fix(api): Fix TA crash meeting unicode input

The original TA would crash if it met unicode input, but now, it will
return an error status_t code to reflect the situation that catch an
unicode input.

accelerator/errors.h

@@ -87,6 +87,9 @@ typedef enum {
   /**< NULL object in serializer */
   SC_SERIALIZER_JSON_PARSE = 0x03 | SC_MODULE_SERIALIZER | SC_SEVERITY_FATAL,
   /**< Fail to parse JSON object in serializer */
+  SC_SERIALIZER_JSON_PARSE_UNICODE =
+      0x04 | SC_MODULE_SERIALIZER | SC_SEVERITY_FATAL,
+  /**< unicode value in JSON */
 
   // Cache module
   SC_CACHE_NULL = 0x01 | SC_MODULE_CACHE | SC_SEVERITY_FATAL,

serializer/serializer.c

@@ -521,6 +521,15 @@ status_t send_mam_req_deserialize(const char* const obj, send_mam_req_t* req) {
     tryte_t* payload_trytes = (tryte_t*)malloc(payload_size * sizeof(tryte_t));
     ascii_to_trytes(json_result->valuestring, payload_trytes);
 
+    // in case the payload is unicode, char more than 128 will result to an
+    // error status_t code
+    for (int i = 0; i < strlen(json_result->valuestring); i++) {
+      if (json_result->valuestring[i] & (unsigned)128) {
+        ret = SC_SERIALIZER_JSON_PARSE_UNICODE;
+        goto done;
+      }
+    }
+
     req->payload_trytes = payload_trytes;
     req->payload_trytes_size = payload_size;
   } else {