Minor white-spece, import changes to minimize impact on existing code

2026-04-20 14:39:26 +01:00
1 parent 41ad6e68b5
commit b79fed5bcf
@@ -45,11 +45,9 @@ import org.apache.guacamole.net.auth.credentials.CredentialsInfo;
 import org.apache.guacamole.net.auth.credentials.GuacamoleInvalidCredentialsException;
 import org.apache.guacamole.net.auth.IdentifierGenerator;
 import org.jose4j.jwt.JwtClaims;
-
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;

-import org.apache.guacamole.net.auth.IdentifierGenerator;

 /**
 * Service that authenticates Guacamole users by processing OpenID tokens.
@@ -81,12 +79,6 @@ public class AuthenticationProviderService implements SSOAuthenticationProviderS
     */
    public static final String AUTH_SESSION_QUERY_PARAM = "state";

-    /**
-     * The REST API used for a local rediect and callback for the IdP to
-     * return a code and access stored PKCE verifiers
-     */
-    public static final String CODE_REDIRECT_API = "/api/ext/openid/redirect";
-
    /**
     * Service for retrieving OpenID configuration information.
     */
@@ -94,7 +86,7 @@ public class AuthenticationProviderService implements SSOAuthenticationProviderS
    private ConfigurationService confService;

    /**
-     * Manager of active SAML authentication attempts.
+     * Manager of active OpenID authentication attempts.
     */
    @Inject
    private OpenIDAuthenticationSessionManager sessionManager;
@@ -197,6 +189,7 @@ public class AuthenticationProviderService implements SSOAuthenticationProviderS
                        new TranslatableMessage("LOGIN.INFO_IDP_REDIRECT_PENDING"))
            }))
        );
+
    }

    @Override
@@ -0,0 +1,274 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.guacamole.auth.openid;
+
+import com.google.inject.Inject;
+import com.google.inject.Provider;
+import com.google.inject.Singleton;
+import java.net.URI;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.Map;
+import java.util.Set;
+import javax.ws.rs.core.UriBuilder;
+import org.apache.guacamole.auth.openid.conf.ConfigurationService;
+import org.apache.guacamole.auth.openid.OpenIDAuthenticationSessionManager;
+import org.apache.guacamole.auth.openid.token.TokenValidationService;
+import org.apache.guacamole.auth.openid.util.PKCEUtil;
+import org.apache.guacamole.GuacamoleException;
+import org.apache.guacamole.auth.sso.NonceService;
+import org.apache.guacamole.auth.sso.SSOAuthenticationProviderService;
+import org.apache.guacamole.auth.sso.user.SSOAuthenticatedUser;
+import org.apache.guacamole.form.Field;
+import org.apache.guacamole.form.RedirectField;
+import org.apache.guacamole.language.TranslatableMessage;
+import org.apache.guacamole.net.auth.Credentials;
+import org.apache.guacamole.net.auth.credentials.CredentialsInfo;
+import org.apache.guacamole.net.auth.credentials.GuacamoleInvalidCredentialsException;
+import org.apache.guacamole.net.auth.IdentifierGenerator;
+import org.jose4j.jwt.JwtClaims;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import org.apache.guacamole.net.auth.IdentifierGenerator;
+
+/**
+ * Service that authenticates Guacamole users by processing OpenID tokens.
+ */
+@Singleton
+public class AuthenticationProviderService implements SSOAuthenticationProviderService {
+
+    /**
+     * Logger for this class.
+     */
+    private final Logger logger = LoggerFactory.getLogger(AuthenticationProviderService.class);
+
+    /**
+     * The standard HTTP parameter which will be included within the URL by all
+     * OpenID services upon successful implicit flow authentication.
+     */
+    public static final String IMPLICIT_TOKEN_PARAMETER_NAME = "id_token";
+
+    /**
+     * The standard HTTP parameter which will be included within the URL by all
+     * OpenID services upon successful code flow authentication. Used to recover
+     * the stored user state.
+     */
+    public static final String CODE_TOKEN_PARAMETER_NAME = "code";
+
+    /**
+     * The name of the query parameter that identifies an active authentication
+     * session (in-progress OpenID authentication attempt).
+     */
+    public static final String AUTH_SESSION_QUERY_PARAM = "state";
+
+    /**
+     * The REST API used for a local rediect and callback for the IdP to
+     * return a code and access stored PKCE verifiers
+     */
+    public static final String CODE_REDIRECT_API = "/api/ext/openid/redirect";
+
+    /**
+     * Service for retrieving OpenID configuration information.
+     */
+    @Inject
+    private ConfigurationService confService;
+
+    /**
+     * Manager of active SAML authentication attempts.
+     */
+    @Inject
+    private OpenIDAuthenticationSessionManager sessionManager;
+
+    /**
+     * Service for validating and generating unique nonce values.
+     */
+    @Inject
+    private NonceService nonceService;
+
+    /**
+     * Service for validating received ID tokens.
+     */
+    @Inject
+    private TokenValidationService tokenService;
+
+    /**
+     * Provider for AuthenticatedUser objects.
+     */
+    @Inject
+    private Provider<SSOAuthenticatedUser> authenticatedUserProvider;
+
+    /**
+     * Return the value of the session identifier associated with the given
+     * credentials, or null if no session identifier is found in the
+     * credentials.
+     *
+     * @param credentials
+     *     The credentials from which to extract the session identifier.
+     *
+     * @return
+     *     The session identifier associated with the given credentials, or
+     *     null if no identifier is found.
+     */
+    public static String getSessionIdentifier(Credentials credentials) {
+
+        // Return the session identifier from the request params, if set, or
+        // null otherwise
+        return credentials != null ? credentials.getParameter(AUTH_SESSION_QUERY_PARAM) : null;
+    }
+
+    @Override
+    public SSOAuthenticatedUser authenticateUser(Credentials credentials)
+            throws GuacamoleException {
+
+        String username = null;
+        Set<String> groups = null;
+        Map<String,String> tokens = Collections.emptyMap();
+
+        logger.debug("OpenID authentication with {} flow (ID: {}, Secret: {}, PKCE: {})",
+                  confService.getFlowType(),
+                  confService.getClientID(),
+                  confService.getClientSecret(),
+                  confService.isPKCERequired());
+
+        if (confService.getFlowType().equals("implicit")) {
+            String token = credentials.getParameter(IMPLICIT_TOKEN_PARAMETER_NAME);
+            if (token != null) {
+                JwtClaims claims = tokenService.validateToken(token);
+                if (claims != null) {
+                    username = tokenService.processUsername(claims);
+                    groups = tokenService.processGroups(claims);
+                    tokens = tokenService.processAttributes(claims);
+                }
+            }
+        } else {
+            String verifier = null;
+            if (confService.isPKCERequired()) {
+                // Recover session
+                String identifier = getSessionIdentifier(credentials);
+                if (identifier != null) {
+                    verifier = sessionManager.getVerifier(identifier);
+                }
+            }
+            String code = credentials.getParameter("code");
+            if (code != null && (confService.isPKCERequired() == false || verifier != null)) {
+                JwtClaims claims = tokenService.validateCode(code, verifier);
+                if (claims != null) {
+                    username = tokenService.processUsername(claims);
+                    groups = tokenService.processGroups(claims);
+                    tokens = tokenService.processAttributes(claims);
+                }
+            }
+        }
+
+        // If the username was successfully retrieved from the token, produce
+        // authenticated user
+        if (username != null) {
+            // Create corresponding authenticated user
+            SSOAuthenticatedUser authenticatedUser = authenticatedUserProvider.get();
+            authenticatedUser.init(username, credentials, groups, tokens);
+            return authenticatedUser;
+        }
+
+        // Request OpenID token (will automatically redirect the user to the
+        // OpenID authorization page via JavaScript)
+        throw new GuacamoleInvalidCredentialsException("Invalid login.",
+            new CredentialsInfo(Arrays.asList(new Field[] {
+                new RedirectField(AUTH_SESSION_QUERY_PARAM, getLoginURI(),
+                        new TranslatableMessage("LOGIN.INFO_IDP_REDIRECT_PENDING"))
+            }))
+        );
+    }
+
+    @Override
+    public URI getLoginURI() throws GuacamoleException {
+        if (confService.getFlowType().equals("implicit")) {
+            return UriBuilder.fromUri(confService.getAuthorizationEndpoint())
+                    .queryParam("scope", confService.getScope())
+                    .queryParam("response_type", IMPLICIT_TOKEN_PARAMETER_NAME)
+                    .queryParam("client_id", confService.getClientID())
+                    .queryParam("redirect_uri", confService.getRedirectURI())
+                    .queryParam("nonce", nonceService.generate(confService.getMaxNonceValidity() * 60000L))
+                    .build();
+        } else  {
+            UriBuilder builder = UriBuilder.fromUri(confService.getAuthorizationEndpoint())
+                    .queryParam("scope", confService.getScope())
+                    .queryParam("response_type", CODE_TOKEN_PARAMETER_NAME)
+                    .queryParam("client_id", confService.getClientID())
+                    .queryParam("redirect_uri", confService.getRedirectURI());
+
+            if (confService.isPKCERequired()) {
+                String codeVerifier = PKCEUtil.generateCodeVerifier();
+                String codeChallenge;
+
+                try {
+                    codeChallenge = PKCEUtil.generateCodeChallenge(codeVerifier);
+                }
+                catch (Exception e) {
+                    throw new GuacamoleException("Unable to compute PKCE challenge", e);
+                }
+
+                // Store verifier for authenticateUser
+                OpenIDAuthenticationSession session = new OpenIDAuthenticationSession(codeVerifier,
+                            confService.getAuthenticationTimeout() * 60000L);
+                String identifier = IdentifierGenerator.generateIdentifier();
+                sessionManager.defer(session, identifier);
+
+                builder.queryParam("code_challenge", codeChallenge)
+                       .queryParam("code_challenge_method", "S256")
+                       .queryParam(AUTH_SESSION_QUERY_PARAM, identifier);
+            }
+
+            return builder.build();
+        }
+    }
+
+    @Override
+    public URI getLogoutURI(String idToken) throws GuacamoleException {
+
+        // If no logout endpoint is configured, return null
+        URI logoutEndpoint = confService.getLogoutEndpoint();
+        if (logoutEndpoint == null)
+            return null;
+
+        // Build the logout URI with appropriate parameters
+        UriBuilder logoutUriBuilder = UriBuilder.fromUri(logoutEndpoint);
+
+        // Add post_logout_redirect_uri parameter
+        logoutUriBuilder.queryParam("post_logout_redirect_uri",
+                confService.getPostLogoutRedirectURI());
+
+        // Add id_token_hint if available, otherwise add client_id
+        if (idToken != null && !idToken.isEmpty())
+            logoutUriBuilder.queryParam("id_token_hint", idToken);
+        else
+            logoutUriBuilder.queryParam("client_id", confService.getClientID());
+
+        return logoutUriBuilder.build();
+    }
+
+    @Override
+    public void shutdown() {
+        sessionManager.shutdown();
+    }
+
+}
@@ -0,0 +1,11 @@
+--- extensions/guacamole-auth-sso/modules/guacamole-auth-sso-openid/src/main/java/org/apache/guacamole/auth/openid/OpenIDAuthenticationProviderModule.java	2026-04-08 19:37:41.518619970 +0200
+++ extensions/guacamole-auth-sso/modules/guacamole-auth-sso-openid/src/main/java/org/apache/guacamole/auth/openid/OpenIDAuthenticationProviderModule.java	2026-04-08 16:43:54.617087120 +0200
+@@ -37,7 +37,7 @@
+      * The configuration environment for this server and extension.
+      */
+     private final Environment environment = new OpenIDEnvironment();
+-
+    
+     @Override
+     protected void configure() {
+         bind(ConfigurationService.class);
@@ -461,7 +461,6 @@ public class ConfigurationService {
        return environment.getProperty(OPENID_AUTH_TIMEOUT, 5);
    }

-
    /**
     * Returns the claim type which contains the authenticated user's username
     * within any valid JWT, as configured with guacamole.properties. By
@@ -0,0 +1,639 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.guacamole.auth.openid.conf;
+
+import com.google.inject.Inject;
+import java.net.URI;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+import org.apache.guacamole.GuacamoleException;
+import org.apache.guacamole.environment.Environment;
+import org.apache.guacamole.properties.BooleanGuacamoleProperty;
+import org.apache.guacamole.properties.IntegerGuacamoleProperty;
+import org.apache.guacamole.properties.StringGuacamoleProperty;
+import org.apache.guacamole.properties.URIGuacamoleProperty;
+
+/**
+ * Service for retrieving configuration information regarding the OpenID
+ * service.
+ */
+public class ConfigurationService {
+
+    /**
+     * The default OICD flow type
+     */
+    private static final String DEFAULT_FLOW_TYPE = "implicit";
+
+    /**
+     * The default claim type to use to retrieve an authenticated user's
+     * username.
+     */
+    private static final String DEFAULT_USERNAME_CLAIM_TYPE = "email";
+
+    /**
+     * The default claim type to use to retrieve an authenticated user's
+     * groups.
+     */
+    private static final String DEFAULT_GROUPS_CLAIM_TYPE = "groups";
+
+    /**
+     * The default JWT claims list to map to tokens.
+     */
+    private static final List<String> DEFAULT_ATTRIBUTES_CLAIM_TYPE = Collections.emptyList();
+
+    /**
+     * The default space-separated list of OpenID scopes to request.
+     */
+    private static final String DEFAULT_SCOPE = "openid email profile";
+
+    /**
+     * The default amount of clock skew tolerated for timestamp comparisons
+     * between the Guacamole server and OpenID service clocks, in seconds.
+     */
+    private static final int DEFAULT_ALLOWED_CLOCK_SKEW = 30;
+
+    /**
+     * The default maximum amount of time that an OpenID token should remain
+     * valid, in minutes.
+     */
+    private static final int DEFAULT_MAX_TOKEN_VALIDITY = 300;
+
+    /**
+     * The default maximum amount of time that a nonce generated by the
+     * Guacamole server should remain valid, in minutes.
+     */
+    private static final int DEFAULT_MAX_NONCE_VALIDITY = 10;
+
+    /**
+     * The authorization endpoint (URI) of the OpenID service.
+     */
+    private static final URIGuacamoleProperty OPENID_AUTHORIZATION_ENDPOINT =
+            new URIGuacamoleProperty() {
+
+        @Override
+        public String getName() { return "openid-authorization-endpoint"; }
+
+    };
+
+    /**
+     * The endpoint (URI) of the JWKS service which defines how received ID
+     * tokens (JWTs) shall be validated.
+     */
+    private static final URIGuacamoleProperty OPENID_JWKS_ENDPOINT =
+            new URIGuacamoleProperty() {
+
+        @Override
+        public String getName() { return "openid-jwks-endpoint"; }
+
+    };
+
+    /**
+     * The issuer to expect for all received ID tokens.
+     */
+    private static final StringGuacamoleProperty OPENID_ISSUER =
+            new StringGuacamoleProperty() {
+
+        @Override
+        public String getName() { return "openid-issuer"; }
+
+    };
+
+    /**
+     * The token endpoint (URI) of the OIDC service.
+     */
+    private static final URIGuacamoleProperty OPENID_TOKEN_ENDPOINT =
+            new URIGuacamoleProperty() {
+        @Override
+        public String getName() {
+            return "openid-token-endpoint";
+        }
+    };
+
+    /**
+     * The flow type of the OpenID service.
+     */
+    private static final StringGuacamoleProperty OPENID_FLOW_TYPE =
+            new StringGuacamoleProperty() {
+
+        @Override
+        public String getName() { return "openid-flow-type"; }
+
+    };
+
+    /**
+     * OIDC client secret which should be submitted to the OIDC service when
+     * validating tokens with code flow
+     */
+    private static final StringGuacamoleProperty OPENID_CLIENT_SECRET =
+            new StringGuacamoleProperty() {
+        @Override
+        public String getName() {
+            return "openid-client-secret";
+        }
+    };
+
+    /**
+     * True if "Proof Key for Code Exchange" (PKCE) must be used.
+     */
+    private static final BooleanGuacamoleProperty OPENID_PKCE_REQUIRED =
+            new BooleanGuacamoleProperty() {
+        @Override
+        public String getName() {
+            return "openid-pkce-required";
+        }
+    };
+
+    /**
+     * The maximum amount of time to allow for an in-progress OpenID
+     * authentication attempt to be completed, in minutes. A user that takes
+     * longer than this amount of time to complete authentication with their
+     * identity provider will be redirected back to the identity provider to
+     * try again.
+     */
+    private static final IntegerGuacamoleProperty OPENID_AUTH_TIMEOUT =
+            new IntegerGuacamoleProperty() {
+        @Override
+        public String getName() { return "openid-auth-timeout"; }
+
+    };
+
+
+    /**
+     * The claim type which contains the authenticated user's username within
+     * any valid JWT.
+     */
+    private static final StringGuacamoleProperty OPENID_USERNAME_CLAIM_TYPE =
+            new StringGuacamoleProperty() {
+
+        @Override
+        public String getName() { return "openid-username-claim-type"; }
+
+    };
+
+    /**
+     * The claim type which contains the authenticated user's groups within
+     * any valid JWT.
+     */
+    private static final StringGuacamoleProperty OPENID_GROUPS_CLAIM_TYPE =
+            new StringGuacamoleProperty() {
+
+        @Override
+        public String getName() { return "openid-groups-claim-type"; }
+
+    };
+
+    /**
+     * The claims within any valid JWT that should be mapped to
+     * the authenticated user's tokens, as configured with guacamole.properties.
+     */
+    private static final StringGuacamoleProperty OPENID_ATTRIBUTES_CLAIM_TYPE =
+            new StringGuacamoleProperty() {
+                @Override
+                public String getName() { return "openid-attributes-claim-type"; }
+            };
+
+    /**
+     * The space-separated list of OpenID scopes to request.
+     */
+    private static final StringGuacamoleProperty OPENID_SCOPE =
+            new StringGuacamoleProperty() {
+
+        @Override
+        public String getName() { return "openid-scope"; }
+
+    };
+
+    /**
+     * The amount of clock skew tolerated for timestamp comparisons between the
+     * Guacamole server and OpenID service clocks, in seconds.
+     */
+    private static final IntegerGuacamoleProperty OPENID_ALLOWED_CLOCK_SKEW =
+            new IntegerGuacamoleProperty() {
+
+        @Override
+        public String getName() { return "openid-allowed-clock-skew"; }
+
+    };
+
+    /**
+     * The maximum amount of time that an OpenID token should remain valid, in
+     * minutes.
+     */
+    private static final IntegerGuacamoleProperty OPENID_MAX_TOKEN_VALIDITY =
+            new IntegerGuacamoleProperty() {
+
+        @Override
+        public String getName() { return "openid-max-token-validity"; }
+
+    };
+
+    /**
+     * The maximum amount of time that a nonce generated by the Guacamole server
+     * should remain valid, in minutes. As each OpenID request has a unique
+     * nonce value, this imposes an upper limit on the amount of time any
+     * particular OpenID request can result in successful authentication within
+     * Guacamole.
+     */
+    private static final IntegerGuacamoleProperty OPENID_MAX_NONCE_VALIDITY =
+            new IntegerGuacamoleProperty() {
+
+        @Override
+        public String getName() { return "openid-max-nonce-validity"; }
+
+    };
+
+    /**
+     * OpenID client ID which should be submitted to the OpenID service when
+     * necessary. This value is typically provided by the OpenID service when
+     * OpenID credentials are generated for your application.
+     */
+    private static final StringGuacamoleProperty OPENID_CLIENT_ID =
+            new StringGuacamoleProperty() {
+
+        @Override
+        public String getName() { return "openid-client-id"; }
+
+    };
+
+    /**
+     * The URI that the OpenID service should redirect to after the
+     * authentication process is complete. This must be the full URL that a
+     * user would enter into their browser to access Guacamole.
+     */
+    private static final URIGuacamoleProperty OPENID_REDIRECT_URI =
+            new URIGuacamoleProperty() {
+
+        @Override
+        public String getName() { return "openid-redirect-uri"; }
+
+    };
+
+    /**
+     * The logout endpoint (URI) of the OpenID service. If specified, users
+     * will be redirected to this endpoint when they log out, allowing them
+     * to log out from the OpenID provider as well.
+     */
+    private static final URIGuacamoleProperty OPENID_LOGOUT_ENDPOINT =
+            new URIGuacamoleProperty() {
+
+        @Override
+        public String getName() { return "openid-logout-endpoint"; }
+
+    };
+
+    /**
+     * The URI that the OpenID service should redirect to after logout is
+     * complete. If not specified, the main redirect URI will be used.
+     */
+    private static final URIGuacamoleProperty OPENID_POST_LOGOUT_REDIRECT_URI =
+            new URIGuacamoleProperty() {
+
+        @Override
+        public String getName() { return "openid-post-logout-redirect-uri"; }
+
+    };
+
+    /**
+     * The Guacamole server environment.
+     */
+    @Inject
+    private Environment environment;
+
+    /**
+     * Returns the authorization endpoint (URI) of the OpenID service as
+     * configured with guacamole.properties.
+     *
+     * @return
+     *     The authorization endpoint of the OpenID service, as configured with
+     *     guacamole.properties.
+     *
+     * @throws GuacamoleException
+     *     If guacamole.properties cannot be parsed, or if the authorization
+     *     endpoint property is missing.
+     */
+    public URI getAuthorizationEndpoint() throws GuacamoleException {
+        return environment.getRequiredProperty(OPENID_AUTHORIZATION_ENDPOINT);
+    }
+
+    /**
+     * Returns the OpenID client ID which should be submitted to the OpenID
+     * service when necessary, as configured with guacamole.properties. This
+     * value is typically provided by the OpenID service when OpenID credentials
+     * are generated for your application.
+     *
+     * @return
+     *     The client ID to use when communicating with the OpenID service,
+     *     as configured with guacamole.properties.
+     *
+     * @throws GuacamoleException
+     *     If guacamole.properties cannot be parsed, or if the client ID
+     *     property is missing.
+     */
+    public String getClientID() throws GuacamoleException {
+        return environment.getRequiredProperty(OPENID_CLIENT_ID);
+    }
+
+    /**
+     * Returns the URI that the OpenID service should redirect to after
+     * the authentication process is complete, as configured with
+     * guacamole.properties. This must be the full URL that a user would enter
+     * into their browser to access Guacamole.
+     *
+     * @return
+     *     The client secret to use when communicating with the OpenID service,
+     *     as configured with guacamole.properties.
+     *
+     * @throws GuacamoleException
+     *     If guacamole.properties cannot be parsed, or if the redirect URI
+     *     property is missing.
+     */
+    public URI getRedirectURI() throws GuacamoleException {
+        return environment.getRequiredProperty(OPENID_REDIRECT_URI);
+    }
+
+    /**
+     * Returns the issuer to expect for all received ID tokens, as configured
+     * with guacamole.properties.
+     *
+     * @return
+     *     The issuer to expect for all received ID tokens, as configured with
+     *     guacamole.properties.
+     *
+     * @throws GuacamoleException
+     *     If guacamole.properties cannot be parsed, or if the issuer property
+     *     is missing.
+     */
+    public String getIssuer() throws GuacamoleException {
+        return environment.getRequiredProperty(OPENID_ISSUER);
+    }
+
+    /**
+     * Returns the endpoint (URI) of the JWKS service which defines how
+     * received ID tokens (JWTs) shall be validated, as configured with
+     * guacamole.properties.
+     *
+     * @return
+     *     The endpoint (URI) of the JWKS service which defines how received ID
+     *     tokens (JWTs) shall be validated, as configured with
+     *     guacamole.properties.
+     *
+     * @throws GuacamoleException
+     *     If guacamole.properties cannot be parsed, or if the JWKS endpoint
+     *     property is missing.
+     */
+    public URI getJWKSEndpoint() throws GuacamoleException {
+        return environment.getRequiredProperty(OPENID_JWKS_ENDPOINT);
+    }
+
+    /**
+     * Returns the token endpoint (URI) of the OIDC service as
+     * configured with guacamole.properties.
+     *
+     * @return
+     *     The token endpoint of the OIDC service, as configured with
+     *     guacamole.properties.
+     *
+     * @throws GuacamoleException
+     *     If guacamole.properties cannot be parsed, or if the authorization
+     *     endpoint property is missing.
+     */
+    public URI getTokenEndpoint() throws GuacamoleException {
+        return environment.getRequiredProperty(OPENID_TOKEN_ENDPOINT);
+    }
+
+    /**
+     * Returns the flow type of the OpenID service as configured with guacamole.properties.
+     *
+     * @return
+     *     The flow type of the OpenID service, as configured with guacamole.properties. Can
+     *     be either 'implicit' or 'code'.
+     *
+     * @throws GuacamoleException
+     *     If guacamole.properties cannot be parsed.
+     */
+    public String getFlowType() throws GuacamoleException {
+        return environment.getProperty(OPENID_FLOW_TYPE, DEFAULT_FLOW_TYPE);
+    }
+
+    /**
+     * Returns the OIDC client secret used for toen validation, as configured
+     * with guacamole.properties. This value is typically provided by the OIDC
+     * service when OIDC credentials are generated for your application, and
+     * may be null.
+     *
+     * @return
+     *     The client secret to use when communicating with the OIDC service,
+     *     as configured with guacamole.properties.
+     *
+     * @throws GuacamoleException
+     *     If guacamole.properties cannot be parsed, or if the client ID
+     *     property is missing.
+     */
+    public String getClientSecret() throws GuacamoleException {
+       return environment.getProperty(OPENID_CLIENT_SECRET);
+    }
+
+    /**
+     * Returns  a boolean value of whether "Proof Key for Code Exchange (PKCE)"
+     * will be used, as configured with guacamole.properties. The choice of
+     * whether to use PKCE is up to you, but the OIDC service must support
+     * it. By default will be false.
+     *
+     * @return
+     *     The whether to use PKCE or not, as configured with guacamole.properties.
+     *
+     * @throws GuacamoleException
+     *     If guacamole.properties cannot be parsed.
+     */
+    public boolean isPKCERequired() throws GuacamoleException {
+        Boolean enabled = environment.getProperty(OPENID_PKCE_REQUIRED);
+        return enabled != null && enabled;
+    }
+
+    /**
+     * Returns the maximum amount of time to allow for an in-progress OpenID
+     * authentication attempt to be completed, in minutes. A user that takes
+     * longer than this amount of time to complete authentication with their
+     * identity provider will be redirected back to the identity provider to
+     * try again.
+     *
+     * @return
+     *     The maximum amount of time to allow for an in-progress SAML
+     *     authentication attempt to be completed, in minutes.
+     *
+     * @throws GuacamoleException
+     *     If the authentication timeout cannot be parsed.
+     */
+    public int getAuthenticationTimeout() throws GuacamoleException {
+        return environment.getProperty(OPENID_AUTH_TIMEOUT, 5);
+    }
+
+
+    /**
+     * Returns the claim type which contains the authenticated user's username
+     * within any valid JWT, as configured with guacamole.properties. By
+     * default, this will be "email".
+     *
+     * @return
+     *     The claim type which contains the authenticated user's username
+     *     within any valid JWT, as configured with guacamole.properties.
+     *
+     * @throws GuacamoleException
+     *     If guacamole.properties cannot be parsed.
+     */
+    public String getUsernameClaimType() throws GuacamoleException {
+        return environment.getProperty(OPENID_USERNAME_CLAIM_TYPE, DEFAULT_USERNAME_CLAIM_TYPE);
+    }
+
+    /**
+     * Returns the claim type which contains the authenticated user's groups
+     * within any valid JWT, as configured with guacamole.properties. By
+     * default, this will be "groups".
+     *
+     * @return
+     *     The claim type which contains the authenticated user's groups
+     *     within any valid JWT, as configured with guacamole.properties.
+     *
+     * @throws GuacamoleException
+     *     If guacamole.properties cannot be parsed.
+     */
+    public String getGroupsClaimType() throws GuacamoleException {
+        return environment.getProperty(OPENID_GROUPS_CLAIM_TYPE, DEFAULT_GROUPS_CLAIM_TYPE);
+    }
+
+    /**
+     * Returns the claims list within any valid JWT that should be mapped to
+     * the authenticated user's tokens, as configured with guacamole.properties.
+     * Empty by default.
+     *
+     * @return
+     *     The claims list within any valid JWT that should be mapped to
+     *     the authenticated user's tokens, as configured with guacamole.properties.
+     *
+     * @throws GuacamoleException
+     *     If guacamole.properties cannot be parsed.
+     */
+    public Collection<String> getAttributesClaimType() throws GuacamoleException {
+        return environment.getPropertyCollection(OPENID_ATTRIBUTES_CLAIM_TYPE, DEFAULT_ATTRIBUTES_CLAIM_TYPE);
+    }
+
+    /**
+     * Returns the space-separated list of OpenID scopes to request. By default,
+     * this will be "openid email profile". The OpenID scopes determine the
+     * information returned within the OpenID token, and thus affect what
+     * values can be used as an authenticated user's username.
+     *
+     * @return
+     *     The space-separated list of OpenID scopes to request when identifying
+     *     a user.
+     *
+     * @throws GuacamoleException
+     *     If guacamole.properties cannot be parsed.
+     */
+    public String getScope() throws GuacamoleException {
+        return environment.getProperty(OPENID_SCOPE, DEFAULT_SCOPE);
+    }
+
+    /**
+     * Returns the amount of clock skew tolerated for timestamp comparisons
+     * between the Guacamole server and OpenID service clocks, in seconds. Too
+     * much clock skew will affect token expiration calculations, possibly
+     * allowing old tokens to be used. By default, this will be 30.
+     *
+     * @return
+     *     The amount of clock skew tolerated for timestamp comparisons, in
+     *     seconds.
+     *
+     * @throws GuacamoleException
+     *     If guacamole.properties cannot be parsed.
+     */
+    public int getAllowedClockSkew() throws GuacamoleException {
+        return environment.getProperty(OPENID_ALLOWED_CLOCK_SKEW, DEFAULT_ALLOWED_CLOCK_SKEW);
+    }
+
+    /**
+     * Returns the maximum amount of time that an OpenID token should remain
+     * valid, in minutes. A token received from an OpenID service which is
+     * older than this amount of time will be rejected, even if it is otherwise
+     * valid. By default, this will be 300 (5 hours).
+     *
+     * @return
+     *     The maximum amount of time that an OpenID token should remain valid,
+     *     in minutes.
+     *
+     * @throws GuacamoleException
+     *     If guacamole.properties cannot be parsed.
+     */
+    public int getMaxTokenValidity() throws GuacamoleException {
+        return environment.getProperty(OPENID_MAX_TOKEN_VALIDITY, DEFAULT_MAX_TOKEN_VALIDITY);
+    }
+
+    /**
+     * Returns the maximum amount of time that a nonce generated by the
+     * Guacamole server should remain valid, in minutes. As each OpenID request
+     * has a unique nonce value, this imposes an upper limit on the amount of
+     * time any particular OpenID request can result in successful
+     * authentication within Guacamole. By default, this will be 10.
+     *
+     * @return
+     *     The maximum amount of time that a nonce generated by the Guacamole
+     *     server should remain valid, in minutes.
+     *
+     * @throws GuacamoleException
+     *     If guacamole.properties cannot be parsed.
+     */
+    public int getMaxNonceValidity() throws GuacamoleException {
+        return environment.getProperty(OPENID_MAX_NONCE_VALIDITY, DEFAULT_MAX_NONCE_VALIDITY);
+    }
+
+    /**
+     * Returns the logout endpoint (URI) of the OpenID service, as configured
+     * with guacamole.properties. If configured, users will be redirected to
+     * this endpoint when they log out from Guacamole.
+     *
+     * @return
+     *     The logout endpoint of the OpenID service, as configured with
+     *     guacamole.properties, or null if not configured.
+     *
+     * @throws GuacamoleException
+     *     If guacamole.properties cannot be parsed.
+     */
+    public URI getLogoutEndpoint() throws GuacamoleException {
+        return environment.getProperty(OPENID_LOGOUT_ENDPOINT);
+    }
+
+    /**
+     * Returns the URI that the OpenID service should redirect to after logout
+     * is complete, as configured with guacamole.properties. If not configured,
+     * the main redirect URI will be used.
+     *
+     * @return
+     *     The post-logout redirect URI, as configured with
+     *     guacamole.properties, or the main redirect URI if not specified.
+     *
+     * @throws GuacamoleException
+     *     If guacamole.properties cannot be parsed.
+     */
+    public URI getPostLogoutRedirectURI() throws GuacamoleException {
+        return environment.getProperty(OPENID_POST_LOGOUT_REDIRECT_URI, getRedirectURI());
+    }
+
+}
@@ -27,7 +27,7 @@ import org.apache.guacamole.environment.LocalEnvironment;
 * configuration.
 */
 public class OpenIDEnvironment extends DelegatingEnvironment {
-
+    
    /**
     * Create a new instance of the configuration environment for the
     * OpenID SSO module, pulling the default instance of the LocalEnvironment.
@@ -35,5 +35,5 @@ public class OpenIDEnvironment extends DelegatingEnvironment {
    public OpenIDEnvironment() {
        super(LocalEnvironment.getInstance());
    }
-
+    
 }
@@ -35,7 +35,7 @@ import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
-import javax.servlet.http.HttpServletRequest;
+
 import javax.ws.rs.core.UriBuilder;
 import org.apache.guacamole.GuacamoleException;
 import org.apache.guacamole.auth.openid.conf.ConfigurationService;
@@ -191,7 +191,7 @@ public class TokenValidationService {

        return null;
    }
-
+    
    /**
     * URLEncodes a key/value pair
     *
@@ -297,7 +297,7 @@ public class TokenValidationService {
    /**
     * Parses the given JwtClaims, returning the username contained
     * therein, as defined by the username claim type given in
-     * guacamole.properties. If the username claim type is missing or
+     * guacamole.properties. If the username claim type is missing or 
     * is invalid, null is returned.
     *
     * @param claims
@@ -362,7 +362,7 @@ public class TokenValidationService {
                List<String> oidcGroups = claims.getStringListClaimValue(groupsClaim);
                if (oidcGroups != null && !oidcGroups.isEmpty())
                    return Collections.unmodifiableSet(new HashSet<>(oidcGroups));
-            }
+            }   
            catch (MalformedClaimException e) {
                logger.info("Rejected OpenID token with malformed claim: {}", e.getMessage());
                logger.debug("Malformed claim within received JWT.", e);
@@ -0,0 +1,430 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.guacamole.auth.openid.token;
+
+import com.google.inject.Inject;
+import java.io.BufferedReader;
+import java.io.OutputStream;
+import java.io.InputStreamReader;
+import java.net.HttpURLConnection;
+import java.net.URL;
+import java.net.URLEncoder;
+import java.net.URI;
+import java.nio.charset.StandardCharsets;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import javax.servlet.http.HttpServletRequest;
+import javax.ws.rs.core.UriBuilder;
+import org.apache.guacamole.GuacamoleException;
+import org.apache.guacamole.auth.openid.conf.ConfigurationService;
+import org.apache.guacamole.auth.sso.NonceService;
+import org.apache.guacamole.token.TokenName;
+import org.jose4j.json.JsonUtil;
+import org.jose4j.jwk.HttpsJwks;
+import org.jose4j.jwt.JwtClaims;
+import org.jose4j.jwt.MalformedClaimException;
+import org.jose4j.jwt.consumer.InvalidJwtException;
+import org.jose4j.jwt.consumer.JwtConsumer;
+import org.jose4j.jwt.consumer.JwtConsumerBuilder;
+import org.jose4j.keys.resolvers.HttpsJwksVerificationKeyResolver;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Service for validating ID tokens forwarded to us by the client, verifying
+ * that they did indeed come from the OpenID service.
+ */
+public class TokenValidationService {
+
+    /**
+     * Logger for this class.
+     */
+    private final Logger logger = LoggerFactory.getLogger(TokenValidationService.class);
+
+    /**
+     * The prefix to use when generating token names.
+     */
+    public static final String OIDC_ATTRIBUTE_TOKEN_PREFIX = "OIDC_";
+
+    /**
+     * Service for retrieving OpenID configuration information.
+     */
+    @Inject
+    private ConfigurationService confService;
+
+    /**
+     * Service for validating and generating unique nonce values.
+     */
+    @Inject
+    private NonceService nonceService;
+
+    /**
+     * Validates the given ID token, using implicit flow, returning the JwtClaims
+     * contained therein. If the ID token is invalid, null is returned.
+     *
+     * @param token
+     *     The ID token to validate.
+     *
+     * @return
+     *     The JWT claims contained within the given ID token if it passes tests,
+     *     or null if the token is not valid.
+     *
+     * @throws GuacamoleException
+     *     If guacamole.properties could not be parsed.
+     */
+    public JwtClaims validateToken(String token) throws GuacamoleException {
+        // Validating the token requires a JWKS key resolver
+        HttpsJwks jwks = new HttpsJwks(confService.getJWKSEndpoint().toString());
+        HttpsJwksVerificationKeyResolver resolver = new HttpsJwksVerificationKeyResolver(jwks);
+
+        // Create JWT consumer for validating received token
+        JwtConsumer jwtConsumer = new JwtConsumerBuilder()
+                .setRequireExpirationTime()
+                .setMaxFutureValidityInMinutes(confService.getMaxTokenValidity())
+                .setAllowedClockSkewInSeconds(confService.getAllowedClockSkew())
+                .setRequireSubject()
+                .setExpectedIssuer(confService.getIssuer())
+                .setExpectedAudience(confService.getClientID())
+                .setVerificationKeyResolver(resolver)
+                .build();
+
+        try {
+            // Validate JWT
+            JwtClaims claims = jwtConsumer.processToClaims(token);
+
+            // Verify a nonce is present
+            String nonce = claims.getStringClaimValue("nonce");
+            if (nonce != null) {
+                // Verify that we actually generated the nonce, and that it has not
+                // already been used
+                if (nonceService.isValid(nonce)) {
+                    // nonce is valid, consider claims valid
+                    return claims;
+                }
+                else {
+                    logger.info("Rejected OpenID token with invalid/old nonce.");
+                }
+            }
+            else {
+                logger.info("Rejected OpenID token without nonce.");
+            }
+        }
+        // Log any failures to validate/parse the JWT
+        catch (MalformedClaimException e) {
+            logger.info("Rejected OpenID token with malformed claim: {}", e.getMessage(), e);
+        }
+        catch (InvalidJwtException e) {
+            logger.info("Rejected invalid OpenID token: {}", e.getMessage(), e);
+        }
+
+        return null;
+    }
+
+    /**
+     * Validates the given ID token, using code flow, returning the JwtClaims
+     * contained therein. If the ID token is invalid, null is returned.
+     *
+     * @param code
+     *     The code to validate and receive the id_token.
+     *
+     * @param verifier
+     *     A PKCE verifier or null if not used.
+     *
+     * @return
+     *     The JWT claims contained within the given ID token if it passes tests,
+     *     or null if the token is not valid.
+     *
+     * @throws GuacamoleException
+     *     If guacamole.properties could not be parsed.
+     */
+    public JwtClaims validateCode(String code, String verifier) throws GuacamoleException {
+        // Validating the token requires a JWKS key resolver
+        HttpsJwks jwks = new HttpsJwks(confService.getJWKSEndpoint().toString());
+        HttpsJwksVerificationKeyResolver resolver = new HttpsJwksVerificationKeyResolver(jwks);
+
+        /* Exchange code → token */
+        String token = exchangeCode(code, verifier);
+
+        // Create JWT consumer for validating received token
+        JwtConsumer jwtConsumer = new JwtConsumerBuilder()
+                .setRequireExpirationTime()
+                .setMaxFutureValidityInMinutes(confService.getMaxTokenValidity())
+                .setAllowedClockSkewInSeconds(confService.getAllowedClockSkew())
+                .setRequireSubject()
+                .setExpectedIssuer(confService.getIssuer())
+                .setExpectedAudience(confService.getClientID())
+                .setVerificationKeyResolver(resolver)
+                .build();
+
+        try {
+            // Validate JWT
+            return jwtConsumer.processToClaims(token);
+        }
+        // Log any failures to validate/parse the JWT
+        catch (InvalidJwtException e) {
+            logger.info("Rejected invalid OpenID token: {}", e.getMessage(), e);
+        }
+
+        return null;
+    }
+
+    /**
+     * URLEncodes a key/value pair
+     *
+     * @param key
+     *     The key to encode
+     *
+     * @param value
+     *     The value to encode
+     *
+     * @return
+     *     The urlencoded kay/value pair
+     */
+     private String urlencode(String key, String value) {
+         StringBuilder builder = new StringBuilder();
+         return builder.append(URLEncoder.encode(key, StandardCharsets.UTF_8))
+                       .append("=")
+                       .append(URLEncoder.encode(value, StandardCharsets.UTF_8))
+                       .toString();
+     }
+
+    /**
+     * Exchanges the authorization code for tokens.
+     *
+     * @param code
+     *     The authorization code received from the IdP.
+     * @param codeVerifier
+     *     The PKCE verifier (or null if PKCE is disabled).
+     *
+     * @return
+     *     The token string returned.
+     *
+     * @throws GuacamoleException
+     *     If a valid token is not returned.
+     */
+    private String exchangeCode(String code, String verifier) throws GuacamoleException {
+
+        try {
+            StringBuilder bodyBuilder = new StringBuilder();
+            bodyBuilder.append(urlencode("grant_type", "authorization_code")).append("&");
+            bodyBuilder.append(urlencode("code", code)).append("&");
+            bodyBuilder.append(urlencode("redirect_uri", confService.getRedirectURI().toString())).append("&");
+            bodyBuilder.append(urlencode("scope", confService.getScope())).append("&");
+            bodyBuilder.append(urlencode("client_id", confService.getClientID()));
+
+            String clientSecret = confService.getClientSecret();
+            if (clientSecret != null && !clientSecret.trim().isEmpty()) {
+                bodyBuilder.append("&").append(urlencode("client_secret", clientSecret));
+            }
+
+            if (confService.isPKCERequired()) {
+                bodyBuilder.append("&").append(urlencode("code_verifier", verifier));
+            }
+
+            // Build the final URI and convert to a URL
+            URL url = confService.getTokenEndpoint().toURL();
+
+            // Open connection, using HttpURLConnection
+            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
+
+            conn.setRequestMethod("POST");
+            conn.setDoOutput(true);
+            conn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded; charset=UTF-8"
+            );
+
+            try (OutputStream out = conn.getOutputStream()) {
+                byte [] body = bodyBuilder.toString().getBytes(StandardCharsets.UTF_8);
+                out.write(body, 0, body.length);
+            }
+
+            // Read response
+            int status = conn.getResponseCode();
+
+            BufferedReader reader = new BufferedReader(
+                    new InputStreamReader(
+                            status >= 200 && status < 300
+                                    ? conn.getInputStream()
+                                    : conn.getErrorStream(),
+                            StandardCharsets.UTF_8
+                    )
+            );
+
+            StringBuilder responseBody = new StringBuilder();
+            String line;
+            while ((line = reader.readLine()) != null) {
+                responseBody.append(line);
+            }
+            reader.close();
+
+            Map<String,Object> json = JsonUtil.parseJson(responseBody.toString());
+
+            if (status < 200 || status >= 300) {
+                throw new GuacamoleException("Token endpoint error (" + status + "): " + json.toString());
+            }
+
+            return (String) json.get("id_token");
+
+        } catch (Exception e) {
+            logger.info("Rejected invalid OpenID code exchange: {}", e.getMessage(), e);
+        }
+        return null;
+    }
+
+    /**
+     * Parses the given JwtClaims, returning the username contained
+     * therein, as defined by the username claim type given in
+     * guacamole.properties. If the username claim type is missing or
+     * is invalid, null is returned.
+     *
+     * @param claims
+     *     A valid JwtClaims to extract the username from.
+     *
+     * @return
+     *     The username contained within the given JwtClaims, or null if the
+     *     claim is not valid or the username claim type is missing,
+     *
+     * @throws GuacamoleException
+     *     If guacamole.properties could not be parsed.
+     */
+    public String processUsername(JwtClaims claims) throws GuacamoleException {
+        String usernameClaim = confService.getUsernameClaimType();
+
+        if (claims != null) {
+            try {
+                // Pull username from claims
+                String username = claims.getStringClaimValue(usernameClaim);
+                if (username != null)
+                    return username;
+            }
+            catch (MalformedClaimException e) {
+                logger.info("Rejected OpenID token with malformed claim: {}", e.getMessage(), e);
+            }
+
+            // Warn if username was not present in token, as it likely means
+            // the system is not set up correctly
+            logger.warn("Username claim \"{}\" missing from token. Perhaps the "
+                    + "OpenID scope and/or username claim type are "
+                    + "misconfigured?", usernameClaim);
+        }
+
+        // Could not retrieve username from JWT
+        return null;
+    }
+
+    /**
+     * Parses the given JwtClaims, returning the groups contained
+     * therein, as defined by the groups claim type given in
+     * guacamole.properties. If the groups claim type is missing or
+     * is invalid, an empty set is returned.
+     *
+     * @param claims
+     *     A valid JwtClaims to extract groups from.
+     *
+     * @return
+     *     A Set of String representing the groups the user is member of
+     *     from the OpenID provider point of view, or an empty Set if
+     *     claim is not valid or the groups claim type is missing,
+     *
+     * @throws GuacamoleException
+     *     If guacamole.properties could not be parsed.
+     */
+    public Set<String> processGroups(JwtClaims claims) throws GuacamoleException {
+        String groupsClaim = confService.getGroupsClaimType();
+
+        if (claims != null) {
+            try {
+                // Pull groups from claims
+                List<String> oidcGroups = claims.getStringListClaimValue(groupsClaim);
+                if (oidcGroups != null && !oidcGroups.isEmpty())
+                    return Collections.unmodifiableSet(new HashSet<>(oidcGroups));
+            }
+            catch (MalformedClaimException e) {
+                logger.info("Rejected OpenID token with malformed claim: {}", e.getMessage(), e);
+            }
+        }
+
+        // Could not retrieve groups from JWT
+        return Collections.emptySet();
+    }
+
+    /**
+     * Parses the given JwtClaims, returning the attributes contained
+     * therein, as defined by the attributes claim type given in
+     * guacamole.properties. If the attributes claim type is missing or
+     * is invalid, an empty set is returned.
+     *
+     * @param claims
+     *     A valid JwtClaims to extract attributes from.
+     *
+     * @return
+     *     A Map of String,String representing the attributes and values
+     *     from the OpenID provider point of view, or an empty Map if
+     *     claim is not valid or the attributes claim type is missing.
+     *
+     * @throws GuacamoleException
+     *     If guacamole.properties could not be parsed.
+     */
+    public Map<String, String> processAttributes(JwtClaims claims) throws GuacamoleException {
+        Collection<String> attributesClaim = confService.getAttributesClaimType();
+
+        if (claims != null && !attributesClaim.isEmpty()) {
+            try {
+                logger.debug("Iterating over attributes claim list : {}", attributesClaim);
+
+                // We suppose all claims are resolved, so the hashmap is initialised to
+                // the size of the configuration list
+                Map<String, String> tokens = new HashMap<String, String>(attributesClaim.size());
+
+                // We iterate over the configured attributes
+                for (String key: attributesClaim) {
+                    // Retrieve the corresponding claim
+                    String oidcAttr = claims.getStringClaimValue(key);
+
+                    // We do have a matching claim and it is not empty
+                    if (oidcAttr != null && !oidcAttr.isEmpty()) {
+                        // append the prefixed claim value to the token map with its value
+                        String tokenName = TokenName.canonicalize(key, OIDC_ATTRIBUTE_TOKEN_PREFIX);
+                        tokens.put(tokenName, oidcAttr);
+                        logger.debug("Claim {} found and set to {}", key, tokenName);
+                    }
+                    else {
+                        // wanted attribute is not found in the claim
+                        logger.debug("Claim {} not found in JWT.", key);
+                    }
+                }
+
+                // We did process all the expected claims
+                return Collections.unmodifiableMap(tokens);
+            }
+            catch (MalformedClaimException e) {
+                logger.info("Rejected OpenID token with malformed claim: {}", e.getMessage(), e);
+            }
+        }
+
+        // Could not retrieve attributes from JWT
+        logger.debug("Attributes claim not defined. Returning empty map.");
+        return Collections.emptyMap();
+    }
+}