fix(fetch): update host header on redirect (#26750)

Fixes https://github.com/microsoft/playwright/issues/26743

packages/playwright-core/src/server/fetch.ts

@@ -291,7 +291,7 @@ export abstract class APIRequestContext extends SdkObject {
             request.destroy();
             return;
           }
-          const headers: HeadersObject = { ...options.headers };
+          const headers = { ...options.headers };
           removeHeader(headers, `cookie`);
 
           // HTTP-redirect fetch step 13 (https://fetch.spec.whatwg.org/#http-redirect-fetch)
@@ -308,6 +308,7 @@ export abstract class APIRequestContext extends SdkObject {
             removeHeader(headers, `content-type`);
           }
 
+
           const redirectOptions: SendRequestOptions = {
             method,
             headers,
@@ -331,6 +332,10 @@ export abstract class APIRequestContext extends SdkObject {
               request.destroy();
               return;
             }
+
+            if (headers['host'])
+              headers['host'] = locationURL.host;
+
             notifyRequestFinished();
             fulfill(this._sendRequest(progress, locationURL, redirectOptions, postData));
             request.destroy();

tests/library/browsercontext-fetch.spec.ts

@@ -1123,4 +1123,33 @@ it('should support set-cookie with SameSite and without Secure attribute over HT
         expect(cookie.sameSite).toBe(value);
     });
   }
-});
+});
+
+it('should update host header on redirect', async ({ context, server }) => {
+  it.info().annotations.push({ type: 'issue', description: 'https://github.com/microsoft/playwright/issues/26743' });
+  let redirectCount = 0;
+  server.setRoute('/redirect', (req, res) => {
+    redirectCount++;
+    const path = (req.headers.host === new URL(server.PREFIX).host) ? '/redirect' : '/test';
+    res.writeHead(302, {
+      host: new URL(server.CROSS_PROCESS_PREFIX).host,
+      location: server.CROSS_PROCESS_PREFIX + path,
+    });
+    res.end();
+  });
+  server.setRoute('/test', (req, res) => {
+    res.writeHead(200, {
+      'content-type': 'text/plain',
+    });
+    res.end('Hello!');
+  });
+  const reqPromise = server.waitForRequest('/test');
+  const response = await context.request.get(server.PREFIX + '/redirect', {
+    headers: { host: new URL(server.PREFIX).host }
+  });
+  expect(redirectCount).toBe(2);
+  await expect(response).toBeOK();
+  expect(await response.text()).toBe('Hello!');
+
+  expect((await reqPromise).headers.host).toBe(new URL(server.CROSS_PROCESS_PREFIX).host);
+});