dnsbl style blocking script (2016)

dnsbl.php

<?php
function CheckIfSpambot($emailAddress, $ipAddress, $userName, $debug = false)
{
  $spambot = false;
  $errorDetected = false;
 
  if ($emailAddress != "")
  {
    $xml_string = file_get_contents("http://www.stopforumspam.com/api?email=" . urlencode($emailAddress));
    $xml = new SimpleXMLElement($xml_string);
 
    if ($xml->appears == "yes") // Was the result was registered
    {
      $spambot = true; // Check failed. Result indicates dangerous.
    }
    elseif ($xml->appears == "no") // Check passed. Result returned safe.
    {
      $spambot = false; // Check passed. Result returned safe.
    }
    else
    {
      $errorDetected = true; // Test returned neither positive or negative result. Service might be down?
    }
  }
 
  // -------------
  // Check IP Address
  // -------------
  if ($spambot != true && $ipAddress != "")
  {
    $xml_string = file_get_contents("http://www.stopforumspam.com/api?ip=" . urlencode($ipAddress));
    $xml = new SimpleXMLElement($xml_string);
 
    if ($xml->appears == "yes") // Was the result was registered
    {
      $spambot = true; // Check failed. Result indicates dangerous.
    }
    elseif ($xml->appears == "no") // Check passed. Result returned safe.
    {
      $spambot = false; // Check passed. Result returned safe.
    }
    else
    {
      $errorDetected = true; // Test returned neither positive or negative result. Service might be down?
    }
  }
 
  // -------------
  // Check Username
  // -------------
  if ($spambot != true && $userName != "")
  {
    $xml_string = file_get_contents("http://www.stopforumspam.com/api?username=" . urlencode($userName));
    $xml = new SimpleXMLElement($xml_string);
 
    if ($xml->appears == "yes") // Was the result was registered
    {
      $spambot = true; // Check failed. Result indicates dangerous.
    }
    elseif ($xml->appears == "no") // Check passed. Result returned safe.
    {
      $spambot = false; // Check passed. Result returned safe.
    }
    else
    {
      $errorDetected = true; // Test returned neither positive or negative result. Service might be down?
    }
  }
 
  // To debug function, call it with the debug flag as true and instead the function will return whether or not an error was detected, rather than the test result.
  if ($debug == true)
  {
    return $errorDetected; // If enabled, return whether or not an error was detected
  }
  else
  {
    return $spambot; // Return test results as either true/false or 1/0
  }
}

function ReverseIPOctets($inputip){
	$ipoc = explode(".",$inputip);
	return $ipoc[3].".".$ipoc[2].".".$ipoc[1].".".$ipoc[0];
}

function IsTorExitPoint($ip){
	if (gethostbyname(ReverseIPOctets($ip).".".$_SERVER['SERVER_PORT'].".".ReverseIPOctets($_SERVER['SERVER_ADDR']).".ip-port.exitlist.torproject.org")=="127.0.0.2") {
		return true;
	} else {
		return false;
	}
}

function checkbl($ip){
	$blacklisted = 0;
	$whitelist = array(''); //ips of users who you wish to whitelist regardless of conditions below
	$blacklist = array(''); //bad ips go here
	$range_blacklist = array(''); //ip ranges go here e.g. 84.72.0.0
	$city_blacklist = array(''); //cities go here
	$region_blacklist = array(''); //regions go here
	
	$geoip = geoip_record_by_name($ip);
	$mask=ip2long("255.255.255.0");
	$remote=ip2long($ip);
	
	//check for tor
	if (IsTorExitPoint($ip)) {
		$blacklisted = 1;
	}
	
	//check stopforumspam if ip is malicious
	if (CheckIfSpambot('', $ip, '')){
		$blacklisted = 1;
	}

	//check if ip is in range_blacklist
	foreach($range_blacklist as $single_range){
		if (($remote & $mask)==ip2long($single_range))
		{
			$blacklisted = 1;
		}
	}
	
	//check if geoip city is blacklisted
	foreach($city_blacklist as $city){
		if ($geoip['city'] == $city)
		{
			$blacklisted = 1;
		}
	}
	
	//check if geoip region is blacklisted
	foreach($region_blacklist as $region){
		if ($geoip['region'] == $region)
		{
			$blacklisted = 1;
		}
	}
	
	//check if ip is in the blacklist
	if (in_array($ip, $blacklist)) {
		$blacklisted = 1;
	}
	
	//do stuff (returns 1 for blacklisted and 0 for safe)
	if($blacklisted && !in_array($ip, $whitelist)){
		return 1;
	}else{
		return 0;
	}
}

if(isset($_REQUEST['ip'])){
	echo checkbl($_REQUEST['ip']);
}else{
	echo checkbl($_SERVER['REMOTE_ADDR']);
}

?>