[Bugfix] Remote descriptor not found when char handles out of order

This resolves the issue of retrieving characteristics out of handle order and then trying to subscribe or
do some other fetch of a descriptor belonging to that characteristic and the search handle was limited
to the handle of the next characteristic in the vector.

This ensures that the vector is sorted in ascending order based on handle values so the next characteristic
in the vector will always have a higher handle value and the desciptor serach will function as intended.

Author: h2zero

src/NimBLERemoteService.cpp

@@ -25,6 +25,7 @@
 # include "NimBLELog.h"
 
 # include <climits>
+# include <algorithm>
 
 static const char* LOG_TAG = "NimBLERemoteService";
 
@@ -207,6 +208,12 @@ bool NimBLERemoteService::retrieveCharacteristics(const NimBLEUUID* uuidFilter)
     NimBLEUtils::taskWait(taskData, BLE_NPL_TIME_FOREVER);
     rc = taskData.m_flags;
     if (rc == 0 || rc == BLE_HS_EDONE) {
+        // sort the characteristics vector by handle to make sure the search range for descriptors is correct
+        std::sort(m_vChars.begin(),
+                  m_vChars.end(),
+                  [](const NimBLERemoteCharacteristic* a, const NimBLERemoteCharacteristic* b) {
+                      return a->getHandle() < b->getHandle();
+                  });
         NIMBLE_LOGD(LOG_TAG, "<< retrieveCharacteristics()");
         return true;
     }