void System.Web.IHttpHandler.ProcessRequest(System.Web.HttpContext context)
{
HttpApplication app = context.ApplicationInstance;
//-- get the unique GUID of the captcha; this must be passed in via the querystring
string guid = app.Request.QueryString["guid"];
CaptchaImage ci = null;
if (guid != "")
{
if (string.IsNullOrEmpty(app.Request.QueryString["s"]))
{
ci = (CaptchaImage)HttpRuntime.Cache.Get(guid);
}
else
{
ci = (CaptchaImage)HttpContext.Current.Session[guid];
}
}
if (ci == null)
{
app.Response.StatusCode = 404;
context.ApplicationInstance.CompleteRequest();
return;
}
//-- write the image to the HTTP output stream as an array of bytes
using (Bitmap b = ci.RenderImage())
{
b.Save(app.Context.Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);
}
app.Response.ContentType = "image/jpeg";
app.Response.StatusCode = 200;
context.ApplicationInstance.CompleteRequest();
}
private CaptchaImage GetCachedCaptcha(string guid)
{
CaptchaImage functionReturnValue = null;
if (_cacheStrategy == CacheType.HttpRuntime)
{
return((CaptchaImage)HttpRuntime.Cache.Get(guid));
}
else
{
return((CaptchaImage)HttpContext.Current.Session[guid]);
}
return(functionReturnValue);
}
/// <summary>
/// Validate the user's text against the CAPTCHA text
/// </summary>
public void ValidateCaptcha()
{
string userEntry = tbUserEntry.Text;
if (!Visible | !Enabled)
{
_userValidated = true;
return;
}
//-- retrieve the previous captcha from the cache to inspect its properties
CaptchaImage ci = GetCachedCaptcha(_prevguid);
if (ci == null)
{
SetErrorMessage("The code you typed has expired after " + this.CaptchaMaxTimeout + " seconds.");
_userValidated = false;
return;
}
//-- was it entered too quickly?
if (this.CaptchaMinTimeout > 0)
{
if ((ci.RenderedAt.AddSeconds(this.CaptchaMinTimeout) > System.DateTime.Now))
{
_userValidated = false;
SetErrorMessage("Code was typed too quickly. Wait at least " + this.CaptchaMinTimeout + " seconds.");
RemoveCachedCaptcha(_prevguid);
return;
}
}
if (string.Compare(userEntry, ci.Text, true) != 0)
{
//((System.Web.UI.IValidator) this).ErrorMessage = "The code you typed does not match the code in the image.";
SetErrorMessage("The code you typed does not match the code in the image.");
_userValidated = false;
RemoveCachedCaptcha(_prevguid);
return;
}
_userValidated = true;
RemoveCachedCaptcha(_prevguid);
}
