fix(modem): Make tcp-client example support multiple connections

Author: david-cermak

components/esp_modem/examples/modem_tcp_client/main/command/sock_dce.cpp

@@ -6,6 +6,7 @@
 
 #include <charconv>
 #include <sys/socket.h>
+#include <algorithm>  // for std::find
 #include "esp_vfs.h"
 #include "esp_vfs_eventfd.h"
 
@@ -15,6 +16,25 @@ namespace sock_dce {
 
 constexpr auto const *TAG = "sock_dce";
 
+// Definition of the static member variables
+std::vector<DCE*> DCE::dce_list{};
+bool DCE::network_init = false;
+
+// Constructor - add this DCE instance to the static list
+DCE::DCE(std::shared_ptr<esp_modem::DTE> dte_arg, const esp_modem_dce_config *config)
+    : Module(std::move(dte_arg), config)
+{
+    dce_list.push_back(this);
+}
+
+// Destructor - remove this DCE instance from the static list
+DCE::~DCE()
+{
+    auto it = std::find(dce_list.begin(), dce_list.end(), this);
+    if (it != dce_list.end()) {
+        dce_list.erase(it);
+    }
+}
 
 bool DCE::perform_sock()
 {
@@ -104,6 +124,7 @@ void DCE::close_sock()
         close(sock);
         sock = -1;
     }
+    close(data_ready_fd);
     dte->on_read(nullptr);
     const int retries = 5;
     int i = 0;
@@ -224,15 +245,18 @@ void DCE::start_listening(int port)
 
 bool DCE::connect(std::string host, int port)
 {
+    data_ready_fd = eventfd(0, EFD_SUPPORT_ISR);
+    assert(data_ready_fd > 0);
     dte->on_read(nullptr);
     tcp_close();
     dte->on_read([this](uint8_t *data, size_t len) {
-        this->perform_at(data, len);
+        read_callback(data, len);
         return esp_modem::command_result::TIMEOUT;
     });
     if (!at.start_connecting(host, port)) {
         ESP_LOGE(TAG, "Unable to start connecting");
         dte->on_read(nullptr);
+        close(data_ready_fd);
         return false;
     }
     state = status::CONNECTING;
@@ -241,12 +265,13 @@ bool DCE::connect(std::string host, int port)
 
 bool DCE::init()
 {
+    if (network_init) {
+        return true;
+    }
+    network_init = true;
     esp_vfs_eventfd_config_t config = ESP_VFS_EVENTD_CONFIG_DEFAULT();
     esp_vfs_eventfd_register(&config);
 
-    data_ready_fd = eventfd(0, EFD_SUPPORT_ISR);
-    assert(data_ready_fd > 0);
-
     dte->on_read(nullptr);
     const int retries = 5;
     int i = 0;

components/esp_modem/examples/modem_tcp_client/main/command/sock_dce.hpp

@@ -99,8 +99,14 @@ class Responder {
 };
 
 class DCE : public Module {
-    using Module::Module;
 public:
+    // Constructor and destructor for managing dce_list
+    // explicit GenericModule(std::shared_ptr<DTE> dte, std::unique_ptr<PdpContext> pdp):
+    //     dte(std::move(dte)), pdp(std::move(pdp)) {}
+    // explicit GenericModule(std::shared_ptr<DTE> dte, );
+    //
+    DCE(std::shared_ptr<esp_modem::DTE> dte_arg, const esp_modem_dce_config *config);
+    ~DCE();
 
     /**
      * @brief Opens network in AT command mode
@@ -237,6 +243,15 @@ class DCE : public Module {
     int sock {-1};
     int listen_sock {-1};
     int data_ready_fd {-1};
+    static std::vector<DCE*> dce_list;
+    static bool network_init;
+    static void read_callback(uint8_t *data, size_t len)
+    {
+        for (auto dce : dce_list) {
+            dce->perform_at(data, len);
+        }
+    }
+
 };
 std::unique_ptr<DCE> create(const esp_modem::dce_config *config, std::shared_ptr<esp_modem::DTE> dte);
 }

components/esp_modem/examples/modem_tcp_client/main/modem_client.cpp

@@ -73,6 +73,7 @@ static void mqtt_event_handler(void *handler_args, esp_event_base_t base, int32_
     }
 }
 
+// sock_dce::DCE::dce_list{};
 
 extern "C" void app_main(void)
 {
@@ -104,7 +105,7 @@ extern "C" void app_main(void)
     esp_modem_dce_config_t dce_config = ESP_MODEM_DCE_DEFAULT_CONFIG(CONFIG_EXAMPLE_MODEM_APN);
 
     /* create the DCE and initialize network manually (using AT commands) */
-    auto dce = sock_dce::create(&dce_config, std::move(dte));
+    auto dce = sock_dce::create(&dce_config, dte);
     if (!dce->init()) {
         ESP_LOGE(TAG,  "Failed to setup network");
         return;