1 files changed, 43 insertions, 3 deletions
diff --git a/android/lib/common/src/main/kotlin/net/mullvad/mullvadvpn/lib/common/util/VpnServiceUtils.kt b/android/lib/common/src/main/kotlin/net/mullvad/mullvadvpn/lib/common/util/VpnServiceUtils.kt
index 59833cb396..06c862936b 100644
--- a/android/lib/common/src/main/kotlin/net/mullvad/mullvadvpn/lib/common/util/VpnServiceUtils.kt
+++ b/android/lib/common/src/main/kotlin/net/mullvad/mullvadvpn/lib/common/util/VpnServiceUtils.kt
@@ -2,10 +2,14 @@ package net.mullvad.mullvadvpn.lib.common.util
 
 import android.content.Context
 import android.content.Intent
+import android.net.VpnService
 import android.net.VpnService.prepare
+import android.os.ParcelFileDescriptor
 import arrow.core.Either
-import arrow.core.flatten
+import arrow.core.flatMap
 import arrow.core.left
+import arrow.core.raise.either
+import arrow.core.raise.ensureNotNull
 import arrow.core.right
 import co.touchlab.kermit.Logger
 import net.mullvad.mullvadvpn.lib.common.util.SdkUtils.getInstalledPackagesList
@@ -13,6 +17,8 @@ import net.mullvad.mullvadvpn.lib.model.PrepareError
 import net.mullvad.mullvadvpn.lib.model.Prepared
 
 /**
+ * Prepare to establish a VPN connection safely.
+ *
  * Invoking VpnService.prepare() can result in 3 out comes:
  * 1. IllegalStateException - There is a legacy VPN profile marked as always on
  * 2. Intent
@@ -34,7 +40,7 @@ fun Context.prepareVpnSafe(): Either<PrepareError, Prepared> =
                 else -> throw it
             }
         }
-        .map { intent ->
+        .flatMap { intent ->
             if (intent == null) {
                 Prepared.right()
             } else {
@@ -46,7 +52,6 @@ fun Context.prepareVpnSafe(): Either<PrepareError, Prepared> =
                 }
             }
         }
-        .flatten()
 
 fun Context.getAlwaysOnVpnAppName(): String? {
     return resolveAlwaysOnVpnPackageName()
@@ -59,3 +64,38 @@ fun Context.getAlwaysOnVpnAppName(): String? {
         ?.loadLabel(packageManager)
         ?.toString()
 }
+
+/**
+ * Establish a VPN connection safely.
+ *
+ * This function wraps the [VpnService.Builder.establish] function and catches any exceptions that
+ * may be thrown and type them to a more specific error.
+ *
+ * @return [ParcelFileDescriptor] if successful, [EstablishError] otherwise
+ */
+fun VpnService.Builder.establishSafe(): Either<EstablishError, ParcelFileDescriptor> = either {
+    val vpnInterfaceFd =
+        Either.catch { establish() }
+            .mapLeft {
+                when (it) {
+                    is IllegalStateException -> EstablishError.ParameterNotApplied(it)
+                    is IllegalArgumentException -> EstablishError.ParameterNotAccepted(it)
+                    else -> EstablishError.UnknownError(it)
+                }
+            }
+            .bind()
+
+    ensureNotNull(vpnInterfaceFd) { EstablishError.NullVpnInterface }
+
+    vpnInterfaceFd
+}
+
+sealed interface EstablishError {
+    data class ParameterNotApplied(val exception: IllegalStateException) : EstablishError
+
+    data class ParameterNotAccepted(val exception: IllegalArgumentException) : EstablishError
+
+    data object NullVpnInterface : EstablishError
+
+    data class UnknownError(val error: Throwable) : EstablishError
+}