基於C#的內網穿透學習筆記(附原始碼)
如何讓兩臺處在不同內網的主機直接互連?你需要內網穿透!
上圖是一個非完整版內外網通訊圖由內網端先發起,內網裝置192.168.1.2:6677傳送資料到外網時候必須經過nat會轉換成對應的外網ip+埠,然後在傳送給外網裝置,外網裝置回覆資料也是發給你的外網ip+埠。這只是單向的內去外,那反過來,如果外網的裝置需要主動訪問我局域網裡的某一個裝置是無法訪問的,因為這個時候還沒做nat轉換所以外網不知道你內網裝置的應用具體對應的是哪個埠,這個時候我們就需要內網穿透了,內網穿透也叫NAT穿透;
穿透原理 如上圖所示經NAT轉換後的內外網地址+埠,會快取一段時間,在這段時間內192.168.1.2:6677和112.48.69.2020:8899的對映關係會一直存在,這樣你的內網主機就得到一個外網地址,這個對應關係又根據NAT轉換方法型別的不同,得用對應的方式實現打洞,NAT轉換方法型別有下列幾種(來源(2)Address-Restricted cone NAT :限制地址,即只接收曾經發送到對端的IP地址來的資料包。
一旦一個內部地址(iAddr:port1)對映到外部地址(eAddr:port2),所有發自iAddr:port1的包都經由eAddr:port2向外傳送。任意外部主機(hostAddr:any)都能通過給eAddr:port2發包到達iAddr:port1的前提是:iAddr:port1之前傳送過包到hostAddr:any. "any"也就是說埠不受限制(只需知道某個轉換後的外網ip+埠即可。)
(3)Port-Restricted cone NAT:類似受限制錐形NAT(Restricted cone NAT),但是還有埠限制。
一旦一個內部地址(iAddr:port1)對映到外部地址(eAddr:port2),所有發自iAddr:port1的包都經由eAddr:port2向外傳送。一個外部主機(hostAddr:port3)能夠發包到達iAddr:port1的前提是:iAddr:port1之前傳送過包到hostAddr:port3.(雙方需要各自知道對方轉換後的外網ip+埠,然後一方先發一次嘗試連線,另一方在次連線過來的時候就能直接連通了。)
(4)Symmetric NAT(對稱NAT)
每一個來自相同內部IP與port的請求到一個特定目的地的IP地址和埠,對映到一個獨特的外部來源的IP地址和埠。 同一個內部主機發出一個資訊包到不同的目的端,不同的對映使用外部主機收到了一封包從一個內部主機可以送一封包回來(只能和Full cone NAT連,沒法打洞,手機流量開熱點就是,同一個本地埠連線不同的伺服器得到的外網第地址和IP不同!) 例子: 下面用一個例子演示下“受限制錐形NAT”的打洞,實現了這個它前面兩個型別也能通用。對稱型的話不考慮,打不了洞。我們知道要實現兩臺“受限制錐形NAT”互連重點就是要知道對 方轉換後的外網IP+埠,這樣我們可以: 1. 準備一臺Full cone NAT 型別的外網服務端,接受來自兩個客戶端的連線,並對應告知對方ip+埠; 2.知道了對方ip+埠 需要設定socke:Socket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);這樣才能埠複用;目的就是讓連線對外的埠一致; 3.最後,我們可以讓兩臺客戶端互相連線,或者一臺先發一個請求,打個洞;另一個在去連線; 程式碼: 1.TCP+IOCP方式,相對 “面向物件”地實現穿透! 服務端 ServerListener類,用SocketAsyncEventArgs:
/// <summary> /// 打洞服務端,非常的簡單,接收兩個連線並且轉發給對方; /// </summary> public class ServerListener : IServerListener { IPEndPoint EndPoint { get; set; } //訊息委託 public delegate void EventMsg(object sender, string e); public static object obj = new object(); //通知訊息 public event EventMsg NoticeMsg; //接收事件 public event EventMsg ReceivedMsg; /// <summary> /// 上次連結的 /// </summary> private Socket Previous; public ServerListener(IPEndPoint endpoint) { this.EndPoint = endpoint; } private Socket listener; public void Start() { this.listener = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp); var connectArgs = new SocketAsyncEventArgs(); listener.Bind(EndPoint); listener.Listen(2); EndPoint = (IPEndPoint)listener.LocalEndPoint; connectArgs.Completed += OnAccept; //是否同步就完成了,同步完成需要自己觸發 if (!listener.AcceptAsync(connectArgs)) OnAccept(listener, connectArgs); } byte[] bytes = new byte[400]; private void OnAccept(object sender, SocketAsyncEventArgs e) { Socket socket = null; try { var remoteEndPoint1 = e.AcceptSocket.RemoteEndPoint.ToString(); NoticeMsg?.Invoke(sender, $"客戶端:{remoteEndPoint1}連線上我了!\r\n"); SocketAsyncEventArgs readEventArgs = new SocketAsyncEventArgs(); readEventArgs.Completed += OnSocketReceived; readEventArgs.UserToken = e.AcceptSocket; readEventArgs.SetBuffer(bytes, 0, 400); if (!e.AcceptSocket.ReceiveAsync(readEventArgs)) OnSocketReceived(e.AcceptSocket, readEventArgs); lock (obj) { socket = e.AcceptSocket; //上次有連結並且連結還”健在“ if (Previous == null||! Previous.Connected) { Previous = e.AcceptSocket; } else { //Previous.SendAsync()..? Previous.Send(Encoding.UTF8.GetBytes(remoteEndPoint1 + "_1")); socket.Send(Encoding.UTF8.GetBytes(Previous.RemoteEndPoint.ToString() + "_2")); NoticeMsg?.Invoke(sender, $"已經通知雙方!\r\n"); Previous = null; } } e.AcceptSocket = null; if (e.SocketError != SocketError.Success) throw new SocketException((int)e.SocketError); if(!listener.AcceptAsync(e)) OnAccept(listener, e); } catch { socket?.Close(); } } public void Close() { using (listener) { // listener.Shutdown(SocketShutdown.Both); listener.Close(); } //throw new NotImplementedException(); } /// <summary> /// 此處留有一個小BUG,接收的字串大於400的時候會有問題;可以參考客戶端修改 /// </summary> public void OnSocketReceived(object sender, SocketAsyncEventArgs e) { Socket socket = e.UserToken as Socket; var remoteEndPoint = socket.RemoteEndPoint.ToString(); try { if (e.BytesTransferred > 0 && e.SocketError == SocketError.Success) { ReceivedMsg?.Invoke(sender, $"收到:{remoteEndPoint}發來資訊:{Encoding.UTF8.GetString(e.Buffer, 0, e.BytesTransferred)}\r\n"); } else { socket?.Close(); NoticeMsg?.Invoke(sender, $"連結:{remoteEndPoint}釋放啦!\r\n"); return; } if (!socket.ReceiveAsync(e)) OnSocketReceived(socket, e); } catch { socket?.Close(); } //{ // if (!((Socket)sender).AcceptAsync(e)) // OnSocketReceived(sender, e); //} //catch //{ // return; //} } }
2.客戶端類 PeerClient用BeginReceive和EndReceive實現非同步;
public class StateObject
{
public Socket workSocket = null;
public const int BufferSize = 100;
public byte[] buffer = new byte[BufferSize];
public List<byte> buffers = new List<byte>();
//是不是和伺服器的連結
public bool IsServerCon = false;
}
/// <summary>
/// 打洞節點客戶端 實現的功能:
/// 連線伺服器獲取對方節點ip
/// 請求對方ip(打洞)
/// 根據條件判斷是監聽連線還是監聽等待連線
/// </summary>
public class PeerClient : IPeerClient
{
//ManualResetEvent xxxxDone = new ManualResetEvent(false);
//Semaphore
/// <summary>
/// 當前連結
/// </summary>
public Socket Client { get;private set; }
#region 服務端
public string ServerHostName { get;private set; }
public int ServerPort { get; private set; }
#endregion
#region 接收和通知事件
public delegate void EventMsg(object sender, string e);
//接收事件
public event EventMsg ReceivedMsg;
//通知訊息
public event EventMsg NoticeMsg;
#endregion
//本地繫結的節點
private IPEndPoint LocalEP;
public PeerClient(string hostname, int port)
{
Client = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
this.ServerHostName = hostname;
this.ServerPort = port;
}
/// <summary>
/// 初始化客戶端(包括啟動)
/// </summary>
public void Init()
{
try
{
Client.Connect(ServerHostName, ServerPort);
}
catch (SocketException ex)
{
NoticeMsg?.Invoke(Client, $"連線伺服器失敗!{ex}!\r\n");
throw;
}
catch (Exception ex)
{
NoticeMsg?.Invoke(Client, $"連線伺服器失敗!{ex}!\r\n");
throw;
}
NoticeMsg?.Invoke(Client, $"連線上伺服器了!\r\n");
var _localEndPoint = Client.LocalEndPoint.ToString();
LocalEP = new IPEndPoint(IPAddress.Parse(_localEndPoint.Split(':')[0])
, int.Parse(_localEndPoint.Split(':')[1]));
Receive(Client);
}
private void Receive(Socket client)
{
try
{
StateObject state = new StateObject();
state.workSocket = client;
state.IsServerCon = true;
client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
new AsyncCallback(ReceiveCallback), state);
}
catch (Exception e)
{
NoticeMsg?.Invoke(Client, $"接收訊息出錯了{e}!\r\n");
}
}
private void ReceiveCallback(IAsyncResult ar)
{
try
{
var state = (StateObject)ar.AsyncState;
Socket _client = state.workSocket;
//因為到這邊的經常Connected 還是true
//if (!_client.Connected)
//{
// _client.Close();
// return;
//}
SocketError error = SocketError.Success;
int bytesRead = _client.EndReceive(ar,out error);
if (error == SocketError.ConnectionReset)
{
NoticeMsg?.Invoke(Client, $"連結已經釋放!\r\n");
_client.Close();
_client.Dispose();
return;
}
if (SocketError.Success!= error)
{
throw new SocketException((int)error);
}
var arr = state.buffer.AsQueryable().Take(bytesRead).ToArray();
state.buffers.AddRange(arr);
if (bytesRead >= state.buffer.Length)
{
_client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
new AsyncCallback(ReceiveCallback), state);
////state.buffers.CopyTo(state.buffers.Count, state.buffer, 0, bytesRead);
//_client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
// new AsyncCallback(ReceiveCallback), state);
}
else
{
var _msg = Encoding.UTF8.GetString(state.buffers.ToArray());
ReceivedMsg?.Invoke(_client, _msg);
if (state.IsServerCon)
{
_client.Shutdown(SocketShutdown.Both);
_client.Close();
int retryCon = _msg.Contains("_1") ? 1 : 100;
_msg = _msg.Replace("_1", "").Replace("_2", "");
TryConnection(_msg.Split(':')[0], int.Parse(_msg.Split(':')[1]), retryCon);
return;
}
state = new StateObject();
state.IsServerCon = false;
state.workSocket = _client;
_client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
new AsyncCallback(ReceiveCallback), state);
}
}
catch (SocketException ex)
{
//10054
NoticeMsg?.Invoke(Client, $"連結已經釋放!{ex}!\r\n");
}
catch (Exception e)
{
NoticeMsg?.Invoke(Client, $"接收訊息出錯了2{e}!\r\n");
}
}
/// <summary>
/// 打洞或者嘗試連結
/// </summary>
private void TryConnection(string remoteHostname, int remotePort,int retryCon)
{
Client = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
var _iPRemotePoint = new IPEndPoint(IPAddress.Parse(remoteHostname), remotePort);
Client.Bind(LocalEP);
System.Threading.Thread.Sleep(retryCon==1?1:3*1000);
for (int i = 0; i < retryCon; i++)
{
try
{
Client.Connect(_iPRemotePoint);
NoticeMsg?.Invoke(Client, $"已經連線上:{remoteHostname}:{remotePort}!\r\n");
StateObject state = new StateObject();
state.workSocket = Client;
state.IsServerCon = false;
Client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
new AsyncCallback(ReceiveCallback), state);
return;
}
catch
{
NoticeMsg?.Invoke(Client, $"嘗試第{i+1}次連結:{remoteHostname}:{remotePort}!\r\n");
}
}
if (retryCon==1)
{
Listening(LocalEP.Port);
return;
}
NoticeMsg?.Invoke(Client, $"嘗試了{retryCon}次都沒有辦法連線到:{remoteHostname}:{remotePort},涼了!\r\n");
}
/// <summary>
/// 如果連線不成功,因為事先有打洞過了,根據條件監聽 等待對方連線來
/// </summary>
private void Listening(int Port)
{
try
{
Client = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
Client.Bind(new IPEndPoint(IPAddress.Any, Port));
Client.Listen((int)SocketOptionName.MaxConnections);
NoticeMsg?.Invoke(Client, $"開始偵聽斷開等待連結過來!\r\n");
StateObject state = new StateObject();
state.IsServerCon = false;
var _socket = Client.Accept();//只有一個連結 不用BeginAccept
Client.Close();//關係現有偵聽
Client = _socket;
state.workSocket = Client;
NoticeMsg?.Invoke(Client, $"接收到來自{Client.RemoteEndPoint}的連線!\r\n");
Client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
new AsyncCallback(ReceiveCallback), state);
}
catch (Exception ex)
{
NoticeMsg?.Invoke(Client, $"監聽出錯了{ex}涼了!\r\n");
}
//scoket.send
}
/// <summary>
/// 本例子只存在一個成功的連結,對成功的連線傳送訊息!
/// </summary>
/// <param name="strMsg"></param>
public void Send(string strMsg)
{
byte[] bytes = Encoding.UTF8.GetBytes(strMsg);
Client.BeginSend(bytes, 0, bytes.Length, 0,
new AsyncCallback(SendCallback), Client);
}
private void SendCallback(IAsyncResult ar)
{
try
{
Socket _socket = (Socket)ar.AsyncState;
//if(ar.IsCompleted)
_socket.EndSend(ar);
}
catch (Exception e)
{
NoticeMsg?.Invoke(Client, $"傳送訊息出錯了{e}!\r\n");
}
}
}
完整程式碼:
https://gitee.com/qqljcn/zsg_-peer-to-peer
Task+(TcpClient+TcpListener )|(UdpClient)實現 tcp|udp的打洞!這個就不貼程式碼了直接放碼雲連線
https://gitee.com/qqljcn/zsg_-peer-to-peer_-lite
1.本人是個老菜鳥程式碼僅供參考,都是挺久以前寫的也沒有經過嚴格的測試僅能演示這個例子,有不成熟的地方,煩請各位大神海涵指教;
2.不要都用本機試這個例子,本機不走nat
3.然後udp因為是無連線的所以打孔成功後不要等太久再發訊息,nat快取一過就失效了!
4.確定自己不是對稱型nat的話,如果打洞不成功,那就多試幾次!
5 .我這個例子程式碼名字叫 PeerToPeer 但不是真的p2p, 微軟提供了p2p的實現 在using System.Net.PeerToPeer名稱空間下。
以上是通過nat的方式,另外還有一種方式是,通過一個有外網ip的第三方伺服器轉發像 花生殼、nat123這類軟體,也有做個小程式,並且自己在用以後演示;