RCOCOA-2310: Fix a crash when receiving 401/403 when opening a watch …

…stream (#8536)

* Fix a crash when error is nil for watch streams

* var -> let

* Assert underlying error is nil

* Fix lint violations

CHANGELOG.md

@@ -5,7 +5,8 @@ x.y.z Release notes (yyyy-MM-dd)
 
 ### Fixed
 * <How to hit and notice issue? what was the impact?> ([#????](https://github.com/realm/realm-swift/issues/????), since v?.?.?)
-* None.
+* Fixed a crash that would occur when an http error 401 or 403 is returned upon
+ opening a watch stream for a MongoDB collection. ([#8519](https://github.com/realm/realm-swift/issues/8519))
 
 <!-- ### Breaking Changes - ONLY INCLUDE FOR NEW MAJOR version -->
 

Realm/ObjectServerTests/RealmServer.swift

@@ -1187,6 +1187,14 @@ public class RealmServer: NSObject {
  return session.apps[appServerId].users[userId].delete()
  }
 
+ public func revokeUserSessions(_ appId: String, userId: String) -> Result<Any?, Error> {
+ guard let appServerId = try? RealmServer.shared.retrieveAppServerId(appId),
+ let session = session else {
+ return .failure(URLError(.unknown))
+ }
+ return session.apps[appServerId].users[userId].logout.put([:])
+ }
+
  public func retrieveSchemaProperties(_ appId: String, className: String, _ completion: @escaping (Result<[String], Error>) -> Void) {
  guard let appServerId = try? RealmServer.shared.retrieveAppServerId(appId),
  let session = session else {

Realm/ObjectServerTests/SwiftObjectServerTests.swift

@@ -1322,6 +1322,35 @@ class SwiftObjectServerTests: SwiftSyncTestCase {
  let objectCol = (obj!.anyCol.dynamicObject?.objectCol as? Object)
  XCTAssertEqual((objectCol?["firstName"] as? String), "Morty")
  }
+
+ func testRevokeUserSessions() {
+ let email = "realm_tests_do_autoverify\(randomString(7))@\(randomString(7)).com"
+ let password = randomString(10)
+
+ app.emailPasswordAuth.registerUser(email: email, password: password).await(self)
+
+ let syncUser = app.login(credentials: Credentials.emailPassword(email: email, password: password)).await(self)
+
+ // Should succeed refreshing custom data
+ syncUser.refreshCustomData().await(self)
+
+ _ = try? RealmServer.shared.revokeUserSessions(appId, userId: syncUser.id).get()
+
+ // Should fail refreshing custom data. This verifies we're correctly handling the error in RLMSessionDelegate
+ syncUser.refreshCustomData().awaitFailure(self)
+
+ // This verifies that we don't crash in RLMEventSessionDelegate when creating a watch stream
+ // with a revoked user. See https://github.com/realm/realm-swift/issues/8519
+ let watchTestUtility = WatchTestUtility(testCase: self, expectError: true)
+ _ = syncUser.collection(for: Dog.self, app: app).watch(delegate: watchTestUtility)
+ watchTestUtility.waitForOpen()
+ watchTestUtility.waitForClose()
+
+ let didCloseError = watchTestUtility.didCloseError! as NSError
+ XCTAssertNotNil(didCloseError)
+ XCTAssertEqual(didCloseError.localizedDescription, "URLSession HTTP error code: 403")
+ XCTAssertNil(didCloseError.userInfo[NSUnderlyingErrorKey])
+ }
 }
 
 #endif // os(macOS)

Realm/ObjectServerTests/WatchTestUtility.swift

@@ -26,10 +26,13 @@ final public class WatchTestUtility: ChangeEventDelegate {
  private let openExpectation: XCTestExpectation
  private let closeExpectation: XCTestExpectation
  private var changeExpectation: XCTestExpectation?
+ private let expectError: Bool
+ public var didCloseError: Error?
 
- public init(testCase: XCTestCase, matchingObjectId: ObjectId? = nil) {
+ public init(testCase: XCTestCase, matchingObjectId: ObjectId? = nil, expectError: Bool = false) {
  self.testCase = testCase
  self.matchingObjectId = matchingObjectId
+ self.expectError = expectError
  openExpectation = testCase.expectation(description: "Open watch stream")
  closeExpectation = testCase.expectation(description: "Close watch stream")
  }
@@ -57,7 +60,13 @@ final public class WatchTestUtility: ChangeEventDelegate {
  }
 
  public func changeStreamDidClose(with error: Error?) {
- XCTAssertNil(error)
+ if expectError {
+ XCTAssertNotNil(error)
+ } else {
+ XCTAssertNil(error)
+ }
+
+ didCloseError = error
  closeExpectation.fulfill()
  }
 

Realm/RLMNetworkTransport.mm

@@ -226,12 +226,14 @@ - (void)URLSession:(__unused NSURLSession *)session
 
  NSString *errorStatus = [NSString stringWithFormat:@"URLSession HTTP error code: %ld",
  (long)httpResponse.statusCode];
+
+ // error may be nil when the http status code is 401/403 - replace it with [NSNull null] in that case
  NSError *wrappedError = [NSError errorWithDomain:RLMAppErrorDomain
  code:RLMAppErrorHttpRequestFailed
  userInfo:@{NSLocalizedDescriptionKey: errorStatus,
- RLMHTTPStatusCodeKey: @(httpResponse.statusCode),
+  RLMHTTPStatusCodeKey: @(httpResponse.statusCode),
  NSURLErrorFailingURLErrorKey: task.currentRequest.URL,
- NSUnderlyingErrorKey: error}];
+ NSUnderlyingErrorKey: error?: [NSNull null]}];
  return [_subscriber didCloseWithError:wrappedError];
 }