Add SettingsProvider interface for settings

lib/src/androidTest/java/at/bitfire/cert4android/OkhttpTest.kt

@@ -59,8 +59,10 @@ class OkhttpTest {
         // set cert4android TrustManager and HostnameVerifier
         val certManager = CustomCertManager(
             CustomCertStore.getInstance(context),
-            trustSystemCerts = true,
-            appInForeground = null
+            object : SettingsProvider {
+                override val appInForeground = null
+                override val trustSystemCerts = true
+            }
         )
 
         val sslContext = SSLContext.getInstance("TLS")

lib/src/main/java/at/bitfire/cert4android/CertStore.kt

@@ -10,7 +10,6 @@
 
 package at.bitfire.cert4android
 
-import kotlinx.coroutines.flow.StateFlow
 import java.security.cert.X509Certificate
 
 interface CertStore {
@@ -23,7 +22,7 @@ interface CertStore {
     /**
      * Determines whether a certificate chain is trusted.
      */
-    fun isTrusted(chain: Array<X509Certificate>, authType: String, trustSystemCerts: Boolean, appInForeground: StateFlow<Boolean>?): Boolean
+    fun isTrusted(chain: Array<X509Certificate>, authType: String, trustSystemCerts: Boolean, appInForeground: Boolean?): Boolean
 
     /**
      * Determines whether a certificate has been explicitly accepted by the user. In this case,

lib/src/main/java/at/bitfire/cert4android/CustomCertManager.kt

@@ -11,7 +11,6 @@
 package at.bitfire.cert4android
 
 import android.annotation.SuppressLint
-import kotlinx.coroutines.flow.StateFlow
 import java.security.cert.CertificateException
 import java.security.cert.X509Certificate
 import java.util.logging.Logger
@@ -21,16 +20,13 @@ import javax.net.ssl.X509TrustManager
 /**
  * TrustManager to handle custom certificates.
  *
- * @param trustSystemCerts whether system certificates will be trusted
- * @param appInForeground  - `true`: if needed, directly launches [TrustCertificateActivity] and shows notification (if possible)
- *                         - `false`: if needed, shows notification (if possible)
- *                         - `null`: non-interactive mode: does not show notification or launch activity
+ * @param certStore certificate store with (un)trusted certificates
+ * @param settings  settings provider to get settings from
  */
 @SuppressLint("CustomX509TrustManager")
 class CustomCertManager @JvmOverloads constructor(
     private val certStore: CertStore,
-    val trustSystemCerts: Boolean = true,
-    var appInForeground: StateFlow<Boolean>?
+    private val settings: SettingsProvider
 ): X509TrustManager {
 
     private val logger
@@ -51,7 +47,13 @@ class CustomCertManager @JvmOverloads constructor(
      */
     @Throws(CertificateException::class)
     override fun checkServerTrusted(chain: Array<X509Certificate>, authType: String) {
-        if (!certStore.isTrusted(chain, authType, trustSystemCerts, appInForeground))
+        if (!certStore.isTrusted(
+                chain,
+                authType,
+                trustSystemCerts = settings.trustSystemCerts,
+                appInForeground = settings.appInForeground
+            )
+        )
             throw CertificateException("Certificate chain not trusted")
     }
 
@@ -75,7 +77,13 @@ class CustomCertManager @JvmOverloads constructor(
             // Allow users to explicitly accept certificates that have a bad hostname here
             (session.peerCertificates.firstOrNull() as? X509Certificate)?.let { cert ->
                 // Check without trusting system certificates so that the user will be asked even for system-trusted certificates
-                if (certStore.isTrusted(arrayOf(cert), "RSA", false, appInForeground))
+                if (certStore.isTrusted(
+                        arrayOf(cert),
+                        "RSA",
+                        trustSystemCerts = false,
+                        appInForeground = settings.appInForeground
+                    )
+                )
                     return true
             }
 

lib/src/main/java/at/bitfire/cert4android/CustomCertStore.kt

@@ -14,7 +14,6 @@ import android.annotation.SuppressLint
 import android.content.Context
 import androidx.annotation.VisibleForTesting
 import kotlinx.coroutines.TimeoutCancellationException
-import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.runBlocking
 import kotlinx.coroutines.withTimeout
 import java.io.File
@@ -75,7 +74,7 @@ class CustomCertStore internal constructor(
     /**
      * Determines whether a certificate chain is trusted.
      */
-    override fun isTrusted(chain: Array<X509Certificate>, authType: String, trustSystemCerts: Boolean, appInForeground: StateFlow<Boolean>?): Boolean {
+    override fun isTrusted(chain: Array<X509Certificate>, authType: String, trustSystemCerts: Boolean, appInForeground: Boolean?): Boolean {
         if (chain.isEmpty())
             throw IllegalArgumentException("Certificate chain must not be empty")
         val cert = chain[0]
@@ -111,7 +110,7 @@ class CustomCertStore internal constructor(
 
             try {
                 withTimeout(userTimeout) {
-                    ui.check(cert, appInForeground.value)
+                    ui.check(cert, appInForeground)
                 }
             } catch (_: TimeoutCancellationException) {
                 logger.log(Level.WARNING, "User timeout while waiting for certificate decision, rejecting")

lib/src/main/java/at/bitfire/cert4android/SettingsProvider.kt

@@ -0,0 +1,37 @@
+/*
+ * Copyright © All Contributors. See LICENSE and AUTHORS in the root directory for details.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ *
+ * SPDX-License-Identifier: MPL-2.0
+ */
+
+package at.bitfire.cert4android
+
+/**
+ * Provides settings for cert4android. Implementations can override the getters.
+ *
+ * Usually implemented by the app which uses cert4android, and then passed to cert4android classes
+ * which need it.
+ */
+interface SettingsProvider {
+
+    /**
+     * The app foreground status:
+     *
+     * - `true`: foreground – directly launch UI ([TrustCertificateActivity]) and show notification (if possible)
+     * - `false`: background – only show notification (if possible)
+     * - `null`: non-interactive mode – don't show notification or launch activity
+     */
+    val appInForeground: Boolean?
+
+    /**
+     * Whether system certificates shall be trusted.
+     *
+     * @return `true` if system certificates are considered trustworthy, `false` otherwise
+     */
+    val trustSystemCerts: Boolean
+
+}

lib/src/test/java/at/bitfire/cert4android/CustomCertManagerTest.kt

@@ -36,8 +36,14 @@ class CustomCertManagerTest {
     @Before
     fun createCertManager() {
         certStore = TestCertStore()
-        certManager = CustomCertManager(certStore, true, null)
-        paranoidCertManager = CustomCertManager(certStore, false, null)
+        certManager = CustomCertManager(certStore, object : SettingsProvider {
+            override val appInForeground = null
+            override val trustSystemCerts = true
+        })
+        paranoidCertManager = CustomCertManager(certStore, object : SettingsProvider {
+            override val appInForeground = null
+            override val trustSystemCerts = false
+        })
     }
 
 

lib/src/test/java/at/bitfire/cert4android/TestCertStore.kt

@@ -11,7 +11,6 @@
 package at.bitfire.cert4android
 
 import androidx.annotation.VisibleForTesting
-import kotlinx.coroutines.flow.StateFlow
 import java.security.cert.X509Certificate
 import java.util.logging.Level
 import java.util.logging.Logger
@@ -43,7 +42,7 @@ class TestCertStore: CertStore {
     /**
      * Determines whether a certificate chain is trusted.
      */
-    override fun isTrusted(chain: Array<X509Certificate>, authType: String, trustSystemCerts: Boolean, appInForeground: StateFlow<Boolean>?): Boolean {
+    override fun isTrusted(chain: Array<X509Certificate>, authType: String, trustSystemCerts: Boolean, appInForeground: Boolean?): Boolean {
         if (chain.isEmpty())
             throw IllegalArgumentException("Certificate chain must not be empty")
         val cert = chain[0]

sample-app/src/main/java/at/bitfire/cert4android/demo/MainActivity.kt

@@ -1,3 +1,13 @@
+/*
+ * Copyright © All Contributors. See LICENSE and AUTHORS in the root directory for details.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ *
+ * SPDX-License-Identifier: MPL-2.0
+ */
+
 package at.bitfire.cert4android.demo
 
 import android.Manifest
@@ -33,6 +43,7 @@ import androidx.lifecycle.MutableLiveData
 import androidx.lifecycle.viewModelScope
 import at.bitfire.cert4android.CustomCertManager
 import at.bitfire.cert4android.CustomCertStore
+import at.bitfire.cert4android.SettingsProvider
 import at.bitfire.cert4android.ThemeManager
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.flow.MutableStateFlow
@@ -62,7 +73,7 @@ class MainActivity : ComponentActivity() {
                     .padding(8.dp)
                     .verticalScroll(rememberScrollState())) {
                     Row {
-                        Checkbox(model.appInForeground.collectAsState().value, onCheckedChange = { foreground ->
+                        Checkbox(model.foreground.collectAsState().value, onCheckedChange = { foreground ->
                             model.setInForeground(foreground)
                         })
                         Text("App in foreground")
@@ -131,7 +142,8 @@ class MainActivity : ComponentActivity() {
         val context: Context
             get() = getApplication()
 
-        val appInForeground = MutableStateFlow(true)
+        val foreground = MutableStateFlow(true)
+
         val resultMessage = MutableLiveData<String>()
 
         init {
@@ -145,7 +157,7 @@ class MainActivity : ComponentActivity() {
         }
 
         fun setInForeground(foreground: Boolean) {
-            appInForeground.value = foreground
+            this.foreground.value = foreground
         }
 
         fun testAccess(url: String, trustSystemCerts: Boolean = true) = viewModelScope.launch(Dispatchers.IO) {
@@ -177,8 +189,12 @@ class MainActivity : ComponentActivity() {
             // set cert4android TrustManager and HostnameVerifier
             val certManager = CustomCertManager(
                 certStore = CustomCertStore.getInstance(context),
-                trustSystemCerts = trustSystemCerts,
-                appInForeground = appInForeground
+                settings = object : SettingsProvider {
+                    override val appInForeground
+                        get() = foreground.value
+                    override val trustSystemCerts
+                        get() = trustSystemCerts
+                }
             )
 
             val sslContext = SSLContext.getInstance("TLS")