OIDC improvements in prep of OIDC-QR reciprocation (#4149)

* Add `device_authorization_endpoint` field to OIDC issuer well-known metadata

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

* Allow `validateIdToken` to skip handling nonce when none is present

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

* Tweak registerOidcClient to check OIDC grant_types_supported before registration

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

---------

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

spec/test-utils/oidc.ts

@@ -44,6 +44,7 @@ export const mockOpenIdConfiguration = (issuer = "https://auth.org/"): Validated
     token_endpoint: issuer + "token",
     authorization_endpoint: issuer + "auth",
     registration_endpoint: issuer + "registration",
+    device_authorization_endpoint: issuer + "device",
     jwks_uri: issuer + "jwks",
     response_types_supported: ["code"],
     grant_types_supported: ["authorization_code", "refresh_token"],

spec/unit/oidc/register.spec.ts

@@ -90,4 +90,31 @@ describe("registerOidcClient()", () => {
             OidcError.DynamicRegistrationInvalid,
         );
     });
+
+    it("should throw when required endpoints are unavailable", async () => {
+        await expect(() =>
+            registerOidcClient(
+                {
+                    ...delegatedAuthConfig,
+                    registrationEndpoint: undefined,
+                },
+                metadata,
+            ),
+        ).rejects.toThrow(OidcError.DynamicRegistrationNotSupported);
+    });
+
+    it("should throw when required scopes are unavailable", async () => {
+        await expect(() =>
+            registerOidcClient(
+                {
+                    ...delegatedAuthConfig,
+                    metadata: {
+                        ...delegatedAuthConfig.metadata,
+                        grant_types_supported: [delegatedAuthConfig.metadata.grant_types_supported[0]],
+                    },
+                },
+                metadata,
+            ),
+        ).rejects.toThrow(OidcError.DynamicRegistrationNotSupported);
+    });
 });

src/@types/oidc-client-ts.d.ts

@@ -0,0 +1,24 @@
+/*
+Copyright 2024 The Matrix.org Foundation C.I.C.
+
+Licensed 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.
+*/
+
+import "oidc-client-ts";
+
+declare module "oidc-client-ts" {
+    interface OidcMetadata {
+        // Add the missing device_authorization_endpoint field to the OidcMetadata interface
+        device_authorization_endpoint?: string;
+    }
+}

src/oidc/register.ts

@@ -50,23 +50,31 @@ interface OidcRegistrationRequestBody {
 }
 
 /**
- * Make the client registration request
- * @param registrationEndpoint - URL as returned from issuer ./well-known/openid-configuration
- * @param clientMetadata - registration metadata
- * @returns resolves to the registered client id when registration is successful
- * @throws An `Error` with `message` set to an entry in {@link OidcError},
- *      when the registration request fails, or the response is invalid.
+ * Attempts dynamic registration against the configured registration endpoint
+ * @param delegatedAuthConfig - Auth config from {@link discoverAndValidateOIDCIssuerWellKnown}
+ * @param clientMetadata - The metadata for the client which to register
+ * @returns Promise<string> resolved with registered clientId
+ * @throws when registration is not supported, on failed request or invalid response
  */
-const doRegistration = async (
-    registrationEndpoint: string,
+export const registerOidcClient = async (
+    delegatedAuthConfig: OidcClientConfig,
     clientMetadata: OidcRegistrationClientMetadata,
 ): Promise<string> => {
+    if (!delegatedAuthConfig.registrationEndpoint) {
+        throw new Error(OidcError.DynamicRegistrationNotSupported);
+    }
+
+    const grantTypes: NonEmptyArray<string> = ["authorization_code", "refresh_token"];
+    if (grantTypes.some((scope) => !delegatedAuthConfig.metadata.grant_types_supported.includes(scope))) {
+        throw new Error(OidcError.DynamicRegistrationNotSupported);
+    }
+
     // https://openid.net/specs/openid-connect-registration-1_0.html
     const metadata: OidcRegistrationRequestBody = {
         client_name: clientMetadata.clientName,
         client_uri: clientMetadata.clientUri,
         response_types: ["code"],
-        grant_types: ["authorization_code", "refresh_token"],
+        grant_types: grantTypes,
         redirect_uris: clientMetadata.redirectUris,
         id_token_signed_response_alg: "RS256",
         token_endpoint_auth_method: "none",
@@ -82,7 +90,7 @@ const doRegistration = async (
     };
 
     try {
-        const response = await fetch(registrationEndpoint, {
+        const response = await fetch(delegatedAuthConfig.registrationEndpoint, {
             method: Method.Post,
             headers,
             body: JSON.stringify(metadata),
@@ -108,20 +116,3 @@ const doRegistration = async (
         }
     }
 };
-
-/**
- * Attempts dynamic registration against the configured registration endpoint
- * @param delegatedAuthConfig - Auth config from {@link discoverAndValidateOIDCIssuerWellKnown}
- * @param clientMetadata - The metadata for the client which to register
- * @returns Promise<string> resolved with registered clientId
- * @throws when registration is not supported, on failed request or invalid response
- */
-export const registerOidcClient = async (
-    delegatedAuthConfig: OidcClientConfig,
-    clientMetadata: OidcRegistrationClientMetadata,
-): Promise<string> => {
-    if (!delegatedAuthConfig.registrationEndpoint) {
-        throw new Error(OidcError.DynamicRegistrationNotSupported);
-    }
-    return doRegistration(delegatedAuthConfig.registrationEndpoint, clientMetadata);
-};

src/oidc/validate.ts

@@ -83,6 +83,7 @@ export const validateOIDCIssuerWellKnown = (wellKnown: unknown): ValidatedIssuer
         requiredStringProperty(wellKnown, "revocation_endpoint"),
         optionalStringProperty(wellKnown, "registration_endpoint"),
         optionalStringProperty(wellKnown, "account_management_uri"),
+        optionalStringProperty(wellKnown, "device_authorization_endpoint"),
         optionalStringArrayProperty(wellKnown, "account_management_actions_supported"),
         requiredArrayValue(wellKnown, "response_types_supported", "code"),
         requiredArrayValue(wellKnown, "grant_types_supported", "authorization_code"),
@@ -118,6 +119,7 @@ export type ValidatedIssuerMetadata = Partial<OidcMetadata> &
         | "response_types_supported"
         | "grant_types_supported"
         | "code_challenge_methods_supported"
+        | "device_authorization_endpoint"
     > & {
         // MSC2965 extensions to the OIDC spec
         account_management_uri?: string;
@@ -176,7 +178,12 @@ const decodeIdToken = (token: string): IdTokenClaims => {
  * @param nonce - nonce used in the authentication request
  * @throws when id token is invalid
  */
-export const validateIdToken = (idToken: string | undefined, issuer: string, clientId: string, nonce: string): void => {
+export const validateIdToken = (
+    idToken: string | undefined,
+    issuer: string,
+    clientId: string,
+    nonce: string | undefined,
+): void => {
     try {
         if (!idToken) {
             throw new Error("No ID token");
@@ -201,7 +208,7 @@ export const validateIdToken = (idToken: string | undefined, issuer: string, cli
          * If a nonce value was sent in the Authentication Request, a nonce Claim MUST be present and its value checked
          * to verify that it is the same value as the one that was sent in the Authentication Request.
          */
-        if (claims.nonce !== nonce) {
+        if (nonce !== undefined && claims.nonce !== nonce) {
             throw new Error("Invalid nonce");
         }