using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.ComponentModel;
using System.Configuration;
using System.Globalization;
using System.IO;
using System.Linq;
using System.Net;
using System.Net.Sockets;
using System.ServiceProcess;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading;
using Newtonsoft.Json.Linq;

namespace smtpproxy.net;

public class SMTPProxy : ServiceBase
{
	private ConcurrentQueue<Email> EmailQueue;

	private ManualResetEvent mre;

	private bool bRunning;

	private Thread Sending;

	private Thread Listening;

	private long ThreadCount;

	private bool ConsoleMode;

	private static readonly object _syncObject = new object();

	private IContainer components;

	public SMTPProxy()
	{
		InitializeComponent();
		base.ServiceName = "SMTPProxy.net";
		ConsoleMode = false;
		EmailQueue = new ConcurrentQueue<Email>();
		mre = new ManualResetEvent(initialState: false);
		bRunning = true;
		ThreadCount = 0L;
	}

	protected override void OnStart(string[] args)
	{
		Listening = new Thread(StartListening);
		Listening.Start();
		Sending = new Thread(StartSending);
		Sending.Start();
	}

	public void Start()
	{
		ConsoleMode = true;
		Listening = new Thread(StartListening);
		Listening.Start();
		Sending = new Thread(StartSending);
		Sending.Start();
	}

	protected override void OnStop()
	{
		bRunning = false;
		mre.Set();
	}

	public void Reload(string Folder)
	{
		foreach (string item in Directory.EnumerateFiles(Folder, "*.eml").ToList())
		{
			Email email = new Email();
			email.sDATA = File.ReadAllText(item);
			email.sHELO = File.ReadAllText(item.Replace(".eml", ".HELO"));
			email.sMAIL = File.ReadAllText(item.Replace(".eml", ".MAIL"));
			foreach (string item2 in File.ReadAllLines(item.Replace(".eml", ".RCPTS")).ToList())
			{
				if (item2.Length > 0)
				{
					email.sRCPTs.Add(item2 + "\r\n");
				}
			}
			email.FromIP = "127.0.0.1";
			EmailQueue.Enqueue(email);
		}
		SendQueuedEmails();
	}

	public void StartSending()
	{
		while (!mre.WaitOne(30000) && bRunning)
		{
			SendQueuedEmails();
		}
	}

	public void StartListening()
	{
		Dns.GetHostEntry(Dns.GetHostName());
		IPAddress iPAddress = IPAddress.Parse(ConfigurationManager.AppSettings["ListeningAddress"]);
		IPEndPoint localEP = new IPEndPoint(iPAddress, 25);
		Socket socket = new Socket(iPAddress.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
		Log("Started Listening on port 25 at " + iPAddress.ToString());
		socket.Bind(localEP);
		socket.Listen(100);
		while (true)
		{
			try
			{
				Socket socket2 = socket.Accept();
				if (socket2.Connected)
				{
					Log("New Connection:" + DateTime.Now.ToString("G", CultureInfo.CreateSpecificCulture("en-AU")));
					ThreadPool.QueueUserWorkItem(ProcessMailClient, socket2);
				}
			}
			catch (SocketException ex)
			{
				Log($"SocketException : {ex.ToString()}");
			}
			catch (Exception ex2)
			{
				Log($"Unexpected exception : {ex2.ToString()}");
			}
		}
	}

	private void ProcessMailClient(object stateinfo)
	{
		Socket socket = (Socket)stateinfo;
		socket.ReceiveTimeout = 180000;
		socket.SendTimeout = 180000;
		byte[] bytes = Encoding.ASCII.GetBytes("220 Connected to SBC SMTPProxy.net\r\n");
		socket.Send(bytes);
		IPEndPoint iPEndPoint = socket.RemoteEndPoint as IPEndPoint;
		string text = ConfigurationManager.AppSettings["LogFolder"] + "in";
		Directory.CreateDirectory(text);
		string logFileName = $"{text}\\{Guid.NewGuid()}_{iPEndPoint.Address}.log";
		Log("New Client Connected from " + iPEndPoint.Address, logFileName);
		new List<Email>();
		List<string> list = new List<string>();
		byte[] array = new byte[2000];
		StringBuilder stringBuilder = new StringBuilder();
		string text2 = "";
		string text3 = "";
		string text4 = "";
		string text5 = "";
		string text6 = "";
		int num = 0;
		bool flag = false;
		do
		{
			try
			{
				num = socket.Receive(array, 1999, SocketFlags.None);
				if (num > 0)
				{
					array[num] = 0;
					string text7 = Encoding.Default.GetString(array, 0, num);
					text3 = text2 + text7;
					text2 = text7;
					stringBuilder.Append(text7);
					if (num == 1999 || !text3.Contains("\r\n"))
					{
						continue;
					}
					string text8 = stringBuilder.ToString();
					string text9 = ((text8.Length < 4) ? text8 : text8.Substring(0, 4));
					string text10 = "500 Invalid Command\r\n";
					bool flag2 = false;
					if (flag)
					{
						text6 += text8;
						if (text8 == ".\r\n" || text8.Contains("\r\n.\r\n"))
						{
							flag = false;
							text10 = "250 OK\r\n";
							Email email = new Email();
							email.sHELO = text4;
							email.sMAIL = text5;
							email.sRCPTs = new List<string>(list);
							email.sDATA = text6;
							email.FromIP = iPEndPoint.Address.ToString();
							EmailQueue.Enqueue(email);
							text5 = (text6 = "");
							list.Clear();
						}
					}
					else
					{
						switch (text9)
						{
						case "HELO":
						case "EHLO":
							text4 = stringBuilder.ToString();
							text10 = "250 Hi\r\n";
							break;
						case "MAIL":
							if (text4.Length == 0)
							{
								text10 = "503 Do HELO first\r\n";
								break;
							}
							if (text5.Length > 0)
							{
								text10 = "503 Already have MAIL\r\n";
								break;
							}
							text5 = stringBuilder.ToString();
							text10 = "250 MAIL command recorded\r\n";
							break;
						case "RCPT":
							if (text4.Length == 0)
							{
								text10 = "503 Do HELO first\r\n";
								break;
							}
							if (text5.Length == 0)
							{
								text10 = "503 Do MAIL first\r\n";
								break;
							}
							list.Add(stringBuilder.ToString());
							text10 = "250 RCPT command recorded\r\n";
							break;
						case "DATA":
							if (text4.Length == 0)
							{
								text10 = "503 Do HELO first\r\n";
							}
							else if (text5.Length == 0)
							{
								text10 = "503 Do MAIL first\r\n";
							}
							else if (list.Count == 0)
							{
								text10 = "503 Do RCPT first\r\n";
							}
							text10 = "354 DATA\r\n";
							flag2 = true;
							break;
						case "RSET":
							text10 = "250 OK\r\n";
							text5 = (text6 = "");
							list.Clear();
							break;
						case "QUIT":
							socket.Shutdown(SocketShutdown.Both);
							socket.Close();
							num = 0;
							goto end_IL_00ed;
						default:
							Log("Unknown:" + text9, logFileName);
							break;
						}
					}
					if (!flag)
					{
						byte[] bytes2 = Encoding.ASCII.GetBytes(text10);
						socket.Send(bytes2);
						Log(text10, logFileName);
					}
					if (flag2)
					{
						flag = true;
					}
					stringBuilder.Clear();
					array[0] = 0;
					continue;
				}
				if (num == 0)
				{
					Log("Client disconnected.", logFileName);
					continue;
				}
				Log("Client reset the connection.", logFileName);
				socket.Shutdown(SocketShutdown.Both);
				socket.Close();
				num = 0;
				end_IL_00ed:;
			}
			catch (SocketException ex)
			{
				Log($"SocketException : {ex.ToString()}", logFileName);
				num = 0;
			}
			catch (Exception ex2)
			{
				Log($"Unexpected exception : {ex2.ToString()}", logFileName);
				num = 0;
			}
		}
		while (socket.Connected && num > 0);
		if (EmailQueue.Count > 5 && Interlocked.Read(ref ThreadCount) < Convert.ToUInt32(ConfigurationManager.AppSettings["ThreadMax"]))
		{
			Interlocked.Increment(ref ThreadCount);
			SendQueuedEmails();
			Interlocked.Decrement(ref ThreadCount);
		}
	}

	private void Log(string info, string LogFileName = null)
	{
		if (ConsoleMode)
		{
			Console.WriteLine(info.Replace("\r\n", ""));
		}
		if (!string.IsNullOrEmpty(LogFileName))
		{
			using (StreamWriter streamWriter = File.AppendText(LogFileName))
			{
				streamWriter.WriteLine("{0}", info);
				streamWriter.Flush();
				return;
			}
		}
		lock (_syncObject)
		{
			DateTime now = DateTime.Now;
			using StreamWriter streamWriter2 = File.AppendText(string.Format("{0}\\{1:00}{2:00}{3:00}.log", ConfigurationManager.AppSettings["LogFolder"] + "in", now.Year, now.Month, now.Day));
			streamWriter2.WriteLine("{0}", info);
			streamWriter2.Flush();
		}
	}

	private void SendQueuedEmails()
	{
		JToken val2 = default(JToken);
		while (!EmailQueue.IsEmpty)
		{
			if (!EmailQueue.TryDequeue(out var result))
			{
				continue;
			}
			string sMAIL = result.sMAIL;
			sMAIL = sMAIL.Replace(" ", "");
			sMAIL = sMAIL.Replace("MAILFROM:", "");
			sMAIL = sMAIL.Replace("<", "");
			sMAIL = sMAIL.Replace(">", "");
			sMAIL = sMAIL.Replace("\r", "");
			sMAIL = sMAIL.Replace("\n", "");
			string path = ConfigurationManager.AppSettings["Profiles"] + result.FromIP + "\\" + sMAIL + ".json";
			if (!File.Exists(path))
			{
				int num = sMAIL.IndexOf('@');
				string text = sMAIL.Substring(num + 1);
				path = ConfigurationManager.AppSettings["Profiles"] + result.FromIP + "\\default@" + text + ".json";
				if (!File.Exists(path))
				{
					path = ConfigurationManager.AppSettings["Profiles"] + result.FromIP + "\\default.json";
				}
			}
			JObject val;
			try
			{
				val = JObject.Parse(File.ReadAllText(path));
			}
			catch (Exception ex)
			{
				Log(ex.Message);
				continue;
			}
			int num2 = Convert.ToInt32(val["logging"][(object)"enabled"]);
			bool bHideRecipients = Convert.ToInt32(val["HideRecipients"]) == 1;
			bool num3 = num2 == 1;
			string text2 = "";
			string text3 = ((object)val["logging"][(object)"path"]).ToString() + "\\log";
			Directory.CreateDirectory(text3);
			Guid guid = Guid.NewGuid();
			string recipientEmail = result.GetRecipientEmail(result.sRCPTs[0]);
			text2 = $"{text3}\\{recipientEmail}.{guid}.log";
			string text4 = ((object)val["logging"][(object)"path"]).ToString() + "\\out";
			Directory.CreateDirectory(text4);
			if (num3)
			{
				File.WriteAllText($"{text4}\\{recipientEmail}.{guid}.eml", result.sDATA);
				File.WriteAllText($"{text4}\\{recipientEmail}.{guid}.HELO", result.sHELO);
				File.WriteAllText($"{text4}\\{recipientEmail}.{guid}.MAIL", result.sMAIL);
				File.WriteAllLines($"{text4}\\{recipientEmail}.{guid}.RCPTS", result.sRCPTs);
			}
			IPAddress iPAddress = Dns.GetHostEntry(((object)val["smtpserver"]).ToString()).AddressList[0];
			IPEndPoint remoteEP = new IPEndPoint(iPAddress, Convert.ToInt32(((object)val["smtpserverport"]).ToString()));
			int num4 = Convert.ToInt32(val["recipientreplacement"][(object)"enabled"]);
			List<string> list = val["recipientreplacement"][(object)"replacements"].ToObject<List<string>>();
			int num5 = Convert.ToInt32(val["recipientfilter"][(object)"enabled"]);
			List<string> list2 = val["recipientfilter"][(object)"whitelist"].ToObject<List<string>>();
			bool flag = false;
			List<string> list3 = null;
			if (val.TryGetValue("bcc", ref val2))
			{
				flag = Extensions.Value<int>((IEnumerable<JToken>)val2[(object)"enabled"]) == 1;
				list3 = val2[(object)"recipients"].ToObject<List<string>>();
			}
			Socket socket = null;
			bool flag2 = num4 == 1;
			bool flag3 = num5 == 1;
			try
			{
				socket = new Socket(iPAddress.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
				socket.Connect(remoteEP);
				if (!CheckAndSend("220", result.sHELO, socket, text2) || !CheckAndSend("250", result.sMAIL, socket, text2))
				{
					continue;
				}
				if (flag2)
				{
					foreach (string item in list)
					{
						string nextCommand = $"RCPT TO: {item}\r\n";
						CheckAndSend("250", nextCommand, socket, text2);
					}
					goto IL_053d;
				}
				int num6 = 0;
				foreach (string sRCPT in result.sRCPTs)
				{
					if (sRCPT.Length < 8)
					{
						continue;
					}
					if (flag3)
					{
						string r = result.GetRecipientEmail(sRCPT);
						if (!list2.Exists((string prd) => prd.Equals(r)))
						{
							Log("Filtering Recipient " + r, text2);
							continue;
						}
						Log("Recipient " + r + " OK", text2);
					}
					if (CheckAndSend("250", sRCPT, socket, text2))
					{
						num6++;
					}
				}
				if (num6 != 0)
				{
					goto IL_053d;
				}
				Log("No Valid recipients, aborting", text2);
				socket.Shutdown(SocketShutdown.Both);
				socket.Close();
				goto end_IL_03a8;
				IL_053d:
				if (flag)
				{
					foreach (string item2 in list3)
					{
						string nextCommand2 = $"RCPT TO: {item2}\r\n";
						CheckAndSend("250", nextCommand2, socket, text2);
					}
				}
				if (CheckAndSend("250", "DATA\r\n", socket, text2) && CheckAndSend("354", CleanseDataBlock(result.sDATA, bHideRecipients), socket, text2) && CheckAndSend("250", "RSET\r\n", socket, text2) && CheckAndSend("250", "QUIT\r\n", socket, text2))
				{
					socket.Shutdown(SocketShutdown.Both);
					socket.Close();
				}
				end_IL_03a8:;
			}
			catch (ArgumentNullException ex2)
			{
				Log($"ArgumentNullException : {ex2.ToString()}", text2);
			}
			catch (SocketException ex3)
			{
				Log($"SocketException : {ex3.ToString()}", text2);
			}
			catch (Exception ex4)
			{
				Log($"Unexpected exception : {ex4.ToString()}", text2);
			}
		}
	}

	private static string CleanseDataBlock(string sData, bool bHideRecipients)
	{
		if (bHideRecipients)
		{
			StringBuilder stringBuilder = new StringBuilder();
			using StringReader stringReader = new StringReader(sData);
			string pattern = "^[Tt][Oo]: *$";
			string pattern2 = "^[Dd][Aa][Tt][Ee]:.*$";
			bool flag = false;
			bool flag2 = false;
			for (string text = stringReader.ReadLine(); text != null; text = stringReader.ReadLine())
			{
				if (flag2)
				{
					stringBuilder.Append(text + "\r\n");
				}
				else if (!flag)
				{
					if (Regex.Match(text, pattern).Success)
					{
						flag = true;
					}
					stringBuilder.Append(text + "\r\n");
				}
				else if (Regex.Match(text, pattern2).Success)
				{
					flag = false;
					stringBuilder.Append(text + "\r\n");
					flag2 = true;
				}
			}
			return stringBuilder.ToString();
		}
		return sData;
	}

	private bool CheckAndSend(string PrevSuccessCode, string NextCommand, Socket sock, string LogFileName)
	{
		byte[] array = new byte[2500];
		string text = "";
		int num = sock.Receive(array);
		if (num <= 0)
		{
			Log("recv failed", LogFileName);
			sock.Shutdown(SocketShutdown.Both);
			sock.Close();
			return false;
		}
		array[num] = 0;
		text = Encoding.ASCII.GetString(array, 0, num);
		Log(text, LogFileName);
		if (text.Substring(0, 3) != PrevSuccessCode)
		{
			sock.Shutdown(SocketShutdown.Both);
			sock.Close();
			return false;
		}
		if (NextCommand.Length > 500)
		{
			Log(NextCommand.Substring(0, 500), LogFileName);
		}
		else
		{
			Log(NextCommand, LogFileName);
		}
		byte[] bytes = Encoding.ASCII.GetBytes(NextCommand);
		sock.Send(bytes);
		return true;
	}

	protected override void Dispose(bool disposing)
	{
		if (disposing && components != null)
		{
			components.Dispose();
		}
		base.Dispose(disposing);
	}

	private void InitializeComponent()
	{
		components = new Container();
		base.ServiceName = "Service1";
	}
}