Kirupa PHP sockets tutorial doesn't wait for complete messages?

I think someone I work with was reading this tutorial:

http://www.kirupa.com/developer/flash8/php5sockets_flash8.htm

Am I misunderstanding how PHP’s socket_recv works, or, would the socket server described in this tutorial not only not wait for complete messages to arrive, but also send multiple null-terminated messages simultaneously if more than one message arrived in the buffer while PHP was busy?