UDP協議不能接收到任何數據

Question

這裏是我的代碼

Socket sck = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp); 
sck.Bind(new IPEndPoint(IPAddress.Any, 0)); 

// Broadcast to find server 
string msg = "Imlookingforaserver:" + udp_listen_port; 
byte[] sendBytes4 = Encoding.ASCII.GetBytes(msg); 
IPEndPoint groupEP = new IPEndPoint(IPAddress.Parse("255.255.255.255"), server_port); 
sck.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.Broadcast, 1); 
sck.SendTo(sendBytes4, groupEP); 

//Wait response from server 
Socket sck2 = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp); 
sck2.Bind(new IPEndPoint(IPAddress.Any, udp_listen_port)); 
byte[] buffer = new byte[128]; 
EndPoint remoteEndPoint = new IPEndPoint(IPAddress.Any, udp_listen_port); 
sck2.ReceiveFrom(buffer, ref remoteEndPoint); //<<< I never pass this line 

我用上面的代碼，試圖找到一個服務器。首先，我廣播一條消息，然後等待服務器的響應。

我用C++編寫的服務器進行測試，運行在Windows Vista中，客戶端用C＃編寫，並且運行在與服務器相同的機器上。

問題是：服務器可以接收客戶端廣播的消息，但客戶端無法從服務器接收任何東西。

我嘗試用C++編寫客戶端，它的功能就像一個魅力，我認爲我的問題是在C＃客戶端。

Answer 1

我會在廣播之前開始在該端口上收聽。您使用的是無連接的UDP，因此您可能會丟失數據包。

Socket sck = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp); 
sck.Bind(new IPEndPoint(IPAddress.Any, 0)); 
//Wait response from server 
Socket sck2 = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp); 
sck2.Bind(new IPEndPoint(IPAddress.Any, udp_listen_port)); 
byte[] buffer = new byte[128]; 
EndPoint remoteEndPoint = new IPEndPoint(IPAddress.Any, udp_listen_port); 

// Broadcast to find server 
string msg = "Imlookingforaserver:" + udp_listen_port; 
byte[] sendBytes4 = Encoding.ASCII.GetBytes(msg); 
IPEndPoint groupEP = new IPEndPoint(IPAddress.Parse("255.255.255.255"), server_port); 
sck.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.Broadcast, 1); 
sck.SendTo(sendBytes4, groupEP); 


sck2.ReceiveFrom(buffer, ref remoteEndPoint);