Decode Form Urlencoded UTF8 in C#

Question

Edit I'd misunderstood what was happening here.. there is a POST send, then receive back a result, then the URL string which I'm seeing here is part of the the query string... so I can't decode what this really is, as it is encoded by the payment gateway people and not me.

I'd like to decode a URL string

Here is the code:

private string SubmitXml(string InputXml)
    {
        string result = InputXml.ToString();

        HttpWebRequest webReq = (HttpWebRequest)WebRequest.Create(_WebServiceUrl);
        webReq.Method = "POST";

        byte[] reqBytes;

        reqBytes = System.Text.Encoding.UTF8.GetBytes(InputXml);
        webReq.ContentType = "application/x-www-form-urlencoded";
        webReq.ContentLength = reqBytes.Length;
        webReq.Timeout = 5000;
        Stream requestStream = webReq.GetRequestStream();
        requestStream.Write(reqBytes, 0, reqBytes.Length);
        requestStream.Close();

        HttpWebResponse webResponse = (HttpWebResponse)webReq.GetResponse();

Here is the InputXml:

 - <GenerateRequest>
  <PxPayUserId>KoruCareCHCH_Dev</PxPayUserId> 
  <PxPayKey>47d99ccdcae54816ecd78c9a80f8878c466a7ed829480e59d421cc4c456cbd93</PxPayKey> 
  <AmountInput>345.00</AmountInput> 
  <BillingId /> 
  <CurrencyInput>NZD</CurrencyInput> 
  <DpsBillingId /> 
  <DpsTxnRef /> 
  <EmailAddress /> 
  <EnableAddBillCard /> 
  <MerchantReference>43</MerchantReference> 
  <TxnData1 /> 
  <TxnData2 /> 
  <TxnData3 /> 
  <TxnType>Purchase</TxnType> 
  <TxnId>43</TxnId> 
  <UrlFail>http://localhost:1527/Auction/PurchaseTickets.aspx</UrlFail> 
  <UrlSuccess>http://localhost:1527/Auction/PurchaseTickets.aspx</UrlSuccess> 
  <Opt /> 
  </GenerateRequest>

Here is the URL

https://sec2.paymentexpress.com/pxpay/pxpay.aspx?userid=KoruCareCHCH_Dev&request=v5lK0D7j3qnGqQVnj3WThhuS5PoWwKhdLUXfnL1hiSzYzxzkKVtTbLKC49e0qerYoTAofoBXfkWHjJdtOEV1MrnEBZ3p9b-G5fTsS-sLqc76RhHOb8HTxtwe0EQ1kz1iCf2ExIgKRod-FPQTKf6XoTLLlQ4jhcrO7yQczrq1Hft5pB98LMJCdBX0FDnA5NV0ZGApR0NaCMy-xbpsVSsyTbSdmp03aiHpGXI4up2RxrBFhbiEOZKtpKkjUpqJ90UuoXmFwqTC5Pj0g1mx3VRV2ee358Tnu1_kuEID_RaP8sZNTVlAMY5-8qjB-u0dgM4ya8Faxxyw5AhyE=

Problem: How do I decode the URL request=blahblah back into XML

I'm doing this to try and prove what is contained in the URL string (it should be just like the XML above!)

Answer 1

Didn't have any luck decoding it so the URL might be wrong, but I used this code:

Uri uri = new Uri(...);
NameValueCollection query = HttpUtility.ParseQueryString(uri.Query);
string value = query["request"].Replace('-', '+').Replace('_', '/');
Debug.WriteLine(Convert.FromBase64String(value));

---

EDIT: In their docs they say it's encrypted.

Answer 2

You can use a regex, something like

var match = new Regex("request=(?<key>[^&]+)").Match(url);

and capture the request value in the named group. From there, hopefully you'd be able to decrypt the captured value.

No guarantees that the above regex is correct - I haven't tested it. It should at least point you in the right direction!