I'm attempting to store a CodeIgniter captcha helper challenge word in a Session variable, as follows:
$cap = create_captcha($val /* array of params */); // Works fine
$this->session->set_userdata('cap-word', $cap['word']);
If I echo $cap['word'] before and after the session set, it is correct (i.e. what was displayed in the browser). If I retrieve the session variable immediately after setting it, it's also correct.
However what gets stored in the session is completely different - it's the right length (character count) but a totally different string. Hence, when I try to retrieve the userdata on the server side (captcha validation) it gets the wrong value.
(I'm configured for 'sess_use_database' and inspecting the user data values in phpMyAdmin after each page load. Cookie encryption is disabled.)
Debug attempts:
- I've tried prepending / appending known strings to the captcha challenge word before storing it in the session. The known strings make it into the session user data just fine, but are prepended / appended to an incorrect captcha word.
- I've tried replacing the challenge word entirely with a fixed string. This makes the round trip through the session no problem.
- I've tried saving the captcha challenge word to a different string variable (rather than passing it directly from $cap['word]') with the same result; only the challenge portion gets "munged" on landing in the session.
After debugging, my code looks more like:
$cap = create_captcha($vals);
echo("<br>cap = ");
print_r($cap);
echo("<br>cap['word'] = " . $cap['word']);
$theword = $cap['word'];
echo("<br> Before theword = " . $theword);
$this->session->set_userdata('cap-word', $theword . 'abcdefg');
echo("<br> After theword = " . $theword);
echo("<br> Session output = " . $this->session->userdata('cap-word'));
This produces the following output in the browser:
cap = Array ( [word] => 5CZaDeHm [time] => 1436765602.678 [image] => {the image})
cap['word'] = 5CZaDeHm
Before theword = 5CZaDeHm
After theword = 5CZaDeHm
Session output = 5CZaDeHmabcdefg
However, what's stored in the session table userdata fields (and, thus, what pops out when I call $this->session->userdata('cap-word') on submit request) is:
a:2:{s:9:"user_data";s:0:"";s:8:"cap-word";s:15:"3g5hb1I3abcdefg";}
Hence, the substring '5CZaDeHm' within $theword has been seemingly replaced by '3g5hb1I3' during the call to $this->session->set_userdata. I have no idea why, or even how this is possible?!
Update 2015-07-13 07:50 EDT: As usual, Occam's Razor applies. Turns out on each page load, my controller is being called twice, generating 2 captcha images with 2 corresponding challenge words. One of these appeared in the browser, the other in the session's database row. Now to figure out why...
