PHP socket 绑定随机端口

<?php

$sock = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
socket_bind ($sock, "127.0.0.1", 0);
socket_getsockname($sock, $socket_address, $socket_port);

echo $socket_address;//被赋值了
echo $socket_port;//被赋值了

socket_listen($sock);