/*
 * 实现一个 ASM 信道（即 ASM 帮助类），供外部调用
 * 
 * 
 * 通过 UdpAnySourceMulticastClient 实现 ASM（Any Source Multicast），即“任意源多播”
 * 多播组基于 IGMP（Internet Group Management Protocol），即“Internet组管理协议”
 * 
 * UdpAnySourceMulticastClient - 一个发送信息到多播组并从任意源接收多播信息的客户端，即 ASM 客户端
 *     BeginJoinGroup(), EndJoinGroup() - 加入多播组的异步方法
 *     BeginReceiveFromGroup(), EndReceiveFromGroup() - 从多播组接收信息的异步方法（可以理解为接收多播组内所有成员发送的信息）
 *     BeginSendToGroup(), EndSendToGroup() - 发送信息到多播组的异步方法（可以理解为发送信息到多播组内的全部成员）
 *     ReceiveBufferSize - 接收信息的缓冲区大小
 *     SendBufferSize - 发送信息的缓冲区大小
 *     
 *     BeginSendTo(), EndSendTo() - 发送信息到指定目标的异步方法
 *     BlockSource() - 阻止指定源，以便不再接收该源发来的信息
 *     UnblockSource() - 取消阻止指定源
 *     MulticastLoopback - 发出的信息是否需要传给自己
 * 
 */

using System;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Ink;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;

using System.Text;
using System.Net.Sockets;

namespace Demo.Communication.SocketClient
{
    public class UdpAnySourceMulticastChannel : IDisposable
    {
        // ASM 客户端
        private UdpAnySourceMulticastClient _client;

        // 接收信息的缓冲区
        private byte[] _buffer;
        // 此客户端是否加入了多播组
        private bool _isJoined;

        /// <summary>
        /// 构造函数
        /// </summary>
        /// <param name="groupAddress">多播组地址</param>
        /// <param name="port">多播组的端口</param>
        /// <param name="maxMessageSize">接收信息的缓冲区大小</param>
        /// <remarks>
        /// 注：udp 报文（Datagram）的最大长度为 65535（包括报文头）
        /// </remarks>
        public UdpAnySourceMulticastChannel(IPAddress groupAddress, int port, int maxMessageSize)
        {
            _buffer = new byte[maxMessageSize];
            // 实例化 ASM 客户端，需要指定的参数为：多播组地址；多播组的端口
            _client = new UdpAnySourceMulticastClient(groupAddress, port);
        }

        // 收到多播信息后触发的事件
        public event EventHandler<UdpPacketEventArgs> Received;
        private void OnReceived(IPEndPoint source, byte[] data)
        {
            var handler = Received;
            if (handler != null)
                handler(this, new UdpPacketEventArgs(data, source));
        }

        // 加入多播组后触发的事件
        public event EventHandler Opening;
        private void OnOpening()
        {
            var handler = Opening;
            if (handler != null)
                handler(this, EventArgs.Empty);
        }

        // 断开多播组后触发的事件
        public event EventHandler Closing;
        private void OnClosing()
        {
            var handler = Closing;
            if (handler != null)
                handler(this, EventArgs.Empty);
        }

        /// <summary>
        /// 加入多播组
        /// </summary>
        public void Open()
        {
            if (!_isJoined)
            {
                _client.BeginJoinGroup(
                    result =>
                    {
                        _client.EndJoinGroup(result);
                        _isJoined = true;
                        Deployment.Current.Dispatcher.BeginInvoke(
                            () =>
                            {
                                OnOpening();
                                Receive();
                            });
                    }, null);
            }
        }

        /// <summary>
        /// 发送信息到多播组，即发送信息到多播组内的所有成员
        /// </summary>
        public void Send(string msg)
        {
            if (_isJoined)
            {
                byte[] data = Encoding.UTF8.GetBytes(msg);

                _client.BeginSendToGroup(data, 0, data.Length,
                    result =>
                    {
                        _client.EndSendToGroup(result);
                    }, null);
            }
        }

        /// <summary>
        /// 从多播组接收信息，即接收多播组内所有成员发送的信息
        /// </summary>
        private void Receive()
        {
            if (_isJoined)
            {
                Array.Clear(_buffer, 0, _buffer.Length);

                _client.BeginReceiveFromGroup(_buffer, 0, _buffer.Length,
                    result =>
                    {
                        IPEndPoint source;
                        _client.EndReceiveFromGroup(result, out source);
                        Deployment.Current.Dispatcher.BeginInvoke(
                            () =>
                            {
                                OnReceived(source, _buffer);
                                Receive();
                            });
                    }, null);
            }
        }

        // 关闭 ASM 信道
        public void Close()
        {
            _isJoined = false;
            OnClosing();
            Dispose();
        }

        public void Dispose()
        {
            if (_client != null)
                _client.Dispose();
        }
    }
}

<phone:PhoneApplicationPage 
    x:Class="Demo.Communication.SocketClient.AnySourceMulticast"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:phone="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone"
    xmlns:shell="clr-namespace:Microsoft.Phone.Shell;assembly=Microsoft.Phone"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    FontFamily="{StaticResource PhoneFontFamilyNormal}"
    FontSize="{StaticResource PhoneFontSizeNormal}"
    Foreground="{StaticResource PhoneForegroundBrush}"
    SupportedOrientations="Portrait" Orientation="Portrait"
    mc:Ignorable="d" d:DesignHeight="768" d:DesignWidth="480"
    shell:SystemTray.IsVisible="True">

    <Grid x:Name="LayoutRoot" Background="Transparent">
        <StackPanel HorizontalAlignment="Left">

            <ListBox Name="lstAllMsg" MaxHeight="400" />
            <TextBox x:Name="txtName" />
            <TextBox x:Name="txtInput" KeyDown="txtInput_KeyDown" />
            <Button x:Name="btnSend" Content="发送" Click="btnSend_Click" />

        </StackPanel>        
    </Grid>

</phone:PhoneApplicationPage>

/*
 * 用于演示 ASM
 */

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;
using Microsoft.Phone.Controls;

using System.Windows.Navigation;

namespace Demo.Communication.SocketClient
{
    public partial class AnySourceMulticast : PhoneApplicationPage
    {
        // 实例化自定义的 ASM 信道
        private UdpAnySourceMulticastChannel _channel;

        public AnySourceMulticast()
        {
            InitializeComponent();
        }

        protected override void OnNavigatedTo(NavigationEventArgs e)
        {
            txtName.Text = "匿名" + new Random().Next(1000, 9999).ToString();

            // 多播组地址是必须介于 224.0.0.0 到 239.255.255.255 之间的 IP 地址，其中范围介于 224.0.0.0 到 224.0.0.255 之间的多播地址是保留多播地址
            // 比如：224.0.0.0 是基址，224.0.0.1 是代表同一个物理网络中所有系统的多播组地址，而 224.0.0.2 代表同一个物理网络中的所有路由器
            _channel = new UdpAnySourceMulticastChannel(IPAddress.Parse("224.0.1.1"), 3368, 2048); 
            _channel.Opening += new EventHandler(_channel_Opening);
            _channel.Received += new EventHandler<UdpPacketEventArgs>(_channel_Received);
            _channel.Closing += new EventHandler(_channel_Closing);

            _channel.Open();

            // 需要的使用，应该调用 Close()
            // _channel.Close();
        }

        void _channel_Opening(object sender, EventArgs e)
        {
            _channel.Send(string.Format("{0}: 进来了 - [{1}]", txtName.Text, DateTime.Now.ToString("HH:mm:ss")));
        }

        void _channel_Received(object sender, UdpPacketEventArgs e)
        {
            // 因为已经指定了接收信息的缓冲区大小是 2048 ，所以如果信息不够 2048 个字节的的话，空白处均为空字节“\0”
            string message = string.Format("{0} - 来自：{1}", e.Message.TrimEnd(‘\0‘), e.Source.ToString()); 
            lstAllMsg.Items.Insert(0, message); 
        }

        void _channel_Closing(object sender, EventArgs e)
        {
            _channel.Send(string.Format("{0}: 离开了 - [{1}]", txtName.Text, DateTime.Now.ToString("HH:mm:ss")));
        }

        private void btnSend_Click(object sender, RoutedEventArgs e)
        {
            SendMsg();
        }

        private void txtInput_KeyDown(object sender, KeyEventArgs e)
        {
            if (e.Key == Key.Enter)
            {
                SendMsg();
                this.Focus();
            }
        }

        private void SendMsg()
        {
            _channel.Send(string.Format("{0}: {1} - [{2}]", txtName.Text, txtInput.Text, DateTime.Now.ToString("HH:mm:ss")));
            txtInput.Text = "";
        }
    }
}