Rename header conversion functions

packages/next/src/export/worker.ts

@@ -43,7 +43,7 @@ import { NEXT_DYNAMIC_NO_SSR_CODE } from '../shared/lib/lazy-dynamic/no-ssr-erro
 import { createRequestResponseMocks } from '../server/lib/mock-request'
 import { NodeNextRequest } from '../server/base-http/node'
 import { isAppRouteRoute } from '../lib/is-app-route-route'
-import { toNodeHeaders } from '../server/web/utils'
+import { toNodeOutgoingHttpHeaders } from '../server/web/utils'
 import { RouteModuleLoader } from '../server/future/helpers/module-loader/route-module-loader'
 import { NextRequestAdapter } from '../server/web/spec-extension/adapters/next-request'
 import * as ciEnvironment from '../telemetry/ci-info'
@@ -445,7 +445,7 @@ export default async function exportPage({
                 context.staticGenerationContext.store?.revalidate || false
 
               results.fromBuildExportRevalidate = revalidate
-              const headers = toNodeHeaders(response.headers)
+              const headers = toNodeOutgoingHttpHeaders(response.headers)
               const cacheTags = (context.staticGenerationContext as any)
                 .fetchTags
 

packages/next/src/server/base-http/web.ts

@@ -1,5 +1,5 @@
 import type { IncomingHttpHeaders, OutgoingHttpHeaders } from 'http'
-import { toNodeHeaders } from '../web/utils'
+import { toNodeOutgoingHttpHeaders } from '../web/utils'
 
 import { BaseNextRequest, BaseNextResponse } from './index'
 
@@ -81,7 +81,7 @@ export class WebNextResponse extends BaseNextResponse<WritableStream> {
   }
 
   getHeaders(): OutgoingHttpHeaders {
-    return toNodeHeaders(this.headers)
+    return toNodeOutgoingHttpHeaders(this.headers)
   }
 
   hasHeader(name: string): boolean {

packages/next/src/server/base-server.ts

@@ -100,7 +100,10 @@ import { I18NProvider } from './future/helpers/i18n-provider'
 import { sendResponse } from './send-response'
 import { RouteKind } from './future/route-kind'
 import { handleInternalServerErrorResponse } from './future/route-modules/helpers/response-handlers'
-import { fromNodeHeaders, toNodeHeaders } from './web/utils'
+import {
+  fromNodeOutgoingHttpHeaders,
+  toNodeOutgoingHttpHeaders,
+} from './web/utils'
 import { NEXT_QUERY_PARAM_PREFIX } from '../lib/constants'
 
 export type FindComponentsResult = {
@@ -1626,7 +1629,7 @@ export default abstract class Server<ServerOptions extends Options = Options> {
               const blob = await response.blob()
 
               // Copy the headers from the response.
-              const headers = toNodeHeaders(response.headers)
+              const headers = toNodeOutgoingHttpHeaders(response.headers)
 
               if (cacheTags) {
                 headers['x-next-cache-tags'] = cacheTags
@@ -2024,7 +2027,7 @@ export default abstract class Server<ServerOptions extends Options = Options> {
         req,
         res,
         new Response(cachedData.body, {
-          headers: fromNodeHeaders(headers),
+          headers: fromNodeOutgoingHttpHeaders(headers),
           status: cachedData.status || 200,
         })
       )

packages/next/src/server/lib/mock-request.ts

@@ -9,7 +9,7 @@ import type { Socket } from 'net'
 import type { TLSSocket } from 'tls'
 
 import Stream from 'stream'
-import { toNodeHeaders } from '../web/utils'
+import { toNodeOutgoingHttpHeaders } from '../web/utils'
 
 interface MockedRequestOptions {
   url: string
@@ -240,7 +240,7 @@ export class MockedResponse extends Stream.Writable implements ServerResponse {
   }
 
   public getHeaders(): OutgoingHttpHeaders {
-    return toNodeHeaders(this.headers)
+    return toNodeOutgoingHttpHeaders(this.headers)
   }
 
   public getHeaderNames(): string[] {

packages/next/src/server/next-server.ts

@@ -78,7 +78,7 @@ import { normalizePagePath } from '../shared/lib/page-path/normalize-page-path'
 import { loadComponents } from './load-components'
 import isError, { getProperError } from '../lib/is-error'
 import { FontManifest } from './font-utils'
-import { splitCookiesString, toNodeHeaders } from './web/utils'
+import { splitCookiesString, toNodeOutgoingHttpHeaders } from './web/utils'
 import { relativizeURL } from '../shared/lib/router/utils/relativize-url'
 import { prepareDestination } from '../shared/lib/router/utils/prepare-destination'
 import { getMiddlewareRouteMatcher } from '../shared/lib/router/utils/middleware-route-matcher'
@@ -2496,7 +2496,7 @@ export default class NextNodeServer extends BaseServer {
 
                 if (isMiddlewareInvoke && 'response' in result) {
                   for (const [key, value] of Object.entries(
-                    toNodeHeaders(result.response.headers)
+                    toNodeOutgoingHttpHeaders(result.response.headers)
                   )) {
                     if (key !== 'content-encoding' && value !== undefined) {
                       res.setHeader(key, value as string | string[])
@@ -2590,7 +2590,7 @@ export default class NextNodeServer extends BaseServer {
             result.response.headers.delete('x-middleware-next')
 
             for (const [key, value] of Object.entries(
-              toNodeHeaders(result.response.headers)
+              toNodeOutgoingHttpHeaders(result.response.headers)
             )) {
               if (
                 [

packages/next/src/server/web/adapter.ts

@@ -1,7 +1,7 @@
 import type { NextMiddleware, RequestData, FetchEventResult } from './types'
 import type { RequestInit } from './spec-extension/request'
 import { PageSignatureError } from './error'
-import { fromNodeHeaders } from './utils'
+import { fromNodeOutgoingHttpHeaders } from './utils'
 import { NextFetchEvent } from './spec-extension/fetch-event'
 import { NextRequest } from './spec-extension/request'
 import { NextResponse } from './spec-extension/response'
@@ -127,7 +127,7 @@ export async function adapter(
     requestUrl.pathname = '/'
   }
 
-  const requestHeaders = fromNodeHeaders(params.request.headers)
+  const requestHeaders = fromNodeOutgoingHttpHeaders(params.request.headers)
   const flightHeaders = new Map()
   // Parameters should only be stripped for middleware
   if (!isEdgeRendering) {

packages/next/src/server/web/spec-extension/adapters/next-request.ts

@@ -3,7 +3,7 @@ import type { NodeNextRequest } from '../../../base-http/node'
 import type { WebNextRequest } from '../../../base-http/web'
 
 import { getRequestMeta } from '../../../request-meta'
-import { fromNodeHeaders } from '../../utils'
+import { fromNodeOutgoingHttpHeaders } from '../../utils'
 import { NextRequest } from '../request'
 
 export class NextRequestAdapter {
@@ -38,7 +38,7 @@ export class NextRequestAdapter {
     return new NextRequest(url, {
       body,
       method: request.method,
-      headers: fromNodeHeaders(request.headers),
+      headers: fromNodeOutgoingHttpHeaders(request.headers),
       // @ts-expect-error - see https://github.com/whatwg/fetch/pull/1457
       duplex: 'half',
       // geo
@@ -57,7 +57,7 @@ export class NextRequestAdapter {
     return new NextRequest(request.url, {
       body,
       method: request.method,
-      headers: fromNodeHeaders(request.headers),
+      headers: fromNodeOutgoingHttpHeaders(request.headers),
       // @ts-expect-error - see https://github.com/whatwg/fetch/pull/1457
       duplex: 'half',
       // geo

packages/next/src/server/web/spec-extension/request.ts

@@ -1,7 +1,7 @@
 import type { I18NConfig } from '../../config-shared'
 import type { RequestData } from '../types'
 import { NextURL } from '../next-url'
-import { toNodeHeaders, validateURL } from '../utils'
+import { toNodeOutgoingHttpHeaders, validateURL } from '../utils'
 import { RemovedUAError, RemovedPageError } from '../error'
 import { RequestCookies } from './cookies'
 
@@ -22,7 +22,7 @@ export class NextRequest extends Request {
     validateURL(url)
     super(url, init)
     const nextUrl = new NextURL(url, {
-      headers: toNodeHeaders(this.headers),
+      headers: toNodeOutgoingHttpHeaders(this.headers),
       nextConfig: init.nextConfig,
     })
     this[INTERNALS] = {

packages/next/src/server/web/spec-extension/response.ts

@@ -1,6 +1,6 @@
 import type { I18NConfig } from '../../config-shared'
 import { NextURL } from '../next-url'
-import { toNodeHeaders, validateURL } from '../utils'
+import { toNodeOutgoingHttpHeaders, validateURL } from '../utils'
 
 import { ResponseCookies } from './cookies'
 
@@ -40,7 +40,7 @@ export class NextResponse<Body = unknown> extends Response {
       cookies: new ResponseCookies(this.headers),
       url: init.url
         ? new NextURL(init.url, {
-            headers: toNodeHeaders(this.headers),
+            headers: toNodeOutgoingHttpHeaders(this.headers),
             nextConfig: init.nextConfig,
           })
         : undefined,

packages/next/src/server/web/utils.test.ts

@@ -1,4 +1,4 @@
-import { toNodeHeaders } from './utils'
+import { toNodeOutgoingHttpHeaders } from './utils'
 
 // We use `Headers` here which is provided by the polyfill.
 import '../node-polyfill-fetch'
@@ -10,7 +10,7 @@ describe('toNodeHeaders', () => {
     headers.append('set-cookie', 'foo=bar')
     headers.append('set-cookie', 'bar=foo')
 
-    expect(toNodeHeaders(headers)).toEqual({
+    expect(toNodeOutgoingHttpHeaders(headers)).toEqual({
       'set-cookie': ['foo=bar', 'bar=foo'],
     })
   })
@@ -20,7 +20,7 @@ describe('toNodeHeaders', () => {
 
     headers.append('set-cookie', 'foo=bar')
 
-    expect(toNodeHeaders(headers)).toEqual({
+    expect(toNodeOutgoingHttpHeaders(headers)).toEqual({
       'set-cookie': 'foo=bar',
     })
   })
@@ -30,13 +30,13 @@ describe('toNodeHeaders', () => {
 
     headers.append('set-cookie', 'foo=bar, bar=foo')
 
-    expect(toNodeHeaders(headers)).toEqual({
+    expect(toNodeOutgoingHttpHeaders(headers)).toEqual({
       'set-cookie': ['foo=bar', 'bar=foo'],
     })
 
     headers.append('set-cookie', 'baz=qux')
 
-    expect(toNodeHeaders(headers)).toEqual({
+    expect(toNodeOutgoingHttpHeaders(headers)).toEqual({
       'set-cookie': ['foo=bar', 'bar=foo', 'baz=qux'],
     })
   })
@@ -47,12 +47,8 @@ describe('toNodeHeaders', () => {
     headers.append('set-cookie', 'foo=bar')
     headers.append('Set-Cookie', 'bar=foo')
 
-    expect(toNodeHeaders(headers)).toEqual({
+    expect(toNodeOutgoingHttpHeaders(headers)).toEqual({
       'set-cookie': ['foo=bar', 'bar=foo'],
     })
   })
-
-  it('should return an empty object when no headers are provided', () => {
-    expect(toNodeHeaders()).toEqual({})
-  })
 })

packages/next/src/server/web/utils.ts

@@ -1,8 +1,19 @@
 import type { OutgoingHttpHeaders } from 'http'
 
-export function fromNodeHeaders(object: OutgoingHttpHeaders): Headers {
+/**
+ * Converts a Node.js IncomingHttpHeaders object to a Headers object. Any
+ * headers with multiple values will be joined with a comma and space. Any
+ * headers that have an undefined value will be ignored and others will be
+ * coerced to strings.
+ *
+ * @param nodeHeaders the headers object to convert
+ * @returns the converted headers object
+ */
+export function fromNodeOutgoingHttpHeaders(
+  nodeHeaders: OutgoingHttpHeaders
+): Headers {
   const headers = new Headers()
-  for (let [key, value] of Object.entries(object)) {
+  for (let [key, value] of Object.entries(nodeHeaders)) {
     const values = Array.isArray(value) ? value : [value]
     for (let v of values) {
       if (typeof v === 'undefined') continue
@@ -92,8 +103,17 @@ export function splitCookiesString(cookiesString: string) {
   return cookiesStrings
 }
 
-export function toNodeHeaders(headers?: Headers): OutgoingHttpHeaders {
-  const result: OutgoingHttpHeaders = {}
+/**
+ * Converts a Headers object to a Node.js OutgoingHttpHeaders object. This is
+ * required to support the set-cookie header, which may have multiple values.
+ *
+ * @param headers the headers object to convert
+ * @returns the converted headers object
+ */
+export function toNodeOutgoingHttpHeaders(
+  headers: Headers
+): OutgoingHttpHeaders {
+  const nodeHeaders: OutgoingHttpHeaders = {}
   const cookies: string[] = []
   if (headers) {
     for (const [key, value] of headers.entries()) {
@@ -102,13 +122,13 @@ export function toNodeHeaders(headers?: Headers): OutgoingHttpHeaders {
         // set-cookie headers. We need to merge them into one header array
         // to represent all the cookies.
         cookies.push(...splitCookiesString(value))
-        result[key] = cookies.length === 1 ? cookies[0] : cookies
+        nodeHeaders[key] = cookies.length === 1 ? cookies[0] : cookies
       } else {
-        result[key] = value
+        nodeHeaders[key] = value
       }
     }
   }
-  return result
+  return nodeHeaders
 }
 
 /**