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/*
* Copyright (c) 2024 Vaughn Nugent
*
* Library: VNLib
* Package: VNLib.Plugins.Essentials
* File: WebSocketSession.cs
*
* WebSocketSession.cs is part of VNLib.Plugins.Essentials which is part of the larger
* VNLib collection of libraries and utilities.
*
* VNLib.Plugins.Essentials is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* VNLib.Plugins.Essentials is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see https://www.gnu.org/licenses/.
*/
using System;
using System.IO;
using System.Threading;
using System.Net.WebSockets;
using System.Threading.Tasks;
using VNLib.Net.Http;
namespace VNLib.Plugins.Essentials
{
/// <summary>
/// A callback method to invoke when an HTTP service successfully transfers protocols to
/// the WebSocket protocol and the socket is ready to be used
/// </summary>
/// <param name="session">The open websocket session instance</param>
/// <returns>
/// A <see cref="Task"/> that will be awaited by the HTTP layer. When the task completes, the transport
/// will be closed and the session disposed
/// </returns>
public delegate Task WebSocketAcceptedCallback(WebSocketSession session);
/// <summary>
/// A callback method to invoke when an HTTP service successfully transfers protocols to
/// the WebSocket protocol and the socket is ready to be used
/// </summary>
/// <typeparam name="T">The type of the user state object</typeparam>
/// <param name="session">The open websocket session instance</param>
/// <returns>
/// A <see cref="Task"/> that will be awaited by the HTTP layer. When the task completes, the transport
/// will be closed and the session disposed
/// </returns>
public delegate Task WebSocketAcceptedCallback<T>(WebSocketSession<T> session);
/// <summary>
/// Represents a <see cref="WebSocket"/> wrapper to manage the lifetime of the captured
/// connection context and the underlying transport. This session is managed by the parent
/// <see cref="HttpServer"/> that it was created on.
/// </summary>
public class WebSocketSession(WebSocketAcceptedCallback callback) : AlternateProtocolBase
{
internal WebSocket? WsHandle;
internal readonly WebSocketAcceptedCallback AcceptedCallback = callback;
/// <summary>
/// A cancellation token that can be monitored to reflect the state
/// of the webscocket
/// </summary>
public CancellationToken Token => CancelSource.Token;
/// <summary>
/// Id assigned to this instance on creation
/// </summary>
public required string SocketID { get; init; }
/// <summary>
/// Negotiated sub-protocol
/// </summary>
public string? SubProtocol { get; internal init; }
/// <summary>
/// The websocket keep-alive interval
/// </summary>
internal TimeSpan KeepAlive { get; init; }
/// <summary>
/// Initialzes the created websocket with the specified protocol
/// </summary>
/// <param name="transport">Transport stream to use for the websocket</param>
/// <returns>The accept callback function specified during object initialization</returns>
protected override async Task RunAsync(Stream transport)
{
try
{
WebSocketCreationOptions ce = new()
{
IsServer = true,
KeepAliveInterval = KeepAlive,
SubProtocol = SubProtocol,
};
//Create a new websocket from the context stream
WsHandle = WebSocket.CreateFromStream(transport, ce);
//Register token to abort the websocket so the managed ws uses the non-fallback send/recv method
using CancellationTokenRegistration abortReg = Token.Register(WsHandle.Abort);
//Return the callback function to explcitly invoke it
await AcceptedCallback(this);
}
finally
{
WsHandle?.Dispose();
}
}
/// <summary>
/// Asynchronously receives data from the Websocket and copies the data to the specified buffer
/// </summary>
/// <param name="buffer">The buffer to store read data</param>
/// <returns>A task that resolves a <see cref="WebSocketReceiveResult"/> which contains the status of the operation</returns>
/// <exception cref="OperationCanceledException"></exception>
public Task<WebSocketReceiveResult> ReceiveAsync(ArraySegment<byte> buffer) => WsHandle!.ReceiveAsync(buffer, CancellationToken.None);
/// <summary>
/// Asynchronously receives data from the Websocket and copies the data to the specified buffer
/// </summary>
/// <param name="buffer">The buffer to store read data</param>
/// <returns></returns>
/// <exception cref="OperationCanceledException"></exception>
public ValueTask<ValueWebSocketReceiveResult> ReceiveAsync(Memory<byte> buffer) => WsHandle!.ReceiveAsync(buffer, CancellationToken.None);
/// <summary>
/// Asynchronously sends the specified buffer to the client of the specified type
/// </summary>
/// <param name="buffer">The buffer containing data to send</param>
/// <param name="type">The message/data type of the packet to send</param>
/// <param name="endOfMessage">A value that indicates this message is the final message of the transaction</param>
/// <returns></returns>
/// <exception cref="OperationCanceledException"></exception>
public Task SendAsync(ArraySegment<byte> buffer, WebSocketMessageType type, bool endOfMessage) => WsHandle!.SendAsync(buffer, type, endOfMessage, CancellationToken.None);
/// <summary>
/// Asynchronously sends the specified buffer to the client of the specified type
/// </summary>
/// <param name="buffer">The buffer containing data to send</param>
/// <param name="type">The message/data type of the packet to send</param>
/// <param name="endOfMessage">A value that indicates this message is the final message of the transaction</param>
/// <returns></returns>
/// <exception cref="OperationCanceledException"></exception>
public ValueTask SendAsync(ReadOnlyMemory<byte> buffer, WebSocketMessageType type, bool endOfMessage)
{
//Begin receive operation only with the internal token
return SendAsync(buffer, type, endOfMessage ? WebSocketMessageFlags.EndOfMessage : WebSocketMessageFlags.None);
}
/// <summary>
/// Asynchronously sends the specified buffer to the client of the specified type
/// </summary>
/// <param name="buffer">The buffer containing data to send</param>
/// <param name="type">The message/data type of the packet to send</param>
/// <param name="flags">Websocket message flags</param>
/// <returns></returns>
/// <exception cref="OperationCanceledException"></exception>
public ValueTask SendAsync(ReadOnlyMemory<byte> buffer, WebSocketMessageType type, WebSocketMessageFlags flags)
=> WsHandle!.SendAsync(buffer, type, flags, CancellationToken.None);
/// <summary>
/// Properly closes a currently connected websocket
/// </summary>
/// <param name="status">Set the close status</param>
/// <param name="reason">Set the close reason</param>
/// <exception cref="ObjectDisposedException"></exception>
public Task CloseSocketAsync(WebSocketCloseStatus status, string reason) => WsHandle!.CloseAsync(status, reason, CancellationToken.None);
/// <summary>
///
/// </summary>
/// <param name="status"></param>
/// <param name="reason"></param>
/// <param name="cancellation"></param>
/// <returns></returns>
public Task CloseSocketOutputAsync(WebSocketCloseStatus status, string reason, CancellationToken cancellation = default)
{
if (WsHandle!.State == WebSocketState.Open || WsHandle.State == WebSocketState.CloseSent)
{
return WsHandle.CloseOutputAsync(status, reason, cancellation);
}
return Task.CompletedTask;
}
}
/// <summary>
/// <inheritdoc/>
/// </summary>
/// <typeparam name="T">The user-state type</typeparam>
public sealed class WebSocketSession<T> : WebSocketSession
{
#nullable disable
/// <summary>
/// A user-defined state object passed during socket accept handshake
/// </summary>
public T UserState { get; internal init; }
#nullable enable
internal WebSocketSession(WebSocketAcceptedCallback<T> callback)
: base((ses) => callback((ses as WebSocketSession<T>)!))
{
UserState = default;
}
}
}
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