搜索站点中的文件并将其复制到阵列

I want to search *.rules from this site http://cvs.snort.org/viewcvs.cgi/snort/rules/

and copy the strings of files into an array

how can I do this? for example:

$array=array('backdoor.rules','bad-traffic.rules');

I can use

$str=file_get_contents( 'http://cvs.snort.org/viewcvs.cgi/snort/rules');

but how can I search?