您可知道如何通过`HTTP2`实现TCP的内网穿透？？？

可能有人很疑惑应用层转发传输层？，为什么会有这样的需求啊？？？哈哈技术无所不用其极，由于一些场景下，对于一个服务器存在某一个内部网站中，但是对于这个服务器它没有访问外网的权限，虽然也可以申请端口访问外部指定的ip+端口，但是对于访问服务内部的TCP的时候我们就会发现忘记申请了！这个时候我们又要提交申请，又要等审批，然后开通端口，对于这个步骤不是一般的麻烦，所以我在想是否可以直接利用现有的Http网关的端口进行转发内部的TCP服务？这个时候我询问了我们的老九大佬，由于我之前也做过通过H2实现HTTP内网穿透，可以利用H2将内部网络中的服务映射出来，但是由于底层是基于yarp的一些方法实现，所以并没有考虑过TCP，然后于老九大佬交流深究，决定尝试验证可行性，然后我们的Taibai项目就诞生了，为什么叫Taibai？您仔细看看这个拼音，翻译过来就是太白，确实全称应该叫太白金星，寓意上天遁地无所不能！下面我们介绍一下具体实现逻辑，确实您仔细看会发现实现是真的超级简单的！

创建Core项目用于共用的核心类库

创建项目名Taibai.Core

下面几个方法都是用于操作Stream的类

DelegatingStream.cs

namespace Taibai.Core;/// <summary>
/// 委托流
/// </summary>
public abstract class DelegatingStream : Stream
{/// <summary>/// 获取所包装的流对象/// </summary>protected readonly Stream Inner;/// <summary>/// 委托流/// </summary>/// <param name="inner"></param>public DelegatingStream(Stream inner){this.Inner = inner;}/// <inheritdoc/>public override bool CanRead => Inner.CanRead;/// <inheritdoc/>public override bool CanSeek => Inner.CanSeek;/// <inheritdoc/>public override bool CanWrite => Inner.CanWrite;/// <inheritdoc/>public override long Length => Inner.Length;/// <inheritdoc/>public override bool CanTimeout => Inner.CanTimeout;/// <inheritdoc/>public override int ReadTimeout{get => Inner.ReadTimeout;set => Inner.ReadTimeout = value;}/// <inheritdoc/>public override int WriteTimeout{get => Inner.WriteTimeout;set => Inner.WriteTimeout = value;}/// <inheritdoc/>public override long Position{get => Inner.Position;set => Inner.Position = value;}/// <inheritdoc/>public override void Flush(){Inner.Flush();}/// <inheritdoc/>public override Task FlushAsync(CancellationToken cancellationToken){return Inner.FlushAsync(cancellationToken);}/// <inheritdoc/>public override int Read(byte[] buffer, int offset, int count){return Inner.Read(buffer, offset, count);}/// <inheritdoc/>public override int Read(Span<byte> destination){return Inner.Read(destination);}/// <inheritdoc/>public override Task<int> ReadAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken){return Inner.ReadAsync(buffer, offset, count, cancellationToken);}/// <inheritdoc/>public override ValueTask<int> ReadAsync(Memory<byte> destination, CancellationToken cancellationToken = default){return Inner.ReadAsync(destination, cancellationToken);}/// <inheritdoc/>public override long Seek(long offset, SeekOrigin origin){return Inner.Seek(offset, origin);}/// <inheritdoc/>public override void SetLength(long value){Inner.SetLength(value);}/// <inheritdoc/>public override void Write(byte[] buffer, int offset, int count){Inner.Write(buffer, offset, count);}/// <inheritdoc/>public override void Write(ReadOnlySpan<byte> source){Inner.Write(source);}/// <inheritdoc/>public override Task WriteAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken){return Inner.WriteAsync(buffer, offset, count, cancellationToken);}/// <inheritdoc/>public override ValueTask WriteAsync(ReadOnlyMemory<byte> source, CancellationToken cancellationToken = default){return Inner.WriteAsync(source, cancellationToken);}/// <inheritdoc/>public override IAsyncResult BeginRead(byte[] buffer, int offset, int count, AsyncCallback? callback, object? state){return TaskToAsyncResult.Begin(ReadAsync(buffer, offset, count), callback, state);}/// <inheritdoc/>public override int EndRead(IAsyncResult asyncResult){return TaskToAsyncResult.End<int>(asyncResult);}/// <inheritdoc/>public override IAsyncResult BeginWrite(byte[] buffer, int offset, int count, AsyncCallback? callback,object? state){return TaskToAsyncResult.Begin(WriteAsync(buffer, offset, count), callback, state);}/// <inheritdoc/>public override void EndWrite(IAsyncResult asyncResult){TaskToAsyncResult.End(asyncResult);}/// <inheritdoc/>public override int ReadByte(){return Inner.ReadByte();}/// <inheritdoc/>public override void WriteByte(byte value){Inner.WriteByte(value);}/// <inheritdoc/>public sealed override void Close(){base.Close();}
}

SafeWriteStream.cs

public class SafeWriteStream(Stream inner) : DelegatingStream(inner)
{private readonly SemaphoreSlim semaphoreSlim = new(1, 1);public override async ValueTask WriteAsync(ReadOnlyMemory<byte> source, CancellationToken cancellationToken = default){try{await this.semaphoreSlim.WaitAsync(CancellationToken.None);await base.WriteAsync(source, cancellationToken);await this.FlushAsync(cancellationToken);}finally{this.semaphoreSlim.Release();}}public override ValueTask DisposeAsync(){this.semaphoreSlim.Dispose();return this.Inner.DisposeAsync();}protected override void Dispose(bool disposing){this.semaphoreSlim.Dispose();this.Inner.Dispose();}
}

创建服务端

创建一个WebAPI的项目项目名Taibai.Server并且依赖Taibai.Core项目

创建ServerService.cs，这个类是用于管理内网的客户端的，这个一般是部署在内网服务器上，用于将内网的端口映射出来，但是我们的Demo只实现了简单的管理不做端口的管理。

using System.Collections.Concurrent;
using Microsoft.AspNetCore.Http.Features;
using Microsoft.AspNetCore.Http.Timeouts;
using Taibai.Core;namespace Taibai.Server;public static class ServerService
{private static readonly ConcurrentDictionary<string, (CancellationToken, Stream)> ClusterConnections = new();public static async Task StartAsync(HttpContext context){// 如果不是http2协议，我们不处理, 因为我们只支持http2if (context.Request.Protocol != HttpProtocol.Http2){return;}// 获取queryvar query = context.Request.Query;// 我们需要强制要求name参数var name = query["name"];if (string.IsNullOrEmpty(name)){context.Response.StatusCode = 400;Console.WriteLine("Name is required");return;}Console.WriteLine("Accepted connection from " + name);// 获取http2特性var http2Feature = context.Features.Get<IHttpExtendedConnectFeature>();// 禁用超时context.Features.Get<IHttpRequestTimeoutFeature>()?.DisableTimeout();// 得到双工流var stream = new SafeWriteStream(await http2Feature.AcceptAsync());// 将其添加到集合中，以便我们可以在其他地方使用CreateConnectionChannel(name, context.RequestAborted, stream);// 注册取消连接context.RequestAborted.Register(() =>{// 当取消时，我们需要从集合中删除ClusterConnections.TryRemove(name, out _);});// 由于我们需要保持连接，所以我们需要等待，直到客户端主动断开连接。await Task.Delay(-1, context.RequestAborted);}/// <summary>/// 通过名称获取连接/// </summary>/// <param name="host"></param>/// <returns></returns>public static (CancellationToken, Stream) GetConnectionChannel(string host){return ClusterConnections[host];}/// <summary>/// 注册连接/// </summary>/// <param name="host"></param>/// <param name="cancellationToken"></param>/// <param name="stream"></param>public static void CreateConnectionChannel(string host, CancellationToken cancellationToken, Stream stream){ClusterConnections.GetOrAdd(host,_ => (cancellationToken, stream));}
}

然后再创建ClientMiddleware.cs，并且继承IMiddleware，这个是我们本地使用的客户端链接的时候进入的中间件，再这个中间件会获取query中携带的name去找到指定的Stream，然后会将客户端的Stream和获取的server的Stream进行Copy，在这里他们会将读取的数据写入到对方的流中，这样就实现了双工通信

using Microsoft.AspNetCore.Http.Features;
using Microsoft.AspNetCore.Http.Timeouts;
using Taibai.Core;namespace Taibai.Server;public class ClientMiddleware : IMiddleware
{public async Task InvokeAsync(HttpContext context, RequestDelegate next){// 如果不是http2协议，我们不处理, 因为我们只支持http2if (context.Request.Protocol != HttpProtocol.Http2){return;}var name = context.Request.Query["name"];if (string.IsNullOrEmpty(name)){context.Response.StatusCode = 400;Console.WriteLine("Name is required");return;}Console.WriteLine("Accepted connection from " + name);var http2Feature = context.Features.Get<IHttpExtendedConnectFeature>();context.Features.Get<IHttpRequestTimeoutFeature>()?.DisableTimeout();// 得到双工流var stream = new SafeWriteStream(await http2Feature.AcceptAsync());// 通过name找到指定的server链接，然后进行转发。var (cancellationToken, reader) = ServerService.GetConnectionChannel(name);try{// 注册取消连接cancellationToken.Register(() =>{Console.WriteLine("断开连接");stream.Close();});// 得到客户端的流，然后给我们的SafeWriteStream,然后我们就可以进行转发了var socketStream = new SafeWriteStream(reader);// 在这里他们会将读取的数据写入到对方的流中，这样就实现了双工通信，这个非常简单并且性能也不错。await Task.WhenAll(stream.CopyToAsync(socketStream, context.RequestAborted),socketStream.CopyToAsync(stream, context.RequestAborted));}catch (Exception e){Console.WriteLine("断开连接" + e.Message);throw;}}
}

打开Program.cs

using Taibai.Server;var builder = WebApplication.CreateBuilder(new WebApplicationOptions());builder.Host.ConfigureHostOptions(host => { host.ShutdownTimeout = TimeSpan.FromSeconds(1d); });builder.Services.AddSingleton<ClientMiddleware>();var app = builder.Build();app.Map("/server", app =>
{app.Use(Middleware);static async Task Middleware(HttpContext context, RequestDelegate _){await ServerService.StartAsync(context);}
});app.Map("/client", app => { app.UseMiddleware<ClientMiddleware>(); });app.Run();

在这里我们将server的所有路由都交过ServerService.StartAsync接管，再server会请求这个地址，

而/client则给了ClientMiddleware中间件。

创建客户端

上面我们实现了服务端，其实服务端可以完全放置到现有的WebApi项目当中的，而且代码也不是很多。

客户端我们创建一个控制台项目名：Taibai.Client，并且依赖Taibai.Core项目

由于我们的客户端有些特殊，再server中部署的它不需要监听端口，它只需要将服务器的数据转发到指定的一个地址即可，所以我们需要将客户端的server部署的和本地部署的分开实现，再服务器部署的客户端我们命名为MonitorClient.cs

ClientOption.cs用于传递我们的客户端地址配置

public class ClientOption
{/// <summary>/// 服务地址/// </summary>public string ServiceUri { get; set; }}

MonitorClient.cs，作为服务器的转发客户端。

using System.Net;
using System.Net.Security;
using System.Net.Sockets;
using Taibai.Core;namespace Taibai.Client;public class MonitorClient(ClientOption option)
{private string Protocol = "taibai";private readonly HttpMessageInvoker httpClient = new(CreateDefaultHttpHandler(), true);private readonly Socket socket = new(SocketType.Stream, ProtocolType.Tcp);private static SocketsHttpHandler CreateDefaultHttpHandler(){return new SocketsHttpHandler{// 允许多个http2连接EnableMultipleHttp2Connections = true,// 设置连接超时时间ConnectTimeout = TimeSpan.FromSeconds(60),SslOptions = new SslClientAuthenticationOptions{// 由于我们没有证书，所以我们需要设置为trueRemoteCertificateValidationCallback = (_, _, _, _) => true,},};}public async Task TransportAsync(CancellationToken cancellationToken){Console.WriteLine("链接中！");// 由于是测试，我们就目前先写死远程地址await socket.ConnectAsync(new IPEndPoint(IPAddress.Parse("192.168.31.250"), 3389), cancellationToken);Console.WriteLine("连接成功");// 将Socket转换为流var stream = new NetworkStream(socket);try{// 创建服务器的连接，然后返回一个流，这个是H2的流var serverStream = await this.CreateServerConnectionAsync(cancellationToken);Console.WriteLine("链接服务器成功");// 将两个流连接起来，这样我们就可以进行双工通信了。它们会自动进行数据的传输。await Task.WhenAll(stream.CopyToAsync(serverStream, cancellationToken),serverStream.CopyToAsync(stream, cancellationToken));}catch (Exception ex){Console.WriteLine(ex.Message);throw;}}/// <summary>/// 创建服务器的连接/// </summary> /// <param name="cancellationToken"></param>/// <exception cref="OperationCanceledException"></exception>/// <returns></returns>public async Task<SafeWriteStream> CreateServerConnectionAsync(CancellationToken cancellationToken){var stream = await Http20ConnectServerAsync(cancellationToken);return new SafeWriteStream(stream);}/// <summary>/// 创建http2连接/// </summary>/// <param name="cancellationToken"></param>/// <returns></returns>private async Task<Stream> Http20ConnectServerAsync(CancellationToken cancellationToken){var serverUri = new Uri(option.ServiceUri);// 这里我们使用Connect方法，因为我们需要建立一个双工流, 这样我们就可以进行双工通信了。var request = new HttpRequestMessage(HttpMethod.Connect, serverUri);// 如果设置了Connect，那么我们需要设置Protocolrequest.Headers.Protocol = Protocol;// 我们需要设置http2的版本request.Version = HttpVersion.Version20;// 我们需要确保我们的请求是http2的request.VersionPolicy = HttpVersionPolicy.RequestVersionExact;// 设置一下超时时间，这样我们就可以在超时的时候取消连接了。using var timeoutTokenSource = new CancellationTokenSource(TimeSpan.FromSeconds(60));using var linkedTokenSource =CancellationTokenSource.CreateLinkedTokenSource(timeoutTokenSource.Token, cancellationToken);// 发送请求，然后等待响应var httpResponse = await this.httpClient.SendAsync(request, linkedTokenSource.Token);// 返回h2的流，用于传输数据return await httpResponse.Content.ReadAsStreamAsync(linkedTokenSource.Token);}
}

创建我们的本地客户端实现类。

Client.cs这个就是在我们本地部署的服务，然后会监听本地的60112的端口，然后会吧这个端口的数据转发到我们的服务器，然后服务器会根据我们使用的name去找到指定的客户端进行交互传输。

using System.Net;
using System.Net.Security;
using System.Net.Sockets;
using Taibai.Core;
using HttpMethod = System.Net.Http.HttpMethod;namespace Taibai.Client;public class Client
{private readonly ClientOption option;private string Protocol = "taibai";private readonly HttpMessageInvoker httpClient;private readonly Socket socket;public Client(ClientOption option){this.option = option;this.httpClient = new HttpMessageInvoker(CreateDefaultHttpHandler(), true);this.socket = new Socket(SocketType.Stream, ProtocolType.Tcp);// 监听本地端口this.socket.Bind(new IPEndPoint(IPAddress.Loopback, 60112));this.socket.Listen(10);}private static SocketsHttpHandler CreateDefaultHttpHandler(){return new SocketsHttpHandler{// 允许多个http2连接EnableMultipleHttp2Connections = true,ConnectTimeout = TimeSpan.FromSeconds(60),ResponseDrainTimeout = TimeSpan.FromSeconds(60),  SslOptions = new SslClientAuthenticationOptions{// 由于我们没有证书，所以我们需要设置为trueRemoteCertificateValidationCallback = (sender, certificate, chain, sslPolicyErrors) => true,},};}public async Task TransportAsync(CancellationToken cancellationToken){Console.WriteLine("Listening on 60112");// 等待客户端连接var client = await this.socket.AcceptAsync(cancellationToken);Console.WriteLine("Accepted connection from " + client.RemoteEndPoint);try{// 将Socket转换为流var stream = new NetworkStream(client);// 创建服务器的连接,然后返回一个流, 这个是H2的流var serverStream = await this.CreateServerConnectionAsync(cancellationToken);Console.WriteLine("Connected to server");// 将两个流连接起来, 这样我们就可以进行双工通信了. 它们会自动进行数据的传输.await Task.WhenAll(stream.CopyToAsync(serverStream, cancellationToken),serverStream.CopyToAsync(stream, cancellationToken));}catch (Exception e){Console.WriteLine(e);throw;}}/// <summary>/// 创建与服务器的连接/// </summary> /// <param name="cancellationToken"></param>/// <exception cref="OperationCanceledException"></exception>/// <returns></returns>public async Task<SafeWriteStream> CreateServerConnectionAsync(CancellationToken cancellationToken){var stream = await this.Http20ConnectServerAsync(cancellationToken);return new SafeWriteStream(stream);}private async Task<Stream> Http20ConnectServerAsync(CancellationToken cancellationToken){var serverUri = new Uri(option.ServiceUri);// 这里我们使用Connect方法, 因为我们需要建立一个双工流var request = new HttpRequestMessage(HttpMethod.Connect, serverUri);// 由于我们设置了Connect方法, 所以我们需要设置协议，这样服务器才能识别request.Headers.Protocol = Protocol;// 设置http2版本request.Version = HttpVersion.Version20;// 强制使用http2request.VersionPolicy = HttpVersionPolicy.RequestVersionExact;using var timeoutTokenSource = new CancellationTokenSource(TimeSpan.FromSeconds(60));using var linkedTokenSource =CancellationTokenSource.CreateLinkedTokenSource(timeoutTokenSource.Token, cancellationToken);// 发送请求，等待服务器验证。var httpResponse = await this.httpClient.SendAsync(request, linkedTokenSource.Token);// 返回一个流return await httpResponse.Content.ReadAsStreamAsync(linkedTokenSource.Token);}
}

然后再Program.cs中，我们封装一个简单的控制台版本。

using Taibai.Client;const string commandTemplate = @"当前是 Taibai 客户端，输入以下命令：- `help` 显示帮助
- `monitor` 使用监控模式，监听本地端口，将流量转发到服务端的指定地址- `monitor=https://localhost:7153/server?name=test`  监听本地端口，将流量转发到服务端指定的客户端名称为 test 的地址
- `client` 使用客户端模式，连接服务端的指定地址，将流量转发到本地端口- `client=https://localhost:7153/client?name=test`  连接服务端指定当前客户端名称为 test，将流量转发到本地端口
- `exit` 退出输入命令：";while (true)
{Console.WriteLine(commandTemplate);var command = Console.ReadLine();if (command?.StartsWith("monitor=") == true){var client = new MonitorClient(new ClientOption(){ServiceUri = command[8..]});await client.TransportAsync(new CancellationToken());}else if (command?.StartsWith("client=") == true){var client = new Client(new ClientOption(){ServiceUri = command[7..]});await client.TransportAsync(new CancellationToken());}else if (command == "help"){Console.WriteLine(commandTemplate);}else if (command == "exit"){Console.WriteLine("Bye!");break;}else{Console.WriteLine("未知命令");}
}