golang流量转发

package main

import (
    "fmt"
    "net"
    "os"
    "sync"
)

func forward(inputAddr string, outputAddr string) {
    inputConn, err := net.Listen("tcp", inputAddr)
    if err != nil {
        fmt.Println("Error listening: ", err.Error())
        os.Exit(1)
    }
    defer inputConn.Close()

    for {
        clientConn, err := inputConn.Accept()
        if err != nil {
            fmt.Println("Error accepting: ", err.Error())
        } else {
            go handleClient(clientConn, outputAddr)
        }
    }
}

func handleClient(client net.Conn, outputAddr string) {
    defer client.Close()
    server, err := net.Dial("tcp", outputAddr)
    if err != nil {
        fmt.Println("Error connecting: ", err.Error())
        return
    }
    defer server.Close()

    var wg sync.WaitGroup
    wg.Add(2)

    go func() {
        defer wg.Done()
        copyData(client, server)
    }()

    go func() {
        defer wg.Done()
        copyData(server, client)
    }()

    wg.Wait()
}

func copyData(src net.Conn, dst net.Conn) {
    defer src.Close()
    defer dst.Close()

    buf := make([]byte, 1024)

    for {
        n, err := src.Read(buf)
        if err != nil {
            fmt.Println("Error reading: ", err.Error())
            return
        }
        _, err = dst.Write(buf[:n])
        if err != nil {
            fmt.Println("Error writing: ", err.Error())
            return
        }
    }
}

func main() {
    inputAddr := "127.0.0.1:8080"
    outputAddr := "127.0.0.1:8888"
    forward(inputAddr, outputAddr)
}