diff options
Diffstat (limited to 'middleware/pkg/dnsutil/reverse.go')
| -rw-r--r-- | middleware/pkg/dnsutil/reverse.go | 38 |
1 files changed, 33 insertions, 5 deletions
diff --git a/middleware/pkg/dnsutil/reverse.go b/middleware/pkg/dnsutil/reverse.go index a360432f3..daf9cc600 100644 --- a/middleware/pkg/dnsutil/reverse.go +++ b/middleware/pkg/dnsutil/reverse.go @@ -1,6 +1,9 @@ package dnsutil -import "strings" +import ( + "net" + "strings" +) // ExtractAddressFromReverse turns a standard PTR reverse record name // into an IP address. This works for ipv4 or ipv6. @@ -10,26 +13,51 @@ import "strings" func ExtractAddressFromReverse(reverseName string) string { search := "" + f := reverse + switch { case strings.HasSuffix(reverseName, v4arpaSuffix): search = strings.TrimSuffix(reverseName, v4arpaSuffix) case strings.HasSuffix(reverseName, v6arpaSuffix): search = strings.TrimSuffix(reverseName, v6arpaSuffix) + f = reverse6 default: return "" } // Reverse the segments and then combine them. - segments := reverse(strings.Split(search, ".")) - return strings.Join(segments, ".") + return f(strings.Split(search, ".")) } -func reverse(slice []string) []string { +func reverse(slice []string) string { for i := 0; i < len(slice)/2; i++ { j := len(slice) - i - 1 slice[i], slice[j] = slice[j], slice[i] } - return slice + ip := net.ParseIP(strings.Join(slice, ".")).To4() + if ip == nil { + return "" + } + return ip.String() +} + +// reverse6 reverse the segments and combine them according to RFC3596: +// b.a.9.8.7.6.5.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2 +// is reversed to 2001:db8::567:89ab +func reverse6(slice []string) string { + for i := 0; i < len(slice)/2; i++ { + j := len(slice) - i - 1 + slice[i], slice[j] = slice[j], slice[i] + } + slice6 := []string{} + for i := 0; i < len(slice)/4; i++ { + slice6 = append(slice6, strings.Join(slice[i*4:i*4+4], "")) + } + ip := net.ParseIP(strings.Join(slice6, ":")).To16() + if ip == nil { + return "" + } + return ip.String() } const ( |