SVSimServer/SVSim.BattleNode/Hosting/BattleNodeWebSocketHandler.cs

// SVSim.BattleNode/Hosting/BattleNodeWebSocketHandler.cs
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.Logging;
using SVSim.BattleNode.Sessions;
using SVSim.BattleNode.Wire;

namespace SVSim.BattleNode.Hosting;

public sealed class BattleNodeWebSocketHandler
{
    private readonly IBattleSessionStore _store;
    private readonly ILogger<BattleNodeWebSocketHandler> _log;
    private readonly ILoggerFactory _loggerFactory;

    public BattleNodeWebSocketHandler(IBattleSessionStore store, ILoggerFactory loggerFactory)
    {
        _store = store;
        _loggerFactory = loggerFactory;
        _log = loggerFactory.CreateLogger<BattleNodeWebSocketHandler>();
    }

    public async Task HandleAsync(HttpContext ctx)
    {
        if (!ctx.WebSockets.IsWebSocketRequest)
        {
            ctx.Response.StatusCode = StatusCodes.Status400BadRequest;
            return;
        }

        // BestHTTP's SocketOptions.AdditionalQueryParams puts these on HTTP request HEADERS
        // for the WebSocket-only transport (not on the URL query string). Real clients
        // therefore send BattleId/viewerId as headers; the integration test sends them as
        // query params for convenience. Check headers first, fall back to query.
        var battleId = ReadCredential(ctx, "BattleId");
        var encryptedViewerId = ReadCredential(ctx, "viewerId");
        if (string.IsNullOrEmpty(battleId) || string.IsNullOrEmpty(encryptedViewerId))
        {
            _log.LogWarning("WS upgrade missing BattleId or viewerId (header or query).");
            ctx.Response.StatusCode = StatusCodes.Status400BadRequest;
            return;
        }

        long viewerId;
        try
        {
            var plain = NodeCrypto.DecryptForNode(encryptedViewerId);
            viewerId = long.Parse(plain);
        }
        catch (Exception ex)
        {
            _log.LogWarning(ex, "viewerId failed to decrypt (encryptedLen={Len})", encryptedViewerId.Length);
            ctx.Response.StatusCode = StatusCodes.Status400BadRequest;
            return;
        }

        var pending = _store.TryGetPending(battleId);
        if (pending is null || pending.ViewerId != viewerId)
        {
            _log.LogWarning("Unknown battle/viewer pair: {Bid}/{Vid}", battleId, viewerId);
            ctx.Response.StatusCode = StatusCodes.Status400BadRequest;
            return;
        }

        var ws = await ctx.WebSockets.AcceptWebSocketAsync();
        _store.RemovePending(battleId);
        var session = new BattleSession(ws, battleId, viewerId, _loggerFactory.CreateLogger<BattleSession>());
        await session.RunAsync(ctx.RequestAborted);
    }

    private static string ReadCredential(HttpContext ctx, string name)
    {
        var header = ctx.Request.Headers[name].ToString();
        if (!string.IsNullOrEmpty(header)) return header;
        return ctx.Request.Query[name].ToString();
    }
}