NetworkAddressChange.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / fx / src / Net / System / Net / NetworkInformation / NetworkAddressChange.cs / 1 / NetworkAddressChange.cs
                        

                        
                             
namespace System.Net.NetworkInformation {

    using System.Net;
    using System.Net.NetworkInformation; 
    using System.Net.Sockets;
    using System.Collections; 
    using System.Collections.Specialized; 
    using System.ComponentModel;
    using System.Threading; 
    using System.Runtime.InteropServices;

    [Flags]
    internal enum StartIPOptions {Both = 3, None = 0, StartIPv4 = 1, StartIPv6 = 2} 

    public class NetworkAvailabilityEventArgs:EventArgs{ 
        bool isAvailable; 

        internal NetworkAvailabilityEventArgs(bool isAvailable){ 
            this.isAvailable = isAvailable;
        }

        public bool IsAvailable{ 
            get{
                return isAvailable; 
            } 
        }
    } 


    public sealed class NetworkChange{
 

        private NetworkChange(){} 
 

        static public event NetworkAvailabilityChangedEventHandler NetworkAvailabilityChanged{ 
            add{
                if (! ComNetOS.IsWin2K)
                     throw new PlatformNotSupportedException(SR.GetString(SR.Win2000Required));
 
                AvailabilityChangeListener.Start(value);
            } 
            remove{ 
                AvailabilityChangeListener.Stop(value);
            } 

        }

 
        static public event NetworkAddressChangedEventHandler NetworkAddressChanged{
            add{ 
                if (! ComNetOS.IsWin2K) 
                     throw new PlatformNotSupportedException(SR.GetString(SR.Win2000Required));
 
                AddressChangeListener.Start(value);
            }
            remove{
                AddressChangeListener.Stop(value); 
            }
 
        } 

 

        static internal bool CanListenForNetworkChanges {
            get{
                if (! ComNetOS.IsWin2K ) 
                   return false;
                return true; 
            } 
        }
 
        /* Consider removing
        static internal void UnsafeListenForNetworkChanges(NetworkAddressChangedEventHandler handler)
        {
            if (!CanListenForNetworkChanges) 
            {
                throw new PlatformNotSupportedException(SR.GetString(SR.Win2000Required)); 
            } 
            AddressChangeListener.UnsafeStart(handler);
        } 
        */


        internal static class AvailabilityChangeListener{ 

            static object syncObject = new object(); 
            static private ListDictionary s_availabilityCallerArray = null; 
            static NetworkAddressChangedEventHandler addressChange = null;
            static bool isAvailable = false; 
            private static ContextCallback s_RunHandlerCallback = new ContextCallback(RunHandlerCallback);


            private static void RunHandlerCallback(object state) 
            {
                ((NetworkAvailabilityChangedEventHandler) state)(null, new NetworkAvailabilityEventArgs(isAvailable)); 
            } 

 
            private static void ChangedAddress(object sender, EventArgs eventArgs) {

                lock(syncObject){
                    bool isAvailableNow = SystemNetworkInterface.InternalGetIsNetworkAvailable(); 

                    if (isAvailableNow != isAvailable) { 
                        isAvailable = isAvailableNow; 

                        DictionaryEntry[] callerArray = new DictionaryEntry[s_availabilityCallerArray.Count]; 
                        s_availabilityCallerArray.CopyTo(callerArray, 0);

                        for (int i = 0; i < callerArray.Length; i++)
                        { 
                            NetworkAvailabilityChangedEventHandler handler = (NetworkAvailabilityChangedEventHandler) callerArray[i].Key;
                            ExecutionContext context = (ExecutionContext) callerArray[i].Value; 
                            if (context == null) 
                            {
                                handler(null, new NetworkAvailabilityEventArgs(isAvailable)); 
                            }
                            else
                            {
                                ExecutionContext.Run(context.CreateCopy(), s_RunHandlerCallback, handler); 
                            }
                        } 
                    } 
                }
            } 



            internal static void Start(NetworkAvailabilityChangedEventHandler caller){ 
                lock(syncObject){
                    if (s_availabilityCallerArray == null) { 
                        s_availabilityCallerArray = new ListDictionary(); 
                        addressChange = new NetworkAddressChangedEventHandler(ChangedAddress);
                    } 

                    if (s_availabilityCallerArray.Count == 0) {
                        isAvailable = NetworkInterface.GetIsNetworkAvailable();
                        AddressChangeListener.UnsafeStart(addressChange); 
                    }
 
                    if ((caller != null) && (!s_availabilityCallerArray.Contains(caller))) { 
                        s_availabilityCallerArray.Add(caller, ExecutionContext.Capture());
                    } 
                }
            }

 
            internal static void Stop(NetworkAvailabilityChangedEventHandler caller)
            { 
               lock(syncObject){ 
                    s_availabilityCallerArray.Remove(caller);
                    if(s_availabilityCallerArray.Count == 0){ 
                        AddressChangeListener.Stop(addressChange);
                    }
                }
            } 
        }
 
 
        //helper class for detecting address change events.
        internal unsafe static class AddressChangeListener{ 

            static private ListDictionary s_callerArray = new ListDictionary();
            static private ContextCallback s_runHandlerCallback = new ContextCallback(RunHandlerCallback);
            static private RegisteredWaitHandle s_registeredWait; 

            //need to keep the reference so it isn't GC'd before the native call executes 
            static private bool s_isListening = false; 
            static private bool s_isPending = false;
            static private SafeCloseSocketAndEvent s_ipv4Socket = null; 
            static private SafeCloseSocketAndEvent s_ipv6Socket = null;
            static private WaitHandle s_ipv4WaitHandle = null;
            static private WaitHandle s_ipv6WaitHandle = null;
 
            //callback fired when an address change occurs
            private static void AddressChangedCallback(object stateObject, bool signaled) { 
                lock (s_callerArray) { 

                    //the listener was cancelled, which would only happen if we aren't listening 
                    //for more events.
                    s_isPending = false;

                    if (!s_isListening) { 
                        return;
                    } 
 
                    s_isListening = false;
 
                    // Need to copy the array so the callback can call start and stop
                    DictionaryEntry[] callerArray = new DictionaryEntry[s_callerArray.Count];
                    s_callerArray.CopyTo(callerArray, 0);
 
                    //wait for the next address change
                    StartHelper(null,false,(StartIPOptions)stateObject); 
 
                    for (int i = 0; i < callerArray.Length; i++)
                    { 
                        NetworkAddressChangedEventHandler handler = (NetworkAddressChangedEventHandler) callerArray[i].Key;
                        ExecutionContext context = (ExecutionContext) callerArray[i].Value;
                        if (context == null)
                        { 
                            handler(null, EventArgs.Empty);
                        } 
                        else 
                        {
                            ExecutionContext.Run(context.CreateCopy(), s_runHandlerCallback, handler); 
                        }
                    }
                }
            } 

            private static void RunHandlerCallback(object state) 
            { 
                ((NetworkAddressChangedEventHandler) state)(null, EventArgs.Empty);
            } 


            //start listening
            internal static void Start(NetworkAddressChangedEventHandler caller) 
            {
                StartHelper(caller, true, StartIPOptions.Both); 
            } 

            internal static void UnsafeStart(NetworkAddressChangedEventHandler caller) 
            {
                StartHelper(caller, false, StartIPOptions.Both);
            }
 
            private static void StartHelper(NetworkAddressChangedEventHandler caller, bool captureContext, StartIPOptions startIPOptions)
            { 
                lock (s_callerArray) { 
                    // setup changedEvent and native overlapped struct.
                    if(s_ipv4Socket == null){ 
                        Socket.InitializeSockets();

                        int blocking;
 
                        if(Socket.SupportsIPv4){
                            blocking = -1; 
                            s_ipv4Socket = SafeCloseSocketAndEvent.CreateWSASocketWithEvent(AddressFamily.InterNetwork, SocketType.Dgram, (ProtocolType)0, true, false); 
                            UnsafeNclNativeMethods.OSSOCK.ioctlsocket(s_ipv4Socket, IoctlSocketConstants.FIONBIO,ref blocking);
                            s_ipv4WaitHandle = s_ipv4Socket.GetEventHandle(); 
                        }

                        if(Socket.OSSupportsIPv6){
                            blocking = -1; 
                            s_ipv6Socket = SafeCloseSocketAndEvent.CreateWSASocketWithEvent(AddressFamily.InterNetworkV6, SocketType.Dgram, (ProtocolType)0, true, false);
                            UnsafeNclNativeMethods.OSSOCK.ioctlsocket(s_ipv6Socket,IoctlSocketConstants.FIONBIO,ref blocking); 
                            s_ipv6WaitHandle = s_ipv6Socket.GetEventHandle(); 
                        }
                    } 

                    if ((caller != null) && (!s_callerArray.Contains(caller))) {
                        s_callerArray.Add(caller, captureContext ? ExecutionContext.Capture() : null);
                    } 

                    //if s_listener is not null, it means we are already actively listening 
                    if (s_isListening || s_callerArray.Count == 0) { 
                        return;
                    } 

                    if(!s_isPending){

                        int length; 
                        SocketError errorCode;
 
                        if(Socket.SupportsIPv4 && (startIPOptions & StartIPOptions.StartIPv4) !=0){ 
                            s_registeredWait = ThreadPool.UnsafeRegisterWaitForSingleObject(
                                s_ipv4WaitHandle, 
                                new WaitOrTimerCallback(AddressChangedCallback),
                                StartIPOptions.StartIPv4,
                                -1,
                                true ); 

                            errorCode = (SocketError) UnsafeNclNativeMethods.OSSOCK.WSAIoctl_Blocking( 
                                s_ipv4Socket.DangerousGetHandle(), 
                                (int) IOControlCode.AddressListChange,
                                null, 0, null, 0, 
                                out length,
                                IntPtr.Zero, IntPtr.Zero);

                            if (errorCode != SocketError.Success) { 
                                NetworkInformationException exception = new NetworkInformationException();
                                if (exception.ErrorCode != (uint)SocketError.WouldBlock) { 
                                    throw exception; 
                                }
                            } 

                            errorCode = (SocketError)UnsafeNclNativeMethods.OSSOCK.WSAEventSelect(s_ipv4Socket, s_ipv4Socket.GetEventHandle().SafeWaitHandle, AsyncEventBits.FdAddressListChange);
                            if (errorCode != SocketError.Success) {
                               throw new NetworkInformationException(); 
                            }
                        } 
 
                        if(Socket.OSSupportsIPv6 && (startIPOptions & StartIPOptions.StartIPv6) !=0){
                            s_registeredWait = ThreadPool.UnsafeRegisterWaitForSingleObject( 
                                s_ipv6WaitHandle,
                                new WaitOrTimerCallback(AddressChangedCallback),
                                StartIPOptions.StartIPv6,
                                -1, 
                                true );
 
                            errorCode = (SocketError) UnsafeNclNativeMethods.OSSOCK.WSAIoctl_Blocking( 
                                s_ipv6Socket.DangerousGetHandle(),
                                (int) IOControlCode.AddressListChange, 
                                null, 0, null, 0,
                                out length,
                                IntPtr.Zero, IntPtr.Zero);
 
                            if (errorCode != SocketError.Success) {
                                NetworkInformationException exception = new NetworkInformationException(); 
                                if (exception.ErrorCode != (uint)SocketError.WouldBlock) { 
                                    throw exception;
                                } 
                            }

                            errorCode = (SocketError)UnsafeNclNativeMethods.OSSOCK.WSAEventSelect(s_ipv6Socket, s_ipv6Socket.GetEventHandle().SafeWaitHandle, AsyncEventBits.FdAddressListChange);
                            if (errorCode != SocketError.Success) { 
                               throw new NetworkInformationException();
                            } 
                        } 
                    }
 
                    s_isListening = true;
                    s_isPending = true;
                }
            } 

 
 
            //stop listening
            internal static void Stop(object caller) 
            {
                lock(s_callerArray){
                    s_callerArray.Remove(caller);
                    if (s_callerArray.Count == 0 && s_isListening) { 
                        s_isListening = false;
                    } 
                } 
            } //ends ignoreaddresschanges
        } 
    }

    public delegate void NetworkAddressChangedEventHandler(object sender, EventArgs e);
    public delegate void NetworkAvailabilityChangedEventHandler(object sender, NetworkAvailabilityEventArgs e); 
}

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