C# 在 .NET 中查找下一个 TCP 端口

Find the next TCP port in .NET

提问by TheSeeker

I want to create a new net.tcp://localhost:x/Service endpoint for a WCF service call, with a dynamically assigned new open TCP port.

我想为 WCF 服务调用创建一个新的 net.tcp://localhost:x/Service 端点，并动态分配一个新的开放 TCP 端口。

I know that TcpClient will assign a new client side port when I open a connection to a given server.

我知道当我打开与给定服务器的连接时，TcpClient 将分配一个新的客户端端口。

Is there a simple way to find the next open TCP port in .NET?

有没有一种简单的方法可以在 .NET 中找到下一个打开的 TCP 端口？

I need the actual number, so that I can build the string above. 0 does not work, since I need to pass that string to another process, so that I can call back on that new channel.

我需要实际数字，以便我可以构建上面的字符串。0 不起作用，因为我需要将该字符串传递给另一个进程，以便我可以回调该新通道。

采纳答案by TheSeeker

Here is what I was looking for:

这是我一直在寻找的：

static int FreeTcpPort()
{
  TcpListener l = new TcpListener(IPAddress.Loopback, 0);
  l.Start();
  int port = ((IPEndPoint)l.LocalEndpoint).Port;
  l.Stop();
  return port;
}

回答by Jerub

Use a port number of 0. The TCP stack will allocate the next free one.

使用端口号 0。TCP 堆栈将分配下一个空闲端口。

回答by jan.vdbergh

First open the port, then give the correct port number to the other process.

先打开端口，然后给其他进程正确的端口号。

Otherwise it is still possible that some other process opens the port first and you still have a different one.

否则，仍然有可能是其他某个进程首先打开了该端口，而您仍然拥有不同的端口。

回答by yoavs

If you want to get a free port in a specific range in order to use it as local port / end point:

如果您想获得特定范围内的空闲端口以将其用作本地端口/终点：

private int GetFreePortInRange(int PortStartIndex, int PortEndIndex)
{
    DevUtils.LogDebugMessage(string.Format("GetFreePortInRange, PortStartIndex: {0} PortEndIndex: {1}", PortStartIndex, PortEndIndex));
    try
    {
        IPGlobalProperties ipGlobalProperties = IPGlobalProperties.GetIPGlobalProperties();

        IPEndPoint[] tcpEndPoints = ipGlobalProperties.GetActiveTcpListeners();
        List<int> usedServerTCpPorts = tcpEndPoints.Select(p => p.Port).ToList<int>();

        IPEndPoint[] udpEndPoints = ipGlobalProperties.GetActiveUdpListeners();
        List<int> usedServerUdpPorts = udpEndPoints.Select(p => p.Port).ToList<int>();

        TcpConnectionInformation[] tcpConnInfoArray = ipGlobalProperties.GetActiveTcpConnections();
        List<int> usedPorts = tcpConnInfoArray.Where(p=> p.State != TcpState.Closed).Select(p => p.LocalEndPoint.Port).ToList<int>();

        usedPorts.AddRange(usedServerTCpPorts.ToArray());
        usedPorts.AddRange(usedServerUdpPorts.ToArray());

        int unusedPort = 0;

        for (int port = PortStartIndex; port < PortEndIndex; port++)
        {
            if (!usedPorts.Contains(port))
            {
                unusedPort = port;
                break;
            }
        }
        DevUtils.LogDebugMessage(string.Format("Local unused Port:{0}", unusedPort.ToString()));

        if (unusedPort == 0)
        {
            DevUtils.LogErrorMessage("Out of ports");
            throw new ApplicationException("GetFreePortInRange, Out of ports");
        }

        return unusedPort;
    }
    catch (Exception ex)
    {
        string errorMessage = ex.Message;
        DevUtils.LogErrorMessage(errorMessage);
        throw;
    }
}


private int GetLocalFreePort()
{
    int hemoStartLocalPort = int.Parse(DBConfig.GetField("Site.Config.hemoStartLocalPort"));
    int hemoEndLocalPort = int.Parse(DBConfig.GetField("Site.Config.hemoEndLocalPort"));
    int localPort = GetFreePortInRange(hemoStartLocalPort, hemoEndLocalPort);
    DevUtils.LogDebugMessage(string.Format("Local Free Port:{0}", localPort.ToString()));
    return localPort;
}


public void Connect(string host, int port)
{
    try
    {
        // Create socket
        Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
        //socket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);

        var localPort = GetLocalFreePort();
        // Create an endpoint for the specified IP on any port
        IPEndPoint bindEndPoint = new IPEndPoint(IPAddress.Any, localPort);

        // Bind the socket to the endpoint
        socket.Bind(bindEndPoint);

        // Connect to host
        socket.Connect(IPAddress.Parse(host), port);

        socket.Dispose();
    }
    catch (SocketException ex)
    {
        // Get the error message
        string errorMessage = ex.Message;
        DevUtils.LogErrorMessage(errorMessage);
    }
}


public void Connect2(string host, int port)
{
    try
    {
        // Create socket

        var localPort = GetLocalFreePort();

        // Create an endpoint for the specified IP on any port
        IPEndPoint bindEndPoint = new IPEndPoint(IPAddress.Any, localPort);

        var client = new TcpClient(bindEndPoint);
        //client.Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true); //will release port when done

        // Connect to the host
        client.Connect(IPAddress.Parse(host), port);

        client.Close();
    }
    catch (SocketException ex)
    {
        // Get the error message
        string errorMessage = ex.Message;
        DevUtils.LogErrorMessage(errorMessage);
    }
}

回答by zumalifeguard

If you just want to give a starting port, and let it return to you the next TCP port available, use code like this:

如果您只想提供一个起始端口，并让它返回给您下一个可用的 TCP 端口，请使用如下代码：

public static int GetAvailablePort(int startingPort)
{
    var portArray = new List<int>();

    var properties = IPGlobalProperties.GetIPGlobalProperties();

    // Ignore active connections
    var connections = properties.GetActiveTcpConnections();
    portArray.AddRange(from n in connections
                        where n.LocalEndPoint.Port >= startingPort
                        select n.LocalEndPoint.Port);

    // Ignore active tcp listners
    var endPoints = properties.GetActiveTcpListeners();
    portArray.AddRange(from n in endPoints
                        where n.Port >= startingPort
                        select n.Port);

    // Ignore active UDP listeners
    endPoints = properties.GetActiveUdpListeners();
    portArray.AddRange(from n in endPoints
                        where n.Port >= startingPort
                        select n.Port);

    portArray.Sort();

    for (var i = startingPort; i < UInt16.MaxValue; i++)
        if (!portArray.Contains(i))
            return i;

    return 0;
}

回答by Eric Boumendil

It's a solution comparable to the accepted answer of TheSeeker. Though I think it's more readable:

这是一个与 TheSeeker 接受的答案相当的解决方案。虽然我认为它更具可读性：

using System;
using System.Net;
using System.Net.Sockets;

    private static readonly IPEndPoint DefaultLoopbackEndpoint = new IPEndPoint(IPAddress.Loopback, port: 0);

    public static int GetAvailablePort()
    {
        using (var socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp))
        {
            socket.Bind(DefaultLoopbackEndpoint);
            return ((IPEndPoint)socket.LocalEndPoint).Port;
        }
    }

回答by Daniel Rosenberg

Here's a more abbreviated way to implement this if you want to find the next available TCP port within a given range:

如果您想在给定范围内找到下一个可用的 TCP 端口，这里有一种更简洁的实现方式：

private int GetNextUnusedPort(int min, int max)
{
    if (max < min)
        throw new ArgumentException("Max cannot be less than min.");

    var ipProperties = IPGlobalProperties.GetIPGlobalProperties();

    var usedPorts =
        ipProperties.GetActiveTcpConnections()
            .Where(connection => connection.State != TcpState.Closed)
            .Select(connection => connection.LocalEndPoint)
            .Concat(ipProperties.GetActiveTcpListeners())
            .Concat(ipProperties.GetActiveUdpListeners())
            .Select(endpoint => endpoint.Port)
            .ToArray();

    var firstUnused =
        Enumerable.Range(min, max - min)
            .Where(port => !usedPorts.Contains(port))
            .Select(port => new int?(port))
            .FirstOrDefault();

    if (!firstUnused.HasValue)
        throw new Exception($"All local TCP ports between {min} and {max} are currently in use.");

    return firstUnused.Value;
}

回答by Fatih TAN

I found the following code from Selenium.WebDriver DLL

我从Selenium.WebDriver DLL 中找到了以下代码

Namespace: OpenQA.Selenium.Internal

命名空间：OpenQA.Selenium.Internal

Class: PortUtility

类: PortUtility

public static int FindFreePort()
{
    int port = 0;
    Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
    try
    {
        IPEndPoint localEP = new IPEndPoint(IPAddress.Any, 0);
        socket.Bind(localEP);
        localEP = (IPEndPoint)socket.LocalEndPoint;
        port = localEP.Port;
    }
    finally
    {
        socket.Close();
    }
    return port;
}