Codeigniter: Session set_flashdata() - Error '502 Bad Gateway'

[julianfuerderer]

Hello,

i dont know if it is a bug:

I got an 502 Bad Gateway-Error after an Ajax-Request.
In the target controller/method i have setted 3 flashdata-session-items:

$this->session->set_flashdata("success","true");
$this->session->set_flashdata("success_to_user_id","1");
$this->session->set_flashdata("success_something_else","xyz");

The request successfully finished. But then, when i refresh the site
(window.location.reload or F5) i got an '502 Bad Gateway' Error.

After playing around I have fixed that error:

I reduced the 3 set_flashdata() calls to 1. Then it works, no more 502.

So:

Less or equal 2x $this->session->set_flashdata(); = OK, NO ERROR

Greater or equal 3x $this->session->set_flashdata(); = ERROR 502 BAD GATEWAY

Is this a bug ?

Greetings,
Julian Fuerderer

[pilathraj]

You are correct, i've same issue...

[AkenRoberts]

• Have you tested it using CI 3.0 to see if it's been fixed yet?
• Are you using DB, cookie, or native sessions?
• Can you provide the actual code you're using?

Things like this require a lot more than just "this didn't work".

[simonl2002]

I ran into this issue while using HaProxy load balancing between apache servers running a web app running CI 2.

This issue is caused by how codeigniter session class cleans up the flash cookie information.
In the CI_Session class function _flashdata_mark()

   function _flashdata_mark()
        {
                $userdata = $this->all_userdata();
                foreach ($userdata as $name => $value)
                {
                        $parts = explode(':new:', $name);
                        if (is_array($parts) && count($parts) === 2)
                        {
                                $new_name = $this->flashdata_key.':old:'.$parts[1];
                                $this->set_userdata($new_name, $value);
                                $this->unset_userdata($name);
                        }
                }
        }

The problem is that for each flash key you have that needs to be destroyed set_userdata(...) and unset_userdata(...) are called, each of which behind the scenes results in a $this->sess_write() being called which will call $this->_set_cookie(...).

So for each piece of flashdata you end up with 2 set cookie calls. That's rather ugly.

Anyway, my fix was to have set_userdata(...) and unset_userdata(...) are called only a single time.

function _flashdata_mark()
        {
                $userdata = $this->all_userdata();
                $newUserData = array();
                $userDataToUnset = array();
                foreach ($userdata as $name => $value)
                {
                        $parts = explode(':new:', $name);
                        if (is_array($parts) && count($parts) === 2)
                        {
                                $new_name = $this->flashdata_key.':old:'.$parts[1];
                                $newUserData[$new_name] = $value;
                                $userDataToUnset[$name] = '';
                                //if we call these for each flash key we end up with a TON of set-cookie headers
                                //this is dumb, and causes problems with loadbalancers etc.
                                //$this->set_userdata($new_name, $value);
                                //$this->unset_userdata($name);
                        }
                }

                if ( count($newUserData) > 0 ) {
                  $this->set_userdata($newUserData);
                  $this->unset_userdata($userDataToUnset);
                }
        }

[simonl2002]

Note: The above code is regarding CI 2, having briefly looked at the newest CI code in this git repo, I think this issue still exists.

[joelbradbury]

Just ran into this issue in the wild.

The above workaround (bundling all the set calls into a single call) worked as a temporary patch for me.

[julianfuerderer]

Is there any 'global' solution ? (except the method above)

[simonl2002]

@julianfuerderer when you say 'global' what do you mean?

[julianfuerderer]

fix it now in the rep

[simonl2002]

Aah ok, I'll put together a pull request. I was meaning to, but just haven't had time.

[ganiutomo]

Is this issue still open?

@narfbg

[narfbg]

Does it look like it's closed?

[ganiutomo]

Sorry @narfbg, I thought it was closed in #2850

[pilathraj]

Thanks for your response. I'm using codeigniter(2.3.1)/nginx/apache, when
i post a simple login form with user and password, after login validation
with database. I've used the DB session the issue has fixed.

After successful login, we are got error message("502 - Bad Gateway") while
storing the login credentials into session variables.

//query the database
$result = $this->user->login($username, $password); # return single array
result.

if($result)
{
$sess_array = array();
foreach($result as $row)
{
$sess_array = array(
'id' => $row->id,
'username' => $row->username
);
$this->session->set_userdata('logged_in', $sess_array);
$this->session->set_flashdata('msg_success', 'Logined in successfully');
}
redirect('myaccount');
}

else

{
$this->session->set_flashdata('msg_error', 'Invalid username or
password');
redirect('login');
}

If login failed message show's correctly, otherwise server responded as 502
bad gateway error.

On Sat, Aug 3, 2013 at 8:31 AM, Eric Roberts [email protected]:

• Have you tested it using CI 3.0 to see if it's been fixed yet?
• Are you using DB, cookie, or native sessions?
• Can you provide the actual code you're using?

Things like this require a lot more than just "this didn't work".

Reply to this email directly or view it on GitHubhttps://github.com/EllisLab/CodeIgniter/issues/2476#issuecomment-22047339
.

Best Regards,
Pilathraj A
[phone]
[phone]
[email protected]
[email protected]

[AkenRoberts]

Make sure to check your server error logs (Apache or nginx) to see what the actual problem is behind the 502 error.

[AdenFraser]

I have encounted the same issue in the past on a site I manage and resolved it recently by increasing the proxy buffer sizes in my nginx.conf file. For instance:

proxy_buffer_size 128k;
proxy_buffers 4 256k;
proxy_busy_buffers_size 256k;

I believe in an Apache setup mod_proxy variables would need to be increased but don't quote me on that.

Regardless, this isn't a Codeigniter issue but instead a server configuration issue which causes the 502 Gateway error to occur, if you check your Apache or Nginx logs as mentioned above, you'll soon be able to resolve the issue.

[jim-parry]

Superceded by #3073? Confused.

[narfbg]

It will be closed when #3073 is closed.

[narfbg]

Fixed by #3073.

[rc1021]

@AdenFraser thank you.

in Nginx, you must set conf with:
在 Nginx 必須在 conf 宣告以下變數

    location ~ \.php$ {
        ....
        fastcgi_buffer_size 128k;
        fastcgi_buffers 4 256k;
        fastcgi_busy_buffers_size 256k;
        fastcgi_temp_file_write_size 256k;
        fastcgi_intercept_errors on;
    }