[OpenSER-Users] How to compare $si with $dr

Hi, I am trying to compare the values of 'IP source address' ($si) and 'Domain in SIP Request's URI' ($rd) to see if they match in Openser 1.1. Probably I have missed the relevant documentation, I checked http://www.openser.org/dokuwiki/doku.php/pseudovariables:1.1.x and http://www.openser.org/dokuwiki/doku.php/core-cookbook:1.1.x . Basically I'd like to do this: if($si == $rd){ #do something } but that gives a syntax error. I also tried this: if(src_ip==$rd){ } but it seems the pseudo variable isn't being expanded before the evaluation, as I don't get a match even though debugging shows $si and $rd to be the same. Also, is there anyway to pass a pseudo variable to rewritehost() or an equivalent function? Thanks for any pointers, Richard