Question

我正在编写某种服务器应用程序（在C ++中），它包含服务器正在与之通信的套接字的文件描述符的fd_set，并且我希望知道其中一个是关闭的\在没有的情况下关闭不得不读\写到它。我经常阻塞select（）（没有超时），等待读取就绪和我提供的两个fd_set的异常条件。

我开始认为在另一侧关闭的任何套接字都会出现在exceptfds中，但是当我读到时，我开始明白它并不一定是这种情况。 select() man page并没有真正说明除了fds之外的其他例外情况。更进一步，我理解什么被视为异常条件changes from OS to OS（我自己正在使用Ubnubt 11.10），我还没有找到任何关于套接字被关闭\关闭（另一方面）的引用例外。

此外，socket(7) man page提到套接字可能发送的两种信号：

SIGPIPE - 在写入关闭套接字时发送。
SIGIO - 在发生I / O事件时发送。

不幸的是，没有提到构成I / O事件的内容，并且无论如何关闭可能不会被所有人视为I / O事件（我自己就是一个很好的例子）。

所以我要问的是 - 我可以在插座关闭时发送信号或将自身插入exceptfds，或以其他方式主动提示我吗？

谢谢，吉文

Answer 1

通常，当远程对等方关闭套接字时，它变为可读（出于select()的目的），当你从中读取时，你得 0 < / em>字节返回。此零字节读取表示另一端正常关闭套接字。这不是特殊情况。

Answer 2

在我自己的应用程序中，当我的select()调用（对于读取事件）返回我的文件描述符时，我调用ioctl()来查看缓冲区中有多少用于读取。如果有零个字节，那么我用它来表示连接已关闭。

当我从这个答案here at stack overflow

开始编写linux套接字时，我确实发现了这一点

Answer 3

您还可以使用＆＃39;适配器＆＃39;

在其他许多内容中抽象此事件

例如我的一个项目......

    #region Copyright
    /*
    This file came from Managed Media Aggregation, You can always find the latest version @ https://net7mma.codeplex.com/      
 */
#endregion

namespace Media.Sockets
{
    #region NetworkConnection

    /// <summary>
    /// Represents a <see cref="Connection"/> specific to the Network.
    /// </summary>
    public class NetworkConnection : Connection, Common.ISocketReference
    {
        #region NetworkConnectionState

        [System.Flags]
        protected enum NetworkConnectionState : long
        {
            None = 0,
            Initialized = 1,
            Bound = 2,
            Connected = 4,
        }

        #endregion

        #region Fields

        /// <summary>
        /// Created in <see cref="CreateWaitHandle"/>, Disposed in <see cref="Dispose"/>.
        /// </summary>
        Common.Extensions.WaitHandle.DisposableWaitHandle WaitHandle;

        /// <summary>
        /// The date and time when the Connection was started.
        /// </summary>
        protected System.DateTime LasRemoteConnectionStartedDateTime;

        /// <summary>
        /// The date and time when the Connection was started.
        /// </summary>
        protected System.DateTime LastRemoteConnectionCompletedDateTime;

        #endregion

        #region Properties

        /// <summary>
        /// Gets the amount of time taken to connect to the <see cref="RemoteEndPoint"/>
        /// </summary>
        public System.TimeSpan RemoteConnectionTime { get { return LastRemoteConnectionCompletedDateTime - LasRemoteConnectionStartedDateTime; } }

        /// <summary>
        /// The <see cref="System.Net.NetworkInformation.NetworkInterface"/> assoicated with the NetworkConnection.
        /// </summary>
        public System.Net.NetworkInformation.NetworkInterface NetworkInterface { get; protected set; }

        /// <summary>
        /// The <see cref="System.Net.Sockets.Socket"/> assoicated with the NetworkConnection.
        /// </summary>
        public System.Net.Sockets.Socket ConnectionSocket { get; protected set; }

        /// <summary>
        /// Indicates if the NetworkConnection has a <see cref="NetworkInterface"/> which is not null.
        /// </summary>
        public bool HasNetworkInterface { get { return NetworkInterface != null; } }

        /// <summary>
        /// The <see cref="System.Net.EndPoint"/> from which this NetworkConnection connects to the <see cref="RemoteEndPoint"/>
        /// </summary>
        public System.Net.EndPoint LocalEndPoint { get; protected set; }

        /// <summary>
        /// Indicates if this NetworkConnection has a <see cref="LocalEndPoint"/> which is not null.
        /// </summary>
        public bool HasLocalEndPoint { get { return LocalEndPoint != null; } }

        /// <summary>
        /// The <see cref="System.Net.EndPoint"/> from which this NetworkConnection is connected to via the <see cref="LocalEndPoint"/>
        /// </summary>
        public System.Net.EndPoint RemoteEndPoint { get; protected set; }

        /// <summary>
        /// Indicates if this NetworkConnection has a <see cref="RemoteEndPoint"/> which is not null.
        /// </summary>
        public bool HasRemoteEndPoint { get { return RemoteEndPoint != null; } }

        /// <summary>
        /// Indicates the <see cref="NetworkConnectionState"/> assoicated with this NetworkConnection
        /// </summary>
        protected NetworkConnectionState NetworkConnectionFlags
        {
            get { return (NetworkConnectionState)Flags; }
            set { Flags = (long)value; }
        }

        #endregion

        #region Constructor

        public NetworkConnection()
            : base() { }

        public NetworkConnection(string name, bool shouldDispose)
            : base(name, shouldDispose) { }

        public NetworkConnection(System.Net.Sockets.Socket existingSocket, bool ownsHandle, bool shouldDispose)
            : this("System.Net.Socket-" + ownsHandle.ToString(), shouldDispose)
        {
            if (existingSocket == null) throw new System.ArgumentNullException("existingSocket");

            //Assign the ConnectionSocket
            ConnectionSocket = existingSocket;

            //Flag Initialized.
            FlagInitialized();

            //Assign the NetworkInterface
            NetworkInterface = Common.Extensions.NetworkInterface.NetworkInterfaceExtensions.GetNetworkInterface(ConnectionSocket);

            //Create a WaitHandle 
            CreateWaitHandle(ConnectionSocket.Handle, ownsHandle);

            //Check IsBound
            if (ConnectionSocket.IsBound)
            {
                //Flag Bound.
                FlagBound();

                //Serialize and Assign LocalEndPoint
                LocalEndPoint = existingSocket.LocalEndPoint;
            }

            //Check Connected
            if (ConnectionSocket.Connected)
            {
                //Sample the clock
                LasRemoteConnectionStartedDateTime = System.DateTime.UtcNow;

                //Serialize and Assign RemoteEndPoint
                RemoteEndPoint = existingSocket.RemoteEndPoint;

                //Call Connect to FlagConnected and call base logic.
                Connect();

                //Sample the clock
                LastRemoteConnectionCompletedDateTime = System.DateTime.UtcNow;
            }
        }

        #endregion

        #region NetworkChange Event Handlers

        void NetworkChange_NetworkAvailabilityChanged(object sender, System.Net.NetworkInformation.NetworkAvailabilityEventArgs e)
        {
            Refresh();
        }

        void NetworkChange_NetworkAddressChanged(object sender, System.EventArgs e)
        {
            Refresh();
        }

        #endregion

        #region Bound

        protected void FlagBound()
        {
            //Indicate Bound
            Flags |= (long)NetworkConnectionState.Bound;
        }

        protected void UnFlagBound()
        {
            //Indicate not Bound
            Flags &= (long)NetworkConnectionState.Bound;
        }

        #endregion

        #region Initialize

        protected void FlagInitialized()
        {
            //Indicate Connected
            Flags |= (long)NetworkConnectionState.Initialized;
        }

        protected void UnFlagInitialized()
        {
            //Indicate Not Connected
            Flags &= (long)NetworkConnectionState.Initialized;
        }

        public virtual void Initialize(bool registerForEvents)
        {
            //Check not already Initialized.
            if (false == NetworkConnectionFlags.HasFlag(NetworkConnectionState.Initialized))
            {
                //Indicate Initialized
                FlagInitialized();

                if (registerForEvents)
                {
                    //Attach events
                    System.Net.NetworkInformation.NetworkChange.NetworkAddressChanged += NetworkChange_NetworkAddressChanged;

                    System.Net.NetworkInformation.NetworkChange.NetworkAvailabilityChanged += NetworkChange_NetworkAvailabilityChanged;
                }
            }
        }

        #endregion

        #region Refresh

        public override void Refresh()
        {
            base.Refresh();
        }

        #endregion

        #region CreateConnectionSocket

        public void CreateConnectionSocket(System.Net.Sockets.AddressFamily addressFamily, System.Net.Sockets.SocketType socketType, System.Net.Sockets.ProtocolType protocolType)
        {
            if (ConnectionSocket == null)
            {
                ConnectionSocket = new System.Net.Sockets.Socket(addressFamily, socketType, protocolType);

                CreateWaitHandle(ConnectionSocket.Handle, true);
            }
        }

        #endregion

        #region CreateWaitHandle

        public void CreateWaitHandle(System.IntPtr handle, bool ownsHandle)
        {
            if (WaitHandle == null)
            {
                WaitHandle = new Common.Extensions.WaitHandle.DisposableWaitHandle(handle, ownsHandle);
            }
        }

        #endregion

        #region Connect

        protected void FlagConnected()
        {
            //Indicate Connected
            Flags |= (long)NetworkConnectionState.Connected;
        }

        protected void UnFlagConnected()
        {
            //Indicate Not Connected
            Flags &= (long)NetworkConnectionState.Connected;
        }

        public override void Connect()
        {
            //Check not already Connected.
            if (false == NetworkConnectionFlags.HasFlag(NetworkConnectionState.Connected))
            {
                //Check IsEstablished
                if (IsEstablished) return;

                if (NetworkInterface == null) throw new System.InvalidOperationException("NetworkInterface must be assigned before calling Connect.");

                if (LocalEndPoint == null) throw new System.InvalidOperationException("LocalEndPoint must be assigned before calling Connect.");

                if (RemoteEndPoint == null) throw new System.InvalidOperationException("RemoteEndPoint must be assigned before calling Connect.");

                //Set established
                base.Connect();

                //Indicate Connected
                FlagConnected();

                //Refresh the connection
                Refresh();
            }
        }

        /// <summary>
        /// Creates the <see cref="CreateConnectionSocket"/> using the specified options and connects the socket.
        /// Assigns <see cref="LocalEndPoint"/> and <see cref="RemoteEndPoint"/>
        /// </summary>
        /// <param name="addressFamily"></param>
        /// <param name="socketType"></param>
        /// <param name="protocolType"></param>
        /// <param name="addressList"></param>
        /// <param name="port"></param>
        public virtual void Connect(System.Net.Sockets.AddressFamily addressFamily, System.Net.Sockets.SocketType socketType, System.Net.Sockets.ProtocolType protocolType, System.Net.IPAddress[] addressList, int port)
        {
            try
            {
                //Create the socket
                CreateConnectionSocket(addressFamily, socketType, protocolType);

                //Sample the clock
                LasRemoteConnectionStartedDateTime = System.DateTime.UtcNow;

                //Connect the socket
                ConnectionSocket.Connect(addressList, port);

                //Sample the clock
                LastRemoteConnectionCompletedDateTime = System.DateTime.UtcNow;
            }
            finally
            {
                //Assign the NetworkInterface
                NetworkInterface = Common.Extensions.NetworkInterface.NetworkInterfaceExtensions.GetNetworkInterface(ConnectionSocket);

                //Assign the LocalEndPoint
                LocalEndPoint = (System.Net.IPEndPoint)ConnectionSocket.LocalEndPoint;

                //Assign the RemoteEndPoint
                RemoteEndPoint = (System.Net.IPEndPoint)ConnectionSocket.RemoteEndPoint;

                //Call Connect to FlagConnected and call base logic.
                Connect();
            }
        }

        #endregion

        #region Disconnect

        public virtual void Disconnect(bool allowReuse = false)
        {
            //Check not already Connected.
            if (((NetworkConnectionState)Flags).HasFlag(NetworkConnectionState.Connected))
            {
                ConnectionSocket.Disconnect(allowReuse);

                base.Disconnect();

                UnFlagConnected();

                Refresh();
            }
        }

        public override void Disconnect()
        {
            Disconnect(false);
        }

        #endregion

        #region Dispose

        protected override void Dispose(bool disposing)
        {
            base.Dispose(disposing);

            using (WaitHandle)
            {
                System.Net.NetworkInformation.NetworkChange.NetworkAddressChanged -= NetworkChange_NetworkAddressChanged;

                System.Net.NetworkInformation.NetworkChange.NetworkAvailabilityChanged -= NetworkChange_NetworkAvailabilityChanged;

                ConnectionSocket = null;

                LocalEndPoint = RemoteEndPoint = null;

                NetworkInterface = null;
            }
        }

        #endregion

        System.Collections.Generic.IEnumerable<System.Net.Sockets.Socket> Common.ISocketReference.GetReferencedSockets()
        {
            yield return ConnectionSocket;
        }
    }

    #endregion
}

如果您需要＆＃39;连接＆＃39;基类，你可以参考这个

#region Copyright
/*
This file came from Managed Media Aggregation, You can always find the latest version @ https://net7mma.codeplex.com/

 Julius.Friedman@gmail.com / (SR. Software Engineer ASTI Transportation Inc. http://www.asti-trans.com)   
 * v//
 */
#endregion


namespace Media.Sockets
{
    #region Connection

    /// <summary>
    /// Provides a base class to facilitate the concept of a Connection.
    /// </summary>
    public abstract class Connection : Common.BaseDisposable
    {
        #region Statics

        /// <summary>
        /// A string with the format of:
        ///     `TypeName Id Flags Name`
        /// </summary>
        const string FormatString = "{0} {1} ({2}) {3}";

        #endregion

        #region Properties

        /// <summary>
        /// The unique identifier assoicated with this instance.
        /// </summary>
        public readonly System.Guid Id = System.Guid.NewGuid();

        /// <summary>
        /// The date and time the instance was created.
        /// </summary>
        public readonly System.DateTime Created = System.DateTime.UtcNow;

        /// <summary>
        /// The name assigned to this instance.
        /// </summary>
        public readonly string Name;

        /// <summary>
        /// Indicates if <see cref="Disconnect"/> will be called when disposing.
        /// </summary>
        public bool IsPersistent
        {
            get
            {
                return ShouldDispose == false;
            }
            set
            {
                ShouldDispose = value == false;
            }
        }

        /// <summary>
        /// Provided for derived implementations
        /// </summary>
        protected long Flags { get; set; }

        /// <summary>
        /// Indicates if the Connection is established.
        /// </summary>
        public virtual bool IsEstablished { get; protected set; }

        /// <summary>
        /// The date and time the Connection was established.
        /// </summary>
        public System.DateTime EstablishedDateTime { get; protected set; }

        /// <summary>
        /// The amount of time the connection has been established.
        /// </summary>
        public System.TimeSpan TimeEstablished { get { return IsEstablished ? System.DateTime.UtcNow - EstablishedDateTime : System.TimeSpan.Zero; } }

        #endregion

        #region Connect

        /// <summary>
        /// If <see cref="IsDisposed"/> is false, Sets <see cref="IsEstablished"/> to true.
        /// </summary>
        public virtual void Connect()
        {
            if (IsDisposed) return;

            EstablishedDateTime = System.DateTime.UtcNow;

            IsEstablished = true;
        }

        #endregion

        #region Disconnect

        /// <summary>
        /// If <see cref="IsDisposed"/> is false, Sets <see cref="IsEstablished"/> to false.
        /// </summary>
        public virtual void Disconnect()
        {
            if (IsDisposed) return;

            IsEstablished = false;
        }

        #endregion

        #region Refresh

        /// <summary>
        /// Refreshes the details of the Connection.
        /// Throws a <see cref="System.ObjectDisposedException"/> if <see cref="IsDisposed"/> is true.
        /// </summary>
        public virtual void Refresh()
        {
            CheckDisposed();
        }

        #endregion

        #region Dispose

        /// <summary>
        /// If <see cref="IsDisposed"/> is True the call returns immediately.
        /// Calls <see cref="Disconnect"/> if <see cref="IsPersistent"/> is False and calls <see cref="Common.BaseDisposable.Dispose"/>
        /// </summary>
        public override void Dispose()
        {
            if (IsDisposed) return;

            if (false == IsPersistent) Disconnect();

            base.Dispose();
        }

        #endregion

        #region Constructor

        public Connection(string name, bool shouldDispose)
            : base(shouldDispose)
        {
            Name = name;
        }

        public Connection()
            : this(string.Empty, true) { }

        #endregion

        #region ToString

        public override string ToString()
        {
            return string.Format(FormatString, GetType().Name.ToString(), Id.ToString(), Flags, Name);
        }

        #endregion

    }

    #endregion
}

Answer 4

您可以参考此代码，以获取实现其他类的IPNetworkConnection示例。

#region Copyright
/*
This file came from Managed Media Aggregation, You can always find the latest version @ https://net7mma.codeplex.com/      
 * v//
 */
#endregion

namespace Media.Sockets
{
#region IPNetworkConnection

/// <summary>
/// Represents a <see cref="NetworkConnection"/> which utilizes the IP Protocol.
/// </summary>
public class IPNetworkConnection : NetworkConnection
{
    #region Statics

    public static System.Net.NetworkInformation.IPGlobalProperties IPGlobalProperties
    {
        get { return System.Net.NetworkInformation.IPGlobalProperties.GetIPGlobalProperties(); }
    }

    #region CreateIPHostEntry

    public static System.Net.IPHostEntry CreateIPHostEntry(System.Net.IPAddress address, string hostName, params string[] aliases)
    {
        return CreateIPHostEntry(Common.Extensions.Object.ObjectExtensions.ToArray<System.Net.IPAddress>(address),
            hostName,
            aliases);
    }

    public static System.Net.IPHostEntry CreateIPHostEntry(string hostName, params System.Net.IPAddress[] address)
    {
        return CreateIPHostEntry(address, hostName, null);
    }

    public static System.Net.IPHostEntry CreateIPHostEntry(System.Net.IPAddress[] addresses, string hostName, params string[] aliases)
    {
        return new System.Net.IPHostEntry()
        {
            AddressList = Common.Extensions.Array.ArrayExtensions.IsNullOrEmpty(addresses) ? Common.Extensions.Object.ObjectExtensions.ToArray<System.Net.IPAddress>(System.Net.IPAddress.None) : addresses,
            Aliases = Common.Extensions.Array.ArrayExtensions.IsNullOrEmpty(aliases) ? Common.Extensions.Object.ObjectExtensions.ToArray<string>(string.Empty) : aliases,
            HostName = hostName ?? string.Empty
        };
    }

    #endregion

    #endregion

    #region Properties

    /// <summary>
    /// Gets the <see cref="System.Net.NetworkInformation.IPInterfaceProperties"/> assoicated with the <see cref="NetworkInterface"/>
    /// </summary>
    public System.Net.NetworkInformation.IPInterfaceProperties IPInterfaceProperties
    {
        get { return HasNetworkInterface ? NetworkInterface.GetIPProperties() : null; }
    }

    /// <summary>
    /// Indicates if the <see cref="RemoteIPEndPoint"/> has a <see cref="System.Net.NetworkInformation.NetworkInterface"/> on this computer.
    /// </summary>
    public bool IsLocalConnection { get { return HasRemoteIPEndPoint && Common.Extensions.NetworkInterface.NetworkInterfaceExtensions.GetNetworkInterface(RemoteIPEndPoint) != null; } }

    /// <summary>
    /// Indicates if the <see cref="RemoteIPEndPoint"/> is from within the same network as this computer.
    /// </summary>
    public bool IsIntranetConnection
    {
        get { return false == IsLocalConnection && Common.Extensions.IPAddress.IPAddressExtensions.IsOnIntranet(RemoteIPEndPoint.Address); }
    }

    #region Local        

    /// <summary>
    /// The <see cref="System.Net.IPHostEntry"/> assoicated with the <see cref="LocalIPEndPoint"/>
    /// </summary>
    public System.Net.IPHostEntry LocalIPHostEntry { get; protected set; }

    /// <summary>
    /// Indicates if the <see cref="LocalIPHostEntry"/> is not null.
    /// </summary>
    public bool HasLocalIPHostEntry { get { return LocalIPHostEntry != null; } }

    /// <summary>
    /// Gets or sets the <see cref="LocalEndPoint"/>.
    /// 
    /// If the <see cref="LocalEndPoint"/> is not a <see cref="System.Net.IPEndPoint"/> a <see cref="System.InvalidOperationException"/> will be thrown.
    /// </summary>
    public System.Net.IPEndPoint LocalIPEndPoint
    {
        get { return (System.Net.IPEndPoint)LocalEndPoint; }
        set
        {
            if (false == LocalEndPoint is System.Net.IPEndPoint) throw new System.InvalidOperationException("LocalEndPoint is not a System.Net.IPEndPoint");

            LocalEndPoint = value;
        }
    }

    /// <summary>
    /// Indicates if the <see cref="LocalIPEndPoint"/> is not null.
    /// </summary>
    public bool HasLocalIPEndPoint { get { return LocalIPEndPoint != null; } }

    #endregion

    #region Dhcp

    /// <summary>
    /// Gets the <see cref="System.Net.NetworkInformation.IPAddressCollection"/> assoicated with the <see cref="IPInterfaceProperties"/>
    /// </summary>
    public virtual System.Net.NetworkInformation.IPAddressCollection DhcpServerAddresses
    {
        get
        {
            return IPInterfaceProperties.DhcpServerAddresses;
        }
    }

    /// <summary>
    /// Indicates if the IPNetworkConnection utilized Dhcp
    /// </summary>
    public bool UsesDhcp
    {
        get
        {
            return DhcpServerAddresses.Count > 0; /* && DhcpLeaseLifetime != System.TimeSpan.MinValue;*/
        }
    }

    //Could make a Superset class of to unify paths..
    //System.Net.NetworkInformation.IPAddressInformationCollection ipAddressCollection;

    /// <summary>
    /// If <see cref="UsesDhcp"/> the amount of time of the IPAddress is leased according the <see cref="System.Net.NetworkInformation.IPAddressInformation"/> assoicated with the <see cref="LocalIPEndPoint"/>.
    /// 
    /// If the <see cref="LocalIPEndPoint"/> is not found in the leased <see cref="System.Net.NetworkInformation.IPAddressInformation"/> then <see cref="Common.Extensions.TimeSpan.TimeSpanExtensions.InfiniteTimeSpan"/> is returned.
    /// </summary>
    public System.TimeSpan DhcpLeaseLifetime
    {
        get
        {
            //If there is no Dhcp server the DhcpLeaveLifeTime is 0
            if (false == UsesDhcp) return System.TimeSpan.Zero;

            //Check Multicast if the address IsMulticast
            if (Common.Extensions.IPAddress.IPAddressExtensions.IsMulticast(LocalIPEndPoint.Address))
            {
                System.Net.NetworkInformation.MulticastIPAddressInformationCollection multicastIPAddressInformationCollection = IPInterfaceProperties.MulticastAddresses;

                foreach (System.Net.NetworkInformation.MulticastIPAddressInformation multicastIPAddressInformation in multicastIPAddressInformationCollection)
                {
                    if (multicastIPAddressInformation.Address.Equals(LocalIPEndPoint.Address))
                    {
                        return System.TimeSpan.FromSeconds(multicastIPAddressInformation.DhcpLeaseLifetime);
                    }
                }
            }
            else //Check Unicast otherwise
            {
                System.Net.NetworkInformation.UnicastIPAddressInformationCollection unicastIPAddressInformationCollection = IPInterfaceProperties.UnicastAddresses;

                foreach (System.Net.NetworkInformation.UnicastIPAddressInformation unicastIPAddressInformation in unicastIPAddressInformationCollection)
                {
                    if (unicastIPAddressInformation.Address.Equals(LocalIPEndPoint.Address))
                    {
                        return System.TimeSpan.FromSeconds(unicastIPAddressInformation.DhcpLeaseLifetime);
                    }
                }
            }

            //Could not find a an IPAddress which matched the LocalIPEndPoint, indicate infinite timeout.
            return Common.Extensions.TimeSpan.TimeSpanExtensions.InfiniteTimeSpan;
        }
    }

    /// <summary>
    /// If <see cref="UsesDhcp"/> Gets the number of seconds remaining during which this address is valid.
    /// 
    /// If the <see cref="LocalIPEndPoint"/> is not found in the leased <see cref="System.Net.NetworkInformation.IPAddressInformation"/> then <see cref="Common.Extensions.TimeSpan.TimeSpanExtensions.InfiniteTimeSpan"/> is returned.
    /// </summary>
    public System.TimeSpan DhcpAddressValidLifetime
    {
        get
        {
            //If there is no Dhcp server the DhcpLeaveLifeTime is 0
            if (false == UsesDhcp) return System.TimeSpan.Zero;

            //Check Multicast if the address IsMulticast
            if (Common.Extensions.IPAddress.IPAddressExtensions.IsMulticast(LocalIPEndPoint.Address))
            {
                System.Net.NetworkInformation.MulticastIPAddressInformationCollection multicastIPAddressInformationCollection = IPInterfaceProperties.MulticastAddresses;

                foreach (System.Net.NetworkInformation.MulticastIPAddressInformation multicastIPAddressInformation in multicastIPAddressInformationCollection)
                {
                    if (multicastIPAddressInformation.Address.Equals(LocalIPEndPoint.Address))
                    {
                        return System.TimeSpan.FromSeconds(multicastIPAddressInformation.AddressValidLifetime);
                    }
                }
            }
            else //Check Unicast otherwise
            {
                System.Net.NetworkInformation.UnicastIPAddressInformationCollection unicastIPAddressInformationCollection = IPInterfaceProperties.UnicastAddresses;

                foreach (System.Net.NetworkInformation.UnicastIPAddressInformation unicastIPAddressInformation in unicastIPAddressInformationCollection)
                {
                    if (unicastIPAddressInformation.Address.Equals(LocalIPEndPoint.Address))
                    {
                        return System.TimeSpan.FromSeconds(unicastIPAddressInformation.AddressValidLifetime);
                    }
                }
            }

            //Could not find a an IPAddress which matched the LocalIPEndPoint, indicate infinite timeout.
            return Common.Extensions.TimeSpan.TimeSpanExtensions.InfiniteTimeSpan;
        }
    }

    /// <summary>
    /// If <see cref="UsesDhcp"/> Gets the number of seconds remaining during which this address is the preferred address.
    /// 
    /// If the <see cref="LocalIPEndPoint"/> is not found in the leased <see cref="System.Net.NetworkInformation.IPAddressInformation"/> then <see cref="Common.Extensions.TimeSpan.TimeSpanExtensions.InfiniteTimeSpan"/> is returned.
    /// </summary>
    public System.TimeSpan DhcpAddressPreferredLifetime
    {
        get
        {
            //If there is no Dhcp server the DhcpLeaveLifeTime is 0
            if (false == UsesDhcp) return System.TimeSpan.Zero;

            //Check Multicast if the address IsMulticast
            if (Common.Extensions.IPAddress.IPAddressExtensions.IsMulticast(LocalIPEndPoint.Address))
            {
                System.Net.NetworkInformation.MulticastIPAddressInformationCollection multicastIPAddressInformationCollection = IPInterfaceProperties.MulticastAddresses;

                foreach (System.Net.NetworkInformation.MulticastIPAddressInformation multicastIPAddressInformation in multicastIPAddressInformationCollection)
                {
                    if (multicastIPAddressInformation.Address.Equals(LocalIPEndPoint.Address))
                    {
                        return System.TimeSpan.FromSeconds(multicastIPAddressInformation.AddressPreferredLifetime);
                    }
                }
            }
            else //Check Unicast otherwise
            {
                System.Net.NetworkInformation.UnicastIPAddressInformationCollection unicastIPAddressInformationCollection = IPInterfaceProperties.UnicastAddresses;

                foreach (System.Net.NetworkInformation.UnicastIPAddressInformation unicastIPAddressInformation in unicastIPAddressInformationCollection)
                {
                    if (unicastIPAddressInformation.Address.Equals(LocalIPEndPoint.Address))
                    {
                        return System.TimeSpan.FromSeconds(unicastIPAddressInformation.AddressPreferredLifetime);
                    }
                }
            }

            //Could not find a an IPAddress which matched the LocalIPEndPoint, indicate infinite timeout.
            return Common.Extensions.TimeSpan.TimeSpanExtensions.InfiniteTimeSpan;
        }
    }

    #endregion

    #region Remote

    /// <summary>
    /// Provides information about the <see cref="RemoteEndPoint"/>.Address
    /// </summary>
    public System.Net.NetworkInformation.IPAddressInformation RemoteAddressInformation { get; protected set; }

    /// <summary>
    /// Indicates if the <see cref="RemoteAddressInformation"/> is not null.
    /// </summary>
    public bool HasRemoteAddressInformation { get { return RemoteAddressInformation != null; } }

    /// <summary>
    /// The <see cref="System.Net.IPHostEntry"/> assoicated with the <see cref="RemoteIPEndPoint"/>
    /// </summary>
    public System.Net.IPHostEntry RemoteIPHostEntry { get; protected set; }

    /// <summary>
    /// Indicates if the <see cref="RemoteIPHostEntry"/> is not null.
    /// </summary>
    public bool HasRemoteIPHostEntry { get { return RemoteIPHostEntry != null; } }

    /// <summary>
    /// Gets or sets the <see cref="RemoteEndPoint"/>.
    /// 
    /// If the <see cref="RemoteEndPoint"/> is not a <see cref="System.Net.IPEndPoint"/> a <see cref="System.InvalidOperationException"/> will be thrown.
    /// </summary>
    public System.Net.IPEndPoint RemoteIPEndPoint
    {
        get { return (System.Net.IPEndPoint)RemoteEndPoint; }
        set
        {
            if (false == RemoteEndPoint is System.Net.IPEndPoint) throw new System.InvalidOperationException("RemoteEndPoint is not a System.Net.IPEndPoint");

            RemoteEndPoint = value;
        }
    }

    /// <summary>
    /// Indicates if the <see cref="RemoteEndPoint"/> is a <see cref="System.Net.IPEndPoint"/>
    /// </summary>
    public bool HasRemoteIPEndPoint { get { return RemoteIPEndPoint != null; } }

    #endregion

    #endregion

    #region Constructor

    /// <summary>
    /// Creates a new NetworkConnection with the given.
    /// </summary>
    /// <param name="remoteIPHostEntry">given</param>
    public IPNetworkConnection(System.Net.IPHostEntry remoteIPHostEntry)
        : base()
    {
        if (remoteIPHostEntry == null) throw new System.ArgumentNullException("remoteIPHostEntry");

        RemoteIPHostEntry = remoteIPHostEntry;            
    }

    /// <summary>
    /// Creates a new NetworkConnection by resolving the given using <see cref="System.Net.Dns.GetHostEntry"/>
    /// </summary>
    /// <param name="hostNameOrAddress">given</param>
    public IPNetworkConnection(string hostNameOrAddress) :
        this(System.Net.Dns.GetHostEntry(hostNameOrAddress))
    {
        RemoteAddressInformation = new IPAddressInformation(System.Net.IPAddress.None, true, false);
    }

    /// <summary>
    /// Creates a new NetworkConnection and <see cref="new System.Net.IPHostEntry"/> using the given address.
    /// </summary>
    /// <param name="address">The address</param>
    public IPNetworkConnection(System.Net.IPAddress address) :
        this(CreateIPHostEntry(string.Empty, address))
    {
        RemoteAddressInformation = new IPAddressInformation(System.Net.IPAddress.None, false, false);
    }

    public IPNetworkConnection(System.Uri uri) : this(uri.DnsSafeHost) { }

    #endregion

    #region Refresh

    /// <summary>
    /// If <see cref="HasNetworkInterface"/> is True And <see cref="HasLocalIPEndPoint"/> then <see cref="NetworkInterface"/> is updated using <see cref="Common.Extensions.NetworkInterface.NetworkInterfaceExtensions.GetNetworkInterface"/>
    /// </summary>
    public void RefreshNetworkInterface()
    {
        if (HasNetworkInterface && HasLocalIPEndPoint)
        {                
            NetworkInterface = Common.Extensions.NetworkInterface.NetworkInterfaceExtensions.GetNetworkInterface(LocalIPEndPoint);
        }
    }

    /// <summary>
    /// If <see cref="HasRemoteAddressInformation"/> is True And <see cref="RemoteAddressInformation.IsDnsEligible"/> then the <see cref="RemoteIPHostEntry"/> is updated using <see cref="System.Net.Dns.GetHostEntry"/>
    /// </summary>
    public void RefreshRemoteIPHostEntry()
    {
        if (HasRemoteAddressInformation && RemoteAddressInformation.IsDnsEligible)
        {
            RemoteIPHostEntry = System.Net.Dns.GetHostEntry(RemoteIPEndPoint.Address);
        }
    }

    public override void Refresh()
    {
        if (IsDisposed) return;

        base.Refresh();

        RefreshNetworkInterface();

        RefreshRemoteIPHostEntry();
    }

    #endregion

    #region Connect

    public void Connect(int addressIndex, System.Net.NetworkInformation.NetworkInterface networkInterface, int port = 0)
    {
        if (ConnectionSocket == null) throw new System.InvalidOperationException("There must be a ConnectionSocket assigned before calling Connect.");

        if (addressIndex < 0) throw new System.IndexOutOfRangeException("addressIndex must be > 0 and < HostEntry.AddressList.Length");

        if (networkInterface == null) throw new System.ArgumentNullException("networkInterface");

        NetworkInterface = networkInterface;

        RemoteEndPoint = new System.Net.IPEndPoint(RemoteIPHostEntry.AddressList[addressIndex], port);

        Connect();

        LocalEndPoint = ConnectionSocket.LocalEndPoint;

        RemoteAddressInformation = new IPAddressInformation(RemoteIPEndPoint.Address, RemoteAddressInformation.IsDnsEligible, RemoteAddressInformation.IsTransient);
    }

    #endregion

    #region Dispose

    public override void Dispose()
    {
        base.Dispose();

        RemoteIPHostEntry = null;

        LocalEndPoint = RemoteEndPoint = null;

        NetworkInterface = null;
    }

    #endregion
}

#endregion
}

Answer 5

这只是众多可能实现中的一种，还应概述如何创建“转换器”以及随后的“TranslatedConnection”。显然（或不是这样）可以在基类内以及在接口内概述发送和接收方法，以便在需要时允许跨网络通信。

“连接”类为任何类型的连接定义了合适的基础。 “NetworkConnection”增加了对网络的要求，最后是“IPNetworkConnection”来实现IP协议所需的逻辑。这也可以扩展到'TcpNetworkConnection'然后扩展到'TcpIpNetworkConnection'或者以'SerialConnection'或'EthernetConnection'所需的任何其他方式扩展，然后构建一个类以允许跨媒体通信，例如除其他外，“SerialToEthernetNetworkConnection”。

例如：

 #region Copyright
/*
This file came from Managed Media Aggregation, You can always find the latest version @ https://net7mma.codeplex.com/

 Julius.Friedman@gmail.com / (SR. Software Engineer ASTI Transportation Inc. http://www.asti-trans.com)

Permission is hereby granted, free of charge, 
 * to any person obtaining a copy of this software and associated documentation files (the "Software"), 
 * to deal in the Software without restriction, 
 * including without limitation the rights to :
 * use, 
 * copy, 
 * modify, 
 * merge, 
 * publish, 
 * distribute, 
 * sublicense, 
 * and/or sell copies of the Software, 
 * and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
 * 
 * 
 * JuliusFriedman@gmail.com should be contacted for further details.

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. 
 * 
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, 
 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, 
 * TORT OR OTHERWISE, 
 * ARISING FROM, 
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 * 
 * v//
 */
#endregion

namespace Media.Sockets
{
    #region TcpNetworkConnection

    public class TcpNetworkConnection : NetworkConnection
    {
        #region Statics

        public static System.Net.NetworkInformation.TcpConnectionInformation[] TcpConnectionInformation
        {
            get { return IPNetworkConnection.IPGlobalProperties.GetActiveTcpConnections(); }
        }

        #endregion

        public TcpNetworkConnection(string name, bool shouldDispose) : base(name, shouldDispose) { }
    }

    #endregion
}

#region Copyright
/*
This file came from Managed Media Aggregation, You can always find the latest version @ https://net7mma.codeplex.com/

 Julius.Friedman@gmail.com / (SR. Software Engineer ASTI Transportation Inc. http://www.asti-trans.com)

Permission is hereby granted, free of charge, 
 * to any person obtaining a copy of this software and associated documentation files (the "Software"), 
 * to deal in the Software without restriction, 
 * including without limitation the rights to :
 * use, 
 * copy, 
 * modify, 
 * merge, 
 * publish, 
 * distribute, 
 * sublicense, 
 * and/or sell copies of the Software, 
 * and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
 * 
 * 
 * JuliusFriedman@gmail.com should be contacted for further details.

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. 
 * 
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, 
 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, 
 * TORT OR OTHERWISE, 
 * ARISING FROM, 
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 * 
 * v//
 */
#endregion

namespace Media.Sockets
{
    #region TcpNetworkConnection

    public class TcpIPNetworkConnection : IPNetworkConnection
    {
        #region Statics

        public static System.Net.NetworkInformation.TcpConnectionInformation[] TcpConnectionInformation
        {
            get { return IPNetworkConnection.IPGlobalProperties.GetActiveTcpConnections(); }
        }

        #endregion

        public TcpIPNetworkConnection() : base(string.Empty) { }
    }

    #endregion
}

这两个都是有效的实现，但用途不同。

插座可以在关闭时发送信号吗？

5 个答案: