测试需要，以前用 C + libevent 写了一个 TCP Echo Server，返回服务器时间、客户端地址信息和客户端发送的原内容。为了水一篇，现在改为 golang 实现。

package main

import (
	"fmt"
	"io"
	"net"
	"os"
	"time"
)

const BUFFER_SIZE = 1024 * 4

var buffer = make([]byte,BUFFER_SIZE)

func handleConnect(tcpConn *net.TCPConn) {
	if tcpConn == nil {
		return
	}
	for {
		n,err := tcpConn.Read(buffer)
		if err == io.EOF {
			fmt.Printf("The RemoteAddr: %s is closed!\n",tcpConn.RemoteAddr().String())
			return
		}
		handleError(err)
		if n > 0 {
			//fmt.Printf("Read: %s",string(buffer[:n]))
			str := tcpConn.RemoteAddr().String() + " @ " +
				time.Now().Format("2006-01-02 15:04:05 Z07:00") + "\r\n" +
				string(buffer[:n])
			tcpConn.Write([]byte(str))
			fmt.Printf("Echo: %s",str)
		}
	}
}

// 错误处理
func handleError(err error) {
	if err == nil {
		return
	}
	panic(err)
	//fmt.Printf("error: %s\n",err.Error())
}

func main() {
	if len(os.Args) < 2 {
		fmt.Println("Usage:",os.Args[0],"<port>")
		return
	}
	port := os.Args[1]
	tcpAddr,err := net.ResolveTCPAddr("tcp4","0.0.0.0:"+port)
	handleError(err)
	tcpListener,err := net.ListenTCP("tcp4",tcpAddr)
	handleError(err)
	defer tcpListener.Close()

	fmt.Println("Listening on",tcpAddr,"...")
	for {
		tcpConn,err := tcpListener.AcceptTCP()
		fmt.Printf("The client: %s has connected!\n",tcpConn.RemoteAddr().String())
		handleError(err)
		defer tcpConn.Close()
		go handleConnect(tcpConn)
	}
}