sharp-chat/SharpChat/SharpChatWebSocketServer.cs

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#nullable disable
using Fleck;
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using System;
using System.Collections.Generic;
using System.IO;
using System.Net;
using System.Net.Sockets;
using System.Runtime.InteropServices;
using System.Security.Authentication;
using System.Security.Cryptography.X509Certificates;
using System.Text;
// Near direct reimplementation of Fleck's WebSocketServer with address reusing
// Fleck's Socket wrapper doesn't provide any way to do this with the normally provided APIs
// https://github.com/statianzo/Fleck/blob/1.1.0/src/Fleck/WebSocketServer.cs
namespace SharpChat {
public class SharpChatWebSocketServer : IWebSocketServer {
private readonly string _scheme;
private readonly IPAddress _locationIP;
private Action<IWebSocketConnection> _config;
public SharpChatWebSocketServer(string location, bool supportDualStack = true) {
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Uri uri = new(location);
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Port = uri.Port;
Location = location;
SupportDualStack = supportDualStack;
_locationIP = ParseIPAddress(uri);
_scheme = uri.Scheme;
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Socket socket = new(_locationIP.AddressFamily, SocketType.Stream, ProtocolType.IP);
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socket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, 1);
if(SupportDualStack && Type.GetType("Mono.Runtime") == null && RuntimeInformation.IsOSPlatform(OSPlatform.Windows)) {
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socket.SetSocketOption(SocketOptionLevel.IPv6, SocketOptionName.IPv6Only, false);
}
ListenerSocket = new SocketWrapper(socket);
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SupportedSubProtocols = Array.Empty<string>();
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}
public ISocket ListenerSocket { get; set; }
public string Location { get; private set; }
public bool SupportDualStack { get; }
public int Port { get; private set; }
public X509Certificate2 Certificate { get; set; }
public SslProtocols EnabledSslProtocols { get; set; }
public IEnumerable<string> SupportedSubProtocols { get; set; }
public bool RestartAfterListenError { get; set; }
public bool IsSecure {
get { return _scheme == "wss" && Certificate != null; }
}
public void Dispose() {
ListenerSocket.Dispose();
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GC.SuppressFinalize(this);
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}
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private static IPAddress ParseIPAddress(Uri uri) {
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string ipStr = uri.Host;
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if(ipStr == "0.0.0.0") {
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return IPAddress.Any;
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} else if(ipStr == "[0000:0000:0000:0000:0000:0000:0000:0000]") {
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return IPAddress.IPv6Any;
} else {
try {
return IPAddress.Parse(ipStr);
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} catch(Exception ex) {
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throw new FormatException("Failed to parse the IP address part of the location. Please make sure you specify a valid IP address. Use 0.0.0.0 or [::] to listen on all interfaces.", ex);
}
}
}
public void Start(Action<IWebSocketConnection> config) {
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IPEndPoint ipLocal = new(_locationIP, Port);
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ListenerSocket.Bind(ipLocal);
ListenerSocket.Listen(100);
Port = ((IPEndPoint)ListenerSocket.LocalEndPoint).Port;
FleckLog.Info(string.Format("Server started at {0} (actual port {1})", Location, Port));
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if(_scheme == "wss") {
if(Certificate == null) {
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FleckLog.Error("Scheme cannot be 'wss' without a Certificate");
return;
}
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if(EnabledSslProtocols == SslProtocols.None) {
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EnabledSslProtocols = SslProtocols.Tls;
FleckLog.Debug("Using default TLS 1.0 security protocol.");
}
}
ListenForClients();
_config = config;
}
private void ListenForClients() {
ListenerSocket.Accept(OnClientConnect, e => {
FleckLog.Error("Listener socket is closed", e);
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if(RestartAfterListenError) {
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FleckLog.Info("Listener socket restarting");
try {
ListenerSocket.Dispose();
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Socket socket = new(_locationIP.AddressFamily, SocketType.Stream, ProtocolType.IP);
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socket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, 1);
ListenerSocket = new SocketWrapper(socket);
Start(_config);
FleckLog.Info("Listener socket restarted");
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} catch(Exception ex) {
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FleckLog.Error("Listener could not be restarted", ex);
}
}
});
}
private void OnClientConnect(ISocket clientSocket) {
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if(clientSocket == null) return; // socket closed
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FleckLog.Debug(string.Format("Client connected from {0}:{1}", clientSocket.RemoteIpAddress, clientSocket.RemotePort.ToString()));
ListenForClients();
WebSocketConnection connection = null;
connection = new WebSocketConnection(
clientSocket,
_config,
bytes => RequestParser.Parse(bytes, _scheme),
r => {
try {
return HandlerFactory.BuildHandler(
r, s => connection.OnMessage(s), connection.Close, b => connection.OnBinary(b),
b => connection.OnPing(b), b => connection.OnPong(b)
);
} catch(WebSocketException) {
const string responseMsg = "HTTP/1.1 200 OK\r\n"
+ "Date: {0}\r\n"
+ "Server: SharpChat\r\n"
+ "Content-Length: {1}\r\n"
+ "Content-Type: text/html; charset=utf-8\r\n"
+ "Connection: close\r\n"
+ "\r\n"
+ "{2}";
string responseBody = File.Exists("http-motd.txt") ? File.ReadAllText("http-motd.txt") : "SharpChat";
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clientSocket.Stream.Write(Encoding.UTF8.GetBytes(string.Format(
responseMsg, DateTimeOffset.Now.ToString("r"), Encoding.UTF8.GetByteCount(responseBody), responseBody
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)));
clientSocket.Close();
return null;
}
},
s => SubProtocolNegotiator.Negotiate(SupportedSubProtocols, s));
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if(IsSecure) {
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FleckLog.Debug("Authenticating Secure Connection");
clientSocket
.Authenticate(Certificate,
EnabledSslProtocols,
connection.StartReceiving,
e => FleckLog.Warn("Failed to Authenticate", e));
} else {
connection.StartReceiving();
}
}
}
}