FIRApp bundle ID validation: allow exact match for extensions (#5531)

* FIRApp bundle ID validation: allow exact match for extensions

* Comments

Author: maksymmalyhin

FirebaseCore/Sources/FIRBundleUtil.m

@@ -49,15 +49,19 @@ + (NSArray *)relevantURLSchemes {
 
 + (BOOL)hasBundleIdentifierPrefix:(NSString *)bundleIdentifier inBundles:(NSArray *)bundles {
   for (NSBundle *bundle in bundles) {
-    // This allows app extensions that have the app's bundle as their prefix to pass this test.
-    NSString *applicationBundleIdentifier =
-        [GULAppEnvironmentUtil isAppExtension]
-            ? [self bundleIdentifierByRemovingLastPartFrom:bundle.bundleIdentifier]
-            : bundle.bundleIdentifier;
-
-    if ([applicationBundleIdentifier isEqualToString:bundleIdentifier]) {
+    if ([bundle.bundleIdentifier isEqualToString:bundleIdentifier]) {
       return YES;
     }
+
+    if ([GULAppEnvironmentUtil isAppExtension]) {
+      // A developer could be using the same `FIROptions` for both their app and extension. Since
+      // extensions have a suffix added to the bundleID, we consider a matching prefix as valid.
+      NSString *appBundleIDFromExtension =
+          [self bundleIdentifierByRemovingLastPartFrom:bundle.bundleIdentifier];
+      if ([appBundleIDFromExtension isEqualToString:bundleIdentifier]) {
+        return YES;
+      }
+    }
   }
   return NO;
 }

FirebaseCore/Tests/Unit/FIRBundleUtilTest.m

@@ -95,6 +95,18 @@ - (void)testBundleIdentifierHasPrefixInBundlesForExtension {
   [environmentUtilsMock stopMocking];
 }
 
+- (void)testBundleIdentifierExistsInBundlesForExtensions_exactMatch {
+  id environmentUtilsMock = [OCMockObject mockForClass:[GULAppEnvironmentUtil class]];
+  [[[environmentUtilsMock stub] andReturnValue:@(YES)] isAppExtension];
+
+  // Mock bundle should have what app extension has, the extension bundle ID.
+  [OCMStub([self.mockBundle bundleIdentifier]) andReturn:@"com.google.test.someextension"];
+  XCTAssertTrue([FIRBundleUtil hasBundleIdentifierPrefix:@"com.google.test.someextension"
+                                               inBundles:@[ self.mockBundle ]]);
+
+  [environmentUtilsMock stopMocking];
+}
+
 - (void)testBundleIdentifierHasPrefixInBundlesNotValidExtension {
   id environmentUtilsMock = [OCMockObject mockForClass:[GULAppEnvironmentUtil class]];
   [[[environmentUtilsMock stub] andReturnValue:@(YES)] isAppExtension];