fix(api): Fix errors in send_trytes

serialize/serialize.c: Return `SC_SERIALIZER_INVALID_REQ` if any element (trytes)
in the  requeting trytes list length not equal to NUM_TRYTES_SERIALIZED_TRANSACTION.

utils/pow.c: Exit pow loop if tx == NULL which may happen if the requesting trytes
is arbitrary tytes which means the transaction indext doesn't meet the real index.

accelerator/errors.h

@@ -97,6 +97,8 @@ typedef enum {
   SC_SERIALIZER_JSON_PARSE_UNICODE =
       0x04 | SC_MODULE_SERIALIZER | SC_SEVERITY_FATAL,
   /**< unicode value in JSON */
+  SC_SERIALIZER_INVALID_REQ = 0x05 | SC_MODULE_SERIALIZER | SC_SEVERITY_FATAL,
+  /**< invald request value in JSON */
 
   // Cache module
   SC_CACHE_NULL = 0x01 | SC_MODULE_CACHE | SC_SEVERITY_FATAL,

serializer/serializer.c

@@ -82,6 +82,10 @@ static status_t ta_json_array_to_hash8019_array(cJSON const* const obj,
   cJSON* current_obj = NULL;
   cJSON_ArrayForEach(current_obj, json_item) {
     if (current_obj->valuestring != NULL) {
+      if (strlen(current_obj->valuestring) !=
+          NUM_TRYTES_SERIALIZED_TRANSACTION) {
+        return SC_SERIALIZER_INVALID_REQ;
+      }
       flex_trits_from_trytes(hash, NUM_TRITS_SERIALIZED_TRANSACTION,
                              (tryte_t const*)current_obj->valuestring,
                              NUM_TRYTES_SERIALIZED_TRANSACTION,

utils/pow.c

@@ -82,7 +82,7 @@ status_t ta_pow(const bundle_transactions_t* bundle,
     ctrunk = iota_flex_digest(tx_trits, NUM_TRITS_SERIALIZED_TRANSACTION);
     tx = (iota_transaction_t*)utarray_prev(bundle, tx);
     free(nonce);
-  } while (cur_idx != 0);
+  } while (cur_idx != 0 && tx != NULL);
 
 done:
   free(ctrunk);