PHP session management

login.php

<?php
require 'secsesh.php';
session_start();

if(/*credentials check out*/){
s_start();
}

header( 'Location: somePage.php' );

}

logout.php

<?php 
require 'secsesh.php';
session_start();

s_end();

otherFiles.php

<?php

require 'secsesh.php';
session_start();

if(s_check()){
  //do stuff
} else {
  header( 'Location: login.php' );
}

secsesh.php

<?php
//===CONFIGURATION===

// Name of the session id cookie
$GLOBALS['sessionName'] = "secID";

// How long should a session remain valid for?
// (in seconds)
$GLOBALS['sessionTimeout'] = 60*60*24;

// --Fingerprint Settings--

	// - Use fingerprints?
	$GLOBALS['useFingerprint'] = true;
	// - Use user agent in fingerprint?
	$GLOBALS['f_useUserAgent'] = true;
	// - Use IP address in fingerprint?
	$GLOBALS['f_useIPaddress'] = true;

// --END Fingerprint Settings--

//===END CONFIGURATION===

ini_set( 'session.use_only_cookies', TRUE );				
ini_set( 'session.use_trans_sid', FALSE );
ini_set( 'session.cookie_httponly', TRUE );
// ini_set( 'session.gc_maxlifetime', $sessionTimeout );
// ini_set( 'session.cookie_lifetime', $sessionTimeout );
ini_set( 'session.name', $sessionName );

session_name($sessionName);


function s_end(){
	if($_SESSION["loggedIn"]){
		$_SESSION["loggedIn"]=false;
		session_destroy();
	}
}

function s_start(){
	if(!$_SESSION["loggedIn"]){
		session_regenerate_id();
		$_SESSION["loggedIn"] = true;
		$_SESSION["lastActivity"] = time();
		if($GLOBALS['useFingerprint']){
			$_SESSION["fingerprint"] = generateFingerprint();
		}
	}
}

function generateFingerprint(){
	$fingerprint = "";
	if($GLOBALS['f_useUserAgent']){
		$fingerprint .= $_SERVER['HTTP_USER_AGENT'];
	}
	$fingerprint .= '_._'; //separator
	if($GLOBALS['f_useIPaddress']){
		$fingerprint .= $_SERVER['REMOTE_ADDR'];
	}
	$fingerprint = md5($fingerprint);
	return $fingerprint;
}

function s_check(){
	if($_SESSION["loggedIn"]){
		
		if($GLOBALS['useFingerprint'] && generateFingerprint() !== $_SESSION["fingerprint"]){
			return false;
		}
		
		if((time() - $_SESSION['lastActivity']) > $GLOBALS['sessionTimeout']){
			$_SESSION["loggedIn"]=false;
			session_destroy();
			return false;
		} else {
			$_SESSION['lastActivity'] = time();
			return true;	
		}
	} else {
			return false;
	}
}