two php function in the same page conflict what can I change to?

I'm trying to protect page by making a member only area the code I use in this case is

<?php 
include 'dbc.php';
page_protect();


?>

there is no error by using this code and also it just working fine but the problem is that whenever I place the below code in the same page the problem will happen with the iPhone, only with this device but the rest still ok, like PCs, laptop and tablet (iPad) they are all no problem

But the iPhone the problem will be that you can access to the page after login but whenever you refresh it will redirect you to the login page and ask for login again.

<?php
if(!isset($_GET['link'])){ 
    $link = 1; 
} else { 
    $link = $_GET['link']; 
}

if ($link == 1) {
echo "";
} elseif ($link == 23) {
echo "";
} else {
echo "";
} 
?>

There is no error show or anything.

my question is that is there anyway to protect the page because I need this to be member only area and the above code is very important and need to be in the page.

Thanks in advance.

here is the dbc.php sorry about that but I copied the whole script and placed here

<?php
/*************** PHP LOGIN SCRIPT V 2.3*********************
(c) Balakrishnan 2010. All Rights Reserved

Usage: This script can be used FREE of charge for any commercial or personal projects. Enjoy!

Limitations:
- This script cannot be sold.
- This script should have copyright notice intact. Dont remove it please...
- This script may not be provided for download except from its original site.

For further usage, please contact me.

/******************** MAIN SETTINGS - PHP LOGIN SCRIPT V2.1 **********************
Please complete wherever marked xxxxxxxxx

/************* MYSQL DATABASE SETTINGS *****************
1. Specify Database name in $dbname
2. MySQL host (localhost or remotehost)
3. MySQL user name with ALL previleges assigned.
4. MySQL password

Note: If you use cpanel, the name will be like account_database
*************************************************************/

define ("DB_HOST", "xxxxxx"); // set database host
define ("DB_USER", "xxxxxx"); // set database user
define ("DB_PASS","xxxxxxx"); // set database password
define ("DB_NAME","xxxxxx"); // set database name

$link = mysql_connect(DB_HOST, DB_USER, DB_PASS) or die("Couldn't make connection.");
$db = mysql_select_db(DB_NAME, $link) or die("Couldn't select database");

/* Registration Type (Automatic or Manual) 
 1 -> Automatic Registration (Users will receive activation code and they will be automatically approved after clicking activation link)
 0 -> Manual Approval (Users will not receive activation code and you will need to approve every user manually)
*/
$user_registration = 1;  // set 0 or 1

define("COOKIE_TIME_OUT", 10); //specify cookie timeout in days (default is 10 days)
define('SALT_LENGTH', 9); // salt for password

//define ("ADMIN_NAME", "admin"); // sp

/* Specify user levels */
define ("ADMIN_LEVEL", 5);
define ("USER_LEVEL", 1);
define ("GUEST_LEVEL", 0);



/*************** reCAPTCHA KEYS****************/
$publickey = "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx";
$privatekey = "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx";


/**** PAGE PROTECT CODE  ********************************
This code protects pages to only logged in users. If users have not logged in then it will redirect to login page.
If you want to add a new page and want to login protect, COPY this from this to END marker.
Remember this code must be placed on very top of any html or php page.
********************************************************/

function page_protect() {
session_start();

global $db; 

/* Secure against Session Hijacking by checking user agent */
if (isset($_SESSION['HTTP_USER_AGENT']))
{
    if ($_SESSION['HTTP_USER_AGENT'] != md5($_SERVER['HTTP_USER_AGENT']))
    {
        logout();
        exit;
    }
}

// before we allow sessions, we need to check authentication key - ckey and ctime stored in database

/* If session not set, check for cookies set by Remember me */
if (!isset($_SESSION['user_id']) && !isset($_SESSION['user_name']) ) 
{
    if(isset($_COOKIE['user_id']) && isset($_COOKIE['use开发者_运维问答r_key'])){
    /* we double check cookie expiry time against stored in database */

    $cookie_user_id  = filter($_COOKIE['user_id']);
    $rs_ctime = mysql_query("select `ckey`,`ctime` from `users` where `id` ='$cookie_user_id'") or die(mysql_error());
    list($ckey,$ctime) = mysql_fetch_row($rs_ctime);
    // coookie expiry
    if( (time() - $ctime) > 60*60*24*COOKIE_TIME_OUT) {

        logout();
        }
/* Security check with untrusted cookies - dont trust value stored in cookie.       
/* We also do authentication check of the `ckey` stored in cookie matches that stored in database during login*/

     if( !empty($ckey) && is_numeric($_COOKIE['user_id']) && isUserID($_COOKIE['user_name']) && $_COOKIE['user_key'] == sha1($ckey)  ) {
          session_regenerate_id(); //against session fixation attacks.

          $_SESSION['user_id'] = $_COOKIE['user_id'];
          $_SESSION['user_name'] = $_COOKIE['user_name'];
        /* query user level from database instead of storing in cookies */  
          list($user_level) = mysql_fetch_row(mysql_query("select user_level from users where id='$_SESSION[user_id]'"));

          $_SESSION['user_level'] = $user_level;
          $_SESSION['HTTP_USER_AGENT'] = md5($_SERVER['HTTP_USER_AGENT']);

       } else {
       logout();
       }

  } else {
    header("Location: login.php");
    exit();
    }
}
}



function filter($data) {
    $data = trim(htmlentities(strip_tags($data)));

    if (get_magic_quotes_gpc())
        $data = stripslashes($data);

    $data = mysql_real_escape_string($data);

    return $data;
}



function EncodeURL($url)
{
$new = strtolower(ereg_replace(' ','_',$url));
return($new);
}

function DecodeURL($url)
{
$new = ucwords(ereg_replace('_',' ',$url));
return($new);
}

function ChopStr($str, $len) 
{
    if (strlen($str) < $len)
        return $str;

    $str = substr($str,0,$len);
    if ($spc_pos = strrpos($str," "))
            $str = substr($str,0,$spc_pos);

    return $str . "...";
}   

function isEmail($email){
  return preg_match('/^\S+@[\w\d.-]{2,}\.[\w]{2,6}$/iU', $email) ? TRUE : FALSE;
}

function isUserID($username)
{
    if (preg_match('/^[a-z\d_]{5,20}$/i', $username)) {
        return true;
    } else {
        return false;
    }
 }  

function isURL($url) 
{
    if (preg_match('/^(http|https|ftp):\/\/([A-Z0-9][A-Z0-9_-]*(?:\.[A-Z0-9][A-Z0-9_-]*)+):?(\d+)?\/?/i', $url)) {
        return true;
    } else {
        return false;
    }
} 

function checkPwd($x,$y) 
{
if(empty($x) || empty($y) ) { return false; }
if (strlen($x) < 4 || strlen($y) < 4) { return false; }

if (strcmp($x,$y) != 0) {
 return false;
 } 
return true;
}

function GenPwd($length = 7)
{
  $password = "";
  $possible = "0123456789bcdfghjkmnpqrstvwxyz"; //no vowels

  $i = 0; 

  while ($i < $length) { 


    $char = substr($possible, mt_rand(0, strlen($possible)-1), 1);


    if (!strstr($password, $char)) { 
      $password .= $char;
      $i++;
    }

  }

  return $password;

}

function GenKey($length = 7)
{
  $password = "";
  $possible = "0123456789abcdefghijkmnopqrstuvwxyz"; 

  $i = 0; 

  while ($i < $length) { 


    $char = substr($possible, mt_rand(0, strlen($possible)-1), 1);


    if (!strstr($password, $char)) { 
      $password .= $char;
      $i++;
    }

  }

  return $password;

}


function logout()
{
global $db;
session_start();

if(isset($_SESSION['user_id']) || isset($_COOKIE['user_id'])) {
mysql_query("update `users` 
            set `ckey`= '', `ctime`= '' 
            where `id`='$_SESSION[user_id]' OR  `id` = '$_COOKIE[user_id]'") or die(mysql_error());
}           

/************ Delete the sessions****************/
unset($_SESSION['user_id']);
unset($_SESSION['user_name']);
unset($_SESSION['user_level']);
unset($_SESSION['HTTP_USER_AGENT']);
session_unset();
session_destroy(); 

/* Delete the cookies*******************/
setcookie("user_id", '', time()-60*60*24*COOKIE_TIME_OUT, "/");
setcookie("user_name", '', time()-60*60*24*COOKIE_TIME_OUT, "/");
setcookie("user_key", '', time()-60*60*24*COOKIE_TIME_OUT, "/");

header("Location: login.php");
}

// Password and salt generation
function PwdHash($pwd, $salt = null)
{
    if ($salt === null)     {
        $salt = substr(md5(uniqid(rand(), true)), 0, SALT_LENGTH);
    }
    else     {
        $salt = substr($salt, 0, SALT_LENGTH);
    }
    return $salt . sha1($pwd . $salt);
}

function checkAdmin() {

if($_SESSION['user_level'] == ADMIN_LEVEL) {
return 1;
} else { return 0 ;
}

}

?>

---

An alternative to your current protect script, ive made it without cookies:

<?php
//A basic login and session script I just whacked up 
session_start();

/**
 * cleanit cleans unwanted chars
 *
 * @param string $input
 * @return clean string containing only a-zA-Z0-9.,_ - 
 */
function cleanit($input){
    return preg_replace('/[^a-zA-Z0-9\.,_ -]/s', '', $input);
}

/**
 * auth function called on each page you want protected
 *
 * @param $_SESSION['user_name'] $logged_in_user
 * @param $_SESSION['user_hash'] $hash
 * @param $_POST['user'] (when logging in) $username
 * @param $_POST['pass'] (when logging in) $password
 * @param [login|check|logout] function control $exe
 * @return $_SESSION gets set returns LOGGED_IN|ERROR:MULTI:USERS|ACCESS_DENIDE|ACCESS_TIMEOUT|ACCESS_LOGGED_OUT
 */
function auth($logged_in_user,$hash,$username,$password,$exe) {
    global $db;
    if ($exe=='login') {
        //LOGIN////////////////////////////////////////////////
        $result = mysql_query('SELECT * from users where username="'.cleanit(mysql_real_escape_string($username)).'" and password="'.cleanit(mysql_real_escape_string(sha1($password))).'"',$db);
        $num = mysql_num_rows($result);
        if($num=='1') {
            session_regenerate_id();
            $_SESSION['user_status']='LOGGED_IN';
            while ($row = mysql_fetch_array($result)) {
                $_SESSION['user_id'] = $row['id'];
                $_SESSION['user_name'] = $row['username'];
                $_SESSION['user_hash'] = md5($_SERVER['REMOTE_ADDR']);
                $_SESSION['user_ip'] = cleanit($_SERVER['REMOTE_ADDR']);
                $_SESSION['user_date'] = time();
                $_SESSION['user_level'] = cleanit($row['user_level']);
            }
            $result2 = mysql_query('REPLACE into users values ("'.mysql_real_escape_string($_SESSION['user_id']).'","'.mysql_real_escape_string($_SESSION['user_name']).'","'.mysql_real_escape_string(sha1($password)).'","'.mysql_real_escape_string($_SESSION['user_hash']).'","'.mysql_real_escape_string($_SESSION['user_ip']).'","'.mysql_real_escape_string($_SESSION['user_date']).'","'.mysql_real_escape_string($_SESSION['user_level']).'")',$db);
            $return = 'LOGGED_IN';
            return $return;
        }elseif($num >='2') {
            $result = mysql_query('DELETE from users where username="'.mysql_real_escape_string($username).'" and password="'.mysql_real_escape_string(sha1($password)).'"');
            $error = 'ERROR:MULTI:USERS';
            return $error;
        }else {
            unset($_SESSION['user_id']);
            unset($_SESSION['user_name']);
            unset($_SESSION['user_hash']);
            unset($_SESSION['user_ip']);
            unset($_SESSION['user_date']);
            unset($_SESSION['user_level']);
            $_SESSION['user_status']=='';
            session_destroy();
            $return = 'ACCESS_DENIDE';
            return $return;
        }
        return $return;
    }

    if($exe=='check') {
        //CHECK////////////////////////////////////////////
        $result = mysql_query('SELECT hash,ip,user_date from users where username="'.mysql_real_escape_string($logged_in_user).'" and hash="'.mysql_real_escape_string($hash).'"',$db);
        if(mysql_num_rows($result)==1) {
            $rows = mysql_fetch_row($result);
            $timeout = (time()-1800);
            if($rows[2]<=$timeout){auth("","","","","logout");
            return'ACCESS_TIMEOUT';
            }
            if($hash==$rows[0] && $_SERVER['REMOTE_ADDR']==$rows[1]) {
                $return = 'LOGGED_IN';
                mysql_query('UPDATE users set user_date="'.time().'"',$db);
                return $return;
            }else {
                session_regenerate_id();
                $return = 'ACCESS_DENIDE';
                return $return;
            }
        }else{
            session_regenerate_id();
            $return = $_SESSION['user_status'];
            return $return;
        }
    }
    if($exe=='logout') {
        //LOGOUT///////////////////////////////////////////
        unset($_SESSION['user_id']);
        unset($_SESSION['user_name']);
        unset($_SESSION['user_hash']);
        unset($_SESSION['user_ip']);
        unset($_SESSION['user_date']);
        unset($_SESSION['user_level']);
        unset($_SESSION['user_status']);
        session_destroy();
        session_regenerate_id();
        $return = 'ACCESS_LOGGED_OUT';
        return $return;
    }
    if($exe=='') {
        //BLANK////////////////////////////////////////////
        unset($_SESSION['user_id']);
        unset($_SESSION['user_name']);
        unset($_SESSION['user_hash']);
        unset($_SESSION['user_ip']);
        unset($_SESSION['user_date']);
        unset($_SESSION['user_level']);
        unset($_SESSION['user_status']);
        session_destroy();
        session_regenerate_id();
        $return = 'FUNCTION.ERROR:DO.MISSING';
        return $return;
    }
    return $return;
}


/*
SQL
CREATE TABLE IF NOT EXISTS `users` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `username` varchar(45) NOT NULL DEFAULT '',
  `password` varchar(45) NOT NULL DEFAULT '',
  `hash` varchar(45) NOT NULL DEFAULT '',
  `ip` varchar(45) NOT NULL DEFAULT '',
  `user_date` varchar(45) NOT NULL DEFAULT '',
  `user_level` varchar(45) NOT NULL DEFAULT '',
  PRIMARY KEY (`id`)
) ENGINE=MyISAM  DEFAULT CHARSET=latin1;

INSERT INTO `users` (`id`, `username`, `password`, `hash`, `ip`, `user_date`, `user_level`) VALUES
(1, 'admin', '6c7ca345f63f835cb353ff15bd6c5e052ec08e7a', 'f528764d624db129b32c21fbca0cb8d6', '127.0.0.1', '1306757011', '1');

admin/admin1
*/


//Usage
/*--------------------------------*/
//login page
session_start();
if(isset($_REQUEST['user']) && isset($_REQUEST['pass'])){
    $user=cleanit($_REQUEST['user']);
    $pass=cleanit($_REQUEST['pass']);
    $_SESSION['user_status'] = auth("","",$user,$pass,"login");
    header('members.php');
}else{
    //Show login form
}
/*--------------------------------*/



/*--------------------------------*/
//Members page
session_start();
//Checks login on each page request put this on all pages you want to protect
$_SESSION['session_status'] = @auth($_SESSION['user_name'],$_SESSION['user_hash'],"","","check");

if($_SESSION['session_status']=='LOGGED_IN'){
    //Logged in norm user
}elseif($_SESSION['session_status']=='LOGGED_IN' && $_SESSION['user_level']==1){
    //Logged in as admin
}else{
    //Logged out
}

/*--------------------------------*/
//Logout
if($_REQUEST['do']=='logout'){
    auth("","","","","logout");
    header('Location: index.php');
}

?>

---

This is a comment posted here for better formatting.

You have to read the man pages on session_ functions work! Doing so will save you time and aggravation. Many here have given you hints on the possible source of your problem. For one, you cannot have ANY output whatsoever before session_start(). For 2, make sure you have error reporting turned on in your environnement.

if(!isset($_GET['link'])){ 
    $link = 1; 
} else { 
    $link = $_GET['link']; 
}

if ($link == 1) {
  echo "";
} elseif ($link == 23) {
  echo "";
} else {
  echo "";

}

This snippet at the top of your post will always make your script fail if you try to echo anything whatsoever. Again, friendly advice, take 15 minutes of your time and read the manual. You will have access to much more valuable first-hand information on those aspects of your work than by posting here out of laziness to get a quick fix. Then again, I probably am not the first one to tell you this.