SVSimServer/SVSim.EmulatedEntrypoint/Services/SteamSessionService.cs

using System.Collections.Concurrent;
using System.Globalization;
using Microsoft.Extensions.Caching.Memory;
using Steamworks;

namespace SVSim.EmulatedEntrypoint.Services;

public class SteamSessionService : IDisposable
{
    private readonly ConcurrentDictionary<string, ulong> _validatedSessionTickets;

    private const int ShadowVerseAppId = 453480;
    
    public SteamSessionService()
    {
        _validatedSessionTickets = new ConcurrentDictionary<string, ulong>();
        SteamServer.Init(ShadowVerseAppId, new SteamServerInit
        {
            GamePort = default,
            QueryPort = default
        });
    }

    /// <summary>
    /// Validates if a given session ticket is valid, and matches up with the given steamid.
    /// </summary>
    /// <param name="ticket">the ticket, represented as a hexadecimal string</param>
    /// <param name="steamId">the steamid that should be associated with the ticket</param>
    /// <returns>whether the ticket is valid for the given steamid</returns>
    public bool IsTicketValidForUser(string ticket, ulong steamId)
    {
        if (_validatedSessionTickets.TryGetValue(ticket, out ulong storedSteamId))
        {
            return storedSteamId == steamId;
        }

        List<byte> ticketBytes = new List<byte>();
        for (int i = 0; i < ticket.Length; i += 2)
        {
            ticketBytes.Add(Convert.ToByte(ticket.Substring(i, 2), 16));
        }

        var steamCheckResults = SteamServer.BeginAuthSession(ticketBytes.ToArray(), new SteamId { Value = steamId });
        if (steamCheckResults)
        {
            _validatedSessionTickets.TryAdd(ticket, storedSteamId);
        }
        
        return steamCheckResults;
    }

    public void Dispose()
    {
        SteamServer.Shutdown();
    }
}