cURL - Navigating multiple forms but can't get passed one page - php

Question

For a personal project, I'm trying to automate the download of a file from a website that I do not have control/access to. To download the file, user input is required on a total of 6 pages, each with a form submission with the download on the final page.
URL: https://www2.iris.gov.hk/eservices/searchlandregister/search.jsp
I've managed to use cURL to navigate through the first 3 pages. When my cURL code gets the 4th page, it gives me the following error:
"Cannot place order from multiple browser windows, please retry."
This error is generated by the server (not cURL) so I have no idea what it means or how to work around this problem. But if you manually submit the forms on each page, you can progress to the 4th page without error.
Here's the working code. You'll notice the first 3 pages work as expected. However, if you uncomment out the code for the forth page, you'll see that it generates the error message.
I'm stumped! Any help or suggestions would be greatly appreciated.
Thanks!
/**
* Page 1
*
* Sample input data:
*
* Floor: 62
* Flat No: D
* House No: 1
* Street Name: Austin Road West
* Area Code: Kowloon
*
*
*/
$cookie="cookie.txt";
$url = "https://www1.iris.gov.hk/eservices/searchlandregister/search.jsp";
$url2 = "https://www2.iris.gov.hk/eservices/searchLandRegister.do";
$url3 = "https://www2.iris.gov.hk/eservices/searchLandRegister.do";
$url4 = "https://www2.iris.gov.hk/eservices/searchByAddressResult2.do";
$params = array(
'previousOp' => urlencode(''),
'functionId' => urlencode('continue'),
'forward2Caller' => urlencode('searchlandregister'),
'SStreetName' => urlencode('eng'),
'SDevelopmentName' => urlencode('eng'),
'SBlock' => urlencode('*'),
'SFloor' => urlencode('62'),
'SFlat' => urlencode('D'),
'searchBySection' => urlencode('StreetName'),
'SSelectedArea' => urlencode('20'),
'SDevelopmentNameEng' => urlencode(''),
'SDevelopmentNameChn' => urlencode(''),
'SStreetNameEng' => urlencode('AUSTIN ROAD WEST'),
'SStreetNameChn' => urlencode(''),
'hasSpec' => urlencode('0'),
'hasLotSpec' => urlencode('0'),
'specPrn' => urlencode(''),
'haveSDR' => urlencode('Y'),
'initFromRVD' => urlencode('N'),
'SHouseNo1' => urlencode('1'),
'SHouseNo2' => urlencode(''),
'SPrn' => urlencode(''),
'SExtension' => urlencode('false'),
'SLotType' => urlencode(''),
'SLotNo' => urlencode(''),
'SSection1' => urlencode(''),
'SSub1' => urlencode(''),
'SSection2' => urlencode(''),
'SSub2' => urlencode(''),
'SSection3' => urlencode(''),
'SSub3' => urlencode(''),
'SSection4' => urlencode(''),
'SMisc' => urlencode(''),
'recordIndex' => urlencode(''),
'SSBlock' => urlencode('*'),
'SSFloor' => urlencode('62'),
'SSFlat' => urlencode('D'),
'SDBlock' => urlencode('*'),
'SDFloor' => urlencode('*'),
'SDFlat' => urlencode('*'),
'SLBlock' => urlencode('*'),
'SLFloor' => urlencode('*'),
'SLFlat' => urlencode('*'),
'SRegisterName' => urlencode('SDR'),
'SSRegisterName' => urlencode('SDR'),
'SLRegisterName' => urlencode('SDR'),
'SDRegisterName' => urlencode('SDR'),
'xSSBlock' => urlencode('*'),
'xSSFloor' => urlencode('62'),
'xSSFlat' => urlencode('D'),
'xHouseNo1' => urlencode('1'),
'xHouseNo2' => urlencode(''),
'SStreetNameInput' => urlencode('AUSTIN ROAD WEST'),
'xSelectedArea' => urlencode('20'),
'xSSRegisterName' => urlencode('SDR'),
'xSDBlock' => urlencode('*'),
'xSDFloor' => urlencode('*'),
'xSDFlat' => urlencode('*'),
'SDevelopmentNameInput' => urlencode(''),
'xSDRegisterName' => urlencode('SDR'),
'xSLBlock' => urlencode('*'),
'xSLFloor' => urlencode('*'),
'xSLFlat' => urlencode('*'),
'SLotTypeInput' => urlencode(''),
'xLotNo' => urlencode(''),
'xSection1' => urlencode(''),
'xSub1' => urlencode(''),
'xSection2' => urlencode(''),
'xSub2' => urlencode(''),
'xSection3' => urlencode(''),
'xSub3' => urlencode(''),
'xSection4' => urlencode(''),
'xMisc' => urlencode(''),
'xSLRegisterName' => urlencode('SDR'),
'xPrn' => urlencode(''),
// Page 2
'dispLotPRN' => urlencode('C5458863'),
'dispBlock' => urlencode('SO1'),
'BBlock' => urlencode('SO1'),
'hasBlock' => urlencode('1'),
// Page 3
'somePrn[0]' => urlencode('B6479113'),
'someSelected[0]' => urlencode('on'),
'someEnquiry[0]' => urlencode('C'),
'someNature[0]' => urlencode('P'),
'someCopies[0]' => urlencode('1'),
// Page 4
'dispHouseNo' => urlencode('1'),
'dispStreetName' => urlencode('AUSTIN ROAD WEST'),
'hasLot' => urlencode('0'),
'hasFloor' => urlencode('0'),
'street' => urlencode('true'),
'dev' => urlencode('false'),
'lot' => urlencode('false')
);
//url-ify the data for the POST
foreach($params as $key=>$value) {
$string .= $key.'='.$value.'&';
} // end foreach
rtrim($string, '&');
$ch = curl_init();
curl_setopt ($ch, CURLOPT_URL, $url);
curl_setopt ($ch, CURLOPT_SSL_VERIFYPEER, FALSE);
curl_setopt ($ch, CURLOPT_USERAGENT, "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/48.0.2564.109 Safari/537.36");
curl_setopt ($ch, CURLOPT_TIMEOUT, 60);
curl_setopt ($ch, CURLOPT_FOLLOWLOCATION, 1);
curl_setopt ($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt ($ch, CURLOPT_COOKIEJAR, $cookie);
curl_setopt ($ch, CURLOPT_COOKIEFILE, $cookie);
curl_setopt ($ch, CURLOPT_POST, false);
$result = curl_exec ($ch);
//echo $result;
// Submit to Page 2
curl_setopt ($ch, CURLOPT_URL, $url2 . '?' . $string);
curl_setopt ($ch, CURLOPT_SSL_VERIFYPEER, FALSE);
curl_setopt ($ch, CURLOPT_USERAGENT, "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/48.0.2564.109 Safari/537.36");
curl_setopt ($ch, CURLOPT_TIMEOUT, 60);
curl_setopt ($ch, CURLOPT_FOLLOWLOCATION, 1);
curl_setopt ($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt ($ch, CURLOPT_COOKIEJAR, $cookie);
curl_setopt ($ch, CURLOPT_COOKIEFILE, $cookie);
curl_setopt ($ch, CURLOPT_POST, false);
curl_setopt ($ch, CURLOPT_POSTFIELDS, $params);
$result = curl_exec ($ch);
//echo $result;
// Submit to Page 3
$params['previousOp'] = 'BLOCK LIST';
curl_setopt ($ch, CURLOPT_URL, $url3 . '?' . $string);
curl_setopt ($ch, CURLOPT_SSL_VERIFYPEER, FALSE);
curl_setopt ($ch, CURLOPT_USERAGENT, "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/48.0.2564.109 Safari/537.36");
curl_setopt ($ch, CURLOPT_TIMEOUT, 60);
curl_setopt ($ch, CURLOPT_FOLLOWLOCATION, 1);
curl_setopt ($ch, CURLOPT_RETURNTRANSFER, 1);
//curl_setopt ($ch, CURLOPT_COOKIEJAR, $cookie);
curl_setopt ($ch, CURLOPT_COOKIEFILE, $cookie);
curl_setopt ($ch, CURLOPT_POST, false);
curl_setopt ($ch, CURLOPT_POSTFIELDS, $params);
$result = curl_exec ($ch);
//echo $result;
// Submit to Page 4
/*
$params['previousOp'] = 'EXACT MATCH';
$params['functionId'] = 'doAddAndGoToOrder';
$params['queryResultHash'] = '978962765';
curl_setopt ($ch, CURLOPT_URL, $url4 . '?' . $string);
curl_setopt ($ch, CURLOPT_SSL_VERIFYPEER, FALSE);
curl_setopt ($ch, CURLOPT_USERAGENT, "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/48.0.2564.109 Safari/537.36");
curl_setopt ($ch, CURLOPT_TIMEOUT, 60);
curl_setopt ($ch, CURLOPT_FOLLOWLOCATION, 1);
curl_setopt ($ch, CURLOPT_RETURNTRANSFER, 1);
//curl_setopt ($ch, CURLOPT_COOKIEJAR, $cookie);
curl_setopt ($ch, CURLOPT_COOKIEFILE, $cookie);
curl_setopt ($ch, CURLOPT_POST, 1);
curl_setopt ($ch, CURLOPT_POSTFIELDS, $params);
$result = curl_exec ($ch);
*/
curl_close($ch);
echo $result;