Launch Android broker through Termux URL handler

docs/platforms/android-client.md

@@ -1,6 +1,6 @@
 # Android CLI 客户端
 
-Termux 登录不让浏览器直接访问 Termux 的 `127.0.0.1`：CLI 通过 `/system/bin/am` 启动 APK，APK 注册 `com.nitload.charac://oauth/callback` 并接收 authentik 回调，再用 `RUN_COMMAND` 调用 `charac callback` 将授权码转回 CLI 的本地监听器。
+Termux 登录不让浏览器直接访问 Termux 的 `127.0.0.1`：CLI 通过 `termux-open-url` 启动 APK，APK 注册 `com.nitload.charac://oauth/callback` 并接收 authentik 回调，再用 `RUN_COMMAND` 调用 `charac callback` 将授权码转回 CLI 的本地监听器。
 
 推荐把 Android CLI 作为 Termux DEB 分发，而不是把 CLI 当成普通 Android APK。APK 只是可选的 One UI 启动器：它不能单独运行 CLI，必须与 Termux、Termux DEB、运行命令权限和 `allow-external-apps=true` 配置一起使用。直接安装 APK 后点击图标不能替代 Termux 环境，也不会自动安装 .NET 或 `charac`。
 

src/android/MainActivity.cs

@@ -57,6 +57,24 @@ public sealed class MainActivity : Activity
 
     private void HandleBrokerIntent(Intent intent)
     {
+        var brokerUri = intent.Data;
+        if (brokerUri?.Scheme == "com.nitload.charac" && brokerUri.Host == "oauth" &&
+            brokerUri.Path == "/start")
+        {
+            var brokerAuthorizationUrl = brokerUri.GetQueryParameter("url");
+            var portText = brokerUri.GetQueryParameter("port");
+            if (brokerAuthorizationUrl is null || !Uri.TryCreate(brokerAuthorizationUrl, UriKind.Absolute, out var parsedUrl) ||
+                parsedUrl.Scheme != Uri.UriSchemeHttps || !int.TryParse(portText, out var port) ||
+                port is <= 0 or > 65535)
+            {
+                SetStatus("OIDC 启动参数无效。请从 Termux 重新发起登录。", false);
+                return;
+            }
+
+            StartBrowserForAuthorization(parsedUrl, port);
+            return;
+        }
+
         if (intent.GetStringExtra(AuthUrlExtra) is { Length: > 0 } authorizationUrl)
         {
             var port = intent.GetIntExtra(CallbackPortExtra, 0);
@@ -85,15 +103,11 @@ public sealed class MainActivity : Activity
                 return;
             }
             updatedEditor.Apply();
-            try
-            {
-                StartActivity(new Intent(Intent.ActionView, global::Android.Net.Uri.Parse(authorizationUrl)));
-                SetStatus("已打开浏览器。完成登录后将自动返回 Termux。", false);
-            }
-            catch (Exception exception)
-            {
-                SetStatus("无法打开浏览器：" + exception.Message, false);
-            }
+            if (Uri.TryCreate(authorizationUrl, UriKind.Absolute, out var parsedUrl) &&
+                parsedUrl.Scheme == Uri.UriSchemeHttps)
+                StartBrowserForAuthorization(parsedUrl, port);
+            else
+                SetStatus("OIDC 授权地址无效。请从 Termux 重新发起登录。", false);
             return;
         }
 
@@ -121,6 +135,33 @@ public sealed class MainActivity : Activity
             SetStatus("登录回调已交给 Termux。请返回终端等待完成。", true);
     }
 
+    private void StartBrowserForAuthorization(Uri authorizationUrl, int port)
+    {
+        var preferences = GetPreferences(FileCreationMode.Private);
+        var editor = preferences?.Edit();
+        if (editor is null)
+        {
+            SetStatus("无法保存 OIDC 回调状态。请从 Termux 重新发起登录。", false);
+            return;
+        }
+        var updatedEditor = editor.PutInt(CallbackPortPreference, port);
+        if (updatedEditor is null)
+        {
+            SetStatus("无法保存 OIDC 回调状态。请从 Termux 重新发起登录。", false);
+            return;
+        }
+        updatedEditor.Apply();
+        try
+        {
+            StartActivity(new Intent(Intent.ActionView, global::Android.Net.Uri.Parse(authorizationUrl.ToString())));
+            SetStatus("已打开浏览器。完成登录后将自动返回 Termux。", false);
+        }
+        catch (Exception exception)
+        {
+            SetStatus("无法打开浏览器：" + exception.Message, false);
+        }
+    }
+
     private bool HasTermux()
     {
         try

src/client/OidcLogin.cs

@@ -9,6 +9,8 @@ namespace Charac.Client;
 
 internal static class OidcLogin
 {
+    private const string TermuxBin = "/data/data/com.termux/files/usr/bin";
+
     public static async Task<string> LoginAsync(HttpClient client, string issuer, string clientId,
         string discoveryUrl,
         CancellationToken cancellationToken = default)
@@ -106,22 +108,18 @@ internal static class OidcLogin
     {
         try
         {
-            var start = new ProcessStartInfo("/system/bin/am") { UseShellExecute = false };
-            start.ArgumentList.Add("start");
-            start.ArgumentList.Add("-n");
-            start.ArgumentList.Add("com.nitload.charac/.MainActivity");
-            start.ArgumentList.Add("--es");
-            start.ArgumentList.Add("charac_auth_url");
-            start.ArgumentList.Add(authorizationUri.ToString());
-            start.ArgumentList.Add("--ei");
-            start.ArgumentList.Add("charac_callback_port");
-            start.ArgumentList.Add(port.ToString(System.Globalization.CultureInfo.InvariantCulture));
+            var brokerUri = new UriBuilder("com.nitload.charac://oauth/start")
+            {
+                Query = $"url={Uri.EscapeDataString(authorizationUri.ToString())}&port={port.ToString(System.Globalization.CultureInfo.InvariantCulture)}"
+            }.Uri;
+            var start = new ProcessStartInfo(TermuxBin + "/termux-open-url") { UseShellExecute = false };
+            start.ArgumentList.Add(brokerUri.ToString());
             using var process = Process.Start(start);
             process?.WaitForExit(5000);
             if (process is null || process.ExitCode != 0)
-                throw new InvalidOperationException("Android callback broker did not start.");
+                throw new InvalidOperationException("Termux could not open the Android callback broker.");
         }
-        catch (Exception exception) when (exception is System.ComponentModel.Win32Exception or InvalidOperationException)
+        catch (Exception exception) when (exception is System.ComponentModel.Win32Exception or InvalidOperationException or System.IO.IOException)
         {
             Console.WriteLine($"Could not start the Android callback broker: {exception.Message}");
             Console.WriteLine("Open the URL manually in a browser on this device.");