I'm working on an active directory managament application. In addition to the typical Create A New User, Enable/Disable an account, reset my password etc. it also managages application permissions for all of the clients web applications. Application management is handled by thousands of AD groups such as which are built from 3 letter codes for the application, section and site, there are also hundreds of AD groups which determine which applications and locations a coordinator can grant rights to. All of these groups in turn belong to other groups so I typically filter the groups list with the MemberOf property to find the groups that a user directly belongs to (or everyone has rights to do everything). I've made extensive use of the System.DirectoryServices.AccountManagment namespace using the FindByIdentity method in 31 places throughout the application. This method calls a private method FindPrincipalByIdentRefHelper on the internal ADStoreCtx class. A SearchResultCollection is created but not disposed so eventually typically once or twice a day the web server runs out of memory and all of the applications on the web server stop responsing until iis is reset because the resources used by the com objects aren't ever relased.
There are places where I fall back to the underlying directory objects, but there are lot of places where I'm using the properties on the Principal - it's a vast improvement over using the esoteric ad property names in the .Net 2.0 Directory services code.
I've contacted microsoft about the problem and it's been fixed in .Net 4.0 but they don't currently have plans to fix it in 3.5 unless there is intrest in the community about it.
I only found information about it in a couple of places
the MDSN documentation in the community content state's there is a memory leak at the bottom (guess I should have read that before using the the method)
http://msdn.microsoft.com/en-us/library/bb345628.aspx
And the class in question is internal and doesn't expose SearchResultsCollection outside the offending method so I can't get at the results to dispose them or inherit from the class and override the method.
So my questions are
Has anyone else encountered this problem? If so were you able to work around it?
Do I have any option besides rewriting the application not using any of the .Net 3.5 active directory code?
Thanks
I have encountered the same error, and no, I don't have a workaround other than using the DirectoryEntry approach.
Wrap your calls to directorysearcher inside a using block and also wrap the resultcollection inside a using block and call .Dispose() on the results explicitly. See answer here:
Memory Leak when using PrincipalSearcher.FindAll()
Related
I use a self hosted service within a WPF application for certain tasks. The service host is started at runtime and its base address is http://localhost:Whatever-port-is-free-at-runtime. This works fine when the user has admin rights but problems arise when the application is ran by a restricted user.
I found some suggestions on the web that suggested reserving the url using netsh/httpcfg which works fine for admin users but fails for restricted users because they presumably do not have the rights to use these tools to reserve a url. As the port number is not known until runtime the url reservation command can logically only be run at runtime which means the process will be initiated by a restricted user without the right privilege to execute the command. Am i correct in thinking this?
What i would like to know is if there is a suitable work around? Also, i would like to know if a restricted user can open a locally hosted WCF service at all, since solving the aforementioned problem will be pointless if the restricted user couldn't do this.
This question perfectly describes my first issue of URL reservation
In WCF, the HTTP and HTTPS bindings use HTTP.sys under the cover to reserve a required URL for a specific WCF service, which is the same path IIS itself follows while doing the bindings for the websites it manages. This explains why the process performing the HTTP/HTTPS binding is required to run in elevated mode.
That being said, I would solve your issue in two different ways:
Option 1: use a different kind of binding. NetTcpBinding and NetNamedPipesBinding, for example, do not generally require administrative privileges: this is by far the easiest way to go.
Option 2: setup the required namespace reservation at installation time. This way you may ask your users to perform the installation in elevated mode and later allow restricted accounts to run it. While performing the initial installation/reservation you may also find out an available port to use (and perhaps save it in a configuration file for later reuse).
In a domain with AD Sites and Services configured is it possible to get the Site of a computer from LDAP? Is it stored as an attribute?
Unless this has changed over the last couple of years outside of my knowledge, there is not. Historically this was never done as AD site knowledge was ephemeral...the assumption was that computers move around so storing where they are is silly. Plus there was no global need for the knowledge.
You could of course add this. By this i mean, you could do something like, extend the schema with a new attribute for this and set a start-up script on your domain-joined machines to write this (if it has changed since they last wrote) to the directory. Obviously you'll want to test this well to ensure it doesn't create more problems than it solves...
On the Win32 point of view you've got the DsAddressToSiteNamesEx API. I don't know how to find it using pure LDAP.
I have a WPF application that loads modules into my application via prism / MEF. Each module will reference an assembly I created to house NHibernate functionality (Unit of Work & repository pattern). Now that I started on the first module, the following questions came up:
Is it common place to have an nhibernate session open for the lifetime of a WPF / windows application?
Would it be a good idea to share the nhibernate session amongst all modules or have each module create its own session?
It's my understanding that the session is lightweight, so opening and closing a session is not a problem... however, if I close the session then I lose the change tracking... when I call Save, and the object is the same as when it was retrieve, I do not want a query to be executed.
Do not have the session open for a the lifetime of a wpf/windows application. You will have performance and memory problems if you do.
It really depends how these modules interact. Are they separate systems, or do they need to work in tandem to do work. If it's the former, I would say that they shouldn't share sessions. If it's the latter, I would use some kind of session manager that can pass out the current session.
Anybody here has actually implemented any logging strategy when application is running as XBAP ? Any suggestion (as code) as to how to implement a simple strategy base on your experience.
My app in desktop mode actually logs to a log file (rolling log) using integrated asop log4net implementation but in xbap I can't log cause it stores the file in cache (app2.0 or something folder) so I check if browser hosted and dont log since i dont even know if it ever logs...(why same codebase)....if there was a way to push this log to a service like a web service or post error to some endpoint...
My xbap is full trust intranet mode.
I would log to isolated storage and provide a way for users to submit the log back to the server using either a simple PUT/POST with HttpWebRequest or, if you're feeling frisky, via a WCF service.
Keep in mind an XBAP only gets 512k of isolated storage so you may actually want to push those event logs back to the server automatically. Also remember that the XBAP can only speak back to it's origin server, so the service that accepts the log files must run under the same domain.
Here's some quick sample code that shows how to setup a TextWriterTraceListener on top of an IsolatedStorageFileStream at which point you can can just use the standard Trace.Write[XXX] methods to do your logging.
IsolatedStorageFileStream traceFileStream = new IsolatedStorageFileStream("Trace.log", FileMode.OpenOrCreate, FileAccess.Write);
TraceListener traceListener = new TextWriterTraceListener(traceFileStream);
Trace.Listeners.Add(traceListener);
UPDATE
Here is a revised answer due to the revision you've made to your question with more details.
Since you mention you're using log4net in your desktop app we can build upon that dependency you are already comfortable working with as it is entirely possible to continue to use log4net in the XBAP version as well. Log4net does not come with an implementation that will solve this problem out of the box, but it is possible to write an implementation of a log4net IAppender which communicates with WCF.
I took a look at the implementation the other answerer linked to by Joachim Kerschbaumer (all credit due) and it looks like a solid implementation. My first concern was that, in a sample, someone might be logging back to the service on every event and perhaps synchronously, but the implementation actually has support for queuing up a certain number of events and sending them back to the server in batch form. Also, when it does send to the service, it does so using an async invocation of an Action delegate which means it will execute on a thread pool thread and not block the UI. Therefore I would say that implementation is quite solid.
Here's the steps I would take from here:
Download Joachim's WCF appender implementation
Add his project's to your solution.
Reference the WCFAppender project from your XBAP
Configure log4net to use the WCF appender. Now, there are several settings for this logger so I suggest checking out his sample app's config. The most important ones however are QueueSize and FlushLevel. You should set QueueSize high enough so that, based on how much you actually are logging, you won't be chattering with the WCF service too much. If you're just configuring warnings/errors then you can probably set this to something low. If you're configuring with informational then you want to set this a little higher. As far as FlushLevel you should probably just set this to ERROR as this will just guarantee that no matter how big the queue is at the time an error occurs everything will be flushed at the moment an error is logged.
The sample appears to use LINQ2SQL to log to a custom DB inside of the WCF service. You will need to replace this implementation to log to whatever data source best suits your needs.
Now, Joachim's sample is written in a way that's intended to be very easy for someone to download, run and understand very quickly. I would definitely change a couple things about it if I were putting it into a production solution:
Separate the WCF contracts into a separate library which you can share between the client and the server. This would allow you to stop using a Visual Studio service reference in the WCFAppender library and just reference the same contract library for the data types. Likewise, since the contracts would no longer be in the service itself, you would reference the contract library from the service.
I don't know that wsHttpBinding is really necessary here. It comes with a couple more knobs and switches than one probably needs for something as simple as this. I would probably go with the simpler basicHttpBinding and if you wanted to make sure the log data was encrypted over the wire I would just make sure to use HTTPS.
My approach has been to log to a remote service, keyed by a unique user ID or GUID. The overhead isn't very high with the usual async calls.
You can cache messages locally, too, either in RAM or in isolated storage -- perhaps as a backup in case the network isn't accessible.
Be sure to watch for duplicate events within a certain time window. You don't want to log 1,000 copies of the same Exception over a period of a few seconds.
Also, I like to log more than just errors. You can also log performance data, such as how long certain functions take to execute (particularly out-of-process calls), or more detailed data in response to the user explicitly entering into a "debug and report" mode. Checking for calls that take longer than a certain threshold is also useful to help catch regressions and preempt user complaints.
If you are running your XBAP under partial trust, you are only allowed to write to the IsolatedStorage on the client machine. And it's just 512 KB, which you would probably want to use in a more valuable way (than for logging), like for storing user's preferences.
You are not allowed to do any Remoting stuff as well under partial trust, so you can't use log4net RemotingAppender.
Finally, under partial trust XBAP you have WebPermission to talk to the server of your app origin only. I would recommend using a WCF service, like described in this article. We use similar configuration in my current project and it works fine.
Then, basically, on the WCF server side you can do logging to any place appropriate: file, database, etc. You may also want to keep your log4net logging code and try to use one of the wcf log appenders available on the internets (this or this).
I'm not finding much documentation on how to use Windows Authentication in a WPF app. I wouldn't have thought that it would be any different than in any non-WPF app, but it seems that it is. I want to go into my project Properties -> Application and ensure that Windows Authentication is on, but that option is not available in a WPF app (as the following document confirms).
http://msdn.microsoft.com/en-us/library/tzdks800.aspx
If I ignore all that and just look at My.User.Name (VB), it is empty. This tells me that somehow Windows Authentication is not enabled.
Seems like there is a concept I am missing; could someone point me in the right direction?
My plan is to use PrincipalPermissionAttribute to restrict access to certain parts of my app (or perhaps the entire app, by applying it to Application_Startup()).
Itowlson's answer is correct, but also, in order to use the PrincipalPermissionAttribute on any method, you have to first make the windows principal the current principal by calling:
AppDomain.CurrentDomain.SetPrincipalPolicy(PrincipalPolicy.WindowsPrincipal)
The reason this doesn't work in WPF is that these services are implemented in VB's WindowsFormsApplicationBase class, which isn't used in WPF applications. To do the same thing yourself:
Call WindowsIdentity.GetCurrent() to get the Windows user identity. You can get the name from this.
If you specifically want to set the thread principal the way the VB Windows Authentication option does, call Thread.CurrentPrincipal = new WindowsPrincipal(WindowsIdentity.GetCurrent()) -- this is exactly what WindowsFormsApplicationBase does internally.
EDIT: If you prefer the My.User API, it looks like you should be able to do the same thing by calling My.User.InitializeWithWindowsUser(). I haven't tested this though.