Return error if calling function will block host task

This will prevent applications from hanging forever when calling a blocking function from the host task.

Author: h2zero

src/NimBLEClient.cpp

@@ -270,6 +270,12 @@ bool NimBLEClient::connect(const NimBLEAddress& address, bool deleteAttributes,
         goto error;
     }
 
+    if (!asyncConnect && NimBLEUtils::inHostTask()) {
+        NIMBLE_LOGE(LOG_TAG, "Cannot connect synchronously from host task");
+        rc = BLE_HS_EREJECT;
+        goto error;
+    }
+
     m_connStatus             = CONNECTING;
     m_peerAddress            = address;
     m_config.asyncConnect    = asyncConnect;
@@ -334,6 +340,11 @@ bool NimBLEClient::connect(const NimBLEAddress& address, bool deleteAttributes,
  */
 bool NimBLEClient::secureConnection(bool async) const {
     NIMBLE_LOGD(LOG_TAG, ">> secureConnection()");
+    if (!async && NimBLEUtils::inHostTask()) {
+        NIMBLE_LOGE(LOG_TAG, "Cannot secure connection synchronously from host task");
+        m_lastErr = BLE_HS_EREJECT;
+        return false;
+    }
 
     int rc = 0;
     if (async && !NimBLEDevice::startSecurity(m_connHandle, &rc)) {
@@ -669,6 +680,10 @@ NimBLERemoteService* NimBLEClient::getService(const char* uuid) {
  */
 NimBLERemoteService* NimBLEClient::getService(const NimBLEUUID& uuid) {
     NIMBLE_LOGD(LOG_TAG, ">> getService: uuid: %s", uuid.toString().c_str());
+    if (NimBLEUtils::inHostTask()) {
+        NIMBLE_LOGE(LOG_TAG, "getService cannot be called from host task");
+        return nullptr;
+    }
 
     for (auto& it : m_svcVec) {
         if (it->getUUID() == uuid) {

src/NimBLEDevice.cpp

@@ -879,6 +879,7 @@ void NimBLEDevice::onSync(void) {
  */
 void NimBLEDevice::host_task(void* param) {
     NIMBLE_LOGI(LOG_TAG, "NimBLE Started!");
+    NimBLEUtils::m_hostTaskHandle = ble_npl_get_current_task_id();
     nimble_port_run(); // This function will return only when nimble_port_stop() is executed
     nimble_port_freertos_deinit();
 } // host_task

src/NimBLERemoteCharacteristic.cpp

@@ -155,6 +155,11 @@ bool NimBLERemoteCharacteristic::retrieveDescriptors(NimBLEDescriptorFilter* pFi
  */
 NimBLERemoteDescriptor* NimBLERemoteCharacteristic::getDescriptor(const NimBLEUUID& uuid) const {
     NIMBLE_LOGD(LOG_TAG, ">> getDescriptor: uuid: %s", uuid.toString().c_str());
+    if (NimBLEUtils::inHostTask()) {
+        NIMBLE_LOGE(LOG_TAG, "getDescriptor cannot be called from host task");
+        return nullptr;
+    }
+
     NimBLEUUID             uuidTmp{uuid};
     NimBLETaskData         taskData(const_cast<NimBLERemoteCharacteristic*>(this));
     NimBLEDescriptorFilter filter{nullptr, &uuidTmp, &taskData};

src/NimBLERemoteService.cpp

@@ -75,6 +75,11 @@ NimBLERemoteCharacteristic* NimBLERemoteService::getCharacteristic(const char* u
  */
 NimBLERemoteCharacteristic* NimBLERemoteService::getCharacteristic(const NimBLEUUID& uuid) const {
     NIMBLE_LOGD(LOG_TAG, ">> getCharacteristic: uuid: %s", uuid.toString().c_str());
+    if (NimBLEUtils::inHostTask()) {
+        NIMBLE_LOGE(LOG_TAG, "getCharacteristic cannot be called from host task");
+        return nullptr;
+    }
+
     NimBLERemoteCharacteristic* pChar     = nullptr;
 
     for (const auto& it : m_vChars) {
@@ -116,6 +121,11 @@ NimBLERemoteCharacteristic* NimBLERemoteService::getCharacteristic(const NimBLEU
  * @return A read-only reference to the vector of characteristics retrieved for this service.
  */
 const std::vector<NimBLERemoteCharacteristic*>& NimBLERemoteService::getCharacteristics(bool refresh) const {
+    if (refresh && NimBLEUtils::inHostTask()) {
+        NIMBLE_LOGE(LOG_TAG, "cannot refresh characteristics from host task");
+        return m_vChars;
+    }
+
     if (refresh) {
         deleteCharacteristics();
         retrieveCharacteristics();

src/NimBLERemoteValueAttribute.cpp

@@ -42,6 +42,11 @@ bool NimBLERemoteValueAttribute::writeValue(const uint8_t* data, size_t length,
         goto Done;
     }
 
+    if (NimBLEUtils::inHostTask()) {
+        NIMBLE_LOGE(LOG_TAG, "writeValue cannot be called from the host task");
+        return false;
+    }
+
     do {
         if (length > mtu) {
             NIMBLE_LOGI(LOG_TAG, "writeValue: long write");
@@ -123,6 +128,10 @@ int NimBLERemoteValueAttribute::onWriteCB(uint16_t conn_handle, const ble_gatt_e
  */
 NimBLEAttValue NimBLERemoteValueAttribute::readValue(time_t* timestamp) {
     NIMBLE_LOGD(LOG_TAG, ">> readValue()");
+    if (NimBLEUtils::inHostTask()) {
+        NIMBLE_LOGE(LOG_TAG, "readValue cannot be called from the host task");
+        return NimBLEAttValue();
+    }
 
     NimBLEAttValue      value{};
     const NimBLEClient* pClient    = getClient();

src/NimBLEScan.cpp

@@ -678,6 +678,11 @@ NimBLEScanResults NimBLEScan::getResults(uint32_t duration, bool is_continue) {
         return m_scanResults;
     }
 
+    if (NimBLEUtils::inHostTask()) {
+        NIMBLE_LOGE(LOG_TAG, "Cannot call blocking getResults from NimBLE host task");
+        return m_scanResults;
+    }
+
     NimBLETaskData taskData;
     m_pTaskData = &taskData;
 

src/NimBLEUtils.cpp

@@ -72,6 +72,8 @@
 constexpr uint32_t TASK_BLOCK_BIT = (1 << MYNEWT_VAL(NIMBLE_CPP_FREERTOS_TASK_BLOCK_BIT));
 static const char* LOG_TAG        = "NimBLEUtils";
 
+void* NimBLEUtils::m_hostTaskHandle = nullptr;
+
 /**
  * @brief Construct a NimBLETaskData instance.
  * @param [in] pInstance An instance of the class that will be waiting.
@@ -604,4 +606,21 @@ NimBLEAddress NimBLEUtils::generateAddr(bool nrpa) {
     return NimBLEAddress{addr};
 } // generateAddr
 
+
+/**
+ * @brief Get the handle of the task that is running the NimBLE host.
+ * @return The task handle or nullptr if there was an error.
+ */
+void* NimBLEUtils::getHostTaskHandle() {
+    return m_hostTaskHandle;
+} // getHostTaskHandle
+
+/**
+ * @brief Check if the current task is the NimBLE host task.
+ * @return True if the current task is the host task, false otherwise.
+ */
+bool NimBLEUtils::inHostTask() {
+    return ble_npl_get_current_task_id() == NimBLEUtils::getHostTaskHandle();
+}
+
 #endif // CONFIG_BT_NIMBLE_ENABLED

src/NimBLEUtils.h

@@ -29,17 +29,16 @@
 #  endif
 # endif
 
-#if MYNEWT_VAL(NIMBLE_CPP_DEBUG_ASSERT_ENABLED) && !defined NDEBUG
-void nimble_cpp_assert(const char *file, unsigned line) __attribute((weak, noreturn));
-# define NIMBLE_ATT_VAL_FILE  (__builtin_strrchr(__FILE__, '/') ? \
-                            __builtin_strrchr (__FILE__, '/') + 1 : __FILE__)
-# define NIMBLE_CPP_DEBUG_ASSERT(cond) \
-    if (!(cond)) { \
-        nimble_cpp_assert(NIMBLE_ATT_VAL_FILE, __LINE__); \
-    }
-#else
-# define NIMBLE_CPP_DEBUG_ASSERT(cond) (void(0))
-#endif
+# if MYNEWT_VAL(NIMBLE_CPP_DEBUG_ASSERT_ENABLED) && !defined NDEBUG
+void nimble_cpp_assert(const char* file, unsigned line) __attribute((weak, noreturn));
+#  define NIMBLE_ATT_VAL_FILE (__builtin_strrchr(__FILE__, '/') ? __builtin_strrchr(__FILE__, '/') + 1 : __FILE__)
+#  define NIMBLE_CPP_DEBUG_ASSERT(cond)                     \
+      if (!(cond)) {                                        \
+          nimble_cpp_assert(NIMBLE_ATT_VAL_FILE, __LINE__); \
+      }
+# else
+#  define NIMBLE_CPP_DEBUG_ASSERT(cond) (void(0))
+# endif
 
 # include <string>
 
@@ -74,6 +73,12 @@ class NimBLEUtils {
     static NimBLEAddress generateAddr(bool nrpa);
     static bool          taskWait(const NimBLETaskData& taskData, uint32_t timeout);
     static void          taskRelease(const NimBLETaskData& taskData, int rc = 0);
+    static void*         getHostTaskHandle();
+    static bool          inHostTask();
+
+  private:
+    friend class NimBLEDevice;
+    static void* m_hostTaskHandle;
 };
 
 #endif // CONFIG_BT_NIMBLE_ENABLED