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fix: handle disposed socket on close attempt #1591

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fix: handle disposed socket on close attempt #1591

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7961fd1
fix: handle disposed socket on close attempt
ezhevita Oct 15, 2025
1a16c80
fix: only attempt to close connection if not disposed
ezhevita Oct 16, 2025
289d4af
fix: wrap it all in semaphore since race condition after passing clos…
ezhevita Oct 16, 2025
b13b19e
fix: acquire semaphore before main connection loop
ezhevita Nov 17, 2025
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75 changes: 47 additions & 28 deletions SteamKit2/SteamKit2/Networking/Steam3/WebSocketContext.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -21,12 +21,14 @@ public WebSocketContext(WebSocketConnection connection, EndPoint endPoint)

cts = new CancellationTokenSource();
socket = new ClientWebSocket();
semaphore = new SemaphoreSlim( 1, 1 );
connectionUri = ConstructUri(endPoint);
}

readonly WebSocketConnection connection;
readonly CancellationTokenSource cts;
readonly ClientWebSocket socket;
readonly SemaphoreSlim semaphore;
readonly Uri connectionUri;
Task? runloopTask;
int disposed;
Expand Down Expand Up @@ -66,38 +68,47 @@ async Task RunCore(HttpMessageInvoker invoker, TimeSpan connectionTimeout, Cance
connection.log.LogDebug( nameof(WebSocketContext), "Connected to {0}", connectionUri);
connection.Connected?.Invoke(connection, EventArgs.Empty);

while (!cancellationToken.IsCancellationRequested && socket.State == WebSocketState.Open)
{
byte[]? packet = null;
await semaphore.WaitAsync(CancellationToken.None).ConfigureAwait( false );

try
{
packet = await ReadMessageAsync( cancellationToken ).ConfigureAwait( false );
}
catch ( Exception ex )
try
{
while (!cancellationToken.IsCancellationRequested && socket.State == WebSocketState.Open)
{
connection.log.LogDebug( nameof( WebSocketContext ), "Exception reading from websocket: {0} - {1}", ex.GetType().FullName, ex.Message );
connection.DisconnectCore( userInitiated: false, specificContext: this );
return;
byte[]? packet = null;

try
{
packet = await ReadMessageAsync( cancellationToken ).ConfigureAwait( false );
}
catch ( Exception ex )
{
connection.log.LogDebug( nameof( WebSocketContext ), "Exception reading from websocket: {0} - {1}", ex.GetType().FullName, ex.Message );
connection.DisconnectCore( userInitiated: false, specificContext: this );
return;
}

if (packet != null && packet.Length > 0)
{
connection.NetMsgReceived?.Invoke(connection, new NetMsgEventArgs(packet, EndPoint));
}
}

if (packet != null && packet.Length > 0)
if (!cancellationToken.IsCancellationRequested && socket.State == WebSocketState.Open)
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@xPaw xPaw Nov 28, 2025

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Will socket.Dispose close cleanly, or should it still let CloseAsync be called here?

{
connection.NetMsgReceived?.Invoke(connection, new NetMsgEventArgs(packet, EndPoint));
connection.log.LogDebug( nameof(WebSocketContext), "Closing connection...");
try
{
await socket.CloseAsync(WebSocketCloseStatus.NormalClosure, null, default).ConfigureAwait(false);
}
catch (Win32Exception ex)
{
connection.log.LogDebug( nameof(WebSocketContext), "Error closing connection: {0}", ex.Message);
}
}
}

if (socket.State == WebSocketState.Open)
finally
{
connection.log.LogDebug( nameof(WebSocketContext), "Closing connection...");
try
{
await socket.CloseAsync(WebSocketCloseStatus.NormalClosure, null, default).ConfigureAwait(false);
}
catch (Win32Exception ex)
{
connection.log.LogDebug( nameof(WebSocketContext), "Error closing connection: {0}", ex.Message);
}
semaphore.Release();
}
}

Expand All @@ -117,16 +128,24 @@ public async Task SendAsync(Memory<byte> data)

public void Dispose()
{
if (Interlocked.Exchange(ref disposed, 1) == 1)
if ( Interlocked.Exchange( ref disposed, 1 ) == 1 )
{
return;
}

cts.Cancel();
cts.Dispose();
runloopTask = null;
semaphore.Wait();
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@xPaw xPaw Nov 28, 2025

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I wouldn't mind an explanatory comment here as to what flow is happening in regards to the semaphore and the cancellation.

try
{
cts.Dispose();
runloopTask = null;

socket.Dispose();
socket.Dispose();
}
finally
{
semaphore.Dispose();
}
}

async Task<byte[]?> ReadMessageAsync( CancellationToken cancellationToken )
Expand Down