LuaCsForBarotraumaEP/Subsurface/Source/Networking/GameServerLogin.cs

using Lidgren.Network;
using Microsoft.Xna.Framework;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Barotrauma.Networking
{
    class UnauthenticatedClient
    {
        public NetConnection Connection;
        public int Nonce;

        public int failedAttempts;

        public float AuthTimer;

        public UnauthenticatedClient(NetConnection connection, int nonce)
        {
            Connection = connection;
            Nonce = nonce;

            AuthTimer = 5.0f;

            failedAttempts = 0;
        }
    }

    partial class GameServer : NetworkMember, IPropertyObject
    {
        List<UnauthenticatedClient> unauthenticatedClients = new List<UnauthenticatedClient>();

        private void ClientAuthRequest(NetConnection conn)
        {
            //client wants to know if server requires password

            if (ConnectedClients.Count >= MaxPlayers)
            {
                //server is full, can't allow new connection
                conn.Disconnect("Server full");
            }

            if (ConnectedClients.Find(c => c.Connection == conn) != null)
            {
                //this client has already been authenticated
                return;
            }
            UnauthenticatedClient unauthClient = unauthenticatedClients.Find(uc => uc.Connection == conn);
            if (unauthClient == null)
            {
                //new client, generate nonce and add to unauth queue
                int nonce = CryptoRandom.Instance.Next();
                unauthClient = new UnauthenticatedClient(conn, nonce);
                unauthenticatedClients.Add(unauthClient);
            }
            //if the client is already in the queue, getting another unauth request means that our response was lost; resend
            NetOutgoingMessage nonceMsg = server.CreateMessage();
            nonceMsg.Write((byte)ServerPacketHeader.AUTH_RESPONSE);
            if (string.IsNullOrEmpty(password))
            {
                nonceMsg.Write(false); //false = no password
            }
            else
            {
                nonceMsg.Write(true); //true = password
                nonceMsg.Write(unauthClient.Nonce); //here's nonce, encrypt with this
            }
            server.SendMessage(nonceMsg, conn, NetDeliveryMethod.Unreliable);
        }

        private void ClientInitialize(NetIncomingMessage inc)
        {
            if (ConnectedClients.Find(c => c.Connection == inc.SenderConnection) != null)
            {
                //this client was already authenticated
                //another init request means they didn't get any update packets yet
                return;
            }

            UnauthenticatedClient unauthClient = unauthenticatedClients.Find(uc => uc.Connection == inc.SenderConnection);
            if (unauthClient == null)
            {
                //client did not ask for nonce first, can't authorize
                inc.SenderConnection.Disconnect("Client did not properly request authentication.");
                return;
            }

            if (!string.IsNullOrEmpty(password))
            {
                //decrypt message and compare password
                string saltedPw = password;
                saltedPw = saltedPw + Convert.ToString(unauthClient.Nonce);
                saltedPw = Encoding.UTF8.GetString(NetUtility.ComputeSHAHash(Encoding.UTF8.GetBytes(saltedPw)));
                NetEncryption algo = new NetXtea(server, saltedPw);
                inc.Decrypt(algo);
                string clPw = inc.ReadString();
                if (clPw != saltedPw)
                {
                    unauthClient.failedAttempts++;
                    if (unauthClient.failedAttempts > 3)
                    {
                        //disconnect after too many failed attempts
                        unauthClient.Connection.Disconnect("Too many failed login attempts.");
                        unauthenticatedClients.Remove(unauthClient);
                        unauthClient = null;
                        return;
                    }
                    else
                    {
                        //not disconnecting the player here, because they'll still use the same connection and nonce if they try logging in again
                        NetOutgoingMessage reject = server.CreateMessage();
                        reject.Write((byte)ServerPacketHeader.AUTH_FAILURE);
                        reject.Write("Wrong password!");
                        server.SendMessage(reject, unauthClient.Connection, NetDeliveryMethod.Unreliable);
                        return;
                    }
                }
            }
            string clVersion = inc.ReadString();
            string clPackageName = inc.ReadString();
            string clPackageHash = inc.ReadString();

            if (clVersion != GameMain.Version.ToString())
            {
                inc.SenderConnection.Disconnect("Version " + GameMain.Version + " required to connect to the server (Your version: " + clVersion + ")");
                unauthenticatedClients.Remove(unauthClient);
                unauthClient = null;
                DebugConsole.NewMessage(name + " couldn't join the server (wrong game version)", Color.Red);
                return;
            }
            if (clPackageName != GameMain.SelectedPackage.Name)
            {
                inc.SenderConnection.Disconnect("Your content package (" + clPackageName + ") doesn't match the server's version (" + GameMain.SelectedPackage.Name + ")");
                unauthenticatedClients.Remove(unauthClient);
                unauthClient = null;
                DebugConsole.NewMessage(name + " couldn't join the server (wrong content package name)", Color.Red);
                return;
            }
            if (clPackageHash != GameMain.SelectedPackage.MD5hash.Hash)
            {
                unauthClient.Connection.Disconnect("Your content package (MD5: " + clPackageHash + ") doesn't match the server's version (MD5: " + GameMain.SelectedPackage.MD5hash.Hash + ")");
                unauthenticatedClients.Remove(unauthClient);
                unauthClient = null;
                DebugConsole.NewMessage(name + " couldn't join the server (wrong content package hash)", Color.Red);
                return;
            }

            string clName = Client.SanitizeName(inc.ReadString());
            if (string.IsNullOrWhiteSpace(clName))
            {
                unauthClient.Connection.Disconnect("You need a name.");
                unauthenticatedClients.Remove(unauthClient);
                unauthClient = null;
                return;
            }
            if (!Client.IsValidName(name))
            {
                unauthClient.Connection.Disconnect("Your name contains illegal symbols.");
                unauthenticatedClients.Remove(unauthClient);
                unauthClient = null;
                return;
            }
            Client nameTaken = ConnectedClients.Find(c => c.name.ToLower() == clName.ToLower());
            if (nameTaken != null)
            {
                if (nameTaken.Connection.RemoteEndPoint.Address.ToString() == inc.SenderEndPoint.Address.ToString())
                {
                    //both name and IP address match, replace this player's connection
                    nameTaken.Connection.Disconnect("Your session was taken by a new connection on the same IP address.");
                    nameTaken.Connection = unauthClient.Connection;
                    unauthenticatedClients.Remove(unauthClient);
                    unauthClient = null;
                    return;
                }
                else
                {
                    //can't authorize this client
                    unauthClient.Connection.Disconnect("That name is taken.");
                    unauthenticatedClients.Remove(unauthClient);
                    unauthClient = null;
                    return;
                }
            }

            //new client
            Client newClient = new Client(clName, GetNewClientID());
            newClient.Connection = unauthClient.Connection;
            unauthenticatedClients.Remove(unauthClient);
            unauthClient = null;
            return;
        }
    }
}