Server.Transfer causing Session exception - c#

In my global I have the following code to handle when an error occurs
//[..] code goes here
Server.Transfer("~/Error.aspx?ErrorID=" + errorId);
It used to be a Response.Redirect which worked perfectly except that it changed the url (which is why I want to use Server.Transfer)
Unfortunately, now when it tries to load the Error page, it crashes on the Masterpage when it tries to refer to the Session
HttpException:
Session state can only be used when enableSessionState is set to true,
either in a configuration file or in the Page directive. Please also
make sure that System.Web.SessionStateModule or a custom session state
module is included in the \\
section in the application configuration.
I do have enableSessionState in both my config and my page.
I also found some links which suggest using Context.RewritePath - that just causes a blank page to load for me.
Using Response.Redirect works perfectly and as expected, so I assume Server.Transfer is the issue here. What is it?
EDIT Code:
protected void Application_Error(object sender, EventArgs e)
{
lock (_lockMe)
{
Exception ex = Server.GetLastError();
if (ex != null)
{
if (ex.InnerException != null)
ex = ex.InnerException;
ErrorLoggingManager.AddError(ex, new MembershipData(), ...); //etc
}
Server.ClearError();
//Some other database code for cleaning up some stuff when an error happens
}
try
{
if (Response != null)
{
//Get the last error logged
MyDataContext db = new MyDataContext();
int errorId = db.LoggedErrors.OrderByDescending(le => le.ErrorId).Select(le => le.ErrorId).FirstOrDefault();
Server.Transfer("~/Error.aspx?ErrorID=" + errorId);
}
}
catch (Exception)
{
}
}

As you have not posted much code. So without seeing the actual implementation you have done. I could suggest you below points.
Point 1. First of all, you need to check if SessionState is enabled for pages. You could set them globally in web.config file. Try the snippet given below in web.config
<configuration>
<system.web>
<pages enableSessionState="true" />
</system.web>
</configuration>
Point 2. And put your Redirection in Application_Error in Global.asax.
public void Application_Error(object sender, EventArgs e)
{
HttpApplication app = (HttpApplication)sender;
app.Server.Transfer("~/Error.aspx?ErrorID=" + errorId,true);
}
Point 3. Also check if your SessionStateis set properly in IIS too.
Details are on MSDN to enable sessionstate
Hope this helps..!!!

From what I understand, Server.Transfer sends the content of another page to the client rather than the requested content. If that is the case, then I am wondering if it does not have something to do with applying a master page to the error page? I had a similar error years ago with earlier technology and it turned out that the master page did not like what I was trying to do.
I hope this helps at least point to a solution.

Here's what the problem is:
If there is a page render exception (ex. "File Not Found") then Server.Transfer screws up the session. This has something to do with it being called during the page render.
As long as you are not appending headers before the error occurs, Response.Redirect will work just fine; if you are, however, using Response.AppendHeader then Response.Redirect will not work during a page render.
Try using HttpContext.Current.RewritePath instead. That should fix all these problems. For whatever reason, RewritePath() does not care that the page hasn't finished rendering.

why not just use customErrors in web.config to do the redirect?
<customErrors mode="Off" defaultRedirect="~/Common/Error.aspx">
<error statusCode="403" redirect="~/SM_AccessDenied.aspx" />
<error statusCode="404" redirect="~/Common/FileNotFound.aspx" />
</customErrors>

I had the same problem in a different context a while ago. I don't know if it is your case, but if you're using IIS7 on Windows 2008, in addition to setting enableSessionState=true in your web.config, you have to put your modules inside the <system.webServer> section, instead of <system.web>. Changing this little thing solved it for me.

Why don't you try like this:
The Server.Transfer method also has a second parameter—"preserveForm". If you set this to True, using a statement such as Server.Transfer("WebForm2.aspx", True), the existing query string and any form variables will still be available to the page you are transferring to.
So I think doing like this your session will not expire.
Server.Transfer("~/Error.aspx?ErrorID=" + errorId,True);

The error you are encountering is because you are using a query string parameter. Per the msdn docs
However, the path parameter must not contain a query string, or ASP returns an error.
http://msdn.microsoft.com/en-us/library/ms525800%28v=vs.90%29.aspx
Its about 3/4 of the way down the page just above Requirements.
Even though the docs here are mentioning asp. and not asp.net, keep in mind the session state is a feature of IIS and is handled before asp.net is ever called.

#user2110845 : I had faced similar problem few months ago. the problem was with having an underscore in the website name. We were deploying a website in IIS with two different host names(adding two entries through the 'Edit Bindings' option on the website). The host names provided were abc_ts, abc_is. When the underscore was removed then the session problem got resolved.
It seems there are certain characters not allowed in a website host name. Check if that is your problem.
I found the answer here : link (check 'update 2' in the article)

You don't mention what version of ASP.NET you are using, but there were some changes between 2.0 and 3.5 in how unhandled exceptions bubbled their way up through an ASP.NET web app and then IIS.
Among some other possibles, while you are clearing the error you are not setting Context.Response.TrySkipIisCustomErrors = true; While this particular flag could have nothing to do with your issue (and is only available for 3.5+), it also could help deal with what is potentially two error pages behind the scenes that are obscuring the real issue. Regardless, it'll save you a lot of grief (at least if you are running 3.5+) with other potential issues. Check out two posts I wrote several years back that may be helpful: while they don't cover session handling, they do cover the multiple song-and-dance routines I had to follow to get proper 500 and 404 handling in various versions of ASP.NET. It's possible you will run into something that will get you further ahead, if not all the way there.
http://www.andornot.com/blog/post/Errors-Sending-the-Right-Message-(Redux-Covering-ASPNET-3540).aspx
http://www.andornot.com/blog/post/Errors-Sending-the-Right-Message.aspx

Related

Directing to custom error page on 404 triggered by a URL with '.' at the end [duplicate]

I'm using ASP .NET MVC Beta and I get the HTTP 404 (The resource cannot be found) error when I use this url which has a "dot" at the end:
http://localhost:81/Title/Edit/Code1.
If I remove the dot at the end or the dot is somewhere in the middle I don't get the error.
I tried to debug but it I get the error from "System.Web.CachedPathData.GetConfigPathData(String configPath)" before ProcessRequest in MvcHandler.
Is "dot" not allowed at the end of a url? Or is there a way to fix the route definition to handle this url?
For an example: I have a table named Detail1 [Id(integer), Code(string), Description(string)] which has FK relationship with Master1 through it's Id column. Whenever I select a record of Master1, I also select it's Detail1 record to get it's Code field. In order to not to make this join everytime (since usually there isn't only one detail, there are more than one) I choose not to use Id column and I make Code PK of Detail1.
But when I get rid of Id and use Code as PK then my routes also start to work with Code field, like: Detail1\Edit\Code1
This Code can have anything in it or at the end, including DOT. There are cases where I can prohibit a DOT at the end but sometimes it's really meaningfull.
And I'have also seen this post that routes can be very flexible, so I didn't think mine is so weird.
So that's why I do something so non-standard. Any suggestions?
And also why it's so weird to have a DOT at the end of a url?
If you are using .NET 4.0, you can set this flag in the system.web section of your web.config and it will be allowed:
<httpRuntime relaxedUrlToFileSystemMapping="true" />
I've tested it and it works. Haack has an explanation of it.
This can be solved in a couple of ways in every ASP.NET version from 1.0 and up. I know it's two years after this thread has been created, but anyway, here it goes:
Cause
Creating your custom error handler, or configuring a custom page in IIS for redirecting the 404 will not work. The reason is that ASP.NET considers this URL dangerous. Internally in System.Web.Util.FileUtil, ASP.NET calls a private method IsSuspiciousPhysicalPath, which tries to map the path to a (virtual but legal) filename.
When the resulting legalized path is not equal to the original path, processing stops and the ASP.NET code returns a 404 (it doesn't ask IIS or the web.config for the custom 404, it returns one itself, which makes it so hard to do something about this).
Windows Explorer works the same way. Try to create a filename ending in one or more dots, i.e. test.txt.. You will find that the resulting name is text.txt.
Solution for ending URL in a dot in ASP.NET
The solution is simple (once you know it, it always is). Just before it sends out this 404, it will call Application_PreSendRequestHeaders, a simple event that you can register to in Global.asax.cs (or the VB equivalent). The following code will return a simple text to the browser, but a Redirect, or any other valid response is also possible.
protected void Application_PreSendRequestHeaders(object sender, EventArgs e)
{
HttpResponse response = this.Context.Response;
HttpRequest request = this.Context.Request;
if (request.RawUrl.EndsWith("."))
{
response.ClearContent();
response.StatusCode = 200;
response.StatusDescription = "OK";
response.SuppressContent = false;
response.ContentType = "text/plain";
response.Write("You have dot at the end of the url, this is allowed, but not by ASP.NET, but I caught you!");
response.End();
}
}
Note: this code also works when "aspx" is not part of the URL. I.e., http://example.com/app/somepath. will call that event. Also note that some paths still won't work (ending with multiple dots, with a hash-tag, or a < -sign, for instance, causes a 400- Bad Request). Then again, it does work for ending on a quote, a space+slash, or multiple dots separated by spaces.
Well, in .NET 4.5 I fixed this problem by adding "/" to the end of the url.
So, in your case it would be "http://localhost:81/Title/Edit/Code1./". It was the only thing I did, I didn't have to add httpRuntime setting.
add this to handlers
<add name="ExtensionlessUrlHandler-Integrated-4.0-ForApi"
path="api/*"
verb="*"
type="System.Web.Handlers.TransferRequestHandler"
preCondition="integratedMode,runtimeVersionv4.0" />
</handlers>
Perhaps http://localhost:81/Title/Edit/Code1%2E would work.
I escaped the period with a hex ascii code.
Why can't you have a dot-terminated URI?
Because a URI is a resource request and a historical imperitive exists on all relevant operating systems that the dot character is the extension separator. The last dot is treated as denoting a file extension, hence dot-terminating will make no sense.
Also worth reading:
RFC1738
RFC3986

GetVaryByCustomString method is not called

Have a problem on production server. On local and test servers this problem is not reproduced.
.NET 4.5, Sitecore 7.2.
Several user controls have the following directive:
<%# OutputCache VaryByParam="*" Duration="300" VaryByCustom="VaryByUrl" %>
Note: corresponding sitecore sublayouts have caching is turned off.
Method in Global.asax:
public override string GetVaryByCustomString(HttpContext context, string custom)
{
switch (custom.ToLower())
{
case "varybyurl":
return context.Request.Url.DnsSafeHost + context.Request.RawUrl + OutputCacheKey;
}
return base.GetVaryByCustomString(context, custom);
}
Previously caching was working normally. But since recent times, it was broken suddenly (but only on live server). Its behavior:
Page #1 with user control (that have mentioned directive) is loaded with some information (e.g. "Text A").
Then I am opening another page #2 with the same control but with another data (which should have "Text B"), but "Text A" is shown on this control on this page.
Only after 300 seconds, after refreshing the page #2, it shows "Text B".
I was trying to add the logging into GetVaryByCustomString and no logs was received on live server, so it means that method was not called.
Maybe someone has any idea why it works in such way?
Thank you!
Cause of problem is found!
Global.asax file was absent on live server.
It was not delivered during last build for some reason.
Current issue could be closed :)

Redirect Loop for Custom Errors Page

For error handling, I have added the following code to Web.config:
<system.web>
<customErrors mode="On" defaultRedirect="~/Error.cshtml?">
</customErrors>
<system.web>
And in Global.asax.cs:
void Application_Error(object sender, EventArgs e)
{
// Code that runs when an unhandled error occurs
Response.Redirect("/Error.cshtml?");
}
However, when the redirect to /Error.cshtml? occurs, there is an error 'This page has a redirect loop'
I've searched through other similar questions (such as How to solve Redirect Loop). However, I have no other routes calling Error.cshtml -- so does anyone have any idea what is causing this loop and how I can work around it?
EDIT: There are multiple errors occurring, and therefore the error page redirect is involved in a redirect loop. Does anyone know of a way to only call Response.Redirect("~/Error.cshtml") once?
EDIT2: If I change the redirect url to a random url outside of the project (such as https://www.facebook.com/), the customError redirect works properly. Still looking for a way to redirect to project page without infinitely looping through the error
Try adding:
Server.ClearError();
first to clear the existing error before redirecting.
Add redirectMode="ResponseRewrite" to customErrors section.

Custom HTTP error page

In asp.net, I can define a custom error page like this:
<configuration>
<system.web>
<customErrors mode="On">
<error statusCode="404" redirect="/servererrors/404.aspx" />
</customErrors>
</system.web>
</configuration>
Now my question: If I replace, say 404.aspx with AnyHTTP.aspx,
and want to get the number of the http error to generalize the page, how do I get that error numer?
Try this setting in CustomErrors (ASP.NET 3.5 SP1):
<customErrors mode="RemoteOnly" defaultRedirect="/servererrors/AnyHTTP.aspx" RedirectMode="ResponseRewrite"/>
As a different solution, you can also do this in Global.asax:
void Application_Error(object sender, EventArgs e)
{
Server.Transfer("/servererrors/AnyHTTP.aspx");
}
and on your error page, load the last error:
Exception e = Server.GetLastError();
It is important to use Server.Transfer() in the Global.asax file; using Response.Redirect will throw a 302 error and you will lose the error that you wanted to catch.
Well you might take a look at http://www.raboof.com/projects/Elmah/ before you venture to deep into doing your own thing...
I'd recommend not using the web.config method. customErrors redirects to the error page, which makes little sense. Essentially it first says "oh yes, that'll work perfectly, you just need to go here instead", and then says "oh, we didn't find that". That's really a bug (if there isn't anything here, then why did the server tell me to go here, clearly to the user code it looks like you the server code messed up; they went to the right URI and then you directed them to the wrong one).
Use Server.Transfer() from global.asax, set a default HTTPHandler, or set IIS to execute (not redirect to) your .aspx or other file with your implementation. If you want the same handler to manage each error, then you could, for example, do a Server.Transfer() from global.asax, but include a query string parameter about the type of error (whether simply an HTTP status code, or something more detailed), or pass information in the HttpContext.

CryptographicException: Padding is invalid and cannot be removed and Validation of viewstate MAC failed

Monitoring my global exception logs this error seems to be impossible to remove no matter what I do, I thought I finally got rid of it but it's back again. You can see a strack trace of the error on a similar post here.
Notes about the environment:
IIS 6.0, .NET 3.5 SP1 single server ASP.NET application
Steps already taken:
<system.web>
<machineKey validationKey="big encryption key"
decryptionKey="big decryption key"
validation="SHA1" decryption="AES" />
In my Page Base for all of my pages
protected override void OnInit(EventArgs e)
{
const string viewStateKey = "big key value";
Page.ViewStateUserKey = viewStateKey;
}
Also in the source of the page I can see that all of the ASP.NET generated hidden fields are correctly at the top of the page.
First of all lets start from the fact, that this error of view state happens on PostBack.
Also I must say that I have done all the things that every one suggest to do to avoid this problem. And I have single machine, but 2 pools that run the same Pages.
So someone do an action, ether a man, ether some other search machine by 'clicking' on your pages, or some hacker try to check your system for problems...
I have similar problems (rare but existing ones), and I finally found that people try to hack-test my pages. (from the same IP I have and dos attacks)
I modify the function LoadPageStateFromPersistenceMedium() that translate the viewstate, and see by logging what exactly was the input, and from what IPs... then I started monitor these results and see that the view state was changed by hand - or was totally empty.
On error I just redirect him to the same page...
Here is what I did...
public abstract class BasePage : System.Web.UI.Page
{
protected override object LoadPageStateFromPersistenceMedium()
{
try
{
.. return the base, or make here your decompress, or what ever...
return base.LoadPageStateFromPersistenceMedium();
}
catch (Exception x)
{
string vsString = Request.Form[__VIEWSTATE];
string cThePage = Request.RawUrl;
...log the x.ToString() error...
...log the vsString...
...log the ip coming from...
...log the cThePage...
// check by your self for local errors
Debug.Fail("Fail to load view state ! Reason:" + x.ToString());
}
// if reach here, then have fail, so I reload the page - maybe here you
// can place somthing like ?rnd=RandomNumber&ErrorId=1 and show a message
Responce.Redirect(Request.RawUrl, true);
// the return is not used after the redirect
return string.Empty;
}
}
Second Reason
Now there is one more reason why this can happen, and the reason is because some one click on your page before the __EVENTVALIDATION is loaded.
This eventValidation is placed on the last button-even that asp.net found, and if you have some of them on many place on the page, or near the button, then this go to the end of the page.
So even if you see the viewstate on the top of the page, where is the Validation ??? maybe this never loaded - page corrupt ?, too fast user click on page ?
<input type="hidden" name="__EVENTVALIDATION" id="__EVENTVALIDATION" ... >
To avoid this kind of problem I made a simple javascript that I do not let it press the button unless this input have been loaded !!!.
One more comment, the __EVENTVALIDATION is not always presents ! so is maybe safer not to search for this field if you make a general solution, but to make a javascript trick to just check if the full page is loaded, or something else that you think.
Here is my final solution with jQuery: (note that I check on PageLoad if eventvalidation exist !). I have this placed on my MasterPages.
<script language="javascript" type="text/javascript">
function AllowFormToRun()
{
var MyEventValidation = $("#__EVENTVALIDATION");
if(MyEventValidation.length == 0 || MyEventValidation.val() == ""){
alert("Please wait for the page to fully loaded.");
return false;
}
return true;
}
</script>
protected void Page_Load(object sender, EventArgs e)
{
// I do not know if Page can be null - just in case I place it.
if (Page != null && Page.EnableEventValidation)
{
Form.Attributes["onsubmit"] = "return AllowFormToRun();";
}
}
You can test by placing near the button of your page a delay.
<% System.Threading.Thread.Sleep(5000); %>
Update
Today I see in log this message again for WebResource and what I discover is that a bot getting the pages and make all the character on the links in lower case, including the parameters, so this was one more reason to not getting the correct encoded string, and throw a message like Padding is invalid and cannot be removed.
Hope this help you more.
A survey of the web pages found with several of the keywords from the error message indicate that this type of error is relatively common, usually random (at least in appearance) and unfortunately rarely inclusive of an explicit work-around or explanation...
The existence of many similar-yet-different situations is probably tied to the very many different architectures and underlying configurations which can somehow lead to the inability of the crypto layer to assert the authenticity of the MAC (Message Authentication Codes) in the request pages:
Server farm setup
Cross domain / syndicated pages
third party widget libraries and such
Actual ASP program logic (of course)
One relatively frequent "marker" around these bug reports is the mention of resource requests (eg. WebResource.axd).
Note that such requests are often not logged (lest they inflate the log files size with event of relative little interest). This absence from the log file and the fact they are often cached (and hence the relative random and infrequent occurrence of the bug) may explain how this possible origin of the bug go "under the radar". This also suggests that in trying to recreate the bug, (while tracking in the logs, in real time etc) it may be useful to prevent the web browser from caching (or for the least to clear it cache initially).
In short, here are a few ideas and things to look for:
start logging the *.axd requests
try and co-relate such axd requests with the error events in the exception log
look for pages with resource references
if in a Farm setting, ensure that all instances use the same key (apparently the snippet provided in the question hint at multiple IIS servers)
Be suspicious of pages with 3rd party tie-ins (search services, affiliate programs...)
Hope this helps ;-)
Are you sure your problem is cryptography related, and not caused by oversized ViewState?
If ViewState is the problem, you can chunk it - change the value of pages / MaxPageStateFieldLength in web.config

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