How to get response from IPN cryptocurrencies

Question

We're trying to receive payment with cryptocurrencies using coinpayment IPN. We are able to create a request and able to do a payment. However, not able to get success or failure response while user come back to the seller side.

Here is how payment request created:

public ActionResult IPN()
{                        

    var uri = new UriBuilder("https://www.coinpayments.net/index.php");
    uri.SetQueryParam("cmd", "_pay_auto"); 
    uri.SetQueryParam("merchant", "merchant_key");
    uri.SetQueryParam("allow_extra", "0");
    uri.SetQueryParam("currency", "USD"); 
    uri.SetQueryParam("reset", "1");
    uri.SetQueryParam("success_url", "http://localhost:49725/home/SuccessResponse"); //todo: redirect to confirm success page
    uri.SetQueryParam("key", "wc_order_5b7b84b91a882");
    uri.SetQueryParam("cancel_url", "http://localhost:49725/home/FailiureResponse");
    uri.SetQueryParam("order_id", "36");
    uri.SetQueryParam("invoice", "PREFIX-36");
    uri.SetQueryParam("ipn_url", "http://localhost:49725/?wc-api=WC_Gateway_Coinpayments");
    uri.SetQueryParam("first_name", "John");
    uri.SetQueryParam("last_name", "Smith");
    uri.SetQueryParam("email", "[email protected]");
    uri.SetQueryParam("want_shipping", "1");
    uri.SetQueryParam("address1", "228 Park Ave S&address2");
    uri.SetQueryParam("city", "New York");
    uri.SetQueryParam("state", "NY");
    uri.SetQueryParam("zip", "10003-1502");
    uri.SetQueryParam("country", "US");
    uri.SetQueryParam("item_name", "Order 33");
    uri.SetQueryParam("quantity", "1");
    uri.SetQueryParam("amountf", "100.00000000");
    uri.SetQueryParam("shippingf", "0.00000000");            

    return Redirect(uri.ToString());
} 

This will be redirected to the coinpayment site, once payment done, it is showing the following screen.

And trying to get data when user click on back to seller's site, I have tried to get data using Request.Form, but not getting any value in form.

The same thing, working with this woocommerce code, but I have no idea of PHP and how they are dealing with it.

Any thought to get IPN response?

Note: there is no development documentation or sample code available for IPN in .NET

Edit I'm trying to get value from IPN success

Public ActionResult SuccessResponse()
{
    var ipn_version = Request.Form["ipn_version"];
    var ipn_id = Request.Form["ipn_id"];
    var ipn_mode = Request.Form["ipn_mode"];
    var merchant = Request.Form["merchant"];
    var txn_id = Request.Form["txn_id"];
    var status = Request.Form["status"];

    return Content(status);
}

Answer 1

As updated answer stated by @Gillsoft AB, you should need to use valid IPN URL from the code end. Also webhook would not work with localhost. thus, you should listen the request with live server.

Simplest way to check webhook response is to use online tool such as Webhook Tester, it will provide an URL which you have to set as your IPN URL, whenever server will sends the data, you can simply see it to the web. To check that, create one URL and set as your IPN URL as below:

 uri.SetQueryParam("ipn_url", "https://webhook.site/#/457f5c55-c9ce-4db4-8f57-20194c17d0ae");

After that run the payment cycle from local machine, payment server will sends notification to that IPN URL.

Make sure you understood it right! success_url and cancel_url are for user redirection, you will not get any response code over there, inspection of seller's store URL give your exact same URL that you have been passing though, so it is recommended to use unique URLs for each order(i.e add order id at last to the URL) which will give you an idea which order payment has been done or canceled.

http://localhost:49725/home/SuccessResponse?orderid=123

In order to test your local code, add following changes and deployed it to server.

1) Add one new method which will listen IPN response

[ValidateInput(false)]
public ActionResult IPNHandler()
{
    byte[] param = Request.BinaryRead(Request.ContentLength);
    string strRequest = Encoding.ASCII.GetString(param);

    //TODO: print string request 

    //nothing should be rendered to visitor
    return Content(""); 
} 

2) Pass IPN URL while creating a request:

public ActionResult IPN()
{                        
    var uri = new UriBuilder("https://www.coinpayments.net/index.php");
    ...
    ..
    uri.SetQueryParam("success_url", "http://localhost:49725/home/SuccessResponse"); 
    uri.SetQueryParam("cancel_url", "http://localhost:49725/home/FailiureResponse");    
    uri.SetQueryParam("ipn_url", "http://localhost:49725/home/IPNHandler");
    ....
    ..
    return Redirect(uri.ToString());
}

You will get all status code responses in IPNHandler method.

Hope this helps!