Automatic Port Selection and Secured Communication

src/ElectronNET.API/Bridge/SocketIOConnection.cs

@@ -3,20 +3,29 @@
 namespace ElectronNET.API;
 
 using System;
+using System.Collections.Generic;
 using System.Threading.Tasks;
 using ElectronNET.API.Serialization;
 using SocketIO.Serializer.SystemTextJson;
 using SocketIO = SocketIOClient.SocketIO;
+using SocketIOOptions = SocketIOClient.SocketIOOptions;
 
 internal class SocketIOConnection : ISocketConnection
 {
     private readonly SocketIO _socket;
     private readonly object _lockObj = new object();
     private bool _isDisposed;
 
-    public SocketIOConnection(string uri)
+    public SocketIOConnection(string uri, string authorization)
     {
-        _socket = new SocketIO(uri);
+        var opts = string.IsNullOrEmpty(authorization) ? new SocketIOOptions() : new SocketIOOptions
+        {
+            ExtraHeaders = new Dictionary<string, string>
+            {
+                ["authorization"] = authorization
+            },
+        };
+        _socket = new SocketIO(uri, opts);
         _socket.Serializer = new SystemTextJsonSerializer(ElectronJson.Options);
         // Use default System.Text.Json serializer from SocketIOClient.
         // Outgoing args are normalized to camelCase via SerializeArg in Emit.

src/ElectronNET.API/Common/ProcessRunner.cs

@@ -26,6 +26,8 @@ public class ProcessRunner : IDisposable
         private readonly StringBuilder stdOut = new StringBuilder(4 * 1024);
         private readonly StringBuilder stdErr = new StringBuilder(4 * 1024);
 
+        public event EventHandler<string> LineReceived;
+
         private volatile ManualResetEvent stdOutEvent;
         private volatile ManualResetEvent stdErrEvent;
         private volatile Stopwatch stopwatch;
@@ -571,6 +573,7 @@ private void Process_OutputDataReceived(object sender, DataReceivedEventArgs e)
             if (e.Data != null)
             {
                 Console.WriteLine("|| " + e.Data);
+                LineReceived?.Invoke(this, e.Data);
             }
             else
             {

src/ElectronNET.API/ElectronNetRuntime.cs

@@ -16,6 +16,7 @@ public static class ElectronNetRuntime
         internal const int DefaultWebPort = 8001;
         internal const string ElectronPortArgumentName = "electronPort";
         internal const string ElectronPidArgumentName = "electronPID";
+        internal const string ElectronAuthTokenArgumentName = "electronAuthToken";
 
         /// <summary>Initializes the <see cref="ElectronNetRuntime"/> class.</summary>
         static ElectronNetRuntime()
@@ -26,6 +27,8 @@ static ElectronNetRuntime()
 
         public static string ElectronExtraArguments { get; set; }
 
+        public static string ElectronAuthToken { get; internal set; }
+
         public static int? ElectronSocketPort { get; internal set; }
 
         public static int? AspNetWebPort { get; internal set; }

src/ElectronNET.API/Runtime/Controllers/RuntimeControllerDotNetFirst.cs

@@ -13,7 +13,6 @@ internal class RuntimeControllerDotNetFirst : RuntimeControllerBase
     {
         private ElectronProcessBase electronProcess;
         private SocketBridgeService socketBridge;
-        private int? port;
 
         public RuntimeControllerDotNetFirst()
         {
@@ -41,19 +40,13 @@ protected override Task StartCore()
             var isUnPacked = ElectronNetRuntime.StartupMethod.IsUnpackaged();
             var electronBinaryName = ElectronNetRuntime.ElectronExecutable;
             var args = string.Format("{0} {1}", ElectronNetRuntime.ElectronExtraArguments, Environment.CommandLine).Trim();
-            this.port = ElectronNetRuntime.ElectronSocketPort;
-
-            if (!this.port.HasValue)
-            {
-                this.port = PortHelper.GetFreePort(ElectronNetRuntime.DefaultSocketPort);
-                ElectronNetRuntime.ElectronSocketPort = this.port;
-            }
+            var port = ElectronNetRuntime.ElectronSocketPort ?? 0;
 
             Console.Error.WriteLine("[StartCore]: isUnPacked: {0}", isUnPacked);
             Console.Error.WriteLine("[StartCore]: electronBinaryName: {0}", electronBinaryName);
             Console.Error.WriteLine("[StartCore]: args: {0}", args);
 
-            this.electronProcess = new ElectronProcessActive(isUnPacked, electronBinaryName, args, this.port.Value);
+            this.electronProcess = new ElectronProcessActive(isUnPacked, electronBinaryName, args, port);
             this.electronProcess.Ready += this.ElectronProcess_Ready;
             this.electronProcess.Stopped += this.ElectronProcess_Stopped;
 
@@ -63,8 +56,10 @@ protected override Task StartCore()
 
         private void ElectronProcess_Ready(object sender, EventArgs e)
         {
+            var port = ElectronNetRuntime.ElectronSocketPort.Value;
+            var token = ElectronNetRuntime.ElectronAuthToken;
             this.TransitionState(LifetimeState.Started);
-            this.socketBridge = new SocketBridgeService(this.port!.Value);
+            this.socketBridge = new SocketBridgeService(port, token);
             this.socketBridge.Ready += this.SocketBridge_Ready;
             this.socketBridge.Stopped += this.SocketBridge_Stopped;
             this.socketBridge.Start();

src/ElectronNET.API/Runtime/Controllers/RuntimeControllerElectronFirst.cs

@@ -11,7 +11,6 @@ internal class RuntimeControllerElectronFirst : RuntimeControllerBase
     {
         private ElectronProcessBase electronProcess;
         private SocketBridgeService socketBridge;
-        private int? port;
 
         public RuntimeControllerElectronFirst()
         {
@@ -36,20 +35,16 @@ internal override ISocketConnection Socket
 
         protected override Task StartCore()
         {
-            this.port = ElectronNetRuntime.ElectronSocketPort;
-
-            if (!this.port.HasValue)
-            {
-                throw new Exception("No port has been specified by Electron!");
-            }
+            var port = ElectronNetRuntime.ElectronSocketPort.Value;
+            var token = ElectronNetRuntime.ElectronAuthToken;
 
             if (!ElectronNetRuntime.ElectronProcessId.HasValue)
             {
                 throw new Exception("No electronPID has been specified by Electron!");
             }
 
             this.TransitionState(LifetimeState.Starting);
-            this.socketBridge = new SocketBridgeService(this.port!.Value);
+            this.socketBridge = new SocketBridgeService(port, token);
             this.socketBridge.Ready += this.SocketBridge_Ready;
             this.socketBridge.Stopped += this.SocketBridge_Stopped;
             this.socketBridge.Start();

src/ElectronNET.API/Runtime/Services/ElectronProcess/ElectronProcessActive.cs

@@ -2,9 +2,11 @@
 {
     using System;
     using System.ComponentModel;
+    using System.Diagnostics;
     using System.IO;
     using System.Linq;
     using System.Runtime.InteropServices;
+    using System.Text.RegularExpressions;
     using System.Threading.Tasks;
     using ElectronNET.Common;
     using ElectronNET.Runtime.Data;
@@ -15,6 +17,7 @@
     [Localizable(false)]
     internal class ElectronProcessActive : ElectronProcessBase
     {
+        private readonly Regex extractor = new Regex("^Electron Socket: listening on port (\\d+) at .* using ([a-f0-9]+)$");
         private readonly bool isUnpackaged;
         private readonly string electronBinaryName;
         private readonly string extraArguments;
@@ -157,18 +160,36 @@ protected override Task StopCore()
 
         private async Task StartInternal(string startCmd, string args, string directoriy)
         {
-            try
+            var tcs = new TaskCompletionSource();
+
+            void Read_SocketIO_Parameters(object sender, string line)
             {
-                await Task.Delay(10.ms()).ConfigureAwait(false);
+                // Look for "Electron Socket: listening on port %s at ..."
+                var match = extractor.Match(line);
 
+                if (match?.Success ?? false)
+                {
+                    var port = int.Parse(match.Groups[1].Value);
+                    var token = match.Groups[2].Value;
+
+                    this.process.LineReceived -= Read_SocketIO_Parameters;
+                    ElectronNetRuntime.ElectronAuthToken = token;
+                    ElectronNetRuntime.ElectronSocketPort = port;
+                    tcs.SetResult();
+                }
+            }
+
+            try
+            {
                 Console.Error.WriteLine("[StartInternal]: startCmd: {0}", startCmd);
                 Console.Error.WriteLine("[StartInternal]: args: {0}", args);
 
                 this.process = new ProcessRunner("ElectronRunner");
                 this.process.ProcessExited += this.Process_Exited;
+                this.process.LineReceived += Read_SocketIO_Parameters;
                 this.process.Run(startCmd, args, directoriy);
 
-                await Task.Delay(500.ms()).ConfigureAwait(false);
+                await tcs.Task.ConfigureAwait(false);
 
                 Console.Error.WriteLine("[StartInternal]: after run:");
 

src/ElectronNET.API/Runtime/Services/SocketBridge/SocketBridgeService.cs

@@ -8,12 +8,14 @@
     internal class SocketBridgeService : LifetimeServiceBase
     {
         private readonly int socketPort;
+        private readonly string authorization;
         private readonly string socketUrl;
         private SocketIOConnection socket;
 
-        public SocketBridgeService(int socketPort)
+        public SocketBridgeService(int socketPort, string authorization)
         {
             this.socketPort = socketPort;
+            this.authorization = authorization;
             this.socketUrl = $"http://localhost:{this.socketPort}";
         }
 
@@ -23,7 +25,7 @@ public SocketBridgeService(int socketPort)
 
         protected override Task StartCore()
         {
-            this.socket = new SocketIOConnection(this.socketUrl);
+            this.socket = new SocketIOConnection(this.socketUrl, this.authorization);
             this.socket.BridgeConnected += this.Socket_BridgeConnected;
             this.socket.BridgeDisconnected += this.Socket_BridgeDisconnected;
             Task.Run(this.Connect);

src/ElectronNET.API/Runtime/StartupManager.cs

@@ -106,6 +106,20 @@ private void CollectProcessData()
                     Console.WriteLine("Electron Process ID: " + result);
                 }
             }
+
+            var authTokenArg = argsList.FirstOrDefault(e => e.Contains(ElectronNetRuntime.ElectronAuthTokenArgumentName, StringComparison.OrdinalIgnoreCase));
+
+            if (authTokenArg != null)
+            {
+                var parts = authTokenArg.Split('=', StringSplitOptions.TrimEntries);
+
+                if (parts.Length > 1 && !string.IsNullOrWhiteSpace(parts[1]))
+                {
+                    var result = parts[1];
+                    ElectronNetRuntime.ElectronAuthToken = result;
+                    Console.WriteLine("Use Auth Token: " + result);
+                }
+            }
         }
 
         private void SetElectronExecutable()

src/ElectronNET.AspNet/API/WebHostBuilderExtensions.cs

@@ -1,6 +1,7 @@
 namespace ElectronNET.API
 {
     using System;
+    using System.Diagnostics;
     using System.IO;
     using System.Threading.Tasks;
     using ElectronNET.AspNet;
@@ -10,6 +11,7 @@
     using ElectronNET.Runtime.Helpers;
     using Microsoft.AspNetCore.Hosting;
     using Microsoft.Extensions.DependencyInjection;
+    using Microsoft.Extensions.Hosting;
 
     /// <summary>
     /// Provides extension methods for <see cref="IWebHostBuilder"/> to enable Electron.NET
@@ -66,23 +68,26 @@ public static IWebHostBuilder UseElectron(this IWebHostBuilder builder, string[]
             // work as expected, see issue #952
             Environment.SetEnvironmentVariable("ELECTRON_RUN_AS_NODE", null);
 
-            var webPort = PortHelper.GetFreePort(ElectronNetRuntime.AspNetWebPort ?? ElectronNetRuntime.DefaultWebPort);
-            ElectronNetRuntime.AspNetWebPort = webPort;
+            var webPort = ElectronNetRuntime.AspNetWebPort ?? 0;
 
             // check for the content folder if its exists in base director otherwise no need to include
             // It was used before because we are publishing the project which copies everything to bin folder and contentroot wwwroot was folder there.
             // now we have implemented the live reload if app is run using /watch then we need to use the default project path.
+
+            // For port 0 (dynamic port assignment), Kestrel requires binding to specific IP (127.0.0.1) not localhost
+            var host = webPort == 0? "127.0.0.1" : "localhost";
+
             if (Directory.Exists($"{AppDomain.CurrentDomain.BaseDirectory}\\wwwroot"))
             {
                 builder = builder.UseContentRoot(AppDomain.CurrentDomain.BaseDirectory)
-                    .UseUrls("http://localhost:" + webPort);
+                    .UseUrls($"http://{host}:{webPort}");
             }
             else
             {
-                builder = builder.UseUrls("http://localhost:" + webPort);
+                builder = builder.UseUrls($"http://{host}:{webPort}");
             }
 
-            builder = builder.ConfigureServices(services =>
+            builder = builder.ConfigureServices((context, services) =>
             {
                 services.AddTransient<IStartupFilter, ServerReadyStartupFilter>();
                 services.AddSingleton<AspNetLifetimeAdapter>();

src/ElectronNET.AspNet/Middleware/ElectronAuthenticationMiddleware.cs

@@ -0,0 +1,100 @@
+namespace ElectronNET.AspNet.Middleware
+{
+    using System;
+    using System.Threading.Tasks;
+    using Microsoft.AspNetCore.Http;
+    using Microsoft.Extensions.Logging;
+    using ElectronNET.AspNet.Services;
+
+    /// <summary>
+    /// Middleware that validates authentication for all Electron requests.
+    /// Checks for authentication cookie or token query parameter on first request.
+    /// Sets HttpOnly cookie for subsequent requests.
+    /// 
+    /// Security Model:
+    /// - First request includes token as query parameter (?token=guid)
+    /// - Middleware validates token and sets secure HttpOnly cookie
+    /// - Subsequent requests use cookie (no token in URL)
+    /// - HTTP endpoints protected
+    /// </summary>
+    public class ElectronAuthenticationMiddleware
+    {
+        private readonly RequestDelegate _next;
+        private readonly IElectronAuthenticationService _authService;
+        private readonly ILogger<ElectronAuthenticationMiddleware> _logger;
+        private const string AuthCookieName = "ElectronAuth";
+
+        public ElectronAuthenticationMiddleware(
+            RequestDelegate next,
+            IElectronAuthenticationService authService,
+            ILogger<ElectronAuthenticationMiddleware> logger)
+        {
+            _next = next;
+            _authService = authService;
+            _logger = logger;
+        }
+
+        public async Task InvokeAsync(HttpContext context)
+        {
+            var path = context.Request.Path.Value;
+
+            // Check if authentication cookie exists
+            var authCookie = context.Request.Cookies[AuthCookieName];
+
+            if (!string.IsNullOrEmpty(authCookie))
+            {
+                // Cookie present - validate it
+                if (_authService.ValidateToken(authCookie))
+                {
+                    await _next(context);
+                    return;
+                }
+                else
+                {
+                    // Invalid cookie - reject
+                    _logger.LogWarning("Authentication failed: Invalid cookie for path {Path} from {RemoteIp}", path, context.Connection.RemoteIpAddress);
+                    context.Response.StatusCode = 401;
+                    await context.Response.WriteAsync("Unauthorized: Invalid authentication");
+                    return;
+                }
+            }
+
+            // No cookie - check for token in query string (first-time authentication)
+            var token = context.Request.Query["token"].ToString();
+
+            if (!string.IsNullOrEmpty(token))
+            {
+                if (_authService.ValidateToken(token))
+                {
+                    // Valid token - set cookie for future requests
+                    _logger.LogInformation("Authentication successful: Setting cookie for path {Path}", path);
+
+                    context.Response.Cookies.Append(AuthCookieName, token, new CookieOptions
+                    {
+                        HttpOnly = true,                     // Prevent JavaScript access (XSS protection)
+                        SameSite = SameSiteMode.Strict,      // CSRF protection
+                        Path = "/",                          // Valid for all routes
+                        Secure = false,                      // False because localhost is HTTP
+                        IsEssential = true                   // Required for app to function
+                    });
+
+                    await _next(context);
+                    return;
+                }
+                else
+                {
+                    // Invalid token - reject
+                    _logger.LogWarning("Authentication failed: Invalid token (prefix: {TokenPrefix}...) for path {Path} from {RemoteIp}", token.Length > 8 ? token.Substring(0, 8) : token, path, context.Connection.RemoteIpAddress);
+                    context.Response.StatusCode = 401;
+                    await context.Response.WriteAsync("Unauthorized: Invalid authentication");
+                    return;
+                }
+            }
+
+            // Neither cookie nor valid token present - reject
+            _logger.LogWarning("Authentication failed: No cookie or token provided for path {Path} from {RemoteIp}", path, context.Connection.RemoteIpAddress);
+            context.Response.StatusCode = 401;
+            await context.Response.WriteAsync("Unauthorized: Authentication required");
+        }
+    }
+}