cURL and ASP.NET : issue with post parameters - php

Question

We have one search engine which was programed in asp.net.
I manage to curl individual results as they have a more or less direct link that I can predict and curl.
But I don't manage to curl the result list, here is how it works :
On the search page we have to select the database we want to search via a checkbox menu.
Once I check the db I want to search, I click on "Search" button which forwards me to the search page taking the db chosen in consideration.
If I try to go to the search page with a direct link, it doesn't work as it does not know in which db the search will be.
I tried to look at the post parameters with Firebug and I got the following :
Checkbox_db1 on
__EVENTARGUMENT
__EVENTTARGET LinkButtonCategory
__VIEWSTATE zeyhbf5vg41g6a4f1ezragf136er46ga4gfv658a4r6g4 (something looking like that but longer)
Here is what I try in curl :
$ch = curl_init();
$fields = array ('Checkbox_db1' => 'on', '__EVENTARGUMENT' => '',
'__EVENTTARGET' => 'LinkButtonCategory', '__VIEWSTATE' => '');
$postvars = '';
foreach($fields as $key=>$value)
{
$postvars .= $key.'='.$value.'&';
}
rtrim ($postvars, '&');
curl_setopt ($ch, CURLOPT_URL, "monsite.com/choosedb.aspx");
curl_setopt ($ch, CURLOPT_POST, count($fields));
curl_setopt ($ch, CURLOPT_POSTFIELDS, $postvars);
curl_setopt ($ch, CURLOPT_RETURNTRANSFER, true);
$output1 = curl_exec($ch);
$fields2 = array ('TxtBox1' => 'value1', 'Txtbox2' => 'value2', '__EVENTARGUMENT' => '',
'__EVENTTARGET' => '', '__VIEWSTATE' => '');
$postvars = '';
foreach($fields2 as $key=>$value)
{
$postvars .= $key.'='.$value.'&';
}
rtrim ($postvars, '&');
curl_setopt ($ch, CURLOPT_URL, "monsite.com/search.aspx");
curl_setopt ($ch, CURLOPT_POST, count($fields2));
curl_setopt ($ch, CURLOPT_POSTFIELDS, $postvars);
curl_setopt ($ch, CURLOPT_RETURNTRANSFER, true);
$output2 = curl_exec($ch);
But of course this doesn't work.... and the issue is that I am not familiar at all with ASP.NET :/
Anyone could help ? Thanks in advance

Answer 1

So first you get the initial page with a regular curl get.
Then you have to extract the VIEWSTATE parameter :
$regexViewstate = '/__VIEWSTATE\" value=\"(.*)\"/i';
function regexExtract($text, $regex, $regs, $nthValue)
{
if (preg_match($regex, $text, $regs)) {
$result = $regs[$nthValue];
}
else {
$result = "";
}
return $result;
}
$viewstate = regexExtract($data,$regexViewstate,$regs,1);
And you make up your new post :
$postData = '__EVENTARGUMENT=&__EVENTTARGET=LinkButtonCategory&__VIEWSTATE=';
$postData .= rawurlencode($viewstate).'&TxtBox1=value1&TxtBox2=value2';
curl_setOpt($ch, CURLOPT_POST, TRUE);
curl_setopt($ch, CURLOPT_POSTFIELDS, $postData);
curl_setopt($ch, CURLOPT_URL, $urlLogin);
curl_setopt($ch, CURLOPT_COOKIEJAR, $cookieFile);
$output = curl_exec($ch);