KTOR-6182 Support throwing UnknownServiceException if there is no cleartext traffic permitted

ktor-client/ktor-client-cio/jvm/src/io/ktor/client/engine/cio/Platform.kt

@@ -0,0 +1,61 @@
+/*
+ * Copyright 2014-2023 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
+ */
+
+package io.ktor.client.engine.cio
+
+import java.lang.reflect.InvocationTargetException
+
+internal actual object Platform {
+    /**
+     * This explicit check avoids activating in Android Studio with Android specific classes available when running plugins inside the IDE.
+     */
+    private val isAndroid: Boolean = System.getProperty("java.vm.name") == "Dalvik"
+
+    actual fun isCleartextTrafficPermitted(hostname: String): Boolean {
+        if (!isAndroid) return true
+        return try {
+            val networkPolicyClass = Class.forName("android.security.NetworkSecurityPolicy")
+            val getInstanceMethod = networkPolicyClass.getMethod("getInstance").apply { isAccessible = true }
+            val networkSecurityPolicy = getInstanceMethod.invoke(null)
+            api24IsCleartextTrafficPermitted(hostname, networkPolicyClass, networkSecurityPolicy)
+        } catch (_: ClassNotFoundException) {
+            true
+        } catch (_: NoSuchMethodException) {
+            true
+        } catch (e: IllegalAccessException) {
+            throw AssertionError("unable to determine cleartext support", e)
+        } catch (e: IllegalArgumentException) {
+            throw AssertionError("unable to determine cleartext support", e)
+        } catch (e: InvocationTargetException) {
+            throw AssertionError("unable to determine cleartext support", e)
+        }
+    }
+
+    @Throws(InvocationTargetException::class, IllegalAccessException::class)
+    private fun api24IsCleartextTrafficPermitted(
+        hostname: String,
+        networkPolicyClass: Class<*>,
+        networkSecurityPolicy: Any
+    ): Boolean = try {
+        val isCleartextTrafficPermittedMethod = networkPolicyClass
+            .getMethod("isCleartextTrafficPermitted", String::class.java)
+            .apply { isAccessible = true }
+        isCleartextTrafficPermittedMethod.invoke(networkSecurityPolicy, hostname) as Boolean
+    } catch (_: NoSuchMethodException) {
+        api23IsCleartextTrafficPermitted(networkPolicyClass, networkSecurityPolicy)
+    }
+
+    @Throws(InvocationTargetException::class, IllegalAccessException::class)
+    private fun api23IsCleartextTrafficPermitted(
+        networkPolicyClass: Class<*>,
+        networkSecurityPolicy: Any
+    ): Boolean = try {
+        val isCleartextTrafficPermittedMethod = networkPolicyClass
+            .getMethod("isCleartextTrafficPermitted")
+            .apply { isAccessible = true }
+        isCleartextTrafficPermittedMethod.invoke(networkSecurityPolicy) as Boolean
+    } catch (_: NoSuchMethodException) {
+        true
+    }
+}

ktor-client/ktor-client-cio/jvmAndNix/src/io/ktor/client/engine/cio/Endpoint.kt

@@ -16,6 +16,7 @@ import io.ktor.util.*
 import io.ktor.util.date.*
 import io.ktor.utils.io.*
 import io.ktor.utils.io.core.*
+import io.ktor.utils.io.errors.UnknownServiceException
 import kotlinx.atomicfu.*
 import kotlinx.coroutines.*
 import kotlinx.coroutines.channels.*
@@ -199,6 +200,12 @@ internal class Endpoint(
         connections.incrementAndGet()
 
         try {
+            if (!Platform.isCleartextTrafficPermitted(host)) {
+                throw UnknownServiceException(
+                    "CLEARTEXT communication to $host not permitted by network security policy"
+                )
+            }
+
             repeat(connectAttempts) {
                 val address = InetSocketAddress(host, port)
 

ktor-client/ktor-client-cio/jvmAndNix/src/io/ktor/client/engine/cio/Platform.kt

@@ -0,0 +1,10 @@
+/*
+ * Copyright 2014-2023 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
+ */
+
+package io.ktor.client.engine.cio
+
+internal expect object Platform {
+
+    fun isCleartextTrafficPermitted(hostname: String): Boolean
+}

ktor-client/ktor-client-cio/nix/src/io/ktor/client/engine/cio/Platform.kt

@@ -0,0 +1,9 @@
+/*
+ * Copyright 2014-2023 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
+ */
+
+package io.ktor.client.engine.cio
+
+internal actual object Platform {
+    actual fun isCleartextTrafficPermitted(hostname: String): Boolean = true
+}

ktor-io/common/src/io/ktor/utils/io/errors/Errors.kt

@@ -5,3 +5,5 @@ public expect open class IOException(message: String, cause: Throwable?) : Excep
 }
 
 public expect open class EOFException(message: String) : IOException
+
+public expect open class UnknownServiceException(message: String) : IOException

ktor-io/jvm/src/io/ktor/utils/io/errors/IOException.kt

@@ -3,3 +3,5 @@ package io.ktor.utils.io.errors
 public actual typealias IOException = java.io.IOException
 
 public actual typealias EOFException = java.io.EOFException
+
+public actual typealias UnknownServiceException = java.net.UnknownServiceException