As of PHP 7.3.0 the setcookie() method supports the SameSite attribute in its options and will accept None as a valid value.
For earlier versions of PHP, you can set the header() directly:
header('Set-Cookie: cross-site-cookie=bar; SameSite=None; Secure');
Instead of this:
<?php setcookie( "TestCookie", $value, strtotime( '+30 days' ) ); ?>
You can this:
<?php setcookie( "TestCookie"); ?>
Be warned! PHP will mangle the names of incoming cookies far more than others have detailed below!
Theoretically, the following non-alphanumeric characters are allowed in a cookie name:
!#$%&'()*+-./:<>?@[]^_`{|}~
However, if you do this:
<?php
setcookie('!#$%&\'()*+-./:<>?@[]^_`{|}~', 123);
setcookie('!#$%&\'()*+-./:<>?@[^_`{|}~', 466);
setcookie('!#$%&\'()*+-./:<>?@]^_`{|}~', 789);
setcookie('!#$%&\'()*+-./:<>?@^_`{|}~', 'abc');
?>
then this:
<?php
print_r($_COOKIE);
?>
you get this back:
<?php
Array
(
[!#$%&'()*_-_/:<>?@] => Array
(
[0] => 123
)
[!#$%&'()*_-_/:<>?@_^_`{|}~] => 456
[!#$%&'()*_-_/:<>?@]^_`{|}~] => 789
[!#$%&'()*_-_/:<>?@^_`{|}~] => abc
)
?>
The rules would appear to be as follows:
- Convert all periods to underscores (as detailed below).
- Convert all plus signs to underscores.
- Convert all unmatched open square brackets to underscores.
- Square bracket pairs mean the value is an array; ignore everything after the closing square bracket.
Note that these rules are only applied by PHP when generating the $_COOKIE array; the cookie name part in the headers sent by your browser and as received by PHP are exactly as you specified above;
<?php
echo $_SERVER['HTTP_COOKIE'];
?>
gives
<?php
!#$%&'()*+-./:<>?@[]^_`{|}~=123; !#$%&'()*+-./:<>?@[^_`{|}~=456; !#$%&'()*+-./:<>?@]^_`{|}~=789; !#$%&'()*+-./:<>?@^_`{|}~=abc
?>
It would be nice if the official notes mentioned this conversion.
I haven't seen this mentioned here and had a lot of issues (and created a lot of stupid hacks) before I figured this out.
If you have a couple of environments for example, and are trying to set cookies on two domains:
example.com (main site)
dev.example.com (dev site)
In this case your (same named) cookies will interfere with each other if you're trying to set cookies with the domain parameter.
Simply use an empty string for the domain parameter and the cookies will refer to each host separately.
If you use the subdomain www. on the main site this won't be an issue, but without a subdomain you'll have issues with reading each others' cookies.
How to store a cookie in php with JSON and read it in JavaScript correctly without using setcookieraw
$defaultActions = array(
'1' => '0',
'2' => '0',
'3' => '0',
'4' => '0',
'5' => '0',
'6' => '0',
'7' => '0',
'8' => '0',
'9' => '0',
'10' => '0'
);
$json_str = json_encode($defaultActions);
//delete all cookies
if (isset($_SERVER['HTTP_COOKIE'])) {
$cookies = explode(';', $_SERVER['HTTP_COOKIE']);
foreach($cookies as $cookie) {
$parts = explode('=', $cookie);
$name = trim($parts[0]);
setcookie($name, '', time()-1000);
setcookie($name, '', time()-1000, '/');
}
}
//setrawcookie("test", $json_str, false,"/",false);
setcookie("test", $json_str, false,"/",false);
?>
<script type="text/javascript">
function getCookie(name) {
var value = "; " + document.cookie;
var parts = value.split("; " + name + "=");
if (parts.length == 2)
return parts.pop().split(";").shift();
}
console.log(decodeURIComponent(getCookie('test')));
</script>
It's worth a mention: you should avoid dots on cookie names.
<?php
// this will actually set 'ace_fontSize' name:
setcookie( 'ace.fontSize', 18 );
?>
> "When deleting a cookie you should assure that the expiration date is in the past, to trigger the removal mechanism in your browser"
This part of the documentation is no longer accurate. On my version of PHP (5.6.28) setting a null, empty string or boolean false value causes the server to ignore your expire date parameter and always sends value "deleted" and expire date 1970-01-01 00:00:01.
Of notice, the cookie when set with a zero expire or ommited WILL not expire when the browser closes.
What happens is that the browser, when closes the window, if it is a well behaved browser, will delete the cookie from the cookie store.
However, the cookie will survive in the server until the garbage collector removes the session, which will happen only when it kicks in and checks the specified session is out of bounds of the setting stated in:
http://php.net/manual/en/session.configuration.php#ini.session.gc-maxlifetime
Please check also:
http://php.net/manual/en/session.security.ini.php
And in case of doubt, PHP runs on the webserver and has no way whatsoever to interact with a browser apart from receiving requests and answering with responses, so assuming that a cookie will be removed from a browser is just an "hint" for the browser. There is no warranty that such will happen as instructed.
That is one of the reasons why the cookie values sent to browsers by some platforms are encrypted and timestamped, to ensure that they are actual and not tampered.
exmaple with test.com；
setcookie('empty_domain','value',time()+3600,'')
equal test.com
setcookie('test_com_domain','value',time()+3600,'','test.com')
equal .test.com
setcookie('dot_test_com_domain','value',time()+3600,'','.test.com')
equal .test.com
ps: .test.com has its self and child domain
Note that at least in PHP 5.5 setcookie() removes previously set cookies with the same name (even if you've set them via header()), so previously fired Set-Cookie headers with e.g. PHPSESSID name are not flushed to the browser. Even headers_list() doesn't see them after session_start():
header("Set-Cookie: PHPSESSID=abc; path=/; domain=.sub.domain.com");
header("Set-Cookie: PHPSESSID=abc; path=/; domain=.domain.com");
print_r(headers_list()); // here you see two Set-Cookie headers with domains for PHPSESSID
session_id('abc');
session_start();
print_r(headers_list()); // here you don't; you see only one Set-Cookie produced by session_start()
Caveat: if you use URL RewriteRules to get stuff like this: domain.com/bla/stuf/etc into parameters, you might run into a hickup when setting cookies.
At least in my setup a change in one of the parameters resulted in the cookie not being 'there' anymore.
The fix is simple: specify the domain. '/' will usualy do fine.
Instead of this:
<?php setcookie( "TestCookie", $value, time()+(60*60*24*30) ); ?>
You can this:
<?php setcookie( "TestCookie", $value, strtotime( '+30 days' ) ); ?>
Want to remove a cookie?
Many people do it the complicated way:
setcookie('name', 'content', time()-3600);
But why do you make it so complicated and risk it not working, when the client's time is wrong? Why fiddle around with time();
Here's the easiest way to unset a cookie:
setcookie('name', 'content', 1);
Thats it.
#cookies.php
/*This code will demonstrate use of cookies with PHP
It is very easy to understand and is better for beginner to
understand and get idea about power of cookies when used
with PHP.Here we give user a form to choose colors he/she
likes for website and when he/she visits site again within one
hour his/her settings are saved and read from cookie
and he/she doesn't have to set the page color and page
text color again.You can change time from 3600
seconds to whatever you deem appropriate in your case.
if you don't understand anything please email me*/
<?php
#checking if form has been submitted
if (isset($_POST['submitted'])){
#if yes (form is submitted) assign values from POST array to variables
$newbgColor=$_POST['bgColor'];
$newtxtColor=$_POST['txtColor'];
#set cookies
setcookie("bgColor",$newbgColor,time()+3600);
setcookie("txtColor",$newtxtColor,time()+3600);
}
#in case user has come for first time and cookies are not set then
if ((!isset($_COOKIE['bgColor']) ) && (!isset($_COOKIE['txtColor']))){
$bgColor = "Black";
$txtColor="White";
}
#if cookies are set then use them
else{
$bgColor = $_COOKIE['bgColor'];
$txtColor = $_COOKIE['txtColor'];
}
?>
<!-- HTML Page-->
<html>
<body bgcolor="<?php echo $bgColor ?>" text="<?php echo $txtColor ?>">
<form action= "<?php echo $_SERVER['PHP_SELF']; ?>" method ="POST">
<p>Body Color:</p>
<select name=bgColor>
<option value ="Red">Red</option>
<option value ="Green" selected>Green</option>
<option value ="Blue">Blue</option>
<option value ="Yellow">Yellow</option>
<option value ="Black">Black</option>
<option value ="Brown">Brown</option>
<option value ="White">White</option>
</select>
<p>Text Color:</p>
<select name=txtColor>
<tion value ="Red">Red</option>
<option value ="Green" selected>Green</option>
<option value ="Blue">Blue</option>
<option value ="Yellow">Yellow</option>
<option value ="Black">Black</option>
<option value ="Brown">Brown</option>
<option value ="White">White</option>
</select>
<input type ="hidden" name="submitted" value="true"></br>
<input type="submit" value="remind">
</form>
</body>
</html>
If you're having problem with IE not accepting session cookies this could help:
It seems the IE (6, 7, 8 and 9) do not accept the part 'Expire=0' when setting a session cookie. To fix it just don't put any expire at all. The default behavior when the 'Expire' is not set is to set the cookie as a session one.
(Firefox doesn't complains, btw.)
I was searching for a simple example of creating a cookie, storing a random number and updating it on refresh. I couldn't find one so I had to figure it out on my own....
- - - -
One thing to *NOTE* is technically you can't update a cookie, you can only overwrite it with a new one with the same name.
- - - -
This creates a random number, stores it in a cookie, then references it on refresh, checks for duplicates and does necessary correction, then stores it again, rinse and repeat...
<?php
ob_start();
$MaxCount = 4;// set the max of the counter, in my tests "4" = (0,1,2,3) I adjusted below (+1) to get a "real" 4 (0,1,2,3,4) this is in reality 5 keys to humans, you can adjust script to eliminate "0", but my script makes use of the "0"
$random =(rand()%($MaxCount+1));//give me a random number limited by the max, adding "1" because computers start counting at "0"
if(!isset($_COOKIE['random'])){// check if random number cookie is not set
//echo"not set";
setcookie('random', $random);//set the cookie for the first time
}else{
$lastRandom= $_COOKIE['random']; //hold the last number if it was set before
if($lastRandom == $random){//some logic to avoid repeats
if($random < $MaxCount){//if below max, add 1
$random++;
//echo "under the max, adding 1, ";
}elseif($random >= ($MaxCount-1)){// if for some reason the random number is more than max or equal to it -1, and an additional -1 for max count in initial var (so in reality this -1 from intial max var, and -1 from $random which should be the same number)
$random--;
//echo "hit the max, subtracting 1, ";
}else{
$random++;
//echo "no case match, adding 1, ";
}
//echo "(".$lastRandom.", ".$random. "), they matched initally - was it fixed?";
}else{
//echo "(".$lastRandom.", ".$random. "), they DO NOT match";
setcookie('random', $random);
}
//echo"is set: {$_COOKIE['random']}";
}
ob_end_flush();
?>
My 2 functions to use "live cookies":
<?php
function SetCookieLive($name, $value='', $expire = 0, $path = '', $domain='', $secure=false, $httponly=false)
{
$_COOKIE[$name] = $value;
return setcookie($name, $value, $expire, $path, $domain, $secure, $httponly);
}
function RemoveCookieLive($name)
{
unset($_COOKIE[$name]);
return setcookie($name, NULL, -1);
}
?>
IE7 can have trouble with settings cookies that are embedded in an iframe. The problem lies with a W3C standard called Platform for Privacy Preferences or P3P for short.
To overcome, include the header:
header('P3P:CP="IDC DSP COR ADM DEVi TAIi PSA PSD IVAi IVDi CONi HIS OUR IND CNT"');
before setting the cookie.
For those of your banging your head as to why a cookie is not present when Internet Explorer 6 prints, the explanation is quite interesting. After a bit of investigation, a cookie with an expiration time other than 0 fails to be passed from IE6 to the server when printing. A cookie with an expiration time of 0 is sent.
Therefore:
setcookie("TestCookie", $value, time()+3600); //will not be sent from Print / Print Preview in IE6
setcookie("TestCookie", $value, 0); //will be sent from Print / Print Preview in IE6
I'll let everyone figure out who's bright idea it was to not send normal expiring cookies when printing in IE6...
A period in a cookie name (like user.name) seems to show up in the $_COOKIE array as an underscore (so user_name). This means that for example $_COOKIE["user_name"] must be used to read a cookie that has been set with setcookie("user.name" ...), which is already rather confusing.
Furthermore the variable $_COOKIE["user_name"] will retain the value set by setcookie("user.name" ...) and no amount of calling setcookie("user_name" ...) will alter this value. This is rather trivially fixed by clearing the "user.name" cookie, but it can take a while to realize this since there's only "user_name" in $_COOKIE.
Hope this saves someone some time.
You can also delete cookies by supplying setcookie an empty value.
setcookie("w3p_cookie", "");
The server my php code is running on has sessions disabled so I am forced to store a fair bit of arbitrary data in cookies. Using array names was impractical and problematic, so I implemented a splitting routine. I do not serialize any class instances, just arrays and simple objects.
In a nutshell, when setting a cookie value, I serialize it, gzcompress it, base64 encode it, break it into pieces and store it as a set of cookies. To fetch the cookie value I get the named piece then iterate through piece names rebuilding the base64 data, then reverse the rest of the process. The only other trick is deleting the pieces correctly.
Sessions are better, but if they are not available this is a viable alternative. I chose gz over bz for compression because it looked faster with only slightly worse ratios.
Here is a simplified version of my implementation. This is a good starting point but is not suitable for most uses. For example, the domain and path are hard coded and no return values are checked for validity.
<?php
define( 'COOKIE_PORTIONS' , '_piece_' );
function clearpieces( $inKey , $inFirst ) {
$expire = time()-3600;
for ( $index = $inFirst ; array_key_exists( $inKey.COOKIE_PORTIONS.$index , $_COOKIE ) ; $index += 1 ) {
setcookie( $inKey.COOKIE_PORTIONS.$index , '' , $expire , '/' , '' , 0 );
unset( $_COOKIE[$inKey.COOKIE_PORTIONS.$index] );
}
}
function clearcookie( $inKey ) {
clearpieces( $inKey , 1 );
setcookie( $inKey , '' , time()-3600 , '/' , '' , 0 );
unset( $_COOKIE[$inKey] );
}
function storecookie( $inKey , $inValue , $inExpire ) {
$decode = serialize( $inValue );
$decode = gzcompress( $decode );
$decode = base64_encode( $decode );
$split = str_split( $decode , 4000 );//4k pieces
$count = count( $split );
for ( $index = 0 ; $index < $count ; $index += 1 ) {
$result = setcookie( ( $index > 0 ) ? $inKey.COOKIE_PORTIONS.$index : $inKey , $split[$index] , $inExpire , '/' , '' , 0 );
}
clearpieces( $inKey , $count );
}
function fetchcookie( $inKey ) {
$decode = $_COOKIE[$inKey];
for ( $index = 1 ; array_key_exists( $inKey.COOKIE_PORTIONS.$index , $_COOKIE ) ; $index += 1 ) {
$decode .= $_COOKIE[$inKey.COOKIE_PORTIONS.$index];
}
$decode = base64_decode( $decode );
$decode = gzuncompress( $decode );
return unserialize( $decode );
}
?>
Note that the $_COOKIE variable not will hold multiple cookies with the same name. It is legitimate to set two cookies with the same name to the same host where the sub domain is different.
<?php
setcookie("testcookie", "value1hostonly", time(), "/", ".example.com", 0, true);
setcookie("testcookie", "value2subdom", time(), "/", "subdom.example.com", 0, true);
?>
The next request from the browser will have both cookies in the $_SERVER['HTTP_COOKIE'] variable, but only one of them will be found in the $_COOKIE variable. Requests to subdom.example.com will have both cookies, while browser request to example.com or www.example.com only sends the cookie with the "value1hostonly" value.
<?php
$kaker = explode(";", $_SERVER['HTTP_COOKIE']);
foreach($kaker as $val){
$k = explode("=", $val);
echo trim($k[0]) . " => " . $k[1];
}
// output
testcookie => value1hostonly
testcookie => value2subdom
?>
Here's a more advanced version of the php setcookie() alternative function:
<?php
/**
* A better alternative (RFC 2109 compatible) to the php setcookie() function
*
* @param string Name of the cookie
* @param string Value of the cookie
* @param int Lifetime of the cookie
* @param string Path where the cookie can be used
* @param string Domain which can read the cookie
* @param bool Secure mode?
* @param bool Only allow HTTP usage?
* @return bool True or false whether the method has successfully run
*/
function createCookie($name, $value='', $maxage=0, $path='', $domain='', $secure=false, $HTTPOnly=false)
{
$ob = ini_get('output_buffering');
// Abort the method if headers have already been sent, except when output buffering has been enabled
if ( headers_sent() && (bool) $ob === false || strtolower($ob) == 'off' )
return false;
if ( !empty($domain) )
{
// Fix the domain to accept domains with and without 'www.'.
if ( strtolower( substr($domain, 0, 4) ) == 'www.' ) $domain = substr($domain, 4);
// Add the dot prefix to ensure compatibility with subdomains
if ( substr($domain, 0, 1) != '.' ) $domain = '.'.$domain;
// Remove port information.
$port = strpos($domain, ':');
if ( $port !== false ) $domain = substr($domain, 0, $port);
}
// Prevent "headers already sent" error with utf8 support (BOM)
//if ( utf8_support ) header('Content-Type: text/html; CHARSET=gb2312');
header('Set-Cookie: '.rawurlencode($name).'='.rawurlencode($value)
.(empty($domain) ? '' : '; Domain='.$domain)
.(empty($maxage) ? '' : '; Max-Age='.$maxage)
.(empty($path) ? '' : '; Path='.$path)
.(!$secure ? '' : '; Secure')
.(!$HTTPOnly ? '' : '; HttpOnly'), false);
return true;
}
?>
Regards,
Isaak
If you're looking to set multiple values in your cookie (rather than setting multiple cookies) you might find these useful.
<?php
function build_cookie($var_array) {
if (is_array($var_array)) {
foreach ($var_array as $index => $data) {
$out.= ($data!="") ? $index."=".$data."|" : "";
}
}
return rtrim($out,"|");
}
function break_cookie ($cookie_string) {
$array=explode("|",$cookie_string);
foreach ($array as $i=>$stuff) {
$stuff=explode("=",$stuff);
$array[$stuff[0]]=$stuff[1];
unset($array[$i]);
}
return $array;
}
?>
Hopefully someone finds these useful.
if you are having problems seeing cookies sometimes or deleting cookies sometimes, despite following the advice below, make sure you are setting the cookie with the domain argument. Set it with the dot before the domain as the examples show: ".example.com". I wasn't specifying the domain, and finally realized I was setting the cookie when the browser url had the http://www.example.com and later trying to delete it when the url didn't have the www. ie. http://example.com. This also caused the page to be unable to find the cookie when the www. wasn't in the domain. (When you add the domain argument to the setcookie code that creates the cookie, make sure you also add it to the code that deletes the cookie.)
About the delete part, I found that Firefox only remove the cookie when you submit the same values for all parameters, except the date, which sould be in the past. Submiting blank values didn't work for me.
Example :
- set -
<?php setcookie( "name", "value", "future_timestamp", "path", "domain" ); ?>
- delete -
<?php setcookie( "name", "value", "past_timestamp", "path", "domain" ); ?>
Jonathan
Be careful of using the same cookie name in subdirectories. Setting a simple cookie
<?php setcookie("region", $_GET['set_region']); ?>
both in the root / and for instance in this case /admin/ will create 2 cookies with different paths. In reading the cookies back only the first one is read regardless of path.
if you only want to do something once per unique visitor, you can test if a cookie is set, and if not, set the cookie and perform the action. This being the poorman's version, it has a problem, where if a user is blocking cookies they will appear as a first time visitor each time. What you can do to avoid this is to set a test cookie first and check that it exists. If it exists, then check to see if your second cookie has been set. If the first one is set, but the second isn't, then you know this is a first time visitor.
If you want to delete all cookies on your domain, you may want to use the value of:
<?php $_SERVER['HTTP_COOKIE'] ?>
rather than:
<?php $_COOKIE ?>
to dertermine the cookie names.
If cookie names are in Array notation, eg: user[username]
Then PHP will automatically create a corresponding array in $_COOKIE. Instead use $_SERVER['HTTP_COOKIE'] as it mirrors the actual HTTP Request header.
<?php
// unset cookies
if (isset($_SERVER['HTTP_COOKIE'])) {
$cookies = explode(';', $_SERVER['HTTP_COOKIE']);
foreach($cookies as $cookie) {
$parts = explode('=', $cookie);
$name = trim($parts[0]);
setcookie($name, '', time()-1000);
setcookie($name, '', time()-1000, '/');
}
}
?>
something that wasn't made clear to me here and totally confused me for a while was that domain names must contain at least two dots (.), hence 'localhost' is invalid and the browser will refuse to set the cookie! instead for localhost you should use false.
to make your code work on both localhost and a proper domain, you can do this:
<?php
$domain = ($_SERVER['HTTP_HOST'] != 'localhost') ? $_SERVER['HTTP_HOST'] : false;
setcookie('cookiename', 'data', time()+60*60*24*365, '/', $domain, false);
?>
You can be sure about the cookie files contents weren't changed.
<?php
$Seperator = '--';
$uniqueID = 'Ju?hG&F0yh9?=/6*GVfd-d8u6f86hp';
$Data = 'Ahmet '.md5('123456789');
setcookie('VerifyUser', $Data.$Seperator.md5($Data.$uniqueID));
if ($_COOKIE) {
$Cut = explode($Seperator, $_COOKIE['VerifyUser']);
if (md5($Cut[0].$uniqueID) === $Cut[1]) {
$_COOKIE['VerifyUser'] = $Cut[0];
} else {
die('Cookie data is invalid!!!');
}
}
echo $_COOKIE['VerifyUser'];
?>
Create a unique id for your site and create a hash with md5($Data.$uniqueID). Attacker can understant that it must be re-hash after change cookie content.
But doesn't. Because cannot guess your unique id. Seperate your hash and data with seperator and send that cookie. Control that hash of returned value and your unique id's is same returned hash. Otherwise you have to stop attack. Sorry for my poor english!
If you are having issues with IE7 and setcookie(), be sure to verify that the cookie is set via http for http sites, and https for https site.
Also, if the time is incorrect on your server, IE7 will also disallow those cookies from being set.
Note when setting "array cookies" that a separate cookie is set for each element of the array.
On high traffic sites, this can substantially increase the size of subsequent HTTP requests from clients (including requests for static content on the same domain).
More importantly though, the cookie specification says that browsers need only accept 20 cookies per domain. This limit is increased to 50 by Firefox, and to 30 by Opera, but IE6 and IE7 enforce the limit of 20 cookie per domain. Any cookies beyond this limit will either knock out an older cookie or be ignored/rejected by the browser.
The following code snippet combines abdullah's and Charles Martin's examples into a powerful combination function (and fixes at least one bug in the process):
<?php
function set_cookie_fix_domain($Name, $Value = '', $Expires = 0, $Path = '', $Domain = '', $Secure = false, $HTTPOnly = false)
{
if (!empty($Domain))
{
// Fix the domain to accept domains with and without 'www.'.
if (strtolower(substr($Domain, 0, 4)) == 'www.') $Domain = substr($Domain, 4);
$Domain = '.' . $Domain;
// Remove port information.
$Port = strpos($Domain, ':');
if ($Port !== false) $Domain = substr($Domain, 0, $Port);
}
header('Set-Cookie: ' . rawurlencode($Name) . '=' . rawurlencode($Value)
. (empty($Expires) ? '' : '; expires=' . gmdate('D, d-M-Y H:i:s', $Expires) . ' GMT')
. (empty($Path) ? '' : '; path=' . $Path)
. (empty($Domain) ? '' : '; domain=' . $Domain)
. (!$Secure ? '' : '; secure')
. (!$HTTPOnly ? '' : '; HttpOnly'), false);
}
?>
Basically, if the domain parameter is supplied, it is converted to support a broader range of domains. This behavior may or may not be desireable (e.g. could be a security problem depending on the server) but it makes cookie handling oh-so-much-nicer (IMO).
If you intend to use persistent cookies (vice session cookies that are deleted when the browser is closed) be aware:
1) Firefox appears to require that you include all paramaters, or it will ignore the expiration and treat the cookie as a session cookie
2) My version of firefox (1.5.0.6) defaults to 'keep cookies until i close firefox' , which essentially makes every cookie a session cookie. This of course sucks for devs, but i suppose is supposed to be a security feature for the end user. If the user wants to configure firefox to respect the expiration date and retain cookies beyond the session, the user must change it to 'keep cookies until they expire'.
You can use cookies to prevent a browser refresh repeating some action from a form post... (providing the client is cookie enabled!)
<?php
//Flag up repeat actions (like credit card transaction, etc)
if(count($_POST)>0) {
$lastpost= isset($_COOKIE['lastpost']) ? $_COOKIE['lastpost'] : '';
if($lastpost!=md5(serialize($_POST))) {
setcookie('lastpost', md5(serialize($_POST)));
$_POST['_REPEATED']=0;
} else {
$_POST['_REPEATED']=1;
}
}
//At this point, if $_POST['_REPEATED']==1, then the user
//has hit the refresh button; so don't do any actions that you don't
//want to repeat!
?>
Hope that helps :)
Gareth
If you want to delete all the cookies set by your domain, you may run the following:
<?php
$cookiesSet = array_keys($_COOKIE);
for ($x=0;$x<count($cookiesSet);$x++) setcookie($cookiesSet[$x],"",time()-1);
?>
Very useful when doing logout scripts and the cookie name may have changed (long story).
Note on setting cookies allowing access to sites:
If you are not using something "personal" from the computer that you are sending the cookie too watch out. Via javascript it is possible to steal cookies from other users. Thus allowing the stealer to login to your site as another user that might not have access otherwise. Try to add something like the user's ip in the cookie and allowing access from that ip only with the stored cookie data.
[Editor's note: ... or simply use sessions. You can't be sure that the visitor will use the same IP the next visit. Not even on the next request (thanks to proxy servers)]
When using your cookies on a webserver that is not on the standard port 80, you should NOT include the :[port] in the "Cookie domain" parameter, since this would not be recognized correctly.
I had the issue working on a project that runs on multiple servers (development, production, etc.). One of the servers is running on a different port (together with other websites that run on the same server but on different ports).