jellyfin/Emby.Server.Implementations/Net/SocketFactory.cs

using System;
using System.IO;
using System.Net;
using System.Net.Sockets;
using Emby.Server.Implementations.Networking;
using MediaBrowser.Model.Net;
using Microsoft.Extensions.Logging;

namespace Emby.Server.Implementations.Net
{
    public class SocketFactory : ISocketFactory
    {
        // THIS IS A LINKED FILE - SHARED AMONGST MULTIPLE PLATFORMS
        // Be careful to check any changes compile and work for all platform projects it is shared in.

        // Not entirely happy with this. Would have liked to have done something more generic/reusable,
        // but that wasn't really the point so kept to YAGNI principal for now, even if the
        // interfaces are a bit ugly, specific and make assumptions.

        public ISocket CreateTcpSocket(IpAddressInfo remoteAddress, int remotePort)
        {
            if (remotePort < 0) throw new ArgumentException("remotePort cannot be less than zero.", nameof(remotePort));

            var addressFamily = remoteAddress.AddressFamily == IpAddressFamily.InterNetwork
                ? AddressFamily.InterNetwork
                : AddressFamily.InterNetworkV6;

            var retVal = new Socket(addressFamily, System.Net.Sockets.SocketType.Stream, System.Net.Sockets.ProtocolType.Tcp);

            try
            {
                retVal.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
            }
            catch (SocketException)
            {
                // This is not supported on all operating systems (qnap)
            }

            try
            {
                return new UdpSocket(retVal, new IpEndPointInfo(remoteAddress, remotePort));
            }
            catch
            {
                if (retVal != null)
                    retVal.Dispose();

                throw;
            }
        }

        /// <summary>
        /// Creates a new UDP acceptSocket and binds it to the specified local port.
        /// </summary>
        /// <param name="localPort">An integer specifying the local port to bind the acceptSocket to.</param>
        public ISocket CreateUdpSocket(int localPort)
        {
            if (localPort < 0) throw new ArgumentException("localPort cannot be less than zero.", nameof(localPort));

            var retVal = new Socket(AddressFamily.InterNetwork, System.Net.Sockets.SocketType.Dgram, System.Net.Sockets.ProtocolType.Udp);
            try
            {
                retVal.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
                return new UdpSocket(retVal, localPort, IPAddress.Any);
            }
            catch
            {
                if (retVal != null)
                    retVal.Dispose();

                throw;
            }
        }

        public ISocket CreateUdpBroadcastSocket(int localPort)
        {
            if (localPort < 0) throw new ArgumentException("localPort cannot be less than zero.", nameof(localPort));

            var retVal = new Socket(AddressFamily.InterNetwork, System.Net.Sockets.SocketType.Dgram, System.Net.Sockets.ProtocolType.Udp);
            try
            {
                retVal.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
                retVal.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.Broadcast, 1);

                return new UdpSocket(retVal, localPort, IPAddress.Any);
            }
            catch
            {
                if (retVal != null)
                    retVal.Dispose();

                throw;
            }
        }

        /// <summary>
        /// Creates a new UDP acceptSocket that is a member of the SSDP multicast local admin group and binds it to the specified local port.
        /// </summary>
        /// <returns>An implementation of the <see cref="ISocket"/> interface used by RSSDP components to perform acceptSocket operations.</returns>
        public ISocket CreateSsdpUdpSocket(IpAddressInfo localIpAddress, int localPort)
        {
            if (localPort < 0) throw new ArgumentException("localPort cannot be less than zero.", nameof(localPort));

            var retVal = new Socket(AddressFamily.InterNetwork, System.Net.Sockets.SocketType.Dgram, System.Net.Sockets.ProtocolType.Udp);
            try
            {
                retVal.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
                retVal.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.MulticastTimeToLive, 4);

                var localIp = NetworkManager.ToIPAddress(localIpAddress);

                retVal.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.AddMembership, new MulticastOption(IPAddress.Parse("239.255.255.250"), localIp));
                return new UdpSocket(retVal, localPort, localIp);
            }
            catch
            {
                if (retVal != null)
                    retVal.Dispose();

                throw;
            }
        }

        /// <summary>
        /// Creates a new UDP acceptSocket that is a member of the specified multicast IP address, and binds it to the specified local port.
        /// </summary>
        /// <param name="ipAddress">The multicast IP address to make the acceptSocket a member of.</param>
        /// <param name="multicastTimeToLive">The multicast time to live value for the acceptSocket.</param>
        /// <param name="localPort">The number of the local port to bind to.</param>
        /// <returns></returns>
        public ISocket CreateUdpMulticastSocket(string ipAddress, int multicastTimeToLive, int localPort)
        {
            if (ipAddress == null) throw new ArgumentNullException(nameof(ipAddress));
            if (ipAddress.Length == 0) throw new ArgumentException("ipAddress cannot be an empty string.", nameof(ipAddress));
            if (multicastTimeToLive <= 0) throw new ArgumentException("multicastTimeToLive cannot be zero or less.", nameof(multicastTimeToLive));
            if (localPort < 0) throw new ArgumentException("localPort cannot be less than zero.", nameof(localPort));

            var retVal = new Socket(AddressFamily.InterNetwork, System.Net.Sockets.SocketType.Dgram, System.Net.Sockets.ProtocolType.Udp);

            try
            {
                // not supported on all platforms. throws on ubuntu with .net core 2.0
                retVal.ExclusiveAddressUse = false;
            }
            catch (SocketException)
            {

            }

            try
            {
                // seeing occasional exceptions thrown on qnap
                // System.Net.Sockets.SocketException (0x80004005): Protocol not available
                retVal.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
            }
            catch (SocketException)
            {

            }

            try
            {
                //retVal.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.Broadcast, true);
                retVal.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.MulticastTimeToLive, multicastTimeToLive);

                var localIp = IPAddress.Any;

                retVal.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.AddMembership, new MulticastOption(IPAddress.Parse(ipAddress), localIp));
                retVal.MulticastLoopback = true;

                return new UdpSocket(retVal, localPort, localIp);
            }
            catch
            {
                if (retVal != null)
                    retVal.Dispose();

                throw;
            }
        }

        public Stream CreateNetworkStream(ISocket socket, bool ownsSocket)
        {
            var netSocket = (UdpSocket)socket;

            return new SocketStream(netSocket.Socket, ownsSocket);
        }
    }

    public class SocketStream : Stream
    {
        private readonly Socket _socket;

        public SocketStream(Socket socket, bool ownsSocket)
        {
            _socket = socket;
        }

        public override void Flush()
        {
        }

        public override bool CanRead => true;

        public override bool CanSeek => false;

        public override bool CanWrite => true;

        public override long Length => throw new NotImplementedException();

        public override long Position
        {
            get => throw new NotImplementedException();
            set => throw new NotImplementedException();
        }

        public override void Write(byte[] buffer, int offset, int count)
        {
            _socket.Send(buffer, offset, count, SocketFlags.None);
        }

        public override IAsyncResult BeginWrite(byte[] buffer, int offset, int count, AsyncCallback callback, object state)
        {
            return _socket.BeginSend(buffer, offset, count, SocketFlags.None, callback, state);
        }

        public override void EndWrite(IAsyncResult asyncResult)
        {
            _socket.EndSend(asyncResult);
        }

        public override void SetLength(long value)
        {
            throw new NotImplementedException();
        }

        public override long Seek(long offset, SeekOrigin origin)
        {
            throw new NotImplementedException();
        }

        public override int Read(byte[] buffer, int offset, int count)
        {
            return _socket.Receive(buffer, offset, count, SocketFlags.None);
        }

        public override IAsyncResult BeginRead(byte[] buffer, int offset, int count, AsyncCallback callback, object state)
        {
            return _socket.BeginReceive(buffer, offset, count, SocketFlags.None, callback, state);
        }

        public override int EndRead(IAsyncResult asyncResult)
        {
            return _socket.EndReceive(asyncResult);
        }
    }

}