OIDC: add dynamic client registration util function (#3481)

* rename OidcDiscoveryError to OidcError

* oidc client registration functions

* test registerOidcClient

* tidy test file

* reexport OidcDiscoveryError for backwards compatibility

spec/unit/autodiscovery.spec.ts

@@ -18,7 +18,7 @@ limitations under the License.
 import MockHttpBackend from "matrix-mock-request";
 
 import { AutoDiscovery } from "../../src/autodiscovery";
-import { OidcDiscoveryError } from "../../src/oidc/validate";
+import { OidcError } from "../../src/oidc/error";
 
 describe("AutoDiscovery", function () {
     const getHttpBackend = (): MockHttpBackend => {
@@ -400,7 +400,7 @@ describe("AutoDiscovery", function () {
                     },
                     "m.authentication": {
                         state: "IGNORE",
-                        error: OidcDiscoveryError.NotSupported,
+                        error: OidcError.NotSupported,
                     },
                 };
 
@@ -441,7 +441,7 @@ describe("AutoDiscovery", function () {
                     },
                     "m.authentication": {
                         state: "IGNORE",
-                        error: OidcDiscoveryError.NotSupported,
+                        error: OidcError.NotSupported,
                     },
                 };
 
@@ -485,7 +485,7 @@ describe("AutoDiscovery", function () {
                     },
                     "m.authentication": {
                         state: "FAIL_ERROR",
-                        error: OidcDiscoveryError.Misconfigured,
+                        error: OidcError.Misconfigured,
                     },
                 };
 
@@ -719,7 +719,7 @@ describe("AutoDiscovery", function () {
                     },
                     "m.authentication": {
                         state: "IGNORE",
-                        error: OidcDiscoveryError.NotSupported,
+                        error: OidcError.NotSupported,
                     },
                 };
 
@@ -775,7 +775,7 @@ describe("AutoDiscovery", function () {
                     },
                     "m.authentication": {
                         state: "IGNORE",
-                        error: OidcDiscoveryError.NotSupported,
+                        error: OidcError.NotSupported,
                     },
                 };
 

spec/unit/oidc/register.spec.ts

@@ -0,0 +1,84 @@
+/*
+Copyright 2023 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 fetchMockJest from "fetch-mock-jest";
+
+import { OidcError } from "../../../src/oidc/error";
+import { registerOidcClient } from "../../../src/oidc/register";
+
+describe("registerOidcClient()", () => {
+    const issuer = "https://auth.com/";
+    const registrationEndpoint = "https://auth.com/register";
+    const clientName = "Element";
+    const baseUrl = "https://just.testing";
+    const dynamicClientId = "xyz789";
+
+    const delegatedAuthConfig = {
+        issuer,
+        registrationEndpoint,
+        authorizationEndpoint: issuer + "auth",
+        tokenEndpoint: issuer + "token",
+    };
+    beforeEach(() => {
+        fetchMockJest.mockClear();
+        fetchMockJest.resetBehavior();
+    });
+
+    it("should make correct request to register client", async () => {
+        fetchMockJest.post(registrationEndpoint, {
+            status: 200,
+            body: JSON.stringify({ client_id: dynamicClientId }),
+        });
+        expect(await registerOidcClient(delegatedAuthConfig, clientName, baseUrl)).toEqual(dynamicClientId);
+        expect(fetchMockJest).toHaveBeenCalledWith(registrationEndpoint, {
+            headers: {
+                "Accept": "application/json",
+                "Content-Type": "application/json",
+            },
+            method: "POST",
+            body: JSON.stringify({
+                client_name: clientName,
+                client_uri: baseUrl,
+                response_types: ["code"],
+                grant_types: ["authorization_code", "refresh_token"],
+                redirect_uris: [baseUrl],
+                id_token_signed_response_alg: "RS256",
+                token_endpoint_auth_method: "none",
+                application_type: "web",
+            }),
+        });
+    });
+
+    it("should throw when registration request fails", async () => {
+        fetchMockJest.post(registrationEndpoint, {
+            status: 500,
+        });
+        expect(() => registerOidcClient(delegatedAuthConfig, clientName, baseUrl)).rejects.toThrow(
+            OidcError.DynamicRegistrationFailed,
+        );
+    });
+
+    it("should throw when registration response is invalid", async () => {
+        fetchMockJest.post(registrationEndpoint, {
+            status: 200,
+            // no clientId in response
+            body: "{}",
+        });
+        expect(() => registerOidcClient(delegatedAuthConfig, clientName, baseUrl)).rejects.toThrow(
+            OidcError.DynamicRegistrationInvalid,
+        );
+    });
+});

spec/unit/oidc/validate.spec.ts

@@ -16,11 +16,8 @@ limitations under the License.
 
 import { M_AUTHENTICATION } from "../../../src";
 import { logger } from "../../../src/logger";
-import {
-    OidcDiscoveryError,
-    validateOIDCIssuerWellKnown,
-    validateWellKnownAuthentication,
-} from "../../../src/oidc/validate";
+import { validateOIDCIssuerWellKnown, validateWellKnownAuthentication } from "../../../src/oidc/validate";
+import { OidcError } from "../../../src/oidc/error";
 
 describe("validateWellKnownAuthentication()", () => {
     const baseWk = {
@@ -29,7 +26,7 @@ describe("validateWellKnownAuthentication()", () => {
         },
     };
     it("should throw not supported error when wellKnown has no m.authentication section", () => {
-        expect(() => validateWellKnownAuthentication(baseWk)).toThrow(OidcDiscoveryError.NotSupported);
+        expect(() => validateWellKnownAuthentication(baseWk)).toThrow(OidcError.NotSupported);
     });
 
     it("should throw misconfigured error when authentication issuer is not a string", () => {
@@ -39,7 +36,7 @@ describe("validateWellKnownAuthentication()", () => {
                 issuer: { url: "test.com" },
             },
         };
-        expect(() => validateWellKnownAuthentication(wk)).toThrow(OidcDiscoveryError.Misconfigured);
+        expect(() => validateWellKnownAuthentication(wk)).toThrow(OidcError.Misconfigured);
     });
 
     it("should throw misconfigured error when authentication account is not a string", () => {
@@ -50,7 +47,7 @@ describe("validateWellKnownAuthentication()", () => {
                 account: { url: "test" },
             },
         };
-        expect(() => validateWellKnownAuthentication(wk)).toThrow(OidcDiscoveryError.Misconfigured);
+        expect(() => validateWellKnownAuthentication(wk)).toThrow(OidcError.Misconfigured);
     });
 
     it("should throw misconfigured error when authentication account is false", () => {
@@ -61,7 +58,7 @@ describe("validateWellKnownAuthentication()", () => {
                 account: false,
             },
         };
-        expect(() => validateWellKnownAuthentication(wk)).toThrow(OidcDiscoveryError.Misconfigured);
+        expect(() => validateWellKnownAuthentication(wk)).toThrow(OidcError.Misconfigured);
     });
 
     it("should return valid config when wk uses stable m.authentication", () => {
@@ -137,7 +134,7 @@ describe("validateOIDCIssuerWellKnown", () => {
     it("should throw OP support error when wellKnown is not an object", () => {
         expect(() => {
             validateOIDCIssuerWellKnown([]);
-        }).toThrow(OidcDiscoveryError.OpSupport);
+        }).toThrow(OidcError.OpSupport);
         expect(logger.error).toHaveBeenCalledWith("Issuer configuration not found or malformed");
     });
 
@@ -148,7 +145,7 @@ describe("validateOIDCIssuerWellKnown", () => {
                 authorization_endpoint: undefined,
                 response_types_supported: [],
             });
-        }).toThrow(OidcDiscoveryError.OpSupport);
+        }).toThrow(OidcError.OpSupport);
         expect(logger.error).toHaveBeenCalledWith("OIDC issuer configuration: authorization_endpoint is invalid");
         expect(logger.error).toHaveBeenCalledWith(
             "OIDC issuer configuration: response_types_supported is invalid. code is required.",
@@ -194,6 +191,6 @@ describe("validateOIDCIssuerWellKnown", () => {
             ...validWk,
             [key]: value,
         };
-        expect(() => validateOIDCIssuerWellKnown(wk)).toThrow(OidcDiscoveryError.OpSupport);
+        expect(() => validateOIDCIssuerWellKnown(wk)).toThrow(OidcError.OpSupport);
     });
 });

src/autodiscovery.ts

@@ -18,12 +18,8 @@ limitations under the License.
 import { IClientWellKnown, IWellKnownConfig, IDelegatedAuthConfig, IServerVersions, M_AUTHENTICATION } from "./client";
 import { logger } from "./logger";
 import { MatrixError, Method, timeoutSignal } from "./http-api";
-import {
-    OidcDiscoveryError,
-    ValidatedIssuerConfig,
-    validateOIDCIssuerWellKnown,
-    validateWellKnownAuthentication,
-} from "./oidc/validate";
+import { ValidatedIssuerConfig, validateOIDCIssuerWellKnown, validateWellKnownAuthentication } from "./oidc/validate";
+import { OidcError } from "./oidc/error";
 
 // Dev note: Auto discovery is part of the spec.
 // See: https://matrix.org/docs/spec/client_server/r0.4.0.html#server-discovery
@@ -297,7 +293,7 @@ export class AutoDiscovery {
 
             if (issuerWellKnown.action !== AutoDiscoveryAction.SUCCESS) {
                 logger.error("Failed to fetch issuer openid configuration");
-                throw new Error(OidcDiscoveryError.General);
+                throw new Error(OidcError.General);
             }
 
             const validatedIssuerConfig = validateOIDCIssuerWellKnown(issuerWellKnown.raw);
@@ -310,15 +306,11 @@ export class AutoDiscovery {
             };
             return delegatedAuthConfig;
         } catch (error) {
-            const errorMessage = (error as Error).message as unknown as OidcDiscoveryError;
-            const errorType = Object.values(OidcDiscoveryError).includes(errorMessage)
-                ? errorMessage
-                : OidcDiscoveryError.General;
+            const errorMessage = (error as Error).message as unknown as OidcError;
+            const errorType = Object.values(OidcError).includes(errorMessage) ? errorMessage : OidcError.General;
 
             const state =
-                errorType === OidcDiscoveryError.NotSupported
-                    ? AutoDiscoveryAction.IGNORE
-                    : AutoDiscoveryAction.FAIL_ERROR;
+                errorType === OidcError.NotSupported ? AutoDiscoveryAction.IGNORE : AutoDiscoveryAction.FAIL_ERROR;
 
             return {
                 state,

src/oidc/error.ts

@@ -0,0 +1,25 @@
+/*
+Copyright 2023 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.
+*/
+
+export enum OidcError {
+    NotSupported = "OIDC authentication not supported",
+    Misconfigured = "OIDC is misconfigured",
+    General = "Something went wrong with OIDC discovery",
+    OpSupport = "Configured OIDC OP does not support required functions",
+    DynamicRegistrationNotSupported = "Dynamic registration not supported",
+    DynamicRegistrationFailed = "Dynamic registration failed",
+    DynamicRegistrationInvalid = "Dynamic registration invalid response",
+}

src/oidc/register.ts

@@ -0,0 +1,111 @@
+/*
+Copyright 2023 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 { IDelegatedAuthConfig } from "../client";
+import { OidcError } from "./error";
+import { Method } from "../http-api";
+import { logger } from "../logger";
+import { ValidatedIssuerConfig } from "./validate";
+
+/**
+ * Client metadata passed to registration endpoint
+ */
+export type OidcRegistrationClientMetadata = {
+    clientName: string;
+    clientUri: string;
+    redirectUris: string[];
+};
+
+/**
+ * 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 when registration request fails, or response is invalid
+ */
+const doRegistration = async (
+    registrationEndpoint: string,
+    clientMetadata: OidcRegistrationClientMetadata,
+): Promise<string> => {
+    // https://openid.net/specs/openid-connect-registration-1_0.html
+    const metadata = {
+        client_name: clientMetadata.clientName,
+        client_uri: clientMetadata.clientUri,
+        response_types: ["code"],
+        grant_types: ["authorization_code", "refresh_token"],
+        redirect_uris: clientMetadata.redirectUris,
+        id_token_signed_response_alg: "RS256",
+        token_endpoint_auth_method: "none",
+        application_type: "web",
+    };
+    const headers = {
+        "Accept": "application/json",
+        "Content-Type": "application/json",
+    };
+
+    try {
+        const response = await fetch(registrationEndpoint, {
+            method: Method.Post,
+            headers,
+            body: JSON.stringify(metadata),
+        });
+
+        if (response.status >= 400) {
+            throw new Error(OidcError.DynamicRegistrationFailed);
+        }
+
+        const body = await response.json();
+        const clientId = body["client_id"];
+        if (!clientId || typeof clientId !== "string") {
+            throw new Error(OidcError.DynamicRegistrationInvalid);
+        }
+
+        return clientId;
+    } catch (error) {
+        if (Object.values(OidcError).includes((error as Error).message as OidcError)) {
+            throw error;
+        } else {
+            logger.error("Dynamic registration request failed", error);
+            throw new Error(OidcError.DynamicRegistrationFailed);
+        }
+    }
+};
+
+/**
+ * Attempts dynamic registration against the configured registration endpoint
+ * @param delegatedAuthConfig - Auth config from ValidatedServerConfig
+ * @param clientName - Client name to register with the OP, eg 'Element'
+ * @param baseUrl - URL of the home page of the Client, eg 'https://app.element.io/'
+ * @returns Promise<string> resolved with registered clientId
+ * @throws when registration is not supported, on failed request or invalid response
+ */
+export const registerOidcClient = async (
+    delegatedAuthConfig: IDelegatedAuthConfig & ValidatedIssuerConfig,
+    clientName: string,
+    baseUrl: string,
+): Promise<string> => {
+    const clientMetadata = {
+        clientName,
+        clientUri: baseUrl,
+        redirectUris: [baseUrl],
+    };
+    if (!delegatedAuthConfig.registrationEndpoint) {
+        throw new Error(OidcError.DynamicRegistrationNotSupported);
+    }
+    const clientId = await doRegistration(delegatedAuthConfig.registrationEndpoint, clientMetadata);
+
+    return clientId;
+};

src/oidc/validate.ts

@@ -16,13 +16,13 @@ limitations under the License.
 
 import { IClientWellKnown, IDelegatedAuthConfig, M_AUTHENTICATION } from "../client";
 import { logger } from "../logger";
+import { OidcError } from "./error";
 
-export enum OidcDiscoveryError {
-    NotSupported = "OIDC authentication not supported",
-    Misconfigured = "OIDC is misconfigured",
-    General = "Something went wrong with OIDC discovery",
-    OpSupport = "Configured OIDC OP does not support required functions",
-}
+/**
+ * re-export for backwards compatibility
+ * @deprecated use OidcError
+ */
+export { OidcError as OidcDiscoveryError };
 
 export type ValidatedIssuerConfig = {
     authorizationEndpoint: string;
@@ -41,7 +41,7 @@ export const validateWellKnownAuthentication = (wellKnown: IClientWellKnown): ID
     const authentication = M_AUTHENTICATION.findIn<IDelegatedAuthConfig>(wellKnown);
 
     if (!authentication) {
-        throw new Error(OidcDiscoveryError.NotSupported);
+        throw new Error(OidcError.NotSupported);
     }
 
     if (
@@ -54,7 +54,7 @@ export const validateWellKnownAuthentication = (wellKnown: IClientWellKnown): ID
         };
     }
 
-    throw new Error(OidcDiscoveryError.Misconfigured);
+    throw new Error(OidcError.Misconfigured);
 };
 
 const isRecord = (value: unknown): value is Record<string, unknown> =>
@@ -93,7 +93,7 @@ const requiredArrayValue = (wellKnown: Record<string, unknown>, key: string, val
 export const validateOIDCIssuerWellKnown = (wellKnown: unknown): ValidatedIssuerConfig => {
     if (!isRecord(wellKnown)) {
         logger.error("Issuer configuration not found or malformed");
-        throw new Error(OidcDiscoveryError.OpSupport);
+        throw new Error(OidcError.OpSupport);
     }
 
     const isInvalid = [
@@ -114,5 +114,5 @@ export const validateOIDCIssuerWellKnown = (wellKnown: unknown): ValidatedIssuer
     }
 
     logger.error("Issuer configuration not valid");
-    throw new Error(OidcDiscoveryError.OpSupport);
+    throw new Error(OidcError.OpSupport);
 };