crawl.go

package main

import (
        "flag"
        "io"
        "log"
        "net"
        "os"
        "strings"
        "time"
)

var (
        a, b, c, d int // start ip
        e, f, g, h int // finish ip
)

func init() {
        flag.IntVar(&a, "a", 1, "")
        flag.IntVar(&b, "b", 1, "")
        flag.IntVar(&c, "c", 1, "")
        flag.IntVar(&d, "d", 1, "")

        flag.IntVar(&e, "e", 255, "")
        flag.IntVar(&f, "f", 255, "")
        flag.IntVar(&g, "g", 255, "")
        flag.IntVar(&h, "h", 255, "")

        flag.Parse()
}

func gen(addr chan<- *net.TCPAddr) {
        for {
                for A := a; A < 256; A++ {
                        for B := b; B < 256; B++ {
                                for C := c; C < 256; C++ {
                                        for D := d; D < 256; D++ {
                                                addr <- &net.TCPAddr{IP: net.IP{byte(A), byte(B), byte(C), byte(D)}, Port: 80}
                                        }
                                }
                        }
                }
        }
}

const request = "GET / HTTP/1.0\r\n\r\n"
const timeout = 20 * time.Second

func probe(c <-chan *net.TCPAddr) {
        for addr := range c {
                conn, err := net.DialTimeout("tcp4", addr.String(), 3*time.Second)
                if err != nil {
                        continue
                }
                conn.SetDeadline(time.Now().Add(timeout))
                if _, err := io.Copy(conn, strings.NewReader(request)); err != nil {
                        conn.Close()
                        continue
                }
                f, err := os.Create(addr.String())
                if err != nil {
                        conn.Close()
                        continue
                }
                n, err := io.Copy(f, conn)
                log.Printf("%v: copied %d bytes, err %v", addr.String(), n, err)
                conn.Close()
                f.Close()
                if n == 0 {
                        os.Remove(f.Name())
                }
        }
}

const N = 64

func main() {
        c := make(chan *net.TCPAddr)
        for i := 0; i < N; i++ {
                go probe(c)
        }
        gen(c)
}