Develop Reference

Cookies become null when page is loaded

I have two asp.net pages. I set cookies using following code in Login Page.
HttpCookie cookie = new HttpCookie("sample");
cookie.Values.Add(cookieValues);
cookie.Expires = DateTime.Now.AddMinutes(60);
HttpContext.Current.Response.Cookies.Add(cookie);
Cookie is set successfully with expired date. I can see it on Watch window of Visual Studio.
However, when I tried to look for the values in another page during page load, both request and response cookies are null.
HttpCookie respCookie = HttpContext.Current.Request.Cookies["sample"];
if (respCookie != null)
{
DateTime expDate = respCookie.Expires;
if (expDate > DateTime.Now)
return respCookie;
else
return null;
}
else
return null;

Try disabling browser extensions or running your page in anonymous mode.
I was using Avast browser extension which messed with my cookies, worked for me.

Cannot find the cookies in asp.net c#

I am creating a web page with .net 2.0 and I want to check if it is the first time visit for the user.
I am using the code block in pageload():
String CookieName = "Cookie";
String CookieValue = "TEST";
if (Request.Cookies[CookieName] != null)
{
Label3.Visible = true;
if (Request.Cookies[CookieName].Value == CookieValue)
{
Label3.Text = "Cookie already exists: " + Request.Cookies[CookieName].Value.ToString();
}
else
Label3.Text = "Cookie var içerisinde: " + Request.Cookies[CookieName].Value.ToString();
}
else
{
Label3.Visible = true;
HttpCookie MyCookie=new HttpCookie(CookieName,CookieValue);
Response.Cookies.Add(MyCookie);
Label3.Text = "Cookie created. " + Request.Cookies[CookieName].Value.ToString();
}
Everything seems to be working, as I run the code "Label3" becomes "Cookie created. Cookie". And after another postback "Label3" becomes "Cookie already exists. Cookie" as it should be.
But I couldn't find my cookies anywhere in my local harddrive.(even if I didn't end the session)
And after ending session and re-run the code, it starts again with "Cookie created. Cookie" which means it couldn't find the previous cookie.
It is obvious that something is missing. I tried to add expry date and path to the cookie. None of them worked for me.
Thank you in advance.
Cagri

But I couldn't find my cookies anywhere in my local harddrive.(even if I didn't end the session)
If you have Chrome, and why don't you :), use it's built-in Dev tools CtrlShiftI and select the Resources tab and boom! not just cookies!:
If you look above, in the Expires column, you'll see one cookie expires at the end of the browser Session, while the other has a set Date.
The cookies you are creating above are Session (dies after browser close).
If you want to them to be persistent and survive a browser close, define Expires property like so:
Response.Cookies.Add(new HttpCookie(CookieName, "hello persistent") { Expires = DateTime.Now.AddDays(1) });
Hth...

Duplicate cookies?

I have an application that leverages a cookie to support a quasi-wizard (i.e. it's a set of pages that are navigated to by each other, and they must occur in a specific order, for registration).
When the Logon.aspx page is loaded - the default page - the browsers cookies look right.
There's one cookie and it has the right value. This ensures that the next page, which is an enrollment agreement, knows that it was loaded from the Logon.aspx page. However, when I get to that page the browsers cookies look much different:
Now we have two of the same cookie.
This doesn't appear to be causing any real issues - but I can't be sure it won't. So, let me show you the code I'm using to set the cookie (because maybe there's something wrong with it):
if (!this.IsPostBack)
{
Utility.HandleReferrer(Request, Response, "Logon.aspx");
Response.Cookies["lastpage"].Value = "Enroll.aspx";
}
and the HandleReferrer method looks like this:
static public void HandleReferrer(HttpRequest request, HttpResponse response, string expectedReferrer)
{
var cookie = request.Cookies["lastpage"];
if (cookie != null && cookie.Value.ToLower().Contains(expectedReferrer.ToLower()))
{
return;
}
response.Redirect("Logon.aspx");
}
So, why in the world does it duplicate this cookie? It doesn't ever seem to create more than two.

I suggest you do one of the following.
First, get the latest glimpse and try again.
If it is still showing 2 cookies with that name then get firebug and/or fiddler and look at it that way. If I had to take a guess I'd say there's either something wrong in glimpse or something wrong in how you are interpreting the results. Perhaps glimpse is showing what cookies existed before and then after the request was processed?
A third option is to simply emit the cookies collection from your own .net code. Something like:
foreach(HttpCookie cookie in request.Cookies) {
Response.Write(String.Format("{0} = {1}", cookie.Name, cookie.Value));
}
and see what happens.

I tried another approach, by creating a method that will return the latest cookie occurrence, this way I'll always get the right data.
This method expect the collection of cookies from Request, and the name of the searched cookie, and returns the latest ticket (the information that is normally encrypted)
private static FormsAuthenticationTicket GetLatestCookie(HttpCookieCollection cookies, string cookieName) {
var cookieOccurrences = new List<FormsAuthenticationTicket>();
for (int index = 0; index < cookies.Count; index++) {
if (cookies.GetKey(index) == cookieName) {
FormsAuthenticationTicket ticket = FormsAuthentication.Decrypt(cookies[index].Value);
cookieOccurrences.Add(ticket);
}
}
DateTime oldestTime = DateTime.MinValue;
FormsAuthenticationTicket oldestTicket = null;
foreach (var formsAuthenticationTicket in cookieOccurrences) {
if (formsAuthenticationTicket.Expiration > oldestTime) {
oldestTime = formsAuthenticationTicket.Expiration;
oldestTicket = formsAuthenticationTicket;
}
}
return oldestTicket;
}

Referral Url's on Facebook Page tab

I have a Facebook Page Tab app and I'm trying to find out where visitors to the page tab are coming from. I've read on http://developers.facebook.com/docs/authentication/signed_request/ that you can get these from app_data in the signed request but whenever I try getting the signed request app_data isn't there.
I used FB.getLoginStatus to get the signed request when inside the tab on Facebook, but
When I debug the signed request with http://developers.facebook.com/tools/echo I get the error "Bad Signature"
Your signed_request was probably not signed with our app_id of xxxxx Here is the payload:
{
"algorithm": "HMAC-SHA256",
"code": "xxxx",
"issued_at": xxxx,
"user_id": "xxxx2"
}
I'm using the C# SDK with Javascript

You can decode the signed request with the code in this topic:
Decode Signed Request Without Authentication
if (Request.Params["signed_request"] != null)
{
string payload = Request.Params["signed_request"].Split('.')[1];
var encoding = new UTF8Encoding();
var decodedJson = payload.Replace("=", string.Empty).Replace('-', '+').Replace('_', '/');
var base64JsonArray = Convert.FromBase64String(decodedJson.PadRight(decodedJson.Length + (4 - decodedJson.Length % 4) % 4, '='));
var json = encoding.GetString(base64JsonArray);
var o = JObject.Parse(json);
var lPid = Convert.ToString(o.SelectToken("page.id")).Replace("\"", "");
var lLiked = Convert.ToString(o.SelectToken("page.liked")).Replace("\"", "");
var lUserId= Convert.ToString(o.SelectToken("user_id")).Replace("\"", "");
}
It should be easy to get the app_data by adding
var lAppData = Convert.ToString(o.SelectToken("app_data")).Replace("\"", "");
To the have the app_data for your tab app you need to add it to the redirect url when acquiring permissions. You redirect url should something like:
http://facebook.com/YOUR_PAGE?sk=app_YOUR_APP_ID&app_data=add,whatever,parameters,you,want,here
I can only guess that the reason you got this error is because you just pasted your signed request in the address bar instead of the one used by the echo tool. The error is because your signed request is signed by your app_id and you're trying to use it with echo which has another app_id. But that's just a guess :)
My primary language is PHP but hope I was able to help :)

When to use Request.Cookies over Response.Cookies?

Do I use response when at a page event (e.g. load) as this is a response from ASP.NET, and request when pressing a button as this is a response going to ASP.NET for processing? Or is there more to it?

They are 2 different things, one SAVES [Response], the other READS [Request]
in a Cookie (informatics speaking) :)
you save a small file for a period of time that contains an object of the type string
in the .NET framework you save a cookie doing:
HttpCookie myCookie = new HttpCookie("MyTestCookie");
DateTime now = DateTime.Now;
// Set the cookie value.
myCookie.Value = now.ToString();
// Set the cookie expiration date.
myCookie.Expires = now.AddMinutes(1);
// Add the cookie.
Response.Cookies.Add(myCookie);
Response.Write("<p> The cookie has been written.");
You wrote a cookie that will be available for one minute... normally we do now.AddMonth(1) so you can save a cookie for one entire month.
To retrieve a cookie, you use the Request (you are Requesting), like:
HttpCookie myCookie = Request.Cookies["MyTestCookie"];
// Read the cookie information and display it.
if (myCookie != null)
Response.Write("<p>"+ myCookie.Name + "<p>"+ myCookie.Value);
else
Response.Write("not found");
Remember:
To Delete a Cookie, there is no direct code, the trick is to Save the same Cookie Name with an Expiration date that already passed, for example, now.AddMinutes(-1)
this will delete the cookie.
As you can see, every time that the time of life of the cookie expires, that file is deleted from the system automatically.

In a web application the request is what comes from the browser and the response is what the server sends back. When validating cookies or cookie data from the browser you should use the Request.Cookies. When you are constructing cookies to be sent to the browser you need to add them to Response.Cookies.

When writing a cookie, use Response but reading may depend on your situation. Normally, you read from Request but if your application is attempting to get a cookie that has just been written or updated and the round trip to the browser has not occured, you may need to read it form Response.
I have been using this pattern for a while and it works well for me.
public void WriteCookie(string name, string value)
{
var cookie = new HttpCookie(name, value);
HttpContext.Current.Response.Cookies.Set(cookie);
}
public string ReadCookie(string name)
{
if (HttpContext.Current.Response.Cookies.AllKeys.Contains(name))
{
var cookie = HttpContext.Current.Response.Cookies[name];
return cookie.Value;
}
if (HttpContext.Current.Request.Cookies.AllKeys.Contains(name))
{
var cookie = HttpContext.Current.Request.Cookies[name];
return cookie.Value;
}
return null;
}

The cookies comes from the browser in the Request.Cookies collection. That is where you read the cookies that was sent.
To send cookies back to the browser you put them in the Response.Cookies collection.
If you want to delete a cookie, you have to tell the browser to remove it by sending the cookie with an expiration date that has passed. The browser is using the local time of the client computer so if you are using the server time to create a date, be sure to subtract at least one day to be sure that it has actually passed in the clients local time.

When i create or update a cookie in .NET i normally do it to both the request and response cookie collection. That way you can be sure if you try to read the cookie further down the page request sequence it will have the correct information.

Andrew's Code gave an error in "AllKeys.Contains" Method. So I corrected a little..
public void WriteCookie(string strCookieName, string strCookieValue)
{
var hcCookie = new HttpCookie(strCookieName, strCookieValue);
HttpContext.Current.Response.Cookies.Set(hcCookie);
}
public string ReadCookie(string strCookieName)
{
foreach (string strCookie in HttpContext.Current.Response.Cookies.AllKeys)
{
if (strCookie == strCookieName)
{
return HttpContext.Current.Response.Cookies[strCookie].Value;
}
}
foreach (string strCookie in HttpContext.Current.Request.Cookies.AllKeys)
{
if (strCookie == strCookieName)
{
return HttpContext.Current.Request.Cookies[strCookie].Value;
}
}
return null;
}