Update Node to support multiple single-value headers in H2

Author: pimterry

package-lock.json

@@ -50,7 +50,7 @@
     "@types/dns-packet": "^5.6.5",
     "@types/lodash": "^4.17.0",
     "@types/mocha": "^10.0.6",
-    "@types/node": "^22.15.30",
+    "@types/node": "^24.0.0",
     "@types/ws": "^8.18.1",
     "chai": "^5.1.0",
     "destroyable-server": "^1.0.1",

package.json

@@ -6,7 +6,12 @@ import { EndpointMeta, EndpointGroup } from './groups.js';
 export type { EndpointMeta, EndpointGroup };
 
 export type HttpRequest = http.IncomingMessage | http2.Http2ServerRequest;
-export type HttpResponse = http.ServerResponse | http2.Http2ServerResponse;
+// The @types/node v24 writeHead overloads diverged between http and http2, breaking
+// union-type calls. We intersect with a compatible signature so call sites can use it.
+export type HttpResponse = (http.ServerResponse | http2.Http2ServerResponse) & {
+    writeHead(statusCode: number, headers?: http.OutgoingHttpHeaders): HttpResponse;
+    writeHead(statusCode: number, statusMessage: string, headers?: http.OutgoingHttpHeaders): HttpResponse;
+};
 
 export type HttpHandler = (
     req: HttpRequest,

src/endpoints/http-index.ts

@@ -257,21 +257,24 @@ export function createHttp2Handler(options: {
     rootDomain: string
 }) {
     const handleRequest = createHttpRequestHandler(options);
-    const handler = http2.createServer(async (req, res) => {
-        try {
-            await handleRequest(req, res);
-        } catch (e) {
-            console.error(e);
-
-            if (res.closed) return;
-            else if (res.headersSent) {
-                res.destroy();
-            } else {
-                res.writeHead(500);
-                res.end('HTTP handler failed');
+    const handler = http2.createServer(
+        { strictSingleValueFields: false } as http2.ServerOptions,
+        async (req, res) => {
+            try {
+                await handleRequest(req, res);
+            } catch (e) {
+                console.error(e);
+
+                if (res.closed) return;
+                else if (res.headersSent) {
+                    res.destroy();
+                } else {
+                    res.writeHead(500);
+                    res.end('HTTP handler failed');
+                }
             }
         }
-    });
+    );
 
     handler.on('error', (err) => console.error('HTTP handler error', err));
 

src/http-handler.ts

@@ -1,4 +1,5 @@
 import * as net from 'net';
+import * as http2 from 'http2';
 import { expect } from 'chai';
 import { DestroyableServer, makeDestroyable } from 'destroyable-server';
 
@@ -57,4 +58,31 @@ describe("Response-headers endpoint", () => {
         expect(response.status).to.equal(200);
         expect(await response.json()).to.deep.equal({});
     });
+
+    it("returns duplicate single-value headers over HTTP/2", async () => {
+        const client = http2.connect(`http://localhost:${serverPort}`, { strictSingleValueFields: false });
+        try {
+            const request = client.request({
+                ':path': '/response-headers?X-Content-Type-Options=b&X-Content-Type-Options=c',
+                ':method': 'GET'
+            });
+            request.end();
+
+            const { status, rawHeaders } = await new Promise<{
+                status: number,
+                rawHeaders: string[]
+            }>((resolve) =>
+                request.on('response', (headers, _flags, rawHeaders) => resolve({
+                    status: headers[':status'] as number,
+                    rawHeaders
+                }))
+            );
+
+            expect(status).to.equal(200);
+            expect(rawHeaders).to.include.members(['x-content-type-options', 'b']);
+            expect(rawHeaders).to.include.members(['x-content-type-options', 'c']);
+        } finally {
+            client.close();
+        }
+    });
 });