Integrate UserDetailsChecker into ReactiveAuthenticationManager & OAuth2 resource server implementations

[edeandrea]

I propose adding a reactive version of UserDetailsChecker along with an implementing class that mirrors the AccountStatusUserDetailsChecker.

This is frequently used when combined with a UserDetailsService for checking the status of a user's account and we need this on the reactive side as well.

It also needs to be tied into the ReactiveAuthenticationManager implementations (i.e. UserDetailsRepositoryReactiveAuthenticationManager). I would say we open a separate ticket for that integration and we keep this ticket just for the introduction of the ReactiveUserDetailsChecker.

I'm happy to supply a PR for this as I already have it built and could submit it pretty quickly.

[rwinch]

Thanks for the ticket @edeandrea!

I'm curious if we need a reactive version of UserDetailsChecker since the UserDetails is provided as an argument. Instead we could potentially use something like:

Mono<UserDetails> ud = ...;

return ud.doOnSucces(ud -> userDetailsChecker.check(ud));

[edeandrea]

Looking specifically at UserDetailsRepositoryReactiveAuthenticationManager (although I assume the pattern could be applied wherever it is implemented) wouldn't you want to do the user details check before the creation of the Authentication like in

@Override
public Mono<Authentication> authenticate(Authentication authentication) {
	final String username = authentication.getName();
	final String presentedPassword = (String) authentication.getCredentials();
	return this.userDetailsService.findByUsername(username)
			.publishOn(this.scheduler)
			.filter(u -> this.passwordEncoder.matches(presentedPassword, u.getPassword()))
			.switchIfEmpty(Mono.defer(() -> Mono.error(new BadCredentialsException("Invalid Credentials"))))
			.flatMap(u -> {
				boolean upgradeEncoding = this.userDetailsPasswordService != null
						&& this.passwordEncoder.upgradeEncoding(u.getPassword());
				if (upgradeEncoding) {
					String newPassword = this.passwordEncoder.encode(presentedPassword);
					return this.userDetailsPasswordService.updatePassword(u, newPassword);
				}
				return Mono.just(u);
			})
                        // Wouldn't you want to check the user details right here?
                        // Maybe like this?
                        .map(u -> {
                          this.userDetailsChecker.check(u);
                          return u;
                        })
			.map(u -> new UsernamePasswordAuthenticationToken(u, u.getPassword(), u.getAuthorities()) );
}

Would the doOnSuccess be evaluated at the correct point in time?

I guess either way the current UserDetailsChecker could be re-used. We'd just have to integrate it into the appropriate ReactiveAuthenticationManager implementations.

[rwinch]

Sounds good. I'd stick with .doOnNext which is doing something with the UserDetails without needing to change its value.

[edeandrea]

I'll rename this ticket then to something more appropriate for integrating UserDetailsChecker into the ReactiveAuthenticationManager implementations.

I'm happy to supply a PR for it as well.

[edeandrea]

I opened #6229 for this.