| title | author | date | CreateTime | categories |
|---|---|---|---|---|
| C# dotnet core 局域网组播方法 | lindexi | 2019-10-30 9:0:48 +0800 | 2019-10-29 12:2:46 +0800 | dotnet C# |
我在微软官网找到了用 C# 做 UDP 组播的方法，我优化一些逻辑，保留核心代码，然后加了一点封装
在使用之前需要注意的是组播可以用来做局域网传输，但是组播不是可靠的方案，随时可能因为路由器等发送失败或无法接收消息
使用组播的方法是创建 Socket 通过 UDP 向组播地址发送数据或从组播地址接收数据
可以作为组播的地址是 239.0.0.0～239.255.255.255 的范围，这个范围是局域网可用。但实际可用或不可用还需要靠实际的路由器
首先创建一个 Socket 然后绑定到端口
private IPAddress LocalIpAddress { set; get; } = IPAddress.Any; private Socket MulticastSocket { get; } private const int MulticastPort = 15003; private void TryBindSocket()
{
for (var i = MulticastPort; i < 65530; i++)
{
try
{
EndPoint localEndPoint = new IPEndPoint(LocalIpAddress, i); MulticastSocket.Bind(localEndPoint);
return;
}
catch (SocketException e)
{
Console.WriteLine(e);
}
}
}
绑定的端口是用来接收的端口，所以绑定失败不会影响发送
绑定完成需要加入组播网络
var multicastOption = new MulticastOption(MulticastAddress, IPAddress.Any); MulticastSocket.SetSocketOption(SocketOptionLevel.IP,
SocketOptionName.AddMembership,
multicastOption); /// <summary>
/// 组播地址
/// <para/>
/// 224.0.0.0～224.0.0.255为预留的组播地址（永久组地址），地址224.0.0.0保留不做分配，其它地址供路由协议使用；
/// <para/>
/// 224.0.1.0～224.0.1.255是公用组播地址，可以用于Internet；
/// <para/>
/// 224.0.2.0～238.255.255.255为用户可用的组播地址（临时组地址），全网范围内有效；
/// <para/>
/// 239.0.0.0～239.255.255.255为本地管理组播地址，仅在特定的本地范围内有效。
/// </summary>
public IPAddress MulticastAddress { set; get; }
需要注意，上面代码的 LocalIpAddress 写的是 Any 也就是只有在默认的网卡是和其他设备网段才能访问
如果发现其他设备不能接收到信息，那么请修改 LocalIpAddress 为你设备的地址
接收方法和接收其他相同
private void ReceiveBroadcastMessages()
{
// 接收需要绑定 MulticastPort 端口
var bytes = new byte[MaxByteLength];
EndPoint remoteEndPoint = new IPEndPoint(IPAddress.Any, 0); try
{
while (true)
{
var length = MulticastSocket.ReceiveFrom(bytes, ref remoteEndPoint); Console.WriteLine(Encoding.UTF8.GetString(bytes, 0, length));
}
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}
接收和发送都是二进制
/// <summary>
/// 发送组播
/// </summary>
/// <param name="message"></param>
public void SendBroadcastMessage(string message)
{
try
{
var endPoint = new IPEndPoint(MulticastAddress, MulticastPort);
var byteList = Encoding.UTF8.GetBytes(message); MulticastSocket.SendTo(byteList, endPoint);
}
catch (Exception e)
{
Console.WriteLine("\n" + e);
}
}
所有代码
internal class PeerMulticastFinder : IDisposable
{
/// <inheritdoc />
public PeerMulticastFinder()
{
MulticastSocket = new Socket(AddressFamily.InterNetwork,
SocketType.Dgram,
ProtocolType.Udp);
MulticastAddress = IPAddress.Parse("230.138.100.2");
} /// <summary>
/// 寻找局域网设备
/// </summary>
public void FindPeer()
{
// 实际是反过来，让其他设备询问 StartMulticast(); var ipList = GetLocalIpList().ToList();
var message = string.Join(';',ipList);
SendBroadcastMessage(message);
// 先发送再获取消息，这样就不会收到自己发送的消息
ReceivedMessage += (s, e) => { Console.WriteLine($"找到 {e}"); };
} /// <summary>
/// 获取本地 IP 地址
/// </summary>
/// <returns></returns>
private IEnumerable<IPAddress> GetLocalIpList()
{
var host = Dns.GetHostEntry(Dns.GetHostName());
foreach (var ip in host.AddressList)
{
if (ip.AddressFamily == AddressFamily.InterNetwork)
{
yield return ip;
}
}
} /// <summary>
/// 组播地址
/// <para/>
/// 224.0.0.0～224.0.0.255为预留的组播地址（永久组地址），地址224.0.0.0保留不做分配，其它地址供路由协议使用；
/// <para/>
/// 224.0.1.0～224.0.1.255是公用组播地址，可以用于Internet；
/// <para/>
/// 224.0.2.0～238.255.255.255为用户可用的组播地址（临时组地址），全网范围内有效；
/// <para/>
/// 239.0.0.0～239.255.255.255为本地管理组播地址，仅在特定的本地范围内有效。
/// </summary>
public IPAddress MulticastAddress { set; get; } private const int MulticastPort = 15003; /// <summary>
/// 启动组播
/// </summary>
public void StartMulticast()
{
try
{
// 如果首次绑定失败，那么将无法接收，但是可以发送
TryBindSocket(); // Define a MulticastOption object specifying the multicast group
// address and the local IPAddress.
// The multicast group address is the same as the address used by the server.
// 有多个 IP 时，指定本机的 IP 地址，此时可以接收到具体的内容
var multicastOption = new MulticastOption(MulticastAddress, IPAddress.Parse("172.18.134.16")); MulticastSocket.SetSocketOption(SocketOptionLevel.IP,
SocketOptionName.AddMembership,
multicastOption);
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
} Task.Run(ReceiveBroadcastMessages);
} /// <summary>
/// 收到消息
/// </summary>
public event EventHandler<string> ReceivedMessage; private void ReceiveBroadcastMessages()
{
// 接收需要绑定 MulticastPort 端口
var bytes = new byte[MaxByteLength];
EndPoint remoteEndPoint = new IPEndPoint(IPAddress.Any, 0); try
{
while (!_disposedValue)
{
var length = MulticastSocket.ReceiveFrom(bytes, ref remoteEndPoint); OnReceivedMessage(Encoding.UTF8.GetString(bytes, 0, length));
}
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
} /// <summary>
/// 发送组播
/// </summary>
/// <param name="message"></param>
public void SendBroadcastMessage(string message)
{
try
{
var endPoint = new IPEndPoint(MulticastAddress, MulticastPort);
var byteList = Encoding.UTF8.GetBytes(message); if (byteList.Length > MaxByteLength)
{
throw new ArgumentException($"传入 message 转换为 byte 数组长度太长，不能超过{MaxByteLength}字节")
{
Data =
{
{ "message", message },
{ "byteList", byteList }
}
};
} MulticastSocket.SendTo(byteList, endPoint);
}
catch (Exception e)
{
Console.WriteLine("\n" + e);
}
} private IPAddress LocalIpAddress { set; get; } = IPAddress.Any; private Socket MulticastSocket { get; } private void TryBindSocket()
{
for (var i = MulticastPort; i < 65530; i++)
{
try
{
EndPoint localEndPoint = new IPEndPoint(LocalIpAddress, i); MulticastSocket.Bind(localEndPoint);
return;
}
catch (SocketException e)
{
Console.WriteLine(e);
}
}
} private const int MaxByteLength = 1024; #region IDisposable Support private bool _disposedValue = false; // 要检测冗余调用 private void Dispose(bool disposing)
{
if (!_disposedValue)
{
if (disposing)
{
} MulticastSocket.Dispose(); ReceivedMessage = null;
MulticastAddress = null; _disposedValue = true;
}
} // 添加此代码以正确实现可处置模式。
public void Dispose()
{
// 请勿更改此代码。将清理代码放入以上 Dispose(bool disposing) 中。
Dispose(true);
GC.SuppressFinalize(this);
} #endregion private void OnReceivedMessage(string e)
{
ReceivedMessage?.Invoke(this, e);
}
}
