html page not getting cookies through libcurl

Question

i modified my previous code. you can see my previous post if your intersted setting cookie through curl But here is a fresh beginning my new code looks linke this i have a php file using curl like this

<?php
$ch=curl_init();
$url="http://localhost/javascript%20cookies/test_cookies.php";
curl_setopt($ch,CURLOPT_URL,$url);
curl_setopt($ch,CURLOPT_COOKIEFILE,dirname(__FILE__) . "/cookie.txt");
curl_setopt($ch,CURLOPT_FOLLOWLOCATION,1);
curl_exec($ch);
curl_close($ch);
?>

the file test_cookies.php looks like this

<?php
if($_COOKIE['user']==1)
{
header("Set-Cookie:user=1; color=blue");
header("Location:http://localhost/javascript%20cookies/test_cookies.html");
}
?>

the file test_cookies.html has some javascript that checks for cookies and if it finds those cookies then it displays the text accordingly. the php file with curl code is sending the cookies and the test_cookies.php is setting the cookie and redirecting to the page test_cookies.html but this page is not receiving the cookies and thus it is not not showing the content accordingly. can somebody tell me whats the problem now?

here are the headers i get displayed in firefox on setting CURLOPT_HEADER to true

HTTP/1.1 302 Found Date: Mon, 16 May 2011 15:03:59 GMT Server: Apache/2.2.14 (Win32) DAV/2 mod_ssl/2.2.14 OpenSSL/0.9.8l mod_autoindex_color PHP/5.3.1 mod_apreq2-20090110/2.7.1 mod_perl/2.0.4 Perl/v5.10.1 X-Powered-By: PHP/5.3.1 Set-Cookie: user=1; color=blue Location: http://localhost/javascript%20cookies/test_cookies.html Content-Length: 0 Content-Type: text/html HTTP/1.1 200 OK Date: Mon, 16 May 2011 15:03:59 GMT Server: Apache/2.2.14 (Win32) DAV/2 mod_ssl/2.2.14 OpenSSL/0.9.8l mod_autoindex_color PHP/5.3.1 mod_apreq2-20090110/2.7.1 mod_perl/2.0.4 Perl/v5.10.1 Last-Modified: Mon, 16 May 2011 12:13:24 GMT ETag: "11000000013d0c-493-4a363950a70f3" Accept-Ranges: bytes Content-Length: 1171 Content-Type: text/html

you can see that there are two set of headers displayed.is this because i am making 2 calls to header?

Answer 1

i will now explain what i was trying to do. i had an html page that asked for some verification code and then it sent that verification code to a php script which on verifying the code set a cookie and redirected to the same html page. the html page had some externally linked javascript which on checking the cookie value displayed the content of the page with some tweaking. i am now writing the code for this

the html file with content and form

test_cookies.html

    //some css,javascript and html and then a form
<form method="post" action="http://localhost/javascript%20cookies/test_cookies.php">

the php file which verifies the code

test_cookies.php

if($_POST['value']=="code")
setcookie("user",1);
if($_POST['value']!="code")
setcookie("user",1,time()-1);
header("Location:http://localhost/javascript%20cookies/test_cookies.html");

and now the php file with curl code

curl_cookies.php

<?php
$ch=curl_init();
$url="http://localhost/javascript%20cookies/test_cookies.php";
$post="value=code";     //here i have hard-coded the pst value for a demo but i could have got this from the user
curl_setopt($ch,CURLOPT_URL,$url);
curl_setopt($ch,CURLOPT_POST,1);
curl_setopt($ch,CURLOPT_POSTFIELDS,$post);
curl_setopt($ch,CURLOPT_HEADER,1);
curl_setopt($ch,CURLOPT_RETURNTRANSFER,1);
$res=curl_exec($ch);
curl_close($ch);
preg_match('/Location: (.*)\s/',$res,$location);
preg_match('/Set-Cookie: (.*)\s/',$res,$cookie);
$cookie=rtrim($cookie[0])."; path=/ ";         //path needed to be changed because curl_cookies.php and test_cookies.html are in different directories. 
header($cookie);
header($location[0]);
?>

this finally worked and the browser is displaying the tweaked content. this thing taught me a lot about http. Thanks to all who helped me when i was in dark.

Answer 2

It is not clear what you are trying to achieve with the code. You'd get better help if you explain why you are doing this. It is probable that your approach is wrong and you could get the ultimate result with a different/simpler approach.

And now to answer your question, this is what happens:

1. From your browser, you send a GET request to curl.php (the name I use for your first file),
2. curl in that file checks cookie.txt and finds user=1, so it sends a GET request to test_cookies.php and sends the cookie with the request
3. test_cookies.php sees that user=1 is true, so it sends a header to curl.php and asks it to set two cookies: user=1 and color=blue (for the first cookie this is pointless, user=1 is already set, but let's ignore this as no harm is done)
4. You have not set CURLOPT_COOKIEJAR option, so when curl.php receives the set cookie header it does not give a damn (nothing happens)
5. Next, test_cookies.php sends a redirect header to curl.php, since you have set CURLOPT_FOLLOWLOCATION,1, curl.php sends another GET request, this time to get test_cookies.html
6. Content of test_cookies.html is returned to curl.php,
7. curl_exec($ch); causes the returned content (source of test_cookies.html) be echoed back to your browser,
8. Your browser parses what it received and the javascript is executed. It checks for a cookie named user and does not find one, so it displays content for when there is no cookie (because there isn't).

Now, you may wonder what happens if you add:

curl_setopt($ch,CURLOPT_COOKIEJAR,dirname(__FILE__) . "/cookie.txt");

What happens is that your cookie.txt will be updated in step 4 and will have two cookies; user=1 and color=blue. But this does NOT give you the result you expect. Because header("Set-Cookie:user=1; color=blue"); is instructing curl to set the cookie, and curl does this by storing the cookies in the file you specified in CURLOPT_COOKIEJAR option. So, even though you added that option, when you reach step 8 javascript will not find that cookie, because the browser you use does not know or care about your cookie.txt, it looks somewhere else to check if a cookie exists. In Google Chrome for instance the format is SQLite and for XP the cookies are stored in %USERPROFILE%\Local Settings\Application Data\Google\Chrome\User Data\Default\Cookies.