Fixed crash with third party library gtm-session-fetcher

Sources/EmbraceCore/Capture/Network/URLSessionCaptureService.swift

@@ -102,6 +102,12 @@ struct URLSessionInitWithDelegateSwizzler: URLSessionSwizzler {
         try swizzleClassMethod { originalImplementation -> BlockImplementationType in
             return { urlSession, configuration, delegate, queue -> URLSession in
                 let proxiedDelegate = (delegate != nil) ? delegate : EmbraceDummyURLSessionDelegate()
+
+                // check if we support proxying this type of delegate
+                guard isDelegateSupported(proxiedDelegate) else {
+                    return originalImplementation(urlSession, Self.selector, configuration, delegate, queue)
+                }
+
                 let newDelegate = URLSessionDelegateProxy(originalDelegate: proxiedDelegate, handler: handler)
                 let session = originalImplementation(urlSession, Self.selector, configuration, newDelegate, queue)
 
@@ -116,6 +122,32 @@ struct URLSessionInitWithDelegateSwizzler: URLSessionSwizzler {
             }
         }
     }
+
+    // list of third party URLSessionDelegate implementations that we don't support
+    // due to issues / crashes out of our control
+    private let unsupportedDelegates: [String] = [
+
+        // This type belongs to an internal library used by Firebase which
+        // incorrectly assumes the type of the URLSession delegate, resulting
+        // in it calling a method that is not implemented by our proxy.
+        //
+        // We can't solve this on our side in a clean way so we'll just not
+        // capture any requests from this library until the issue is solved
+        // on their side.
+        //
+        // Library: https://github.com/google/gtm-session-fetcher/
+        // Issue: https://github.com/google/gtm-session-fetcher/issues/190
+        "GTMSessionFetcher"
+    ]
+
+    func isDelegateSupported(_ delegate: URLSessionDelegate?) -> Bool {
+        guard let delegate = delegate else {
+            return true
+        }
+
+        let name = String(describing: delegate)
+        return unsupportedDelegates.first { name.contains($0) } == nil
+    }
 }
 
 struct SessionTaskResumeSwizzler: URLSessionSwizzler {

Tests/EmbraceCoreTests/Capture/Network/URLSessionInitWithDelegateSwizzlerTests.swift

@@ -15,7 +15,7 @@ class URLSessionInitWithDelegateSwizzlerTests: XCTestCase {
     func testAfterInstall_onCreateURLSessionWithDelegate_originalShouldBeWrapped() throws {
         givenDataTaskWithURLRequestSwizzler()
         try givenSwizzlingWasDone()
-        whenInitializingURLSessionWithDummyDelegate()
+        whenInitializingURLSessionWithDelegate()
         thenSessionsDelegateShouldntBeDummyDelegate()
         thenSessionsDelegateShouldBeEmbracesProxy()
     }
@@ -31,6 +31,14 @@ class URLSessionInitWithDelegateSwizzlerTests: XCTestCase {
         givenDataTaskWithURLRequestSwizzler()
         thenBaseClassShouldBeURLSession()
     }
+
+    func test_unsupportedDelegates() throws {
+        givenDataTaskWithURLRequestSwizzler()
+        try givenSwizzlingWasDone()
+        whenInitializingURLSessionWithDelegate(GTMSessionFetcher())
+        thenSessionsDelegateShouldntBeEmbracesProxy()
+        XCTAssertTrue(session.delegate.self is GTMSessionFetcher)
+    }
 }
 
 private extension URLSessionInitWithDelegateSwizzlerTests {
@@ -43,10 +51,9 @@ private extension URLSessionInitWithDelegateSwizzlerTests {
         try sut.install()
     }
 
-    func whenInitializingURLSessionWithDummyDelegate() {
-        let originalDelegate = DummyURLSessionDelegate()
+    func whenInitializingURLSessionWithDelegate(_ delegate: URLSessionDelegate = DummyURLSessionDelegate()) {
         session = URLSession(configuration: .default,
-                             delegate: originalDelegate,
+                             delegate: delegate,
                              delegateQueue: nil)
     }
 
@@ -62,7 +69,14 @@ private extension URLSessionInitWithDelegateSwizzlerTests {
         XCTAssertTrue(session.delegate.self is URLSessionDelegateProxy)
     }
 
+    func thenSessionsDelegateShouldntBeEmbracesProxy() {
+        XCTAssertFalse(session.delegate.self is URLSessionDelegateProxy)
+    }
+
     func thenBaseClassShouldBeURLSession() {
         XCTAssertTrue(sut.baseClass == URLSession.self)
     }
 }
+
+// unsupported delegates
+class GTMSessionFetcher: NSObject, URLSessionDelegate {}