IdentityServer4 Reject Token Request If Custom Parameter Not Valid - asp.net-core

Question

I have this test client sending RequestToken:
var tokenResponse = await client.RequestTokenAsync(new TokenRequest
{
Address = disco.TokenEndpoint,
GrantType = "password",
ClientId = "My_Client",
ClientSecret = "mysecret",
Parameters =
{
{ "username", "user#entity.com" },
{ "password", "userpassword" },
{ "logged_entity_id", "143" },
{ "scope", "MyAPI" }
}
});
Now each user has a list of entity and I want to reject the token request if the value in the parameter "logged_entity_id" does not exist in the user's list of entity.
I was initially planning on checking it via IsActiveSync in my CustomProfileService but I can't seem to access the raw parameters in IsActiveSync method.
public class CustomProfileService : IProfileService
{
protected UserManager<User> _userManager;
public CustomProfileService(UserManager<User> userManager)
{
_userManager = userManager;
}
public Task GetProfileDataAsync(ProfileDataRequestContext context)
{
var claims = new List<Claim>
{
new Claim("LoggedEntityId", context.ValidatedRequest.Raw["logged_entity_id"])
};
context.IssuedClaims.AddRange(claims);
return Task.FromResult(0);
}
public Task IsActiveAsync(IsActiveContext context)
{
var user = _userManager.GetUserAsync(context.Subject).Result;
// var entityId = Can't access logged_entity_id parameter here
context.IsActive = user != null && user.DeletingDate == null && user.entities.Contains(entityId);
return Task.FromResult(0);
}
}
I'm not really sure if this is where I should check and reject it.

Answer 1

In asp.net core you can register a dependency using the built-in dependency injection container. The dependency injection container supplies the IHttpContextAccessor to any classes that declare it as a dependency in their constructors:
public void ConfigureServices(IServiceCollection services)
{
...
services.AddHttpContextAccessor();
...
}
Then in your class ,for example , in the implement of IProfileService :
private readonly IHttpContextAccessor _httpContextAccessor;
public CustomProfileService(IHttpContextAccessor httpContextAccessor)
{
_httpContextAccessor = httpContextAccessor;
}
Then in IsActiveAsync method get the value by :
var id = _httpContextAccessor.HttpContext.Request.Form["logged_entity_id"].ToString();

Answer 2

You can implement ICustomTokenValidator to validate token's request on your own way
You can run custom code as part of the token issuance pipeline at the token endpoint. This allows e.g. for
adding additional validation logic
changing certain parameters (e.g.token lifetime) dynamically
public class CustomValidator : ICustomTokenRequestValidator
{
public Task<TokenValidationResult> ValidateAccessTokenAsync(TokenValidationResult result)
{
throw new NotImplementedException();
}
public Task<TokenValidationResult> ValidateIdentityTokenAsync(TokenValidationResult result)
{
throw new NotImplementedException();
}
}
and in your startup.cs:
services.AddIdentityServer(options =>
{
...
})
.AddCustomTokenRequestValidator<CustomValidator>();