<?php

class mxlookup
{
     var $dns_socket = NULL;
     var $QNAME = "";
     var $dns_packet= NULL;
     var $ANCOUNT = 0;
     var $cIx = 0;
     var $dns_repl_domain;
     var $arrMX = array();

     function mxlookup($domain, $dns="192.76.85.133")
     {
         $this->QNAME($domain);
         $this->pack_dns_packet();
         $dns_socket = fsockopen("udp://$dns", 53);

         fwrite($dns_socket,$this->dns_packet,strlen($this->dns_packet));
         $this->dns_reply  = fread($dns_socket,1);
         $bytes = stream_get_meta_data($dns_socket);
         $this->dns_reply .= fread($dns_socket,$bytes['unread_bytes']);
         fclose($dns_socket);
         $this->cIx=6;
         $this->ANCOUNT  = $this->gord(2);
         $this->cIx+=4;
         $this->parse_data($this->dns_repl_domain);
         $this->cIx+=7;

         for($ic=1;$ic<=$this->ANCOUNT;$ic++)
         {
           $QTYPE = ord($this->gdi($this->cIx));
           if($QTYPE!==15){print("[MX Record not returned]"); die();}
           $this->cIx+=9;
           $mxPref = ord($this->gdi($this->cIx));
           $this->parse_data($curmx);
           $this->arrMX[] = array("MX_Pref" => $mxPref, "MX" => $curmx);
           $this->cIx+=3;
         }
     }

     function parse_data(&$retval)
     {
       $arName = array();
       $byte = ord($this->gdi($this->cIx));
       while($byte!==0)
       {
         if($byte==192) //compressed
         {
           $tmpIx = $this->cIx;
           $this->cIx = ord($this->gdi($cIx));
           $tmpName = $retval;
           $this->parse_data($tmpName);
           $retval=$retval.".".$tmpName;
           $this->cIx = $tmpIx+1;
           return;
         }
         $retval="";
         $bCount = $byte;
         for($b=0;$b<$bCount;$b++)
         {
           $retval .= $this->gdi($this->cIx);
         }
         $arName[]=$retval;
         $byte = ord($this->gdi($this->cIx));
       }
       $retval=join(".",$arName);
     }

     function gdi(&$cIx,$bytes=1)
     {
       $this->cIx++;
       return(substr($this->dns_reply, $this->cIx-1, $bytes));
     }

     function QNAME($domain)
     {
       $dot_pos = 0; $temp = "";
       while($dot_pos=strpos($domain,"."))
       {
         $temp  = substr($domain,0,$dot_pos);
         $domain = substr($domain,$dot_pos+1);
         $this->QNAME .= chr(strlen($temp)).$temp;
       }
       $this->QNAME .= chr(strlen($domain)).$domain.chr(0);
     }

     function gord($ln=1)
     {
       $reply="";
       for($i=0;$i<$ln;$i++){
         $reply.=ord(substr($this->dns_reply,$this->cIx,1));
         $this->cIx++;
         }

       return $reply;
     }

     function pack_dns_packet()
     {
       $this->dns_packet = chr(0).chr(1).
                           chr(1).chr(0).
                           chr(0).chr(1).
                           chr(0).chr(0).
                           chr(0).chr(0).
                           chr(0).chr(0).
                           $this->QNAME.
                           chr(0).chr(15).
                           chr(0).chr(1);
     }

}

?>



<form name="mxlookup" action="mx.php" method="post">

<table table style="border: #000000 1px solid" width="200">
<tr>
    <td><div align="right" style=font-size:0.8em>Domain:   </div></td>
    <td><input name="domain" type="text" size="25" style="border: #000000 1px solid" value=""></td>
</tr>
</table>

</form>


<?php

/* HTML Form Output*/
$domain = $_POST['domain'];
$mx = new mxlookup("$domain");

print $mx->ANCOUNT." MX Records\n";
print "Records For ".$mx->dns_repl_domain.":\n<pre>";
print_r($mx->arrMX);

?>