cURL post data to asp.net page - php

Question

I am trying to call the __doPostback javascript function in a asp.net page from php using curl.
I learnt that this can be done by making a post request to the asp.net page with the appropriate parameters.
So in curl,
I make a get request / just use file_get_contents to retrieve the initial page.
From this, I extract the values for __VIEWSTATE and __EVENTVALIDATION.
So far everything seems ok.
Now, I understand that we need to make a post request using cURL with __VIEWSTATE and other parameters required. ( values for the fields present in the asp.net form )
I am unable to construct the CURLOPT_POSTFIELDS correctly.
For instance, I am trying this out,
$postoptions1='__EVENTTARGET='.('ctl00$ContentPlaceHolder1$gRef').'&__EVENTARGUMENT='.('$2');
$postoptions2 = '&__VIEWSTATE='.urlencode($viewState) ;
$otherparams = '&ctl00$ContentPlaceHolder1$ddlName=Abc';
And before using setopt for CURLOPT_POSTFIELDS, I am doing,
urlencode ($postoptions1.$postoptions2.$otherparams)
This does not work. The submit results are not shown, which means, the required parameter __VIEWSTATE was not found in my post request.
If I change the order of the parameters and place __VIEWSTATE as the first parameter, the results page is shown but the other parameter values are not honoured.
I think there is some problem with the way I am encoding the parameters.
Please tell me how to construct the parameters for the post request to a asp.net page.
Thanks.
--Edited--
Here is the complete code:
$resultsPerPage='10';
$url = "www.example.com"; // url changed
$curl_connection = curl_init($url);
function sendCurl($curl_connection,$url,$params,$isPost=false) {
//$post_string = $params;
$post_string = http_build_query($params);
//$post_string = build_query_string($params);
//$post_string = urlencode($params);
echo 'After Encode'.$post_string;
$cookie="/cookie.txt";
//set options
curl_setopt($curl_connection, CURLOPT_CONNECTTIMEOUT, 300);
curl_setopt($curl_connection, CURLOPT_USERAGENT,
"Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1)");
curl_setopt($curl_connection, CURLOPT_RETURNTRANSFER, true);
curl_setopt($curl_connection, CURLOPT_HEADER, 0); // don't return headers
curl_setopt($curl_connection, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($curl_connection, CURLOPT_FOLLOWLOCATION, 1);
curl_setopt($curl_connection,CURLOPT_REFERER, $url);
if($isPost) {
curl_setopt ($curl_connection, CURLOPT_POST, true);
//set data to be posted
curl_setopt($curl_connection, CURLOPT_POSTFIELDS, $post_string);
curl_setopt($curl_connection,CURLOPT_COOKIEJAR,$cookie);
}
else {
curl_setopt($curl_connection,CURLOPT_COOKIEFILE,$cookie);
}
$response1 = curl_exec($curl_connection);
if($response1 === false)
{
echo 'Curl error: ' . curl_error($curl_connection);
}
else
{
echo 'Operation completed without any errors';
}
return $response1;
} **// First time, get request to asp.net page
$response1 = sendCurl($curl_connection,$url,'',false);
$viewState=getVStateContent($response1);
$eventValidation =getEventValidationContent($response1);
$simpleParams = '&__VIEWSTATE='.$viewState.'&ctl00$ContentPlaceHolder1$ddlManuf=&ctl00$ContentPlaceHolder1$ddlCrossType=&ctl00$ContentPlaceHolder1$ddlPageSize='.$resultsPerPage.'&ctl00$ContentPlaceHolder1$btnSearch=Search&ctl00_ToolkitScriptManager1_HiddenField=&__EVENTTARGET=&__EVENTARGUMENT=';
// Second post - for submitting the search form
$response2= sendCurl($curl_connection,$url,$simpleParams,true);
----**

Answer 1

What you want is http_build_query, which will format an array as proper HTTP parameters.
Edit: To clarify what this should probably look like:
$params = array(
'__EVENTTARGET' => 'ctl00$ContentPlaceHolder1$gRef',
'__EVENTARGUMENT' => '$2',
'__VIEWSTATE' => $viewState,
'ctl00$ContentPlaceHolder1$ddlName' => 'Abc'
);
curl_setopt($curlHandler, CURLOPT_POSTFIELDS, http_build_query($params));
Also, what's ctl00$ContentPlaceHolder1$ddlName supposed to be?

Answer 2

Don't urlencode() the ampersands (&) linking the parameters together, just the keys & values (the stuff on either side of the ampersands).