C＃套接字数据报溢出
我是新来的c＃=）
我有一个关于udp socket的问题。 我有一个聊天服务器，接收数据包到特定的结构（udp数据报）。
为什么程序在套接字缓冲区已满时接收数据？ 所有后来的事情都不应该丢失吗？ 也许数据包碎片发生？
数据包结构：udp_headers（28字节）| dataIdentifier（4字节）|名称长度（4字节）|消息长度（4字节）|名称（名称长度）|消息（消息长度）
当我发送比内部缓冲区大的数据包时。 该程序引发异常：
ReceiveData错误：在数据报套接字上发送的消息大于内部消息缓冲区或其他网络限制，或者用于接收数据报的缓冲区小于数据报本身
我需要的只是在导致此错误之前丢弃这些数据包。 可能吗？
服务器代码：
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Net.Sockets;
using System.Net;
using System.Collections;
using ChatApplication;
namespace ChatServer
{
public partial class Server : Form
{
#region Private Members
// Structure to store the client information
private struct Client
{
public EndPoint endPoint;
public string name;
}
// Listing of clients
private ArrayList clientList;
// Server socket
private Socket serverSocket;
// Data stream
private byte[] dataStream = new byte[1024];
// Status delegate
private delegate void UpdateStatusDelegate(string status);
private UpdateStatusDelegate updateStatusDelegate = null;
#endregion
#region Constructor
public Server()
{
InitializeComponent();
}
#endregion
#region Events
private void Server_Load(object sender, EventArgs e)
{
try
{
// Initialise the ArrayList of connected clients
this.clientList = new ArrayList();
// Initialise the delegate which updates the status
this.updateStatusDelegate = new UpdateStatusDelegate(this.UpdateStatus);
// Initialise the socket
serverSocket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
// Initialise the IPEndPoint for the server and listen on port 30000
IPEndPoint server = new IPEndPoint(IPAddress.Any, 30000);
// Associate the socket with this IP address and port
serverSocket.Bind(server);
// Initialise the IPEndPoint for the clients
IPEndPoint clients = new IPEndPoint(IPAddress.Any, 0);
// Initialise the EndPoint for the clients
EndPoint epSender = (EndPoint)clients;
// Start listening for incoming data
serverSocket.BeginReceiveFrom(this.dataStream, 0, 1024, SocketFlags.None, ref epSender, new AsyncCallback(ReceiveData), epSender);
lblStatus.Text = "Listening";
}
catch (Exception ex)
{
lblStatus.Text = "Error";
MessageBox.Show("Load Error: " + ex.Message, "UDP Server", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
}
private void btnExit_Click(object sender, EventArgs e)
{
Close();
}
#endregion
#region Send And Receive
public void SendData(IAsyncResult asyncResult)
{
try
{
serverSocket.EndSend(asyncResult);
}
catch (Exception ex)
{
MessageBox.Show("SendData Error: " + ex.Message, "UDP Server", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
}
private void ReceiveData(IAsyncResult asyncResult)
{
try
{
byte[] data;
// Initialise a packet object to store the received data
Packet receivedData = new Packet(this.dataStream);
// Initialise a packet object to store the data to be sent
Packet sendData = new Packet();
// Initialise the IPEndPoint for the clients
IPEndPoint clients = new IPEndPoint(IPAddress.Any, 0);
// Initialise the EndPoint for the clients
EndPoint epSender = (EndPoint)clients;
// Receive all data
serverSocket.EndReceiveFrom(asyncResult, ref epSender);
// Start populating the packet to be sent
sendData.ChatDataIdentifier = receivedData.ChatDataIdentifier;
sendData.ChatName = receivedData.ChatName;
switch (receivedData.ChatDataIdentifier)
{
case DataIdentifier.Message:
sendData.ChatMessage = string.Format("{0}: {1}", receivedData.ChatName, receivedData.ChatMessage);
break;
case DataIdentifier.LogIn:
// Populate client object
Client client = new Client();
client.endPoint = epSender;
client.name = receivedData.ChatName;
// Add client to list
this.clientList.Add(client);
sendData.ChatMessage = string.Format("-- {0} is online --", receivedData.ChatName);
break;
case DataIdentifier.LogOut:
// Remove current client from list
foreach (Client c in this.clientList)
{
if (c.endPoint.Equals(epSender))
{
this.clientList.Remove(c);
break;
}
}
sendData.ChatMessage = string.Format("-- {0} has gone offline --", receivedData.ChatName);
break;
}
// Get packet as byte array
data = sendData.GetDataStream();
foreach (Client client in this.clientList)
{
if (client.endPoint != epSender || sendData.ChatDataIdentifier != DataIdentifier.LogIn)
{
// Broadcast to all logged on users
serverSocket.BeginSendTo(data, 0, data.Length, SocketFlags.None, client.endPoint, new AsyncCallback(this.SendData), client.endPoint);
}
}
// Listen for more connections again...
serverSocket.BeginReceiveFrom(this.dataStream, 0, 1024, SocketFlags.None, ref epSender, new AsyncCallback(this.ReceiveData), epSender);
// Update status through a delegate
this.Invoke(this.updateStatusDelegate, new object[] { sendData.ChatMessage });
}
catch (Exception ex)
{
MessageBox.Show("ReceiveData Error: " + ex.Message, "UDP Server", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
}
#endregion
#region Other Methods
private void UpdateStatus(string status)
{
rtxtStatus.Text += status + Environment.NewLine;
}
#endregion
}
}
这是udp发件人和收件人之一。 使用/ s，如果你想听
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net;
using System.Net.Sockets;
using System.Threading;
namespace UDPTestClient
{
class Program
{
static void RecvCompleted(object sender, SocketAsyncEventArgs e)
{
string Data = Encoding.ASCII.GetString(e.Buffer, e.Offset, e.BytesTransferred);
e.Dispose();
ReceiveUdp((Socket)e.UserToken);
Console.WriteLine(Data);
}
static void SendCompleted(object sender, SocketAsyncEventArgs e)
{
int i = e.Count;
e.Dispose();
Console.WriteLine("{0} bytes send", i);
}
static void ReceiveUdp(Socket s)
{
SocketAsyncEventArgs e = new SocketAsyncEventArgs();
//set buffer to 100 .Now it's work fine.
e.SetBuffer(new byte[100], 0, 100);
e.RemoteEndPoint = new IPEndPoint(IPAddress.Any, 0);
e.UserToken = s;
e.Completed += new EventHandler<SocketAsyncEventArgs>(RecvCompleted);
s.ReceiveFromAsync(e);
}
static void SendUdp(Socket s, string Data)
{
SocketAsyncEventArgs e = new SocketAsyncEventArgs();
byte[] buf = Encoding.ASCII.GetBytes(Data);
e.SetBuffer(buf, 0, buf.Length);
e.RemoteEndPoint = new IPEndPoint(IPAddress.Parse("127.0.0.1"), 3333);
e.UserToken = s;
e.Completed += new EventHandler<SocketAsyncEventArgs>(SendCompleted);
s.SendToAsync(e);
}
static void Main(string[] args)
{
Socket s = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
if (args.Length != 0 && args[0] == "/s")
{
IPEndPoint ip = new IPEndPoint(IPAddress.Any, 3333);
s.Bind(ip);
ReceiveUdp(s);
}
else
{
SendUdp(s, "Hello!");
}
Console.ReadKey();
s.Close();
}
}
}
UDP是一个哑巴协议，因为它实际上没有任何大小的知识或如何处理这个问题。 如果您想在发生异常之前处理此问题，则需要为您的通信创建不同的结构。 我会建议您执行以下操作之一：