[[rsocket]]
= RSocket Security

Spring Security's RSocket support relies on a `SocketAcceptorInterceptor`.
The main entry point into security is in `PayloadSocketAcceptorInterceptor`, which adapts the RSocket APIs to allow intercepting a `PayloadExchange` with `PayloadInterceptor` implementations.

The following example shows a minimal RSocket Security configuration:

* Hello RSocket {gh-samples-url}/reactive/rsocket/hello-security[hellorsocket]
* https://github.com/rwinch/spring-flights/tree/security[Spring Flights]


== Minimal RSocket Security Configuration

You can find a minimal RSocket Security configuration below:

====
.Java
[source,java,role="primary"]
----
@Configuration
@EnableRSocketSecurity
public class HelloRSocketSecurityConfig {

	@Bean
	public MapReactiveUserDetailsService userDetailsService() {
		UserDetails user = User.withDefaultPasswordEncoder()
			.username("user")
			.password("user")
			.roles("USER")
			.build();
		return new MapReactiveUserDetailsService(user);
	}
}
----

.Kotlin
[source,kotlin,role="secondary"]
----
@Configuration
@EnableRSocketSecurity
open class HelloRSocketSecurityConfig {
    @Bean
    open fun userDetailsService(): MapReactiveUserDetailsService {
        val user = User.withDefaultPasswordEncoder()
            .username("user")
            .password("user")
            .roles("USER")
            .build()
        return MapReactiveUserDetailsService(user)
    }
}
----
====

This configuration enables <<rsocket-authentication-simple,simple authentication>> and sets up <<rsocket-authorization,rsocket-authorization>> to require an authenticated user for any request.

== Adding SecuritySocketAcceptorInterceptor

For Spring Security to work, we need to apply `SecuritySocketAcceptorInterceptor` to the `ServerRSocketFactory`.
Doing so connects our `PayloadSocketAcceptorInterceptor` with the RSocket infrastructure.
In a Spring Boot application, you can do this automatically by using `RSocketSecurityAutoConfiguration` with the following code:

====
.Java
[source,java,role="primary"]
----
@Bean
RSocketServerCustomizer springSecurityRSocketSecurity(SecuritySocketAcceptorInterceptor interceptor) {
    return (server) -> server.interceptors((registry) -> registry.forSocketAcceptor(interceptor));
}
----

.Kotlin
[source,kotlin,role="secondary"]
----
@Bean
fun springSecurityRSocketSecurity(interceptor: SecuritySocketAcceptorInterceptor): RSocketServerCustomizer {
    return RSocketServerCustomizer { server ->
        server.interceptors { registry ->
            registry.forSocketAcceptor(interceptor)
        }
    }
}
----
====

[[rsocket-authentication]]
== RSocket Authentication

RSocket authentication is performed with `AuthenticationPayloadInterceptor`, which acts as a controller to invoke a `ReactiveAuthenticationManager` instance.

[[rsocket-authentication-setup-vs-request]]
=== Authentication at Setup versus Request Time

Generally, authentication can occur at setup time or at request time or both.

Authentication at setup time makes sense in a few scenarios.
A common scenarios is when a single user (such as a mobile connection) uses an RSocket connection.
In this case, only a single user uses the connection, so authentication can be done once at connection time.

In a scenario where the RSocket connection is shared, it makes sense to send credentials on each request.
For example, a web application that connects to an RSocket server as a downstream service would make a single connection that all users use.
In this case, if the RSocket server needs to perform authorization based on the web application's users credentials, authentication for each request makes sense.

In some scenarios, authentication at both setup and for each request makes sense.
Consider a web application, as described previously.
If we need to restrict the connection to the web application itself, we can provide a credential with a `SETUP` authority at connection time.
Then each user can have different authorities but not the `SETUP` authority.
This means that individual users can make requests but not make additional connections.

[[rsocket-authentication-simple]]
=== Simple Authentication

Spring Security has support for the https://github.com/rsocket/rsocket/blob/5920ed374d008abb712cb1fd7c9d91778b2f4a68/Extensions/Security/Simple.md[Simple Authentication Metadata Extension].

[NOTE]
====
Basic Authentication evolved into Simple Authentication and is only supported for backward compatibility.
See `RSocketSecurity.basicAuthentication(Customizer)` for setting it up.
====

The RSocket receiver can decode the credentials by using `AuthenticationPayloadExchangeConverter`, which is automatically setup by using the `simpleAuthentication` portion of the DSL.
The following example shows an explicit configuration:

====
.Java
[source,java,role="primary"]
----
@Bean
PayloadSocketAcceptorInterceptor rsocketInterceptor(RSocketSecurity rsocket) {
	rsocket
		.authorizePayload(authorize ->
			authorize
					.anyRequest().authenticated()
					.anyExchange().permitAll()
		)
		.simpleAuthentication(Customizer.withDefaults());
	return rsocket.build();
}
----

.Kotlin
[source,kotlin,role="secondary"]
----
@Bean
open fun rsocketInterceptor(rsocket: RSocketSecurity): PayloadSocketAcceptorInterceptor {
    rsocket
        .authorizePayload { authorize -> authorize
                .anyRequest().authenticated()
                .anyExchange().permitAll()
        }
        .simpleAuthentication(withDefaults())
    return rsocket.build()
}
----
====

The RSocket sender can send credentials by using `SimpleAuthenticationEncoder`, which you can add to Spring's `RSocketStrategies`.

====
.Java
[source,java,role="primary"]
----
RSocketStrategies.Builder strategies = ...;
strategies.encoder(new SimpleAuthenticationEncoder());
----

.Kotlin
[source,kotlin,role="secondary"]
----
var strategies: RSocketStrategies.Builder = ...
strategies.encoder(SimpleAuthenticationEncoder())
----
====

You can then use it to send a username and password to the receiver in the setup:

====
.Java
[source,java,role="primary"]
----
MimeType authenticationMimeType =
	MimeTypeUtils.parseMimeType(WellKnownMimeType.MESSAGE_RSOCKET_AUTHENTICATION.getString());
UsernamePasswordMetadata credentials = new UsernamePasswordMetadata("user", "password");
Mono<RSocketRequester> requester = RSocketRequester.builder()
	.setupMetadata(credentials, authenticationMimeType)
	.rsocketStrategies(strategies.build())
	.connectTcp(host, port);
----

.Kotlin
[source,kotlin,role="secondary"]
----
val authenticationMimeType: MimeType =
    MimeTypeUtils.parseMimeType(WellKnownMimeType.MESSAGE_RSOCKET_AUTHENTICATION.string)
val credentials = UsernamePasswordMetadata("user", "password")
val requester: Mono<RSocketRequester> = RSocketRequester.builder()
    .setupMetadata(credentials, authenticationMimeType)
    .rsocketStrategies(strategies.build())
    .connectTcp(host, port)
----
====

Alternatively or additionally, a username and password can be sent in a request.

====
.Java
[source,java,role="primary"]
----
Mono<RSocketRequester> requester;
UsernamePasswordMetadata credentials = new UsernamePasswordMetadata("user", "password");

public Mono<AirportLocation> findRadar(String code) {
	return this.requester.flatMap(req ->
		req.route("find.radar.{code}", code)
			.metadata(credentials, authenticationMimeType)
			.retrieveMono(AirportLocation.class)
	);
}
----

.Kotlin
[source,kotlin,role="secondary"]
----
import org.springframework.messaging.rsocket.retrieveMono

// ...

var requester: Mono<RSocketRequester>? = null
var credentials = UsernamePasswordMetadata("user", "password")

open fun findRadar(code: String): Mono<AirportLocation> {
    return requester!!.flatMap { req ->
        req.route("find.radar.{code}", code)
            .metadata(credentials, authenticationMimeType)
            .retrieveMono<AirportLocation>()
    }
}
----
====

[[rsocket-authentication-jwt]]
=== JWT

Spring Security has support for the https://github.com/rsocket/rsocket/blob/5920ed374d008abb712cb1fd7c9d91778b2f4a68/Extensions/Security/Bearer.md[Bearer Token Authentication Metadata Extension].
The support comes in the form of authenticating a JWT (determining that the JWT is valid) and then using the JWT to make authorization decisions.

The RSocket receiver can decode the credentials by using `BearerPayloadExchangeConverter`, which is automatically setup by using the `jwt` portion of the DSL.
The following listing shows an example configuration:

====
.Java
[source,java,role="primary"]
----
@Bean
PayloadSocketAcceptorInterceptor rsocketInterceptor(RSocketSecurity rsocket) {
	rsocket
		.authorizePayload(authorize ->
			authorize
				.anyRequest().authenticated()
				.anyExchange().permitAll()
		)
		.jwt(Customizer.withDefaults());
	return rsocket.build();
}
----

.Kotlin
[source,kotlin,role="secondary"]
----
@Bean
fun rsocketInterceptor(rsocket: RSocketSecurity): PayloadSocketAcceptorInterceptor {
    rsocket
        .authorizePayload { authorize -> authorize
            .anyRequest().authenticated()
            .anyExchange().permitAll()
        }
        .jwt(withDefaults())
    return rsocket.build()
}
----
====

The configuration above relies on the existence of a `ReactiveJwtDecoder` `@Bean` being present.
An example of creating one from the issuer can be found below:

====
.Java
[source,java,role="primary"]
----
@Bean
ReactiveJwtDecoder jwtDecoder() {
	return ReactiveJwtDecoders
		.fromIssuerLocation("https://example.com/auth/realms/demo");
}
----

.Kotlin
[source,kotlin,role="secondary"]
----
@Bean
fun jwtDecoder(): ReactiveJwtDecoder {
    return ReactiveJwtDecoders
        .fromIssuerLocation("https://example.com/auth/realms/demo")
}
----
====

The RSocket sender does not need to do anything special to send the token, because the value is a simple `String`.
The following example sends the token at setup time:

====
.Java
[source,java,role="primary"]
----
MimeType authenticationMimeType =
	MimeTypeUtils.parseMimeType(WellKnownMimeType.MESSAGE_RSOCKET_AUTHENTICATION.getString());
BearerTokenMetadata token = ...;
Mono<RSocketRequester> requester = RSocketRequester.builder()
	.setupMetadata(token, authenticationMimeType)
	.connectTcp(host, port);
----

.Kotlin
[source,kotlin,role="secondary"]
----
val authenticationMimeType: MimeType =
    MimeTypeUtils.parseMimeType(WellKnownMimeType.MESSAGE_RSOCKET_AUTHENTICATION.string)
val token: BearerTokenMetadata = ...

val requester = RSocketRequester.builder()
    .setupMetadata(token, authenticationMimeType)
    .connectTcp(host, port)
----
====

Alternatively or additionally, you can send the token in a request:

====
.Java
[source,java,role="primary"]
----
MimeType authenticationMimeType =
	MimeTypeUtils.parseMimeType(WellKnownMimeType.MESSAGE_RSOCKET_AUTHENTICATION.getString());
Mono<RSocketRequester> requester;
BearerTokenMetadata token = ...;

public Mono<AirportLocation> findRadar(String code) {
	return this.requester.flatMap(req ->
		req.route("find.radar.{code}", code)
	        .metadata(token, authenticationMimeType)
			.retrieveMono(AirportLocation.class)
	);
}
----

.Kotlin
[source,kotlin,role="secondary"]
----
val authenticationMimeType: MimeType =
    MimeTypeUtils.parseMimeType(WellKnownMimeType.MESSAGE_RSOCKET_AUTHENTICATION.string)
var requester: Mono<RSocketRequester>? = null
val token: BearerTokenMetadata = ...

open fun findRadar(code: String): Mono<AirportLocation> {
    return this.requester!!.flatMap { req ->
        req.route("find.radar.{code}", code)
            .metadata(token, authenticationMimeType)
            .retrieveMono<AirportLocation>()
    }
}
----
====

[[rsocket-authorization]]
== RSocket Authorization

RSocket authorization is performed with `AuthorizationPayloadInterceptor`, which acts as a controller to invoke a `ReactiveAuthorizationManager` instance.
You can use the DSL to set up authorization rules based upon the `PayloadExchange`.
The following listing shows an example configuration:

====
.Java
[source,java,role="primary"]
----
rsocket
	.authorizePayload(authz ->
		authz
			.setup().hasRole("SETUP") // <1>
			.route("fetch.profile.me").authenticated() // <2>
			.matcher(payloadExchange -> isMatch(payloadExchange)) // <3>
				.hasRole("CUSTOM")
			.route("fetch.profile.{username}") // <4>
				.access((authentication, context) -> checkFriends(authentication, context))
			.anyRequest().authenticated() // <5>
			.anyExchange().permitAll() // <6>
	);
----
.Kotlin
[source,kotlin,role="secondary"]
----
rsocket
    .authorizePayload { authz ->
        authz
            .setup().hasRole("SETUP") // <1>
            .route("fetch.profile.me").authenticated() // <2>
            .matcher { payloadExchange -> isMatch(payloadExchange) } // <3>
            .hasRole("CUSTOM")
            .route("fetch.profile.{username}") // <4>
            .access { authentication, context -> checkFriends(authentication, context) }
            .anyRequest().authenticated() // <5>
            .anyExchange().permitAll()
    } // <6>
----
<1> Setting up a connection requires the `ROLE_SETUP` authority.
<2> If the route is `fetch.profile.me`, authorization only requires the user to be authenticated.
<3> In this rule, we set up a custom matcher, where authorization requires the user to have the `ROLE_CUSTOM` authority.
<4> This rule uses custom authorization.
The matcher expresses a variable with a name of `username` that is made available in the `context`.
A custom authorization rule is exposed in the `checkFriends` method.
<5> This rule ensures that a request that does not already have a rule requires the user to be authenticated.
A request is where the metadata is included.
It would not include additional payloads.
<6> This rule ensures that any exchange that does not already have a rule is allowed for anyone.
In this example, it means that payloads that have no metadata also have no authorization rules.
====

Note that authorization rules are performed in order.
Only the first authorization rule that matches is invoked.
