feat(modem): Add mqtt example in AT-only mode

Similar to pppos-client, but without PPP mode.
This uses standard mqtt client and a loopback service that forwards the
TCP traffic from localhost to the modem and vice-versa.
(next step is to create a dedicated tcp-transport layer for modem)
Console example uses DCE commandable to demontrate how to handle URC

components/esp_modem/examples/modem_console/CMakeLists.txt

@@ -1,6 +1,7 @@
 # The following lines of boilerplate have to be in your project's CMakeLists
 # in this exact order for cmake to work correctly
-cmake_minimum_required(VERSION 3.5)
+cmake_minimum_required(VERSION 3.8)
+set(CMAKE_CXX_STANDARD 17)
 
 include($ENV{IDF_PATH}/tools/cmake/project.cmake)
 project(modem-console)

components/esp_modem/examples/modem_console/main/CMakeLists.txt

@@ -1,5 +1,6 @@
 idf_component_register(SRCS "modem_console_main.cpp"
                             "console_helper.cpp"
+                            "my_module_dce.cpp"
                             "httpget_handle.c"
                             "ping_handle.c"
                        REQUIRES console esp_http_client nvs_flash

components/esp_modem/examples/modem_console/main/Kconfig.projbuild

@@ -17,7 +17,7 @@ menu "Example Configuration"
 
     choice EXAMPLE_MODEM_DEVICE
         prompt "Choose supported modem device (DCE)"
-        default EXAMPLE_MODEM_DEVICE_BG96
+        default EXAMPLE_MODEM_DEVICE_SHINY
         help
             Select modem device connected to the ESP DTE.
         config EXAMPLE_MODEM_DEVICE_SHINY

components/esp_modem/examples/modem_console/main/modem_console_main.cpp

@@ -89,6 +89,14 @@ void wakeup_modem(void)
     vTaskDelay(pdMS_TO_TICKS(2000));
 }
 
+#ifdef CONFIG_EXAMPLE_MODEM_DEVICE_SHINY
+command_result handle_urc(uint8_t *data, size_t len)
+{
+    ESP_LOG_BUFFER_HEXDUMP("on_read", data, len, ESP_LOG_INFO);
+    return command_result::TIMEOUT;
+}
+#endif
+
 extern "C" void app_main(void)
 {
     static RTC_RODATA_ATTR char apn_rtc[20] = DEFAULT_APN;
@@ -122,19 +130,19 @@ extern "C" void app_main(void)
     dte_config.dte_buffer_size = CONFIG_EXAMPLE_MODEM_UART_RX_BUFFER_SIZE / 2;
     auto uart_dte = create_uart_dte(&dte_config);
 
-#if CONFIG_EXAMPLE_MODEM_DEVICE_SHINY == 1
+#if defined(CONFIG_EXAMPLE_MODEM_DEVICE_SHINY)
     ESP_LOGI(TAG, "Initializing esp_modem for the SHINY module...");
     auto dce = create_shiny_dce(&dce_config, uart_dte, esp_netif);
-#elif CONFIG_EXAMPLE_MODEM_DEVICE_BG96 == 1
+#elif defined(CONFIG_EXAMPLE_MODEM_DEVICE_BG96)
     ESP_LOGI(TAG, "Initializing esp_modem for the BG96 module...");
     auto dce = create_BG96_dce(&dce_config, uart_dte, esp_netif);
-#elif CONFIG_EXAMPLE_MODEM_DEVICE_SIM800 == 1
+#elif defined(CONFIG_EXAMPLE_MODEM_DEVICE_SIM800)
     ESP_LOGI(TAG, "Initializing esp_modem for the SIM800 module...");
     auto dce = create_SIM800_dce(&dce_config, uart_dte, esp_netif);
-#elif CONFIG_EXAMPLE_MODEM_DEVICE_SIM7000 == 1
+#elif defined(CONFIG_EXAMPLE_MODEM_DEVICE_SIM7000)
     ESP_LOGI(TAG, "Initializing esp_modem for the SIM7000 module...");
     auto dce = create_SIM7000_dce(&dce_config, uart_dte, esp_netif);
-#elif CONFIG_EXAMPLE_MODEM_DEVICE_SIM7070 == 1
+#elif defined(CONFIG_EXAMPLE_MODEM_DEVICE_SIM7070)
     ESP_LOGI(TAG, "Initializing esp_modem for the SIM7070 module...");
     auto dce = create_SIM7070_dce(&dce_config, uart_dte, esp_netif);
 #elif CONFIG_EXAMPLE_MODEM_DEVICE_SIM7600 == 1
@@ -303,8 +311,9 @@ extern "C" void app_main(void)
 
     const ConsoleCommand GetOperatorName("get_operator_name", "reads the operator name", no_args, [&](ConsoleCommand * c) {
         std::string operator_name;
+        int act;
         ESP_LOGI(TAG, "Reading operator name...");
-        CHECK_ERR(dce->get_operator_name(operator_name), ESP_LOGI(TAG, "OK. Operator name: %s", operator_name.c_str()));
+        CHECK_ERR(dce->get_operator_name(operator_name, act), ESP_LOGI(TAG, "OK. Operator name: %s", operator_name.c_str()));
     });
 
     const struct GenericCommandArgs {
@@ -356,6 +365,20 @@ extern "C" void app_main(void)
         ESP_LOGI(TAG, "Resetting the module...");
         CHECK_ERR(dce->reset(), ESP_LOGI(TAG, "OK"));
     });
+#ifdef CONFIG_EXAMPLE_MODEM_DEVICE_SHINY
+    const ConsoleCommand HandleURC("urc", "toggle urc handling", no_args, [&](ConsoleCommand * c) {
+        static int cnt = 0;
+        if (++cnt % 2) {
+            ESP_LOGI(TAG, "Adding URC handler");
+            dce->set_on_read(handle_urc);
+        } else {
+            ESP_LOGI(TAG, "URC removed");
+            dce->set_on_read(nullptr);
+        }
+        return 0;
+    });
+#endif
+
     const struct SetApn {
         SetApn(): apn(STR1, nullptr, nullptr, "<apn>", "APN (Access Point Name)") {}
         CommandArgs apn;

components/esp_modem/examples/modem_console/main/my_module_dce.cpp

@@ -0,0 +1,114 @@
+/*
+ * SPDX-FileCopyrightText: 2023 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Unlicense OR CC0-1.0
+ */
+/* Modem console example: Custom DCE
+
+   This example code is in the Public Domain (or CC0 licensed, at your option.)
+
+   Unless required by applicable law or agreed to in writing, this
+   software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
+   CONDITIONS OF ANY KIND, either express or implied.
+*/
+
+#include <cstring>
+#include "cxx_include/esp_modem_api.hpp"
+#include "cxx_include/esp_modem_dce_module.hpp"
+#include "generate/esp_modem_command_declare.inc"
+#include "my_module_dce.hpp"
+
+using namespace esp_modem;
+
+//
+// Define preprocessor's forwarding to dce_commands definitions
+//
+
+// Helper macros to handle multiple arguments of declared API
+#define ARGS0
+#define ARGS1 , p1
+#define ARGS2 , p1 , p2
+#define ARGS3 , p1 , p2 , p3
+#define ARGS4 , p1 , p2 , p3, p4
+#define ARGS5 , p1 , p2 , p3, p4, p5
+#define ARGS6 , p1 , p2 , p3, p4, p5, p6
+
+#define _ARGS(x)  ARGS ## x
+#define ARGS(x)  _ARGS(x)
+
+#define CMD_OK    (1)
+#define CMD_FAIL  (2)
+
+//
+// Repeat all declarations and forward to the AT commands defined in esp_modem::dce_commands:: namespace
+//
+#define ESP_MODEM_DECLARE_DCE_COMMAND(name, return_type, arg_nr, ...) \
+     return_type Shiny::DCE::name(__VA_ARGS__) { return esp_modem::dce_commands::name(this ARGS(arg_nr) ); }
+
+DECLARE_ALL_COMMAND_APIS(return_type name(...) )
+
+#undef ESP_MODEM_DECLARE_DCE_COMMAND
+
+std::unique_ptr<Shiny::DCE> create_shiny_dce(const esp_modem::dce_config *config,
+        std::shared_ptr<esp_modem::DTE> dte,
+        esp_netif_t *netif)
+{
+    return Shiny::Factory::create(config, std::move(dte), netif);
+}
+
+/**
+ * @brief Definition of the command API, which makes the Shiny::DCE "command-able class"
+ * @param cmd Command to send
+ * @param got_line Recv line callback
+ * @param time_ms timeout in ms
+ * @param separator line break separator
+ * @return OK, FAIL or TIMEOUT
+ */
+command_result Shiny::DCE::command(const std::string &cmd, got_line_cb got_line, uint32_t time_ms, const char separator)
+{
+    if (!handling_urc) {
+        return dte->command(cmd, got_line, time_ms, separator);
+    }
+    handle_cmd = got_line;
+    signal.clear(CMD_OK | CMD_FAIL);
+    esp_modem::DTE_Command command{cmd};
+    dte->write(command);
+    signal.wait_any(CMD_OK | CMD_FAIL, time_ms);
+    handle_cmd = nullptr;
+    if (signal.is_any(CMD_OK)) {
+        return esp_modem::command_result::OK;
+    }
+    if (signal.is_any(CMD_FAIL)) {
+        return esp_modem::command_result::FAIL;
+    }
+    return esp_modem::command_result::TIMEOUT;
+}
+
+/**
+ * @brief Handle received data
+ *
+ * @param data Data received from the device
+ * @param len Length of the data
+ * @return standard command return code (OK|FAIL|TIMEOUT)
+ */
+command_result Shiny::DCE::handle_data(uint8_t *data, size_t len)
+{
+    if (std::memchr(data, '\n', len)) {
+        if (handle_urc) {
+            handle_urc(data, len);
+        }
+        if (handle_cmd) {
+            auto ret = handle_cmd(data, len);
+            if (ret == esp_modem::command_result::TIMEOUT) {
+                return command_result::TIMEOUT;
+            }
+            if (ret == esp_modem::command_result::OK) {
+                signal.set(CMD_OK);
+            }
+            if (ret == esp_modem::command_result::FAIL) {
+                signal.set(CMD_FAIL);
+            }
+        }
+    }
+    return command_result::TIMEOUT;
+}

components/esp_modem/examples/modem_console/main/my_module_dce.hpp

@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2022 Espressif Systems (Shanghai) CO LTD
+ * SPDX-FileCopyrightText: 2022-2023 Espressif Systems (Shanghai) CO LTD
  *
  * SPDX-License-Identifier: Unlicense OR CC0-1.0
  */
@@ -11,6 +11,8 @@
 #pragma once
 
 
+#include <utility>
+
 #include "cxx_include/esp_modem_dce_factory.hpp"
 #include "cxx_include/esp_modem_dce_module.hpp"
 
@@ -28,13 +30,84 @@ public:
     }
 };
 
+namespace Shiny {
+
+using namespace esp_modem;
+
+class DCE : public esp_modem::DCE_T<MyShinyModem>, public CommandableIf {
+public:
+    using DCE_T<MyShinyModem>::DCE_T;
+
+    command_result
+    command(const std::string &cmd, got_line_cb got_line, uint32_t time_ms) override
+    {
+        return command(cmd, got_line, time_ms, '\n');
+    }
+
+    command_result
+    command(const std::string &cmd, got_line_cb got_line, uint32_t time_ms, const char separator) override;
+
+    int write(uint8_t *data, size_t len) override
+    {
+        return dte->write(data, len);
+    }
+
+    void on_read(got_line_cb on_data) override
+    {
+        return dte->on_read(on_data);
+    }
+
+#define ESP_MODEM_DECLARE_DCE_COMMAND(name, return_type, num, ...) \
+    esp_modem::return_type name(__VA_ARGS__);
+
+    DECLARE_ALL_COMMAND_APIS(forwards name(...))
+
+#undef ESP_MODEM_DECLARE_DCE_COMMAND
+
+    void set_on_read(esp_modem::got_line_cb on_read_cb)
+    {
+        if (on_read_cb == nullptr) {
+            handling_urc = false;
+            handle_urc = nullptr;
+            dte->on_read(nullptr);
+            return;
+        }
+        handle_urc = std::move(on_read_cb);
+        dte->on_read([this](uint8_t *data, size_t len) {
+            this->handle_data(data, len);
+            return command_result::TIMEOUT;
+        });
+        handling_urc = true;
+    }
+
+private:
+    got_line_cb handle_urc{nullptr};
+    got_line_cb handle_cmd{nullptr};
+    SignalGroup signal;
+    bool handling_urc {false};
+
+    command_result handle_data(uint8_t *data, size_t len);
+
+};
+
+class Factory: public ::esp_modem::dce_factory::Factory {
+public:
+
+    static std::unique_ptr<DCE> create(const esp_modem::dce_config *config,
+                                       std::shared_ptr<esp_modem::DTE> dte,
+                                       esp_netif_t *netif)
+    {
+        return build_generic_DCE<MyShinyModem, DCE, std::unique_ptr<DCE>>(config, std::move(dte), netif);
+    }
+
+};
+
+} // namespace Shiny
+
 /**
  * @brief Helper create method which employs the DCE factory for creating DCE objects templated by a custom module
  * @return unique pointer of the resultant DCE
  */
-std::unique_ptr<esp_modem::DCE> create_shiny_dce(const esp_modem::dce_config *config,
+std::unique_ptr<Shiny::DCE> create_shiny_dce(const esp_modem::dce_config *config,
         std::shared_ptr<esp_modem::DTE> dte,
-        esp_netif_t *netif)
-{
-    return esp_modem::dce_factory::Factory::build_unique<MyShinyModem>(config, std::move(dte), netif);
-}
+        esp_netif_t *netif);