Only create locale domain links if on locale domain (#22032)

This updates to only create locale domain links if the current hostname is a locale domain to prevent making links unvisitable in development and preview environments where the configured locale domains don't point to the current build. 

Closes: #21211
Closes: #22011

packages/next/build/webpack/loaders/next-serverless-loader/utils.ts

@@ -349,6 +349,7 @@ export function getUtils({
     if (detectedDomain) {
       defaultLocale = detectedDomain.defaultLocale
       detectedLocale = defaultLocale
+      ;(req as any).__nextIsLocaleDomain = true
     }
 
     // if not domain specific locale use accept-language preferred

packages/next/client/link.tsx

@@ -301,12 +301,17 @@ function Link(props: React.PropsWithChildren<LinkProps>) {
     const curLocale =
       typeof locale !== 'undefined' ? locale : router && router.locale
 
-    const localeDomain = getDomainLocale(
-      as,
-      curLocale,
-      router && router.locales,
-      router && router.domainLocales
-    )
+    // we only render domain locales if we are currently on a domain locale
+    // so that locale links are still visitable in development/preview envs
+    const localeDomain =
+      router &&
+      router.isLocaleDomain &&
+      getDomainLocale(
+        as,
+        curLocale,
+        router && router.locales,
+        router && router.domainLocales
+      )
 
     childProps.href =
       localeDomain ||

packages/next/client/router.ts

@@ -41,6 +41,7 @@ const urlPropertyFields = [
   'locales',
   'defaultLocale',
   'isReady',
+  'isLocaleDomain',
 ]
 const routerEvents = [
   'routeChangeStart',

packages/next/next-server/lib/router/router.ts

@@ -348,6 +348,7 @@ export type BaseRouter = {
   locales?: string[]
   defaultLocale?: string
   domainLocales?: DomainLocales
+  isLocaleDomain: boolean
 }
 
 export type NextRouter = BaseRouter &
@@ -488,6 +489,7 @@ export default class Router implements BaseRouter {
   defaultLocale?: string
   domainLocales?: DomainLocales
   isReady: boolean
+  isLocaleDomain: boolean
 
   private _idx: number = 0
 
@@ -579,12 +581,17 @@ export default class Router implements BaseRouter {
       self.__NEXT_DATA__.gip ||
       (!autoExportDynamic && !self.location.search)
     )
+    this.isLocaleDomain = false
 
     if (process.env.__NEXT_I18N_SUPPORT) {
       this.locale = locale
       this.locales = locales
       this.defaultLocale = defaultLocale
       this.domainLocales = domainLocales
+      this.isLocaleDomain = !!detectDomainLocale(
+        domainLocales,
+        self.location.hostname
+      )
     }
 
     if (typeof window !== 'undefined') {
@@ -817,6 +824,7 @@ export default class Router implements BaseRouter {
         if (
           !didNavigate &&
           detectedDomain &&
+          this.isLocaleDomain &&
           self.location.hostname !== detectedDomain.domain
         ) {
           const asNoBasePath = delBasePath(as)

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

@@ -443,6 +443,7 @@ export default class Server {
       if (detectedDomain) {
         defaultLocale = detectedDomain.defaultLocale
         detectedLocale = defaultLocale
+        ;(req as any).__nextIsLocaleDomain = true
       }
 
       // if not domain specific locale use accept-language preferred

packages/next/next-server/server/render.tsx

@@ -80,6 +80,7 @@ class ServerRouter implements NextRouter {
   locales?: string[]
   defaultLocale?: string
   domainLocales?: DomainLocales
+  isLocaleDomain: boolean
   // TODO: Remove in the next major version, as this would mean the user is adding event listeners in server-side `render` method
   static events: MittEmitter = mitt()
 
@@ -90,10 +91,11 @@ class ServerRouter implements NextRouter {
     { isFallback }: { isFallback: boolean },
     isReady: boolean,
     basePath: string,
-    locale?: string,
-    locales?: string[],
-    defaultLocale?: string,
-    domainLocales?: DomainLocales
+    locale: string | undefined,
+    locales: string[] | undefined,
+    defaultLocale: string | undefined,
+    domainLocales: DomainLocales | undefined,
+    isLocaleDomain: boolean
   ) {
     this.route = pathname.replace(/\/$/, '') || '/'
     this.pathname = pathname
@@ -106,6 +108,7 @@ class ServerRouter implements NextRouter {
     this.defaultLocale = defaultLocale
     this.isReady = isReady
     this.domainLocales = domainLocales
+    this.isLocaleDomain = isLocaleDomain
   }
 
   push(): any {
@@ -550,7 +553,8 @@ export async function renderToHTML(
     renderOpts.locale,
     renderOpts.locales,
     renderOpts.defaultLocale,
-    renderOpts.domainLocales
+    renderOpts.domainLocales,
+    (req as any).__nextIsLocaleDomain
   )
   const ctx = {
     err,

test/integration/i18n-support/test/shared.js

@@ -67,7 +67,9 @@ export function runTests(ctx) {
     })
   })
 
-  it('should redirect to locale domain correctly client-side', async () => {
+  // this test can not currently be tested in browser without modifying the
+  // host resolution since it needs a domain to test locale domains behavior
+  it.skip('should redirect to locale domain correctly client-side', async () => {
     const browser = await webdriver(ctx.appPort, `${ctx.basePath || '/'}`)
 
     await browser.eval(`(function() {
@@ -104,7 +106,9 @@ export function runTests(ctx) {
     )
   })
 
-  it('should render the correct href for locale domain', async () => {
+  // this test can not currently be tested in browser without modifying the
+  // host resolution since it needs a domain to test locale domains behavior
+  it.skip('should render the correct href for locale domain', async () => {
     let browser = await webdriver(
       ctx.appPort,
       `${ctx.basePath || ''}/links?nextLocale=go`
@@ -142,6 +146,46 @@ export function runTests(ctx) {
     }
   })
 
+  it('should render the correct href with locale domains but not on a locale domain', async () => {
+    let browser = await webdriver(
+      ctx.appPort,
+      `${ctx.basePath || ''}/links?nextLocale=go`
+    )
+
+    for (const [element, pathname] of [
+      ['#to-another', '/another'],
+      ['#to-gsp', '/gsp'],
+      ['#to-fallback-first', '/gsp/fallback/first'],
+      ['#to-fallback-hello', '/gsp/fallback/hello'],
+      ['#to-gssp', '/gssp'],
+      ['#to-gssp-slug', '/gssp/first'],
+    ]) {
+      const href = await browser.elementByCss(element).getAttribute('href')
+      const { hostname, pathname: hrefPathname } = url.parse(href)
+      expect(hostname).not.toBe('example.com')
+      expect(hrefPathname).toBe(`${ctx.basePath || ''}/go${pathname}`)
+    }
+
+    browser = await webdriver(
+      ctx.appPort,
+      `${ctx.basePath || ''}/links?nextLocale=go-BE`
+    )
+
+    for (const [element, pathname] of [
+      ['#to-another', '/another'],
+      ['#to-gsp', '/gsp'],
+      ['#to-fallback-first', '/gsp/fallback/first'],
+      ['#to-fallback-hello', '/gsp/fallback/hello'],
+      ['#to-gssp', '/gssp'],
+      ['#to-gssp-slug', '/gssp/first'],
+    ]) {
+      const href = await browser.elementByCss(element).getAttribute('href')
+      const { hostname, pathname: hrefPathname } = url.parse(href)
+      expect(hostname).not.toBe('example.com')
+      expect(hrefPathname).toBe(`${ctx.basePath || ''}/go-BE${pathname}`)
+    }
+  })
+
   it('should navigate through history with query correctly', async () => {
     const browser = await webdriver(ctx.appPort, `${ctx.basePath || '/'}`)