+
+### Hardware Required
+
+To run this example, you need any ESP32 development board or just PC/virtual machine/container running linux operating system.
+
+### Host build modes
+
+Linux build is supported in these two modes:
+* `WITH_LWIP=0`: Without lwIP component. The project uses linux BSD socket interface to interact with TCP/IP stack. There's no connection phase, we use the host network as users. This mode is often referred to as user-side networking.
+* `WITH_LWIP=1`: Including lwIP component, which is added to the list of required components and compiled on host. In this mode, we have to map the host network (linux TCP/IP stack) to the target network (lwip). We use IDF's [`tapif_io`](https://github.com/espressif/esp-idf/tree/master/examples/common_components/protocol_examples_tapif_io) component to create a network interface, which will be used to pass packets to and from the simulated target. Please refer to the [README](https://github.com/espressif/esp-idf/tree/master/examples/common_components/protocol_examples_tapif_io#readme) for more details about the host side networking.
+
+### Building on linux
+
+1) Configure linux target
+```bash
+idf.py --preview set-target linux
+```
+
+2) Build the project with preferred components (with or without lwip)
+```bash
+idf.py -DWITH_LWIP=0 build  # Building without lwip (user networking)
+idf.py -DWITH_LWIP=1 build  # Building with lwip (TAP networking)
+```
+
+3) Run the project
+
+It is possible to run the project elf file directly, or using `idf.py` monitor target (no need to flash):
+```bash
+idf.py monitor
+```
+idf.py -DWITH_LWIP=0 build  # Building without lwip (user networking)

examples/mqtt/main/CMakeLists.txt

@@ -2,9 +2,3 @@ idf_component_register(SRCS "app_main.cpp"
                     INCLUDE_DIRS ".")
 
 target_compile_options(${COMPONENT_LIB} PRIVATE "-Wno-format")
-
-if(${IDF_TARGET} STREQUAL "linux")
-    if(WITH_LWIP STREQUAL "1")
-        target_compile_definitions(${COMPONENT_LIB} PUBLIC WITH_LWIP)
-    endif()
-endif()

examples/mqtt/main/Kconfig.projbuild

@@ -6,8 +6,4 @@ menu "Example Configuration"
         help
             URL of the broker to connect to
 
-    config BROKER_URL_FROM_STDIN
-        bool
-        default y if BROKER_URL = "FROM_STDIN"
-
 endmenu

examples/mqtt/main/app_main.cpp

@@ -12,15 +12,13 @@
 #include "esp_event.h"
 #include "esp_netif.h"
 #include "protocol_examples_common.h"
-
-#include "freertos/FreeRTOS.h"
-#include "freertos/task.h"
+#include "esp_netif.h"
 #include "esp_system.h"
 
 #include "esp_log.h"
 #include "mqtt_client.h"
 
-static const char *TAG = "MQTT_EXAMPLE";
+static const char *TAG = "esp_mqtt_demo";
 
 
 static void log_error_if_nonzero(const char *message, int error_code)
@@ -109,8 +107,6 @@ static void mqtt_app_start(void)
     esp_mqtt_client_start(client);
 }
 
-#include "esp_netif.h"
-#include "netdb.h"
 
 extern "C" void app_main(void)
 {
@@ -120,10 +116,10 @@ extern "C" void app_main(void)
 
     esp_log_level_set("*", ESP_LOG_INFO);
     esp_log_level_set("mqtt_client", ESP_LOG_VERBOSE);
-    esp_log_level_set("MQTT_EXAMPLE", ESP_LOG_VERBOSE);
-    esp_log_level_set("TRANSPORT_BASE", ESP_LOG_VERBOSE);
+    esp_log_level_set("esp_mqtt_demo", ESP_LOG_VERBOSE);
+    esp_log_level_set("transport_base", ESP_LOG_VERBOSE);
     esp_log_level_set("esp-tls", ESP_LOG_VERBOSE);
-    esp_log_level_set("TRANSPORT", ESP_LOG_VERBOSE);
+    esp_log_level_set("transport", ESP_LOG_VERBOSE);
     esp_log_level_set("outbox", ESP_LOG_VERBOSE);
 
     ESP_ERROR_CHECK(nvs_flash_init());
@@ -135,13 +131,6 @@ extern "C" void app_main(void)
      * examples/protocols/README.md for more information about this function.
      */
     ESP_ERROR_CHECK(example_connect());
-#if CONFIG_IDF_TARGET_LINUX && WITH_LWIP
-    esp_netif_dns_info_t dns;
-    dns.ip.u_addr.ip4.addr = ipaddr_addr("8.8.8.8");
-    dns.ip.type = IPADDR_TYPE_V4;
-    ESP_ERROR_CHECK(esp_netif_set_dns_info(esp_netif_get_handle_from_ifkey("TAP"), ESP_NETIF_DNS_MAIN, &dns));
-#endif
 
     mqtt_app_start();
-    vTaskDelay(pdMS_TO_TICKS(1000));
 }