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krisdb2009krisdb2009
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‎SMTP2Graph/Program.cs‎

Lines changed: 0 additions & 133 deletions
This file was deleted.

‎SMTP2Graph/SMTP2Graph.cs‎

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using Microsoft.Graph;
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using Azure.Identity;
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using System.Net.Sockets;
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using System.Net;
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using System.Text.RegularExpressions;
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using System.Text;
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using Microsoft.Kiota.Abstractions;
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using Microsoft.Win32;
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using Microsoft.Extensions.Logging;
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namespace SMTP2Graph;
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class Service
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{
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private static ILogger<Service> Logger = LoggerFactory.Create((lf) => {
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lf.AddSimpleConsole((sc) => {
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sc.SingleLine = true;
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sc.TimestampFormat = "MM/dd/yyyy: hh:mm:ss: ";
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});
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if (OperatingSystem.IsWindows()) lf.AddEventLog();
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}).CreateLogger<Service>();
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public static void Main()
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{
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Logger.LogInformation("Initializing SMTP2Graph...");
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var mail_listener = new TcpListener(IPAddress.Any, 25);
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var scopes = new[] { "https://graph.microsoft.com/.default" };
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var options = new ClientSecretCredentialOptions
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{
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AuthorityHost = AzureAuthorityHosts.AzurePublicCloud,
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};
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Logger.LogInformation("Connecting to MS Graph...");
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GraphServiceClient graphClient = null;
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try
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{
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var clientSecretCredential = new ClientSecretCredential(
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GetConfigOption("TENANT_ID"),
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GetConfigOption("CLIENT_ID"),
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GetConfigOption("CLIENT_SECRET"),
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options
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);
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graphClient = new GraphServiceClient(clientSecretCredential, scopes);
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}
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catch (Exception e)
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{
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Logger.LogCritical(e, "Failed to connect to MS Graph.");
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Environment.Exit(0);
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}
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Logger.LogInformation("Starting SMTP listener loop, ready for connections.");
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mail_listener.Start();
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while (true)
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{
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var client = mail_listener.AcceptTcpClient();
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Logger.LogInformation("Accepting connection, attempting to process...");
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_ = Task.Run(() => {
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try
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{
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client.NoDelay = true;
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var stream = client.GetStream();
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var sw = new StreamWriter(stream);
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var sr = new StreamReader(stream);
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sw.AutoFlush = true;
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sw.Write($"220 {Environment.MachineName} SMTP2Graph Service ready\r\n");
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HandleConnection(client, stream, sw, sr);
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}
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catch (Exception e)
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{
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if (client.Connected) client.Close();
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Logger.LogError(e, "An error occured in the SMTP listener loop.");
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}
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});
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}
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string GetConfigOption(string Key)
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{
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string? env;
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env = Environment.GetEnvironmentVariable(Key);
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if (env != null) return env;
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if (OperatingSystem.IsWindows()) env = (string?)(Registry.LocalMachine.OpenSubKey(@"SOFTWARE\SMTP2Graph")?.GetValue(Key));
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if (env != null) return env;
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Logger.LogCritical($"Config option not set: {Key}.");
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Environment.Exit(0);
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return string.Empty;
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}
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void HandleConnection(TcpClient client, Stream stream, StreamWriter sw, StreamReader sr)
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{
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string From = string.Empty;
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string MIME = string.Empty;
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while (true)
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{
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var msg = sr.ReadLine();
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if (msg == null) continue;
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if (msg.StartsWith("HELO") || msg.StartsWith("EHLO"))
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{
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Logger.LogInformation("HELO");
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sw.Write("250 OK\r\n");
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continue;
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}
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if (msg.StartsWith("MAIL FROM:"))
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{
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Logger.LogInformation("MAIL FROM");
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#pragma warning disable SYSLIB1045
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From = Regex.Match(msg, "<(.*)>").Groups[1].Value;
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#pragma warning restore SYSLIB1045
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sw.Write("250 OK\r\n");
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continue;
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}
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if (msg.StartsWith("RCPT TO:"))
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{
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Logger.LogInformation("RCPT TO");
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sw.Write("250 OK\r\n");
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continue;
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}
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if (msg.StartsWith("DATA"))
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{
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Logger.LogInformation("DATA");
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sw.Write("354 Start mail input; end with <CRLF>.<CRLF>\r\n");
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MIME = ReadMIME(sr);
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sw.Write("250 OK\r\n");
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Logger.LogInformation("Sending to MS Graph...");
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SendMessage(From, MIME);
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Logger.LogInformation("Sent.");
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continue;
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}
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if (msg.StartsWith("QUIT"))
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{
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Logger.LogInformation("QUIT");
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sw.Write($"221 {Environment.MachineName} Service closing transmission channel\r\n");
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break;
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}
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}
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Logger.LogInformation("Closing connection...");
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client.Close();
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Logger.LogInformation("Done.");
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}
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string ReadMIME(StreamReader sr)
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{
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string MIME = string.Empty;
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while (true)
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{
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var msg = sr.ReadLine();
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if (msg == ".") break;
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if (msg == "..")
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{
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msg = ".";
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}
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MIME += msg + "\r\n";
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}
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return MIME;
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}
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void SendMessage(string From, string MIME)
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{
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var mimeb64bytes = Encoding.UTF8.GetBytes(
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Convert.ToBase64String(
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Encoding.UTF8.GetBytes(MIME)
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)
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);
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var request = new RequestInformation
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{
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URI = new($"https://graph.microsoft.com/v1.0/users/{From}/sendMail"),
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HttpMethod = Method.POST
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};
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request.Headers.Add("Content-Type", "text/plain");
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request.Content = new MemoryStream(mimeb64bytes);
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_ = graphClient.RequestAdapter.SendNoContentAsync(request);
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}
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}
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}

‎SMTP2Graph/SMTP2Graph.csproj‎

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Original file line numberDiff line numberDiff line change
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<PropertyGroup>
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<OutputType>Exe</OutputType>
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<TargetFramework>net9.0</TargetFramework>
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<TargetFramework>net10.0</TargetFramework>
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<ImplicitUsings>enable</ImplicitUsings>
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<Nullable>enable</Nullable>
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<UserSecretsId>d63d6915-df69-48cf-8d6c-88fd2de116f1</UserSecretsId>
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</PropertyGroup>
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<ItemGroup>
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<PackageReference Include="Azure.Identity" Version="1.17.1" />
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<PackageReference Include="Microsoft.Graph" Version="5.98.0" />
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<PackageReference Include="Azure.Identity" Version="1.21.0" />
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<PackageReference Include="Microsoft.Extensions.Hosting.WindowsServices" Version="10.0.6" />
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<PackageReference Include="Microsoft.Graph" Version="5.104.0" />
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</ItemGroup>
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</Project>

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