Unable to log in with CURL... But do not know why - php

Question

Here's my problem. A few months ago, I wrote a PHP script to get connected to my account on a website. I was using CURL to get connected and everything was fine. Then, they updated the website and now I am no longer able to get connected. The problem is not with CURL, as I do not get any error from CURL, but it is the website itself which tells me that I am not able.
Here's my script :
<?php
require('simple_html_dom.php');
//Getting the website main page
$url = "http://www.kijiji.ca/h-ville-de-quebec/1700124";
$main = file_get_html($url);
$links = $main -> find('a');
//Finding the login page
foreach($links as $link){
if($link -> innertext == "Ouvrir une session"){
$page = $link;
}
}
$to_go = "http://www.kijiji.ca/".$page->href;
//Getting the login page
$main = file_get_html($to_go);
$form = $main -> find("form");
//Parsing the page for the login form
foreach($form as $f){
if($f -> id == "login-form"){
$cform = $f;
}
}
$form = str_get_html($cform);
//Getting my post data ready
$postdata = "";
$tot = count($form->find("input"));
$count = 0;
/*I've got here a foreach loop to find all the inputs in the form. As there are hidden input for security, I make my script look for all the input and get the value of each, and then add them in my post data. When the name of the input is emailOrNickname or password, I enter my own info there, then it gets added to the post data*/
foreach($form -> find("input") as $input){
$count++;
$postdata .= $input -> name;
$postdata .= "=";
if($input->name == "emailOrNickname"){
$postdata.= "my email address ";
}else if($input->name == "password"){
$postdata.= "my password";
}else{
$postdata .= $input -> value;
}
if($count<$tot){
$postdata .= "&";
}
}
//Getting my curl session
$ch = curl_init();
curl_setopt_array($ch, array(
CURLOPT_URL => $to_go,
CURLOPT_RETURNTRANSFER => true,
CURLOPT_POST => true,
CURLOPT_POSTFIELDS => $postdata,
CURLOPT_FOLLOWLOCATION => true,
CURLOPT_COOKIESESSION => true,
CURLOPT_COOKIEJAR => 'cookie.txt'
));
$result = curl_exec ($ch);
curl_close ($ch);
echo $result;
?>
CURL nor PHP return any error. In fact, it returns the webpage of the website, but this webpage tells me that there's an error that occurred, as if there was missing some post data.
What do you think can cause that ? Could it be some missing curl_setopts ? I've got no idea, do you have any ?

Answer 1

$form = $main -> find("form") finds first occurrence of element
and that is <form id="SearchForm" action="/b-search.html">
you will need to change that into $form = $main->find('#login-form')

Answer 2

Most likely the problem is that the site (server) checks cookies. This process mainly consists of two phases:
1) When you visit the site first time on some page, e.g. on the login page, the server sets cookies with some data.
2) On each subsequent page visit or POST request the server checks cookies it has set.
So you have to reproduce this process in your script which mean you have to use CURL to get any page from the site, including the login page which should be getting by CURL, not file_get_html.
Furthemore you have to set both CURLOPT_COOKIEJAR and CURLOPT_COOKIEFILE options to the same absolute path value ('cookies.txt' is a relative path) on each request. This is necessary in order to enable cookies auto-handling (session maintaining) within entire series of requests (including redirects) the script will perform.