/
ipv6_rev.go
63 lines (53 loc) · 1.35 KB
/
ipv6_rev.go
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package dn42
import (
"errors"
"fmt"
"net"
"strings"
)
const IPv6_PTR_SUFFIX = ".ip6.arpa."
func (dn42 DN42) parseIPv6Query(ip string) (string, int) {
splitted := strings.Split(ip, ".")
reverse(splitted)
ipMaskMax := 4 * len(splitted)
for len(splitted) < 32 {
splitted = append(splitted, "0")
}
result := ""
for i := 0; i < 32; i++ {
if i != 0 && i%4 == 0 {
result += ":"
}
result += splitted[i]
}
return result, ipMaskMax
}
func (dn42 DN42) parseIPv6Ptr(qname string) (*net.IP, int, error) {
if !strings.HasSuffix(qname, IPv6_PTR_SUFFIX) {
return nil, 0, errors.New("not IPv6 ptr query")
}
qname = strings.TrimSuffix(qname, IPv6_PTR_SUFFIX)
ipString, ipMask := dn42.parseIPv6Query(qname)
ip := net.ParseIP(ipString)
if ip == nil {
return nil, 0, errors.New("not IPv6 ptr query")
}
if ip.To4() != nil {
return nil, 0, errors.New("not IPv6 ptr query")
}
return &ip, ipMask, nil
}
func (dn42 DN42) findIPv6RecordFile(ip net.IP, ipMask int) (string, int, error) {
ipString := ip.String()
for i := ipMask; i >= 0; i-- {
_, cidr, err := net.ParseCIDR(fmt.Sprintf("%s/%d", ipString, i))
if err != nil {
return "", 0, err
}
cidrFilename := strings.ReplaceAll(cidr.String(), "/", "_")
if dn42.fileExists("inet6num", cidrFilename) {
return cidrFilename, i, nil
}
}
return "", 0, errors.New("file for range not found")
}