check if IP is within the mask

isipinsub.php

<?php

$ipthing = "192.168.1.201";
$ipsubthing = "*.*.*.201";
 
if(isipinsub ($ipthing, $ipsubthing)) {echo "It's in the subnet."; } else { echo "Nope."; } 


#---------------------------------# 
#------isipinsub function---------# 
#---------------------------------# 
#--checks whether an IP is in a---# 
#--subnet. Can understand single--# 
#--IPs, CIDR-style and 'asterisk'-# 
#----style entries. Returns as----# 
#------either true or false.------# 
#----Needs ipto32bin function.----# 
#------Cjwinnit@codingforums------# 
#---------------------------------# 
 
function isipinsub ( $ip, $ipsub ) 
{ 
$x = strpos($ipsub, "/"); 
$y = strpos($ipsub, "*"); 
 
//The next if statement works out  
//if it contains (an) asterisk(s) or a slash. 
//If it has neither, we treat it as a single IP 
//and we go straight to the comparison at the end. 
 
if (!($x === false) || !($y === false))  
{ 
  //so it's either CIDR-style or asterisk. 
  //do different things to each... 
  if (!($x === false)) 
    {  
    //it's CIDR-style. Nick the end number. 
    $lengthcomp = substr($ipsub, $x + 1); 
    //trim off the end number and slash. 
    $ipsub = substr($ipsub, 0, $x); 
    //next two lines trim the binary strings 
    //to the correct length using $lengthcomp. 
 
    $ip = substr(ipto32bin($ip),0,$lengthcomp); 
    $ipsub = substr(ipto32bin($ipsub),0,$lengthcomp); 
    //We'll go-compaa-AARE! at the end. 
      
    } else { 
    //Asterisk-style. Bit more complicated... 
 
    $asteriskarraysub = explode(".",$ipsub);  
    $asteriskarray = explode(".",$ip);  
        //do an element-by-element comparison. 
        $iinf = 0; do { 
        if (!(($asteriskarraysub[$iinf] == $asteriskarray[$iinf]) || ($asteriskarraysub[$iinf] == "*"))) { return FALSE; }  
        $iinf++; 
          
        } while($iinf<=3); 
    //each of the elements in original IP pairs up 
    //with either it's own number in subip or "*" in subip. 
    //Therefore it's in the subnet.     
    return TRUE; 
    } 
 
} 
//It's where you go to, 
//Insure your motor.... 
if($ip === $ipsub) return TRUE; 
else return FALSE; 
} 
#------isipinsub function end-----#