golang 扫描文本文件Go

Posted 2021-05-24

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f, err := os.Open("salary.txt")
if err != nil {
	log.Fatal(err)
}
defer f.Close()

var xs []float64
scan := bufio.NewScanner(f)
for scan.Scan() {
	var v float64
	txt := scan.Text()
	_, err := fmt.Sscanf(txt, "%f", &v)
	if err != nil {
		log.Fatalf("could not convert to float64 %q: %v", txt, err)
	}
	xs = append(xs, v)
}

// make sure scanning the file and extracting values
// went fine without any error
if err = scan.Err(); err != nil {
	log.Fatalf("error scanning file: %v", err)
}

端口扫描(go)

golang学习

通过golang打造高效的端口扫描器

golang源码如下

package main

import (
    "flag"
    "fmt"
    "net"
    "os"
    "regexp"
    "strconv"
    "strings"
    "sync"
)

var port string
var portRange string
var parallelCounts int

func init() {

    flag.StringVar(&port, "p", "21,22,23,53,80,135,139,443,445,1080,1433,1521,2222,3000,3306,3389,8080,8888,50050,55553","port")
    flag.StringVar(&portRange, "r", "", "range ports. format is <from>-<to>. eg. 100-200")
    flag.IntVar(&parallelCounts, "s", 100, "speed")
    flag.Usage = func() {
        fmt.Fprintf(os.Stderr, "\\nUsage: [Options] <IP>\\n\\neg: ./portscan -r 1-65535 -s 10000 127.0.0.1\\n\\nOptions:\\n\\n")
        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()

    } else{

        //fmt.Println("port " + strconv.Itoa(port) + " is close")
    }
    <-*parallelChan

}

func main() {


    args := flag.Args()

    if len(args) != 1 {
        flag.Usage()
    } else {

        ip := net.ParseIP(flag.Arg(0))

        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)

                    parallelChan := make(chan int, parallelCounts)

                    for i := startPort; i <= endPort; i++ {

                        parallelChan <- 1

                        go checkPort(ip, i, &wg, &parallelChan)

                    }

                    wg.Wait()

                }

            }

        } else {
            parallelChan := make(chan int, parallelCounts)
            arr:=strings.Split(port,",")
            wg.Add(len(arr))
            for i :=0 ; i < len(arr); i++ {
                p,err:=strconv.Atoi(arr[i])
                if err == nil {
                    parallelChan <- 1
                    go checkPort(ip, p, &wg, &parallelChan)
                }
            }
            wg.Wait()

        }

    }

}