fix(next): bind new stream functions with base incomingMessage object

packages/next/server/body-streams.ts

@@ -41,7 +41,7 @@ function replaceRequestBody<T extends IncomingMessage>(
   for (const key in stream) {
     let v = stream[key as keyof Readable] as any
     if (typeof v === 'function') {
-      v = v.bind(stream)
+      v = v.bind(base)
     }
     base[key as keyof T] = v
   }

test/e2e/proxy-request-with-middleware/app/middleware.js

@@ -0,0 +1,5 @@
+import { NextResponse } from 'next/server'
+
+export async function middleware() {
+  return NextResponse.next()
+}

test/e2e/proxy-request-with-middleware/app/pages/api/index.js

@@ -0,0 +1,28 @@
+import request from 'request'
+
+export const config = {
+  api: {
+    bodyParser: false,
+  },
+}
+
+export default function handler(req, res) {
+  return req
+    .pipe(
+      request(
+        `http://${
+          // node v18 resolves to IPv6 by default so force IPv4
+          process.version.startsWith('v18.')
+            ? `127.0.0.1:${req.headers.host.split(':').pop() || ''}`
+            : req.headers.host
+        }${req.url}/post`,
+        {
+          followAllRedirects: false,
+          followRedirect: false,
+          gzip: true,
+          json: false,
+        }
+      )
+    )
+    .pipe(res)
+}

test/e2e/proxy-request-with-middleware/app/pages/api/post.js

@@ -0,0 +1,12 @@
+export const config = {
+  api: {
+    bodyParser: false,
+  },
+}
+
+export default function handler(req, res) {
+  return res.json({
+    method: req.method,
+    headers: req.headers,
+  })
+}

test/e2e/proxy-request-with-middleware/test/index.test.ts

@@ -0,0 +1,53 @@
+/* eslint-env jest */
+
+import { join } from 'path'
+import { fetchViaHTTP } from 'next-test-utils'
+import { NextInstance } from 'test/lib/next-modes/base'
+import { createNext, FileRef } from 'e2e-utils'
+
+describe('Requests not effected when middleware used', () => {
+  let next: NextInstance
+
+  afterAll(() => next.destroy())
+  beforeAll(async () => {
+    next = await createNext({
+      files: {
+        pages: new FileRef(join(__dirname, '../app/pages')),
+        'middleware.js': new FileRef(join(__dirname, '../app/middleware.js')),
+      },
+      dependencies: {
+        request: '^2.88.2',
+      },
+    })
+  })
+
+  sendRequest('GET')
+  sendRequest('POST')
+
+  function sendRequest(method) {
+    const body = !['get', 'head'].includes(method.toLowerCase())
+      ? JSON.stringify({
+          key: 'value',
+        })
+      : undefined
+    it(`should proxy ${method} request ${
+      body ? 'with body' : ''
+    }`, async () => {
+      const headers = {
+        'content-type': 'application/json',
+        'x-custom-header': 'some value',
+      }
+      const res = await fetchViaHTTP(next.url, `api`, '', {
+        method: method.toUpperCase(),
+        headers,
+        body: method.toLowerCase() !== 'get' ? body : undefined,
+      })
+      const data = await res.json()
+      expect(data.method).toEqual(method)
+      if (body) {
+        expect(data.headers['content-length']).toEqual(String(body.length))
+      }
+      expect(data.headers).toEqual(expect.objectContaining(headers))
+    })
+  }
+})