前话

最近痴迷于Golang这个新兴语言，因为它是强类型编译型语言，可以直接编译成三大平台的二进制执行文件，可以直接运行无需其他依赖环境。而且Golang独特的goroutine使得多线程任务执行如new一个对象般简单。

带着为学习理解Golang的好奇心情，我试着写了个端口扫描器。

github项目链接如下， 更多的实用工具我会慢慢添加。

https://github.com/pwcong/go-tools

源码

package mainimport (
"flag"
"fmt"
"net"
"os"
"regexp"
"strconv"
"strings"
"sync"
)var port int
var portRange stringvar parallelCounts intfunc init() {flag.IntVar(&port, "p", 80, "port")
flag.StringVar(&portRange, "r", "", "range ports. format is <from>~<to>. eg. 100~200")
flag.IntVar(&parallelCounts, "n", 1, "parallel counts")// 修改提示信息
flag.Usage = func() {
fmt.Fprintf(os.Stderr, "\nUsage: %s [Options] <IP>\n\nOptions:\n\n", os.Args[0])
flag.PrintDefaults()
}flag.Parse()}func printOpeningPort(port int) {fmt.Println("port " + strconv.Itoa(port) + " is opening")}func checkPort(ip net.IP, port int, wg *sync.WaitGroup, parallelChan *chan int) {defer wg.Done()tcpAddr := net.TCPAddr{
IP:   ip,
Port: port,
}conn, err := net.DialTCP("tcp", nil, &tcpAddr)if err == nil {
printOpeningPort(port)
conn.Close()}<-*parallelChan}func main() {args := flag.Args()if len(args) != 1 {
flag.Usage()
} else {ip := net.ParseIP(flag.Arg(0))// 用于协程任务控制
wg := sync.WaitGroup{}if portRange != "" {matched, _ := regexp.Match(`^\d+~\d+$`, []byte(portRange))if !matched {flag.Usage()} else {portSecs := strings.Split(portRange, "~")startPort, err1 := strconv.Atoi(portSecs[0])
endPort, err2 := strconv.Atoi(portSecs[1])if err1 != nil || err2 != nil || startPort < 1 || endPort < 2 || endPort <= startPort || parallelCounts < 1 {
flag.Usage()
} else {wg.Add(endPort - startPort + 1)// 用于控制协程数
parallelChan := make(chan int, parallelCounts)for i := startPort; i <= endPort; i++ {parallelChan <- 1go checkPort(ip, i, &wg, &parallelChan)}wg.Wait()}}} else {wg.Add(1)parallelChan := make(chan int)go func() {
parallelChan <- 1
}()go checkPort(ip, port, &wg, &parallelChan)wg.Wait()}}}

运行结果

1. 执行 go build ./main.go， 生成二进制文件
2. 运行二进制文件，结果如下：

   $ port-scanner.exeUsage: E:\Program Files\GoPath\bin\port-scanner.exe [Options] <IP>Options:  -n int
           parallel counts (default 1)
     -p int
           port (default 80)
     -r string
           range ports. format is <from>~<to>. eg. 100~200$ port-scanner.exe -p 80 127.0.0.1
   port 80 is opening$ port-scanner.exe -r 1~100 -n 50 127.0.0.1
   port 80 is opening