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package dnsbl
import (
"encoding/hex"
"fmt"
"net"
"strings"
)
type ResultList struct {
Listed bool
Results []Result
}
/*
Result holds the individual IP lookup results for each RBL search
*/
type Result struct {
// Blacklist is the DNSBL server that gave this result
Blacklist string
// Address is the IP address that was searched
Address string
// Listed indicates whether or not the IP was on the RBL
Listed bool
// RBL lists sometimes add extra information as a TXT record
// if any info is present, it will be stored here.
Text string
// Error represents any error that was encountered (DNS timeout, host not
// found, etc.) if any
Error bool
// ErrorType is the type of error encountered if any
ErrorType error
}
/*
Convert an IP to a hostname ready for a dnsbl lookup
127.0.0.1 becomes 1.0.0.127
1234:1234:1234:1234:1234:1234:1234:1234 becomes 4.3.2.1.4.3.2.1.4.3.2.1.4.3.2.1.4.3.2.1.4.3.2.1.4.3.2.1.4.3.2.1
*/
func toDnsBlHostname(ip net.IP) string {
if ip.To4() != nil {
// IPv4
// Reverse the complete octects
splitAddress := strings.Split(ip.String(), ".")
for i, j := 0, len(splitAddress)-1; i < len(splitAddress)/2; i, j = i+1, j-1 {
splitAddress[i], splitAddress[j] = splitAddress[j], splitAddress[i]
}
return strings.Join(splitAddress, ".")
}
// IPv6
// Remove all : from a full expanded address, then reverse all the hex characters
ipv6Str := expandIPv6(ip)
addrHexStr := strings.ReplaceAll(ipv6Str, ":", "")
chars := []rune(addrHexStr)
for i, j := 0, len(chars)-1; i < j; i, j = i+1, j-1 {
chars[i], chars[j] = chars[j], chars[i]
}
return strings.Join(strings.Split(string(chars), ""), ".")
}
func expandIPv6(ip net.IP) string {
dst := make([]byte, hex.EncodedLen(len(ip)))
_ = hex.Encode(dst, ip)
return string(dst[0:4]) + ":" +
string(dst[4:8]) + ":" +
string(dst[8:12]) + ":" +
string(dst[12:16]) + ":" +
string(dst[16:20]) + ":" +
string(dst[20:24]) + ":" +
string(dst[24:28]) + ":" +
string(dst[28:])
}
func query(rbl string, host string, r *Result) {
r.Listed = false
lookup := fmt.Sprintf("%s.%s", host, rbl)
res, err := net.LookupHost(lookup)
if len(res) > 0 {
r.Listed = true
txt, _ := net.LookupTXT(lookup)
if len(txt) > 0 {
r.Text = txt[0]
}
}
if err != nil {
r.Error = true
r.ErrorType = err
}
return
}
func Lookup(dnsblList []string, targetHost string) (r ResultList) {
ip, err := net.LookupIP(targetHost)
if err != nil {
return
}
for _, dnsbl := range dnsblList {
for _, addr := range ip {
res := Result{}
res.Blacklist = dnsbl
res.Address = addr.String()
addr := toDnsBlHostname(addr)
query(dnsbl, addr, &res)
r.Results = append(r.Results, res)
if res.Listed {
r.Listed = true
}
}
}
return
}
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