Skip requests to assets/main/vercel hosts in middleware (#2927)

Author: SamyPesse

packages/gitbook-v2/src/middleware.ts

@@ -8,7 +8,7 @@ import { removeLeadingSlash, removeTrailingSlash } from '@/lib/paths';
 import { getResponseCookiesForVisitorAuth, getVisitorToken } from '@/lib/visitor-token';
 import { serveResizedImage } from '@/routes/image';
 import { getPublishedContentByURL } from '@v2/lib/data';
-import { GITBOOK_URL } from '@v2/lib/env';
+import { GITBOOK_ASSETS_URL, GITBOOK_URL } from '@v2/lib/env';
 import { MiddlewareHeaders } from '@v2/lib/middleware';
 
 export const config = {
@@ -20,7 +20,7 @@ type URLWithMode = { url: URL; mode: 'url' | 'url-host' };
 export async function middleware(request: NextRequest) {
     try {
         // Route all requests to a site
-        const extracted = extractURL(request);
+        const extracted = getSiteURLFromRequest(request);
         if (extracted) {
             /**
              * Serve image resizing requests (all requests containing `/~gitbook/image`).
@@ -114,7 +114,7 @@ async function serveSiteByURL(request: NextRequest, urlWithMode: URLWithMode) {
         encodePathInSiteContent(data.pathname),
     ].join('/');
 
-    console.log(`rewriting to ${route}`);
+    console.log(`rewriting ${request.nextUrl.toString()} to ${route}`);
 
     const rewrittenURL = new URL(`/${route}`, request.nextUrl.toString());
     const response = NextResponse.rewrite(rewrittenURL, {
@@ -163,7 +163,7 @@ function serveErrorResponse(error: Error) {
  * - The request URL is matching `/url/:url`:
  *      URL is taken from the pathname.
  */
-function extractURL(request: NextRequest): URLWithMode | null {
+function getSiteURLFromRequest(request: NextRequest): URLWithMode | null {
     const xGitbookUrl = request.headers.get('x-gitbook-url');
     if (xGitbookUrl) {
         return {
@@ -172,30 +172,45 @@ function extractURL(request: NextRequest): URLWithMode | null {
         };
     }
 
-    const xForwardedHost = request.headers.get('x-forwarded-host');
-    // The x-forwarded-host is set by Vercel for all requests
-    // so we ignore it if the hostname is the same as the instance one.
-    if (xForwardedHost && GITBOOK_URL && new URL(GITBOOK_URL).host !== xForwardedHost) {
-        console.log('xForwardedHost', xForwardedHost, GITBOOK_URL, new URL(GITBOOK_URL).host);
-        console.log('process.env.VERCEL_URL', process.env.VERCEL_URL);
-        console.log('process.env.GITBOOK_URL', process.env.GITBOOK_URL);
+    const isMainHost =
+        (GITBOOK_URL && request.nextUrl.host === new URL(GITBOOK_URL).host) ||
+        (process.env.VERCEL_URL && request.nextUrl.host === new URL(process.env.VERCEL_URL).host);
+    const isAssetsHost =
+        GITBOOK_ASSETS_URL && request.nextUrl.host === new URL(GITBOOK_ASSETS_URL).host;
+
+    // /url/:url requests on the main host
+    const prefix = '/url/';
+    if (isMainHost && request.nextUrl.pathname.startsWith(prefix)) {
         return {
             url: appendQueryParams(
-                new URL(`https://${xForwardedHost}${request.nextUrl.pathname}`),
+                new URL(`https://${request.nextUrl.pathname.slice(prefix.length)}`),
                 request.nextUrl.searchParams
             ),
-            mode: 'url-host',
+            mode: 'url',
         };
     }
 
-    const prefix = '/url/';
-    if (request.nextUrl.pathname.startsWith(prefix)) {
+    // Skip other requests to main hosts
+    if (isMainHost || isAssetsHost) {
+        return null;
+    }
+
+    const xForwardedHost = request.headers.get('x-forwarded-host');
+    // The x-forwarded-host is set by Vercel for all requests
+    // so we ignore it if the hostname is the same as the instance one.
+    if (xForwardedHost) {
+        console.log('xForwardedHost', xForwardedHost, request.nextUrl.host);
+        console.log('env', {
+            VERCEL_URL: process.env.VERCEL_URL,
+            GITBOOK_URL: GITBOOK_URL,
+            GITBOOK_ASSETS_URL: GITBOOK_ASSETS_URL,
+        });
         return {
             url: appendQueryParams(
-                new URL(`https://${request.nextUrl.pathname.slice(prefix.length)}`),
+                new URL(`https://${xForwardedHost}${request.nextUrl.pathname}`),
                 request.nextUrl.searchParams
             ),
-            mode: 'url',
+            mode: 'url-host',
         };
     }