[Bugfix] NimBLEDevice::createServer can crash if stack not initialized.

This removes the gatts/gap reset calls from NimBLEDevice::createServer so that it can be safely used before initializing the stack.

This also deprecates NimBLEService::start the the services will now be added/created only when the server is started.

Author: h2zero

src/NimBLEDevice.cpp

@@ -125,9 +125,6 @@ extern "C" int ble_vhci_disc_duplicate_mode_enable(int mode);
 NimBLEServer* NimBLEDevice::createServer() {
     if (NimBLEDevice::m_pServer == nullptr) {
         NimBLEDevice::m_pServer = new NimBLEServer();
-        ble_gatts_reset();
-        ble_svc_gap_init();
-        ble_svc_gatt_init();
     }
 
     return m_pServer;

src/NimBLEServer.cpp

@@ -272,13 +272,15 @@ void NimBLEServer::gattRegisterCallback(ble_gatt_register_ctxt* ctxt, void* arg)
 void NimBLEServer::start() {
     if (m_svcChanged && !getConnectedCount()) {
         NIMBLE_LOGD(LOG_TAG, "Services have changed since last start, resetting GATT server");
-        resetGATT();
+        m_gattsStarted = false;
     }
 
     if (m_gattsStarted) {
         return; // already started
     }
 
+    resetGATT();
+
     ble_hs_cfg.gatts_register_cb = NimBLEServer::gattRegisterCallback;
     gattRegisterCallbackArgs args{};
     ble_hs_cfg.gatts_register_arg = &args;
@@ -873,8 +875,6 @@ void NimBLEServer::resetGATT() {
     ble_svc_gap_init();
     ble_svc_gatt_init();
 
-    m_gattsStarted = false;
-
     for (auto svcIt = m_svcVec.begin(); svcIt != m_svcVec.end();) {
         auto* pSvc = *svcIt;
         if (pSvc->getRemoved() == NIMBLE_ATT_REMOVE_DELETE) {
@@ -908,7 +908,7 @@ void NimBLEServer::resetGATT() {
         }
 
         if (pSvc->getRemoved() == 0) {
-            pSvc->start();
+            pSvc->start_internal();
         }
 
         pSvc->m_handle = 0;

src/NimBLEService.cpp

@@ -83,22 +83,8 @@ void NimBLEService::dump() const {
  * and registers it with the NimBLE stack.
  * @return bool success/failure .
  */
-bool NimBLEService::start() {
+bool NimBLEService::start_internal() {
     NIMBLE_LOGD(LOG_TAG, ">> start(): Starting service: UUID: %s", getUUID().toString().c_str());
-    // If the server has started before then we need to reset the GATT server
-    // to update the service/characteristic/descriptor definitions. If characteristics or descriptors
-    // have been added/removed since the last server start then this service will be started on gatt reset.
-    if (getServer()->m_svcChanged && getServer()->m_gattsStarted) {
-        NIMBLE_LOGW(LOG_TAG, "<< start(): GATT change pending, cannot start service");
-        return false;
-    }
-
-    // If started previously and no characteristics have been added or removed,
-    // then we can skip the service registration process.
-    if (m_pSvcDef->characteristics && !getServer()->m_svcChanged) {
-        return true;
-    }
-
     // Make sure the definitions are cleared first
     clearServiceDefinitions();
 

src/NimBLEService.h

@@ -37,11 +37,19 @@ class NimBLEService : public NimBLELocalAttribute {
     NimBLEService(const NimBLEUUID& uuid);
     ~NimBLEService();
 
-    NimBLEServer*         getServer() const;
-    std::string           toString() const;
-    void                  dump() const;
-    bool                  isStarted() const;
-    bool                  start();
+    NimBLEServer* getServer() const;
+    std::string   toString() const;
+    void          dump() const;
+    bool          isStarted() const;
+
+    /**
+     * @brief Dummy function to start the service. Services are started when the server is started.
+     * This will be removed in a future release. Use `NimBLEServer::start()` to start the server and all associated services.
+     */
+    __attribute__((deprecated("NimBLEService::start() has no effect. "
+                   "Services are started when the server is started.")))
+    bool start() { return true; }
+
     NimBLECharacteristic* createCharacteristic(const char* uuid,
                                                uint32_t    properties = NIMBLE_PROPERTY::READ | NIMBLE_PROPERTY::WRITE,
                                                uint16_t    max_len    = BLE_ATT_ATTR_MAX_LEN);
@@ -61,6 +69,7 @@ class NimBLEService : public NimBLELocalAttribute {
 
   private:
     friend class NimBLEServer;
+    bool start_internal();
     void clearServiceDefinitions();
 
     std::vector<NimBLECharacteristic*> m_vChars{};