从UDP套接字接收并发回数据

我正在尝试编写一个接受请求的控制台应用程序（大小为18个字节），然后将一些东西（大小为7个字节）发送回客户端。 我为我的生活似乎无法让这个工作。 我可以很好地接收数据，但我发回的数据永远不会到达客户端。

这是我的代码

static void Main(string[] args) { // Data to return byte[] ret = { 0xfe, 0xfd, 0x09, 0x00, 0x00, 0x00, 0x00 }; // tell the user that we are waiting Console.WriteLine("Waiting for UDP Connection..."); // Create a new socket to listen from Socket Skt = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp); Skt.EnableBroadcast = true; Skt.Bind(new IPEndPoint(IPAddress.Loopback, 27900)); try { // Blocks until a message returns on this socket from a remote host. Byte[] receiveBytes = new byte[48]; IPEndPoint sender = new IPEndPoint(IPAddress.Any, 0); EndPoint senderRemote = (EndPoint)sender; Skt.ReceiveFrom(receiveBytes, ref senderRemote); string returnData = Encoding.UTF8.GetString(receiveBytes).Trim(); Console.WriteLine("This is the message you received " + returnData.ToString()); // Sent return data int sent = Skt.SendTo(ret, senderRemote); Console.WriteLine("Sent {0} bytes back", sent); Skt.Close(); } catch (Exception e) { Console.WriteLine(e.ToString()); } Console.ReadLine(); } 

有人给我一些指示吗？

Answer 1

如果没有看到您的客户端代码，很难确定问题可能在哪里。 我可以使用网络库 networkcomms.net为您提供有效的解决方案。 服务器的代码如下：

 using System; using System.Collections.Generic; using System.Linq; using System.Text; using NetworkCommsDotNet; namespace UPDServer { class Program { static void Main(string[] args) { NetworkComms.AppendGlobalIncomingPacketHandler("Message", (packetHeader, connection, incomingString) => { Console.WriteLine("This is the message you received " + incomingString); connection.SendObject("Message", incomingString + " relayed by server."); }); UDPConnection.StartListening(true); Console.WriteLine("Server ready. Press any key to shutdown server."); Console.ReadKey(true); NetworkComms.Shutdown(); } } } 

对于客户：

 using System; using System.Collections.Generic; using System.Linq; using System.Text; using NetworkCommsDotNet; namespace UDPClient { class Program { static void Main(string[] args) { string messageToSend = "This is a message To Send"; string messageFromServer = UDPConnection.GetConnection(new ConnectionInfo("127.0.0.1", 10000), UDPOptions.None).SendReceiveObject("Message", "Message", 2000, messageToSend); Console.WriteLine("Server said '{0}'.", messageFromServer); Console.WriteLine("Press any key to exit."); Console.ReadKey(true); NetworkComms.Shutdown(); } } } 

您显然需要从网站下载NetworkCommsDotNet DLL，以便您可以在“使用NetworkCommsDotNet”参考中添加它。 另请参阅客户端示例中的服务器IP地址当前为“127.0.0.1”，如果您在同一台计算机上同时运行服务器和客户端，这应该可以工作。 有关更多信息，请查看入门或如何创建客户端服务器应用程序文章。

Answer 2

以下是我修改过的示例代码，您可以看到可以从此示例接收和发送。 方法测试充当客户端，可以是一个不同的过程，现在我已经在不同的线程中进行模拟。

 using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Net.Sockets; using System.Net; using System.Threading; namespace ConsoleApplication1 { class Program { static void Main(string[] args) { // Data to return byte[] ret = { 0xfe, 0xfd, 0x09, 0x00, 0x00, 0x00, 0x00 }; // tell the user that we are waiting Console.WriteLine("Waiting for UDP Connection..."); // Create a new socket to listen from Socket Skt = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp); Skt.EnableBroadcast = true; Skt.Bind(new IPEndPoint(IPAddress.Loopback, 27900)); try { // Blocks until a message returns on this socket from a remote host. Byte[] receiveBytes = new byte[48]; IPEndPoint sender = new IPEndPoint(IPAddress.Any, 0); EndPoint senderRemote = (EndPoint)sender; Thread thr = new Thread(new ThreadStart(Test)); thr.Start(); Skt.ReceiveFrom(receiveBytes, ref senderRemote); string returnData = Encoding.UTF8.GetString(receiveBytes).Trim(); Console.WriteLine("This is the message you received " + returnData.ToString()); // Sent return data int sent = Skt.SendTo(ret, senderRemote); Console.WriteLine("Sent {0} bytes back", sent); Skt.Close(); } catch (Exception e) { Console.WriteLine(e.ToString()); } Console.ReadLine(); } public static void Test() { byte[] ret = { 0xfe, 0xfd, 0x09, 0x00, 0x00, 0x00, 0x00 }; Socket Skt = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp); Skt.EnableBroadcast = true; IPEndPoint test=new IPEndPoint(IPAddress.Loopback, 27900); int sent = Skt.SendTo(ret, test); try { // Blocks until a message returns on this socket from a remote host. Byte[] receiveBytes = new byte[48]; IPEndPoint sender = new IPEndPoint(IPAddress.Any, 0); EndPoint senderRemote = (EndPoint)sender; Skt.ReceiveFrom(receiveBytes, ref senderRemote); string returnData = Encoding.UTF8.GetString(receiveBytes).Trim(); Console.WriteLine("This is the message you received " + returnData.ToString()); // Sent return data //int sent = Skt.SendTo(ret, senderRemote); Console.WriteLine("Sent {0} bytes back", sent); Skt.Close(); } catch (Exception ex) { } } } }