check-rbl.go

package main

import (
	"fmt"
	"net"
	"os"
	"strings"
)

/*
## https://goplay.tools/snippet/37-MxfGC4Mp
## https://socketloop.com/tutorials/golang-reverse-ip-address-for-reverse-dns-lookup-example
Para Compilar voce precisa instalar Golang 1.20
go build -ldflags="-s -w" check-rbl.go
Como usar
./check-rbl dnsbl.spfbl.net 104.219.19.88
*/

func ReverseIPAddress(ip net.IP) string {

	if ip.To4() != nil {
		// split into slice by dot .
		addressSlice := strings.Split(ip.String(), ".")
		reverseSlice := []string{}

		for i := range addressSlice {
			octet := addressSlice[len(addressSlice)-1-i]
			reverseSlice = append(reverseSlice, octet)
		}
		return strings.Join(reverseSlice, ".")

	} else {
		println("Invalid IPv4 Address")
		return "1.0.0.127"
	}
}

func main() {

	if len(os.Args) < 3 {
		fmt.Printf("\nUsage:\n\t%s rbl ipaddress\n", os.Args[0])
		fmt.Printf("\t%s dnsbl.spfbl.net 74.63.210.183\n\n", os.Args[0])
		os.Exit(1)
	}

	if len(os.Args) > 2 {
		ipAddress := net.ParseIP(os.Args[2])
		reverseIpAddress := ReverseIPAddress(ipAddress)
		reverseIpAddress = fmt.Sprintf("%s.%s", reverseIpAddress, os.Args[1])

		//fmt.Println("Before:", ipAddress.To4())
		//fmt.Println("After:", reverseIpAddress)

		//ip, err := net.LookupHost(reverseIpAddress)
		ip, err := net.ResolveIPAddr("ip", reverseIpAddress)

		if err != nil {
			fmt.Print("unlisted:")
			os.Exit(0)
		}

		fmt.Print("listed:", ip.String())
		os.Exit(1)
	}

	os.Exit(0)
}