From 53dc930115123a69b7a43afc07b80cc85e598ec8 Mon Sep 17 00:00:00 2001
From: mcuw <112967559+mcuw@users.noreply.github.com>
Date: Fri, 28 Aug 2026 22:18:27 +0200
Subject: [PATCH] chore: add common ot_coap_client component which contains a
 function to ensure that CoAP is started

---
 ot_br/components/ot_br_web_api/CMakeLists.txt |  2 +-
 .../ot_br_web_api/ot_br_web_api_coap_client.c |  9 ++++--
 .../components/ot_coap_client/CMakeLists.txt  |  5 +++
 .../ot_coap_client/include/ot_coap_client.h   | 31 +++++++++++++++++++
 .../ot_coap_client/ot_coap_client.c           | 24 ++++++++++++++
 5 files changed, 67 insertions(+), 4 deletions(-)
 create mode 100644 ot_br/components/ot_coap_client/CMakeLists.txt
 create mode 100644 ot_br/components/ot_coap_client/include/ot_coap_client.h
 create mode 100644 ot_br/components/ot_coap_client/ot_coap_client.c

diff --git a/ot_br/components/ot_br_web_api/CMakeLists.txt b/ot_br/components/ot_br_web_api/CMakeLists.txt
index e1e1d24..29bbd47 100644
--- a/ot_br/components/ot_br_web_api/CMakeLists.txt
+++ b/ot_br/components/ot_br_web_api/CMakeLists.txt
@@ -1,5 +1,5 @@
 idf_component_register(
     SRCS "ot_br_web_api.c" "ot_br_web_api_auth.c" "ot_br_web_api_handlers.c" "ot_br_web_api_ota.c" "ot_br_web_api_static.c" "ot_br_web_api_setup_mode.c" "ot_br_web_api_command.c" "ot_br_web_api_coap_client.c"
     INCLUDE_DIRS "include"
-    REQUIRES esp_http_server openthread nvs_flash esp_hw_support esp_app_format mbedtls espressif__cjson app_update esp_https_ota esp_http_client joltwallet__littlefs esp_driver_gpio esp_timer
+    REQUIRES esp_http_server openthread nvs_flash esp_hw_support esp_app_format mbedtls espressif__cjson app_update esp_https_ota esp_http_client joltwallet__littlefs esp_driver_gpio esp_timer ot_coap_client
 )
\ No newline at end of file
diff --git a/ot_br/components/ot_br_web_api/ot_br_web_api_coap_client.c b/ot_br/components/ot_br_web_api/ot_br_web_api_coap_client.c
index 3e6ac47..bef3211 100644
--- a/ot_br/components/ot_br_web_api/ot_br_web_api_coap_client.c
+++ b/ot_br/components/ot_br_web_api/ot_br_web_api_coap_client.c
@@ -9,6 +9,8 @@
 #include "openthread/netdiag.h"
 #include "freertos/semphr.h"
 
+#include "ot_coap_client.h"
+
 static const char *TAG = "ot_br_coap_client";
 static SemaphoreHandle_t s_response_sem = NULL;
 static otCoapCode s_last_response_code = 0;
@@ -43,12 +45,13 @@ void ot_br_coap_client_init(void)
     s_response_sem = xSemaphoreCreateBinary();
 
     otInstance *instance = esp_openthread_get_instance();
+
     esp_openthread_lock_acquire(portMAX_DELAY);
-    otError err = otCoapStart(instance, OT_DEFAULT_COAP_PORT);
+    esp_err_t err = ot_coap_client_ensure_started(instance);
     esp_openthread_lock_release();
 
-    if (err != OT_ERROR_NONE && err != OT_ERROR_ALREADY) {
-        ESP_LOGE("ot_br_coap_client", "otCoapStart fehlgeschlagen: %d", err);
+    if (err != ESP_OK) {
+        ESP_LOGE(TAG, "Failed to start CoAP-Client");
     }
 }
 
diff --git a/ot_br/components/ot_coap_client/CMakeLists.txt b/ot_br/components/ot_coap_client/CMakeLists.txt
new file mode 100644
index 0000000..f7202e8
--- /dev/null
+++ b/ot_br/components/ot_coap_client/CMakeLists.txt
@@ -0,0 +1,5 @@
+idf_component_register(
+    SRCS "ot_coap_client.c"
+    INCLUDE_DIRS "include"
+    REQUIRES driver openthread
+)
\ No newline at end of file
diff --git a/ot_br/components/ot_coap_client/include/ot_coap_client.h b/ot_br/components/ot_coap_client/include/ot_coap_client.h
new file mode 100644
index 0000000..ddb191a
--- /dev/null
+++ b/ot_br/components/ot_coap_client/include/ot_coap_client.h
@@ -0,0 +1,31 @@
+#pragma once
+
+#include "esp_err.h"
+#include "openthread/instance.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief Ensure the OpenThread CoAP layer's UDP socket is open.
+ *
+ * otCoapSendRequest() requires otCoapStart() to have been called at
+ * least once -- even for pure client usage that never registers a
+ * resource -- otherwise it fails with OT_ERROR_INVALID_STATE. This
+ * wrapper makes that call exactly once per boot and is safe to call
+ * from every place that is about to send a CoAP request.
+ *
+ * Must be called with the OpenThread lock already held by the caller
+ * (esp_openthread_lock_acquire()), same as any other otXxx() call.
+ *
+ * @param instance  A valid OpenThread instance (e.g. from
+ *                  esp_openthread_get_instance()).
+ * @return ESP_OK if the CoAP layer is started (either just now or
+ *         already before), ESP_FAIL if otCoapStart() itself failed.
+ */
+esp_err_t ot_coap_client_ensure_started(otInstance *instance);
+
+#ifdef __cplusplus
+}
+#endif
diff --git a/ot_br/components/ot_coap_client/ot_coap_client.c b/ot_br/components/ot_coap_client/ot_coap_client.c
new file mode 100644
index 0000000..967ea21
--- /dev/null
+++ b/ot_br/components/ot_coap_client/ot_coap_client.c
@@ -0,0 +1,24 @@
+#include "ot_coap_client.h"
+
+#include "esp_log.h"
+#include "openthread/coap.h"
+
+static const char *TAG = "ot_coap_client";
+static bool s_coap_started = false;
+
+esp_err_t ot_coap_client_ensure_started(otInstance *instance)
+{
+    if (s_coap_started) {
+        return ESP_OK;
+    }
+
+    otError error = otCoapStart(instance, OT_DEFAULT_COAP_PORT);
+    if (error != OT_ERROR_NONE && error != OT_ERROR_ALREADY) {
+        ESP_LOGE(TAG, "otCoapStart failed: %s", otThreadErrorToString(error));
+        return ESP_FAIL;
+    }
+
+    s_coap_started = true;
+    ESP_LOGI(TAG, "CoAP client layer started on port %d", OT_DEFAULT_COAP_PORT);
+    return ESP_OK;
+}
\ No newline at end of file