src/HTTP/Request2/Adapter/Socket.php
protected function canKeepAlive($requestKeepAlive, HTTP_Request2_Response $response)
    {
        // Do not close socket on successful CONNECT request
        if (HTTP_Request2::METHOD_CONNECT == $this->request->getMethod()
            && 200 <= $response->getStatus() && 300 > $response->getStatus()
        ) {
            return true;
        }

        $lengthKnown = 'chunked' == strtolower($response->getHeader('transfer-encoding'))
                       || null !== $response->getHeader('content-length')
                       // no body possible for such responses, see also request #17031
                       || HTTP_Request2::METHOD_HEAD == $this->request->getMethod()
                       || in_array($response->getStatus(), array(204, 304));
        $persistent  = 'keep-alive' == strtolower($response->getHeader('connection')) ||
                       (null === $response->getHeader('connection') &&
                        '1.1' == $response->getVersion());
        return $requestKeepAlive && $lengthKnown && $persistent;
    }
protected function canKeepAlive($requestKeepAlive, HTTP_Request2_Response $response)
    {
        // Do not close socket on successful CONNECT request
        if (HTTP_Request2::METHOD_CONNECT == $this->request->getMethod()
            && 200 <= $response->getStatus() && 300 > $response->getStatus()
        ) {
            return true;
        }

        $lengthKnown = 'chunked' == strtolower($response->getHeader('transfer-encoding'))
                       || null !== $response->getHeader('content-length')
                       // no body possible for such responses, see also request #17031
                       || HTTP_Request2::METHOD_HEAD == $this->request->getMethod()
                       || in_array($response->getStatus(), array(204, 304));
        $persistent  = 'keep-alive' == strtolower($response->getHeader('connection')) ||
                       (null === $response->getHeader('connection') &&
                        '1.1' == $response->getVersion());
        return $requestKeepAlive && $lengthKnown && $persistent;
    }
Checks whether current connection may be reused or should be closed

@param boolean                $requestKeepAlive whether connection could
be persistent in the first place
@param HTTP_Request2_Response $response         response object to check

@return   boolean