Apply middleware patches

packages/next/build/webpack-config.ts

@@ -155,6 +155,12 @@ export function getDefineEnv({
     'process.env.__NEXT_OPTIMISTIC_CLIENT_CACHE': JSON.stringify(
       config.experimental.optimisticClientCache
     ),
+    'process.env.__NEXT_NO_MIDDLEWARE_URL_NORMALIZE': JSON.stringify(
+      config.experimental.skipMiddlewareUrlNormalize
+    ),
+    'process.env.__NEXT_ALLOW_MIDDLEWARE_RESPONSE_BODY': JSON.stringify(
+      config.experimental.allowMiddlewareResponseBody
+    ),
     'process.env.__NEXT_CROSS_ORIGIN': JSON.stringify(config.crossOrigin),
     'process.browser': JSON.stringify(isClient),
     'process.env.__NEXT_TEST_MODE': JSON.stringify(
@@ -1779,6 +1785,8 @@ export default async function getBaseWebpackConfig(
         new MiddlewarePlugin({
           dev,
           sriEnabled: !dev && !!config.experimental.sri?.algorithm,
+          allowMiddlewareResponseBody:
+            !!config.experimental.allowMiddlewareResponseBody,
         }),
       isClient &&
         new BuildManifestPlugin({

packages/next/build/webpack/plugins/middleware-plugin.ts

@@ -335,12 +335,14 @@ function getCodeAnalyzer(params: {
   dev: boolean
   compiler: webpack.Compiler
   compilation: webpack.Compilation
+  allowMiddlewareResponseBody: boolean
 }) {
   return (parser: webpack.javascript.JavascriptParser) => {
     const {
       dev,
       compiler: { webpack: wp },
       compilation,
+      allowMiddlewareResponseBody,
     } = params
     const { hooks } = parser
 
@@ -557,8 +559,10 @@ Learn More: https://nextjs.org/docs/messages/node-module-in-edge-runtime`,
         .for(`${prefix}WebAssembly.instantiate`)
         .tap(NAME, handleWrapWasmInstantiateExpression)
     }
-    hooks.new.for('Response').tap(NAME, handleNewResponseExpression)
-    hooks.new.for('NextResponse').tap(NAME, handleNewResponseExpression)
+    if (!allowMiddlewareResponseBody) {
+      hooks.new.for('Response').tap(NAME, handleNewResponseExpression)
+      hooks.new.for('NextResponse').tap(NAME, handleNewResponseExpression)
+    }
     hooks.callMemberChain.for('process').tap(NAME, handleCallMemberChain)
     hooks.expressionMemberChain.for('process').tap(NAME, handleCallMemberChain)
     hooks.importCall.tap(NAME, handleImport)
@@ -797,10 +801,19 @@ function getExtractMetadata(params: {
 export default class MiddlewarePlugin {
   private readonly dev: boolean
   private readonly sriEnabled: boolean
-
-  constructor({ dev, sriEnabled }: { dev: boolean; sriEnabled: boolean }) {
+  private readonly allowMiddlewareResponseBody: boolean
+  constructor({
+    dev,
+    sriEnabled,
+    allowMiddlewareResponseBody,
+  }: {
+    dev: boolean
+    sriEnabled: boolean
+    allowMiddlewareResponseBody: boolean
+  }) {
     this.dev = dev
     this.sriEnabled = sriEnabled
+    this.allowMiddlewareResponseBody = allowMiddlewareResponseBody
   }
 
   public apply(compiler: webpack.Compiler) {
@@ -813,6 +826,7 @@ export default class MiddlewarePlugin {
         dev: this.dev,
         compiler,
         compilation,
+        allowMiddlewareResponseBody: this.allowMiddlewareResponseBody,
       })
       hooks.parser.for('javascript/auto').tap(NAME, codeAnalyzer)
       hooks.parser.for('javascript/dynamic').tap(NAME, codeAnalyzer)

packages/next/lib/load-custom-routes.ts

@@ -624,50 +624,52 @@ export default async function loadCustomRoutes(
     )
   }
 
-  if (config.trailingSlash) {
-    redirects.unshift(
-      {
-        source: '/:file((?!\\.well-known(?:/.*)?)(?:[^/]+/)*[^/]+\\.\\w+)/',
-        destination: '/:file',
-        permanent: true,
-        locale: config.i18n ? false : undefined,
-        internal: true,
-      } as Redirect,
-      {
-        source: '/:notfile((?!\\.well-known(?:/.*)?)(?:[^/]+/)*[^/\\.]+)',
-        destination: '/:notfile/',
-        permanent: true,
-        locale: config.i18n ? false : undefined,
-        internal: true,
-      } as Redirect
-    )
-    if (config.basePath) {
-      redirects.unshift({
-        source: config.basePath,
-        destination: config.basePath + '/',
-        permanent: true,
-        basePath: false,
-        locale: config.i18n ? false : undefined,
-        internal: true,
-      } as Redirect)
-    }
-  } else {
-    redirects.unshift({
-      source: '/:path+/',
-      destination: '/:path+',
-      permanent: true,
-      locale: config.i18n ? false : undefined,
-      internal: true,
-    } as Redirect)
-    if (config.basePath) {
+  if (!config.experimental?.skipTrailingSlashRedirect) {
+    if (config.trailingSlash) {
+      redirects.unshift(
+        {
+          source: '/:file((?!\\.well-known(?:/.*)?)(?:[^/]+/)*[^/]+\\.\\w+)/',
+          destination: '/:file',
+          permanent: true,
+          locale: config.i18n ? false : undefined,
+          internal: true,
+        } as Redirect,
+        {
+          source: '/:notfile((?!\\.well-known(?:/.*)?)(?:[^/]+/)*[^/\\.]+)',
+          destination: '/:notfile/',
+          permanent: true,
+          locale: config.i18n ? false : undefined,
+          internal: true,
+        } as Redirect
+      )
+      if (config.basePath) {
+        redirects.unshift({
+          source: config.basePath,
+          destination: config.basePath + '/',
+          permanent: true,
+          basePath: false,
+          locale: config.i18n ? false : undefined,
+          internal: true,
+        } as Redirect)
+      }
+    } else {
       redirects.unshift({
-        source: config.basePath + '/',
-        destination: config.basePath,
+        source: '/:path+/',
+        destination: '/:path+',
         permanent: true,
-        basePath: false,
         locale: config.i18n ? false : undefined,
         internal: true,
       } as Redirect)
+      if (config.basePath) {
+        redirects.unshift({
+          source: config.basePath + '/',
+          destination: config.basePath,
+          permanent: true,
+          basePath: false,
+          locale: config.i18n ? false : undefined,
+          internal: true,
+        } as Redirect)
+      }
     }
   }
 

packages/next/server/base-server.ts

@@ -434,6 +434,33 @@ export default abstract class Server<ServerOptions extends Options = Options> {
     parsedUrl?: NextUrlWithParsedQuery
   ): Promise<void> {
     try {
+      // ensure cookies set in middleware are merged and
+      // not overridden by API routes/getServerSideProps
+      const _res = (res as any).originalResponse || res
+      const origSetHeader = _res.setHeader.bind(_res)
+
+      _res.setHeader = (name: string, val: string | string[]) => {
+        if (name.toLowerCase() === 'set-cookie') {
+          const middlewareValue = getRequestMeta(req, '_nextMiddlewareCookie')
+
+          if (
+            !middlewareValue ||
+            !Array.isArray(val) ||
+            !val.every((item, idx) => item === middlewareValue[idx])
+          ) {
+            val = [
+              ...(middlewareValue || []),
+              ...(typeof val === 'string'
+                ? [val]
+                : Array.isArray(val)
+                ? val
+                : []),
+            ]
+          }
+        }
+        return origSetHeader(name, val)
+      }
+
       const urlParts = (req.url || '').split('?')
       const urlNoQuery = urlParts[0]
 

packages/next/server/config-schema.ts

@@ -222,6 +222,9 @@ const configSchema = {
         adjustFontFallbacks: {
           type: 'boolean',
         },
+        allowMiddlewareResponseBody: {
+          type: 'boolean',
+        },
         amp: {
           additionalProperties: false,
           properties: {
@@ -348,6 +351,12 @@ const configSchema = {
         sharedPool: {
           type: 'boolean',
         },
+        skipMiddlewareUrlNormalize: {
+          type: 'boolean',
+        },
+        skipTrailingSlashRedirect: {
+          type: 'boolean',
+        },
         sri: {
           properties: {
             algorithm: {

packages/next/server/config-shared.ts

@@ -78,6 +78,9 @@ export interface NextJsWebpackConfig {
 }
 
 export interface ExperimentalConfig {
+  allowMiddlewareResponseBody?: boolean
+  skipMiddlewareUrlNormalize?: boolean
+  skipTrailingSlashRedirect?: boolean
   optimisticClientCache?: boolean
   legacyBrowsers?: boolean
   browsersListForSwc?: boolean

packages/next/server/next-server.ts

@@ -83,7 +83,7 @@ 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 { toNodeHeaders } from './web/utils'
+import { splitCookiesString, toNodeHeaders } from './web/utils'
 import { relativizeURL } from '../shared/lib/router/utils/relativize-url'
 import { prepareDestination } from '../shared/lib/router/utils/prepare-destination'
 import { normalizeLocalePath } from '../shared/lib/i18n/normalize-locale-path'
@@ -1051,9 +1051,17 @@ export default class NextNodeServer extends BaseServer {
         name: '_next/data catchall',
         check: true,
         fn: async (req, res, params, _parsedUrl) => {
+          const isNextDataNormalizing = getRequestMeta(
+            req,
+            '_nextDataNormalizing'
+          )
+
           // Make sure to 404 for /_next/data/ itself and
           // we also want to 404 if the buildId isn't correct
           if (!params.path || params.path[0] !== this.buildId) {
+            if (isNextDataNormalizing) {
+              return { finished: false }
+            }
             await this.render404(req, res, _parsedUrl)
             return {
               finished: true,
@@ -1797,6 +1805,14 @@ export default class NextNodeServer extends BaseServer {
     } else {
       for (let [key, value] of allHeaders) {
         result.response.headers.set(key, value)
+
+        if (key.toLowerCase() === 'set-cookie') {
+          addRequestMeta(
+            params.request,
+            '_nextMiddlewareCookie',
+            splitCookiesString(value)
+          )
+        }
       }
     }
 
@@ -2105,8 +2121,13 @@ export default class NextNodeServer extends BaseServer {
     params.res.statusCode = result.response.status
     params.res.statusMessage = result.response.statusText
 
-    result.response.headers.forEach((value, key) => {
-      params.res.appendHeader(key, value)
+    result.response.headers.forEach((value: string, key) => {
+      // the append handling is special cased for `set-cookie`
+      if (key.toLowerCase() === 'set-cookie') {
+        params.res.setHeader(key, value)
+      } else {
+        params.res.appendHeader(key, value)
+      }
     })
 
     if (result.response.body) {

packages/next/server/request-meta.ts

@@ -22,6 +22,8 @@ export interface RequestMeta {
   _nextHadBasePath?: boolean
   _nextRewroteUrl?: string
   _protocol?: string
+  _nextMiddlewareCookie?: string[]
+  _nextDataNormalizing?: boolean
 }
 
 export function getRequestMeta(

packages/next/server/router.ts

@@ -7,7 +7,11 @@ import type {
 } from '../shared/lib/router/utils/route-matcher'
 import type { RouteHas } from '../lib/load-custom-routes'
 
-import { getNextInternalQuery, NextUrlWithParsedQuery } from './request-meta'
+import {
+  addRequestMeta,
+  getNextInternalQuery,
+  NextUrlWithParsedQuery,
+} from './request-meta'
 import { getPathMatch } from '../shared/lib/router/utils/path-match'
 import { removeTrailingSlash } from '../shared/lib/router/utils/remove-trailing-slash'
 import { normalizeLocalePath } from '../shared/lib/i18n/normalize-locale-path'
@@ -189,7 +193,11 @@ export default class Router {
       ...(middlewareCatchAllRoute
         ? this.fsRoutes
             .filter((route) => route.name === '_next/data catchall')
-            .map((route) => ({ ...route, check: false }))
+            .map((route) => ({
+              ...route,
+              name: '_next/data normalizing',
+              check: false,
+            }))
         : []),
       ...this.headers,
       ...this.redirects,
@@ -433,6 +441,11 @@ export default class Router {
         }
 
         if (params) {
+          const isNextDataNormalizing = route.name === '_next/data normalizing'
+
+          if (isNextDataNormalizing) {
+            addRequestMeta(req, '_nextDataNormalizing', true)
+          }
           parsedUrlUpdated.pathname = matchPathname
           const result = await route.fn(
             req,
@@ -441,6 +454,9 @@ export default class Router {
             parsedUrlUpdated,
             upgradeHead
           )
+          if (isNextDataNormalizing) {
+            addRequestMeta(req, '_nextDataNormalizing', false)
+          }
           if (result.finished) {
             return true
           }