🚀 Add main function

main.go

@@ -0,0 +1,93 @@
+package main
+
+import (
+	"bufio"
+	"flag"
+	"fmt"
+	"net"
+	"os"
+	"sync"
+)
+
+func main() {
+	concurrency := 20
+	flag.IntVar(&concurrency, "c", 20, "Set the concurrency level")
+	flag.Parse()
+	jobs := make(chan string)
+	var wg sync.WaitGroup
+	for i := 0; i < concurrency; i++ {
+		wg.Add(1)
+		go func() {
+			for host := range jobs {
+				addr, err := net.LookupIP(host)
+				if err != nil {
+					continue
+				}
+				if !isCloudflare(addr[0]) {
+					fmt.Println(addr[0])
+				}
+			}
+			wg.Done()
+		}()
+	}
+
+	sc := bufio.NewScanner(os.Stdin)
+	for sc.Scan() {
+		jobs <- sc.Text()
+	}
+
+	close(jobs)
+
+	if err := sc.Err(); err != nil {
+		fmt.Fprintf(os.Stderr, "failed to read input: %s\n", err)
+	}
+
+	wg.Wait()
+}
+
+func inc(ip net.IP) {
+	for j := len(ip) - 1; j >= 0; j-- {
+		ip[j]++
+		if ip[j] > 0 {
+			break
+		}
+	}
+}
+
+func hosts(cidr string) ([]string, error) {
+	ip, ipnet, err := net.ParseCIDR(cidr)
+	if err != nil {
+		return nil, err
+	}
+
+	var ips []string
+	for ip := ip.Mask(ipnet.Mask); ipnet.Contains(ip); inc(ip) {
+		ips = append(ips, ip.String())
+	}
+
+	lenIPs := len(ips)
+	switch {
+	case lenIPs < 2:
+		return ips, nil
+
+	default:
+		return ips[1 : len(ips)-1], nil
+	}
+}
+
+func isCloudflare(ip net.IP) bool {
+	cidrs := []string{"173.245.48.0/20", "103.21.244.0/22", "103.22.200.0/22", "103.31.4.0/22", "141.101.64.0/18", "108.162.192.0/18", "190.93.240.0/20", "188.114.96.0/20", "197.234.240.0/22", "198.41.128.0/17", "162.158.0.0/15", "104.16.0.0/12", "172.64.0.0/13", "131.0.72.0/22"}
+	for i := range cidrs {
+		hosts, err := hosts(cidrs[i])
+		if err != nil {
+			continue
+		}
+
+		for _, host := range hosts {
+			if host == ip.String() {
+				return true
+			}
+		}
+	}
+	return false
+}