/// <summary>
/// Validates the captcha.
/// </summary>
/// <param name="collection">The collection.</param>
/// <param name="modelState">State of the model.</param>
/// <param name="captchaKey">The captcha key.</param>
/// <param name="captchaValue">The captcha value.</param>
private static void ValidateCaptcha(FormCollection collection, ModelStateDictionary modelState, String captchaKey, String captchaValue)
{
bool isValid = true;
// get the guid from form collection
String guid = collection[CaptchaImage.CaptchaImageGuidKey];
// check for the guid because it is required from the rest of the opperation
if (String.IsNullOrEmpty(guid))
{
isValid = false;
}
else
{
// get values
CaptchaImage image = CaptchaImage.GetCachedCaptcha(guid);
String expectedValue = image == null ? String.Empty : image.Text;
// removes the captch from cache so it cannot be used again
HttpContext.Current.Cache.Remove(guid);
// validate the captch
if (String.IsNullOrEmpty(captchaValue) || String.IsNullOrEmpty(expectedValue) || !String.Equals(captchaValue, expectedValue, StringComparison.OrdinalIgnoreCase))
{
isValid = false;
}
}
if (!isValid)
{
modelState.AddModelError(captchaKey, @"The code you typed does not match the code the image.");
}
}
/// <summary>
/// Enables processing of HTTP Web requests by a custom HttpHandler that implements the <see cref="T:System.Web.IHttpHandler"/> interface.
/// </summary>
/// <param name="filterContext">An <see cref="T:System.Web.HttpContext"/> object that provides references to the intrinsic server objects (for example, Request, Response, Session, and Server) used to service HTTP requests.</param>
public void ProcessRequest(HttpContext context)
{
// get the unique GUID of the captcha; this must be passed in via the querystring
string guid = context.Request.QueryString["guid"];
CaptchaImage ci = CaptchaImage.GetCachedCaptcha(guid);
if (String.IsNullOrEmpty(guid) || ci == null)
{
context.Response.StatusCode = 404;
context.Response.StatusDescription = "Not Found";
context.Response.End();
return;
}
// write the image to the HTTP output stream as an array of bytes
using (Bitmap b = ci.RenderImage())
{
b.Save(context.Response.OutputStream, ImageFormat.Gif);
}
context.Response.ContentType = "image/gif";
context.Response.StatusCode = 200;
context.Response.StatusDescription = "OK";
context.Response.End();
}
/// <summary>
/// Called when [action executed].
/// </summary>
/// <param name="filterContext">The filter filterContext.</param>
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
// make sure no values are getting sent in from the outside
if (filterContext.ActionParameters.ContainsKey("captchaValid"))
{
filterContext.ActionParameters["captchaValid"] = null;
}
// get the guid from the post back
string guid = filterContext.HttpContext.Request.Form["captcha-guid"];
// check for the guid because it is required from the rest of the opperation
if (String.IsNullOrEmpty(guid))
{
filterContext.RouteData.Values.Add("captchaValid", false);
return;
}
// get values
CaptchaImage image = CaptchaImage.GetCachedCaptcha(guid);
string actualValue = filterContext.HttpContext.Request.Form[Field];
string expectedValue = image == null ? String.Empty : image.Text;
// removes the captch from cache so it cannot be used again
filterContext.HttpContext.Cache.Remove(guid);
// validate the captch
filterContext.ActionParameters["captchaValid"] =
!String.IsNullOrEmpty(actualValue) &&
!String.IsNullOrEmpty(expectedValue) &&
String.Equals(actualValue, expectedValue, StringComparison.OrdinalIgnoreCase);
}
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
base.OnActionExecuting(filterContext);
if (Try())
{
return;
}
var modelState = filterContext.Controller.ViewData.ModelState;
// make sure the captcha valid key is not contained in the route data
//if (filterContext.RouteData.Values.ContainsKey("captchaValid"))
// filterContext.RouteData.Values.Remove("captchaValid");
string guid = filterContext.RequestContext.HttpContext.Request.Form["captcha-guid"];
if (String.IsNullOrEmpty(guid))
{
modelState.AddModelError(Field, ValidationMessage);
//filterContext.RouteData.Values.Add("captchaValid", false);
return;
}
CaptchaImage image = CaptchaImage.GetCachedCaptcha(guid);
string actualValue = filterContext.RequestContext.HttpContext.Request.Form[Field];
string expectedValue = image == null ? String.Empty : image.Text;
filterContext.RequestContext.HttpContext.Cache.Remove(guid);
if (String.IsNullOrEmpty(actualValue) || String.IsNullOrEmpty(expectedValue) ||
!String.Equals(actualValue, expectedValue, StringComparison.OrdinalIgnoreCase))
{
modelState.AddModelError(Field, ValidationMessage);
}
else
{
modelState.Remove(Field);
}
}