auth: redo implementation with a cleaner and simpler API surface (#741)

3 files changed, 74 insertions, 89 deletions

diff --git a/app/src/main/java/com/zeapo/pwdstore/utils/BiometricAuthenticator.kt b/app/src/main/java/com/zeapo/pwdstore/utils/BiometricAuthenticator.kt
new file mode 100644
index 00000000..36d1f8f4
--- /dev/null
+++ b/app/src/main/java/com/zeapo/pwdstore/utils/BiometricAuthenticator.kt
@@ -0,0 +1,74 @@
+/*
+ * Copyright © 2014-2020 The Android Password Store Authors. All Rights Reserved.
+ * SPDX-License-Identifier: GPL-3.0-only
+ */
+package com.zeapo.pwdstore.utils
+
+import android.app.KeyguardManager
+import android.os.Handler
+import androidx.annotation.StringRes
+import androidx.biometric.BiometricConstants
+import androidx.biometric.BiometricManager
+import androidx.biometric.BiometricPrompt
+import androidx.core.content.getSystemService
+import androidx.fragment.app.FragmentActivity
+import com.github.ajalt.timberkt.Timber.tag
+import com.github.ajalt.timberkt.d
+import com.zeapo.pwdstore.R
+
+object BiometricAuthenticator {
+    private const val TAG = "BiometricAuthenticator"
+    private val handler = Handler()
+
+    sealed class Result {
+        data class Success(val cryptoObject: BiometricPrompt.CryptoObject?) : Result()
+        data class Failure(val code: Int?, val message: CharSequence) : Result()
+        object HardwareUnavailableOrDisabled : Result()
+        object Cancelled : Result()
+    }
+
+    fun authenticate(
+        activity: FragmentActivity,
+        @StringRes dialogTitleRes: Int = R.string.biometric_prompt_title,
+        callback: (Result) -> Unit
+    ) {
+        val authCallback = object : BiometricPrompt.AuthenticationCallback() {
+            override fun onAuthenticationError(errorCode: Int, errString: CharSequence) {
+                super.onAuthenticationError(errorCode, errString)
+                tag(TAG).d { "BiometricAuthentication error: errorCode=$errorCode, msg=$errString" }
+                callback(when (errorCode) {
+                    BiometricConstants.ERROR_CANCELED, BiometricConstants.ERROR_USER_CANCELED,
+                    BiometricConstants.ERROR_NEGATIVE_BUTTON -> {
+                        Result.Cancelled
+                    }
+                    BiometricConstants.ERROR_HW_NOT_PRESENT, BiometricConstants.ERROR_HW_UNAVAILABLE,
+                    BiometricConstants.ERROR_NO_BIOMETRICS, BiometricConstants.ERROR_NO_DEVICE_CREDENTIAL -> {
+                        Result.HardwareUnavailableOrDisabled
+                    }
+                    else -> Result.Failure(errorCode, activity.getString(R.string.biometric_auth_error_reason, errString))
+                })
+            }
+
+            override fun onAuthenticationFailed() {
+                super.onAuthenticationFailed()
+                callback(Result.Failure(null, activity.getString(R.string.biometric_auth_error)))
+            }
+
+            override fun onAuthenticationSucceeded(result: BiometricPrompt.AuthenticationResult) {
+                super.onAuthenticationSucceeded(result)
+                callback(Result.Success(result.cryptoObject))
+            }
+        }
+        val biometricPrompt = BiometricPrompt(activity, { handler.post(it) }, authCallback)
+        val promptInfo = BiometricPrompt.PromptInfo.Builder()
+                .setTitle(activity.getString(dialogTitleRes))
+                .setDeviceCredentialAllowed(true)
+                .build()
+        if (BiometricManager.from(activity).canAuthenticate() == BiometricManager.BIOMETRIC_SUCCESS ||
+                activity.getSystemService<KeyguardManager>()?.isDeviceSecure == true) {
+            biometricPrompt.authenticate(promptInfo)
+        } else {
+            callback(Result.HardwareUnavailableOrDisabled)
+        }
+    }
+}
diff --git a/app/src/main/java/com/zeapo/pwdstore/utils/auth/AuthenticationResult.kt b/app/src/main/java/com/zeapo/pwdstore/utils/auth/AuthenticationResult.kt
deleted file mode 100644
index 6bde6360..00000000
--- a/app/src/main/java/com/zeapo/pwdstore/utils/auth/AuthenticationResult.kt
+++ /dev/null
@@ -1,21 +0,0 @@
-/*
- * Copyright © 2014-2020 The Android Password Store Authors. All Rights Reserved.
- * SPDX-License-Identifier: GPL-3.0-only
- */
-package com.zeapo.pwdstore.utils.auth
-
-import androidx.biometric.BiometricPrompt
-
-internal sealed class AuthenticationResult {
-    internal data class Success(val cryptoObject: BiometricPrompt.CryptoObject?) :
-            AuthenticationResult()
-
-    internal data class RecoverableError(val code: Int, val message: CharSequence) :
-            AuthenticationResult()
-
-    internal data class UnrecoverableError(val code: Int, val message: CharSequence) :
-            AuthenticationResult()
-
-    internal object Failure : AuthenticationResult()
-    internal object Cancelled : AuthenticationResult()
-}
diff --git a/app/src/main/java/com/zeapo/pwdstore/utils/auth/Authenticator.kt b/app/src/main/java/com/zeapo/pwdstore/utils/auth/Authenticator.kt
deleted file mode 100644
index 34fc9455..00000000
--- a/app/src/main/java/com/zeapo/pwdstore/utils/auth/Authenticator.kt
+++ /dev/null
@@ -1,68 +0,0 @@
-/*
- * Copyright © 2014-2020 The Android Password Store Authors. All Rights Reserved.
- * SPDX-License-Identifier: GPL-3.0-only
- */
-package com.zeapo.pwdstore.utils.auth
-
-import android.os.Handler
-import androidx.biometric.BiometricManager
-import androidx.biometric.BiometricPrompt
-import androidx.fragment.app.FragmentActivity
-import com.github.ajalt.timberkt.Timber.tag
-import com.github.ajalt.timberkt.d
-import com.zeapo.pwdstore.R
-
-internal class Authenticator(
-    private val fragmentActivity: FragmentActivity,
-    private val callback: (AuthenticationResult) -> Unit
-) {
-    private val handler = Handler()
-    private val biometricManager = BiometricManager.from(fragmentActivity)
-
-    private val authCallback = object : BiometricPrompt.AuthenticationCallback() {
-
-        override fun onAuthenticationError(errorCode: Int, errString: CharSequence) {
-            super.onAuthenticationError(errorCode, errString)
-            tag(TAG).d { "Error: $errorCode: $errString" }
-            callback(AuthenticationResult.UnrecoverableError(errorCode, errString))
-        }
-
-        override fun onAuthenticationFailed() {
-            super.onAuthenticationFailed()
-            tag(TAG).d { "Failed" }
-            callback(AuthenticationResult.Failure)
-        }
-
-        override fun onAuthenticationSucceeded(result: BiometricPrompt.AuthenticationResult) {
-            super.onAuthenticationSucceeded(result)
-            tag(TAG).d { "Success" }
-            callback(AuthenticationResult.Success(result.cryptoObject))
-        }
-    }
-
-    private val biometricPrompt = BiometricPrompt(
-            fragmentActivity,
-            { runnable -> handler.post(runnable) },
-            authCallback
-    )
-
-    private val promptInfo = BiometricPrompt.PromptInfo.Builder()
-            .setTitle(fragmentActivity.getString(R.string.biometric_prompt_title))
-            .setDeviceCredentialAllowed(true)
-            .build()
-
-    fun authenticate() {
-        if (biometricManager.canAuthenticate() != BiometricManager.BIOMETRIC_SUCCESS) {
-            callback(AuthenticationResult.UnrecoverableError(
-                    0,
-                    fragmentActivity.getString(R.string.biometric_prompt_no_hardware)
-            ))
-        } else {
-            biometricPrompt.authenticate(promptInfo)
-        }
-    }
-
-    companion object {
-        private const val TAG = "Authenticator"
-    }
-}