MediatR.RequestAuthorization

Authorization rules for MediatR. This library uses pipline behavior IPipelineBehavior<,> in mediator middleware.

Installing MediatR.RequestAuthorization

You should install MediatR.RequestAuthorization with NuGet:

Install-Package MediatR.RequestAuthorization

Or via the .NET Core command line interface:

dotnet add package MediatR.RequestAuthorization

Implement IUserContext and register it on DI container

Simple implementation for aspnetcore:

public class HttpUserContext : IUserContext
{
    public IHttpContextAccessor Http { get; }

    public HttpUserContext(IHttpContextAccessor http)
    {
        Http = http;
        User = http?.HttpContext?.User;
    }

    public virtual string? ExtraAttribute(string key)
    {
        return null;
    }

    public ClaimsPrincipal? User { get; }
    public string? Id
    {
        get
        {
            if (User?.Identity != null && User.Identity.IsAuthenticated)
            {
                return User.Claims.FirstOrDefault(p => p.Type == ClaimTypes.NameIdentifier)?.Value ?? User.Claims.FirstOrDefault(p => p.Type == "sub")?.Value;
            }

            return null;
        }
    }
    public string Name => User?.Identity.Name;
    public bool IsAuthenticated => User?.Identity != null && User.Identity.IsAuthenticated;
    public virtual string? ClaimValue(string claimType)
    {
        return User?.Claims?.FirstOrDefault(p => p.Type == claimType)?.Value;
    }

    public virtual bool HasClaim(string type, string value)
    {
        return User?.HasClaim(type, value) ?? false;
    }

    public virtual bool HasClaim(Predicate<Claim> match)
    {
        return User?.HasClaim(match) ?? false;
    }
}

Add IAuthorizationRule<YourQueryOrCommand> to your DI container

services.AddTrancient<IAuthorizationRule<YourQueryOrCommand>,MySecurityRuleImplementation>();

Register behavior IAuthorizationRule<YourQueryOrCommand> to your DI container

services.AddMediatR(cfg =>
{
    cfg.RegisterServicesFromAssemblies(coreAsms); // all core handlers
    cfg.AddOpenBehavior(typeof(RequestAuthorizationBehavior<,>)); // enable security

});

Common usage (Example):

Define authorization rule for your IRequest impl class

//your IRequest class
public class GetProfileQuery:IRequest<UserProfile>
{
    
}

// your IAuthorizationRule class
class GetProfileQuerySecurityRule:IAuthorizationRule<GetProfileQuery>
{
    private readonly ISomeService _someService;

    public GetProfileQuerySecurityRule(ISomeService someService)
    {
        _someService = someService;
    }

    public Task Authorize(TRequest request, IUserContext userContext, CancellationToken cancellationToken)
    {
        
        if(userContext.IsAuthenticated)
        {
            return SecurltyResult.Ok();
        }

        return SecurityResult.AnonimousUser(request);

    }
}

SecurityResult is a static helper class, that wraps throwing Exceptions

AccessDeniedException is a helper Exception class. You may use your own exceptions.