fix: improve compatibility of Google Cloud Functions, req.body is t…

…he parsed JSON payload (#937)

src/middleware/node/get-payload.ts

@@ -12,11 +12,21 @@ import AggregateError from "aggregate-error";
 type IncomingMessage = any;
 
 export function getPayload(request: IncomingMessage): Promise<string> {
-  // If request.body already exists we can stop here
-  // See https://github.com/octokit/webhooks.js/pull/23
-
-  if (request.body) return Promise.resolve(request.body);
+  if ("body" in request) {
+    if (
+      typeof request.body === "object" &&
+      "rawBody" in request &&
+      request.rawBody instanceof Buffer
+    ) {
+      // The body is already an Object and rawBody is a Buffer (e.g. GCF)
+      return Promise.resolve(request.rawBody.toString("utf8"));
+    } else {
+      // The body is a String (e.g. Lambda)
+      return Promise.resolve(request.body);
+    }
+  }
 
+  // We need to load the payload from the request (normal case of Node.js server)
   return new Promise((resolve, reject) => {
     let data: Buffer[] = [];
 

test/integration/node-middleware.test.ts

@@ -654,3 +654,47 @@ describe("createNodeMiddleware(webhooks)", () => {
     server.close();
   });
 });
+
+test("request.body is already an Object and has request.rawBody as Buffer (e.g. GCF)", async () => {
+  expect.assertions(3);
+
+  const webhooks = new Webhooks({
+    secret: "mySecret",
+  });
+  const dataChunks: any[] = [];
+  const middleware = createNodeMiddleware(webhooks);
+
+  const server = createServer((req, res) => {
+    req.once("data", (chunk) => dataChunks.push(chunk));
+    req.once("end", () => {
+      // @ts-expect-error - TS2339: Property 'rawBody' does not exist on type 'IncomingMessage'.
+      req.rawBody = Buffer.concat(dataChunks);
+      // @ts-expect-error - TS2339: Property 'body' does not exist on type 'IncomingMessage'.
+      req.body = JSON.parse(req.rawBody);
+      middleware(req, res);
+    });
+  }).listen();
+
+  webhooks.on("push", (event) => {
+    expect(event.id).toBe("123e4567-e89b-12d3-a456-426655440000");
+  });
+
+  // @ts-expect-error complains about { port } although it's included in returned AddressInfo interface
+  const { port } = server.address();
+
+  const response = await fetch(`http://localhost:${port}/api/github/webhooks`, {
+    method: "POST",
+    headers: {
+      "Content-Type": "application/json",
+      "X-GitHub-Delivery": "123e4567-e89b-12d3-a456-426655440000",
+      "X-GitHub-Event": "push",
+      "X-Hub-Signature-256": signatureSha256,
+    },
+    body: pushEventPayload,
+  });
+
+  expect(response.status).toEqual(200);
+  expect(await response.text()).toEqual("ok\n");
+
+  server.close();
+});