fix(core): Do not add Authentication header when authentication type is body (#8201)

packages/@n8n/client-oauth2/src/ClientOAuth2.ts

@@ -1,6 +1,5 @@
 /* eslint-disable @typescript-eslint/no-unsafe-return */
 /* eslint-disable @typescript-eslint/no-unsafe-argument */
-
 /* eslint-disable @typescript-eslint/no-explicit-any */
 import * as qs from 'querystring';
 import { Agent } from 'https';
@@ -26,6 +25,7 @@ export interface ClientOAuth2Options {
 	clientId: string;
 	clientSecret?: string;
 	accessTokenUri: string;
+	authentication?: 'header' | 'body';
 	authorizationUri?: string;
 	redirectUri?: string;
 	scopes?: string[];

packages/@n8n/client-oauth2/src/CredentialsFlow.ts

@@ -1,9 +1,12 @@
-import type { ClientOAuth2, ClientOAuth2Options } from './ClientOAuth2';
+import type { ClientOAuth2 } from './ClientOAuth2';
 import type { ClientOAuth2Token, ClientOAuth2TokenData } from './ClientOAuth2Token';
 import { DEFAULT_HEADERS } from './constants';
+import type { Headers } from './types';
 import { auth, expects, getRequestOptions } from './utils';
 
 interface CredentialsFlowBody {
+	client_id?: string;
+	client_secret?: string;
 	grant_type: 'client_credentials';
 	scope?: string;
 }
@@ -19,10 +22,11 @@ export class CredentialsFlow {
 	/**
 	 * Request an access token using the client credentials.
 	 */
-	async getToken(opts?: Partial<ClientOAuth2Options>): Promise<ClientOAuth2Token> {
-		const options = { ...this.client.options, ...opts };
+	async getToken(): Promise<ClientOAuth2Token> {
+		const options = { ...this.client.options };
 		expects(options, 'clientId', 'clientSecret', 'accessTokenUri');
 
+		const headers: Headers = { ...DEFAULT_HEADERS };
 		const body: CredentialsFlowBody = {
 			grant_type: 'client_credentials',
 		};
@@ -31,15 +35,21 @@ export class CredentialsFlow {
 			body.scope = options.scopes.join(options.scopesSeparator ?? ' ');
 		}
 
+		const clientId = options.clientId;
+		const clientSecret = options.clientSecret;
+
+		if (options.authentication === 'body') {
+			body.client_id = clientId;
+			body.client_secret = clientSecret;
+		} else {
+			headers.Authorization = auth(clientId, clientSecret);
+		}
+
 		const requestOptions = getRequestOptions(
 			{
 				url: options.accessTokenUri,
 				method: 'POST',
-				headers: {
-					...DEFAULT_HEADERS,
-					// eslint-disable-next-line @typescript-eslint/naming-convention
-					Authorization: auth(options.clientId, options.clientSecret),
-				},
+				headers,
 				body,
 			},
 			options,

packages/@n8n/client-oauth2/src/index.ts

@@ -1,2 +1,3 @@
 export { ClientOAuth2, ClientOAuth2Options, ClientOAuth2RequestObject } from './ClientOAuth2';
 export { ClientOAuth2Token, ClientOAuth2TokenData } from './ClientOAuth2Token';
+export type * from './types';

packages/@n8n/client-oauth2/src/types.ts

@@ -1 +1,19 @@
 export type Headers = Record<string, string | string[]>;
+
+export type OAuth2GrantType = 'pkce' | 'authorizationCode' | 'clientCredentials';
+
+export interface OAuth2CredentialData {
+	clientId: string;
+	clientSecret?: string;
+	accessTokenUrl: string;
+	authentication?: 'header' | 'body';
+	authUrl?: string;
+	scope?: string;
+	authQueryParameters?: string;
+	grantType: OAuth2GrantType;
+	ignoreSSLIssues?: boolean;
+	oauthTokenData?: {
+		access_token: string;
+		refresh_token?: string;
+	};
+}

packages/@n8n/client-oauth2/test/CredentialsFlow.test.ts

@@ -1,4 +1,6 @@
 import nock from 'nock';
+import type { Headers } from '../src/types';
+import type { ClientOAuth2Options } from '../src';
 import { ClientOAuth2, ClientOAuth2Token } from '../src';
 import * as config from './config';
 
@@ -11,18 +13,24 @@ describe('CredentialsFlow', () => {
 		nock.restore();
 	});
 
+	beforeEach(() => jest.clearAllMocks());
+
 	describe('#getToken', () => {
-		const createAuthClient = (scopes?: string[]) =>
+		const createAuthClient = ({
+			scopes,
+			authentication,
+		}: Pick<ClientOAuth2Options, 'scopes' | 'authentication'> = {}) =>
 			new ClientOAuth2({
 				clientId: config.clientId,
 				clientSecret: config.clientSecret,
 				accessTokenUri: config.accessTokenUri,
+				authentication,
 				authorizationGrants: ['credentials'],
 				scopes,
 			});
 
-		const mockTokenCall = (requestedScope?: string) =>
-			nock(config.baseUrl)
+		const mockTokenCall = async ({ requestedScope }: { requestedScope?: string } = {}) => {
+			const nockScope = nock(config.baseUrl)
 				.post(
 					'/login/oauth/access_token',
 					({ scope, grant_type }) =>
@@ -34,10 +42,19 @@ describe('CredentialsFlow', () => {
 					refresh_token: config.refreshToken,
 					scope: requestedScope,
 				});
+			return new Promise<{ headers: Headers; body: unknown }>((resolve) => {
+				nockScope.once('request', (req) => {
+					resolve({
+						headers: req.headers,
+						body: req.requestBodyBuffers.toString('utf-8'),
+					});
+				});
+			});
+		};
 
 		it('should request the token', async () => {
-			const authClient = createAuthClient(['notifications']);
-			mockTokenCall('notifications');
+			const authClient = createAuthClient({ scopes: ['notifications'] });
+			const requestPromise = mockTokenCall({ requestedScope: 'notifications' });
 
 			const user = await authClient.credentials.getToken();
 
@@ -45,34 +62,62 @@ describe('CredentialsFlow', () => {
 			expect(user.accessToken).toEqual(config.accessToken);
 			expect(user.tokenType).toEqual('bearer');
 			expect(user.data.scope).toEqual('notifications');
+
+			const { headers, body } = await requestPromise;
+			expect(headers.authorization).toBe('Basic YWJjOjEyMw==');
+			expect(body).toEqual('grant_type=client_credentials&scope=notifications');
 		});
 
 		it('when scopes are undefined, it should not send scopes to an auth server', async () => {
 			const authClient = createAuthClient();
-			mockTokenCall();
+			const requestPromise = mockTokenCall();
 
 			const user = await authClient.credentials.getToken();
 			expect(user).toBeInstanceOf(ClientOAuth2Token);
 			expect(user.accessToken).toEqual(config.accessToken);
 			expect(user.tokenType).toEqual('bearer');
 			expect(user.data.scope).toEqual(undefined);
+
+			const { body } = await requestPromise;
+			expect(body).toEqual('grant_type=client_credentials');
 		});
 
 		it('when scopes is an empty array, it should send empty scope string to an auth server', async () => {
-			const authClient = createAuthClient([]);
-			mockTokenCall('');
+			const authClient = createAuthClient({ scopes: [] });
+			const requestPromise = mockTokenCall({ requestedScope: '' });
 
 			const user = await authClient.credentials.getToken();
 			expect(user).toBeInstanceOf(ClientOAuth2Token);
 			expect(user.accessToken).toEqual(config.accessToken);
 			expect(user.tokenType).toEqual('bearer');
 			expect(user.data.scope).toEqual('');
+
+			const { body } = await requestPromise;
+			expect(body).toEqual('grant_type=client_credentials&scope=');
+		});
+
+		it('should handle authentication = "header"', async () => {
+			const authClient = createAuthClient({ scopes: [] });
+			const requestPromise = mockTokenCall({ requestedScope: '' });
+			await authClient.credentials.getToken();
+			const { headers, body } = await requestPromise;
+			expect(headers?.authorization).toBe('Basic YWJjOjEyMw==');
+			expect(body).toEqual('grant_type=client_credentials&scope=');
+		});
+
+		it('should handle authentication = "body"', async () => {
+			const authClient = createAuthClient({ scopes: [], authentication: 'body' });
+			const requestPromise = mockTokenCall({ requestedScope: '' });
+			await authClient.credentials.getToken();
+			const { headers, body } = await requestPromise;
+			expect(headers?.authorization).toBe(undefined);
+			expect(body).toEqual('grant_type=client_credentials&scope=&client_id=abc&client_secret=123');
 		});
 
 		describe('#sign', () => {
 			it('should be able to sign a standard request object', async () => {
-				const authClient = createAuthClient(['notifications']);
-				mockTokenCall('notifications');
+				const authClient = createAuthClient({ scopes: ['notifications'] });
+				void mockTokenCall({ requestedScope: 'notifications' });
 
 				const token = await authClient.credentials.getToken();
 				const requestOptions = token.sign({
@@ -99,8 +144,8 @@ describe('CredentialsFlow', () => {
 					});
 
 			it('should make a request to get a new access token', async () => {
-				const authClient = createAuthClient(['notifications']);
-				mockTokenCall('notifications');
+				const authClient = createAuthClient({ scopes: ['notifications'] });
+				void mockTokenCall({ requestedScope: 'notifications' });
 
 				const token = await authClient.credentials.getToken();
 				expect(token.accessToken).toEqual(config.accessToken);