Merge pull request #13449 from paul-szczepanek-arm/fix-prep-write

BLE: Fix writing attributes larger than MTU size

Author: 0xc0170

connectivity/FEATURE_BLE/libraries/TARGET_CORDIO/include/ble/internal/PalAttClientImpl.h

@@ -381,13 +381,11 @@ class PalAttClient : public interface::PalAttClient {
     struct PrepareWriteResponseConverter : ResponseConverter<ATTC_PREPARE_WRITE_RSP> {
         static AttPrepareWriteResponse convert(const attEvt_t* event)
         {
-            // WARNING: Not sure if correct, the stack erase the length parameter
             return AttPrepareWriteResponse(
                 event->handle,
-                to_uint16_t(event->pValue + 2),
-                // FIXME: the stack set the lenght to 0, the data won't be seen ...
+                0, /* offset is lost */
                 make_const_Span(
-                    event->pValue + 4,
+                    event->pValue,
                     event->valueLen
                 )
             );

connectivity/FEATURE_BLE/libraries/TARGET_CORDIO/stack/ble-host/sources/stack/att/atts_write.c

@@ -260,7 +260,7 @@ void attsProcPrepWriteReq(attsCcb_t *pCcb, uint16_t len, uint8_t *pPacket)
   }
   /* verify write length, fixed length */
   else if (((pAttr->settings & ATTS_SET_VARIABLE_LEN) == 0) &&
-           (writeLen != pAttr->maxLen))
+           (writeLen > pAttr->maxLen))
   {
     err = ATT_ERR_LENGTH;
   }