我正在尝试完成UDP打孔。我的理论基于this article和WIKI page，但我面临着C＃编码的一些问题。这是我的问题：
使用已发布的代码here我现在能够连接到远程计算机并在同一端口侦听传入连接（将2个UDP客户端绑定到同一端口）。
由于某种原因，对同一端口的两个绑定会阻止接收任何数据。 我有一个响应我的连接的UDP服务器，所以如果我在将任何其他客户端绑定到端口之前先连接到它，我会得到它的响应。
如果我将另一个客户端绑定到该端口，则不会在任何一个客户端上收到任何数据。
以下是显示我的问题的2个代码段。第一个连接到远程服务器以在NAT设备上创建规则，然后在另一个线程上启动侦听器以捕获传入的数据包。然后代码将数据包发送到本地IP，以便侦听器获取它。第二个只发送数据包到本地IP，以确保这是有效的。我知道这不是真正的打孔，因为我在不使用NAT设备的情况下将数据包发送给自己。我现在面临一个问题，如果我在NAT设备旁边使用计算机进行连接，我不会想到这会有任何不同。
[编辑] 2012年2月4日 我尝试在我的网络上使用另一台计算机和WireShark（数据包嗅探器）来测试监听器。我看到从其他计算机传入的数据包但是没有被侦听器UDP客户端（udpServer）或发送方UDP客户端（客户端）接收。
[编辑] 2/5/2010 我现在添加了一个函数调用，在初始发送和接收数据包之后关闭第一个UDP客户端，只有第二个UDP客户端才能侦听端口。这有效，我可以从该端口上的网络内部接收数据包。我现在将尝试从网络外部发送和接收数据包。我一发现就会发布我的发现。
使用此代码我在侦听客户端上获取数据：
static void Main(string[] args)
{
IPEndPoint localpt = new IPEndPoint(Dns.Resolve(Dns.GetHostName()).AddressList[0], 4545);
ThreadPool.QueueUserWorkItem(delegate
{
UdpClient udpServer = new UdpClient();
udpServer.ExclusiveAddressUse = false;
udpServer.Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
udpServer.Client.Bind(localpt);
IPEndPoint inEndPoint = new IPEndPoint(IPAddress.Any, 0);
Console.WriteLine("Listening on " + localpt + ".");
byte[] buffer = udpServer.Receive(ref inEndPoint); //this line will block forever
Console.WriteLine("Receive from " + inEndPoint + " " + Encoding.ASCII.GetString(buffer) + ".");
});
Thread.Sleep(1000);
UdpClient udpServer2 = new UdpClient(6000);
// the following lines work and the data is received
udpServer2.Connect(Dns.Resolve(Dns.GetHostName()).AddressList[0], 4545);
udpServer2.Send(new byte[] { 0x41 }, 1);
Console.Read();
}
如果我使用以下代码，在客户端和服务器之间进行连接和数据传输之后，监听UDP客户端将不会收到任何内容：
static void Main(string[] args)
{
IPEndPoint localpt = new IPEndPoint(Dns.Resolve(Dns.GetHostName()).AddressList[0], 4545);
//if the following lines up until serverConnect(); are removed all packets are received correctly
client = new UdpClient();
client.ExclusiveAddressUse = false;
client.Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
client.Client.Bind(localpt);
remoteServerConnect(); //connection to remote server is done here
//response is received correctly and printed to the console
ThreadPool.QueueUserWorkItem(delegate
{
UdpClient udpServer = new UdpClient();
udpServer.ExclusiveAddressUse = false;
udpServer.Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
udpServer.Client.Bind(localpt);
IPEndPoint inEndPoint = new IPEndPoint(IPAddress.Any, 0);
Console.WriteLine("Listening on " + localpt + ".");
byte[] buffer = udpServer.Receive(ref inEndPoint); //this line will block forever
Console.WriteLine("Receive from " + inEndPoint + " " + Encoding.ASCII.GetString(buffer) + ".");
});
Thread.Sleep(1000);
UdpClient udpServer2 = new UdpClient(6000);
// I expected the following line to work and to receive this as well
udpServer2.Connect(Dns.Resolve(Dns.GetHostName()).AddressList[0], 4545);
udpServer2.Send(new byte[] { 0x41 }, 1);
Console.Read();
}
答案 0 :(得分：13)
如果我理解正确的话，你是尝试使用中介服务器进行打孔，在两个不同NAT后面的客户端之间进行点对点通信？
几年前我在c＃中完成了同样的事情，我还没有找到代码，但是如果你愿意的话会给你一些指示：
首先，我不会在udpclient上使用Connect（）函数，因为UDP是一个无连接协议，所有这个功能确实隐藏了UDP套接字的功能。
您应该执行以下步骤：
您应该注意nat上使用的端口可能与客户端PC上的端口不同!!服务器应将此外部端口分发给客户端。 您必须使用外部地址和外部端口发送到！
另请注意，您的NAT可能不支持此类端口转发。一些NAT将指定端口上的所有传入流量转发给您的客户端，这就是您想要的。但是有些nat会对传入的数据包进行过滤，因此可能会阻止其他客户端数据包。但是，使用标准个人用户路由器时不太可能。
答案 1 :(得分：4)
编辑：经过更多测试后，除非我启用UPnP，否则这对我来说似乎根本不起作用。所以我在这里写的很多东西你可能会觉得有用，但很多人没有启用UPnP（因为这是一个安全风险），所以它对他们不起作用。
以下是一些使用PubNub作为中继服务器的代码:)。我不推荐使用此代码而不进行测试，因为它并不完美（我不确定它是否安全或是正确的做事方式？我不是网络专家）但是它应该让你知道该怎么做。到目前为止，它至少对我来说是一个爱好项目。缺少的东西是：
首先，您需要一种获取外部和本地IP的方法。以下是获取本地IP的代码：
// From http://stackoverflow.com/questions/6803073/get-local-ip-address
public string GetLocalIp()
{
var host = Dns.GetHostEntry(Dns.GetHostName());
foreach (var ip in host.AddressList)
{
if (ip.AddressFamily == AddressFamily.InterNetwork)
{
return ip.ToString();
}
}
throw new Exception("Failed to get local IP");
}
以下是一些代码，可以通过尝试一些旨在返回外部IP的网站来获取外部IP
public string GetExternalIp()
{
for (int i = 0; i < 2; i++)
{
string res = GetExternalIpWithTimeout(400);
if (res != "")
{
return res;
}
}
throw new Exception("Failed to get external IP");
}
private static string GetExternalIpWithTimeout(int timeoutMillis)
{
string[] sites = new string[] {
"http://ipinfo.io/ip",
"http://icanhazip.com/",
"http://ipof.in/txt",
"http://ifconfig.me/ip",
"http://ipecho.net/plain"
};
foreach (string site in sites)
{
try
{
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(site);
request.Timeout = timeoutMillis;
using (var webResponse = (HttpWebResponse)request.GetResponse())
{
using (Stream responseStream = webResponse.GetResponseStream())
{
using (StreamReader responseReader = new System.IO.StreamReader(responseStream, Encoding.UTF8))
{
return responseReader.ReadToEnd().Trim();
}
}
}
}
catch
{
continue;
}
}
return "";
}
现在我们需要找到一个开放端口并将其转发到外部端口。如上所述，我使用了Open.NAT。首先，在查看registered UDP ports之后，将您认为合理的端口列表放在一起，以供应用程序使用。以下是一些例子：
public static int[] ports = new int[]
{
5283,
5284,
5285,
5286,
5287,
5288,
5289,
5290,
5291,
5292,
5293,
5294,
5295,
5296,
5297
};
现在我们可以遍历它们，并希望找到一个未使用的端口转发：
public UdpClient GetUDPClientFromPorts(out Socket portHolder, out string localIp, out int localPort, out string externalIp, out int externalPort)
{
localIp = GetLocalIp();
externalIp = GetExternalIp();
var discoverer = new Open.Nat.NatDiscoverer();
var device = discoverer.DiscoverDeviceAsync().Result;
IPAddress localAddr = IPAddress.Parse(localIp);
int workingPort = -1;
for (int i = 0; i < ports.Length; i++)
{
try
{
// You can alternatively test tcp with nc -vz externalip 5293 in linux and
// udp with nc -vz -u externalip 5293 in linux
Socket tempServer = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
tempServer.Bind(new IPEndPoint(localAddr, ports[i]));
tempServer.Close();
workingPort = ports[i];
break;
}
catch
{
// Binding failed, port is in use, try next one
}
}
if (workingPort == -1)
{
throw new Exception("Failed to connect to a port");
}
int localPort = workingPort;
// You could try a different external port if the below code doesn't work
externalPort = workingPort;
// Mapping ports
device.CreatePortMapAsync(new Open.Nat.Mapping(Open.Nat.Protocol.Udp, localPort, externalPort));
// Bind a socket to our port to "claim" it or cry if someone else is now using it
try
{
portHolder = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
portHolder.Bind(new IPEndPoint(localAddr, localPort));
}
catch
{
throw new Exception("Failed, someone is now using local port: " + localPort);
}
// Make a UDP Client that will use that port
UdpClient udpClient = new UdpClient(localPort);
return udpClient;
}
现在为PubNub中继服务器代码（P2PPeer将在下面定义）。这里有很多，所以我不会解释它，但希望代码足够清楚，以帮助您了解正在发生的事情
public delegate void NewPeerCallback(P2PPeer newPeer);
public event NewPeerCallback OnNewPeerConnection;
public Pubnub pubnub;
public string pubnubChannelName;
public string localIp;
public string externalIp;
public int localPort;
public int externalPort;
public UdpClient udpClient;
HashSet<string> uniqueIdsPubNubSeen;
object peerLock = new object();
Dictionary<string, P2PPeer> connectedPeers;
string myPeerDataString;
public void InitPubnub(string pubnubPublishKey, string pubnubSubscribeKey, string pubnubChannelName)
{
uniqueIdsPubNubSeen = new HashSet<string>();
connectedPeers = new Dictionary<string, P2PPeer>;
pubnub = new Pubnub(pubnubPublishKey, pubnubSubscribeKey);
myPeerDataString = localIp + " " + externalIp + " " + localPort + " " + externalPort + " " + pubnub.SessionUUID;
this.pubnubChannelName = pubnubChannelName;
pubnub.Subscribe<string>(
pubnubChannelName,
OnPubNubMessage,
OnPubNubConnect,
OnPubNubError);
return pubnub;
}
//// Subscribe callbacks
void OnPubNubConnect(string res)
{
pubnub.Publish<string>(pubnubChannelName, connectionDataString, OnPubNubTheyGotMessage, OnPubNubMessageFailed);
}
void OnPubNubError(PubnubClientError clientError)
{
throw new Exception("PubNub error on subscribe: " + clientError.Message);
}
void OnPubNubMessage(string message)
{
// The message will be the string ["localIp externalIp localPort externalPort","messageId","channelName"]
string[] splitMessage = message.Trim().Substring(1, message.Length - 2).Split(new char[] { ',' });
string peerDataString = splitMessage[0].Trim().Substring(1, splitMessage[0].Trim().Length - 2);
// If you want these, I don't need them
//string peerMessageId = splitMessage[1].Trim().Substring(1, splitMessage[1].Trim().Length - 2);
//string channelName = splitMessage[2].Trim().Substring(1, splitMessage[2].Trim().Length - 2);
string[] pieces = peerDataString.Split(new char[] { ' ', '\t' });
string peerLocalIp = pieces[0].Trim();
string peerExternalIp = pieces[1].Trim();
string peerLocalPort = int.Parse(pieces[2].Trim());
string peerExternalPort = int.Parse(pieces[3].Trim());
string peerPubnubUniqueId = pieces[4].Trim();
pubNubUniqueId = pieces[4].Trim();
// If you are on the same device then you have to do this for it to work idk why
if (peerLocalIp == localIp && peerExternalIp == externalIp)
{
peerLocalIp = "127.0.0.1";
}
// From me, ignore
if (peerPubnubUniqueId == pubnub.SessionUUID)
{
return;
}
// We haven't set up our connection yet, what are we doing
if (udpClient == null)
{
return;
}
// From someone else
IPEndPoint peerEndPoint = new IPEndPoint(IPAddress.Parse(peerExternalIp), peerExternalPort);
IPEndPoint peerEndPointLocal = new IPEndPoint(IPAddress.Parse(peerLocalIp), peerLocalPort);
// First time we have heard from them
if (!uniqueIdsPubNubSeen.Contains(peerPubnubUniqueId))
{
uniqueIdsPubNubSeen.Add(peerPubnubUniqueId);
// Dummy messages to do UDP hole punching, these may or may not go through and that is fine
udpClient.Send(new byte[10], 10, peerEndPoint);
udpClient.Send(new byte[10], 10, peerEndPointLocal); // This is if they are on a LAN, we will try both
pubnub.Publish<string>(pubnubChannelName, myPeerDataString, OnPubNubTheyGotMessage, OnPubNubMessageFailed);
}
// Second time we have heard from them, after then we don't care because we are connected
else if (!connectedPeers.ContainsKey(peerPubnubUniqueId))
{
//bool isOnLan = IsOnLan(IPAddress.Parse(peerExternalIp)); TODO, this would be nice to test for
bool isOnLan = false; // For now we will just do things for both
P2PPeer peer = new P2PPeer(peerLocalIp, peerExternalIp, peerLocalPort, peerExternalPort, this, isOnLan);
lock (peerLock)
{
connectedPeers.Add(peerPubnubUniqueId, peer);
}
// More dummy messages because why not
udpClient.Send(new byte[10], 10, peerEndPoint);
udpClient.Send(new byte[10], 10, peerEndPointLocal);
pubnub.Publish<string>(pubnubChannelName, connectionDataString, OnPubNubTheyGotMessage, OnPubNubMessageFailed);
if (OnNewPeerConnection != null)
{
OnNewPeerConnection(peer);
}
}
}
//// Publish callbacks
void OnPubNubTheyGotMessage(object result)
{
}
void OnPubNubMessageFailed(PubnubClientError clientError)
{
throw new Exception("PubNub error on publish: " + clientError.Message);
}
这是P2PPeer
public class P2PPeer
{
public string localIp;
public string externalIp;
public int localPort;
public int externalPort;
public bool isOnLan;
P2PClient client;
public delegate void ReceivedBytesFromPeerCallback(byte[] bytes);
public event ReceivedBytesFromPeerCallback OnReceivedBytesFromPeer;
public P2PPeer(string localIp, string externalIp, int localPort, int externalPort, P2PClient client, bool isOnLan)
{
this.localIp = localIp;
this.externalIp = externalIp;
this.localPort = localPort;
this.externalPort = externalPort;
this.client = client;
this.isOnLan = isOnLan;
if (isOnLan)
{
IPEndPoint endPointLocal = new IPEndPoint(IPAddress.Parse(localIp), localPort);
Thread localListener = new Thread(() => ReceiveMessage(endPointLocal));
localListener.IsBackground = true;
localListener.Start();
}
else
{
IPEndPoint endPoint = new IPEndPoint(IPAddress.Parse(externalIp), externalPort);
Thread externalListener = new Thread(() => ReceiveMessage(endPoint));
externalListener.IsBackground = true;
externalListener.Start();
}
}
public void SendBytes(byte[] data)
{
if (client.udpClient == null)
{
throw new Exception("P2PClient doesn't have a udpSocket open anymore");
}
//if (isOnLan) // This would work but I'm not sure how to test if they are on LAN so I'll just use both for now
{
client.udpClient.Send(data, data.Length, new IPEndPoint(IPAddress.Parse(localIp), localPort));
}
//else
{
client.udpClient.Send(data, data.Length, new IPEndPoint(IPAddress.Parse(externalIp), externalPort));
}
}
// Encoded in UTF8
public void SendString(string str)
{
SendBytes(System.Text.Encoding.UTF8.GetBytes(str));
}
void ReceiveMessage(IPEndPoint endPoint)
{
while (client.udpClient != null)
{
byte[] message = client.udpClient.Receive(ref endPoint);
if (OnReceivedBytesFromPeer != null)
{
OnReceivedBytesFromPeer(message);
}
//string receiveString = Encoding.UTF8.GetString(message);
//Console.Log("got: " + receiveString);
}
}
}
最后，以下是我的所有用法：
using PubNubMessaging.Core; // Get from PubNub GitHub for C#, I used the Unity3D library
using System;
using System.Collections.Generic;
using System.IO;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Threading;
我愿意接受评论和提问，如果这里的内容不好或者不起作用，请随时提供反馈。我的代码翻译中引入了一些错误，我最终会在这里修复，但这至少应该让你知道该怎么做。
答案 2 :(得分：3)
您是否尝试过使用Async函数，以下是一个如何使其工作的示例，可能需要一些工作才能使其100％正常运行：
public void HolePunch(String ServerIp, Int32 Port)
{
IPEndPoint LocalPt = new IPEndPoint(Dns.GetHostEntry(Dns.GetHostName()).AddressList[0], Port);
UdpClient Client = new UdpClient();
Client.ExclusiveAddressUse = false;
Client.Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
Client.Client.Bind(LocalPt);
IPEndPoint RemotePt = new IPEndPoint(IPAddress.Parse(ServerIp), Port);
// This Part Sends your local endpoint to the server so if the two peers are on the same nat they can bypass it, you can omit this if you wish to just use the remote endpoint.
byte[] IPBuffer = System.Text.Encoding.UTF8.GetBytes(Dns.GetHostEntry(Dns.GetHostName()).AddressList[0].ToString());
byte[] LengthBuffer = BitConverter.GetBytes(IPBuffer.Length);
byte[] PortBuffer = BitConverter.GetBytes(Port);
byte[] Buffer = new byte[IPBuffer.Length + LengthBuffer.Length + PortBuffer.Length];
LengthBuffer.CopyTo(Buffer,0);
IPBuffer.CopyTo(Buffer, LengthBuffer.Length);
PortBuffer.CopyTo(Buffer, IPBuffer.Length + LengthBuffer.Length);
Client.BeginSend(Buffer, Buffer.Length, RemotePt, new AsyncCallback(SendCallback), Client);
// Wait to receve something
BeginReceive(Client, Port);
// you may want to use a auto or manual ResetEvent here and have the server send back a confirmation, the server should have now stored your local (you sent it) and remote endpoint.
// you now need to work out who you need to connect to then ask the server for there remote and local end point then need to try to connect to the local first then the remote.
// if the server knows who you need to connect to you could just have it send you the endpoints as the confirmation.
// you may also need to keep this open with a keepalive packet untill it is time to connect to the peer or peers.
// once you have the endpoints of the peer you can close this connection unless you need to keep asking the server for other endpoints
Client.Close();
}
public void ConnectToPeer(String PeerIp, Int32 Port)
{
IPEndPoint LocalPt = new IPEndPoint(Dns.GetHostEntry(Dns.GetHostName()).AddressList[0], Port);
UdpClient Client = new UdpClient();
Client.ExclusiveAddressUse = false;
Client.Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
Client.Client.Bind(LocalPt);
IPEndPoint RemotePt = new IPEndPoint(IPAddress.Parse(PeerIp), Port);
Client.Connect(RemotePt);
//you may want to keep the peer client connections in a list.
BeginReceive(Client, Port);
}
public void SendCallback(IAsyncResult ar)
{
UdpClient Client = (UdpClient)ar.AsyncState;
Client.EndSend(ar);
}
public void BeginReceive(UdpClient Client, Int32 Port)
{
IPEndPoint ListenPt = new IPEndPoint(IPAddress.Any, Port);
Object[] State = new Object[] { Client, ListenPt };
Client.BeginReceive(new AsyncCallback(ReceiveCallback), State);
}
public void ReceiveCallback(IAsyncResult ar)
{
UdpClient Client = (UdpClient)((Object[])ar.AsyncState)[0];
IPEndPoint ListenPt = (IPEndPoint)((Object[])ar.AsyncState)[0];
Byte[] receiveBytes = Client.EndReceive(ar, ref ListenPt);
}
我希望这会有所帮助。
答案 3 :(得分：1)
<强>更新
无论哪个UdpClients首先绑定是由Windows发送传入数据包的那个。在您的示例中，尝试将设置侦听线程的代码块移动到顶部。
您确定问题不仅仅是接收线程只是为了处理单个接收而编写的吗？尝试使用以下方法替换接收线程。
ThreadPool.QueueUserWorkItem(delegate
{
UdpClient udpServer = new UdpClient();
udpServer.ExclusiveAddressUse = false;
udpServer.Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
udpServer.Client.Bind(localpt);
IPEndPoint inEndPoint = new IPEndPoint(IPAddress.Any, 0);
Console.WriteLine("Listening on " + localpt + ".");
while (inEndPoint != null)
{
byte[] buffer = udpServer.Receive(ref inEndPoint);
Console.WriteLine("Bytes received from " + inEndPoint + " " + Encoding.ASCII.GetString(buffer) + ".");
}
});
答案 4 :(得分：0)
很抱歉，上传了如此庞大的代码，但是我想这很清楚地解释了事情是如何工作的，可能真的有用。如果您对此代码有疑问，请告诉我。
注意：
UdpClient的服务器与服务器通信Server.cs
using System;
using System.Collections.Generic;
using System.Net;
using System.Net.Sockets;
using HolePunching.Common;
namespace HolePunching.Server
{
class Server
{
private static bool _isRunning;
private static UdpClient _udpClient;
private static readonly Dictionary<byte, PeerContext> Contexts = new Dictionary<byte, PeerContext>();
private static readonly Dictionary<byte, byte> Mappings = new Dictionary<byte, byte>
{
{1, 2},
{2, 1},
};
static void Main()
{
_udpClient = new UdpClient( Consts.UdpPort );
ListenUdp();
Console.ReadLine();
_isRunning = false;
}
private static async void ListenUdp()
{
_isRunning = true;
while ( _isRunning )
{
try
{
var receivedResults = await _udpClient.ReceiveAsync();
if ( !_isRunning )
{
break;
}
ProcessUdpMessage( receivedResults.Buffer, receivedResults.RemoteEndPoint );
}
catch ( Exception ex )
{
Console.WriteLine( $"Error: {ex.Message}" );
}
}
}
private static void ProcessUdpMessage( byte[] buffer, IPEndPoint remoteEndPoint )
{
if ( !UdpProtocol.UdpInfoMessage.TryParse( buffer, out UdpProtocol.UdpInfoMessage message ) )
{
Console.WriteLine( $" >>> Got shitty UDP [ {remoteEndPoint.Address} : {remoteEndPoint.Port} ]" );
_udpClient.Send( new byte[] { 1 }, 1, remoteEndPoint );
return;
}
Console.WriteLine( $" >>> Got UDP from {message.Id}. [ {remoteEndPoint.Address} : {remoteEndPoint.Port} ]" );
if ( !Contexts.TryGetValue( message.Id, out PeerContext context ) )
{
context = new PeerContext
{
PeerId = message.Id,
PublicUdpEndPoint = remoteEndPoint,
LocalUdpEndPoint = new IPEndPoint( message.LocalIp, message.LocalPort ),
};
Contexts.Add( context.PeerId, context );
}
byte partnerId = Mappings[context.PeerId];
if ( !Contexts.TryGetValue( partnerId, out context ) )
{
_udpClient.Send( new byte[] { 1 }, 1, remoteEndPoint );
return;
}
var response = UdpProtocol.PeerAddressMessage.GetMessage(
partnerId,
context.PublicUdpEndPoint.Address,
context.PublicUdpEndPoint.Port,
context.LocalUdpEndPoint.Address,
context.LocalUdpEndPoint.Port );
_udpClient.Send( response.Data, response.Data.Length, remoteEndPoint );
Console.WriteLine( $" <<< Responsed to {message.Id}" );
}
}
public class PeerContext
{
public byte PeerId { get; set; }
public IPEndPoint PublicUdpEndPoint { get; set; }
public IPEndPoint LocalUdpEndPoint { get; set; }
}
}
Client.cs
using System;
namespace HolePunching.Client
{
class Client
{
public const string ServerIp = "your.server.public.address";
static void Main()
{
byte id = ReadIdFromConsole();
// you need some smarter :)
int localPort = id == 1 ? 61043 : 59912;
var x = new Demo( ServerIp, id, localPort );
x.Start();
}
private static byte ReadIdFromConsole()
{
Console.Write( "Peer id (1 or 2): " );
var id = byte.Parse( Console.ReadLine() );
Console.Title = $"Peer {id}";
return id;
}
}
}
Demo.cs
using HolePunching.Common;
using System;
using System.Collections.Generic;
using System.Net;
using System.Net.Sockets;
using System.Threading;
using System.Threading.Tasks;
namespace HolePunching.Client
{
public class Demo
{
private static bool _isRunning;
private static UdpClient _udpPuncher;
private static UdpClient _udpClient;
private static UdpClient _extraUdpClient;
private static bool _extraUdpClientConnected;
private static byte _id;
private static IPEndPoint _localEndPoint;
private static IPEndPoint _serverUdpEndPoint;
private static IPEndPoint _partnerPublicUdpEndPoint;
private static IPEndPoint _partnerLocalUdpEndPoint;
private static string GetLocalIp()
{
var host = Dns.GetHostEntry( Dns.GetHostName() );
foreach ( var ip in host.AddressList )
{
if ( ip.AddressFamily == AddressFamily.InterNetwork )
{
return ip.ToString();
}
}
throw new Exception( "Failed to get local IP" );
}
public Demo( string serverIp, byte id, int localPort )
{
_serverUdpEndPoint = new IPEndPoint( IPAddress.Parse( serverIp ), Consts.UdpPort );
_id = id;
// we have to bind all our UdpClients to this endpoint
_localEndPoint = new IPEndPoint( IPAddress.Parse( GetLocalIp() ), localPort );
}
public void Start( )
{
_udpPuncher = new UdpClient(); // this guy is just for punching
_udpClient = new UdpClient(); // this will keep hole alive, and also can send data
_extraUdpClient = new UdpClient(); // i think, this guy is the best option for sending data (explained below)
InitUdpClients( new[] { _udpPuncher, _udpClient, _extraUdpClient }, _localEndPoint );
Task.Run( (Action) SendUdpMessages );
Task.Run( (Action) ListenUdp );
Console.ReadLine();
_isRunning = false;
}
private void InitUdpClients(IEnumerable<UdpClient> clients, EndPoint localEndPoint)
{
// if you don't want to use explicit localPort, you should create here one more UdpClient (X) and send something to server (it will automatically bind X to free port). then bind all clients to this port and close X
foreach ( var udpClient in clients )
{
udpClient.ExclusiveAddressUse = false;
udpClient.Client.SetSocketOption( SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true );
udpClient.Client.Bind( localEndPoint );
}
}
private void SendUdpMessages()
{
_isRunning = true;
var messageToServer = UdpProtocol.UdpInfoMessage.GetMessage( _id, _localEndPoint.Address, _localEndPoint.Port );
var messageToPeer = UdpProtocol.P2PKeepAliveMessage.GetMessage();
while ( _isRunning )
{
// while we dont have partner's address, we will send messages to server
if ( _partnerPublicUdpEndPoint == null && _partnerLocalUdpEndPoint == null )
{
_udpPuncher.Send( messageToServer.Data, messageToServer.Data.Length, _serverUdpEndPoint );
Console.WriteLine( $" >>> Sent UDP to server [ {_serverUdpEndPoint.Address} : {_serverUdpEndPoint.Port} ]" );
}
else
{
// you can skip it. just demonstration, that you still can send messages to server
_udpClient.Send( messageToServer.Data, messageToServer.Data.Length, _serverUdpEndPoint );
Console.WriteLine( $" >>> Sent UDP to server [ {_serverUdpEndPoint.Address} : {_serverUdpEndPoint.Port} ]" );
// THIS is how we punching hole! very first this message should be dropped by partner's NAT, but it's ok.
// i suppose that this is good idea to send this "keep-alive" messages to peer even if you are connected already,
// because AFAIK "hole" for UDP lives ~2 minutes on NAT. so "we will let it die? NEVER!" (c)
_udpClient.Send( messageToPeer.Data, messageToPeer.Data.Length, _partnerPublicUdpEndPoint );
_udpClient.Send( messageToPeer.Data, messageToPeer.Data.Length, _partnerLocalUdpEndPoint );
Console.WriteLine( $" >>> Sent UDP to peer.public [ {_partnerPublicUdpEndPoint.Address} : {_partnerPublicUdpEndPoint.Port} ]" );
Console.WriteLine( $" >>> Sent UDP to peer.local [ {_partnerLocalUdpEndPoint.Address} : {_partnerLocalUdpEndPoint.Port} ]" );
// "connected" UdpClient sends data much faster,
// so if you have something that your partner cant wait for (voice, for example), send it this way
if ( _extraUdpClientConnected )
{
_extraUdpClient.Send( messageToPeer.Data, messageToPeer.Data.Length );
Console.WriteLine( $" >>> Sent UDP to peer.received EP" );
}
}
Thread.Sleep( 3000 );
}
}
private async void ListenUdp()
{
_isRunning = true;
while ( _isRunning )
{
try
{
// also important thing!
// when you did not punched hole yet, you must listen incoming packets using "puncher" (later we will close it).
// where you already have p2p connection (and "puncher" closed), use "non-puncher"
UdpClient udpClient = _partnerPublicUdpEndPoint == null ? _udpPuncher : _udpClient;
var receivedResults = await udpClient.ReceiveAsync();
if ( !_isRunning )
{
break;
}
ProcessUdpMessage( receivedResults.Buffer, receivedResults.RemoteEndPoint );
}
catch ( SocketException ex )
{
// do something here...
}
catch ( Exception ex )
{
Console.WriteLine( $"Error: {ex.Message}" );
}
}
}
private static void ProcessUdpMessage( byte[] buffer, IPEndPoint remoteEndPoint )
{
// if server sent partner's endpoinps, we will store it and (IMPORTANT) close "puncher"
if ( UdpProtocol.PeerAddressMessage.TryParse( buffer, out UdpProtocol.PeerAddressMessage peerAddressMessage ) )
{
Console.WriteLine( " <<< Got response from server" );
_partnerPublicUdpEndPoint = new IPEndPoint( peerAddressMessage.PublicIp, peerAddressMessage.PublicPort );
_partnerLocalUdpEndPoint = new IPEndPoint( peerAddressMessage.LocalIp, peerAddressMessage.LocalPort );
_udpPuncher.Close();
}
// since we got this message we know partner's endpoint for sure,
// and we can "connect" UdpClient to it, so it will work faster
else if ( UdpProtocol.P2PKeepAliveMessage.TryParse( buffer ) )
{
Console.WriteLine( $" IT WORKS!!! WOW!!! [ {remoteEndPoint.Address} : {remoteEndPoint.Port} ]" );
_extraUdpClientConnected = true;
_extraUdpClient.Connect( remoteEndPoint );
}
else
{
Console.WriteLine( "???" );
}
}
}
}
Protocol.cs
我不确定这种方法的效果如何，也许像protobuf这样的方法可以做得更好
using System;
using System.Linq;
using System.Net;
using System.Text;
namespace HolePunching.Common
{
public static class UdpProtocol
{
public static readonly int GuidLength = 16;
public static readonly int PeerIdLength = 1;
public static readonly int IpLength = 4;
public static readonly int IntLength = 4;
public static readonly byte[] Prefix = { 12, 23, 34, 45 };
private static byte[] JoinBytes( params byte[][] bytes )
{
var result = new byte[bytes.Sum( x => x.Length )];
int pos = 0;
for ( int i = 0; i < bytes.Length; i++ )
{
for ( int j = 0; j < bytes[i].Length; j++, pos++ )
{
result[pos] = bytes[i][j];
}
}
return result;
}
#region Helper extensions
private static bool StartsWith( this byte[] @this, byte[] value, int offset = 0 )
{
if ( @this == null || value == null || @this.Length < offset + value.Length )
{
return false;
}
for ( int i = 0; i < value.Length; i++ )
{
if ( @this[i + offset] < value[i] )
{
return false;
}
}
return true;
}
private static byte[] ToUnicodeBytes( this string @this )
{
return Encoding.Unicode.GetBytes( @this );
}
private static byte[] Take( this byte[] @this, int offset, int length )
{
return @this.Skip( offset ).Take( length ).ToArray();
}
public static bool IsSuitableUdpMessage( this byte[] @this )
{
return @this.StartsWith( Prefix );
}
public static int GetInt( this byte[] @this )
{
if ( @this.Length != 4 )
throw new ArgumentException( "Byte array must be exactly 4 bytes to be convertible to uint." );
return ( ( ( @this[0] << 8 ) + @this[1] << 8 ) + @this[2] << 8 ) + @this[3];
}
public static byte[] ToByteArray( this int value )
{
return new[]
{
(byte)(value >> 24),
(byte)(value >> 16),
(byte)(value >> 8),
(byte)value
};
}
#endregion
#region Messages
public abstract class UdpMessage
{
public byte[] Data { get; }
protected UdpMessage( byte[] data )
{
Data = data;
}
}
public class UdpInfoMessage : UdpMessage
{
private static readonly byte[] MessagePrefix = { 41, 57 };
private static readonly int MessageLength = Prefix.Length + MessagePrefix.Length + PeerIdLength + IpLength + IntLength;
public byte Id { get; }
public IPAddress LocalIp { get; }
public int LocalPort { get; }
private UdpInfoMessage( byte[] data, byte id, IPAddress localIp, int localPort )
: base( data )
{
Id = id;
LocalIp = localIp;
LocalPort = localPort;
}
public static UdpInfoMessage GetMessage( byte id, IPAddress localIp, int localPort )
{
var data = JoinBytes( Prefix, MessagePrefix, new[] { id }, localIp.GetAddressBytes(), localPort.ToByteArray() );
return new UdpInfoMessage( data, id, localIp, localPort );
}
public static bool TryParse( byte[] data, out UdpInfoMessage message )
{
message = null;
if ( !data.StartsWith( Prefix ) )
return false;
if ( !data.StartsWith( MessagePrefix, Prefix.Length ) )
return false;
if ( data.Length != MessageLength )
return false;
int index = Prefix.Length + MessagePrefix.Length;
byte id = data[index];
index += PeerIdLength;
byte[] localIpBytes = data.Take( index, IpLength );
var localIp = new IPAddress( localIpBytes );
index += IpLength;
byte[] localPortBytes = data.Take( index, IntLength );
int localPort = localPortBytes.GetInt();
message = new UdpInfoMessage( data, id, localIp, localPort );
return true;
}
}
public class PeerAddressMessage : UdpMessage
{
private static readonly byte[] MessagePrefix = { 36, 49 };
private static readonly int MessageLength = Prefix.Length + MessagePrefix.Length + PeerIdLength + ( IpLength + IntLength ) * 2;
public byte Id { get; }
public IPAddress PublicIp { get; }
public int PublicPort { get; }
public IPAddress LocalIp { get; }
public int LocalPort { get; }
private PeerAddressMessage( byte[] data, byte id, IPAddress publicIp, int publicPort, IPAddress localIp, int localPort )
: base( data )
{
Id = id;
PublicIp = publicIp;
PublicPort = publicPort;
LocalIp = localIp;
LocalPort = localPort;
}
public static PeerAddressMessage GetMessage( byte id, IPAddress publicIp, int publicPort, IPAddress localIp, int localPort )
{
var data = JoinBytes( Prefix, MessagePrefix, new[] { id },
publicIp.GetAddressBytes(), publicPort.ToByteArray(),
localIp.GetAddressBytes(), localPort.ToByteArray() );
return new PeerAddressMessage( data, id, publicIp, publicPort, localIp, localPort );
}
public static bool TryParse( byte[] data, out PeerAddressMessage message )
{
message = null;
if ( !data.StartsWith( Prefix ) )
return false;
if ( !data.StartsWith( MessagePrefix, Prefix.Length ) )
return false;
if ( data.Length != MessageLength )
return false;
int index = Prefix.Length + MessagePrefix.Length;
byte id = data[index];
index += PeerIdLength;
byte[] publicIpBytes = data.Take( index, IpLength );
var publicIp = new IPAddress( publicIpBytes );
index += IpLength;
byte[] publicPortBytes = data.Take( index, IntLength );
int publicPort = publicPortBytes.GetInt();
index += IntLength;
byte[] localIpBytes = data.Take( index, IpLength );
var localIp = new IPAddress( localIpBytes );
index += IpLength;
byte[] localPortBytes = data.Take( index, IntLength );
int localPort = localPortBytes.GetInt();
message = new PeerAddressMessage( data, id, publicIp, publicPort, localIp, localPort );
return true;
}
}
public class P2PKeepAliveMessage : UdpMessage
{
private static readonly byte[] MessagePrefix = { 11, 19 };
private static P2PKeepAliveMessage _message;
private P2PKeepAliveMessage( byte[] data )
: base( data )
{
}
public static bool TryParse( byte[] data )
{
if ( !data.StartsWith( Prefix ) )
return false;
if ( !data.StartsWith( MessagePrefix, Prefix.Length ) )
return false;
return true;
}
public static P2PKeepAliveMessage GetMessage()
{
if ( _message == null )
{
var data = JoinBytes( Prefix, MessagePrefix );
_message = new P2PKeepAliveMessage( data );
}
return _message;
}
}
#endregion
}
}