Properly handle serverURL and publicServerUrl in Batch requests #6980 (#7049)

* fix: detect if the caller is accessing us via local or parse for batch requests (#6980)

* chore: minor cleanup from PR

Author: ZachGoldberg

spec/batch.spec.js

@@ -9,6 +9,7 @@ const serverURL1 = 'http://localhost:1234/1';
 const serverURLNaked = 'http://localhost:1234/';
 const publicServerURL = 'http://domain.com/parse';
 const publicServerURLNaked = 'http://domain.com/';
+const publicServerURLLong = 'https://domain.com/something/really/long';
 
 const headers = {
   'Content-Type': 'application/json',
@@ -24,6 +25,26 @@ describe('batch', () => {
     expect(internalURL).toEqual('/classes/Object');
   });
 
+  it('should return the proper url given a public url-only path', () => {
+    const originalURL = '/something/really/long/batch';
+    const internalURL = batch.makeBatchRoutingPathFunction(
+      originalURL,
+      serverURL,
+      publicServerURLLong
+    )('/parse/classes/Object');
+    expect(internalURL).toEqual('/classes/Object');
+  });
+
+  it('should return the proper url given a server url-only path', () => {
+    const originalURL = '/parse/batch';
+    const internalURL = batch.makeBatchRoutingPathFunction(
+      originalURL,
+      serverURL,
+      publicServerURLLong
+    )('/parse/classes/Object');
+    expect(internalURL).toEqual('/classes/Object');
+  });
+
   it('should return the proper url same public/local endpoint', () => {
     const originalURL = '/parse/batch';
     const internalURL = batch.makeBatchRoutingPathFunction(

src/batch.js

@@ -36,12 +36,23 @@ function makeBatchRoutingPathFunction(originalUrl, serverURL, publicServerURL) {
   if (serverURL && publicServerURL && serverURL.path != publicServerURL.path) {
     const localPath = serverURL.path;
     const publicPath = publicServerURL.path;
+
     // Override the api prefix
     apiPrefix = localPath;
     return function (requestPath) {
-      // Build the new path by removing the public path
-      // and joining with the local path
-      const newPath = path.posix.join('/', localPath, '/', requestPath.slice(publicPath.length));
+      // Figure out which server url was used by figuring out which
+      // path more closely matches requestPath
+      const startsWithLocal = requestPath.startsWith(localPath);
+      const startsWithPublic = requestPath.startsWith(publicPath);
+      const pathLengthToUse =
+        startsWithLocal && startsWithPublic
+          ? Math.max(localPath.length, publicPath.length)
+          : startsWithLocal
+            ? localPath.length
+            : publicPath.length;
+
+      const newPath = path.posix.join('/', localPath, '/', requestPath.slice(pathLengthToUse));
+
       // Use the method for local routing
       return makeRoutablePath(newPath);
     };