[Bugfix] Missing notification data when length > 255 bytes

When the ACL buffer is less than the MTU, the data arrives in more than one mbuf.
This combines the data from the mbuf chain and stores it before calling the appliation callback, ensuring it has all the data

Author: h2zero

src/NimBLEClient.cpp

@@ -933,7 +933,6 @@ int NimBLEClient::handleGapEvent(struct ble_gap_event* event, void* arg) {
 
     switch (event->type) {
         case BLE_GAP_EVENT_DISCONNECT: {
-
             // workaround for bug in NimBLE stack where disconnect event argument is not passed correctly
             pClient = NimBLEDevice::getClientByPeerAddress(event->disconnect.conn.peer_ota_addr);
             if (pClient == nullptr) {
@@ -946,8 +945,7 @@ int NimBLEClient::handleGapEvent(struct ble_gap_event* event, void* arg) {
             }
 
             if (pClient == nullptr) {
-                NIMBLE_LOGE(LOG_TAG, "Disconnected client not found, conn_handle=%d",
-                            event->disconnect.conn.conn_handle);
+                NIMBLE_LOGE(LOG_TAG, "Disconnected client not found, conn_handle=%d", event->disconnect.conn.conn_handle);
                 return 0;
             }
 
@@ -1050,33 +1048,46 @@ int NimBLEClient::handleGapEvent(struct ble_gap_event* event, void* arg) {
         } // BLE_GAP_EVENT_TERM_FAILURE
 
         case BLE_GAP_EVENT_NOTIFY_RX: {
-            if (pClient->m_connHandle != event->notify_rx.conn_handle) return 0;
-            NIMBLE_LOGD(LOG_TAG, "Notify Received for handle: %d", event->notify_rx.attr_handle);
-
-            for (const auto& svc : pClient->m_svcVec) {
-                // Dont waste cycles searching services without this handle in its range
-                if (svc->getEndHandle() < event->notify_rx.attr_handle) {
-                    continue;
-                }
-
-                NIMBLE_LOGD(LOG_TAG,
-                            "checking service %s for handle: %d",
-                            svc->getUUID().toString().c_str(),
-                            event->notify_rx.attr_handle);
+            if (pClient->m_connHandle != event->notify_rx.conn_handle) {
+                return 0;
+            }
 
-                for (const auto& chr : svc->m_vChars) {
-                    if (chr->getHandle() == event->notify_rx.attr_handle) {
-                        NIMBLE_LOGD(LOG_TAG, "Got Notification for characteristic %s", chr->toString().c_str());
+            NIMBLE_LOGD(LOG_TAG, "Notify Received for handle: %d", event->notify_rx.attr_handle);
 
-                        uint32_t data_len = OS_MBUF_PKTLEN(event->notify_rx.om);
-                        chr->m_value.setValue(event->notify_rx.om->om_data, data_len);
+            NimBLERemoteCharacteristic* pChr = pClient->getCharacteristic(event->notify_rx.attr_handle);
+            if (pChr == nullptr) {
+                NIMBLE_LOGW(LOG_TAG, "unknown handle: %d", event->notify_rx.attr_handle);
+                return BLE_ATT_ERR_INVALID_HANDLE;
+            }
 
-                        if (chr->m_notifyCallback != nullptr) {
-                            chr->m_notifyCallback(chr, event->notify_rx.om->om_data, data_len, !event->notify_rx.indication);
-                        }
+            auto len = event->notify_rx.om->om_len;
+            if (pChr->m_value.setValue(event->notify_rx.om->om_data, len)) {
+                os_mbuf* next;
+                next = SLIST_NEXT(event->notify_rx.om, om_next);
+                while (next != NULL) {
+                    pChr->m_value.append(next->om_data, next->om_len);
+                    if (pChr->m_value.length() != len + next->om_len) {
+                        rc = BLE_ATT_ERR_INVALID_ATTR_VALUE_LEN;
                         break;
                     }
+                    len  += next->om_len;
+                    next  = SLIST_NEXT(next, om_next);
                 }
+            } else {
+                rc = BLE_ATT_ERR_INVALID_ATTR_VALUE_LEN;
+            }
+
+            if (rc != 0) { // This should never happen
+                NIMBLE_LOGE(LOG_TAG, "notification value error; exceeds limit");
+                return rc;
+            }
+
+            if (pChr->m_notifyCallback != nullptr) {
+                // TODO: change this callback to use the NimBLEAttValue class instead of raw data and length
+                pChr->m_notifyCallback(pChr,
+                                       const_cast<uint8_t*>(pChr->m_value.getValue().data()),
+                                       pChr->m_value.length(),
+                                       !event->notify_rx.indication);
             }
 
             return 0;