See `CURLMOPT_PUSHFUNCTION`, `CURL_PUSH_OK` and `CURL_PUSH_DENY` options for [curl_multi_setopt](http://php.net/manual/de/function.curl-multi-setopt.php). CURL extension requires version 7.46 or above.
See
CURLMOPT_PUSHFUNCTION,CURL_PUSH_OKandCURL_PUSH_DENYoptions for curl_multi_setopt.CURL extension requires version 7.46 or above.