Ensure that when no Matrix gateway exists, the default one is used.

libraries/pushproviders/unifiedpush/src/main/kotlin/io/element/android/libraries/pushproviders/unifiedpush/UnifiedPushGatewayResolver.kt

@@ -12,12 +12,21 @@ import io.element.android.libraries.core.coroutine.CoroutineDispatchers
 import io.element.android.libraries.core.data.tryOrNull
 import io.element.android.libraries.di.AppScope
 import kotlinx.coroutines.withContext
+import retrofit2.HttpException
 import timber.log.Timber
+import java.net.HttpURLConnection
 import java.net.URL
 import javax.inject.Inject
 
+sealed interface UnifiedPushGatewayResolverResult {
+    data class Success(val gateway: String) : UnifiedPushGatewayResolverResult
+    data class Error(val gateway: String) : UnifiedPushGatewayResolverResult
+    data object NoMatrixGateway : UnifiedPushGatewayResolverResult
+    data object ErrorInvalidUrl : UnifiedPushGatewayResolverResult
+}
+
 interface UnifiedPushGatewayResolver {
-    suspend fun getGateway(endpoint: String): String
+    suspend fun getGateway(endpoint: String): UnifiedPushGatewayResolverResult
 }
 
 @ContributesBinding(AppScope::class)
@@ -27,7 +36,7 @@ class DefaultUnifiedPushGatewayResolver @Inject constructor(
 ) : UnifiedPushGatewayResolver {
     private val logger = Timber.tag("DefaultUnifiedPushGatewayResolver")
 
-    override suspend fun getGateway(endpoint: String): String {
+    override suspend fun getGateway(endpoint: String): UnifiedPushGatewayResolverResult {
         val url = tryOrNull(
             onError = { logger.d(it, "Cannot parse endpoint as an URL") }
         ) {
@@ -35,7 +44,7 @@ class DefaultUnifiedPushGatewayResolver @Inject constructor(
         }
         return if (url == null) {
             logger.d("Using default gateway")
-            UnifiedPushConfig.DEFAULT_PUSH_GATEWAY_HTTP_URL
+            UnifiedPushGatewayResolverResult.ErrorInvalidUrl
         } else {
             val port = if (url.port != -1) ":${url.port}" else ""
             val customBase = "${url.protocol}://${url.host}$port"
@@ -47,14 +56,21 @@ class DefaultUnifiedPushGatewayResolver @Inject constructor(
                     val discoveryResponse = api.discover()
                     if (discoveryResponse.unifiedpush.gateway == "matrix") {
                         logger.d("The endpoint seems to be a valid UnifiedPush gateway")
+                        UnifiedPushGatewayResolverResult.Success(customUrl)
                     } else {
-                        logger.e("The endpoint does not seem to be a valid UnifiedPush gateway")
+                        // The endpoint returned a 200 OK but didn't promote an actual matrix gateway, which means it doesn't have any
+                        logger.w("The endpoint does not seem to be a valid UnifiedPush gateway, using fallback")
+                        UnifiedPushGatewayResolverResult.NoMatrixGateway
                     }
                 } catch (throwable: Throwable) {
-                    logger.e(throwable, "Error checking for UnifiedPush endpoint")
+                    if ((throwable as? HttpException)?.code() == HttpURLConnection.HTTP_NOT_FOUND) {
+                        logger.i("Checking for UnifiedPush endpoint yielded 404, using fallback")
+                        UnifiedPushGatewayResolverResult.NoMatrixGateway
+                    } else {
+                        logger.e(throwable, "Error checking for UnifiedPush endpoint")
+                        UnifiedPushGatewayResolverResult.Error(customUrl)
+                    }
                 }
-                // Always return the custom url.
-                customUrl
             }
         }
     }

libraries/pushproviders/unifiedpush/src/main/kotlin/io/element/android/libraries/pushproviders/unifiedpush/VectorUnifiedPushMessagingReceiver.kt

@@ -64,6 +64,21 @@ class VectorUnifiedPushMessagingReceiver : MessagingReceiver() {
         Timber.tag(loggerTag.value).i("onNewEndpoint: $endpoint")
         coroutineScope.launch {
             val gateway = unifiedPushGatewayResolver.getGateway(endpoint)
+                .let { gatewayResult ->
+                    when (gatewayResult) {
+                        is UnifiedPushGatewayResolverResult.Error -> {
+                            // Use previous gateway if any, or the provided one
+                            unifiedPushStore.getPushGateway(instance) ?: gatewayResult.gateway
+                        }
+                        UnifiedPushGatewayResolverResult.ErrorInvalidUrl,
+                        UnifiedPushGatewayResolverResult.NoMatrixGateway -> {
+                            UnifiedPushConfig.DEFAULT_PUSH_GATEWAY_HTTP_URL
+                        }
+                        is UnifiedPushGatewayResolverResult.Success -> {
+                            gatewayResult.gateway
+                        }
+                    }
+                }
             unifiedPushStore.storePushGateway(instance, gateway)
             val result = newGatewayHandler.handle(endpoint, gateway, instance)
                 .onFailure {

libraries/pushproviders/unifiedpush/src/test/kotlin/io/element/android/libraries/pushproviders/unifiedpush/DefaultUnifiedPushGatewayResolverTest.kt

@@ -43,7 +43,7 @@ class DefaultUnifiedPushGatewayResolverTest {
         )
         val result = sut.getGateway("https://custom.url")
         assertThat(unifiedPushApiFactory.baseUrlParameter).isEqualTo("https://custom.url")
-        assertThat(result).isEqualTo("https://custom.url/_matrix/push/v1/notify")
+        assertThat(result).isEqualTo(UnifiedPushGatewayResolverResult.Success("https://custom.url/_matrix/push/v1/notify"))
     }
 
     @Test
@@ -56,7 +56,7 @@ class DefaultUnifiedPushGatewayResolverTest {
         )
         val result = sut.getGateway("https://custom.url:123")
         assertThat(unifiedPushApiFactory.baseUrlParameter).isEqualTo("https://custom.url:123")
-        assertThat(result).isEqualTo("https://custom.url:123/_matrix/push/v1/notify")
+        assertThat(result).isEqualTo(UnifiedPushGatewayResolverResult.Success("https://custom.url:123/_matrix/push/v1/notify"))
     }
 
     @Test
@@ -69,7 +69,7 @@ class DefaultUnifiedPushGatewayResolverTest {
         )
         val result = sut.getGateway("https://custom.url:123/some/path")
         assertThat(unifiedPushApiFactory.baseUrlParameter).isEqualTo("https://custom.url:123")
-        assertThat(result).isEqualTo("https://custom.url:123/_matrix/push/v1/notify")
+        assertThat(result).isEqualTo(UnifiedPushGatewayResolverResult.Success("https://custom.url:123/_matrix/push/v1/notify"))
     }
 
     @Test
@@ -82,7 +82,7 @@ class DefaultUnifiedPushGatewayResolverTest {
         )
         val result = sut.getGateway("http://custom.url:123/some/path")
         assertThat(unifiedPushApiFactory.baseUrlParameter).isEqualTo("http://custom.url:123")
-        assertThat(result).isEqualTo("http://custom.url:123/_matrix/push/v1/notify")
+        assertThat(result).isEqualTo(UnifiedPushGatewayResolverResult.Success("http://custom.url:123/_matrix/push/v1/notify"))
     }
 
     @Test
@@ -95,11 +95,11 @@ class DefaultUnifiedPushGatewayResolverTest {
         )
         val result = sut.getGateway("http://custom.url")
         assertThat(unifiedPushApiFactory.baseUrlParameter).isEqualTo("http://custom.url")
-        assertThat(result).isEqualTo("http://custom.url/_matrix/push/v1/notify")
+        assertThat(result).isEqualTo(UnifiedPushGatewayResolverResult.Error("http://custom.url/_matrix/push/v1/notify"))
     }
 
     @Test
-    fun `when a custom url is invalid, the default url is returned`() = runTest {
+    fun `when a custom url is invalid, ErrorInvalidUrl is returned`() = runTest {
         val unifiedPushApiFactory = FakeUnifiedPushApiFactory(
             discoveryResponse = matrixDiscoveryResponse
         )
@@ -108,11 +108,11 @@ class DefaultUnifiedPushGatewayResolverTest {
         )
         val result = sut.getGateway("invalid")
         assertThat(unifiedPushApiFactory.baseUrlParameter).isNull()
-        assertThat(result).isEqualTo(UnifiedPushConfig.DEFAULT_PUSH_GATEWAY_HTTP_URL)
+        assertThat(result).isEqualTo(UnifiedPushGatewayResolverResult.ErrorInvalidUrl)
     }
 
     @Test
-    fun `when a custom url provides a invalid matrix gateway, the custom url is still returned`() = runTest {
+    fun `when a custom url provides a invalid matrix gateway, NoMatrixGateway is returned`() = runTest {
         val unifiedPushApiFactory = FakeUnifiedPushApiFactory(
             discoveryResponse = invalidDiscoveryResponse
         )
@@ -121,7 +121,7 @@ class DefaultUnifiedPushGatewayResolverTest {
         )
         val result = sut.getGateway("https://custom.url")
         assertThat(unifiedPushApiFactory.baseUrlParameter).isEqualTo("https://custom.url")
-        assertThat(result).isEqualTo("https://custom.url/_matrix/push/v1/notify")
+        assertThat(result).isEqualTo(UnifiedPushGatewayResolverResult.NoMatrixGateway)
     }
 
     private fun TestScope.createDefaultUnifiedPushGatewayResolver(

libraries/pushproviders/unifiedpush/src/test/kotlin/io/element/android/libraries/pushproviders/unifiedpush/FakeUnifiedPushGatewayResolver.kt

@@ -10,9 +10,9 @@ package io.element.android.libraries.pushproviders.unifiedpush
 import io.element.android.tests.testutils.lambda.lambdaError
 
 class FakeUnifiedPushGatewayResolver(
-    private val getGatewayResult: (String) -> String = { lambdaError() },
+    private val getGatewayResult: (String) -> UnifiedPushGatewayResolverResult = { lambdaError() },
 ) : UnifiedPushGatewayResolver {
-    override suspend fun getGateway(endpoint: String): String {
+    override suspend fun getGateway(endpoint: String): UnifiedPushGatewayResolverResult {
         return getGatewayResult(endpoint)
     }
 }

libraries/pushproviders/unifiedpush/src/test/kotlin/io/element/android/libraries/pushproviders/unifiedpush/VectorUnifiedPushMessagingReceiverTest.kt

@@ -104,7 +104,7 @@ class VectorUnifiedPushMessagingReceiverTest {
         val vectorUnifiedPushMessagingReceiver = createVectorUnifiedPushMessagingReceiver(
             unifiedPushStore = unifiedPushStore,
             unifiedPushGatewayResolver = FakeUnifiedPushGatewayResolver(
-                getGatewayResult = { "aGateway" }
+                getGatewayResult = { UnifiedPushGatewayResolverResult.Success("aGateway") }
             ),
             endpointRegistrationHandler = endpointRegistrationHandler,
             unifiedPushNewGatewayHandler = unifiedPushNewGatewayHandler,
@@ -144,7 +144,7 @@ class VectorUnifiedPushMessagingReceiverTest {
         val vectorUnifiedPushMessagingReceiver = createVectorUnifiedPushMessagingReceiver(
             unifiedPushStore = unifiedPushStore,
             unifiedPushGatewayResolver = FakeUnifiedPushGatewayResolver(
-                getGatewayResult = { "aGateway" }
+                getGatewayResult = { UnifiedPushGatewayResolverResult.Success("aGateway") }
             ),
             endpointRegistrationHandler = endpointRegistrationHandler,
             unifiedPushNewGatewayHandler = unifiedPushNewGatewayHandler,