feat(auth): Added code flow support for OIDC flow.

etc/firebase-admin.api.md

@@ -241,15 +241,23 @@ export namespace auth {
     export interface MultiFactorUpdateSettings {
         enrolledFactors: UpdateMultiFactorInfoRequest[] | null;
     }
+    export interface OAuthResponseType {
+        code?: boolean;
+        idToken?: boolean;
+    }
     export interface OIDCAuthProviderConfig extends AuthProviderConfig {
         clientId: string;
+        clientSecret?: string;
         issuer: string;
+        responseType?: OAuthResponseType;
     }
     export interface OIDCUpdateAuthProviderRequest {
         clientId?: string;
+        clientSecret?: string;
         displayName?: string;
         enabled?: boolean;
         issuer?: string;
+        responseType?: OAuthResponseType;
     }
     export interface PhoneIdentifier {
         // (undocumented)

src/auth/auth-config.ts

@@ -24,6 +24,7 @@ import MultiFactorConfigState = auth.MultiFactorConfigState;
 import AuthFactorType = auth.AuthFactorType;
 import EmailSignInProviderConfig = auth.EmailSignInProviderConfig;
 import OIDCAuthProviderConfig = auth.OIDCAuthProviderConfig;
+import OAuthResponseType = auth.OAuthResponseType;
 import SAMLAuthProviderConfig = auth.SAMLAuthProviderConfig;
 
 /** A maximum of 10 test phone number / code pairs can be configured. */
@@ -75,6 +76,8 @@ export interface OIDCConfigServerRequest {
   issuer?: string;
   displayName?: string;
   enabled?: boolean;
+  clientSecret?: string;
+  responseType?: OAuthResponseType;
   [key: string]: any;
 }
 
@@ -87,6 +90,8 @@ export interface OIDCConfigServerResponse {
   issuer?: string;
   displayName?: string;
   enabled?: boolean;
+  clientSecret?: string;
+  responseType?: OAuthResponseType;
 }
 
 /** The server side email configuration request interface. */
@@ -650,6 +655,8 @@ export class OIDCConfig implements OIDCAuthProviderConfig {
   public readonly providerId: string;
   public readonly issuer: string;
   public readonly clientId: string;
+  public readonly clientSecret?: string;
+  public readonly responseType: OAuthResponseType;
 
   /**
    * Converts a client side request to a OIDCConfigServerRequest which is the format
@@ -676,6 +683,12 @@ export class OIDCConfig implements OIDCAuthProviderConfig {
     request.displayName = options.displayName;
     request.issuer = options.issuer;
     request.clientId = options.clientId;
+    if (typeof options.clientSecret !== 'undefined') {
+      request.clientSecret = options.clientSecret;
+    }
+    if (typeof options.responseType !== 'undefined') {
+      request.responseType = options.responseType;
+    } 
     return request;
   }
 
@@ -715,6 +728,12 @@ export class OIDCConfig implements OIDCAuthProviderConfig {
       providerId: true,
       clientId: true,
       issuer: true,
+      clientSecret: true,
+      responseType: true,
+    };
+    const validResponseTypes = {
+      idToken: true,
+      code: true,
     };
     if (!validator.isNonNullObject(options)) {
       throw new FirebaseAuthError(
@@ -773,6 +792,59 @@ export class OIDCConfig implements OIDCAuthProviderConfig {
         '"OIDCAuthProviderConfig.displayName" must be a valid string.',
       );
     }
+    if (typeof options.clientSecret !== 'undefined' &&
+        !validator.isNonEmptyString(options.clientSecret)) {
+      throw new FirebaseAuthError(
+        AuthClientErrorCode.INVALID_CONFIG,
+        '"OIDCAuthProviderConfig.clientSecret" must be a valid string.',
+      );
+    }
+    if (validator.isNonNullObject(options.responseType) && typeof options.responseType !== 'undefined') {
+      Object.keys(options.responseType).forEach((key) => {
+        if (!(key in validResponseTypes)) {
+          throw new FirebaseAuthError(
+            AuthClientErrorCode.INVALID_CONFIG,
+            `"${key}" is not a valid OAuthResponseType parameter.`,
+          );          
+        }
+      });
+
+      const idToken = options.responseType.idToken;
+      if (typeof idToken !== 'undefined' && !validator.isBoolean(idToken)) { 
+        throw new FirebaseAuthError(
+          AuthClientErrorCode.INVALID_ARGUMENT,
+          '"OIDCAuthProviderConfig.responseType.idToken" must be a boolean.',
+        );
+      }
+
+      const code = options.responseType.code;
+      if (typeof code !== 'undefined') {
+        if (!validator.isBoolean(code)) {
+          throw new FirebaseAuthError(
+            AuthClientErrorCode.INVALID_ARGUMENT,
+            '"OIDCAuthProviderConfig.responseType.code" must be a boolean.',
+          );
+        }
+
+        // If code flow is enabled, client secret must be provided.
+        if (code && typeof options.clientSecret === 'undefined') {
+          throw new FirebaseAuthError(
+            AuthClientErrorCode.MISSING_OAUTH_CLIENT_SECRET,
+            'The OAuth configuration client secret is required to enable OIDC code flow.',
+          );          
+        }
+      }
+
+      const allKeys = Object.keys(options.responseType).length;
+      const enabledCount = Object.values(options.responseType).filter(Boolean).length;
+      // Only one of OAuth response types can be set to true.
+      if (allKeys > 1 && enabledCount != 1) {
+        throw new FirebaseAuthError(
+          AuthClientErrorCode.INVALID_OAUTH_RESPONSETYPE,
+          'Only exactly one OAuth responseType should be set to true.',
+        );
+      }
+    }
   }
 
   /**
@@ -806,6 +878,13 @@ export class OIDCConfig implements OIDCAuthProviderConfig {
     // When enabled is undefined, it takes its default value of false.
     this.enabled = !!response.enabled;
     this.displayName = response.displayName;
+
+    if (typeof response.clientSecret !== 'undefined') {
+      this.clientSecret = response.clientSecret;
+    }
+    if (typeof response.responseType !== 'undefined') {
+      this.responseType = response.responseType;
+    }
   }
 
   /** @return {OIDCAuthProviderConfig} The plain object representation of the OIDCConfig. */
@@ -816,6 +895,8 @@ export class OIDCConfig implements OIDCAuthProviderConfig {
       providerId: this.providerId,
       issuer: this.issuer,
       clientId: this.clientId,
+      clientSecret: deepCopy(this.clientSecret),
+      responseType: deepCopy(this.responseType),
     };
   }
 }

src/auth/index.ts

@@ -1289,6 +1289,25 @@ export namespace auth {
     callbackURL?: string;
   }
 
+  /**
+   * The interface representing OIDC provider's response object for OAuth
+   * authorization flow.
+   * We need either of them to be true, there are two cases:
+   * If set code to true, then we are doing code flow.
+   * If set idToken to true, then we are doing idToken flow.
+   */
+  export interface OAuthResponseType {
+    /**
+     * Whether ID token is returned from IdP's authorization endpoint.
+     */ 
+    idToken?: boolean;
+
+    /**
+     * Whether authorization code is returned from IdP's authorization endpoint.
+     */
+    code?: boolean;
+  }
+
   /**
    * The [OIDC](https://openid.net/specs/openid-connect-core-1_0-final.html) Auth
    * provider configuration interface. An OIDC provider can be created via
@@ -1321,6 +1340,16 @@ export namespace auth {
      * [spec](https://openid.net/specs/openid-connect-core-1_0.html#IDTokenValidation).
      */
     issuer: string;
+
+    /**
+     * The OIDC provider's client secret to enable OIDC code flow.
+     */
+    clientSecret?: string;
+
+    /**
+     * The OIDC provider's response object for OAuth authorization flow.
+     */
+    responseType?: OAuthResponseType;
   }
 
   /**
@@ -1403,6 +1432,17 @@ export namespace auth {
      * configuration's value is not modified.
      */
     issuer?: string;
+
+    /**
+     * The OIDC provider's client secret to enable OIDC code flow.
+     * If not provided, the existing configuration's value is not modified.
+     */
+    clientSecret?: string;
+
+    /**
+     * The OIDC provider's response object for OAuth authorization flow.
+     */
+    responseType?: OAuthResponseType;
   }
 
   /**

src/utils/error.ts

@@ -525,6 +525,10 @@ export class AuthClientErrorCode {
     code: 'invalid-provider-uid',
     message: 'The providerUid must be a valid provider uid string.',
   };
+  public static INVALID_OAUTH_RESPONSETYPE = {
+    code: 'invalid-oauth-responsetype',
+    message: 'Only exactly one OAuth responseType should be set to true.',
+  };
   public static INVALID_SESSION_COOKIE_DURATION = {
     code: 'invalid-session-cookie-duration',
     message: 'The session cookie duration must be a valid number in milliseconds ' +
@@ -597,6 +601,10 @@ export class AuthClientErrorCode {
     code: 'missing-oauth-client-id',
     message: 'The OAuth/OIDC configuration client ID must not be empty.',
   };
+  public static MISSING_OAUTH_CLIENT_SECRET = {
+    code: 'missing-oauth-client-secret',
+    message: 'The OAuth configuration client secret is required to enable OIDC code flow.',
+  };
   public static MISSING_PROVIDER_ID = {
     code: 'missing-provider-id',
     message: 'A valid provider ID must be provided in the request.',

test/integration/auth.spec.ts

@@ -1334,12 +1334,21 @@ describe('admin.auth', () => {
         enabled: true,
         issuer: 'https://oidc.com/issuer1',
         clientId: 'CLIENT_ID1',
+        responseType: {
+          idToken: true,
+          code: false,
+        },
       };
       const modifiedConfigOptions = {
         displayName: 'OIDC_DISPLAY_NAME3',
         enabled: false,
         issuer: 'https://oidc.com/issuer3',
         clientId: 'CLIENT_ID3',
+        clientSecret: 'CLIENT_SECRET',
+        responseType: {
+          idToken: false,
+          code: true,
+        },
       };
 
       before(function() {
@@ -1633,13 +1642,20 @@ describe('admin.auth', () => {
       enabled: true,
       issuer: 'https://oidc.com/issuer1',
       clientId: 'CLIENT_ID1',
+      responseType: {
+        idToken: true,
+      },
     };
     const authProviderConfig2 = {
       providerId: randomOidcProviderId(),
       displayName: 'OIDC_DISPLAY_NAME2',
       enabled: true,
       issuer: 'https://oidc.com/issuer2',
       clientId: 'CLIENT_ID2',
+      clientSecret: 'CLIENT_SECRET',
+      responseType: {
+        code: true,
+      },
     };
 
     const removeTempConfigs = (): Promise<any> => {
@@ -1706,39 +1722,65 @@ describe('admin.auth', () => {
         });
     });
 
-    it('updateProviderConfig() successfully overwrites an OIDC config', () => {
+    it('updateProviderConfig() successfully partially modifies an OIDC config', () => {
+      const deltaChanges = {
+        displayName: 'OIDC_DISPLAY_NAME3',
+        enabled: false,
+        issuer: 'https://oidc.com/issuer3',
+        clientId: 'CLIENT_ID3',
+        clientSecret: 'CLIENT_SECRET',
+        responseType: {
+          idToken: false,
+          code: true,
+        },
+      };
+      // Only above fields should be modified.
       const modifiedConfigOptions = {
+        providerId: authProviderConfig1.providerId,
         displayName: 'OIDC_DISPLAY_NAME3',
         enabled: false,
         issuer: 'https://oidc.com/issuer3',
         clientId: 'CLIENT_ID3',
+        clientSecret: 'CLIENT_SECRET',
+        responseType: {
+          code: true,
+        },
       };
-      return admin.auth().updateProviderConfig(authProviderConfig1.providerId, modifiedConfigOptions)
+      return admin.auth().updateProviderConfig(authProviderConfig1.providerId, deltaChanges)
         .then((config) => {
-          const modifiedConfig = deepExtend(
-            { providerId: authProviderConfig1.providerId }, modifiedConfigOptions);
-          assertDeepEqualUnordered(modifiedConfig, config);
+          assertDeepEqualUnordered(modifiedConfigOptions, config);
         });
     });
 
-    it('updateProviderConfig() successfully partially modifies an OIDC config', () => {
+    it('updateProviderConfig() with invalid oauth response type should be rejected', () => {
       const deltaChanges = {
         displayName: 'OIDC_DISPLAY_NAME4',
+        enabled: false,
         issuer: 'https://oidc.com/issuer4',
+        clientId: 'CLIENT_ID4',
+        clientSecret: 'CLIENT_SECRET',
+        responseType: {
+          idToken: false,
+          code: false,
+        },
       };
-      // Only above fields should be modified.
-      const modifiedConfigOptions = {
-        displayName: 'OIDC_DISPLAY_NAME4',
+      return admin.auth().updateProviderConfig(authProviderConfig1.providerId, deltaChanges).
+        should.eventually.be.rejected.and.have.property('code', 'auth/invalid-oauth-responsetype');
+    });
+
+    it('updateProviderConfig() code flow with no client secret should be rejected', () => {
+      const deltaChanges = {
+        displayName: 'OIDC_DISPLAY_NAME5',
         enabled: false,
-        issuer: 'https://oidc.com/issuer4',
-        clientId: 'CLIENT_ID3',
+        issuer: 'https://oidc.com/issuer5',
+        clientId: 'CLIENT_ID5',
+        responseType: {
+          idToken: false,
+          code: true,
+        },
       };
-      return admin.auth().updateProviderConfig(authProviderConfig1.providerId, deltaChanges)
-        .then((config) => {
-          const modifiedConfig = deepExtend(
-            { providerId: authProviderConfig1.providerId }, modifiedConfigOptions);
-          assertDeepEqualUnordered(modifiedConfig, config);
-        });
+      return admin.auth().updateProviderConfig(authProviderConfig1.providerId, deltaChanges).
+        should.eventually.be.rejected.and.have.property('code', 'auth/missing-oauth-client-secret');
     });
 
     it('deleteProviderConfig() successfully deletes an existing OIDC config', () => {