In identity server 3 how to relate user to client - identityserver3

Question

I am using Identity Server 3. I have couple applications ie. Client configured and have few users configured. How do i establish the relationship between User and a Client and also view all applications that the selected User has access to.
Update 1
I am sorry if question was confusing. On IdSvr3 home page, there is a link to revoke application permissions. I am guessing in order to revoke the permission you have to first establish the relationship between user and application.
and i wanted to know how to establish that permission when i add new user?

Answer 1

There's no direct way to limit one or multiple users to a certain client. This is where you should think about implementing your own custom validation. Fortunately, the IdentityServer provides an extensibility point for this kind of requirement.
ICustomRequestValidator
You should implement this interface to further validate users to see if they belong to certain clients and filter them out. You can look into the user details by looking at ValidatedAuthorizeRequest.Subject. This custom validator will start after validating optional parameters such as nonce, prompt, arc_values ( AuthenticationContextReference ), login_hint, and etc. The endpoint is AuthorizeEndPointController and the default implementation of the interface for the tailored job is AuthorizeRequestValidator and its RunValidationAsync. You should take a look at the controller and the class.
Implementation tip
By the time the custom request validation begins, a Client reference will be presented in ValidatedAuthorizeRequest. So all you need to do would be matching the client id or some other identifiers you think you need to verify the client. Probably, you might want to add a Claim key-value pair to your client which you want to allow a few users.
Maybe something like this.
new InMemoryUser{Subject = "870805", Username = "damon", Password = "damon",
Claims = new Claim[]
{
new Claim(Constants.ClaimTypes.Name, "Damon Jeong"),
new Claim(Constants.ClaimTypes.Email, "dmjeong#email.com"),
new Claim(Constants.ClaimTypes.EmailVerified, "true", ClaimValueTypes.Boolean)
}
}
Assume you have above user, then add the subject id to the claim of a client like below.
new Client
{
ClientName = "WPF WebView Client Sample",
ClientId = "wpf.webview.client",
Flow = Flows.Implicit,
.
.
.
// Add claim for limiting this client to certain users.
// Since a claim only accepts type and value as string,
// You can add a list of subject id by comma separated values
// eg ( new Claim("BelongsToThisUser", "870805, 870806, 870807") )
Claims = new List<Claim>
{
new Claim("BelongsToThisUser", "870805")
}
},
And then just implement the ICustomRequestValidator and try to match the Claim value with the given user in its ValidateAuthorizeRequestAsync.
public class UserRequestLimitor : ICustomRequestValidator
{
public Task<AuthorizeRequestValidationResult> ValidateAuthorizeRequestAsync(ValidatedAuthorizeRequest request)
{
var clientClaim = request.Client.claims.Where(x => x.Type == "BelongsToThisUser").FirstOrDefault();
// Check is this client has "BelongsToThisUser" claim.
if(clientClaim != null)
{
var subClaim = request.Subject.Claims.Where(x => x.Type == "sub").FirstOrDefault() ?? new Claim(string.Empty, string.Empty);
if(clientClaim.Value == userClaim.Value)
{
return Task.FromResult<AuthorizeRequestValidationResult>(new AuthorizeRequestValidationResult
{
IsError = false
});
}
else
{
return Task.FromResult<AuthorizeRequestValidationResult>(new AuthorizeRequestValidationResult
{
ErrorDescription = "This client doesn't have an authorization to request a token for this user.",
IsError = true
});
}
}
// This client has no access controls over users.
else
{
return Task.FromResult<AuthorizeRequestValidationResult>(new AuthorizeRequestValidationResult
{
IsError = false
});
}
}
public Task<TokenRequestValidationResult> ValidateTokenRequestAsync(ValidatedTokenRequest request)
{
// your implementation
}
}
Time to DI
You need to inject your own dependency when you configure up your IdentityServer. The authorization server uses IdentityServerServiceFactory for registering dependencies.
var factory = new IdentityServerServiceFactory();
factory.Register(new Registration<ICustomRequestValidator>(resolver => new UserRequestLimitor()));
Then Autofac; the IoC container in IdentityServer will do the rest of the DI jobs for you.