modification

below is my completed code, please somebody can help me how to accept ONLY agents pasted in $ar_agent $ar_badreferer , all others agents and referers must be disabled, being more clear,, the code below currently disable agents/referers access only as desrcibed in $ar_agent $ar_badreferer.

 require_once('Connections/default.php');


// Set These VARS

	$banned_ips = file_get_contents("./ipjatba.txt");
	$logfile = "./log.html";
	$ipfile = "./ajpijat.txt";
	$ar_agent = array("Firefox","Opera");
	$ar_badreferer = array("Google","Yahoo");
	$doubles = 0;  // value of 0 or 1
	$userid = "admin";  // Change this to the userid in your database
	
	

if (!function_exists("GetSQLValueString")) {
function GetSQLValueString($theValue, $theType, $theDefinedValue = "", $theNotDefinedValue = "") 
{
  $theValue = get_magic_quotes_gpc() ? stripslashes($theValue) : $theValue;

  $theValue = function_exists("mysql_real_escape_string") ? mysql_real_escape_string($theValue) : mysql_escape_string($theValue);

  switch ($theType) {
    case "text":
      $theValue = ($theValue != "") ? "'" . $theValue . "'" : "NULL";
      break;    
    case "long":
    case "int":
      $theValue = ($theValue != "") ? intval($theValue) : "NULL";
      break;
    case "double":
      $theValue = ($theValue != "") ? "'" . doubleval($theValue) . "'" : "NULL";
      break;
    case "date":
      $theValue = ($theValue != "") ? "'" . $theValue . "'" : "NULL";
      break;
    case "defined":
      $theValue = ($theValue != "") ? $theDefinedValue : $theNotDefinedValue;
      break;
  }
  return $theValue;
}
}
	

mysql_select_db($database_default, $default);
$query_Recordset1 = "SELECT * FROM sajti WHERE (userid = 'admin') AND (sajti.a_count < sajti.a_max)  AND (sajti.a_active = '1')  ORDER BY sajti.a_count";
$Recordset1 = mysql_query($query_Recordset1, $default) or die(mysql_error());
$row_Recordset1 = mysql_fetch_assoc($Recordset1);
$totalRows_Recordset1 = mysql_num_rows($Recordset1);


// Fixed Vars - Do NOT EDIT

	$display = 1;
	$reason = "";


// Function HTTP_USER_AGENTS

	function checkagent($agent) {
		if (substr_count($_SERVER['HTTP_USER_AGENT'], $agent) <> 0) {
			$bagent = 1;
		}
	return $bagent;
	}

// Function HTTP_REFERER

	function checkref($referer) {
		if(substr_count($_SERVER['HTTP_REFERER'], $referer) <> 0) {
			$breferer = 1;
		}
	return $breferer;
	}


	function itsnull($danullvoid) {
		if ($danullvoid == "") {
			return false;
		}
	return true;
	}


	$ar_banned = explode("\n", $banned_ips);

	$enduserip = $_SERVER['REMOTE_ADDR'];

	list($eu_a, $eu_b, $eu_c, $eu_d) = split("\.", $enduserip);

	foreach ($ar_banned as $val) {
		list($banned_a, $banned_b, $banned_c, $banned_d) = split("\.", $val);
			if  (($eu_a == $banned_a) AND ($eu_b == $banned_b) AND ($val <> "")){
				$reason .= "Banned IP (" . $val . ") / ";
				// print "val=".$val;
			}
	}


	if ($doubles == 1) {
		$fs = file_get_contents($ipfile);
		$fa = explode("\n", $fs);
		foreach ($fa as $value) {
	                if ($value == $_SERVER['REMOTE_ADDR']) {
			$reason .= "Already / ";
                	}
	        }
	}

// Filter HTTP_USER_AGENT

	foreach ($ar_agent as $agent_value) {
		if (checkagent($agent_value) == 1) {
			$display = 0;
			$reason .= "Bad Agent: ". $agent_value ." / ";
		}
	}

// Filter HTTP_REFERER 

	foreach ($ar_badreferer as $badreferer_value) {
		if (checkref($badreferer_value) == 1) {
			$display = 0;
			$reason .= "Bad Referer: ". $badreferer_value ." / ";
		}
	}
	

	$calc_ctr = rand(1,100);
	
	if ($reason == "") {
		$display = 1;
		$foundone = 0;
	
	do {

	if ($calc_ctr < $row_Recordset1['a_ctr']) {
		$foundone = 1;
		echo "display=1&banner=" . $row_Recordset1['a_url'];

		$fh = fopen($logfile, 'a') or die("can't open file");
                fwrite($fh,"\n<br>Referer: ");
                fwrite($fh, ($_SERVER['HTTP_REFERER']) );
                fwrite($fh,", ");
                fwrite($fh, ($_SERVER['HTTP_USER_AGENT']) );
                fwrite($fh,", ");
                fwrite($fh, $_SERVER['REMOTE_ADDR']);
                fwrite($fh,", ");
                fwrite($fh, date('l jS \of F Y h:i:s A') );
                fclose($fh);
			if ($doubles == 1) {
                $ipf = fopen($ipfile, 'a') or die("Can't Open File");
                fwrite($ipf, $_SERVER['REMOTE_ADDR']);
                fwrite($ipf, "\n");
                fclose($ipf);		
			}
				$newcount = $row_Recordset1['a_count'];
				$newcount++;

			    $updateSQL = sprintf("UPDATE sajti SET a_count=%s WHERE affiliateid=%s",
                       GetSQLValueString($newcount, "int"),
                       GetSQLValueString($row_Recordset1['affiliateid'], "int"));


			    mysql_select_db($database_default, $default);
			    $Result1 = mysql_query($updateSQL, $default) or die(mysql_error());
	}
	} while ( ($row_Recordset1 = mysql_fetch_assoc($Recordset1)) && ($foundone == 0));

		if ($foundone == 0) {
			echo "display=0&banner=";
		}
	}
	else {

	
		//echo "display=0&ctr=". $ctr . "&banner=" . $arr_affiliate[$affiliate_id];
		echo "display=0&banner=";

     	        $fh = fopen($logfile, 'a') or die("can't open file");
                fwrite($fh,"\n<font color=\"red\"><br><b>" . $reason);
                fwrite($fh,"</b> ");
                fwrite($fh,"Referer: ");
                fwrite($fh, ($_SERVER['HTTP_REFERER']) );
                fwrite($fh,", ");
                fwrite($fh, ($_SERVER['HTTP_USER_AGENT']) );
                fwrite($fh,", ");
                fwrite($fh, $_SERVER['REMOTE_ADDR']);
                fwrite($fh,", ");
                fwrite($fh, date('l jS \of F Y h:i:s A') );
                fwrite($fh, "</font>");
                fclose($fh);
	}

mysql_free_result($Recordset1);

Code (markup):

 

why not use stristr or a regex pattern for this?