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 const invalidCharMsg = "invalid char %q at index %d in %q" // ValidateDomainNameLabel returns an error if label is not a valid label of // a domain name. func ValidateDomainNameLabel(label string) (err error) { l := len(label) if l > maxDomainLabelLen { return fmt.Errorf("%q is too long, max: %d", label, maxDomainLabelLen) } else if l == 0 { return agherr.Error("label is empty") } if r := label[0]; !IsValidHostOuterRune(rune(r)) { return fmt.Errorf(invalidCharMsg, r, 0, label) } else if l == 1 { return nil } for i, r := range label[1 : l-1] { if !isValidHostRune(r) { return fmt.Errorf(invalidCharMsg, r, i+1, label) } } if r := label[l-1]; !IsValidHostOuterRune(rune(r)) { return fmt.Errorf(invalidCharMsg, r, l-1, label) } 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) { 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("%q is too long, max: %d", name, 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 "" }