fix: accept float claims but round down to ignore them (#492)

Author: croensch

Diff for: src/JWT.php

@@ -152,18 +152,18 @@ public static function decode(
 
         // Check the nbf if it is defined. This is the time that the
         // token can actually be used. If it's not yet that time, abort.
-        if (isset($payload->nbf) && $payload->nbf > ($timestamp + static::$leeway)) {
+        if (isset($payload->nbf) && floor($payload->nbf) > ($timestamp + static::$leeway)) {
             throw new BeforeValidException(
-                'Cannot handle token prior to ' . \date(DateTime::ISO8601, $payload->nbf)
+                'Cannot handle token prior to ' . \date(DateTime::ISO8601, (int) $payload->nbf)
             );
         }
 
         // Check that this token has been created before 'now'. This prevents
         // using tokens that have been created for later use (and haven't
         // correctly used the nbf claim).
-        if (!isset($payload->nbf) && isset($payload->iat) && $payload->iat > ($timestamp + static::$leeway)) {
+        if (!isset($payload->nbf) && isset($payload->iat) && floor($payload->iat) > ($timestamp + static::$leeway)) {
             throw new BeforeValidException(
-                'Cannot handle token prior to ' . \date(DateTime::ISO8601, $payload->iat)
+                'Cannot handle token prior to ' . \date(DateTime::ISO8601, (int) $payload->iat)
             );
         }