Refactor gateway service

.vscode/tasks.json

@@ -3,7 +3,7 @@
     "tasks": [
         {
             "type": "meson",
-            "target": "credentialsd",
+            "target": "credentialsd/src/credentialsd:custom",
             "mode": "build",
             "problemMatcher": [
                 "$meson-gcc"
@@ -13,7 +13,7 @@
         },
         {
             "type": "meson",
-            "target": "credentialsd-ui",
+            "target": "credentialsd-ui/src/credentialsd-ui:custom",
             "mode": "build",
             "problemMatcher": [
                 "$meson-gcc"

ARCHITECTURE.md

@@ -103,11 +103,15 @@ Actual interaction I/O is performed in the [libwebauthn][libwebauthn] library.
 
 [libwebauthn]: https://github.com/linux-credentials/libwebauthn
 
+### `credentialsd/src/gateway/`
+
+The Gateway service is defined here, along with its D-Bus interface.
+
 ### `credentialsd/src/dbus/`
 
 D-Bus clients and services.
 
-The Gateway and Flow Controller services are defined here, as well as a client
+The Flow Controller services are defined here, as well as a client
 for the UI Controller.
 
 The `model` module contains some methods to convert from D-Bus types to internal

credentialsd/Cargo.toml

@@ -7,6 +7,7 @@ license = "LGPL-3.0-only"
 
 [dependencies]
 async-stream = "0.3.6"
+async-trait = "0.1.89"
 base64 = "0.22.1"
 credentialsd-common = { path = "../credentialsd-common" }
 futures-lite.workspace = true

credentialsd/src/dbus/flow_control.rs

@@ -1,9 +1,9 @@
 //! This module implements the service to allow the user to control the flow of
 //! the credential request through the trusted UI.
 
-use std::future::Future;
 use std::{collections::VecDeque, fmt::Debug, sync::Arc};
 
+use async_trait::async_trait;
 use credentialsd_common::model::{
     BackgroundEvent, Device, Error as CredentialServiceError, RequestingApplication, WebAuthnError,
 };
@@ -341,13 +341,16 @@ enum SignalState {
     Active,
 }
 
+/// Coordinates between user and various devices connected to the machine to
+/// fulfill credential requests.
+#[async_trait]
 pub trait CredentialRequestController {
-    fn request_credential(
+    async fn request_credential(
         &self,
         requesting_app: Option<RequestingApplication>,
         request: CredentialRequest,
         window_handle: Option<WindowHandle>,
-    ) -> impl Future<Output = Result<CredentialResponse, WebAuthnError>> + Send;
+    ) -> Result<CredentialResponse, WebAuthnError>;
 }
 
 pub struct CredentialRequestControllerClient {
@@ -359,6 +362,7 @@ pub struct CredentialRequestControllerClient {
     )>,
 }
 
+#[async_trait]
 impl CredentialRequestController for CredentialRequestControllerClient {
     async fn request_credential(
         &self,