.net update, implemented base session, added test client

smtp-relay.sln

@@ -1,12 +1,16 @@
 
 Microsoft Visual Studio Solution File, Format Version 12.00
-# Visual Studio Version 17
+# Visual Studio Version 18
-VisualStudioVersion = 17.9.34902.65
+VisualStudioVersion = 18.0.11222.15 d18.0
 MinimumVisualStudioVersion = 10.0.40219.1
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "src", "src", "{7162BB38-DF40-4438-827C-05A55268EB23}"
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "smtprelay", "src\smtprelay\smtprelay.csproj", "{F1834A4A-8E76-61A2-D639-D02937B8885C}"
 EndProject
+Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "tests", "tests", "{8B4B0C4C-3F23-4418-91B4-C143295838F5}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "smtpclient", "tests\smtpclient\smtpclient.csproj", "{19058057-D6D9-980C-0359-AC3A630D5EAD}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -17,12 +21,17 @@ Global
 		{F1834A4A-8E76-61A2-D639-D02937B8885C}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{F1834A4A-8E76-61A2-D639-D02937B8885C}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{F1834A4A-8E76-61A2-D639-D02937B8885C}.Release|Any CPU.Build.0 = Release|Any CPU
+		{19058057-D6D9-980C-0359-AC3A630D5EAD}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{19058057-D6D9-980C-0359-AC3A630D5EAD}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{19058057-D6D9-980C-0359-AC3A630D5EAD}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{19058057-D6D9-980C-0359-AC3A630D5EAD}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
 	EndGlobalSection
 	GlobalSection(NestedProjects) = preSolution
 		{F1834A4A-8E76-61A2-D639-D02937B8885C} = {7162BB38-DF40-4438-827C-05A55268EB23}
+		{19058057-D6D9-980C-0359-AC3A630D5EAD} = {8B4B0C4C-3F23-4418-91B4-C143295838F5}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {91A1FDC3-5235-4A64-AFB8-BF772349C4E7}

src/smtprelay/Graph/GraphSmtpSession.cs

@@ -0,0 +1,31 @@
+using Microsoft.Extensions.Logging;
+
+namespace SmtpRelay.Graph;
+
+public partial class GraphSmtpSession(GraphSender graphSender, ILogger<GraphSmtpSession> logger) : SmtpSessionBase(logger)
+{
+    private readonly GraphSender _graphSender = graphSender;
+
+    protected override async Task OnProcessDataAsync(ReadOnlyMemory<byte> dataBytes, CancellationToken cancellationToken)
+    {
+        // save to spool dir (optional)
+        var spoolFile = await SpoolToFileAsync(dataBytes, cancellationToken);
+
+        // sent via graph api
+        await _graphSender.SendAsync(spoolFile, dataBytes, cancellationToken);
+    }
+
+    private async Task<FileInfo> SpoolToFileAsync(ReadOnlyMemory<byte> data, CancellationToken cancellationToken)
+    {
+        Directory.CreateDirectory(Common.SpoolDir.FullName);
+
+        var path = Path.Combine(Common.SpoolDir.FullName, $"{Guid.NewGuid()}.eml");
+        var spoolFile = new FileInfo(path);
+
+        await File.WriteAllBytesAsync(spoolFile.FullName, data, cancellationToken);
+
+        _logger.LogInformation("Spooled: {Path}", spoolFile.FullName);
+
+        return spoolFile;
+    }
+}

src/smtprelay/Program.cs

@@ -136,8 +136,8 @@ internal partial class Program
             services.AddSingleton(graphConfig);
 
             // register smtp instances
-            services.AddSingleton<SmtpServer>();
+            services.AddSingleton<SmtpServer<GraphSmtpSession>>();
-            services.AddScoped<SmtpSession>();
+            services.AddScoped<GraphSmtpSession>();
 
             // register smtp service
             services.AddHostedService<Service>();

src/smtprelay/Service.cs

@@ -1,11 +1,12 @@
 using Microsoft.Extensions.Hosting;
 using Microsoft.Extensions.Logging;
+using SmtpRelay.Graph;
 
 namespace SmtpRelay;
 
-internal class Service(SmtpServer server, SmtpConfig config, ILogger<Service> logger) : BackgroundService
+internal class Service(SmtpServer<GraphSmtpSession> server, SmtpConfig config, ILogger<Service> logger) : BackgroundService
 {
-    private readonly SmtpServer _server = server;
+    private readonly SmtpServer<GraphSmtpSession> _server = server;
     private readonly SmtpConfig _config = config;
     private readonly ILogger<Service> _logger = logger;
 

src/smtprelay/Smtp/SmtpServer.cs

@@ -5,16 +5,17 @@ using System.Net.Sockets;
 
 namespace SmtpRelay;
 
-public class SmtpServer(IServiceScopeFactory scopeFactory, ILogger<SmtpServer> logger)
+public class SmtpServer<TSession>(IServiceScopeFactory scopeFactory, ILogger<SmtpServer<TSession>> logger)
+    where TSession : SmtpSessionBase
 {
-    private readonly ILogger<SmtpServer> _logger = logger;
+    protected readonly IServiceScopeFactory _scopeFactory = scopeFactory;
-    private readonly IServiceScopeFactory _scopeFactory = scopeFactory;
+    protected readonly ILogger<SmtpServer<TSession>> _logger = logger;
 
     public bool IsRunning { get; private set; } = false;
 
     public async Task RunAsync(SmtpConfig config, CancellationToken cancellationToken)
     {
-        if (IsRunning) 
+        if (IsRunning)
             return;
 
         var ep = new IPEndPoint(IPAddress.Parse(config.Host), config.Port);
@@ -48,7 +49,7 @@ public class SmtpServer(IServiceScopeFactory scopeFactory, ILogger<SmtpServer> l
                 _logger.LogError(ex.ToString());
             }
         }
-        
+
         // set listener state
         IsRunning = false;
     }
@@ -57,7 +58,7 @@ public class SmtpServer(IServiceScopeFactory scopeFactory, ILogger<SmtpServer> l
     {
         // create session
         using var scope = _scopeFactory.CreateScope();
-        var session = scope.ServiceProvider.GetRequiredService<SmtpSession>();
+        var session = scope.ServiceProvider.GetRequiredService<TSession>();
 
         try
         {

src/smtprelay/Smtp/SmtpSession.cs

@@ -1,21 +1,18 @@
 using Microsoft.Extensions.Logging;
 using SmtpRelay.Graph;
-using System.Diagnostics.CodeAnalysis;
 using System.Net.Sockets;
 using System.Text;
-using System.Text.Json;
 using System.Text.RegularExpressions;
 
 namespace SmtpRelay;
 
-public partial class SmtpSession(GraphSender graphSender, ILogger<SmtpSession> logger)
+public abstract partial class SmtpSessionBase(ILogger<SmtpSessionBase> logger)
 {
     private static byte[] CrlnSpan { get; } = Encoding.ASCII.GetBytes("\r\n");
     private static byte[] DataDelimiterSpan { get; } = Encoding.ASCII.GetBytes("\r\n.\r\n");
 
-    private readonly GraphSender _graphSender = graphSender;
+    protected readonly ILogger<SmtpSessionBase> _logger = logger;
-    private readonly ILogger<SmtpSession> _logger = logger;
+    protected readonly List<string> _rcptTo = [];
-    private readonly List<string> _rcptTo = [];
 
     private bool _ehlo = false;
     private bool _authenticated = false;
@@ -86,6 +83,8 @@ public partial class SmtpSession(GraphSender graphSender, ILogger<SmtpSession> l
         _logger.LogInformation("[{REP}] Disconnected", socket.RemoteEndPoint);
     }
 
+    protected abstract Task OnProcessDataAsync(ReadOnlyMemory<byte> dataBytes, CancellationToken cancellationToken);
+
     private async Task OnGreeting(Socket socket, SmtpConfig config, CancellationToken cancellationToken)
     {
         // write default reply message
@@ -354,7 +353,7 @@ public partial class SmtpSession(GraphSender graphSender, ILogger<SmtpSession> l
         {
             var rawData = await ReadToSpanAsync(socket, DataDelimiterSpan, true, cancellationToken);
 
-            await ProcessCapturedData(rawData, cancellationToken);
+            await OnProcessDataAsync(rawData, cancellationToken);
 
             // dot unstuff
             //if (response.StartsWith(".."))
@@ -600,15 +599,6 @@ public partial class SmtpSession(GraphSender graphSender, ILogger<SmtpSession> l
         }
     }
 
-    private async Task ProcessCapturedData(ReadOnlyMemory<byte> dataBytes, CancellationToken cancellationToken)
-    {
-        // save to spool dir
-        var spoolFile = await SpoolToFileAsync(dataBytes, cancellationToken);
-
-        // sent via graph api
-        await _graphSender.SendAsync(spoolFile, dataBytes, cancellationToken);
-    }
-
     private static bool ValidateUser(SmtpConfig config, string user, string password)
     {
         if (!config.Authentication.Any(p => p.Key == user))
@@ -636,7 +626,6 @@ public partial class SmtpSession(GraphSender graphSender, ILogger<SmtpSession> l
         return spoolFile;
     }
 
-
     [GeneratedRegex(@"^MAIL\s+FROM:\s*<([^>]+)>(?:\s+(.*))?$", RegexOptions.IgnoreCase)]
     public static partial Regex MailFromRegex();
 

src/smtprelay/appsettings.json

@@ -8,24 +8,23 @@
     "UseWhitelist": true,
     "UsePipelining": true,
     "Authentication": {
-      "relay@example.local": "supersecret",
+      "relay@example.local": "supersecret"
-      "relay@autohaus-weigl.local": "Secret-Prevent-Whole"
     },
     "Whitelist": {
       "Senders": [
-        "test@example.local",
+        "me2@example.local"
-        "rechnung@autohaus-weigl.de"
       ],
       "Receivers": [
+        "noreply@example.local",
         "%"
       ]
     }
   },
   "Graph": {
+    "Bypass": true,
     "TenantId": "",
     "ClientId": "",
     "ClientSecret": "",
-    "SenderUpn": "",
+    "SenderUpn": ""
-    "Bypass": true
   }
 }

src/smtprelay/smtprelay.csproj

@@ -3,9 +3,9 @@
 	<PropertyGroup>
 		<Product>SmtpRelay</Product>
 		<AssemblyName>smtp_relay</AssemblyName>
-		<AssemblyVersion>2025.10.27.0</AssemblyVersion>
+		<AssemblyVersion>2025.12.3.0</AssemblyVersion>
 		<OutputType>Exe</OutputType>
-		<TargetFramework>net9.0</TargetFramework>
+		<TargetFramework>net10.0</TargetFramework>
 		<LangVersion>latest</LangVersion>
 		<RootNamespace>SmtpRelay</RootNamespace>
 		<ImplicitUsings>enable</ImplicitUsings>
@@ -17,11 +17,11 @@
 	</PropertyGroup>
 
 	<ItemGroup>
-		<PackageReference Include="Microsoft.Extensions.Hosting.Systemd" Version="9.0.10" />
+		<PackageReference Include="Microsoft.Extensions.Hosting.Systemd" Version="10.0.0" />
-		<PackageReference Include="Microsoft.Extensions.Hosting.WindowsServices" Version="9.0.10" />
+		<PackageReference Include="Microsoft.Extensions.Hosting.WindowsServices" Version="10.0.0" />
 		<PackageReference Include="Serilog.Extensions.Logging.File" Version="3.0.0" />
-		<PackageReference Include="Azure.Identity" Version="1.17.0" />
+		<PackageReference Include="Azure.Identity" Version="1.17.1" />
-		<PackageReference Include="System.IdentityModel.Tokens.Jwt" Version="8.14.0" />
+		<PackageReference Include="System.IdentityModel.Tokens.Jwt" Version="8.15.0" />
 	</ItemGroup>
 
 	<ItemGroup>

tests/smtpclient/Program.cs

@@ -0,0 +1,276 @@
+using System.Data;
+using System.Net;
+using System.Net.Mail;
+using System.Net.Sockets;
+using System.Text;
+
+namespace SmtpClient;
+
+internal class Program
+{
+    private static string? _host = null;
+    private static string? _username = null;
+    private static string? _password = null;
+    private static string? _from = null;
+    private static List<string>? _rcpts = [];
+    private static List<string>? _rcptsCc = [];
+    private static string? _subject = null;
+    private static string? _body = null;
+    private static bool _secure = false;
+
+    static async Task Main()
+    {
+        Console.WriteLine("Relay Test Client");
+
+        Console.WriteLine("\nSelect Input:");
+        Console.WriteLine("\t1-Static");
+        Console.WriteLine("\t2-Interactive");
+
+        switch (Console.ReadKey().Key)
+        {
+            case ConsoleKey.D1:
+            case ConsoleKey.NumPad1:
+                StaticInput();
+                break;
+            case ConsoleKey.D2:
+            case ConsoleKey.NumPad2:
+                InteractiveInput();
+                break;
+            default:
+                return;
+        }
+
+        Console.WriteLine("\nSelect Method:");
+        Console.WriteLine("\t1-Single Mail");
+        Console.WriteLine("\t2-Single Mail (Raw Pipelined)");
+        Console.WriteLine("\t3-Mutli Mail");
+
+        try
+        {
+            switch (Console.ReadKey(true).Key)
+            {
+                case ConsoleKey.D1:
+                case ConsoleKey.NumPad1:
+                    await SendAsync();
+                    break;
+                case ConsoleKey.D2:
+                case ConsoleKey.NumPad2:
+                    await SendPipelinedAsync();
+                    break;
+                case ConsoleKey.D3:
+                case ConsoleKey.NumPad3:
+                    await SendMultiAsync();
+                    break;
+                default:
+                    Console.WriteLine("\nUndefined Method");
+                    break;
+            }
+        }
+        catch (Exception ex)
+        {
+            Console.WriteLine(ex.ToString());
+        }
+    }
+
+    static void StaticInput()
+    {
+        _host = "localhost:2525"?.Trim();
+        _secure = false;
+        _username = "relay@example.local";
+        _password = "supersecret";
+        _from = "me@example.local"?.Trim();
+        _rcpts = "noreply@example.local"?.Trim()?.Split(';').ToList();
+        _rcptsCc = [];
+        _subject = "Testnachricht";
+        _body = "Das ist eine Testnachricht.";
+    }
+
+    static void InteractiveInput()
+    {
+        Console.WriteLine("\nEnter Relay Host: ");
+        _host = Console.ReadLine()?.Trim();
+
+        Console.WriteLine("\nEnter Username (Optional): ");
+        _username = Console.ReadLine()?.Trim();
+
+        if (!string.IsNullOrWhiteSpace(_username))
+        {
+            Console.WriteLine("\nEnter Password: ");
+            _password = Console.ReadLine()?.Trim();
+        }
+
+        Console.WriteLine("\nEnter Sender:");
+        _from = Console.ReadLine()?.Trim();
+
+        Console.WriteLine("\nEnter Receiver (delimit with ';'):");
+        _rcpts = Console.ReadLine()?.Trim()?.Split(';').ToList();
+
+        Console.WriteLine("\nEnter Cc Receiver (delimit with ';'):");
+        _rcptsCc = Console.ReadLine()?.Trim()?.Split(';').ToList();
+
+        Console.WriteLine("\nEnter Subject:");
+        _subject = Console.ReadLine()?.Trim();
+
+        Console.WriteLine("\nEnter Body:");
+        _body = Console.ReadLine()?.Trim();
+    }
+
+    static async Task SendAsync()
+    {
+        var from = new MailAddress(_from!);
+        var to = _rcpts!.Select(p => new MailAddress(p)).ToList();
+        var cc = _rcptsCc!.Select(p => new MailAddress(p)).ToList();
+
+        var firstTo = to.First();
+        to.Remove(firstTo);
+
+        using var message = new MailMessage(from, firstTo)
+        {
+            Priority = MailPriority.Normal,
+            Subject = _subject ?? "Undefined",
+            IsBodyHtml = false,
+            Body = _body ?? string.Empty,
+        };
+
+        foreach (var x in to)
+            message.To.Add(x);
+
+        foreach (var x in cc)
+            message.CC.Add(x);
+
+        message.Attachments.Add(new Attachment("attachment.txt"));
+
+        var credential = new NetworkCredential();
+
+        if (!string.IsNullOrWhiteSpace(_username))
+        {
+            credential.UserName = _username;
+            credential.Password = _password;
+        }
+
+        var host = _host;
+        var port = 25;
+
+        if (_host!.Contains(':'))
+        {
+            host = _host.Split(':')[0];
+            port = int.Parse(_host.Split(":")[1]);
+        }
+
+        using var smtp = new System.Net.Mail.SmtpClient(host, port)
+        {
+            UseDefaultCredentials = false,
+            Credentials = credential,
+            EnableSsl = _secure,
+            DeliveryMethod = SmtpDeliveryMethod.Network
+        };
+
+        await smtp.SendMailAsync(message);
+    }
+
+    static async Task SendMultiAsync()
+    {
+        var from = new MailAddress(_from!);
+        var to = _rcpts!.Select(p => new MailAddress(p)).ToList();
+        var cc = _rcptsCc!.Select(p => new MailAddress(p)).ToList();
+
+        var firstTo = to.First();
+        to.Remove(firstTo);
+
+        using var message = new MailMessage(from, firstTo)
+        {
+            Priority = MailPriority.Normal,
+            Subject = _subject ?? "Undefined",
+            IsBodyHtml = false,
+            Body = _body ?? string.Empty
+        };
+
+        foreach (var x in to)
+            message.To.Add(x);
+
+        foreach (var x in cc)
+            message.CC.Add(x);
+
+        message.Attachments.Add(new Attachment("attachment.txt"));
+
+        var credential = new NetworkCredential();
+
+        if (!string.IsNullOrWhiteSpace(_username))
+        {
+            credential.UserName = _username;
+            credential.Password = _password;
+        }
+
+        var host = _host;
+        var port = 25;
+
+        if (_host!.Contains(':'))
+        {
+            host = _host.Split(':')[0];
+            port = int.Parse(_host.Split(":")[1]);
+        }
+
+        using var smtp = new System.Net.Mail.SmtpClient(host, port)
+        {
+            UseDefaultCredentials = false,
+            Credentials = credential,
+            EnableSsl = _secure,
+            DeliveryMethod = SmtpDeliveryMethod.Network
+        };
+
+        await smtp.SendMailAsync(message);
+        await smtp.SendMailAsync(message);
+    }
+
+    static async Task SendPipelinedAsync()
+    {
+        var raw = "EHLO SmtpClient\r\n";
+
+        if (!string.IsNullOrWhiteSpace(_username))
+        {
+            raw += $"AUTH PLAIN {Convert.ToBase64String(Encoding.UTF8.GetBytes($"\0{_username}\0{_password}"))}\r\n";
+        }
+
+        raw += $"MAIL FROM:<{_from}> SIZE=512\r\n";
+
+        foreach (var rcpt in _rcpts!)
+        {
+            raw += $"RCPT TO:<{rcpt}>\r\n";
+        }
+
+        raw += "DATA\r\n";
+        raw += "MIME-Version: 1.0\r\n";
+        raw += $"From: {_from}\r\n";
+        raw += $"To: {string.Join(", ", _rcpts!)}\r\n";
+
+        if (_rcptsCc != null && _rcptsCc.Count > 0)
+        {
+            raw += $"Cc: {string.Join(", ", _rcptsCc!)}\r\n";
+        }
+
+        raw += "Date: 29 Oct 2025 21:10:56 +0100\r\n";
+        raw += $"Subject:{_subject}\r\n";
+        raw += "\r\n" ;
+        raw += $"{_body}";
+        raw += "\r\n.\r\n";
+        raw += "QUIT\r\n";
+
+        var bytes = Encoding.ASCII.GetBytes(raw);
+        var sock = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
+
+        var host = _host;
+        var port = 25;
+
+        if (_host!.Contains(':'))
+        {
+            host = _host.Split(':')[0];
+            port = int.Parse(_host.Split(":")[1]);
+        }
+
+        await sock.ConnectAsync(host!, port);
+        await sock.SendAsync(bytes);
+
+        Console.WriteLine("wait 3 seconds...");
+        await Task.Delay(3000);
+    }
+}

tests/smtpclient/attachment.txt

@@ -0,0 +1 @@
+test

tests/smtpclient/smtpclient.csproj

@@ -0,0 +1,23 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+	  <Product>SmtpClient</Product>
+	  <AssemblyName>smtp_client</AssemblyName>
+	  <AssemblyVersion>2025.12.3.0</AssemblyVersion>
+	  <OutputType>Exe</OutputType>
+	  <TargetFramework>net10.0</TargetFramework>
+	  <LangVersion>latest</LangVersion>
+	  <RootNamespace>SmtpClient</RootNamespace>
+	  <ImplicitUsings>enable</ImplicitUsings>
+	  <Nullable>enable</Nullable>
+	  <SatelliteResourceLanguages>none</SatelliteResourceLanguages>
+	  <InvariantGlobalization>true</InvariantGlobalization>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <None Update="attachment.txt">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </None>
+  </ItemGroup>
+
+</Project>