AdGuardHome/internal/aghnet/addr.go

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package aghnet
import (
"fmt"
"net"
"strconv"
"strings"
"github.com/AdguardTeam/AdGuardHome/internal/agherr"
"golang.org/x/net/idna"
)
// IsValidHostOuterRune returns true if r is a valid initial or final rune for
// a hostname label.
func IsValidHostOuterRune(r rune) (ok bool) {
return (r >= 'a' && r <= 'z') ||
(r >= 'A' && r <= 'Z') ||
(r >= '0' && r <= '9')
}
// isValidHostRune returns true if r is a valid rune for a hostname label.
func isValidHostRune(r rune) (ok bool) {
return r == '-' || IsValidHostOuterRune(r)
}
// ValidateHardwareAddress returns an error if hwa is not a valid EUI-48,
// EUI-64, or 20-octet InfiniBand link-layer address.
func ValidateHardwareAddress(hwa net.HardwareAddr) (err error) {
defer agherr.Annotate("validating hardware address %q: %w", &err, hwa)
switch l := len(hwa); l {
case 0:
return agherr.Error("address is empty")
case 6, 8, 20:
return nil
default:
return fmt.Errorf("bad len: %d", l)
}
}
// maxDomainLabelLen is the maximum allowed length of a domain name label
// according to RFC 1035.
const maxDomainLabelLen = 63
// maxDomainNameLen is the maximum allowed length of a full domain name
// according to RFC 1035.
//
// See https://stackoverflow.com/a/32294443/1892060.
const maxDomainNameLen = 253
// ValidateDomainNameLabel returns an error if label is not a valid label of
// a domain name.
func ValidateDomainNameLabel(label string) (err error) {
defer agherr.Annotate("validating label %q: %w", &err, label)
l := len(label)
if l > maxDomainLabelLen {
return fmt.Errorf("label is too long, max: %d", maxDomainLabelLen)
} else if l == 0 {
return agherr.Error("label is empty")
}
if r := label[0]; !IsValidHostOuterRune(rune(r)) {
return fmt.Errorf("invalid char %q at index %d", r, 0)
} else if l == 1 {
return nil
}
for i, r := range label[1 : l-1] {
if !isValidHostRune(r) {
return fmt.Errorf("invalid char %q at index %d", r, i+1)
}
}
if r := label[l-1]; !IsValidHostOuterRune(rune(r)) {
return fmt.Errorf("invalid char %q at index %d", r, l-1)
}
return nil
}
// ValidateDomainName validates the domain name in accordance to RFC 952, RFC
// 1035, and with RFC-1123's inclusion of digits at the start of the host. It
// doesn't validate against two or more hyphens to allow punycode and
// internationalized domains.
//
// TODO(a.garipov): After making sure that this works correctly, port this into
// module golibs.
func ValidateDomainName(name string) (err error) {
defer agherr.Annotate("validating domain name %q: %w", &err, name)
name, err = idna.ToASCII(name)
if err != nil {
return err
}
l := len(name)
if l == 0 {
return agherr.Error("domain name is empty")
} else if l > maxDomainNameLen {
return fmt.Errorf("too long, max: %d", maxDomainNameLen)
}
labels := strings.Split(name, ".")
for i, l := range labels {
err = ValidateDomainNameLabel(l)
if err != nil {
return fmt.Errorf("invalid domain name label at index %d: %w", i, err)
}
}
return nil
}
// The maximum lengths of generated hostnames for different IP versions.
const (
ipv4HostnameMaxLen = len("192-168-100-10-")
ipv6HostnameMaxLen = len("ff80-f076-0000-0000-0000-0000-0000-0010")
)
// generateIPv4Hostname generates the hostname for specific IP version.
func generateIPv4Hostname(ipv4 net.IP) (hostname string) {
hnData := make([]byte, 0, ipv4HostnameMaxLen)
for i, part := range ipv4 {
if i > 0 {
hnData = append(hnData, '-')
}
hnData = strconv.AppendUint(hnData, uint64(part), 10)
}
return string(hnData)
}
// generateIPv6Hostname generates the hostname for specific IP version.
func generateIPv6Hostname(ipv6 net.IP) (hostname string) {
hnData := make([]byte, 0, ipv6HostnameMaxLen)
for i, partsNum := 0, net.IPv6len/2; i < partsNum; i++ {
if i > 0 {
hnData = append(hnData, '-')
}
for _, val := range ipv6[i*2 : i*2+2] {
if val < 10 {
hnData = append(hnData, '0')
}
hnData = strconv.AppendUint(hnData, uint64(val), 16)
}
}
return string(hnData)
}
// GenerateHostname generates the hostname from ip. In case of using IPv4 the
// result should be like:
//
// 192-168-10-1
//
// In case of using IPv6, the result is like:
//
// ff80-f076-0000-0000-0000-0000-0000-0010
//
func GenerateHostname(ip net.IP) (hostname string) {
if ipv4 := ip.To4(); ipv4 != nil {
return generateIPv4Hostname(ipv4)
} else if ipv6 := ip.To16(); ipv6 != nil {
return generateIPv6Hostname(ipv6)
}
return ""
}