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Finally finished writing part of the wheel: tcp proxy, record it

Popularity：483 ℃/2025-03-08 16:28:03

After 24 years of life, I set up a flag myself: I made some wheels to play in 25 years (used to waste my life and I can’t make money)
So I have been planning to write a network agent in C# for 25 yearsNZOrz(nginx knows it, that thing does that thing), including udp/tcp/http1 2 3,
As for why I don’t need to write rust, it is mainly because some uninformative reasons of a certain computer are not convenient to install rust. So I will talk about it when I finish writing C# and have time later (it should be 25 years old)

Source of code reference

Adhering to the spirit of creating wheels that wastes life to the end, if you don’t have the strength, you can learn from it as much as possible (How can you say plagiarism, scholars?)
So here is the first to list the sources of reference

  1. BorrowingKestrelThe socket processing core (theoretically, it is also feasible based on Kestrel)
  2. BorrowingYarpAll proxy processing (implementing only http)

Therefore, the overall implementation is the socket upper layer for multi-threading processing, and does not write code that interacts with the system kernel or deals with other io event libraries.
(Why? If you want to deal with cross-platform, I might as well write Linux directly with rust. Whether it is written in window or not depends on your mood. Anyway, the server is the kingly way, is it?)

Limited

I have to mention a limitation first. Dotnet's socket does not provide a unified cross-process socket transfer API, because dotnet is cross-platform and has differences between different systems. This issueMigrate Socket between processesNothing has been going on for many years

So it's not easy to restart

Preliminary completion progress

Yes, at present, the basic tcp part has been completed (the proxy protocol does not support it, after all, there is so much, and time is limited). The next step is to udp as the priority (document? Let me finish it first)

tcp proxy usage

Currently, no ready-made packaged exe or docker images are provided, after all, there is still a long way to go before completion
If you want to play, you can do this

Create a Console project with net8.0 or net9.0
Install package

dotnet add package  --version 0.0.0.2-beta

Entry Code

using ;
using ;
using ;
using .L4;

var app = (args)
    .UseJsonConfig()
    .Build();

await ();

Configuration File

{
  "Logging": {
    "LogLevel": {
      "Default": "Information"
    }
  },
  "ReverseProxy": {
    "Routes": {
      "apidemo": {
        "Protocols": "TCP",
        "Match": {
          "Hosts": [ "*:5000" ]
        },
        "ClusterId": "apidemo",
        "RetryCount": 1,
        "Timeout": "00:00:11"
      }
    },
    "Clusters": {
      "apidemo": {
        "LoadBalancingPolicy": "RoundRobin",
        "HealthCheck": {
          "Active": {
            "Enable": false,
            "Policy": "Connect"
          }
        },
        "Destinations": [
          {
            "Address": "[::1]:5144"
          },
          {
            "Address": "[::1]:5146"
          },
          {
            "Address": ":998"
          },
          {
            "Address": ""
          },
          {
            "Address": ""
          },
          {
            "Address": ""
          }
        ]
      }
    }
  }
}

Then start the log as follows

info: [18]
      Config changed. Starting the following endpoints: [Protocols: TCP,Route: apidemo,EndPoint: 0.0.0.0:5000],[Protocols: TCP,Route: apidemo,EndPoint: [::]:5000]
info: [0]
      Application started. Press Ctrl+C to shut down.
info: [0]
      Hosting environment: Production
info: [0]
      Content root path: D:\code\edge\l4proxy\src\L4Proxy\bin\Debug\net8.0

Of course, if it is changedContent, re-listen to the changed port/rebuild the routing table, etc. according to the configuration

It can also make up for the problem of not being able to restart hot

Change the data of tcp

If you want to change the data of tcp, you can implement middlewareITcpMiddleware

for example

public class EchoMiddleware : ITcpMiddleware
{
    public int Order => 0;

    public Task<ReadOnlyMemory<byte>> OnRequest(ConnectionContext connection, ReadOnlyMemory<byte> source, CancellationToken cancellationToken, TcpConnectionDelegate next)
    {
        ($"{} {()} request size: {}");
        return (source);
    }

    public Task<ReadOnlyMemory<byte>> OnResponse(ConnectionContext connection, ReadOnlyMemory<byte> source, CancellationToken cancellationToken, TcpConnectionDelegate next)
    {
        ($"{} {()} reponse size: {}");
        //source = Encoding.("HTTP/1.1 400 Bad Request\r\nDate: Sun, 18 Oct 2012 10:36:20 GMT\r\nServer: Apache/2.2.14 (Win32)\r\nContent-Length: 0\r\nContent-Type: text/html; charset=iso-8859-1\r\nConnection: Closed\r\n\r\n").AsMemory();
        //();
        return (source);
    }
}

Then inject ioc

var app = (args)
    .ConfigServices(services =>
    {
        <ITcpMiddleware, EchoMiddleware>();
    })
    .UseJsonConfig()
    .Build();

Simple configuration instructions

Let's write the document in detail

Protocols SupportTCP

Hosts supports suffix matching, for example, you can write by matching all instances port 5000.*:5000, matching an instance of 192.1.1.1, port 3000 can be written192.1.1.1:3000
(The routing table implementation uses prefix tree + dictionary +SIEVE cahce）

Service discovery currently only supports DNS, but does not support specifying dns server, becausednsNo support, let's talk about it later

HealthCheck supports active passive. Choose one of two, do not support use together, active. Only socket connect is supported for the time being. Successful checking.

LoadBalancingPolicy supports four typesRandom , RoundRobin , LeastRequests , PowerOfTwoChoices

Just like that, wait for me to realize the rest

If you have time, can you go to GitHub/fs7744/NZOrzClick a star? After all, it is not easy to borrow code, hahahahaha

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