From a0b0ee2b13b72d1ec6a489150c717c8bfa863158 Mon Sep 17 00:00:00 2001
From: Torsten Grote <t@grobox.de>
Date: Tue, 1 Sep 2020 09:49:05 -0300
Subject: [cashier] check authentication credentials against auth endpoint

before accepting config

This was an unannounced change at the server which removed auth from the
/config endpoint.
---
 .../src/main/java/net/taler/cashier/Response.kt    |  2 +-
 .../java/net/taler/cashier/config/ConfigManager.kt | 37 +++++++++++++++-------
 2 files changed, 26 insertions(+), 13 deletions(-)

(limited to 'cashier/src/main')

diff --git a/cashier/src/main/java/net/taler/cashier/Response.kt b/cashier/src/main/java/net/taler/cashier/Response.kt
index 0ad39d0..c5b1c32 100644
--- a/cashier/src/main/java/net/taler/cashier/Response.kt
+++ b/cashier/src/main/java/net/taler/cashier/Response.kt
@@ -55,7 +55,7 @@ class Response<out T> private constructor(
         }
     }
 
-    private val isFailure: Boolean get() = value is Failure
+    val isFailure: Boolean get() = value is Failure
 
     suspend fun onSuccess(block: suspend (result: T) -> Unit): Response<T> {
         @Suppress("UNCHECKED_CAST")
diff --git a/cashier/src/main/java/net/taler/cashier/config/ConfigManager.kt b/cashier/src/main/java/net/taler/cashier/config/ConfigManager.kt
index a18073d..f83c7ba 100644
--- a/cashier/src/main/java/net/taler/cashier/config/ConfigManager.kt
+++ b/cashier/src/main/java/net/taler/cashier/config/ConfigManager.kt
@@ -24,7 +24,10 @@ import androidx.annotation.WorkerThread
 import androidx.lifecycle.LiveData
 import androidx.lifecycle.MutableLiveData
 import androidx.security.crypto.EncryptedSharedPreferences
+import androidx.security.crypto.EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV
+import androidx.security.crypto.EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
 import androidx.security.crypto.MasterKeys
+import androidx.security.crypto.MasterKeys.AES256_GCM_SPEC
 import io.ktor.client.HttpClient
 import io.ktor.client.request.get
 import io.ktor.client.request.header
@@ -56,11 +59,9 @@ class ConfigManager(
 
     val configDestination = ConfigFragmentDirections.actionGlobalConfigFragment()
 
-    private val masterKeyAlias = MasterKeys.getOrCreate(MasterKeys.AES256_GCM_SPEC)
+    private val masterKeyAlias = MasterKeys.getOrCreate(AES256_GCM_SPEC)
     private val prefs = EncryptedSharedPreferences.create(
-        PREF_NAME, masterKeyAlias, app,
-        EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
-        EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
+        PREF_NAME, masterKeyAlias, app, AES256_SIV, AES256_GCM
     )
 
     internal var config = Config(
@@ -111,17 +112,29 @@ class ConfigManager(
         }
     }
 
-    private suspend fun checkConfig(config: Config): Response<ConfigResponse> =
-        withContext(Dispatchers.IO) {
-            val url = "${config.bankUrl}/config"
-            Log.d(TAG, "Checking config: $url")
-            response {
-                httpClient.get(url) {
-                    // TODO why does that not fail already?
+    private suspend fun checkConfig(config: Config) = withContext(Dispatchers.IO) {
+        val url = "${config.bankUrl}/config"
+        Log.d(TAG, "Checking config: $url")
+        val configResponse = response {
+            httpClient.get(url) as ConfigResponse
+        }
+        if (configResponse.isFailure) {
+            configResponse
+        } else {
+            // we need to check an endpoint that requires authentication as well
+            // to see if the credentials are valid
+            val balanceResponse = response {
+                val authUrl = "${config.bankUrl}/accounts/${config.username}/balance"
+                Log.d(TAG, "Checking auth: $authUrl")
+                httpClient.get<Unit>(authUrl) {
                     header(Authorization, config.basicAuth)
-                } as ConfigResponse
+                }
             }
+            @Suppress("UNCHECKED_CAST")  // The type doesn't matter for failures
+            if (balanceResponse.isFailure) balanceResponse as Response<ConfigResponse>
+            else configResponse
         }
+    }
 
     @WorkerThread
     @SuppressLint("ApplySharedPref")
-- 
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