Question

I am having difficulty in consuming the reCaptcha Web Service using C#/.Net 3.5. Although I think the problem is with consuming web services in general.

String validate = String.Format("http://api-verify.recaptcha.net/verify?privatekey={0}&remoteip={1}&challenge={2}&response={3}", PrivateKey, UserIP, Challenge, Response);
WebClient serviceRequest = new WebClient();
serviceRequest.Headers.Add("ContentType","application/x-www-form-urlencoded")

String response = serviceRequest.DownloadString(new Uri(validate ));

It keeps telling me that the error is: nverify-params-incorrect. Which means:

The parameters to /verify were incorrect, make sure you are passing all the required parameters.

But it’s correct. I am using the private key, the IP address (locally) is 127.0.0.1, and the challenge and response seem fine. However the error keeps occurring.

I am pretty sure this is a issue with how I am requesting the service as this is the first time I have actually used webservices and .Net.

I also tried this as it ensures the data is posted:

    String queryString = String.Format("privatekey={0}&remoteip={1}&challenge={2}&response={3}",PrivateKey, UserIP, Challenge, Response);
    String Validate = "http://api-verify.recaptcha.net/verify" + queryString;

    HttpWebRequest request = (HttpWebRequest)WebRequest.Create(new Uri(Validate));
    request.Method = "POST";
    request.ContentType = "application/x-www-form-urlencoded";
    request.ContentLength = Validate.Length;


    **HttpWebResponse captchaResponse = (HttpWebResponse)request.GetResponse();**
    String response;
    using (StreamReader reader = new StreamReader(captchaResponse.GetResponseStream()))
        response = reader.ReadToEnd();

Seems to stall at the point where I get response.

Any advice?

Thanks in advance

Answer 1

So got this working, for some reason I needed to write the request to a stream like so:

//Write data to request stream 
        using (Stream requestSteam = request.GetRequestStream())
            requestSteam.Write(byteData, 0, byteData.Length);

Could anyone explain why this works. I didn’t think I would need to do this, don’t completely understand what’s happening behind the scenes..