How to bypass the Validate method in UserNamepasswordvalidator after authentication - wcf

I am using Customvalidator class inheriting the UserNamepasswordvalidator
The problem is Its getting called on every request. I want to bypass it once the user is authenticated
any help would be appreciated

There's no way to skip the validator, custom, UserName/Password or certificate based. It's actually called before the request hits your main function, so there's no way to step around it using a session or variable.
And that's really the point of separating authentication from the message processing ... it allows you to reject bogus requests at the earliest stage of the request/response process so your program's not wasting cycles fighting off zombie attacks and the like.
You can, of course, apply no authentication up front in your message processing and authenticate when the request arrives (not before as in the prior model). At that point you can create a session programmatically and go on from there ... but you'll be processing every message that comes through.
I'll add this, however. If think that if you use something like NetTCPBinding, or NetNamedPipesBinding, you can create a persistant session between the client and host, thus authenticating only once.

Related

Variable scope in Apigee Edge. Request and Response

I am working with Apigee edge lately and am having trouble with a specific implementation. Essentially, the client will request an oauth token from their API through apigee. However, to make calls to our proxy they need an oauth token from us as well. So far my flow goes like this.
Client calls token endpoint on apigees side, a service callout is made to get a token from one of our other proxies (returned as a json object). Then the request passes through and gets the token from the clients API.
Here is where I am having trouble. After the response from the clients API, I want to use the assign message policy to modify the response to include the first token that was grabbed from our other proxy. The problem is the variable seems to be falling out of scope between request/response.
Am I missing something obvious here? I have looked into the PopulateCache policy, but I feel like this may be overkill as I only want the variable to remain in scope for the request/response. Thanks for any clarity you guys can provide! Sorry if my explanation is not very good, I am VERY new to Apigee Edge.
You aren't missing anything obvious. Variables should not fall out of scope between request and response flows. You are right that PopulateCache isn't necessary.
One item that catches people sometimes is how you access the response from the service callout. If you configure the service callout response to be stored in a variable called calloutResponse, then when you access the body to extract information, you'd use calloutResponse.content as the source. If you try to access calloutResponse instead, you might think that the variable had disappeared.
Add more details/trace if that is not the problem, and we can figure out what is going wrong.

WCF as BLL (Middle Tier) and Security techniques

So bear with me, i am new at MVC and WCF. I already have a set of services (WCF) that exposes my BLL and I am trying to consume those from my MVC.net web application but i am unsure on how to perform security operations here.
These are my app requirements:
Be able to consume WCF services using different credentials for every user on the web application
My BLL (WCF) needs to know what consumer is calling it (right now I only have the MVC app but i am planning to add iOS and Andriod calls to it, so later on i will add REST services to the WCF endpoints) Is there any design pattern for this out there? (or should i just use the soap header to include the caller ID? should i use some sort of caller secret or something?)
I need a security mechanism like Tokens or something so I dont have to pass the username and password on every call of the service method (WCF)
What i have so far:
WCF uses a certificate and and with a custom username validator.
I have manually coded proxies using the contract interfaces instead of generated proxies: But I hate the fact that i have to validate username and password every time a call is made to a WCF service. How in heaven can i use Tokens here? like to know if a given token sent on the soap header is valid or not yet expired? i have searched a lot and no tutorial/code/example is clear enough for me to actually start coding that ;(
I am trying to cache the ChannelFactory but should I? i mean, i will need to cache a channer factory per logged in user per contract ;( is that ok? what can i do here?
Thanks in advance!
Should you cache the ChannelFactory per user per contract?
It depends. There are a couple of considerations. Instantiating a channel factory could take up to 70ms. If you are doing this repeatedly, you will see a noticeable performance hit if you are not caching the ChannelFactory and instantiating one (or more) each time a user makes a http request to your MVC app that results in controller actions calling web services. This would indicate that caching the channelFactory would be beneficial for speed.
On the other hand, depending on the number of users you have, if you are caching a lot of channel factories (in a static dictionary for example), you are going to start to use a non-trivial amount of memory - this may become an issue for you.
You have to decide if the cost of instantiating channel factories on the fly (and correctly closing / aborting them and their contained channels) is too high a price vs increasing memory utilisation in the application pool hosting your MVC app.
Either way, I strongly advise to profile your app before you deploy to production.

wcf ServiceSecurityContext concurrency

I have a WCF service which uses a custom authentication and authorization manager.
Each time a client makes a call the authentication manager looks for a message header and uses the information to identify the user. The user gets created as an IPrincipal and placed into ServiceSecurityContext.Current.AuthorizationContext.Properties["Principal"].
I noticed on subsequent calls, where the users is different, the old user info is in the Current context. My service is tagged as PerCall. I am stumped on why the context is not getting cleared for every call.
Or is OperationContext different lifetime from SecurityContext?
If so any ideas on how to achieve what I described above? Thanks for help.

MVVM on top of claims aware web services

I'm looking for some input for a challenge that I'm currently facing.
I have built a custom WIF STS which I use to identify users who want to call some WCF services that my system offers. The WCF services use a custom authorization manager that determines whether or not the caller has the required claims to invoke a given service.
Now, I'm building a WPF app. on top of those WCF services. I'm using the MVVM pattern, such that the View Model invokes the protected WCF services (which implement the Model). The challenge that I'm facing is that I do not know whether or not the current user can succesfully invoke the web service methods without actually invoking them. Basically, what I want to achieve is to enable/disable certain parts of the UI based on the ability to succesfully invoke a method.
The best solution that I have come up with thus far is to create a service, which based on the same business logic as the custom authorization policy manager will be able to determine whether or not a user can invoke a given method. Now, the method would have to passed to this service as a string, or actually two strings, ServiceAddress and Method (Action), and based on that input, the service would be able to determine if the current user has the required claims to access the method. Obviously, for this to work, this service would itself have to require a issued token from the same STS, and with the same claims, in order to do its job.
Have any of you done something similar in the past, or do you have any good ideas on how to do this?
Thanks in advance,
Klaus
This depends a bit on what claims you're requiring in your services.
If your services require the same set of claims, I would recommend making a service that does nothing but checks the claims, and call that in advance. This would let you "pre-authorize" the user, in turn enabling/disabling the appropriate portions of the UI. When it comes time to call your actual services, the user can just call them at will, and you've already checked that it's safe.
If the services all require different sets of claims, and there is no easy way to verify that they will work in advance, I would just let the user call them, and handle this via normal exception handling. This is going to make life a bit trickier, though, since you'll have to let the user try (and fail) then disable.
Otherwise, you can do something like what you suggested - put in some form of catalog you can query for a specific user. In addition to just passing a address/method, it might be nicer to allow you to just pass an address, and retrieve the entire set of allowed (or disallowed, whichever is smaller) methods. This way you could reduce the round trips just for authentication.
An approach that I have taken is a class that does the inspection of a ClaimSet to guard the methods behind the service. I use attributes to decorate the methods with type, resource and right property values. Then the inspection class has a Demand method that throws an exception if the caller's ClaimSet does not contain a Claim with those property values. So before any method code executes, the claim inspection demand is called first. If the method is still executing after the demand, then the caller is good. There is also a bool function in the inspection class to answer the same question (does the caller have the appropriate claims) without throwing an exception.
I then package the inspection class so that it is deployed with clients and, as long as the client can also get the caller's ClaimSet (which I provide via a GetClaimSet method on the service) then it has everything it needs to make the same evaluations that the domain model is doing. I then use the bool method of the claim inspection class in the CanExecute method of ICommand properties in my view models to enable/disable controls and basically keep the user from getting authorization exceptions by not letting them do things that they don't have the claims for.
As far as how the client knows what claims are required for what methods, I guess I leave that up to the client developer to just know. In general on my projects this isn't a big problem because the methods have been very classic crud. So if the method is to add an Apple, then the claim required is intuitively going to be Type = Apple, Right = Add.
Not sure if this helps your situation but it has worked pretty well on some projects I have done.

WCF using Enterprise Library Validation Application Block - how to get hold of invalid messages?

I've got some WCF services (hosted in IIS 6) which use the Enterprise Library (4.0) Validation Application Block. If a client submits a message which fails validation (i.e. gets thrown back in a ValidationFault exception), I'd quite like to be able to log the message XML somewhere (using code, no IIS logs). All the validation happens before the service implementation code kicks in.
I'm sure it's possible to set up some class to get run before the service implementation (presumably this is how the Validation Application Block works), but I can't remember how, or work out exactly what to search for.
Is it possible to create a class and associated configuration that will give me access to either the whole SOAP request message, or at least the message body?
Take a look at using the Policy Injection Application Block...
I'm currently developing an application in which I intercept (using PIAB) all requests incoming to the server and based on the type of request I apply different validation behavior using the VAB.
Here's an article about integrating PIAB with WCF:
http://msdn.microsoft.com/en-us/magazine/cc136759.aspx
You can create different inteception mechanisms such as attributes applied to exposed operations.
You could log the whole WCF Message:
http://msdn.microsoft.com/en-us/library/ms730064.aspx
Or you could combine it with Enterprise Library Logging Application Block.
I found a blog post which seems to do what I want - you create a class that implements IDispatchMessageInspector. In the AfterReceiveRequest method, you have access to the whole incoming message, so can log away. This occurs after authentication, so you also have access to the user name - handy for logging. You can create supporting classes that let you assign this behaviour to services via attributes and/or configuration.
IDispatchMessageInspector also gives you a BeforeSendReply method, so you could log (or alter) your response message.
Now when customers attempt to literally hand-craft SOAP request messages (not even using some kind of DOM object) to our services, we have easy-to-access proof that they are sending rubbish!