buff2.0/steam-client/steamAPI/Program.cs

using System;
using System.IO;
using System.Linq;
using System.Net;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.Hosting;
using Newtonsoft.Json;
using SteamAuth;
using SteamKit2;
using SteamKit2.Authentication;

var builder = WebApplication.CreateBuilder(args);
var app = builder.Build();

app.MapPost("/login", async (HttpContext http) =>
{
    var req = await GetRequestBodyAsync(http);
    if (req == null)
    {
        http.Response.StatusCode = 400;
        await http.Response.WriteAsync("invalid request");
        return;
    }

    if (!File.Exists(req.MaFilePath))
    {
        http.Response.StatusCode = 400;
        await http.Response.WriteAsync("maFile not found");
        return;
    }

    SteamGuardAccount? account;
    try
    {
        var contents = await File.ReadAllTextAsync(req.MaFilePath);
        account = JsonConvert.DeserializeObject<SteamGuardAccount>(contents);
    }
    catch (Exception ex)
    {
        http.Response.StatusCode = 500;
        await http.Response.WriteAsync("failed to read maFile: " + ex.Message);
        return;
    }

    try
    {
        // Start SteamClient and authenticate using the maFile-provided SteamGuardAccount
        SteamClient steamClient = new SteamClient();
        steamClient.Connect();

        var timeoutMs = 15000;
        var waited = 0;
        while (!steamClient.IsConnected && waited < timeoutMs)
        {
            await Task.Delay(200);
            waited += 200;
        }
        if (!steamClient.IsConnected)
        {
            http.Response.StatusCode = 500;
            await http.Response.WriteAsync("failed to connect to steam network");
            return;
        }

        CredentialsAuthSession authSession = await steamClient.Authentication.BeginAuthSessionViaCredentialsAsync(new AuthSessionDetails
        {
            Username = req.Username,
            Password = req.Password,
            IsPersistentSession = false,
            // PlatformType and ClientOSType are optional; omit to avoid enum symbol differences across SteamKit2 versions.
            Authenticator = new FileAuthenticator(account),
        });

        var pollResponse = await authSession.PollingWaitForResultAsync();

        var sessionData = new SessionData()
        {
            SteamID = authSession.SteamID.ConvertToUInt64(),
            AccessToken = pollResponse.AccessToken,
            RefreshToken = pollResponse.RefreshToken,
        };

        // Serialize cookies
        var uri = new Uri("https://steamcommunity.com");
        var cookies = sessionData.GetCookies().GetCookies(uri).Cast<Cookie>().Select(c => new
        {
            name = c.Name,
            value = c.Value,
            domain = c.Domain,
            path = c.Path,
            expires = c.Expires == DateTime.MinValue ? null : (DateTime?)c.Expires
        }).ToArray();

        var resp = new
        {
            session = new
            {
                steamId = sessionData.SteamID,
                accessToken = sessionData.AccessToken,
                refreshToken = sessionData.RefreshToken,
                sessionId = sessionData.SessionID
            },
            cookies = cookies
        };

        http.Response.ContentType = "application/json";
        await http.Response.WriteAsync(JsonConvert.SerializeObject(resp, Formatting.Indented));
        return;
    }
    catch (Exception ex)
    {
        http.Response.StatusCode = 500;
        await http.Response.WriteAsync("login failed: " + ex.Message);
        return;
    }
});

app.Run();

async Task<LoginRequest?> GetRequestBodyAsync(HttpContext http)
{
    try
    {
        using var sr = new StreamReader(http.Request.Body);
        var body = await sr.ReadToEndAsync();
        if (string.IsNullOrWhiteSpace(body)) return null;
        return JsonConvert.DeserializeObject<LoginRequest>(body);
    }
    catch
    {
        return null;
    }
}

record LoginRequest(string Username, string Password, string MaFilePath);

internal class FileAuthenticator : IAuthenticator
{
    private readonly SteamGuardAccount? account;
    private int deviceCodesGenerated = 0;

    public FileAuthenticator(SteamGuardAccount? account)
    {
        this.account = account;
    }

    public Task<bool> AcceptDeviceConfirmationAsync()
    {
        return Task.FromResult(false);
    }

    public async Task<string> GetDeviceCodeAsync(bool previousCodeWasIncorrect)
    {
        if (previousCodeWasIncorrect)
        {
            if (deviceCodesGenerated > 2)
                throw new Exception("failed to generate device code from maFile");
            await Task.Delay(30000);
        }

        if (account == null) return null;
        deviceCodesGenerated++;
        var code = await account.GenerateSteamGuardCodeAsync();
        return code ?? "";
    }

    public Task<string> GetEmailCodeAsync(string email, bool previousCodeWasIncorrect)
    {
        // This implementation does not support interactive email codes.
        return Task.FromResult(string.Empty);
    }
}