BSO-Server/MasterClient.cs

using System.Net.Http.Json;
using System.Security.Cryptography;
using System.Text.Json;
using BSO.Net;

namespace BSO.Server;

/// <summary>
/// Verbindung zur BSO-Website (wie MasterClient bei MSCO): jede Minute ein Heartbeat fuer die Serverliste, beim Beenden
/// abmelden. Ausserdem der oeffentliche Ticket-Schluessel, mit dem der Server die Konten der Spieler prueft - er wird in
/// ticket-key.xml zwischengespeichert, damit ein Neustart auch ohne Website klappt.
/// </summary>
public class MasterClient
{
    public const string DefaultUrl = "https://bso.mbm.wtf";
    static readonly TimeSpan Interval = TimeSpan.FromSeconds(60);

    readonly string url;
    readonly GameServer server;
    readonly int port;
    readonly bool listed;
    readonly string publicAddress, description;
    readonly HttpClient http = new() { Timeout = TimeSpan.FromSeconds(15) };
    readonly CancellationTokenSource stop = new();
    bool? lastReachable;

    public RSA TicketKey { get; private set; }
    static string KeyFile => Path.Combine(AppContext.BaseDirectory, "ticket-key.xml");

    public MasterClient(string url, GameServer server, int port, bool listed, string publicAddress, string description)
    {
        this.url = url.TrimEnd('/');
        this.server = server;
        this.port = port;
        this.listed = listed;
        this.publicAddress = publicAddress;
        this.description = description;
        http.DefaultRequestHeaders.UserAgent.ParseAdd("BSO-Server/" + GameServer.Version);
    }

    /// <summary>Ticket-Schluessel von der Website - sonst der zuletzt gespeicherte.</summary>
    public async Task LoadTicketKeyAsync()
    {
        string xml = null;
        try
        {
            var r = await http.GetFromJsonAsync<JsonElement>(url + "/api/auth/ticket-key");
            xml = r.GetProperty("key").GetString();
            File.WriteAllText(KeyFile, xml);
            GameServer.Log("Ticket-Schluessel von " + url + " geladen - Spieler brauchen ein BSO-Konto");
        }
        catch (Exception e)
        {
            if (File.Exists(KeyFile))
            {
                xml = File.ReadAllText(KeyFile);
                GameServer.Log($"Website nicht erreichbar ({e.Message}) - nehme gespeicherten Ticket-Schluessel");
            }
            else GameServer.Log($"Website nicht erreichbar ({e.Message}) und kein gespeicherter Ticket-Schluessel - niemand kann beitreten (zum Testen: --no-auth)");
        }
        if (xml == null) return;
        var rsa = RSA.Create();
        rsa.FromXmlString(xml);
        TicketKey = rsa;
    }

    public void Start()
    {
        if (!listed) { GameServer.Log("Nicht in der Serverliste (--private) - Beitritt nur per Adresse"); return; }
        _ = Task.Run(async () =>
        {
            while (!stop.IsCancellationRequested)
            {
                await Heartbeat();
                try { await Task.Delay(Interval, stop.Token); } catch (TaskCanceledException) { }
            }
        });
    }

    async Task Heartbeat()
    {
        try
        {
            var res = await http.PostAsJsonAsync(url + "/api/servers/heartbeat", new
            {
                name = server.Name,
                description,
                port,
                players = server.PlayerCount,
                maxPlayers = server.MaxPlayers,
                version = GameServer.Version,
                protocol = Protocol.Version,
                publicAddress,
                @public = true
            });
            var r = await res.Content.ReadFromJsonAsync<JsonElement>();
            if (!res.IsSuccessStatusCode)
            {
                GameServer.Log("Serverliste: " + (r.TryGetProperty("error", out var err) ? err.GetString() : res.StatusCode.ToString()));
                return;
            }
            bool? reachable = r.GetProperty("reachable").ValueKind switch { JsonValueKind.True => true, JsonValueKind.False => false, _ => null };
            if (reachable != lastReachable && reachable != null)
                GameServer.Log(reachable == true
                    ? $"In der Serverliste als {r.GetProperty("address").GetString()}"
                    : $"Nicht in der Serverliste: die Website erreicht {r.GetProperty("address").GetString()} nicht - Port {port}/TCP freigeben (oder --public-address)");
            lastReachable = reachable ?? lastReachable;
        }
        catch (Exception e)
        {
            GameServer.Log("Serverliste nicht erreichbar: " + e.Message);
        }
    }

    public void Stop()
    {
        stop.Cancel();
        if (!listed) return;
        try { http.PostAsJsonAsync(url + "/api/servers/unregister", new { port, publicAddress }).Wait(3000); } catch { }
    }
}