fix(core): Webhooks responding with binary data should not prematurely end the response stream

Author: netroy

packages/cli/src/WebhookHelpers.ts

@@ -9,7 +9,7 @@
 import type express from 'express';
 import { Container } from 'typedi';
 import get from 'lodash/get';
-import { pipeline } from 'stream/promises';
+import { finished } from 'stream/promises';
 import formidable from 'formidable';
 
 import { BinaryDataService, NodeExecuteFunctions } from 'n8n-core';
@@ -30,6 +30,7 @@ import type {
 	IWebhookResponseData,
 	IWorkflowDataProxyAdditionalKeys,
 	IWorkflowExecuteAdditionalData,
+	WebhookResponseMode,
 	Workflow,
 	WorkflowExecuteMode,
 } from 'n8n-workflow';
@@ -272,7 +273,7 @@ export async function executeWebhook(
 		additionalKeys,
 		undefined,
 		'onReceived',
-	);
+	) as WebhookResponseMode;
 	const responseCode = workflow.expression.getSimpleParameterValue(
 		workflowStartNode,
 		webhookData.webhookDescription.responseCode as string,
@@ -291,7 +292,7 @@ export async function executeWebhook(
 		'firstEntryJson',
 	);
 
-	if (!['onReceived', 'lastNode', 'responseNode'].includes(responseMode as string)) {
+	if (!['onReceived', 'lastNode', 'responseNode'].includes(responseMode)) {
 		// If the mode is not known we error. Is probably best like that instead of using
 		// the default that people know as early as possible (probably already testing phase)
 		// that something does not resolve properly.
@@ -562,7 +563,8 @@ export async function executeWebhook(
 					if (binaryData?.id) {
 						res.header(response.headers);
 						const stream = await Container.get(BinaryDataService).getAsStream(binaryData.id);
-						await pipeline(stream, res);
+						stream.pipe(res, { end: false });
+						await finished(stream);
 						responseCallback(null, { noWebhookResponse: true });
 					} else if (Buffer.isBuffer(response.body)) {
 						res.header(response.headers);
@@ -595,6 +597,7 @@ export async function executeWebhook(
 						});
 					}
 
+					process.nextTick(() => res.end());
 					didSendResponse = true;
 				})
 				.catch(async (error) => {
@@ -659,17 +662,9 @@ export async function executeWebhook(
 						return data;
 					}
 
-					if (responseMode === 'responseNode') {
-						if (!didSendResponse) {
-							// Return an error if no Webhook-Response node did send any data
-							responseCallback(null, {
-								data: {
-									message: 'Workflow executed successfully',
-								},
-								responseCode,
-							});
-							didSendResponse = true;
-						}
+					// in `responseNode` mode `responseCallback` is called by `responsePromise`
+					if (responseMode === 'responseNode' && responsePromise) {
+						await Promise.allSettled([responsePromise.promise()]);
 						return undefined;
 					}
 
@@ -795,14 +790,16 @@ export async function executeWebhook(
 								res.setHeader('Content-Type', binaryData.mimeType);
 								if (binaryData.id) {
 									const stream = await Container.get(BinaryDataService).getAsStream(binaryData.id);
-									await pipeline(stream, res);
+									stream.pipe(res, { end: false });
+									await finished(stream);
 								} else {
-									res.end(Buffer.from(binaryData.data, BINARY_ENCODING));
+									res.write(Buffer.from(binaryData.data, BINARY_ENCODING));
 								}
 
 								responseCallback(null, {
 									noWebhookResponse: true,
 								});
+								process.nextTick(() => res.end());
 							}
 						} else if (responseData === 'noData') {
 							// Return without data

packages/workflow/src/Interfaces.ts

@@ -1834,7 +1834,7 @@ export interface IWebhookResponseData {
 }
 
 export type WebhookResponseData = 'allEntries' | 'firstEntryJson' | 'firstEntryBinary' | 'noData';
-export type WebhookResponseMode = 'onReceived' | 'lastNode';
+export type WebhookResponseMode = 'onReceived' | 'lastNode' | 'responseNode';
 
 export interface INodeTypes {
 	getByName(nodeType: string): INodeType | IVersionedNodeType;