fix: correct duplicate descriptor handle assignment for same-UUID descriptors

When multiple GATT descriptors share the same UUID (e.g. 0x2904 Presentation Format),
NimBLEServer::start() incorrectly assigned them all the same handle due to
ble_gatts_find_dsc() performing a UUID-only lookup.

Author: srgg

src/NimBLEServer.cpp

@@ -210,7 +210,7 @@ void NimBLEServer::start() {
         // Set the descriptor handles now as the stack does not set these when the service is started
         for (const auto& chr : svc->m_vChars) {
             for (auto& desc : chr->m_vDescriptors) {
-                ble_gatts_find_dsc(svc->getUUID().getBase(), chr->getUUID().getBase(), desc->getUUID().getBase(), &desc->m_handle);
+                ble_gatts_find_dsc(svc->getUUID().getBase(), chr->getUUID().getBase(), desc->getUUID().getBase(), desc, &desc->m_handle);
             }
         }
     }

src/nimble/nimble/host/include/host/ble_gatt.h

@@ -1360,7 +1360,11 @@ int ble_gatts_find_chr(const ble_uuid_t *svc_uuid, const ble_uuid_t *chr_uuid,
  *
  * @param svc_uuid              The UUID of the grandparent service.
  * @param chr_uuid              The UUID of the parent characteristic.
- * @param dsc_uuid              The UUID of the descriptor ro look up.
+ * @param dsc_uuid              The UUID of the descriptor to look up.
+ * @param dsc_arg               The descriptor argument; a pointer to a
+ *                                  NimBLEDescriptor instance used to search
+ *                                  across multiple descriptors sharing
+ *                                  the same UUID.
  * @param out_dsc_handle        On success, populated with the handle
  *                                  of the descriptor attribute.  Pass null if
  *                                  you don't need this value.
@@ -1371,7 +1375,7 @@ int ble_gatts_find_chr(const ble_uuid_t *svc_uuid, const ble_uuid_t *chr_uuid,
  *                                  found.
  */
 int ble_gatts_find_dsc(const ble_uuid_t *svc_uuid, const ble_uuid_t *chr_uuid,
-                       const ble_uuid_t *dsc_uuid, uint16_t *out_dsc_handle);
+                       const ble_uuid_t *dsc_uuid, void* dsc_arg, uint16_t *out_dsc_handle);
 
 /** Type definition for GATT service iteration callback function. */
 typedef void (*ble_gatt_svc_foreach_fn)(const struct ble_gatt_svc_def *svc,

src/nimble/nimble/host/src/ble_gatts.c

@@ -2740,7 +2740,7 @@ ble_gatts_find_chr(const ble_uuid_t *svc_uuid, const ble_uuid_t *chr_uuid,
 
 int
 ble_gatts_find_dsc(const ble_uuid_t *svc_uuid, const ble_uuid_t *chr_uuid,
-                   const ble_uuid_t *dsc_uuid, uint16_t *out_handle)
+                   const ble_uuid_t *dsc_uuid, void* dsc_arg, uint16_t *out_handle)
 {
     struct ble_gatts_svc_entry *svc_entry;
     struct ble_att_svr_entry *att_chr;
@@ -2772,7 +2772,7 @@ ble_gatts_find_dsc(const ble_uuid_t *svc_uuid, const ble_uuid_t *chr_uuid,
             return BLE_HS_ENOENT;
         }
 
-        if (ble_uuid_cmp(cur->ha_uuid, dsc_uuid) == 0) {
+        if (ble_uuid_cmp(cur->ha_uuid, dsc_uuid) == 0 && (dsc_arg == NULL || (dsc_arg != NULL && cur->ha_cb_arg == dsc_arg))) {
             if (out_handle != NULL) {
                 *out_handle = cur->ha_handle_id;
                 return 0;