来呀！用golang做个简单的tcpproxy

作为一个中间的tcp代理转发，来不及解释了，快上车！上Code!

数据转发示意图：

package main

import (
    "fmt"
    "log"
    "net"
    //"os"
)

func main() {
    //这里可以传入参数
    //if len(os.Args) != 5 {
    //  log.Fatalf("Usage: %s <source ip> <source port> <destination ip> <destination port>", os.Args[0])
    //}

    //源端口，目的端口
    var fromport, toport int = 8888,43822
    fromaddr := fmt.Sprintf("0.0.0.0:%d",  fromport)
    toaddr := fmt.Sprintf("192.168.3.88:%d", toport)

    fromlistener, err := net.Listen("tcp", fromaddr)

    if err != nil {
        log.Fatal("Unable to listen on: %s, error: %s\n", fromaddr, err.Error())
    }
    defer fromlistener.Close()

    for {
        fromcon, err := fromlistener.Accept()
        if err != nil {
            fmt.Printf("Unable to accept a request, error: %s\n", err.Error())
        } else {
            fmt.Println("new connect:" + fromcon.RemoteAddr().String())
        }

        //这边最好也做个协程，防止阻塞
        toCon, err := net.Dial("tcp", toaddr)
        if err != nil {
            fmt.Printf("can not connect to %s\n", toaddr)
            continue
        }

        go handleConnection(fromcon, toCon)
        go handleConnection(toCon, fromcon)

    }

}

func handleConnection(r, w net.Conn) {
    defer r.Close()
    defer w.Close()

    var buffer = make([]byte, 100000)
    for {
        n, err := r.Read(buffer)
        if err != nil {
            break
        }

        n, err = w.Write(buffer[:n])
        if err != nil {
            break
        }
    }

}

Code跑起来：

使用netstat查看下监听端口:

新开一个cmd窗口，使用telnet探测一下8888端口：

说明代理转发成功，代码短小精悍。